title: Autoantibodies in polymyositis and dermatomyositis.
abstract: Inflammatory myopathies are a group of acquired diseases, characterized by immunoflogistic processes primarily involving the skeletal muscle. According to recent classification criteria, four major diseases have been identified: polymyositis (PM), dermatomyositis (DM), sporadic inclusion body myositis (IBM), and necrotizing autoimmune myositis (NAM). Autoantibodies can be found in the sera of most patients with myositis. Myositis-specific autoantibodies (MSAs) are markers of very specific disease entities within the spectrum of myositis, and target proteins involved in key processes of protein synthesis. Myositis autoantigens comprise the well-defined aminoacyl-tRNA synthetases, the Mi-2 helicase/histone deacetylase protein complex, and the signal recognition particle (SRP) ribonucleoprotein, together with novel targets such as TIF1-γ, MDA5, NXP2, SAE, and HMGCR. Recent studies suggest that autoantigens drive a B cell antigen-specific immune response in muscles. Interestingly, an increased expression of Jo-1 and Mi-2 in regenerating fibers in muscle biopsies from PM and DM patients compared to normal was demonstrated. Myositis autoantigen up-regulation was observed in neoplastic tissues, thus representing a potential link between cancer and autoimmunity in myositis. Non-immunological mechanisms seem to participate to the pathogenesis of inflammatory myopathies; induction of endoplasmic reticulum stress response in response to abnormal muscle regeneration and inflammation has recently been reported in patients with myositis. This review article provides an update of new emerging insights about the clinical and pathophysiologic role of principal autoantibodies in myositis.
authors.affiliation: Department of Medicine, Division of Rheumatology, University of Padova, Padova, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Ghirardello
authors.forename: Nicola
authors.initials: N
authors.lastname: Bassi
authors.forename: Lavinia
authors.initials: L
authors.lastname: Palma
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Borella
authors.forename: Marta
authors.initials: M
authors.lastname: Domeneghetti
authors.forename: Leonardo
authors.initials: L
authors.lastname: Punzi
authors.forename: Andrea
authors.initials: A
authors.lastname: Doria
mesh_terms: D000604:Amino Acyl-tRNA Synthetases / Q000276:immunology / Q000378:metabolism*; D001323:Autoantibodies / Q000276:immunology* / Q000378:metabolism; D001324:Autoantigens / Q000276:immunology / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D003882:Dermatomyositis / Q000097:blood* / Q000276:immunology / Q000503:physiopathology; D006643:Histidine-tRNA Ligase / Q000276:immunology / Q000378:metabolism; D006801:Humans; D056245:Mi-2 Nucleosome Remodeling and Deacetylase Complex / Q000276:immunology / Q000378:metabolism*; D018485:Muscle Fibers, Skeletal / Q000276:immunology / Q000378:metabolism; D018482:Muscle, Skeletal / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D012038:Regeneration; D018271:Signal Recognition Particle / Q000276:immunology / Q000378:metabolism*
chemical_list: D001323:Autoantibodies; D001324:Autoantigens; D015415:Biomarkers; C115323:CHD4 protein, human; D018271:Signal Recognition Particle; D056245:Mi-2 Nucleosome Remodeling and Deacetylase Complex; D000604:Amino Acyl-tRNA Synthetases; D006643:Histidine-tRNA Ligase