Systemic Sclerosis: From Pathophysiology to Novel Therapeutic Approaches

Soluble oncostatin M receptor (sOSMR): A potential biomarker in systemic sclerosis diagnosis

BACKGROUND

Systemic sclerosis (SSc) is a complex disease whose diagnosis is based on clinical manifestations, serological testing for autoantibodies, and nailfold capillaroscopy. Although some proteins have been proposed as biomarkers, the diagnosis of SSc remains a challenge for clinicians. The soluble oncostatin M receptor (sOSMR) is a potential biomarker for the diagnosis of SSc, as it appears to act as an antagonist of oncostatin M (OSM)-mediated signaling, which is involved in biological and inflammatory processes, including tissue injury and fibrosis. Therefore, this study aimed to evaluate the diagnostic performance of sOSMR in systemic sclerosis.

METHODOLOGY

Serum samples were collected from 105 patients with SSc, 50 with rheumatoid arthritis (RA), 64 with systemic lupus erythematosus (SLE), and 130 healthy controls (HC). The sOSMR levels were measured using an ELISA kit, and a receiver operating characteristic (ROC) curve was used to analyze the biomarker's potential for diagnosing SSc.

RESULTS

sOSMR levels are significantly elevated in the serum of patients with SSc when compared to patients with RA and SLE, as well as healthy controls (p < 0.0001 for all comparisons). The area under the curve (AUC) of ROC curve analysis revealed the ability of sOSMR serum levels to distinguish patients with SSc from those with RA (0.901 [95 % CI 0.842-0.943]; p < 0.0001), with a sensitivity of 89.52 % and specificity of 78.00 %, and from patients with SLE (0.897 [95 % CI 0.841-0.938]; p < 0.0001), with a sensitivity of 81.90 % and specificity of 89.06 %, as well as from healthy controls (0.876 [95 % CI 0.827 - 0.916]; p < 0.0001), with a sensitivity of 82.86 % and specificity of 81.54 %. When comparing patients with SSc to patients with other diseases (RA and SLE combined), an AUC of 0.898 ([95 % CI 0.851-0.935]; p < 0.0001) was found, with a sensitivity of 82.86 % and specificity of 85.09 %.

CONCLUSION

Serum sOSMR levels are elevated in patients with SSc and have shown a good ability to distinguish between SSc patients, patients with other autoimmune rheumatologic diseases (RA and SLE), and healthy controls. Thus, sOSMR is a promising marker for diagnosing SSc.

Endothelin-1 as a Candidate Biomarker of Systemic Sclerosis: A GRADE-Assessed Systematic Review and Meta-Analysis With Meta-Regression

Background

There is an ongoing search for novel biomarkers of vascular dysfunction, extent of fibrosis and organ involvement in systemic sclerosis (SSc).

Objectives

We critically appraised the studies investigating the circulating concentrations of endothelin-1 in SSc patients and healthy controls.

Design

This was a systematic review with meta-analysis.

Data sources and methods

We searched electronic databases (PubMed, Scopus, and Web of Science) from inception to 15 June 2024. We assessed the risk of bias and the certainty of evidence using the JBI Critical Appraisal Checklist and GRADE, respectively.

Results

Endothelin-1 concentrations were significantly higher in SSc patients than in controls (26 studies; standardised mean difference, SMD = 0.98, 95% CI 0.73-1.23, P < .001; moderate certainty of evidence). In SSc patients, there were no significant differences in endothelin-1 concentrations between those with limited and diffuse cutaneous SSc (10 studies; SMD = 0.32, 95% CI -0.07 to 0.71 P = .11; very low certainty), and with and without digital ulcers (5 studies; SMD = 0.82, 95% CI -0.06 to 1.69, P = .066; very low certainty), pulmonary arterial hypertension (7 studies; SMD = 0.22, 95% CI -0.01 to 0.45, P = .066; very low certainty) or interstitial lung disease (3 studies; SMD = 0.09, 95% CI -0.18 to 0.35, P = .51; very low certainty). There was limited evidence in SSc patients with different video capillaroscopy pattern and telangiectasias. Subgroup and meta-regression analyses showed significant associations between the effect size and geographical location (studies investigating SSc patients and controls), year of publication (studies investigating SSc patients with limited and diffuse cutaneous SSc), and biological matrix assessed (studies investigating SSc patients with and without digital ulcers).

