Optimizing a Point-of-Care Lateral Flow Assay for Measuring Eosinophil Peroxidase in the Esophageal String Test

Description
Background: Eosinophilic esophagitis (EoE) is an increasingly prevalent allergic disease characterized by eosinophilic inflammation and symptoms of esophageal dysfunction. Diagnosis and monitoring require repeated, invasive endoscopic esophageal biopsies to assess levels of eosinophilic inflammation. Recently, the minimally invasive esophageal string

Background: Eosinophilic esophagitis (EoE) is an increasingly prevalent allergic disease characterized by eosinophilic inflammation and symptoms of esophageal dysfunction. Diagnosis and monitoring require repeated, invasive endoscopic esophageal biopsies to assess levels of eosinophilic inflammation. Recently, the minimally invasive esophageal string test (EST) has been used collect protein in mucosal secretions as a surrogate for tissue biopsies in monitoring disease activity. From the string, assessment of the eosinophil-associated proteins major basic protein-1 (MBP-1) and eotaxin-3 (Eot3) is used to assess disease activity; however, this requires measurement in a reference laboratory, for which the turnaround time for results exceeds the time required for histopathologic assessment of endoscopic biopsies. In addition, MBP-1 and Eot3 are not markers unique to eosinophils. These obstacles can be overcome by targeting eosinophil peroxidase (EPX), an eosinophil-specific protein, using a rapid point-of-care test. Currently, EPX is measured by a labor-intensive enzyme-linked immunosorbent assay (ELISA), but we sought to optimize a rapid point-of-care test to measure EPX in EST segments. Methods: We extracted protein from residual EST segments and measured EPX levels by ELISA and a lateral flow assay (LFA). Results: EPX levels measured by LFA strongly correlated with those quantified by ELISA (rs = 0.90 {95% CI: 0.8283, 0.9466}). The EPX LFA is comparable to ELISA for measuring EPX levels in ESTs. Conclusions: The EPX LFA can provide a way to rapidly test EPX levels in ESTs in clinical settings and may serve as a valuable tool to facilitate diagnosis and monitoring of EoE.
Date Created
2024-05
Agent

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

Description

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

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.

Date Created
2023-05
Agent