2024-05-08 09:47:00
the essentials A team of researchers from Inserm was interested in the influence of air pollution on genes in the placenta. The more mothers are exposed to it, the more this pollution affects the genes involved, for example in the development of the immune system, the nervous system or even the intellect.
Does air pollution affect fetal development? This is suspected, recalls the National Institute of Health and Medical Research (Inserm), to be the cause of cardiometabolic, respiratory or even neuropsychological pathologies in the unborn child. But by what mechanisms? This is what a team from Inserm wanted to understand, which published their work in the journal The Lancet Planetary Health.
She was particularly interested in the placenta, which is largely involved in the development of the fetus. “Especially vulnerable to many chemical compounds, it can be compared to an ‘archive’ that bears witness to the child’s prenatal environment: the epigenetic modifications (modification of genes without modification of DNA, ed. note) that occur in the cells partly reflect the environmental exposures of the mother during pregnancy,” specifies Inserm in a press release dated May 7. To assess these modifications, we measure the level of methylation of placental DNA: these are chemical modifications involved in the control and expression of genes.
Consequences for the development of the unborn child
The scientific team (Inserm, CNRS, Université Grenoble Alpes) measured the impact of three air pollutants, nitrogen dioxide (NO2) and fine particles (PM2.5), on three mother-child cohorts and PM10. Exposure to these three pollutants and methylation levels might be compared during the pregnancy of 1,500 participants. “The results show a significant impact of exposure to three air pollutants on the levels of placental DNA methylation regarding genes involved in fetal development,” reports Inserm.
Result: these three pollutants play a role in the methylation levels of genes, a third of which concerns the development of the child (weight, size of the child at birth, duration of pregnancy, head circumference, etc.). Other modifications have been observed regarding genes involved in the development of the nervous and immune systems and metabolism – especially neonatal diabetes and obesity.
Genes are affected depending on gender
The researchers were also able to highlight the times of pregnancy when exposure to pollutants had the greatest influence on fetal development: the first trimester for boys and the third for girls. In boys, methylation changes were “critical” for genes involved in the nervous system and intellect.
In girls, the relevant genes were involved in fetal development and regulation of oxidative stress. These results can “thus be associated with developmental defects that are likely to increase the risk of developing chronic metabolic diseases (hypertension, diabetes, obesity, etc.) later in life, but also with the occurrence of miscarriages or pre-eclampsia in the mother”, summarizes Inserm.
High vulnerability in male children
For Lucile Broséus, first author of the publication, “these observations support the growing number of studies linking exposure to air pollution during pregnancy and impaired neurodevelopment and/or a reduction in cognitive abilities. , with greater vulnerability in male children.
“Future studies will be able to investigate whether placental epigenetic changes caused by exposure to air pollution during pregnancy persist following birth and how they may affect development in childhood,” adds Johanna Lepeule, leader of the team.
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