Comparative single-cell multiplex immunophenotyping of therapy-naive patients with rheumatoid arthritis, systemic sclerosis, and systemic lupus erythematosus shed light on disease-specific composition of the peripheral immune system.

Introduction: Systemic autoimmune diseases (SADs) are a significant burden on the healthcare system. Understanding the complexity of the peripheral immunophenotype in SADs may facilitate the differential diagnosis and identification of potential therapeutic targets. Methods: Single-cell mass cytometric immunophenotyping was performed on peripheral blood mononuclear cells (PBMCs) from healthy controls (HCs) and therapy-naive patients with rheumatoid arthritis (RA), progressive systemic sclerosis (SSc), and systemic lupus erythematosus (SLE). Immunophenotyping was performed on 15,387,165 CD45+ live single cells from 52 participants (13 cases/group), using an antibody panel to detect 34 markers. Results: Using the t-SNE (t-distributed stochastic neighbor embedding) algorithm, the following 17 main immune cell types were determined: CD4+/CD57- T cells, CD4+/CD57+ T cells, CD8+/CD161- T cells, CD8+/CD161+/CD28+ T cells, CD8dim T cells, CD3+/CD4-/CD8- T cells, TCRγ/δ T cells, CD4+ NKT cells, CD8+ NKT cells, classic NK cells, CD56dim/CD98dim cells, B cells, plasmablasts, monocytes, CD11cdim/CD172dim cells, myeloid dendritic cells (mDCs), and plasmacytoid dendritic cells (pDCs). Seven of the 17 main cell types exhibited statistically significant frequencies in the investigated groups. The expression levels of the 34 markers in the main populations were compared between HCs and SADs. In summary, 59 scatter plots showed significant differences in the expression intensities between at least two groups. Next, each immune cell population was divided into subpopulations (metaclusters) using the FlowSOM (self-organizing map) algorithm. Finally, 121 metaclusters (MCs) of the 10 main immune cell populations were found to have significant differences to classify diseases. The single-cell T-cell heterogeneity represented 64MCs based on the expression of 34 markers, and the frequency of 23 MCs differed significantly between at least twoconditions. The CD3- non-T-cell compartment contained 57 MCs with 17 MCs differentiating at least two investigated groups. In summary, we are the first to demonstrate the complexity of the immunophenotype of 34 markers over 15 million single cells in HCs vs. therapy-naive patients with RA, SSc, and SLE. Disease specific population frequencies or expression patterns of peripheral immune cells provide a single-cell data resource to the scientific community.

Levels of anti-topoisomerase I antibody correlated with short onset of cardiopulmonary involvement in Thai systemic sclerosis patients.

Anti-topoisomerase-I antibody (ATA) is associated with disease severity and internal organ involvement in patients with systemic sclerosis (SSc). The correlation between ATA levels and the clinical course of SSc is unclear. We aimed to determine the correlation between ATA level and survival time and the onset of internal organ fibrosis in SSc patients. This historical cohort study was conducted in adult SSc patients with quantitative tests of ATA between January 2019 and December 2022. Patients with overlap syndrome and no quantitative ATA test were excluded. According to the sample size calculation, and 10% compensated for missing data, a total of 153 patients were needed. The respective mean age on the study date and median ATA level was 59.9 ± 11.3 years and 370 U/mL (range 195-652). Most cases (107 cases; 69.9%) were the diffuse cutaneous SSc subset. According to a multivariable analysis, the ATA titer had a negative correlation with the onset of cardiac involvement (Rho - 0.47, p = 0.01), and had a positive correlation with skin thickness progression (Rho 0.39, p = 0.04). Eleven cases exhibited ATA levels < 7 U/mL and outlier ATA levels were excluded, 142 cases were included in the sensitivity analysis, and multivariable analysis showed the correlation between early onset of ILD and cardiac involvement (Rho - 0.43, p = 0.03 and Rho - 0.51, p = 0.01, respectively). The ATA level was correlated with neither the survival time nor the onset of renal crisis in both analyses. High ATA levels were correlated with a short onset of ILD and cardiac involvement and the presence of extensive skin tightness. Quantitative tests of ATA could serve as an effective tool for identifying patients at risk of an unfavorable prognosis.

