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The role of Glut1 in glucose-restricted CD8+ T cells Ser, Terri

Abstract

Adoptive T cell therapy (ACT) is a popular cancer treatment that involves transferring CD8+ T cells to patients, and its therapeutic efficacy depends on the ability of CD8+ T cells to produce pro-inflammatory molecules, such as IFN-γ. Despite the promising results in leukemia, the effectiveness of T cell therapies remains limited for solid tumours. Previous research has shown that subjecting CD8+ T cells to transient glucose restriction (TGR) in vitro before infusion enhances anti-tumour function, improves in vivo persistence, and promotes complete tumour clearance. Upon T cell activation, glucose transporters Glut1 and Glut3 are both upregulated; however, TGR only promotes upregulation of Glut1, as Glut3 expression remains unchanged. Although glucose metabolism has previously been linked to IFN-γ production, the role of Glut1 in TGR CD8+ T cells remains unknown. Therefore, we aimed to investigate whether Glut1 contributes to the enhanced effector functions seen in TGR CD8+ T cells. Ovalbumin (OVA)-specific mouse T cells were activated using OVA peptide to generate effector T cells. To assess the role of Glut1, two different experimental models were used: genetic deletion or pharmacological inhibition of Glut1 after CD8+ T cell activation. These cells were then plated in either 10 (control) or 1mM (TGR) glucose. Metabolic pathways were assessed using Seahorse assays, where Extracellular Acidification Rate (ECAR) and Oxygen Consumption Rate (OCR) are used as proxies for glucose and mitochondrial metabolism, respectively. Effector function was assessed by co-culturing T cells with a B16-OVA melanoma cell line and measuring IFN-γ using flow cytometry. We found that both deletion and inhibition of Glut1 increases the OCR:ECAR ratio, with a more pronounced effect in the TGR condition, suggesting that Glut1 helps sustain glucose metabolism in TGR T cells. Additionally, deletion and inhibition of Glut1 dampens IFN-γ production, with a more pronounced decrease seen in TGR T cells. Together, these findings suggest that Glut1 contributes to the enhanced anti-tumour function seen in TGR T cells. Future studies may further explore the role of Glut1to uncover insights into the metabolically improved TGR CD8+ T cells, with the goal of broadening the application of ACT for different types of cancer.

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