Jörg H W Distler

Abstract Our previous study demonstrated increased expression of Heat shock protein (Hsp) 90 in the skin of patients with systemic sclerosis (SSc). We aimed to evaluate plasma Hsp90 in SSc and characterize its association with SSc-related features. Ninety-two SSc patients and 92 age-/sex-matched healthy controls were recruited for the cross-sectional analysis. The longitudinal analysis comprised 30 patients with SSc associated interstitial lung disease (ILD) routinely treated with cyclophosphamide. Hsp90 was increased in SSc compared to healthy controls. Hsp90 correlated positively with C-reactive protein and negatively with pulmonary function tests: forced vital capacity and diffusing capacity for carbon monoxide (DLCO). In patients with diffuse cutaneous (dc) SSc, Hsp90 positively correlated with the modified Rodnan skin score. In SSc-ILD patients treated with cyclophosphamide, no differences in Hsp90 were found between baseline and after 1, 6, or 12 months of therapy. However, baseline Hsp90 predicts the 12-month change in DLCO. This study shows that Hsp90 plasma levels are increased in SSc patients compared to age-/sex-matched healthy controls. Elevated Hsp90 in SSc is associated with increased inflammatory activity, worse lung functions, and in dcSSc, with the extent of skin involvement. Baseline plasma Hsp90 predicts the 12-month change in DLCO in SSc-ILD patients treated with cyclophosphamide.

The aim was to update the 2009 European League against Rheumatism (EULAR) recommendations for the treatment of systemic sclerosis (SSc), with attention to new therapeutic questions. Update of the previous treatment recommendations was performed according to EULAR standard operating procedures. The task force consisted of 32 SSc clinical experts from Europe and the USA, 2 patients nominated by the pan-European patient association for SSc (Federation of European Scleroderma Associations (FESCA)), a clinical epidemiologist and 2 research fellows. All centres from the EULAR Scleroderma Trials and Research group were invited to submit and select clinical questions concerning SSc treatment using a Delphi approach. Accordingly, 46 clinical questions addressing 26 different interventions were selected for systematic literature review. The new recommendations were based on the available evidence and developed in a consensus meeting with clinical experts and patients. The procedure resulted in 16 recommendations being developed (instead of 14 in 2009) that address treatment of several SSc-related organ complications: Raynaud's phenomenon (RP), digital ulcers (DUs), pulmonary arterial hypertension (PAH), skin and lung disease, scleroderma renal crisis and gastrointestinal involvement. Compared with the 2009 recommendations, the 2016 recommendations include phosphodiesterase type 5 (PDE-5) inhibitors for the treatment of SSc-related RP and DUs, riociguat, new aspects for endothelin receptor antagonists, prostacyclin analogues and PDE-5 inhibitors for SSc-related PAH. New recommendations regarding the use of fluoxetine for SSc-related RP and haematopoietic stem cell transplantation for selected patients with rapidly progressive SSc were also added. In addition, several comments regarding other treatments addressed in clinical questions and suggestions for the SSc research agenda were formulated. These updated data-derived and consensus-derived recommendations will help rheumatologists to manage patients with SSc in an evidence-based way. These recommendations also give directions for future clinical research in SSc.

The transforming growth factor-β (TGF-β) signalling pathway is a key mediator of fibroblast activation that drives the aberrant synthesis of extracellular matrix in fibrotic diseases. Here we demonstrate a novel link between transforming growth factor-β and the canonical Wnt pathway. TGF-β stimulates canonical Wnt signalling in a p38-dependent manner by decreasing the expression of the Wnt antagonist Dickkopf-1. Tissue samples from human fibrotic diseases show enhanced expression of Wnt proteins and decreased expression of Dickkopf-1. Activation of the canonical Wnt pathway stimulates fibroblasts in vitro and induces fibrosis in vivo. Transgenic overexpression of Dickkopf-1 ameliorates skin fibrosis induced by constitutively active TGF-β receptor type I signalling and also prevents fibrosis in other TGF-β-dependent animal models. These findings demonstrate that canonical Wnt signalling is necessary for TGF-β-mediated fibrosis and highlight a key role for the interaction of both pathways in the pathogenesis of fibrotic diseases.

To investigate the role of microRNA (miRNA) as posttranscriptional regulators of profibrotic genes in systemic sclerosis (SSc).MicroRNA, which target collagens, were identified by in silico analysis. Expression of miRNA-29 (miR-29) was determined by TaqMan real-time polymerase chain reaction analysis of skin biopsy and fibroblast samples from SSc patients and healthy controls as well as in the mouse model of bleomycin-induced skin fibrosis. Cells were transfected with precursor miRNA (pre-miRNA)/anti-miRNA of miR-29 using Lipofectamine. Collagen gene expression was also studied in luciferase reporter gene assays. For stimulation, recombinant transforming growth factor beta (TGFbeta), platelet-derived growth factor B (PDGF-B), or interleukin-4 (IL-4) was used. The effects of inhibiting PDGF-B and TGFbeta signaling on the levels of miR-29 were studied in vitro and in the bleomycin model.We found that miR-29a was strongly down-regulated in SSc fibroblasts and skin sections as compared with the healthy controls. Overexpression in SSc fibroblasts significantly decreased, and accordingly, knockdown in normal fibroblasts increased, the levels of messenger RNA and protein for type I and type III collagen. In the reporter gene assay, cotransfection with pre-miR-29a significantly decreased the relative luciferase activity, which suggests a direct regulation of collagen by miR-29a. TGFbeta, PDGF-B, or IL-4 reduced the levels of miR-29a in normal fibroblasts to those seen in SSc fibroblasts. Similar to human SSc, the expression of miR-29a was reduced in the bleomycin model of skin fibrosis. Inhibition of PDGF-B and TGFbeta pathways by treatment with imatinib restored the levels of miR-29a in vitro and in the bleomycin model in vivo.These data add the posttranscriptional regulation of collagens by miR-29a as a novel aspect to the fibrogenesis of SSc and suggest miR-29a as a potential therapeutic target.

Objectives To determine the causes of death and risk factors in systemic sclerosis (SSc). Methods Between 2000 and 2011, we examined the death certificates of all French patients with SSc to determine causes of death. Then we examined causes of death and developed a score associated with all-cause mortality from the international European Scleroderma Trials and Research (EUSTAR) database. Candidate prognostic factors were tested by Cox proportional hazards regression model by single variable analysis, followed by a multiple variable model stratified by centres. The bootstrapping technique was used for internal validation. Results We identified 2719 French certificates of deaths related to SSc, mainly from cardiac (31%) and respiratory (18%) causes, and an increase in SSc-specific mortality over time. Over a median follow-up of 2.3 years, 1072 (9.6%) of 11 193 patients from the EUSTAR sample died, from cardiac disease in 27% and respiratory causes in 17%. By multiple variable analysis, a risk score was developed, which accurately predicted the 3-year mortality, with an area under the curve of 0.82. The 3-year survival of patients in the upper quartile was 53%, in contrast with 98% in the first quartile. Conclusion Combining two complementary and detailed databases enabled the collection of an unprecedented 3700 deaths, revealing the major contribution of the cardiopulmonary system to SSc mortality. We also developed a robust score to risk-stratify these patients and estimate their 3-year survival. With the emergence of new therapies, these important observations should help caregivers plan and refine the monitoring and management to prolong these patients’ survival.

Abstract Objective Imatinib mesylate is a clinically well‐tolerated small molecule inhibitor that exerts selective, dual inhibition of the transforming growth factor β (TGFβ) and platelet‐derived growth factor (PDGF) pathways. This study was undertaken to test the potential use of imatinib mesylate as an antifibrotic drug for the treatment of dermal fibrosis in systemic sclerosis (SSc). Methods The expression of extracellular matrix (ECM) proteins in SSc and normal dermal fibroblasts was analyzed by real‐time polymerase chain reaction, Western blot, and Sircol collagen assay. Proliferation capacity was assessed with the MTT assay. Cell viability was analyzed by mitochondrial membrane potential and by annexin V/propidium iodide staining. Bleomycin‐induced experimental dermal fibrosis was used to assess the antifibrotic effects of imatinib mesylate in vivo. Results Imatinib mesylate efficiently reduced basal synthesis of COL1A1, COL1A2, and fibronectin 1 messenger RNA in SSc and normal dermal fibroblasts, in a dose‐dependent manner. The induction of ECM proteins after stimulation with TGFβ and PDGF was also strongly and dose‐dependently inhibited by imatinib mesylate. These results were confirmed at the protein level. Imatinib mesylate did not alter proliferation or induce apoptosis and necrosis in dermal fibroblasts. Consistent with the in vitro findings, imatinib mesylate reduced dermal thickness, the number of myofibroblasts, and synthesis of ECM proteins in experimental dermal fibrosis, without evidence of toxic side effects. Conclusion These data show that imatinib mesylate at biologically relevant concentrations has potent antifibrotic effects in vitro and in vivo, without toxic side effects. Considering its favorable pharmacokinetics and clinical experience with its use in other diseases, imatinib mesylate is a promising candidate for the treatment of fibrotic diseases such as SSc.

Objectives To assess the effects of Rituximab (RTX) on skin and lung fibrosis in patients with systemic sclerosis (SSc) belonging to the European Scleroderma Trial and Research (EUSTAR) cohort and using a nested case-control design. Methods Inclusion criteria were fulfilment of American College of Rheumatology classification criteria for SSc, treatment with RTX and availability of follow-up data. RTX-treated patients were matched with control patients from the EUSTAR database not treated with RTX. Matching parameters for skin/lung fibrosis were the modified Rodnan Skin Score (mRSS), forced vital capacity (FVC), follow-up duration, scleroderma subtype, disease duration and immunosuppressive co-treatment. The primary analysis was mRSS change from baseline to follow-up in the RTX group compared with the control group. Secondary analyses included change of FVC and safety measures. Results 63 patients treated with RTX were included in the analysis. The case-control analysis in patients with severe diffuse SSc showed that mRSS changes were larger in the RTX group versus matched controls (N=25; −24.0±5.2% vs −7.7±4.3%; p=0.03). Moreover, in RTX-treated patients, the mean mRSS was significantly reduced at follow-up compared with baseline (26.6±1.4 vs 20.3±1.8; p=0.0001). In addition, in patients with interstitial lung disease, RTX prevented significantly the further decline of FVC compared with matched controls (N=9; 0.4±4.4% vs −7.7±3.6%; p=0.02). Safety measures showed a good profile consistent with previous studies in autoimmune rheumatic diseases. Conclusions The comparison of RTX treated versus untreated matched-control SSc patients from the EUSTAR cohort demonstrated improvement of skin fibrosis and prevention of worsening lung fibrosis, supporting the therapeutic concept of B cell inhibition in SSc.

Innate lymphoid cells (ILCs) have potent immunological functions in experimental conditions in mice, but their contributions to immunity in natural conditions in humans have remained unclear. We investigated the presence of ILCs in a cohort of patients with severe combined immunodeficiency (SCID). All ILC subsets were absent in patients with SCID who had mutation of the gene encoding the common γ-chain cytokine receptor subunit IL-2Rγ or the gene encoding the tyrosine kinase JAK3. T cell reconstitution was observed in patients with SCID after hematopoietic stem cell transplantation (HSCT), but the patients still had considerably fewer ILCs in the absence of myeloablation than did healthy control subjects, with the exception of rare cases of reconstitution of the ILC1 subset of ILCs. Notably, the ILC deficiencies observed were not associated with any particular susceptibility to disease, with follow-up extending from 7 years to 39 years after HSCT. We thus report here selective ILC deficiency in humans and show that ILCs might be dispensable in natural conditions, if T cells are present and B cell function is preserved.

Abstract Signal transducer and activator of transcription 3 (STAT3) is phosphorylated by various kinases, several of which have been implicated in aberrant fibroblast activation in fibrotic diseases including systemic sclerosis (SSc). Here we show that profibrotic signals converge on STAT3 and that STAT3 may be an important molecular checkpoint for tissue fibrosis. STAT3 signaling is hyperactivated in SSc in a TGFβ-dependent manner. Expression profiling and functional studies in vitro and in vivo demonstrate that STAT3 activation is mediated by the combined action of JAK, SRC, c-ABL, and JNK kinases. STAT3-deficient fibroblasts are less sensitive to the pro-fibrotic effects of TGFβ. Fibroblast-specific knockout of STAT3, or its pharmacological inhibition, ameliorate skin fibrosis in experimental mouse models. STAT3 thus integrates several profibrotic signals and might be a core mediator of fibrosis. Considering that several STAT3 inhibitors are currently tested in clinical trials, STAT3 might be a candidate for molecular targeted therapies of SSc.

Autophagy is a homeostatic process to recycle dispensable and damaged cell organelles. Dysregulation of autophagic pathways has recently been implicated in the pathogenesis of various diseases. Here, we investigated the role of autophagy during joint destruction in arthritis.Autophagy in osteoclasts was analysed in vitro and ex vivo by transmission electron microscopy, Western blotting and immunohistochemistry for Beclin1 and Atg7. Small molecule inhibitors, LysMCre-mediated knockout of Atg7 and lentiviral overexpression of Beclin1 were used to modulate autophagy in vitro and in vivo. Osteoclast differentiation markers were quantified by real-time PCR. The extent of bone and cartilage destruction was analysed in human tumour necrosis factor α transgenic (hTNFα tg) mice after adoptive transfer with myeloid specific Atg7-deficient bone marrow.Autophagy was activated in osteoclasts of human rheumatoid arthritis (RA) showing increased expression of Beclin1 and Atg7. TNFα potently induced the expression of autophagy-related genes and activated autophagy in vitro and in vivo. Activation of autophagy by overexpression of Beclin1-induced osteoclastogenesis and enhanced the resorptive capacity of cultured osteoclasts, whereas pharmacologic or genetic inactivation of autophagy prevented osteoclast differentiation. Arthritic hTNFα tg mice transplanted with Atg7(fl/fl)×LysMCre(+) bone marrow cells (BMC) showed reduced numbers of osteoclasts and were protected from TNFα-induced bone erosion, proteoglycan loss and chondrocyte death.These findings demonstrate that autophagy is activated in RA in a TNFα-dependent manner and regulates osteoclast differentiation and bone resorption. We thus provide evidence for a central role of autophagy in joint destruction in RA.

Vascular damage and platelet activation are associated with tissue remodeling in diseases such as systemic sclerosis, but the molecular mechanisms underlying this association have not been identified. In this study, we show that serotonin (5-hydroxytryptamine [5-HT]) stored in platelets strongly induces extracellular matrix synthesis in interstitial fibroblasts via activation of 5-HT2B receptors (5-HT2B) in a transforming growth factor β (TGF-β)–dependent manner. Dermal fibrosis was reduced in 5-HT2B−/− mice using both inducible and genetic models of fibrosis. Pharmacologic inactivation of 5-HT2B also effectively prevented the onset of experimental fibrosis and ameliorated established fibrosis. Moreover, inhibition of platelet activation prevented fibrosis in different models of skin fibrosis. Consistently, mice deficient for TPH1, the rate-limiting enzyme for 5-HT production outside the central nervous system, showed reduced experimental skin fibrosis. These findings suggest that 5-HT/5-HT2B signaling links vascular damage and platelet activation to tissue remodeling and identify 5-HT2B as a novel therapeutic target to treat fibrotic diseases.

Inflammatory diseases such as arthritis are chronic conditions that fail to resolve spontaneously. While the cytokine and cellular pathways triggering arthritis are well defined, those responsible for the resolution of inflammation are incompletely characterized. Here we identified interleukin (IL)-9-producing type 2 innate lymphoid cells (ILC2s) as the mediators of a molecular and cellular pathway that orchestrates the resolution of chronic inflammation. In mice, the absence of IL-9 impaired ILC2 proliferation and activation of regulatory T (Treg) cells, and resulted in chronic arthritis with excessive cartilage destruction and bone loss. In contrast, treatment with IL-9 promoted ILC2-dependent Treg activation and effectively induced resolution of inflammation and protection of bone. Patients with rheumatoid arthritis in remission exhibited high numbers of IL-9+ ILC2s in joints and the circulation. Hence, fostering IL-9-mediated ILC2 activation may offer a novel therapeutic approach inducing resolution of inflammation rather than suppression of inflammatory responses.

Systemic sclerosis (SSc) is an orphan, complex, inflammatory disease affecting the immune system and connective tissue. SSc stands out as a severely incapacitating and life-threatening inflammatory rheumatic disease, with a largely unknown pathogenesis. We have designed a two-stage genome-wide association study of SSc using case-control samples from France, Italy, Germany, and Northern Europe. The initial genome-wide scan was conducted in a French post quality-control sample of 564 cases and 1,776 controls, using almost 500 K SNPs. Two SNPs from the MHC region, together with the 6 loci outside MHC having at least one SNP with a P<10(-5) were selected for follow-up analysis. These markers were genotyped in a post-QC replication sample of 1,682 SSc cases and 3,926 controls. The three top SNPs are in strong linkage disequilibrium and located on 6p21, in the HLA-DQB1 gene: rs9275224, P = 9.18×10(-8), OR = 0.69, 95% CI [0.60-0.79]; rs6457617, P = 1.14×10(-7) and rs9275245, P = 1.39×10(-7). Within the MHC region, the next most associated SNP (rs3130573, P = 1.86×10(-5), OR = 1.36 [1.18-1.56]) is located in the PSORS1C1 gene. Outside the MHC region, our GWAS analysis revealed 7 top SNPs (P<10(-5)) that spanned 6 independent genomic regions. Follow-up of the 17 top SNPs in an independent sample of 1,682 SSc and 3,926 controls showed associations at PSORS1C1 (overall P = 5.70×10(-10), OR:1.25), TNIP1 (P = 4.68×10(-9), OR:1.31), and RHOB loci (P = 3.17×10(-6), OR:1.21). Because of its biological relevance, and previous reports of genetic association at this locus with connective tissue disorders, we investigated TNIP1 expression. A markedly reduced expression of the TNIP1 gene and also its protein product were observed both in lesional skin tissue and in cultured dermal fibroblasts from SSc patients. Furthermore, TNIP1 showed in vitro inhibitory effects on inflammatory cytokine-induced collagen production. The genetic signal of association with TNIP1 variants, together with tissular and cellular investigations, suggests that this pathway has a critical role in regulating autoimmunity and SSc pathogenesis.

Background Systemic sclerosis-associated interstitial lung disease (ILD) carries a high mortality risk; expert guidance is required to aid early recognition and treatment. We aimed to develop the first expert consensus and define an algorithm for the identification and management of the condition through application of well established methods. Methods Evidence-based consensus statements for systemic sclerosis-associated ILD management were established for six domains (ie, risk factors, screening, diagnosis and severity assessment, treatment initiation and options, disease progression, and treatment escalation) using a modified Delphi process based on a systematic literature analysis. A panel of 27 Europe-based pulmonologists, rheumatologists, and internists with expertise in systemic sclerosis-associated ILD participated in three rounds of online surveys, a face-to-face discussion, and a WebEx meeting, followed by two supplemental Delphi rounds, to establish consensus and define a management algorithm. Consensus was considered achieved if at least 80% of panellists indicated agreement or disagreement. Findings Between July 1, 2018, and Aug 27, 2019, consensus agreement was reached for 52 primary statements and six supplemental statements across six domains of management, and an algorithm was defined for clinical practice use. The agreed statements most important for clinical use included: all patients with systemic sclerosis should be screened for systemic sclerosis-associated ILD using high-resolution CT; high-resolution CT is the primary tool for diagnosing ILD in systemic sclerosis; pulmonary function tests support screening and diagnosis; systemic sclerosis-associated ILD severity should be measured with more than one indicator; it is appropriate to treat all severe cases; no pharmacological treatment is an option for some patients; follow-up assessments enable identification of disease progression; progression pace, alongside disease severity, drives decisions to escalate treatment. Interpretation Through a robust modified Delphi process developed by a diverse panel of experts, the first evidence-based consensus statements were established on guidance for the identification and medical management of systemic sclerosis-associated ILD. Funding An unrestricted grant from Boehringer Ingelheim International.

