Restriction of innate Tγδ17 cell plasticity by an AP-1 regulatory axis

Interleukin-17 (IL-17)-producing γδ T (Tγδ17) cells are innate-like mediators of intestinal barrier immunity. Although IL-17-producing helper T cell and group 3 innate lymphoid cell plasticity have been extensively studied, the mechanisms governing Tγδ17 cell effector flexibility remain undefined. Here, we combined type 3 fate mapping with single-cell ATAC-sequencing/RNA-sequencing multiome profiling to define the cellular features and regulatory networks underlying Tγδ17 cell plasticity. During homeostasis, Tγδ17 cell effector identity was stable across tissues, including for intestinal T-bet⁺ Tγδ17 cells that restrained interferon-γ production. However, Salmonella enterica subsp. enterica serovar Typhimurium infection induced intestinal V_γ6⁺ Tγδ17 cell conversion into type 1 effectors, with loss of IL-17A production and partial RORγt downregulation. Multiome analysis revealed a trajectory along V_γ6⁺ Tγδ17 cell effector conversion, with TIM-3 marking ex-Tγδ17 cells with enhanced type 1 functionality. Last, we characterized and validated a critical AP-1 regulatory axis centered around JUNB and FOSL2 that controls V_γ6⁺ Tγδ17 cell plasticity by stabilizing type 3 identity and restricting type 1 effector conversion.