Differential toxic effects of bile acid mixtures in isolated mitochondria and physiologically relevant HepaRG cells

• Published in: Toxicology in vitro 2019-12, Vol.61, p.104595, Article 104595
• Main Authors: Penman, Sophie L., Sharma, Parveen, Aerts, Hélène, Park, B. Kevin, Weaver, Richard J., Chadwick, Amy E.
• Format: Article
• Language: English
• Subjects: Bile; Bile acids; Bile Acids and Salts - toxicity; Biliary transporters; Cell Line; Cholestasis; Cytotoxicity; Drug resistance; Drug-induced cholestasis; Electron transport; Electron transport chain; Galactose; HepaRG; Humans; Membrane potential; Membrane Potential, Mitochondrial - drug effects; Mitochondria; Mitochondria - drug effects; Mitochondria - physiology; Multidrug resistance; Multidrug Resistance-Associated Proteins - metabolism; Oxygen consumption; Time dependence; Toxicity
• ISSN: 0887-2333; 1879-3177
• DOI: 10.1016/j.tiv.2019.104595

Bile acids (BAs) are recognised as the causative agents of toxicity in drug-induced cholestasis (DIC). Research in isolated mitochondria and HepG2 cells have demonstrated BA-mediated mitochondrial dysfunction as a key mechanism of toxicity in DIC. However, HepG2 cells are of limited suitability for DIC studies as they do not express the necessary physiological characteristics. In this study, the mitotoxic potentials of BA mixtures were assessed in isolated mitochondria and a better-suited hepatic model, HepaRG cells. BAs induced structural alterations and a loss of mitochondrial membrane potential (MMP) in isolated mitochondria however, this toxicity did not translate to HepaRG cells. There were no changes in oxygen consumption rate, MMP or ATP levels in glucose and galactose media, indicating that there was no direct mitochondrial toxicity mediated via electron transport chain dysfunction in HepaRG cells. Assessment of key biliary transporters revealed that there was a time-dependent reduction in the expression and activity of multi-drug resistance protein 2 (MRP2), which was consistent with the induction of cytotoxicity in HepaRG cells. Overall, the findings from this study have demonstrated that mitochondrial dysfunction is not a mechanism of BA-induced toxicity in HepaRG cells. •HepaRG cells are a better suited in vitro model for cholestatic studies than HepG2 cell.•Bile acids cause mitochondrial toxicity in isolated mitochondria but not in HepaRG cells.•Time-dependent alterations in biliary transporters are consistent with the cytotoxicity of bile acid mixtures.•There are important mechanistic differences when bile acids interact at the organelle level versus the whole cell.