High endothelial venules associated with T cell subsets in the inflamed gut of newly diagnosed Inflammatory Bowel Disease patients.
Horjus Talabur Horje CS, Smids C, Meijer JW, Groenen MJ, Rijnders MK, van Lochem EG, Wahab PJ.
Naive and central memory T lymphocytes (TN and TCM ) can infiltrate the inflamed gut mucosa in Inflammatory Bowel Disease (IBD) patients. Homing of these subsets to the gut might be explained by ectopic formation of tertiary lymphoid organs (TLOs), containing high endothelial venules (HEVs). We aimed to evaluate the presence of HEVs and TLOs in inflamed intestinal mucosa of newly diagnosed, untreated, IBD patients in relation to the presence of TN and TCM lymphocytes.
IBD patients (n=39) and healthy controls (n=8) were prospectively included. Biopsy samples of respectively inflamed and normal intestine were analyzed by immunohistochemistry for lymphocytes (CD3/CD20), blood vessels (CD31) and PNAd expression (MECA-79). TN and TCM lymphocyte subsets were identified by flowcytometric immunophenotyping.
A higher number of HEVs was found in the inflamed colon of patients with ulcerative colitis (median 3.05 HEV/mm2 ; (IQR 0-6.39) and ileum of Crohn's disease patients (1.40; 0-4.34) compared to healthy controls (both 0; P=0.033). A high density of colonic HEVs (HEVhigh ) was associated with increased infiltration of TN and TCM in the inflamed gut (median 87%; IQR 82-93% of T cell population), compared to HEVlow patients (58%; 38-81%; P=0.003). The number of colonic follicles was higher in HEVhigh patients (median 0.54/mm2 ; IQR 0.28-0.84) compared to HEVlow patients (0.25/mm2 ; 0.08-0.45; P=0.031) and controls (0.31/mm2 ; 0.23-0.45; P=0.043).
Increased homing of TN and TCM lymphocytes to inflamed gut tissue in IBD patients might be facilitated by ectopic formation of extrafollicular HEVs and TLOs in a subgroup of patients. This article is protected by copyright. All rights reserved.
© 2016 British Society for Immunology.
Clin Exp Immunol. 2016 Dec 29. doi: 10.1111/cei.12918. [Epub ahead of print]