益生菌对实验性结肠炎大鼠肠黏膜TLR2、TLR4表达及NF-κB活性的影响

摘要

Objective To detect the expression of TLR2,TLR4 and activation of NF-kB in colon mucosa in rats with DSS-induced colitis, and to investigate the mechanism of probiotics in ulcertive colitis. Methods Thirty male SD rats were divided randomly into three groups; normal control group (N) , model group (M) and probiotics group (P). Sub-acute colitis was induced with 5% DSS in drinking water for 10 d in group M and group P. After DSS exposure, the rats in group P were subjected to oral administration of bifido-bacterium solution (500 mg ?kg-1?d-1 ) for 2 weeks. In group M and group N, oral saline was administered. Disease activity index (DAI) and histopathological score (HPS) were observed. The expression of TLR2 and TLR4 in IECs were tested by RT-PCR. The activation of NF-kB in colon mucosa was further studied by immuno-histochemistry. Results DAI and HPS in group P were significant lower than those in group M. The expression of TLR2 and TLR4 in group M and P were increased markedly (P <0. 001 ) . Compared with the group M , expression of TLR2 was increased (P <0. 05) and expression of TLR4 was decreased (P < 0. 001 ) in group P. The activation of NF-kB in group M was increased significantly than those in group P and group N ( P < 0. 001 ) . There was no difference in the activation of NF-kB between group IN and group P ( P > 0. 05 ) . Conclusion The bifidobacterium (probiotics) may exert their effects in DSS induced UC by the expression of TLR2 , then inhibit the expression of TLR4 and the activation of NF-kB.%目的 通过检测益生菌对实验性结肠炎大鼠肠黏膜上皮细胞(IECs) Toll样受体(Toll Like recefor,TLR)、TLR4表达及肠黏膜核因子,kappa B活化的影响,探讨益生菌预防与辅助治疗溃疡性结肠炎的作用机制.方法 将30只雄性SD大鼠随机分为3组,即正常对照组(N)、模型组(M)、益生菌组(P).正常对照组正常饲养,不予任何处理；模型组给予含5％葡聚糖硫酸钠dextran sulfate sodium的饮用水10 d建立亚急性结肠炎模型,第11d开始常规饲养观察2周；益生菌组则在建立模型后给予双歧三联活菌500 mg.kg-1·d-1灌胃,1次/d,共2周；2周后处死所有大鼠,观察疾病活动指数(DAI),进行组织学评分(HPS)和分离ICEs并提取ICE中的总RNA,用RT-PCR法检测TLR2、TLR4的表达；采用免疫组织化学方法检测NF-κB的活性情况.结果 益生菌组的症状、组织损害程度均较模型组明显减轻；模型组和益生菌组TLR2和TLR4的表达均明显高于正常对照组(P＜ 0.001)；与模型组比较,益生菌组TLR2的表达增加(P＜0.05),而TLR4的表达则明显下降(P＜0.001)；模型组NF-κB活性明显高于益生菌组和正常对照组(P ＜0.001),益生菌组与正常对照组NF-κB活性比较差异无统计学意义(P＞0.05).结论 益生菌通过促使TLR2表达进一步增加,并可抑制TLR4的表达,进而控制NF-κB的活性,并在缓解肠道炎症中发挥作用.