Our ligand–receptor analysis indicated that NEC epithelial cells interact with macrophages through elevated levels of TNFSF9 (Fig 6H), and NK cells signal to NEC epithelial cells via IL1B-IL1R1/IL1R2 and GZMB-PGRMC1 (Fig 6I). This evidence concerns the gene PGRMC1 and necrotizing enterocolitis.