The profile and clinical significance of myositis-specific autoantibodies in Chinese patients with dermatomyositis

Abstract

Objective The aim of this study is to analyze the prevalence of myositis-specific autoantibodies (MSAs) and to elucidate their associations with clinical features in Chinese dermatomyositis (DM) patients. Methods Four hundreds and twenty-seven DM patients were enrolled in this retrospective study. Clinical features and sera were collected. Twelve subtypes of MSAs were detected by commercial test kits. The correlations between MSAs and clinical phenotypes in DM patients were calculated by t test, Mann-Whitney U test or χ2 test. In order to clarify whether MSAs subsets would be independent factors of certain clinical feature or not, separate models were established to test the correlation via the Logistic regression analysis. Results The positivity of MSAs was 69.8% in 427 patients with DM. Anti-ARS, anti-MDA5 and anti-TIF1-γ antibodies were the three most common MSAs in the DM patients with positivity of 19.9%, 17.6% and 17.1% respectively. Different kinds of rash associated with MSAs subtypes by χ2 test. Certain MSAs subtype might be an independent factor for clinical features via logistic regression analysis. Interstitial lung disease (ILD) was observed more frequently in patients carrying anti-MDA5 [OR=5.266, 95%CI (2.522, 10.996), P<0.01] and anti-Jo-1 [OR=6.232, 95%CI (1.674, 23.199), P=0.006]. On the contrary, anti-Mi2 [OR=0.208, 95%CI (0.074, 0.580, P=0.003] and anti-TIF1-γ [OR=0.189, 95%CI (0.096, 0.370), P<0.01] were protective factors against developing ILD. Anti-TIF1-γ was an independent risk factor for cancer-associated myositis [OR=5.907, 95%CI (2.868, 12.168), P<0.01]. Anti-TIF1-γ [OR=2.789, 95%CI (1.594, 4.880) P<0.01], anti-NXP2 [OR=2.983, 95%CI (1.274, 6.982), P=0.012] and anti-SAE1 [OR=4.815, 95%CI (1.082, 21.424), P=0.039] could worsen dysphagic tendencies. In contrast, anti-MDA5 [OR=0.349, 95%CI (0.169, 0.720), P=0.004] might decrease the prevalence of this manifestation. Conclusion Patients with DM have a high frequency of MSAs. Some subtypes of MSAs are correlated with and may be independent factors of different clinical phenotypes. These indicated that MSAs can be useful biomarkers in monitoring the extramuscular features in DM patients. Key words: Dermatomyositis; Antibody specificity; Biomedical research