P0046 Proteomic Profiles Associated with Residual Ultrastructural Anomalies in the Epithelium of IBD patients in Endoscopic Remission
Authors: Meuwis M A , Loly J P , Salée C , Massot C , Baiwir D , Fléron M , Mazzucchelli G , Vieujean S , Somja J , Louis E 
Published: January 2025

Abstract

Background
Increased permeability, mucosal barrier and epithelial anomalies (crypt distortion, wider crypt lumen, epithelial gaps) as well as altered tight junctions have been described in active ulcerative colitis (UC) and Crohn’s Disease (CD). Probe based Confocal laser endomicroscopy (pCLE) is able to monitor epithelial anomalies in vivo1. This study aimed at comparing the proteomic profiles of the colonic epithelium associated with pCLE anomalies in UC, CD and non-IBD subjects.

Methods
Biopsies were collected in IBDs in endoscopic remission (n=37) and non-IBD control (CT) (n=10) undergoing colonoscopy with pCLE as previously described1. Biopsy sampled in the right colon and the rectum were analysed by mass spectrometry label free proteomics, with enrichment of epithelial cells using laser capture microdissection2. Comparisons of epithelial protein profiles, in presence (1) or absence (0) of fluorescein leaks were obtained in the colon and rectum, in CD, UC and non-IBD-CT. Significant proteins obtained were confronted and the entire protein profiles were evaluated using Gene Ontology functional annotations.

Results
Colon and rectum samples analyses provided 3227 and 3303 protein identifications (≥50% occurrence in minimum 1 group). Unique proteins (≥50% occurrence in only 1 group) were identified in the colon (n=40) and rectum (n=18). Differential analyses (0vs1) in the colon highlighted 165 and 152 significant proteins in CD and UC respectively, from which 13 were in common. In non-IBD CT (0vs1) 88 proteins were discriminant, with 9 and 6 being shared with CD and UC respectively. In the rectum, 74 and 172 discriminant proteins were obtained in CD and UC, from which 16 were also found significant in colon CD and UC protein lists(0vs1). DAZAP, STK4, LAMC1 and PDCD10 showed similar distribution tendencies in both segments in CD0vs1. While HNRPH1 and 2, VASP, TMX1 and PREP distributions were akin in UC0vs1 in both segments (Fig.1.A). GO analyses highlighted more numerous proteins with a decrease when leaks were observed in IBDs than in non-IBD-CT (Fig.2. Right arm of volcano plots). These proteins are associated with junction proteins, matrix and cytoskeleton, proteasome, protease, peptidase functions, or are involved in apoptosis and innate immune controls and morphogenesis. STK4 product, a key regulator of the HIPPO and MAPK pathways, showed a drop (0&gt;1) in IBDs and non-IBD CT with leaks (Fig.1.B).

Conclusion
This proteomic study reveals proteins with perturbed epithelial distributions associated with pCLE fluorescein leaks. Functional analyses are required to disclose and understand our findings and might confirm very early epithelial key players involved in IBD epithelial homeostasis loss.

References
1Jean-Philippe Loly, Sophie Vieujean, Catherine Reenaers, Catherine Van Kemseke, Laurence Seidel ScD, Edouard Louis, Joan Somja In-Depth Assessment of Endoscopic Remission in Inflammatory Bowel Disease Treated by Anti-TNF or Vedolizumab Inflamm Bowel Dis. 2024 Feb 1;30(2):240-246. doi: 10.1093/ibd/izad066. DOI: 10.1093/ibd/izad066
2.Angela-Maria Merli, Sophie Vieujean, Charlotte Massot, Noella Blétard, Florence Quesada Calvo, Dominique Baiwir, Gabriel Mazzucchelli, Laurence Servais, Odile Wéra, Cécile Oury, Laurence de Leval, Christine Sempoux, Roberto Manzini, Sena Bluemel, Michael Scharl, Gerhard Rogler, Edwin De Pauw, C Coimbra Marques, Arnaud Colard, Anne Vijverman, Philippe Delvenne, Edouard Louis, Marie-Alice Meuwis Solute carrier family 12 member 2 as a proteomic and histological biomarker of dysplasia and neoplasia in ulcerative colitis J Crohns Colitis 2020 Sep 13:jjaa168. doi: 10.1093/ecco-jcc/jjaa168.