P058 Proteomic analysis-based discovery of a novel biomarker that differentiates intestinal Behçet’s disease from Crohn’s disease

Abstract Background Intestinal Behçet’s disease (BD) and Crohn’s disease (CD) present similar manifestations, but there are no specific pathognomonic clinical, laboratory, or histological diagnostic tests to differentiate intestinal BD from CD. We used a proteomic approach to discover a novel diagnostic biomarker specific to intestinal BD. Methods The colon mucosa tissue samples were obtained using colonoscopy-guided biopsy of the affected bowel from patients with intestinal BD or CD at the Inflammatory Bowel Disease Clinic of Severance Hospital, Seoul, Korea. Peptides from seven intestinal BD and seven CD patients were extracted and labeled using tandem mass tag (TMT) reagents. The labeled peptides were identified and quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The differentially expressed proteins were further validated using immunohistochemical (IHC) analysis with tissue samples and an ELISA test with serum samples from 20 intestinal BD and 20 CD patients. Results A total of 3,266 proteins were identified using TMT/LC-MS/MS-based proteomic quantification, including 39 candidate proteins differentially expressed between intestinal BD and CD. Beta-2 glycoprotein 1 (APOH) and maltase-glucoamylase (MGAM) showed significantly higher intensity in the IHC staining of the intestinal BD tissues than that of CD tissues. Furthermore, the serum MGAM level was significantly higher in patients with intestinal BD than in patients with CD. Conclusion Our proteomic analysis revealed that some proteins were differentially expressed in intestinal BD patients compared to CD patients. Differential MGAM expression in intestinal BD suggests its role as a potential novel diagnostic biomarker in the differentiation of intestinal BD from CD.