Anti-CX3CL1 (fractalkine) monoclonal antibody attenuates lung and skin fibrosis in sclerodermatous graft-versus-host disease mouse model.

BACKGROUND: Systemic sclerosis (SSc) is an autoimmune disease characterized by vascular injury and inflammation, followed by excessive fibrosis of the skin and other internal organs, including the lungs. CX3CL1 (fractalkine), a chemokine expressed on endothelial cells, supports the migration of macrophages and T cells that express its specific receptor CX3CR1 into targeted tissues. We previously reported that anti-CX3CL1 monoclonal antibody (mAb) treatment significantly inhibited transforming growth factor (TGF)-ß1-induced expression of type I collagen and fibronectin 1 in human dermal fibroblasts. Additionally, anti-mouse CX3CL1 mAb efficiently suppressed skin inflammation and fibrosis in bleomycin- and growth factor-induced SSc mouse models. However, further studies using different mouse models of the complex immunopathology of SSc are required before the initiation of a clinical trial of CX3CL1 inhibitors for human SSc. METHODS: To assess the preclinical utility and functional mechanism of anti-CX3CL1 mAb therapy in skin and lung fibrosis, a sclerodermatous chronic graft-versus-host disease (Scl-cGVHD) mouse model was analyzed with immunohistochemical staining for characteristic infiltrating cells and RNA sequencing assays. RESULTS: On day 42 after bone marrow transplantation, Scl-cGVHD mice showed increased serum CX3CL1 level. Intraperitoneal administration of anti-CX3CL1 mAb inhibited the development of fibrosis in the skin and lungs of Scl-cGVHD model, and did not result in any apparent adverse events. The therapeutic effects were correlated with the number of tissue-infiltrating inflammatory cells and α-smooth muscle actin (α-SMA)-positive myofibroblasts. RNA sequencing analysis of the fibrotic skin demonstrated that cGVHD-dependent induction of gene sets associated with macrophage-related inflammation and fibrosis was significantly downregulated by mAb treatment. In the process of fibrosis, mAb treatment reduced cGVHD-induced infiltration of macrophages and T cells in the skin and lungs, especially those expressing CX3CR1. CONCLUSIONS: Together with our previous findings in other SSc mouse models, the current results indicated that anti-CX3CL1 mAb therapy could be a rational therapeutic approach for fibrotic disorders, such as human SSc and Scl-cGVHD.

Clinical features of patients with systemic sclerosis positive for anti-SS-A antibody: a cohort study of 156 patients.

BACKGROUND: Anti-SS-A/Ro antibody (anti-SSA), the diagnostic marker of Sjögren's syndrome (SS), is often detected in systemic sclerosis (SSc). Some patients are diagnosed with SSc/SS overlap syndromes, while there are anti-SSA-positive SSc cases without SS. In this study, we investigated the clinical characteristics of SSc with anti-SSA and clarified the clinical impact of this antibody in SSc. METHODS: A retrospective chart review was conducted of 156 patients with SSc at Yokohama City University Hospital from 2018 to 2021. Clinical data, laboratory data, imaging, and autoantibody positivity status were collected and analysed to assess the association between these variables and anti-SSA using multivariable logistic regression analysis. RESULTS: This cohort included 18 men and 138 women with SSc (median age, 69.0 years). Thirty-nine patients had diffuse cutaneous SSc (dcSSc) (25%), and 117 patients had limited cutaneous SSc (75%). Forty-four patients were anti-SSA-positive. Among them, 24 fulfilled the SS criteria. Multivariable logistic regression revealed that anti-SSA was statistically associated with interstitial lung disease (ILD; odds ratio [OR] = 2.67; 95% confidence interval [CI], 1.14-6.3; P = 0.024). Meanwhile, anti-SSA positivity tended to increase the development of digital ulcer (OR = 2.18; 95% CI, 0.99-4.82, P = 0.054). In the comparative analysis of the autoantibody single-positive and anti-SSA/SSc-specific autoantibody double-positive groups, the anti-SSA single-positive group showed a significantly increased risk of ILD (OR = 12.1; 95% CI, 2.13-140.57; P = 0.003). Furthermore, patients with SSc and anti-SSA indicated that anti-SSA-positive SSc without SS was strongly associated with dcSSc when compared to that in patients with SS (OR = 6.45; 95% CI, 1.23-32.60; P = 0.024). CONCLUSIONS: Anti-SSA positivity increases the risk of organ involvement, such as ILD, in patients with SSc. Additionally, the anti-SSA-positive SSc without SS population may have more severe skin fibrosis than others. Anti-SSA may be a potential marker of ILD and skin severity in SSc.

