高脂饮食诱导高胆汁酸通过下调干细胞功能损伤肠黏膜

摘要

背景：高脂饮食可破坏肠道黏膜屏障功能，但机制未明。高脂饮食可诱导胆汁酸产生增加。目的：探讨高脂饮食诱导的高胆汁酸通过下调小肠干细胞功能损伤肠黏膜。方法：将24只大鼠分为3组，分别给予常规饮食、高脂饮食、高脂饮食+考来烯胺，连续2周。采用 ELISA 法测定血清胆汁酸浓度，测量小肠直径，行 HE 染色观察小肠黏膜组织学表现，以 RT-qPCR 检测 Lgr5基因表达。体外研究将常规饮食大鼠的回肠组织与脱氧胆酸（DCA）或 DCA+考来烯胺共培养24 h，以 RT-qPCR 检测 Lgr5基因表达。结果：与对照组相比，高脂饮食组血清胆汁酸浓度明显升高（P <0.05），肠管直径明显降低（P <0.05），肠道绒毛+隐窝长度明显降低（P <0.05），Lgr5基因表达明显降低（P <0.01）；给予考来烯胺后，上述指标均明显改善（P <0.05）。DCA 组 Lgr5基因表达显著降低（P <0.01），而考来烯胺可明显上调 Lgr5表达（P <0.05）。结论：高脂饮食引起的循环高胆汁酸通过下调小肠干细胞功能破坏肠道黏膜，而考来烯胺可改善此病理过程。%Background:High-fat diet leads to intestinal mucosa barrier dysfunction,but the mechanism is not clear. High-fat diet can induce increase of bile acid. Aims:To investigate whether the high bile acid induced by high-fat diet could act on intestinal stem cell to disrupt stem cell differentiation and imparing the intestinal mucosa. Methods:Twenty-four rats were divided into 3 groups:fed with regular diet,high-fat diet and high-fat diet + cholestyramine,respectively,for 2 weeks. Serum bile acid was detected by ELISA. Ileal diameter was measured and HE staining was performed to observe histology of intestinal mucosa. Expression of Lgr5 gene was determined by RT-qPCR. Ileal tissue fed with regular diet was cultured with deoxycholic acid(DCA)or DCA + cholestyramine for 24 hours in vitro,expression of Lgr5 gene was determined by RT-qPCR. Results:Compared with control group,serum bile acid was significantly increased(P < 0. 05),ileal diameter was significantly decreased,height of intestinal crypts and villus was significantly decreased(P < 0. 05),and expression of Lgr5 gene was significantly decreased in high-fat diet group(P < 0. 01). All the above-mentioned indices were significantly ameliorated in high-fat diet + cholestyramine group(P < 0. 05). In vitro study showed that expression of Lgr5 gene was significantly decreased in DCA group than in control group(P < 0. 01),and cholestyramine could significantly increase expression of Lgr5 gene(P < 0. 05). Conclusions:High-fat diet induced increasing of circulatory bile acid can cause injury of intestinal mucosa by inhibiting stem cell function,which can be ameliorated by cholestyramine.