TGF-ß1 Drives Integrin-Dependent Pericyte Migration and Microvascular Destabilization in Fibrotic Disease.

Interactions between endothelial cells (ECs) and mural pericytes (PCs) are critical to maintaining the stability and function of the microvascular wall. Abnormal interactions between these two cell types are a hallmark of progressive fibrotic diseases such as systemic sclerosis (also known as scleroderma). However, the role that PCs play in signaling microvascular dysfunction remains underexplored. It is hypothesized that integrin-matrix interactions contribute to PC migration from the vascular wall and conversion into interstitial myofibroblasts. Using pro-inflammatory tumor necrosis factor α (TNFα) or a fibrotic growth factor [transforming growth factor ß1 (TGF-ß1)], human PC inflammatory and fibrotic phenotypes were evaluated by assessing their migration, matrix deposition, integrin expression, and subsequent effects on endothelial dysfunction. Both TNFα and TGF-ß1 treatment altered integrin expression and matrix protein deposition, but only fibrotic TGF-ß1 drove PC migration in an integrin-dependent manner. In addition, integrin-dependent PC migration was correlated to changes in EC angiopoietin-2 levels, a marker of vascular instability. Finally, there was evidence of changes in vascular stability corresponding to disease state in human systemic sclerosis skin. This work shows that TNFα and TGF-ß1 induce changes in PC integrin expression and matrix deposition that facilitate migration and reduce vascular stability, providing evidence that microvascular destabilization can be an early indicator of tissue fibrosis.

Systems-based identification of the Hippo pathway for promoting fibrotic mesenchymal differentiation in systemic sclerosis.

Systemic sclerosis (SSc) is a devastating autoimmune disease characterized by excessive production and accumulation of extracellular matrix, leading to fibrosis of skin and other internal organs. However, the main cellular participants in SSc skin fibrosis remain incompletely understood. Here using differentiation trajectories at a single cell level, we demonstrate a dual source of extracellular matrix deposition in SSc skin from both myofibroblasts and endothelial-to-mesenchymal-transitioning cells (EndoMT). We further define a central role of Hippo pathway effectors in differentiation and homeostasis of myofibroblast and EndoMT, respectively, and show that myofibroblasts and EndoMTs function as central communication hubs that drive key pro-fibrotic signaling pathways in SSc. Together, our data help characterize myofibroblast differentiation and EndoMT phenotypes in SSc skin, and hint that modulation of the Hippo pathway may contribute in reversing the pro-fibrotic phenotypes in myofibroblasts and EndoMTs.

A qualitative interview study exploring the psychological health impacts of the SPIN-CHAT program among people with systemic sclerosis at the onset of COVID-19: perceptions of trial participants and research team members.

PURPOSE: Explore trial participants' and research team members' perceptions of the impact of the videoconference-based, supportive care program (SPIN-CHAT Program) during early COVID-19 for individuals with systemic sclerosis (SSc). METHODS: Data were collected cross-sectionally. A social constructivist paradigm was adopted, and one-on-one videoconference-based, semi-structured interviews were conducted with SPIN-CHAT Trial participants and research team members. A hybrid inductive-deductive approach and reflexive thematic analysis were used. RESULTS: Of the 40 SPIN-CHAT Trial participants and 28 research team members approached, 30 trial participants (Mean age = 54.9; SD = 13.0 years) and 22 research team members agreed to participate. Those who took part in interviews had similar characteristics to those who declined. Five themes were identified: (1) The SPIN-CHAT Program conferred a range of positive psychological health outcomes, (2) People who don't have SSc don't get it: The importance of SSc-specific programming, (3) The group-based format of the SPIN-CHAT Program created a safe space to connect and meet similar others, (4) The structure and schedule of the SPIN-CHAT Program reduced feelings of boredom and contributed to enhanced psychological health, (5) The necessity of knowledge, skills, and tools to self-manage SSc and navigate COVID-19. CONCLUSION: Participants' and research team members' perspectives elucidated SPIN-CHAT Program benefits and how these benefits may have been realized. Results underscore the importance of social support from similar others, structure, and self-management to enhance psychological health during COVID-19. TRIAL REGISTRATION: clinicaltrials.gov (NCT04335279)IMPLICATIONS FOR REHABILITATIONThe videoconference-based, supportive care SPIN-CHAT Program enhanced psychological health amongst individuals affected by systemic sclerosis.SPIN-CHAT Program participants and research team members shared that being around similar others, program structure, and self-management support were important and may have contributed to enhanced psychological health.Further efforts are required to explore experiences within supportive care programs to better understand if and how psychological health is impacted.

