Food allergy (FA) affects 4–10% of children, particularly children with atopic dermatitis (AD). The gut microbiome can determine both the course of FA and tolerance to food allergens during infancy. Analogically, the skin microbiome changes during AD. FA has been related with a lower abundance and diversity of Lactobacillales and Clostridiales, but greater numbers of Enterobacterales, while AD in children has been described with lower numbers of Staphylococcus epidermidis and S. hominis but an abundance of S. aureus and Streptococcus species, by many studies. 

Recent studies demonstrated skin sensitization to food antigens have a significant influence on the occurrence of FA, suggesting a strong link between the skin and gut immune responses. Some studies suggest that the skin and gut are linked via modulation of the immune environment via the microbiome but it is not clear whether modulation of the gut microbiome can impact the skin microbiome and vice versa. 

Influence of the gut and skin microbiome on the immune system

Among the many functions, the influence of the gut microbiome on the immune system in allergy is of key importance. Microbiomes influence on the development and function of the immune system, maintaining the balance between the Th1/Th2 responses, by regulating various lymphocyte subpopulations, especially Tregs, responsible for immune tolerance serves the most important function. The absence of an intact intestinal microbiome increases the levels of both IgE and circulating basophils.

A novel therapeutic strategy aiming to restore the natural skin microbiome, like the application of probiotic strains/topical microbiome transplantation is being studied.

Thus, changes in the microbiome grant protection or susceptibility to FA or AD by modulating the immune system ad so early childhood appears to be critical for the colonization of a diverse microbiome. Recent researches have focused on the identification of bacterial strains necessary for oral tolerance and identification of the most effective probiotic strains for the prevention and treatment of FA. Early skin topical treatment may reduce S. aureus colonization by exerting an anti-inflammatory effect. The management of skin diseases by manipulation of gut function may be a future. Balancing the gut and skin microbiome will prove an effective allergy treatment. Therefore, extensive studies are warranted to identify the interactions between the gut and skin microbiomes.

Source: Postepy Dermatol Alergol. 2020;37(5):641-650. doi:10.5114/ada.2019.90120