肠道DCs在肠道菌群失调诱发T2DM中的作用及机制研究

Intestinal DCs play a central role in maintaining intestinal immune homeostasis and regulating intestinal immune responses. However, the role and mechanism of intestinal DCs in modulating the occurrence and development of T2DM remains to be investigated. Based on our previous study that DCs related to the improvement of glycolipid metabolism and the amelioration of inflammation in insulin-resistant mice, we intend to explore how intestinal DCs regulate the progression of T2DM. At different stages of T2DM, gut microbiota and metabolites will be detected by metagenomic sequencing and metabolomics technologies, the functions of intestinal DCs will be analyzed, and the candidate microbiota and metabolites tuning intestinal DCs functions will be determined. Then, the critical role of intestinal DCs in intestinal dysbiosis-induced T2DM is to be confirmed using CD11c-DTR mice, and adoptive transfer of DCs and fecal microbiota transplantation experiments. The key genes regulating the functions of intestinal DCs will be identified by microarray and CRISPR/Cas9 methods. Finally, the relationship among gut microbiota, intestinal DCs, and T2DM will be clarified, which will provide new theoretical basis and scientific evidence for the maintenance of intestinal homeostasis and the prevention and treatment of T2DM.

肠道DCs在维持肠道免疫稳态和调节肠道免疫应答中发挥重要作用，但其在肠道菌群紊乱诱发T2DM过程中的作用及机制尚不清楚。因此，本课题在DCs与胰岛素抵抗小鼠糖脂代谢改善和炎症减轻有关的前期研究基础上，围绕肠道DCs如何调控T2DM发生发展的科学问题，利用宏基因组测序和代谢组学技术检测T2DM不同发病阶段的肠道菌群和代谢产物，同时动态检测肠道DCs的功能，确定调节肠道DCs功能的候选菌群及代谢产物并明确其作用方式。然后，采用CD11c-DTR小鼠和过继转移DCs及粪菌移植实验，明确DCs在肠道菌群紊乱诱发T2DM过程中的关键作用；利用Microarray和CRISPR/Cas9方法，确定调控肠道DCs功能的关键基因。最终，阐明肠道菌群-肠道DCs-T2DM之间的内在联系，为维持肠道内环境稳态及防治T2DM提供新的理论基础和科学依据。

肠道菌群紊乱可促进肥胖、胰岛素抵抗、2型糖尿病等代谢性疾病的发生发展，而且树突状细胞（DCs）是连接天然免疫和获得性免疫的桥梁，在维持机体免疫稳态、调控糖尿病发展中发挥重要作用。我们研究发现T2DM发病中DCs向成熟方向分化，脂质合成增加，免疫原性增强；肠道致病菌和致病代谢物增多，有益菌和有益代谢物减少，共同作用加速T2DM发展。确定了DCs上关键分子FXR激活后增强PPARγ活性、减弱p38MAPK磷酸化，进而抑制DCs成熟及脂质合成，减少炎性细胞因子分泌，减弱其免疫原性。FXR活化还可重塑肠道菌群和代谢物组成，减轻胰岛素抵抗和高胰岛素血症，改善糖脂代谢及机体炎症，发挥有效的抗糖尿病作用。我们还发现中药小檗碱和水苏糖联用可改善肠道微生物和代谢物组成，抑制DCs成熟，减轻炎症，维持糖脂代谢稳态，抑制T2DM发展。此外，我们研究发现原创抗糖尿病药物桑枝总生物碱可通过抑制MAPK信号通路发挥抗炎作用，完善了其抗炎和抗T2DM机制。该研究确定了DCs、肠道微生物和代谢物在T2DM进程中的重要作用及调控DCs功能的关键分子，丰富了DCs介导T2DM发生发展的的作用及机制，强化了FXR作为抗糖尿病药物靶点的理论基础，为挖掘FXR治疗T2DM的新机制和新途径提供了参考，为T2DM防治提供了新策略。