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.