Amplified STAT3 signaling alters expression of CD39 in STAT3 gain-of-function (STAT3 GOF) and in healthy donor CD8 +T cells

Abstract

Abstract It is still unknown whether primary immune regulatory disorders (PIRD) due to genetic variants that amplify T cell receptor and/or inflammatory cytokine signaling yield T cell exhaustion. Here, we investigate the impact of dysregulated cytokine signaling on CD8 +T cells in STAT3 gain-of-function (STAT3 GOF) patients. Immune profiling via 43-parameter CyTOF reveals altered CD8 +T cell differentiation, including loss of naïve cells, increased frequency of effector memory and T EMRAcells, and downregulation of markers of stemness (i.e., TCF-1 and CD127) in STAT3 GOF. Additionally, STAT3 GOF CD8 +T cells demonstrate decreased IL-2 production and proliferation. We identify increased expression of the ecto-enzyme, CD39, which has been reported on exhausted cells and hydrolyzes extracellular ATP, on CD8 +T cells from STAT3 GOF patients and in a mouse model of STAT3 GOF. To identify the signals regulating CD39, healthy donor CD8 +T cells were cultured with STAT3-activating cytokines alone but did not upregulate CD39. However, TCR engagement led to robust CD39 expression which was further augmented with STAT3-activating cytokines. Specifically, CD39 upregulation occurs in pSTAT3 Y705+cells. Finally, sorted CD39 +CD8 +T cells hydrolyzed ATP and suppressed effector CD8 +T cell proliferation compared to CD39 −CD8 +T cells. These data suggest that STAT3 signaling may play a role in regulating CD39 levels and thus contribute to CD8 +T cell exhaustion, which will be explored in future work. Understanding how dysregulated STAT3 signaling impacts T cell function in these rare patients can improve our understanding of this complex disease and may yield insights into shared aspects of T cell dysfunction found in more common inflammatory diseases. HHMI Gilliam Fellowship for Advanced Studies (GT15736) Penn Presidential Fellowship PIDTC (Henrickson Lab) IDF (Henrickson Lab) NIH NIAD K08AI135091 (Henrickson Lab) Burroughs Wellcome Fund CAMS (Henrickson Lab)