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ObjectivePathologically activated circulating immune cells, including monocytes, play major roles in systemic sclerosis (SSc). Their functional characterization can provide crucial information with direct clinical relevance. However, tools for the evaluation of pathologic immune cell activation and, in general, of clinical outcomes in SSc are scarce. Biophysical phenotyping (including characterization of cell mechanics and morphology) provides access to a novel, mostly unexplored layer of information regarding pathophysiologic immune cell activation. We hypothesized that the biophysical phenotyping of circulating immune cells, reflecting their pathologic activation, can be used as a clinical tool for the evaluation and risk stratification of patients with SSc.MethodsWe performed biophysical phenotyping of circulating immune cells by real-time fluorescence and deformability cytometry (RT-FDC) in 63 SSc patients, 59 rheumatoid arthritis (RA) patients, 28 antineutrophil cytoplasmic antibody–associated vasculitis (AAV) patients, and 22 age- and sex-matched healthy donors.ResultsWe identified a specific signature of biophysical properties of circulating immune cells in SSc patients that was mainly driven by monocytes. Since it is absent in RA and AAV, this signature reflects an SSc-specific monocyte activation rather than general inflammation. The biophysical properties of monocytes indicate current disease activity, the extent of skin or lung fibrosis, and the severity of manifestations of microvascular damage, as well as the risk of disease progression in SSc patients.ConclusionChanges in the biophysical properties of circulating immune cells reflect their pathologic activation in SSc patients and are associated with clinical outcomes. As a high-throughput approach that requires minimal preparations, RT-FDC–based biophysical phenotyping of monocytes can serve as a tool for the evaluation and risk stratification of patients with SSc.

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.

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 of10% 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% to80%. 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.

Mitochondrial transcription factor A (TFAM) controls the transcription of core proteins required for mitochondrial homeostasis. This study was undertaken to investigate changes in TFAM expression in systemic sclerosis (SSc), to analyze mitochondrial function, and to evaluate the consequences for fibroblast activation.TFAM expression was analyzed by immunofluorescence and Western blotting. The effects of TFAM knockout were investigated in cultured fibroblasts and in murine models of bleomycin-induced skin fibrosis, bleomycin-induced lung fibrosis, and skin fibrosis induced by overexpression of constitutively active transforming growth factor β type I receptor (TGFβRΙ).TFAM expression was down-regulated in fibroblasts in SSc skin and in cultured SSc fibroblasts. The down-regulation of TFAM was associated with decreased mitochondrial number and accumulation of damaged mitochondria with release of mitochondrial DNA (mtDNA), accumulation of deletions in mtDNA, metabolic alterations with impaired oxidative phosphorylation, and release of the mitokine GDF15. Normal fibroblasts subjected to long-term, but not acute, exposure to TGFβ mimicked SSc fibroblasts, with down-regulation of TFAM and accumulation of mitochondrial damage. Down-regulation of TFAM promoted fibroblast activation with up-regulation of fibrosis-relevant Gene Ontology terms in RNA-Seq, partially in a reactive oxygen species-dependent manner. Mice with fibroblast-specific knockout of Tfam were prone to fibrotic tissue remodeling, with fibrotic responses even to NaCl instillation and enhanced sensitivity to bleomycin injection and overexpression of constitutively active TGFβRI. TFAM knockout fostered Smad3 signaling to promote fibroblast activation.Alterations in the key mitochondrial transcription factor TFAM in response to prolonged activation of TGFβ and associated mitochondrial damage induce transcriptional programs that promote fibroblast-to-myofibroblast transition and drive tissue fibrosis.

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 of18. 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 of18 (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.

Pathologically activated circulating immune cells, including monocytes, play major roles in systemic sclerosis (SSc). Their functional characterization can provide crucial information with direct clinical relevance. However, tools for evaluation of pathologic immune cell activation and, in general, of clinical outcomes in SSc are scarce. Biophysical phenotyping (including characterization of cell mechanics and morphology) provides access to a novel, mostly unexplored layer of information regarding physio-pathological immune cell activation. We hypothesized that the biophysical phenotyping of circulating immune cells, reflecting their pathologic activation, can be used as a clinical tool in SSc.We performed biophysical phenotyping of circulating immune cells by real-time fluorescence and deformability cytometry (RT-FDC) in 63 SSc patients, 59 rheumatoid arthritis (RA) patients, 28 ANCA-associated vasculitis (AAV) patients and 22 age- and sex-matched healthy donors.We identified a specific signature of biophysical properties of circulating immune cells in SSc mainly driven by monocytes. Since it is absent in RA and AAV, this signature reflects an SSc-specific monocyte activation rather than general inflammation. The biophysical properties of monocytes indicate current disease activity, the extent of skin or lung fibrosis and the severity of manifestations of microvascular damage, as well as the risk of disease progression in SSc.Changes in biophysical properties of circulating immune cells reflect their pathologic activation in SSc and are associated with clinical outcomes. As a high throughput approach that requires minimal preparations, RT-FDC-based biophysical phenotyping of monocytes can serve as a tool for evaluation and risk stratification of patients with SSc.

