| Trichinella spiralis(T.spiralis)is a kind of multicellular parasites.The common characteristic and crucial method of helminth invasion and parasitism is inducing the severe immunosuppression,especially for T.spiralis.Epidemiological studies indicate that the helminth infection rate is low but the incidence rate of inflammatory bowel disease(IBD)is high in the developed country.Researchers proposed,studied and employed the “Helminth therapy” to treat IBD on this basis.The immunity mechanism of “Helminth therapy” is built on the influence of helminth infection on the intestinal tract immune system during the parasitism process,mainly by eliminating the immunologic injury caused by the Th1 type immune response,and regulating the Th2 type immune response.Extensive animal experiments have showed that T.spiralis and its products such as excrete secretory products(ESP),extracellular vesicles(EVs),recombinant protein such as serine protease inhibitor,cysteine protease inhibitor,53 k Da protein have showed the potential on the intervention of IBD,but the mechanism behind it needed to be illustrated.In this study,we choose the efficient antigenic element of T.spiralis-the serine protease gene from the newborn larval of T.spiralis.Prokaryotic expression by the expression vector which established by our lab before,and the endotoxin was removed.The effect of recombinant serine protease on 2,4,6-trinitro benzene sulfonic acid(TNBS)-induced experimental colitis model in mice and the mechanism behind it were explored.In this study,the Balb/c was immunized 3 times,100μg NBL-SP at an interval of7 days.And the experimental colitis was established by 100μL solution which consisting of 5% TNBS and absolute ethyl alcohol at a volumetric ratio of 1:1.100 μL50% ethanol solution was used in the control group.The experiment consists of the control group,NBL-SP group,TNBS group and NBL-SP+TNBS group.Comparing with the TNBS group,the disease activity index score(DAI)was decreased,the shorten of colon length was alleviated,macroscopic and microscopic score was decreased,MPO activity was weaken,the indexes above all indicate that the NBL-SP could alleviate the experimental colitis induced by TNBS.The cytokines of serum and cultural supernatant were measured by MSD and Elisa.The differentiation direction of T cells which were obtained from the spleen of mice was detected by the flow cytometry(FCM).The results show that the immune response induced by TNBS is mainly about Th1,and NBL-SP induced the Th2 and Treg immune response.Cytokine level of serum and colon culture supernatant and the differentiation of splenic T cells all show that the NBL-SP could intervene the Th1 immune response which induced by TNBS,decreasing the Th1 immune response.As the bridge that connects the innate and adaptive immune response,dendritic cells(DCs)are good at initiate na(?)ve T cells.DCs could control the T cells immune response directions,and inducing the na(?)ve T cells to differentiate into different kinds of effector T cells.To explore the mechanism that how the NBL-SP intervene the TNBS-induced IBD,the DCs were chosen as the study object,and the phenotype and function of DCs were studied.Lipopolysaccharide(LPS)is well accepted as the drug that could induce the DCs toward mature phenotype.The result of FCM and Elisa shows that NBL-SP can decrease the co-stimulatory molecules expression level of DCs that induced by LPS,making DCs differentiate toward “semi-mature”,enhancing the Th2 and Treg cytokines level of DCs cuture supernatant,and decreasing the Th1 cytokines level.The result of coincubation of DCs and T cells was consisitant with FCM and Elisa,the DCs stimulated by NBL-SP could induce T cells toward Th2 and Treg.The result above shows NBL-SP plays an intervention effect on the TNBS-induced experimental colitis.NBL-SP could interfere the differentiation directions of T cells,and DCs may play an important role on it. |
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