Notch1-Nuclear Factor κB Involves in Oxidative Stress-Induced Alcoholic Steatohepatitis

Abstract

The Notch1 signaling pathway is implicated in multiple inflammatory diseases. However, the role of Notch1 signaling in alcoholic steatohepatitis (ASH) has not been fully investigated. We aimed to determine whether Notch1-Nuclear factor-κB (NF-κB) signaling mediates oxidative stress-induced ASH. In vitro, three cell lines were used: the HepG2 cells, HepG2 cells transfected with a control vector (Neo cells) and HepG2 cells transfected with a cytochrome P4502E1-expression vector (2E1 cells), which allows the cells to undergo oxidative stress in response to ethanol. All three cell lines were incubated with ethanol with/without Notch1 inhibitor treatment, oxidative stress marker, steatohepatitis marker and Notch1-NF-κB signaling were assessed. To further test Notch1-NF-κB signaling in vivo, rats were fed with ethanol, ethanol plus Notch1 inhibitor or an isocaloric diet for 8 weeks. Hepatitis, oxidative stress and Notch1-NF-κB activity in the liver were assessed to further verify the in vitro results. Ethanol was shown to induce oxidative stress and steatohepatitis with remarkably elevated Notch1-NF-κB expression in 2E1 cells rather than HepG2 and Neo cells. Notch1 inhibitor was non-toxic in the three cell lines and had a protective effect against markers of ASH. Similarly, chronic alcohol administration in vivo induced alcoholic hepatitis, oxidative stress and elevated Notch1-NF-κB expression in rats, while Notch1 inhibitor attenuated alcoholic liver injury. These findings provide direct in vitro and in vivo evidence that the oxidative stress-induced ASH is mediated by the Notch1-NF-κB signaling pathway, which can be effectively reversed by Notch1 inhibitor.