Preventive effects of Schistosoma japonicum ova on trinitrobenzenesulfonic acid-induced colitis and bacterial translocation in mice

Aims: To evaluate the preventive effects of Schistosoma japonicum ova on trinitrobenzenesulfonic acid (TNBS)-induced colitis and bacterial translocation in mice. Methods: BALB/c mice were randomly divided into three groups: control group; TNBS+Ova- group; and TNBS+Ova+ group. Mice of the TNBS+Ova+ group were exposed to 10 000 freeze-killed S. japonicum ova by i.p. injection on day 1 and day 11. On day 15, mice were challenged with TNBS to induce colitis. The following variables were assessed: colon pathological changes; serum expression of tumor necrosis factor-alpha (TNF-alpha), gamma-interferon (IFN-gamma) and interleukin-10 (IL-10); expression of Toll-like receptor 4 (TLR4) in colon; IFN-gamma, IL-10 and TLR4 mRNA expression in colon; and the bacterial translocation rate. Results: Compared to TNBS+Ova- group, the colonic inflammation in the TNBS+Ova+ group were relieved. A highly significant elevation of IFN-gamma and TNF-alpha were observed in the TNBS-induced colitis group. After exposure to the eggs, IFN-gamma was significantly decreased, while TNF-alpha was similar to that of the TNBS+ova- group. No obvious variation was seen in IL-10 expression in TNBS-induced colitis, compared to the controls. Exposure to the eggs led to a significant upregulation of IL-10 expression. TLR4 expression was elevated after injected with TNBS and was downregulated in the eggs group. Less intestinal bacterial translocation frequency was observed when exposed to eggs. Conclusion: S. japonicum ova can prevent the TNBS-induced colitis and reduce the bacterial translocation frequency in mice. The mechanisms were supposed to be due to the regulation of T-helper cell 1/2 balance and TLR4 expression.