The inhibition of YAP Signaling Prevents Chronic Biliary Fibrosis in the Abcb4-/- Model by Modulation of Hepatic Stellate Cell and Bile Duct Epithelium Cell Pathophysiology

Aging Dis. 2024 Feb 1;15(1):338-356. doi: 10.14336/AD.2023.0602.

Abstract

Primary sclerosing cholangitis (PSC) represents a chronic liver disease characterized by poor prognosis and lacking causal treatment options. Yes-associated protein (YAP) functions as a critical mediator of fibrogenesis; however, its therapeutic potential in chronic biliary diseases such as PSC remains unestablished. The objective of this study is to elucidate the possible significance of YAP inhibition in biliary fibrosis by examining the pathophysiology of hepatic stellate cells (HSC) and biliary epithelial cells (BEC). Human liver tissue samples from PSC patients were analyzed to assess the expression of YAP/connective tissue growth factor (CTGF) relative to non-fibrotic control samples. The pathophysiological relevance of YAP/CTGF in HSC and BEC was investigated in primary human HSC (phHSC), LX-2, H69, and TFK-1 cell lines through siRNA or pharmacological inhibition utilizing verteporfin (VP) and metformin (MF). The Abcb4-/- mouse model was employed to evaluate the protective effects of pharmacological YAP inhibition. Hanging droplet and 3D matrigel culture techniques were utilized to investigate YAP expression and activation status of phHSC under various physical conditions. YAP/CTGF upregulation was observed in PSC patients. Silencing YAP/CTGF led to inhibition of phHSC activation and reduced contractility of LX-2 cells, as well as suppression of epithelial-mesenchymal transition (EMT) in H69 cells and proliferation of TFK-1 cells. Pharmacological inhibition of YAP mitigated chronic liver fibrosis in vivo and diminished ductular reaction and EMT. YAP expression in phHSC was effectively modulated by altering extracellular stiffness, highlighting YAP's role as a mechanotransducer. In conclusion, YAP regulates the activation of HSC and EMT in BEC, thereby functioning as a checkpoint of fibrogenesis in chronic cholestasis. Both VP and MF demonstrate effectiveness as YAP inhibitors, capable of inhibiting biliary fibrosis. These findings suggest that VP and MF warrant further investigation as potential therapeutic options for the treatment of PSC.

MeSH terms

  • Animals
  • Bile Ducts
  • Cholestasis* / metabolism
  • Epithelium / metabolism
  • Fibrosis
  • Hepatic Stellate Cells*
  • Humans
  • Liver Cirrhosis / drug therapy
  • Mice

Grants and funding

Liangtao Ye is granted by the National Natural Science Foundation of China (No. 82000577 and 82073148), China Postdoctoral Science Foundation (No. 2020M680135), Guangdong Provincial Key Laboratory of Digestive Cancer Research (No. 2021B1212040006), and Shenzhen Science and Technology Innovation Committee (JCYJ20200109142605909). The funding agencies were not involved in the study design and data collection, analysis, and interpretation. Parts of this work were presented at the annual meeting of the Bavarian Society of Gastroenterology (GFGB) 2021 (Z Gastroenterol 2021; 59(06): e60) and the work was selected as the Presidential Poster (Top 5). Furthermore, other parts of this work were presented at the International Liver Congress of the EASL (Journal of Hepatology 2021; Volume 75, S389) and also presented as an oral presentation at the annual meeting of the German Society for Digestive and Metabolic Diseases (DGVS) 2021 (Z Gastroenterol 2021; 59(08): e213). This study was supported by the Human Tissue and Cell Research Foundation, a nonprofit foundation regulated by German civil law, which facilitates research with human tissue through the provision of an ethical and legal framework for prospective sample collection. We thank Sebastian Reiter for his support with the illustrations and Jingguo Li for the technical support on parts of the western blot.