Objective To study the effects of Trichinella spiralis (T.spiralis) infection on mice with oxazolone (OXZ)-induced colitis and the possible immunologic mechanism.Methods Female BALB/c mice at age 6-8 weeks were randomly divided into four groups (A to D).Each mouse in groups B and D was infected with T.spiralis strains.Twenty-one days after T.spiralis infection,the mice in groups A and B were treated with 50％ ethanol solution,while those in groups C and D were treated with OXZ to induce the murine model of colitis.Several parameters including survival rate,disease activity index (DAI),macroscopic damage and histological score,myeloperoxidase (MPO) activity and the expression of cytokines (IFN-γ,IL-4 and IL-10) in colonic and splenic tissues at mRNA and protein levels were measured 3 and 7 days after modeling.Results No significant differences in the survival rate,DAI score,macroscopic damage score,histological score,MPO activity were observed between mice from groups C and D (P＞0.05).Pre-exposing the mice to T.spiralis strains neither alleviated the mucosal damages nor aggravated the condition of colitis.Compared with group C,the expression of IFN-γ on the third day and the expression of IFN-γ,IL-4 and IL-10 on the seventh day at mRNA and protein levels in colon and spleen tissues were significantly increased in mice treated with T.spiralis and OXZ (P＜0.05).The expression of IL-10 at transcriptional level in spleen tissues on the third day was higher than that of group C (P＜0.05).The expression of IL-4 and IL-10 at protein level in colon tissues on the third day were significantly up-regulated as compared with those of group C (P＜0.05).Conclusion The severity of OXZ-induced colitis in the murine model was neither alleviated nor aggravated by pre-exposing the mice to T.spiralis strains.High doses of IL-10 not only weakened the regulatory effects on Th2 responses,but also induced the production of proinflammatory cytokines,resulting in a new drift of Th1/Th2 without aggravating Th2 responses.Further investigation on the mechanism of T.spiralis-induced over-expression of IL-10 should be conducted,which might increase the practicability of using T.spiralis strains against OXZ-induced colitis.