Transforming growth factor-β (TGF-β) is widely recognized as a core pathway of fibrosis. Inhibition of TGF-β signaling may thus offer potential for antifibrotic therapies. Long-term inhibition of TGF-β signaling at the level of its isoforms and receptors can be associated with unacceptable adverse effects. However, TGF-β regulates a myriad of intracellular signaling cascades to transmit its profibrotic effects and several of those pathways offer potential for pharmacologic intervention. Moreover, the multiple interactions of TGF-β with other profibrotic pathways also yielded candidates for therapeutic intervention. In this review, we discuss selected targets within the TGF-β pathway with high translational potential.

In this study, 1,833 systemic sclerosis (SSc) cases and 3,466 controls were genotyped with the Immunochip array. Classical alleles, amino acid residues, and SNPs across the human leukocyte antigen (HLA) region were imputed and tested. These analyses resulted in a model composed of six polymorphic amino acid positions and seven SNPs that explained the observed significant associations in the region. In addition, a replication step comprising 4,017 SSc cases and 5,935 controls was carried out for several selected non-HLA variants, reaching a total of 5,850 cases and 9,401 controls of European ancestry. Following this strategy, we identified and validated three SSc risk loci, including DNASE1L3 at 3p14, the SCHIP1-IL12A locus at 3q25, and ATG5 at 6q21, as well as a suggested association of the TREH-DDX6 locus at 11q23. The associations of several previously reported SSc risk loci were validated and further refined, and the observed peak of association in PXK was related to DNASE1L3. Our study has increased the number of known genetic associations with SSc, provided further insight into the pleiotropic effects of shared autoimmune risk factors, and highlighted the power of dense mapping for detecting previously overlooked susceptibility loci. In this study, 1,833 systemic sclerosis (SSc) cases and 3,466 controls were genotyped with the Immunochip array. Classical alleles, amino acid residues, and SNPs across the human leukocyte antigen (HLA) region were imputed and tested. These analyses resulted in a model composed of six polymorphic amino acid positions and seven SNPs that explained the observed significant associations in the region. In addition, a replication step comprising 4,017 SSc cases and 5,935 controls was carried out for several selected non-HLA variants, reaching a total of 5,850 cases and 9,401 controls of European ancestry. Following this strategy, we identified and validated three SSc risk loci, including DNASE1L3 at 3p14, the SCHIP1-IL12A locus at 3q25, and ATG5 at 6q21, as well as a suggested association of the TREH-DDX6 locus at 11q23. The associations of several previously reported SSc risk loci were validated and further refined, and the observed peak of association in PXK was related to DNASE1L3. Our study has increased the number of known genetic associations with SSc, provided further insight into the pleiotropic effects of shared autoimmune risk factors, and highlighted the power of dense mapping for detecting previously overlooked susceptibility loci.

Systemic sclerosis (SSc) is a rare and clinically heterogeneous autoimmune disorder characterised by fibrosis and microvascular obliteration of the skin and internal organs. Organ involvement mostly manifests after a variable period of the onset of Raynaud's phenomenon (RP). We aimed to map the incidence and predictors of pulmonary, cardiac, gastrointestinal (GI) and renal involvement in the early course of SSc.In the EUSTAR cohort, patients with early SSc were identified as those who had a visit within the first year after RP onset. Incident SSc organ manifestations and their risk factors were assessed using Kaplan-Meier methods and Cox regression analysis.Of the 695 SSc patients who had a baseline visit within 1 year after RP onset, the incident non-RP manifestations (in order of frequency) were: skin sclerosis (75%) GI symptoms (71%), impaired diffusing capacity for monoxide<80% predicted (65%), DU (34%), cardiac involvement (32%), FVC<80% predicted (31%), increased PAPsys>40mmHg (14%), and renal crisis (3%). In the heart, incidence rates were highest for diastolic dysfunction, followed by conduction blocks and pericardial effusion. While the main baseline risk factor for a short timespan to develop FVC impairment was diffuse skin involvement, for PAPsys>40mmHg it was higher patient age. The main risk factors for incident cardiac manifestations were anti-topoisomerase autoantibody positivity and older age. Male sex, anti-RNA-polymerase-III positivity, and older age were risk factors associated with incident renal crisis.In SSc patients presenting early after RP onset, approximately half of all incident organ manifestations occur within 2 years and have a simultaneous rather than a sequential onset. These findings have implications for the design of new diagnostic and therapeutic strategies aimed to 'widen' the still very narrow 'window of opportunity'. They may also enable physicians to counsel and manage patients presenting early in the course of SSc more accurately.

A proportion of patients with fibrosing interstitial lung diseases (ILDs) develop a progressive phenotype characterised by decline in lung function, worsening quality of life and early mortality. Other than idiopathic pulmonary fibrosis (IPF), there are no approved drugs for fibrosing ILDs and a poor evidence base to support current treatments. Fibrosing ILDs with a progressive phenotype show commonalities in clinical behaviour and in the pathogenic mechanisms that drive disease worsening. Nintedanib is an intracellular inhibitor of tyrosine kinases that has been approved for treatment of IPF and has recently been shown to reduce the rate of lung function decline in patients with ILD associated with systemic sclerosis (SSc-ILD). In vitro data demonstrate that nintedanib inhibits several steps in the initiation and progression of lung fibrosis, including the release of pro-inflammatory and pro-fibrotic mediators, migration and differentiation of fibrocytes and fibroblasts, and deposition of extracellular matrix. Nintedanib also inhibits the proliferation of vascular cells. Studies in animal models with features of fibrosing ILDs such as IPF, SSc-ILD, rheumatoid arthritis-ILD, hypersensitivity pneumonitis and silicosis demonstrate that nintedanib has anti-fibrotic activity irrespective of the trigger for the lung pathology. This suggests that nintedanib inhibits fundamental processes in the pathogenesis of fibrosis. A trial of nintedanib in patients with progressive fibrosing ILDs other than IPF (INBUILD) will report results in 2019.

Nintedanib is a tyrosine kinase inhibitor that has recently been shown to slow disease progression in idiopathic pulmonary fibrosis in two replicate phase III clinical trials. The aim of this study was to analyse the antifibrotic effects of nintedanib in preclinical models of systemic sclerosis (SSc) and to provide a scientific background for clinical trials in SSc.The effects of nintedanib on migration, proliferation, myofibroblast differentiation and release of extracellular matrix of dermal fibroblasts were analysed by microtitre tetrazolium and scratch assays, stress fibre staining, qPCR and SirCol assays. The antifibrotic effects of nintedanib were evaluated in bleomycin-induced skin fibrosis, in a murine sclerodermatous chronic graft-versus-host disease model and in tight-skin-1 mice.Nintedanib dose-dependently reduced platelet-derived growth factor-induced and transforming growth factor-β-induced proliferation and migration as well as myofibroblast differentiation and collagen release of dermal fibroblasts from patients with and healthy individuals. Nintedanib also inhibited the endogenous activation of SSc fibroblasts. Nintedanib prevented bleomycin-induced skin fibrosis in a dose-dependent manner and was also effective in the treatment of established fibrosis. Moreover, treatment with nintedanib ameliorated fibrosis in the chronic graft-versus-host disease model and in tight-skin-1 mice in well-tolerated doses.We demonstrate that nintedanib effectively inhibits the endogenous as well as cytokine-induced activation of SSc fibroblasts and exerts potent antifibrotic effects in different complementary mouse models of SSc. These data have direct translational implications for clinical trials with nintedanib in SSc.

To assess the safety and efficacy of rituximab in systemic sclerosis (SSc) in clinical practice.We performed a prospective study including patients with SSc from the European Scleroderma Trials and Research (EUSTAR) network treated with rituximab and matched with untreated patients with SSc. The main outcomes measures were adverse events, skin fibrosis improvement, lung fibrosis worsening and steroids use among propensity score-matched patients treated or not with rituximab.254 patients were treated with rituximab, in 58% for lung and in 32% for skin involvement. After a median follow-up of 2 years, about 70% of the patients had no side effect. Comparison of treated patients with 9575 propensity-score matched patients showed that patients treated with rituximab were more likely to have skin fibrosis improvement (22.7 vs 14.03 events per 100 person-years; OR: 2.79 [1.47-5.32]; p=0.002). Treated patients did not have significantly different rates of decrease in forced vital capacity (FVC)>10% (OR: 1.03 [0.55-1.94]; p=0.93) nor in carbon monoxide diffusing capacity (DLCO) decrease. Patients having received rituximab were more prone to stop or decrease steroids (OR: 2.34 [1.56-3.53], p<0.0001). Patients treated concomitantly with mycophenolate mofetil had a trend for better outcomes as compared with patients receiving rituximab alone (delta FVC: 5.22 [0.83-9.62]; p=0.019 as compared with controls vs 3 [0.66-5.35]; p=0.012).Rituximab use was associated with a good safety profile in this large SSc-cohort. Significant change was observed on skin fibrosis, but not on lung. However, the limitation is the observational design. The potential stabilisation of lung fibrosis by rituximab has to be addressed by a randomised trial.

Systemic sclerosis (SSc) is a systemic autoimmune disease affecting multiple organ systems, including the lungs. Interstitial lung disease (ILD) is the leading cause of death in SSc. There are no valid biomarkers to predict the occurrence of SSc-ILD, although auto-antibodies against anti-topoisomerase I and several inflammatory markers are candidate biomarkers that need further evaluation. Chest auscultation, presence of shortness of breath and pulmonary function testing are important diagnostic tools, but lack sensitivity to detect early ILD. Baseline screening with high-resolution computed tomography (HRCT) is therefore necessary to confirm an SSc-ILD diagnosis. Once diagnosed with SSc-ILD, patients' clinical courses are variable and difficult to predict, although certain patient characteristics and biomarkers are associated with disease progression. It is important to monitor patients with SSc-ILD for signs of disease progression, although there is no consensus about which diagnostic tools to use or how often monitoring should occur. In this article, we review methods used to define and predict disease progression in SSc-ILD. There is no valid definition of SSc-ILD disease progression, but we suggest that either a decline in forced vital capacity (FVC) from baseline of ≥10%, or a decline in FVC of 5–9% in association with a decline in diffusing capacity of the lung for carbon monoxide of ≥15% represents progression. An increase in the radiographic extent of ILD on HRCT imaging would also signify progression. A time period of 1–2 years is generally used for this definition, but a decline over a longer time period may also reflect clinically relevant disease progression.

Fibroblasts are polymorphic cells with pleiotropic roles in organ morphogenesis, tissue homeostasis and immune responses. In fibrotic diseases, fibroblasts synthesize abundant amounts of extracellular matrix, which induces scarring and organ failure. By contrast, a hallmark feature of fibroblasts in arthritis is degradation of the extracellular matrix because of the release of metalloproteinases and degrading enzymes, and subsequent tissue destruction. The mechanisms that drive these functionally opposing pro-fibrotic and pro-inflammatory phenotypes of fibroblasts remain unknown. Here we identify the transcription factor PU.1 as an essential regulator of the pro-fibrotic gene expression program. The interplay between transcriptional and post-transcriptional mechanisms that normally control the expression of PU.1 expression is perturbed in various fibrotic diseases, resulting in the upregulation of PU.1, induction of fibrosis-associated gene sets and a phenotypic switch in extracellular matrix-producing pro-fibrotic fibroblasts. By contrast, pharmacological and genetic inactivation of PU.1 disrupts the fibrotic network and enables reprogramming of fibrotic fibroblasts into resting fibroblasts, leading to regression of fibrosis in several organs.

Background In the Safety and Efficacy of Nintedanib in Systemic Sclerosis (SENSCIS) trial, nintedanib reduced the rate of decline in forced vital capacity (FVC) in patients with systemic sclerosis-associated interstitial lung disease (SSc-ILD). Patients on stable treatment with mycophenolate for at least 6 months before randomisation could participate. The aim of this subgroup analysis was to examine the efficacy and safety of nintedanib by mycophenolate use at baseline. Methods The SENSCIS trial was a randomised, double-blind, placebo-controlled trial, in which patients with SSc-ILD were randomly assigned (1:1) to receive 150 mg of oral nintedanib twice daily or placebo for at least 52 weeks. In a prespecified subgroup analysis, we analysed the primary endpoint of rate of decline in FVC over 52 weeks by mycophenolate use at baseline. In a post-hoc analysis, we analysed the proportion of patients with an absolute decrease in FVC of at least 3·3% predicted at week 52 (proposed minimal clinically important difference estimate for worsening of FVC in patients with SSc-ILD) in subgroups by mycophenolate use at baseline. Adverse events were reported in subgroups by mycophenolate use at baseline. Analyses were done in all participants who received at least one dose of study drug. We analysed the annual rate of decline in FVC using a random coefficient regression model (with random slopes and intercepts) including anti-topoisomerase I antibody status, age, height, sex, and baseline FVC as covariates and terms for baseline-by-time, treatment-by-subgroup, and treatment-by-subgroup-by-time interactions. SENSCIS is registered with ClinicalTrials.gov, NCT02597933, and is now complete. Findings Between Nov 30, 2015, and Oct 31, 2017, 819 participants were screened and 576 were enrolled, randomly assigned to, and treated with nintedanib (n=288) or placebo (n=288). 139 (48%) of 288 in the nintedanib group and 140 (49%) of 288 in the placebo group were taking mycophenolate at baseline. In patients taking mycophenolate at baseline, the adjusted mean annual rate of decline in FVC was –40·2 mL per year (SE 19·8) with nintedanib and –66·5 mL per year (19·3) with placebo (difference: 26·3 mL per year [95% CI –27·9 to 80·6]). In patients not taking mycophenolate at baseline, the adjusted mean annual rate of decline in FVC was –63·9 mL per year (SE 19·3) with nintedanib and –119·3 mL per year (19·0) with placebo (difference: 55·4 mL per year [95% CI 2·3 to 108·5]). We found no heterogeneity in the effect of nintedanib versus placebo on the annual rate of decline in FVC between the subgroups by mycophenolate use (p value for interaction=0·45). In a post-hoc analysis, the proportion of patients with an absolute decrease in FVC of at least 3·3% predicted was lower with nintedanib than with placebo in both patients taking mycophenolate (40 [29%] of 138 vs 56 [40%] of 140; odds ratio 0·61 [0·37 to 1·01]) and those not taking mycophenolate (59 [40%] of 149 vs 70 [47%] of 148; 0·73 [0·46 to 1·16]) at baseline. The adverse event profile of nintedanib was similar between the subgroups. Diarrhoea, the most common adverse event, was reported in 106 (76%) of 139 patients in the nintedanib group and 48 (34%) of 140 in the placebo group among those taking mycophenolate at baseline, and in 112 (75%) of 149 in the nintedanib group and 43 (29%) of 148 in the placebo group among those not taking mycophenolate at baseline. Over the entire trial period, 19 patients died (ten in the nintedanib group and nine in the placebo group). One death in the nintedanib group was considered to be related to study drug. Interpretation Nintedanib reduced the progression of interstitial lung disease both in patients with SSc-ILD who were and were not using mycophenolate at baseline, with no heterogeneity in its treatment effect detected between the subgroups. The adverse event profile of nintedanib was similar in the subgroups by mycophenolate use. Our findings suggest that the combination of mycophenolate and nintedanib offers a safe treatment option for patients with SSc-ILD. More data are needed on the benefits of initial combination therapy versus a sequential approach to treatment of SSc-ILD. Funding Boehringer Ingelheim.

Objectives To date, there is no valuable tool to assess fibrotic disease activity in humans in vivo in a non-invasive way. This study aims to uncouple inflammatory from fibrotic disease activity in fibroinflammatory diseases such as IgG 4 -related disease. Methods In this cross-sectional clinical study, 27 patients with inflammatory, fibrotic and overlapping manifestations of IgG 4 -related disease underwent positron emission tomography (PET) scanning with tracers specific for fibroblast activation protein (FAP; 68 Ga-FAP inhibitor (FAPI)-04), 18 F-fluorodeoxyglucose (FDG), MRI and histopathological assessment. In a longitudinal approach, 18 F-FDG and 68 Ga-FAPI-04 PET/CT data were evaluated before and after immunosuppressive treatment and correlated to clinical and MRI data. Results Using combination of 68 Ga-FAPI-04 and 18 F-FDG-PET, we demonstrate that non-invasive functional tracking of IgG 4 -related disease evolution from inflammatory towards a fibrotic outcome becomes feasible. 18 F-FDG-PET positive lesions showed dense lymphoplasmacytic infiltration of IgG 4 + cells in histology, while 68 Ga-FAPI-04 PET positive lesions showed abundant activated fibroblasts expressing FAP according to results from RNA-sequencing of activated fibroblasts. The responsiveness of fibrotic lesions to anti-inflammatory treatment was far less pronounced than that of inflammatory lesions. Conclusion FAP-specific PET/CT permits the discrimination between inflammatory and fibrotic activity in IgG 4 -related disease. This finding may profoundly change the management of certain forms of immune-mediated disease, such as IgG 4 -related disease, as subtypes dominated by fibrosis may require different approaches to control disease progression, for example, specific antifibrotic agents rather than broad spectrum anti-inflammatory treatments such as glucocorticoids.

Arthritis typically involves recurrence and progressive worsening at specific predilection sites, but the checkpoints between remission and persistence remain unknown. Here, we defined the molecular and cellular mechanisms of this inflammation-mediated tissue priming. Re-exposure to inflammatory stimuli caused aggravated arthritis in rodent models. Tissue priming developed locally and independently of adaptive immunity. Repeatedly stimulated primed synovial fibroblasts (SFs) exhibited enhanced metabolic activity inducing functional changes with intensified migration, invasiveness and osteoclastogenesis. Meanwhile, human SF from patients with established arthritis displayed a similar primed phenotype. Transcriptomic and epigenomic analyses as well as genetic and pharmacological targeting demonstrated that inflammatory tissue priming relies on intracellular complement C3- and C3a receptor-activation and downstream mammalian target of rapamycin- and hypoxia-inducible factor 1α-mediated metabolic SF invigoration that prevents activation-induced senescence, enhances NLRP3 inflammasome activity, and in consequence sensitizes tissue for inflammation. Our study suggests possibilities for therapeutic intervention abrogating tissue priming without immunosuppression.

To analyze the efficacy and safety of nintedanib in patients with fibrosing autoimmune disease-related interstitial lung diseases (ILDs) with a progressive phenotype.The INBUILD trial enrolled patients with a fibrosing ILD other than idiopathic pulmonary fibrosis, with diffuse fibrosing lung disease of >10% extent on high-resolution computed tomography, forced vital capacity percent predicted (FVC%) ≥45%, and diffusing capacity of the lungs for carbon monoxide percent predicted ≥30% to <80%. Patients fulfilled protocol-defined criteria for progression of ILD within the 24 months before screening, despite management deemed appropriate in clinical practice. Subjects were randomized to receive nintedanib or placebo. We assessed the rate of decline in FVC (ml/year) and adverse events (AEs) over 52 weeks in the subgroup with autoimmune disease-related ILDs.Among 170 patients with autoimmune disease-related ILDs, the rate of decline in FVC over 52 weeks was -75.9 ml/year with nintedanib versus -178.6 ml/year with placebo (difference 102.7 ml/year [95% confidence interval 23.2, 182.2]; nominal P = 0.012). No heterogeneity was detected in the effect of nintedanib versus placebo across subgroups based on ILD diagnosis (P = 0.91). The most frequent AE was diarrhea, reported in 63.4% and 27.3% of subjects in the nintedanib and placebo groups, respectively. AEs led to permanent discontinuation of trial drug in 17.1% and 10.2% of subjects in the nintedanib and placebo groups, respectively.In the INBUILD trial, nintedanib slowed the rate of decline in FVC in patients with progressive fibrosing autoimmune disease-related ILDs, with AEs that were manageable for most patients.

Abstract During surgery, rapid and accurate histopathological diagnosis is essential for clinical decision making. Yet the prevalent method of intra-operative consultation pathology is intensive in time, labour and costs, and requires the expertise of trained pathologists. Here we show that biopsy samples can be analysed within 30 min by sequentially assessing the physical phenotypes of singularized suspended cells dissociated from the tissues. The diagnostic method combines the enzyme-free mechanical dissociation of tissues, real-time deformability cytometry at rates of 100–1,000 cells s −1 and data analysis by unsupervised dimensionality reduction and logistic regression. Physical phenotype parameters extracted from brightfield images of single cells distinguished cell subpopulations in various tissues, enhancing or even substituting measurements of molecular markers. We used the method to quantify the degree of colon inflammation and to accurately discriminate healthy and tumorous tissue in biopsy samples of mouse and human colons. This fast and label-free approach may aid the intra-operative detection of pathological changes in solid biopsies.

