Prenatal inflammation remodels lung immunity and function by programming ILC2 hyperactivation

We examined how prenatal inflammation shapes tissue function and immunity in the lung by reprogramming tissue-resident immune cells from early development. Maternal, but not fetal, type I interferon-mediated inflammation provoked expansion and hyperactivation of group 2 innate lymphoid cells (ILC2s) seeding the developing lung. Hyperactivated ILC2s produced increased IL-5 and IL-13, were associated with acute Th2 bias, decreased Tregs, and persistent lung eosinophilia into adulthood. ILC2 hyperactivation was recapitulated by adoptive transfer of a fetal liver precursor following prenatal inflammation, indicative of developmental programming at the fetal progenitor level. Reprogrammed ILC2 hyperactivation and subsequent lung immune remodeling, including persistent eosinophilia, was associated with worsened histopathology and increased airway dysfunction equivalent to papain exposure, indicating increased asthma susceptibility in offspring. Our data elucidate a potential mechanism by which early-life inflammation results in increased asthma susceptibility, driven by hyperactivated ILC2s that drive persistent changes to lung immunity during perinatal development. Overall design: Single-cell RNA sequencing of ILC2s sorted from neonatal (postnatal day 14) mouse lung after prenatal saline or poly(I:C) treatment (embryonic day E14.5).