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.

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.

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.

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.

Antibiotics Drive Expansion of Rare Pathogens in a Chronic Infection Microbiome Model.

Chronic (long-lasting) infections are globally a major and rising cause of morbidity and mortality. Unlike typical acute infections, chronic infections are ecologically diverse, characterized by the presence of a polymicrobial mix of opportunistic pathogens and human-associated commensals. To address the challenge of chronic infection microbiomes, we focus on a particularly well-characterized disease, cystic fibrosis (CF), where polymicrobial lung infections persist for decades despite frequent exposure to antibiotics. Epidemiological analyses point to conflicting results on the benefits of antibiotic treatment yet are confounded by the dependency of antibiotic exposures on prior pathogen presence, limiting their ability to draw causal inferences on the relationships between antibiotic exposure and pathogen dynamics. To address this limitation, we develop a synthetic infection microbiome model representing CF metacommunity diversity and benchmark on clinical data. We show that in the absence of antibiotics, replicate microbiome structures in a synthetic sputum medium are highly repeatable and dominated by oral commensals. In contrast, challenge with physiologically relevant antibiotic doses leads to substantial community perturbation characterized by multiple alternate pathogen-dominant states and enrichment of drug-resistant species. These results provide evidence that antibiotics can drive the expansion (via competitive release) of previously rare opportunistic pathogens and offer a path toward microbiome-informed conditional treatment strategies. IMPORTANCE We develop and clinically benchmark an experimental model of the cystic fibrosis (CF) lung infection microbiome to investigate the impacts of antibiotic exposures on chronic, polymicrobial infections. We show that a single experimental model defined by metacommunity data can partially recapitulate the diversity of individual microbiome states observed across a population of people with CF. In the absence of antibiotics, we see highly repeatable community structures, dominated by oral microbes. Under clinically relevant antibiotic exposures, we see diverse and frequently pathogen-dominated communities, and a nonevolutionary enrichment of antimicrobial resistance on the community scale, mediated by competitive release. The results highlight the potential importance of nonevolutionary (community-ecological) processes in driving the growing global crisis of increasing antibiotic resistance.

Biological and clinical insights from a randomized phase 2 study of an anti-oncostatin M monoclonal antibody in systemic sclerosis.

OBJECTIVES: The cytokine oncostatin M (OSM) is implicated in the pathology of SSc. Inhibiting OSM signalling using GSK2330811 (an anti-OSM monoclonal antibody) in patients with SSc has the potential to slow or stop the disease process. METHODS: This multicentre, randomized, double-blind, placebo-controlled study enrolled participants ≥18 years of age with active dcSSc. Participants were randomized 3:1 (GSK2330811:placebo) in one of two sequential cohorts to receive GSK2330811 (cohort 1: 100 mg; cohort 2: 300 mg) or placebo s.c. every other week for 12 weeks. The primary endpoint was safety; blood and skin biopsy samples were collected to explore mechanistic effects on inflammation and fibrosis. Clinical efficacy was an exploratory endpoint. RESULTS: Thirty-five participants were randomized to placebo (n = 8), GSK2330811 100 mg (n = 3) or GSK2330811 300 mg (n = 24). Proof of mechanism, measured by coordinate effects on biomarkers of inflammation or fibrosis, was not demonstrated following GSK2330811 treatment. There were no meaningful differences between GSK2330811 and placebo for any efficacy endpoints. The safety and tolerability of GSK2330811 were not favourable in the 300 mg group, with on-target, dose-dependent adverse events related to decreases in haemoglobin and platelet count that were not observed in the 100 mg or placebo groups. CONCLUSION: Despite a robust and novel experimental medicine approach and evidence of target engagement, anticipated SSc-related biologic effects of GSK2330811 were not different from placebo and safety was unfavourable, suggesting OSM inhibition may not be a useful therapeutic strategy in SSc. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov, NCT03041025; EudraCT, 2016-003417-95.

Inorganic pyrophosphate is reduced in patients with systemic sclerosis.

