CYP450 drug inducibility in NAFLD via an in vitro hepatic model: Understanding drug-drug interactions in the fatty liver

Drug-drug-interactions (DDIs) occur when a drug alters the metabolic rate, efficacy, and toxicity of concurrently used drugs. While almost 1 in 4 adults now use at least 3 concurrent prescription drugs in the United States, the Non-alcoholic fatty liver disease (NAFLD) prevalence has also risen over 25%. The effect of NALFD on DDIs is largely unknown. NAFLD is characterized by lipid vesicle accumulation in the liver, which can progress to severe steatohepatitis (NASH), fibrosis, cirrhosis, and hepatic carcinoma. The CYP450 enzyme family dysregulation in NAFLD, which might already alter the efficacy and toxicity of drugs, has been partially characterized. Nevertheless, the drug-induced dysregulation of CYP450 enzymes has not been studied in the fatty liver. These changes in enzymatic inducibility during NAFLD, when taking concurrent drugs, could cause unexpected fatalities through inadvertent DDIs. We have, thus, developed an in vitro model to investigate the CYP450 transcriptional regulation in NAFLD. Specifically, we cultured primary human hepatocytes in a medium containing free fatty acids, high glucose, and insulin for seven days. These cultures displayed intracellular macro-steatosis after 5 days and cytokine secretion resembling NAFLD patients. We further verified the model’s dysregulation in the transcription of key CYP450 enzymes. We then exposed the NAFLD model to the drug inducers rifampicin, Omeprazole, and Phenytoin as activators of transcription factors pregnane X receptor (PXR), aryl hydrocarbon receptor (AHR) and constitutive androstane receptor (CAR), respectively. In the NAFLD model, Omeprazole maintained an expected induction of CYP1A1, however Phenytoin and Rifampicin showed elevated induction of CYP2B6 and CYP2C9 compared to healthy cultures. We, thus, conclude that the fatty liver could cause aggravated drug-drug interactions in NAFLD or NASH patients related to CYP2B6 and CYP2C9 enzymes.