1,25(OH)2D3 Protects Liver Fibrosis Through Decreasing the Generation of TH17 Cells.

BACKGROUND The aim of this study was to study the effects of 1-alpha,25-dihydroxy-cholecalcifero (1,25(OH)2D3) on liver fibrosis and the generation of Th17 cells in vivo and in vitro. MATERIAL AND METHODS Thirty C57 mice were randomly divided into control, model, and treatment groups. Hepatic fibrosis was induced by subcutaneous injection of CCl4. Liver fibrosis condition was evaluated through pathological inspection and blood biochemical examination of liver function. Immunohistochemical assays were used to detect the expression of α-SMA, TGF-β, and collagen I to observe hepatic stellate cell activation level. Flow cytometry, ELISA, and RT-PCR were performed to explore the association between 1,25(OH)2D3 and Th17 cell differentiation. RESULTS Collagen I, TGF-β, and α-SMA were decreased after 1,25(OH)2D3 treatment. Consistently, RORγt mRNA and the rate of Th17 cells was significantly reduced after 1,25(OH)2D3 treatment. In vitro, the proportion of Th17 cells was also obviously reduced in the 1,25(OH)2D3 group, and mRNA levels of IL-17A, IL-22, RORγt, and RORa were significantly decrease in the 1,25(OH)2D3 group compared to the control group. CONCLUSIONS Treatment with 1,25(OH)2D3 can alleviate the damage caused by liver fibrosis. Experiments in vivo and in vitro showed that 1,25(OH)2D3 treatment deceased the rates of Th1 and Th17 cells and increased the rate of Th2 cells. The level of IL-17A, IL-22 and IFN-γ were decreased, while the level of IL-4 was increased by the treatment of 1,25(OH)2D3.