Fatty acid-mediated induction of CYP2E1 activity in HepaRG cells is not systematically associated with exacerbated acetaminophen cytotoxicity

Hepatic cytochrome P450 2E1 (CYP2E1) is thought to contribute to the pathophysiology of metabolic dysfunction-associated steatotic liver disease (MASLD) formerly known as non-alcoholic fatty liver disease (NAFLD). Indeed, increased activity of CYP2E1 in obese subjects with fatty liver may contribute to higher oxidative stress, mitochondrial dysfunction and the progression to steatohepatitis. Besides, higher CYP2E1 activity in obesity and MASLD is deemed to increase the risk of acetaminophen (APAP)-induced hepatotoxicity because this pain reliever is metabolized by CYP2E1 to N-acetyl-p-benzoquinone imine (NAPQI), a highly toxic metabolite. Although the mechanism of MASLD-associated CYP2E1 induction is still unclear, evidence suggests that hepatic CYP2E1 activity is regulated by fatty acids (FAs). In this study, we investigated the effect of 9 FAs differing by their carbon chain length and their degree of unsaturation on CYP2E1 activity in differentiated HepaRG cells. One-week incubation with palmitic acid (PA), stearic acid (SA) and linoleic acid (LA) induced CYP2E1 activity but only LA exposure induced triglyceride accumulation. APAP hepatotoxicity was then assessed in HepaRG cells cultured with or without PA, SA or LA. Acute APAP cytotoxicity was exacerbated in presence of PA or SA and this was accompanied by more severe mitochondrial dysfunction. These effects were not observed when cells were incubated with LA. Hence, FA-mediated increased CYP2E1 activity in HepaRG cells does not necessarily require steatosis. In addition, FA-mediated CYP2E1 induction does not systematically lead to higher APAP-induced cytotoxicity. By favoring triglyceride accumulation, LA might curb APAP-induced mitochondrial dysfunction and cell death.