【作者】 胡刚正；

【导师】 郑长青；

【作者基本信息】 中国医科大学 ， 内科学， 2004， 硕士

【摘要】 目的 炎症性肠病表现为一种慢性非特异性胃肠道炎症，包括Crohn病和溃疡性结肠炎，我国的近年发病率呈上升趋势。其病因尚不很清楚，由易感个体免疫系统对自体的某些肠道抗原失耐受而诱发的慢性持续免疫反应是目前较公认的发病机制。关于IBD免疫失耐受中抗原与易感性的研究，目前国外主要集中在寻找其易感体质的遗传基础及特异的致病抗原，而在动物实验中直接研究不同抗原的接触方式及相互作用能否影响实验性结肠炎发病的文献尚没有。本试验利用能促进不同Th1/Th2极化的半抗原TNBS和恶唑酮，通过观察不同抗原接触方案所诱发的结肠炎症程度并检测血清细胞因子浓度来分析结肠炎发病是否与不同抗原的接触方式及相互作用相关，及其与Th1/Th2/Th3平衡的关系。 材料和方法 SPF级BALB/c小鼠随机分为4组，分别用不同的抗原接触方案诱导结肠炎，A组；先10mg TNBS两次灌胃，1周后1mg TNBS灌肠；B组：直接1mg TNBS灌肠；C组：1mg恶唑酮和1mg TNBS同时灌肠；D组：先1mg恶唑酮灌肠，1周后1mgTNBS灌肠。各组小鼠均在末次灌肠后第7天处死，观察和评价临床表现(症状，体重)及结肠炎的程度(肉眼及组织学分级)，并检测INF-γ，IL-10和IL-4的血清浓度。 结果 1．10mg TNBS灌胃能诱导口服耐受 10mg TNBS两次灌胃再灌肠的小鼠(A组)与直接灌肠(B组)小鼠相比，临床表现和结肠炎明显较轻。B组体重下降明显而恢复较慢，A组体重仅短暂而轻微地下降。A组小鼠远端6cm结肠重量较B组轻，宏观分级和组织学分级得分均较低。 2．Oxazolone与TNBS在诱导试验性结肠炎中相互作用1mg TNBS与1mg Oxazolone同时灌肠(C组)与单纯1mg TNBS灌肠(B组)比较，临床和结肠炎症表现无差异。1 mg Oxazolone灌肠1星期后再TNBS灌肠组(D组)与B组比较，体重下降较小，远端6cm结肠重量较轻，宏观分级得分较低，但组织学分级差别无统计学意义。 3.血清细胞因子浓度变化血清INF一丫浓度在B、C和D组处于同一较高水平，而在A组显著下降。IL一10浓度在A组显著升高，而在B、C和D组中均很低。IL4在A组中升高，而在其他各组中均达不到检测浓度。结论 尽管半抗原TNBS和恶哇酮灌肠均能诱导结肠炎，但先用恶哇酮灌肠能够改善TNBS诱发的临床症状，同时灌肠也不使症状加重，说明此两种抗原在诱导结肠炎中存在拮抗作用，而这种对抗作用可能并非通过Thl厂rhZ平衡来实现;TNBS预先灌胃可诱导口服耐受，其机制可能主要通过调节Thl/Th3平衡。在炎症性肠病发病的环境因素中，各种抗原的相互作用及接触方式(途径、先后顺序、次数和剂量等)可能扮演重要角色，这些机制可望用于炎症性肠病的防治。更多还原

【Abstract】 Exposure procedure and interaction of various intestinal antigen, as well as the individual susceptibility and pathogenic specificity of antigen, may be partly responsible for the loss of immune tolerance contributing to IBD. To veriiy the hypothesis, the study was conducted to observe whether the different exposure route of haptin TNBS and the interaction with Oxazolone influence induction of experimental colitis, and the relationship with Thl/Th2/Th3 balance.MethodsFor induction of colitis by different exposure procedure of haptins, SPF BALB/c mice were randomly divided into 4 groups. Group A: gavages of lOmg TNBS on days 1 and 8, then enema of 1 mg TNBS one week later. Group B: mere enema of lmg TNBS. Group C; simultaneous enema of lmg TNBS and lmg Oxazolone. Group D: enema of lmg Oxazolone, then enema of lmg TNBS one week later. All mice were sacrificed 7 days after colitis induction by the last enema of TNBS. Colitis was assessed according to clinical and histological parameters. The serum concentrations of IL-10, IL-4 and INF-Twere measured.ResultsCompared with group B or group C, mice in group A manifested significantly ameliorated inflammatory response according to clinical or histological assessment and an increase in EL-10 and a decrease in INF-rserum levels. Clinical response (symptoms and weight loss) in group D was significantly reduced, but the histological grading and serum concentrations of IL-10, IL-4 and INF--yshowed no differences among group B, group C and group D.ConclusionsThe two haptins have mutual antagonistic effect in the pathogenesis of experimental colitis. But it seems not to be related to the Thl/Th2 balance. Feeding of TNBS can induce oral tolerance and prevent colitis caused by enema. The mechanisms may involve in Thl/Th3 balance. In summary, exposure procedure and interaction (route, chronological order, frequency and dosage) of various antigen may be an important part of the environmental factors that contribute to the pathogenesis of inflammatory bowel disease.更多还原