ZBTB46 defines and regulates ILC3s that protect the intestine.

RORγt is a lineage-specifying transcription factor that is expressed by immune cells that are enriched in the gastrointestinal tract and promote immunity, inflammation and tissue homeostasis 1-15 . However, fundamental questions remain with regard to the cellular heterogeneity among these cell types, the mechanisms that control protective versus inflammatory properties and their functional redundancy. Here we define all RORγt + immune cells in the intestine at single-cell resolution and identify a subset of group 3 innate lymphoid cells (ILC3s) that expresses ZBTB46, a transcription factor specifying conventional dendritic cells 16-20 . ZBTB46 is robustly expressed by CCR6 + lymphoid-tissue-inducer-like ILC3s that are developmentally and phenotypically distinct from conventional dendritic cells, and its expression is imprinted by RORγt, fine-tuned by microbiota-derived signals and increased by pro-inflammatory cytokines. ZBTB46 restrains the inflammatory properties of ILC3s, including the OX40L-dependent expansion of T helper 17 cells and the exacerbated intestinal inflammation that occurs after enteric infection. Finally, ZBTB46 + ILC3s are a major source of IL-22, and selective depletion of this population renders mice susceptible to enteric infection and associated intestinal inflammation. These results show that ZBTB46 is a transcription factor that is shared between conventional dendritic cells and ILC3s, and identify a cell-intrinsic function for ZBTB46 in restraining the pro-inflammatory properties of ILC3s and a non-redundant role for ZBTB46 + ILC3s in orchestrating intestinal health.