Key Laboratory of Basic Pharmacology of Ministry of Education and Joint International Research Laboratory of Ethnomedicine of Ministry of Education, Zunyi Medical University, Zunyi, China.
School of Pharmacy, Zunyi Medical University, Zunyi, China.
J Appl Toxicol. 2023 Aug;43(8):1201-1213. doi: 10.1002/jat.4456. Epub 2023 Mar 23.
Natural pentacyclic triterpenoid oleanolic acid (OA) is used as an over-the-counter drug for acute and chronic hepatitis. However, clinical use of OA-containing herbal medicines has been reported to cause cholestasis, and the specific mechanism is unknown. The purpose of this study was to explore how OA causes cholestatic liver injury via the AMP-activated protein kinase (AMPK)-farnesoid X receptor (FXR) pathway. In animal experiments, it was found that OA treatment activated AMPK and decreased FXR and bile acid efflux transport proteins expression. When intervened with the specific inhibitor Compound C (CC), it was observed that AMPK activation was inhibited, the reduction of FXR and bile acid efflux transport protein expression was effectively alleviated, serum biochemical indicators were significantly reduced, and liver pathological damage brought about by OA was effectively ameliorated. In addition, OA was found to downregulate the expression of FXR and bile acid efflux transport proteins by activating the ERK1/2-LKB1-AMPK pathway in cellular experiments. The ERK1/2 inhibitor U0126 was used to pretreat primary hepatocytes, and this drastically reduced the phosphorylation levels of LKB1 and AMPK. The inhibition effects of OA on FXR and bile acid efflux transport proteins were also effectively alleviated after pretreatment with CC. In addition, OA-induced downregulation of FXR gene and protein expression levels was significantly prevented after silencing AMPKα1 expression in AML12 cells. Our study demonstrated that OA inhibited FXR and bile acid efflux transporters through the activation of AMPK, thus leading to cholestatic liver injury.
天然五环三萜齐墩果酸 (OA) 被用作治疗急、慢性肝炎的非处方药。然而，含有 OA 的草药的临床应用已被报道可导致胆汁淤积，具体机制尚不清楚。本研究旨在探讨 OA 通过 AMP 激活蛋白激酶 (AMPK)-法尼醇 X 受体 (FXR) 途径引起胆汁淤积性肝损伤的机制。在动物实验中，发现 OA 处理激活了 AMPK，降低了 FXR 和胆汁酸外排转运蛋白的表达。当用特异性抑制剂 Compound C (CC) 进行干预时，观察到 AMPK 激活被抑制，FXR 和胆汁酸外排转运蛋白表达的减少得到有效缓解，血清生化指标显著降低，OA 引起的肝病理损伤得到有效改善。此外，在细胞实验中，OA 通过激活 ERK1/2-LKB1-AMPK 通路下调 FXR 和胆汁酸外排转运蛋白的表达。用 ERK1/2 抑制剂 U0126 预处理原代肝细胞，可明显降低 LKB1 和 AMPK 的磷酸化水平。用 CC 预处理后，OA 对 FXR 和胆汁酸外排转运蛋白的抑制作用也得到有效缓解。此外，在 AML12 细胞中沉默 AMPKα1 表达后，OA 诱导的 FXR 基因和蛋白表达水平的下调明显得到预防。本研究表明，OA 通过激活 AMPK 抑制 FXR 和胆汁酸外排转运体，导致胆汁淤积性肝损伤。