Conclusion

The results of this systematic review and meta-analysis highlight the potential role of endothelin-1 as a candidate biomarker of SSc. Further research is warranted to determine the utility of measuring endothelin-1 in SSc subgroups with different extent of fibrosis and organ involvement.

Registration

PROSPERO registration number - CRD42024566461.

B-Lines in the Assessment of Interstitial Lung Disease Associated with Scleroderma: The Role of Handheld Devices

Background: Timely detection and aggressive management of interstitial lung disease (ILD) in systemic sclerosis (SSc) are essential to improving outcomes and reducing risks of irreversible lung injury. Objective: to explore the usefulness of an ultraportable ultrasound device for the management of SSc-related ILD and to compare it with clinical and instrumental data. Methods: A total of 19 consecutive SSc patients underwent a comprehensive pulmonary evaluation: clinical, pulmonary function tests (PFTs) (spirometry, DLCO), lung CT (1.5 mm slice thickness reconstruction; HRCT), and lung ultrasound (LUS). A total score was calculated based on the number of color-coded B-lines recorded for each lung sliding. B-lines were analyzed against dyspnea, cough, Velcro, CT imaging (Warrick's score), and PFTs. Global and subgroup analysis were performed (diffuse versus limited cutaneous SSc, Warrick's < 7 versus >7). Results: Symptomatic lung involvement with varying degrees of dyspnea was reported in about 74% of cases (functional NYHA > 2 in more than half), chronic dry cough in one-third, Velcro rales in 42%. A total of 84.24% were classified as SSc with ILD on CT imaging. Statistically significant mild-to-moderate correlations between B-lines and clinical manifestations were demonstrated, as well as PFTs and Warrick's scores (more B-lines, lower pulmonary function, but higher extent and severity on CT) (p < 0.05); there were differences between SSc patients without and with ILD in terms of the number and distribution of B-lines (p < 0.05), as well as different B-lines patterns and numbers in diffuse versus limited SSc (p < 0.05). Conclusions: Ultraportable handheld LUS is a promising method suitable for the management (screening, early detection, and evaluation) of SSc patients.

Vitamin D association with systemic sclerosis and its clinical features: A systematic review, meta-analysis, and meta-regression

Objectives

The aim of this review was to summarize existing data on the contribution of Vitamin D level and/or deficiency/insufficiency to systemic sclerosis susceptibility and its clinical features.

Methods

An electronic literature search for eligible studies among all papers published prior to 30 June 2024 was conducted through PubMed, EMBASE, Web of science, and Scopus databases. Meta-analyses estimating pooled raw mean differences, odds ratios, and Pearson r together with subgroup analyses and meta-regressions were performed for the association of Vitamin D with susceptibility to systemic sclerosis and disease presentation.

Results

Combined analysis revealed a significant decrease in Vitamin D level in systemic sclerosis patients comparatively to healthy controls, with raw mean differences 95% CI = -11.68 [-15.43 to -7.92] ng/mL, p < 1 E-10. Likewise, Vitamin D insufficiency (Vitamin D < 30 ng/mL) and deficiency (<10 ng/mL) were significantly associated with systemic sclerosis; odds ratios 95% CI = 3.58 [2.59-4.95], p < 1 E-10 and odds ratios 95% CI = 7.67 [3.97-14.83], p < 1 E-10, respectively. Moreover, decreased Vitamin D level was significantly associated with interstitial lung disease occurrence (raw mean differences 95% CI = -3.61 [-6.93 to -0.3], p = 0.003), while Vitamin D deficiency was associated with increased systolic pulmonary arterial pressure, raw mean differences (95% CI = 4.17 [1.44-6.89], p = 0.003). Besides, Vitamin D level was negatively correlated with the modified Rodnan skin score, r (95% CI = -0.26 [-0.44 to -0.08], p = 0.004). Conversely, Vitamin D level was significantly increased in systemic sclerosis patients with cutaneous calcinosis, raw mean differences (95% CI = 4.18 [1.07-7.28], p = 0.008).