Heavy-chain antibody targeting of CD38 NAD+ hydrolase ectoenzyme to prevent fibrosis in multiple organs.

The functionally pleiotropic ectoenzyme CD38 is a glycohydrolase widely expressed on immune and non-hematopoietic cells. By converting NAD+ to ADP-ribose and nicotinamide, CD38 governs organismal NAD+ homeostasis and the activity of NAD+-dependent cellular enzymes. CD38 has emerged as a major driver of age-related NAD+ decline underlying adverse metabolic states, frailty and reduced health span. CD38 is upregulated in systemic sclerosis (SSc), a chronic disease characterized by fibrosis in multiple organs. We sought to test the hypothesis that inhibition of the CD38 ecto-enzymatic activity using a heavy-chain monoclonal antibody Ab68 will, via augmenting organismal NAD+, prevent fibrosis in a mouse model of SSc characterized by NAD+ depletion. Here we show that treatment of mice with a non-cytotoxic heavy-chain antibody that selectively inhibits CD38 ectoenzyme resulted in NAD+ boosting that was associated with significant protection from fibrosis in multiple organs. These findings suggest that targeted inhibition of CD38 ecto-enzymatic activity could be a potential pharmacological approach for SSc fibrosis treatment.

Efficacy of a Pseudomonas aeruginosa serogroup O9 vaccine.

There are currently no approved vaccines against the opportunistic pathogen Pseudomonas aeruginosa. Among vaccine targets, the lipopolysaccharide (LPS) O antigen of P. aeruginosa is the most immunodominant protective candidate. There are 20 different O antigens composed of different repeat sugar structures conferring serogroup specificity, and 10 are found most frequently in infection. Thus, one approach to combat infection by P. aeruginosa could be to generate immunity with a vaccine cocktail that includes all these serogroups. Serogroup O9 is 1 of the 10 serogroups commonly found in infection, but it has never been developed into a vaccine, due in part to the acid-labile nature of the O9 polysaccharide. Our laboratory has previously shown that intranasal administration of an attenuated Salmonella strain expressing the P. aeruginosa serogroup O11 LPS O antigen was effective in clearing bacteria and preventing mortality in mice following intranasal challenge with serogroup O11 P. aeruginosa. Consequently, we set out to develop a P. aeruginosa serogroup O9 vaccine using a similar approach. Here, we show that Salmonella expressing serogroup O9 triggered an antibody-mediated immune response following intranasal administration to mice and that it conferred protection from P. aeruginosa serogroup O9 in a murine model of acute pneumonia.

Emerging cellular and immunotherapies for systemic sclerosis: from mesenchymal stromal cells to CAR-T cells and vaccine-based approaches.

PURPOSE OF REVIEW: Although two targeted therapies have received recent approval for systemic sclerosis (SSc)-associated interstitial lung disease, they do not show major disease-modifying activity, highlighting the need for novel therapies and innovative paradigms. To that end, cellular therapies may represent a new opportunity for the treatment of SSc. The purpose of this review is to provide an up-to-date overview of emerging cell-based disease-modifying therapies in SSc. RECENT FINDINGS: Initial small studies in patients with severe refractory systemic lupus erythematosus (SLE) using engineered regulatory cells show promising results. CD19-directed CAR-T have shown promising results in one case report of refractory diffuse cutaneous SSc patients. T cells engineered to express a chimeric autoantibody receptor (CAAR-T cells) may be even more relevant via the specific elimination of auto-reactive B cells. Targeting pro-fibrotic or senescence-related pathways may also constitute promising approaches in SSc. SUMMARY: Building on the classification of the clinical phenotype and prediction of clinical trajectory based on individual patients' autoantigen and/or autoantibody profile, cellular therapies targeting the same autoantigen or related autoreactive cells may represent an unprecedented opportunity to implement personalized medicine in SSc.

