Dipartimento di Scienze Biomediche e Chirurgiche, Università di Perugia, Perugia, Italy.
Dipartimento di Farmacia, Università di Napoli ' Federico II', Napoli, Italy.
Biochim Biophys Acta Mol Cell Biol Lipids. 2020 Sep;1865(9):158733. doi: 10.1016/j.bbalip.2020.158733. Epub 2020 May 1.
The farnesoid-X-receptor (FXR) is validated target in the cholestatic disorders treatment. Obeticholic acid (OCA), the first in class of FXR agonist approved for clinical use, causes side effects including acute liver decompensation when administered to cirrhotic patients with primary biliary cholangitis at higher than recommended doses. The V-Maf avian-musculoaponeurotic-fibrosarcoma-oncogene-homolog-G (Mafg) and nuclear factor-erythroid-2-related-factor-2 (Nrf2) mediates some of the downstream effects of FXR. In the present study we have investigated the role of FXR/MafG/NRF2 pathway in the development of liver toxicity caused by OCA in rodent models of cholestasis. Cholestasis was induced by bile duct ligation (BDL) or administration of α-naphtyl-isothiocyanate (ANIT) to male Wistar rats and FXR and FXR mice. Treating BDL and ANIT rats with OCA exacerbated the severity of cholestasis, hepatocytes injury and severely downregulated the expression of basolateral transporters. In mice, genetic ablation FXR or its pharmacological inhibition by 3-(naphthalen-2-yl)-5-(piperidin-4-yl)-1,2,4-oxadiazole rescued from negative regulation of MRP4 and protected against liver injury caused by ANIT. By RNAseq analysis we found that FXR antagonism effectively reversed the transcription of over 2100 genes modulated by OCA/ANIT treatment, including Mafg and Nrf2 and their target genes Cyp7a1, Cyp8b1, Mat1a, Mat2a, Gss. Genetic and pharmacological Mafg inhibition by liver delivery of siRNA antisense or S-adenosylmethionine effectively rescued from damage caused by ANIT/OCA. In contrast, Nrf2 induction by sulforaphane was protective. CONCLUSIONS: Liver injury caused by FXR agonism in cholestasis is FXR-dependent and is reversed by FXR and Mafg antagonism or Nrf2 induction.
法尼醇 X 受体 (FXR) 是治疗胆汁淤积性疾病的有效靶点。奥贝胆酸 (OCA) 是首个被批准用于临床的 FXR 激动剂，在高于推荐剂量用于原发性胆汁性胆管炎合并肝硬化的患者时，会引起急性肝功能失代偿等副作用。V-Maf 禽肌动蛋白-aponeurotic-fibrosarcoma-oncogene-homolog-G (Mafg) 和核因子-红细胞 2 相关因子-2 (Nrf2) 介导了 FXR 的一些下游效应。在本研究中，我们研究了 FXR/MafG/NRF2 通路在奥贝胆酸引起的胆汁淤积模型啮齿动物肝毒性发展中的作用。通过胆管结扎 (BDL) 或α-萘基异硫氰酸酯 (ANIT) 给药诱导胆汁淤积，在雄性 Wistar 大鼠和 FXR 和 FXR 小鼠中诱导胆汁淤积。用奥贝胆酸治疗 BDL 和 ANIT 大鼠加重了胆汁淤积的严重程度、肝细胞损伤，并严重下调了基底外侧转运体的表达。在小鼠中，FXR 的基因缺失或其药理学抑制通过 3-(萘-2-基)-5-(哌啶-4-基)-1,2,4-恶二唑可挽救由 MRP4 负调控引起的，并可防止 ANIT 引起的肝损伤。通过 RNAseq 分析，我们发现 FXR 拮抗作用有效地逆转了 2100 多个由 OCA/ANIT 治疗调节的基因的转录，包括 Mafg 和 Nrf2 及其靶基因 Cyp7a1、Cyp8b1、Mat1a、Mat2a、Gss。通过肝递送 siRNA 反义寡核苷酸或 S-腺苷甲硫氨酸对 Mafg 的遗传和药理学抑制可有效地挽救由 ANIT/OCA 引起的损伤。相反，磺酰基氟烷诱导的 Nrf2 诱导是保护性的。结论：胆汁淤积中 FXR 激动引起的肝损伤是 FXR 依赖性的，并可通过 FXR 和 Mafg 拮抗或 Nrf2 诱导来逆转。
