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)
Yun Liu, Ben Youngblood, Caitlin C. Zebley et al.· Journal of Immunology· 0 citations
Despite suppressive antiretroviral therapy (ART), HIV reservoirs rapidly rebound upon treatment interruption, driven in part by progressive dysfunction of HIV-specific CD8+ T cells. Current strategies targting CD8+T cell dysfunction in cancer show limited benefit in people living with HIV (PLWH), underscoring the need for alternative approaches tailored to the unique immunological landscape of HIV infection. Adenosine (ADO) signaling is a potent immunoregulatory pathway regulated by adenosine deaminase-1 (ADA-1) that becomes dysregulated in PLWH and is associated with viral persistence. However, more work is needed to define its direct contribution to HIV-specific CD8+ T-cell dysfunction.
Using primary samples from PLWH, we applied three complementary approaches: (1) multi-omic and phenotypic profiling of tetramer-sorted HIV- and CMV-specific CD8+ T cells to assess regulation of ADA and ADO-signaling components; (2) ex vivo functional assays measuring cytokine production and degranulation following ADO or 2-chloroadenosine exposure with ADA-1 inhibition; and (3) CD8-targeted lipid nanoparticles (CD8-ADA-LNPs) to selectively deliver ADA-1 mRNA and assess functional improvement.
HIV-specific CD8+ T cells exhibited repression of the ADA locus, increased expression of CD39 and the A2a adenosine receptor, indicating potential heightened sensitivity to ADO-mediated suppression. Functionally, ADO-exposure impaired CD8+ T-cell function, dependent on ADA-1. Targeted ADA-1 mRNA delivery via CD8-ADA-LNPs restored ADA-1 expression and improved antigen-specific CD8+ T-cell function in PLWH ex vivo.
These findings identify dysregulated ADO signaling and ADA-1 deficiency as contributors to HIV-specific CD8+ T-cell dysfunction and establish targeted ADA-1 delivery as a novel strategy to enhance CD8+ T-cell function. This approach provides a framework for targeting ADO-mediated immune suppression of CD8+T cells in HIV and other disease landscapes, including cancer.
Part of this work was funded by NIH grant to Dr. Elias K Haddad (# U19AI128910-04S1)
Translational and Interventional Immunology (TI)
Arden O. Edgerton, Dillon O'Neill, David Joyner et al.· Journal of Immunology· 0 citations
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