A Prospective Study of Eosinophilic Esophagitis and the Expression of Tight Junction Proteins in Patients with Gastroesophageal Reflux Disease Symptoms

Background/Aims Eosinophilic esophagitis (EoE) is often erroneously diagnosed as gastroesophageal reflux disease (GERD). The aim of this study is to investigate the prevalence of EoE and the expression of tight junction (TJ) proteins in patients with GERD symptoms. Methods One hundred patients with GERD symptoms and 10 healthy controls were prospectively studied. Sixty-two patients had symptoms refractory to proton pump inhibitors (PPI). All patients underwent esophageal biopsy. Patients were diagnosed with EoE if the number of eosinophil granulocytes per high-power field was ≥15. Immunohistochemical analysis of TJ proteins (claudin-1, claudin-4, occludin, and zonula occludin-1 [ZO-1]) was performed. Results EoE was diagnosed in six of 100 patients (6%) with GERD symptoms and in six patients (9.7%) of 62 patients with PPI-refractory GERD. Only one had typical EoE endoscopic findings. The proportion of ZO-1-positive cells was significantly lower in the lower than in the middle esophagus (56.0%±14.0% vs 66.0%±11.5%, p＜0.05). There were no significant correlations between TJ protein expression and GERD symptoms. Conclusions The prevalence of EoE among patients with PPI-refractory GERD is approximately 10%. Regardless of endoscopic findings, esophageal biopsy is crucial in diagnosing EoE. The disruption of ZO-1 expression in the lower esophagus is significantly associated with GERD symptoms.