Tissue signals imprint ILC2 identity with anticipatory function [single cell RNA-Seq]

Group 2 innate lymphoid cells (ILC2s) are distributed systemically and produce type 2 cytokines in response to a variety of stimuli, including the epithelial cytokines interleukin (IL)-25, IL-33, and thymic stromal lymphopoietin (TSLP). Transcriptional profiling of ILC2s from different tissues, however, grouped ILC2s according to their tissue of origin, even in the setting of combined IL-25, IL-33R and TSLPR-deficiency. Single-cell profiling confirmed a tissue-organizing transcriptome and identified ILC2 subsets expressing distinct activating receptors, including the major subset of skin ILC2s, which were activated preferentially by IL-18. Tissue ILC2 subsets were normal in germ- free mice, suggesting that endogenous, tissue-derived, signals drive the maturation of ILC2 subsets by controlling expression of distinct patterns of activating receptors, thus anticipating tissue-specific patterns to perturbations occurring later in life. Overall design: 8-14 week old ILC2 reporter mice were used to sort steady-state activated ILC2 from bone marrow, lung, visceral adipose tissue, small intestine lamina propia and skin.