Altered expression of regulatory molecules in the skin of psoriasis.

The presence of T regulatory cells (Tregs) is highly required in normal skin in order to maintain immune tolerance to commensal microbes and to prevent the development of immune-mediated inflammation. Psoriasis is a chronic inflammatory skin disease in which effector T cells, namely, Th17 and their relevant pro-inflammatory cytokines are increased in peripheral blood as well as in the inflamed skin. The status of Tregs in psoriatic skin is continuously studied. In this case, CD4 + CD25high T cells and other regulatory cytokines such as IL-35 are demonstrated to be significantly decreased. Aiming to better characterize Tregs in psoriatic skin and to establish the finding of their abnormal balance, we assessed the expression of semaphorin3A and neuropilin-1 (both reported as biomarkers of Tregs). Semaphorin3A and neuropilin-1 expressing Tregs were found to be significantly decreased in psoriatic skin when compared to normal skin. These findings were supported by demonstrating the downregulation of IL-10 expression in psoriatic skin. Our findings suggest that semaphoring3A may turn to be a new promising therapeutic approach in the process of improving Treg function in psoriasis.