Inflammatory myopathies: disease mechanisms.

PURPOSE OF REVIEW: Recent developments pertaining to disease mechanisms in the inflammatory myopathies are discussed, emphasizing those areas that are of particular interest to me.

RECENT FINDINGS: The identification and further characterization of the type 1 interferon pathway in dermatomyositis is leading down a path of genomic medicine. Myonuclear structural abnormalities and the presence of nucleic acid-binding proteins, including the TAR DNA binding protein TDP-43, in sporadic inclusion body myositis (sIBM) sarcoplasm are important recent observations. This is an area likely to provide deep understanding of the mechanism of myofiber injury in sIBM. Proteomic characterization of proteins in sIBM muscle, muscle functioning as a lymphoid tissue, and the nature of belief systems, particularly one pertaining to beta-amyloid and sIBM, are other areas of interest.

SUMMARY: Clarification of disease mechanisms is providing a basis for rational drug development for some patients with myositis.