Systemic sclerosis (SSc) skin lesions are characterized by disturbed vessel morphology with enlarged capillaries and an overall reduction in capillary density, suggesting a deregulated, insufficient angiogenic response. It has been postulated that this phenomenon is due to reduced expression of the potent angiogenic factor vascular endothelial growth factor (VEGF). In contrast to this hypothesis, we demonstrate that the expression of both VEGF and its receptors VEGFR-1 and VEGFR-2 is dramatically upregulated in skin specimens of SSc patients throughout different disease stages. Interestingly, upregulation of VEGF was not mediated by hypoxia-inducible transcription factor-1 (HIF-1) as indicated by only a weak expression of the oxygen-sensitive α-subunit of HIF-1 in the skin of SSc patients. This was unexpected on measuring low P o 2 values in the SSc skin by using a polarographic oxygen microelectrode system. Considering our observation that PDGF and IL-1β costimulated VEGF expression, we propose that chronic and uncontrolled VEGF upregulation that is mediated by an orchestrated expression of cytokines rather than VEGF downregulation is the cause of the disturbed vessel morphology in the skin of SSc patients. Consequently, for therapeutic approaches aiming to improve tissue perfusion in these patients, a controlled expression and timely termination of VEGF signaling appears to be crucial for success of proangiogenic therapies.

Articular adipose tissue is a ubiquitous component of human joints, but its local functions are largely unknown. Because recent studies revealed several links between adipose tissue, adipocytokines, and arthritis, we investigated the expression of the adipocytokine adiponectin and its functional role in articular adipose tissue and synovium of patients with different arthritides. In contrast to its protective role in endocrinological and vascular diseases, adiponectin was found to be involved in key pathways of inflammation and matrix degradation in the human joint. The effects of adiponectin in human synovial fibroblasts appear to be highly selective by inducing only two of the main mediators of rheumatoid arthritis pathophysiology, IL-6 and matrix metalloproteinase-1, via the p38 MAPK pathway. Owing to the observation that these effects could be inhibited by different TNF-alpha inhibitors, adipocytokines such as adiponectin may also be key targets for therapeutic strategies in inflammatory joint diseases. In summary, articular adipose tissue and adipocytokines cannot be regarded as innocent bystanders any more in chronic inflammatory diseases such as arthritis.

Rheumatoid arthritis is a chronic inflammatory disease characterized by destruction of cartilage and bone that is mediated by synovial fibroblasts. To determine the mechanisms by which these cells are activated to produce matrix metalloproteinases (MMPs), the effects of microparticles were investigated. Microparticles are small membrane-bound vesicles whose release from immune cells is increased during activation and apoptosis. Because microparticles occur abundantly in the synovial fluid in rheumatoid arthritis, they could represent novel stimulatory agents. Microparticles derived from T cells and monocytes strongly induced the synthesis of MMP-1, MMP-3, MMP-9, and MMP-13 in fibroblasts. The induction was time-dependent, with effects primarily observed after 36 h; under these conditions, MMP-2, MMP-14, and tissue inhibitor of MMP-1 (TIMP-1), TIMP-2, and TIMP-3 were not induced. Microparticles also increased the synthesis of inflammatory mediators including IL-6, IL-8, monocyte chemoattractant protein 1 (MCP-1), and MCP-2. In Iκ-B-transfected synovial fibroblasts, MMPs were less inducible by microparticles compared with wild-type fibroblasts. Blocking of TNFα and IL-1β with antibodies against TNFα and with IL-1 receptor antagonist did not abrogate stimulation by microparticles. These data provide evidence for a novel mechanism by which vesicles derived from activated or apoptotic immune cells can promote the destructive activity of synovial fibroblasts in rheumatoid arthritis.

The vascular system that ensures an adequate blood flow is required to provide the cells with sufficient supply of nutrients and oxygen. Two different mechanisms of the formation of new vessels can be distinguished: vasculogenesis, the formation of the first primitive vascular plexus de novo and angiogenesis, the formation of new vessels from preexisting ones. Both processes are regulated by a delicate balance of pro- and anti-angiogenic factors. Physiologically, angiostatic mediators outweigh the angiogenic molecules and angiogenesis does not occur. Under certain conditions such as tumor formation or wound healing, the positive regulators of angiogenesis predominate and the endothelium becomes activated. Angiogenesis is initiated by vasodilatation and an increased permeability. After destabilization of the vessel wall, endothelial cells proliferate, migrate and form a tube, which is finally stabilized by pericytes and smooth muscle cells. Numerous soluble growth factors and inhibitors, cytokines and proteases as well as extracellular matrix proteins and adhesion molecules strictly control this multi-step process. The properties and interactions of angiogenic molecules such as VEGFs, FGFs, angiopoietins, PDGF, angiogenin, angiotropin, HGF, CXC chemokines with ELR motif, PECAM-1, integrins and VE-cadherin as well as angiostatic key players such as angiostatin, endostatin, thrombospondin, CXC chemokines without ELR motif, PEDF are discussed in this review with respect to their molecular impact on angiogenesis.

Abstract Objective Rheumatoid arthritis (RA) is a chronic inflammatory disorder of unknown origin. Histone deacetylase (HDA) activity is considered to play a major role in the transcriptional regulation of proinflammatory genes. We undertook this study to investigate the balance of histone acetylase and HDA activity in synovial tissue from RA patients compared with that from patients with osteoarthritis (OA) and normal controls. Methods Activity of histone acetylases and HDAs was measured in nuclear extracts of total synovial tissue samples, which were obtained from RA and OA patients undergoing surgical joint replacement, and compared with the activity in synovial tissues from patients without arthritis. Tissue expression of HDAs 1 and 2 was quantified by Western blotting. In addition, immunohistochemistry was performed for HDA‐2. Results Mean ± SEM HDA activity in synovial tissue samples derived from patients with RA was measured as 1.5 ± 0.3 μmoles/μg, whereas the activity levels in OA (3.2 ± 0.7 μmoles/μg) and normal (7.1 ± 4.2 μmoles/μg) synovial tissue samples were significantly higher. Histone acetylase activity reached similar levels in RA and OA tissues and in normal tissues. The ratio of HDA activity to histone acetylase activity in RA synovial tissue was significantly reduced (12 ± 2%) compared with that in OA synovial tissue (26 ± 3%). The activity ratio in normal control samples was arbitrarily set at 100 ± 40%. In addition, the tissue expression of HDA‐1 and HDA‐2 proteins was clearly lower in RA samples than in OA samples. Conclusion The balance of histone acetylase/HDA activities is strongly shifted toward histone hyperacetylation in patients with RA. These results offer novel molecular insights into the pathogenesis of the disease that might be relevant to the development of future therapeutic approaches.

Abstract Objective Imatinib is a small‐molecule tyrosine kinase inhibitor capable of selective, dual inhibition of the transforming growth factor β and platelet‐derived growth factor (PDGF) pathways. Imatinib has previously been shown to prevent the development of inflammation‐driven experimental fibrosis when treatment was initiated before administration of the profibrotic stimulus. The aim of this study was to confirm the efficacy of imatinib in a murine model of systemic sclerosis (SSc) that is less driven by inflammation and to investigate whether imatinib is also effective for the treatment of established fibrosis. Methods The tight skin 1 (TSK‐1) mouse model of SSc was used to evaluate the antifibrotic effects of imatinib in a genetic model of the later stages of SSc. In addition, the efficacy of imatinib for the treatment of preestablished fibrosis was analyzed in a modified model of bleomycin‐induced dermal fibrosis in which the application of bleomycin was prolonged and the onset of treatment was late. Results Treatment with imatinib reduced dermal and hypodermal thickening in TSK‐1 mice and prevented the differentiation of resting fibroblasts into myofibroblasts. In the model of preestablished dermal fibrosis, imatinib not only stopped further progression of fibrosis but also induced regression of preexisting dermal fibrosis, with a reduction in dermal thickness below pretreatment levels. Conclusion These results indicate that combined inhibition of the tyrosine kinase c‐Abl and PDGF receptor might be effective in the later, less inflammatory stages of SSc and for the treatment of established fibrosis. Thus, imatinib might be an interesting candidate for clinical trials in patients with longstanding disease and preexisting tissue fibrosis.

Introduction Inflammation is a major risk factor for systemic bone loss. Proinflammatory cytokines like tumour necrosis factor (TNF) affect bone homeostasis and induce bone loss. It was hypothesised that impaired bone formation is a key component in inflammatory bone loss and that Dkk-1, a Wnt antagonist, is a strong inhibitor of osteoblast-mediated bone formation.TNF transgenic (hTNFtg) mice were treated with neutralising antibodies against TNF, Dkk-1 or a combination of both agents. Systemic bone architecture was analysed by bone histomorphometry. The expression of β-catenin, osteoprotegerin and osteocalcin was analysed. In vitro, primary osteoblasts were stimulated with TNF and analysed for their metabolic activity and expression of Dkk-1 and sclerostin. Sclerostin expression and osteocyte death upon Dkk-1 blockade were analysed in vivo.Neutralisation of Dkk-1 completely protected hTNFtg mice from inflammatory bone loss by preventing TNF-mediated impaired osteoblast function and enhanced osteoclast activity. These findings were accompanied by enhanced skeletal expression of β-catenin, osteocalcin and osteoprotegerin. In vitro, TNF rapidly increased Dkk-1 expression in primary osteoblasts and effectively blocked osteoblast differentiation. Moreover, blockade of Dkk-1 not only rescued impaired osteoblastogenesis but also neutralised TNF-mediated sclerostin expression in fully differentiated osteoblasts in vitro and in vivo.These findings indicate that low bone formation and expression of Dkk-1 trigger inflammatory bone loss. Dkk-1 blocks osteoblast differentiation, induces sclerostin expression and leads to osteocyte death. Inhibition of Dkk-1 may thus be considered as a potent strategy to protect bone from inflammatory damage.

Objectives Pathologic fibroblast activation drives fibrosis of the skin and internal organs in patients with systemic sclerosis (SSc). β-catenin is an integral part of adherens junctions and a central component of canonical Wnt signaling. Here, the authors addressed the role of β-catenin in fibroblasts for the development of SSc dermal fibrosis. Methods Nuclear accumulation of β-catenin in fibroblasts was assessed by triple staining for β-catenin, prolyl-4-hydroxylase-β and 4′,6-diamidino-2-phenylindole (DAPI). The expression of Wnt proteins in the skin was analysed by real-time PCR and immunohistochemistry. Mice with fibroblast-specific stabilisation or fibroblast-specific depletion were used to evaluate the role of β-catenin in fibrosis. Results The auhors found significantly increased nuclear levels of β-catenin in fibroblasts in SSc skin compared to fibroblasts in the skin of healthy individuals. The accumulation of β-catenin resulted from increased expression of Wnt-1 and Wnt-10b in SSc. The authors further showed that the nuclear accumulation of β-catenin has direct implications for the development of fibrosis: Mice with fibroblast-specific stabilisation of β-catenin rapidly developed fibrosis within 2 weeks with dermal thickening, accumulation of collagen and differentiation of resting fibroblasts into myofibroblasts. By contrast, fibroblast-specific deletion of β-catenin significantly reduced bleomycin-induced dermal fibrosis. Conclusions The present study findings identify β-catenin as a key player of fibroblast activation and tissue fibrosis in SSc. Although further translational studies are necessary to test the efficacy and tolerability of β-catenin/Wnt inhibition in SSc, the present findings may have clinical implications, because selective inhibitors of β-catenin/Wnt signaling have recently entered clinical trials.

Abelson kinase (c-abl) and platelet-derived growth factor (PDGF) are key players in the pathogenesis of systemic sclerosis (SSc). The aim of the present study was to evaluate the antifibrotic potential of dasatinib and nilotinib, 2 novel inhibitors of c-abl and PDGF, which are well tolerated and have recently been approved. Dasatinib and nilotinib dose-dependently reduced the mRNA and protein levels of extracellular matrix proteins in human stimulated dermal fibroblasts from SSc patients (IC(50) of 0.5-2.0 nM for dasatinib and 0.8-2.5 nM for nilotinib). In a mouse model of bleomycin-induced dermal fibrosis, dasatinib and nilotinib potently reduced the dermal thickness, the number of myofibroblasts, and the collagen content of the skin in a dose-dependent manner at well-tolerated doses. These data indicate that dasatinib and nilotinib potently inhibit the synthesis of extracellular matrix in vitro and in vivo at biologically relevant concentrations. Thus, we provide the first evidence that dasatinib and nilotinib might be promising drugs for the treatment of patients with SSc.

The aetiology of SSc is subject to ongoing research, as the precise events that underlie the development of this disease remain unclear. The pathogenesis is known to involve endothelium, epithelium, fibroblasts, innate and adaptive immune systems and their component immunological mediators. Endothelial cell damage may be the initiating factor, but the precise triggering event(s) remain elusive. Angiogenesis also appears to be dysregulated. Vasculopathy shows similarities in different organs (e.g. pulmonary arterial hypertension, renal disease, digital tip ulcers). Endothelin-1 is a potent mediator of vasculopathy, and hence represents a highly relevant target for intervention of vascular features in SSc.

Abstract Objective Insufficient angiogenesis with tissue ischemia and accumulation of extracellular matrix are hallmarks of systemic sclerosis (SSc). Based on the severely decreased oxygen levels in the skin of patients with SSc, we aimed to investigate the role of hypoxia in the pathogenesis of SSc. Methods Subtractive hybridization was used to compare gene expression in dermal fibroblasts under hypoxic and normoxic conditions. Dermal fibroblasts were further characterized by exposure to different concentrations of oxygen and for different time periods as well as by interference with hypoxia‐inducible factor 1α (HIF‐1α). The systemic normobaric hypoxia model in mice was used for in vivo analyses. Results Several extracellular matrix proteins and genes involved in extracellular matrix turnover, such as thrombospondin 1, proα2(I) collagen, fibronectin 1, insulin‐like growth factor binding protein 3, and transforming growth factor β–induced protein, were induced by hypoxia in SSc and healthy dermal fibroblasts. The induction of these genes was time‐ and dose‐dependent. Experiments with HIF‐1α–knockout mouse embryonic fibroblasts, deferoxamine/cobalt ions as chemical stabilizers of HIF‐1α, and HIF‐1α small interfering RNA consistently showed that extracellular matrix genes are induced in dermal fibroblasts by HIF‐1α–dependent, as well as HIF‐1α–independent, mechanisms. Using the systemic normobaric hypoxia mouse model, we demonstrated that dermal hypoxia leads to the induction of the identified extracellular matrix genes in vivo after both short exposure and prolonged exposure to hypoxia. Conclusion These data show that hypoxia contributes directly to the progression of fibrosis in patients with SSc by increasing the release of major extracellular matrix proteins. Targeting of hypoxia pathways might therefore be of therapeutic value in patients with SSc.

To determine the role and expression of the cytokine/receptor pair interleukin-21 (IL-21)/IL-21 receptor (IL-21R) in rheumatoid arthritis (RA).The expression of IL-21R and IL-21 was analyzed by TaqMan real-time polymerase chain reaction (PCR) and in situ hybridization of synovial biopsy samples from patients with RA and osteoarthritis (OA). Double labeling by immunohistochemistry after in situ hybridization was performed with anti-CD68 antibodies. The expression of IL-21R at the protein level was confirmed by Western blotting. Stimulation experiments were performed with recombinant IL-1beta, tumor necrosis factor alpha (TNFalpha), platelet-derived growth factor (PDGF), and transforming growth factor beta (TGFbeta). The role of IL-21R in cartilage destruction was analyzed in the SCID mouse coimplantation model of RA.IL-21R was found in total RNA extracts and in synovial biopsy samples from RA patients, whereas no expression or only minimal expression was seen in samples from OA patients. Double labeling indicated that both synovial macrophages and synovial fibroblasts expressed IL-21R. Western blotting with anti-IL-21R antibodies confirmed the expression of IL-21R protein in RA synovial fibroblasts (RASFs). Of note, IL-21 was not detectable by real-time PCR and in situ hybridization in the same samples in vivo as in vitro. The level of expression of IL-21R messenger RNA (mRNA) was not altered by stimulation with IL-1beta, TNFalpha, PDGF, or TGFbeta. Interestingly, in the SCID mouse coimplantation model, RASFs did not maintain their expression of IL-21R at sites of invasion into the cartilage. Similarly, IL-21R mRNA was not expressed at sites of invasion into cartilage and bone in RA synovium.Our data demonstrate that IL-21R is expressed in RA synovium by RASFs and synovial macrophages. IL-21R is associated with the activated phenotype of RASFs independently of the major proinflammatory cytokines IL-1beta and TNFalpha, but correlates negatively with the destruction of articular cartilage and bone.

Activated Wnt signalling with decreased expression of endogenous inhibitors has recently been characterised as a central pathomechanism in systemic sclerosis (SSc). Aberrant epigenetic modifications also contribute to the persistent activation of SSc fibroblasts. We investigated whether increased Wnt signalling and epigenetic changes in SSc are causally linked via promoter hypermethylation-induced silencing of Wnt antagonists.The methylation status of endogenous Wnt antagonists in leucocytes and fibroblasts was evaluated by methylation-specific PCR. 5-aza-2'-deoxycytidine was used to inhibit DNA methyltransferases (Dnmts) in cultured fibroblasts and in the mouse model of bleomycin-induced skin fibrosis. Activation of Wnt signalling was assessed by analysing Axin2 mRNA levels and by staining for β-catenin.The promoters of DKK1 and SFRP1 were hypermethylated in fibroblasts and peripheral blood mononuclear cells of patients with SSc. Promoter hypermethylation resulted in impaired transcription and decreased expression of DKK1 and SFRP1 in SSc. Treatment of SSc fibroblasts or bleomycin-challenged mice with 5-aza prevented promoter methylation-induced silencing and increased the expression of both genes to normal levels. Reactivation of DKK1 and SFRP1 transcription by 5-aza inhibited canonical Wnt signalling in vitro and in vivo and effectively ameliorated experimental fibrosis.We demonstrate that hypermethylation of the promoters of DKK1 and SFRP1 contributes to aberrant Wnt signalling in SSc and that Dnmt inhibition effectively reduces Wnt signalling. These data provide a novel link between epigenetic alterations and increased Wnt signalling in SSc and also have translational implications because Dnmt inhibitors are already approved for clinical use.

T-helper type 2 responses are crucial in Churg-Strauss syndrome (CSS) and may enhance the production of IgG4 antibodies. The authors assessed the IgG4 immune response in CSS patients.The authors included 46 consecutive patients with CSS (24 with active and 22 with quiescent disease), 26 with granulomatosis with polyangiitis (GPA, Wegener's), 25 with atopic asthma and 20 healthy controls and determined serum IgG, IgM, IgA, IgE and IgG subclass levels. Tissue infiltration by IgG4 plasma cells was assessed in nine patients with CSS, 10 with GPA, 22 with chronic sinusitis (11 with and 11 without eosinophilia).IgG4 levels were markedly higher in active CSS patients than in controls (p<0.001 vs all control groups). Serum IgG4 correlated with the number of disease manifestations (r=0.52, p=0.01) and the Birmingham vasculitis activity score (r=0.64, p=0.001). Longitudinal analysis in 12 CSS cases showed that both the IgG4 level and IgG4/IgG ratio dropped during disease remission (p=3×10(-5) and p=6×10(-4), respectively). Tissue analysis did not show an increased IgG4 plasma cell infiltration in CSS biopsies compared with control groups.Serum IgG4 levels are markedly elevated in active CSS and correlate with the number of organ manifestations and disease activity.

