Human Breast Milk-Derived Exosomal miR-148a-3p Protects Against Necrotizing Enterocolitis by Regulating p53 and Sirtuin 1.

Necrotizing enterocolitis (NEC) is a gastrointestinal disease that results in the exaggerated intestinal inflammation and injury. Human breast milk-derived exosome (BMEXO) 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 BMEXO remains unclear. We established a NEC mouse model, and miRNA sequencing was performed to determine the miRNA profiling in BMEXO. 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 BMEXO treatment exerts a significant protective effect on NEC mice, including inhibiting inflammation and improving intercellular tight junctions. Additionally, as the most abundant miRNA in BMEXO, 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 BMEXO 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.