To further define the nature of the predominant macrophage population (subgroup 0) in the NEC group, we examined key inflammatory factors and chemokines, such as IL-1β, IL-6, CCL3, CCL4, etc. The expression levels of these genes were significantly higher in the predominant macrophage population (subgroup 0) of the NEC group compared to the control group’s predominant macrophage population (subgroup 1) (Fig. 2C). Here, CCL3 is linked to necrotizing enterocolitis.