Conclusion

This meta-analysis showed that decreased Vitamin D level was associated with susceptibility to systemic sclerosis, interstitial lung disease occurrence, increased systolic pulmonary arterial pressure, and higher modified Rodnan skin score. Conversely, calcinosis was found to be associated with increased Vitamin D level.

Registration

This review has been registered on PROSPERO: CRD42024565045, available from: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42024565045.

Parvovirus B19 in Rheumatic Diseases

Parvovirus B19 (B19V) is a human pathogen belonging to the Parvoviridae family. It is widely diffused in the population and responsible for a wide range of diseases, diverse in pathogenetic mechanisms, clinical course, and severity. B19V infects and replicates in erythroid progenitor cells (EPCs) in the bone marrow leading to their apoptosis. Moreover, it can also infect, in an abortive manner, a wide set of different cell types, normally non-permissive, and modify their normal physiology. Differences in the characteristics of virus-cell interaction may translate into different pathogenetic mechanisms and clinical outcomes. Joint involvement is a typical manifestation of B19V infection in adults. Moreover, several reports suggest, that B19V could be involved in the pathogenesis of some autoimmune rheumatologic diseases such as rheumatoid arthritis (RA), juvenile idiopathic arthritis (JIA), systemic sclerosis (SSc), systemic lupus erythematosus (SLE), or vasculitis. This review provides basic information on the B19 virus, highlights characteristics of viral infection in permissive and non-permissive systems, and focuses on recent findings concerning the pathogenic role of B19V in rheumatologic diseases.

Speckle-tracking global longitudinal strain predicts death and cardiovascular events in patients with systemic sclerosis

Aims

Albeit often asymptomatic, heart involvement in systemic sclerosis (SSc) represents a negative prognostic factor, accounting for nearly one-fourth of all deaths. Global longitudinal strain (GLS) is accurate in detecting heart involvement in patients with SSc and no overt cardiac disease and allows early detection and longitudinal monitoring, but its association with clinical endpoints has not been tested so far. The primary outcome was the association between left and right GLS and mortality for all causes. The secondary outcome was the association between left and right GLS and hospitalizations.

Methods and results

A prospective longitudinal study enrolling all consecutive patients with SSc without structural heart disease or previous cardiovascular event.A total of 164 patients were enrolled, of whom 19 (11.5%) died during follow-up and 48 (29.3%) were hospitalized. Both left (LV) and right ventricle (RV) GLS at enrolment were independently associated with an increased risk of death for all causes and hospitalizations. Patients with biventricular GLS impairment, respectively, had a 4.2-, 4.9-, and 13.9-fold increased risk of death when compared with patients with only LV, only RV, or no impairment (P < 0.001). The incidence of hospitalization in patients with biventricular GLS impairment was nearly four times higher when compared with patients with only LV or only RV impairment, and nine times higher when compared with normal biventricular GLS (P < 0.001).

Conclusion

Biventricular GLS is associated with an increased risk of death and hospitalization in patients with SSc during a median of 3-year follow-up, acting as a reliable and accurate prognostic tool in everyday practice.

PPARγ partial agonist LPSF/GQ-16 prevents dermal and pulmonary fibrosis in HOCl-induced systemic sclerosis (SSc) and modulates cytokine production in PBMC of SSc patients

