ObjectiveTo determine the serum MDA5 levels and their clinical associations in patients with polymyositis/dermatomyositis (PM/DM).MethodsSerum anti-MDA5 antibody was detected by ELISA in 119 adult PM/DM patients,30 patients with systemic lupus erythematosus(SLE),30 patients with rheumatoid arthritis (RA),15 patients with primary Sj(O)gren's syndrome (SS),21 patients with pulmonary infection and 50 healthy controls.t-test,Mann-Whitney U test or chi-square test or Fisher exact test as well as Logistic multivariate regression analysis were carried out to compare the results of this study.ResultsSerum antiMDA5 antibody positive rate in DM patients(22.6％) were significantly higher compared with that of patients with PM (0,P＜0.01),patients with SLE (3.3％,X2=5.68,P＜0.05),RA (3.3％,X2=5.68,P＜0.05),pSS (0,P＜0.05) and pulmonary infection(0,P＜0.05) and healthy controls (0,P＜0.01).In the DM subgroup,CADM patients presented a higher positive anti-MDA5 antibody rate than classic DM patients.The incidence of arthritis,fever,vrash raised CEA and CA153 level,and serum concentration of GGT and ferritin were significantly higher in the anti-MDA5 positive DM group than anti-MDA5 negative DM group (X2=4.08,8.06,6.357,32.4,4.867; Z=-2.86,-2.44; P value of all these tests were less than 0.05 ),while the rate of serum positive ANA,serum level of CK and T,NK cell counts in the peripheral blood were much lower than those in anti-MDA5 negative DM group(X2=4.08; Z=-2.072,-2.013,-2.907; all P＜0.05).Moreover,the incidence of acute/subacute interstitial pneumonia(A/SIP) was significantly higher in anti-MDA5 positive DM patients than anti-MDA5 negative DM patients.The sensitivity and specificity of anti-MDA5 antibody for diagnosing A/SIP in DM patients were 88.2％ and 94％ respectively.Additionally,logistic multivariate analysis showed that anti-MDA5 was an independent risk factor for death of interstitial lung diseases (ILD) in DM (OR=8.46,95％CI 1.77～40.36,P＜0.01).ConclusionIn Chinese PM/DM patients,serum anti-MDA5 antibody is mainly present in DM patients and is a strong predictor for poor prognosis diagnosis of DM with A/SIP and is an independent risk factor for death of ILD in DM.

  Rheumatoid arthritis (RA) is a bone destructive autoimmune disease. Many patients with RA recognize fluctuations of their joint synovitis according to changes of air pressure, but the correlations between them have never been addressed in large-scale association studies. To address this point we recruited large-scale assessments of RA activity in a Japanese population, and performed an association analysis. Here, a total of 23,064 assessments of RA activity from 2,131 patients were obtained from the KURAMA (Kyoto University Rheumatoid Arthritis Management Alliance) database. Detailed correlations between air pressure and joint swelling or tenderness were analyzed separately for each of the 326 patients with more than 20 assessments to regulate intra-patient correlations. Association studies were also performed for seven consecutive days to identify the strongest correlations. Standardized multiple linear regression analysis was performed to evaluate independent influences from other meteorological factors. As a result, components of composite measures for RA disease activity revealed suggestive negative associations with air pressure. The 326 patients displayed significant negative mean correlations between air pressure and swellings or the sum of swellings and tenderness (p=0.00068 and 0.00011, respectively). Among the seven consecutive days, the most significant mean negative correlations were observed for air pressure three days before evaluations of RA synovitis (p=1.7x10-7, 0.00027, and 8.3x10-8, for swellings, tenderness and the sum of them, respectively). Standardized multiple linear regression analysis revealed these associations were independent from humidity and temperature. Our findings suggest that air pressure is inversely associated with synovitis in patients with RA.