The deviated balance between regulatory T cell and Th17 in autoimmunity.

Identifying the regulatory T cells (Tregs) and Th17 cells led to breaking the dichotomy of Th1/Th2 cells axis in immune responses involved in several autoimmune diseases. It is now well known that Tregs and Th17 cells are main orchestra leaders in pathogenesis symphony of autoimmunity. While Tregs are protective cells in autoimmune diseases, Th17 cells enhance the progression of autoimmune responses through induction of various pro-inflammatory reactions. It seems that the progression of autoimmunity may be associated with increase in Th17 and decrease in Treg levels, so that skewed balance between Tregs and Th17 toward Th17 is a phenomenon, which could be observed during progression of several autoimmune diseases. Although it is suggested that expansion and transfer of Tregs can be a new therapeutic target for autoimmune diseases, however, recent data about the phenotype conversion of Tregs into Th17 cells obligate us to more investigation on this approaching. Thus, identifying the new factors that induce stable phenotype in Tregs and prevent their phenotype conversion into Th17 cells as well as targeting the factor, which can modulate their balance, might be recommended as a new promising therapeutic method for autoimmune therapy. In this review, we try to clarify the factors, which can affect on this balance in various autoimmune diseases, as new targets in treatment of these diseases.