THU0388 Differences in clinical courses and serum markers of interstitial lung disease associated with anti-aminoacyl-transfer rna synthetase antibody and anti-melanoma differentiation-associated gene 5 antibody-positive polymyositis/dermatomyositis
Authors: K. Akashi, Y. Nose, T. Shirai, Y. Fujikawa, T. Nagamoto, T. Okano, S. Takahashi, S. Sendo, A. Onishi, J. Saegusa, A. Morinobu
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Polymyositis/dermatomyositis (PM/DM) is a chronic autoimmune disease that is often complicated by interstitial lung disease (ILD). Anti-aminoacyl-transfer RNA synthetase antibody (ARS-Ab) and anti-melanoma differentiation-associated gene 5 antibody (MDA5-Ab) are highly detected in PM/DM with ILD. It was reported that ARS-Ab-positive-ILD (ARS-ILD) is often recurrent<sup>1</sup>, and patients with MDA5-Ab-positive-ILD (MDA5-ILD) develop fatal rapidly progressive ILD<sup>2</sup>. <h3>Objectives</h3> To evaluate the differences in clinical courses between ARS-ILD and MDA5-ILD, including the changes in serum ILD markers. <h3>Methods</h3> We retrospectively investigated 25 patients with ARS-ILD and 26 patients with MDA5-ILD who received induction therapy between <sup><sup>April 2002</sup></sup> and September 2017 at Kobe University Hospital. The survival rate and relapse-free survival rate were analysed with Kaplan-Meier estimation and the log-rank test. The differences in serum ILD markers between patients with ARS-ILD and MDA5-ILD were evaluated with the Student's t-test. <h3>Results</h3> Disease subtypes at diagnosis with PM/DM-associated ILD were as follows: Eleven ARS-ILD and no MDA5-ILD patients had PM, 10 ARS-ILD and 5 MDA5-ILD patients had DM, and 4 ARS and 21 MDA5 patients had amyopathic DM. The survival rate for MDA5-ILD was significantly lower than that for ARS-ILD (p&lt;0.01, figure 1A). On the other hand, there was no significant difference in the relapse-free survival rate between ARS-ILD and MDA5-ILD (p=0.25, figure 1B). The serum level of Krebs von den Lungen-6 was not significantly different between ARS-ILD and MDA5-ILD (1044.3±768.1 U/ml in ARS-ILD vs 1044. 863.1 ±566.5 U/ml in MDA5-ILD, p=0.33), but the serum level of ferritin was significantly higher in MDA5-ILD than in ARS-ILD (286.4±422.3 ng/ml in ARS-ILD vs 696.2±839.5 ng/ml in MDA5-ILD, p=0.04). Although the serum level of surfactant protein D (SP-D) in ARS-ILD was high, the SP-D level in MDA5-ILD was normal (158.9±82.1 ng/ml in ARS-ILD vs 46.3±22.1 ng/ml, p&lt;0.01). <h3>Conclusions</h3> MDA5-ILD patients should monitored for both rapidly progressive disease and relapsing disease. A normal SP-D level is a feature of MDA5-ILD. <h3>References</h3> [1] Nakazawa M, Kaneko Y, Takeuchi T. Risk factors for the recurrence of interstitial lung disease in patients with polymyositis and dermatomyositis: a retrospective cohort study. Clin Rheumatol2017. Epub ahead of print. [2] Hozumi H, Fujisawa T, Nakashima R, et al. Comprehensive assessment of myositis-specific autoantibodies in polymyositis/dermatomyositis-associated interstitial lung disease. Respir Med2016;121:91–9. <h3>Acknowledgements</h3> none. <h3>Disclosure of Interest</h3> None declared