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Resume Objectif Dans la sclerodermie systemique (ScS) et les myopathies inflammatoires idiopathiques (MII), les auto-anticorps sont utilises dans la pratique quotidienne comme biomarqueurs des phenotypes cliniques. Cette etude vise a estimer la prevalence des anticorps specifiques des myosites (ASM) et des anticorps associes aux myosites (AAM) en utilisant deux tests immunoblots differents dans une cohorte de patients atteints de ScS bien caracterises, puis a etudier leurs associations cliniques. Methodes Dans cette etude transversale, les serums de 300 patients ont ete testes de facon consecutive, avec realisation simultanee des tests immunoblots « myosites » Euroimmun® et D-tek®. Resultats La prevalence des ASM/AAM, ASM et AAM etait respectivement de 17,0 %, 8,0 % et 9,7 %. En combinant les resultats des deux tests, des anticorps anti-PM/Scl 100 etaient presents chez 5,0 % (intervalle de confiance a 95 % : 2,8 ; 8,1) ; anti-PM/Scl 75 et anti-TIF1γ chez 3,7 % (1,8 ; 6,5) ; anti-Ku chez 3,0 % (1,4 ; 5,6) ; anti-MDA5 chez 1,3 % (0,4 ; 3,4) ; anti-Mi-2 β, anti-NXP2, anti-PL-7 et anti-SRP chez 0,7 % (0,08 ; 2,4) ; anti-EJ et anti-PL-12 chez 0,3 % (0,01 ; 1,8) des patients. Aucune reactivite anti-SAE1, Jo-1 ou OJ n’a ete observee. Les anticorps anti-PM/Scl 75 etaient associes a la pneumopathie interstitielle (80 % contre 42 %) et la myosite (27 % contre 3 %) ; les anticorps anti-Ku etaient associes avec la myosite (33 % contre 3 %). Conclusion Dans cette etude transversale portant sur 300 patients atteints de ScS, la prevalence des ASM/AAM, des ASM et des AAM, testes a partir de deux immunoblots differents, etait respectivement de 17,0 %, 8,0 % et 9,7 %. La positivite des AAM etait associee a la pneumopathie interstitielle et a la myosite, mais cette etude n’a pas mis en evidence d’association clinique avec les ASM.

International audience; Fibroblasts (Fb) are key effector cells in systemic sclerosis (SSc). Fb stimulation with transforming growth factor beta 1 (TGF-β1) is considered as a positive control in studies assessing fibrogenesis. The lack of standardization of TGF-β1 stimulation might be responsible for discrepancies in experiments performed in different conditions. Using quantitative proteomics analysis, we evaluated the impact of changes in experimental conditions on proteomic profiles of primary Fb. Principal component analysis (PCA) identified several groups of differentially expressed proteins influenced by cell passage, culture medium, and both concentration and duration of exposure to TGF-β1 stimulation. Bioinformatics analysis revealed that late passages expressed proteins involved in senescence. TGF-β1 concentration and time of stimulation were correlated with the expression of proteins involved in the fibrogenesis and inflammatory processes. These data underline the need for standardization of culture conditions to allow inter-data comparisons in future in vitro studies, especially when using “omics” approaches.

Objective In systemic sclerosis (SSc) and idiopathic inflammatory myopathies (IIM), auto-antibodies are used in daily practice as potent biomarkers of clinical phenotypes. This study aimed at estimating the prevalence of myositis-specific (MSA) and myositis-associated (MAA) auto-antibodies in a well-characterised SSc patients cohort using two different immunoblot assays, and studying their clinical associations. Methods In this cross-sectional study, the sera of 300 consecutive patients were tested at the same time with myositis antibodies Euroimmun® and D-tek® immunoblot assays. Results Prevalence of MSA/MAA, MSA and MAA were 17.0%, 8.0% and 9.7%, respectively. When combining results of both tests, anti-PM/Scl 100 were found in 5.0% (95% confidence interval 2.8; 8.1); anti-PM/Scl 75 and anti-TIF1γ in 3.7% (1.8; 6.5); anti-Ku 3.0% (1.4; 5.6); anti-MDA5 in 1.3% (0.4; 3.4); anti-Mi-2 β, anti-NXP2, anti-PL-7 and anti-SRP in 0.7% (0.08; 2.4); anti-EJ and anti-PL-12 in 0.3% (0.01; 1.8) of patients. No reactivity against SAE1, Jo-1 or OJ was observed. Anti-PM/Scl 75 antibodies were associated with interstitial lung disease (80% vs. 42%) and myositis (27% vs. 3%); anti-Ku antibodies were associated with myositis (33% vs. 3%). Conclusion In this cross-sectional study of 300 SSc patients, the prevalence of MSA/MAA, MSA and MAA using immunoblot assays were 17.0%, 8.0% and 9.7%, respectively. MAA positivity was associated with ILD and myositis, but this study did not highlight any clinical associations with MSA positivity.

Background Fibroblasts (Fb) are key effectors cells in systemic sclerosis (SSc).1 Fb stimulation with TGF-β1 is usually considered as the positive control in studies assessing the fibrogenesis in SSc.2 Yet, the lack of standardisation of TGF-β1 stimulation might be responsible for discrepancies in experiments performed in different conditions. Proteomic approach allows the analysis of differential expression of the whole proteins (proteome) in Fb, and appears an interesting approach to compare different culture conditions. Objectives We designed this study to compare the whole protein expression in Fb stimulated by TGF-β1 in different conditions. Methods At fifth passage, primary culture of human Fb from healthy subjects (ATCC; PCS-201–012) were stimulated or not with different concentrations of recombinant human active TGF-β1 (0.04, 1, and 5 ng/mL) (R and D Systems; 240-B-002) during 24, 48 and 72 hours. Proteins were extracted and analysed using an eFASP LC-MS/MS approach on an Orbitrap mass spectrometer (Thermo Scientific; Q Exactive +). Proteins quantitation was performed by Maxquant and statistical analysis by Perseus using ANOVA and principal component analysis (PCA). Results A total of 3267 proteins were identified, of which 1957 showed differential expression using ANOVA analysis. PCA revealed several clusters of differential proteins expression (figure 1). There were clear clusters of protein expression related to (i) unstimulated and stimulated conditions, (ii) between the three different times of stimulation and (iii) to TGF-β1 concentrations used. Although the expression of proteins in Fb exposed to 0.04 and 1 ng/mL of TGF-β1 during 72 hour were rather close, there was a unique proteins profile related to the condition with 5 ng/mL of TGF-β1 during 72 hour. Figure 1: PCA representation of differential proteins expression in different conditions. [TGF-β1]=0.04 ng/mL: square; [TGF-β1]=1 ng/mL: circle; [TGF-β1]=5 ng/mL: diamond. The more the points appear distanced, the more different is the protein expression. Conclusions This study highlights a variation of proteins expression depending on both stimulation time and TGF-β1 concentrations in Fb culture. The identification of protein differentially expressed will provide insights in the impact of TGF-β1 on Fb physiology under stimulation conditions. These data underline the need of standardisation of culture conditions to allow inter-data comparisons using in sensitive “omic” approaches. References [1] Garret SM, Frost DB, Feghali-Bostwick C. The mighty fibroblast and its utility in scleroderma research. J Scleroderma Relat Disord2017;2(2):69–134. [2] Verrecchia F, Mauviel A. Transforming growth factor-beta signaling through the Smad pathway: role in extracellular matrix gene expression and regulation. J Invest Dermatol2002Feb;118(2):211–5. Disclosure of Interest None declared