Metabolic Activation of Intrahepatic CD8+ T Cells and NKT Cells Causes Nonalcoholic Steatohepatitis and Liver Cancer via Cross-Talk with Hepatocytes

Hepatocellular carcinoma (HCC), the fastest rising cancer in the United States and increasing in Europe, often occurs with nonalcoholic steatohepatitis (NASH). Mechanisms underlying NASH and NASH-induced HCC are largely unknown. We developed a mouse model recapitulating key features of human metabolic syndrome, NASH, and HCC by long-term feeding of a choline-deficient high-fat diet. This induced activated intrahepatic CD8+ T cells, NKT cells, and inflammatory cytokines, similar to NASH patients. CD8+ T cells and NKT cells but not myeloid cells promote NASH and HCC through interactions with hepatocytes. NKT cells primarily cause steatosis via secreted LIGHT, while CD8+ and NKT cells cooperatively induce liver damage. Hepatocellular LTβR and canonical NF-κB signaling facilitate NASH-to-HCC transition, demonstrating that distinct molecular mechanisms determine NASH and HCC development. [Display omitted] •CD-HFD recapitulates metabolic syndrome, NASH, and NASH-induced HCC in humans•NKT cells mediate lipid uptake via LTβR activation on hepatocytes•CD8+ and NKT cells promote liver damage, NASH, and HCC development•NASH-to-HCC transition is facilitated by hepatic LTβR and canonical NF-κB signaling Wolf et al. examine a mouse model of human metabolic syndrome that predispose patients to hepatocellular carcinoma (HCC) and find that activated CD8+ T cells and NKT cells in the liver are important in promoting nonalcoholic steatohepatitis that leads to HCC.