Microparticles are a heterogeneous population of membrane-coated vesicles which can be released from virtually all cell types during activation or apoptosis. Release occurs from the cell surface in an exogenous budding process involving local rearrangement of the cytoskeleton. Given their origin, these particles can be identified by staining for cell surface markers and annexin V. As shown in in vitro studies, microparticles may represent a novel subcellular element for intercellular communication in inflammation. Thus, microparticles can transfer chemokine receptors and arachidonic acid between cells, activate complement, promote leukocyte rolling and stimulate the release of pro-inflammatory mediators. Under certain conditions, however, microparticles may also exert anti-inflammatory properties by inducing immune cell apoptosis and the production of anti-inflammatory mediators. Microparticles may play an important role in the pathogenesis of rheumatologic diseases as evidenced by their elevation in diseases such as systemic sclerosis (SSc), systemic vasculitis and antiphospholipid antibody syndrome and correlation with clinical events. A role in inflammatory arthritis is suggested by the finding that leukocyte-derived microparticles induce the production of matrix metalloproteinases and cytokines by synovial fibroblasts. Together, these findings point to novel signaling pathways of cellular cross-talk that may operate along the spectrum of soluble cytokines and mediators of direct cell-cell contact.

Abstract Objective Tissue fibrosis is a hallmark compromising feature of many disorders. In this study, we investigated the antifibrogenic effects of the histone deacetylase inhibitor trichostatin A (TSA) on cytokine‐driven fibrotic responses in vitro and in vivo. Methods Skin fibroblasts from patients with systemic sclerosis (SSc) and normal healthy control subjects were stimulated with profibrotic cytokines in combination with TSA. Human Colα1(I) and fibronectin were measured using real‐time polymerase chain reaction, and levels of soluble collagen were estimated using the SirCol collagen assay. Electromobilty shift assay and confocal fluorescence microscopy were used to investigate the intracellular distribution of Smad transcription factors. For in vivo analysis, skin fibrosis was quantified by histologic assessment of mouse skin tissue in a model of bleomycin‐induced fibrosis. Results Reductions in the cytokine‐induced transcription of Colα1(I) and fibronectin were observed in both normal and SSc skin fibroblasts following the addition of TSA. Similarly, the expression of total collagen protein in TSA‐stimulated SSc skin fibroblasts was reduced to basal levels. The mechanism of action of TSA included inhibition of the nuclear translocation and DNA binding of profibrotic Smad transcription factors. Western blot analysis revealed an up‐regulation of the cell cycle inhibitor p21 by TSA, leading to reduced proliferation of fibroblasts. In addition, in bleomycin‐induced fibrosis in mice, TSA prevented dermal accumulation of extracellular matrix in vivo. Conclusion These findings provide novel insights into the epigenetic regulation of fibrosis. TSA and similar inhibitory compounds appear to represent early therapeutic strategies for achieving reversal of the cytokine‐driven induction of matrix synthesis that leads to fibrosis.

Abstract Objective Hedgehog signaling not only plays crucial roles during human development but also has been implicated in the pathogenesis of several diseases in adults. The aim of the present study was to investigate the role of the hedgehog pathway in fibroblast activation in systemic sclerosis (SSc). Methods Activation of the hedgehog pathway was analyzed by immunohistochemistry and real‐time polymerase chain reaction (PCR). The effects of sonic hedgehog (SHH) on collagen synthesis were analyzed by reporter assays, real‐time PCR, and Sircol assays. Myofibroblast differentiation was assessed by quantification of α‐smooth muscle actin and stress fiber staining. The role of hedgehog signaling in vivo was analyzed by adenoviral overexpression of SHH and using mice lacking 1 allele of the gene for inhibitory receptor Patched homolog 1 ( Ptch +/− mice). Results SHH was overexpressed and resulted in activation of hedgehog signaling in patients with SSc, with accumulation of the transcription factors Gli‐1 and Gli‐2 and increased transcription of hedgehog target genes. Activation of hedgehog signaling induced an activated phenotype in cultured fibroblasts, with differentiation of resting fibroblasts into myofibroblasts and increased release of collagen. Adenoviral overexpression of SHH in the skin of mice was sufficient to induce skin fibrosis. Moreover, Ptch +/− mice with increased hedgehog signaling were more sensitive to bleomycin‐induced dermal fibrosis. Conclusion We demonstrated that the hedgehog pathway is activated in patients with SSc. Hedgehog signaling potently stimulates the release of collagen and myofibroblast differentiation in vitro and is sufficient to induce fibrosis in vivo. These findings identify the hedgehog cascade as a profibrotic pathway in SSc.

Nintedanib is an inhibitor targeting platelet-derived growth factor receptor, fibroblast growth factor receptor and vascular endothelial growth factor receptor tyrosine kinases that has recently been approved for the treatment of idiopathic pulmonary fibrosis. The aim of this study was to analyse the effects of nintedanib in the fos-related antigen-2 (Fra2) mouse model of systemic sclerosis (SSc).The effects of nintedanib on pulmonary arterial hypertension with proliferation of pulmonary vascular smooth muscle cells (PVSMCs) and luminal occlusion, on microvascular disease with apoptosis of microvascular endothelial cells (MVECs) and on fibroblast activation with myofibroblast differentiation and accumulation of extracellular matrix were analysed. We also studied the effects of nintedanib on the levels of key mediators involved in the pathogenesis of SSc and on macrophage polarisation.Nintedanib inhibited proliferation of PVSMCs and prevented thickening of the vessel walls and luminal occlusion of pulmonary arteries. Treatment with nintedanib also inhibited apoptosis of MVECs and blunted the capillary rarefaction in Fra2-transgenic mice. These effects were associated with a normalisation of the serum levels of vascular endothelial growth factor in Fra2 mice on treatment with nintedanib. Nintedanib also effectively blocked myofibroblast differentiation and reduced pulmonary, dermal and myocardial fibrosis in Fra2-transgenic mice. The antifibrotic effects of nintedanib were associated with impaired M2 polarisation of monocytes and reduced numbers of M2 macrophages.Nintedanib targets core features of SSc in Fra2-transgenic mice and ameliorates histological features of pulmonary arterial hypertension, destructive microangiopathy and pulmonary and dermal fibrosis. These data might have direct implications for the ongoing phase III clinical trial with nintedanib in SSc-associated interstitial lung disease.

Abstract Objective To investigate whether JAK‐2 contributes to the pathologic activation of fibroblasts in patients with systemic sclerosis (SSc) and to evaluate the antifibrotic potential of JAK‐2 inhibition for the treatment of SSc. Methods Activation of JAK‐2 in human skin and in experimental fibrosis was determined by immunohistochemical analysis. JAK‐2 signaling was inhibited by the selective JAK‐2 inhibitor TG101209 or by small interfering RNA. Bleomycin‐induced dermal fibrosis in mice and TSK‐1 mice were used to evaluate the antifibrotic potential of specific JAK‐2 inhibition in vivo. Results Increased activation of JAK‐2 was detected in the skin of patients with SSc, particularly in fibroblasts. The activation of JAK‐2 was dependent on transforming growth factor β (TGFβ) and persisted in cultured SSc fibroblasts. Inhibition of JAK‐2 reduced basal collagen synthesis selectively in SSc fibroblasts but not in resting healthy dermal fibroblasts. Moreover, inhibition of JAK‐2 prevented the stimulatory effects of TGFβ on fibroblasts. Treatment with TG101209 not only prevented bleomycin‐induced fibrosis but also effectively reduced skin fibrosis in TSK‐1 mice. Conclusion We demonstrated that JAK‐2 is activated in a TGFβ‐dependent manner in SSc. Considering the potent antifibrotic effects of JAK‐2 inhibition, our study might have direct translational implications, because inhibitors of JAK‐2 are currently being evaluated in clinical trials for myeloproliferative disorders and would also be available for evaluation in patients with SSc.

Dermal fibroblasts from patients with systemic sclerosis (SSc) release excessive amounts of collagen resulting in tissue fibrosis. The molecular mechanisms underlying this pathological activation are incompletely understood.To investigate whether Notch signalling contributes to the uncontrolled activation of fibroblasts in SSc.Activation of the Notch pathway was assessed by immunohistochemistry or Western blot for the Notch intracellular domain and the Notch ligand Jagged-1 (Jag-1) and real-time PCR for the target gene hes-1. Differentiation of resting dermal fibroblasts into myofibroblasts was assessed by staining for α-smooth muscle actin. The synthesis of collagen was quantified by real-time PCR and Sircol assays.Notch signalling was activated in lesional skin of patients with SSc. The activation persisted in cultured dermal SSc fibroblasts. Stimulation of healthy dermal fibroblasts with recombinant human Jag-1-Fc chimera resulted in an SSc-like phenotype with increased release of collagen and differentiation of resting fibroblasts into myofibroblasts. Consistent with the selective activation of the Notch pathway in dermal SSc fibroblasts, DAPT or siRNA against Notch strongly reduced the basal collagen expression in SSc fibroblasts, but not in fibroblasts from healthy volunteers.It was shown that Notch signalling is activated in SSc and plays an important role in fibroblast activation and collagen release. Inhibition of Notch signalling might be an effective strategy to selectively prevent the aberrant activation of SSc fibroblasts.

Abstract Objective Tissue fibrosis caused by pathologic activation of fibroblasts with increased synthesis of extracellular matrix components is a major hallmark of systemic sclerosis (SSc). Notch signaling regulates tissue differentiation, and abnormal activation of Notch signaling has been implicated in the pathogenesis of various malignancies. The present study was undertaken to investigate the role of Notch signaling in SSc and to evaluate the therapeutic potential of Notch inhibition for the treatment of fibrosis. Methods Activation of the Notch pathways was analyzed by staining for the Notch intracellular domain (NICD) and quantification of levels of HES‐1 messenger RNA. In the mouse model of bleomycin‐induced dermal fibrosis and in tight skin 1 mice, Notch signaling was inhibited by the γ‐secretase inhibitor DAPT and by overexpression of a Notch‐1 antisense construct. Results Notch signaling was activated in SSc in vivo, with accumulation of the NICD and increased transcription of the target gene HES‐1. Overexpression of a Notch antisense construct prevented bleomycin‐induced fibrosis and hypodermal thickening in tight skin 1 mice. Potent antifibrotic effects were also obtained with DAPT treatment. In addition to prevention of fibrosis, targeting of Notch signaling resulted in almost complete regression of established experimental fibrosis. Conclusion The present results demonstrate that pharmacologic as well as genetic inhibition of Notch signaling exerts potent antifibrotic effects in different murine models of SSc. These findings might have direct translational implications because different inhibitors of the γ‐secretase complex are available and have yielded promising results in cancer trials.

Chronic inflammation is a major risk factor for systemic bone loss leading to osteoporotic fracture and substantial morbidity and mortality. Inflammatory cytokines, particularly tumour necrosis factor (TNF) and interleukin-1 (IL1), are thought to play a key role in the pathogenesis of inflammation-induced bone loss, but their exact roles are yet to be determined.To determine whether TNF directly triggers bone loss or requires IL1, human TNFalpha mice (hTNFtg) were crossed with mice lacking IL1alpha and IL1beta (IL1(-/-)hTNFtg). Systemic bone architecture was evaluated using CT scanning, static and dynamic bone histomorphometry and serum markers of bone metabolism.hTNFtg mice developed severe bone loss accompanied by a severe distortion of bone microarchitecture. Bone trabeculae were thinner and decreased in numbers, resulting in increased trabecular separation. Histomorphometric analyses revealed strongly increased bone resorption in hTNFtg mice compared with wild-type mice. In contrast, IL1(-/-)hTNFtg mice were fully protected from systemic bone loss despite still developing inflammation in their joints. Lack of IL1 completely reversed increased osteoclast formation and bone resorption in hTNFtg mice and the increased levels of RANKL in these mice. Structural parameters and osteoclast and osteoblast numbers were indistinguishable from wild-type mice.These data indicate that IL1 is essential for TNF-mediated bone loss. Despite TNF-mediated inflammatory arthritis, systemic bone is fully protected by the absence of IL1, which suggests that IL1 is an essential mediator of inflammatory osteopenia.

<h3>Background</h3> Sirt1 is a member of the sirtuin family of proteins<i>.</i> Sirt1 is a class III histone deacetylase with important regulatory roles in transcription, cellular differentiation, proliferation and metabolism. As aberrant epigenetic modifications have been linked to the pathogenesis of systemic sclerosis (SSc), we aimed to investigate the role of Sirt1 in fibroblast activation. <h3>Methods</h3> Sirt1 expression was analysed by real-time PCR, western blot and immunohistochemistry. Sirt1 signalling was modulated with the Sirt1 agonist resveratrol and by fibroblast-specific knockout. The role of Sirt1 was evaluated in bleomycin-induced skin fibrosis and in mice overexpressing a constitutively active transforming growth fac­tor-β (TGF-β) receptor I (TBRIact). <h3>Results</h3> The expression of Sirt1 was decreased in patients with SSc and in experimental fibrosis in a TGF-β-dependent manner. Activation of Sirt1 potentiated the profibrotic effects of TGF-β with increased Smad reporter activity, elevated transcription of TGF-β target genes and enhanced release of collagen. In contrast, knockdown of Sirt1 inhibited TGF-β/SMAD signalling and reduced release of collagen in fibroblasts. Consistently, mice with fibroblast-specific knockdown of Sirt1 were less susceptible to bleomycin- or TBRIact-induced fibrosis. <h3>Conclusions</h3> We identified Sirt1 as a crucial regulator of TGF-β/Smad signalling in SSc. Although Sirt1 is downregulated, this decrease is not sufficient to counterbalance the excessive activation of TGF-β signalling in SSc. However, augmentation of this endogenous regulatory mechanism, for example, by knockdown of Sirt1, can effectively inhibit TGF-β signalling and exerts potent antifibrotic effects. Sirt1 may thus be a key regulator of fibroblast activation in SSc.

<h3>Background</h3> Vitamin D receptor (VDR) is a member of the nuclear receptor superfamily. Its ligand, 1,25-(OH)₂D, is a metabolically active hormone derived from vitamin D₃. The levels of vitamin D₃ are decreased in patients with systemic sclerosis (SSc). Here, we aimed to analyse the role of VDR signalling in fibrosis. <h3>Methods</h3> VDR expression was analysed in SSc skin, experimental fibrosis and human fibroblasts. VDR signalling was modulated by siRNA and with the selective agonist paricalcitol. The effects of VDR on Smad signalling were analysed by reporter assays, target gene analyses and coimmunoprecipitation. The effects of paricalcitol were evaluated in the models of bleomycin-induced fibrosis and fibrosis induced by overexpression of a constitutively active transforming growth factor-β (TGF-β) receptor I (TBRI^CA). <h3>Results</h3> VDR expression was decreased in fibroblasts of SSc patients and murine models of SSc in a TGF-β-dependent manner. Knockdown of VDR enhanced the sensitivity of fibroblasts towards TGF-β. In contrast, activation of VDR by paricalcitol reduced the stimulatory effects of TGF-β on fibroblasts and inhibited collagen release and myofibroblast differentiation. Paricalcitol stimulated the formation of complexes between VDR and phosphorylated Smad3 in fibroblasts to inhibit Smad-dependent transcription. Preventive and therapeutic treatment with paricalcitol exerted potent antifibrotic effects and ameliorated bleomycin- as well as TBRI^CA-induced fibrosis. <h3>Conclusions</h3> We characterise VDR as a negative regulator of TGF-β/Smad signalling. Impaired VDR signalling with reduced expression of VDR and decreased levels of its ligand may thus contribute to hyperactive TGF-β signalling and aberrant fibroblast activation in SSc.

Abstract Systemic sclerosis (SSc) is an autoimmune disease that shows one of the highest mortality rates among rheumatic diseases. We perform a large genome-wide association study (GWAS), and meta-analysis with previous GWASs, in 26,679 individuals and identify 27 independent genome-wide associated signals, including 13 new risk loci. The novel associations nearly double the number of genome-wide hits reported for SSc thus far. We define 95% credible sets of less than 5 likely causal variants in 12 loci. Additionally, we identify specific SSc subtype-associated signals. Functional analysis of high-priority variants shows the potential function of SSc signals, with the identification of 43 robust target genes through HiChIP. Our results point towards molecular pathways potentially involved in vasculopathy and fibrosis, two main hallmarks in SSc, and highlight the spectrum of critical cell types for the disease. This work supports a better understanding of the genetic basis of SSc and provides directions for future functional experiments.

The rarity of early diffuse cutaneous systemic sclerosis (dcSSc) makes randomised controlled trials very difficult. We aimed to use an observational approach to compare effectiveness of currently used treatment approaches.This was a prospective, observational cohort study of early dcSSc (within three years of onset of skin thickening). Clinicians selected one of four protocols for each patient: methotrexate, mycophenolate mofetil (MMF), cyclophosphamide or 'no immunosuppressant'. Patients were assessed three-monthly for up to 24 months. The primary outcome was the change in modified Rodnan skin score (mRSS). Confounding by indication at baseline was accounted for using inverse probability of treatment (IPT) weights. As a secondary outcome, an IPT-weighted Cox model was used to test for differences in survival.Of 326 patients recruited from 50 centres, 65 were prescribed methotrexate, 118 MMF, 87 cyclophosphamide and 56 no immunosuppressant. 276 (84.7%) patients completed 12 and 234 (71.7%) 24 months follow-up (or reached last visit date). There were statistically significant reductions in mRSS at 12 months in all groups: -4.0 (-5.2 to -2.7) units for methotrexate, -4.1 (-5.3 to -2.9) for MMF, -3.3 (-4.9 to -1.7) for cyclophosphamide and -2.2 (-4.0 to -0.3) for no immunosuppressant (p value for between-group differences=0.346). There were no statistically significant differences in survival between protocols before (p=0.389) or after weighting (p=0.440), but survival was poorest in the no immunosuppressant group (84.0%) at 24 months.These findings may support using immunosuppressants for early dcSSc but suggest that overall benefit is modest over 12 months and that better treatments are needed.NCT02339441.

Tyrosine kinases regulate a broad variety of physiological cell processes, including metabolism, growth, differentiation and apoptosis. Abnormal tyrosine kinase activity disturbs the physiological cell homeostasis and can lead to cancer, vascular disease, and fibrosis. In regard to fibrosis, different tyrosine kinases have been identified as determinants of disease progression and potential targets for anti-fibrotic therapies. This includes both receptor tyrosine kinases (e.g., PDGF receptor, VEGF receptor, EGF receptor, and JAK kinases) as well as non-receptor tyrosine kinases (e.g., c-Abl, c-Kit, and Src kinases). Given their central role in the pathogenesis of fibrosis, researchers of our field study the anti-fibrotic effects of monoclonal antibodies or small-molecule inhibitors to block the aberrant tyrosine kinase activity and treat fibrosis in preclinical models of various fibrotic diseases (e.g., idiopathic pulmonary fibrosis, renal fibrosis, liver fibrosis, and dermal fibrosis). The results of these studies were promising and prompted clinical trials with different compounds in fibrotic diseases. So far, results from studies with intedanib in idiopathic pulmonary fibrosis and imatinib in idiopathic pulmonary fibrosis and systemic sclerosis have been reported. Although none of these studies reported a positive primary outcome, promising trends in anti-fibrotic efficacy awaken our hopes for a new class of effective anti-fibrotic targeted therapies. This article is part of a Special Issue entitled: Fibrosis: Translation of basic research to human disease.

Abstract WNT5A has recently been implicated in inflammatory processes, but its role as a bone marrow stromal cell (BMSC)–derived mediator of joint inflammation in arthritis is unclear. Here, we investigated whether inflammatory stimuli induce WNT5A in BMSC to control inflammatory responses. WNT5A levels were determined in human BMSC after stimulation with lipopolysaccharide (LPS) or tumor necrosis factor α (TNF-α,) and in synovial cells and tissue of patients with rheumatoid arthritis (RA) and human TNF-α transgenic (hTNFtg) mice. A microarray analysis of WNT5A-treated murine osteoblasts was performed using Affymetrix gene chips. The regulation of cytokine/chemokine expression was confirmed by qPCR, ELISA, and Luminex technology in BMSC after stimulation with WNT5A or WNT5A knockdown. Relevant signaling pathways were identified using specific inhibitors. Migration of MACS-purified T lymphocytes and monocytes was assessed using the FluoroBlok system. WNT5A expression was increased threefold in BMSC after stimulation with LPS or TNF-α. Synovial fibroblasts from patients with RA showed a twofold increase of WNT5A expression compared with control cells, and its expression was highly induced in the synovial tissue of patients with RA and hTNFtg mice. Microarray analysis of WNT5A-treated osteoblasts identified cytokines and chemokines as targets. The induction of IL-1β, IL-6, CCL2, CCL5, CXCL1, and CXCL5 by WNT5A was confirmed in BMSC and depended on the activation of the NF-κB, mitogen-activated protein (MAPK), and Akt pathways. Accordingly, knockdown of WNT5A markedly reduced the basal and LPS-induced cytokine/chemokine production. Finally, migration of monocytes and T cells toward the supernatant of WNT5A-treated BMSC was increased by 25% and 20%, respectively. This study underlines the critical role of BMSC-derived WNT5A in the regulation of inflammatory processes and suggests its participation in the pathogenesis of RA. © 2012 American Society for Bone and Mineral Research.

