Relation of Soluble Factors of Immune System to Fenotype of Idiopathic Inflammatory Myopathies

Introduction: Idiopathic inflammatory myopathies (myositis, IIM) are heterogeneous group of rare autoimmune systemic diseases, characterized particularly by proximal skeletal muscle weakness. Heretogeneity of myositis is based on different pathogenetic mechanisms which may be reflected by variable imunophenotypic response in individual subtypes. Objectives: The aim of this work was to explore the associations and influence of soluble factors of immune system in patient's sera on phenotypic characteristics and subtypes of IIM, to describe their expression in inflammed muscle tissue and study their eventual role in pathogenesis by analysis of effect on immune and muscle cells in vitro. Results: We have described prevalence and characteristics of joint involvement in myositis patients and its significant association with anti-Jo-1 autoantibody. Further we confirmed the relation of anti-HMGCR antibody to immune mediated necrotizing myopathy, its tight relation to statins and recent increase in incidence. We showed inverse association of IFNα serum levels with muscle activity detected on MRI. Clinical activity positively correlated with IFN type-I pathway activation in patients with dermatomyositis. We also show positive correlation of resistin levels and clinical activity and correlation of activity..