Expression of urokinase-type plasminogen activator in the mucosal lesions of inflammatory bowel disease

The expression of plasminogen activators was analysed in mucosal homogenates from inflammatory bowel disease patients to determine whether the urokinase-type (u-PA) is implicated in the pathogenesis of mucosal tissue injury. Homogenates of mucosal biopsy tissue from ulcerative colitis, Crohn's disease, infectious colitis and normal control patients were subjected to polyacrylamide gel electrophoresis. The types of plasminogen activator present were detected by zones of lysis in a fibrin-agarose gel overlay. All the tissues studied displayed tissue plasminogen activator activity (t-PA). In ulcerative colitis, 18 of the 19 diseased colon biopsies, but none of six biopsies from uninvolved areas of the same colon, showed u-PA activity. Similar results were found in 12 Crohn's disease patients. Biopsies from the infectious colitis group and from radiation colitis patients also showed both u-PA and t-PA activity. The age, sex, duration of disease, and presence and type of treatment did not affect u-PA expression in the inflamed mucosa. The results suggest that u-PA may be implicated in the mediation of tissue injury in the inflamed intestinal mucosa.