Interstitial lung disease (ILD) is a key driver of mortality in patients with systemic sclerosis (SSc). A lack of approved treatments encompasses a high unmet medical need. Nintedanib has recently been approved for treatment in SSc-associated ILD (SSc-ILD) following SENSCIS®, a Phase III clinical trial showing that nintedanib slows the loss of pulmonary function in patients with SSc-ILD relative to placebo, as measured by annual rate of decline in forced vital capacity over 52 weeks. The aim of this study was to compare the activity of nintedanib and mycophenolate mofetil (MMF) in a transgenic Fra2 mouse model of SSc-ILD.Fra2 transgenic mice were treated with MMF or nintedanib. Haematoxylin and Eosin and Sirius Red staining were used to identify pulmonary fibrosis and vascular remodelling in whole lung sections. Fibrosis was quantified by Ashcroft scoring, fold change in fibrotic area, and hydroxyproline. Ki67, SM22a, CD31, and caspase-3 staining was used to quantify proliferating vascular smooth muscle cells and apoptotic endothelial cells.Nintedanib effectively ameliorated pulmonary vascular remodelling and fibrosis in Fra2 transgenic mice. Pulmonary fibrotic and vascular remodelling parameter scores and the apoptosis of dermal endothelial cells were significantly reduced compared with vehicle-treated Fra2 transgenic mice. Treatment with MMF had only mild antifibrotic effects and no effect on pulmonary vascular remodelling.In this model of SSc-ILD, nintedanib ameliorated pulmonary fibrosis, remodelling of pulmonary vasculature, and the apoptosis of endothelial cells. In contrast, MMF had minor effects on pulmonary fibrosis and no effects on vascular manifestations.

Objective Digital pitting scars (DPS) are frequent, but little studied in SSc to date. Methods An analysis of SSc patients enrolled in the EUSTAR database. Primary objectives were to (i) examine DPS prevalence; (ii) examine whether DPS are associated with digital ulcers (DUs) and active digital ischaemia (DUs or gangrene); and (iii) describe other associations with DPS including internal organ complications. Secondary objectives were whether DPS are associated with (i) functional impairment; (ii) structural microvascular disease; and (iii) mortality. Descriptive statistics and parametric/non-parametric tests were used. Binary logistic regression was used to examine the association between DPS and DUs, active digital ischaemia and mortality. Results A total of 9671 patients were included with reported DPS at any time point (n = 4924) or ‘never’ DPS (n = 4747). The majority (86.9%) were female and mean age was 55.7 years. DPS were associated with longer disease and Raynaud’s duration (both P ≤ 0.001). DPS were associated with interstitial lung disease, pulmonary hypertension, conduction blocks, telangiectases, calcinosis (all P ≤ 0.001) and joint synovitis (P = 0.021). Patients were more likely to have more severe capillaroscopic abnormality and greater hand functional impairment. Multivariable logistic regression analyses showed that DPS were associated (odds ratio) with DUs: 22.03 (19.51–24.87), active digital ischaemia: 6.30 (5.34–7.42) and death: 1.86 (1.48–2.36). Conclusion DPS are associated with a severe disease course including death. The impact of DPS on hand function and ischaemia is significant. The presence of DPS should alert the clinician to a poor prognosis and need to optimize the therapeutic strategy.

Early and effective discrimination (triage) of patients with inflammatory rheumatic diseases (IRD) and other diseases (non-IRD) is essential for successful treatment and preventing damage. The aim of this study was to investigate diagnostic delays and pre-diagnosis treatment in patients newly presenting to rheumatology outpatient clinics. A total of 600 patients newly presenting to one university hospital and two non-academic centers were included. Time from onset of symptoms to rheumatology consultation “total delay” as well as medical treatment before consultation were recorded. Median time from symptom onset to rheumatologist appointment (total delay) was 30 weeks. Median time to online search, first physician appointment request and first physician appointment was 2, 4 and 5 weeks, respectively. Total delay was significantly shorter for IRD patients compared to non-IRD patients, 26 vs 35 weeks (p = 0.007). Only 17.7% of all patients and 22.9% of IRD patients had a delay of less than 12 weeks. Total delay was significantly lower in patients seen in non-academic centers compared to the university center, 20 vs 50 weeks (p

Chronic graft-versus-host disease (cGVHD) is a major life-threatening complication of allogeneic hematopoietic stem cell transplantation. The molecular mechanisms underlying cGVHD remain poorly understood, and targeted therapies for clinical use are not well established. Here, we examined the role of the canonical WNT pathway in sclerodermatous cGVHD (sclGVHD). WNT signaling was activated in human sclGVHD with increased nuclear accumulation of the transcription factor β-catenin and a WNT-biased gene expression signature in lesional skin. Treatment with the highly selective tankryase inhibitor G007-LK, the CK1α agonist pyrvinium, or the LRP6 inhibitor salinomycin abrogated the activation of WNT signaling and protected against experimental cGVHD, without a significant impact on graft-versus-leukemia effect (GVL). Treatment with G007-LK, pyrvinium, or salinomycin almost completely prevented the development of clinical and histological features in the B10.D2 (H-2d) → BALB/c (H-2d) and LP/J (H-2b) → C57BL/6 (H-2b) models of sclGVHD. Inhibition of canonical WNT signaling reduced the release of extracellular matrix from fibroblasts and reduced leukocyte influx, suggesting that WNT signaling stimulates fibrotic tissue remodeling by direct effects on fibroblasts and by indirect inflammation-dependent effects in sclGVHD. Our findings may have direct translational potential, because pyrvinium is in clinical use, and tankyrase inhibitors are in clinical trials for other indications.

