Expression data from inflammatory myopathies

MHC-I overexpression in muscle biopsies is a hallmark of inflammatory myopathies.However the mechanisms of MHC-I overexpression in each disease is not well understood. Microarray analysis from MHC-I-microdissected myofibers showed a differential expression signature in each inflammatory myopathy. Innate immunity and IFN-I pathways are upregulated vs healthy controls, specifically in dermatomyositis (DM). RNA from MHC-I-positive myofibers were obtained from muscle biopsies of 5 patients with dermatomyositis, 5 with polymyositis, 4 with inclusion body myositis and normal looking fibers from healthy controls.