The inflammatory milieu in idiopathic inflammatory myositis

Abstract

The idiopathic inflammatory myopathies (IIM) are systemic autoimmune diseases that have predominant mononuclear inflammatory cell infiltrates in the skeletal muscle. The cells that are typically involved in the pathogenesis of disease are B-lymphocytes, T-lymphocytes, macrophages, dendritic cells, and natural killer cells. However, in addition to these immune cells, cells of nonimmunologic origin, such as myocytes, may be directly involved in the immune response. The local milieu also consists of distinct cytokine and chemokine profiles considered related to type 1 interferon stimulation. Tumor necrosis factor and interleukin 1 are also prominent, proinflammatory cytokines involved in the evolution of IIM. Although the pathologic processes involved in IIM have yet to be fully elucidated, we understand the inflammatory milieu is a model of dynamic flux made of diverse cytokine and chemokine expressions leading to alterations in muscle fiber structure and function.

Effects of immunosuppressive treatment on interleukin-15 and interleukin-15 receptor α expression in muscle tissue of patients with polymyositis or dermatomyositis

“…This trans-presentation is anticipated to be relevant for T cells as they express IL-2Rβ and γc subunits on their cell membrane 17 32. T cell infiltration in skeletal muscle is a characteristic histopathological feature of PM/DM 33. T cells usually maintain a state of homeostasis even after IS treatment, as shown by our data in this study and in a previous report 34.…”

Treatment with CA-074Me, a Cathepsin B inhibitor, reduces lung interstitial inflammation and fibrosis in a rat model of polymyositis

“…In contrast to DM, CD4 þ T cells and B cells are known to predominate in the perivascular areas of the muscle tissue. 36 Nevertheless, there remains much about pathogenesis to be learned in ILD in PM/DM, which might differ from mechanisms in the lung. A recent study showed low counts of peripheral T cells and a low percentage of CD4 þ T cells were associated with the presence of ILD in PM/DM.…”

Pathogenesis, classification and treatment of inflammatory myopathies

“…Thus, endomysial infiltratesfound predominantly in polymyositis and sIBM-are mainly composed of CD8 + T cells, CD4 + T cells, dendritic cells (DCs) and macrophages, whereas the peri vascular infiltrates that predominate in dermatomyositis are mainly composed of CD4 + T cells, DCs, and macro phages, with occasional B cells ( Figure 1). [10][11][12] …”