Adventitial stromal cells define group 2 innate lymphoid cell tissue niches

We identify a subset of IL-33 expressing adventitial stromal cells as local regulators of ILC2s Type 2 lymphocytes promote both physiologic tissue remodeling and allergic pathology, yet their physical tissue niches are poorly described. In this study, we used quantitative imaging together with scRNAseq to define tissue niches of group 2 innate lymphoid cells (ILC2s), critical instigators of type 2 immunity. We identified a dominant adventitial cuff niche around lung bronchi and larger vessels in multiple tissues, where ILC2s localized with subsets of dendritic and regulatory T cells. However, ILC2s were most intimately associated with adventitial stromal cells (ASC), a mesenchymal fibroblast-like subset that expressed Interleukin-33 (IL-33) and thymic stromal lymphopoietin (TSLP) and supported ILC2s and tissue-resident Th2 cells. Analysis of CD45- stromal cells in lung and adipose tissue