In accordance with the impaired function of PMN-MDSCs, DhpsΔLysm pups exhibited exacerbated severity of NEC compared with Dhpsfl/fl controls, which was characterized by decreased survival rates, heightened intestinal inflammation, elevated expression of proinflammatory genes (Il1b and Tnfa), downregulated expression of an antiinflammatory gene (Il10), and increased bacterial abundance in the intestinal wall (Figure 7, G–J). Here, IL1B is linked to necrotizing enterocolitis.