Summary Background 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. Methods 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. Findings 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 Interpretation 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. Funding German Research Foundation, Erlangen Anschubs-und Nachwuchsfinanzierung, Interdisziplinares Zentrum fur Klinische Forschung Erlangen, Bundesministerium fur Bildung und Forschung, Deutsche Stiftung Systemische Sklerose, Wilhelm-Sander-Foundation, Else-Kroner-Fresenius-Foundation, European Research Council, Ernst-Jung-Foundation, and Clinician Scientist Program Erlangen.

Summary Background Extracellular matrix remodelling is a hallmark of systemic sclerosis. We evaluated extracellular matrix neo-epitopes as potential serum biomarkers for progression of fibrosis in systemic sclerosis. Methods We included patients meeting the 2013 American College of Rheumatology and European League Against Rheumatism criteria and healthy controls from a derivation and validation cohort. The primary outcome was progression of fibrosis at follow-up, defined as decline in percentage of predicted forced vital capacity of 10% or more in patients with interstitial lung disease or increase in modified Rodnan skin score of 25% or more and more than 5 points at a 1-year follow-up visit. Longitudinal assessment and biobanking followed European Scleroderma Trials and Research standards. Extracellular matrix-degradation (BGM, C3M, C4M, and C6M) and extracellular matrix-formation neo-epitopes (PRO-C1, PRO-C3, PRO-C4, PRO-C5, and PRO-C6) were measured in serum using validated ELISAs. Findings Between Aug 18, 2011, and Jan 19, 2015, 149 patients with systemic sclerosis (27 [18%] progressors and 122 [82%] non-progressors) and 29 healthy controls were included in the derivation cohort. Concentrations of type III and IV collagen neo-epitopes were higher in patients with systemic sclerosis compared with healthy controls and were significantly associated with systemic sclerosis in univariable logistic regression. Concentrations of degradation neo-epitopes of type III and IV collagens and their turnover ratios distinguished between progressors and non-progressors (C3M area under the curve 0·77 [95% CI 0·67–0·86], p Interpretation These data suggest that neo-epitopes of type III and IV collagens are promising biomarkers for the assessment and prediction of extracellular matrix remodelling in systemic sclerosis. They could be used in clinical practice to risk stratify patients at risk of progression of fibrosis. Funding None.

ObjectivesPlasmacytoid dendritic cells (pDC) have been implicated in the pathogenesis of autoimmune diseases, such as scleroderma (SSc). However, this has been derived from indirect evidence using ex vivo human samples or mouse pDC in vivo. We have developed human-specific pDC models to directly identify their role in inflammation and fibrosis, as well as attenuation of pDC function with BDCA2-targeting to determine its therapeutic application.MethodsRNAseq of human pDC with TLR9 agonist ODN2216 and humanised monoclonal BDCA2 antibody, CBS004. Organotypic skin rafts consisting of fibroblasts and keratinocytes were stimulated with supernatant from TLR9-stimulated pDC and with CBS004. Human pDC were xenotransplanted into Nonobese diabetic/severe combined immunodeficiency (NOD SCID) mice treated with Aldara (inflammatory model), or bleomycin (fibrotic model) with CBS004 or human IgG control. Skin punch biopsies were used to assess gene and protein expression.ResultsRNAseq shows TLR9-induced activation of human pDC goes beyond type I interferon (IFN) secretion, which is functionally inactivated by BDCA2-targeting. Consistent with these findings, we show that BDCA2-targeting of pDC can completely suppress in vitro skin IFN-induced response. Most importantly, xenotransplantation of human pDC significantly increased in vivo skin IFN-induced response to TLR agonist and strongly enhanced fibrotic and immune response to bleomycin compared with controls. In these contexts, BDCA2-targeting suppressed human pDC-specific pathological responses.ConclusionsOur data indicate that human pDC play a key role in inflammation and immune-driven skin fibrosis, which can be effectively blocked by BDCA2-targeting, providing direct evidence supporting the development of attenuation of pDC function as a therapeutic application for SSc.

The activation of fibroblasts is required for physiological tissue remodelling such as wound healing. However, when the regulatory mechanisms are disrupted and fibroblasts remain persistently activated, the progressive deposition of extracellular matrix proteins leads to tissue fibrosis, which results in dysfunction or even loss of function of the affected organ. Although fibrosis has been recognized as a major cause of morbidity and mortality in modern societies, there are only few treatment options available that directly disrupt the release of extracellular matrix from fibroblasts. Intensive research in recent years, however, identified several pathways as core fibrotic mechanisms that are shared across different fibrotic diseases and organs. We discuss herein selection of those core pathways, especially downstream of the profibrotic TGF-β pathway, which are druggable and which may be transferable from bench to bedside.

TGF-beta 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-beta-driven tissue fibrosis. H19X was consistently upregulated in a wide variety of human fibrotic tissues and diseases and was strongly induced by TGF-beta, particularly in fibroblasts and fibroblast-related cells. Functional experiments following H19X silencing revealed that H19X was an obligatory factor for TGF-beta-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-beta-induced ECM remodeling and fibrosis.

