Dysregulation of CD8(+) T cell function in the setting of altered cytokine signaling due to inborn errors of immunity

Abstract A key outcome of chronic antigenic stimulation in the setting of sustained inflammation is the development of CD8+ T cell exhaustion. However, the relative roles of inflammation and antigen stimulation on T cell dysfunction remain unclear. Inborn errors of immunity (IEIs) provide an opportunity to study the effect of genetic alterations in signaling pathways on immune function. Here, we focus on an IEI resulting from genetically amplified cytokine signaling: gain-of-function mutations in STAT3 (STAT3 GOF). STAT3 signals downstream of multiple inflammatory cytokines (e.g., IL-6 and IL-27) and we used STAT3 GOF as a genetic mimic of chronic inflammation. To assess how amplified STAT3 signaling impacts immune cell subset distribution and activation status, PBMCs from STAT3 GOF patients and age-matched healthy controls were profiled via mass cytometry (CyTOF). This revealed altered states of CD8+ T cell activation including increased expression of immunoregulatory receptors (e.g., PD-1 and CD39). STAT3 GOF CD8+ T cells also showed impaired cytokine production and reduced proliferative capacity. Bulk RNA sequencing of naïve STAT3 GOF CD8+ T cells identified an exhausted-like transcriptional profile. Quantitation of metabolic function shows alterations in glucose use and oxidative phosphorylation in STAT3 GOF. Our studies suggest that inflammation alone may directly impair CD8+ T cell function. Understanding the mechanisms by which inflammation impacts T cell function may identify components of T cell dysregulation that can be targeted therapeutically in these rare patients, as well as those with more common inflammatory diseases (e.g., obesity) with shared aspects of T cell dysfunction. Supported by CHOP Research Institute, The Primary Immune Deficiency Treatment Consortium (PIDTC) and Immune Deficiency Foundation (IDF).