Innate lymphoid cells in the intestines and the role of dietary compounds.

Abstract

The incidence of intestinal related diseases such as inflammatory bowel disease annually increases and progress in research is impeded by the complexity of the intestinal environment characterized by interactions of the host, commensal and diet compartment. The host immune system in the gut recently gained a new cell type namely the innate lymphoid cells (ILC) which are classified in three families and exhibit functions ranging from lymphoid organogenesis and tissue remodelling to cytotoxicity and immunity against pathogens. Since the diet has been shown to have a large impact on gut immunity, the association with ILCs is currently being investigated. Exogenous AhR ligands and vitamins were found to ensure a tolerogenic environment in the intestines suggesting a beneficial role during periods of excessive inflammation. However, studies which focus on vitamin A, obtained contradictory findings indicating that the effect cannot be studied in the absence of other factors such as the endogenous cytokines TGFβ or IL-15. Both AhR ligands and vitamins determine the outcome of developmental or functional mechanisms concerning ILCs. In this review we report the different ILC families and an update of findings regarding dietary influences on ILCs in the intestines.