Human Breast Milk-Derived Exosomal miR-148a-3p Protects Against Necrotizing Enterocolitis by Regulating p53 and...

Necrotizing enterocolitis (NEC) is a gastrointestinal disease that results in the exaggerated intestinal inflammation and injury. Human breast milk-derived exosome (BM^EXO) has been reported to relieve NEC, which is closely related to the contained microRNAs (miRNAs). However, which miRNA and whether its synthesized mimic can replace the protection of BM^EXO remains unclear. We established a NEC mouse model, and miRNA sequencing was performed to determine the miRNA profiling in BM^EXO. The downstream target of miRNA was then confirmed by dual-luciferase reporter assay. Finally, we explored the protective effect of a single miRNA agomir on NEC and its downstream mechanisms. The results revealed that BM^EXO treatment exerts a significant protective effect on NEC mice, including inhibiting inflammation and improving intercellular tight junctions. Additionally, as the most abundant miRNA in BM^EXO, miR-148a-3p directly targets Tp53 on its 3' untranslated region (3' UTR). miR-148a-3p mimic treatment significantly reduces p53 expression and upregulates sirtuin 1 (SIRT1) level in the lipopolysaccharide (LPS)-treated intestinal epithelial IEC6 cells. In addition, decreased nuclear translocation of nuclear factor-κB (NF-κB) and cell apoptosis were observed by miR-148a-3p mimic. Also, delivery of miR-148a-3p agomir in vivo exerts a similar protective role on NEC as BM^EXO treatment, accompanied by changes in p53 and SIRT1. Finally, the abolition of the protection of miR-148a-3p agomir on NEC was observed in a Sirt1-deficient (Sirt1^+/-) mouse. Collectively, our present study demonstrated that the miR-148a-3p/p53/SIRT1 axis has a considerable protective effect on NEC, and the agomir therapy provides a new treatment strategy for NEC.