Immunometabolism regulation by PSGL-1 signaling in tumor-specific CD8 T cells

Abstract

Abstract We previously identified that the adhesion molecule P-selectin glycoprotein ligand-1 (PSGL-1) regulates T cell function and exhaustion in response to chronic viral infection and tumors. Subsequent studies have focused on investigating the role of PSGL-1 signaling in T cell responses, with an emphasis on understanding the mechanisms by which PSGL-1 regulates T cell exhaustion. Single-cell RNA-sequencing of tumor infiltrating PSGL-1−/− CD8+ T cells identified the upregulation and differential modulation of several genes associated with T cell metabolism and enhanced intratumoral responses, including Mtor, Hif1a, and Mki67 in Gzmb/Ifng double-positive cells from tumors and Tcf7 in both tumor draining and non-draining inguinal lymph nodes. These data suggest an important role for PSGL-1 signaling in the development and maintenance of effective anti-tumor T cell responses to melanoma. Using the Seahorse glycolysis stress test, we identified that both CD4+ and CD8+ PSGL-1−/− T cells demonstrate increased glycolysis after 72 hours of in vitro activation compared to wild-type T cells. In situ activation of PSGL-1−/− CD8+ T cells demonstrated that PSGL-1−/− CD8+ T cells have increased glycolysis and increased glycolytic capacity at both sub-optimal and optimal levels of α-CD3 stimulation, and 2-NBDG glucose uptake assays confirmed increased glucose uptake by PSGL-1−/− CD8+ T cells within two hours of stimulation. Importantly, this increased glycolytic phenotype does not come at the cost of CD8+ T cell stemness, as determined by TCF-1 staining. Taken together, these data show that PSGL-1 signaling has an intrinsic and immediate role in the development of T cell responses and their metabolic profile in response to melanoma tumors.