AB0589 Hypercoagulable State Might Be Induced by Alveolar-Endothelial Damages in Interstitial Lung Disease Associated with Polymyositis/dermatomyositis

Background Polymyositis and dermatomyositis (PM/DM) are often complicated by interstitial lung diseases (ILD), which is an important cause of death. It has been reported that endothelial damages are likely to exist in PM/DM patients with ILD (PM/DM-ILD). Endothelial damages and oxidative stress induced hypercoagulable state in many connective tissue diseases (CTD) such as rheumatoid arthritis, systemic lupus erythematosus and systemic scleroderma. Recent evidence suggested that anticoagulation therapies might contribute to improve the disease activity of pneumonia related to CTDs. Objectives The purpose of this study was to clarify the association between the disease activity of ILD and blood coagulation disorders in patients with PM/DM. Methods This study is retrospective observation study. The medical records of 22 patients who were diagnosed as having PM/DM admitted to our hospital from April 2012 to March 2015 were reviewed in present study (median age: 50.5, female ratio: 81.8%). Diagnosis of ILD was evaluated by chest high-resolution CT. We reviewed the laboratory findings and autoantibody profile associated with PM/DM. Results Eighteen of 22 (81.8%) patients with PM/DM were diagnosed as having ILD. Autoantibodies associated with PM/DM were evaluated in 14 patients among 18 patients with PM/DM-ILD. Anti-aminoacyl-tRNA synthetases (ARS) and anti-MDA5 antibody was positive in 8/14 patients (57%) and 4/14 patients (29%), respectively. Anti-Jo-1 antibody was detected in 3 patients (38%), anti-PL7 in 3 patients (38%), anti-OJ in one patient (12%), and anti-EJ in one patient (12%) in 8 patients with anti-ARS antibody positive PM/DM-ILD. The levels of creatinine kinase (CK) in anti-ARS antibody positive PM/DM-ILD patients was higher than those in anti-ARS antibody negative PM/DM-ILD patients (median CK 2464 v.s 106 IU/ml, p=0.01). The levels of serum KL-6 and plasma D-dimer in anti-ARS antibody positive PM/DM-ILD patients tended to be higher than those in anti-ARS antibody negative PM/DM-ILD patients (median KL-6 691 v.s 489 IU/ml, D-dimer 2.57 v.s 1.96 ug/ml). Additionally, there is significantly positive correlation in the levels of between serum KL-6 and plasma D-dimer (R=0.58, p=0.0008). However, there is no correlation between the levels of serum KL-6 and blood coagulation tests, such as prothrombin time (%) and activated thromboplastin time. Conclusions These results suggest that anti-ARS antibody, especially anti-Jo-1 and anti-PL7, seems to be associated with the severity of muscular manifestation and alveolar-endothelial damages. The level of plasma D-dimer reflects the disease activity of ILD in patients with PM/DM. The hypercoagulable state might be induced by alveolar-endothelial damages and oxidative stress in PM/DM-ILD. Acknowledgement We thank Ms. Yuki Kaseda for excellent technical assistance. Disclosure of Interest None declared