Origin of Allergy From In Utero Exposures to the Postnatal Environment

Abstract

As the incidence of atopic conditions continues to increase, emphasis has been placed on understanding the origin of allergy with hope that prevention measures can be achieved. The perinatal environment is important for this understanding, given that both the immune system and microbiome start forming prenatally. Maternal exposure can greatly impact on fetal health. Additionally, the dysfunctional epithelial barrier is influential in allowing allergens and irritants to penetrate the skin or mucosa, leading to the release of proinflammatory cytokines and mediators to drive type 2 tissue inflammation and the onset of allergy. There are numerous factors related to skin, airway, and gut epithelial barriers dysfunction, and genetic predispositions are also present. Comprehensive birth cohort studies and further mechanistic studies will be keys to understanding the origin of allergy.

Keywords: Allergy; allergens; asthma; cytokines; dermatitis, atopic; etiology; food allergy; immune system; microbiome.

Figure. Perinatal factors contributing to the development of atopy. Left: the prenatal maternal-fetal environment can cause fetal epigenetic changes and immune dysregulation with maternal exposure. Right: the birth delivery route and post-natal infant exposure are contributing factors to the dysfunctional epithelium of the skin, airway, and gut. Please note that the collectively listed factors affect multiple organ systems, as the factors listed under one category can modulate the immune system leading to systemic consequences. Figure adapted with permission from Hui and Leung.

AD, atopic dermatitis; FA, food allergy.