Bile salts regulate CYP7A1 expression and elicit a fibrotic response and abnormal lipid production in 3D liver microtissues

Toxicol In Vitro. 2019 Oct;60:261-271. doi: 10.1016/j.tiv.2019.06.002. Epub 2019 Jun 10.

Abstract

Disrupted regulation and accumulation of bile salts (BS) in the liver can contribute towards progressive liver damage and fibrosis. Here, we investigated the role of BS in the progression of cholestatic injury and liver fibrosis using 3D scaffold-free multicellular human liver microtissues (MTs) comprising the cell lines HepaRG, THP-1 and hTERT-HSCs. This in vitro model has been shown to recapitulate cellular events leading to fibrosis including hepatocellular injury, inflammation and activation of HSCs, ultimately leading to increased deposition of extracellular matrix (ECM). In order to better differentiate the contribution of individual cells during cholestasis, the effects of BS were evaluated either on each of the three cell types individually or on the multicellular MTs. Our data corroborate the toxic effects of BS on HepaRG cells and indicate that BS exposure elicited a slight increase in cytokines without causing stellate cell activation. Contrarily, using the MTs, we could demonstrate that low concentrations of BS led to cellular damage and triggered a fibrotic response. This indicates that cellular interplay is required to achieve BS-triggered activation of HSC. Moreover, BS were capable of down-regulating CYP7A1 expression in MTs and elicited abnormal lipid production (accumulation) concordant with clinical cases where chronic cholestasis results in hypercholesterolemia.

MeSH terms

  • Bile Acids and Salts / toxicity*
  • Cell Line
  • Cholestasis / metabolism*
  • Cholesterol 7-alpha-Hydroxylase / genetics*
  • Coculture Techniques
  • Humans
  • Lipid Metabolism / drug effects*
  • Liver / metabolism
  • Liver Cirrhosis / metabolism*
  • Tissue Engineering

Substances

  • Bile Acids and Salts
  • CYP7A1 protein, human
  • Cholesterol 7-alpha-Hydroxylase