Figure 3. Cooperative actions of innate cells activate M2 macrophages.

M2 macrophages can be induced by multiple mechanisms in the context of helminth infection. Type 2 cytokines, produced by ILC2s, basophils, mast cells, eosinophils and neutrophils contribute to M2 macrophage responses. Additionally, epithelial cells release adenosine in response to the helminth-induced damage, which further amplifies M2 macrophage activation. However, whether these signals differentially act on tissue-resident and monocyte-derived macrophages remains unknown. Further, whether neuronal-derived signals also regulate macrophage activation has not been determined.