| Background:Polymyositis and dermatomyositis (PM/DM) are systemic autoimmune diseases of unknown etiology that mainly affect skeletal muscles and other internal organs. Interstitial lung disease (ILD) is associated with high mortality in PM/DM patients, the presence of ILD requires a more aggressive approach in therapy.Objective:To determine the serum levels of anti-melanoma differentiation-associated gene 5(MDA5) antibodies and their clinical association in patients with PM and DM. The aims of this study are also to investigate the activation status of down-stream molecules of inflammasome in serum, and to explore its effects on the pathogenesis of DM.Methods:A total of 72 PM/DM patients hospitalized in our department from March, 2010 to December,2014 were recruited. Sera, clinical and laboratory data were collected. Serum concentrations of anti-MDA5 antibodies were determined by enzyme-linked immunosorbent assay (ELISA) in 72 adult PM/DM patients (49 with ILD,23 without ILD) and 8 healthy controls. The correlations between serum anti-MDA5 antibodies levels and clinical features or laboratory examinations of PM/DM patients were investigated. The levels of IL-1β and IL-18 were detected by ELISA.Results:Serum anti-MDA5 antibody positive rate in the DM patients (24.1%) were significantly higher compared with PM patients (0%, P<0.005) and healthy controls (0%, P<0.001). In DM subgroup, CADM patients presented a higher positive anti-MDA5 antibody rate than classic DM patients. The rate of ILD was significantly higher in anti-MDA5 antibody positive DM patients than anti-MDA5 antibody negative DM patients. The sensitivity and specificity of anti-MDA5 antibody for diagnosing ILD in DM patients were 84.2% and 94.7% respectively. The positive predictive value and negative predictive value of anti-MDA5 antibody were 78.5% and 96.8%, respectively. The levels of C-reactive proteinand (CRP) of anti-MDA5 antibody positive DM patients were significantly higher than anti-MDA5 antibody negative patients. Logistic multivariate analysis showed anti-MDA5 is an independent risk factor for death of ILD in DM (P=0.009, OR=7.45,95%CI 1.77-42.06)。The levels of IL-1β in anti-MDA5 antibody positive DM group was significantly higher than that in anti-MDA5 antibody negative DM group and control group, with statistical significance.Conclusion:In Chinese PM/DM patients, Serum anti-MDA5 antibody is mainly presented in DM patients. It is a strong predictor for diagnosing of DM with ILD. It is an independent risk factor for death of ILD in DM. in PM/DM patients. Innate immune plays a critical role in the pathogenesis of DM. The activation of inflammasome participates in the inflammation of anti-MDA5 antibody positive DM. |
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