Biomarkers for eosinophilic esophagitis: A review

The complex pathophysiology of eosinophilic esophagitis (EoE) provides several candidate biomarkers that could be used to establish diagnosis, assess response to therapy, and document disease recurrence. To review the literature on various biomarkers of EoE, with respect to their correlation to disease activity and response to treatment. A literature search was performed using PubMed and OVID with keyword combinations of EoE and various potential biomarkers. Between 2006 and 2012, 26 studies that investigated the correlation of various tissue and serum biomarkers with EoE were identified. The markers investigated included eotaxins-1,-2, and -3, interleukin-5 (IL-5), interleukin-13 (IL-13), eosinophil-derived neurotoxin, mast cell markers, absolute eosinophil count, and micro-RNAs. Several studies have shown a positive correlation between eotaxin-3, IL-5, and IL-13 messenger RNA (mRNA) expression in esophageal tissue and disease activity. Eotaxin-3 mRNA staining was found to have 89% sensitivity for diagnosing EoE. Staining for mast cells and their products has also shown promise. More recently, a microRNA signature that can potentially distinguish EoE from non-EoE esophagitis has been identified. The studies are quite heterogeneous with respect to their methodology and the biomarker(s) studied, but most have investigated tissue biomarkers. Eotaxin-3 and IL-13 have emerged as the most promising ones with respect to sensitivity and degree of positive correlation to disease process. Future research on biomarkers for EoE should include longitudinal studies, establishment of normal values, effects of concomitant atopic diseases, age and gender, and validation of methodology of the tests.