OBJECTIVE: The pathogenesis of calcinosis cutis, a disabling complication of SSc, is poorly understood and effective treatments are lacking. Inorganic pyrophosphate (PPi) is a key regulator of ectopic mineralization, and its deficiency has been implicated in ectopic mineralization disorders. We therefore sought to test the hypothesis that SSc may be associated with reduced circulating PPi, which might play a pathogenic role in calcinosis cutis. METHODS: Subjects with SSc and age-matched controls without SSc were recruited from the outpatient rheumatology clinics at Rutgers and Northwestern Universities (US cohort), and from the Universities of Szeged and Debrecen (Hungarian cohort). Calcinosis cutis was confirmed by direct palpation, by imaging or both. Plasma PPi levels were determined in platelet-free plasma using ATP sulfurylase to convert PPi into ATP in the presence of excess adenosine 5' phosphosulfate. RESULTS: Eighty-one patients with SSc (40 diffuse cutaneous, and 41 limited cutaneous SSc) in the US cohort and 45 patients with SSc (19 diffuse cutaneous and 26 limited cutaneous SSc) in the Hungarian cohort were enrolled. Calcinosis was frequently detected (40% of US and 46% of the Hungarian cohort). Plasma PPi levels were significantly reduced in both SSc cohorts with and without calcinosis (US: P = 0.003; Hungarian: P < 0.001). CONCLUSIONS: Circulating PPi are significantly reduced in SSc patients with or without calcinosis. Reduced PPi may be important in the pathophysiology of calcinosis and contribute to tissue damage with chronic SSc. Administering PPi may be a therapeutic strategy and larger clinical studies are planned to confirm our findings.

Contribution of monocytes and macrophages to the pathogenesis of systemic sclerosis: recent insights and therapeutic implications.

PURPOSE OF REVIEW: To discuss recent studies addressing the role of monocytes and macrophages in the pathogenesis of systemic sclerosis (SSc) based on human and mouse models. RECENT FINDINGS: Studies indicate that monocyte adhesion could be increased in SSc secondary to an interferon-dependent loss of CD52, and chemotaxis up-regulated through the CCR3/CCL24 pathway. Beyond the conventional M1/M2 paradigm of macrophage subpopulations, new subpopulations of macrophages have been recently described in skin and lung biopsies from SSc patients. Notably, single-cell ribonucleic acid sequencing has provided evidence for SPP1+ lung macrophages or FCGR3A+ skin macrophages in SSc. Impaired pro-resolving capacities of macrophages such as efferocytosis, i.e. the ability to phagocyte apoptotic cells, could also participate in the inflammatory and autoimmune features in SSc. SUMMARY: Through their potential pro-fibrotic and pro-inflammatory properties, macrophages are at the cross-road of key SSc pathogenic processes and associated manifestations. Investigative drugs targeting macrophage polarization, such as pan-janus kinase inhibitors (tofacitinib or ruxolitinib) impacting both M1 and M2 activations, or Romilkimab inhibiting IL-4 and IL-13, have shown promising results in preclinical models or phase I/II clinical trials in SSc and other fibro-inflammatory disorders. Macrophage-based cellular therapy may also represent an innovative approach for the treatment of SSc, as initial training of macrophages may modulate the severity of fibrotic and autoimmune manifestations of the disease.

Adiponectin Deregulation in Systemic Autoimmune Rheumatic Diseases.

Deregulation of adiponectin is found in systemic autoimmune rheumatic diseases (SARDs). Its expression is downregulated by various inflammatory mediators, but paradoxically, elevated serum levels are present in SARDs with high inflammatory components, such as rheumatoid arthritis and systemic lupus erythematosus. Circulating adiponectin is positively associated with radiographic progression in rheumatoid arthritis as well as with cardiovascular risks and lupus nephritis in systemic lupus erythematosus. However, in SARDs with less prominent inflammation, such as systemic sclerosis, adiponectin levels are low and correlate negatively with disease activity. Regulators of adiponectin gene expression (PPAR-γ, Id3, ATF3, and SIRT1) and inflammatory cytokines (interleukin 6 and tumor necrosis factor α) are differentially expressed in SARDs and could therefore influence total adiponectin levels. In addition, anti-inflammatory therapy could also have an impact, as tocilizumab treatment is associated with increased serum adiponectin. However, anti-tumor necrosis factor α treatment does not seem to affect its levels. Our review provides an overview of studies on adiponectin levels in the bloodstream and other biological samples from SARD patients and presents some possible explanations why adiponectin is deregulated in the context of therapy and gene regulation.

Hematopoietic stem cell transplantation in systemic sclerosis: Yes!! BUT. . .

