Prediction of cholestatic potential of drugs and investigation of mechanisms underlying cholestasis using HepaRG cells
Drug-induced liver injury (DILI) is a major cause of attrition during both early and late stages of drug development and a leading cause for drug withdrawal in postmarketing. Drug-induced cholestasis (DIC) accounts for as much as 50% of DILI cases. Unfortunately, current preclinical models including animals and in vitro models fail to accurately predict the cholestatic potential of drugs. Cholestasis is characterized by impaired bile secretion that results in the accumulation of high levels of bile acids causing liver injury. Depending on the site of bile acid accumulation, two types of cholestasis are distinguished: extrahepatic and intrahepatic cholestasis.
HepaRG cells represent a unique human metabolically competent cell line with bile canaliculi-like structure formation. Contrary to other human liver cell lines, differentiated HepaRG cells express features of mature hepatocytes, including expression of phase I and II enzymes, transporters, and nuclear receptors at levels comparable to those observed in primary human hepatocytes. Interestingly, differentiated HepaRG cells stably maintain this expression for almost 4 weeks. The main influx and efflux transporters are functional in HepaRG hepatocyte-like cells and are correctly localized to canalicular or basolateral membrane domains. Using HepaRG cells, different mechanisms underlying DIC have been discovered. Oxidative stress generation, endoplasmic stress, mitochondrial impairment, and inflammation were reported to play important roles in DIC in HepaRG cells.
Importantly, the molecular initiating events of DIC such as changes in expression and activities of transporters, disruption of tight junctions, and alteration of bile canaliculi dynamics were all characterized in the HepaRG cell model. Moreover, it has been shown that the 3D spheroid model of HepaRG cells constitutes a potential model to study bile acid accumulation, biliary excretion processes, and intrahepatic cholestasis. Altogether, these studies highlight the HepaRG cell line as a robust and adequate alternative model to primary human hepatocytes, to study drug-induced cholestasis, and to investigate cholestasis adverse outcome pathways.
Speaker: Pamela Azzi
Pamela Bachour El Azzi is a professor at the Lebanese University, Université Saint Joseph, and Université Antonine for 6 years. She is a scientific consultant at Biopredic International. Dr. Bachour El Azzi has completed a Ph.D. in Biology and health sciences with a specialty in toxicology at the Université de Rennes I and the Lebanese University. The main Ph.D. work of Dr. Bachour El Azzi was the characterization of bile acid transporters in HepaRG cells and the investigation of drug-induced cholestatic mechanisms. She studied cellular mechanisms underlying chlorpromazine-induced intrahepatic cholestasis in vitro in the presence or not of an inflammatory context.