Hyperoxia induced fatty liver injury through the AKT-dependent and HIF2α-independent pathways

Supplemental oxygen is widely used to treat hypoxemia, but prolonged exposure induces oxidative stress. We investigated whether hyperoxia-induced reactive oxygen species (ROS) contribute to fatty liver injury and delineated the underlying mechanism. To enhance translational relevance, mice were housed under normoxic (21% O₂) or hyperoxic (30% O₂) conditions for 10 days. We also used H₂O₂-treated HepG2 cells and human liver organoids. Western blotting, real-time PCR, and immunostaining were performed to assess molecular changes. Hyperoxia increased systemic oxidative stress, inflammatory markers, liver weights, and hepatic triglyceride (TG) accumulation. These changes were accompanied by repression of fatty acid β-oxidation (FAO) and mitochondrial biogenesis genes, and activation of lipogenesis. Hyperoxia also increased glycolysis, as shown by increased GLUT2 and Gck expression, and activated AKT signaling without altering HIF-2α expression. Consistently, H2O₂-treated HepG2 cells and human liver organoids exhibited similar alterations, including TG accumulation, upregulation of glycolytic and lipogenic markers, downregulation of FAO genes, and increased fibrosis marker and inflammation. Notably, siHIF-2α failed to attenuate TG accumulation, confirming an HIF-2α-independent mechanism. Finally, inhibition of AKT signaling attenuated TG accumulation and fibrosis in vitro by preventing glycolysis (via downregulation of GCK) and de novo lipid synthesis, while improving mitochondrial function; however, GLUT2 expression remained unaffected. In summary, hyperoxia-induced oxidative stress promotes hepatic TG accumulation and fibrosis by impairing mitochondrial function and enhancing glycolysis and lipogenesis in an AKT-dependent, HIF-2α-independent manner. These findings highlight risks of oxygen therapy on hepatic metabolism and identify AKT signaling as a therapeutic target to mitigate hyperoxia-induced fatty liver injury.