Non-Invasive Biomarkers for Eosinophilic Esophagitis: Latest Developments and Future Directions.

Eosinophilic esophagitis (EoE) is an emerging disease characterized by chronic inflammation of the esophagus. EoE is a multifactorial disorder, likely resulting from the combination of genetic predisposition, epithelial barrier dysfunction, environmental risk factors, and allergen sensitization, which lead to type 2 inflammation of the esophagus. The clinical manifestations are related to esophageal dysfunction and include dysphagia, food impaction, heartburn, regurgitation, and food refusal. These symptoms are sometimes superimposable and can often be confused with the symptoms of gastroesophageal reflux disease. To-date, EoE diagnosis relies on endoscopic examination and histological analysis of esophageal biopsies, with the diagnostic criterion defined as the presence of ≥15 eosinophils per high-power field (eos/HPF). As a result, both the diagnostic and the subsequent disease monitoring processes, including assessment of treatment, efficacy, and remission status, require repeated endoscopic procedures. These procedures are rather invasive for patients, particularly in the pediatric population, and impose a significant financial strain on healthcare systems. Therefore, in recent years, substantial efforts have been made to identify novel non-invasive or minimally invasive biomarkers. This review aims at synthesizing the current findings and at categorizing the most promising biomarkers according to the different biological sources to ultimately enable earlier detection, reduce patient discomfort, and guide personalized treatment strategies.