ABSTRACT
Objective To study the levels of Th1 and Th2 type cytokines in 3-nitrobenzene sulfonate(TNBS) and oxazolone(OXZ) colitis without or with Trichinella spiralis( T. spiralis) infection. Methods Female BALB/c mice were randomly divided into 4 groups: 50% Ethanol, T. spiralis only, TNBS or OXZ,T. spiralis +TNBS or OXZ(at least 6 in each group when mice were killed). The levels of IFN-γ, IL-12,IL-4, IL-10 in colon in mice with colitis induced by TNBS or OXZ without or with T. spiralis infection 3 d and 7 d post-induction were assessed using ELISA method. Results Colonic protein levels of IFN-γand IL-12 were significantly increased 3 d and 7 d after intra-colonic injection of TNBS( P ＜0.05 ). Concurrent infection with T. spiralis prevented this rise in IFN-γand IL-12 secretion and tended to induce a rise in colonic IL-4 and IL-10 content(P ＜0. 05). The levels of IFN-γ, IL-4 and IL-10 protein in colitic mice colon with prior nematode infection on days 3 and 7 post-induction of colitis were significantly higher than that seen in colitic mice without prior nematode infection ( P ＜ 0.05 ). Conclusion T. spiralis infection significantly attenuates TNBS-induced colitis in mice. The local immunologic mechanism is that T. spiralis can down-regulate strongly Th1-type immune response of colitis and up-regulate Th2 response, Tr1-cytokines. According to the change of Th1/Th2 cytokines, prior T. spiralis infection doesn't reduce the severity of OXZ-induced colitis, but without aggravating colitis. The exactly immunologic mechanism deserve to be explored deeply.