Proton‐pump Inhibitor Response Prediction Using Esophageal microRNAs in Children With Eosinophilic Esophagitis

ABSTRACT Objectives: Eosinophilic esophagitis (EoE) is a chronic esophageal disease characterized by eosinophilic inflammation. Proton‐pump inhibitors (PPI) induce disease remission but no predictive factors of PPI‐responsiveness have been identified yet. So, a biomarker must be found to differentiate between responders (PPI‐R) and nonresponder patients (PPI‐NR) to PPI. Aims were to identify any molecular biomarker that could predict PPI responsiveness and to study molecular remission after PPI therapy. Methods: This prospective study enrolled 39 controls and 43 pediatric children with EoE from 2 hospitals, and they were treated with esomeprazole for 8 to 12 weeks. After therapy, patients were classified as either PPI‐R or PPI‐NR. Biopsies were collected and RNA, microRNAs, and proteins were isolated from them, measuring levels by qPCR and Western blot (WB). Also, miRNAs were evaluated in serum. Results: We found several esophageal miRNAs with different expression values between PPI‐R and PPI‐NR children, which can be used to discriminate them (area under curve = 0.90). No useful serum miRNAs were, however, identified. Also, these miRNAs were dysregulated in responder patients before and after PPI therapy. Moreover, we corroborated in this child population, that PPI‐R displayed a significant decrease in eotaxin‐3, IL‐5, IL‐13, periostin, and major basic protein (P