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Antitumor progenitor exhausted CD8 T cells are sustained with TCR engagement [ATACseq]

ABSTRACT: Durability of an antitumor immune response is mediated in part by the persistence of progenitor exhausted CD8 T cells (Tpex). Tpex serve as a source for the pool of effector T cells, and in the absence of their cognate antigen, they are able to preserve their quantity through a process of self-renewal. However, it remains unknown how TCR engagement impacts the self-renewal capacity of Tpex in settings of continued antigen exposure. Here, we used a Lewis lung carcinoma model that elicits an optimal or attenuated TCR signal in CD8 T cells to investigate its effect on Tpex persistence during tumor development. Longitudinal phenotyping and single-cell transcriptomics of tumor-specific T cells revealed that formation of the Tpex reservoir in tumor-draining lymph nodes, and its subsequent replenishment of intratumoral Tpex, is dependent on optimal TCR engagement. Notably, adoptive transfer of optimally primed Tpex into a tumor setting with attenuated TCR stimulation significantly accelerates their terminal differentiation, contrasting to the sustained self-renewal occuring with optimal TCR stimulation. This TCR-reinforced Tpex development and self-renewal is coupled to proximal positioning to dendritic cell niches and epigenetic imprinting that involves increased chromatin accessibility at Egr2 and Tcf1 target loci. Collectively, our study highlights the critical role of TCR engagement in sustaining Tpex during tumor progression

ORGANISM(S): Mus musculus

PROVIDER: GSE262842 | GEO | 2024/04/05

REPOSITORIES: GEO

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Project description:In chronic infections and cancer, exhausted CD8 T cells exhibit heterogeneous subpopulations. TCF1+PD-1+ progenitor exhausted CD8 T cells (Tpex) can self-renew and give rise to Tim-3+PD-1+ terminally differentiated CD8 T cells that retain their effector functions. Tpex cells are thus essential to maintaining a pool of antigen-specific CD8 T cells during persistent antigenic stimulation, and only they respond to PD-1-targeted therapy. Despite their potential as a crucial therapeutic target for immune interventions, the mechanisms controlling the maintenance of virus-specific Tpex cells remain to be determined. We observed approximately 10-fold fewer Tpex cells in the spleens of mice chronically infected with lymphocytic choriomeningitis virus (LCMV) one-year post-infection (p.i.) than at three months p.i. Similar to memory CD8 T cells, Tpex cells have been found to undergo self-renewal in the lymphoid organs, prominently the bone marrow, during chronic LCMV infection. Furthermore, ex vivo treatment with IL-15 preferentially induced the proliferation of Tpex cells rather than the terminally differentiated subsets. Interestingly, single-cell RNA sequencing analysis of LCMV-specific exhausted CD8 T cells after ex vivo IL-15 treatment compared with those before treatment revealed upregulation of ribosome-related genes and downregulation of genes associated with the TCR signaling pathway and apoptosis in both Tpex and Ttex subsets. The exogenous administration of IL-15 to chronically LCMV-infected mice also significantly increased self-renewal of Tpex cells in the spleen and bone marrow. In addition, we assessed the responsiveness of CD8 tumor-infiltrating lymphocytes (TILs) from renal cell carcinoma patients to IL-15. Similar to the data we obtained from chronic viral infection in mice, the expansion of the Tpex subset of PD-1+ CD8 TILs upon ex vivo IL-15 treatment was significantly higher than that of the terminally differentiated subset. These results show that IL-15 could promote self-renewal of Tpex cells, which has important therapeutic implications.

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Antitumor progenitor exhausted CD8 T cells are sustained with TCR engagement [ATACseq]

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