Systemic sclerosis is a chronic multisystem, autoimmune disease with high mortality, and to date, has no effective approved therapy. For patients with the most severe forms of systemic sclerosis, autologous hematopoietic stem cell therapy has been proven to be effective, as demonstrated by three randomized controlled clinical trials and at least two registry studies. In the controlled studies, autologous hematopoietic stem cell therapy was shown to improve mortality, skin involvement, quality-of-life, and function compared with patients treated with intravenous cyclophosphamide. There is significant transplant-related mortality associated with autologous hematopoietic stem cell therapy, as well as infectious and noninfectious serious adverse events, including cardiac and renal compromise. Although the results of autologous hematopoietic stem cell therapy clinical trials to date are highly encouraging, a number of important unanswered questions remain. These include the following: What is the optimal transplant regimen; can the spectrum of systemic sclerosis patients who respond to autologous hematopoietic stem cell therapy be expanded; how can disease relapse following autologous hematopoietic stem cell therapy be predicted and managed; can treatment-related toxicity and mortality be mitigated; can response or toxicity be predicted; and finally, is there a place for allogeneic stem cell transplants in systemic sclerosis? Systemic sclerosis is an autoimmune disease with multiple immunological, vascular, and fibrotic abnormalities. Immunosuppressive therapy is frequently used, but to date its efficacy has been generally modest. Stem cell transplantation is the most potent immunosuppressive therapy currently available, and as discussed below, may have an important role in the management of systemic sclerosis.

Microbiome Data Enhances Predictive Models of Lung Function in People With Cystic Fibrosis.

BACKGROUND: Microbiome sequencing has brought increasing attention to the polymicrobial context of chronic infections. However, clinical microbiology continues to focus on canonical human pathogens, which may overlook informative, but nonpathogenic, biomarkers. We address this disconnect in lung infections in people with cystic fibrosis (CF). METHODS: We collected health information (lung function, age, and body mass index [BMI]) and sputum samples from a cohort of 77 children and adults with CF. Samples were collected during a period of clinical stability and 16S rDNA sequenced for airway microbiome compositions. We use ElasticNet regularization to train linear models predicting lung function and extract the most informative features. RESULTS: Models trained on whole-microbiome quantitation outperformed models trained on pathogen quantitation alone, with or without the inclusion of patient metadata. Our most accurate models retained key pathogens as negative predictors (Pseudomonas, Achromobacter) along with established correlates of CF disease state (age, BMI, CF-related diabetes). In addition, our models selected nonpathogen taxa (Fusobacterium, Rothia) as positive predictors of lung health. CONCLUSIONS: These results support a reconsideration of clinical microbiology pipelines to ensure the provision of informative data to guide clinical practice.

Large-Scale Characterization of Systemic Sclerosis Serum Protein Profile: Comparison to Peripheral Blood Cell Transcriptome and Correlations With Skin/Lung Fibrosis.

OBJECTIVE: To provide a large-scale assessment of serum protein dysregulation in diffuse cutaneous systemic sclerosis (dcSSc) and to investigate serum protein correlates of SSc fibrotic features. METHODS: We investigated serum protein profiles of 66 participants with dcSSc at baseline who were enrolled in the Scleroderma: Cyclophosphamide or Transplant Trial and 66 age- and sex-matched healthy control subjects. A panel of 230 proteins, including several cytokines and chemokines, was investigated. Whole blood gene expression profiling in concomitantly collected samples was performed. RESULTS: Among the participants with dcSSc, the mean disease duration was 2.3 years. All had interstitial lung disease (ILD), and none were being treated with immunosuppressive agents at baseline. Ninety proteins were differentially expressed in participants with dcSSc compared to healthy control subjects. Similar to previous global skin transcript results, hepatic fibrosis, granulocyte and agranulocyte adhesion, and diapedesis were the top overrepresented pathways. Eighteen proteins correlated with the modified Rodnan skin thickness score (MRSS). Soluble epidermal growth factor receptor was significantly down-regulated in dcSSc and showed the strongest negative correlation with the MRSS, being predictive of the score's course over time, whereas α1 -antichymotrypsin was significantly up-regulated in dcSSc and showed the strongest positive correlation with the MRSS. Furthermore, higher levels of cancer antigen 15-3 correlated with more severe ILD, based on findings of reduced forced vital capacity and higher scores of disease activity on high-resolution computed tomography. Only 14 genes showed significant differential expression in the same direction in serum protein and whole blood RNA gene expression analyses. CONCLUSION: Diffuse cutaneous SSc has a distinct serum protein profile with prominent dysregulation of proteins related to fibrosis and immune cell adhesion/diapedesis. The differential expression for most serum proteins in SSc is likely to originate outside the peripheral blood cells.

Lung Cancer Survival in Patients With Autoimmune Disease.

