Su1113 In Search of a Non-Invasive Blood Test for Diagnosis and Monitoring of EoE: A Prospective Study of a Serum Biomarker Panel

Abstract

increasing in the population especially in pediatrics and reach 1:1000 in diseases such as EoE (Eosinophilic Esophagitis) (Lee 2013). CD24 is a small, mucin-like glycoprotein that functions both in signal transduction and as an adhesion molecule (Sagiv, 2008). CD24 is expressed on many hematopoietic cells, non-hematopoietic cells and malignancies (Fang, 2010). Previous studies in eosinophils have suggested CD24 as an IL-5-upregulated gene that is involved in eosinophil apoptosis and survival (Temple, 2011). The role evoked for CD24 in IL-5-induced survival of eosinophils remains to be investigated. We hypothesize that CD24 is a key molecular checkpoint, regulating eosinophil functions in chronic mucosal GI diseases, all of which are characterized by significant eosinophil infiltration. Aim: 1) To assess the expression of CD24 in eosinophils in the GI tract in wild-type (WT) mice; 2) To assess the level of eosinophils in the GI tract in CD24 knockout (-/-) and to compare it to WT mice.Methods: We have previously established a colony of CD24-/mice, on a C57BL/ 6J genetic background, and their WT littermates at our local animal facility. The levels of eosinophils were assessed in WT and CD24-/mice. Bone marrow (BM) cells were collected, and grown in medium containing 10 ng/mL recombinant mouse interleukin-5 (rmIL-5). On day 13 the cells were counted and levels of eosinophils were assessed by FACS. The levels of eosinophil and CD24 expression in different tissues were also evaluated. Results: Eosinophil counts in BM extracted from mice were significantly (p-value=0.0436) higher in CD24-/compared to WT mice, (Fig. 1). Fluorescense intensity was stronger in CD24-/compared to WT mice even though there were no differences in the eosinophil population of mature cells (Fig 2). Eosinophil count was higher in BM from CD24-/compared to WT mice, and lower in blood and addipose tissue (Fig. 3). CD24 expression was higher in peripheral tissues compared to the blood and BM (Fig 4). Conclusion: Based on our preliminary results, it is suggested that CD24 has an important role in negatively regulating eosinophil proliferation/maturation/chemotaxis. Understanding the role of eosinophil in GI disorders may have a large imapct on our understanding of the EGIDs. Targeting specific proteins that play an important role in these processes may lead to novel therapeutic approaches