1,25-Dihydroxyvitamin D3 inhibits the differentiation and migration of T(H)17 cells to protect against experimental autoimmune encephalomyelitis.

Abstract

BackgroundVitamin D(3), the most physiologically relevant form of vitamin D, is an essential organic compound that has been shown to have a crucial effect on the immune responses. Vitamin D(3) ameliorates the onset of the experimental autoimmune encephalomyelitis (EAE); however, the direct effect of vitamin D(3) on T cells is largely unknown.Methodology/principal findingsIn an in vitro system using cells from mice, the active form of vitamin D(3) (1,25-dihydroxyvitamin D(3)) suppresses both interleukin (IL)-17-producing T cells (T(H)17) and regulatory T cells (Treg) differentiation via a vitamin D receptor signal. The ability of 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) to reduce the amount of IL-2 regulates the generation of Treg cells, but not T(H)17 cells. Under T(H)17-polarizing conditions, 1,25(OH)(2)D(3) helps to increase the numbers of IL-10-producing T cells, but 1,25(OH)(2)D(3)'s negative regulation of T(H)17 development is still defined in the IL-10(-/-) T cells. Although the STAT1 signal reciprocally affects the secretion of IL-10 and IL-17, 1,25(OH)(2)D(3) inhibits IL-17 production in STAT1(-/-) T cells. Most interestingly, 1,25(OH)(2)D(3) negatively regulates CCR6 expression which might be essential for T(H)17 cells to enter the central nervous system and initiate EAE.Conclusions/significanceOur present results in an experimental murine model suggest that 1,25(OH)(2)D(3) can directly regulate T cell differentiation and could be applied in preventive and therapeutic strategies for T(H)17-mediated autoimmune diseases.