炎症性筋疾患の自己抗体update

Autoantibodies of Inflammatory Myopathies: Update

炎症性筋疾患（筋炎）は免疫学的機序により筋線維が障害される疾患の総称である。筋炎はさまざまな病態機序を背景に持つ疾患の集合体であり，臨床症状，筋病理，自己抗体の3つの側面から個別に分類されてきた。筋炎の自己抗体は，疾患概念の変遷や新規自己抗体の発見から，免疫介在性壊死性ミオパチーに関連した自己抗体，アミノアシルtRNA合成酵素に対する自己抗体，皮膚筋炎に関連した自己抗体，他疾患に関連した自己抗体に分けることが可能である。

Abstract

Inflammatory myopathies are a heterogeneous group of immune-mediated diseases that involve the skeletal muscle as well as many other organs. In addition to a histological diagnosis at muscle biopsy, the clinical phenotypes of inflammatory myopathies can be defined by the presence of various autoantibodies that are originally detected by RNA or protein immunoprecipitation. However, the correlation between histological features and autoantibodies has not been fully elucidated. Immune-mediated necrotizing myopathy (IMNM), which is characterized by significant necrotic and regeneration muscle fibers with minimal or no inflammatory cell infiltration, is associated with the presence of autoantibodies. IMNM is now classified as a distinct category of inflammatory myopathies, separate from polymyositis, dermatomyositis, and sporadic inclusion body myositis. Here, we divided the autoantibodies of inflammatory myopathies into the following categories: those associated with IMNM, those with activity against aminoacyl transfer RNA synthetase, those associated with dermatomyositis, and those related to other disorders, including overlap syndrome, inclusion body myositis, and primary biliary cirrhosis. The detection of autoantibodies against signal recognition particle or 3-hydroxy-3-methylglutaryl-coenzyme A reductase is useful for the diagnosis of IMNM. The screening of autoantibodies has clinical relevance for managing patients with inflammatory myopathies.