Tumor Necrosis Factor Receptor 1-mediated Caspase-2 driven apoptosis reduces HBV DNA levels during free-fatty acid exposure in vitro

Background The coexistence of chronic hepatitis B (CHB) and metabolic dysfunction–associated steatotic liver disease (MASLD) is increasingly prevalent. Clinical and experimental evidence suggests an inverse association between hepatic steatosis and hepatitis B virus (HBV) replication; however, the underlying molecular mechanisms remain poorly defined. This study aimed to investigate the effect of free fatty acid–induced steatosis on HBV replication and the associated apoptotic signaling pathways in vitro. Methods HepG2.2.15 cells, a stable HBV-producing hepatocyte cell line, were treated with a free fatty acid (FFA) mixture of sodium oleate and sodium palmitate at a 2:1 ratio to induce steatosis. Intracellular triglyceride content and Oil Red O staining were used to confirm lipid accumulation. Apoptosis was assessed by flow cytometry. The expression levels of tumor necrosis factor-alpha (TNF-α), tumor necrosis factor receptor 1 (TNFR1), Caspase-2, Caspase-8, and HBV DNA were analyzed before and after FFA treatment. Results FFA treatment induced significant lipid accumulation in HepG2.2.15 cells, accompanied by increased apoptotic cell death. Steatotic cells exhibited significantly elevated levels of TNF-α, TNFR1, Caspase-2, and Caspase-8 compared with untreated controls. In parallel, intracellular HBV DNA levels were markedly reduced following steatosis induction. Conclusions Free fatty acid–induced steatosis in HepG2.2.15 cells is associated with activation of the TNF-α/TNFR1/Caspase-8/Caspase-2 apoptotic pathway and a concomitant reduction in HBV DNA levels. These findings suggest that lipid-induced apoptosis may contribute to the suppression of HBV replication in the context of metabolic stress.