丁酸梭菌通过HIF-1α调控肠道Tregs缓解1型糖尿病的作用及机制研究

The targeted migration of colon-primed regulatory T cells (Tregs) to pancreas protects against type 1 diabetes (T1D). Clostridium butyrate (CB) promotes the oxidation of butyrate to carbon dioxide (CO2), thereby rendering the epithelia hypoxia. Hypoxia inhibits dendritic cells (DCs) differentiation, maturation, stimulatory capacity for T-cell functions, as well as their homing to lymph nodes. However, how the gut-primed α4β7+Tregs migrate to the pancreas is unknown. Our previous studies have shown that: (1) pancreatic α4β7 (gut homing receptor)+Tregs are decreased in the female non-obese diabetic（NOD）mice compared to wild type and male NOD mice; (2) CB elevates hypoxia inducible factor 1α (HIF-1α), chemokine receptor 5 (CCR5), and promotes the targeted-migration of colon-primed Tregs to pancreas. These results suggest that CB may facilitate Tregs generation and promote the targeted-migration of colon-primed Tregs to pancreas by up-regulating colonic HIF-1α/CCR5 pathway. In the current project, with HIF-1 inducer/HIF-1 inhibitor in NOD, GPR41-/-, GPR43-/- and GPR109A-/- mice, we aim to further demonstrate: ①CB facilitates Tregs generation via HIF-1α; ②CB inhibits DCs differentiation, maturation, homing to lymph nodes and stimulatory capacity for T-cell functions via HIF-1α; ③the mechanisms that CB promotes the targeted-migration of colon-primed α4β7+Tregs to pancreas by up-regulating colonic HIF-1α/CCR5 pathway. Our study provides novel targets for intervening T1D.

肠道调节性T细胞（Tregs）向胰腺的迁移延缓1型糖尿病（T1D）发病；丁酸梭菌（CB）诱导结肠低氧，抑制树突状细胞（DCs）成熟、激活、迁移，从而诱导Tregs生成。然而，调控肠道来源的α4β7+Tregs向胰腺迁移的机制尚未阐明。已发现发病T1D天然模型鼠（NOD鼠）胰腺中α4β7+Tregs减少；CB上调结肠低氧诱导因子1α（HIF-1α）、趋化因子受体5（CCR5），促进α4β7+Tregs向胰腺迁移。本课题拟进一步采用短链脂肪酸受体G蛋白偶联受体41、43、109缺陷GPR41-/-、GPR43-/-、GPR109A-/-小鼠，结合HIF-1α诱导剂/抑制剂等，①明确CB通过HIF-1α促进结肠Tregs生成；②阐明CB通过HIF-1α调控DCs功能；③揭示CB通过HIF-1α/CCR5促进α4β7+Tregs向胰腺迁移的分子机制。本项目实施将为T1D防治提供新策略。

肠道调节性T细胞（Tregs）向胰腺的迁移延缓1型糖尿病（T1D）发病。我们的研究表明：（1）与野生型WT和雄性非肥胖糖尿病（NOD）小鼠相比，雌性NOD小鼠胰腺α4β7（肠道归巢受体) +Tregs减少；（2）丁酸梭菌上调低氧诱导因子lα、趋化因子受体5表达，促进结肠来源Tregs向胰腺的靶向迁移。丁酸是肠道丁酸梭菌的代谢产物。丁酸诱导宿主抗菌肽CRAMP表达。我们的研究表明丁酸梭菌、丁酸、CRAMP在T1D小鼠中表达减少。在NOD小鼠中，丁酸梭菌、丁酸、CRAMP给药均调节胰腺微环境中的的免疫细胞平衡和促炎性细胞因子、抗炎性细胞因子平衡，并抑制T1D的发生。本项目使用NOD，Cnlp-/-TID小鼠和细胞模型，分析研究丁酸梭菌、丁酸、CRAMP在调节T1D过程中对胰腺免疫细胞（Treg、DC、巨噬细胞）表型、信号通路、炎症因子、肠道免疫稳态的作用及分子机制。本项目有助于从肠道菌群和胰腺免疫细胞的角度了解TID发病机制，揭示丁酸梭菌、丁酸梭菌、CRAMP是直接调节胰腺免疫环境的关键分子，为干预TID提供新的靶点。