Background: The placenta acts not only as a conduit of nutrient and waste exchange between mother and developing fetus but also functions as a regulator of the intrauterine environment. Pre-eclampsia (PE) and gestational diabetes mellitus (GDM) are leading causes of complications during pregnancy. Pathophysiologies show that they are associated with one another. Epigenetics provides a link between environmental factors that have previously been linked to poor pregnancy outcomes and fetal programming. Methods and Results: The present study investigated genome-wide DNA methylation changes in PE and GDM compared with control subjects through DNA methylation microarray. We found that the methylation patterns of placentas from PE and GDM women were similar; 64.4% of the annotated genes with differential methylation presented concordant changes between PE and GDM patients. Significantly, the same functional processes were affected by PE and GDM, with cell adhesion and cell differentiation being the most populated clusters and including genes related to carbohydrate metabolism and lipid metabolism. Conclusion: Our work showed that of DNA methylation patterns in human placentas are reliably and significantly associated with PE and GDM. DNA methylation status in the human placenta can function as a marker for the intrauterine environment and potentially play a functional role in PE and GDM development.

Emerging evidences indicate that placenta plays a critical role in gestational diabetes mellitus (GDM). DNA methylation could be associated with altered placental development and functions. This study is to uncover the genome-wide DNA methylation patterns in this disorder. DNA methylation was measured at >385,000 CpG sites using methylated DNA immunoprecipitation (MeDIP) and a huamn CpG island plus promoter microarray. We totally identified 6,641 differentially methylated regions (DMRs) targeting 3,320 genes, of which 2,729 DMRs targeting 1,399 genes, showed significant hypermethylation in GDM relative to the controls, whereas 3,912 DMRs targeting 1,970 genes showed significant hypomethylation. Functional analysis divided these genes into different functional networks, which mainly involved in the pathways of cell growth and death regulation, immune and inflammatory response and nervous system development. In addition, the methylation profiles and expressions of 4 loci (RBP4, GLUT3, Resistin and PPARα) were validated by BSP for their higher log2 ratio and potential functions with energy metabolism. This study demonstrates aberrant patterns of DNA methylation in GDM which may be involved in the pathophysiology of GDM and reflect the fetal development. Future work will assess the potential prognostic and therapeutic value for these findings in GDM.

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