Thiazolidinediones (TZD) are synthetic molecules that have a range of biological effects, including antifibrotic and anti-inflammatory, and they may represent a promising therapeutic strategy for systemic sclerosis (SSc). The aim of this study was to investigate the immunomodulatory and antifibrotic properties of LPSF/GQ-16, a TZD derivative, in peripheral blood mononuclear cells (PBMC) from SSc patients and in a murine model of SSc HOCl-induced. The PBMC of 20 SSc patients were stimulated with phytohemagglutinin (PHA) and treated with LPSF/GQ-16 for 48 h, later cytokines in the culture supernatants were quantified by sandwich enzyme-linked immunosorbent assay (ELISA) or cytometric bead array (CBA). Experimental SSc was induced by intradermal injections of hypochlorous acid (HOCl) for 6 weeks. HOCl-induced SSc mice received daily treatment with LPSF/GQ-16 (30 mg/kg) through intraperitoneal injections during the same period. Immunological parameters were evaluated by flow cytometry and ELISA, and dermal and pulmonary fibrosis were evaluated by RT-qPCR, hydroxyproline dosage and histopathological analysis. In PBMC cultures, it was possible to observe that LPSF/GQ-16 modulated the secretion of cytokines IL-2 (p < 0.001), IL-4 (p < 0.001), IL-6 (p < 0.001), IL-17A (p = 0.006), TNF (p < 0.001) and IFN-γ (p < 0.001). In addition, treatment with LPSF/GQ-16 in HOCl-induced SSc mice promoted a significant reduction in dermal thickening (p < 0.001), in the accumulation of collagen in the skin (p < 0.001), down-regulated the expression of fibrosis markers in the skin (Col1a1, α-Sma and Tgfβ1, p < 0.001 for all) and lungs (Il4 and Il13, p < 0.001 for both), as well as reduced activation of CD4 + T cells (p < 0.001), B cells (p < 0.001) and M2 macrophages (p < 0.001). In conclusion, LPSF/GQ-16 showed immunomodulatory and antifibrotic properties, demonstrating the therapeutic potential of this molecule for SSc.

Expression of epidermal growth factor receptor (EGFR) in systemic sclerosis patients (SSc) and gastro-oesophageal reflux disease (GORD)

INTRODUCTION

Systemic sclerosis (SSc) affects the connective tissue and leads to an abnormal fibrotic process in the skin and internal organs. Epidermal Growth Factor Receptor (EGFR) is able to induce cell proliferation and differentiation, and its expression is increased in SSc patients with pulmonary artery hypertension and in skin biopsies in patients with scleroderma. To date, no data on esophageal expression of EGFR are available in SSc patients. We aimed to evaluate whether the pro-fibrogenic pathways of SSc may affect EGFR expression in the esophagus.

METHODS

A retrospective analysis included patients with SSc and control subjects suffering from gastroesophageal reflux symptoms. Endoscopic assessment and histopathologic analyses were performed in all subjects and the presence of microscopic esophagitis was used to distinguish patients with normal esophageal mucosa and subjects with non-erosive reflux disease. EGFR expression was measured in all subjects.

RESULTS

A total of 35 patients with SSc were included, while the control group included 67 non-SSc patients. EGFR expression at the Z-line was higher in SSc patients than non-SSc patients in absence of microscopic esophagitis (median 65 %, IQR 56-71 % vs 42 %, IQR 37-54 %, p < 0.001). Microscopic esophagitis was found in 60 % of patients with SSc and 62.7 % of control patients, and EGFR expression was significantly higher in patients presenting microscopic esophagitis both in SSc and non-SSc patients.

CONCLUSION

The EGFR hyperexpression may be due to SSc and/or reflux-related damage in patients with microscopic esophagitis. Further studies are warranted to answer open questions and provide a possible role of EGFR in terms of diagnosis, prognosis, and therapy.

Non-classical circulating monocytes expressing high levels of microsomal prostaglandin E2 synthase-1 tag an aberrant IFN-response in systemic sclerosis

Systemic sclerosis (SSc) is a complex disease that affects the connective tissue, causing fibrosis. SSc patients show altered immune cell composition and activation in the peripheral blood (PB). PB monocytes (Mos) are recruited into tissues where they differentiate into macrophages, which are directly involved in fibrosis. To understand the role of CD14+ PB Mos in SSc, a single-cell transcriptome analysis (scRNA-seq) was conducted on 8 SSc patients and 8 controls. Using unsupervised clustering methods, CD14+ cells were assigned to 11 clusters, which added granularity to the known monocyte subsets: classical (cMos), intermediate (iMos) and non-classical Mos (ncMos) or type 2 dendritic cells. NcMos were significantly overrepresented in SSc patients and showed an active IFN-signature and increased expression levels of PTGES, in addition to monocyte motility and adhesion markers. We identified a SSc-related cluster of IRF7+ STAT1+ iMos with an aberrant IFN-response. Finally, a depletion of M2 polarised cMos in SSc was observed. Our results highlighted the potential of PB Mos as biomarkers for SSc and provided new possibilities for putative drug targets for modulating the innate immune response in SSc.

