On the surface: Skin microbial exposure contributes to allergic disease

Area of Science:

• Dermatology
• Immunology
• Microbiology

Background:

• Allergic disorders involve immunoglobulin E (IgE) sensitivity and T helper 2 (T_H2) cell responses.
• Skin microbiome fluctuations are increasingly linked to the development and exacerbation of allergic diseases.
• Commensal-epidermal homeostasis plays a crucial role in modulating skin immunity and protecting against pathogens.

Purpose of the Study:

• To review the intricate relationship between the skin microbiome, skin immunology, and allergic diseases.
• To discuss how commensal-epidermal interactions influence the development and progression of allergies.
• To explore current and future therapeutic strategies targeting the skin microbiome for allergy management.

Main Methods:

• Literature review of studies on commensal-epidermal homeostasis, skin microbiome dysbiosis, and microbiome-targeted therapeutics.
• Analysis of research articles obtained from the PubMed database.
• Inclusion of studies addressing prevention and treatment of allergy through microbiome modulation.

Main Results:

• Commensal microbes promote antiallergic T_H1 and T_H17 immune responses and stimulate keratinocytes to produce antimicrobial peptides and alarmins, enhancing skin barrier function.
• Dysbiosis, characterized by reduced commensals and increased pathogens like *Staphylococcus aureus*, is associated with atopic dermatitis.
• Skin microbiome alterations contribute to impaired barrier function, allergic sensitization, and increased T_H2 cytokine secretion, impacting various allergic conditions.

Conclusions:

• Maintaining commensal-epidermal homeostasis is vital for preventing allergic diseases.
• Further research is needed to understand the skin microbiome's impact on extracutaneous allergic disorders and to develop targeted microbiome therapeutics.
• Therapeutic approaches include enhancing skin barrier function, restoring commensal flora, and employing anti-T_H2 biologic therapies.