Variation in Immune-Related microRNAs Profile in Human Milk Amongst Lactating Women

Human Milk (HM) is a biological fluid representing the first nutrient for newborns. It directly impacts the development of the infant's immune system. In this concern, specific microRNAs (miRNAs) such as hsa-miR-21, hsa-miR-181a, hsa-miR-150 and hsa-miR-223 are known to be involved in the innate and acquired immune response. Herein, these miRNAs were evaluated in frozen and pasteurized samples of human colostrum and HM in order to elucidate the distribution and the expression profile of these biological mediators in both biological fluids. Our study provided evidence of a comparable profile of immune specific miRNAs in colostrum and HM for hsamiR- 181a and hsa-miR-223 indicative to act on T and granulocytes cell populations as selective targets. These biomolecules could affect newborn's immune homeostasis at early stages of life. Of interest, pasteurization procedure did not alter the distribution or the expression profile of the miRNAs tested in both colostrum and HM. Considering, this evidence the variation in immune-related miRNAs should be take into account and could be relevant for preterm and hospitalized infants who usually received pasteurized HM from donors.