The development of novel treatments for rheumatoid arthritis (RA) requires the interplay between clinical observations and studies in animal models. Given the complex molecular pathogenesis and highly heterogeneous clinical picture of RA, there is an urgent need to dissect its multifactorial nature and to propose new strategies for preventive, early and curative treatments. Research on animal models has generated new knowledge on RA pathophysiology and aetiology and has provided highly successful paradigms for innovative drug development. Recent focus has shifted towards the discovery of novel biomarkers, with emphasis on presymptomatic and emerging stages of human RA, and towards addressing the pathophysiological mechanisms and subsequent efficacy of interventions that underlie different disease variants. Shifts in the current paradigms underlying RA pathogenesis have also led to increased demand for new (including humanised) animal models. There is therefore an urgent need to integrate the knowledge on human and animal models with the ultimate goal of creating a comprehensive 'pathogenesis map' that will guide alignment of existing and new animal models to the subset of disease they mimic. This requires full and standardised characterisation of all models at the genotypic, phenotypic and biomarker level, exploiting recent technological developments in 'omics' profiling and computational biology as well as state of the art bioimaging. Efficient integration and dissemination of information and resources as well as outreach to the public will be necessary to manage the plethora of data accumulated and to increase community awareness and support for innovative animal model research in rheumatology.

Background and objectives Fibrosis is a major socioeconomic burden, but effective antifibrotic therapies are not available in the clinical routine. There is growing evidence for a central role of Wnt signalling in fibrotic diseases such as systemic sclerosis, and we therefore evaluated the translational potential of pharmacological Wnt inhibition in experimental dermal fibrosis. Methods We examined the antifibrotic effects of PKF118-310 and ICG-001, two novel inhibitors of downstream canonical Wnt signalling, in the models of prevention and treatment of bleomycin-induced dermal fibrosis as well as in experimental dermal fibrosis induced by adenoviral overexpression of a constitutively active transforming growth factor (TGF)-β receptor I. Results PKF118-310 and ICG-001 were well tolerated throughout all experiments. Both therapeutic approaches showed antifibrotic effects in preventing and reversing bleomycin-induced dermal fibrosis as measured by skin thickness, hydroxyproline content and myofibroblast counts. PKF118-310 and ICG-001 were effective in inhibiting TGF-β receptor I-driven fibrosis as assessed by the same outcome measures. Conclusions Blockade of canonical Wnt signalling by PKF118-310 and ICG-001 showed antifibrotic effects in different models of skin fibrosis. Both therapies were well tolerated. Although further experimental evidence for efficacy and tolerability is necessary, inhibition of canonical Wnt signalling is a promising treatment approach for fibrosis.

Systemic sclerosis-associated pulmonary arterial hypertension differs from idiopathic pulmonary arterial hypertension with respect to histopathology, treatment responses and survival. Medical progress on PAH is hampered by the lack of human biosamples and suitable animal models. In this study, the authors evaluated fos-related antigen 2 (Fra-2) transgenic mice as a novel model for systemic sclerosis-associated pulmonary arterial hypertension.Lung sections of Fra-2 transgenic (n=12) and wild-type mice (n=6) were analysed at 16 weeks by histology using Dana Point criteria. Cellular and molecular key players were assessed by immunohistochemistry. To test the model's sensitivity to change over treatment, a subgroup of Fra-2 transgenic mice (n=6) was treated with the tyrosine kinase inhibitor nilotinib twice daily 37.5 mg orally from 8 weeks of age.Fra-2 transgenic mice developed severe vascular remodelling of pulmonary arteries and non-specific interstitial pneumonia-like interstitial lung disease resembling human systemic sclerosis-associated pulmonary hypertension. Histological features typical for systemic sclerosis-associated pulmonary arterial hypertension, such as intimal thickening with concentric laminar lesions, medial hypertrophy, perivascular inflammatory infiltrates, adventitial fibrosis, but not pulmonary occlusive venopathy were frequently detected. Platelet-derived growth factor signalling pathways were activated in pulmonary vessels of Fra-2 transgenic compared with wild-type mice. Since treatment with nilotinib strongly prevented the development of proliferative vasculopathy and lung fibrosis, the model proved to be sensitive to treatment.This study suggests that Fra-2 transgenic mice as an animal model of systemic sclerosis-associated pulmonary arterial hypertension display main characteristic features of the human disease. It therefore allows studying pathophysiological aspects and might serve as a preclinical model for interventional proof-of-concept studies.

We have previously described the antifibrotic role of the soluble guanylate cyclase (sGC). The mode of action, however, remained elusive. In the present study, we describe a novel link between sGC signalling and transforming growth factor β (TGFβ) signalling that mediates the antifibrotic effects of the sGC.Human fibroblasts and murine sGC knockout fibroblasts were treated with the sGC stimulator BAY 41-2272 or the stable cyclic guanosine monophosphate (cGMP) analogue 8-Bromo-cGMP and stimulated with TGFβ. sGC knockout fibroblasts were isolated from sGCI(fl/fl) mice, and recombination was induced by Cre-adenovirus. In vivo, we studied the antifibrotic effects of BAY 41-2272 in mice overexpressing a constitutively active TGF-β1 receptor.sGC stimulation inhibited TGFβ-dependent fibroblast activation and collagen release. sGC knockout fibroblasts confirmed that the sGC is essential for the antifibrotic effects of BAY 41-2272. Furthermore, 8-Bromo-cGMP reduced TGFβ-dependent collagen release. While nuclear p-SMAD2 and 3 levels, SMAD reporter activity and transcription of classical TGFβ target genes remained unchanged, sGC stimulation blocked the phosphorylation of ERK. In vivo, sGC stimulation inhibited TGFβ-driven dermal fibrosis but did not change p-SMAD2 and 3 levels and TGFβ target gene expression, confirming that non-canonical TGFβ pathways mediate the antifibrotic sGC activity.We elucidated the antifibrotic mode of action of the sGC that increases cGMP levels, blocks non-canonical TGFβ signalling and inhibits experimental fibrosis. Since sGC stimulators have shown excellent efficacy and tolerability in phase 3 clinical trials for pulmonary arterial hypertension, they may be further developed for the simultaneous treatment of fibrosis and vascular disease in systemic sclerosis.

Abstract Uncontrolled activation of TGFβ signaling is a common denominator of fibrotic tissue remodeling. Here we characterize the tyrosine phosphatase SHP2 as a molecular checkpoint for TGFβ-induced JAK2/STAT3 signaling and as a potential target for the treatment of fibrosis. TGFβ stimulates the phosphatase activity of SHP2, although this effect is in part counterbalanced by inhibitory effects on SHP2 expression. Stimulation with TGFβ promotes recruitment of SHP2 to JAK2 in fibroblasts with subsequent dephosphorylation of JAK2 at Y570 and activation of STAT3. The effects of SHP2 on STAT3 activation translate into major regulatory effects of SHP2 on fibroblast activation and tissue fibrosis. Genetic or pharmacologic inactivation of SHP2 promotes accumulation of JAK2 phosphorylated at Y570, reduces JAK2/STAT3 signaling, inhibits TGFβ-induced fibroblast activation and ameliorates dermal and pulmonary fibrosis. Given the availability of potent SHP2 inhibitors, SHP2 might thus be a potential target for the treatment of fibrosis.

Autophagy has recently been shown to regulate osteoclast activity and osteoclast differentiation. Here, we aim to investigate the impact of autophagy inhibition as a potential therapeutic approach for the treatment of osteoporosis in preclinical models.Systemic bone loss was induced in mice by glucocorticoids and by ovariectomy (OVX). Autophagy was targeted by conditional inactivation of autophagy-related gene 7 (Atg7) and by treatment with chloroquine (CQ). Bone density was evaluated by microCT. The role of autophagy on osteoclastogenesis was analysed by osteoclastogenesis and bone resorption assays. The quantification of receptor activator of nuclear factor κ B ligand and osteoprotegerin proteins in cocultures was performed using ELISA whereas that of osteoclast and osteoblast differentiation markers was by qPCR.Selective deletion of Atg7 in monocytes from Atg7(fl/fl)_x_LysM-Cre mice mitigated glucocorticoid-induced and OVX-induced osteoclast differentiation and bone loss compared with Atg7(fl/fl) littermates. Pharmacological inhibition of autophagy by treatment with CQ suppressed glucocorticoid-induced osteoclastogenesis and protected mice from bone loss. Similarly, inactivation of autophagy shielded mice from OVX-induced bone loss. Inhibition of autophagy led to decreased osteoclast differentiation with lower expression of osteoclast markers such as NFATc1, tartrate-resistant acid phosphatase, OSCAR and cathepsin K and attenuated bone resorption in vitro. In contrast, osteoblast differentiation was not affected by inhibition of autophagy.Pharmacological or genetic inactivation of autophagy ameliorated glucocorticoid-induced and OVX-induced bone loss by inhibiting osteoclastogenesis. These findings may have direct translational implications for the treatment of osteoporosis, since inhibitors of autophagy such as CQ are already in clinical use.

Fibroblasts are key effector cells in tissue remodeling. They remain persistently activated in fibrotic diseases, resulting in progressive deposition of extracellular matrix. Although fibroblast activation may be initiated by external factors, prolonged activation can induce an “autonomous,” self-maintaining profibrotic phenotype in fibroblasts. Accumulating evidence suggests that epigenetic alterations play a central role in establishing this persistently activated pathologic phenotype of fibroblasts. We demonstrated that in fibrotic skin of patients with systemic sclerosis (SSc), a prototypical idiopathic fibrotic disease, TGF-β induced the expression of DNA methyltransferase 3A (DNMT3A) and DNMT1 in fibroblasts in a SMAD-dependent manner to silence the expression of suppressor of cytokine signaling 3 (SOCS3) by promoter hypermethylation. Downregulation of SOCS3 facilitated activation of STAT3 to promote fibroblast-to-myofibroblast transition, collagen release, and fibrosis in vitro and in vivo. Reestablishment of the epigenetic control of STAT3 signaling by genetic or pharmacological inactivation of DNMT3A reversed the activated phenotype of SSc fibroblasts in tissue culture, inhibited TGF-β–dependent fibroblast activation, and ameliorated experimental fibrosis in murine models. These findings identify a pathway of epigenetic imprinting of fibroblasts in fibrotic disease with translational implications for the development of targeted therapies in fibrotic diseases.

Objective Expression of dipeptidylpeptidase 4 ( DPP ‐4) identifies a dermal fibroblast lineage involved in scarring during wound healing. The role of DDP ‐4 in tissue fibrosis is, however, unknown. The aim of the present study was to evaluate DPP ‐4 as a potential target for the treatment of fibrosis in patients with systemic sclerosis ( SS c). Methods Expression of DPP ‐4 in skin biopsy samples and dermal fibroblasts was analyzed by real‐time polymerase chain reaction, immunofluorescence, and Western blot analyses. The activity of DPP ‐4 was modulated by overexpression, knockdown, and pharmacologic inhibition of DPP 4 using sitagliptin and vildagliptin. The effects of DPP 4 inhibition were analyzed in human dermal fibroblasts and in different mouse models of SS c (each n = 6). Results The expression of DPP ‐4 and the number of DPP ‐4–positive fibroblasts were increased in the fibrotic skin of SS c patients, in a transforming growth factor β ( TGF β)–dependent manner. DPP ‐4–positive fibroblasts expressed higher levels of myofibroblast markers and collagen (each P &lt; 0.001 versus healthy controls). Overexpression of DPP 4 promoted fibroblast activation, whereas pharmacologic inhibition or genetic inactivation of DPP 4 reduced the proliferation, migration, and expression of contractile proteins and release of collagen (each P &lt; 0.001 versus control mice) by interfering with TGF β‐induced ERK signaling. DPP 4‐knockout mice were less sensitive to bleomycin‐induced dermal and pulmonary fibrosis ( P &lt; 0.0001 versus wild‐type controls). Treatment with DPP 4 inhibitors promoted regression of fibrosis in mice that had received bleomycin challenge and mice with chronic graft‐versus‐host disease, and ameliorated fibrosis in TSK 1 mice (each P &lt; 0.001 versus untreated controls). These antifibrotic effects were associated with a reduction in inflammation. Conclusion DPP ‐4 characterizes a population of activated fibroblasts and shows that DPP ‐4 regulates TGF β‐induced fibroblast activation in the fibrotic skin of SS c patients. Inhibition of DPP 4 exerts potent antifibrotic effects when administered in well‐tolerated doses. As DPP 4 inhibitors are already in clinical use for diabetes, these results may have direct translational implications for the treatment of fibrosis in patients with SS c.

Innate lymphoid cells (ILC) have a high potency for cytokine production independent of specific Ag stimulation. Imbalance of ILC subsets may influence cytokine production in humans and hence be associated with the development of inflammatory disease. Evidence for an imbalance of ILC homeostasis in human disease, however, is very limited to date. In this study we show that psoriatic arthritis (PsA), a severe disease of the joints depending on the activation of the IL-23/IL-17 pathway, is characterized by a skewed ILC homeostasis. Circulating ILC3s as potent source of IL-17/IL-22 were elevated in active PsA, whereas ILC2s, which produce proresolving cytokines, were decreased. The ILC2/ILC3 ratio was significantly correlated with clinical disease activity scores and the presence of imaging signs of joint inflammation and bone damage. Multivariable analysis showed that a high ILC2/ILC3 ratio is associated with remission in PsA, suggesting that specific alterations of ILC homeostasis control disease activity in PsA.

Regulatory T cells (Tregs) represent a major population in the control of immune homeostasis and autoimmunity. Here we show that Fos-like 2 (Fosl2), a TCR-induced AP1 transcription factor, represses Treg development and controls autoimmunity. Mice overexpressing Fosl2 (Fosl2tg) indeed show a systemic inflammatory phenotype, with immune infiltrates in multiple organs. This phenotype is absent in Fosl2tg × Rag2−/− mice lacking T and B cells, and Fosl2 induces T cell-intrinsic reduction of Treg development that is responsible for the inflammatory phenotype. Fosl2tg T cells can transfer inflammation, which is suppressed by the co-delivery of Tregs, while Fosl2 deficiency in T cells reduces the severity of autoimmunity in the EAE model. We find that Fosl2 could affect expression of FoxP3 and other Treg development genes. Our data highlight the importance of AP1 transcription factors, in particular Fosl2, during T cell development to determine Treg differentiation and control autoimmunity.

TGF-β is a master regulator of fibrosis, driving the differentiation of fibroblasts into apoptosis-resistant myofibroblasts and sustaining the production of extracellular matrix (ECM) components. Here, we identified the nuclear long noncoding RNA (lncRNA) H19X as a master regulator of TGF-β–driven tissue fibrosis. H19X was consistently upregulated in a wide variety of human fibrotic tissues and diseases and was strongly induced by TGF-β, particularly in fibroblasts and fibroblast-related cells. Functional experiments following H19X silencing revealed that H19X was an obligatory factor for TGF-β–induced ECM synthesis as well as differentiation and survival of ECM-producing myofibroblasts. We showed that H19X regulates DDIT4L gene expression, specifically interacting with a region upstream of the DDIT4L gene and changing the chromatin accessibility of a DDIT4L enhancer. These events resulted in transcriptional repression of DDIT4L and, in turn, in increased collagen expression and fibrosis. Our results shed light on key effectors of TGF-β–induced ECM remodeling and fibrosis.

<h2>Summary</h2><h3>Background</h3> Interstitial lung disease (ILD) is the most common cause of death in systemic sclerosis. To date, the progression of systemic sclerosis-associated ILD is judged by the accrual of lung damage on CT and pulmonary function tests. However, diagnostic tools to assess disease activity are not available. Here, we tested the hypothesis that quantification of fibroblast activation by PET-CT using a ⁶⁸Ga-labelled selective inhibitor of prolyl endopeptidase FAP (⁶⁸Ga-FAPI-04) would correlate with ILD activity and disease progression in patients with systemic sclerosis-associated ILD. <h3>Methods</h3> Between Sept 10, 2018, and April 8, 2020, 21 patients with systemic sclerosis-associated ILD confirmed by high-resolution CT (HRCT) within 12 months of inclusion and with onset of systemic sclerosis-associated ILD within 5 years or signs of progressive ILD and 21 controls without ILD were consecutively enrolled. All participants underwent ⁶⁸Ga-FAPI-04 PET-CT imaging and standard-of-care procedures, including HRCT and pulmonary function tests at baseline. Patients with systemic sclerosis-associated ILD were followed for 6 months with HRCT and pulmonary function tests. We compared baseline ⁶⁸Ga-FAPI-04 PET-CT uptake with standard diagnostic tools and predictors of ILD progression. The association of ⁶⁸Ga-FAPI-04 uptake with changes in forced vital capacity was analysed using mixed-effects models. Follow-up ⁶⁸Ga-FAPI-04 PET-CT scans were obtained in a subset of patients treated with nintedanib (follow-up between 6–10 months) to assess change over time. <h3>Findings</h3> ⁶⁸Ga-FAPI-04 accumulated in fibrotic areas of the lungs in patients with systemic sclerosis-associated ILD compared with controls, with a median standardised uptake value (SUV) mean over the whole lung of 0·80 (IQR 0·60–2·10) in the systemic sclerosis-ILD group and 0·50 (0·40–0·50) in the control group (p<0·0001) and a mean whole lung maximal SUV of 4·40 (range 3·05–5·20) in the systemic sclerosis-ILD group compared with 0·70 (0·65–0·70) in the control group (p<0·0001). Whole-lung FAPI metabolic active volume (wlFAPI-MAV) and whole-lung total lesion FAPI (wlTL-FAPI) were not measurable in control participants, because no ⁶⁸Ga-FAPI-04 uptake above background level was observed. In the systemic sclerosis-ILD group the median wlFAPI-MAV was 254·00 cm³ (IQR 163·40–442·30), and the median wlTL-FAPI was 183·60 cm³ (98·04–960·70). ⁶⁸Ga-FAPI-04 uptake was higher in patients with extensive disease, with previous ILD progression, or high EUSTAR activity scores than in those with with limited disease, previously stable ILD, or low EUSTAR activity scores. Increased ⁶⁸Ga-FAPI-04 uptake at baseline was associated with progression of ILD independently of extent of involvement on HRCT scan and the forced vital capacity at baseline. In consecutive ⁶⁸Ga-FAPI-04 PET-CTs, changes in ⁶⁸Ga-FAPI-04 uptake was concordant with the observed response to the fibroblast-targeting antifibrotic drug nintedanib. <h3>Interpretation</h3> Our study presents the first in-human evidence that fibroblast activation correlates with fibrotic activity and disease progression in the lungs of patients with systemic sclerosis-associated ILD and that ⁶⁸Ga-FAPI-04 PET-CT might improve risk assessment of systemic sclerosis-associated ILD. <h3>Funding</h3> German Research Foundation, Erlangen Anschubs-und Nachwuchsfinanzierung, Interdisziplinäres Zentrum für Klinische Forschung Erlangen, Bundesministerium für Bildung und Forschung, Deutsche Stiftung Systemische Sklerose, Wilhelm-Sander-Foundation, Else-Kröner-Fresenius-Foundation, European Research Council, Ernst-Jung-Foundation, and Clinician Scientist Program Erlangen.