Background and purpose Genetic deletion and pharmacological studies suggest a role for lysophosphatidic acid (LPA1 ) receptor in fibrosis. We investigated the therapeutic potential in systemic sclerosis (SSc) of a new orally active selective LPA1 receptor antagonist using dermal fibroblasts from patients and an animal model of skin fibrosis. Experimental approach Dermal fibroblast and skin biopsies from systemic sclerosis patients were used. Myofibroblast differentiation, gene expression and cytokine secretion were measured following LPA and/or SAR100842 treatment. Pharmacolgical effect of SAR100842 was assessed in the tight skin 1 (Tsk1) mouse model. Key results SAR100842 is equipotent against various LPA isoforms. Dermal fibroblasts and skin biopsies from patients with systemic sclerosis expressed high levels of LPA1 receptor. The LPA functional response (Ca2+ ) in systemic sclerosis dermal fibroblasts was fully antagonized with SAR100842. LPA induced myofibroblast differentiation in systemic sclerosis dermal and idiopathic pulmonary fibrosis lung fibroblasts and the secretion of inflammatory markers and activated Wnt markers. Results from systemic sclerosis dermal fibroblasts mirror those obtained in a mouse Tsk1 model of skin fibrosis. Using a therapeutic protocol, SAR100842 consistently reversed dermal thickening, inhibited myofibroblast differentiation and reduced skin collagen content. Inflammatory and Wnt pathway markers were also inhibited by SAR100842 in the skin of Tsk1 mice. Conclusion and implications The effects of SAR100842 on LPA-induced inflammation and on mechanisms linked to fibrosis like myofibroblast differentiation and Wnt pathway activation indicate that LPA1 receptor activation plays a key role in skin fibrosis. Our results support the therapeutic potential of LPA1 receptor antagonists in systemic sclerosis.

ObjectivesSystemic sclerosis is a heterogeneous, multisystem disease. It can occur at any age, but most patients develop the disease between the age of 40 to 50 years. There is controversial evidence on whether/how the age at disease onset affects their clinical phenotype. We here investigate the relationship between age at disease onset and symptoms in a large cohort of SSc patients (lcSSc, dcSSc and SSc-overlap syndromes).MethodsClinical data of the registry of the German Network for Systemic Scleroderma including 3281 patients were evaluated and subdivided into three age groups at disease onset (60 years).ResultsAmong all SSc patients, 24.5% developed their first non-Raynaud phenomenon symptoms at the age 60 years), except for gastrointestinal and musculoskeletal involvement. No significant difference was found for the use of corticosteroids. However, significantly, fewer patients older than 60 years received immunosuppressive treatment.ConclusionIn this large registry, ∼25% of patients developed SSc at an age above 60 years with an increased frequency of lcSSc. In this age group, an onset of internal organ involvement was significantly accelerated across all three subsets. These findings suggest that, in the elderly cohort, more frequent follow-up examinations are required for an earlier detection of organ complications.

Remodelling of the extracellular matrix by myofibroblasts is crucial for wound repair, but if deregulated, it might contribute to the development of fibrosis. Fibroblast-to-myofibroblast differentiation is promoted by aberrant microRNA-145-5p (miR-145) expression in response to transforming growth factor β1 (TGFβ1). One of several myofibroblast markers is human xylosyltransferase-I (XT-I), which is the initial and rate-limiting enzyme of proteoglycan biosynthesis. Increased serum XT activity was quantified in patients with systemic sclerosis (SSc), but the underlying cellular mechanism of this disease remains unknown. This study aims to determine the underlying molecular basis of XT-I induction by considering the miR-mediated regulation of XT-I. We found that miR-145 is upregulated in TGFβ1-treated dermal fibroblasts and correlates with an increased cellular XYLT1 expression and XT activity. Overexpression of miR-145 in dermal fibroblasts induced XYLT1 expression and XT activity and enhanced TGFβ1-promoted XT activity increase. Since direct XYLT1 3'-UTR targeting by miR-145 could be experimentally excluded, an indirect effect of miR-145 on XT-I regulation was indicated. We identified six transcription factor-binding sites for Krueppel-like factor 4 (KLF4), a zinc-finger transcription regulator and putative miR-145 target, in the XYLT1 promoter in silico. A suppressive role of KLF4 on XYLT1 expression was confirmed by targeted gene silencing in dermal fibroblasts and the quantification of KLF4 expression in SSc fibroblasts. Taken together, this study improves the mechanistic understanding of fibrotic remodelling in SSc by identifying a hitherto unknown miR-145/KLF4 pathway mediating the fibrogenic XT-I induction. This knowledge on XYLT1 may lead to the development of novel approaches in the therapy of fibrosis.

Summary 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.

