Foxo/Atrogin induction in human and experimental myositis

► It is unknown if Atrogin is associated with sarcopenia in human myositis disorders. ► Aβ expression and autoimmune inflammation independently result in Foxo3A nuclear translocation and Atrogin-1 induction. ► Aβi accumulation and cellular immune activation may drive atrophy in sIBM and PM, respectively, or synergistically in sIBM. ► In either disorder, efforts to limit Foxo3A activation may be therapeutic.