基于HNF1b/DPP4/NOX1通路探讨苓桂术甘汤治疗非酒精性脂肪性肝病的分子机制研究

Insulin resistance plays a key role in the mechanism of NAFLD. There is no specific drug in western medicine. As a classical Chinese herbal formula, Linggui Zhugan decoction (LGZG) is widely prescribed to treat NAFLD in clinical practice with significant effect. However, the exact molecular mechanism is unclear by far. Previous studies have shown that HNF1b can decrease the generation of superoxide mediated by DPP4 /NOX1 pathway through negative regulation. Therefore it plays an important role in controlling the steady state of triglyceride in liver and enhancing insulin sensitivity. HNF1b knockout can increase lipid content in the mouse liver and induce insulin resistance. HNF1b high-expression can reduce liver lipid content in high-fat-diet-induced mouse model and reduce insulin resistance. In clinic, we also find that LGZG can improve insulin resistance and lower lipid profile. Based on these studies, we propose the hypothesis that LGZG can reverse insulin resistance and ease NAFLD through HNF1b/DPP4/NOX1 pathway. The expected results can help us to illustrate the mechanisim of LGZG decoction and provide a new treatment for preventing and controlling NAFLD by traditional Chinese medicine.

胰岛素抵抗在非酒精性脂肪性肝病（non-alcoholic fatty liver disease, NAFLD）中扮演关键角色，西医对本病尚无特效药物。苓桂术甘汤作为传统经方在临床上被广泛应用于NAFLD的治疗中，疗效显著，但确切分子机制不明。前期研究发现肝细胞核因子1b（HNF1b）通过负调控DPP4/NOX1介导的超氧化物的产生，在控制肝脏甘油三酯稳态和胰岛素敏感性方面发挥重要作用。HNF1b的敲除增加了小鼠和肝细胞中的肝脏脂质含量以及诱导胰岛素抵抗。HNF1b高表达能够减轻高脂饮食小鼠的肝脏脂质含量以及减轻胰岛素抵抗。我们在临床上也发现苓桂术甘汤能够显著改善NAFLD患者胰岛素抵抗，降低血脂水平。基于此我们提出假说：苓桂术甘汤通过调控HNF1b/DPP4/NOX1通路逆转胰岛素抵抗，缓解NAFLD。预期结果将为阐明苓桂术甘汤作用机制，为非酒精性脂肪性肝病的中医药治疗提供新的思路。

非酒精性脂肪性肝病（NAFLD）已成为当今最常见的慢性肝病之一。当前西医尚无治疗NAFLD的特效药。而中医根据患者的病因病机，辨证论治选取中药汤剂、中成药等策略治疗本病，具有显著的疗效优势。 苓桂术甘汤（LGZG）是经典名方，切合NAFLD中医辨证，治疗NAFLD临床疗效显著。尽管既往有多个研究分析了LGZG对肝脏病理、糖脂代谢相关信号通路机制的影响，但由于其成分复杂，可能存在多重靶点，因而LGZG治疗NAFLD的药效机制仍值得进一步挖掘和完善。我们的结果表明：LGZG 可明显改善高脂饮食引起的小鼠小鼠葡萄糖和胰岛素耐受，降低小鼠空腹血糖，改善小鼠肝脏炎症及脂肪沉积，减轻HFD-C57小鼠NAFLD 症状。LGZG 干预后能够显著升高肝脏HNF1b 的表达。但是免疫组化结果提示：其对DPP4/NOX1 的表达影响不明显。另一方面，炎症是导致非酒精性脂肪性肝病（NAFLD）进展的关键因素之一，改善肝脏炎症可显著减缓NAFLD进展。与炎症密切相关的干扰素基因刺激蛋白（STING）在NAFLD小鼠模型肝脏巨噬细胞（kupffer 细胞）中高表达；kupffer 细胞中STING-TBK1-NF-κB通路激活导致的炎症反应是促进NAFLD进展的重要途径。这些进展提示：STING相关通路在kupffer细胞诱导的炎症中扮演关键角色，可作为潜在的NAFLD治疗靶标。我们的结果提示，LGZG可以显著降低HFD诱导的肝脏巨噬细胞浸润和STING的表达。LGZG 还可以通过抑制Kupffer 细胞中STINGTBK1-NF-κB 信号通路，降低TNFα、IFNβ 等炎症因子的释放，减轻肝脏炎症水平，从而减轻HFD 导致的肝细胞脂肪沉积，减缓NAFLD 的进展。这些结果表明多条信号通路可能参与LGZG 治疗NAFLD 的机制当中。同时也说明了LGZG 和其他传统中药一样，存在多靶点，多种机制协同作用。本研究为阐明LGZG治疗NAFLD的机制提供了新的理论依据。