Constant supply of oxygen is crucial for multicellular tissue homeostasis and energy metabolism in cardiac tissue. As a first response to acute hypoxia, endothelial cells (ECs) promote recruitment and adherence of immune cells to the dysbalanced EC barrier by releasing inflammatory mediators and growth factors, whereas chronic hypoxia leads to the activation of a transcription factor (TF) battery, that potently induces expression of growth factors and cytokines including platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF). We report a hypoxia-minded, targeted bioinformatics approach aiming to identify and validate TFs that regulate angiogenic signaling.A comprehensive RNA-Seq dataset derived from human ECs subjected to normoxic or hypoxic conditions was selected to identify significantly regulated genes based on (i) fold change (normoxia vs. hypoxia) and (ii) relative abundancy. Transcriptional regulation of this gene set was confirmedBy detailed

Background: The current subclassification of systemic sclerosis into cutaneous subtypes does not fully capture the heterogeneity of the disease. We aimed to compare the performances of stratification into LeRoy's cutaneous subtypes versus stratification by autoantibody status in systemic sclerosis. Methods: For this cohort study, we assessed people with systemic sclerosis in the multicentre international European Scleroderma Trials and Research (EUSTAR) database. Individuals positive for systemic-sclerosis autoantibodies of two specificities were excluded, and remaining individuals were classified by cutaneous subtype, according to their systemic sclerosis-specific autoantibodies, or both. We assessed the performance of each model to predict overall survival, progression-free survival, disease progression, and different organ involvement. The three models were compared by use of the area under the curve (AUC) of the receiver operating characteristic and the net reclassification improvement (NRI). Missing data were imputed. Findings: We assessed the database on July 26, 2019. Of 16 939 patients assessed for eligibility, 10 711 patients were included: 1647 (15·4%) of 10 709 were male, 9062 (84·6%) were female, mean age was 54·4 (SD 13·8) years, and mean disease duration was 7·9 (SD 8·2) years. Information regarding cutaneous subtype was available for 10 176 participants and antibody data were available for 9643 participants. In the prognostic analysis, there was no difference in AUC for overall survival (0·82, 95% CI 0·81–0·84 for cutaneous only vs 0·84, 0·82–0·85 for antibody only vs 0·84, 0·83–0·86 for combined) or for progression-free survival (0·70, 0·69–0·71 vs 0·71, 0·70–0·72 vs 0·71, 0·70–0·72). However, at 4 years the NRI showed substantial improvement for the antibody-only model compared with the cutaneous-only model in prediction of overall survival (0·57, 0·46–0·71 for antibody only vs 0·29, 0·19–0·39 for cutaneous only) and disease progression (0·36, 0·29–0·46 vs 0·21, 0·14–0·28). The antibody-only model did better than the cutaneous-only model in predicting renal crisis (AUC 0·72, 0·70–0·74 for antibody only vs 0·66, 0·64–0·69 for cutaneous only) and lung fibrosis leading to restrictive lung function (AUC 0·76, 0·75–0·77 vs 0·71, 0·70–0·72). The combined model improved the prediction of digital ulcers and elevated systolic pulmonary artery pressure, but did poorly for cardiac involvement. Interpretation: The autoantibody-only model outperforms cutaneous-only subsetting for risk stratifying people with systemic sclerosis in the EUSTAR cohort. Physicians should be aware of these findings at the time of decision making for patient management. Funding: World Scleroderma Foundation.

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 (SSc). 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 DPP4 using sitagliptin and vildagliptin. The effects of DPP4 inhibition were analyzed in human dermal fibroblasts and in different mouse models of SSc (each n = 6). RESULTS The expression of DPP-4 and the number of DPP-4-positive fibroblasts were increased in the fibrotic skin of SSc patients, in a transforming growth factor β (TGFβ)-dependent manner. DPP-4-positive fibroblasts expressed higher levels of myofibroblast markers and collagen (each P < 0.001 versus healthy controls). Overexpression of DPP4 promoted fibroblast activation, whereas pharmacologic inhibition or genetic inactivation of DPP4 reduced the proliferation, migration, and expression of contractile proteins and release of collagen (each P < 0.001 versus control mice) by interfering with TGFβ-induced ERK signaling. DPP4-knockout mice were less sensitive to bleomycin-induced dermal and pulmonary fibrosis (P < 0.0001 versus wild-type controls). Treatment with DPP4 inhibitors promoted regression of fibrosis in mice that had received bleomycin challenge and mice with chronic graft-versus-host disease, and ameliorated fibrosis in TSK1 mice (each P < 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 TGFβ-induced fibroblast activation in the fibrotic skin of SSc patients. Inhibition of DPP4 exerts potent antifibrotic effects when administered in well-tolerated doses. As DPP4 inhibitors are already in clinical use for diabetes, these results may have direct translational implications for the treatment of fibrosis in patients with SSc.

Rapid and accurate histopathological diagnosis during surgery is critical for clinical decision-making. The prevalent method of intraoperative consultation pathology is time, labour and cost intensive and requires the expertise of trained pathologists. Here, we present an alternative technique for the rapid, label-free analysis of biopsy samples by sequentially assessing the physical phenotype of singularized, suspended cells in high-throughput. This new diagnostic pipeline combines enzyme-free, mechanical dissociation of tissues with real-time deformability cytometry at measurement rates of 100 – 1,000 cells/sec, and machine learning-based analysis. We show that physical phenotype parameters extracted from brightfield images of single cells can be used to distinguish subpopulations of cells in various tissues, without prior knowledge or the need for molecular markers. Further, we demonstrate the potential of our method for inflammatory bowel disease diagnostics. Using unsupervised dimensionality reduction and logistic regression, we accurately differentiate between healthy and tumorous tissue in both mouse and human biopsy samples. The method delivers results within 30 minutes, laying the groundwork for a fast and marker-free diagnostic pipeline to detect pathological changes in solid biopsies.

