Stephen T. Holgate

The health effects of air pollution have been subject to intense study in recent years. Exposure to pollutants such as airborne particulate matter and ozone has been associated with increases in mortality and hospital admissions due to respiratory and cardiovascular disease. These effects have been found in short-term studies, which relate day-to-day variations in air pollution and health, and long-term studies, which have followed cohorts of exposed individuals over time. Effects have been seen at very low levels of exposure, and it is unclear whether a threshold concentration exists for particulate matter and ozone below which no effects on health are likely. In this review, we discuss the evidence for adverse effects on health of selected air pollutants.

Reproducible science requires transparent reporting. The ARRIVE guidelines (Animal Research: Reporting of In Vivo Experiments) were originally developed in 2010 to improve the reporting of animal research. They consist of a checklist of information to include in publications describing in vivo experiments to enable others to scrutinise the work adequately, evaluate its methodological rigour, and reproduce the methods and results. Despite considerable levels of endorsement by funders and journals over the years, adherence to the guidelines has been inconsistent, and the anticipated improvements in the quality of reporting in animal research publications have not been achieved. Here, we introduce ARRIVE 2.0. The guidelines have been updated and information reorganised to facilitate their use in practice. We used a Delphi exercise to prioritise and divide the items of the guidelines into 2 sets, the "ARRIVE Essential 10," which constitutes the minimum requirement, and the "Recommended Set," which describes the research context. This division facilitates improved reporting of animal research by supporting a stepwise approach to implementation. This helps journal editors and reviewers verify that the most important items are being reported in manuscripts. We have also developed the accompanying Explanation and Elaboration (E&E) document, which serves (1) to explain the rationale behind each item in the guidelines, (2) to clarify key concepts, and (3) to provide illustrative examples. We aim, through these changes, to help ensure that researchers, reviewers, and journal editors are better equipped to improve the rigour and transparency of the scientific process and thus reproducibility.

Reproducible science requires transparent reporting. The ARRIVE guidelines (Animal Research: Reporting of In Vivo Experiments) were originally developed in 2010 to improve the reporting of animal research. They consist of a checklist of information to include in publications describing in vivo experiments to enable others to scrutinise the work adequately, evaluate its methodological rigour, and reproduce the methods and results. Despite considerable levels of endorsement by funders and journals over the years, adherence to the guidelines has been inconsistent, and the anticipated improvements in the quality of reporting in animal research publications have not been achieved. Here, we introduce ARRIVE 2.0. The guidelines have been updated and information reorganised to facilitate their use in practice. We used a Delphi exercise to prioritise and divide the items of the guidelines into 2 sets, the "ARRIVE Essential 10," which constitutes the minimum requirement, and the "Recommended Set," which describes the research context. This division facilitates improved reporting of animal research by supporting a stepwise approach to implementation. This helps journal editors and reviewers verify that the most important items are being reported in manuscripts. We have also developed the accompanying Explanation and Elaboration document, which serves (1) to explain the rationale behind each item in the guidelines, (2) to clarify key concepts, and (3) to provide illustrative examples. We aim, through these changes, to help ensure that researchers, reviewers, and journal editors are better equipped to improve the rigour and transparency of the scientific process and thus reproducibility.

Interleukin-5 (IL-5) is essential for the formation of eosinophils, which are thought to have a major role in the pathogenesis of asthma and other allergic diseases. We aimed to assess the effects of monoclonal antibody to IL-5 on blood and sputum eosinophils, airway hyper-responsiveness, and the late asthmatic reaction to inhaled allergen in patients with mild asthma.We did a double-blind randomised placebo-controlled trial, in which a single intravenous infusion of humanised (IgG-K) monoclonal antibody to IL-5 (SB-240563) was given at doses of 2.5 mg/kg (n=8) or 10.0 mg/kg (n=8). The effects of treatment on responses to inhaled allergen challenge, sputum eosinophils, and airway hyper-responsiveness to histamine were measured at weeks 1 and 4 with monitoring of blood eosinophil counts for up to 16 weeks.Monoclonal antibody against IL-5 lowered the mean blood eosinophil count at day 29 from 0.25x10(9)/L (95% CI 0.16-0.34) in the placebo group to 0.04x10(9)/L (0.00-0.07) in the 10 mg/kg group (p<0.0001), and prevented the blood eosinophilia that follows allergen challenge. After inhaled allergen challenge, 9 days after treatment, the percentage sputum eosinophils were 12.2% in the placebo group and lowered to 0.9% (-1.2 to 3.0; p=0.0076) in the 10 mg/kg group, and this effect persisted at day 30 after the dose. There was no significant effect of monoclonal antibody to IL-5 on the late asthmatic response or on airway hyper-responsiveness to histamine.A single dose of monoclonal antibody to IL-5 decreased blood eosinophils for up to 16 weeks and sputum eosinophils at 4 weeks, which has considerable therapeutic potential for asthma and allergy. However, our findings question the role of eosinophils in mediating the late asthmatic response and causing airway hyper-responsiveness.

Children with asthma commonly have positive skin tests for inhaled allergens, and in the United Kingdom the majority of older children with asthma are sensitized to the house-dust mite. In a cohort of British children at risk for allergic disease because of family history, we investigated prospectively from 1978 to 1989 the relation between exposure to the house-dust mite allergen (Der p I) and the development of sensitization and asthma.Of the 67 children studied in 1989, 35 were atopic (positive skin tests), and 32 were nonatopic. Of the 17 with active asthma, 16 were atopic (P less than 0.005), all of whom were sensitized to the house-dust mite, as judged by positive skin tests and levels of specific IgE antibodies (P less than 0.001). For house-dust samples collected from the homes of 59 of the children in 1979 and from 65 homes in 1989, the geometric means for the highest Der p I exposure were, respectively, 16.1 and 16.8 micrograms per gram of sieved dust. There was a trend toward an increasing degree of sensitization at the age of 11 with greater exposure at the age of 1 (P = 0.062). All but one of the children with asthma at the age of 11 had been exposed at 1 year of age to more than 10 micrograms of Der p I per gram of dust; for this exposure, the relative risk of asthma was 4.8 (P = 0.05). The age at which the first episode of wheezing occurred was inversely related to the level of exposure at the age of 1 for all children (P = 0.015), but especially for the atopic children (r = -0.66, P = 0.001).In addition to genetic factors, exposure in early childhood to house-dust mite allergens is an important determinant of the subsequent development of asthma.

Improving the reproducibility of biomedical research is a major challenge. Transparent and accurate reporting is vital to this process; it allows readers to assess the reliability of the findings and repeat or build upon the work of other researchers. The ARRIVE guidelines (Animal Research: Reporting In Vivo Experiments) were developed in 2010 to help authors and journals identify the minimum information necessary to report in publications describing in vivo experiments. Despite widespread endorsement by the scientific community, the impact of ARRIVE on the transparency of reporting in animal research publications has been limited. We have revised the ARRIVE guidelines to update them and facilitate their use in practice. The revised guidelines are published alongside this paper. This explanation and elaboration document was developed as part of the revision. It provides further information about each of the 21 items in ARRIVE 2.0, including the rationale and supporting evidence for their inclusion in the guidelines, elaboration of details to report, and examples of good reporting from the published literature. This document also covers advice and best practice in the design and conduct of animal studies to support researchers in improving standards from the start of the experimental design process through to publication.

Over the past decade, it has become increasingly recognized that airways inflammation is one of the major components of asthma. Until recently, measurements of bronchial responsiveness and mediators of allergic reactions were the only methods of studying pathogenetic mechanisms in asthma. With improved diagnostic procedures such as fiberoptic bronchoscopy, it has become possible to investigate these mechanisms and the resulting inflammatory changes in situ. BAL has highlighted the presence of mast cells and eosinophils and has given proof of their mediator participation in airways inflammation and hyperresponsiveness. Endobronchial biopsies have so far yielded results that are similar to those obtained from postmortem studies, although it appears that there are varying degrees of inflammation in living asthmatics. Even in mild disease, the histopathologic features of bronchial asthma are consistent with chronic inflammation. Indirect evidence obtained from allergen challenge leading to increased bronchial hyperresponsiveness during LAR, and direct evidence of inflammatory cells and their mediators in the airway mucosa and lumen after allergen challenge argue for an active role of cells in bringing about inflammatory changes. At present, however, it is not possible to relate precisely the findings obtained by bronchoscopy to the clinical presentation and progression of asthma. Cell activation with production of potent mediators of inflammation may be more relevant to inflammation than the simple presence of these cells in the airways. Almost all the inflammatory cells present in the bronchial wall and lumen have been implicated in the pathogenesis of mucosal inflammation in asthma, but with our current state of knowledge, none can be singled out as the most important contributor. The mast cell was the first to be investigated in depth, and despite the accumulation of large amounts of data concerning its ultrastructure and function, it remains uncertain to what extent this cell is involved in inflammatory responses. Thus, while its main role appears to be that of initiator of allergen-induced responses, the eosinophil has attracted more attention as a proinflammatory cell rather than as an antiinflammatory cell with a capacity to be selectively recruited from the circulation in response to IgE-dependent signals. The eosinophil secretes potent mediators that cause damage to the bronchial epithelium and lead to bronchoconstriction. The role of other cells is at present not as well defined.(ABSTRACT TRUNCATED AT 400 WORDS)

Asthma and eosinophilic bronchitis are characterized by similar inflammatory infiltrates in the submucosa of the lower airway. However, eosinophilic bronchitis differs from asthma in that there is no variable airflow obstruction or airway hyperresponsiveness in the former condition. We tested the hypothesis that there were differences between the two conditions in the microlocalization of mast cells within the airway smooth muscle.

Rhinoviruses are the major trigger of acute asthma exacerbations and asthmatic subjects are more susceptible to these infections. To investigate the underlying mechanisms of this increased susceptibility, we examined virus replication and innate responses to rhinovirus (RV)-16 infection of primary bronchial epithelial cells from asthmatic and healthy control subjects. Viral RNA expression and late virus release into supernatant was increased 50- and 7-fold, respectively in asthmatic cells compared with healthy controls. Virus infection induced late cell lysis in asthmatic cells but not in normal cells. Examination of the early cellular response to infection revealed impairment of virus induced caspase 3/7 activity and of apoptotic responses in the asthmatic cultures. Inhibition of apoptosis in normal cultures resulted in enhanced viral yield, comparable to that seen in infected asthmatic cultures. Examination of early innate immune responses revealed profound impairment of virus-induced interferon-beta mRNA expression in asthmatic cultures and they produced >2.5 times less interferon-beta protein. In infected asthmatic cells, exogenous interferon-beta induced apoptosis and reduced virus replication, demonstrating a causal link between deficient interferon-beta, impaired apoptosis and increased virus replication. These data suggest a novel use for type I interferons in the treatment or prevention of virus-induced asthma exacerbations.

Several epidemiologic studies have demonstrated a consistent association between levels of particulate matter (PM) in the ambient air with increases in cardiovascular and respiratory mortality and morbidity. Diesel exhaust (DE), in addition to generating other pollutants, is a major contributor to PM pollution in most places in the world. Although the epidemiologic evidence is strong, there are as yet no established biological mechanisms to explain the toxicity of PM in humans. To determine the impact of DE on human airways, we exposed 15 healthy human volunteers to air and diluted DE under controlled conditions for 1 h with intermittent exercise. Lung functions were measured before and after each exposure. Blood sampling and bronchoscopy were performed 6 h after each exposure to obtain airway lavages and endobronchial biopsies. While standard lung function measures did not change following DE exposure, there was a significant increase in neutrophils and B lymphocytes in airway lavage, along with increases in histamine and fibronectin. The bronchial biopsies obtained 6 h after DE exposure showed a significant increase in neutrophils, mast cells, CD4 + and CD8 + T lymphocytes along with upregulation of the endothelial adhesion molecules ICAM-1 and VCAM-1, with increases in the numbers of LFA-1 + cells in the bronchial tissue. Significant increases in neutrophils and platelets were observed in peripheral blood following DE exposure. This study demonstrates that at high ambient concentrations, acute short-term DE exposure produces a well-defined and marked systemic and pulmonary inflammatory response in healthy human volunteers, which is underestimated by standard lung function measurements.

Asthma is characterized by the presence of an inflammatory cell infiltrate in the bronchial mucosa consisting of activated mast cells, eosinophils, and T cells. Several cytokines are considered to play a pivotal role in this response, particularly interleukin (IL)-4, IL-5, IL-6, and tumor necrosis factor-alpha (TNF-alpha). In this study, we have used immunohistochemistry applied to thin glycol methacrylate sections of bronchial mucosal biopsies to define the cellular provenance of these cytokines in normal and asthmatic airways. Both the asthmatic and normal mucosa contained numerous cells staining positively for all four cytokines, with the majority identified as mast cells by their tryptase content. Eosinophils also accounted for some IL-5 immunostaining in the asthmatic biopsies. By using two monoclonal antibodies directed to different epitopes of IL-4, we provide tentative evidence for enhanced IL-4 secretion in asthma. Similarly, a sevenfold increase in the number of mast cells staining for TNF-alpha in the asthmatic biopsies suggests that this cytokine is also up-regulated in this disease. These findings clearly identify human mast cells as a source of IL-4, IL-5, IL-6, and TNF-alpha and add to the view that, along with T cells, mast cells may play an important role in initiating and maintaining the inflammatory response in asthma.

Nitric oxide (NO) is a mediator of vasodilatation and bronchodilatation synthesised from L-arginine by the enzyme NO synthase, which is either constitutive or induced by lipopolysaccharides and/or cytokines. The presence and function of NO synthase in normal or diseased lung is not yet clear. Asthma is characterised by bronchial hyperresponsiveness, epithelial damage, inflammation, and increased cytokine production. To investigate the presence of NO synthase in asthma, we immunostained bronchial biopsies from non-steroid-treated people with asthma and non-asthmatic controls with specific polyvalent antisera to purified inducible NO synthase and to a selected peptide sequence of the same enzyme. Immunoreactivity was seen in the epithelium and some inflammatory cells in 22 of 23 biopsies from people with asthma, but in only 2 of 20 controls. To assess the relation of cytokines to NO synthase induction, bronchial epithelial cells in culture were stimulated with tumour necrosis factor (TNF alpha). Inducible enzyme immunoreactivity was found only in the treated cells. The existence of inducible NO synthase in human lungs suggests that increased production of NO, probably induced by cytokines, may be relevant to the pathology of asthma.

Asthma and chronic obstructive pulmonary disease (COPD) are two prevalent chronic airway diseases that have a high personal and social impact. They likely represent a continuum of different diseases that may share biological mechanisms (i.e. endotypes), and present similar clinical, functional, imaging and/or biological features that can be observed (i.e. phenotypes) which require individualised treatment. Precision medicine is defined as "treatments targeted to the needs of individual patients on the basis of genetic, biomarker, phenotypic, or psychosocial characteristics that distinguish a given patient from other patients with similar clinical presentations". In this Perspective, we propose a precision medicine strategy for chronic airway diseases in general, and asthma and COPD in particular.

While asthma is considered an inflammatory disorder of the conducting airways, it is becoming increasingly apparent that the disease is heterogeneous with respect to immunopathology, clinical phenotypes, response to therapies, and natural history. Once considered purely an allergic disorder dominated by Th2-type lymphocytes, IgE, mast cells, eosinophils, macrophages, and cytokines, the disease also involves local epithelial, mesenchymal, vascular and neurologic events that are involved in directing the Th2 phenotype to the lung and through aberrant injury-repair mechanisms to remodeling of the airway wall. Structural cells provide the necessary "soil" upon which the "seeds" of the inflammatory response are able to take root and maintain a chronic phenotype and upon which are superimposed acute and subacute episodes usually driven by environmental factors such as exposure to allergens, microorganisms, pollutants or caused by inadequate antiinflammatory treatment. Greater consideration of additional immunologic and inflammatory pathways are revealing new ways of intervening in the prevention and treatment of the disease. Thus increased focus on environmental factors beyond allergic exposure (such as virus infection, air pollution, and diet) are identifying targets in structural as well as immune and inflammatory cells at which to direct new interventions.

Asthma is a global health problem affecting around 300 million individuals of all ages, ethnic groups and countries. It is estimated that around 250,000 people die prematurely each year as a result of asthma. Concepts of asthma severity and control are important in evaluating patients and their response to treatment, as well as for public health, registries, and research (clinical trials, epidemiologic, genetic, and mechanistic studies), but the terminology applied is not standardized, and terms are often used interchangeably. A common international approach is favored to define severe asthma, uncontrolled asthma, and when the 2 coincide, although adaptation may be required in accordance with local conditions. A World Health Organization meeting was convened April 5-6, 2009, to propose a uniform definition of severe asthma. An article was written by a group of experts and reviewed by the Global Alliance against Chronic Respiratory Diseases review group. Severe asthma is defined by the level of current clinical control and risks as "Uncontrolled asthma which can result in risk of frequent severe exacerbations (or death) and/or adverse reactions to medications and/or chronic morbidity (including impaired lung function or reduced lung growth in children)." Severe asthma includes 3 groups, each carrying different public health messages and challenges: (1) untreated severe asthma, (2) difficult-to-treat severe asthma, and (3) treatment-resistant severe asthma. The last group includes asthma for which control is not achieved despite the highest level of recommended treatment and asthma for which control can be maintained only with the highest level of recommended treatment.

A thickened bronchial epithelial basement membrane has long been regarded as a histopathologic characteristic of bronchial asthma. As we had previously demonstrated that this phenomenon is due to the deposition of interstitial collagens and fibronectin, we have now sought to determine the nature of the cell responsible for this process by studying endobronchial biopsies from eight normal and seven asthmatic volunteers by immunohistochemistry and electron microscopy. Biopsies were stained with PR 2D3, a monoclonal antibody to myofibroblasts of the pericrypt sheath of the colon and a monoclonal antibody to alpha-smooth muscle actin. The thickness of the subepithelial collagen and the organelle content of the cells therein were determined by electron microscopy.The subepithelial collagen thickness in the normal subjects ranged from 2.16 to 6.26 µm, while that in the asthmatic subjects ranged from 3.75 to 11.1 µm (Mann-Whitney test; P = 0.05). Elongated cells in the collagen layer were identified by staining with PR 2D3. As this antibody also stains smooth muscle, consecutive frozen sections were stained for alpha-smooth muscle actin and the number of positive cells per millimeter of basement membrane was subtracted from the count for PR 2D3. This yielded a count of 4.9 to 9.4 cells/mm in the normal subjects and 11.9 to 20.6 cells/mm in the asthmatics (P = 0.001). There was a highly significant correlation between the depth of subepithelial collagen and the number of PR 2D3-positive, alpha-smooth muscle actin-positive cells (Spearman rank correlation; r = 0.764 and P = 0.006). Electron microscopy confirmed the myofibroblastic nature of these cells. We propose that bronchial myofibroblasts are responsible for the characteristic subepithelial fibrosis seen in allergic asthma.

The effect of inhaled corticosteroid therapy on airway mucosal inflammation was investigated in 10 symptomatic atopic asthmatic patients treated with inhaled albuterol and whose disease severity required preventative antiinflammatory treatment. Endobronchial biopsies were obtained by fiberoptic bronchoscopy before and after 6 wk of therapy with inhaled beclomethasone dipropionate (2,000 µg/day for 2 wk followed by 1,000 µg/day for 4 wk). Following treatment, there was a significant increase in mean morning peak expiratory flow (p < 0.05) and baseline FEV1 measured on the day of methacholine challenge (p < 0.05) and a decrease in asthma symptoms (p < 0.01), peak expiratory flow variation (p < 0.05), and albuterol usage (p < 0.05). This was accompanied by a sevenfold decrease in airway responsiveness (p = 0.001). The clinical improvement in asthma was associated with a significant (p < 0.05) reduction in epithelial and mucosal mast cells and eosinophils and submucosal T lymphocytes, but electron microscopy did not identify any changes in the extent of mast cell and eosinophil degranulation following treatment. Because of the association between the decrease in inflammatory cell numbers and the improvement in all the measured clinical and physiologic indices of asthma, we suggest that the beneficial effect of inhaled corticosteroids in asthma may be attributed to their antiinflammatory action in the bronchial mucosa.

Reproducible science requires transparent reporting. The ARRIVE guidelines (Animal Research: Reporting of In Vivo Experiments) were originally developed in 2010 to improve the reporting of animal research. They consist of a checklist of information to include in publications describing in vivo experiments to enable others to scrutinise the work adequately, evaluate its methodological rigour, and reproduce the methods and results. Despite considerable levels of endorsement by funders and journals over the years, adherence to the guidelines has been inconsistent, and the anticipated improvements in the quality of reporting in animal research publications have not been achieved. Here, we introduce ARRIVE 2.0. The guidelines have been updated and information reorganised to facilitate their use in practice. We used a Delphi exercise to prioritise and divide the items of the guidelines into 2 sets, the "ARRIVE Essential 10," which constitutes the minimum requirement, and the "Recommended Set," which describes the research context. This division facilitates improved reporting of animal research by supporting a stepwise approach to implementation. This helps journal editors and reviewers verify that the most important items are being reported in manuscripts. We have also developed the accompanying Explanation and Elaboration document, which serves (1) to explain the rationale behind each item in the guidelines, (2) to clarify key concepts, and (3) to provide illustrative examples. We aim, through these changes, to help ensure that researchers, reviewers, and journal editors are better equipped to improve the rigour and transparency of the scientific process and thus reproducibility.

Allergic diseases have reached epidemic proportions worldwide. An understanding of the cellular and soluble mediators that are involved in allergic inflammatory responses not only helps in understanding the mechanisms of current treatments, but is also important for the identification of new targets that are amenable to both small-molecule and biological interventions. There is now considerable optimism with regards to tackling the allergy epidemic in light of improvements in systemic and mucosal allergen-specific immunotherapy, the identification of key cytokines and their receptors that drive T-helper-2-cell polarization, a clearer understanding of the pathways of leukocyte recruitment and the signalling pathways that are involved in cell activation and mediator secretion, and new approaches to vaccine development.

