Bovine Colostrum miR-30a-5p Targets the NF-κB Signaling Pathway to Alleviate Inflammation in Intestinal Epithelial Cells

Inflammatory bowel disease (IBD) is a common disease of the digestive system, and an excessive immune response mediated by the nuclear factor κ-B (NF-κB) signaling pathway is an essential etiology. Recent studies have found that bovine milk exosomes can improve intestinal mucosal health by delivering microRNA (miRNA), but the mechanism of action is so far unknown. In the present study, we analyzed the differential expression profiles of miRNA in colostrum and mature milk exosomes using high-throughput sequencing, based on the demonstration that colostrum exosomes inhibit the lipopolysaccharide (LPS)-induced intestinal epithelial NF-κB inflammatory pathway better than mature milk exosomes. The bta-miR-30a-5p, which is specifically highly expressed in colostrum, was screened, and its predicted target gene TRAM was found to be closely related to the NF-κB signaling pathway by functional enrichment analysis. Further, we used gene overexpression and silencing techniques and found that the bta-miR-30a-5p transfection treatment was confirmed to inhibit LPS-induced NF-κB signaling pathway activation and downstream pro-inflammatory factor expression, while the expression of its potential target gene, TRAM, was also suppressed. It is hypothesized that the high expression of bta-miR-30a-5p in colostrum, which targets TRAM to inhibit the downstream NF-κB inflammatory pathway, may be one of the molecular mechanisms responsible for its superior effect on resisting inflammatory attack compared to mature milk.