Efficacy of a Pseudomonas aeruginosa Serogroup O9 Vaccine.

There are currently no approved vaccines against the opportunistic pathogen Pseudomonas aeruginosa. Among vaccine targets, the lipopolysaccharide (LPS) O antigen of P. aeruginosa is the most immunodominant protective candidate. There are twenty different O antigens composed of different repeat sugars structures conferring serogroup specificity, and ten are found most frequently in infection. Thus, one approach to combat infection by P. aeruginosa could be to generate immunity with a vaccine cocktail that includes all these serogroups. Serogroup O9 is one of the ten serogroups commonly found in infection, but it has never been developed into a vaccine, likely due, in part, to the acid labile nature of the O9 polysaccharide. Our laboratory has previously shown that intranasal administration of an attenuated Salmonella strain expressing the P. aeruginosa serogroup O11 LPS O antigen was effective in clearing and preventing mortality in mice following intranasal challenge with serogroup O11 P. aeruginosa. Consequently, we set out to develop a P. aeruginosa serogroup O9 vaccine using a similar approach. Here we show that Salmonella expressing serogroup O9 triggered an antibody-mediated immune response following intranasal administration to mice and that it conferred protection from P. aeruginosa serogroup O9 in a murine model of acute pneumonia.

Extracellular Matrix-Derived Damage-Associated Molecular Patterns (DAMP): Implications in Systemic Sclerosis and Fibrosis.

Damage-associated molecular patterns (DAMPs) are intracellular molecules released under cellular stress or recurring tissue injury, which serve as endogenous ligands for toll-like receptors (TLRs). Such DAMPs are either actively secreted by immune cells or passively released into the extracellular environment from damaged cells or generated as alternatively spliced mRNA variants of extracellular matrix (ECM) glycoproteins. When recognized by pattern recognition receptors (PRRs) such as TLRs, DAMPs trigger innate immune responses. Currently, the best-characterized PRRs include, in addition to TLRs, nucleotide-binding oligomerization domain-like receptors, RIG-I-like RNA helicases, C-type lectin receptors, and many more. Systemic sclerosis (SSc) is a chronic autoimmune condition characterized by inflammation and progressive fibrosis in multiple organs. Using an unbiased survey for SSc-associated DAMPs, we have identified the ECM glycoproteins fibronectin-containing extra domain A and tenascin C as the most highly upregulated in SSc skin and lung biopsies. These DAMPs activate TLR4 on resident stromal cells to elicit profibrotic responses and sustained myofibroblasts activation resulting in progressive fibrosis. This review summarizes the current understanding of the complex functional roles of DAMPs in the progression and failure of resolution of fibrosis in general, with a particular focus on SSc, and considers viable therapeutic approaches targeting DAMPs.

Pansclerotic morphea is characterized by IFN-γ responses priming dendritic cell fibroblast crosstalk to promote fibrosis.

