Diagnostic Utility of Major Basic Protein and Eotaxin-3 Staining in the Esophageal Epithelium for Differentiation of Eosinophilic Esophagitis from Gastroesophageal Reflux Disease: ACG Governors Award for Excellence in Clinical Research

Abstract

Purpose: Features of eosinophilic esophagitis (EoE) and gastroesophageal reflux disease (GERD) overlap. Markers of eosinophil activation and migration, such as major basic protein (MBP) and eotaxin-3, have been implicated in EoE pathogenesis, but their role in diagnosis of EoE has not been extensively characterized. The aim was to determine whether the MBP and eotaxin-3 staining in the esophageal epithelium differentiates EoE from GERD and has utility for diagnosis of EoE. Methods: In this case-control study, cases had a new diagnosis of EoE, defined by 2007 consensus guidelines (≥15 eosinophils in ≥1 high-power field; ≥1 symptom of esophageal dysfunction; other causes of eosinophilia excluded; no response to proton-pump inhibition). Controls had GERD (≥1 typical symptom; other causes excluded) and were selected to have inflammation including eosinophils on biopsy because this is the group where there is diagnostic difficulty. Immunohistochemistry was performed for MBP and eotaxin-3. After masking, maximum epithelial MBP and eotaxin-3 staining density was quantified (positive cells/mm2). Staining levels and eosinophil counts (eos/hpf; hpf = 0.24mm2) were compared, and receiver operator characteristic (ROC) curves were constructed. Results: For the 51 EoE patients (mean age: 24; 69% male; mean of 143 eos/hpf) and 55 GERD patients (mean age 34; 61% male; mean of 20 eos/hpf), the maximum MBP density was higher in EoE than in GERD (1479 ± 1290 cells/mm2 vs 59 ± 103; p<0.001) as was the max eotaxin-3 density (2219 ± 1782 vs 479 ± 777; p<0.001; see Figure). MBP density and eosinophil count strongly correlated (R = 0.81; p<0.001); correlation with eotaxin-3 was weaker (R = 0.25; p = 0.01). The area under the ROC curve for diagnosis of EoE was 0.96 for MBP staining alone, 0.87 for eotaxin-3 alone, 0.96 for MBP and eotaxin-3 together, and 0.99 for the combination of MBP, eotaxin-3, and eosinophil count.Figure: No Caption available.Conclusion: Patients with EoE have substantially higher levels of MBP and eotaxin-3 staining in the esophageal epithelium compared with GERD patients. Staining with MBP and eotaxin-3 provides added diagnostic value beyond eosinophil counts alone, and MBP staining in particular may have utility as a diagnostic assay for EoE.