ADHESION MOLECULES EXPRESSION IN JUVENILE DERMATOMYOSITIS, POLYMYOSITIS AND DERMATOMYOSITIS

Background: The idiopathic inflammatory myopathies including juvenile dermatomyositis (JDM), polymyositis (PM) and dermatomyositis (DM), present many common clinical features; although it is well known that JDM is characterized by marked vasculitis, more than PM and DM.ICAM-1 was identified as the main endothelial ligand activated and its expression was more intense in DM microvessels than PM. In contrast, VCAM-1 also involved in endothelial cells induction presented minor role in the pathogenesis of PM and DM. There are no studies concerning ICAM-1 and VCAM-1 expression in JDM on muscle tissue. The immunopathological mechanisms that underlie these diseases are not completely clarified. A more extensive analysis of the adhesion molecules on these inflammatory myopathies might contribute for the better understanding of the immunological mechanisms underlying these diseases.Objectives: To study the differential expression of adhesion molecules ICAM-1 and VCAM-1 on vessels and muscle fibers in JDM, PM, and DM.Methods: 37 JDM, 15 PM, and 15 DM muscle fragments from patients diagnosed according to Bohan and Peter criteria. Immunohistochemical tests (StreptABComplex/HRP) for VCAM-1 and ICAM-1 (Dakopatts) were performed on serial frozen muscle sections in all patients, with and without corticosteroids. Staining was assessed semi-quantitatively as (-): no staining; (+): less than 25%; (++): less than 50%; (+++): less than 75%; (++++): 100% staining.Results: ICAM-1 expression on vessels was significantly (p=0,0010) more present on JDM than PM and DM. On the other hand, on muscle fibers, ICAM-1 expression was absent in JDM, but present in 33,4% and 40% respectively in PM and DM (p=0,0013). VCAM-1 expression on vessels was significantly more present in PM and DM than JDM (p<0,0001) and VCAM-1 expression on muscle fibers was almost absent in the three groups (p=0,1721). JDM PM DM ++/+++ ICAM-1 VESSELS 81,1% 33,3% 40,0% ICAM-1 FIBERS 2,7% 33,4% 40,0% VCAM-1 VESSELS 0 46,7% 60,0% VCAM-1 FIBERS 0 0 6,7% Positive expression (++/+++) of adhesion molecules expression on vessels and muscle fibers in JDM, PM and DM Positive expression (++/+++) of adhesion molecules expression on vessels and muscle fibers in JDM, PM and DMConclusion: This study emphatizes the importance of adhesion molecules in the pathophisiology of the inflammatory myopathies showing striking difference among JDM and PM and DM: intensive expression of ICAM-1 on vessels in DMJ, corroborating the microvascular involvement in JDM. On the other hand, adhesion molecules expression do not contribute for the differentiation between PM and DM. VCAM-1 seems not to play a major role in JDM, as already described in PM and DM. Adhesion molecules expression in JDM presents different aspects when compared to PM and DM. *Supported by FAPESPCitation: , volume , supplement , year 2002, page Session: Myopathies and soft tissue diseases