他汀类降脂药是防治冠心病的重要药物，长期使用能引起转氨酶异常升高和肝损伤，但是，他汀类药物产生肝毒性的机制尚不明确，已成为这领域的难点问题。他汀类药物引起的肝损伤多为胆汁淤积和黄疸，这提示其肝毒性可能与胆汁酸稳态失衡相关。胆汁酸核受体FXR能够通过促进胆汁酸的胆汁排泄并负反馈抑制胆汁酸的合成维持胆汁酸稳态。本课题假设他汀类药物通过抑制FXR通路激活，上调Cyp7a1使胆汁酸的肝脏合成增加，并下调Bsep和Mrp2使胆汁酸的胆汁排泄减少，进而产生胆汁酸在肝脏的累积，最终导致肝毒性。本课题应用超高效液相色谱-串联质谱联用法测定他汀类药物引起的肝脏胆汁酸浓度的变化；揭示他汀类药物产生肝毒性是通过FXR介导的；并进一步利用高血脂和肝内胆汁淤积动物模型证明与FXR激动剂合并用药能够减少长期使用他汀类药物产生的肝损伤。本研究将为临床上预估和提高他汀类药物的长期用药的安全性提供重要指导。

Statins are a class of lipid-lowering drugs that are essential in the treatment of coronary heart diseases. Long-term use of statins can lead to abnormal elevation of liver-specific enzymes in blood and liver injury. However, the exact mechanism of the hepatotoxicity of statins remains elusive，which has become a hurdle of this field. The majority of statin-induced liver injuries are cholestasis and jaundice, which indicates the possible connection between the hepatotoxicity of statins and the disrupted metabolism of bile acids. The bile acid nuclear receptor FXR plays a crucial role in maintaining bile acid homeostasis, through promoting the biliary excretion of bile acids and feed-back inhibiting bile acid synthesis in liver. In this grant, it is hypothesized that statins can inhibit FXR transactivation and thus up-regulate Cyp7a1 and bile acid synthesis in liver and down-regulate Bsep and Mrp2 and biliary excretion of bile acids, which results in bile acid accumulation in liver and ultimately hepatotoxicity. In this grant, a UPLC-MS/MS method will be applied to determine the changes in hepatic concentrations of bile acids after statin treatment. A novel mechanism of statin-induced hepatotoxicity through the inhibition of FXR pathway will be revealed. Furthermore, combined therapy with a FXR agonist will be proved to effectively decrease the hepatotoxicity of long-term use of statins in hypercholesterolemic and intrahepatic cholestatic animal models, respectively. The proposed study will provide valuable guidance on predicting and improving the safety of long-term clinical use of statins.

本课题研究证实阿托伐他汀抑制FXR通路水平，上调Cyp7a1的转录使胆汁酸的肝脏合成增加，并下调Bsep和Mrp2的转录使胆汁酸的胆汁排泄减少，进而产生胆汁酸在肝脏的累积，最终导致肝毒性。本课题利用饮食导致的高胆固醇模型研究长期用他汀类药物调脂产生的肝损伤，利用α-萘异硫氰酸酯（ANIT）诱导肝内胆汁淤积模型研究恢复他汀用药产生的二次肝损伤。ANIT诱导的肝内胆汁淤积损伤伴随炎症反应和胆管上皮细胞增生，并且长期损伤还会导致肝脏纤维化。FXR可减轻肝脏的纤维化程度，长期使用阿托伐他汀时可以抑制FXR通路，导致肝脏胆汁酸水平升高，产生肝毒性；当与FXR激动剂合并用药时可以减轻肝毒性。