Detection and Quantification of Tissue Eosinophilia in a Pig Model of Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) is an allergic disease characterized by eosinophilic inflammation, tissue remodeling (e.g. fibrosis), and dysfunction of the esophagus. Symptoms include trouble swallowing (dysphagia), food getting stuck in the esophagus (impaction), regurgitation, abdominal pain, and GI distress/vomiting. Clinical limitations include: 1) Diagnosis and monitoring of EoE requires multiple invasive upper endoscopic procedures to retrieve esophageal biopsies for histopathological assessment of eosinophilic infiltrate. 2) The manual quantification of tissue eosinophils is a laborious and subjective process. 3) The disease mechanisms of EoE are not well understood and treatment options are limited. Mouse models that recapitulate pathology seen in human EoE have been critical in advancing our understanding of EoE to help address these limitations. Recently, there have been efforts to develop pig models of EoE, as pig esophageal anatomy better resembles that of humans. We designed and optimized an immunohistochemistry (IHC) staining protocol targeting eosinophil peroxidase (EPX), an eosinophil-specific granule protein, to assess esophageal eosinophilia in a pig model of EoE. The optimized IHC protocol demonstrated successful positive staining of eosinophils in pig esophageal tissue samples and distinguished a pig model of EoE from controls. EPX staining is a useful tool for evaluating pig eosinophils by IHC. This novel IHC staining protocol provides the opportunity to further our current understanding of the histopathology, immunologic mechanisms, and potential treatment options for EoE.