Enhanced Innate and Acquired Immune Responses in Systemic Sclerosis Primary Peripheral Blood Mononuclear Cells (PBMCs)

Chronic immune activation in systemic sclerosis is supported by the production of a plethora of cytokines with proven regulatory activities of the immune responses. This study aimed to explore PBMCs' cytokine profiles in SSc patients versus controls, as well as to investigate the balance between pro- and anti-inflammatory cytokines in association with disease duration. PBMCs were isolated from 18 SSc patients and 17 controls and further subjected to in vitro stimulation with lipopolysaccharide and heat-killed Candida albicans. Cytokine production was measured after 24 h and 7 days, respectively, using ELISA kits for interleukin (IL)-1β, IL-1 receptor antagonist (IL-1Ra), IL-6, tumor necrosis factor (TNF), IL-10, IL-17, and interferon-gamma (IFN-gamma). IL-1 β, IL-6, and TNF levels were increased in SSc patients compared with healthy volunteers irrespective of the stimulus used. IL-1Ra and Il-17 concentrations were not statistically different between groups, even though a trend toward higher levels in patients compared with their matched controls was also observed. Most cytokines demonstrated a stable course with disease progression, except for IL-10 levels, which declined over time. In conclusion, the results of this pilot study reveal that in patients with SSc a persistently enhanced immune response is established and maintained regardless of stimulus or disease duration.

Mediators of systemic sclerosis-associated interstitial lung disease (SSc-ILD): systematic review and meta-analyses

Systemic sclerosis-associated interstitial lung disease (SSc-ILD) is rare, poorly understood, with heterogeneous characteristics resulting in difficult diagnosis. We aimed to systematically review evidence of soluble markers in peripheral blood or bronchoalveolar lavage fluid (BALF) as biomarkers in SSc-ILD.

METHOD

Five databases were screened for observational or interventional, peer-reviewed studies in adults published between January 2000 and September 2021 that assessed levels of biomarkers in peripheral blood or BALF of SSc-ILD patients compared with healthy controls. Qualitative assessment was performed using Critical Appraisal Skills Programme (CASP) checklists. Standardised mean difference (SMD) in biomarkers were combined in random-effects meta-analyses where multiple independent studies reported quantitative data.

RESULTS

768 published studies were identified; 38 articles were included in the qualitative synthesis. Thirteen studies were included in the meta-analyses representing three biomarkers: KL6, SP-D and IL-8. Greater IL-8 levels were associated with SSc-ILD in both peripheral blood and BALF, overall SMD 0.88 (95% CI 0.61 to 1.15; I2=1%). Greater levels of SP-D and KL-6 were both estimated in SSc-ILD peripheral blood compared with healthy controls, at an SMD of 1.78 (95% CI 1.50 to 2.17; I2=8%) and 1.66 (95% CI 1.17 to 2.14; I2=76%), respectively.

CONCLUSION

We provide robust evidence that KL-6, SP-D and IL-8 have the potential to serve as reliable biomarkers in blood/BALF for supporting the diagnosis of SSc-ILD. However, while several other biomarkers have been proposed, the evidence of their independent value in diagnosis and prognosis is currently lacking and needs further investigation.

PROSPERO REGISTRATION NUMBER

CRD42021282452.

