Effect of prematurity on genome wide methylation in the placenta

Jessica Schuster,Christoph Schorl,Alper Uzun,James F Padbury,Joan Stablia,Mari Mori

doi:10.1186/s12881-019-0835-6

Abstract

BackgroundPreterm birth is a significant clinical problem and an enormous burden on society, affecting one in eight pregnant women and their newborns. Despite decades of research, the molecular mechanism underlying its pathogenesis remains unclear. Many studies have shown that preterm birth is associated with health risks across the later life course. The “fetal origins” hypothesis postulates that adverse intrauterine exposures are associated with later disease susceptibility. Our recent studies have focused on the placental epigenome at term. We extended these studies to genome-wide placental DNA methylation across a wide range of gestational ages. We applied methylation dependent immunoprecipitation/DNA sequencing (MeDIP-seq) to 9 placentas with gestational age from 25 weeks to term to identify differentially methylated regions (DMRs).ResultsEnrichment analysis revealed 427 DMRs with nominally significant differences in methylation between preterm and term placentas (p < 0.01) and 21 statistically significant DMRs after multiple comparison correction (FDR p < 0.05), of which 62% were hypo-methylated in preterm placentas vs term placentas. The majority of DMRs were in distal intergenic regions and introns. Significantly enriched pathways identified by Ingenuity Pathway Analysis (IPA) included Citrulline-Nitric Oxide Cycle and Fcy Receptor Mediated Phagocytosis in macrophages. The DMR gene set overlapped placental gene expression data, genes and pathways associated evolutionarily with preterm birth.ConclusionThese studies form the basis for future studies on the epigenetics of preterm birth, “fetal programming” and the impact of environment exposures on this important clinical challenge.

Highlights

Preterm birth is a significant clinical problem and an enormous burden on society, affecting one in eight pregnant women and their newborns
Placental samples were obtained from six preterm pregnancies and three term pregnancies (37–41 weeks)
Following False discovery rate (FDR) correction, we found 67 significant Differentially methylated regions (DMR) that associate with gestational age, using a filter for low mean counts to maximize the number of FDR significant peaks at an adjusted p < 0.05

Summary

Introduction

Preterm birth is a significant clinical problem and an enormous burden on society, affecting one in eight pregnant women and their newborns. Many studies have shown that preterm birth is associated with health risks across the later life course. Our recent studies have focused on the placental epigenome at term We extended these studies to genome-wide placental DNA methylation across a wide range of gestational ages. The underlying cause of preterm birth remains enigmatic It is a leading cause of newborn morbidity, hospitalization, and developmental delays [1]. Preterm birth is associated with health risks across the later life course of the newborn, including cardiovascular disease, metabolic syndromes, psychiatric conditions, obesity and cognitive disabilities [1, 2]. The “fetal origins” or Developmental Origins and Health and Disease (DOHaD) hypothesis, developed from a series of epidemiologic observations, demonstrated that measures of birth size were associated with long-term chronic. DNA methylation is an essential epigenetic mechanism in fetal development [7]

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