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Beta-catenin in dendritic cells negatively regulates CD8 T cell im-mune responses through the immune checkpoint molecule Tim-3

ABSTRACT: Recent studies have demonstrated that b-catenin in dendritic cells (DCs) serves as a key mediator in promoting both CD4 and CD8 T cell tolerance, although the mechanisms underlying how b-catenin exerts its functions remains incompletely understood. Here we report that activation of b-catenin leads to the up-regulation of inhibitory molecule T-cell immunoglobulin and mucin domain 3 (Tim-3) in type 1 conventional DCs (cDC1s). Using a cDC1-targeted vaccine model with anti-DEC-205 engineered to express the melanoma antigen--human gp100 (anti-DEC-205-hgp100), we demonstrated that CD11c-b-cateninactive mice exhibited impaired cross-priming and memory re-sponses of gp100-specific CD8 T (Pmel-1) cells upon immunization with anti-DEC-205-hgp100. Sin-gle cell RNA sequencing (scRNA-seq) analysis revealed that b-catenin in DCs negatively regulated transcription programs for effector function and proliferation of primed Pmel-1 cells, correlating with suppressed CD8 T cell immunity in CD11c-b-cateninactive mice. Further experiments showed that treating CD11c-b-cateninactive mice with anti-Tim-3 antibody upon anti-DEC-205-hgp100 vac-cination led to restored cross-priming and memory responses of gp100-specific CD8 T cells, sug-gesting that anti-Tim-3 treatment likely synergizes with DC vaccines to improve their efficacy. In-deed, treating B16F10-bearing mice with DC vaccines using anti-DEC-205-hgp100 in combination with anti-Tim-3 treatment resulted in significantly reduced tumor growth, compared to treatment with DC vaccine alone. Taken together, we have identified the b-catenin/Tim-3 axis as a novel mech-anism to inhibit anti-tumor CD8 T cell immunity, and that combination immunotherapy of a DC-targeted vaccine with anti-Tim-3 treatment leads to improved anti-tumor efficacy.

ORGANISM(S): Mus musculus

PROVIDER: GSE263715 | GEO | 2024/05/02

REPOSITORIES: GEO

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Project description:GSK-3b plays a critical role in regulating the Wnt/b-catenin signaling pathway, and manipulating GSK-3b in dendritic cells (DCs) has been shown to improve anti-tumor efficacy of DC vaccines. Since inhibition of GSK-3b leads to activation of b-catenin, we hypothesize that blocking GSK-3b in DCs negatively regulates DC-mediated CD8 T cell immunity and anti-tumor immunity. Using CD11c-GSK-3b-/- conditional knockout mice in which GSK-3b is genetically deleted in CD11c-expressing DCs, we surprisingly found that deletion of GSK-3b in DCs resulted in increased anti-tumor immunity, which contradicted our initial expectation of reduced anti-tumor immunity due to presumed upregulation of b-catenin in DCs. Indeed, we found by both western blot and flow cytometry that deletion of GSK-3b in DCs did not lead to augmented expression of b-catenin protein, suggesting that GSK-3b exerts its function independent of b-catenin. Supporting this notion, our single cell RNA sequencing (scRNA-seq) analysis revealed that GSK-3b-deficient DCs exhibited distinct gene expression patterns with minimally overlapping differentially expressed genes (DEGs) compared to DCs with activated b-catenin. This suggests that deletion of GSK-3b in DCs is unlikely to lead to upregulation of b-catenin at the transcriptional level. Consistent with enhanced anti-tumor immunity, we also found that CD11c-GSK-3b-/- mice exhibited significantly augmented cross-priming of antigen-specific CD8 T cells following DC-targeted vaccines. We further found that deletion of GSK-3b in DCs completely abrogated memory CD8 T cell responses, suggesting that GSK-3b in DCs also plays a negative role in regulating the differentiation and/or maintenance of memory CD8 T cells. scRNA-seq analysis further revealed that although deletion of GSK-3b in DCs positively regulated transcriptional programs for effector differentiation and function of primed antigen-specific CD8 T cells in CD11c-GSK-3b-/- mice during the priming phase, it resulted in significantly reduced antigen-specific memory CD8 T cells, consistent with diminished memory responses. Taken together, our data demonstrate that GSK-3b in DCs has opposite functions in regulating cross-priming and memory CD8 T cell responses, and GSK-3b exerts its functions independent of its regulation of b-catenin.

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Beta-catenin in dendritic cells negatively regulates CD8 T cell im-mune responses through the immune checkpoint molecule Tim-3

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