Exploring the associations between microRNA expression profiles and environmental pollutants in human placenta from the National Children’s Study (NCS)

The placenta is the principal regulator of the in utero environment, and disruptions to this environment can result in adverse offspring health outcomes. To better characterise the impact of in utero perturbations, the authors assessed the influence of known environmental pollutants on the expression of microRNA (miRNA) in placental samples collected from the National Children’s Study (NCS) Vanguard birth cohort. This study analysed the expression of 654 miRNAs in 110 term placentas. Environmental pollutants measured in these placentas included dichlorodiphenyldichloroethylene (DDE), bisphenol A (BPA), polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), arsenic (As), mercury (Hg), lead (Pb), and cadmium (Cd). A moderated t-test was used to identify a panel of differentially expressed miRNAs, which were further analysed using generalised linear models. The authors observed 112 miRNAs consistently expressed in >70% of the samples. Consistent with the literature, miRNAs located within the imprinted placenta-specific C19MC cluster, specifically mir-517a, mir-517c, mir-522, and mir-23a, are among the top expressed miRNA in our study. A positive association was observed between PBDE 209 and miR-188-5p and an inverse association between PBDE 99 and let-7c. Both PCBs and Cd were positively associated with miR-1537 expression level. In addition, multiple let-7 family members were downregulated with increasing levels of Hg and Pb. DDE or BPA levels did not appear to be associated with placental miRNA expression. This is the first birth cohort study linking environmental pollutants and placental expression of miRNAs. The authors concluded that the results suggest that placental miRNA profiles may signal in utero exposures to environmental chemicals.

Authors: Li Q, Kappil MA, Li A, Dassanayake PS, Darrah TH, Friedman AE, Friedman M, Lambertini L, Landrigan P, Stodgell CJ, Xia Y, Nanes JA, Aagaard KM, Schadt EE, Murray JC, Clark EB, Dole N, Culhane J, Swanson J, Varner M, Moye J, Kasten C, Miller RK, Chen J. ;Full Source: Epigenetics. 2015 Sep 2;10(9):793-802. doi: 10.1080/15592294.2015.1066960. Epub 2015 Aug 7. ;