Epigenetic mechanisms controlling longevity of T cell immunity 2259637
Long-lived T cell immunity can protect against endemic pathogens that result in iterative challenge to the host, but how such repeated activation of T cells impacts on the molecular mechanisms governing memory potential remains largely unclear. Here, we assessed the role of de novo epigenetic programs in shaping the repertoire and recall response of memory T cells in a setting of iterative acute viral infection. Using our previously established CRISPR system for deleting epigenetic regulators (Kang et al, 2024, Science), we optimized an iterative acute viral infection model with LCMV to serially activate Dnmt3a deficient memory T cells. CRISPR-edited Dnmt3a-deficient P14 CD8 T cells were adoptively transferred cells into B6 mice and subjected to acute infections. Based on our previously established acute viral infection, we evaluated the impact of repetitive antigen exposure on memory CD8 T cells differentiation, longevity, proliferation, cytotoxicity and anti-tumor activity. Dnmt3a KO retain potentially memory CD8 T cells stronger proliferative capacity during acutely prolonged stimulation, but non-target sgRNA group P14 ratio gradually decrease. Additionally, Dnmt3a knockout T cells displayed sustained memory precursor features, including higher CXCR3, Ly108, and TCF1, with lower PD-1 and Tim-3 expression. Functionally, they produced more IL-2, suggesting enhanced viral clearance and overall T cell survival. These results indicate that loss of Dnmt3a preserves stem-like properties and enhance the long-term persistence of memory CD8 T cells under repetitive antigen exposure, providing an epigenetic mechanism to improve immune durability. Our findings show that Dnmt3a KO T cells have increased T cell stemness and durability and indicate that Dnmt3a drives CD8 T cell memory capacity during iterative acute stimulation. These results clarify our research direction that de novo epigenetic programming continues to shape T cell repertoire and recall memory response. National Institutes of Health Immune Response Regulation: Molecular Mechanisms (IRM)