Semaphorin 3A - a marker for disease activity and a potential putative disease-modifying treatment in systemic lupus erythematosus.

Semaphorin 3A (sema3A) and neuropilin-1 (NP-1) play a regulatory role in immune responses and have a demonstrated effect on the course of collagen-induced arthritis. Sema3A was also found to be involved in other immune-mediated diseases, e.g. psoriasis and allergic rhinitis. In this review we concentrated on the involvement of sema3A and NP-1 in the pathogenesis of systemic lupus erythematosus (SLE) and on the specific effect of sema3A on the auto-reactive properties of B cells in SLE patients. We demonstrated the expression of sema3A in renal biopsies from lupus glomerulonephritis patients. This expression was found to be inversely correlated with proteinuria and kidney function tests. Sema3A serum levels in SLE patients were found to be significantly lower than in RA patients (disease control) and lower yet than in normal individuals. Altered serum sema3A levels were found to be in inverse correlation with SLE disease activity, mainly with renal damage and the presence of anti-cardiolipin antibodies. The expression of both sema3A and NP-1 on B cells from SLE patients was significantly different in comparison with normal healthy individuals. Finally, we demonstrated that when sema3A was co-cultured with CpG-ODN-stimulated memory B cells of SLE patients, their TLR-9 expression was significantly reduced by almost 50% (p = 0.001). These findings, along with the observation of sema3A being reduced in SLE patients in correlation with disease severity and autoimmunity, and memory B cells being beneficially responsive to sema3A, suggest this regulatory molecule may be considered as a potential therapy for SLE. Such focused therapies will help in achieving the maintenance of self-tolerance and alter pro-inflammatory status in lupus.