IgE plays an important role in allergic asthma. We hypothesized that reducing IgE in the airway mucosa would reduce airway inflammation. Forty-five patients with mild to moderate persistent asthma with sputum eosinophilia of 2% or more were treated with humanized monoclonal antibody against IgE (omalizumab) (n = 22) or placebo (n = 23) for 16 weeks. Outcomes included inflammatory cells in induced sputum and bronchial biopsies, and methacholine responsiveness. Treatment with omalizumab resulted in marked reduction of serum IgE and a reduction of IgE+ cells in the airway mucosa. The mean percentage sputum eosinophil count decreased significantly (p < 0.001) from 6.6 to 1.7% in the omalizumab group, a reduction significantly (p = 0.05) greater than with placebo (8.5 to 7.0%). This was associated with a significant reduction in tissue eosinophils; cells positive for the high-affinity Fc receptor for IgE; CD3+, CD4+, and CD8+ T lymphocytes; B lymphocytes; and cells staining for interleukin-4, but not with improvement in airway hyperresponsiveness to methacholine. This study shows antiinflammatory effects of omalizumab treatment and provides clues for mechanisms whereby omalizumab reduces asthma exacerbations and other asthma outcomes in more severe asthma. The lack of effect of omalizumab on methacholine responsiveness suggests that IgE or eosinophils may not be causally linked to airway hyperresponsiveness to methacholine in mild to moderate asthma.

Summary Therapists regularly perform various measurements. How reliable these measurements are in themselves, and how reliable therapists are in using them, is clearly essential knowledge to help clinicians decide whether or not a particular measurement is of any value. The aim of this paper is to explain the nature of reliability, and to describe some of the commonly used estimates that attempt to quantify it. An understanding of reliability, and how it is estimated, will help therapists to make sense of their own clinical findings, and to interpret published studies. Although reliability is generally perceived as desirable, there is no firm definition as to the level of reliability required to reach clinical acceptability. As with hypothesis testing, statistically significant levels of reliability may not translate into clinically acceptable levels, so that some authors' claims about reliability may need to be interpreted with caution. Reliability is generally population specific, so that caution is also advised in making comparisons between studies. The current consensus is that no single estimate is sufficient to provide the full picture about reliability, and that different types of estimate should be used together. Therapists regularly perform various measurements. How reliable these measurements are in themselves, and how reliable therapists are in using them, is clearly essential knowledge to help clinicians decide whether or not a particular measurement is of any value. The aim of this paper is to explain the nature of reliability, and to describe some of the commonly used estimates that attempt to quantify it. An understanding of reliability, and how it is estimated, will help therapists to make sense of their own clinical findings, and to interpret published studies. Although reliability is generally perceived as desirable, there is no firm definition as to the level of reliability required to reach clinical acceptability. As with hypothesis testing, statistically significant levels of reliability may not translate into clinically acceptable levels, so that some authors' claims about reliability may need to be interpreted with caution. Reliability is generally population specific, so that caution is also advised in making comparisons between studies. The current consensus is that no single estimate is sufficient to provide the full picture about reliability, and that different types of estimate should be used together.

IL-17 signaling has been implicated in development and persistence of asthma. Cytokine-targeted strategies blocking IL-17 receptor signaling may be beneficial in asthma treatment.To determine efficacy and safety of brodalumab, a human anti-IL-17 receptor A monoclonal antibody, in subjects with inadequately controlled moderate to severe asthma taking regular inhaled corticosteroids.Three hundred two subjects were randomized to brodalumab (140, 210, or 280 mg) or placebo. Primary endpoint was change in Asthma Control Questionnaire (ACQ) score from baseline to Week 12. Secondary endpoints included FEV1, symptom scores, and symptom-free days. Prespecified subgroup analyses were conducted to identify potential responsive subpopulations. Analyses included randomized subjects receiving one or more doses of investigational product using last-observation-carried-forward imputation.Demographics and baseline characteristics were generally balanced among groups (n = 302; n = 226 brodalumab). For the overall study population, no treatment differences were observed. Nine prespecified subgroups were examined without corrections for multiple testing. In only the high-reversibility subgroup (post-bronchodilator FEV1 improvement ≥ 20%; n = 112) was an ACQ change with nominal significance noted; ACQ responses were nominally significant in the 210-mg group (estimated treatment difference, 0.53) but not significant in the higher 280-mg group (estimated treatment difference, 0.38). Adverse events, generally balanced among groups, were most commonly asthma, upper respiratory tract infection, and injection site reaction.Inhibition of IL-17 receptor A did not produce a treatment effect in subjects with asthma. The results of the high-reversibility subgroup analysis are of uncertain significance, requiring further study of brodalumab in this asthma subpopulation. Clinical trial registered with www.clinicaltrials.gov (NCT01199289).

We have shown that viruses are associated with 80 to 85% of asthma exacerbations in school-age children in the community. We hypothesize that viral infections are also associated with severe attacks of asthma precipitating hospital admissions. To investigate this, we conducted a time-trend analysis, comparing the seasonal patterns of respiratory infections and hospital admissions for asthma in adults and children. During a 1-yr study in the Southampton area of the United Kingdom, 108 school-age children monitored upper and lower respiratory symptoms and took peak expiratory flow rate (PEFR) recordings. From children reporting a symptomatic episode or a decrease in PEFR, samples were taken for detection of viruses and atypical bacteria. A total of 232 respiratory viruses and four atypical bacteria were detected. The half-monthly rates of upper respiratory infection were compared with the half-monthly rates for hospital admissions for asthma (International Classification of Diseases [ICD] code 493) for the same time period for the hospitals serving the areas from which the cohort of schoolchildren was drawn. The relationships of upper respiratory infections and hospital admissions for asthma with school attendance were studied. Strong correlations were found between the seasonal patterns of upper respiratory infections and hospital admissions for asthma (r = 0.72; p < 0.0001). This relationship was stronger for pediatric (r = 0.68; p < 0.0001) than for adult admissions (r = 0.53; p < 0.01). Upper respiratory infections and admissions for asthma were more frequent during periods of school attendance (87% of pediatric and 84% of total admissions), than during school holiday periods (p < 0.001). These relationships remained significant when allowance was made for linear trend and seasonal variation using multiple regression analysis (p < 0.01). Not surprisingly, school attendance, because it is a major factor in respiratory virus transmission, was found to be a major confounding variable in children. This study demonstrates that upper respiratory viral infections are strongly associated in time with hospital admissions for asthma in children and adults. Rhinoviruses were the major pathogen implicated, and the majority of viral infections and asthma admissions occurred during school attendance.

The major function of the respiratory epithelium was once thought to be that of a physical barrier. However, it constitutes the interface between the internal milieu and the external environment as well as being a primary target for inhaled respiratory drugs. It also responds to changes in the external environment by secreting a large number of molecules and mediators that signal to cells of the immune system and underlying mesenchyme. Thus, the epithelium is in a unique position to translate gene-environment interactions. Normally, the epithelium has a tremendous capacity to repair itself following injury. However, evidence is rapidly accumulating to show that the airway epithelium of asthmatics is abnormal and has increased susceptibility to injury compared to normal epithelium. Areas of detachment and fragility are a characteristic feature not observed in other inflammatory diseases such as COPD. In addition to being more susceptible to damage, normal repair processes are also compromised. Failure of appropriate growth and differentiation of airway epithelial cells will cause persistent mucosal injury. The response to traditional therapy such as glucocorticoids may also be compromised. However, whether the differences observed in asthmatic epithelium are a cause of or secondary to the development of the disease remains unanswered. Strategies to address this question include careful examination of the ontogeny of the disease in children and use of gene array technology should provide some important answers, as well as allow a better understanding of the critical role that the epithelium plays under normal conditions and in diseases such as asthma.

BackgroundAsthma is a complex disease involving gene and environment interactions. Although atopy is a strong predisposing risk factor for asthma, local tissue susceptibilities are required for disease expression. The bronchial epithelium forms the interface with the external environment and is pivotally involved in controlling tissue homeostasis through provision of a physical barrier controlled by tight junction (TJ) complexes.ObjectivesTo explain the link between environment exposures and airway vulnerability, we hypothesized that epithelial TJs are abnormal in asthma, leading to increased susceptibility to environmental agents.MethodsLocalization of TJs in bronchial biopsies and differentiated epithelial cultures was assessed by electron microscopy or immunostaining. Baseline permeability and the effect of cigarette smoke and growth factor were assessed by measurement of transepithelial electrical resistance and passage of fluorescently labeled dextrans.ResultsBy using immunostaining, we found that bronchial biopsies from asthmatic subjects displayed patchy disruption of TJs. In differentiated bronchial epithelial cultures, TJ formation and transepithelial electrical resistance were significantly lower (P < .05) in cultures from asthmatic donors (n = 43) than from normal controls (n = 40) and inversely correlated with macromolecular permeability. Cultures from asthmatic donors were also more sensitive to disruption by cigarette smoke extract. Epidermal growth factor enhanced basal TJ formation in cultures from asthmatic subjects (P < .01) and protected against cigarette smoke–induced barrier disruption (P < .01).ConclusionsOur results show that the bronchial epithelial barrier in asthma is compromised. This defect may facilitate the passage of allergens and other agents into the airway tissue, leading to immune activation and may thus contribute to the end organ expression of asthma. Asthma is a complex disease involving gene and environment interactions. Although atopy is a strong predisposing risk factor for asthma, local tissue susceptibilities are required for disease expression. The bronchial epithelium forms the interface with the external environment and is pivotally involved in controlling tissue homeostasis through provision of a physical barrier controlled by tight junction (TJ) complexes. To explain the link between environment exposures and airway vulnerability, we hypothesized that epithelial TJs are abnormal in asthma, leading to increased susceptibility to environmental agents. Localization of TJs in bronchial biopsies and differentiated epithelial cultures was assessed by electron microscopy or immunostaining. Baseline permeability and the effect of cigarette smoke and growth factor were assessed by measurement of transepithelial electrical resistance and passage of fluorescently labeled dextrans. By using immunostaining, we found that bronchial biopsies from asthmatic subjects displayed patchy disruption of TJs. In differentiated bronchial epithelial cultures, TJ formation and transepithelial electrical resistance were significantly lower (P < .05) in cultures from asthmatic donors (n = 43) than from normal controls (n = 40) and inversely correlated with macromolecular permeability. Cultures from asthmatic donors were also more sensitive to disruption by cigarette smoke extract. Epidermal growth factor enhanced basal TJ formation in cultures from asthmatic subjects (P < .01) and protected against cigarette smoke–induced barrier disruption (P < .01). Our results show that the bronchial epithelial barrier in asthma is compromised. This defect may facilitate the passage of allergens and other agents into the airway tissue, leading to immune activation and may thus contribute to the end organ expression of asthma.

Aspirin causes bronchoconstriction in aspirin-intolerant asthma (AIA) patients by triggering cysteinyl-leukotriene (cys-LT) production, probably by removing PGE2-dependent inhibition. To investigate why aspirin does not cause bronchoconstriction in all individuals, we immunostained enzymes of the leukotriene and prostanoid pathways in bronchial biopsies from AIA patients, aspirin-tolerant asthma (ATA) patients, and normal (N) subjects. Counts of cells expressing the terminal enzyme for cys-LT synthesis, LTC4 synthase, were fivefold higher in AIA biopsies (11.5+/-2.2 cells/mm2, n = 10) than in ATA biopsies (2.2+/-0.7, n = 10; P = 0. 0006) and 18-fold higher than in N biopsies (0.6+/-0.4, n = 9; P = 0. 0002). Immunostaining for 5-lipoxygenase, its activating protein (FLAP), LTA4 hydrolase, cyclooxygenase (COX)-1, and COX-2 did not differ. Enhanced baseline cys-LT levels in bronchoalveolar lavage (BAL) fluid of AIA patients correlated uniquely with bronchial counts of LTC4 synthase+ cells (rho = 0.83, P = 0.01). Lysine-aspirin challenge released additional cys-LTs into BAL fluid in AIA patients (200+/-120 pg/ml, n = 8) but not in ATA patients (0. 7+/-5.1, n = 5; P = 0.007). Bronchial responsiveness to lysine-aspirin correlated exclusively with LTC4 synthase+ cell counts (rho = -0.63, P = 0.049, n = 10). Aspirin may remove PGE2-dependent suppression in all subjects, but only in AIA patients does increased bronchial expression of LTC4 synthase allow marked overproduction of cys-LTs leading to bronchoconstriction.

Rhinovirus infections cause exacerbations of asthma. We postulated that people with asthma are more susceptible to rhinovirus infection than people without the disease and compared the susceptibility of these groups.We recruited 76 cohabiting couples. One person in every couple had atopic asthma and one was healthy. Participants completed daily diary cards of upper-respiratory-tract (URT) and lower-respiratory-tract (LRT) symptoms and measured peak expiratory flow twice daily. Every 2 weeks nasal aspirates were taken and examined for rhinovirus. Mixed models were used to compare risks of infection between groups. We also compared the severity and duration of infections.We analysed 753 samples. Rhinovirus was detected in 10.1% (38/378) of samples from participants with asthma and 8.5% (32/375) of samples from healthy participants. After adjustment for confounding factors, asthma did not significantly increase risk of infection (odds ratio 1.15, 95% CI 0.71-1.87). Groups did not differ in frequency, severity, or duration of URT infections or symptoms associated with rhinovirus infection. First rhinovirus infection was associated more frequently with LRT infection in participants with asthma than in healthy individuals (12 of 28 infections vs four of 23, respectively, p=0.051). Symptoms of LRT associated with rhinovirus infection were significantly more severe (p=0.001) and longer-lasting in participants with asthma than in healthy participants (p=0.005).People with atopic asthma are not at greater risk of rhinovirus infection than healthy individuals but suffer from more frequent LRT infections and have more severe and longer-lasting LRT symptoms.