De novo Connective Tissue Disorders as Immune-related Adverse Events.

Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment through blocking immunoregulatory pathways, resulting in augmented antitumor responses. However, ICIs can cause inflammatory autoimmune toxicities, known as immune-related adverse events (irAEs). Common rheumatic irAEs include inflammatory arthritis, polymyalgia rheumatica-like symptoms, and myositis. Fewer cases of de novo connective tissue disease as irAEs have been described and have mainly presented with cutaneous manifestations of systemic lupus erythematosus (SLE) and systemic sclerosis (SSc). Treatments include glucocorticoids and steroid-sparing agents such as hydroxychloroquine, mycophenolate mofetil, and methotrexate with improvement of symptoms. In this review, the authors discuss immune-related SLE and SSc and their management.

Alterations in peripheral T- and B-cell subsets in patients with systemic sclerosis.

OBJECTIVES: To determine the alteration of peripheral T and B cell subsets in patients with systemic sclerosis (SSc) and to evaluate their correlation with the progression of SSc. METHODS: We recruited 47 SSc patients and 45 healthy controls (HCs) in this study. Demographic and clinical data were then collected. Flow cytometry was used to detect the proportions of 44 different T and B cell subsets in circulating blood. RESULTS: The proportion of total B cells (p = .043) decreased in SSc patients, together with similar frequencies of total T cells, CD4+ T cells, and CD8+ T cells in both groups. Several subsets of T and B cells differed significantly between these two groups. Follicular helper T cells-1 (Tfh1) (p < .001), helper T cells-1 (Th1) (p = .001), regulatory T cells (Treg) (p = .004), effector memory CD8+ T cells (p = .041), and cytotoxic T cells-17 (Tc17) (p = .01) were decreased in SSc patients. Follicular helper T cells-2 (Tfh2) (p = .001) and, helper T cells-2 (Th2) (p = .001) levels increased in the SSc group. Regulatory B cells (Breg) (p = .015) were lower in the SSc group, together with marginal zone (MZ) B cells (p < .001), memory B cells (p = .001), and non-switched B cells (p = .005). The modified Rodnan skin score (mRSS) correlated with helper T cells-17 (Th17) (r = -.410, p = .004), Tfh1 (r = -.321, p = .028), peripheral helper T cells (Tph) (r = -.364, p = .012) and plasma cells (r = -.312, p = .033). CONCLUSIONS: The alterations in T and B cells implied immune dysfunction, which may play an essential role in systemic sclerosis.

Induction of regulatory T cells and efficacy of low-dose interleukin-2 in systemic sclerosis: interventional open-label phase 1-phase 2a study.

BACKGROUND: Systemic sclerosis (SSc) is a chronic autoimmune disease, with impaired immune response, increased fibrosis and endothelial dysfunction. Regulatory T cells (Tregs), which are essential to control inflammation, tissue repair and autoimmunity, have a decreased frequency and impaired function in SSc patients. Low-dose interleukin-2 (IL-2LD) can expand and activate Tregs and has, therefore, a therapeutic potential in SSc. OBJECTIVE: We aimed to assess the safety and biological efficacy of IL-2LD in patients with SSc. METHODS: As part of the TRANSREG open-label phase IIa basket trial in multiple autoimmune diseases, we studied nine patients with SSc without severe organ involvement. Patients received 1 million international units (MIU)/day of IL-2 for 5 days, followed by fortnightly injections for 6 months. Laboratory and clinical evaluations were performed between baseline and month 6. RESULTS: At day 8, the primary endpoint (Treg frequency) was reached with a 1.8±0.5-fold increase of Treg levels among CD4+ T lymphocytes (p=0.0015). There were no significant changes in effector T cells nor in B cells. IL-2LD was well tolerated, and no serious adverse events related to treatment occurred. There was a globally stable measurement in the modified Rodnan skin score and Valentini score at month 6. Disease activity and severity measures, the quality of life evaluated by EuroQL-5D-5L and pulmonary function test parameters remained stable during the study period. CONCLUSION: IL-2LD at a dosage of 1 MIU/day safely and selectively activates and expands Tregs. Clinical signs remain stable during the study period. This opens the door to properly powered phase II efficacy trials investigating IL-2LD therapeutic efficacy in SSc.