Pansclerotic morphea (PSM) is a rare, devastating disease characterized by extensive soft tissue fibrosis, secondary contractions, and significant morbidity. PSM pathogenesis is unknown, and aggressive immunosuppressive treatments rarely slow disease progression. We aimed to characterize molecular mechanisms driving PSM and to identify therapeutically targetable pathways by performing single-cell and spatial RNA-Seq on 7 healthy controls and on lesional and nonlesional skin biopsies of a patient with PSM 12 months apart. We then validated our findings using immunostaining and in vitro approaches. Fibrotic skin was characterized by prominent type II IFN response, accompanied by infiltrating myeloid cells, B cells, and T cells, which were the main IFN-γ source. We identified unique CXCL9+ fibroblasts enriched in PSM, characterized by increased chemokine expression, including CXCL9, CXCL10, and CCL2. CXCL9+ fibroblasts were related to profibrotic COL8A1+ myofibroblasts, which had enriched TGF-ß response. In vitro, TGF-ß and IFN-γ synergistically increased CXCL9 and CXCL10 expression, contributing to the perpetuation of IFN-γ responses. Furthermore, cell-to-cell interaction analyses revealed cDC2B DCs as a key communication hub between CXCL9+ fibroblasts and COL8A1+ myofibroblasts. These results define PSM as an inflammation-driven condition centered on type II IFN responses. This work identified key pathogenic circuits between T cells, cDC2Bs, and myofibroblasts, and it suggests that JAK1/2 inhibition is a potential therapeutic option in PSM.

Pharmacological inhibition of TAK1 prevents and induces regression of experimental organ fibrosis.

Multiorgan fibrosis in systemic sclerosis (SSc) accounts for substantial mortality and lacks effective therapies. Lying at the crossroad of TGF-ß and TLR signaling, TGF-ß-activated kinase 1 (TAK1) might have a pathogenic role in SSc. We therefore sought to evaluate the TAK1 signaling axis in patients with SSc and to investigate pharmacological TAK1 blockade using a potentially novel drug-like selective TAK1 inhibitor, HS-276. Inhibiting TAK1 abrogated TGF-ß1 stimulation of collagen synthesis and myofibroblasts differentiation in healthy skin fibroblasts, and it ameliorated constitutive activation of SSc skin fibroblasts. Moreover, treatment with HS-276 prevented dermal and pulmonary fibrosis and reduced the expression of profibrotic mediators in bleomycin-treated mice. Importantly, initiating HS-276 treatment even after fibrosis was already established prevented its progression in affected organs. Together, these findings implicate TAK1 in the pathogenesis of SSc and identify targeted TAK1 inhibition using a small molecule as a potential strategy for the treatment of SSc and other fibrotic diseases.

Mental health symptoms in scleroderma during COVID-19: a Scleroderma Patient-centred Intervention Network (SPIN) cohort longitudinal study.

OBJECTIVES: People with systemic sclerosis (SSc) are vulnerable in COVID-19 and face challenges related to shifting COVID-19 risk and protective restrictions. We evaluated mental health symptom trajectories in people with SSc through March 2022. METHODS: The longitudinal Scleroderma Patient-centred Intervention Network (SPIN) COVID-19 cohort was launched in April 2020 and included participants from the ongoing SPIN Cohort and external enrolees. Analyses included estimated means with 95% CIs for anxiety and depression symptoms pre-COVID-19 for ongoing SPIN Cohort participants and anxiety, depression, loneliness, and fear of COVID-19 for all participants across 28 COVID-19 assessments up to March 2022. We conducted sensitivity analyse including estimating trajectories using only responses from participants who completed >90% of items for ≥21 of 28 possible assessments ("completers") and stratified analyses for all outcomes by sex, age, country, and SSc subtype. RESULTS: Anxiety symptoms increased in early 2020 but returned to pre-COVID-19 levels by mid-2020 and remained stable through March 2022. Depression symptoms did not initially change but were slightly lower by mid-2020 compared to pre-COVID-19 and were stable through March 2022. COVID-19 fear started high and decreased. Loneliness did not change across the pandemic. Results were similar for completers and for all subgroups. CONCLUSIONS: People with SSc continue to face COVID-19 challenges related to ongoing risk, the opening of societies, and removal of protective restrictions. People with SSc, in aggregate, appear to be weathering the pandemic well, but health care providers should be mindful that some individuals may benefit from mental health support.

Exploring research team members' and trial participants' perceptions of acceptability and implementation within one videoconference-based supportive care program for individuals affected by systemic sclerosis during COVID-19: a qualitative interview study.

