Idiopathic Inflammatory Myopathy—Molecular Mechanisms Underlying Its Pathogenesis and Physical Therapy Effects

Idiopathic inflammatory myopathies (IIMs) are rare autoimmune disorders characterized by muscle weakness. As currently used immunosuppressive treatment presents several limitations, recent investigations focus on elucidating immune and nonimmune molecular mechanisms underlying its pathogenesis. Mitochondrial dysfunctions, endoplasmic reticulum stress, neutrophil dysregulation, and alterations in myokines and cell death pathways have been implicated in IIM pathophysiology. In this paper, the newest therapeutic strategies targeting reactive oxygen species overproduction, neutrophil extracellular traps formation, and pyroptotic and necroptotic pathways together with mitochondrial transplantations will be presented, and their safety and efficacy will be discussed. As physical therapy constitutes an essential part of IIM management, an additional focus will be directed towards molecular mechanisms underlying the effects of exercises in myositis treatment. Furthermore, the interplay between immune and nonimmune mechanisms will be analyzed and the translational challenges and limitations of current studies will be investigated.