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.