Neonatal diet impacts circulatory miRNA profile in a porcine model

Authors: CARR, LAURA - Arkansas Children'S Nutrition Research Center (ACNC); BOWLIN, ANNE - Arkansas Children'S Nutrition Research Center (ACNC); ELOLIMY, AHMED - Arkansas Children'S Nutrition Research Center (ACNC); BYRUM, STEPHANIE - University Arkansas For Medical Sciences (UAMS); WASHAM, CHARITY - University Arkansas For Medical Sciences (UAMS); RANDOLPH, CHRISTOPHER - Arkansas Children'S Nutrition Research Center (ACNC); MACLEOD, STEWART - Arkansas Children'S Nutrition Research Center (ACNC); YERUVA, LAXMI - Arkansas Children'S Nutrition Research Center (ACNC)

Submitted to: Frontiers in Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/18/2020
Publication Date: 6/23/2020
Citation: Carr, L.E., Bowlin, A.K., Elolimy, A.E., Byrum, S.D., Washam, C.L., Randolph, C.E., Macleod, S.L., Yeruva, L. 2020. Neonatal diet impacts circulatory miRNA profile in a porcine model. Frontiers in Immunology. 11:1240. https://doi.org/10.3389/fimmu.2020.01240.
DOI: https://doi.org/10.3389/fimmu.2020.01240

Interpretive Summary: Breastfeeding is associated with positive health outcomes such as decreased rates of infections, obesity, and allergies. However, the exact mechanisms that make breastfeeding better for infants are still unclear. To address this, we utilized a piglet model fed either human breastmilk or dairy-based milk formula until postnatal day 21, and weaned to solid diet until postnatal day 51 to model neonatal feeding similar to human infants. Serum levels of microRNAs (unique secreted factors that regulate the expression of genes in tissues) were measured on days 21, 35, and 51 using small RNA sequencing. Specialized computer software was used to determine the impacted biological pathways predicted to be altered in the formula fed group versus human milk fed group. We observed differential expression of blood miRNA. The total differentially expressed miRNA was greater at postnatal day 51 than at days 21 and 35 (27 vs. 24 and 8, respectively), suggesting a persistent effect of the neonatal diet on miRNA expression. Pathway analysis suggested that many of the miRNAs were involved in immune function. Future studies will determine the specific role of the miRNAs in the health effects of breastfeeding.

Technical Abstract: MicroRNAs (miRNAs) are conserved non-coding small nucleotide molecules found in nearly all species and breastmilk. miRNAs present in breastmilk are very stable to freeze-thaw, RNase treatment, and low pH as they are protected inside exosomes. They are involved in regulating several physiologic and pathologic processes, including immunologic pathways, and we have demonstrated better immune response to vaccines in piglets fed with human milk (HM) in comparison to dairy-based formula (MF). To understand if neonatal diet impacts circulatory miRNA expression, serum miRNA expression was evaluated in piglets fed HM or MF while on their neonatal diet at postnatal day (PND) 21 and post-weaning to solid diet at PND 35 and 51. MF fed piglets showed increased expression of 14 miRNAs and decreased expression of 10 miRNAs, relative to HM fed piglets at PND 21. At PND 35, 9 miRNAs were downregulated in the MF compared to the HM group. At PND 51, 10 miRNAs were decreased and 17 were increased in the MF relative to HM suggesting the persistent effect of neonatal diet. miR-148 and miR-181 were decreased in MF compared to HM at PND 21. Let-7 was decreased at PND 35 while miR-199a and miR-199b were increased at PND 51 in MF compared to HM. Pathway analysis suggested that many of the miRNAs are involved in immune function. In conclusion, we observed differential expression of blood miRNAs at both PND 21 and PND 51. miRNA found in breastmilk were decreased in the serum of the MF group, suggesting that diet impacts circulating miRNA profiles at PND 21. The miRNAs continue to be altered at PND 51 suggesting a persistent effect of the neonatal diet. The sources of miRNAs in circulation need to be evaluated, as the piglets were fed the same solid diet leading up to PND 51 collections. In conclusion, the HM diet appears to have an immediate and persistent effect on the miRNA pro'le and likely regulates the pathways that impact the immune system and pose benefits to breastfed infants.