The neonatal gut and skin evolve parallelly, developing a blockade to the outside world and shaping the immune system. A possible connection between skin and gut is explained by exploring the role of probiotics in the prevention of atopic dermatitis (AD).

A recent report published in Pediatric Dermatology related the findings of a systematic review and meta-analysis that showed that probiotic supplementation in both, the pre‐ and postnatal period reduced the incidence of pediatric AD. However, at the same time probiotic were not beneficial in treatment of pediatric AD.

It was stated that this gut‐skin link in the prevention, but not treatment, of AD underscores the significance of host‐microbe interactions in the perinatal period. The cutaneous microbiomecontains microbes that live inside and on the skin, which then influence both infectious and inflammatory dermal conditions, as well as immune system development. The composition of the dermal microbiome changes over the first year of life—including the rapid colonization that occurs at birth. The effectual state of the infant microbiome allows for pathology if evolution is altered, but also for opportunities to moderate—thereby preventing diseases.

Factors influencing the neonatal cutaneous microbiome are:

• Neonatal skin structure
• Microbial diversity
• From womb to the external world
• Interaction between the microbes and immune system

The role of the dermal microbiome in pediatric skin diseases:

• Atopic dermatitis (AD) –a common and persistent skin condition, that usually presentsduring early childhood. It is characterized by dry skin, intense itchingand a defective skin barrier, leaving patients at risk of infection. Children with AD have a higher predilection to develop asthma and allergic rhinitis.

Barrier dysfunction, inflammation and microbes are major contributors to AD, and the relationship between AD and microbes has been well established. While few healthy individuals are colonized with Staphylococcus aureus, 70% of patients with AD are colonized at lesional sites. On the other hand, early exposure to S. aureus reduces evolution of AD.

• Seborrheic dermatitis (SD) – a common chronic inflammatory skin disease, is characterized by erythema with overlying greasy scales. Infantile SD prominently affects the scalp, neck, faceand diaper area. Exact etiology of SD is unknown; scientist suggest a relation with lipophilic yeast Malassezia.
• Erythema toxicumneonatorum –a common, benign neonatal skin condition, consists of pustules and papules on an asymmetrical erythematous base. This condition arises within days 2-4 after birth and regresses unprompted within a week. Contusions usually appear on the butt¬ocks, thighs and trunk.

Skin microbiome of an infant is diverse and dynamic and many factors play a significant role in shaping it. The unique relationship of skin barrier, immune function with the skin microbiome is a key to understanding advent of pediatric diseases. Early intervention strategies may also help in the prevention of dermatological pathologies.

Source: SchochJJ., Monir RL., et al. The infantile cutaneous microbiome: A review. PediatrDermatol 2019 Sep; 36(5) : 574 - 580