Theoretical Studies of DNA Microarray Present Potential Molecular and Cellular Interconnectivity of Signaling Pathways in Immune System Dysregulation.

Autoimmunity is defined as the inability to regulate immunological activities in the body, especially in response to external triggers, leading to the attack of the tissues and organs of the host. Outcomes include the onset of autoimmune diseases whose effects are primarily due to dysregulated immune responses. In past years, there have been cases that show an increased susceptibility to other autoimmune disorders in patients who are already experiencing the same type of disease. Research in this field has started analyzing the potential molecular and cellular causes of this interconnectedness, bearing in mind the possibility of advancing drugs and therapies for the treatment of autoimmunity. With that, this study aimed to determine the correlation of four autoimmune diseases, which are type 1 diabetes (T1D), psoriasis (PSR), systemic sclerosis (SSc), and systemic lupus erythematosus (SLE), by identifying highly preserved co-expressed genes among datasets using WGCNA. Functional annotation was then employed to characterize these sets of genes based on their systemic relationship as a whole to elucidate the biological processes, cellular components, and molecular functions of the pathways they are involved in. Lastly, drug repurposing analysis was performed to screen candidate drugs for repositioning that could regulate the abnormal expression of genes among the diseases. A total of thirteen modules were obtained from the analysis, the majority of which were associated with transcriptional, post-transcriptional, and post-translational modification processes. Also, the evaluation based on KEGG suggested the possible role of TH17 differentiation in the simultaneous onset of the four diseases. Furthermore, clomiphene was the top drug candidate for regulating overexpressed hub genes; meanwhile, prilocaine was the top drug for regulating under-expressed hub genes. This study was geared towards utilizing transcriptomics approaches for the assessment of microarray data, which is different from the use of traditional genomic analyses. Such a research design for investigating correlations among autoimmune diseases may be the first of its kind.

Clinical features of patients with connective tissue disease with anti-human upstream binding factor antibodies: A single-center retrospective study.

Anti-human upstream-binding factor (anti-hUBF) antibodies have been reported predominantly in patients with connective tissue diseases (CTDs); these have also been reported in patients without CTDs such as hepatocellular carcinoma. Because of the low frequency of expression and few case reports, there is no consensus on the clinical significance of these antibodies. Thus, we aimed to examine the clinical features of patients with anti-hUBF antibodies and analyzed 1042 patients with clinically suspected CTDs. The presence of anti-hUBF antibodies was screened using immunoprecipitation assays. Of the 1042 patients, 19 (1.82%) tested positive for anti-hUBF antibodies; among them, 10 (56%) were diagnosed with undifferentiated CTD (UCTD), six with systemic sclerosis (SSc) and three with other diseases. Five of the 10 patients with UCTD were referred to our hospital with suspected SSc. None of the five patients fulfilled the 2013 American College of Rheumatology/European League Against Rheumatism classification criteria, but three scored seven points, a relatively high score. Six anti-hUBF-positive patients with SSc had a significantly lower modified Rodnan skin score (mRSS) than that of anti-hUBF-negative patients with SSc (2 [0-2] vs 7 [0-49], p < 0.01). Compared with anti-topoisomerase I-positive patients, anti-hUBF-positive patients had a significantly lower mRSS (2 [0-2] vs 13 [0-42], p < 0.01) and lower incidence of scleroderma renal crisis (0 of 6 vs 8 of 184, p < 0.01). Compared with anti-centromere-positive patients, anti-hUBF-positive patients had a higher incidence of interstitial lung disease (ILD), but the difference was not statistically significant (4 of 6 vs 19 of 239). In conclusion, anti-hUBF antibodies were predominantly detected in patients with CTDs and UCTD. In patients with CTDs, SSc exhibited a high ratio, displaying a lower mRSS and higher incidence of ILD. In patients with UCTD, careful follow-up is recommended as they may develop CTDs in the future.