Importance: Patients with autoimmune disease and lung cancer pose a multidisciplinary treatment challenge, particularly with the advent of immunotherapy. However, the association between autoimmune disease and lung cancer survival is largely unknown. Objective: To determine the association between autoimmune disease and lung cancer survival. Design, Setting, and Participants: Retrospective cohort study between 2003 and 2019 at a single academic medical center (Northwestern University). A query of the Northwestern Medicine Enterprise Data Warehouse identified 349 patients with lung cancer and several autoimmune diseases. Types of lung cancers included small cell, adenocarcinoma, squamous cell carcinoma, non-small cell not otherwise specified, and large cell carcinoma. Autoimmune diseases included rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, mixed connective tissue disease, myositis, and Sjögren syndrome. Inclusion criteria were biopsy-confirmed lung cancer, autoimmune diagnosis confirmed by a rheumatologist, and death or an encounter listed in the electronic medical record within 2 years of study end. A control group of patients with biopsy-proven lung cancer but without autoimmune disease was identified. Data analysis was conducted from March to July 2020. Exposure: Presence of autoimmune disease. Main Outcomes and Measures: Overall survival and progression-free survival in patients with autoimmune disease. The hypothesis was that patients with autoimmune disease would have worse progression-free survival and overall survival compared with patients in the control group. Results: Of the original 349 patients, 177 met inclusion criteria. Mean (SD) age at lung cancer diagnosis was 67.0 (10.0) years and 136 (76.8%) were women. Most common autoimmune diseases were rheumatoid arthritis (97 [54.8%]), systemic sclerosis (43 [24.3%]), and systemic lupus erythematous (15 [8.5%]). Most common lung cancers were adenocarcinoma (99 [55.9%]), squamous cell carcinoma (29 [16.4%]), and small cell lung cancer (17 [9.6%]). A total of 219 patients (mean [SD] age at diagnosis, 65.9 [4.1] years; 173 [79.0%]) were identified as having lung cancer without autoimmune disease and included in the control cohort. Compared with patients in the control group, patients with autoimmune disease experienced no difference in overall survival (log-rank P = .69). A total of 126 patients (69.5%) with autoimmune disease received standard of care vs 213 patients (97.3%) in the control group (P < .001). No individual autoimmune disease was associated with worse prognosis, even among patients with underlying interstitial lung disease. Conclusions and Relevance: Compared with institutional controls, patients with autoimmune disease experienced no difference in survival despite the fact that fewer patients in this group received standard-of-care treatment. No individual autoimmune disease was associated with worse prognosis. Future multicenter prospective trials are needed to further evaluate autoimmune disease and lung cancer survival.

The NADase enzyme CD38: an emerging pharmacological target for systemic sclerosis, systemic lupus erythematosus and rheumatoid arthritis.

PURPOSE OF REVIEW: Here we review recent literature on the emerging role of nicotinamide adenine dinucleotide (NAD) metabolism and its dysfunction via the enzyme CD38 in the pathogenesis of rheumatologic diseases. We evaluate the potential of targeting CD38 to ameliorate NAD-related metabolic imbalance and tissue dysfunction in the treatment of systemic sclerosis (SSc), systemic lupus erythematous (SLE), and rheumatoid arthritis (RA). RECENT FINDINGS: In this review, we will discuss emerging basic, preclinical, and human data that point to the novel role of CD38 in dysregulated NAD-homeostasis in SSc, SLE, and RA. In particular, recent studies implicate increased activity of CD38, one of the main enzymes in NAD catabolism, in the pathogenesis of persistent systemic fibrosis in SSc, and increased susceptibility of SLE patients to infections. We will also discuss recent studies that demonstrate that a cytotoxic CD38 antibody can promote clearance of plasma cells involved in the generation of RA antibodies. SUMMARY: Recent studies identify potential therapeutic approaches for boosting NAD to treat rheumatologic diseases including SSc, RA, and SLE, with particular attention to inhibition of CD38 enzymatic activity as a target. Key future directions in the field include the determination of the cell-type specificity and role of CD38 enzymatic activity versus CD38 structural roles in human diseases, as well as the indicators and potential side effects of CD38-targeted treatments.

Calcinosis in Systemic Sclerosis: Updates in Pathophysiology, Evaluation, and Treatment.

PURPOSE OF REVIEW: Calcinosis is a common complication of systemic sclerosis with no known effective pharmacologic therapy. We reviewed the literature regarding systemic sclerosis-related calcinosis as well as other disorders of biomineralization in order to identify targets of future study for calcinosis. RECENT FINDINGS: Patients with systemic sclerosis-related calcinosis demonstrate systemic abnormalities in mineralization pathways, including decreased levels of the mineralization inhibitor inorganic pyrophosphate. Insights from other mineralization disorders suggest that local and systemic phosphate metabolism pathways involving the ABCC6, ENPP1, and NT5E genes play a critical role in regulation of ectopic calcification. Knockout models of these genes may lead to an appropriate murine model for study of calcinosis. Poly(ADP-ribose) polymerase (PARP) enzymes may also play a critical role in hydroxyapatite nucleation and warrant future study in systemic sclerosis. Study of local and systemic mineralization pathways, particularly phosphate metabolism pathways and PARP enzymes, should provide greater insight into the pathogenesis of systemic sclerosis-related calcinosis.

