大肠埃希氏菌在葡聚糖硫酸钠诱导的结肠炎恢复中的作用

目的: 随着对炎症性肠病(inflammatory bowel disease,IBD) 发病机制的深入研究, 肠道正常菌群与肠道炎症的密切关系日益受到重视。本研究旨在评价肠道大肠埃希氏菌( E.coli )对葡聚糖硫酸钠(dextran sulfate sodium,DSS) 诱导的小鼠结肠炎肠道黏膜的保护作用及其可能机制。方法: BALB/c 小鼠饮用含 3.5%DSS的饮用水 5 d, 诱导小鼠急性结肠炎, 模拟人类溃疡性结肠炎。 空白对照组饮用未添加 DSS的饮用水。饮用DSS的小鼠随机分为 3组, 分别给予不同的处理: (1) 单纯DSS 处理组; (2) 细菌耗竭小鼠(bacteria-depleted mice,BD小鼠)单纯DSS处理组; (3) 细菌耗竭小鼠大肠埃希氏菌处理组。从 4方面评价各组的处理反应: (1) 一般情况: 包括体重、疾病活动度(disease activity index, DAI)评分、结肠长度和重量; (2) 组织病理评分;(3) 化学比色法检测病变组织髓过氧化物酶(myeloperoxidase,MPO) 活性; (4) 免疫组织化学方法检测活化的核转录因子-κΒ(nuclear factor kappa B,NF-κB)。结果: 无E.coli处理的细菌耗竭小鼠难以从DSS诱导的肠炎中恢复。E.coli处理组和无E.coli处理组比较,大体评分、 组织病理评分和MPO活性明显改善(P<0.05)。E.coli处理组NF-κB活性显著高于无E.coli处理组 (均P<0.05)。结论: 肠道正常菌群是肠道炎症恢复的必需条件。大肠埃希氏菌能够促进小鼠DSS结肠炎的恢复;该作用与促进NF-κB的活化有关。

Escherichia coli promotes recovery from dextran sulfate sodium-induced colitis in mice

AIM: To investigate the important role of intestinal microflora in the pathogenesis of inflammatory bowel disease by studying the effects of E.coli on dextran sulfate sodium(DSS)-induced colitis in mice.METHODS: BALB/c mice were given 3.5% DSS in the drinking water for 5 days to induce acute colitis.The control mice(n=6) did not drink DSS water.The mice subject to drinking DSS were randomly divided into 3 groups:(1) simple DSS treatment group;(2) bacteria-depleted mice treated with DSS alone;(3) bacteria-depleted mice treated with DSS+E.coli.Four aspects of the treatment response were evaluated in each group:(1) general conditions,including body weight,disease activity index(DAI) score,colon length and weight;(2) histological score;(3) chemical colorimetric detection of myeloperoxidase(MPO) activity in the diseased tissues;(4) the activation of NF-κB detected by immune histochemistry.RESULTS: The bacteria-depleted mice that did not treat with E.coli were difficult to recover from DSS-induced colitis.Compared with non-treatment group,the general score,histological score and MPO activity in E.coli treatment group improved significantly(P<0.05).The activity of NF-κB in E.coli treatment group was significantly higher than that in non-E.coli treatment group(P<0.05).CONCLUSION: Intestinal microbiota is necessary during the recovery from DSS-induced colitis.E.coli promotes the recovery from DSS-induced colitis in mice.The mechanism may be associated with NF-κB activation.