Soluble markers of B cell activation suggest a role of B cells in the pathogenesis of systemic sclerosis-associated pulmonary arterial hypertension

IntroductionSoluble markers of B cell activation are interesting diagnostic and prognostic tools in autoimmune diseases. Data in systemic sclerosis (SSc) are scarce and few studies focused on their association with disease characteristics.Methods1. Serum levels of 14 B cell biomarkers (β2-microglobulin, rheumatoid factor (RF), immunoglobulins (Ig) G, IgA, IgM, BAFF, APRIL, soluble (s)TACI, sBCMA sCD21, sCD23, sCD25, sCD27, CXCL13) were measured in SSc patients and healthy controls (HC). 2. Associations between these biomarkers and SSc characteristics were assessed. 3. The pathophysiological relevance of identified associations was explored by studying protein production in B cell culture supernatant.ResultsIn a discovery panel of 80 SSc patients encompassing the broad spectrum of disease manifestations, we observed a higher frequency of RF positivity, and increased levels of β2-microglobulin, IgG and CXCL13 compared with HC. We found significant associations between several biomarkers and SSc characteristics related to disease phenotype, activity and severity. Especially, serum IgG levels were associated with pulmonary hypertension (PH); β2-microglobulin with Nt-pro-BNP and DLCO; and BAFF with peak tricuspid regurgitation velocity (TRV). In a validation cohort of limited cutaneous SSc patients without extensive ILD, we observed lower serum IgG levels, and higher β2-microglobulin, sBCMA, sCD23 and sCD27 levels in patients with pulmonary arterial hypertension (PAH). BAFF levels strongly correlated with Nt-pro-BNP levels, FVC/DLCO ratio and peak TRV in SSc-PAH patients. Cultured SSc B cells showed increased production of various angiogenic factors (angiogenin, angiopoietin-1, VEGFR-1, PDGF-AA, MMP-8, TIMP-1, L-selectin) and decreased production of angiopoietin-2 compared to HC.ConclusionSoluble markers of B cell activation could be relevant tools to assess organ involvements, activity and severity in SSc. Their associations with PAH could plead for a role of B cell activation in the pathogenesis of pulmonary microangiopathy. B cells may contribute to SSc vasculopathy through production of angiogenic mediators

Community-Level Responses to Iron Availability in Open Ocean Plankton Ecosystems

Predicting responses of plankton to variations in essential nutrients is hampered by limited in situ measurements, a poor understanding of community composition, and the lack of reference gene catalogs for key taxa. Iron is a key driver of plankton dynamics and, therefore, of global biogeochemical cycles and climate. To assess the impact of iron availability on plankton communities, we explored the comprehensive bio-oceanographic and bio-omics data sets from Tara Oceans in the context of the iron products from two state-of-the-art global scale biogeochemical models. We obtained novel information about adaptation and acclimation toward iron in a range of phytoplankton, including picocyanobacteria and diatoms, and identified whole subcommunities covarying with iron. Many of the observed global patterns were recapitulated in the Marquesas archipelago, where frequent plankton blooms are believed to be caused by natural iron fertilization, although they are not captured in large-scale biogeochemical models. This work provides a proof of concept that integrative analyses, spanning from genes to ecosystems and viruses to zooplankton, can disentangle the complexity of plankton communities and can lead to more accurate formulations of resource bioavailability in biogeochemical models, thus improving our understanding of plankton resilience in a changing environment

Intravenous immunoglobulins improve skin fibrosis in experimental models of systemic sclerosis

