MiRNA profiling of plasma-derived exosomes from dairy cows during gestation.

Exosomes, one kind of extracellular vesicles, are released under abnormal and normal physiological conditions. An understanding of plasma-derived exosomal microRNA (miRNA) profiles during pregnancy will significantly contribute to knowledge of maternal-fetal communication in ruminants. In this study, we isolated plasma-derived exosomes from dairy cows during early (∼60 days, gestational day (G_D) 60), mid (∼150 days, G_D 150) and late (∼240 days, G_D 240) pregnancy. Exosomal miRNA profiles were revealed using RNA sequencing technology, and the abundance of exosomal miRNAs between each stage were compared. In the G_D150 vs. G_D60, G_D240 vs. G_D60 and G_D240 vs. G_D150stages, there were 23, 32 and 29 miRNAs, respectively, significantly differentially enriched. Significant annotations for protein binding and transport- or immunoregulatory-related categories or pathways were found for the predicted target genes of these miRNAs. In addition, we further identified specific exosomal miRNAs for each pregnancy stage, including the following: bta-miR-499, bta-miR-16a, bta-miR-20a, bta-miR-223, and bta-miR-128 in the G_D60 stage; bta-miR-493, bta-miR-127, and bta-miR-143 in the G_D150 stage; and bta-miR-122, bta-miR-182, bta-miR-183, bta-miR-200b, and bta-miR-200c in the G_D240 stage. Our findings provide new insight into maternal-fetal communication during pregnancy. Future studies will use these data to identify and characterize specific exosomal miRNA regulatory mechanisms in the maternal-fetal immune response.