TLR4 and necrotizing enterocolitis: After adding the NOD2 inhibitor on the NEC + Astaxanthin group, the NOD2 expression in intestinal tissues was reduced but the expressions of the TLR4, NF-κB, and MyD88 in intestinal tissues were elevated in relative to the NEC + Astaxanthin group (P < 0.05 or P < 0.01).