There is compelling evidence that human mast cells contribute to the pathophysiology of asthma. Mast cells, but not T cells or eosinophils, localize within the bronchial smooth muscle bundles in patients with asthma but not in normal subjects or those with eosinophilic bronchitis, a factor likely to be important in determining the asthmatic phenotype. The mechanism of mast cell recruitment by asthmatic airway smooth muscle involves the CXCL10/CXCR3 axis, and several mast cell mediators have profound effects on airway smooth muscle function. The autacoids are established as potent bronchoconstrictors, whereas the proteases tryptase and chymase are being demonstrated to have a range of actions consistent with key roles in inflammation, tissue remodeling, and bronchial hyperresponsiveness. IL-4 and IL-13, known mast cell products, also induce bronchial hyperresponsiveness in the mouse independent of the inflammatory response and enhance the magnitude of agonist-induced intracellular Ca2+ responses in cultured human airway smooth muscle. There are therefore many pathways by which the close approximation of mast cells with airway smooth muscle cells might lead to disordered airway smooth muscle function. Mast cells also infiltrate the airway mucous glands in subjects with asthma, showing features of degranulation, and a positive correlation with the degree of mucus obstructing the airway lumen, suggesting that mast cells play an important role in regulating mucous gland secretion. The development of potent and specific inhibitors of mast cell secretion, which remain active when administered long-term to asthmatic airways, should offer a novel approach to the treatment of asthma. There is compelling evidence that human mast cells contribute to the pathophysiology of asthma. Mast cells, but not T cells or eosinophils, localize within the bronchial smooth muscle bundles in patients with asthma but not in normal subjects or those with eosinophilic bronchitis, a factor likely to be important in determining the asthmatic phenotype. The mechanism of mast cell recruitment by asthmatic airway smooth muscle involves the CXCL10/CXCR3 axis, and several mast cell mediators have profound effects on airway smooth muscle function. The autacoids are established as potent bronchoconstrictors, whereas the proteases tryptase and chymase are being demonstrated to have a range of actions consistent with key roles in inflammation, tissue remodeling, and bronchial hyperresponsiveness. IL-4 and IL-13, known mast cell products, also induce bronchial hyperresponsiveness in the mouse independent of the inflammatory response and enhance the magnitude of agonist-induced intracellular Ca2+ responses in cultured human airway smooth muscle. There are therefore many pathways by which the close approximation of mast cells with airway smooth muscle cells might lead to disordered airway smooth muscle function. Mast cells also infiltrate the airway mucous glands in subjects with asthma, showing features of degranulation, and a positive correlation with the degree of mucus obstructing the airway lumen, suggesting that mast cells play an important role in regulating mucous gland secretion. The development of potent and specific inhibitors of mast cell secretion, which remain active when administered long-term to asthmatic airways, should offer a novel approach to the treatment of asthma. Mast cells are resident in all normal tissues, where they are believed to play an important role in tissue homeostasis, wound healing, and host defense, particularly bacterial infection (see review1Bradding P. Holgate S.T. Immunopathology and human mast cell cytokines.Crit Rev Oncol Haematol. 1999; 31: 119-133Abstract Full Text Full Text PDF PubMed Scopus (105) Google Scholar). Chronic mast cell activation contributes to the pathophysiology of many diverse diseases through the synthesis and release of numerous proinflammatory mediators and cytokines, the pattern of which varies depending on the stimulus.2Okumura S. Kashiwakura J. Tomita H. Matsumoto K. Nakajima T. Saito H. et al.Identification of specific gene expression profiles in human mast cells mediated by Toll-like receptor 4 and FcεRI.Blood. 2003; 102: 2547-2554Crossref PubMed Scopus (136) Google Scholar It is beyond our scope to review in detail all of the evidence implicating mast cells in the pathophysiology of asthma, and for further information, the reader is referred to references.3Bradding P. Mast cells in asthma.in: Busse W.W. Holgate S.T. Asthma & rhinitis. Blackwell Scientific Publications, Inc, Boston2000: 319-338Google Scholar, 4Bradding P. The role of the mast cell in asthma: a reassessment.Curr Opin Allergy Clin Immunol. 2003; 3: 45-50Crossref PubMed Scopus (75) Google Scholar We therefore focus on important recent advances in this field. Mast cells secrete the autacoid mediators histamine, prostaglandin (PG) D2, and leukotriene (LT) C4, which are capable of inducing bronchoconstriction, mucus secretion, and mucosal edema, all features of asthma. This is particularly evident during experimental allergen challenge, in which blockade of these mediators attenuates the early fall in lung function (see review3Bradding P. Mast cells in asthma.in: Busse W.W. Holgate S.T. Asthma & rhinitis. Blackwell Scientific Publications, Inc, Boston2000: 319-338Google Scholar). However, mast cells also synthesize and secrete a large number of proinflammatory cytokines (including IL-4, IL-5, and IL-13), which regulate both IgE synthesis and the development of eosinophilic inflammation, and several profibrogenic cytokines, including TGF-β and basic fibroblast growth factor (FGF-2).1Bradding P. Holgate S.T. Immunopathology and human mast cell cytokines.Crit Rev Oncol Haematol. 1999; 31: 119-133Abstract Full Text Full Text PDF PubMed Scopus (105) Google Scholar, 3Bradding P. Mast cells in asthma.in: Busse W.W. Holgate S.T. Asthma & rhinitis. Blackwell Scientific Publications, Inc, Boston2000: 319-338Google Scholar The serine proteases tryptase, chymase, and carboxy-peptidase are major secretory products of human mast cells that can interact with various cell types via protease activated receptors (PARs) and by other processes to alter their behavior profoundly.3Bradding P. Mast cells in asthma.in: Busse W.W. Holgate S.T. Asthma & rhinitis. Blackwell Scientific Publications, Inc, Boston2000: 319-338Google Scholar Importantly, bronchial mucosal mast cells in subjects with asthma exhibit features of chronic ongoing activation3Bradding P. Mast cells in asthma.in: Busse W.W. Holgate S.T. Asthma & rhinitis. Blackwell Scientific Publications, Inc, Boston2000: 319-338Google Scholar (Fig 1). Although most of these studies have been performed in atopic individuals, similar evidence has been obtained to support a role for ongoing mast cell secretory activity in both nonatopic and occupational asthma.3Bradding P. Mast cells in asthma.in: Busse W.W. Holgate S.T. Asthma & rhinitis. Blackwell Scientific Publications, Inc, Boston2000: 319-338Google Scholar Although, in general, total mast cell numbers appear not to be increased in the bronchial mucosa of subjects with asthma compared with normal subjects, this inadequately describes the complexity, because it is evident that they localize to 3 key sites: the airway smooth muscle (ASM), the airway mucous glands, and the bronchial epithelium. It is a widely held view that the disordered airway physiology and airway wall remodeling characteristic of asthma are consequences of the inflammatory process, but there are examples where this relationship is weak. This is most evident in patients with eosinophilic bronchitis (EB), a condition that accounts for about 15% of cases of cough referred to respiratory specialists. It is characterized by corticosteroid responsive cough and the presence of a sputum eosinophilia occurring in the absence of variable airflow obstruction or bronchial hyperresponsiveness (BHR).5Brightling C.E. Ward R. Goh K.L. Wardlaw A.J. Pavord I.D. Eosinophilic bronchitis is an important cause of chronic cough.Am J Respir Crit Care Med. 1999; 160: 406-410Crossref PubMed Scopus (375) Google Scholar However, despite differing functional effects on the airways, the immunopathology of asthma and EB is virtually identical.6Brightling C.E. Symon F.A. Birring S.S. Bradding P. Pavord I.D. Wardlaw A.J. TH2 cytokine expression in bronchoalveolar lavage fluid T lymphocytes and bronchial submucosa is a feature of asthma and eosinophilic bronchitis.J Allergy Clin Immunol. 2002; 110: 899-905Abstract Full Text Full Text PDF PubMed Scopus (194) Google Scholar, 7Brightling C.E. Symon F.A. Birring S.S. Bradding P. Wardlaw A.J. Pavord I.D. Comparison of airway immunopathology of eosinophilic bronchitis and asthma.Thorax. 2003; 58: 528-532Crossref PubMed Scopus (202) Google Scholar Thus, in bronchoalveolar lavage, induced sputum, and airway biopsies, the extent of T-cell and eosinophil infiltration and activation, mucosal mast cell numbers, IL-4 and IL-5 cytokine expression, epithelial integrity, subbasement membrane collagen deposition, and mediator concentrations including histamine and PGD2 are almost identical. This leads us to the conclusion that many of the immunopathological features previously attributed to causing asthma may not, in fact, be fundamental to the development of airflow obstruction and BHR. After a series of in-depth studies we have found only 2 key differences between the pathology of asthma and eosinophilic bronchitis. The first is that the concentration of IL-13 is elevated in the induced sputum of subjects with asthma but not subjects with EB.8Berry M.A. Parker D. Neale N. Woodman L. Morgan A. Monk P. et al.Sputum and bronchial submucosal IL-13 expression in asthma and eosinophilic bronchitis.J Allergy Clin Immunol. 2004; 114: 1106-1109Abstract Full Text Full Text PDF PubMed Scopus (140) Google Scholar The numbers of IL-13+ cells in the airway mucosa in asthma is relatively low but increased when compared with EB, with most of the IL-13+ cells identified as eosinophils. However, the most striking difference between the pathology of asthma and EB is in the ASM. Abnormal ASM function is fundamentally important to the pathophysiology of asthma and yet, surprisingly, this compartment has not been the focus of detailed immunopathological assessments. In subjects with asthma, we have observed that there are many mast cells between the ASM bundles, but virtually none in the ASM from patients with EB or normal subjects (Fig 2).9Brightling C.E. Bradding P. Symon F.A. Holgate S.T. Wardlaw A.J. Pavord I.D. Mast cell infiltration of airway smooth muscle in asthma.N Engl J Med. 2002; 346: 1699-1705Crossref PubMed Scopus (1020) Google Scholar This has been confirmed in a further independent study.10El-Shazly A. Berger P. Girodet P.O. Ousova O. Fayon M. Vernejoux J.M. et al.Fraktalkine produced by airway smooth muscle cells contributes to mast cell recruitment in asthma.J Immunol. 2006; 176: 1860-1868PubMed Google Scholar The majority of mast cells in the ASM were of the MCTC phenotype—that is, containing both tryptase and chymase—and also expressed IL-4 and IL-13, but interestingly, not IL-5 (Fig 2).11Brightling C.E. Symon F.A. Holgate S.T. Wardlaw A.J. Pavord I.D. Bradding P. IL-4 and IL-13 are co-localised to mast cells within airway smooth muscle in asthma.Clin Exp Allergy. 2003; 33: 1711-1716Crossref PubMed Scopus (123) Google Scholar In contrast, in asthmatic biopsies there were almost no T cells or eosinophils in the ASM of any of the study groups. This indicates that ASM infiltration by mast cells may be one of the critical determinants of the asthmatic phenotype, and could explain the observed correlation between ASM mast cell numbers and BHR within the asthmatic group. These observations have further implications. For example, not only might it clarify why many atopic patients do not have asthma but also it could explain why the presence of asthma is such a strong risk factor for death from anaphylaxis and allergen desensitization.12Bock S.A. Munoz-Furlong A. Sampson H.A. Fatalities due to anaphylactic reactions to foods.J Allergy Clin Immunol. 2001; 107: 191-193Abstract Full Text PDF PubMed Scopus (1354) Google Scholar In many instances, it is likely that cellular communication within the airways works across a distance of 1 to 2 μm and that cell-cell contact is critical to influence function. The localization of mast cells within the ASM in asthma will facilitate specific interactions between these cells and ASM in terms of both localized mediator release and direct cell-cell contact. Therefore, it is entirely plausible that the presence of mast cells within the ASM could contribute to the development of ASM hypertrophy and hyperplasia, smooth muscle dysfunction expressed as BHR, and variable airflow obstruction. It is reasonable to hypothesize that the primary stimulus for mast cell recruitment lies within the ASM involving the release of chemoattractants for mast cells or their progenitors. The ASM secretes many chemokines and growth factors that exhibit mast cell chemotactic activity. These include CCL11, CXCL8, and CXCL12. We have demonstrated that human lung mast cells (HLMCs) express CXCR3,13Brightling C.E. Kaur D. Berger P. Morgan A.J. Wardlaw A.J. Bradding P. Differential expression of CCR3 and CXCR3 by human lung and bone marrow-derived mast cells: implications for tissue mast cell migration.J Leuk Biol. 2005; 77: 759-766Crossref PubMed Scopus (82) Google Scholar and ASM secretes the 3 CXCR3 ligands CXCL9, CXCL10, and CXCL11.14Brightling C.E. Ammit A.J. Kaur D. Black J.L. Wardlaw A.J. Hughes J.M. et al.The CXCL10/CXCR3 axis mediates human lung mast cell migration to asthmatic airway smooth muscle.Am J Respir Crit Care Med. 2005; 171: 1103-1108Crossref PubMed Scopus (233) Google Scholar Of importance, cultured human ASM from subjects with asthma preferentially secrete CXCL10 after cytokine activation, and this accounts in large part for the greatly enhanced HLMC chemotaxis mediated by conditioned medium from asthmatic compared with normal ASM.14Brightling C.E. Ammit A.J. Kaur D. Black J.L. Wardlaw A.J. Hughes J.M. et al.The CXCL10/CXCR3 axis mediates human lung mast cell migration to asthmatic airway smooth muscle.Am J Respir Crit Care Med. 2005; 171: 1103-1108Crossref PubMed Scopus (233) Google Scholar The relevance of this to mast cell recruitment by the asthmatic ASM in vivo is further demonstrated by the increased expression of CXCL10 by the ASM in bronchial biopsies from subjects with asthma compared with normal subjects, and by the enrichment of CXCR3+ mast cells within the ASM bundles compared with the surrounding airway mucosa.14Brightling C.E. Ammit A.J. Kaur D. Black J.L. Wardlaw A.J. Hughes J.M. et al.The CXCL10/CXCR3 axis mediates human lung mast cell migration to asthmatic airway smooth muscle.Am J Respir Crit Care Med. 2005; 171: 1103-1108Crossref PubMed Scopus (233) Google Scholar Other chemoattractants may also contribute to the ASM mast cell myositis. Stem cell factor (SCF; c-kit ligand) is produced by both ASM and mast cells and is both a chemoattractant and an essential survival factor for mast cells. In addition, TGF-β is another mast cell chemoattractant released by ASM after exposure to tryptase, providing a mechanism through which mast cells might contribute to further mast cell recruitment15Berger P. Girodet P.O. Begueret H. Ousova O. Perng D.W. Marthan R. et al.Tryptase-stimulated human airway smooth muscle cells induce cytokine synthesis and mast cell chemotaxis.FASEB J. 2003; 17: 2139-2141Crossref PubMed Scopus (139) Google Scholar via autocrine pathways. Once present in the ASM bundle, adhesion of mast cells to ASM cells is likely to be important for the retention of mast cells and the functional interaction between the 2 cell types. This hypothesis is supported by the observation that unlike T cells and eosinophils, which adhere poorly to ASM, HLMCs adhere readily.16Yang W. Kaur D. Okayama Y. Ito A. Wardlaw A.J. Brightling C.E. et al.Human lung mast cells adhere to human airway smooth muscle, in part, via tumor suppressor in lung cancer-1.J Immunol. 2006; 176: 1238-1243PubMed Google Scholar Interestingly, this is mediated in part via a molecule known as tumor suppressor in lung cancer 1 (TSLC-1; also known as SgIGSF, IGSF4, RA175, Necl2, and SynCAM). Tumor suppressor in lung cancer 1 is highly expressed by HLMC and mediates HLMC adhesion to ASM through a heterophilic Ca2+-independent mechanism. The classic mast cell autacoid mediators histamine, PGD2, and LTC4 are all potent agonists for ASM contraction. Exogenously administered tryp tase induces bronchoconstriction and BHR in dogs and sheep,17Sekizawa K. Caughey G.H. Lazarus S.C. Gold W.M. Nadel J.A. Mast cell tryptase causes airway smooth muscle hyperresponsiveness in dogs.J Clin Invest. 1989; 83: 175-179Crossref PubMed Scopus (140) Google Scholar and in vitro, tryptase can potentiate the contractile response of sensitized bronchi to histamine.18Berger P. Compton S.J. Molimard M. Walls A.F. N'Guyen C. Marthan R. et al.Mast cell tryptase as a mediator of hyperresponsiveness in human isolated bronchi.Clin Exp Allergy. 1999; 29: 804-812Crossref PubMed Scopus (66) Google Scholar Tryptase-induced bronchoconstriction in animal models is likely to be mediated by mast cell activation because it may be blocked by pretreatment with antihistamines. Human tryptase can act as a stimulus for histamine release from mast cells from several tissues including those of the lung,19He S. Aslam A. Gaca M.D. He Y. Buckley M.G. Hollenberg M.D. et al.Inhibitors of tryptase as mast cell-stabilizing agents in the human airways: effects of tryptase and other agonists of proteinase-activated receptor 2 on histamine release.J Pharmacol Exp Ther. 2004; 309: 119-126Crossref PubMed Scopus (52) Google Scholar and consistent with this, inhibitors of this protease can be effective as mast cell stabilizing agents. In addition to its ability to stimulate cytokine release from ASM, tryptase can act as a potent mitogen in vitro.20Berger P. Perng D.W. Thabrew H. Compton S.J. Cairns J.A. McEuen A.R. et al.Tryptase and agonists of PAR-2 induce the proliferation of human airway smooth muscle cells.J Appl Physiol. 2001; 91: 1372-1379Crossref PubMed Scopus (152) Google Scholar, 21Brown J.K. Jones C.A. Rooney L.A. Caughey G.H. Hall I.P. Tryptase's potent mitogenic effects in human airway smooth muscle cells are via nonproteolytic actions.Am J Physiol Lung Cell Mol Physiol. 2002; 282: L197-L206PubMed Google Scholar The precise mechanism whereby tryptase may interact with these cells is unclear. Several studies have suggested the need for an intact catalytic site,20Berger P. Perng D.W. Thabrew H. Compton S.J. Cairns J.A. McEuen A.R. et al.Tryptase and agonists of PAR-2 induce the proliferation of human airway smooth muscle cells.J Appl Physiol. 2001; 91: 1372-1379Crossref PubMed Scopus (152) Google Scholar although there is a report that nonproteolytic actions may be involved in mitogenesis.21Brown J.K. Jones C.A. Rooney L.A. Caughey G.H. Hall I.P. Tryptase's potent mitogenic effects in human airway smooth muscle cells are via nonproteolytic actions.Am J Physiol Lung Cell Mol Physiol. 2002; 282: L197-L206PubMed Google Scholar ASMs abundantly express the G-protein–coupled receptor PAR2, peptide agonists of which can stimulate mitogenesis and cytokine release similar to that seen with tryptase.20Berger P. Perng D.W. Thabrew H. Compton S.J. Cairns J.A. McEuen A.R. et al.Tryptase and agonists of PAR-2 induce the proliferation of human airway smooth muscle cells.J Appl Physiol. 2001; 91: 1372-1379Crossref PubMed Scopus (152) Google Scholar IL-4 and IL-13 are also believed to be key in the development of BHR. This is supported by an in vivo study in mice in which instillation of TH2 cell conditioned medium to the airways of naive mice induced BHR within 6 hours. This required expression of the IL-4 receptor α subunit and signal transducer and activator of transcription 6, suggesting a critical role for IL-4 and/or IL-13, and both of these cytokines produced similar effects when administered individually.22Venkayya R. Lam M. Willkom M. Grunig G. Corry D.B. Erle D.J. The Th2 lymphocyte products IL-4 and IL-13 rapidly induce airway hyperresponsiveness through direct effects on resident airway cells.Am J Respir Cell Mol Biol. 2002; 26: 202-208Crossref PubMed Scopus (198) Google Scholar IL-4 and IL-13 and also enhance the magnitude of agonist-induced intracellular Ca2+ responses in cultured human ASM. In asthma, there are few T cells within the ASM, but mast cells at this site do express both IL-4 (Fig 2) and IL-13,11Brightling C.E. Symon F.A. Holgate S.T. Wardlaw A.J. Pavord I.D. Bradding P. IL-4 and IL-13 are co-localised to mast cells within airway smooth muscle in asthma.Clin Exp Allergy. 2003; 33: 1711-1716Crossref PubMed Scopus (123) Google Scholar revealing a further pathway through which mast cells could contribute to the development of BHR. Chymase is a chymotryptic protease of mast cells whose roles in asthma have been less extensively studied than tryptase, but it is expressed by those mast cells infiltrating the ASM in asthma.9Brightling C.E. Bradding P. Symon F.A. Holgate S.T. Wardlaw A.J. Pavord I.D. Mast cell infiltration of airway smooth muscle in asthma.N Engl J Med. 2002; 346: 1699-1705Crossref PubMed Scopus (1020) Google Scholar Interestingly, chymase degrades human ASM pericellular matrix and inhibits T-cell adhesion to ASM, which might explain the paucity of T cells within this structure in asthma.23Lazaar A.L. Plotnick M.I. Kucich U. Crichton I. Lotfi S. Das S.K.P. et al.Mast cell chymase modifies cell-matrix interactions and inhibits mitogen-induced proliferation of human airway smooth muscle cells.J Immunol. 2002; 169: 1014-1020PubMed Google Scholar Consistent with roles in tissue remodeling are the ability of chymase to process type 1 procollagen to initiate the formation of collagen fibrils, to activate matrix metalloprotease 1, and to stimulate the release of extracellular TGF-β1 (see review24Walls A.F. The roles of neutral proteases in asthma and rhinitis.in: Busse W.W. Holgate S.T. Asthma and rhinitis. Blackwell, Boston2000: 968-997Google Scholar). Further roles in controlling the bioavailability of cytokines and growth factors are suggested by the findings that chymase can convert IL-1β into the active form, degrade IL-4, and induce the release of membrane-bound SCF. Although characterized as a potent stimulus for mucus secretion, relatively little is known of the direct actions of chymase on cells, and apart from being able to inactivate PAR1, it does not seem to act on any of the PARs. The effects of combined secretion of chymase, tryptase, and other mast cell mediators in vivo remains unclear and will perhaps be best delineated in coculture experiments using intact human lung mast cells and primary cultures of asthmatic ASM cells. Mast cells infiltrate the bronchial epithelium in asthma.3Bradding P. Mast cells in asthma.in: Busse W.W. Holgate S.T. Asthma & rhinitis. Blackwell Scientific Publications, Inc, Boston2000: 319-338Google Scholar This is likely to be of importance in disease pathogenesis for 2 reasons. First, mast cells are placed at the portal of entry of noxious stimuli such as aeroallergens, which would facilitate an effector role in the ongoing immunologic response (antigen presentation, TH2 cell differentiation, IgE synthesis). Second, there are likely to be important consequences of mast cell degranulation on epithelial function. For example, mast cells adhere avidly to bronchial epithelial cells,25Sanmugalingam D. Wardlaw A.J. Bradding P. Adhesion of human lung mast cells to bronchial epithelium: evidence for a novel carbohydrate-mediated mechanism.J Leukoc Biol. 2000; 68: 38-46PubMed Google Scholar and tryptase stimulates airway epithelial IL-8 release and can upregulate intercellular adhesion molecule 1 expression.26Cairns J.A. Walls A.F. Mast cell tryptase is a mitogen for epithelial cells: stimulation of IL-8 production and intercellular adhesion molecule-1 expression.J Immunol. 1996; 156: 275-283PubMed Google Scholar At this site, mast cells could also more readily respond to other stimuli, such as hyperosmolar or inhaled adenosine. Severe mucus plugging is a well known feature of severe fatal asthma but is also recognized as a feature of milder disease, and results from mucus hypersecretion by hyperplastic submucosal glands and epithelial goblet cells. Carroll et al27Carroll N.G. Mutavdzic S. James A.L. Increased mast cells and neutrophils in submucosal mucous glands and mucus plugging in patients with asthma.Thorax. 2002; 57: 677-682Crossref PubMed Scopus (145) Google Scholar performed a detailed analysis of cartilaginous airways in postmortem lung specimens from patients with fatal asthma, patients with asthma who died from other causes (nonfatal asthma), and subjects without asthma who died of nonpulmonary causes. Immunohistochemistry for mast cell tryptase revealed a significant increase in the number of mast cells within the mucosal gland stroma in nonfatal asthma (Fig 3) and a marked increase in the number of degranulated mast cells in both fatal asthma and nonfatal asthma compared with normal controls. They established significant correlations between the density of both intact and degranulated mast cells in the within mucous glands with the degree of mucus obstruction in the airways. Taken together, these data provide some support for a role of mast cells in the development of mucous gland hyperplasia and the mucus gland secretion characteristic of asthma. Numerous mast cell products are likely to contribute to these features of asthma including histamine, PGD2, LTC4, IL-6, IL-13, TNF-α, tryptase, and chymase. A further molecule of interest and of relevance to the epithelium and mucosal glands is amphiregullin, a member of the epidermal growth factor family. Amphiregullin expression is induced in human progenitor–derived mast cells after activation through FcεRI,28Wang S.W. Oh C.K. Cho S.H. Hu G. Martin R. Demissie-Sanders S. et al.Amphiregulin expression in human mast cells and its effect on the primary human lung fibroblasts.J Allergy Clin Immunol. 2005; 115: 287-294Abstract Full Text Full Text PDF PubMed Scopus (74) Google Scholar, 29Okumura S. Sagara H. Fukuda T. Saito H. Okayama Y. FcepsilonRI-mediated amphiregulin production by human mast cells increases mucin gene expression in epithelial cells.J Allergy Clin Immunol. 2005; 115: 272-279Abstract Full Text Full Text PDF PubMed Scopus (104) Google Scholar an effect that is not suppressed by dexamethasone. Amphiregullin is expressed at increased levels by mast cells in the asthmatic bronchial mucosa, and in vitro, mast cell–derived amphiregullin increases mucin gene expression in the NCI-H292 epithelial cell line. These observations focus attention on mast cell–derived amphiregullin as contributing to epithelial goblet cell metaplasia and mucus hypersecretion in asthma, which is refractory to corticosteroids. In addition, recombinant amphiregullin induces the proliferation of human airway fibroblasts but not ASM cells, suggesting a further mechanism whereby mast cells can contribute to subepithelial fibrosis (Fig 4). TNF-α is a proinflammatory cytokine strongly implicated in the pathogenesis of asthma.30Bradding P. Roberts J.A. Britten K.M. Montefort S. Djukanovic R. Mueller R. et al.Interleukin-4, -5, and -6 and tumor necrosis factor-alpha in normal and asthmatic airways: evidence for the human mast cell as a source of these cytokines.Am J Respir Cell Mol Biol. 1994; 10: 471-480Crossref PubMed Scopus (759) Google Scholar When administered by inhalation to animals and human beings, it induces both BHR and sputum neutrophilia and exacerbates BHR in patients with asthma.31Thomas P.S. Yates D.H. Barnes P.J. Tumor necrosis factor-alpha increases airway responsiveness and sputum neutrophilia in normal human subjects.Am J Respir Crit Care Med. 1995; 152: 76-80Crossref PubMed Scopus (333) Google Scholar, 32Thomas P.S. Heywood G. Effects of inhaled tumour necrosis factor alpha in subjects with mild asthma.Thorax. 2002; 57: 774-778Crossref PubMed Scopus (128) Google Scholar TNF-α immunoreactivity is increased in the airways of patients with mild asthma, largely because of increased expression by mucosal mast cells.30Bradding P. Roberts J.A. Britten K.M. Montefort S. Djukanovic R. Mueller R. et al.Interleukin-4, -5, and -6 and tumor necrosis factor-alpha in normal and asthmatic airways: evidence for the human mast cell as a source of these cytokines.Am J Respir Cell Mol Biol. 1994; 10: 471-480Crossref PubMed Scopus (759) Google Scholar Two studies have recently shown that TNF-α expression is increased markedly in severe asthma, as shown by increased protein in bronchoalveolar lavage, increased protein expression on PBMCs, and both increased protein and a 30-fold increase in mRNA in the bronchial mucosa,33Berry M.A. Hargadon B. Shelley M. Parker D. Shaw D.E. Green R.H. et al.Evidence of a role of TNFα in refractory asthma.N Engl J Med. 2006; 354: 697-708Crossref PubMed Scopus (715) Google Scholar, 34Howarth P.H. Babu K.S. Arshad H.S. Lau L.C. Buckley M.G. McConnell W. et al.Tumour necrosis factor (TNF{alpha}) as a novel therapeutic target in symptomatic corticosteroid-dependent asthma.Thorax. 2005; 60: 1012-1018Crossref PubMed Scopus (466) Google Scholar despite patients receiving high-dose inhaled and oral corticosteroid therapy. Interestingly, the increased protein expression in endobronchial biopsies was accounted for by increased numbers of TNF-α+ mast cells.34Howarth P.H. Babu K.S. Arshad H.S. Lau L.C. Buckley M.G. McConnell W. et al.Tumour necrosis factor (TNF{alpha

Asthma is characterized pathologically by structural changes in the airway, termed airway remodeling. These changes are associated with worse long-term clinical outcomes and have been attributed to eosinophilic inflammation. In vitro studies indicate, however, that the compressive mechanical forces that arise during bronchoconstriction may induce remodeling independently of inflammation. We evaluated the influence of repeated experimentally induced bronchoconstriction on airway structural changes in patients with asthma.

Summary Background Patients with severe asthma are often inadequately controlled on existing anti‐asthma therapy, constituting an unmet clinical need. Objective This randomized, double‐blind, placebo‐controlled trial evaluated the ability of omalizumab, a humanized monoclonal anti‐IgE antibody, to improve disease control sufficiently to enable inhaled corticosteroid reduction in patients with severe allergic asthma. Methods After a run‐in period when an optimized fluticasone dose (1000 μg/day) was received for 4 weeks, patients were randomized to receive subcutaneous omalizumab [minimum 0.016 mg/kg/IgE (IU/mL) per 4 weeks; n =126] or matching placebo ( n =120) at intervals of 2 or 4 weeks. The study comprised a 16‐week add‐on phase of treatment followed by a 16‐week fluticasone‐reduction phase. Short‐/long‐acting β 2 ‐agonists were allowed as needed. Results Median reductions in fluticasone dose were significantly greater with omalizumab than placebo: 60% vs. 50% ( P =0.003). Some 73.8% and 50.8% of patients, respectively, achieved a 50% dose reduction ( P =0.001). Fluticasone dose reduction to 500 μg/day occurred in 60.3% of omalizumab recipients vs. 45.8% of placebo‐treated patients ( P =0.026). Through both phases, omalizumab reduced rescue medication requirements, improved asthma symptoms and asthma‐related quality of life compared to placebo. Conclusion Omalizumab treatment improves asthma control in severely allergic asthmatics, reducing inhaled corticosteroid requirements without worsening of symptom control or increase in rescue medication use.