The SPIN-CHAT Program was designed to support mental health among individuals with systemic sclerosis (SSc; commonly known as scleroderma) and at least mild anxiety symptoms at the onset of COVID-19. The program was formally evaluated in the SPIN-CHAT Trial. Little is known about program and trial acceptability, and factors impacting implementation from the perspectives of research team members and trial participants. Thus, the propose of this follow-up study was to explore research team members' and trial participants' experiences with the program and trial to identify factors impacting acceptability and successful implementation. Data were collected cross-sectionally through one-on-one, videoconference-based, semi-structured interviews with 22 research team members and 30 purposefully recruited trial participants (Mage = 54.9, SD = 13.0 years). A social constructivist paradigm was adopted, and data were analyzed thematically. Data were organized into seven themes: (i) getting started: the importance of prolonged engagement and exceeding expectations; (ii) designing the program and trial: including multiple features; (iii) training: research team members are critical to positive program and trial experiences; (iv) offering the program and trial: it needs to be flexible and patient-oriented; (v) maximizing engagement: navigating and managing group dynamics; (vi) delivering a videoconference-based supportive care intervention: necessary, appreciated, and associated with some barriers; and (vii) refining the program and trial: considering modification when offered beyond the period of COVID-19 restrictions. Trial participants were satisfied with and found the SPIN-CHAT Program and Trial to be acceptable. Results offer implementation data that can guide the design, development, and refinement of other supportive care programs seeking to promote psychological health during and beyond COVID-19.

The Scleroderma Patient-centered Intervention Network COVID-19 Home-isolation Activities Together (SPIN-CHAT) Program, a videoconference-based supportive care program, was designed to protect and enhance mental health in individuals affected by systemic sclerosis (commonly known as scleroderma) with at least mild anxiety symptoms during the COVID-19 pandemic. A trial was conducted to evaluate the SPIN-CHAT Program, and results were generally positive. However, important gaps in knowledge remained. Specifically, research team members' and participants' perceptions of SPIN-CHAT Trial acceptability (including satisfaction) and factors impacting implementation of the SPIN-CHAT Program had not yet been explored. To fill this gap, we conducted one-on-one, videoconference-based, semi-structured interviewed with 22 research team members and 30 purposefully recruited trial participants. Interviews sought to gain insights into research team members' and trial participants' experiences within the SPIN-CHAT Program, delivery preferences, and aspects that were/were not beneficial. Findings suggest research team members and participants valued the SPIN-CHAT Program and found the trial to be acceptable. Results also highlight important factors to consider when designing, developing, and/or refining videoconference-based supportive care programs.

Mindin (SPON2) Is Essential for Cutaneous Fibrogenesis in a Mouse Model of Systemic Sclerosis.

Systemic sclerosis is a fibrotic disease that initiates in the skin and progresses to internal organs, leading to a poor prognosis. Unraveling the etiology of a chronic, multifactorial disease such as systemic sclerosis has been aided by various animal models that recapitulate certain aspects of the human pathology. We found that the transcription factor SNAI1 is overexpressed in the epidermis of patients with systemic sclerosis, and a transgenic mouse recapitulating this expression pattern is sufficient to induce many clinical features of the human disease. Using this mouse model as a discovery platform, we have uncovered a critical role for the matricellular protein Mindin (SPON2) in fibrogenesis. Mindin is produced by SNAI1 transgenic skin keratinocytes and aids fibrogenesis by inducing early inflammatory cytokine production and collagen secretion in resident dermal fibroblasts. Given the dispensability of Mindin in normal tissue physiology, targeting this protein holds promise as an effective therapy for fibrosis.

Alterations of the Primary Cilia Gene SPAG17 and SOX9 Locus Noncoding RNAs Identified by RNA-Sequencing Analysis in Patients With Systemic Sclerosis.

