丙酮酸乙酯对TNBS结肠炎小鼠HMGB1及Th17细胞反应的影响

Effect of ethyl pyruvate on HMGB1 expression and Th17 response in TNBS-induced colitis mice

目的探讨高迁移率族蛋白1(HMGB1)的抑制剂丙酮酸乙酯(EP)对实验性结肠炎小鼠模型的治疗机制。方法 30只BALB/c小鼠随机分为乙醇对照组、模型组和EP组,利用2,4,6-三硝基苯磺酸(TNBS)建立小鼠结肠炎模型,EP组每天按100 mg/kg腹腔注射EP溶液1次,连续6 d。造模后每天进行疾病活动指数(DAI)评分;实验第7天处死小鼠,观察结肠组织病理学改变;ELISA法检测血清和结肠组织中HMGB1、IL-17的表达水平;流式细胞术检测脾脏、肠系膜淋巴结中Th17细胞比例变化。结果与模型组比较,EP组DAI评分下降,镜下组织病理损伤亦明显减轻(P<0.01),EP组小鼠血清和结肠组织中HMGB1水平明显降低,伴随血清及结肠局部IL-17表达减少(P<0.01),同时脾脏和肠系膜淋巴结Th17细胞比例亦明显降低(P<0.01)。结论 EP可能通过阻断内源性免疫刺激剂HMGB1的释放,进而间接抑制Th17细胞及其介导的炎症瀑布反应,从而对IBD小鼠发挥保护作用。

Objective To investigate the therapeutic mechanism of ethyl pyruvate （EP）, the inhibitor of high mobility group box 1 （HMGB1）, on experimental colitis model in mice. Methods 30 BALB/c mice were randomly divided into 3 groups： Ethanol Control Group, Model Group and EP Group. Trinitro-benzene sulfonic acid （TNBS） was used to establish colitis model of mice. EP Group received treatment with intraperitoneal injection of 100 mg/kg EP solution for 6 consecutive days, qd. After model construction, the disease activity index （DAI） was evaluated every day; The mice were sacrificed on the 7th day, and pathological changes of colon tissue were observed; The serum and colonic expression of HMGB1 and IL-1.7 were determined by ELISA. The percentages of Th17 cells in spleen and mesenteric lymph nodes （MLN） were detected by flow cytometry （FCM）. Results Compared with Model Group, DAI score in EP Group was reduced and histopathological damage in colon was significantly reduced in EP Group （P〈0.01）. The expression of HMGB1 in serum and in colon in EP Group was significantly reduced （P〈0.01）, and the IL-17 levels in serum and in colon were also reduced （P〈0.01）. Meanwhile, the percentage of Th17 cells in the spleen and MLN were also decreased （P〈0.01）. Conclusion EP may indirectly inhibit Th17 cells and Th17 mediated inflammatory cascade through blocking the release of HMGB 1, and thus play a protective role for IBD mice.