Itaconate promotes memory CD8 + T cell development by epigenetic modification and glucose flux redirection in viral infection and cancer

Background: Coordinated metabolic alterations and epigenetic remodeling are known to critically influence T cell fate decisions and functional states. However, the specific extrinsic metabolic signals that guide CD8 + T cell memory differentiation remain to be fully elucidated. Methods: Naïve CD45.1⁺ OT-I CD8⁺ T cells were adoptively transferred into Listeria monocytogenes-infected CD45.2 mice to track in vivo differentiation trajectories. Tumor-infiltrating CD8⁺ T cells were analyzed by single-cell RNA sequencing to delineate T cell subclusters. Mechanistically, we profiled global chromatin accessibility of CD8⁺ T cells under itaconate treatment using ATAC-seq, revealing its epigenetic remodeling effects. Through a combination of surface plasmon resonance (SPR) and complementary biochemical assays, we demonstrated that itaconate directly binds to lysine demethylase 5B (KDM5B) and functionally antagonizes alpha-ketoglutarate (alpha-KG). Furthermore, metabolic flux analyses, along with direct measurements of NADPH and GSH levels, confirmed that itaconate drives metabolic reprogramming in CD8⁺ T cells to sustain redox balance and memory differentiation capacity. Results: We found that itaconate, induced during immune responses, is a critical promoter of memory T cell (T M ) differentiation. Mechanistically, itaconate directly binds to KDM5B and acts as an alpha-KG antagonist, competitively inhibiting KDM5B-dependent demethylation of H3K4me3. This inhibition leads to increased chromatin accessibility at genes essential for T M cell differentiation. Furthermore, itaconate redirects glucose flux from glycolysis to the PPP, thereby ensuring high levels of NADPH and glutathione in TM cells to alleviate oxidative stress. Conclusions: Our results identify itaconate as a key immunometabolic regulator that promotes durable immune memory in viral infections and cancer by concurrently modulating epigenetic programming and metabolic fitness. This machinery presents a potential therapeutic target to enhance the stem-like phenotype and persistence of CAR T cells.