Epigenome analyses implicate ILC2s as key mediators of allergic airway inflammation

Group 2 innate lymphoid (ILC2) cells are major producers of the cytokines that drive allergic asthma and elevated levels of ILC2s have been detected in the blood and sputum of asthma patients. Asthma susceptibility has strong (epi)genetic components, but the underlying mechanisms and whether they are linked to ILC2 biology remain unclear. To reveal the molecular basis of ILC2 function in allergic airway inflammation (AAI) and assess its relevance for understanding how genetic variation affects asthma susceptibility. Gata3-IRES-YFP reporter mice were used to isolate ILC2s from bronchoalveolar lavage fluid and lymph nodes. Human naive ILC2s were purified from peripheral blood and activated in vitro. We employed RNA-Seq, ChIPm-Seq and computational approaches to study the transcriptome and epigenome in the context of ILC2 activation, tissue-specific functions and genetic susceptibility to asthma. Activated ILC2s displayed a tissue-specific gene expression signature that emerged from a highly similar epigenome. We identify superenhancers - a class of regulatory regions susceptible to epigenetic drugs - controlling ILC2 identity and asthma-associated genes. The majority of genes implicated in asthma by genome-wide association studies resided in an active or primed state in ILC2s. A substantial number of asthma-associated genetic variants were found in ILC2 gene regulatory elements. Our genome-wide analyses reveal new potential functions for ILC2s in AAI, which possess a plastic and flexible epigenome. Importantly, we reveal a strong link between gene regulatory mechanisms in ILC2s and the (epi)genetic basis of asthma susceptibility, supporting a pathogenic role for ILC2s in human asthma. Biological replicate (n=2-4) ChIP-Seq and RNA-Seq