The placenta is vulnerable to air pollution, which could be the cause of long-term changes in the metabolism of fetuses faced with nitrogen dioxide and fine particles.
- French researchers have just demonstrated that three air pollutants – nitrogen dioxide (NO2) and fine particles (PM2.5 and PM10) – have an impact on the methylation of placental DNA.
- This impact is not the same for girls and boys.
- “Future studies will be able to investigate whether placental epigenetic changes caused by exposure to air pollution during pregnancy persist after childbirth and how they could influence development during childhood,” says the author of the study. ‘study.
Air pollution harms babies in utero, says new French research published in The Lancet.
Three air pollutants impact placental DNA methylation
A research team led by Johanna Lepeule, Inserm researcher at the Institute for the Advancement of Biosciences (Inserm/CNRS/Université Grenoble Alpes), was interested in the impact of three air pollutants – carbon dioxide. nitrogen (NO2) and fine particles (PM2.5 and PM10) – on placental DNA methylation. Thanks to data from three French mother-child cohorts, she was able to compare exposure to these pollutants and methylation levels in more than 1,500 participants during their pregnancy.
The results show a significant impact of exposure to three air pollutants on placental DNA methylation levels regarding genes involved in fetal development. A third of these modifications were directly associated with indicators of child development (birth weight and height, head circumference, duration of pregnancy, etc.).
Other placental changes concerned genes involved in the development of the nervous system, the immune system and metabolism (neonatal diabetes or obesity).
Air pollution: a different impact on girls and boys
If these alterations in methylation are present in both sexes, scientists have also been able to highlight modifications having an additional impact and affecting different genes depending on the sex of the unborn child. Two different gestation periods particularly vulnerable to epigenetic modifications under the effect of pollutants emerge in this work: the beginning of pregnancy (1er trimester) in boys and the end of pregnancy (3e trimester) in girls.
“Our results show that exposure to air pollution during pregnancy induces changes in placental DNA methylation specific to each of the two sexes,” indicates Johanna Lepeule. “VSand differentiated impact could contribute to alterations in the development and course of pregnancy that are different depending on the sex of the unborn child. continues the scientist.
Thus, in boys, significant alterations in methylation at the level of genes critically involved in the development of the nervous system and intellect were detected.
“These observations support the growing number of studies associating exposure to air pollution during pregnancy with impaired neurodevelopment and/or a reduction in cognitive abilities,” specifies Lucile Broséus, Inserm researcher and co-author of the publication.
In girls, methylations affected genes involved in fetal development and the regulation of oxidative stress. They could thus be associated with developmental defects likely to increase the risks of contracting chronic metabolic diseases (hypertension, diabetes, obesity, etc.) later in life, but also with the occurrence of miscarriages or pre-eclampsia. at the mother’s.
Air pollution and the placenta: new research planned
“This work therefore provides new data concerning the epigenetic mechanisms involved in the deregulation of fetal growth under the effect of air pollution and which could be at the origin of long-term changes in metabolism,” concludes Inserm in a press release.
“Future studies may investigate whether placental epigenetic changes caused by exposure to air pollution during pregnancy persist after delivery and how they might influence development during childhood., adds Johanna Lepeule. “In addition, this research work having been carried out on French cohorts, its results will have to be verified in populations from other geographical regions and with different genetic profiles.concludes the researcher.
