Introduction
Atopic dermatitis (AD) is a chronic pruritic inflammatory skin condition characterized by disrupted skin barrier function and immune dysregulation. Its onset is typically in early life and is more common in children, afflicting up to 25%.1 AD is a complex disease with a multifaced burden encompassing physical discomfort, sleep disturbances, limitations in daily activities and exerts a profound psychosocial impact on children and their caregivers.2
In addition to these challenges, children with AD often experience multiple co-morbidities such as food allergies (FA), allergic rhinitis, asthma, autoimmune disorders, and recurrent skin infections.3, 4 The pathogenesis of AD in children involves a complex interplay of genetic factors, skin barrier defects, Th2 cytokine imbalances, allergen sensitization, and microbial interactions.5
In particular, early onset and severe AD are significant risk factors for the development of FA in children. The “Dual Allergy Exposure Hypothesis” proposes that allergen exposure, either through the skin or the gut, during a critical period in early life can lead to the development of FA.6 The concept of primary prevention of AD has thus gained traction as a strategy to mitigate transcutaneous sensitization and subsequently reduce the risk of FA and other allergic disorders in the “atopic march”.
The skin, being the largest organ in the human body, plays a vital role in providing barrier protection, sensory regulation, and immune and thermal homeostasis.7 It is colonized by an extensive community of bacteria, fungi, mites, and viruses thought to interact with the host to influence health and disease states. Recent advances in sequencing technology revealing a diverse skin microbial community on healthy skin and increasing microbial-host interaction studies in humans and model systems suggest a fine equilibrium exists among pathogens, commensal organisms, and the immune system. However, in children with AD, this skin microbiome is altered.
This review highlights the known mechanistic pathways involved in the development of AD and FA in children, as well as the emerging understanding of the role of the skin microbiome in pediatric AD and FA. It also discusses recent studies exploring the potential of the skin microbiome in the treatment and prevention of these conditions.