Figure 2. ILCs promote acute inflammation to mediate innate immunity to pathogens.
ILCs promote innate immune responses to a number of pathogens in the intestine. (a) ILC1 promote innate immunity to intracellular pathogens, such as Toxoplasma gondii, by producing TNF and IFNγ in response to DC-derived IL-12 and subsequently promoting recruitment of inflammatory myeloid cells. (b) Following infection with the helminth parasites Nippostrongylus brasiliensis or Trichuris muris, ILC2 produce IL-13 in response to epithelial-cell derived-IL-25 and IL-33, which increases smooth muscle contractility and mucus production from goblet cells. (c) ILC3 produce IL-17 and IL-22 in response to DC-derived IL-23 and IL-1β, which promotes innate immunity to fungi and extracellular bacteria, such as Citrobacter rodentium and Candida albicans. IL-17 and IL-22 promote neutrophil recruitment to the intestine and the production of antimicrobial peptides from IECs.