Abstract Systemic sclerosis (SSc) is the most severe systemic autoimmune disease with currently no cure. Intravenous immunoglobulins (IVIg) are an attractive candidate in this disease to counteract inflammation and fibrosis but data are scarce and conflicting. This study, assessed the effects of IVIg in a murine HOCl-induced model of SSc. We showed that IVIg prevented skin inflammation and fibrosis, by mitigating the immune cell infiltration (p = 0.04), proinflammatory cytokines gene overexpression (IL1β, p = 0.04; TNFα, p = 0.04; IL6, p = 0.05), skin and dermal thickening (p = 0.003 at d21 and p = 0.0003 at d42), the expression markers of fibrosis, such as αSMA (p = 0.031 for mRNA and p = 0.05 for protein), collagen (p = 0.05 for mRNA and p = 0.04 for protein, p = 0.05 for the hydroxyproline content) and fibronectin (p = 0.033 for mRNA). Moreover, IVIg prevented HOCl-induced alterations in splenic cell homeostasis. When administered in curative mode, despite their ability to reduce skin and dermal thickness (p < 0.0001 and p = 0.0002), IVIg showed partial or more mixed effects on skin inflammation and established fibrosis. These data favor further clinical trials in SSc patients on the potential efficiency of early and/or repeated IVIg administration

Acquired Hemophilia A in IgG4-Related Disease: Case Report, Immunopathogenic Study, and Review of the Literature

International audienceWe report the observation of a 75-year-old patient referred for cervical lymphadenopathies. A pre-lymphadenectomy blood work revealed an asymptomatic elevation of aPTT with low factor VIII (FVIII) levels and high anti-FVIII antibodies titers, consistent with acquired hemophilia A (AHA). Histological work-up of a cervical lymphadenopathy revealed benign follicular hyperplasia with IgG4+ lymphoplasmacytic infiltration; and serum IgG4 levels were markedly elevated, compatible with IgG4-related disease (IgG4-RD). He was successfully treated with a 9-month course of prednisone, secondarily associated with rituximab when an AHA relapse occurred. As this patient presented with an unusual association of rare diseases, we wondered whether there was a link between the two conditions. Our first hypothesis was that the anti-FVIII autoantibodies could be directly produced by the proliferating IgG4+ plasma cells as a result of broken tolerance to autologous FVIII. To test this assumption, we determined the anti-FVIII IgG subclasses in our patient and in a control group of 11 AHA patients without IgG4-RD. The FVIII inhibitor was mostly IgG4, with an anti-FVIII IgG4/IgG1 ratio of 42 at diagnosis and 268 at relapse in our patient; similar values were observed in non-IgG4-RD AHA patients. As a second hypothesis, we considered whether the anti-FVIII activity could be the result of a non-specific autoantibody production due to polyclonal IgG4+ plasma cell proliferation. To test this hypothesis, we measured the anti-FVIII IgG4/total IgG4 ratio in our patient, as well as in several control groups: 11 AHA patients without IgG4-RD, 8 IgG4-RD patients without AHA, and 11 healthy controls. We found that the median [min-max] ratio was higher in AHA-only controls (2.4 10-2 [5.7 10-4-1.79 10-1]), an oligoclonal setting in which only anti-FVIII plasma cells proliferate, than in IgG4-RD-only controls (3.0 10-5 [2.0 10-5-6.0 10-5]), a polyclonal setting in which all IgG4+ plasma cells proliferate equally. Our patient had intermediate ratio values (2.7 10-3 at diagnosis and 1.0 10-3 at relapse), which could plead for a combination of both mechanisms. Although no definitive conclusion can be drawn, we hypothesized that the anti-FVIII autoantibody production in our IgG4-RD AHA patient could be the result of both broken tolerance to FVIII and bystander polyclonal IgG4+ plasma cell proliferation

Biomarkers of haemodynamic severity of systemic sclerosis-associated pulmonary arterial hypertension by serum proteome analysis

