Clinical value of myositis antibodies in patients with connective tissue disease-associated interstitial lung diseases

Abstract

Objective: To investigate the clinical significance of detection of myositis-specific antibodies (MSAs) and myositis-associated antibodies (MAAs) in patients with connective tissue disease-associated interstitial lung diseases (CTD-ILD). Methods: Serum samples of 120 patients with CTD-ILD admitted to the Department of Respiratory, Affiliated Drum Tower Hospital of Nanjing University Medical College from December 2016 to April 2018 were collected for analysis. The patients included 45 with polymyositis/dermatomyositis (PM/DM), 36 with Sjogren's syndrome (SS) and 39 with undifferentiated connective tissue disease (UCTD). There were 37 males and 83 females with an average age of (56±11) years. Thirty-two patients with non-CTD-ILD, 10 males and 22 females with an average age of (42±17) years, were enrolled as the control group. Euroline Autoimmune Inflammatory Myopathies 16 Ag kit was used for detecting MSAs and MAAs, and the positive rates of serum MSAs and MAAs were calculated. The antibody distribution and clinical characteristics of different groups were analyzed and compared. Results: Eighty-nine of the 120 patients with CTD-ILD were positive for MSA and/or MAA (74.2%), and the detection rates of MSAs and MAAs were 52.5% (63/120) and 61.7% (74/120) respectively. No myositis antibody was detected in the non-CTD-ILD group. The detection rates of MSAs in PM/DM-ILD group, SS-ILD group and UCTD-ILD group were 75.6% (34/45), 33.3%(12/36) and 43.6%(17/39) respectively. The total detection rate of MSAs in PM/DM group was significantly higher than that in SS group and UCTD group (χ(2)=14.53, 8.95, 0.01). The anti-ARS was the most frequent (50/120, 41.7%). The positive rates of MAAs in the three groups were 64.4%(29/45), 77.8%(28/36), 43.6%(17/39) respectively, and anti-Ro-52 accounted for 60%(72/120), and were highly correlated with MSAs such as anti-Jo-1 antibodies. Conclusion: Myositis antibody profiling should be performed in patients with ILD who were negative for conventional autoimmune antibody testing and had no CTD. In patients with SS-ILD and UCTD-ILD, the myositis antibody spectrum could detect the presence of myositis-specific antibodies and myositis-related antibodies in some patients, and its role in clinical diagnosis and treatment needed further observation.