基于肠组织缺氧与神经酰胺的肝代谢毒性探讨辛开苦降法降糖调脂作用的局部机制

Representative prescription of Xinkai-kujiang method, Banxia Xiexin decoction, is famous for its unique compatibility and remarkable curative effect in the treatment of type 2 diabetes, but its compatibility and mechanism are not completely clear. Recent studies have shown that hypoxia arises in the intestine exposed to high-fat diet, and that intestinal ceramide production increases through the HIF2α/Neu3/ceramide signaling pathway, leading to metabolic inflammation and insulin resistance in liver. Berberine, a bitter monomer, is recognized to be hypoglycemic and lipid-lowering, and its effect mechanism was related to HIFα and ceramide. On the basis of our previous studies, this project proposes that regulating the intestinal HIF2α/Neu3/ceramide pathway to reduce the production of lipotoxic ceramide and improve the liver metabolism might be the hypoglycemic and lipid-lowering mechanism of Banxia Xiexin decoction; besides, the combination of Xinkai-kujiang-ganhuan method is superior to those by disassembly. To testify this hypothesis, the techniques of lipidomics, serum pharmacology and siRNA interference will be employed. Then, the hypoglycemic and lipid-lowering effects of combination and disassembly of Xinkai-kujiang-ganhuan method will be compared, their regulatory effects on intestinal hypoxia and ceramide production will be explored, and the intestinal mechanism of Banxia Xiexin decoction in the treatment of type 2 diabetes mellitus will be elucidated.

辛开苦降法代表方半夏泻心汤治疗2型糖尿病以其配伍独特、疗效显著而闻名，但其配伍优势及作用机制尚不完全清楚。近来研究表明，高脂饮食下肠组织缺氧，并通过HIF2α/Neu3/ceramide信号通路导致肠源性神经酰胺产生增加，促发代谢性炎症和肝胰岛素抵抗。苦味药单体小檗碱被公认可降糖调脂，且作用机制可能与HIFα、神经酰胺等有关。本项目在前期研究基础上，提出“调控肠道HIF2α/Neu3/ceramide通路、降低脂毒性神经酰胺产生、改善肝脏代谢，可能是半夏泻心汤降糖调脂作用的局部机制；辛开苦降甘缓法配伍，可能作用环节有别，但协同整合全方更优”的假说。通过高糖高脂饮食诱导小鼠2型糖尿病模型，结合离体实验，运用脂质组学、血清药理学、siRNA干扰等技术，比较辛开苦降甘缓三法拆方与合方改善糖脂代谢紊乱的效应，探讨其对肠组织缺氧与神经酰胺产生的调节作用，阐明半夏泻心汤治疗2型糖尿病的肠道机制。

辛开苦降法代表方半夏泻心汤改善2型糖尿病（T2DM）、非酒精性脂肪性肝病（NAFLD）和肥胖等代谢性疾病疗效显著，然而半夏泻心汤改善糖脂代谢紊乱的机制尚不完全清楚。近来研究表明缺氧诱导脂毒性神经酰胺产生，影响机体糖脂代谢，是胰岛素抵抗的重要发病机制。本课题探究了T2DM发生发展过程中，缺氧、神经酰胺代谢、胰岛素抵抗之间的联系，并致力于阐明辛开苦降法代表方半夏泻心汤拆方和合方对糖脂代谢的影响及其潜在的分子机制。在高脂饮食诱导小鼠糖脂紊乱进程中，肝脏HIF-2α累积导致肝脏缺氧和神经酰胺含量增加，诱导胰岛素抵抗发生。辛开苦降法代表方半夏泻心汤改善肝脏胰岛素抵抗及脂质沉积的效果优于辛开、苦降、甘缓药性拆方。肝脏转录组学及免疫印迹数据显示，半夏泻心汤抑制高脂饮食诱导的小鼠肝脏CIDEc的表达，改善肝脏胰岛素抵抗和脂肪变性。经液相色谱鉴定半夏泻心汤的单体成分，结合分子对接显示HIF-2α与小檗碱较高的亲和力，本研究继续评估了小檗碱在HIF-2α-神经酰胺-胰岛素抵抗发病环节中的药理学作用。动物模型脂质组学结果显示小檗碱降低缺氧诱导的神经酰胺产生，并通过PP2A-AKT-GSK3β信号通路缓解了神经酰胺诱导的胰岛素抵抗。这些研究结果为阐明神经酰胺在肝脏缺氧和胰岛素抵抗中的作用提供了及时必要的证据，同时为半夏泻心汤及其有效成分小檗碱改善T2DM和NAFLD提供了扎实的药理学基础。