Eosinophils in the visceral adipose tissue (VAT) contribute to the maintenance of alternatively activated (M2) macrophages and insulin sensitivity. In The Journal of Experimental Medicine, Locksley and colleagues show that innate lymphoid type 2 cells (ILC2 cells) resident in the VAT promote the accumulation of eosinophils through the production of interleukin 5 (IL-5) and IL-13. ILC2 cells are the main producers of these cytokines in the VAT in the basal state or after IL-33-mediated activation. Deficiency in IL-5 or IL-13, depletion of ILC2 cells or consumption of a high-fat diet, which induces loss of adipose ILC2 cells, results in fewer eosinophils and M2 macrophages in the VAT, whereas helminth infection increases the number of eosinophils in the VAT in an ILC2 cell–dependent manner. These results indicate a role for ILC2 cells in metabolic homeostasis, probably through the maintenance of an anti-inflammatory state.

J. Exp. Med. (18 February 2013) doi:10.1084/jem.20121964