Nonalcoholic fatty liver disease (NAFLD) is a hepatic manifestation of obesity and diabetes. Hepatocyte injury and death pathologically mark a turning point from simple liver steatosis to nonalcoholic steatohepatitis (NASH). Chronic hepatocyte injury and hepatic inflammation drive liver fibrosis, leading to liver cirrhosis, end-stage liver failure, and/or hepatocellular carcinoma. We previously reported that NAFLD is associated with a marked elevation of NF-κB-inducing kinase (NIK) in the liver. NIK in turn augments the hepatic hyperglycemic response to counterregulatory hormone glucagon, contributing to hyperglycemia and diabetes progression. Here, we demonstrate that hepatic NIK also promotes hepatocyte injury and death, exacerbating liver disease. We found that hepatocyte-specific overexpression of NIK substantially increased hepatocyte death and liver inflammation in mice treated with acetaminophen (APAP), a hepatocyte-toxic drug. Conversely, hepatocyte-specific deletion of NIK significantly blunted APAP-induced liver injury and hepatitis. In line with these findings, in primary liver cell cultures, overexpression of NIK substantially enhanced APAP sensitivity to induce cell death. Notably, NIK overexpression dramatically increased liver reactive oxygen species (ROS) levels in APAP-treated mice, and ablation of hepatocyte NIK had the opposite effects. Treatment with antioxidant N-acetylcysteine abrogated the ability of NIK and APAP to induce hepatocyte death and liver inflammation. Given that ROS drives ferroptosis, we treated primary liver cells with ferroptosis inhibitors ferrostatin 1 and liproxtatin-1. Both ferrostatin 1 and liproxtatin-1 dose-dependently suppressed NIK/APAP-induced cell death. Collectively, our data suggest that aberrant activation of hepatic NIK augments hepatocyte ferroptosis, thereby promoting liver injury, liver inflammation, and liver disease progression.
X. Zhong: None. L. Rui: None.