Aiolos and Eos drive distinct human TH17 functional states.

CD4+ T helper (TH)-17 cells play a pivotal role in mucosal immune defense and are implicated in autoimmune diseases and cancer. Although Th17 cell plasticity is well-studied in mice, the factors driving their transition between pro-inflammatory and immunomodulatory states in humans remain less understood. Our study explored the transcriptional and epigenetic landscapes of single-cell cultures of human memory TH17 cells, focusing on clones that produce either immunomodulatory IL-10 or pro-inflammatory IFNγ and IL-22. We found that IL-10+ TH17 cells exhibit a T cell exhaustion-like profile with increased CTLA-4 expression and reduced IL-2 levels, while Ikaros zinc finger (IkZF) transcription factors, Aiolos and Eos, are differentially expressed in IL-10+ and IL-22+ TH17 cells, respectively. While exogenous IL-2 promotes IL-10 production in TH17 cells, lenalidomide induces IL-2 and promotes inflammatory TH17 cells, shifting TH17 cells towards a pro-inflammatory phenotype by reducing IL-10 and increasing IL-22 and IFNγ levels. Conversely, upregulation of Eos enhanced pro-inflammatory cytokine production. These findings highlight the crucial role of IkZF transcription factors in regulating human TH17 cell functions. Moreover, single-cell RNA sequencing of PBMCs from lenalidomide-treated patients confirmed an enrichment of inflammatory signatures, including interferon and IL-2/STAT5 pathways in TH17 cells. The ability to modulate this axis through targeted interventions, such as lenalidomide-induced Aiolos degradation or enforced Eos expression, presents new therapeutic opportunities for managing TH17 cell states in cancer and autoimmune diseases.