Abstract Allergic mucosal inflammation is characterized by the presence of cell infiltration, predominantly with IgE-sensitized mast cells and activated eosinophils, and appears to be regulated by the local production and release of several cytokines, particularly IL-4 and IL-5. Although attention has focused on the Th2 subpopulation of CD4+ T lymphocytes as an important source of these cytokines, human mast cells have been shown to both store and secrete IL-4 and TNF-alpha. To investigate the expression of cytokines relevant to allergic inflammation and to identify their cellular localization within the nasal mucosa, we have undertaken specific immunohistochemical staining of thin sections of inferior turbinate biopsies from patients with perennial allergic rhinitis and, for comparison, from nonatopic healthy volunteers. The cytokines investigated were IL-4, IL-5, IL-6, and IL-8. In both the normal and rhinitic biopsies numerous cells immunoreactive for IL-4, IL-5, and IL-6 were seen. Staining of adjacent 2-microns sections for CD3, mast cell tryptase, and eosinophil cationic protein revealed that 90% of the IL-4 immunoreactive cells were mast cells, with biopsies from rhinitic subjects containing significantly more IL-4+ cells than biopsies from normal controls (p = 0.02), especially when assessed with the anti-IL-4 mAb 3H4. Mast cells also accounted for &amp;gt; 90% of IL-6 and &amp;gt; 50% of IL-5 immunoreactive cells. IL-5 immunoreactivity was also localized to eosinophils, whereas IL-8 localized predominantly to the nasal epithelium in both groups. No cytokines were found in association with T lymphocytes. These findings indicate that the mast cell is an important source of preformed cytokines and as such may contribute to the chronicity of the mucosal inflammation that characterizes allergic rhinitis.

During lung development, repair, and inflammation, local production of cytokines (eg, transforming growth factor-beta) and growth factors (eg, epidermal growth factor) by epithelial and mesenchymal cells mediate bidirectional growth control effectively creating an epithelial-mesenchymal trophic unit. In asthma the bronchial epithelium is highly abnormal, with structural changes involving separation of columnar cells from their basal attachments and functional changes including increased expression and release of proinflammatory cytokines, growth factors, and mediator-generating enzymes. Beneath this damaged structure there is an increase in the number of subepithelial myofibroblasts that deposit interstitial collagens causing thickening and increased density of the subepithelial basement membrane. Our recent studies suggest that the extent of epithelial damage in asthma may be the result of impaired epidermal growth factor receptor-mediated repair. In view of the close spatial relationship between the damaged epithelium and the underlying myofibroblasts, we propose that impaired epithelial repair cooperates with the T(H)2 environment to shift the set point for communication within the trophic unit. This leads to myofibroblast activation, excessive matrix deposition, and production of mediators that propagate and amplify the remodeling responses throughout the airway wall.

With more than 81 000 deaths worldwide from coronavirus disease 2019 (COVID-19) by April 8, 2020,1European Centre for Disease Prevention and ControlCOVID-19 situation update worldwide, as of 8 April 2020.https://www.ecdc.europa.eu/en/geographical-distribution-2019-ncov-casesDate accessed: April 8, 2020Google Scholar it is incumbent on researchers to accelerate clinical trials of any readily available and potentially acceptably safe therapies that could reduce the rising death toll. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) gains access to host cells via angiotensin-converting enzyme 2, which is expressed in the type II surfactant-secreting alveolar cells of the lungs.2Letko M Marzi A Munster V Functional assessment of cell entry and receptor usage for SARS-CoV-2 and other lineage B betacoronaviruses.Nat Microbiol. 2020; 5: 562-569Crossref PubMed Scopus (2049) Google Scholar Severe COVID-19 is associated with a major immune inflammatory response with abundant neutrophils, lymphocytes, macrophages, and immune mediators. Which mediators are most important in driving the immune pathology remains to be elucidated. Deaths from COVID-19 are chiefly due to diffuse alveolar damage with pulmonary oedema, hyaline membrane formation, and interstitial mononuclear inflammatory infiltrate compatible with early-phase adult respiratory distress syndrome (ARDS).3Xu Z Shi L Wang Y et al.Pathological findings of COVID-19 associated with acute respiratory distress syndrome.Lancet Respir Med. 2020; 8: 420-422Summary Full Text Full Text PDF PubMed Scopus (6346) Google Scholar Prevention of ARDS and death in patients with COVID-19 is a pressing health emergency. Anti-tumour necrosis factor (TNF) antibodies have been used for more than 20 years in severe cases of autoimmune inflammatory disease such as rheumatoid arthritis, inflammatory bowel disease, or ankylosing spondylitis. There are ten (as reported on Sept 29, 2019) US Food and Drug Administration approved and four off-label indications for anti-TNF therapy,4Gerriets V Bansal P Khaddour K Tumor necrosis factor (TNF) inhibitors. Publishing, Treasure Island, FL2020Google Scholar indicating that TNF is a valid target in many inflammatory diseases. TNF is present in blood and disease tissues of patients with COVID-195Wang L He W Yu X et al.Coronavirus disease 2019 in elderly patients: characteristics and prognostic factors based on 4-week follow-up.J Infect. 2020; (published online March 30.)DOI:10.1016/j.jinf.2020.03.019Summary Full Text Full Text PDF Scopus (833) Google Scholar and TNF is important in nearly all acute inflammatory reactions, acting as an amplifier of inflammation. We propose that anti-TNF therapy should be evaluated in patients with COVID-19 on hospital admission to prevent progression to needing intensive care support. There is evidence of an inflammatory excess in patients with COVID-19. Lung pathology in COVID-19 is characterised by capillary leakage of fluid and recruitment of immune-inflammatory lymphocytes, neutrophils, and macrophages,6Liu J Zheng X Tong Q et al.Overlapping and discrete aspects of the pathology and pathogenesis of the emerging human pathogenic coronaviruses SARS-CoV, MERS-CoV, and 2019-nCoV.J Med Virol. 2020; 92: 491-494Crossref PubMed Scopus (427) Google Scholar implying a role for adhesion molecules, chemokines, and cytokines targeting vascular endothelium. Cytokine upregulation is documented in COVID-19. In patients with COVID-19, there is upregulation of pro-inflammatory cytokines in the blood, including interleukin (IL)-1, IL-6, TNF, and interferon γ,7Huang C Wang Y Li X et al.Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China.Lancet. 2020; 395: 497-506Summary Full Text Full Text PDF PubMed Scopus (32861) Google Scholar, 8Gong J Dong H Xia Q et al.Correlation analysis between disease severity and inflammation-related parameters in patients with COVID-19 pneumonia.MedRxiv. 2020; (published online Feb 27.) (preprint).https://doi.org/10.1101/2020.02.25.20025643Google Scholar and patients in intensive care units have increased concentrations of many cytokines. Preliminary data from Salford Royal Hospital and the University of Manchester in the UK document the presence of proliferating excess monocytes expressing TNF by intracellular staining in patients with COVID-19 in intensive care (Hussell T, Grainger J, Menon M, Mann E, University of Manchester, Manchester, UK, personal communication). Available cytokine data on immunology and inflammation in COVID-19 are summarised in the appendix. Initial reports comprising a trial of 21 severe and critical COVID-19 patients in China (ChiCTR2000029765) and a case study from France9Michot JM Albiges L Chaput N et al.Tocilizumab, an anti-IL6 receptor antibody, to treat COVID-19-related respiratory failure: a case report.Ann Oncol. 2020; (published online April 2.)DOI:10.1016/j.annonc.2020.03.300Summary Full Text PDF PubMed Scopus (262) Google Scholar of clinical benefit with the anti-IL6 receptor antibody10Conti P Ronconi G Caraffa A et al.Induction of pro-inflammatory cytokines (IL-1 and IL-6) and lung inflammation by coronavirus-19 (COVI-19 or SARS-CoV-2): anti-inflammatory strategies.J Biol Regul Homeost Agents. 2020; (published online March 14.)DOI:10.23812/CONTI-EGoogle Scholar tocilizumab in COVID-19 suggest that cytokines are of importance in the "cytokine storm" and further controlled clinical trials are in progress. Although there are many potential drug candidates for reducing inflammation in COVID-19, only a few drugs such as the anti-TNF antibodies infliximab or adalimumab are potentially effective, widely available, and have a well established safety profile. The potential role of anti-TNF therapy thus warrants consideration. Preclinical studies suggest that the response to severe respiratory syncytial virus (RSV) and influenza in mice is ameliorated by anti-TNF therapy, which reduces weight loss, disease duration, and cell and fluid infiltrate.11Hussell T Pennycook A Openshaw PJ Inhibition of tumor necrosis factor reduces the severity of virus-specific lung immunopathology.Eur J Immunol. 2001; 31: 2566-2573Crossref PubMed Scopus (258) Google Scholar This research suggests a potential rationale for use of anti-TNF therapy in viral pneumonia, especially given the known mechanism of action of TNF and the reversal of TNF-induced immunopathology by TNF blockade in multiple diseases. It is known TNF is produced in most types of inflammation, especially in the acute phase, and is important in the coordination and development of the inflammatory response. However, too much production of TNF for too long becomes immune suppressive.12Clark J Vagenas P Panesar M Cope AP What does tumour necrosis factor excess do to the immune system long term?.Ann Rheum Dis. 2005; 64: iv70-iv76Crossref PubMed Scopus (82) Google Scholar Blockade of TNF alone is clinically effective in many circumstances and diseases, despite the presence of many other pro-inflammatory cytokines and mediators. There is evidence of a "TNF dependent cytokine cascade" in rheumatoid arthritis tissue and upon bacterial challenge in baboons.13Brennan FM Chantry D Jackson A Maini R Feldmann M Inhibitory effect of TNF alpha antibodies on synovial cell interleukin-1 production in rheumatoid arthritis.Lancet. 1989; 2: 244-247Summary PubMed Scopus (836) Google Scholar, 14Fong Y Tracey KJ Moldawer LL et al.Antibodies to cachectin/tumor necrosis factor reduce interleukin 1 beta and interleukin 6 appearance during lethal bacteremia.J Exp Med. 1989; 170: 1627-1633Crossref PubMed Scopus (580) Google Scholar Thus, if TNF is blocked, there is a rapid (ie, <12 h) decrease of IL-6 and IL-1 concentrations in patients with active rheumatoid arthritis15Charles P Elliott MJ Davis D et al.Regulation of cytokines, cytokine inhibitors, and acute-phase proteins following anti-TNF-alpha therapy in rheumatoid arthritis.J Immunol. 1999; 163: 1521-1528Crossref PubMed Google Scholar and, importantly, a reduction of adhesion molecules and vascular endothelial growth factor, which is also known as vascular permeability factor, denoting its importance in capillary leak.15Charles P Elliott MJ Davis D et al.Regulation of cytokines, cytokine inhibitors, and acute-phase proteins following anti-TNF-alpha therapy in rheumatoid arthritis.J Immunol. 1999; 163: 1521-1528Crossref PubMed Google Scholar, 16Paleolog EM Young S Stark AC McCloskey RV Feldmann M Maini RN Modulation of angiogenic vascular endothelial growth factor by tumor necrosis factor alpha and interleukin-1 in rheumatoid arthritis.Arthritis Rheum. 1998; 41: 1258-1265Crossref PubMed Scopus (321) Google Scholar, 17Majewska E Paleolog E Baj Z Kralisz U Feldmann M Tchorzewski H Role of tyrosine kinase enzymes in TNF-alpha and IL-1 induced expression of ICAM-1 and VCAM-1 on human umbilical vein endothelial cells.Scand J Immunol. 1997; 45: 385-392Crossref PubMed Scopus (37) Google Scholar, 18Feldmann M Maini RN Anti-TNF alpha therapy of rheumatoid arthritis: what have we learned?.Annu Rev Immunol. 2001; 19: 163-196Crossref PubMed Scopus (1175) Google Scholar, 19Dvorak HF Brown LF Detmar M Dvorak AM Vascular permeability factor/vascular endothelial growth factor, microvascular hyperpermeability, and angiogenesis.Am J Pathol. 1995; 146: 1029-1039PubMed Google Scholar Furthermore, a reduction in leucocyte trafficking occurs in inflamed tissues of joints due to reduction in adhesion molecules and chemokines20Taylor PC Peters AM Paleolog E et al.Reduction of chemokine levels and leukocyte traffic to joints by tumor necrosis factor alpha blockade in patients with rheumatoid arthritis.Arthritis Rheum. 2000; 43: 38-47Crossref PubMed Scopus (374) Google Scholar with reduction in cell content and exudate. Finally, after anti-TNF infusion tissue TNF is reduced as it passes into the blood bound to the anti-TNF antibody. Blood concentrations of immunoreactive, but biologically inactive, TNF increase more than ten times after infusion.15Charles P Elliott MJ Davis D et al.Regulation of cytokines, cytokine inhibitors, and acute-phase proteins following anti-TNF-alpha therapy in rheumatoid arthritis.J Immunol. 1999; 163: 1521-1528Crossref PubMed Google Scholar For these reasons it is possible that a single infusion of anti-TNF antibody might reduce some of the processes that occur during COVID-19 lung inflammation, reducing TNF and other inflammatory mediators, cellularity, and exudate. What would be the best time for intervention with anti-TNF therapy in patients with COVID-19? We postulate that the earlier the better after hospital admission might be the answer because patients will already have initiated anti-viral immunity for several days. There is a balance to be struck between stage of intervention and ensuring patients are at sufficient risk of a poor outcome and can be appropriately monitored. We propose that initial assessment of anti-TNF therapy in clinical trials should be in patients with moderate disease admitted to hospital and who require oxygen support but not intensive care. If this treatment approach proved beneficial with a good safety profile, treatment in the community for people identified as being at high risk of progressing to hospital admission might be considered. The range of available formulations and administration routes of anti-TNF products could facilitate this treatment approach. Is there a trade-off between immunity and virus clearance? The use of powerful anti-inflammatory drugs in acute viral diseases has to be approached with caution because of the risk of increasing viral replication or bacterial infections. For lung viral infections, the higher the infectious dose, the greater the tissue damage from viral replication and the ensuing immune response. In animal models that resemble lung viral infection in humans, the immune response to the virus is so great that even a moderate reduction in inflammation is beneficial—eg, mice with severe pneumonia from RSV or influenza benefit from anti-TNF treatment without compromising viral clearance11Hussell T Pennycook A Openshaw PJ Inhibition of tumor necrosis factor reduces the severity of virus-specific lung immunopathology.Eur J Immunol. 2001; 31: 2566-2573Crossref PubMed Scopus (258) Google Scholar because more of the lung architecture is preserved. However, concerns about safety are important when considering new therapy. Would anti-TNF therapy increase the risk of bacterial or fungal super-infections? After respiratory viral infection, superinfections with other organisms occur at the most severe end of the disease spectrum. Many research groups have elucidated the mechanisms responsible21McCullers JA The co-pathogenesis of influenza viruses with bacteria in the lung.Nat Rev Microbiol. 2014; 12: 252-262Crossref PubMed Scopus (487) Google Scholar and anecdotal evidence suggests that bacteria might have a role in in COVID-19,5Wang L He W Yu X et al.Coronavirus disease 2019 in elderly patients: characteristics and prognostic factors based on 4-week follow-up.J Infect. 2020; (published online March 30.)DOI:10.1016/j.jinf.2020.03.019Summary Full Text Full Text PDF Scopus (833) Google Scholar, 22Collins J COVID-19 pneumonia. MRI Online.https://mrionline.com/diagnosis/covid-19-pneumoniaDate: 2020Date accessed: April 8, 2020Google Scholar although this remains to be confirmed. Bacteria gain a foothold faster in a lung that is damaged. Experimental studies suggest that if the duration of inflammation is limited, with its associated collateral lung damage, then bacterial superinfection is reduced.23Goulding J Godlee A Vekaria S Hilty M Snelgrove R Hussell T Lowering the threshold of lung innate immune cell activation alters susceptibility to secondary bacterial superinfection.J Infect Dis. 2011; 204: 1086-1094Crossref PubMed Scopus (96) Google Scholar There is concern that anti-TNF therapy might increase the risk of bacterial infection.24Galloway JB Hyrich KL Mercer LK Dixon WG et al.Anti-TNF therapy is associated with an increased risk of serious infections in patients with rheumatoid arthritis especially in the first 6 months of treatment: updated results from the British Society for Rheumatology Biologics Register with special emphasis on risks in the elderly.Rheumatology (Oxford). 2011; 50: 124-131Crossref PubMed Scopus (548) Google Scholar Yet two randomised studies in critically unwell patients with septic shock25Abraham E Wunderink R Silverman H et al.Efficacy and safety of monoclonal antibody to human tumor necrosis factor alpha in patients with sepsis syndrome. A randomized, controlled, double-blind, multicenter clinical trial. TNF-alpha MAb Sepsis Study Group.JAMA. 1995; 273: 934-941Crossref PubMed Scopus (801) Google Scholar, 26Cohen J Carlet J INTERSEPT: an international, multicenter, placebo-controlled trial of monoclonal antibody to human tumor necrosis factor-alpha in patients with sepsis. International Sepsis Trial Study Group.Crit Care Med. 1996; 24: 1431-1440Crossref PubMed Scopus (442) Google Scholar showed that monoclonal anti-TNF therapy had good safety data with no evidence of increased secondary bacterial infections in the anti-TNF treated group. In an observational trial in rheumatoid arthritis patients with serious infections, the risk of sepsis and death was reduced in patients on TNF inhibitors compared with those on synthetic disease-modifying anti-rheumatic drugs (DMARDS).27Richter A Listing J Schneider M et al.Impact of treatment with biologic DMARDs on the risk of sepsis or mortality after serious infection in patients with rheumatoid arthritis.Ann Rheum Dis. 2016; 75: 1667-1673Crossref PubMed Scopus (77) Google Scholar 46 (11%) of 399 patients on TNF inhibitors developed sepsis after serious infection, of whom 20 (43%) died, compared with 74 (17%) of 444 patients on DMARDS who developed sepsis, of whom 54 (74%) died.27Richter A Listing J Schneider M et al.Impact of treatment with biologic DMARDs on the risk of sepsis or mortality after serious infection in patients with rheumatoid arthritis.Ann Rheum Dis. 2016; 75: 1667-1673Crossref PubMed Scopus (77) Google Scholar Paradoxically, another class of TNF inhibitor, a TNF-R2 Ig-Fc fusion protein, etanercept, was associated with moderately increased mortality in a randomised trial of this treatment for sepsis,28Fisher Jr., CJ Agosti JM Opal SM et al.Treatment of septic shock with the tumor necrosis factor receptor:Fc fusion protein. The Soluble TNF Receptor Sepsis Study Group.N Engl J Med. 1996; 334: 1697-1702Crossref PubMed Scopus (1086) Google Scholar possibly due to its faster off-rate for TNF potentially resulting in some redistribution and bioavailability of pathogenic TNF rather than its clearance. There has been interest as to whether the safety of anti-TNF therapy in patients with COVID-19 might be gleaned from analysis of the course of COVID-19 in patients with inflammatory bowel disease (IBD) or rheumatoid arthritis who are already on anti-TNF treatment. As of April 6, 2020, on SECURE-IBD, a coronavirus and IBD reporting database with a register of outcomes of IBD patients with COVID-19, there were 116 patients on anti-TNF therapy alone, 99 of whom recovered without hospitalisation and one patient died. By contrast, about half of 71 patients on sulfasalazine/mesalamine recovered without hospital admission and six patients died. Thus IBD patients with COVID-19 on anti-TNF therapy do not fare worse than those treated with other drugs, but there are insufficient data to make conclusions about a better outcome. We believe there is sufficient evidence to support clinical trials of anti-TNF therapy in patients with COVID-19. With an average of 2 days between hospital admission and ARDS,7Huang C Wang Y Li X et al.Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China.Lancet. 2020; 395: 497-506Summary Full Text Full Text PDF PubMed Scopus (32861) Google Scholar we propose anti-TNF therapy should be initiated as early as is practicable. If there is preliminary evidence of benefit and safety of anti-TNF therapy in hospitalised patients, we suggest consideration should be given to out of hospital treatment for patients with COVID-19 at high risk, such as older people and those with pre-existing conditions, and who can be monitored appropriately. MF and RNM have held patents, now expired, on use of infliximab and methotrexate in inflammatory arthritis and have received royalties from Johnson and Johnson, AbbVie, Amgen, and UCB, none of which are for respiratory or critical care. The financial assets of the Kennedy Trust for Rheumatology Research were largely derived from patent royalties on anti-TNF antibodies. JNW is a General Partner at Laterell Venture Partners, a role unrelated to the topic of this Comment. STH is Non-Executive Board Director (NED) and a shareholder of Synairgen. Synairgen is conducting a clinical trial of inhaled IFN β in COVID-19 patients, but this is unrelated to this Comment. STH has played no direct role in the Synairgen trial other than his role as a NED. STH has no direct interests in anti-TNF or any other therapeutics referred to in this Comment. GW receives directors fees that include options to shares as Founder and Director of Bicycle Therapeutics plc unrelated to the topic of this Comment and was a Founder of Cambridge Antibody Technology, which in the 1990s co-developed the anti-TNF antibody adalimumab, and pre-2003 advised Peptech and Domantis on their anti-TNF developments and patents. GW is a Trustee of the Kennedy Trust for Rheumatology Research, for which the financial assets were largely derived from patent royalties on anti-TNF antibodies. DR reports personal fees for consultancy on drug safety from GlaxoSmithKline unrelated to the topic of this Comment. MR and TH declare no competing interests. We thank Fiona McCann and Claudia Monaco from the Kennedy Institute, University of Oxford, for help in collating data, finding references, preparing the appendix, and other support in preparing this Comment. Download .pdf (.11 MB) Help with pdf files Supplementary appendix Prevention of the cytokine storm in COVID-19The Comment by Marc Feldman and colleagues,1 published recently in The Lancet, discussed the potential of anti-tumor necrosis factor (TNF) therapy to inhibit development of a cytokine storm in patients with coronavirus disease 2019 (COVID-19). Following this Comment, I write to propose that the opioid, meptazinol, might be a possible alternative or addition to anti-TNF therapy, particularly in the UK, where meptazinol is a licensed drug (current licenced supplier Almirall, Barcelona, Spain) and thus could be easily prescribed. Full-Text PDF

Abstract Reproducible science requires transparent reporting. The ARRIVE guidelines (Animal Research: Reporting of In Vivo Experiments) were originally developed in 2010 to improve the reporting of animal research. They consist of a checklist of information to include in publications describing in vivo experiments to enable others to scrutinise the work adequately, evaluate its methodological rigour, and reproduce the methods and results. Despite considerable levels of endorsement by funders and journals over the years, adherence to the guidelines has been inconsistent, and the anticipated improvements in the quality of reporting in animal research publications have not been achieved. Here, we introduce ARRIVE 2.0. The guidelines have been updated and information reorganised to facilitate their use in practice. We used a Delphi exercise to prioritise and divide the items of the guidelines into 2 sets, the ‘ARRIVE Essential 10,’ which constitutes the minimum requirement, and the ‘Recommended Set,’ which describes the research context. This division facilitates improved reporting of animal research by supporting a stepwise approach to implementation. This helps journal editors and reviewers verify that the most important items are being reported in manuscripts. We have also developed the accompanying Explanation and Elaboration document, which serves (1) to explain the rationale behind each item in the guidelines, (2) to clarify key concepts, and (3) to provide illustrative examples. We aim, through these changes, to help ensure that researchers, reviewers, and journal editors are better equipped to improve the rigour and transparency of the scientific process and thus reproducibility.