Activation of fibroblasts is essential for physiological tissue repair. Uncontrolled activation of fibroblasts, however, may lead to tissue fibrosis with organ dysfunction. Although several pathways capable of promoting fibroblast activation and tissue repair have been identified, their interplay in the context of chronic fibrotic diseases remains incompletely understood. Here, we provide evidence that transforming growth factor-β (TGFβ) activates autophagy by an epigenetic mechanism to amplify its profibrotic effects. TGFβ induces autophagy in fibrotic diseases by SMAD3-dependent downregulation of the H4K16 histone acetyltransferase MYST1, which regulates the expression of core components of the autophagy machinery such as ATG7 and BECLIN1. Activation of autophagy in fibroblasts promotes collagen release and is both, sufficient and required, to induce tissue fibrosis. Forced expression of MYST1 abrogates the stimulatory effects of TGFβ on autophagy and re-establishes the epigenetic control of autophagy in fibrotic conditions. Interference with the aberrant activation of autophagy inhibits TGFβ-induced fibroblast activation and ameliorates experimental dermal and pulmonary fibrosis. These findings link uncontrolled TGFβ signaling to aberrant autophagy and deregulated epigenetics in fibrotic diseases and may contribute to the development of therapeutic interventions in fibrotic diseases.

Timely diagnosis and treatment are essential in the effective management of inflammatory rheumatic diseases (IRDs). Symptom checkers (SCs) promise to accelerate diagnosis, reduce misdiagnoses, and guide patients more effectively through the health care system. Although SCs are increasingly used, there exists little supporting evidence.To assess the diagnostic accuracy, patient-perceived usability, and acceptance of two SCs: (1) Ada and (2) Rheport.Patients newly presenting to a German secondary rheumatology outpatient clinic were randomly assigned in a 1:1 ratio to complete Ada or Rheport and consecutively the respective other SCs in a prospective non-blinded controlled randomized crossover trial. The primary outcome was the accuracy of the SCs regarding the diagnosis of an IRD compared to the physicians' diagnosis as the gold standard. The secondary outcomes were patient-perceived usability, acceptance, and time to complete the SC.In this interim analysis, the first 164 patients who completed the study were analyzed. 32.9% (54/164) of the study subjects were diagnosed with an IRD. Rheport showed a sensitivity of 53.7% and a specificity of 51.8% for IRDs. Ada's top 1 (D1) and top 5 disease suggestions (D5) showed a sensitivity of 42.6% and 53.7% and a specificity of 63.6% and 54.5% concerning IRDs, respectively. The correct diagnosis of the IRD patients was within the Ada D1 and D5 suggestions in 16.7% (9/54) and 25.9% (14/54), respectively. The median System Usability Scale (SUS) score of Ada and Rheport was 75.0/100 and 77.5/100, respectively. The median completion time for both Ada and Rheport was 7.0 and 8.5 min, respectively. Sixty-four percent and 67.1% would recommend using Ada and Rheport to friends and other patients, respectively.While SCs are well accepted among patients, their diagnostic accuracy is limited to date.DRKS.de, DRKS00017642 . Registered on 23 July 2019.

Using data from the SENSCIS trial, these analyses were undertaken to assess the effects of nintedanib versus placebo in subgroups of patients with systemic sclerosis-associated interstitial lung disease (SSc-ILD), based on characteristics previously identified as being associated with the progression of SSc-ILD.Patients with SSc-ILD were randomized to receive either nintedanib or placebo, stratified by anti-topoisomerase I antibody (ATA) status. We assessed the rate of decline in forced vital capacity (FVC) (expressed in ml/year) over 52 weeks in subgroups based on baseline ATA status, modified Rodnan skin thickness score (MRSS) (<18 versus ≥18), and SSc subtype (limited cutaneous SSc [lcSSc] versus diffuse cutaneous SSc [dcSSc]).At baseline, 60.8% of 576 patients who received treatment with either nintedanib or placebo were positive for ATA, 51.9% had dcSSc, and 77.5% of 574 patients with MRSS data available had an MRSS of <18. The effect of nintedanib versus placebo on reducing the rate of decline in FVC (ml/year) was numerically more pronounced in ATA-negative patients compared to ATA-positive patients (adjusted difference in the rate of FVC decline, 57.2 ml/year [95% confidence interval (95% CI) -3.5, 118.0] versus 29.9 ml/year [95% CI -19.1, 78.8]), in patients with a baseline MRSS ≥18 compared to those with a baseline MRSS of <18 (adjusted difference in the rate of FVC decline, 88.7 ml/year [95% CI 7.7, 169.8] versus 26.4 ml/year [95% CI -16.8, 69.6]), and in patients with dcSSc compared to those with lcSSc (adjusted difference in the rate of FVC decline, 56.6 ml/year [95% CI 3.2, 110.0] versus 25.3 ml/year [95% CI -28.9, 79.6]). However, all exploratory interaction P values were nonsignificant (all P > 0.05), indicating that there was no heterogeneity in the effect of nintedanib versus placebo between these subgroups of patients.In patients with SSc-ILD, reduction in the annual rate of decline in FVC among patients receiving nintedanib compared to those receiving placebo was not found to be heterogenous across subgroups based on ATA status, MRSS, or SSc subtype.

Objective S100A4 is a DAMP protein. S100A4 is overexpressed in patients with systemic sclerosis (SSc), and levels correlate with organ involvement and disease activity. S100A4 −/− mice are protected from fibrosis. The aim of this study was to assess the antifibrotic effects of anti‐S100A4 monoclonal antibody (mAb) in murine models of SSc and in precision cut skin slices of patients with SSc. Methods The effects of anti‐S100A4 mAbs were evaluated in a bleomycin‐induced skin fibrosis model and in Tsk‐1 mice with a therapeutic dosing regimen. In addition, the effects of anti‐S100A4 mAbs on precision cut SSc skin slices were analyzed by RNA sequencing. Results Inhibition of S100A4 was effective in the treatment of pre‐established bleomycin‐induced skin fibrosis and in regression of pre‐established fibrosis with reduced dermal thickening, myofibroblast counts, and collagen accumulation. Transcriptional profiling demonstrated targeting of multiple profibrotic and proinflammatory processes relevant to the pathogenesis of SSc on targeted S100A4 inhibition in a bleomycin‐induced skin fibrosis model. Moreover, targeted S100A4 inhibition also modulated inflammation‐ and fibrosis‐relevant gene sets in precision cut SSc skin slices in an ex vivo trial approach. Selected downstream targets of S100A4, such as AMP‐activated protein kinase, calsequestrin‐1, and phosphorylated STAT3, were validated on the protein level, and STAT3 inhibition was shown to prevent the profibrotic effects of S100A4 on fibroblasts in human skin. Conclusion Inhibition of S100A4 confers dual targeting of inflammatory and fibrotic pathways in complementary mouse models of fibrosis and in SSc skin. These effects support the further development of anti‐S100A4 mAbs as disease‐modifying targeted therapies for SSc.

To examine the expression and regulation of interleukin-21 (IL-21) and IL-21 receptor (IL-21R) in patients with systemic sclerosis (SSc; scleroderma).Skin biopsy specimens were obtained from 23 patients with SSc and 15 healthy controls. IL-21/IL-21R messenger RNA (mRNA) was quantified using real-time polymerase chain reaction (PCR). The expression pattern of IL-21/IL-21R was analyzed by in situ hybridization and Western blotting. Stimulation experiments were performed with cultured dermal fibroblasts from patients with SSc and healthy controls as well as with keratinocytes, using IL-1beta, platelet-derived growth factor BB, monocyte chemoattractant protein 1, transforming growth factor beta, and IL-21. The SCID-hu skin mouse model was used for in vivo experiments.IL-21R mRNA was detected in all biopsy specimens from patients with SSc and controls, with a 4.7-fold increase observed in SSc samples. In situ hybridization and immunohistochemical analysis showed an up-regulation of IL-21R in samples of epidermis from SSc patients, whereas no signal was detected in skin specimens from healthy controls. These results were confirmed in vitro, in that cultured keratinocytes expressed significant levels of IL-21R, whereas no signal was observed in fibroblasts. Interestingly, mRNA for IL-21 could not be detected by real-time PCR and in situ hybridization. Various concentrations of key cytokines in the pathogenesis of SSc did not stimulate the expression of IL-21R mRNA in cultured keratinocytes and dermal fibroblasts. In the SCID mouse transplantation model, the overexpression of IL-21R mRNA in SSc keratinocytes remained unchanged after transplantation.The up-regulation of IL-21R in keratinocytes indicates that, similar to fibroblasts and endothelial cells, the expression pattern is altered in SSc. Moreover, the expression of IL-21R appears to be independent of key cytokines that are operant in SSc.

Abstract Objective Src kinases are nonreceptor tyrosine kinases, which have been implicated in cytoskeletal organization and cell mobility. This study was undertaken to evaluate the potential of Src kinases as novel targets of antifibrotic therapies. Methods Fibroblast cultures were obtained from 10 patients with systemic sclerosis (SSc) and 5 healthy subjects. Src signaling was inhibited using small‐molecule inhibitors and overexpression of a dominant‐negative mutant of Src and of the endogenous inhibitor Csk. The expression of extracellular matrix proteins was analyzed by real‐time polymerase chain reaction and by SirCol collagen assay. Toxic effects were excluded by MTT assay and staining for annexin V and propidium iodide. The mouse model of bleomycin‐induced dermal fibrosis was used to assess the role of Src kinases in dermal fibrosis in vivo. Results Stimulation with transforming growth factor β and platelet‐derived growth factor activated Src signaling in dermal fibroblasts from patients with SSc and healthy donors. Incubation with the Src kinase inhibitors or overexpressed mutant Src or Csk reduced the synthesis of messenger RNA for COL1A1, COL1A2, and fibronectin 1. A dose‐dependent reduction in collagen release was also observed at the protein level. No inhibitory effects on proliferation and no increase in the number of apoptotic or necrotic fibroblasts were observed. Consistent with the in vitro data, inhibition of Src kinases prevented experimental dermal fibrosis. Dermal thickness, the amount of collagen protein, and the number of myofibroblasts were reduced in a dose‐dependent manner. Conclusion These findings indicate that Src kinases play important roles in the activation of fibroblasts and in the development of experimental fibrosis. Thus, Src kinases might be interesting targets for novel antifibrotic therapies in SSc.

Abstract Objective Rho‐associated kinases (Rock) are the major cellular mediators of Rho GTPases and play an important role in the organization of the actin cytoskeleton. Inhibitors of Rock are currently being evaluated for the treatment of pulmonary arterial hypertension. This study was undertaken to analyze the role of Rock in the activation of fibroblasts in systemic sclerosis (SSc). Methods Rock signaling was inhibited using chemical inhibitors and small interfering RNA. The expression of extracellular matrix (ECM) proteins and α‐smooth muscle actin was analyzed by real‐time polymerase chain reaction, Western blotting, and SirCol assay. Metabolic activity was quantified by MTT assay. Cell viability was assessed by staining with annexin V and propidium iodide. The role of MAP kinases was investigated using selective inhibitors and Western blotting. Results Inhibition of Rock strongly reduced the synthesis of the major ECM proteins at the messenger RNA level as well as the protein level. Counterregulatory changes in the expression of tissue inhibitors of metalloproteinases and matrix metalloproteinases were not observed. Inhibition of Rock prevented myofibroblast differentiation. Transforming growth factor β activated ERK in a Rock‐dependent manner, and ERK mediated in part the stimulatory effects of Rock on myofibroblast differentiation. Toxic adverse effects of the inhibition of Rock were not observed. Conclusion Our findings demonstrate that Rock potently stimulates the differentiation of resting fibroblasts into myofibroblasts and the production of ECM at biologically relevant concentrations without cell toxicity. These findings, along with the beneficial effects of Rock inhibition on vascular disease, indicate that inhibition of Rock might be an interesting novel therapeutic approach for the treatment of SSc.

Abstract Objective To determine whether the functional BANK1 variants rs3733197 and rs10516487 are associated with systemic sclerosis (SSc) in 2 European Caucasian populations and to investigate the putative gene–gene interactions between BANK1 and IRF5 as well as STAT4 . Methods BANK1 single‐nucleotide polymorphisms were genotyped in a total population of 2,432 individuals. The French cohort consisted of 874 SSc patients and 955 controls (previously genotyped for both IRF5 rs2004640 and STAT4 rs7574865). The German cohort consisted of 421 SSc patients and 182 controls. Results The BANK1 variants were found to be associated with diffuse cutaneous SSc (dcSSc) in both cohorts, providing an odds ratio (OR) of 0.77 for the rs10516487 T rare allele in the combined populations of dcSSc patients as compared with the combined populations of controls (95% confidence interval [95% CI] 0.64–0.93) and an OR of 0.73 (95% CI 0.61–0.87) for the rs3733197 A rare allele. BANK1 haplotype analysis found the A‐T haplotype to be protective in dcSSc patients (OR 0.70 [95% CI 0.57–0.86], P = 3.39 × 10 −4 ) and the G‐C haplotype to be a risk factor (OR 1.25 [95% CI 1.06–1.47], P = 0.008). Significant differences were also observed when the limited cutaneous subset of SSc was compared with the dcSSc subset, both for the rare alleles and for the haplotypes. The BANK1 , IRF5 , and STAT4 risk alleles displayed a multiplicatively increased risk of dcSSc of 1.43‐fold. Conclusion Our results establish BANK1 as a new SSc genetic susceptibility factor and show that BANK1 , IRF5 , and STAT4 act with additive effects.

Microvascular damage is one of the first pathological changes in systemic sclerosis. In this study, we investigated the role of Fos-related antigen-2 (Fra-2), a transcription factor of the activator protein-1 family, in the peripheral vasculopathy of systemic sclerosis and examined the underlying mechanisms.Expression of Fra-2 protein was significantly increased in skin biopsies of systemic sclerosis patients compared with healthy controls, especially in endothelial and vascular smooth muscle cells. Fra-2 transgenic mice developed a severe loss of small blood vessels in the skin that was paralleled by progressive skin fibrosis at 12 weeks of age. The reduction in capillary density was preceded by a significant increase in apoptosis in endothelial cells at week 9 as detected by immunohistochemistry. Similarly, suppression of Fra-2 by small interfering RNA prevented human microvascular endothelial cells from staurosporine-induced apoptosis and improved both the number of tubes and the cumulative tube lengths in the tube formation assay. In addition, cell migration in the scratch assay and vascular endothelial growth factor-dependent chemotaxis in a modified Boyden chamber assay were increased after transfection of human microvascular endothelial cells with Fra-2 small interfering RNA, whereas proliferation was not affected.Fra-2 is present in human systemic sclerosis and may contribute to the development of microvasculopathy by inducing endothelial cell apoptosis and by reducing endothelial cell migration and chemotaxis. Fra-2 transgenic mice are a promising preclinical model to study the mechanisms and therapeutic approaches of the peripheral vasculopathy in systemic sclerosis.

The cannabinoid receptor CB2 is predominantly expressed in non-neuronal tissue and exerts potent immunomodulatory effects. This study was undertaken to evaluate the role of CB2 in the pathogenesis of dermal fibrosis.Mice deficient in CB2 (CB2(-/-) mice) and their wild-type littermates (CB2(+/+) mice) were injected with bleomycin to induce experimental fibrosis. Mice were treated with selective agonists and antagonists of CB2. Lesional skin was evaluated for dermal thickness and numbers of infiltrating leukocytes. Bone marrow transplantation experiments were performed.CB2(-/-) mice were more sensitive to bleomycin-induced dermal fibrosis than were CB2(+/+) mice, and showed increased dermal thickness. Leukocyte counts were significantly higher in the lesional skin of CB2(+/+) mice. Increased dermal fibrosis was also observed upon treatment with the CB2 antagonist AM-630. In contrast, the selective CB2 agonist JWH-133 reduced leukocyte infiltration and dermal thickening. The phenotype of CB2(-/-) mice was mimicked by transplantation of CB2(-/-) bone marrow into CB2(+/+) mice, whereas CB2(-/-) mice transplanted with bone marrow from CB2(+/+) mice did not display an increased sensitivity to bleomycin-induced fibrosis, indicating that leukocyte expression of CB2 critically influences experimental fibrosis.Our findings indicate that CB2 limits leukocyte infiltration and tissue fibrosis in experimental dermal fibrosis. Since selective CB2 agonists are available and well tolerated, CB2 might be an interesting molecular target for the treatment of early inflammatory stages of systemic sclerosis.

Objective. Churg–Strauss Syndrome (CSS) is characterized by excessive eosinophil accumulation in peripheral blood and affected tissues with development of granulomatous vasculitic organ damage. The contribution of eosinophil-chemotactic cytokines (eotaxin family) to eosinophilia and disease activity in CSS is unknown. Thus, we compared serum levels of the eotaxin family members in CSS patients with healthy and disease controls. Methods. Forty patients with CSS diagnosed according to ACR 1990 criteria, 30 healthy controls (HC) and 57 disease controls (28 asthma, 20 small vessel vasculitis, 9 hypereosinophilic syndrome) were studied. Clinical data were collected and serum levels of eotaxin-1, -2 and -3 were determined by ELISA. Further, immunohistochemistry was applied to identify eotaxin-3 expression in tissue biopsies from patients with CSS. Results. In contrast to eotaxin-1 and -2, eotaxin-3 was highly elevated in serum samples of active CSS patients and correlated highly significantly with eosinophil counts, total immunoglobulin E (IgE) levels and acute-phase parameters. Moreover, eotaxin-3 was not elevated in other eosinophilic and vasculitic diseases. Immunohistochemical analysis revealed strong expression of eotaxin-3 in endothelial and inflammatory cells in affected tissues of active CSS patients. Conclusions. This study reveals the specific association of elevated eotaxin-3 expression with high disease activity and eosinophilia in CSS patients. Eotaxin-3 might thus be a pathogenic player, biomarker and potential therapeutic target in CSS.

Autoimmunity, microangiopathy and tissue fibrosis are hallmarks of systemic sclerosis (SSc). Vascular alterations and reduced capillary density decrease blood flow and impair tissue oxygenation in SSc. Oxygen supply is further reduced by accumulation of extracellular matrix (ECM), which increases diffusion distances from blood vessels to cells. Therefore, severe hypoxia is a characteristic feature of SSc and might contribute directly to the progression of the disease. Hypoxia stimulates the production of ECM proteins by SSc fibroblasts in a transforming growth factor-beta-dependent manner. The induction of ECM proteins by hypoxia is mediated via hypoxia-inducible factor-1alpha-dependent and -independent pathways. Hypoxia may also aggravate vascular disease in SSc by perturbing vascular endothelial growth factor (VEGF) receptor signalling. Hypoxia is a potent inducer of VEGF and may cause chronic VEGF over-expression in SSc. Uncontrolled over-expression of VEGF has been shown to have deleterious effects on angiogenesis because it leads to the formation of chaotic vessels with decreased blood flow. Altogether, hypoxia might play a central role in pathogenesis of SSc by augmenting vascular disease and tissue fibrosis.

Abstract Objective We have recently shown a significant reduction in cytokine‐induced transcription of type I collagen and fibronectin in systemic sclerosis (SSc) skin fibroblasts upon treatment with trichostatin A (TSA). Moreover, in a mouse model of fibrosis, TSA prevented the dermal accumulation of extracellular matrix. The purpose of this study was to analyze the silencing of histone deacetylase 7 (HDAC‐7) as a possible mechanism by which TSA exerts its antifibrotic function. Methods Skin fibroblasts from patients with SSc were treated with TSA and/or transforming growth factor β. Expression of HDACs 1–11, extracellular matrix proteins, connective tissue growth factor (CTGF), and intercellular adhesion molecule 1 (ICAM‐1) was analyzed by real‐time polymerase chain reaction, Western blotting, and the Sircol collagen assay. HDAC‐7 was silenced using small interfering RNA. Results SSc fibroblasts did not show a specific pattern of expression of HDACs. TSA significantly inhibited the expression of HDAC‐7, whereas HDAC‐3 was up‐regulated. Silencing of HDAC‐7 decreased the constitutive and cytokine‐induced production of type I and type III collagen, but not fibronectin, as TSA had done. Most interestingly, TSA induced the expression of CTGF and ICAM‐1, while silencing of HDAC‐7 had no effect on their expression. Conclusion Silencing of HDAC‐7 appears to be not only as effective as TSA, but also a more specific target for the treatment of SSc, because it does not up‐regulate the expression of profibrotic molecules such as ICAM‐1 and CTGF. This observation may lead to the development of more specific and less toxic targeted therapies for SSc.

