Inflammatory muscle diseases: a critical review on pathogenesis and therapies

Based on unique clinicopathological criteria, the most common immune inflammatory muscle disorders include Dermatomyositis (DM), Polymyositis (PM), Necrotizing Myositis (NM), and sporadic Inclusion Body Myositis (sIBM). DM is an undeniably a complement-mediated microangiopathy with destruction of capillaries, hypoperfusion, and inflammatory cell stress on the perifascicular regions. Necrotizing Myopathy is a poorly studied subacute myopathy triggered by toxic, viral, or autoimmune factors with macrophages as the final effector cells. In PM and IBM cytotoxic CD8-positive T-cells clonally expand in situ and invade MHC-I-expressing muscle fibers. In sIBM, in addition to autoimmune inflammation, there are degenerative features characterized by vacuolization and accumulation of stressor and amyloid-related molecules. Advances in the immunobiology of these disorders are discussed including the interaction between pro-inflammatory and β-amyloid or stressor proteins. A critical review regarding tissue biomarkers and strategies for more effective treatments are presented.