Identification of miRNAs associated with eosinophilic esophagitis shown by esophageal mucosal biopsy results of Japanese patients

The number of eosinophilic esophagitis (EoE) patients has been rapidly increasing worldwide in recent years, though remains relatively lower in Japan. To determine whether Japanese EoE cases have pathogenic differences, microRNA (miRNA) transcriptome analyses of esophageal biopsy specimens from patients with EoE were performed to identify involved miRNAs and the results were compared with those for cases reported in Western countries. Japanese patients with EoE (<i>n</i> = 9) or reflux esophagitis (RE) (<i>n</i> = 4) were enrolled, with the latter serving as controls. Biopsies of esophageal mucosal tissue were performed as a part of an upper gastrointestinal endoscopy, followed by comprehensive miRNA expression analysis (2,588 target human miRNAs) using microarray technology. The EoE patients were then treated with a proton pomp inhibitor, and miRNA expression in the esophagus was compared before and after treatment. Hierarchical cluster analysis findings showed clear differences in miRNA expression patterns between the EoE and RE patients, with increased expression of 13 and decreased expression of 10 miRNAs noted in the EoE cases. These results were then compared with miRNA expression in esophageal mucosa of EoE patients presented in Western reports and the expression profiles were found to be very similar. In addition, changes in expression profiles of several miRNAs before and after treatment were observed in the present EoE patients. miRNA microarray analysis of Japanese EoE patients demonstrated a significant overlap of miRNA expression in comparison with Western patients, indicating that EoE likely represents the same disease among diverse racial populations and shows a consistent pathogenesis worldwide.