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Hepatic Steatosis Shifts Phase I Metabolism & Alters In Vitro Toxicant Susceptibility
Citation:
Tucker, N., G. Nelson, J. Harrill, AND B. Chorley. Hepatic Steatosis Shifts Phase I Metabolism & Alters In Vitro Toxicant Susceptibility. Environmental Mutagenesis & Genomics Society Virtual Annual Meeting, NA, NC, September 12 - 16, 2020. https://doi.org/10.23645/epacomptox.13157924
Impact/Purpose:
Nearly 30% of the US population have some form of fatty liver disease. The majority of these individuals have asymptomatic hepatic steatosis due to primarily diet and sedentary lifestyle, but also genetic predisposition, environmental exposure, and other factors. Given the principal function of the liver is to metabolize, detoxify, inactivate, and convert both endogenous and exogenous substances that are either excreted into bile or returned to the systemic circulation, excessive hepatic fat accumulation has the potential to alter the liver’s absorption, deposition, metabolism, and excretion (ADME) of those chemicals. This can directly affect the hepatotoxicity of these exogenous chemical exposures. In vitro assays provide a broad survey of the potential proximal biochemical and cellular targets for a chemical.The goal of this research is to measure the impact of steatosis on ADME of chemicals that are linked to liver toxicity using an in vitro model.
Description:
Hepatic steatosis can alter liver xenobiotic metabolism, impacting bioactivation or detoxification of exposed chemicals. To assess the influence of steatosis on chemical toxicity in vitro, we induced a steatotic state in human hepatoma-derived cells, HepaRGs, with1 mM 1:2 oleic:palmitic free fatty acid for 1 week. Alterations in cytochrome P450 (CYP) gene expression and activity confirmed changes in phase I metabolism. Cellular toxicity measures were determined by Cell Titer Glo (CTG), lactate dehydrogenase (LDH) release, and multiplexed fluorometric measurements of nuclear morphology using the Opera Phenix high-content imaging analyzer. Naive and steatotic HepaRG cells were exposed to a known hepatotoxicant (rotenone) over a 5-point dose range for 24 or 48 hrs. Rotenone toxicity (IC50) shifted 0.64 μM to 0.48 μM in a steatotic model in CTG measurements, from 0.83 μM to 0.57 μM measuring LDH, and 0.80 μM to 0.62 μM using cell counts derived from high content imaging analysis. Expanding this analysis to incorporate additional toxicologic measurements such as cellular reactive oxygen species and mitochondrial membrane potential, a key factor in describing modalities of cell death, will increase the competence of this analytical model in quantifying cell viability and potentially in interrogating biological mechanisms underlying cellular response mechanisms to chemical insult. This abstract does not necessarily reflect the policy of the US EPA.
URLs/Downloads:
DOI: Hepatic Steatosis Shifts Phase I Metabolism & Alters In Vitro Toxicant Susceptibility
2020_EMGS_TUCKER.PDF (PDF, NA pp, 1180.785 KB, about PDF)
2020_EMGS_TUCKER_FULL_POSTER.PDF (PDF, NA pp, 5158.375 KB, about PDF)