The glycolysis/HIF-1α axis defines the inflammatory role of IL-4-primed macrophages.

T helper type 2 (Th2) cytokine-activated M2 macrophages contribute to inflammation resolution and wound healing. This study shows that IL-4-primed macrophages exhibit a stronger response to lipopolysaccharide stimulation while maintaining M2 signature gene expression. Metabolic divergence between canonical M2 and non-canonical proinflammatory-prone M2 (M2) macrophages occurs after the IL-4Rα/Stat6 axis. Glycolysis supports Hif-1α stabilization and proinflammatory phenotype of M2 macrophages. Inhibiting glycolysis blunts Hif-1α accumulation and M2 phenotype. Wdr5-dependent H3K4me3 mediates the long-lasting effect of IL-4, with Wdr5 knockdown inhibiting M2 macrophages. Our results also show that the induction of M2 macrophages by IL-4 intraperitoneal injection and transferring of M2 macrophages confer a survival advantage against bacterial infection in vivo. In conclusion, our findings highlight the previously neglected non-canonical role of M2 macrophages and broaden our understanding of IL-4-mediated physiological changes. These results have immediate implications for how Th2-skewed infections could redirect disease progression in response to pathogen infection.