The Role of CCL24 in Systemic Sclerosis

Systemic sclerosis (SSc) is a chronic immune-mediated disease characterized by microangiopathy, immune dysregulation, and progressive fibrosis of the skin and internal organs. Though not fully understood, the pathogenesis of SSc is dominated by microvascular injury, endothelial dysregulation, and immune response that are thought to be associated with fibroblast activation and related fibrogenesis. Among the main clinical subsets, diffuse SSc (dSSc) is a progressive form with rapid and disseminated skin thickening accompanied by internal organ fibrosis and dysfunction. Despite recent advances and multiple randomized clinical trials in early dSSc patients, an effective disease-modifying treatment for progressive skin fibrosis is still missing, and there is a crucial need to identify new targets for therapeutic intervention. Eotaxin-2 (CCL24) is a chemokine secreted by immune cells and epithelial cells, which promotes trafficking of immune cells and activation of pro-fibrotic cells through CCR3 receptor binding. Higher levels of CCL24 and CCR3 were found in the skin and sera of patients with SSc compared with healthy controls; elevated levels of CCL24 and CCR3 were associated with fibrosis and predictive of greater lung function deterioration. Growing evidence supports the potency of a CCL24-blocking antibody as an anti-inflammatory and anti-fibrotic modulating agent in multiple preclinical models that involve liver, skin, and lung inflammation and fibrosis. This review highlights the role of CCL24 in orchestrating immune, vascular, and fibrotic pathways, and the potential of CCL24 inhibition as a novel treatment for SSc.

Disturbed Antioxidant Capacity in Patients with Systemic Sclerosis Associates with Lung and Gastrointestinal Symptoms

The correct balance between reactive oxygen species and antioxidant defense in an organism is disturbed in oxidative stress. To assess oxidative balance in 36 SSc patients and 26 healthy controls (HCs), we measured reactive oxidative metabolites (ROMs), total antioxidant capacity (TAC), lipid peroxidation (measuring 4-HNE), and DNA oxidative damage (measuring 8-OHdG) in serum. Furthermore, DNA breaks in leukocytes of 35 SSc patients and 32 HCs were evaluated using COMET. While we report high ROMs for both SSc patients and age/sex matched HC samples, there was a significant increase in TAC in SSc patients as compared to HCs, and thus also a significantly higher oxidative stress index in SSc patients. TAC was significantly higher in SSc patients with ILD and gastrointestinal involvement, as well as in patients with anti-topoisomerase antibodies. We observe no difference in serum lipid peroxidation status or oxidative DNA damage. However, SSc patients had significantly more leukocyte DNA breaks than HCs; the most damage was observed in patients treated with immunosuppressives. Thus, our study confirms presence of oxidative stress and increased DNA damage in leukocytes of SSc patients; however, it points toward increased antioxidant capacity, which needs to be further studied.

Mesenchymal Stem/Stromal Cell-Based Therapies in Systemic Rheumatic Disease: From Challenges to New Approaches for Overcoming Restrictions

Systemic rheumatic diseases, such as rheumatoid arthritis, systemic lupus erythematosus, and systemic sclerosis, are chronic autoimmune diseases affecting multiple organs and tissues. Despite recent advances in treatment, patients still experience significant morbidity and disability. Mesenchymal stem/stromal cell (MSC)-based therapy is promising for treating systemic rheumatic diseases due to the regenerative and immunomodulatory properties of MSCs. However, several challenges need to be overcome to use MSCs in clinical practice effectively. These challenges include MSC sourcing, characterization, standardization, safety, and efficacy issues. In this review, we provide an overview of the current state of MSC-based therapies in systemic rheumatic diseases, highlighting the challenges and limitations associated with their use. We also discuss emerging strategies and novel approaches that can help overcome the limitations. Finally, we provide insights into the future directions of MSC-based therapies for systemic rheumatic diseases and their potential clinical applications.

Screening and Analysis of Possible Drugs Binding to PDGFRα: A Molecular Modeling Study

The platelet-derived growth factor receptor (PDGFR) is a membrane tyrosine kinase receptor involved in several metabolic pathways, not only physiological but also pathological, as in tumor progression, immune-mediated diseases, and viral diseases. Considering this macromolecule as a druggable target for modulation/inhibition of these conditions, the aim of this work was to find new ligands or new information to design novel effective drugs. We performed an initial interaction screening with the human intracellular PDGFRα of about 7200 drugs and natural compounds contained in 5 independent databases/libraries implemented in the MTiOpenScreen web server. After the selection of 27 compounds, a structural analysis of the obtained complexes was performed. Three-dimensional quantitative structure-activity relationship (3D-QSAR) and absorption, distribution, metabolism, excretion, and toxicity (ADMET) analyses were also performed to understand the physicochemical properties of identified compounds to increase affinity and selectivity for PDGFRα. Among these 27 compounds, the drugs Bafetinib, Radotinib, Flumatinib, and Imatinib showed higher affinity for this tyrosine kinase receptor, lying in the nanomolar order, while the natural products included in this group, such as curcumin, luteolin, and epigallocatechin gallate (EGCG), showed sub-micromolar affinities. Although experimental studies are mandatory to fully understand the mechanisms behind PDGFRα inhibitors, the structural information obtained through this study could provide useful insight into the future development of more effective and targeted treatments for PDGFRα-related diseases, such as cancer and fibrosis.

