ASTHMA AND PREGNANCY: PRENATAL EPIGENETIC ASSOCIATIONS

Abstract

Pregnancy is arguably the most critical period of developmental programming. Here, we particularly focus on the emerging paradigm that disease propensity is epigenetically determined by maternal exposures that have the capacity to activate or silence fetal genes. Children having their early gestational period in the pollen season for broad-leafed trees are more prone to sensitisation to food allergens than other children. The most notable recent candidate to emerge in this role has been dietary folate, a methyl donor clearly associated with changes in gene expression and disease susceptibility through gene hypermethylation. Animal studies also provide the first evidence that the allergy protective effects of microbial exposure in pregnancy may be mediated by changes in methylation of Th1 genes of the offspring. New studies reinforce the importance of in-utero exposures (including dietary nutrients, microbial products, cigarette smoking, and certain maternal mediations) in fetal immune development and in programming the susceptibility to asthma and allergic disease.