Department of Gastroenterology and Hepatology, Institution of Digestive Diseases, Tongji Hospital, Tongji University School of Medicine, Shanghai, China.
Department of Gastroenterology and Hepatology, Institution of Digestive Diseases, Tongji Hospital, Tongji University School of Medicine, Shanghai, China.
Life Sci. 2020 Jun 15;251:117595. doi: 10.1016/j.lfs.2020.117595. Epub 2020 Mar 30.
The activation of hepatic stellate cells (HSCs) plays a central role in liver fibrosis progression. Phospholipase D (PLD) enzymes participate in multiple cellular activities. However, whether and how PLD regulates HSCs activation remain elusive.
The expression of intrahepatic PLD1 and PLD2 was determined in CCl-induced mouse liver fibrosis models by western blot and immunohistochemistry. Cell model of liver fibrogenesis was constructed using rat HSCs line (HSC-T6) treated with recombinant transforming growth factor β1 (TGFβ1). Fibrogenesis was evaluated on the aspects of proliferation, expression of pro-fibrogenic markers and migration. The effects mediated by PLD1-mTOR axis on TGFβ1-induced fibrogenesis were evaluated using HSC-T6 treated with small-molecular PLD1 inhibitors, PLD1-SiRNA, rapamycin (mTOR inhibitor) and MHY1485 (mTOR activator).
Significant increase of PLD1, not PLD2 was documented in CCl-induced cirrhotic compared to normal liver tissues. Suppression of PLD1 activities by PLD inhibitors or down-regulation of PLD1 expression in HSC-T6 could significantly restrain TGFβ1-induced fibrogenesis, as reflected by decreased cell proliferation and reduced expression of pro-fibrogenic markers. Besides, either PLD1 inhibitor or PLD1-SiRNA significantly inhibited mTOR activity of HSC-T6. Moreover, PLD1 inhibitors not only exhibited similar effects with rapamycin in TGFβ1-induced fibrogenesis, but also blunted MHY1485 enhanced cell proliferation of HSC-T6.
The PLD1-mTOR axis of HSCs could be therapeutically targeted in advanced liver fibrosis.
肝星状细胞（HSCs）的激活在肝纤维化进展中起着核心作用。磷酸脂酶 D（PLD）酶参与多种细胞活动。然而，PLD 是否以及如何调节 HSCs 的激活仍不清楚。
通过 Western blot 和免疫组织化学法测定 CCl 诱导的小鼠肝纤维化模型中肝内 PLD1 和 PLD2 的表达。用重组转化生长因子β1（TGFβ1）处理大鼠 HSCs 系（HSC-T6）构建肝纤维化细胞模型。从增殖、促纤维化标志物表达和迁移等方面评估纤维化。用小分子 PLD1 抑制剂、PLD1-SiRNA、雷帕霉素（mTOR 抑制剂）和 MHY1485（mTOR 激活剂）处理 HSC-T6，评估 PLD1-mTOR 轴介导的 TGFβ1 诱导的纤维化作用。
与正常肝组织相比，CCl 诱导的肝硬化组织中 PLD1 而非 PLD2 显著增加。PLD 抑制剂或 PLD1-SiRNA 抑制 HSC-T6 中 PLD1 活性可显著抑制 TGFβ1 诱导的纤维化，表现为细胞增殖减少和促纤维化标志物表达降低。此外，PLD1 抑制剂或 PLD1-SiRNA 均可显著抑制 HSC-T6 的 mTOR 活性。此外，PLD1 抑制剂不仅在 TGFβ1 诱导的纤维化中表现出与雷帕霉素相似的作用，而且还减弱了 MHY1485 增强 HSC-T6 细胞增殖的作用。
HSCs 的 PLD1-mTOR 轴可作为晚期肝纤维化的治疗靶点。
