AB0667 SPECIFICITY OF ANTI-TRNA SYNTHETASE AUTOANTIBODIES CORRELATED WITH CLINICAL COURSE AND PROGNOSIS OF MYOSITIS-ASSOCIATED INTERSTITIAL LUNG DISEASE

Background: Interstitial lung disease (ILD) is associated with mortality among patients with idiopathic inflammatory myopathy (IIM). Anti-aminoacyl-tRNA synthetase (anti-ARS) autoantibodies have been identified highly specific for IIM and coincidence of ILD. It has been identified that non-Jo1 positive anti-ARS patients may have decreased survival rate. However, differences of characteristics and prognosis in myositis-associated ILD with an individual anti-ARS autoantibody have not been clarified. Objectives: To compare the characteristics and cumulative survival of myositis-associated ILD with different positivity of anti-ARS antibodies. Methods: We investigated retrospectively all consecutive patients with myositis -associated ILD evaluated from 1999-2017.All autoantibodies were screened by using RNA and protein immunoprecipitation assays. Demographic data, laboratory findings and chest computed tomography (CT) images were obtained. Results: Among 105 patients with myositis-associated ILD, enrolled, 47 had anti-Jo1 antibody and 58 had non-Jo1 antibody: anti-EJ (n=20), anti-PL12 (n=12), ant-PL7 (n=11), anti-KS (n=8) and anti OJ (n=7). The diagnosis at first visit were polymyositis (PM; n=28), dermatomyositis (DM; n=42), clinically amyopathic dermatomyositis (CADM; n=3) and antisynthetase syndrome (ASS; n=31). Most common causes of death in this study were exacerbation of ILD (n=10, 71.4%). Anti-Jo-1 positive patients had better ILD prognosis than non-Jo1 patients (log rank test, p = 0.03). The prevalence of rapidly progressive ILD (RP-ILD) and upper lung field lesions in CT scans were significantly higher in anti-EJ positive patients (p=0.02 and p=0.05, respectively). Although the prognosis of ILD was not significantly different among 6 anti-ARS antibodies, anti-EJ positive patients had poor ILD prognosis than anti-Jo1 patients with the 5-year unadjusted cumulative survival was 73% and 95%, respectively. Conclusion: Our data confirm that the characteristics and outcomes of myositis-associated ILD are distinct by anti-ARS antibodies and highlighted that anti-EJ antibody positivity associated with relatively poor prognosis and RP-ILD. References [1] McHugh NJ, Tansley SL. Nat Rev Rheumatol. 2018; 20;14(5):290-302. [2] aggarwal, R. et al. Ann. Rheum. Dis. 2014; 73: 227–232 [3] Shi J. et al. J Rheumatol2017; 44: 1051-1057 [4] Takanashi S, et al. Rheumatology (Oxford). 2019Jan8. doi: 10.1093/rheumatology/key420. Acknowledgement: The authors would particularly like to thank Etsuko Iwata and Masui for their assistance Disclosure of interests: None declared