Pollutant exposure and pre-existing steatosis sensitize human hepatocytes to drug-induced liver injury

Introduction: Drug-induced liver injury (DILI) is a major cause of acute liver failure. Unlike intrinsic DILI, which is dose-dependent, idiosyncratic DILI (iDILI) occurs unpredictably at therapeutic doses and remains difficult to predict in standard preclinical models. Emerging evidence suggests that acquired conditions, including exposure to persistent organic pollutants (POPs) and pre-existing hepatic steatosis may increase susceptibility by enhancing drug toxicity.

Methods: Human Upcyte hepatocytes were exposed to perfluorooctanoic acid (PFOA) or bisphenol A (BPA), alone or in combination with azathioprine (AZA), amoxicillin/clavulanic acid (AMOX/CLAV) or clavulanic acid (CLAV). Cell injury was assessed by MTT, neutral red uptake or LDH release. Metabolic steatosis was induced by oleate/palmitate (O/P, 2:1), and the impact of AZA and valproic acid (VPA) on intracellular triglycerides was quantified by AdipoRed. Gene expression was analyzed by RT-qPCR.

Results: Environmental pollutants potentiated drug hepatotoxicity. A synergistic loss of viability was observed with PFOA+AMOX/CLAV and after acute co-exposure to PFOA +AZA when compared to PFOA . Co-treatment with PFOA and CLAV also increased expression of the NRF2-related genes and FGF19, when compared to CLAV alone, consistent with activation of oxidative stress-adaptive pathways. In parallel, supporting a synergistic interaction, co-exposure to AZA and BPA caused a greater-than-expected decrease in cell viability, increased ROS levels, promoted glutathione metabolism and a lipogenic gene expression profile, and induced triglyceride accumulation.

Preloading hepatocytes with O/P markedly modified their response to steatogenic drugs. In AZA-treated cells, O/P slightly enhanced cytotoxicity and strongly potentiated triglyceride accumulation. RT-qPCR analysis showed increased expression of several lipogenesis-related genes, particularly PLIN2, CIDEC, ACC2 and AGPAT5. O/P also potentiated VPA-induced triglyceride accumulation.

Conclusions: These preliminary findings suggest that environmental and metabolic context modulate hepatocyte susceptibility to drug toxicity. Incorporating pollutant exposure and steatotic background into in vitro testing may improve mechanistic understanding of iDILI.