Let-7d-5p suppresses inflammatory response in neonatal rats with necrotizing enterocolitis via LGALS3-mediated TLR4/NF-κB signaling pathway.

Necrotizing enterocolitis (NEC) is an acute intestinal condition accounting for severe mortality and morbidity in preterm infants. This study aimed to identify the possible roles of let-7d-5p in neonatal rats with NEC. The differentially expressed genes (DEGs) related to NEC were initially screened in silico. After establishment of NEC rat models, the measurement of the expression of let-7d-5p, galectin-3 (LGALS3), toll-like receptor 4 (TLR4) and nuclear factor kappa B (NF-κB) as well as proinflammatory cytokines (TNF-α, IL-1b and IL-6) was conducted. The interaction between let-7d-5p and LGALS3 or Argonaute2 (AGO2) was identified. Gain- and loss-function approaches were then performed in an attempt to investigate the regulatory roles of let-7d-5p and LGALS3 in inflammation and cell apoptosis in NEC neonatal rats. Let-7d-5p was poorly expressed, while LGALS3, TLR4 and NF-κB were highly expressed in the intestinal tissues of NEC rats. Over-expression of let-7d-5p resulted in decreased levels of proinflammatory factors in the intestinal tissues of NEC rats. Through sequential experimentation, let-7d-5p was identified to target LGALS3 and bind to AGO2. In addition, LGALS3 silencing or LPS treatment blocked the TLR4/NF-κB signaling pathway, thereby suppressing intestinal epithelial cell apoptosis and inflammation in NEC. Collectively, let-7d-5p might exercise its inhibitory properties in the inflammatory response and intestinal epithelial cell apoptosis in NEC neonatal rats via inactivation of the LGALS3-dependent TLR4/NF-κB signaling pathway.