AB0195 Semaphorin 3A as A Possible Immunoregulator in Systemic Sclerosis

Background Semaphorin 3A (sema 3A), is now recognized as a potent immuno-regulator during all stages of the immune response. Sema 3A expression has been recognized on T regulatory cells as a suppressive marker, contributing to the regulatory properties of these cells [1]. Decreased expression of sema 3A and correlation with disease activity has been reported in rheumatoid arthritis patients and systemic lupus erthematosus (SLE) [2,3]. The expression of sema 3A hasn't been evaluated in systemic sclerosis (SSc) thus far. Objectives To compare sema 3A serum levels in patients with SSc to SLE patients (disease control) and healthy controls. To measure expression of sema 3A in whole blood and on regulatory T-cells and correlate it with demographic, clinical and laboratory parameters in SSc. Methods 27 SSc patients were evaluated for demographics, clinical manifestations, routine laboratory results, serum autoantibodies, sema 3A serum levels (measured by commercial ELISA kit) and expression on regulatory T cells CD 4+ CD 25 bright (by flow cytometry), nailfold videocapillaroscopy patterns, pulmonary function tests, echocardiograms, high resolution lung CT scans, modified Rodnan skin score (mRSS), Medsger disease severity scale and Valentini activity index. Sema 3A serum levels were also evaluated in 42 sex and age matched SLE patients (disease control) and 28 healthy controls. Results Twenty seven SSc patients (10 with diffuse cutaneous disease) were evaluated and compared with healthy controls and disease controls (SLE). Sema 3A expression in SSc patients was lower than healthy controls as measured by flow cytometry on regulatory T cells 61.7% ±15.7 vs. 88.7% ±3.6 (p