Distinct DNA methylation in mother-infant dyads exposed to PM2.5 in pregnancy

Air pollution exposure during pregnancy increases the risk of allergic and respiratory diseases, yet its epigenetic effects across the maternal-fetal interface remain poorly understood. We conducted a pilot study of 10 mother-infant dyads near Fresno, California, to investigate whether prenatal air pollution exposure is associated with differential DNA methylation (DNAm) in maternal peripheral blood mononuclear cells (PBMCs) and infant cord blood mononuclear cells (CBMCs). Using a custom DNAm array targeting high-value allergy- and asthma-associated loci, we identified 24 CpG sites in maternal PBMCs and 18 in infant CBMCs associated with PM2.5 exposure. Only one CpG site was shared between PBMCs and CBMCs, suggesting largely distinct DNAm responses to PM2.5 in maternal and fetal circulations. Further research is needed to validate these associations and determine their functional implications for immune development and disease risk.