SSc is a chronic autoimmune rheumatic disease that involves numerous organs and presents major management challenges. The histopathologic hallmarks of SSc include vasculopathy, fibrosis and autoimmune phenomena involving both innate and adaptive immune systems. Purinergic signalling is a pathway that may be implicated in the pathophysiology of several of these disease manifestations. Extracellular purines are potent signalling mediators, which have been shown to be dysregulated in SSc. As examples, purines can exacerbate vasculopathy and provoke platelet dysfunction; as well as contributing to immune dysregulation. Elements of purinergic signalling further promote organ and tissue fibrosis in several disease models. Here, we provide an overview of extracellular purine metabolism in purinergic signalling and link disorders of these to the molecular pathology of SSc. We also discuss targeting the purinergic signalling and explore the translational applications for new therapeutic options in SSc.

Objectives To evaluate the changes in disease-related biomarkers and safety of paquinimod, an oral immunomodulatory compound, in patients with systemic sclerosis (SSc). Methods In this open-label, single-arm, multicenter study, SSc patients with a rapidly progressive disease received paquinimod for 8 weeks. Blood and skin biopsies were collected at baseline, during treatment, and at follow-up for the analyses of type I interferon (IFN) activity, chemokine (C-C motif) ligand 2 (CCL2), and the number of myofibroblasts. The safety of paquinimod was evaluated throughout the study. Results Nine SSc patients were enrolled and completed the study treatment with paquinimod at 3 mg/day for 8 weeks. After the treatment, a reduction of type I IFN activity in the plasma from one patient with elevated baseline IFN activity was recorded. A trend towards reduced IFN activity in the skin after treatment was also observed in patients. The serum level of CCL2 was reduced in 7 of 9 patients after paquinimod treatment. There was a median reduction of 10% of the number of myofibroblasts in skin biopsies at week 8 compared to baseline. No change in modified Rodnan skin score and quality of life was detected in the study. Reported adverse events (AEs) were mild to moderate and expected with the most common being arthralgia (n = 3) and headache (n = 3), and C-reactive protein (CRP) increase. Conclusions Analysis of biomarkers before and after treatment suggest reduced type I IFN activity and reduced number of myofibroblasts in lesional skin. Paquinimod was overall well tolerated with mild to moderate and expected AEs. Trial registration ClinicalTrials.gov, NCT01487551. Registered on 7 September 2011

ObjectiveSystemic Sclerosis is an autoimmune connective tissue disease which results in fibrosis of the skin and lungs. The disease is characterized by activation of myofibroblasts but what governs this is unknown. Gremlin-1 is a BMP antagonist that is developmentally regulated and we sought to investigate its role in Systemic Sclerosis.MethodsDermal fibroblasts were transfected with Grem1pcDNA3.1 expression vectors or empty vectors. Various markers of myofibroblasts were measured at the mRNA and protein levels. Scratch wound assays were also performed. Media Transfer experiments were performed to evaluate cytokine like effects. Various inhibitors of TGF-β signaling and MAPK signaling were used post-transfection. siRNA to Gremlin-1 in SSc dermal fibroblasts were performed to evaluate the role of Gremlin-1. Different cytokines were incubated with fibroblasts and Gremlin-1 measured. Bleomycin was used as model of fibrosis and immunohistochemistry performed.ResultsOverexpression of Gremlin-1 was achieved in primary dermal fibroblasts and lead to activation of quiescent cells to myofibroblasts indicated by collagen and α-Smooth muscle actin. Overexpression also led to functional effects. This was associated with increased TGF-β1 levels and SBE luciferase activity but not increased Thrombospondin-1 expression. Inhibition of Gremlin-1 overexpression cells with antibodies to TGF-β1 but not isotype controls led to reduced collagen and various TGF-β pathway chemical inhibitors also led to reduced collagen levels. In SSc cells siRNA mediated reduction of Gremlin-1 reduced collagen expression and CTGF gene and protein levels in these cells. IL-13 did not lead to elevated Gremlin-1 expression nor did IL-11. Gremlin-1 was elevated in an animal model of fibrosis compared to NaCl-treated mice.ConclusionGremlin-1 is a key regulator of myofibroblast transition leading to enhanced ECM deposition. Strategies that block Gremlin-1 maybe a possible therapeutic target in fibrotic diseases such as SSc.

Our previous study demonstrated that heat shock protein 90 (Hsp90) is overexpressed in the involved skin of patients with systemic sclerosis (SSc) and in experimental dermal fibrosis. Pharmacological inhibition of Hsp90 prevented the stimulatory effects of transforming growth factor-beta on collagen synthesis and the development of dermal fibrosis in three preclinical models of SSc. In the next step of the preclinical analysis, herein, we aimed to evaluate the efficacy of an Hsp90 inhibitor, 17-dimethylaminoethylamino-17-demethoxygeldanamycin (17-DMAG), in the treatment of established experimental dermal fibrosis induced by bleomycin. Treatment with 17-DMAG demonstrated potent antifibrotic and anti-inflammatory properties: it decreased dermal thickening, collagen content, myofibroblast count, expression of transforming growth factor beta receptors, and pSmad3-positive cell counts, as well as leukocyte infiltration and systemic levels of crucial cytokines/chemokines involved in the pathogenesis of SSc, compared to vehicle-treated mice. 17-DMAG effectively prevented further progression and may induce regression of established bleomycin-induced dermal fibrosis to an extent comparable to nintedanib. These findings provide further evidence of the vital role of Hsp90 in the pathophysiology of SSc and characterize it as a potential target for the treatment of fibrosis with translational implications due to the availability of several Hsp90 inhibitors in clinical trials for other indications.

