According to the previous study of Richardson et al. [8], they revealed that NOD2 inhibits TLR4 signaling in the intestinal epithelium in vivo and in vitro experiments with lower NOD2 and more TLR4 receptors, which could explain the change of the NOD2 and TLR4 in NEC rats in our study. Here, NOD2 is linked to necrotizing enterocolitis.