Targeting ferroptosis restores the antiviral activity of CD8+ T cells during chronic HBV infection

CD8+ T cells play a crucial role in antiviral immunity; however, hepatitis B virus (HBV)-specific CD8+ T cells become dysfunctional during chronic HBV (CHB) infection. Blocking inhibitory pathways only partially restores efficient antiviral responses, suggesting that the mechanism underlying CD8+ T-cell dysfunction is complicated. This study aimed to investigate whether HBV-specific CD8+ T cells undergo ferroptosis, examine its correlation with T-cell dysfunction, and elucidate the underlying mechanism and potential intervention strategies. Analysis of CD8+ T cells from CHB patients revealed ferroptosis markers via flow cytometry, electron microscopy, and scRNA-seq, and HBV-specific CD8+ T cells were identified using HBV-core antigen peptide-loaded MHC I tetramer. Flow cytometry, scRNA-seq and additional experimental approaches were employed to investigate the ferroptosis-associated mechanisms in CD8+ T-cell dysfunction. Ferroptosis was observed in CD8+ T cells from CHB patients, as indicated with increased lipid peroxidation, Fe2+ accumulation and mitochondrial atrophy, particular in HBV-specific CD8+ T cells. Downregulation of GPX4 and upregulation of CD36 were found in CD8+ T cells with high level of lipid peroxidation. Furthermore, ferroptosis is accompanied by impaired antiviral ability. Mechanistically, palmitic acid (PA) upregulates CD36 expression, leading to lipid accumulation; while elevated serum TGF-β1 in CHB patients reduces GPX4 expression and impairs antioxidant capacity. These factors synergistically promote ferroptosis and dysfunction of CD8+ T cells. Treatment with selenium and liproxstain-1 enhanced cytotoxic cytokines production by CD8+ T cells, and subsequently improved antiviral efficacy in vivo. Our study demonstrates that ferroptosis drives CD8+ T-cell dysfunction in chronic HBV infection. Targeting ferroptosis pathways may offer a novel therapeutic strategy to restore antiviral immunity.