Fibrosis is defined as an excessive deposition of connective tissue components and can affect virtually every organ system, including the skin, lungs, liver and kidney. Fibrotic tissue remodelling often leads to organ malfunction and is commonly associated with high morbidity and mortality. The medical need for effective antifibrotic therapies is thus very high. However, the extraordinarily high costs of drug development and the rare incidence of many fibrotic disorders hinder the development of targeted therapies for individual fibrotic diseases. A potential strategy to overcome this challenge is to target common mechanisms and core pathways that are of central pathophysiological relevance across different fibrotic diseases. The factors influencing susceptibility to and initiation of these diseases are often distinct, with disease-specific and organ-specific risk factors, triggers and sites of first injury. Fibrotic remodelling programmes with shared fibrotic signalling responses such as transforming growth factor-β (TGFβ), platelet-derived growth factor (PDGF), WNT and hedgehog signalling drive disease progression in later stages of fibrotic diseases. The convergence towards shared responses has consequences for drug development as it might enable the development of general antifibrotic compounds that are effective across different disease entities and organs. Technological advances, including new models, single-cell technologies and gene editing, could provide new insights into the pathogenesis of fibrotic diseases and the development of drugs for their treatment. A number of core pathways and mechanisms of fibrosis, outlined in this Review, are shared across different tissues and might therefore present targets for general antifibrotic strategies. Organ-specific and disease-specific differences in fibrotic diseases could also provide insights for drug development efforts.

Interstitial lung disease (ILD) is a common manifestation of systemic autoimmune diseases and a leading cause of death in these patients. A proportion of patients with autoimmune ILDs develop a progressive fibrosing form of ILD, characterized by increasing fibrosis on high-resolution computed tomography, worsening of lung function, and early mortality. Autoimmune disease–related ILDs have a variable clinical course and not all patients will require treatment, but all patients should be monitored for signs of progression. Apart from systemic sclerosis–associated ILD, the limited evidence to support the efficacy of immunosuppression as a treatment for ILDs is based mainly on small retrospective series and expert opinion. Non-clinical data suggest that there are commonalities in the mechanisms that drive progressive fibrosis in ILDs with an immunological trigger as in other forms of progressive fibrosing ILD. This suggests that nintedanib and pirfenidone, drugs known to slow disease progression in patients with idiopathic pulmonary fibrosis, may also slow the progression of ILD associated with systemic autoimmune diseases. In the SENSCIS® trial, nintedanib reduced the rate of ILD progression in patients with systemic sclerosis–associated ILD. The results of other large clinical trials will provide further insights into the role of anti-fibrotic therapies in the treatment of autoimmune disease–related ILDs.

Tyrosine kinase inhibitors have emerged as a therapeutic option for rheumatic diseases such as systemic sclerosis (SSc). Because tyrosine kinases like c-Abl kinase are important for fibroblast activation and fibrosis development in SSc, the c-Abl inhibitor imatinib was proposed for SSc treatment. Transporters for organic cations have become increasingly recognized as an important determinant for uptake and efficacy of tyrosine kinase inhibitors. Therefore, we investigated the role of organic cation transporters in the uptake of imatinib. Moreover, the influence of important SSc pathogenetic factors, like PDGF and Notch pathway activation on these uptake processes, has been studied. We showed that organic cation transporters OCT1-3, novel organic cation transporters OCTN1/2, and the multidrug and toxin extrusion protein MATE1 are expressed in healthy dermal and SSc fibroblasts. Decreased expression levels of MATE1 and decreased imatinib uptake were measured in SSc fibroblasts. In small interfering RNA experiments, MATE1 was identified as key transporter for imatinib uptake and biological effect in dermal fibroblasts. Furthermore, PDGF reduced imatinib uptake by decreasing MATE1 expression in SSc fibroblasts, but not in healthy fibroblasts. Blocking the Notch pathway in SSc fibroblasts increased MATE1 transporter expression and imatinib uptake. In conclusion, MATE1-mediated transport governs therapeutic efficacy of imatinib in SSc.

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.

Systemic sclerosis (SSc) is a rare systemic autoimmune disease associated with a high mortality. The first histopathological hallmarks are vasculopathy and inflammation, followed by fibrosis of the skin and internal organs. The molecular and cellular mechanisms are incompletely understood. Rodent models provide important insights into the pathogenesis of SSc and are a mainstay for the development of novel targeted therapies. Here we describe the mechanistic insights of inducible and genetic models, and also discuss in detail the limitations and pitfalls of the most frequently used SSc mouse models. We also describe protocols for running the established bleomycin-induced scleroderma skin fibrosis model.

