The Molecular and Epigenetic Mechanisms of Innate Lymphoid Cell (ILC) Memory and its Relevance for Asthma. The Molecular and Epigenetic Mechanisms of Innate Lymphoid Cell (ILC) Memory and its Relevance for Asthma

Repetitive exposure of Rag1-/- mice to the Alternaria allergen extract generated a form of memory that elicited an asthma-like response upon a subthreshold recall challenge 3-15 weeks later. This memory was associated with lung ICOS+ST2+ILC2s. Genetic, pharmacologic and antibody-mediated inhibition, and adoptive transfer established an essential role for ILC2s in memory-driven asthma. ATAC-seq demonstrated a distinct epigenetic landscape of memory ILC2s, and identified Bach2 and AP1 (JunD and Fosl2) motifs as major drivers of altered gene accessibility. scRNA-seq, gene knockout and signaling studies suggest that repetitive allergenic stress induces a gene repression program involving Nr4a2, Zeb1, Bach2, and JunD, and a preparedness program involving Fhl2, FosB, Stat6, Srebf2 and MPP7 in memory ILC2s. A mutually regulated balance between these two programs establishes and maintains memory. The preparedness program (e.g. Fhl2) can be activated with a subthreshold cognate stimulation, which downregulates repressors and activates effector pathways to elicit the memory-driven phenotype. Overall design: Total 17 samples. 11 samples from Rag1 KO mice and 6 samples from wild-type C57B/6 mice. Study groups: 1) Alt/Alt: mice senstized with the Alternaria allergen (Alt) and underwent recall challenge with Alt; 2) Alt/-:mice sensitized with Alt and underwent no (-) recall challenge; 3) Sal/Alt: mice senitized with saline (Sal) and underwent recall challenge with Alt. 4) Sal/-: mice sensitized with Sal and underwent no (-) recall challenge. Each groups had three replicates except Alt-; which had two biological replicates. 6 samples were from wild type C57BL/6 mice. This study had two groups Alt/Alt and Sal/Alt,each groups had three bilogical replicates.