Air pollution is detrimental to pregnancy adversely affecting maternal and child health. Our objective was to unravel epigenetic mechanisms mediating the effect of preconception, periconception, and gestational exposure to inhaled air pollutants (AP) upon the maternal and placental-fetal phenotype and explore the benefit of an omega-3 rich dietary intervention. To this end, we investigated intranasal instilled AP during 8 weeks of preconception, periconception, and gestation (G; D0 to 18) upon GD16-19 maternal mouse metabolic status, placental nutrient transporters, placental-fetal size, and placental morphology. Prepregnant mice were glucose intolerant and insulin resistant, while pregnant mice were glucose intolerant but displayed no major placental macro-nutrient transporter changes, except for an increase in CD36. Placentas revealed inflammatory cellular infiltration with cellular edema, necrosis, hemorrhage, and an increase in fetal body weight. Upon examination of placental genome-wide epigenetic processes of DNA sequence specific 5'-hydroxymethylation (5'-hmC) and 5'-methylation (5'-mC) upon RNA sequenced gene expression profiles, revealed changes in key metabolic, inflammatory, transcriptional, and cellular processing genes and pathways. An omega-3 rich anti-inflammatory diet from preconception (8 weeks) through periconception and gestation (GD0-18), ameliorated all these maternal and placental-fetal adverse effects. We conclude that preconceptional, periconceptional and gestational exposures to AP incite a maternal inflammatory response resulting in features of pre-existing maternal diabetes mellitus with injury to the placental-fetal unit. DNA 5'-mC more than 5'-hmC mediated AP induced maternal inflammatory and metabolic dysregulation which together alter placental gene expression and phenotype. A dietary intervention partially reversing these adversities provides possibilities for a novel nutrigenomic therapeutic strategy.
