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

Aims: The Notch1 signaling pathway is implicated in multiple inflammatory diseases. However, the role of Notch1 signal- ing 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. Methods: 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. 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. Conclusion: 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.