筋炎と抗アミノアシル転写RNA合成酵素（ARS）抗体

Idiopathic Inflammatory Myopathy and Anti-aminoacyl-tRNA Synthetase Antibody

抗アミノアシル転写RNA合成酵素（ARS）抗体（抗Jo-1，PL-7，PL-12，EJ，OJ，KS，Ha，Zo抗体）陽性症例は抗ARS抗体症候群（筋炎，間質性肺炎，機械工の手，レイノー現象，多関節炎）を呈すが，陽性となる抗体ごとに臨床像の多様性もある。2014年OJ，Ha，Zo以外のARSに対する「抗ARS抗体」の測定が保険収載された。近年，筋線維の核内アクチン凝集や抗Jo-1抗体筋炎マウスが報告された。

Abstract

Anti-aminoacyl-tRNA synthetase (ARS) antibodies (anti-Jo-1, anti-PL-7, anti-PL-12, anti-EJ, anti-KS, anti-OJ, anti-Ha, and anti-Zo antibodies) are found in 25 to 40% of myositis patients. The patients with these antibodies have anti-synthetase syndrome with one or more of the following clinical features: myositis, interstitial lung disease, arthritis, fever, Raynaud's phenomenon, and mechanic's hands. In Japan, health insurance coverage of treatments for patients in whom the “anti-ARS antibodies,” anti-Jo-1, anti-PL-7, anti-PL-12, anti-EJ, and anti-KS are detected by enzyme-linked immunosorbent assay was approved by the Ministry of Health, Labour and Welfare in 2014. Recently, clinical features have been discovered to be heterogeneous. Patients with the anti-PL-7, anti-PL-12, anti-KS, and anti-OJ antibodies exhibit interstitial lung disease rather than myositis. Interstitial lung disease is related to the prognosis of this syndrome. Regarding histopathological findings of the muscle, perimysial connective tissue fragmentation with positive staining for alkaline phosphatase is the characteristic feature. Myonuclear actin filament inclusions are also detected. A recent work demonstrated that immunization of mice with histidyl-tRNA synthetase results in muscle inflammation consistent with myositis. These findings promote understanding of the pathological mechanism of the development of myositis associated with anti-ARS antibodies.