RESUMO
BACKGROUND: 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. OBJECTIVE: 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. METHODS: Using quantitative approach qRT-PCR, we analyzed immune-related microRNAs in both, colostrum and HM. RESULTS: Our study provided evidence of a comparable profile of immune specific miRNAs in colostrum and HM. Although we detected all the four miRNAs tested, we point out the prevalence of hsamiR- 181a and hsa-miR-223 indicative to act on T and granulocytes cell populations as selective targets. Therefore, these biomolecules could affect newborn's immune homeostasis at early stages of life. While, variation in immune-related miRNAs was found in HM amongst lactating women, it was not evidenced in colostrum. Of interest, pasteurization procedure did not alter the distribution or the expression profile of the miRNAs tested in both colostrum and HM. Herein, we also proposed a simple method to determine the quantity of these biomolecules in biological fluids. CONCLUSION: 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.