It is unclear why activated platelets and platelet-derived microparticles (MPs) accumulate in the blood of patients with systemic sclerosis (SSc). This study was undertaken to investigate whether defective phagocytosis might contribute to MP accumulation in the blood of patients with SSc.Blood samples were obtained from a total of 81 subjects, including 25 patients with SSc and 26 patients with stable coronary artery disease (CAD). Thirty sex- and age-matched healthy volunteers served as controls. Studies were also conducted in NSG mice, in which the tail vein of the mice was injected with MPs, and samples of the lung parenchyma were obtained for analysis of the pulmonary microvasculature. Tissue samples from human subjects and from mice were assessed by flow cytometry and immunochemical analyses for determination of platelet-neutrophil interactions, phagocytosis, levels and distribution of P-selectin, P-selectin glycoprotein ligand 1 (PSGL-1), and HMGB1 on platelets and MPs, and concentration of byproducts of neutrophil extracellular trap (NET) generation/catabolism.Activated P-selectin+ platelets and platelet-derived HMGB1+ MPs accumulated in the blood of SSc patients but not in the blood of healthy controls. Patients with CAD, a vasculopathy independent of systemic inflammation, had fewer P-selectin+ platelets and a negligible number of MPs. The expression of the receptor for P-selectin, PSGL-1, in neutrophils from SSc patients was significantly decreased, raising the possibility that phagocytes in SSc do not recognize activated platelets, leading to a failure of phagocytosis and continued neutrophil release of MPs. As evidence of this process, activated platelets were not detected in the neutrophils from SSc patients, whereas they were consistently present in the neutrophils from patients with CAD. HMGB1+ MPs elicited generation of NETs, which were only detected in the plasma of SSc patients. In mice, P-selectin-PSGL-1 interaction resulted in platelet phagocytosis in vitro and influenced the ability of MPs to elicit NETs, endothelial activation, and migration of leukocytes through the pulmonary microvasculature.The clearance of activated platelets via PSGL-1 limits the undesirable effects of MP-elicited neutrophil activation. This balance is disrupted in patients with SSc. Its reconstitution might curb vascular inflammation and prevent fibrosis.

Systemic sclerosis (SSc) is an idiopathic autoimmune connective tissue disease with vascular abnormalities, inflammation and fibrosis. The fibrosis affects the skin as well as several internal organs. An incomplete understanding of the pathways that govern activation of the cells involved in disease pathogenesis has hampered new therapies. In this issue of Annals of the Rheumatic Diseases, Malaab et al (REF to be inserted by ARD) employ a unique cohort of 15 twins disconcordant for the diagnosis of SSc to demonstrate a key role of epigenetics including methylation, alterations of microRNA and ultimately dysregulation of Kruppel-like factor 4 (KLF4) that impacts on fibrosis. This sheds light on underlying epigenetic mechanisms and exposes a new therapeutic target. Epigenetics is the study of heritable changes in gene expression not mediated by changes in the DNA sequence itself. Three main mechanisms mediate epigenetic changes: non-coding RNAs, DNA methylation and histone modifications.1 DNA and the cytosine base of DNA can be modified by the addition of a methyl group by a family of three DNA methyltransferases enzymes on the fifth carbon of cytosine. This modification enables binding of DNA methylation proteins such as methyl binding domain proteins, which in turn recruit histone modifying proteins and other epigenetic modulators that ultimately represses gene expression. Non-coding RNAs are defined as a long or short set arbitrarily defined by length. In the case of microRNAs, they regulate gene expression by binding the 3’UTR of mRNA that leads to gene repression. Long non-coding RNAs are usually much longer and regulate gene expression, both positively and negatively, through only partially unknown mechanisms. Finally, alteration in the histone tails of …

Systemic sclerosis (SSc) is an inflammatory fibrotic disease characterized by an excessive extracellular matrix deposition in the skin and internal organs. One fibrotic key event remains the fibroblast-to-myofibroblast differentiation that is controlled by a combination of mechanical and soluble factors, such as transforming growth factor-β1 (TGF-β1) and interleukin-1β (IL-1β). One important myofibroblast biomarker is human xylosyltransferase-I (XT-I), the initial enzyme in proteoglycan biosynthesis. Increased serum XT activity was quantified in SSc, but the underlying cellular mechanisms remain elusive. This study aims to determine the cellular basis of XT-I induction in SSc by using a myofibroblast cell culture model with SSc fibroblasts (SScF) and healthy control fibroblasts. We found that SScF exhibit a higher extracellular XT-I activity compared to control fibroblasts. This increased XT-I activity in SScF was demonstrated to be mediated by an enhanced autocrine TGF-β signaling. Upon IL-1β treatment, SScF showed an increased mRNA expression level of XT-I and TGF-β receptor II (TGFBR2), while healthy control fibroblasts did not, pointing towards an involvement of IL-1β in the cytokine-mediated XT-I induction. Performing microRNA (miRNA) inhibition experiments in the presence of TGF-β1, we showed that the pro-fibrotic effect of IL-1β may be mediated by a miRNA-21/TGF-β receptor II axis, enhancing the autocrine TGF-β signaling in SScF. Taken together, this study improves the mechanistic understanding of fibrotic XT-I induction in SSc by identifying a hitherto unknown IL-1β-mediated miRNA-21/TGFBR2 regulation contributing to the enhanced XYLT1 expression and XT-I activity in SScF.