International audienceObjectives To mine the serum proteome of patients with systemic sclerosis-associated pulmonary arterial hypertension (SSc-PAH) and to detect biomarkers that may assist in earlier and more effective diagnosis and treatment. Methods Patients with limited cutaneous SSc, no extensive interstitial lung disease and no PAH-specific therapy were included. They were classified as cases if they had PAH confirmed by right heart catheterisation (RHC) and serum collected on the same day as RHC; and as controls if they had no clinical evidence of PAH. Results Patients were mostly middle-aged females with anticentromere-associated SSc. Among 1129 proteins assessed by a high-throughput proteomic assay (SOMAscan), only 2 were differentially expressed and correlated significantly with pulmonary vascular resistance (PVR) in SSc-PAH patients (n=15): chemerin ( ρ =0.62, p=0.01) and SET ( ρ =0.62, p=0.01). To validate these results, serum levels of chemerin were measured by ELISA in an independent cohort. Chemerin levels were confirmed to be significantly higher (p=0.01) and correlate with PVR ( ρ =0.42, p=0.04) in SSc-PAH patients (n=24). Chemerin mRNA expression was detected in fibroblasts, pulmonary artery smooth muscle cells (PA-SMCs)/pericytes and mesothelial cells in SSc-PAH lungs by single-cell RNA-sequencing. Confocal immunofluorescence revealed increased expression of a chemerin receptor, CMKLR1, on SSc-PAH PA-SMCs. SSc-PAH serum seemed to induce higher PA-SMC proliferation than serum from SSc patients without PAH. This difference appeared neutralised when adding the CMKLR1 inhibitor α-NETA. Conclusion Chemerin seems an interesting surrogate biomarker for PVR in SSc-PAH. Increased chemerin serum levels and CMKLR1 expression by PA-SMCs may contribute to SSc-PAH pathogenesis by inducing PA-SMC proliferation

Factors associated with the 6-minute walk distance in patients with systemic sclerosis

Abstract Background There is an ongoing debate regarding the relevance of the 6-minute walking distance (6MWD) in systemic sclerosis (SSc) assessment, widely used as a usual test in these patients as well as an outcome measure in clinical trials. In this work, we aimed to assess the associations between the 6MWD and various disease parameters in patients with SSc. Methods Consecutive patients followed in our SSc National Reference Centre were included in this cross-sectional study if they fulfilled the 2013 American College of Rheumatology/European League Against Rheumatism criteria for SSc. Data were systematically collected during a comprehensive standardized evaluation that included a 6-minute walk test, clinical assessment, biological results, pulmonary function tests, transthoracic echocardiography, composite scores (European Scleroderma Study Group Activity Index, Medsger severity score, Health Assessment Questionnaire–Disability Index (HAQ-DI)) and treatments. Associations of the 6MWD with various disease parameters were assessed by linear regression in univariate and multivariate analyses. Results The study population comprised 298 patients (females 81%; mean age 58.2 ± 13.3 years; limited cutaneous SSc 82%; interstitial lung disease (ILD) 42%; pulmonary arterial hypertension (PAH) 6%). The 6MWD was significantly and independently associated with gender, age, body mass index, baseline heart rate (HR), HR variation during the test, PAH, history of arterial thrombosis and C-reactive protein levels, as well as with the HAQ-DI score in a sensitivity analysis. Muscle involvement, joint involvement and ILD were not independently associated with the 6MWD. Conclusions During SSc, the 6MWD is independently associated with initial HR and HR variation; with PAH but not ILD, suggesting that pulmonary vasculopathy may have a greater impact than parenchymal involvement on functional limitation; and with global markers of disease activity and patient disability. These results give clinicians further insight into how to interpret the 6MWD in the context of SSc

Simple gene signature to assess murine fibroblast polarization

International audienceAbstract We provide an original multi-stage approach identifying a gene signature to assess murine fibroblast polarization. Prototypic polarizations (inflammatory/fibrotic) were induced by seeded mouse embryonic fibroblasts (MEFs) with TNFα or TGFß1, respectively. The transcriptomic and proteomic profiles were obtained by RNA microarray and LC-MS/MS. Gene Ontology and pathways analysis were performed among the differentially expressed genes (DEGs) and proteins (DEPs). Balb/c mice underwent daily intradermal injections of HOCl (or PBS) as an experimental murine model of inflammation-mediated fibrosis in a time-dependent manner. As results, 1456 and 2215 DEGs, and 289 and 233 DEPs were respectively found in MEFs in response to TNFα or TGFß1, respectively . Among the most significant pathways, we combined 26 representative genes to encompass the proinflammatory and profibrotic polarizations of fibroblasts. Based on principal component analysis, this signature deciphered baseline state, proinflammatory polarization, and profibrotic polarization as accurately as RNA microarray and LC-MS/MS did. Then, we assessed the gene signature on dermal fibroblasts isolated from the experimental murine model. We observed a proinflammatory polarization at day 7, and a mixture of a proinflammatory and profibrotic polarizations at day 42 in line with histological findings. Our approach provides a small-size and convenient gene signature to assess murine fibroblast polarization