Continuing Medical Education examinationCONTINUING MEDICAL EDUCATION ARTICLE Credit can now be obtained, free for a limited time, by reading the following review. Please note the instructions listed below. Method of Physician Participation in Learning Process: The core material for this activity can be read in this issue of the Journal or online at the JACI Web site: www.mosby.com/jaci . The accompanying test may only be submitted online at www.mosby.com/jaci . Fax or other copies will not be accepted. Date of Original Release: February 2003. Credit may be obtained for this course until January 31, 2004. Copyright Statement: Copyright © 2003-2004. All rights reserved. List of Design Committee Members: Authors: Donna E. Davies, James Wicks, Robert M. Powell, Sarah M. Puddicomb, Stephen T. Holgate Overall Purpose/Goal: To provide excellent reviews on key aspects of allergic disease to those who research, treat, or manage allergic disease. Target Audience: Physicians and researchers within the field of allergic disease. Activity Objectives (a) To understand the structural changes that occur in asthmatic airways. (b) To appreciate the importance of gene-environment interactions and the early life origins of asthma. (c) To recognize potential mechanisms of airway wall remodeling. Accreditation/Provider Statements and Credit Designation: The American Academy of Allergy, Asthma and Immunology (AAAAI) is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians. The AAAAI designates this educational activity for up to 1.0 hour in category I credit toward the AMA Physician's Recognition Award. Each physician should claim only those hours of credit he or she actually spent in the educational activity. Recognition of Commercial Support: This activity has not received external commercial support.

Although asthma is an inflammatory disorder of the conducting airways involving T(H)2-type T cells, there is increasing evidence for an important role played by the epithelium in orchestrating the inflammatory response by interacting with multiple environmental factors to produce a chronic wound scenario involving tissue injury and aberrant repair. Part of this abnormal response is the consequence of impaired barrier function caused by a primary disruption of epithelial tight junctions that allows inhaled substances to pass more easily into the airway wall to interact with immune and inflammatory cells. Aberrant communication between the damaged and stressed epithelium leads to the generation of growth factors that interact with the underlying mesenchyme to promote airway remodeling responses and a more chronic and persistent inflammatory phenotype. Disordered epithelial function with reduced antioxidant defense and impaired capacity to produce primary IFNs may also account for asthmatic susceptibility to air pollution and respiratory virus infection, respectively. Considering asthma as a disease of impaired barrier function opens new opportunities for therapeutic intervention or prevention by agents that could increase the airways resistance to the inhaled environment rather than suppressing the immune or inflammatory response.

We have used fiberoptic bronchoscopy to obtain endobronchial biopsies in which mast cells and eosinophils were enumerated using monoclonal antibodies directed against mast cell tryptase (AA1) and the eosinophil cationic protein (EG2). Eleven symptomatic atopic asthmatics treated with beta 2-agonists alone and six normal subjects were studied. Over a period of 2 wk prior to bronchoscopy, patients recorded asthma symptom scores, bronchodilator usage, and twice-daily peak expiratory flow. Five days before bronchoscopy, methacholine responsiveness was assessed. Two biopsies were taken from the subcarinae, one of which was processed into araldite for immunostaining by the streptavidin biotin immunoperoxidase method and the other into Spurr resin for electron microscopy. The number of AA1 staining mast cells present in the bronchial mucosa was not significantly different in the epithelium or submucosa between the asthmatic and the normal subjects. However, in the biopsies from asthmatics, there were significantly greater numbers of EG2-staining eosinophils in the epithelium (median, 1.2/mm versus zero; p less than 0.005) and in the submucosa (median, 50/mm2 versus 1/mm2; p less than 0.001). Electron microscopy showed morphologic features of mast cell and eosinophil degranulation in the asthmatics. No correlation could be established between mast cell or eosinophil numbers and indices of disease activity of PC20 methacholine, which points to the complexity of mechanisms responsible for the symptoms and the airway hyperresponsiveness of asthma.

Asthma is the most common inflammatory disease of the lungs. The prevalence of asthma is increasing in many parts of the world that have adopted aspects of the Western lifestyle, and the disease poses a substantial global health and economic burden. Asthma involves both the large-conducting and the small-conducting airways, and is characterized by a combination of inflammation and structural remodelling that might begin in utero. Disease progression occurs in the context of a developmental background in which the postnatal acquisition of asthma is strongly linked with allergic sensitization. Most asthma cases follow a variable course, involving viral-induced wheezing and allergen sensitization, that is associated with various underlying mechanisms (or endotypes) that can differ between individuals. Each set of endotypes, in turn, produces specific asthma characteristics that evolve across the lifecourse of the patient. Strong genetic and environmental drivers of asthma interconnect through novel epigenetic mechanisms that operate prenatally and throughout childhood. Asthma can spontaneously remit or begin de novo in adulthood, and the factors that lead to the emergence and regression of asthma, irrespective of age, are poorly understood. Nonetheless, there is mounting evidence that supports a primary role for structural changes in the airways with asthma acquisition, on which altered innate immune mechanisms and microbiota interactions are superimposed. On the basis of the identification of new causative pathways, the subphenotyping of asthma across the lifecourse of patients is paving the way for more-personalized and precise pathway-specific approaches for the prevention and treatment of asthma, creating the real possibility of total prevention and cure for this chronic inflammatory disease.

Rationale: The treatment effect of golimumab, a human monoclonal antibody against tumor necrosis factor (TNF)-α, in severe persistent asthma is unknown.Objectives: To assess the safety and efficacy of golimumab in a large population of patients with uncontrolled, severe persistent asthma.Methods: From 2004 to 2006, 309 patients with severe and uncontrolled asthma, despite high-dose inhaled corticosteroids and long-acting β2 agonists, were randomized 1:1:1:1 to monthly subcutaneous injections of placebo or golimumab (50, 100, or 200 mg) through Week 52. Coprimary endpoints were the change from baseline through Week 24 in prebronchodilator percent-predicted FEV1 and the number of severe asthma exacerbations through Week 24.Measurements and Main Results: No significant differences were observed for the change in percent-predicted FEV1 (least squares mean: placebo, 2.44 [95% confidence interval (CI) −0.574 to 5.461]; combined 100-mg and 200-mg, 2.91 [0.696–5.116]) or severe exacerbations (mean ± SD: placebo, 0.5 ± 1.07 vs. combined 100-mg and 200-mg 0.5 ± 0.97) through week 24. Through Week 24, 2.6% of patients treated with placebo vs. 19.5% of those treated with golimumab discontinued the study agent, and 1.3% and 7.8% discontinued study participation, respectively. An unfavorable risk–benefit profile led to early discontinuation of study-agent administration after the Week-24 database lock. Through Week 76, 20.5% of patients treated with placebo and 30.3% of patients treated with golimumab experienced serious adverse events, with serious infections occurring more frequently in golimumab-treated patients. One death and all eight malignancies occurred in the active groups.Conclusions: Overall, treatment with golimumab did not demonstrate a favorable risk–benefit profile in this study population of patients with severe persistent asthma.Clinical trial registered with www.clinicaltrials.gov (NCT00207740).

IgE plays a central role in allergic asthma, and there is also growing evidence suggestive of a role in nonallergic (intrinsic) asthma. The central role of IgE in allergic inflammation and the proposed mechanisms of action of omalizumab in inhibiting IgE-mediated processes are depicted schematically in Fig 2. Omalizumab treatment results in a rapid reduction in free IgE levels and downregulation of FcεRI on basophils, mast cells, and other inflammatory cells.13MacGlashan Jr., D.W. Bochner B.S. Adelman D.C. Jardieu P.M. Togias A. McKenzie-White J. et al.Down-regulation of Fc(epsilon)RI expression on human basophils during in vivo treatment of atopic patients with anti-IgE antibody.J Immunol. 1997; 158: 1438-1445PubMed Google Scholar, 14Lin H. Boesel K.M. Griffith D.T. Prussin C. Foster B. Romero F.A. et al.Omalizumab rapidly decreases nasal allergic response and FcεRI on basophils.J Allergy Clin Immunol. 2004; 113: 297-302Abstract Full Text Full Text PDF PubMed Scopus (250) Google Scholar, 17Prussin C. Griffith D.T. Boesel K.M. Lin H. Foster B. Casale T.B. Omalizumab treatment downregulates dendritic cell FcεRI expression.J Allergy Clin Immunol. 2003; 112: 1147-1154Abstract Full Text Full Text PDF PubMed Scopus (333) Google Scholar, 31Milgrom H. Berger W. Nayak A. Gupta N. Pollard S. McAlary M. et al.Treatment of childhood asthma with anti-immunoglobulin E antibody (omalizumab).Pediatrics. 2001; 108: E36Crossref PubMed Scopus (458) Google Scholar, 32Busse W. Corren J. Lanier B.Q. McAlary M. Fowler-Taylor A. Della-Cioppa G. et al.Omalizumab, anti-IgE recombinant humanized monoclonal antibody, for the treatment of severe allergic asthma.J Allergy Clin Immunol. 2001; 108: 184-190Abstract Full Text Full Text PDF PubMed Scopus (1150) Google Scholar, 33Solér M. Matz J. Townley R. Buhl R. O'Brien J. Fox H. et al.The anti-IgE antibody omalizumab reduces exacerbations and steroid requirement in allergic asthmatics.Eur Respir J. 2001; 18 ([published erratum appears in Eur Respir J 2001;18:739-40]): 254-261Crossref PubMed Scopus (815) Google Scholar Recent research has shown that the effects of omalizumab on circulating IgE and cellular IgE receptor expression are accompanied by a reduction in FcεRI+ cells and IgE+ cells in the airways of patients with asthma,20Djukanović R. Wilson S.J. Kraft M. Jarjour N.N. Steel M. Chung K.F. et al.The effects of anti-IgE (omalizumab) treatment on airways inflammation in allergic asthma.Am J Respir Crit Care Med. 2004; 170: 583-593Crossref PubMed Scopus (575) Google Scholar and because Fregonese et al5Fregonese L. Patel A. van Schadewijk A. Santos M.A. Dolhnikoff M. Sterk P.J. et al.Expression of the high-affinity IgE receptor (FcεRI) is increased in fatal asthma.Am J Respir Crit Care Med. 2004; 169 ([abstract]): A297Google Scholar have highlighted a possible relationship between FcεRI expression and fatal asthma, it is interesting to speculate whether omalizumab could have an effect on mortality.Fig 2Proposed mechanisms of action of omalizumab. Omalizumab decreases free IgE levels and reduces FcεRI receptor expression on mast cells and basophils. This results in decreased mast cell activation and sensitivity, leading to a reduction in eosinophil influx and activation. Anti-IgE treatment with omalizumab might result in decreased mast cell survival. Omalizumab also reduces dendritic cell FcεRI receptor expression.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Airway wall remodeling is an established pathological feature in asthma. Its causes are not well understood, but one mediator of potential relevance is transforming growth factor-beta 1 (TGF-beta 1). We have measured levels of immunoreactive TGF-beta 1 in bronchoalveolar lavage (BAL) fluid from clinically stable atopic asthmatics and healthy control subjects. We have also examined the influence of allergen exposure on TGF-beta 1 release in the airways using a segmental bronchoprovocation model, with BAL performed at two time points following endobronchial allergen and sham saline challenges. Basal concentrations of TGF-beta 1 were significantly higher in asthmatics than control subjects (median 8.0 versus 5.5 pg/ml, p = 0.027). Following segmental bronchoprovocation, concentrations of TGF-beta 1 at the allergen- and saline-challenged sites were not significantly different after 10 min, (31.3 versus 25.0 pg/ml, p = 0.78), but after 24 h there were significantly higher TGF-beta 1 concentrations at the allergen-challenged sites (46.0 versus 21.5 pg/ml, p = 0.017). We conclude that basal TGF-beta 1 levels in the airways are elevated in atopic asthma and that these levels increase further in response to allergen exposure. These findings are consistent with the hypothesis that TGF-beta 1 is implicated in airway wall remodeling in asthma.

<h2>Summary</h2><h3>Background</h3> Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection carries a substantial risk of severe and prolonged illness; treatment options are currently limited. We assessed the efficacy and safety of inhaled nebulised interferon beta-1a (SNG001) for the treatment of patients admitted to hospital with COVID-19. <h3>Methods</h3> We did a randomised, double-blind, placebo-controlled, phase 2 pilot trial at nine UK sites. Adults aged 18 years or older and admitted to hospital with COVID-19 symptoms, with a positive RT-PCR or point-of-care test, or both, were randomly assigned (1:1) to receive SNG001 (6 MIU) or placebo by inhalation via a mouthpiece daily for 14 days. The primary outcome was the change in clinical condition on the WHO Ordinal Scale for Clinical Improvement (OSCI) during the dosing period in the intention-to-treat population (all randomised patients who received at least one dose of the study drug). The OSCI is a 9-point scale, where 0 corresponds to no infection and 8 corresponds to death. Multiple analyses were done to identify the most suitable statistical method for future clinical trials. Safety was assessed by monitoring adverse events for 28 days. This trial is registered with Clinicaltrialsregister.eu (2020-001023-14) and ClinicalTrials.gov (NCT04385095); the pilot trial of inpatients with COVID-19 is now completed. <h3>Findings</h3> Between March 30 and May 30, 2020, 101 patients were randomly assigned to SNG001 (n=50) or placebo (n=51). 48 received SNG001 and 50 received placebo and were included in the intention-to-treat population. 66 (67%) patients required oxygen supplementation at baseline: 29 in the placebo group and 37 in the SNG001 group. Patients receiving SNG001 had greater odds of improvement on the OSCI scale (odds ratio 2·32 [95% CI 1·07–5·04]; p=0·033) on day 15 or 16 and were more likely than those receiving placebo to recover to an OSCI score of 1 (no limitation of activities) during treatment (hazard ratio 2·19 [95% CI 1·03–4·69]; p=0·043). SNG001 was well tolerated. The most frequently reported treatment-emergent adverse event was headache (seven [15%] patients in the SNG001 group and five [10%] in the placebo group). There were three deaths in the placebo group and none in the SNG001 group. <h3>Interpretation</h3> Patients who received SNG001 had greater odds of improvement and recovered more rapidly from SARS-CoV-2 infection than patients who received placebo, providing a strong rationale for further trials. <h3>Funding</h3> Synairgen Research.

Patients with severe persistent asthma who are inadequately controlled despite treatment according to current asthma management guidelines have a significant unmet medical need. Such patients are at high risk of serious exacerbations and asthma-related mortality.Here, we pooled data from seven studies to determine the effect of omalizumab, an anti-immunoglobulin E (IgE) monoclonal antibody, on asthma exacerbations in patients with severe persistent asthma. Omalizumab was added to current asthma therapy and compared with placebo (in five double-blind studies) or with current asthma therapy alone (in two open-label studies). The studies included 4308 patients (2511 treated with omalizumab), 93% of whom had severe persistent asthma according to the Global Initiative for Asthma (GINA) 2002 classification. Using the Poisson regression model, results were calculated as the ratio of treatment effect (omalizumab : control) on the standardized exacerbation rate per year.Omalizumab significantly reduced the rate of asthma exacerbations by 38% (P < 0.0001 vs control) and the rate of total emergency visits by 47% (P < 0.0001 vs control). Analysis of demographic subgroups showed that the efficacy of omalizumab on asthma exacerbations was unaffected by patient age, gender, baseline serum IgE (split by median) or by 2- or 4-weekly dosing schedule, although benefit in absolute terms appeared to be greatest in patients with more severe asthma, defined by a lower value of percentage predicted forced expiratory volume in 1 s (FEV(1)) at baseline.These results suggest that omalizumab may fulfil an important need in patients with severe persistent asthma, many of whom are not adequately controlled on current therapy.

Background Interleukin-12 (IL-12) is a macrophage-derived cytokine that modulates T lymphocyte responses and has the capacity to suppress allergic and eosinophilic inflammation. Methods We carried out a double-blind, randomised, parallel group clinical study, in which patients with mild allergic asthma were given subcutaneous recombinant human IL-12 at increasing weekly injections of 0·1, 0·25, 0·5 μg/kg (n=19), or placebo (n=20). We compared responses to inhaled allergen challenge 24 h before the first injection and 24 h after the final injection. Airways hyper-responsiveness and concentrations of peripheral blood eosinophils and sputum eosinophils were also assessed. Findings IL-12 caused a significant decrease from baseline in the main peripheral blood eosinophil count 24 h after the fourth injection compared with placebo (p=0·0001). Sputum eosinophils were also significantly decreased 24 h after allergen challenge when treated with IL-12 compared with placebo (p=0·024). IL-12 caused a non-significant trend towards improvement in airway hyper-responsiveness to histamine, but had no significant effect on the late asthmatic reaction after inhaled allergen challenge. After administration of IL-12, four of 19 patients withdrew prematurely; two with cardiac arrhythmias, one with abnormal liver function, and a single patient with severe flu-like symptoms. Interpretation We have shown that IL-12 lowers numbers of blood and sputum eosinophils, but without any significant effects on airway hyper-responsiveness or the late asthmatic reaction. This questions the role of eosinophils in mediating these reactions, and has important implications for development of new anti-inflammatory treatments.

To cite this article: Church MK, Maurer M, Simons FER, Bindslev‐Jensen C, van Cauwenberge P, Bousquet J, Holgate ST, Zuberbier T. Risk of first‐generation H 1 ‐antihistamines: a GA 2 LEN position paper. Allergy 2010; 65 : 459–466. Abstract Background: First‐generation H 1 ‐antihistamines obtained without prescription are the most frequent form of self‐medication for allergic diseases, coughs and colds and insomnia even though they have potentially dangerous unwanted effects which are not recognized by the general public. Aims: To increase consumer protection by bringing to the attention of regulatory authorities, physicians and the general public the potential dangers of the indiscriminate use first‐generation H 1 ‐antihistamines purchased over‐the counter in the absence of appropriate medical supervision. Methods: A GA 2 LEN (Global Allergy and Asthma European Network) task force assessed the unwanted side‐effects and potential dangers of first‐generation H1‐antihistamines by reviewing the literature (Medline and Embase) and performing a media audit of US coverage from 1996 to 2008 of accidents and fatal adverse events in which these drugs were implicated. Results: First‐generation H 1 ‐antihistamines, all of which are sedating, are generally regarded as safe by laypersons and healthcare professionals because of their long‐standing use. However, they reduce rapid eye movement (REM)‐sleep, impair learning and reduce work efficiency. They are implicated in civil aviation, motor vehicle and boating accidents, deaths as a result of accidental or intentional overdosing in infants and young children and suicide in teenagers and adults. Some exhibit cardiotoxicity in overdose. Conclusions: This review raises the issue of better consumer protection by recommending that older first‐generation H 1 ‐antihistamines should no longer be available over‐the‐counter as prescription‐ free drugs for self‐medication of allergic and other diseases now that newer second‐ generation nonsedating H 1 ‐antihistamines with superior risk/benefit ratios are widely available at competitive prices.

The adoption of the concept that asthma is primarily a disease most frequently associated with elaboration of T-helper 2 (Th2)-type inflammation has led to the widely held concept that its origins, exacerbation, and persistence are allergen driven. Taking aside the asthma that is expressed in non-allergic individuals leaves the great proportion of asthma that is associated with allergy (or atopy) and that often has its onset in early childhood. Evidence is presented that asthma is primarily an epithelial disorder and that its origin as well as its clinical manifestations have more to do with altered epithelial physical and functional barrier properties than being purely linked to allergic pathways. In genetically susceptible individuals, impaired epithelial barrier function renders the airways vulnerable to early life virus infection, and this in turn provides the stimulus to prime immature dendritic cells toward directing a Th2 response and local allergen sensitization. Continued epithelial susceptibility to environmental insults such as viral, allergen, and pollutant exposure and impaired repair responses leads to asthma persistence and provides the mediator and growth factor microenvironment for persistence of inflammation and airway wall remodeling. Increased deposition of matrix in the epithelial lamina reticularis provides evidence for ongoing epithelial barrier dysfunction, while physical distortion of the epithelium consequent upon repeated bronchoconstriction provides additional stimuli for remodeling. This latter response initially serves a protective function but, if exaggerated, may lead to fixed airflow obstruction associated with more severe and chronic disease. Dual pathways in the origins, persistence, and progression of asthma help explain why anti-inflammatory treatments fail to influence the natural history of asthma in childhood and only partially does so in chronic severe disease. Positioning the airway epithelium as fundamental to the origins and persistence of asthma provides a rationale for pursuit of therapeutics that increase the resistance of the airways to environmental insults rather than concentrating all effort on suppressing inflammation.

There has been a recent increase in the prevalence of asthma worldwide; however, the 5–10% of patients with severe disease account for a substantial proportion of the health costs. Although most asthma cases can be satisfactorily managed with a combination of anti-inflammatory drugs and bronchodilators, patients who remain symptomatic despite maximum combination treatment represent a heterogeneous group consisting of those who are under-treated or non-adherent with their prescribed medication. After excluding under-treatment and poor compliance, corticosteroid refractory asthma can be identified as a subphenotype characterised by a heightened neutrophilic airway inflammatory response in the presence or absence of eosinophils, with evidence of increased tissue injury and remodelling. Although a wide range of environmental factors such as allergens, smoking, air pollution, infection, hormones, and specific drugs can contribute to this phenotype, other features associated with changes in the airway inflammatory response should be taken into account. Aberrant communication between an injured airway epithelium and underlying mesenchyme contributes to disease chronicity and refractoriness to corticosteroids. The importance of identifying underlying causative factors and the recent introduction of novel therapeutic approaches, including the targeting of immunoglobulin E and tumour necrosis factor α with biological agents, emphasise the need for careful phenotyping of patients with severe disease to target improved management of the individual patient's needs.

