Effects Of Schistosome Japonicum Ova On Regulatory T Cells And Regulatory B Cells On TNBS-induced Colitis In Mice

Aims:To observe the possible effects of schistosome japonicum ova on regulatory T cells and regulatory B cells, and to explore the mechanism.Methods:Sixty BALB/c mice were randomly divided into four groups, control group (ctrl group, n=10), schistosome ova group(TNBS-OVA+ group, n=10), TNBS group(TNBS+OVA- group, n=20), TNBS plus schistosome ova group(TNBS+OVA+ group, n=20).Mice of TNBS-OVA+ and TNBS+OVA+ group were exposed to 15000 freeze-killed schistosome japonicum ova by intraperitoneal injection on day 9 and day2. At the same time, mice of ctrl and TNBS+OVA- group were exposed to 1ml NS by intraperitoneal injection. Each mice of the TNBS+OVA- and TNBS+OVA+ group was challenged with 3mg trinitrobenzesulfonic acid (TNBS) to induce colitis. All mice were killed 6 days later and assessed with following variables including mortality, morphology change of colon, the expression levels of regulatory T cells and regulatory B cells in the spleen.Results:(1) Compared with TNBS+OVA- group, the mortality of TNBS+OVA+ group is decreased, the mortality of TNBS+OVA- group is 35%, the mortality of TNBS+OVA+ group is 15%(P＜0.05). Compared with TNBS+OVA- group, the colonic inflammation of TNBS+OVA+ group is alleviated. (2) the expression levels of regulatory T cells in mice of TNBS-OVA+ group increased compared with that of the ctrl group (7.24±0.14% vs 5.53±2.29%, P＜0.05); the expression levels of regulatory T cells in mice of TNBS+OVA+ group increased compared with that of the TNBS+OVA-group (6.56±3.79% vs 4.91±0.94%, P＜0.05). (3) the expression levels of IL-10+ cells in mice of TNBS-OVA+ group decreased compared with that of the ctrl group (21.07±5.86% vs 73.64±7.40%, P＜0.05); the expression levels of IL-10+ cells in mice of TNBS+OVA+ group decreased compared with that of the TNBS+OVA- group (9.21±1.47% vs 74.19±9.87%, P＜0.05). the expression levels of IL-10+ regulatory B cells in mice of TNBS-OVA+ group decreased compared with that of the ctrl group (21.03±5.45% vs 44.16±3.48%, P＜0.05); the expression levels of IL-10+ regulatory B cells in mice of TNBS+OVA+ group decreased compared with that of the TNBS+OVA- group (8.69±1.54% vs 40.55±4.07%, P＜0.05). (4) the expression levels of TGF-β+ cells has a remarkable reduction in the TNBS-OVA+ group compared with that of the ctrl group (60.71±12.64% vs 96.95±1.34%, P＜0.05); Eggs exsposure also downregulated the number of TGF-β+ cells in TNBS-induced moderls (97.57±0.97% vs 68.59±9.90%, P＜0.05). the number of TGF-β+ regulatory B cells has a remarkable reduction in the TNBS-OVA+ group compared with the ctrl group (16.81±3.28% vs 43.68±2.83%, P＜0.05); the expressions levels of TGF-β+ regulatory B cells in mice of TNBS+OVA+ group decreased compared with that of the TNBS+OVA- group (7.24±5.0% vs 48.41±3.98%, P＜0.05).Conclusion:(1) Schistosome japonicum ova can promote regulatory T cells, thereby relieve the severity of inflammatory bowel disease.(2) Whether the schistosome japonicum ova relieved the experimental colitis throug IL-10+ Breg cells and TGF-β+ Breg cells stimuli can not be confirmed in the present study.