What Is the Relationship Between Eosinophilic Esophagitis (EoE) and Aeroallergens? Implications for Allergen Immunotherapy

Observations suggesting that aeroallergens trigger eosinophilic esophagitis (EoE) in a subset of patients raise questions about the implications this finding has on the evaluation and management of patients with EoE, including a potential role for allergen immunotherapy. The majority of studies evaluating the potential role of aeroallergens as provocateurs of EoE have addressed this issue by assessing the seasonal variation in EoE diagnosis and/or symptom onset or worsening, with mixed results. For various reasons, reaching accurate conclusions based on this methodology is potentially fraught with error. In addition, studies examining the even harder to assess role of perennial aeroallergens in triggering EoE are lacking. Although clearly not the majority, there may be a subset of patients with EoE and allergic rhinitis in whom exposure to aeroallergens to which they are sensitized contributes to esophageal eosinophilia either through direct chronic esophageal mucosal contact with pollen allergens or from repetitive exposure of the esophageal mucosa to pollen allergens, mediators, and eosinophils in swallowed nasal secretions. Therefore, evaluation for and optimal treatment of comorbid allergic rhinitis in EoE patients are clearly indicated. Recognition of the potential role of aeroallergens as triggers of EoE also raises the question of whether allergen immunotherapy might be an effective form of EoE treatment. Reports of sublingual immunotherapy (SLIT) inducing EoE support the notion that aeroallergens can trigger EoE, but negate this approach as a potential form of EoE therapy. In fact, the use of SLIT is contraindicated in patients with EoE. The literature regarding the role of subcutaneous immunotherapy (SCIT) in patients with EoE is limited. Current evidence indicates that it should not be typically recommended; however, SCIT might benefit a subset of patients with EoE and uncontrolled allergic rhinitis on conventional therapies in whom SCIT would otherwise be indicated for allergic rhinoconjunctivitis, particularly in those with sensitizations to pollens containing allergens that cross react with food allergens. The purpose of this review is to discuss the current literature examining the role of aeroallergens in triggering EoE with a focus on the potential clinical implications of this finding on managing patients with EoE.