A positive loop formed by SOX11 and periostin upregulates TGF-β signals leading to skin fibrosis

Systemic sclerosis (SSc) is a chronic, heterogenous disease of connective tissue characterized by organ fibrosis together with vascular injury and autoimmunity. Transforming growth factor (TGF)-β plays a central role in generating fibrosis, including SSc. Periostin is a matricellular protein playing a key role in the generation of fibrosis by amplifying the TGF-β signals. SOX (SRY-related HMG box) 11 is a transcription factor playing several important roles in organ development in embryos. We have previously shown that SOX11 induces periostin expression. However, the roles of the interactions among the TGF-β signals, periostin, and SOX11 remain unknown in the pathogenesis of SSc. In this study, we found that most clones of dermal fibroblasts derived from SSc patients showed constitutive, high expression of SOX11, which is significantly induced by TGF-β1. SOX11 forms a positive loop with periostin to activate the TGF-β signals in SSc dermal fibroblasts. Genetic deletion of Sox11 in Postn-expressing fibroblasts impairs dermal fibrosis by bleomycin. Moreover, using the DNA microarray method, we identified several fibrotic factors dependent on the TGF-β/SOX11/periostin pathway in SSc dermal fibroblasts. Our findings, taken together, show that a positive loop formed by SOX11 and periostin in fibroblasts upregulates the TGF-β signals, leading to skin fibrosis.

Increased expression of the ectoenzyme CD38 in peripheral blood plasmablasts and plasma cells of patients with systemic sclerosis

Objective

CD38 is a type II glycoprotein highly expressed on plasmablasts and on short- and long-lived plasma cells, but weakly expressed by lymphoid, myeloid, and non-hematopoietic cells. CD38 is a target for therapies aimed at depleting antibody-producing plasma cells. Systemic sclerosis (SSc) is an immune-mediated disease with a well-documented pathogenic role of B cells. We therefore analyzed CD38 expression in different subsets of peripheral blood mononuclear cells (PBMCs) from a cohort of SSc patients.

Methods

Cell surface expression of CD38 was evaluated on PBMCs from SSc patients using eight-color flow cytometry analysis performed with a FacsCanto II (BD). Healthy individuals were used as controls (HC).

Results

Forty-six SSc patients (mean age 56, range 23-79 years; 38 females and 8 males), and thirty-two age- and sex-matched HC were studied. Twenty-eight patients had the limited cutaneous form and eighteen the diffuse cutaneous form of SSc. The mean disease duration was 7 years. Fourteen patients were on immunosuppressive therapy (14 MMF, 5 RTX). The total percentages of T, B and NK cells were not different between SSc and HC. Compared to HC, SSc patients had higher levels of CD3+CD38+ T cells (p<0.05), higher percentage (p<0.001) of CD3+CD4+CD25+FOXP3+ regulatory T cells, lower percentage (p<0.05) of CD3+CD56+ NK T cells. Moreover, SSc patients had higher levels of CD24^highCD19+CD38^high regulatory B cells than HC (p<0.01), while the amount of CD24+CD19+CD38+CD27+ memory B cells was lower (p<0.001). Finally, the percentages of circulating CD38^highCD27+ plasmablasts and CD138+CD38^high plasma cells were both higher in the SSc group than in HC (p<0.001). We did not observe any correlations between these immunophenotypes and disease subsets or duration, and ongoing immunosuppressive treatment.

Conclusions

The increased expression of CD38 in peripheral blood plasmablasts and plasma cells of SSc patients may suggest this ectoenzyme as a candidate therapeutic target, under the hypothesis that depletion of these cells may beneficially downregulate the chronic immune response in SSc patients. Validation of this data in multicenter cohorts shall be obtained prior to clinical trials with existing anti-CD38 drugs.