<h2>Abstract</h2> The prevalence of allergic airway diseases such as asthma and rhinitis has increased dramatically to epidemic proportions worldwide. Besides air pollution from industry derived emissions and motor vehicles, the rising trend can only be explained by gross changes in the environments where we live. The world economy has been transformed over the last 25 years with developing countries being at the core of these changes. Around the planet, in both developed and developing countries, environments are undergoing profound changes. Many of these changes are considered to have negative effects on respiratory health and to enhance the frequency and severity of respiratory diseases such as asthma in the general population. Increased concentrations of greenhouse gases, and especially carbon dioxide (CO₂), in the atmosphere have already warmed the planet substantially, causing more severe and prolonged heat waves, variability in temperature, increased air pollution, forest fires, droughts, and floods – all of which can put the respiratory health of the public at risk. These changes in climate and air quality have a measurable impact not only on the morbidity but also the mortality of patients with asthma and other respiratory diseases. The massive increase in emissions of air pollutants due to economic and industrial growth in the last century has made air quality an environmental problem of the first order in a large number of regions of the world. A body of evidence suggests that major changes to our world are occurring and involve the atmosphere and its associated climate. These changes, including global warming induced by human activity, have an impact on the biosphere, biodiversity, and the human environment. Mitigating this huge health impact and reversing the effects of these changes are major challenges. This statement of the World Allergy Organization (WAO) raises the importance of this health hazard and highlights the facts on climate-related health impacts, including: deaths and acute morbidity due to heat waves and extreme meteorological events; increased frequency of acute cardio-respiratory events due to higher concentrations of ground level ozone; changes in the frequency of respiratory diseases due to trans-boundary particle pollution; altered spatial and temporal distribution of allergens (pollens, molds, and mites); and some infectious disease vectors. According to this report, these impacts will not only affect those with current asthma but also increase the incidence and prevalence of allergic respiratory conditions and of asthma. The effects of climate change on respiratory allergy are still not well defined, and more studies addressing this topic are needed. Global warming is expected to affect the start, duration, and intensity of the pollen season on the one hand, and the rate of asthma exacerbations due to air pollution, respiratory infections, and/or cold air inhalation, and other conditions on the other hand.

Reproducible science requires transparent reporting. The ARRIVE guidelines (Animal Research: Reporting of In Vivo Experiments) were originally developed in 2010 to improve the reporting of animal research. They consist of a checklist of information to include in publications describing in vivo experiments to enable others to scrutinise the work adequately, evaluate its methodological rigour, and reproduce the methods and results. Despite considerable levels of endorsement by funders and journals over the years, adherence to the guidelines has been inconsistent, and the anticipated improvements in the quality of reporting in animal research publications have not been achieved. Here, we introduce ARRIVE 2.0. The guidelines have been updated and information reorganised to facilitate their use in practice. We used a Delphi exercise to prioritise and divide the items of the guidelines into 2 sets, the “ARRIVE Essential 10,” which constitutes the minimum requirement, and the “Recommended Set,” which describes the research context. This division facilitates improved reporting of animal research by supporting a stepwise approach to implementation. This helps journal editors and reviewers verify that the most important items are being reported in manuscripts. We have also developed the accompanying Explanation and Elaboration (E&amp;E) document, which serves (1) to explain the rationale behind each item in the guidelines, (2) to clarify key concepts, and (3) to provide illustrative examples. We aim, through these changes, to help ensure that researchers, reviewers, and journal editors are better equipped to improve the rigour and transparency of the scientific process and thus reproducibility.

Although prostaglandin D2 is the most abundant prostanoid generated by human lung mast cells and causes bronchoconstriction in animals, its effects have not been studied in human beings. We have compared the effects of inhaled prostaglandin D2 and prostaglandin F2 alpha on specific airway conductance in seven normal subjects and seven patients with mild allergic asthma. In dose-response studies in normal subjects, prostaglandin D2 caused a significant (20 +/- 6 per cent) fall in specific airway conductance after the two highest concentrations (250 and 500 micrograms per milliliter), whereas prostaglandin F2 alpha had no effect. In the asthmatic subjects, both prostaglandin D2 and prostaglandin F2 alpha caused a dose-related fall in specific airway conductance, starting at the lowest concentration of 4 micrograms per milliliter. Prostaglandin D2 was 3.5 times more potent than prostaglandin F2 alpha. In a single-dose study of both drugs (250 micrograms per milliliter), a minor fall in specific airway conductance occurred with prostaglandin D2 in the normal subjects, and a larger fall occurred with both drugs in the asthmatic subjects. Maximum effects were seen at three minutes: there was a 75 +/- 5 per cent fall with prostaglandin D2 and a 33 +/- 8 per cent fall with prostaglandin F2 alpha. These results suggest that prostaglandin D2 may be involved in the pathogenesis of bronchoconstriction in allergic asthma.

Asthma is an inflammatory disorder principally involving the conducting airways and characterised by infiltration of the airway wall with a range of inflammatory cells driven in large part by activation of Th2-type lymphocytes, mast cells and eosinophils. However a key component of asthma is the structural change that involves all of the elements of the airway wall. Here evidence is presented to suggest that the airway epithelium in asthma is fundamentally abnormal with increased susceptibility to environmental injury and impaired repair associated with activation of the epithelial-mesenchymal trophic unit (EMTU). In addition to adopting an activated phenotype, the barrier function of the epithelium is impaired through defective tight junction formation thereby facilitating penetration of potentially toxic or damaging environmental insults. Activated and repairing epithelial cells generate a range of growth factors that are involved in the early life origins of this disease as well as its progression in the form of mucous metaplasia and airway wall remodeling. By placing the epithelium at the forefront of asthma pathogenesis, different approaches to treatment can be devised focused more on protecting vulnerable airways against environmental injury rather than focusing on suppressing airway inflammation or manipulating the immune response.

Biodiversity loss and climate change secondary to human activities are now being associated with various adverse health effects. However, less attention is being paid to the effects of biodiversity loss on environmental and commensal (indigenous) microbiotas. Metagenomic and other studies of healthy and diseased individuals reveal that reduced biodiversity and alterations in the composition of the gut and skin microbiota are associated with various inflammatory conditions, including asthma, allergic and inflammatory bowel diseases (IBD), type1 diabetes, and obesity. Altered indigenous microbiota and the general microbial deprivation characterizing the lifestyle of urban people in affluent countries appear to be risk factors for immune dysregulation and impaired tolerance. The risk is further enhanced by physical inactivity and a western diet poor in fresh fruit and vegetables, which may act in synergy with dysbiosis of the gut flora. Studies of immigrants moving from non-affluent to affluent regions indicate that tolerance mechanisms can rapidly become impaired in microbe-poor environments. The data on microbial deprivation and immune dysfunction as they relate to biodiversity loss are evaluated in this Statement of World Allergy Organization (WAO). We propose that biodiversity, the variability among living organisms from all sources are closely related, at both the macro- and micro-levels. Loss of the macrodiversity is associated with shrinking of the microdiversity, which is associated with alterations of the indigenous microbiota. Data on behavioural means to induce tolerance are outlined and a proposal made for a Global Allergy Plan to prevent and reduce the global allergy burden for affected individuals and the societies in which they live.

The term severe refractory asthma (SRA) in adults applies to patients who remain difficult to control despite extensive re-evaluation of diagnosis and management following an observational period of at least 6 months by a specialist. Factors that influence asthma control should be recognized and adequately addressed prior to confirming the diagnosis of SRA. This report presents statements according to the literature defining SRA in order address the important questions. Phenotyping SRA will improve our understanding of mechanisms, natural history, and prognosis. Female gender, obesity, and smoking are associated with SRA. Atopy is less frequent in SRA, but occupational sensitizers are common inducers of new-onset SRA. Viruses contribute to severe exacerbations and can persist in the airways for long periods. Inflammatory cells are in the airways of the majority of patients with SRA and persist despite steroid therapy. The T(H)2 immune process alone is inadequate to explain SRA. Reduced responsiveness to corticosteroids is common, and epithelial cell and smooth muscle abnormalities are found, contributing to airway narrowing. Large and small airway wall thickening is observed, but parenchymal abnormalities may influence airway limitation. Inhaled corticosteroids and bronchodilators are the mainstay of treatment, but patients with SRA remain uncontrolled, indicating a need for new therapies.

A major part of the burden of asthma is caused by acute exacerbations. Exacerbations have been strongly and consistently associated with respiratory infections. Respiratory viruses and bacteria are therefore possible treatment targets. To have a reasonable estimate of the burden of disease induced by such infectious agents on asthmatic patients, it is necessary to understand their nature and be able to identify them in clinical samples by employing accurate and sensitive methodologies. This systematic review summarizes current knowledge and developments in infection epidemiology of acute asthma in children and adults, describing the known impact for each individual agent and highlighting knowledge gaps. Among infectious agents, human rhinoviruses are the most prevalent in regard to asthma exacerbations. The newly identified type-C rhinoviruses may prove to be particularly relevant. Respiratory syncytial virus and metapneumovirus are important in infants, while influenza viruses seem to induce severe exacerbations mostly in adults. Other agents are relatively less or not clearly associated. Mycoplasma and Chlamydophila pneumoniae seem to be involved more with asthma persistence rather than with disease exacerbations. Recent data suggest that common bacteria may also be involved, but this should be confirmed. Although current information is considerable, improvements in detection methodologies, as well as the wide variation in respect to location, time and populations, underline the need for additional studies that should also take into account interacting factors.

Ex vivo, bronchial epithelial cells from people with asthma are more susceptible to rhinovirus infection caused by deficient induction of the antiviral protein, IFN-β. Exogenous IFN-β restores antiviral activity.To compare the efficacy and safety of inhaled IFN-β with placebo administered to people with asthma after onset of cold symptoms to prevent or attenuate asthma symptoms caused by respiratory viruses.A total of 147 people with asthma on inhaled corticosteroids (British Thoracic Society Steps 2-5), with a history of virus-associated exacerbations, were randomized to 14-day treatment with inhaled IFN-β (n = 72) or placebo (n = 75) within 24 hours of developing cold symptoms and were assessed clinically, with relevant samples collected to assess virus infection and antiviral responses.A total of 91% of randomized patients developed a defined cold. In this modified intention-to-treat population, asthma symptoms did not get clinically significantly worse (mean change in six-item Asthma Control Questionnaire <0.5) and IFN-β treatment had no significant effect on this primary endpoint, although it enhanced morning peak expiratory flow recovery (P = 0.033), reduced the need for additional treatment, and boosted innate immunity as assessed by blood and sputum biomarkers. In an exploratory analysis of the subset of more difficult-to-treat, Step 4-5 people with asthma (n = 27 IFN-β; n = 31 placebo), Asthma Control Questionnaire-6 increased significantly on placebo; this was prevented by IFN-β (P = 0.004).Although the trial did not meet its primary endpoint, it suggests that inhaled IFN-β is a potential treatment for virus-induced deteriorations of asthma in difficult-to-treat people with asthma and supports the need for further, adequately powered, trials in this population. Clinical trial registered with www.clinicaltrials.gov (NCT 01126177).

Genetic variation provides the basis for differences in the host response to a variety of environmental factors that can result in complex genetic diseases, including asthma and atopy. Through our ability to capture genetic variation at the single-nucleotide level and our increasing ability to perform large-scale sequencing of the human genome, including the development of computer algorithms for improved data analysis, our understanding of these complex diseases has increased dramatically in recent years. The genetics of allergy have shifted from characterizing a single polymorphism in a candidate gene as being responsible for the disease to inclusion of a multitude of genetic and nongenetic risk factors. Studies now must consider complex relationships that modify an individual's susceptibility, including possible gene-environment and gene-gene interactions and possible epigenetic modification of the genome. This review will discuss the techniques used for genetic analysis of complex diseases, some of the important genes that have been replicated in multiple asthma studies, and the future of genetic studies in asthma.

IgE is central to the pathophysiology of allergic asthma. Omalizumab, a humanized anti-IgE mAb, specifically binds free IgE and interrupts the allergic cascade by preventing binding of IgE with its high-affinity FcεRI receptors on mast cells, antigen-presenting cells, and other inflammatory cells. The clinical efficacy of omalizumab has been well documented in a number of clinical trials that involve adults, adolescents, and children with moderate-to-severe and severe allergic asthma. In these studies, omalizumab reduced exacerbations, asthma symptoms, inhaled corticosteroid and rescue medication use, and improved quality of life relative to placebo or best standard of care. Similar benefits have been reported in observational studies in "real-world" populations of patients. Results from recent pooled data from randomized clinical trials and from a large prospective cohort study provide reassurance about the long-term safety of omalizumab. Omalizumab dosing is individualized according to body weight and serum-IgE level, and recent adjustments to the dosing algorithm in Europe have enabled more patients to be eligible for treatment. Ongoing and future research is investigating the optimal duration of therapy, accurate predictors of response to treatment, and efficacy in nonatopic asthma as well as other IgE-mediated conditions.

Asthma is widely accepted as a complex heterogeneous condition with diverse pathophysiological mechanisms, clinical presentations, comorbidities, physiological characteristics, pathology and outcomes that is typically best managed by a multidisciplinary team [1–4]. Severe asthma is recognised as a major unmet need with a high personal and social impact, as well as a high burden on healthcare resources [4]. As a consequence of advances in the development of precision medicines for patients with severe asthma, the need to identify asthma subtypes by phenotype based on clinical, functional or inflammatory parameters is becoming a mandatory part of management [4–6]. A task force has identified key consensus issues for defining, diagnosing and treating severe eosinophilic asthma <http://ow.ly/zrvO30axYWx> The contents of this paper reflect the discussions between attending participants at the European Consensus Meeting for Severe Eosinophilic Asthma (November 24 2016, Amsterdam, The Netherlands) where medical attendees from TEVA Pharmaceuticals Europe B.V. were present as observers. The authors have been given full editorial control and independence and TEVA has had no influence on the contents. The following members of the expert group made important contributions at the initial meeting and/or made useful comments on earlier drafts of this editorial: Ratko Djukanovic (University of Southampton, Southampton, UK), Kian Fan Chung (Imperial College, London, UK), Walter Canonica (Humanitas University, Milan, Italy), Alberto Papi (Ferrara University, Ferrara, Italy), Chris Brightling (University of Leicester, Leicester, UK), Ildiko Horváth (Semmelweis University, Budapest, Hungary), Samantha Walker (Asthma UK, London, UK), Guy Brusselle (Ghent University Hospital, Ghent, Belgium), Vibeke Backer (Bispebjerg Hospital, Copenhagen, Denmark), Piotr Kuna (University of Lodz, Lodz, Poland), Elisabeth Bel (University of Amsterdam, Amsterdam, The Netherlands), Luis Perez de Llano (Lucus Agusti University Hospital, Lugo, Spain), and Klaus Rabe (University of Kiel, Kiel, Germany).

Reproducible science requires transparent reporting. The ARRIVE guidelines (Animal Research: Reporting of In Vivo Experiments) were originally developed in 2010 to improve the reporting of animal research. They consist of a checklist of information to include in publications describing in vivo experiments to enable others to scrutinise the work adequately, evaluate its methodological rigour, and reproduce the methods and results. Despite considerable levels of endorsement by funders and journals over the years, adherence to the guidelines has been inconsistent, and the anticipated improvements in the quality of reporting in animal research publications have not been achieved. Here, we introduce ARRIVE 2.0. The guidelines have been updated and information reorganised to facilitate their use in practice. We used a Delphi exercise to prioritise and divide the items of the guidelines into 2 sets, the "ARRIVE Essential 10," which constitutes the minimum requirement, and the "Recommended Set," which describes the research context. This division facilitates improved reporting of animal research by supporting a stepwise approach to implementation. This helps journal editors and reviewers verify that the most important items are being reported in manuscripts. We have also developed the accompanying Explanation and Elaboration document, which serves (1) to explain the rationale behind each item in the guidelines, (2) to clarify key concepts, and (3) to provide illustrative examples. We aim, through these changes, to help ensure that researchers, reviewers, and journal editors are better equipped to improve the rigour and transparency of the scientific process and thus reproducibility.

Reproducible science requires transparent reporting. The ARRIVE guidelines (Animal Research: Reporting of In Vivo Experiments) were originally developed in 2010 to improve the reporting of animal research. They consist of a checklist of information to include in publications describing in vivo experiments to enable others to scrutinise the work adequately, evaluate its methodological rigour and reproduce the methods and results. Despite considerable levels of endorsement by funders and journals over the years, adherence to the guidelines has been inconsistent, and the anticipated improvements in the quality of reporting in animal research publications have not been achieved. Here, we introduce ARRIVE 2.0. The guidelines have been updated and information reorganised to facilitate their use in practice. We used a Delphi exercise to prioritise and divide the items of the guidelines into two sets, the 'ARRIVE Essential 10', which constitutes the minimum requirement, and the 'Recommended Set', which describes the research context. This division facilitates improved reporting of animal research by supporting a stepwise approach to implementation. This helps journal editors and reviewers verify that the most important items are being reported in manuscripts. We have also developed the accompanying Explanation and Elaboration document, which serves (1) to explain the rationale behind each item in the guidelines, (2) to clarify key concepts and (3) to provide illustrative examples. We aim, through these changes, to help ensure that researchers, reviewers and journal editors are better equipped to improve the rigour and transparency of the scientific process and thus reproducibility.

Abstract The exponential growth of precision diagnostic tools, including omic technologies, molecular diagnostics, sophisticated genetic and epigenetic editing, imaging and nano‐technologies and patient access to extensive health care, has resulted in vast amounts of unbiased data enabling in‐depth disease characterization. New disease endotypes have been identified for various allergic diseases and triggered the gradual transition from a disease description focused on symptoms to identifying biomarkers and intricate pathogenetic and metabolic pathways. Consequently, the current disease taxonomy has to be revised for better categorization. This European Academy of Allergy and Clinical Immunology Position Paper responds to this challenge and provides a modern nomenclature for allergic diseases, which respects the earlier classifications back to the early 20th century. Hypersensitivity reactions originally described by Gell and Coombs have been extended into nine different types comprising antibody‐ (I‐III), cell‐mediated (IVa‐c), tissue‐driven mechanisms (V‐VI) and direct response to chemicals (VII). Types I‐III are linked to classical and newly described clinical conditions. Type IVa‐c are specified and detailed according to the current understanding of T1, T2 and T3 responses. Types V‐VI involve epithelial barrier defects and metabolic‐induced immune dysregulation, while direct cellular and inflammatory responses to chemicals are covered in type VII. It is notable that several combinations of mixed types may appear in the clinical setting. The clinical relevance of the current approach for allergy practice will be conferred in another article that will follow this year, aiming at showing the relevance in clinical practice where various endotypes can overlap and evolve over the lifetime.

We have previously demonstrated that short-term exposure to diesel exhaust (DE) for 1 h induced a marked leukocytic infiltration in the airways of healthy human volunteers involving neutrophils, lymphocytes, and mast cells along with increases in several inflammatory mediators. We hypothesized that the leukocyte infiltration and the various inflammatory responses induced by DE were mediated by enhanced chemokine and cytokine production by resident cells of the airway tissue and lumen. To investigate this, 15 healthy human volunteers were exposed to diluted DE and air on two separate occasions for 1 h each in an exposure chamber. Fiberoptic bronchoscopy was performed 6 h after each exposure to obtain endobronchial biopsies and bronchial wash (BW) cells. Using reverse transcriptase/polymerase chain reaction enzyme-linked immunosorbent assay (RT-PCR ELISA), a novel and sensitive technique to quantify relative amounts of cytokine mRNA gene transcripts, and immunohistochemical staining with computer-assisted image analysis to quantify expression of cytokine protein in the bronchial tissue, we have demonstrated that DE enhanced gene transcription of interleukin-8 (IL-8) in the bronchial tissue and BW cells along with increases in IL-8 and growth-regulated oncogene-alpha (GRO-alpha) protein expression in the bronchial epithelium, and an accompanying trend toward an increase in IL-5 mRNA gene transcripts in the bronchial tissue. There were no significant changes in the gene transcript levels of interleukin-1B (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), interferon gamma (IFN-gamma), and granulocyte macrophage colony-stimulating factor (GM-CSF) either in the bronchial tissue or BW cells after DE exposure at this time point. These observations suggest an underlying mechanism for DE-induced airway leukocyte infiltration and offer a possible explanation for the association observed between ambient levels of particulate matter and various respiratory health outcome indices noted in epidemiological studies.

A new paradigm for asthma pathogenesis is presented in which exaggerated inflammation and remodeling in the airways are a consequence of abnormal injury and repair responses arising from a subject's susceptibility to components of the inhaled environment. An epithelial-mesenchymal trophic unit becomes activated to drive pathologic remodeling and smooth muscle proliferation through complex cytokine interactions. Histamine, prostanoids, and cysteinyl leukotrienes (CysLTs) are potent contractile agonists of airway smooth muscle (ASM). The CysLTs appear to play a central role in regulating human ASM motor tone and phenotypic alterations, manifested as hypertrophy and hyperplasia in chronic severe asthma. The CysLTs augment growth factor–induced ASM mitogenesis through activation of CysLT receptors. Although they mediate their contractile effects by increasing phosphoinositide turnover and inducing increased cytosolic calcium, new data suggest that part of the contractile effect may be independent of calcium mobilization. Prostaglandin E2, the predominant eicosanoid product of the airway epithelium, is a potent inhibitor of mitogenesis, collagen synthesis, and mesenchymal cell chemotaxis and therefore can suppress inflammation and fibroblast activation. The capacity of the epithelium for CysLT synthesis is inversely related to its ability to make PGE2. The ASM is capable of expressing both leukotriene-synthesizing enzymes and CysLT receptors, and cytokines upregulate the receptor expression. This may be an explanation for the CysLTs promoting airway hyperresponsiveness in asthma. The CysLTs play an important role in the airway remodeling seen in persistent asthma that includes increases of airway goblet cells, mucus, blood vessels, smooth muscle, myofibroblasts, and airway fibrosis. Evidence from a mouse model of asthma demonstrated that CysLT1 receptor antagonists inhibit the airway remodeling processes, including eosinophil trafficking to the lungs, eosinophil degranulation, TH2 cytokine release, mucus gland hyperplasia, mucus hypersecretion, smooth muscle cell hyperplasia, collagen deposition, and lung fibrosis. (J Allergy Clin Immunol 2003;111:S18-36.)

