IRF5 and necrotizing enterocolitis: It has been recently reported that IRF5 acts as a key regulator of M1 macrophage responses in newborns,19 and our previous report confirmed that M1 macrophages promote NEC.20 Regarding the crucial role of IRF5 in M1 macrophage polarization, we hypothesized that Irf5 deficiency in macrophages may prevent NEC.