Fig. 4.

ROS and metabolism in monocyte and macrophage subsets. Three monocyte subsets have been defined in humans with different functional properties. There is some evidence, from animal models, for interchange between these subsets during pathology. According to differentiation cues, monocytes can polarize into one of two distinctive macrophage phenotypes. Monocytes will polarize to pro-inflammatory M1 macrophages in the presence of LPS and IFNγ to produce O₂^-., NO., H₂O₂. In the presence of IL-4 and IL-13, monocytes differentiate to pro-resolving M2 macrophages with increased expression of anti-inflammatory cytokines and lipids.