Fra-2 belongs to the activator protein 1 family of transcription factors. Mice transgenic for Fra-2 develop a systemic fibrotic disease with vascular manifestations similar to those of systemic sclerosis (SSc). The aim of the present study was to investigate whether Fra-2 plays a role in the pathogenesis of SSc and to identify the molecular mechanisms by which Fra-2 induces fibrosis.Dermal thickness and the number of myofibroblasts were determined in skin sections from Fra-2-transgenic and wild-type mice. The expression of Fra-2 in SSc patients and in animal models of SSc was analyzed by real-time polymerase chain reaction and immunohistochemistry. Fra-2, transforming growth factor beta (TGFbeta), and ERK signaling in SSc fibroblasts were inhibited using small interfering RNA, neutralizing antibodies, and small-molecule inhibitors.Fra-2-transgenic mice developed a skin fibrosis with increases in dermal thickness and increased myofibroblast differentiation starting at age 12 weeks. The expression of Fra-2 was up-regulated in SSc patients and in different mouse models of SSc. Stimulation with TGFbeta and platelet-derived growth factor (PDGF) significantly increased the expression of Fra-2 in SSc fibroblasts and induced DNA binding of Fra-2 in an ERK-dependent manner. Knockdown of Fra-2 potently reduced the stimulatory effects of TGFbeta and PDGF and decreased the release of collagen from SSc fibroblasts.We demonstrate that Fra-2 is overexpressed in SSc and acts as a novel downstream mediator of the profibrotic effects of TGFbeta and PDGF. Since transgenic overexpression of Fra-2 causes not only fibrosis but also vascular disease, Fra-2 might be an interesting novel candidate for molecular-targeted therapies for SSc.

Fibrosis is characterized by an excessive deposition of extracellular matrix (ECM) components, predominantly of collagens. Fibrotic changes have been observed in various diseases affecting different organs, such as the skin, lung, liver, and kidney. Current concepts of fibrogenesis suggest a cascade of events similar to those in wound healing (1, 2). An initial trigger or injury activates resident cells, which produce proinflammatory mediators. The resulting gradient of chemotactic cytokines guides the infiltration of inflammatory cells, which in turn, produce profibrotic mediators such as transforming growth factor β (TGFβ), platelet-derived growth factor, and interleukin-4 (IL-4) (3). Depending on the organ involved, these cytokines activate fibroblasts, hepatic stellate cells, mesangial cells, or tubular epithelial cells, leading to an increased production of ECM proteins. In later stages of the fibrotic diseases, profibrotic cytokines are often produced by resident cells. In addition to an increased production of ECM proteins, an imbalance between matrix-degrading enzymes and their inhibitors might contribute to the development of fibrosis. The matrix components accumulate in the extracellular compartment and disrupt the physiologic tissue structure, often causing severe functional impairment of the involved organs. Tumor necrosis factor α (TNFα) is produced by a wide variety of hematopoietic and nonhematopoietic cells, such as macrophages, CD4+ and CD8+ T cells, B cells, natural killer cells, neutrophils, smooth muscle cells, endothelial cells, and fibroblasts (4). TNFα exists in 2 forms, a membrane-bound form and a soluble form, both of which are functional and contribute to the effects of TNFα (5, 6). Human TNFα is expressed as a precursor protein with a molecular mass of 26 kd, which is then enzymatically cleaved to yield a 17-kd active form. Under physiologic conditions, TNFα forms homotrimers, which interact and crosslink with the respective receptors. TNFα binds with high affinity to 2 transmembrane receptors, TNF receptor I (TNFRI; also referred to as TNFRβ, p55, or CD120a) and TNFRII (also referred to as TNFRα or p75) (7). The homology between the 2 receptors is limited, especially within their intracellular regions (7, 8). The expression of TNFRI and TNFRII is differentially regulated. The expression of TNFRI seems to be controlled by a housekeeping promoter with high basal activity and only a weak response to stimulation. In contrast, the expression of TNFRII is strongly influenced by external factors (9, 10). TNFRI can mediate almost all activities of TNFα, whereas TNFRII transduces signals at physiologic levels only in a few cell types such as T cells (11). However, TNFRII plays an important role in fine-tuning TNFRI signaling. Due to its higher affinity, TNFRII binds TNFα preferentially at low concentrations. TNFα is then passed to neighboring TNFRI molecules, which allows TNFα to exert its effects at lower concentrations (12). The efficacy of TNFα antagonists in inflammatory diseases such as rheumatoid arthritis (RA), spondylarthropathies, and Crohn's disease has been demonstrated in numerous clinical trials and plays an important role in the treatment of patients with these diseases (13-15). Recent reports suggest that TNFα antagonists might also be beneficial for the treatment of fibrotic disorders. In a retrospective case series, treatment with etanercept appeared to be efficacious in improving active inflammatory joint disease in patients with systemic sclerosis (SSc). Etanercept was generally well tolerated, and skin fibrosis was reduced under treatment in this uncontrolled study (16). Similarly, investigators in another case series reported on outcomes in 4 patients with SSc and erosive arthritis treated with TNFα antagonists (17). TNFα antagonists not only improved arthritis, but the modified Rodnan skin thickness score (MRSS) (18), used as a clinical score for the quantification of skin fibrosis in SSc patients, also decreased in all patients, with reductions of >50% in 3 patients. Another case report showed stabilization of lung fibrosis in a patient with SSc under treatment with infliximab (19). Three additional open-label studies with etanercept or infliximab have been reported in abstract form (20-22). Overall, treatment was well tolerated in these case series, including long-term application for a mean of 24 months in 1 study. The MRSS was stable or improved, and levels of N-terminal propeptide of type III procollagen as a biomarker for fibrosis decreased under treatment in 1 study. While definite conclusions cannot be drawn from open-label, uncontrolled case series, these data suggest that TNFα antagonists might play a role in the treatment of fibrotic diseases. However, TNFα has long been considered an antifibrotic cytokine, and treatment with TNFα antagonists might not be safe in SSc patients. Accordingly, another case report showed that treatment with adalimumab was associated with fatal exacerbation of fibrosing alveolitis in a patient with SSc (23). Similarly, TNFα antagonists have been associated with fibrosing alveolitis in patients with RA in a number of case reports (24). Thus, before TNFα antagonists can be considered for the treatment of patients with fibrotic diseases, the following open questions have to be addressed: What is the experimental evidence for TNFα antagonists for the treatment of fibrotic disorders? Do molecular studies demonstrate a profibrotic role of TNFα, or do they rather show antifibrotic effects of TNFα? In this review, we discuss in detail the results of in vitro and in vivo studies analyzing the role of TNFα signaling in organ fibrosis, with a focus on skin and pulmonary fibrosis, to provide a basis for further clinical studies in rheumatic diseases. The effects of TNFα on the production of collagen and the turnover of ECM have been analyzed in numerous studies (Table 1). Mauviel and coworkers (25, 26) demonstrated that TNFα inhibits the synthesis of type I collagen in cultured dermal fibroblasts on the transcriptional level, resulting in a dose-dependent reduction of the production of type I collagen as measured by radioimmunoassay and gel electrophoresis. In addition, TNFα inhibited the synthesis of type III collagen and fibronectin (25). TNFα also plays an important role in the inhibitory effects of CD4+ T cells on collagen production in dermal fibroblasts. Th1 and Th2 cells activated by CD3 crosslinking as well as preparations of Th1 and Th2 plasma membranes significantly decreased the production of collagen in dermal fibroblasts from healthy controls (27). Antagonism of TNFα by the addition of soluble TNFRI, but not neutralization of IL-4 and interferon-γ, significantly reduced the inhibitory activity of T cells on matrix production. Addition of Th2 membranes to fibroblasts stimulated with the profibrotic cytokines TGFβ and IL-4 abrogated the increased production of collagen, demonstrating that the inhibition by Th2 membranes was dominant over the stimulatory effects of TGFβ and IL-4. Interestingly, these antifibrotic mechanisms of TNFα via T cell membranes might not be fully active in fibrotic diseases, because SSc fibroblasts were resistant to inhibition by Th2 membranes and less sensitive to inhibition by Th1 membranes compared with healthy fibroblasts. The inhibitory effects of TNFα on the production of collagen are partially mediated by NF-κB. Using electrophoretic mobility shift assays (EMSAs) and supershift assays, Kouba and coworkers (28) demonstrated that RelA–NF-κB (p65–p50) complexes bind to a cis element adjacent to the promoter of COL1A2. Mutation of the NF-κB binding site almost completely prevented the inhibitory effects of TNFα. The crucial role of NF-κB in the down-regulation of COL1A2 synthesis was confirmed using fibroblasts deficient in the NF-κB–essential modulator (NEMO) (29). NEMO is activated in response to inflammatory stimuli and activates the associated IκB kinases (IKKs). In turn, IKKs phosphorylate IκB. Phosphorylated IκB dissociates from NF-κB, which can then enter the nucleus and activate transcription of NF-κB–dependent genes. NEMO deficiency prevented the inhibitory effects of TNFα on COL1A2 transcription. Similar results were also obtained in dermal fibroblasts transfected with dominant-negative forms of IKKα (29). In addition to direct effects on the transcription of collagens, TNFα might exert antifibrotic properties by interfering with TGFβ signaling cascades (30). Incubation of neonatal human foreskin fibroblasts with TNFα 1 hour prior to stimulation with TGFβ prevented Smad-specific gene transcription, as analyzed with reporter constructs of the Smad3/4-binding element (SBE). The inhibitory effect of TNFα on the activation of TGFβ-dependent Smad signaling was not mediated by induction of the inhibitory Smad7, but rather, was inhibited by activator protein 1 (AP-1)–dependent pathways. JunB and c-Jun, 2 members of the AP-1 family, are strongly induced in dermal fibroblasts upon stimulation with TNFα. Overexpression of JunB and c-Jun abrogated the Smad3-dependent transactivation of the SBE reporter construct in a dose-dependent manner. The important role of AP-1 signaling for the inhibitory effect of TNFα was further supported by experiments demonstrating that expression of antisense c-Jun messenger RNA (mRNA) prevented the inhibition of TGFβ/Smad signaling by TNFα. The inhibitory effects of JunB and c-Jun on Smad signaling are mediated by 2 distinct mechanisms. Coprecipitation assays and EMSAs demonstrated that JunB and c-Jun form heterocomplexes with Smad3 and that JunB and c-Jun reduce the binding of Smad3 to its cognate cis DNA element. These findings suggest that Smad3–AP-1 interactions may sequester Smad3 and compete against Smad3 for binding to DNA. Furthermore, JunB and c-Jun bind p300, a cofactor essential for optimal transcription of Smad-regulated genes. Because the amount of p300 in the nucleus is limited, competition of JunB and c-Jun with Smad3 for p300 can efficiently prevent Smad signaling (30). In addition to its direct effects on the synthesis of ECM proteins, TNFα regulates the expression of matrix-degrading enzymes and their inhibitors. TNFα induced matrix metalloproteinase 1 (MMP-1) mRNA and protein in a dose-dependent manner in dermal, gingival, and synovial fibroblasts (31, 32). Furthermore, higher concentrations of TNFα reduced the expression of tissue inhibitor of metalloproteinases 1 (TIMP-1), thereby promoting the degradation of ECM proteins (33). The effects of TNFα on collagen synthesis and on the production of MMPs and TIMPs are not restricted to fibroblasts and are also found in other cell types (34). In contrast to the results discussed above, a recent study suggested that TNFα might promote a profibrotic phenotype in murine intestinal myofibroblasts in vitro (35). In vimentin- and α-smooth muscle actin–positive myofibroblasts isolated from wild-type (WT) mice, murine TNFα stimulated collagen synthesis, increased expression of TIMP-1, and decreased activity of MMP-2. Similar results were also obtained with myofibroblasts from mice homozygous for the disruption of the gene for TNFRI (TNFRI−/− mice). However, no induction of collagen was observed in myofibroblasts from TNFRII−/− mice and from TNFRI−/− and TNFRII−/− double-knockout mice (TNFRI−/−/II−/− mice), suggesting that the profibrotic effect of TNFα on myofibroblasts is mediated by signaling via TNFRII. It remains unclear why the effects of TNFα on the production of ECM in that study differed from those found in previous studies. The concentrations of TNFα used were within the range of those used in other studies, and species-specific differences can be excluded because murine fibroblasts respond to TNFα with an up-regulation of collagen and induction of MMPs similar to that found in human fibroblasts (29). However, the effects of TNFα might be cell type and organ specific, and intestinal myofibroblasts might react differently from other cell types. Investigators in another in vitro study also proposed a profibrotic effect of TNFα, indirectly via induction of TGFβ (36). Incubation of Swiss 3T3 cells (a mouse fibroblast cell line) and primary mouse fibroblasts with TNFα stimulated the expression of TGFβ mRNA and protein. The induction of TGFβ by TNFα was blocked by inhibitors of the ERK-specific MAPK pathway. However, it remains unclear whether the induction of TGFβ is sufficient to overcome the inhibitory effects of TNFα on collagen production, since the investigators did not analyze the expression of collagen. The induction of TGFβ upon stimulation with TNFα might therefore represent a counterregulatory mechanism to compensate for the inhibitory effects of TNFα on Smad signaling. Phagocytosis of collagen has been suggested to play a role in the homeostasis of the ECM, and inhibition of this phagocytosis might therefore lead to fibrosis (37). Although this mechanism is currently not considered to play a major role, it might further enhance fibrotic processes. TNFα has been suggested to inhibit the phagocytosis of collagen by fibroblasts, and it might also therefore enhance fibrotic processes via this mechanism. Incubation with TNFα increased slightly the expression of α1β1 integrin and α2β1 integrin, which bind collagen in human gingival fibroblasts, but the binding of collagen was significantly decreased, suggesting an inactivation of the binding sites for collagen by TNFα (38). Consistent with decreased binding, the percentage of phagocytosed collagen beads per cell and the proportion of phagocytically active gingival fibroblasts were reduced in a dose-dependent manner by TNFα. Results from animal studies of the overexpression of TNFα are inconsistent regarding the effects on ECM synthesis (Table 2). A number of studies indicate profibrotic effects of TNFα. Overexpression of TNFα in the lungs has been linked to fibrosis. Using a replication-deficient adenovirus, a prolonged overexpression of TNFα for 7–10 days was achieved in the lungs of rats (39). This local overexpression resulted in severe infiltration of the lungs by neutrophils, macrophages, and lymphocytes. Later on, increased expression of TGFβ was detected and myofibroblasts appeared. After the inflammation subsided, a patchy fibrosis developed that persisted beyond day 64. These data are supported by the analysis of peripheral CD4+ T cells from patients with idiopathic pulmonary fibrosis. Compared with those from normal subjects, these CD4+ T cells synthesized higher levels of TNFα, as analyzed by intracellular fluorescence-activated cell sorting staining (40). The role of TNFα in pulmonary fibrosis has also been analyzed with transgenic mice overexpressing murine TNFα in the lungs under the control of the human surfactant protein C (SP-C) promoter. These mice spontaneously developed a chronic lymphocytic alveolitis, and its severity correlated with the expression of TNFα mRNA in the lungs (41). The transgenic mice also had greater lung volumes, pulmonary hypertension, and decreased elastic recoil compared with control mice. Histologically, the investigators observed thickened alveolar walls due to accumulation of desmin-containing fibroblasts and collagen fibers, a phenotype resembling idiopathic pulmonary fibrosis. Similar profibrotic effects of TNFα were observed in animal models of congestive heart failure using modified TNFα-transgenic mice (42, 43). Accordingly, continuous subcutaneous infusion of TNFα led to abundant infiltration with polymorphonuclear leukocytes and stimulated the growth of dermal fibroblasts, resulting in an increased local deposition of collagen (44). While these studies suggest that TNFα is a profibrotic cytokine, other studies in mice overexpressing TNFα indicate antifibrotic effects and a protective role of TNFα in models of experimental fibrosis. A more recent study by a different group on the same transgenic mice with lung-specific TNFα expression under the control of the human SP-C promoter led to different conclusions. Fujita and colleagues (45) confirmed the presence of chronic pulmonary inflammation and increased lung volumes with an increase in the total amount of hydroxyproline in the lungs. However, when the hydroxyproline content was normalized for the lung weight, no differences were observed between TNFα-transgenic mice and controls. Accordingly, Fujita et al observed only very little fibrosis in the lungs of transgenic animals. Furthermore, TNFα-transgenic mice were resistant to experimental pulmonary fibrosis induced by bleomycin or by overexpression of TGFβ. In contrast to WT mice, no increase in the hydroxyproline content and no fibrotic changes in histologic sections were observed in TNFα-transgenic mice. It needs to be stressed that the determination of the hydroxyproline content is often misleading, especially under inflammatory conditions, in which inflammatory cells produce C1q (which also contains hydroxyproline). The fact that type III collagen contains 30% more hydroxyproline than does type I collagen also contributes to this problem. The antifibrotic role of TNFα in experimental pulmonary fibrosis in these animals was further supported by experiments demonstrating that application of recombinant human TNFα attenuated bleomycin-induced pulmonary fibrosis in WT mice. An antifibrotic effect of TNFα was also reported by Buck and coworkers (46). They demonstrated that inoculation of nude mice with Chinese hamster ovary cells secreting TNFα resulted in a decreased collagen synthesis in the skin, which also led to impaired wound healing and was paralleled by decreased expression of TGFβ. Similar results in the liver were obtained by the same group (47). Studies by Piguet and coworkers (48, 49) demonstrated that TNFα antagonists can significantly reduce the accumulation of ECM in mouse models of silica- and bleomycin-induced pulmonary fibrosis. Silica and bleomycin stimulate the expression of TNFα and lead to a patchy fibrosis after 15 days. Infusion of anti-TNFα antibodies or recombinant soluble TNFRI prevented the development of fibrosis in both models. Treatment of established fibrosis with soluble TNFRI was also effective, as demonstrated by experiments in which soluble TNFRI was administered 25 days after bleomycin and silica. Accordingly, continuous infusion of recombinant TNFα strongly augmented the fibrotic process (48). Beneficial effects of TNFα inhibitors were also found in a transplantation model (50). When tracheas from Brown-Norway rats were transplanted into Lewis rats, obliterative airway disease with inflammatory infiltrates and fibroproliferative lesions developed. Luminal occlusion occurred in 58% of untreated animals after 14 days. When animals were treated with antibodies against TNFα or with RDP-58, a translational inhibitor of TNFα, fibroproliferative lesions were strongly reduced and the percentage of luminal occlusion decreased from 58% to 32%. Similar antifibrotic effects with anti-TNFα antibodies were observed in experimental crescentic glomerulonephritis as a model for kidney fibrosis (51). Numerous studies have analyzed outcomes in mice deficient in TNFRI (TNFRI−/− mice), TNFRII (TNFRII−/− mice), or both receptors (TNFRI−/−/II−/− mice) in different models of organ fibrosis. In contrast to experiments with TNFα-transgenic mice, these studies demonstrated uniformly that inhibition of signaling via TNFRI and TNFRII prevents the development of fibrosis. For instance, TNFRI−/−/II−/− mice were protected from experimental pulmonary fibrosis induced by silica, asbestos, and bleomycin (52-54). In contrast to WT mice, TNFRI−/−/II−/− mice did not demonstrate significant inflammation or increased proliferation in the lungs after exposure to profibrotic agents, the induction of TNFα was diminished, and there was no increased deposition of ECM. Similar results were obtained with TNFRI−/− and TNFRI−/−/II−/− mice in different models of liver and kidney fibrosis, while TNFRII−/− mice were not protected from kidney and liver fibrosis (55-59). Results of in vitro and in vivo experiments concerning the role of TNFα in fibrosis are in part contradictory and do not allow definite conclusions about the role of TNFα as a profibrotic mediator or an antifibrotic cytokine. The majority of in vitro studies show antifibrotic effects of TNFα, in that it suppresses the production of collagen, reduces the expression of TIMPs, and stimulates the release of MMPs, thereby preventing the accumulation of ECM. The intracellular signaling pathways that mediate these effects have been identified and include activation of JunB and c-Jun. However, under certain circumstances, TNFα might have profibrotic effects in vitro. Myofibroblasts in particular, which are thought to play a central role in fibrotic disorders such as SSc by releasing large amounts of ECM proteins, might react to TNFα differently from resting fibroblasts. While the in vitro studies overall favor TNFα as an antifibrotic cytokine, different in vivo animal studies with antagonists of TNFα and mice lacking TNFRI or both TNFα receptors demonstrated that inhibition of TNFα signaling can prevent fibrosis. However, studies on TNFα-transgenic mice yielded different results, with most suggesting a profibrotic role of TNFα. In our opinion, these differences in the results between in vitro and in vivo studies might be explained by the inflammatory component in animal models of experimental fibrosis (Figure 1). Most of these models depend critically on a strong inflammatory component at the initial stages as a trigger for the later development of fibrosis. As a major proinflammatory stimulus, TNFα has been shown to play an important role in the activation of inflammatory cells. Inflammatory conditions and cellular inflammatory infiltrates are absent in vitro, and TNFα can exert its direct effects on the matrix-producing cells. In our view, a likely scenario is that the direct antifibrotic effects of TNFα on fibroblasts might be outweighed in experimental models of fibrosis by its important role in driving inflammation. Tumor necrosis factor α (TNFα) exerts prominent proinflammatory properties and activates inflammatory cells in the initial phases of experimental models of fibrosis. Inflammatory cells secrete profibrotic mediators, which activate fibroblasts. Activated fibroblasts produce increased amounts of extracellular matrix, resulting in tissue fibrosis in later stages. However, TNFα directly inhibits the synthesis of extracellular matrix proteins in fibroblasts in vitro in most studies. We do not yet have a clear picture of the net result of these contrary effects in human fibrotic diseases, in which inflammation is often less pronounced than in experimental models. Thus, to predict the effects of anti-TNFα treatments in human fibrotic diseases, the key question is whether inflammation triggers and perpetuates the development of fibrosis in humans. The role of inflammation in human fibrotic diseases is less clear than was initially thought; it might differ between the specific organs and might also depend on other parameters such as disease duration. For example, in SSc skin fibrosis, inflammatory infiltrates are thought to play an important role in very early disease stages, but are rarely seen in later stages of the disease. This might predict that anti-TNFα treatments could be a promising antifibrotic strategy for very early inflammatory skin fibrosis in SSc, while it might even be deleterious for later noninflammatory stages of skin fibrosis. Accordingly, the effects on lung fibrosis might be different from those on skin fibrosis. Inflammation is thought to play a more important role in interstitial pulmonary fibrosis associated with SSc, with recurrent alveolitis triggering progression of fibrosis during the course of the disease. If this concept holds true, patients with pulmonary fibrosis and alveolitis might benefit from anti-TNFα treatments, while the effects on lung fibrosis might again be deleterious in patients with no evidence of inflammation/alveolitis. However, it must be emphasized that this concept is theoretical, because so far, no controlled study has looked at the effects of TNFα in inflammatory phases of SSc. Taken together, the results of available molecular and cellular studies do not allow definite conclusions about the role of TNFα in fibrotic diseases. More experimental studies are necessary, with a particular focus on fibrotic animal models that are independent of inflammation as a trigger for the fibrotic process. Cellular studies have lacked a complete description of the transcriptom after TNF or anti-TNF treatment, which would provide a more comprehensive analysis and, together with a proteomics study, could elucidate the contradictory findings reported so far instead of analyzing only selective and expected pathways. Open-label uncontrolled studies with TNFα inhibitors in SSc appear to be promising. However, from the existing literature, there are concerns that treatment with TNFα antagonists could lead to progression of fibrosis. Therefore, TNFα antagonists should not be used in daily clinical practice for the treatment of patients with fibrotic diseases until these concerns are cleared. To elucidate the definitive clinical effects of TNFα antagonists in fibrotic diseases, placebo-controlled trials need to be performed. Patients with inflammatory stages of the fibrotic disease are most likely to respond, while patients with noninflammatory stages of fibrosis might even show deleterious effects. Regarding safety issues, these trials need to focus on fibrosis outcomes in addition to the conventional safety issues such as infection and malignancy, and they need to be designed with sufficient statistical power to exclude potentially harmful effects.

