| IBD is a chronic relapsing inflammatory condition of the gastrointestinal tract that manifests as UC or CD. IBD is most common in highly industrialized country, but with the improving of standard of living and change of dietary, it is more common in our country. Because of the side effect of immunosuppressive and the recurrent attacks of IBD, exploring pathogenesis and new therapeutic tool are hot items. IBD occurs more commonly in societies where the prevalence of chronic enteric infestation is low. T. spiralis as a kind of immunomodulator prevent and cure IBD by adjusting colonic immunity will be investigated in this study. If the study succeed, it will offer a valuable theory and practice evidence for further research that hurtless T. spiralis our owning or purified effective antigen prevent and cure IBD, and consequently provide a kind of safe and effective immunomodulator for inflammatory bowel disease. Different from other researches, the colitis mice, experimentally established by TNBS and OXZ respectively, will be infected with T. spiralis, the effect for mice colitis prevention and treatment will be evaluated contrastively and the immunologic mechanism will be also investigated.TNBS or OXZ colitis without or with T. spiralis infection on days 3 and 7 post-induction of colitis was assessed using survival rate, DAI score, macroscopic damage and histological score, MPO activity assay, colonic and splenic cytokine IFN-γ, IL-4, IL-10, IL-12 mRNA production assay by RT-PCR. LPMC and spleen lymphocyte were cultured for 48h with anti-CD3, anti-CD28. IFN-γ, IL-4, IL-10, IL-12 levels were measured by enzyme-linked immunosorbent assay. The ratio of Th1/Th2 lymphocyte in spleen was detected by FCM with three color intracellular cytokine staining. The results of investigation on the efficacy and immunologic mechanism of T. spiralis intervening TNBS induced colitis were the following. Infection of mice with T. spiralis prior to TNBS treatment resulted in a significant increase in the survival rate, significant reduction in DAI score, macroscopic damage score, histological score, MPO activity compared to that in TNBS colitis without T. spiralis infection(p<0.05). This was accompanied by less mucosal damage, less thickening of the colonic wall, less gramulocyte infiltrate. Colonic mRNA and protein levels of IFN-γand IL-12 were significantly increased 3 days and 7 days 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 IL-12 mRNA and protein that seen in colitic mice spleen with prior nematode infection on days 3 and 7 and IFN-γmRNA on day 7 post-induction of colitis were significantly lower than that seen in colitic mice spleen without prior nematode infection(p<0.05). The levels of IL-4 and IL-10 mRNA, protein were significantly higher than that seen in colitic mice spleen without prior nematode infection(p<0.05). The levels of IFN-γmRNA and protein that seen in colitic mice spleen with prior nematode infection on day 3 post-induction of colitis had no significantly difference compared to that seen in colitic mice spleen without prior nematode infection(p>0.05). In spleen lymphocyte of colitic mice with prior nematode infection on days 3 and 7 post-induction of colitis, the percentage of Th1 were not significantly different from that seen in colitic mice without prior nematode infection(p>0.05). In spleen lymphocyte of colitic mice with prior nematode infection, the percentage of Th2 were not significantly different from that seen in colitic mice without prior nematode infection on day 3 post-induction of colitis(p>0.05), the percentage of Th2 were higher than which on day 7 post-induction of colitis(p<0.05). In spleen lymphocyte of colitic mice with prior nematode infection, the ratio of Th1/Th2 were not significantly different compared with that seen in colitic mice without prior nematode infection on day 3 post-induction of colitis(p>0.05), the ratio of Th1/Th2 was significantly lower than which on day 7 post-induction of colitis(p<0.05). The results of investigation on the efficacy and immunologic mechanism of T. spiralis intervening OXZ induced colitis were the following. Infection of mice with T. spiralis prior to OXZ treatment resulted in no significant difference in the survival rate, DAI score, macroscopic damage score, histological score, MPO activity compared to that in OXZ colitis without T. spiralis infection(p>0.05). This was accompanied by no improvement of mucosal damage, thickening of the colonic wall, gramulocyte infiltrate. The levels of IFN-γmRNA and protein that seen 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), as well as the levels of IL-4 and IL-10 mRNA on day 7 and IL-4 and IL-10 protein levels on days 3 and 7 post-induction of colitis(p<0.05). The levels of IL-4 and IL-10 mRNA were no significant difference compared with that seen in colitic mice colon without prior nematode infection on day 3 post-induction of colitis(p>0.05). The levels of IFN-γmRNA and protein that seen in colitic mice spleen with prior nematode infection on day 3 post-induction of colitis were significantly higher than that seen in colitic mice spleen without prior nematode infection(p<0.05), as well as the levels of IL-10 mRNA on day 3 post-induction of colitis(p<0.05).The levels of IL-4 mRNA and protein were no significant difference compared with that seen in colitic mice spleen without prior nematode infection(p>0.05), as well as the levels of IL-10 protein on day 3 post-induction of colitis(p>0.05). The levels of IFN-γ, IL-4, IL-10 mRNA and protein that seen in colitic mice spleen with prior nematode infection on days 3 and 7 post-induction of colitis were significantly higher than that seen in colitic mice spleen without prior nematode infection(p<0.05). In spleen lymphocyte of colitic mice with prior nematode infection on days 3 and 7 post-induction of colitis, the percentage of Th1 were significantly higher than that seen in colitic mice without prior nematode infection(p<0.05), the percentage of Th2 were not significantly different from which(p>0.05). In spleen lymphocyte of colitic mice with prior nematode infection on days 3 and 7 post-induction of colitis, the ratio of Th1/Th2 was significantly higher than that seen in colitic mice without prior nematode infection(p<0.05). Conclusions: Prior T. spiralis infection reduces the severity of TNBS-induced colitis. We interpret these findings to indicate that infection of mice with T. spiralis distractes the mucosal immune system response from a Th1 response toward a protective Th2 response with an attendant reduction in the severity of colonic damage and balance of Th1/Th2. Prior T. spiralis infection doesn't reduce the severity of OXZ-induced colitis, but without aggravating colitis. Prior T. spiralis infection in OXZ-induced colitis increases the ratio of Th1/Th2, which is a new drift presumedly in response to high doses of IL-10 induced by T. spiralis exposure. Proper doses of IL-10 can ameliorate inflammation, but high doses of IL-10 not only decreases the ability of regulating excessive dysregulated Th2 responses but also induces much proinflammatory cytokine, which resultes in a new drift of Th1/Th2 without aggravating Th2 responses. This phenomenon may be responsible for the lack of efficacy of T. spiralis in the treatment of OXZ-induced colitis and no corruption of inflammation. Athough, IL-10 is elevated in both TNBS and OXZ models with T. spiralis infection, because of different immunologic mechanism of two models, T. spiralis induce diverse doses of IL-10. These results indicate that if we can find the cause of inducing high doses of IL-10 and change it, or explore other mechanisms in future studies, T. spiralis will likely induce proper doses of IL-10 to result in efficacy on Th2 responses. So T. spiralis may have bidirectional immunomodulatory effects, which deserve to be explored deeply. |
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