Pulmonary arterial hypertension in idiopathic inflammatory myopathies

International audienceOccurrence of pulmonary arterial hypertension (PAH) in idiopathic inflammatory myopathies (IIMs) without extensive interstitial lung disease (ILD) has rarely been described in the medical literature. This study aimed to report all cases with association of PAH and IIM in the French Pulmonary Hypertension (PH) Registry, to identify IIM features associated with the presence of PAH, and to describe treatment modalities of these patients.All cases of IIM-PAH were retrieved from the French PH Registry, which gathers PH patients prospectively enrolled by 27 referral hospital centers across France. Patients were excluded if they had an extensive ILD or overlap syndrome. Characteristics of IIM-PAH patients were compared with a control group of IIM patients without PH.Among the 5223 PH patients in the Registry, 34 had a diagnosis of IIM. Among them, 3 IIM-PAH patients (2 females and 1 male) had no evidence of extensive ILD or overlap syndrome, and were included in this study. In these 3 patients, dermatomyositis (DM) was the only identified IIM. One patient had autoantibodies classically associated with IIM (anti-Ku). PAH had always developed after IIM onset, was severe in all cases, and led to a marked functional impairment.By pooling our cases with 6 patients previously reported in the literature, and comparing them with a control cohort of 35 IIM patients without PH, we identify several IIM characteristics possibly associated with PAH occurrence, including DM subtype (78% vs 46%; P = 0.02), skin involvement (P = 0.04), anti-SSA antibodies (P = 0.05), and peripheral microangiopathy (P = 0.06).Overall, IIM-PAH patients were managed by corticosteroids and/or immunosuppressants, either alone or combined with PAH therapy. Patients did not seem to respond to IIM treatment alone.Our study reports for the first time the rare but possible association of PAH and IIM in a large prospective PH Registry. In that setting, PAH seems associated with DM, skin involvement, peripheral microangiopathy, and anti-SSA positivity. The best therapeutic strategy for IIM-PAH remains to be defined

Intravenous immunoglobulins in systemic sclerosis: Data from a French nationwide cohort of 46 patients and review of the literature

International audienceBACKGROUND:As intravenous immunoglobulins (IVIG) exhibit immunomodulatory and antifibrotic properties, they may be a relevant treatment for systemic sclerosis (SSc). The objectives of this work were thus to report on the efficacy and safety of IVIG in a population of SSc patients and to review the available literature.METHODS:46 patients from 19 French centers were retrospectively recruited. They were included if they had a diagnosis of SSc and received at least 1 IVIG infusion at a dosage >1g/kg/cycle. Relevant data collected at IVIG discontinuation were compared to those collected at IVIG initiation. A comprehensive literature review was performed.RESULTS:We observed a significant improvement of muscle pain (74% vs. 20%, p<0.0001), muscle weakness (45% vs. 21%, p=0.01), joint pain (44% vs. 19%, p=0.02), CK levels (1069±1552UI vs. 288±449UI, p<0.0001) and CRP levels (13.1±17.6mg/L vs. 9.2±16.6mg/L, p=0.001). We also noted a trend for an improvement of gastro-esophageal reflux disease (68% vs. 53%, p=0.06) and bowel symptoms (42% vs. 27%, p=0.06). Skin and cardiorespiratory involvements remained stable. Finally, corticosteroid daily dose was significantly lower by the end of treatment (13.0±11.6mg/day vs. 8.9±10.4mg/day, p=0.01). Only two severe adverse events were reported (one case of deep vein thrombosis and one case of diffuse edematous syndrome).CONCLUSION:Our work suggests that IVIG are a safe therapeutic option that may be effective in improving musculoskeletal involvement, systemic inflammation, digestive tract symptoms and could be corticosteroid sparing