Leukotriene antagonists block the proinflammatory actions of leukotrienes (LT) and have been introduced as new treatments for asthma. Conventional therapy with glucocorticosteroids does not inhibit the biosynthesis of leukotrienes. We therefore tested whether addition of the leukotriene receptor antagonist montelukast was of therapeutic benefit in a group of aspirin-intolerant patients with asthma of whom 90% already were treated with moderate to high doses of glucocorticosteroids. Under double-blind conditions, 80 aspirin-intolerant patients with asthma were randomized to receive 4 wk oral treatment of either 10 mg of montelukast or placebo once daily at bedtime. Pulmonary function was measured as forced expiratory volume in 1 s (FEV(1)) once a week in the clinic and daily as morning and evening peak expiratory flow rate (PEFR). Asthma symptoms and use of rescue bronchodilator were also recorded daily. Asthma specific quality of life (QoL) was assessed before and after the treatments. The group receiving montelukast showed a remarkable improvement of their asthma, whereas the group given placebo showed no change. Thus, from equal baseline values, the mean difference between the groups over the 4-wk treatment period was 10.2% for FEV(1) and 28.0 L for morning PEFR (p for both < 0.001). The improved pulmonary function in the group receiving montelukast occurred at the same time as 27% less bronchodilator was used (p < 0.05), and it was associated with fewer asthma symptoms than in the group given placebo, including 1.3 nights more of sleep per week and 54% fewer asthma exacerbations (p < 0.05). There was also an improvement in asthma-specific QoL (p < 0.05). The therapeutic response to montelukast was consistent across patients with different baseline characteristics and did not correlate with baseline urinary LTE(4). Addition of a leukotriene receptor antagonist such as montelukast improves asthma in aspirin-intolerant patients over and above what can be achieved by glucocorticosteroids.

A link between exposure to the air pollutant nitrogen dioxide (NO2) and respiratory disease has been suggested. Viral infections are the major cause of asthma exacerbations. We aimed to assess whether there is a relation between NO2 exposure and the severity of asthma exacerbations caused by proven respiratory viral infections in children.A cohort of 114 asthmatic children aged between 8 and 11 years recorded daily upper and lower respiratory-tract symptoms, peak expiratory flow (PEF), and measured personal NO2 exposures every week for up to 13 months. We took nasal aspirates during reported episodes of upper respiratory-tract illness and tested for infection by common respiratory viruses and atypical bacteria with RT-PCR assays. We used generalised estimating equations to assess the relation between low (<7.5 microg/m3), medium (7.5-14 microg/m3 ), and high (>14 microg/m3) tertiles of NO2 exposure in the week before or after upper respiratory-tract infection and the severity of asthma exacerbation in the week after the start of an infection.One or more viruses were detected in 78% of reported infection episodes, and the medians of NO2 exposure were 5 (IQR 3.6-6.3), 10 (8.7-12.0), and 21 microg/m3 (16.8-42.9) for low, medium, and high tertiles, respectively. There were significant increases in the severity of lower respiratory-tract symptom scores across the three tertiles (0.6 for all viruses [p=0.05] and >2 for respiratory syncytial virus [p=0.01]) and a reduction in PEF of more than 12 L/min for picornavirus (p=0.04) for high compared with low NO2 exposure before the start of the virus-induced exacerbation.High exposure to NO2 in the week before the start of a respiratory viral infection, and at levels within current air quality standards, is associated with an increase in the severity of a resulting asthma exacerbation.

The sulfidopeptide leukotrienes C4, D4, and E4 are released from mast cells in response to allergen challenge and may be involved in the bronchoconstrictor response to inhaled allergen in asthma. Since mast cell activation may also be implicated in exercise-induced bronchoconstriction, we assessed the inhibitory effects of a potent orally active leukotriene D4 receptor antagonist, ICI 204219 (20 mg), on the bronchoconstrictor response to exercise in eight male asthmatic patients in a placebo-controlled, randomized crossover study. Exercise challenge respiring dry air was performed on a treadmill at constant speed and gradient 2 h after drug administration, and bronchoconstriction was assessed as change in FEV1 over 30 min postexercise. No significant effect on airway caliber, measured as FEV1, was noted 2 h after ICI 204219. The mean maximum percentage fall in FEV1 following exercise was 36.0% following placebo, and reduced to 21.6% after ICI 204219 (p < 0.01). Analysis of the time course of bronchoconstriction showed that inhibition was most marked over the latter part of the period assessed. These data indicate that the release of sulfidopeptide leukotrienes makes a major contribution to exercise-induced bronchoconstriction.

To determine whether routine assessment of peak expiratory flow (PEF) in association with a self management plan based on inhaled corticosteroid use is effective in the management of chronic asthma, 36 consecutive adult patients with asthma attending an outpatient chest clinic were admitted to an open prospective study. Patients were treated with inhaled salbutamol and beclomethasone dipropionate in an attempt to achieve normal lung function. Each patient had a "potential normal value," which was either the predicted normal or the maximum PEF value achieved by the patient, whichever was the higher. Patients measured PEF at home and if it fell by more than 30% from the potential normal value the dose of beclomethasone was doubled until PEF returned to the potential normal value, then continued at 20 mg/day for the same number of days. If PEF fell to below 150-200 l/min patients were asked to obtain emergency medical assistance. In the 30 patients who completed the trial the six months before and the six months after intervention with the self management plan were compared. There was a substantial improvement in both subjective and objective measurements of asthma severity, with a significant reduction in nights woken, days lost from work, and requirement for oral corticosteroids and a significant increase in baseline lung function. Routine measurement of PEF in association with a self management plan appears to be effective in reducing symptoms of asthma and improving lung function.

Poorly controlled severe asthma can lead to growth impairment in childhood. In children with mild asthma, it is less clear whether treatment influences growth or adrenal function. We determined in a randomized, double-blind, placebo-controlled, community-based study, the effect of inhaled beclomethasone dipropionate (BDP) 400 micrograms/day for 7 mo on the linear growth and adrenal function of 94 children 7 to 9 yr of age. Height was measured at least monthly during treatment, and adrenal function assessed by overnight urinary cortisol at baseline and after 3 and 6 mo of treatment. Mean regressed daily growth was significantly decreased during the treatment period in the BDP-treated group, 0.79 versus 1.14 mm/wk (difference 0.35 mm/wk; 95% CI -0.46 to -0.25; p < 0.0001). At the end of the 7 mo, the BDP-treated children had grown significantly less than the children on placebo: mean of 2.66 versus 3.66 cm (difference 1.0 cm; 95% CI -1.36 to -0.64 cm; p < 0.0001). Growth was significantly decreased in both males and females. During a washout period of 4 mo, there was no significant catch-up growth. BDP had no effect on overnight urinary cortisol production. BDP at a dose taken by many children significantly decreases statural growth in children with mild asthma, and this effect is unlikely to be mediated through the hypothalamo-pituitary-adrenal axis.

Study objective To determine baseline characteristics predictive of response to omalizumab, an anti-IgE antibody, in patients with allergic asthma. Design Pooled analysis of two multicenter, double-blind, randomized, placebo-controlled phase III studies with omalizumab. Patients One thousand seventy allergic asthma patients symptomatic despite moderate-to-high doses (mean, 725 μg/d) of inhaled beclomethasone dipropionate (BDP). Interventions Omalizumab (n = 542) or placebo (n = 528) were administered at a 4-weekly subcutaneous dose of at least 0.016 mg/kg/IgE (IU/mL) for 16 weeks in addition to stable BDP therapy. Measurements and results Univariate logistic regression was performed to explore baseline variables predictive of best response. Various aspects of response (reduced symptom scores, reduced usage of rescue medication, improved lung function, improved quality of life [QoL]) were explored as well as a composite definition of response (response in at least one of these four aspects with no asthma exacerbation during 16 weeks of treatment). Time to onset of response as well as the ability to predict eventual response were also determined for the composite definition of response. A consistent pattern of predictive covariates was seen over all definitions of response (except for QoL). For the composite definition, a history of emergency asthma treatment in the past year was the factor most predictive (p = 0.015) of best response on active treatment (response rate for those with such history was 67% for omalizumab and 42% for placebo; for those without a history the response rates were 63% and 54%, respectively). Another factor predictive of best response on active treatment was high BDP dose (p = 0.037; response rate for those treated with ≥ 800 μg/d was 65% for omalizumab and 40% for placebo; for those treated with < 800 μg/d, the response rates were 63% and 55%, respectively). A low FEV1 was also predictive (p = 0.072; response rates for those with FEV1 ≤ 65% predicted were 60% for omalizumab and 40% for placebo; for those with FEV1 ≥ 65% predicted, the response rates were 67% and 53%, respectively). Seventy-six percent of patients had at least one of these factors. This subgroup showed odds of being a responder (composite definition) 2.25 times higher (95% confidence interval, 1.68 to 3.01) than placebo. Some 38% of patients treated with omalizumab showed a response (composite definition) at the first evaluation time point at 4 weeks, increasing to 64% at week 16 (vs 48% for placebo; p < 0.001). Among omalizumab responders at 16 weeks, only 61% had responded at 4 weeks whereas 87% had responded at 12 weeks. Conclusions Patients who benefit most when omalizumab is administered as add-on therapy are those receiving high doses of BDP, those with a history of frequent emergency asthma treatment, and those with poor lung function. Patients should be treated with omalizumab for a minimum duration of 12 weeks. To determine baseline characteristics predictive of response to omalizumab, an anti-IgE antibody, in patients with allergic asthma. Pooled analysis of two multicenter, double-blind, randomized, placebo-controlled phase III studies with omalizumab. One thousand seventy allergic asthma patients symptomatic despite moderate-to-high doses (mean, 725 μg/d) of inhaled beclomethasone dipropionate (BDP). Omalizumab (n = 542) or placebo (n = 528) were administered at a 4-weekly subcutaneous dose of at least 0.016 mg/kg/IgE (IU/mL) for 16 weeks in addition to stable BDP therapy. Univariate logistic regression was performed to explore baseline variables predictive of best response. Various aspects of response (reduced symptom scores, reduced usage of rescue medication, improved lung function, improved quality of life [QoL]) were explored as well as a composite definition of response (response in at least one of these four aspects with no asthma exacerbation during 16 weeks of treatment). Time to onset of response as well as the ability to predict eventual response were also determined for the composite definition of response. A consistent pattern of predictive covariates was seen over all definitions of response (except for QoL). For the composite definition, a history of emergency asthma treatment in the past year was the factor most predictive (p = 0.015) of best response on active treatment (response rate for those with such history was 67% for omalizumab and 42% for placebo; for those without a history the response rates were 63% and 54%, respectively). Another factor predictive of best response on active treatment was high BDP dose (p = 0.037; response rate for those treated with ≥ 800 μg/d was 65% for omalizumab and 40% for placebo; for those treated with < 800 μg/d, the response rates were 63% and 55%, respectively). A low FEV1 was also predictive (p = 0.072; response rates for those with FEV1 ≤ 65% predicted were 60% for omalizumab and 40% for placebo; for those with FEV1 ≥ 65% predicted, the response rates were 67% and 53%, respectively). Seventy-six percent of patients had at least one of these factors. This subgroup showed odds of being a responder (composite definition) 2.25 times higher (95% confidence interval, 1.68 to 3.01) than placebo. Some 38% of patients treated with omalizumab showed a response (composite definition) at the first evaluation time point at 4 weeks, increasing to 64% at week 16 (vs 48% for placebo; p < 0.001). Among omalizumab responders at 16 weeks, only 61% had responded at 4 weeks whereas 87% had responded at 12 weeks. Patients who benefit most when omalizumab is administered as add-on therapy are those receiving high doses of BDP, those with a history of frequent emergency asthma treatment, and those with poor lung function. Patients should be treated with omalizumab for a minimum duration of 12 weeks.

Particulate matter (PM) pollution adversely affects the airways, with asthmatic subjects thought to be especially sensitive. The authors hypothesised that exposure to diesel exhaust (DE), a major source of PM, would induce airway neutrophilia in healthy subjects, and that either these responses would be exaggerated in subjects with mild allergic asthma, or DE would exacerbate pre-existent allergic airways. Healthy and mild asthmatic subjects were exposed for 2 h to ambient levels of DE (particles with a 50% cut-off aerodynamic diameter of 10 microm (PM10) 108 microg x m(-3)) and lung function and airway inflammation were assessed. Both groups showed an increase in airway resistance of similar magnitude after DE exposure. Healthy subjects developed airway inflammation 6 h after DE exposure, with airways neutrophilia and lymphocytosis together with an increase in interleukin-8 (IL-8) protein in lavage fluid, increased IL-8 messenger ribonucleic acid expression in the bronchial mucosa and upregulation of the endothelial adhesion molecules. In asthmatic subjects, DE exposure did not induce a neutrophilic response or exacerbate their pre-existing eosinophilic airway inflammation. Epithelial staining for the cytokine IL-10 was increased after DE in the asthmatic group. Differential effects on the airways of healthy subjects and asthmatics of particles with a 50% cut-off aerodynamic diameter of 10 microm at concentrations below current World Health Organisation air quality standards have been observed in this study. Further work is required to elucidate the significance of these differential responses.

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Summary The prevalence of allergic respiratory diseases such as bronchial asthma has increased in recent years, especially in industrialized countries. A change in the genetic predisposition is an unlikely cause of the increase in allergic diseases because genetic changes in a population require several generations. Consequently, this increase may be explained by changes in environmental factors, including indoor and outdoor air pollution. Over the past two decades, there has been increasing interest in studies of air pollution and its effects on human health. Although the role played by outdoor pollutants in allergic sensitization of the airways has yet to be clarified, a body of evidence suggests that urbanization, with its high levels of vehicle emissions, and a westernized lifestyle are linked to the rising frequency of respiratory allergic diseases observed in most industrialized countries, and there is considerable evidence that asthmatic persons are at increased risk of developing asthma exacerbations with exposure to ozone, nitrogen dioxide, sulphur dioxide and inhalable particulate matter. However, it is not easy to evaluate the impact of air pollution on the timing of asthma exacerbations and on the prevalence of asthma in general. As concentrations of airborne allergens and air pollutants are frequently increased contemporaneously, an enhanced IgE‐mediated response to aeroallergens and enhanced airway inflammation could account for the increasing frequency of allergic respiratory allergy and bronchial asthma. Pollinosis is frequently used to study the interrelationship between air pollution and respiratory allergy. Climatic factors (temperature, wind speed, humidity, thunderstorms, etc) can affect both components (biological and chemical) of this interaction. By attaching to the surface of pollen grains and of plant‐derived particles of paucimicronic size, pollutants could modify not only the morphology of these antigen‐carrying agents but also their allergenic potential. In addition, by inducing airway inflammation, which increases airway permeability, pollutants overcome the mucosal barrier and could be able to ‘prime’ allergen‐induced responses. There are also observations that a thunderstorm occurring during pollen season can induce severe asthma attacks in pollinosis patients. After rupture by thunderstorm, pollen grains may release part of their cytoplasmic content, including inhalable, allergen‐carrying paucimicronic particles.

Rhinoviruses and enteroviruses are the major members of the picornavirus genus that cause human disease. We compared the polymerase chain reaction and viral culture for the identification of picornaviruses in nasal aspirates from children during episodes of respiratory symptoms and when asymptomatic and from asymptomatic adults. One hundred eight children, aged 9 to 11 years, completed a year-long study. Within 24 to 48 h of a report of respiratory symptoms, a nasal aspirate was taken in the home. Nasal aspirates were also taken from 65 of the children and from 33 normal adults when they had been free of respiratory symptoms for at least 2 weeks. Picornaviruses were isolated by culture for three passages in Ohio HeLa cells in rolling tubes at 33 degrees C and pH 7.0. For the polymerase chain reaction, duplicate 50-microliters samples were amplified with conserved primers from the 5' noncoding region. Picornaviruses generated approximately 380-bp bands in agarose gel electrophoresis; the specificity of these bands was confirmed by filter hybridization with a conserved internal probe. Picornaviruses were isolated by culture in 47 (46 rhinoviruses) of 292 symptomatic episodes (16%), whereas the polymerase chain reaction identified picornavirus genomic material in 146 episodes (50%), including all but one of the culture-positive episodes. As for asymptomatic samples, eight (12%) children and two (4%) adults were positive by the polymerase chain reaction, whereas only one child's specimen was positive by culture. This polymerase chain reaction assay represents a clear advance in the identification of picornavirus infection, with a detection rate threefold greater than the virus culture method.

We describe a guinea pig model of asthma in which animals were sensitized and challenged by inhalation of aerosolized ovalbumin. Challenge was performed under cover of mepyramine (10 mg/kg) to allow a high enough concentration of ovalbumin to elicit consistent late responses. Airway resistance and thoracic gas volume of conscious guinea pigs was assessed by whole body plethysmography before and at regular intervals for as long as 72 h after challenge. At the same time points, cellular changes in the lung were assessed by both examination of cells recovered by bronchoalveolar lavage (BAL) and lung histology. There were no significant changes in specific airway conductance (SGaw), BAL cell content or lung histology in animals challenged with saline control. Challenge with 2% ovalbumin caused an early fall in SGaw, which peaked at 2 h and amounted to a 43.7 +/- 4.1% fall from baseline. This was followed by 2 late responses, the first reaching maximum at 17 h with a 46.9 +/- 4.5% decrease in SGaw from baseline and the second at 72 h with a 39.0 +/- 3.5% fall in SGaw. Examination of BAL fluid revealed a 7-fold increase in neutrophils at 6 h and a 17-fold increase at 17 h, after which numbers decreased to baseline. Eosinophilia developed more slowly, being insignificant at 6 h and 6-fold at 17 h; by 72 h, eosinophils constituted 48.9 +/- 6.9% of the total cells recovered. No changes in mononuclear cells or lymphocytes were observed. Histologic examination of the lung revealed a progressive eosinophil infiltration of the airways, but not alveoli or vascular bed. Electron microscopy showed degranulation of eosinophils recovered by BAL and discharge of mucus from goblet cells in the trachea. Because these changes are similar to those that occur after allergen challenge in human asthma, we suggest that this represents a useful animal model in which to study the mechanism of early and late bronchoconstriction responses.

Human rhinoviruses (HRV) cause the majority of common colds and are etiologically linked with changes in lower airways physiology and asthma exacerbations. We hypothesized that changes in bronchial mucosal inflammatory cell populations may be responsible for HRV-induced changes in airway reactivity. We examined bronchial mucosal biopsies during experimental infections with HRV serotype 16 and measured changes in histamine reactivity. Seventeen adult volunteers (six atopic asthmatics) had baseline measurements of histamine reactivity and fiberoptic bronchoscopic biopsies, followed 2 wk later by viral inoculation. Further bronchial biopsies were taken on Day 4 of the infection and 6 to 10 wk later. Mast cells, eosinophils, lymphocytes, and neutrophils were quantified by immunohistochemical techniques. Infection was documented by viral culture, seroconversion, and symptoms. An increase in histamine responsiveness during the cold (p = 0.048) was accompanied by increases in submucosal lymphocytes (p = 0.050). There was a subsequent decrease in submucosal and epithelial lymphocytes in convalescence (p = 0.028; p = 0.030). There was an increase in epithelial eosinophils with the cold (p = 0.042), and in asthmatics this appeared to persist into convalescence. A peripheral blood lymphopenia correlated with increased responsiveness (r = 0.062, p = 0.014). Rhinoviral colds are associated with a bronchial mucosal lymphocytic and eosinophilic infiltrate that may be related to changes in airway responsiveness and asthma exacerbations.

There is extensive pharmacological and physiological evidence that endothelin-1 influences airway calibre. In mammals, endothelin receptors occur on airway smooth muscle, local storage and release of the peptide have been demonstrated, and inhalation of endothelin-1 induces bronchoconstriction. To investigate the relation between endothelins and asthma the expression of this peptide in endobronchial biopsy specimens was examined immunohistochemically with an antiserum against endothelin-1. Biopsy specimens from 17 asthmatic patients and 11 atopic and non-atopic healthy controls revealed striking differences, with endothelin expression being evident in airways epithelium and vascular endothelium in 11 of the 17 asthmatic patients but in only 1 of 11 controls. These results suggest that endothelins may play a part in the exaggerated bronchomotor tone of asthma.

Abnormal apoptotic mechanisms are associated with disease pathogenesis. Because the asthmatic bronchial epithelium is characteristically damaged with loss of columnar epithelial cells, we postulated that this is due to unscheduled apoptosis. Using an antibody directed toward the caspase cleavage product of poly(ADP-ribose) polymerase, immunohistochemistry applied to endobronchial biopsies showed higher levels of staining in the bronchial epithelium of subjects with asthma as compared with normal control subjects (% epithelial staining [median (range) = 10.5 (1.4-24.5) versus 0.4 (0.0-9.7)]; P < 0.001). Because we were unable to determine whether this difference was due to ongoing inflammation in vivo, cultures of normal and asthmatic bronchial epithelial cells were used to study apoptosis in vitro. In complete growth medium, these cells showed no difference in their rate of proliferation or viability. However, cells from subjects with asthma were more susceptible to the apoptotic effects of H2O2 than cells from normal control subjects (% apoptotic cells = 32.2 [8.8-54.9] versus 14.3 [6.4-24.7]; P < 0.05), even though both were similarly affected by treatment with actinomycin D. These data indicate that the susceptibility of asthmatic bronchial epithelium to oxidants is greater than normal. This susceptibility may contribute to the rising trends in asthma associated with air pollution and diets low in antioxidants.

The effects of the long-acting beta 2-agonist salmeterol on early and late phase airways events provoked by inhaled allergen were assessed in a group of atopic asthmatic patients. In a placebo-controlled study, salmeterol 50 micrograms inhaled before allergen challenge ablated both the early and late phase of allergen-induced bronchoconstriction over a 34 h time period. Salmeterol also completely inhibited the allergen-induced rise in non-specific bronchial responsiveness over the same time period. These effects were shown to be unrelated to prolonged bronchodilatation or functional antagonism. These data suggest novel actions for topically active long-acting beta 2-agonists in asthma that extend beyond their protective action on airways smooth muscle.

A cohort of 67 babies at risk of developing atopic disorders was followed up prospectively for 11 years. Clinical assessment and skin prick allergen sensitivity testing were performed annually over the first five years. At 11 years the cohort was restudied, symptoms were assessed by questionnaire, and bronchial reactivity (BHR) to histamine was measured. On the basis of skin testing, 35 children were atopic and 32 remained non-atopic. The expression of atopy increased with age. The lifetime prevalence of eczema, wheeze, and hay fever were 46%, 63%, and 56% respectively. The yearly period prevalence of hay fever increased with age, that of eczema declined, while that for wheeze showed a bimodal distribution with a peak before the age of 2 years and a gradual increase thereafter. Of the 21 children who wheezed before their second birthday, most never wheezed again and did not show BHR at 11 years. Of the 21 children whose first wheezing was after 2 years of age, 17 were still wheezing at 11 years and 12 showed BHR. Of the children who wheezed before 2 years of age, 10 were or became atopic, compared with 20 of the 23 children who wheezed at 11 years. These findings suggest that childhood asthma is a heterogeneous condition with atopy being strongly associated with the persistence of wheeze.

