Maternal cigarette smoking affects DNA methylation in imprinting control regions and enhancer regions in placenta

Abstract

TPS 911: Air pollution, epigenetics, biomarkers, Exhibition Hall, Ground floor, August 26, 2019, 3:00 PM - 4:30 PM Background/Aim: Exposure to cigarette smoking during pregnancy has been robustly associated with cord blood dna methylation. However, little is known about such effects on the placenta; in particular, whether cigarette smoking before pregnancy could also induce epigenetic alterations in the placenta of former smokers is unknown. Methods: Placental DNA methylation levels were measured in 568 women and compared among non-smokers and women either smoking during their pregnancy or who had ceased smoking before pregnancy. Results: Among the 344 genomic regions identified as differentially methylated as a result of maternal exposure to cigarette smoking, 44 presented a transmissible “epigenetic memory” of past exposure to cigarette-smoking. Additionally, an analysis of the encode placental histone marks associated with most of the 344 differentially methylated loci presented characteristics of gene enhancer regions. Conclusions: Finally, a number of imprinting control regions was also among the 344 differentially methylated regions, suggesting mechanisms by which tobacco could directly impact fetal development.