OBJECTIVE: Systemic sclerosis (SSc) is characterized by immune activation, vasculopathy, and unresolving fibrosis in the skin, lungs, and other organs. We performed RNA-sequencing analysis on skin biopsy samples and peripheral blood mononuclear cells (PBMCs) from SSc patients and unaffected controls to better understand the pathogenesis of SSc. METHODS: We analyzed these data 1) to test for case/control differences and 2) to identify genes whose expression levels correlate with SSc severity as measured by local skin score, modified Rodnan skin thickness score (MRSS), forced vital capacity (FVC), or diffusing capacity for carbon monoxide (DLco). RESULTS: We found that PBMCs from SSc patients showed a strong type I interferon signature. This signal was found to be replicated in the skin, with additional signals for increased extracellular matrix (ECM) genes, classical complement pathway activation, and the presence of B cells. Notably, we observed a marked decrease in the expression of SPAG17, a cilia component, in SSc skin. We identified genes that correlated with the MRSS, DLco, and FVC in SSc PBMCs and skin using weighted gene coexpression network analysis. These genes were largely distinct from the case/control differentially expressed genes. In PBMCs, type I interferon signatures negatively correlated with the DLco. In SSc skin, ECM gene expression positively correlated with the MRSS. Network analysis of SSc skin genes that correlated with clinical features identified the noncoding RNAs SOX9-AS1 and ROCR, both near the SOX9 locus, as highly connected, "hub-like" genes in the network. CONCLUSION: These results identify noncoding RNAs and SPAG17 as novel factors potentially implicated in the pathogenesis of SSc.

Risk factors for lung function decline in systemic sclerosis-associated interstitial lung disease in a large single-centre cohort.

OBJECTIVES: The aim of this study was to identify risk factors of percent predicted forced vital capacity (ppFVC) decline in patients with SSc-associated interstitial lung disease (SSc-ILD). METHODS: We identified 484 patients with SSc who had HRCT Chest, of which 312 with ILD. Those with serial pulmonary function tests were included in a longitudinal analysis (n = 184). Linear mixed effect models were fitted to assess the decline in ppFVC over time, and to explore the effect of demographics and baseline characteristics on ppFVC decline. RESULTS: The majority of SSc-ILD patients were female (76.3%) and 51.3% had diffuse cutaneous subset. The mean (s.d.) age was 53.6 (12.7) years, median disease duration since first non-RP symptoms was 2.6 years, and 48.4% of the patients had ILD extent >20% on HRCT. In the univariate analysis, longer disease duration (>2.37 years), ILD extent >20%, and anti-topoisomerase I (ATA) positivity were significantly associated with ppFVC decline. In the multivariate analysis, the only statistically significant variable associated with ppFVC decline was ATA positivity. The overall group's mean decline in ppFVC was -0.28% (P-value 0.029), with -0.13% (n = 163) in those who were alive and -8.28% (P-value 0.0002 for the change in ppFVC trajectory) in patients who died within 2 years. CONCLUSION: Our study confirms that ppFVC is a marker of survival in SSc-ILD, supporting its use for risk stratification to identify patients who may benefit from earlier interventions and treatment. Our study also supports the role of ATA positivity as a predictive marker for ppFVC decline in this population.

Differences in symptom experience among patients with systemic sclerosis: a cluster analytic approach to identifying subgroups.

OBJECTIVES: Symptoms of people who have SSc are heterogeneous and difficult to address clinically. Because diverse symptoms often co-occur and may share common underlying mechanisms, identifying symptoms that cluster together may better target treatment approaches. We sought to identify and characterize patient subgroups based on symptom experience. METHODS: An exploratory hierarchical agglomerative cluster analysis was conducted to identify subgroups from a large SSc cohort from a single US academic medical centre. Patient-reported symptoms of pain interference, fatigue, sleep disturbance, dyspnoea, depression and anxiety were used for clustering. A multivariate analysis of variance (MANOVA) was used to examine the relative contribution of each variable across subgroups. Analyses of variance were performed to determine participant characteristics based on subgroup assignment. Presence of symptom clusters were tallied within subgroup. RESULTS: Participants (n = 587; 84% female, 41% diffuse cutaneous subtype, 59% early disease) divided into three subgroups via cluster analysis based on symptom severity: (i) no/minimal, (ii) mild, and (iii) moderate. Participants in mild and moderate symptoms subgroups had similar disease severity, but different symptom presentation. In the mild symptoms subgroup, pain, fatigue and sleep disturbance was the main symptom cluster. Participants in the moderate symptoms subgroup were characterized by co-occurring pain, fatigue, sleep disturbance, depression and anxiety. CONCLUSION: Identification of distinct symptom clusters, particularly among SSc patients who experience mild and moderate symptoms, suggests potential differences in treatment approach and in mechanisms underlying symptom experience that require further study.