Overlap syndrome of systemic sclerosis with antineutrophil cytoplasmic antibody-associated vasculitis according to 2022 ACR/EULAR criteria.

BACKGROUND/AIMS: This study applied the 2022 American College of Rheumatology (ACR)/European Alliance of Associations for Rheumatology (EULAR) criteria for antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) to patients with systemic sclerosis (SSc) and investigated the frequency of overlap syndrome of SSc and AAV (SSc-AAV-OS). METHODS: Among the 232 patients diagnosed with SSc, 105 with signs suggestive of small- or medium-vessel vasculitis, which were defined as the present of interstitial lung disease (ILD), peripheral neuropathy, or suspected renal vasculitis, were included in this study and analyzed. RESULTS: Among the 105 SSc patients, the detection rate of ANCA was 19.0%. When the 2022 ACR/EULAR criteria were applied, the frequency of SSc-AAV-OS was 20.0%, which was much higher than 1.7% reported with previous criteria for AAV. ANCA positivity contributed to the reclassification of SSc-AAV-OS more than ANCA negativity in SSc patients with signs suggestive of small- or medium-vessel vasculitis. CONCLUSION: The frequency of SSc-AAV-OS in SSc patients with signs suggestive of small- or medium-vessel vasculitis at diagnosis was 20.0%. Therefore, we suggest that physicians should perform ANCA tests in SSc patients exhibiting signs suggestive of small- or medium-vessel vasculitis and apply the new criteria for AAV.

Increased CD8+ tissue resident memory T cells, regulatory T cells and activated natural killer cells in systemic sclerosis lungs.

OBJECTIVE: Multiple observations indicate a role for lymphocytes in driving autoimmunity in SSc. While T and NK cells have been studied in SSc whole blood and bronchoalveolar lavage fluid, their role remains unclear, partly because no studies have analysed these cell types in SSc-interstitial lung disease (ILD) lung tissue. This research aimed to identify and analyse the lymphoid subpopulations in SSc-ILD lung explants. METHODS: Lymphoid populations from 13 SSc-ILD and 6 healthy control (HC) lung explants were analysed using Seurat following single-cell RNA sequencing. Lymphoid clusters were identified by their differential gene expression. Absolute cell numbers and cell proportions in each cluster were compared between cohorts. Additional analyses were performed using pathway analysis, pseudotime and cell ligand-receptor interactions. RESULTS: Activated CD16+ NK cells, CD8+ tissue resident memory T cells and Treg cells were proportionately higher in SSc-ILD compared with HC lungs. Activated CD16+ NK cells in SSc-ILD showed upregulated granzyme B, IFN-γ and CD226. Amphiregulin, highly upregulated by NK cells, was predicted to interact with epidermal growth factor receptor on several bronchial epithelial cell populations. Shifts in CD8+ T cell populations indicated a transition from resting to effector to tissue resident phenotypes in SSc-ILD. CONCLUSIONS: SSc-ILD lungs show activated lymphoid populations. Activated cytotoxic NK cells suggest they may kill alveolar epithelial cells, while their expression of amphiregulin suggests they may also induce bronchial epithelial cell hyperplasia. CD8+ T cells in SSc-ILD appear to transition from resting to the tissue resident memory phenotype.

Anti-Gephyrin Antibodies: A Novel Specificity in Patients With Systemic Sclerosis and Lower Bowel Dysfunction.

