Exosomes and exosome-like vesicles participate in cell-to-cell communication in animals, plant and bacteria. Dietary exosomes in bovine milk are bioavailable in non-bovine species, but a fraction of milk exosomes reaches the large intestine. Researchers from the University of Nebraska-Lincoln hypothesized that milk exosomes alter the composition of the gut microbiome in mice. C57BL/6 mice were fed AIN-93G diets, defined by their content of bovine milk exosomes and RNA cargos: exosome/RNA-depleted (ERD) versus exosome/RNA-sufficient (ERS) diets. Feeding was initiated at age three weeks and cecum content was collected at ages 7, 15 and 47 weeks. Microbial communities were identified by 16S rRNA gene sequencing. Milk exosomes altered bacterial communities in the murine cecum. The abundance of three phyla, seven families and 52 operational taxonomic units (OTUs) was different in the ceca from mice fed ERD and ERS (P < 0.05). For example, at the phylum level, Tenericutes were more than three-fold abundance in ERS mice at ages 15 and 47 weeks compared with ERD mice (P < 0.05). At the family level, Verrucomicrobiaceae were much less abundant in ERS mice compared with ERD mice age 47 weeks (P < 0.05). At the OTU level, four OTUs from the family of Lachnospiraceae were more than 2 times more abundant in ERS mice compared with ERD at age 7 and 47 weeks (P < 0.05). The researchers conclude that exosomes in bovine milk alter microbial communities in non-bovine species, suggesting that exosomes and their cargos participate in the crosstalk between bacterial and animal kingdoms.
Microbial families (heat map) in the cecum of mice fed exosome RNA-sufficient (ERS) or exosome RNA-depleted (ERD) diets at ages 7, 15 and 47 weeks. f, family; o, order; p, phylum.