PECAM-1 (CD 31) mediates transendothelial leukocyte migration in experimental colitis

Transendothelial migration of circulating leukocytes into the colonic wall is a key step in the development of the inflammatory infiltrate in inflammatory bowel disease (IBD). The platelet-endothelial cell adhesion molecule-1 PECAM-1 (CD31) is expressed in the tight junction area of endothelial cells, where it is supposed to support the transmigration process. The aim of this study was to determine the role of PECAM-1 in experimental IBD and to show whether blockade of PECAM-1 has therapeutic effects. Chronic colitis was induced in female BALB/c mice by cyclic oral administration of dextran sodium sulfate (DSS) 3% (wt/vol). Expression of PECAM-1 was visualized by immunohistochemistry. In the treatment group animals received 1 mg/kg anti-PECAM-1 (2H8) ip daily starting on day 26. On day 30 leukocyte adhesion and migration was measured during N2O-isoflurane anesthesia in the distal colon by intravital microscopy. Disease activity index (DAI), histology, and MPO levels were compared with healthy and diseased...