Aiolos restrains the acquisition of cytotoxic features by CD4+ T cells

Abstract

Abstract Classically, CD4+ T cells have been defined as “helper” type cells, providing aid to other immune cell populations via the secretion of cytokines and direct cell-cell interactions. More recently, a subset of CD4+ T cells with cytotoxic capabilities, termed CD4+ cytotoxic T lymphocytes (CD4-CTLs), have been observed in both mice and humans, performing protective functions in the settings of infection and cancer while conversely contributing to the pathogenesis of autoimmunity. Despite their well-documented importance in several disease contexts, the complete mechanisms that underlie their differentiation and function remain unknown. Here, we identify the Ikaros family member, Aiolos, as a novel regulator of CD4+ CTL differentiation and function. We find that Aiolos deficiency results in increased expression of key CD4+ CTL transcription factors and effector molecules both in vitro and in an in vivo murine model of influenza infection. Mechanistically, we find that Aiolos deficiency results in increased IL-2/STAT5 signaling, supporting a repressive role for Aiolos in CD4+ CTL differentiation via negative regulation of the IL-2/STAT5 pathway. Collectively, this work identifies Aiolos as a novel negative regulator of CD4+ cytotoxic gene programming, and thus may represent a therapeutic target for the treatment of autoimmune diseases and enhanced anti-tumor immunity. Sponsored by a grant from NIAID (NIH-RO1 AI134972) and funds through The Ohio State University College of Medicine