Circulating CTRP9 Is Associated With Severity of Systemic Sclerosis-Associated Interstitial Lung Disease.

OBJECTIVE: While interstitial lung disease (ILD) is the leading cause of morbidity and mortality in systemic sclerosis (SSc), there remains a paucity of predictive markers to assess disease progression. We previously demonstrated that adipose tissue metabolism and adipokine homeostasis is dysregulated in SSc. The present study was undertaken to determine the association and predictive ability of the novel adipokine C1q/tumor necrosis factor-related protein 9 (CTRP9) for SSc-associated ILD. METHODS: We performed a retrospective longitudinal study utilizing the Northwestern Scleroderma Program Patient Registry and Biorepository. Serum levels of CTRP9 were measured in 110 SSc patients at baseline, and demographic, clinical, and pulmonary function test data were collected in 12-month intervals to 48 months. Longitudinal trajectory of forced vital capacity percent predicted (FVC%) was used as a primary outcome measure. We utilized a mixed model to compare trajectories of lung function by CTRP9 groups and performed latent trajectory analysis to accommodate for heterogeneity. RESULTS: In cross-sectional analysis, elevated circulating CTRP9 was associated with significantly lower FVC% at baseline (72% ± 17 versus 80% ± 18; P = 0.02) and 48 months (68 ± 19 versus 84 ± 18; P = 0.001). In mixed model analysis, high CTRP9 was associated with worse lung function but not with a different trajectory (P = 0.23). In contrast, low CTRP9 identified patients with stability of lung disease with reasonable accuracy (sensitivity 73%). Latent trajectory analysis confirmed the association of lower CTRP9 with higher FVC%. CONCLUSION: Higher circulating CTRP9 associated with worse pulmonary function, while low CTRP9 identified patients with lung disease stability over time. These findings suggest that CTRP9 may be a potential biomarker in SSc-associated ILD.

Reduced SPAG17 Expression in Systemic Sclerosis Triggers Myofibroblast Transition and Drives Fibrosis.

Systemic sclerosis (SSc) is a clinically heterogeneous fibrotic disease with no effective treatment. Myofibroblasts are responsible for unresolving synchronous skin and internal organ fibrosis in SSc, but the drivers of sustained myofibroblast activation remain poorly understood. Using unbiased transcriptome analysis of skin biopsies, we identified the downregulation of SPAG17 in multiple independent cohorts of patients with SSc, and by orthogonal approaches, we observed a significant negative correlation between SPAG17 and fibrotic gene expression. Fibroblasts and endothelial cells explanted from SSc skin biopsies showed reduced chromatin accessibility at the SPAG17 locus. Remarkably, mice lacking Spag17 showed spontaneous skin fibrosis with increased dermal thickness, collagen deposition and stiffness, and altered collagen fiber alignment. Knockdown of SPAG17 in human and mouse fibroblasts and microvascular endothelial cells was accompanied by spontaneous myofibroblast transformation and markedly heightened sensitivity to profibrotic stimuli. These responses were accompanied by constitutive TGF-ß pathway activation. Thus, we discovered impaired expression of SPAG17 in SSc and identified, to our knowledge, a previously unreported cell-intrinsic role for SPAG17 in the negative regulation of fibrotic responses. These findings shed fresh light on the pathogenesis of SSc and may inform the search for innovative therapies for SSc and other fibrotic conditions through SPAG17 signaling.