Schistosome-derived Components Ameliorate Experimental Colitis In Vivo And Vitro

Objective: The present work aims to explore the potential therapeutic effect and the modulatory mechanism of soluble protein(SjSWP)and recombinant cystatin(rSjcystatin)of Schistosoma japonicum in Caco-2 cells and TNBS-induced colitis of mice that resembles inflammatory bowel diseases(IBDs).Methods: Twenty-four BALB/c female rats were divided into control group,TNBS group,rSjcystatin group and SjSWP group.Colitis in a murine model was induced by 2.5 % TNBS intrarectal perfusion.Mice were treated with 50 ?g S.japonicum-derived components through intraperitoneal injection after TNBS administration.The pathological and inflammatory parameters were estimated by measuring weight loss,disease activity index(DAI),colon length,myeloperoxidase(MPO)activity,macroscopic score(MAO),and microscopic score(MIO).Th1andTh2 cells were measured in spleens to determine the schistosome products-induced immune response.Simultaneously,T regulatory cells(Tregs)were monitored in spleens.Lipopolysaccharide(LPS)was used to stimulate macrophages for 6hr to generate proinflammatory macrophages,followed bythe co-culture with intestinal epithelial cells.In the experimental group,the macrophages were treated with rSjcystatin simultaneously.The differentiation related proteins of polarized macrophages were detected by Western blotting,and the apoptosis of intestinal epithelial cells was measuredby flow cytometry.The content of inflammatory cytokines in cell culture supernatants and colonic tissues were detected by ELISA.Results: After treatment with schistosome-derived molecules,the pathology and inflammatory parameters of colon in mice with colitis were significantly reduced,while the production of IL-4,IL-13 and IL-10 cytokines in colon tissue was relatively increased.Meanwhile,the number of Tregs cells in spleen was lifted from(8.22 ? 3.13)%to(18.40 ? 2.06)%(F=8.34,P<0.05).Furthermore,the data demonstrated that the therapeutic effect of rSjcystatin was similar to that of SjSWP in the mice of experimental colitis.After rSjcystatin was added to the experimental colitis model in vitro,the expression of iNOS related to M1 type inflammatory macrophages induced by LPS was decreased and the secretion of TNF-? cytokines was dampened from126.90 ? 13.81pg/mlto 57.15 ? 12.13pg/ml(F=11.39,P<0.01),while the expression of Arg-1 and IL-10 related to M2 macrophages was increased from 359.07 ? 59.50pg/ml to774.46 ? 71.13pg/ml(F=16.78,P<0.01).The apoptosis of co-cultured intestinal epithelial cells decreased from(11.65 ? 0.22)%inthe inflammatory group to(6.20 ? 0.29)% in the protective group(F=44.77,P<0.001).Conclusions: Schistosoma japonicum-derived components SjSWP and rSjcystatin may alleviate experimental colitis in mice via increasing Tregs and Th2 mediated responseand,suppressing Th1 dominant response which is responsible for the pathogenesis of colitis.Cystatin can reduce the apoptosis of intestinal epithelial cells in experimental enteropathy by inhibiting M1 type proinflammatory macrophages and partially promoting differentiation of M1 into M2 macrophages.