Summary Omalizumab is a humanized monoclonal anti‐IgE antibody developed for the treatment of allergic disease, with established efficacy in patients with moderate‐to‐severe allergic asthma and in patients with intermittent (seasonal) and persistent (perennial) allergic rhinitis (AR). Omalizumab is known to result in a marked reduction in serum levels of free IgE and down‐regulation of IgE receptors on circulating basophils. Recent work has shed further light on its mechanism of action, showing significant and profound reductions in tissue (nasal and bronchial) eosinophils and in bronchial IgE + cells (mast cells), as well as T cells and B cells. Omalizumab treatment was also shown to be associated with down‐regulation of IgE receptors on circulating (precursor) dendritic cells, suggesting that blocking IgE may inhibit more chronic aspects of allergic inflammation involving T cell activation. Further work with omalizumab demonstrated it to have important benefits in patients with poorly controlled asthma despite high‐dose inhaled corticosteroid therapy, and analysis of clinical data suggests that the patients who are the best ‘responders’ to anti‐IgE treatment are those with asthma at the more severe end of the spectrum. Notably, systemic anti‐IgE therapy with omalizumab has been shown to improve symptoms, quality of life and disease control (asthma exacerbations) in patients with concomitant asthma and persistent AR. These impressive clinical data and the studies elucidating the anti‐inflammatory profile of omalizumab also serve to emphasize the fundamental importance of IgE in the pathogenesis of allergic diseases.

The contribution of nonspecific bronchial reactivity to the day-to-day clinical expression of asthma is uncertain. We have examined this relationship in a longitudinal study of eight children and 12 adults. Measurements of reactivity to methacholine were made every 2 to 3 wk over a period of 12 to 18 months, deriving the dose that caused a 20% fall in FEV1 (PD20). Throughout the study, all patients kept a daily record of symptoms and treatment and twice daily measurements of peak expiratory flow (PEF). A significant relationship was found between subjects' overall reactivity (median PD20) and both their average day-to-day variation in morning PEF (Spearman's rho = −0.53, p = 0.016) and diurnal variation in PEF (Spearman's rho = −0.60, p = 0.004). However, examining the temporal relationship between reactivity and asthma within subjects, individual PD20 measurements were not consistently related to concurrent asthma severity: in only six subjects did changes in PD20 generally reflect simultaneous trends in symptoms or PEF. In several patients, exacerbations of asthma occurred in the absence of bronchial hyperreactivity (PD20 > 12.8 µmol). We conclude that nonspecific bronchial reactivity is only one mechanism underlying airflow obstruction in asthma, and that its relationship to the clinical state of asthma is not sufficiently close to be of practical clinical use.

We have examined the mucosal changes occurring in bronchial biopsies from six atopic asthmatics 5-6 h after local endobronchial allergen challenge and compared them with biopsies from saline-challenged segments from the same subjects at the same time point. All the subjects developed localized bronchoconstriction in the allergen-challenged segment and had a decrease in forced expiratory volume in 1 s (FEV1) (P < 0.01) and a decrease in their methacholine provocative concentration of agonist required to reduce FEV1 from baseline by 20% (P < 0.05) 24 h postchallenge. At 6 h we observed an increase in neutrophils (P = 0.03), eosinophils (P = 0.025), mast cells (P = 0.03), and CD3+ lymphocytes (P = 0.025), but not in CD4+ or CD8+ lymphocyte counts. We also detected an increase in endothelial intercellular adhesion molecule type 1 (P < 0.05) and E-selectin (P < 0.005), but not vascular cell adhesion molecule type 1 expression with a correlative increase in submucosal and epithelial LFA+ leucocytes (P < 0.01). Thus, in sensitized asthmatics, local endobronchial allergen instillation leads to an increased inflammatory cell infiltrate of the airway mucosa that involves upregulation of specific adhesion molecules expressed on the microvasculature.

Epithelial damage and airway remodeling are consistent features of bronchial asthma and are correlated with disease chronicity, severity, and bronchial hyperreactivity. To examine the mechanisms that control bronchial epithelial repair, we investigated expression of the epidermal growth factor receptor (c-erbB1, EGFR) in asthmatic bronchial mucosa and studied repair responses in vitro. In biopsies from asthmatic subjects, areas of epithelial damage were frequently observed and exhibited strong EGFR immunostaining. EGFR expression was also high in morphologically intact asthmatic epithelium. Using image analysis, EGFR immunoreactivity (% of total epithelial area, median (range) was found to increase from 9.4 (4.1-20.4) in normal subjects (n=10) to 18.4 (9.3-28.9) in mild asthmatics (P<0.01, n=13) and 25.4 (15.4-31.8) in severe asthmatics (P<0.00, n=5). Epithelial EGFR immunoreactivity remained elevated in patients treated with corticosteroids and was positively correlated with subepithelial reticular membrane thickening. Using 16HBE 14o- bronchial epithelial cells, we found that EGF accelerated repair of scrape-wounded monolayers and that the EGFR-selective inhibitor, tyrphostin AG1478, inhibited both EGF-stimulated and basal wound closure whereas dexamethasone was without effect. Intrinsic activation of the EGFR was confirmed by analysis of tyrosine phosphorylated proteins, which revealed a rapid, damage-induced phosphorylation of the EGFR, irrespective of the presence of exogenous EGF. To assess the relationship between EGFR-mediated repair and tissue remodeling, release of the profibrogenic mediator TGF-β2 was also measured. Scrape wounding increased release of TGF-β2 from epithelial monolayers and EGF had no additional stimulatory effect. However, when repair was retarded with AG1478, the amount of TGF-β2 increased significantly. These data indicate that the EGFR may play an important role in bronchial epithelial repair in asthma and that impairment of this function may augment airway remodeling.—Puddicombe, S. M., Polosa, R., Richter, A., Krishna, M. T., Howarth, P. H., Holgate, S. T., Davies, D. E. Involvement of the epidermal growth factor receptor in epithelial repair in asthma. FASEB J. 14, 1362–1374 (2000)

Although Th-2-mediated inflammation is a key therapeutic target in asthma, its relationship to altered structure and functions of the airways is largely unknown. In addition to inflammation, asthma is a disorder involving the airway epithelium that is more vulnerable to environmental injury and responds to this by impaired healing. This establishes a chronic wound scenario that is capable of sustaining chronic inflammation as well as remodeling. This response occurs as a consequence of activation of the epithelial-mesenchymal unit, involving reciprocal activities of growth factors belonging to the fibroblast growth factor, epidermal growth factor, and transforming growth factor-beta families. The observation that structural changes in the airways in children at or before the onset of asthma occurs irrespective of inflammation might suggest that premodeling is required before Th-2 inflammatory responses can be sustained. Once established, altered function of constitutive airway cells, including fibroblasts, smooth muscle, nerves, and the epithelium, provides an abnormal microenvironment in which to generate a separate set of signals that underpin the acute/subacute inflammation characteristic of asthma exacerbations, triggered by viruses, pollutants, and allergens.

Increased Th2 cytokine production in asthma is widely accepted, but excess production by asthmatic human airway CD4(+) T cells has not been demonstrated, nor has a relationship with disease severity. The importance of airway CD8(+) T cell type 1 and type 2 cytokine production in asthma is unknown. We investigated frequencies of IFN-gamma, interleukin (IL)-4 and IL-5 producing CD4(+) and CD8(+) blood and sputum T cells from normal subjects and subjects with asthma and compared between cell subsets, subject groups, and body compartments with and without in vitro stimulation and investigated relationships between cytokine production and asthma severity. Production of IL-4, IL-5, and IFN-gamma by unstimulated sputum CD4(+) and CD8(+) T cells was increased in subjects with asthma and related to disease severity, more for CD8(+) than for CD4(+) T cells. Frequencies of sputum CD8(+) T cells producing type 1 and type 2 cytokines were similar to those of CD4(+) T cells. In vitro stimulation polarized peripheral blood cytokine production toward IFN-gamma production, significantly more in subjects with asthma than in normal subjects. These data demonstrate increased type 1 and 2 cytokine production in CD4(+) and CD8(+) T cells in sputum and relate production to disease severity. Findings in blood did not reflect those in airways.

Omalizumab (Xolair) is a recombinant humanized monoclonal anti-IgE antibody with proven efficacy in patients with moderate-to-severe and severe persistent allergic (IgE-mediated) asthma.To review clinical study data to assess the safety profile of omalizumab.We analysed the safety of omalizumab using data from completed clinical studies (up to 1 year) involving more than 7500 patients with asthma, rhinitis or related conditions and up to 4 years in one study of patients with severe allergic asthma, as well as post-marketing safety data. Analysis focuses on the risk of immune-system effects, hypersensitivity reactions, malignant neoplasia, parasitic infections and thrombocytopenia.Omalizumab exhibited a good safety and tolerability profile that was maintained up to 4 years in one study. The incidence of anaphylaxis was 0.14% in omalizumab-treated patients and 0.07% in control patients. No omalizumab-treated patient developed measurable anti-omalizumab antibodies. Post-marketing, based on estimated exposure of 57,300 patients (June 2003-December 2006), the frequency of anaphylaxis attributed to omalizumab use was estimated to be at least 0.2% of patients. Current clinical trial data do not support an increased risk of malignant neoplasia or thrombocytopenia with omalizumab.Data indicate that the proven efficacy of add-on omalizumab in patients with moderate-to-severe or severe allergic asthma is accompanied by a favourable safety and tolerability profile.

This study describes the natural history of atopic and wheezy disorders from birth to adult life in a cohort at risk of atopy. One hundred subjects born in Poole, England, were selected at birth in 1976 on the basis that at least one parent was atopic. Subjects were examined annually in the preschool years, and at the ages of 11 and 22 yr. Skin prick tests and total serum immunoglobulin E (IgE) were performed at each visit, and at 11 and 22 yr, bronchial hyperresponsiveness (BHR) to inhaled histamine was measured. Sixty-three subjects remained on follow-up at 22 yr. The annual prevalence of both wheeze and atopy increased with age. Twenty-five percent of adults showed both wheeze and BHR (asthma). Remission of wheeze was common in subjects younger than 5 yr of age and likely if wheezing occurred on less than two occasions, but wheeze at 11 yr was likely to persist. Sixty percent of the adult subjects with asthma developed sensitivity to common allergens by the age of 2 yr and were showing BHR by mid-childhood. Sensitization to dietary allergens occurred in infancy and waned after early childhood but predicted the early sensitization to inhalant allergens. In conclusion, adults with asthma can begin wheezing at any age but tend to sensitize early and have abnormal airway characteristics by the age of 11 yr.

Prediction of adult asthma is important, and early prevention strategies should be targeted at those most at risk. Identifying high-risk children at an early age, however, is currently difficult.We sought to determine those factors present in early life that predict an increased risk of adult asthma.A prospective cohort study of subjects at risk of asthma and atopy was undertaken in Poole, England. One hundred babies of atopic parents were recruited at birth. During the first 5 years of life, subjects were recalled annually, all respiratory events were reported, and skin prick tests and total serum IgE measurements were performed. At 11 and 22 years, bronchial hyperresponsiveness was also measured. Seventy-three subjects were followed up at 5 years, 67 at 11 years, and 63 at 22 years.Twenty-three (37%) adult subjects reported wheezing within the previous 12 months. Fifteen (25%) of these subjects showed signs of bronchial hyperresponsiveness and were regarded as asthmatic. Wheezing before the age of 2 years occurred in 28% and was not significantly related to adult asthma (odds ratio, 0.3; 95% CI, 0.03-1.7; P = .19). A positive skin prick test response to hen's egg, cow's milk, or both in the first year was independently predictive of adult asthma (odds ratio, 10.7; 95% CI, 2.1-55.1; P = .001; sensitivity, 57%; specificity, 89%).Prediction of adult asthma remains difficult. In this study of subjects at risk of atopy, skin sensitivity to hen's egg or cow's milk in the first year was predictive of adult asthma.

We have shown in nocturnal asthma that alveolar tissue eosinophils are increased at night as compared with the proximal airway, and that they correlate with the overnight decrement in lung function. As the CD4 + cell is thought to be the principal orchestrating cell in eosinophil recruitment, we evaluated its presence in the proximal and distal airways in nocturnal asthma. Eleven patients with nocturnal asthma (NA) and 10 patients with non-nocturnal asthma (NNA) underwent two bronchoscopies with proximal airway endobronchial and distal alveolar tissue transbronchial biopsy in a random order at 4:00 p.m. and at 4:00 a.m. separated by 1 wk. Immunohistochemical staining and morphometric analysis were used to determine the number of CD3 + , CD4 + , and CD8 + cells and EG2 + eosinophils per mm2 in the epithelium, lamina propria, and alveolar tissue. At 4:00 a.m., the NA group had a significantly greater number of CD4 + cells in the alveolar tissue than the NNA group (9.8 cells/ mm2 [5.6–30.8, interquartile (IQ)] versus 1.5 cells/mm2 [0–6.3, IQ], p = 0.04). Within the NA group, there were significantly greater numbers of CD3 + , CD4 + , CD8 + , and EG2 + cells in the proximal airway lamina propria than in the distal airway at both 4:00 p.m. and 4:00 a.m. There were no differences within the epithelium between the groups at either time point. Only alveolar tissue, not airway tissue, CD4 + cells correlated inversely with the percentage predicted FEV1 at 4:00 a.m. (r = − 0.68, p = 0.0018) and positively with the number of alveolar tissue EG2 + cells (r = 0.66, p = 0.01). These findings suggest that the CD4 + lymphocyte is increased in the alveolar tissue at night in nocturnal asthma as compared with non-nocturnal asthma.

This article briefly reviews the advances in our understanding of asthma with a particular focus on the role of inflammation, before providing a concise overview of current knowledge of leukotrienes in the pathophysiology of the disease. The development of leukotriene receptor antagonists and synthesis inhibitors in briefly described; and acute exercise, allergen, and aspirin challenge studies with these agents are reviewed. Clinical studies with leukotriene antagonists and inhibitors have confirmed the central role of leukotrienes in asthma pathophysiology. In conclusion, we suggest that the new generation of leukotriene receptor antagonists may be suitable as first-line therapy in patients with mild to moderate asthma. Further studies are required to determine whether the leukotriene synthesis inhibitors will be equally effective or provide any additional antiinflammatory benefit.

We have investigated the presence of regulated on activation, normal T-cell expressed and probably secreted (RANTES), macrophage inflammatory peptide-1 α (MIP-1 α ), and macrophage chemotactic peptide (MCP-1) in the bronchoalveolar lavage fluid (BALF) obtained from normal (n = 7) and stable asthmatic subjects (n = 8), and studied their kinetic release into asthmatic airways following endobronchial allergen challenge (n = 18). Measurements of RANTES, MIP-1 α , and MCP-1 in 10 times (10 × ) concentrated BALF showed that these three chemokines were present in both normal controls and stable asthmatic patients, but no significant difference between the two groups was found in the levels of the three chemokines. However, at 4 h after allergen challenge, BALF levels of RANTES, MIP-1 α , and MCP-1 were significantly increased in fluid obtained from the allergen-challenge site when compared with the saline-challenge control site (median: 175 pg/ml versus 11.5 pg/ml, 258 pg/ml versus 88 pg/ml, and 900 pg/ml versus 450 pg/ml, respectively). At 24 h, levels of the three chemokines returned to baseline values. To investigate whether cells in BALF obtained 4 h after allergen exposure release chemokines, they were cultured for 24 h. BALF cells from the allergen site released more RANTES and MCP-1 than those from the saline site, but released similar amounts of MIP-1 α . These findings suggest that RANTES, MIP-1 α , and MCP-1 may regulate cell trafficking in asthma in response to allergen exposure.

Asthma and atopic dermatitis are epithelial disorders in which T helper 2 (Th2)-type inflammation has a prominent role. Thymic stromal lymphopoietin (TSLP) is a cytokine produced by the skin and airway epithelium that is capable of directing dendritic cells towards a Th2 response, thereby providing an essential link between epithelial cell activation and allergic-type inflammation. In addition, TSLP can interact directly with mast cells to initiate Th2 cytokine production to also provide a non-T cell route to mediate its pro-allergic effects. Induction of TSLP production occurs through the activation of epithelial Toll-like receptors to provide an important new link between innate immunity and allergic disease. Asthma and atopic dermatitis are epithelial disorders in which T helper 2 (Th2)-type inflammation has a prominent role. Thymic stromal lymphopoietin (TSLP) is a cytokine produced by the skin and airway epithelium that is capable of directing dendritic cells towards a Th2 response, thereby providing an essential link between epithelial cell activation and allergic-type inflammation. In addition, TSLP can interact directly with mast cells to initiate Th2 cytokine production to also provide a non-T cell route to mediate its pro-allergic effects. Induction of TSLP production occurs through the activation of epithelial Toll-like receptors to provide an important new link between innate immunity and allergic disease.

Rationale: The molecular mechanisms involved in airway oxidative stress responses reported in healthy smokers and in those with chronic obstructive pulmonary disease (COPD) are poorly understood.Objectives: To assess the expression of genes involved in oxidative stress responses in the bronchial epithelium of smokers with or without COPD and in relation to disease severity.Methods: Global gene expression was assessed in bronchial brushings in 38 subjects with COPD, 14 healthy nonsmokers, and 18 healthy smokers.Results: Gene expression analysis using Affymetrix arrays revealed mRNAs representing 341 out of 642 oxidative stress genes from two predefined gene sets to be differentially expressed in healthy nonsmokers when compared with healthy smokers, and 200 differentially expressed oxidative genes in subjects with COPD when compared with healthy smokers. Gene set enrichment analysis showed that pathways involved in oxidant/antioxidant responses were among the most differentially expressed gene pathways in smoking individuals, with further differences seen in COPD. Distinct, nonlinear gene expression patterns were identified across the severity spectrum of COPD, which correlated with the presence of certain transcription factor binding sites in their promoters. Significant changes in oxidant response genes observed in vivo were reproduced in vitro using primary bronchial epithelial cells from the same donors cultured at an air–liquid interface and exposed to cigarette smoke extract.Conclusions: Cigarette smoke induces significant changes in oxidant defense responses; some of these are further amplified, but not in a linear fashion, in individuals who develop COPD.

Background: In adult asthma the bronchial epithelium shows high expression of the epidermal growth factor receptor (EGFR) and the cyclin dependent kinase inhibitor, p21 waf , linked to ongoing stress and injury.Methods: To determine if these are early markers of disease, sections of bronchial specimens obtained post mortem or by bronchoscopy from non-asthmatic (n = 7), moderate (n = 7), or severe (n = 9) asthmatic children aged 5-15 years were examined immunohistochemically.All severe and one moderately asthmatic children were receiving inhaled corticosteroids.Results: The lamina reticularis of the asthmatic biopsy sections was found to be thicker (p = 0.01) than normal with increased deposition of collagen III (p = 0.007); submucosal eosinophil numbers did not differ between groups.As in adults, there was an asthma-related increase in epithelial EGFR (p,0.002) but there was no evidence of proliferation, with Ki67 being reduced (p = 0.001) and p21 waf increased (p,0.004).The thickness of the lamina reticularis was significantly correlated with epithelial EGFR (rho = 0.77, p,0.001).Conclusions: These data provide evidence that, in asthmatic children, the epithelium is stressed or injured without significant eosinophilic inflammation.This change in the epithelial phenotype is associated with collagen deposition in the lamina reticularis, suggesting that the epithelial mesenchymal trophic unit is active early in, and may contribute to, the pathogenesis of asthma.

In sensitized individuals, exposure to allergens such as Dermatophagoides pteronyssinus (Der p) causes Th2 polarization and release of cytokines, including IL-4 and IL-13. Because Der p extracts also have direct effects on epithelial cells, we hypothesized that allergen augments the effects of Th2 cytokines by promoting mediator release from the bronchial epithelium in allergic asthma. To test our hypothesis, primary bronchial epithelial cultures were grown from bronchial brushings of normal and atopic asthmatic subjects. RT-PCR showed that each culture expressed IL-4R(alpha), common gamma-chain, and IL-13R(alpha)(1), as well as IL-13R(alpha)(2), which negatively regulates IL-13 signaling; FACS analysis confirmed IL-13R(alpha)(2) protein expression. Exposure of epithelial cultures to either Der p extracts, TNF-alpha, IL-4, or IL-13 enhanced GM-CSF and IL-8 release, and this was partially suppressible by corticosteroids. Simultaneous exposure of the epithelial cultures to IL-4 or IL-13 together with Der p resulted in a further increase in cytokine release, which was at least additive. Release of TGF-alpha was also increased by TNF-alpha and combinations of IL-4, IL-13, and Der p; however, this stimulation was only significant in the asthma-derived cultures. These data suggest that, in an allergic environment, Th2 cytokines and allergen have the potential to sustain airway inflammation through a cooperative effect on cytokine release by the bronchial epithelium. Our novel finding that IL-4, IL-13, and allergen enhance release of TGF-alpha, a ligand for the epidermal growth factor receptor that stimulates fibroblast proliferation and goblet cell differentiation, provides a potential link between allergen exposure, Th2 cytokines, and airway remodelling in asthma.

Asthma is an inflammatory disorder of the conducting airways that has strong association with allergic sensitization. The disease is characterized by a polarized Th-2 (T-helper-2)-type T-cell response, but in general targeting this component of the disease with selective therapies has been disappointing and most therapy still relies on bronchodilators and corticosteroids rather than treating underlying disease mechanisms. With the disappointing outcomes of targeting individual Th-2 cytokines or manipulating T-cells, the time has come to re-evaluate the direction of research in this disease. A case is made that asthma has its origins in the airways themselves involving defective structural and functional behaviour of the epithelium in relation to environmental insults. Specifically, a defect in barrier function and an impaired innate immune response to viral infection may provide the substrate upon which allergic sensitization takes place. Once sensitized, the repeated allergen exposure will lead to disease persistence. These mechanisms could also be used to explain airway wall remodelling and the susceptibility of the asthmatic lung to exacerbations provoked by respiratory viruses, air pollution episodes and exposure to biologically active allergens. Variable activation of this epithelial-mesenchymal trophic unit could also lead to the emergence of different asthma phenotypes and a more targeted approach to the treatment of these. It also raises the possibility of developing treatments that increase the lung's resistance to the inhaled environment rather than concentrating all efforts on trying to suppress inflammation once it has become established.