Myositis-specific autoantibodies and their clinical significance

The idiopathic inflammatory myopathies polymyositis (PM) and dermatomyositis (DM) have historically been defined using broad clinical and pathological criteria. These conditions affect both adults and children with clinical features including muscle weakness, skin disease, internal organ involvement, and an association with cancer in adults. Using a clinical-serological approach, PM and DM can be defined into more homogeneous subsets. In recent years, myositis-specific autoantibodies (MSAs) have been better characterized and include autoantibodies to the signal-recognition particle and aminoacyl tRNA-synthetase enzymes. In addition, clinically significant novel autoantibodies - anti-p155/p140, anti-CADM-140, and others - have been described in the disease spectrum. MSAs are directed against cytoplasmic or nuclear components involved in key regulatory intracellular processes including protein synthesis, translocation, and transcription. The striking association between unique serological profiles and distinct clinical phenotypes suggests that target autoantigens may play a role in disease induction and propagation. This review reports recent progress in myositis-specific autoantigens, particularly their clinical significance.