Acute inflammatory intestinal vascular lesions and in situ abnormalities of the plasminogen activation system in Crohn's disease

Objectives The distribution of the intestinal vascular lesions and their re lation with the fibrinolysis process are poorly known in Crohn's disease (C D). The mediators of the plasminogen activator system, namely urokinase-typ e plasminogen activator (u-PA), tissue-type plasminogen activator (t-PA) an d plasminogen activator inhibitor type-1 (PAI-1), are a key complex involve d in fibrinolysis. The aims of this study were: (1) to further define vascu lar lesions and their distribution in the intestine; and (2) to study conco mitantly the qualitative in situ expression and the levels of u-PA, t-PA an d PAI-1 in the ileum of patients with CD. Patients and methods Histological, immunohistochemical and ultrastructural studies of vascular lesions in the resected ileum of 27 patients with CD we re performed and compared with 36 control patients. Levels of u-PA, t-PA an d PAI-1 measured by ELISA methods were compared in healthy and inflamed ile al tissues of 17 patients with CD. Results Acute vascular lesions involving mainly serosal venules and capilla ries were present in 63% of patients with CD vs 3/36 controls and were asso ciated with PAI-1 expression. They were prominent on the mesenteric border beneath macroscopically normal mucosa, In contrast, chronic vascular lesion s were present in all layers beneath mucosal ulcerations, where a significa nt increase of PAI-1 levels was found. Conclusions These results suggest that vascular involvement associated with abnormalities of PAI-1 expression is an early and widespread event in CD. Their prominence on the mesenteric border might explain the characteristic location of CD ulceration along the mesenteric margin. Eur J Gastroenterol Hepatol 11:1113-1119 (C) 1999 Lippincott Williams & Wilkins.