Study on the levels of microRNA-146b, microRNA-155 and microRNA-30b in human milk and their correlation with maternal and infant health

Abstract

Objective To explore the expression levels of immune-related microRNA-146b(miR-146b), microRNA-155(miR-155) and microRNA-30b(miR-30b) in human breast milk and its relationship with maternal and infant's health. Methods One hundred and thirty-four mothers and their infants from obstetrical department were recruited in the study after delivery.The subjects were divided into 2 groups, breast feeding group(n=86) and formula-fee-ding group(n=48), and were followed up 3 months after delivery.Breast milk samples were collected at 2-5 days after delivery(colostrum) and 3 months after delivery(mature milk). The expression levels of microRNAs in milk samples were detected by real-time PCR.The relationship between levels of microRNAs and maternal and infant-related factors was analyzed. Results 1.MiR-146b, miR-155 and miR-30b expressions were abundant both in human colostrums(5.950±0.823, 3.899±0.920, 4.057±0.604) and mature milk(4.840±0.805, 2.128±0.969, 4.929±0.566). The levels of miR-146b and miR-155 were higher in colostrum than that of mature milk(t=7.716, 10.215, all P<0.01), while the level of miR-30b was higher in mature milk than that of colostrums(t=-8.626, P<0.01).2.Additionally, the level of miR-30b was negatively correlated with maternal pre-pregnancy body mass index(r=-0.298, P<0.01).3.The levels of miR-146b and miR-30b were higher in mothers giving birth by vaginal delivery than those who underwent cesarean section(t=2.356, 3.108, all P<0.05).4.The levels of miR-146b and miR-155 were higher in colostrum-fed girls than boys(t=-2.204, -2.985, all P<0.05).5.The level of miR-146b in mature milk was negatively correlated with 3-month-old infant's Z score of body weight(r=-0.425, P<0.05) and body length(r=-0.569, P<0.01).6.During follow-up, the incidence of baby eczema in breast feeding group(8.82%, 3/34 cases) was lower than that in formula milk feeding group(29.17%, 14/48 cases) (χ2 = 5.012, P=0.025). Conclusions The levels of immunocompetent microRNAs in human milk are influenced by the lactation period, maternal pre-pregnancy body mass index, mode of delivery and infant sex.The immune-related microRNAs in human milk could be involved in the regulation of infant's immunity and growth. Key words: Human milk; Immunity; MicroRNA-146b; MicroRNA-155; MicroRNA-30b; Maternal and infant health