HLA and autoantibodies define scleroderma subtypes and risk in African and European Americans and suggest a role for molecular mimicry.

Systemic sclerosis (SSc) is a clinically heterogeneous autoimmune disease characterized by mutually exclusive autoantibodies directed against distinct nuclear antigens. We examined HLA associations in SSc and its autoantibody subsets in a large, newly recruited African American (AA) cohort and among European Americans (EA). In the AA population, the African ancestry-predominant HLA-DRB1*08:04 and HLA-DRB1*11:02 alleles were associated with overall SSc risk, and the HLA-DRB1*08:04 allele was strongly associated with the severe antifibrillarin (AFA) antibody subset of SSc (odds ratio = 7.4). These African ancestry-predominant alleles may help explain the increased frequency and severity of SSc among the AA population. In the EA population, the HLA-DPB1*13:01 and HLA-DRB1*07:01 alleles were more strongly associated with antitopoisomerase (ATA) and anticentromere antibody-positive subsets of SSc, respectively, than with overall SSc risk, emphasizing the importance of HLA in defining autoantibody subtypes. The association of the HLA-DPB1*13:01 allele with the ATA+ subset of SSc in both AA and EA patients demonstrated a transancestry effect. A direct correlation between SSc prevalence and HLA-DPB1*13:01 allele frequency in multiple populations was observed (r = 0.98, P = 3 × 10-6). Conditional analysis in the autoantibody subsets of SSc revealed several associated amino acid residues, mostly in the peptide-binding groove of the class II HLA molecules. Using HLA α/ß allelic heterodimers, we bioinformatically predicted immunodominant peptides of topoisomerase 1, fibrillarin, and centromere protein A and discovered that they are homologous to viral protein sequences from the Mimiviridae and Phycodnaviridae families. Taken together, these data suggest a possible link between HLA alleles, autoantibodies, and environmental triggers in the pathogenesis of SSc.

Calcinosis in scleroderma made crystal clear.

PURPOSE OF REVIEW: Review the current state of knowledge and recent developments in the field of scleroderma-related calcinosis [systemic sclerosis (SSc)-calcinosis], focusing on emerging information related to pathophysiology. RECENT FINDINGS: Recent studies have begun to characterize that factors that regulate ectopic mineralization, and those that underlie the imbalance of promoters and inhibitors of this process in SSc. SUMMARY: Calcinosis cutis due to ectopic mineralization is a common and highly troublesome complication of SSc. Despite its significant prevalence and clinical impact, the pathogenesis is poorly understood and effective treatment is lacking. More research to better understand the pathophysiology is needed for the identification of novel management strategies for this severe complication of SSc.

Myeloablation followed by autologous stem cell transplantation normalises systemic sclerosis molecular signatures.

OBJECTIVE: In the randomised scleroderma: Cyclophosphamide Or Transplantation (SCOT trial) (NCT00114530), myeloablation, followed by haematopoietic stem cell transplantation (HSCT), led to improved clinical outcomes compared with monthly cyclophosphamide (CYC) treatment in systemic sclerosis (SSc). Herein, the study aimed to determine global molecular changes at the whole blood transcript and serum protein levels ensuing from HSCT in comparison to intravenous monthly CYC in 62 participants enrolled in the SCOT study. METHODS: Global transcript studies were performed at pretreatment baseline, 8 months and 26 months postrandomisation using Illumina HT-12 arrays. Levels of 102 proteins were measured in the concomitantly collected serum samples. RESULTS: At the baseline visit, interferon (IFN) and neutrophil transcript modules were upregulated and the cytotoxic/NK module was downregulated in SSc compared with unaffected controls. A paired comparison of the 26 months to the baseline samples revealed a significant decrease of the IFN and neutrophil modules and an increase in the cytotoxic/NK module in the HSCT arm while there was no significant change in the CYC control arm. Also, a composite score of correlating serum proteins with IFN and neutrophil transcript modules, as well as a multilevel analysis showed significant changes in SSc molecular signatures after HSCT while similar changes were not observed in the CYC arm. Lastly, a decline in the IFN and neutrophil modules was associated with an improvement in pulmonary forced vital capacity and an increase in the cytotoxic/NK module correlated with improvement in skin score. CONCLUSION: HSCT contrary to conventional treatment leads to a significant 'correction' in disease-related molecular signatures.