OBJECTIVE: Autoantibodies are clinically useful in phenotyping patients with systemic sclerosis (SSc). Gastrointestinal (GI) function is regulated by the enteric nervous system (ENS) and commonly impaired in SSc, suggesting that the SSc autoimmune response may target ENS antigens. We sought to identify novel anti-ENS autoantibodies with an aim to clinically phenotype SSc GI dysfunction. METHODS: Serum from a patient with SSc with GI dysfunction but without defined SSc-associated autoantibodies was used for autoantibody discovery. Immunoprecipitations performed with murine myenteric plexus lysates were on-bead digested, and autoantigens were identified by mass spectrometry. Prevalence was determined, and clinical features associated with novel autoantibodies were evaluated in a SSc cohort using regression analyses. The expression of gephyrin in human GI tract tissue was examined by immunohistochemistry. RESULTS: We identified gephyrin as a novel SSc autoantigen. Anti-gephyrin antibodies were present in 9% of patients with SSc (16/188) and absent in healthy controls (0/46). Anti-gephyrin antibody-positive patients had higher constipation scores (1.00 vs 0.50, P = 0.02) and were more likely to have severe constipation and severe distention/bloating (46% vs 15%, P = 0.005; 54% vs 25%, P = 0.023, respectively). Anti-gephyrin antibody levels were significantly higher among patients with severe constipation (0.04 vs 0.00; P = 0.001) and severe distention and bloating (0.03 vs 0.004; P = 0.010). Severe constipation was associated with anti-gephyrin antibodies even in the adjusted model. Importantly, gephyrin was expressed in the ENS, which regulates gut motility. CONCLUSION: Gephyrin is a novel ENS autoantigen that is expressed in human myenteric ganglia. Anti-gephyrin autoantibodies are associated with the presence and severity of constipation in patients with SSc.

Immunologic and nonimmunologic sclerodermal skin conditions - review.

Scleroderma-like cutaneous lesions have been found in many pathological conditions and they have the clinical appearance of sclerotic or scleroatrophic lesions. Affected skin biopsies described histopathological changes similar to those of scleroderma located strictly on the skin or those of systemic sclerosis. These skin lesions can be found in inflammatory diseases with autoimmune substrate (generalized morphea, chronic graft versus host disease, eosinophilic fasciitis), tissue storage diseases (scleredema, scleromyxedema, nephrogenyc systemic fibrosis, systemic amyloidosis), metabolic diseases (porphyrya cutanea tarda, phenylketonuria, hypothyroidism, scleredema diabeticorum), progeroid syndromes. Given the multiple etiologies of sclerodermal lesions, a correct differential diagnosis is necessary to establish the appropriate treatment.

Environmental Risks for Systemic Sclerosis.

There is an increasing body of literature suggesting a relationship between environmental factors and the development of systemic sclerosis (SSc). These include occupational exposures, chemical materials, medications, alterations in the microbiome, and dysbiosis. Environmental exposures may impact epigenetic regulation thereby triggering an aberrant immune response resulting in the clinical and serologic phenotype that we diagnose as SSc. Screening and studying putative triggers will not only improve our understanding of the pathogenesis of SSc but also inform the institution for protective measures.

Endothelin B Receptor Immunodynamics in Pulmonary Arterial Hypertension.

Introduction: Inflammation is a major pathological feature of pulmonary arterial hypertension (PAH), particularly in the context of inflammatory conditions such as systemic sclerosis (SSc). The endothelin system and anti-endothelin A receptor (ETA) autoantibodies have been implicated in the pathogenesis of PAH, and endothelin receptor antagonists are routinely used treatments for PAH. However, immunological functions of the endothelin B receptor (ETB) remain obscure. Methods: Serum levels of anti-ETB receptor autoantibodies were quantified in healthy donors and SSc patients with or without PAH. Age-dependent effects of overexpression of prepro-endothelin-1 or ETB deficiency on pulmonary inflammation and the cardiovascular system were studied in mice. Rescued ETB-deficient mice (ETB-/-) were used to prevent congenital Hirschsprung disease. The effects of pulmonary T-helper type 2 (Th2) inflammation on PAH-associated pathologies were analyzed in ETB-/- mice. Pulmonary vascular hemodynamics were investigated in isolated perfused mouse lungs. Hearts were assessed for right ventricular hypertrophy. Pulmonary inflammation and collagen deposition were assessed via lung microscopy and bronchoalveolar lavage fluid analyses. Results: Anti-ETB autoantibody levels were elevated in patients with PAH secondary to SSc. Both overexpression of prepro-endothelin-1 and rescued ETB deficiency led to pulmonary hypertension, pulmonary vascular hyperresponsiveness, and right ventricular hypertrophy with accompanying lymphocytic alveolitis. Marked perivascular lymphocytic infiltrates were exclusively found in ETB-/- mice. Following induction of pulmonary Th2 inflammation, PAH-associated pathologies and perivascular collagen deposition were aggravated in ETB-/- mice. Conclusion: This study provides evidence for an anti-inflammatory role of ETB. ETB seems to have protective effects on Th2-evoked pathologies of the cardiovascular system. Anti-ETB autoantibodies may modulate ETB-mediated immune homeostasis.

