Background: Expression of adhesion molecules is increased in inflamed colonic mucosa, but little is known about their functional activity in vascular endothelium.
Methods: We studied in situ nitroblue tetrazolium reducing activity and expression of E-selectin, ICAM-1, CD31, and VCAM-1 by immunohistochemistry in the same biopsy specimen in controls and patients with ulcerative colitis (UC).
Results: VCAM-1 expression was negative in mucosal vessels. E-selectin-positive vessels were significantly increased in endoscopically active colitis compared with normal mucosa. ICAM-1-positive vessels were consistently found in normal, quiescent UC and active UC. CD31-positive vessels were not significantly increased in quiescent UC and active UC compared with control. Only E-selectin significantly correlated with the histologic grade of inflammation. Nitroblue tetrazolium reducing vessels were increased in inflamed mucosa, and these vessels expressed ICAM-1 and CD31. E-selectin positivity in association with nitroblue tetrazolium reduction was mainly seen in the large mucosal vessels, but capillaries showing nitroblue tetrazolium reduction were rarely positive for E-selectin.
Conclusions: Phenotypic and functional activation of vascular endothelium might be involved in the recruitment of leukocytes and tissue destruction of inflamed colonic mucosa.