SARA suppresses myofibroblast precursor transdifferentiation in fibrogenesis in a mouse model of scleroderma

We previously reported that Smad anchor for receptor activation (SARA) plays a critical role in maintaining epithelial cell phenotype. Here, we show that SARA suppressed myofibroblast precursor transdifferentiation in a mouse model of scleroderma. Mice overexpressing SARA specifically in PDGFR-β+ pericytes and pan-leukocytes (SARATg) developed significantly less skin fibrosis in response to bleomycin injection compared with wild-type littermates (SARAWT). Single-cell RNA-Seq analysis of skin PDGFR-β+ cells implicated pericyte subsets assuming myofibroblast characteristics under fibrotic stimuli, and SARA overexpression blocked the transition. In addition, a cluster that expresses molecules associated with Th2 cells and macrophage activation was enriched in SARAWT mice, but not in SARATg mice, after bleomycin treatment. Th2-specific Il-31 expression was increased in skin of the bleomycin-treated SARAWT mice and patients with scleroderma (or systemic sclerosis, SSc). Receptor-ligand analyses indicated that lymphocytes mediated pericyte transdifferentiation in SARAWT mice, while with SARA overexpression the myofibroblast activity of pericytes was suppressed. Together, these data suggest a potentially novel crosstalk between myofibroblast precursors and immune cells in the pathogenesis of SSc, in which SARA plays a critical role.

Cellular-Based Therapies in Systemic Sclerosis: From Hematopoietic Stem Cell Transplant to Innovative Approaches

Systemic sclerosis (SSc) is a systemic disease characterized by autoimmune responses, vasculopathy and tissue fibrosis. The pathogenic mechanisms involve a wide range of cells and soluble factors. The complexity of interactions leads to heterogeneous clinical features in terms of the extent, severity, and rate of progression of skin fibrosis and internal organ involvement. Available disease-modifying drugs have only modest effects on halting disease progression and may be associated with significant side effects. Therefore, cellular therapies have been developed aiming at the restoration of immunologic self-tolerance in order to provide durable remissions or to foster tissue regeneration. Currently, SSc is recommended as the 'standard indication' for autologous hematopoietic stem cell transplantation by the European Society for Blood and Marrow Transplantation. This review provides an overview on cellular therapies in SSc, from pre-clinical models to clinical applications, opening towards more advanced cellular therapies, such as mesenchymal stem cells, regulatory T cells and potentially CAR-T-cell therapies.

PDGF/PDGFR: A Possible Molecular Target in Scleroderma Fibrosis

Systemic sclerosis (SSc) is a clinically heterogeneous disorder of the connective tissue characterized by vascular alterations, immune/inflammatory manifestations, and organ fibrosis. SSc pathogenesis is complex and still poorly understood. Therefore, effective therapies are lacking and remain nonspecific and limited to disease symptoms. In the last few years, many molecular and cellular mediators of SSc fibrosis have been described, providing new potential options for targeted therapies. In this review: (i) we focused on the PDGF/PDGFR pathway as key signaling molecules in the development of tissue fibrosis; (ii) we highlighted the possible role of stimulatory anti-PDGFRα autoantibodies in the pathogenesis of SSc; (iii) we reported the most promising PDGF/PDGFR targeting therapies.

Tissue Resident Foxp3+ Regulatory T Cells: Sentinels and Saboteurs in Health and Disease

Foxp3⁺ regulatory T (Treg) cells are a CD4 T cell subset with unique immune regulatory function that are indispensable in immunity and tolerance. Their indisputable importance has been investigated in numerous disease settings and experimental models. Despite the extensive efforts in determining the cellular and molecular mechanisms operating their functions, our understanding their biology especially in vivo remains limited. There is emerging evidence that Treg cells resident in the non-lymphoid tissues play a central role in regulating tissue homeostasis, inflammation, and repair. Furthermore, tissue-specific properties of those Treg cells that allow them to express tissue specific functions have been explored. In this review, we will discuss the potential mechanisms and key cellular/molecular factors responsible for the homeostasis and functions of tissue resident Treg cells under steady-state and inflammatory conditions.