Immunomodulatory effects of 1,25 dihydroxyvitamin D3 in the treatment of experimental colitis

Objective To explore the immunomodulatory effects of 1,25-dihydroxyvitamin D3 (1,25 (OH)2D3) in the treatment of experimental colitis induced by dextran sulfate sodium (DSS) in mice.Methods According to random number table,thirty BALB/c mice were randomly divided into control group,model group,low dose,moderate dose,and high dose intervention group.Mice of model group,low dose,moderate dose and high dose intervention group drank 5％ DSS solution for seven days to create colitis model.On the 1st,3rd,5th,7th day,the mice of low dose,moderate dose and high dose intervention group were intraperitoneal injected with low,moderate,and high dose of 1,25(OH)2D3 (50,100 and 200 ng/each mouse,respectively).Mice of control group and model group were intraperitoneal injected with sterile soybean oil as control.The observed indicators included disease activity index (DAI) and colonic histopathological score (HPS).On the 8th day,all mice were sacrificed.The expression of interferon (IFN)-γ,interleukin (IL-17) and IL-21 in mice colon tissues and spleens at mRNA and protein level were measured by reverse transcription-polymerose chain reaction (RT-PCR) and flow cytometry,respectively.The data were analyzed by one way ANOVA.LSD-test or Tamhane test were performed for comparison in groups.Results Compared with the control group,the DAI and colitis HPS of mice in the model group significantly increased (0.33±0.52 vs 7.33±1.03,0.17±0.41 vs 12.00±0.63).Compared with the model group,the DAI and colonic HPS of intervention groups treated with 1,25 (OH)2 D3 declined with varying degrees (2.83 ± 0.40,2.83±0.75,2.33±0.52 and 10.83±0.98,7.50±0.84,6.67±0.52,LSD-t=0.39 and 0.41,all P＜0.01).The expression of IFN-γ,IL-17 and IL-21 of the model group were significantly higher than those of the control group.The expressions of IFN-γ,IL-17 and IL-21 of intervention group were signifiantly lower than that of the model group (mRNA:LSD-t =0.12,0.13,0.09; protein:F =20.61,22.46,4.80,all P＜0.01).Conclusion 1,25 (OH)2D3 might have a direct role on T-cell phenotype,down-regulate effective cytokines IFN-γ,IL-17 and IL-21 and then play an interventional role. Key words: Calcitriol;  Colitis;  Disease models, animal;  Interferon type Ⅱ;  Interleukin-17; Interleukins