Objectives Epigenetic modifications such as DNA methylation and histone acetylation have been implicated in the pathogenesis of systemic sclerosis. However, histone methylation has not been investigated so far. We therefore aimed to evaluate the role of the trimethylation of histone H3 on lysine 27 (H3K27me3) on fibroblast activation and fibrosis. Methods H3K27me3 was inhibited by 3-deazaneplanocin A (DZNep) in cultured fibroblasts and in two murine models of dermal fibrosis. Fibrosis was analysed by assessment of the dermal thickening, determination of the hydroxyproline content and by quantification of the numbers of myofibroblasts. The expression of fos-related antigen 2 (fra-2) was assessed by real-time PCR, western blot and immunohistochemistry and modulated by siRNA. Results Inhibition of H3K27me3 stimulated the release of collagen in cultured fibroblasts in a time and dose-dependent manner. Treatment with DZNep exacerbated fibrosis induced by bleomycin or by overexpression of a constitutively active transforming growth factor β receptor type I. Moreover, treatment with DZNep alone was sufficient to induce fibrosis. Inhibition of H3K27me3 induced the expression of the profibrotic transcription factor fra-2 in vitro and in vivo. Knockdown of fra-2 completely prevented the profibrotic effects of DZNep. Conclusions These data demonstrate a novel role of H3 Lys27 histone methylation in fibrosis. In contrast to other epigenetic modifications such as DNA methylation and histone acetylation, H3 Lys27 histone methylation acts as a negative regulator of fibroblast activation in vitro and in vivo by repressing the expression of fra-2.

Abstract Objective Microparticles are small, membrane‐coated vesicles that can serve as novel signaling structures between cells. The aim of the present study was to analyze the profile of microparticles in the blood of patients with systemic sclerosis (SSc; scleroderma) and healthy controls. Methods The study population consisted of 37 patients with SSc and 15 healthy subjects of comparable sex and age. Microparticles were isolated from plasma by high‐speed differential centrifugation. Microparticles were stained with monoclonal antibodies against cell type–specific markers and were quantified by fluorescence‐activated cell sorting analyses. Results The total number of microparticles was strongly increased in patients with SSc compared with healthy controls (mean ± SEM 88.0 ± 4.8 × 10 5 microparticles/ml plasma versus 42.3 ± 9.4 × 10 5 microparticles/ml plasma; P &lt; 0.001). Similarly, significant increases were found for microparticles derived from platelets, endothelial cells, monocytes, and T cells, reflecting the activation of these cells in SSc. Platelets were the most common source of microparticles in the blood of patients with SSc (66.9 ± 5.2% of all microparticles) and healthy donors, followed by microparticles derived from endothelial cells (8.8 ± 0.9% in SSc patients). The modified Rodnan skin thickness score (MRSS) was inversely correlated with the total number of microparticles. Furthermore, patients with cutaneous ulcers showed a significantly lower total number of microparticles. In multivariate analysis, an additive model of age, C‐reactive protein, MRSS, and subtype of disease accounted for 55% of the variability of the total microparticle count (r = 0.744). Conclusion The number of microparticles from different cellular sources is increased in the blood of SSc patients. Considering their role as important mediators of intercellular communication, microparticles could be a novel link between activated cellular compartments in the pathogenesis of SSc.

Systemic sclerosis (SSc) is complex autoimmune disease affecting the connective tissue; influenced by genetic and environmental components. Recently, we performed the first successful genome-wide association study (GWAS) of SSc. Here, we perform a large replication study to better dissect the genetic component of SSc. We selected 768 polymorphisms from the previous GWAS and genotyped them in seven replication cohorts from Europe. Overall significance was calculated for replicated significant SNPs by meta-analysis of the replication cohorts and replication-GWAS cohorts (3237 cases and 6097 controls). Six SNPs in regions not previously associated with SSc were selected for validation in another five independent cohorts, up to a total of 5270 SSc patients and 8326 controls. We found evidence for replication and overall genome-wide significance for one novel SSc genetic risk locus: CSK [P-value = 5.04 × 10−12, odds ratio (OR) = 1.20]. Additionally, we found suggestive association in the loci PSD3 (P-value = 3.18 × 10−7, OR = 1.36) and NFKB1 (P-value = 1.03 × 10−6, OR = 1.14). Additionally, we strengthened the evidence for previously confirmed associations. This study significantly increases the number of known putative genetic risk factors for SSc, including the genes CSK, PSD3 and NFKB1, and further confirms six previously described ones.

Churg-Strauss syndrome (CSS) is a Th2-mediated systemic vasculitis characterized by eosinophilic infiltration, blood eosinophilia, and high IgE levels. CCL17/thymus and activation-regulated chemokine (TARC) is a chemokine responsible for the recruitment of Th2 cells. This study was undertaken to explore a possible role of CCL17/TARC in CSS.CCL17/TARC levels in serum from patients with active or inactive CSS, hypereosinophilic syndrome, systemic small-vessel vasculitis other than CSS, other types of eosinophilia, and healthy controls were determined by enzyme-linked immunosorbent assay. Biopsy samples of affected tissue from CSS patients were examined by immunohistochemical staining for Th2 infiltration and CCL17/TARC expression.Serum CCL17/TARC levels were significantly elevated in CSS patients with active disease (mean ± SEM 1,122.0 ± 422.7 pg/ml) compared with controls (220.6 ± 27.9 pg/ml) and patients with inactive disease (388.9 ± 72.6 pg/ml) (P < 0.001 and P < 0.05, respectively). These levels correlated with the clinical disease course of CSS and with absolute eosinophil counts as well as IgE levels. Infiltrating Th2 cells in active CSS lesions were evidenced by CD294 staining. CCL17/TARC in the affected tissue of CSS patients was readily identified by immunohistochemical analysis. Elevated CCL17/TARC levels were also noted in patients with hypereosinophilic syndrome (794.5 ± 294.8 pg/ml) and other disorders associated with eosinophilia (1,096.0 ± 345.3 pg/ml) (both P < 0.005 versus controls).CCL17/TARC may contribute to CSS pathogenesis by recruitment of Th2 cells into affected tissue. Serum CCL17/TARC levels reflect disease activity, and further studies to validate its use as an activity marker in CSS are warranted.

Background Osteophyte formation is a common phenomenon in arthritis. Bone formation by endochondral ossification is considered a key pathophysiological process in the formation of osteophytes. Objective To examine the hypothesis that inhibition of smoothened (Smo), a key component of the hedgehog pathway inhibits osteophyte formation as the hedgehog pathway mediates endochondral ossification. Methods Arthritis was induced in 8-week-old C57/BL6 mice by serum transfer (K/BxN model). Mice were then treated by daily administration of either vehicle or LDE223, a specific small molecule inhibitor for Smo, over 2 weeks starting at the onset of disease. Clinical course of arthritis, histological and molecular changes of bone in the affected joints as well as systemic bone changes were assessed. Results Serum transfer-induced arthritis led to severe osteophyte formation within 2 weeks of onset. Blockade of Smo inhibited hedgehog signalling in vivo and also significantly inhibited osteophyte formation, whereas the clinical and histopathological signs of arthritis were not affected. Also, systemic bone mass did not change. Smo inhibitor particularly blocked the formation of hypertrophic chondrocytes and collagen type X expression. Conclusions The data indicate that blockade of hedgehog signalling by targeting Smo specifically inhibits osteophyte formation in arthritis without affecting inflammation and without eliciting bone destruction at the local and systemic level. Blockade of Smo may thus be considered as a strategy to specifically influence the periosteal bone response in arthritis associated with bone apposition.

<h3>Background</h3> Cannabinoids modulate fibrogenesis in scleroderma. Ajulemic acid (AjA) is a non-psychoactive synthetic analogue of tetrahydrocannabinol that can bind the peroxisome proliferator-activated receptor-γ (PPAR-γ). Recent evidence suggests a key role for PPAR-γ in fibrogenesis. <h3>Objective</h3> To determine whether AjA can modulate fibrogenesis in murine models of scleroderma. <h3>Material and methods</h3> Bleomycin-induced experimental fibrosis was used to assess the antifibrotic effects of AjA in vivo. In addition, the efficacy of AjA in pre-established fibrosis was analysed in a modified model of bleomycin-induced dermal fibrosis and in mice overexpressing a constitutively active transforming growth factor β (TGFβ) receptor I. Skin fibrosis was evaluated by quantification of skin thickness and hydroxyproline content. As a marker of fibroblast activation, α-smooth muscle actin was examined. To study the direct effect of AjA in collagen neosynthesis, skin fibroblasts from patients with scleroderma were treated with increasing concentrations of AjA. Protein expression of PPAR-γ, and its endogenous ligand 15d-PGJ2, and TGFβ were assessed before and after AjA treatment. <h3>Results</h3> AjA significantly prevented experimental bleomycin-induced dermal fibrosis and modestly reduced its progression when started 3 weeks into the disease. AjA strongly reduced collagen neosynthesis by scleroderma fibroblasts in vitro, an action which was reversed completely by co-treatment with a selective PPAR-γ antagonist. <h3>Conclusions</h3> AjA prevents progression of fibrosis in vivo and inhibits fibrogenesis in vitro by stimulating PPAR-γ signalling. Since therapeutic doses of AjA are well tolerated in humans, it is suggested that AjA as an interesting molecule targeting fibrosis in patients with scleroderma.

Abstract Objective To investigate whether c‐Jun and c‐Fos contribute to the pathologic activation of fibroblasts in systemic sclerosis (SSc) and to evaluate the antifibrotic potential of selective activator protein 1 (AP‐1) inhibition. Methods Expression of c‐Jun and c‐Fos was determined by real‐time polymerase chain reaction (PCR) and immunohistochemical analysis. Fibroblasts were stimulated with transforming growth factor β (TGFβ) and incubated with T‐5224, a small‐molecule inhibitor of AP‐1, or were transfected with small interfering RNA (siRNA) duplexes against c‐Jun and c‐Fos. Collagen synthesis was quantified by real‐time PCR and hydroxyproline assay. Differentiation of resting fibroblasts into myofibroblasts was assessed by staining for α‐smooth muscle actin and stress fibers. The antifibrotic potential of T‐5224 was evaluated in mouse models of dermal fibrosis induced by bleomycin or by adenoviral overexpression of a constitutively active TGFβ receptor type I. Results Up‐regulation of c‐Jun and c‐Fos was detected in mouse models of SSc and in the skin and dermal fibroblasts of patients with SSc. Stimulation of healthy fibroblasts with TGFβ induced the expression of c‐Jun and c‐Fos. Treatment with T‐5224 or nucleofection with siRNA directed against c‐Jun and c‐Fos abrogated the profibrotic effects of TGFβ. T‐5224 decreased the release of collagen selectively in SSc fibroblasts. T‐5224 was well tolerated and prevented dermal fibrosis induced by bleomycin or by adenoviral activation of TGFβ signaling. Conclusion AP‐1 is up‐regulated in a TGFβ‐dependent manner in SSc. The selective AP‐1 inhibitor T‐5224 reduced collagen synthesis selectively in SSc fibroblasts and efficiently prevented the development of experimental dermal fibrosis. Thus, AP‐1 might be a promising new molecular target for the treatment of SSc.

Abstract Objective To investigate the effect of chondromodulin 1 on the phenotype of osteochondral progenitor cells in cartilage repair tissue. Methods Self‐complementary adeno‐associated virus (AAV) vectors carrying chondromodulin 1 complementary DNA (AAV‐Chm‐1) were applied to cartilage lesions in the knee joints of miniature pigs that were treated by the microfracture technique. Alternatively, isolated porcine osteochondral progenitor cells were infected with AAV‐Chm‐1 or with AAV‐GFP control vectors ex vivo prior to being transplanted into cartilage lesions in which the subchondral bone plate was left intact. The quality of the repair tissue and the degree of endochondral ossification were assessed by histochemical and immunohistochemical methods. The effects of chondromodulin 1 overexpression were also analyzed by angiogenesis assays and quantitative reverse transcriptase–polymerase chain reaction. Results AAV‐Chm‐1–infected cells efficiently produced chondromodulin 1, which had strong antiangiogenic effects, as verified by the inhibition of tube formation of endothelial cells. Gene expression analyses in vitro revealed the cell cycle inhibitor p21 WAF1/Cip1 as one target up‐regulated by AAV‐Chm‐1. Direct application of AAV‐Chm‐1 vectors into microfractured porcine cartilage lesions stimulated chondrogenic differentiation of ingrowing progenitor cells, but significantly inhibited terminal chondrocyte hypertrophy, the invasion of vessel structures, and excessive endochondral ossification, which were otherwise observed in untreated lesions. Indirect gene transfer, with infection of porcine osteochondral progenitor cells by AAV‐Chm‐1 ex vivo, also supported chondrogenic differentiation of these transplanted cells. AAV‐Chm‐1–infected cells maintained a chondrocyte‐like phenotype and formed a hyaline‐like matrix that was superior to that formed by uninfected or AAV‐GFP–infected cells. Conclusion Our findings indicate that the antiangiogenic factor chondromodulin 1 stabilizes the chondrocyte phenotype by supporting chondrogenesis but inhibiting chondrocyte hypertrophy and endochondral ossification.

A polymorphism for the phase I drug-metabolizing enzyme, flavin-containing monooxygenase isoform 2 (FMO2), encoding either truncated inactive protein, FMO2X472 (FMO2.2A), or full-length active enzyme, FMO2Q472 (FMO2.1), is known and exhibits significant interethnic differences in allelic frequency. FMO2 is the major or sole FMO isoform expressed in the lung of most mammals, including nonhuman primates. To date, FMO2.1 has been found only in African-American and Hispanic populations, rendering individuals with this allele subject to drug metabolism that is potentially different from that of the general population. Approximately 26% of African-Americans (<i>n</i> = 180) possess the <i>FMO2^*1</i> allele. In preliminary studies, we initially estimated that 5% of Hispanics (<i>n</i> = 40) have the <i>FMO2^*1</i> allele, but access to large cohorts of individuals of defined national origin has allowed us to determine the occurrence among Mexican-American and Puerto Rican-American groups. We used allele-specific genotyping to detect <i>FMO2^*1</i> from 632 Hispanic individuals, including 280 individuals of Mexican origin and 327 individuals of Puerto Rican origin. Statistical analysis indicated that results from Mexican (five sample sources) and Puerto Rican (three sample sources) samples were consistent with the hypothesis of homogeneity within each group from different sources. Data were subsequently pooled across sources to test for evidence of a difference in occurrence of <i>FMO2^*1</i> between ethnic groups. There was strong evidence (<i>p</i> = 0.0066) that <i>FMO2^*1</i> is more common among Puerto Ricans (7%) than among individuals of Mexican descent (2%). The overall occurrence of <i>FMO2^*1</i> among Hispanics of all origins is estimated to be between 2 and 7%.

The transcription factor STAT-4 has recently been identified as a genetic susceptibility factor in systemic sclerosis (SSc) and other autoimmune diseases. The aim of this study was to investigate the contribution of STAT-4 in the development of a fibrotic phenotype in 2 different mouse models of experimental dermal fibrosis.STAT-4-deficient (stat4(-/-) ) mice and their wild-type littermates (stat4(+/+) ) were injected with bleomycin or NaCl. Infiltrating leukocytes, T cells, B cells, and monocytes were quantified in the lesional skin of stat4(-/-) and stat4(+/+) mice. Inflammatory and profibrotic cytokines were measured in sera and lesional skin samples from stat4(-/-) and stat4(+/+) mice. The outcome of mice lacking STAT-4 was also investigated in the tight skin 1 (TSK-1) mouse model.Stat4(-/-) mice were protected against bleomycin-induced dermal fibrosis, with a reduction in dermal thickening (mean ± SEM 65 ± 3% decrease; P = 0.03), hydroxyproline content (68 ± 5% decrease; P = 0.02), and myofibroblast counts (71 ± 6% decrease; P = 0.005). Moreover, the number of infiltrating leukocytes, especially T cells, was significantly decreased in the lesional skin of stat4(-/-) mice (mean ± SEM 63 ± 5% reduction in T cell count; P = 0.02). Stat4(-/-) mice also displayed decreased levels of inflammatory cytokines such as tumor necrosis factor α, interleukin-6 (IL-6), IL-2, and interferon-γ in lesional skin. Consistent with a primary role of STAT-4 in inflammation, STAT-4 deficiency did not ameliorate fibrosis in TSK-1 mice.The results of this study demonstrate that the transcription factor STAT-4 exerts potent profibrotic effects by controlling T cell activation and proliferation and cytokine release. These findings confirm the results of genetics studies on the role of STAT-4 in the development of SSc.