Pathophysiology of systemic sclerosis (scleroderma).

Systemic sclerosis (scleroderma) is an autoimmune-triggered chronic fibrosing disease that affects the skin and many other organs. Its pathophysiology is complex and involves an early endothelial damage, an inflammatory infiltrate and a resulting fibrotic reaction. Based on a predisposing genetic background, an altered balance of the acquired and the innate immune system leads to the release of many cytokines and chemokines as well as autoantibodies, which induce the activation of fibroblasts with the formation of myofibroblasts and the deposition of a stiff and rigid connective tissue. A curative treatment is still not available but remarkable progress has been made in the management of organ complications. In addition, several breakthroughs in the pathophysiology have led to new therapeutic concepts. Based on these, many new compounds have been developed during the last years, which target these different pathways and offer specific therapeutic approaches.

Defective Early B Cell Tolerance Checkpoints in Patients With Systemic Sclerosis Allow the Production of Self Antigen-Specific Clones.

OBJECTIVE: Early selection steps preventing autoreactive naive B cell production are often impaired in patients with autoimmune diseases, but central and peripheral B cell tolerance checkpoints have not been assessed in patients with systemic sclerosis (SSc). This study was undertaken to characterize early B cell tolerance checkpoints in patients with SSc. METHODS: Using an in vitro polymerase chain reaction-based approach that allows the expression of recombinant antibodies cloned from single B cells, we tested the reactivity of antibodies expressed by 212 CD19+CD21low CD10+IgMhigh CD27- new emigrant/transitional B cells and 190 CD19+CD21+CD10-IgM+CD27- mature naive B cells from 10 patients with SSc. RESULTS: Compared to serum from healthy donors, serum from patients with SSc displayed elevated proportions of polyreactive and antinuclear-reactive new emigrant/transitional B cells that recognize topoisomerase I, suggesting that defective central B cell tolerance contributes to the production of serum autoantibodies characteristic of the disease. Frequencies of autoreactive mature naive B cells were also significantly increased in SSc patients compared to healthy donors, thus indicating that a peripheral B cell tolerance checkpoint may be impaired in SSc. CONCLUSION: Defective counterselection of developing autoreactive naive B cells in SSc leads to the production of self antigen-specific B cells that may secrete autoantibodies and allow the formation of immune complexes, which promote fibrosis in SSc.

Autoantibody profiles delineate distinct subsets of scleromyositis.

OBJECTIVE: Scleromyositis remains incompletely characterized owing in part to its heterogeneity. The purpose of this study was to explore the role of autoantibody profiles to define subsets of scleromyositis. METHODS: Subjects with scleromyositis from a prospective cohort were divided into three groups based on autoantibody profiles: subjects with SSc-specific autoantibodies (anti-centromere, -topoisomerase 1, -RNA polymerase III, -Th/To, -fibrillarin), subjects with SSc-overlap autoantibodies (anti-PM/Scl, -U1RNP, -Ku) and subjects without SSc-related autoantibodies. Clinical features, laboratory tests and histopathological findings were retrieved and compared between groups. RESULTS: Of 42 scleromyositis subjects (79% female, mean age at diagnosis 55 years, mean disease duration 3.5 years), 8 (19%) subjects had SSc-specific autoantibodies, 14 (33%) SSc-overlap autoantibodies and 20 (48%) had no SSc-related autoantibodies. One-third had no skin involvement, a finding more frequent in the SSc-overlap subjects and those without SSc-related autoantibodies. Proximal and distal weakness was common and head drop/bent spine was found in 50% of the SSc-specific and 35% of the subjects without SSc-related autoantibodies. Of note, the group without SSc-related autoantibodies had the only cases of severe cardiac systolic dysfunction (n = 1) and scleroderma renal crisis (n = 1), as well as three out of the four cancers and three out of the four deaths. CONCLUSION: In this carefully phenotyped series of scleromyositis subjects, absence of SSc-related autoantibodies was common and associated with distinct features and poor prognosis. Future studies are needed to validate these results and possibly identify novel autoantibodies or other biomarkers associated with scleromyositis.