Follow up on atopy and the gastrointestinal tract – a review of a common association 2018

ABSTRACT

Introduction: Primary atopic disorders can be classified as heritable genetic disorders presenting with deregulated pathogenic allergic effector responses irrespective of sensitization. In the last decade, there are parallel rises in the burden of atopic and gastrointestinal (GI) diseases.

Areas covered: There is increasing recognition of an association between atopy and GI disease through immune dysregulation, the microbiome and shared genetic pathways. Since the first article on atopy and the GI tract in 2014 in this journal, many more studies have shed light on the shared pathways in these diseases, particularly in the field of eosinophilic GI disease, functional GI disorders, and inflammatory bowel disease.

Expert opinion: Understanding the links with common mechanisms in atopy and GI diseases that may lead to better targeting of treatment through manipulation of immune mechanisms, the microbiome, genetics, food allergens and specific GI diseases such as inflammatory bowel disease, functional GI disorders.

KEYWORDS:

• Gastrointestinal inflammation
• atopy
• eosinophilic gastrointestinal disease
• food allergy
• microbiome
• genetics

Article highlights

• Gastrointestinal diseases are associated with atopy - Atopy is defined as the tendency to become sensitized and express IgE to environmental allergens after ordinary exposure. Parallel rises in the burden of GI disease and atopic diseases in the last decade, including eosinophilic esophagitis, food allergy, inflammatory bowel disease and functional gastrointestinal disorders

• Common immune pathways in atopy and GI disease - Recently described, innate lymphoid cells (ILCs) residing in the GI tract play critical roles in maintaining intestinal homeostasis, driving inflammatory pathology promoting allergic responses, these cells likely provide an immunological link between GI dysfunction and atopy.

• Microbiome and atopy - the microbiota actively contributes to maintaining immune homeostasis, a fine balance which when disrupted by overgrowth or loss of diversity can promote disease, for example, loss of key digestive enzymes through microbial alterations may promote increased exposure to antigenic moieties on otherwise harmless foods.

• Inflammatory Bowel Disease (IBD) and Atopy – there is a strong association between IBD and the development of extra-intestinal atopic disease, including atopic dermatitis and asthma both of which themselves are linked to dysbiosis. Associations between IBD and atopic disease are bidirectional as asthma, and atopic dermatitis are associated with an increased risk of subsequent IBD diagnosis.

• Food Allergy and Functional Gastrointestinal Disorders – the immunology of food allergy shares similarities to other GI diseases such as eosinophilic oesophagitis, and the functional GI disorders (FGIDs); functional dyspepsia and the irritable bowel syndrome associated with traditionally type-2 immune responses.

• Genetics, Atopy and Gastrointestinal Disease - genome-wide association studies show overlap of genetic linkage of autoimmune disorders, asthma, and inflammatory bowel disease.

Declaration of interest

The authors have no 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

This paper was not funded.