Abstract Background Intestinal barrier impairment is a hallmark of inflammatory bowel disease (IBD), driving immune activation, neutrophil-mediated injury, and chronic mucosal damage. While endoscopy and molecular assessment provide insight into epithelial and vascular integrity, the ability of histologic features to predict functional barrier impairment and clinical outcomes remains insufficiently defined 1,2. This study aimed to: 1) determine whether histologic activity predicts intestinal barrier dysfunction assessed by advanced imaging; 2) identify multilevel predictors of major adverse outcomes (MAOs) at 12-month follow-up by integrating histologic, advanced imaging and molecular data. Methods Patients with IBD undergoing endoscopy for disease assessment or surveillance were included. In vivo assessment of epithelial and vascular barrier was performed using probe-based confocal laser endomicroscopy (pCLE) and endocytoscopy (ECS), quantified with validated scoring systems 3,4. Parallel mucosal biopsies were collected for histologic evaluation and protein expression analysis. Histologic inflammation was graded according to PHRI and RHI scores. Expression of epithelial tight junction (ZO-1, Claudin-2, E-cadherin) and vascular barrier proteins (CD31, PV1) was analysed on 131 biopsies by confocal microscopy and quantified with QuPath. Correlation among histology, advanced imaging, and protein-based barrier expression was assessed. Predictive ability for MAOs at 12-month follow-up was determined. Results Eighty-eight IBD patients, 52 Crohn’s disease CD and 36 Ulcerative Colitis UC were included. Barrier impairment was identified by advanced imaging in 35/52 (67%) CD patients and 28/36 (78%) UC patients. Neutrophilic and chronic infiltrate correlated with barrier impairment (r = 0.3-0.6; p 0.01), mainly with CD. Neutrophils in both the epithelium and the lamina propria strongly correlated with epithelial barrier dysfunction (r = 0.6; p 0.01). Conversely, chronic infiltrate significantly correlated with vascular barrier impairment (r = 0.5; p 0.01) and PV1 expression (r = 0.3; p 0.01) in CD, suggesting more endothelial involvement than UC (Table 1). Finally, in CD, patients with both barrier alterations (advanced imaging + PV1 expression) and a cellular infiltrate experienced a higher rate of MAOs than those with barrier changes or infiltrate alone (Log-Rank p 0.01), underscoring the value of integrated, multilevel assessment (Fig.1). Conclusion Histology provides a robust predictor of epithelial and vascular barrier dysfunction in IBD. When assessed in vivo using advanced imaging combined with high-resolution endoscopic and molecular profiling, it enables multidimensional evaluation of barrier impairment, enhancing the prediction of disease outcomes. References: 1.Horowitz A, Chanez-Paredes SD, Haest X, Turner JR. Paracellular permeability and tight junction regulation in gut health and disease. Nat Rev Gastroenterol Hepatol. 2023;20(7):417-432. doi:10.1038/s41575-023-00766-3 2.Brescia P, Rescigno M. The gut vascular barrier: a new player in the gut-liver-brain axis. Trends Mol Med. 2021;27(9):844-855. doi:10.1016/j.molmed.2021.06.007 3.Iacucci M, Jeffery L, Acharjee A, et al. Computer-Aided Imaging Analysis of Probe-Based Confocal Laser Endomicroscopy With Molecular Labeling and Gene Expression Identifies Markers of Response to Biological Therapy in IBD Patients: The Endo-Omics Study. Inflamm Bowel Dis. 2023;29(9):1409-1420. doi:10.1093/ibd/izac233 4.Majumder S, Santacroce G, Maeda Y, et al. Endocytoscopy with automated multispectral intestinal barrier pathology imaging for assessment of deep healing to predict outcomes in ulcerative colitis. Gut. 2024;73(10):1603-1606. Published 2024 Sep 9. doi:10.1136/gutjnl-2024-332894 Conflict of interest: Iacucci, Marietta: Grant: Pentax, Olympus, Eli lilly,Helmsley Personal Fees: Pentax, Pfitzer, Janssen,EliLilly,J & J Lo Bello, Antonio: No conflict of interest Zammarchi, Irene: No conflicts Pugliano, Cecilia Lina: None Majumder, Snehali: No conflict of interest to declare. Hughes, Robert: No conflict of interest Crotty, Rory: No conflict of interest Hayes, Brian: No conflict of interest Burke, Louise: No conflict of interest Ghosh, Subrata: None None None
Iacucci et al. (Thu,) studied this question.