In Vitro-In Silico Models to Elucidate Mechanisms of Bile Acid Disposition and Cellular Aerobics in Human Hepatocytes.

Understanding the kinetics of hepatic processes, such as bile acid (BA) handling and cellular aerobic metabolism, is crucial for advancing our knowledge of liver toxicity, particularly drug-induced cholestasis (DiCho). This article aimed to construct interpretable models with parameter estimations serving as reference values when investigating these cell metrics. Longitudinal datasets on BA disposition and oxygen consumption rates were collected using sandwich-cultured human hepatocytes. Chenodeoxycholic acid (CDCA), lithocholic acid (LCA), as well as their amidated and sulfate-conjugated metabolites were quantified with liquid chromatography-mass spectrometry. The bile salt export pump (BSEP) abundance was monitored with targeted proteomics and modelled for activity assessment. Oxygen consumption was measured using Seahorse XFp analyser. Ordinary differential equation-based models were solved in R. The basolateral uptake and efflux clearance of glycine-conjugated CDCA (GCDCA) were estimated at 1.22 µL/min/10⁶ cells (RSE 14%) and 0.11 µL/min/10⁶ cells (RSE 10%), respectively. The GCDCA clearance from canaliculi back to the medium was 2.22 nL/min/10⁶ cells (RSE 17%), and the dissociation constant between (G)CDCA and FXR for regulating BSEP abundance was 25.73 nM (RSE 11%). Sulfation clearance for LCA was 0.19 µL/min/10⁶ cells (RSE 11%). Model performance was further demonstrated by a maximum two-fold deviation of the 95% confidence boundaries from parameter estimates. These in vitro-in silico models provide a quantitative framework for exploring xenobiotic impacts on BA disposition, BSEP activity, and cellular aerobic metabolism in hepatocytes. Model simulations were consistent with reported in vivo data in progressive familial intrahepatic cholestasis type II patients.