The clinical implications of the microbiome in the development of allergy diseases

ABSTRACT

Introduction: A substantial number of patients worldwide are affected by allergies. Emerging evidence suggests that the individual microbial composition might contribute to the development of allergies or might even protect from allergic diseases.

Areas covered: This review provides a detailed summary regarding available knowledge on the composition of a healthy human microbiome at allergy relevant body sites. It highlights factors influencing the microbiota composition. Furthermore, recent findings on the mutual interaction of the microbiota with the innate and adaptive immune system are reported. In the final part, this knowledge is combined to discuss microbial implications for food allergy, allergic asthma, allergic rhinitis, and skin allergies. Literature for this review was gathered by searching PubMed and Google Scholar databases between October and December 2020.

Expert opinion: Due to the highly individual composition, it is currently not possible to define the characteristics of a site-specific microbiome in health and disease. Mainly effects of bacterial communities have been investigated, while fungal or viral influences are not yet well understood. The communication between microbial communities found in different organs impact on allergy development. Thus, a personalized approach is essential to beneficially influence these complex interactions and to modulate the host-specific microbiota in allergies.

KEYWORDS:

• Microbiota
• microbiome
• bacterial communities
• allergy
• immune response
• immune modulation
• inflammation

Article highlights

• As the microbiota is highly host specific, it is not possible to define the composition of a healthy microbiome from currently available data. Metabolic pathways of microbes show better interindividual comparability.

• Microbiota modulates the innate and adaptive immune response. The influences are bidirectional as the immune system of the host also shapes the microbial landscape.

• Changes of the microbiota towards a nonbeneficial profile, especially during infancy, are associated with the development of inflammatory diseases such as allergies.

Declaration of interest

The authors are supported in JPI HDHL KP project ‘Intestinal microbiomics’ co-financed by the Austria Research Promotion Agency FFG. L. Koidl has no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. E. Untersmayr has received a speaker’s honorarium from Danone Trading Medical B.V., and has participated in an advisory board of Bencard Allergie GmbH. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

The research work of the authors is financially supported by the JPI HDHL KP project ‘Intestinal microbiomics’ co-financed by the Austria Research Promotion Agency FFG.