Amplified STAT3 increases expression of the CD39 ectoenzyme and impairs function of CD8+ T cells.

Abstract

Abstract Regulation of T cell signaling is paramount to mount an appropriate immune response and protect the host from pathophysiology. Here, we study the impact on CD8+ T cells in monogenic inborn error of immunity patients exhibiting dysregulated signal 3 (cytokine signaling) pathways resulting from STAT3 gain- or loss-of-function variants (STAT3 GOF and STAT3 LOF). Using high dimensional immune profiling, we demonstrate increased expression of the ectoenzyme, CD39, which hydrolyzes extracellular ATP, on STAT3 GOF patient CD8+ T cells. Moreover, CD8+ T cells from two mouse models of STAT3 GOF (STAT3+/G421R and NOD-STAT3+/K392R) recapitulated this increase in CD39. In vitro, STAT3-activating cytokines (e.g., IL-6, IL-21, IL-27, IL-10) augment CD39 induction in a TCR-dependent manner in healthy donor and in STAT3 GOF CD8+ T cells. In contrast, STAT3 LOF patients show diminished CD39 induction. We find a positive correlation between CD39 induction and phosphorylated STAT3 levels while STAT3 inhibition prevents this cytokine-driven augmentation of CD39. Finally, acutely activated, and sorted CD39+CD8+ T cells from healthy donors inhibit bystander CD8+ T cell cytokine production (e.g., IFN-g). Pharmacologic inhibition of CD39 enzymatic activity or genetic ablation via CRISPR/Cas9 editing reversed decreases in cytokine production. Together, our data demonstrate a mechanistic connection between amplified STAT3 signaling and CD39 levels which is capable of impairing CD8+ T cell function.