Deoxycorticosterone Reshapes CD8⁺ T Cell State and Effector Function Through Distinct Metabolic Signaling Programs

Background/Objectives: Whether individual endogenous corticosteroids exert distinct immunoregulatory effects on CD8⁺ T cells remains poorly understood. We investigated how deoxycorticosterone (DOC) affects CD8⁺ T cell state and function. Methods: Primary mouse CD8⁺ T cells were activated with anti-CD3/CD28 and IL-2 in the presence or absence of DOC. Flow cytometry was used to assess exhaustion-associated markers and effector function, and pharmacological perturbations were used to examine the involvement of AMP-activated protein kinase (AMPK), mechanistic target of rapamycin (mTOR), and protein kinase B (AKT) signaling. Results: DOC promoted an exhaustion-associated phenotype characterized by increased frequencies of PD-1⁺LAG-3⁺ and PD-1⁺TIM-3⁺ cells and elevated TOX expression. DOC concurrently impaired effector function, reducing IFN-γ/TNF co-production, granzyme B expression, and IL-2 production. Pharmacological inhibition of AMPK or activation of mTOR partially attenuated exhaustion-associated features induced by DOC, whereas AKT activation partially restored effector function. Conclusions: DOC directly reshapes CD8⁺ T cell state and function in vitro, with exhaustion-associated and effector responses exhibiting distinct pharmacological signaling dependencies. These findings identify DOC as a previously underappreciated endogenous corticosteroid capable of modulating CD8⁺ T cell biology.