黄连解毒汤调节肠道L细胞GLP-2分泌预防糖尿病的作用及其机制

Intestine is the largest immune organ of human. Recently, abnormal intestinal bacteria and its related impairment of intestinal barrier have been proved to induce the infiltration of bacteria and its toxin into blood circulation, and therefore initiate chronic inflammation and insulin resistance. In our formal study, we found that the abnormal intestinal barrier also exists in OLETF rats, and moreover, the expression of GLP-2 which is responsible for the repair of intestinal barrier is decreased in OLETF rats. GLP-2 is secreted by intestinal L cells, and abnormal secretion of L cells has been proved in patients with pre-diabetes. We hypotheses the down expression of GLP-2 may play important roles in the occurrence of type 2 diabetes. In the later research, we will investigate the alteration of GLP-2 expression in the natural course of type 2 diabetes in OLETF rats, and explore the relationship among abnormal intestinal bacteria, GLP-2 down expression, impairment of intestinal barrier and chronic inflammation. We will then coculture the primary intestinal epithelial cell and intestinal endocrine cell with E. coli, and study the GLP-2 dependent mechanism of Huanglian Jiedutang on the proliferation of epithelial cell and the expression of occudin and ZO-1. At last, we will interfere pre-diabetic rats with traditional Chinese herb Huanglian Jiedutang to investigate its improvement on intestinal barrier, intestinal bacteria, GLP-2 expression and inflammation, and discuss the potential role of Huanglian Jiedutang in the prevention of type 2 diabetes and pre-diabetes.

肠道菌群紊乱导致的肠粘膜屏障受损可使肠道细菌及毒素入血，从而启动慢性非特异性炎症反应，参与胰岛素抵抗及2型糖尿病发生。黄连解毒汤是我国传统消炎抑菌方剂。我们前期发现黄连解毒汤可改善2型糖尿病大鼠肠粘膜屏障功能、改善胰岛素抵抗，并促进肠道L细胞分泌肠粘膜屏障修复蛋白胰高糖素样肽(GLP)-2；同时发现糖尿病前期已存在肠粘膜屏障受损及肠道L细胞功能紊乱。因此推测黄连解毒汤早期干预可能具有预防并治疗2型糖尿病的重要作用。本研究将首先引入肠道菌群宏基因组16S rDNA测序技术及肠内容物代谢组学技术，分析黄连解毒汤对糖尿病前期OLETF大鼠2型糖尿病的预防作用及对肠道菌群、肠道屏障功能、慢性炎症反应的调节作用；并建立原代小鼠肠上皮细胞及肠内分泌细胞共培养体系，体外研究黄连解毒汤对GLP-2分泌及上皮细胞间紧密连接蛋白表达的调节机制，为我国传统消炎抑菌方剂预防及早期干预2型糖尿病提供坚实的理论基础。

项目背景：肠道菌群紊乱导致的肠粘膜屏障受损可使肠道细菌及毒素入血，从而启动慢性非特异性炎症反应，参与胰岛素抵抗及2型糖尿病的发生。同时发现IGT患者肠道L细胞分泌的肠粘膜保护蛋白胰高糖素样肽(GLP)-2水平下降。黄连解毒汤是我国传统消炎抑菌方剂。我们前期发现黄连解毒汤可改善2型糖尿病大鼠肠粘膜屏障功能、改善胰岛素抵抗，并促进肠道L细胞分泌GLP-2；同时发现糖尿病前期已存在肠粘膜屏障受损及肠L细胞功能紊乱。.研究内容：观察IGT大鼠肠黏膜屏障、肠道菌群紊乱及LPS、GLP-1及GLP-2等指标变化；初步探讨肠道菌群紊乱在糖尿病大鼠GLP-2水平下降、肠粘膜屏障受损及2型糖尿病发生发展中的作用，并观察黄连解毒汤对IGT大鼠2型糖尿病的预防及其与肠道菌群紊乱及肠粘膜屏障破坏的改善作用。.重要结果：证实大鼠IGT时期已存在内毒素血症及除胰岛素外其他血糖调节激素的异常；且已出现肠道黏膜屏障受损、肠道菌群结构改变。揭示肠道L细胞GLP-2功能紊乱在启动2型糖尿病相关慢性炎症反应中的重要作用。揭示肠道菌群紊乱导致肠粘膜屏障受损在2型糖尿病发生发展中的重要作用。黄连解毒汤可一定程度上延缓IGT进展为2型糖尿病，其机制可能与改善胰岛功能、减轻胰岛素抵抗、减少肠道黏膜屏障损伤，改善肠道菌群结构等相关。 .科学意义：1. 高脂饮食环境下GLP-2水平下降与肠粘膜屏障受损有关，后者可能通过菌血症→慢性炎症→胰岛素抵抗而促进了糖尿病的发生。2.黄连解毒汤具有预防2型糖尿病的作用，这可能与黄连解毒汤改善肠道菌群、促进GLP-2分泌，进而改善肠黏膜屏障功能相关。