Dermatomyositis, polymyositis and immune-mediated necrotising myopathies

• Published in: Biochimica et biophysica acta 2015-04, Vol.1852 (4), p.622-632
• Main Authors: Luo, Yue-Bei, Mastaglia, Frank L.
• Format: Article
• Language: English
• Subjects: Animals; Autoantibodies - immunology; Autoantibody; Autoimmune Diseases - immunology; Autoimmune Diseases - pathology; Complement Activation - immunology; Dermatomyositis; Dermatomyositis - immunology; Dermatomyositis - pathology; Histocompatibility Antigens Class I - immunology; Humans; Idiopathic inflammatory myopathy; Immune-mediated necrotising myopathy; Polymyositis; T-Lymphocytes - immunology; T-Lymphocytes - pathology; Vascular Diseases - immunology; Vascular Diseases - pathology
• ISSN: 0925-4439; 0006-3002; 1879-260X
• DOI: 10.1016/j.bbadis.2014.05.034

Dermatomyositis, polymyositis and immune-mediated necrotising myopathy are major forms of idiopathic inflammatory myopathy. We review here recent developments in understanding the pathology and pathogenesis of these diseases, and characterisation of autoantibody biomarkers. Dermatomyositis is traditionally considered to be due to a complement-mediated microangiopathy but the factors responsible for complement activation remain uncertain. Recent studies have emphasised the importance of the type I interferon pathway in the pathogenesis of the disease and have identified autoantibodies with specificities for different clinical subgroups of patients. Polymyositis is characterised by a cytotoxic T cell response targeting as yet unidentified muscle antigens presented by MHC Class I molecules, and can occur in isolation but is more often part of a multi-systemic overlap syndrome. The immune-mediated necrotising myopathies are heterogeneous and are distinguished from polymyositis by the sparseness of inflammatory infiltrates and recognition of an association with specific autoantibodies such as anti-SRP and anti-HMGCR in many cases. This article is part of a Special Issue entitled: Neuromuscular Diseases: Pathology and Molecular Pathogenesis. •Complement-dependent microangiopathy and activation of the type I IFN pathway play major roles in DM.•CD8+ T cell-mediated cytotoxicity is the cause of muscle injury in PM.•IMNM associated with anti-SRP antibody is complement-mediated.•IMNM associated with anti-HMGCR antibody can occur both in statin-treated and statin-naïve patients.