Influence of the treatment used in inflammatory bowel disease on the level of protease activity

Abstract

Introduction: There is growing evidence that intestinal proteases have a role in the pathogenesis of gastrointestinal inflammatory diseases. IBD, which includes Crohn's disease (CD) and ulcerative colitis (UC), has an additional source of proteases represented by infiltrated and activated inflammatory cells. The aim of our study was to determine proteolytic system activity in patients with CD and UC. We limited the number of proteases tested by determining proteases active in acidic, neutral and alkaline pH.Material and methods: The study included 40 patients with IBD – 20 CD patients and 20 UC patients. Among the 20 CD patients, 17 were treated with aminosalicylates, 14 with azathioprine, and 4 with corticosteroids, while 8 patients were undergoing biological treatment. Among the 20 UC patients, 19 were treated with aminosalicylates, 8 with azathioprine, and 3 with corticosteroids. The optimal pH in which the enzymes were active was determined in acidic, neutral, and alkaline buffer environments. We prepared buffers of defined pH from 2.2 to 12.8, separated by 0.2 intervals and then determined proteolytic activity against substrates (gelatine, haemoglobin, ovalbumin, albumin, cytochrome C, and casein). Results: A decrease was observed in the activity of acid proteases (pH 5), alkaline proteases (pH 7), and neutral proteases (pH 7.6 and 8.6) in the groups of CD patients in remission in comparison with the active phase. In the group of patients with CD treated biologically, acid protease activity (pH 5.0) was lower than in CD patients not receiving biological treatment.Activity of neutral (pH 7.0) and alkaline (pH 7.6 and 8.6) proteases in the plasma of patients with UC in remission were lower in comparison to the active phase.Activity of acid (pH 5.0) and alkaline (8.6) protease inhibitors was higher in CD patients in the active phase in comparison to remission. In UC patients with exacerbation of the disease, the activity of alkaline (pH 8.6) protease inhibitors was increased compared to remission.Conclusions: 1. Our research may suggest that the immunomodulatory treatment used in IBD, aimed at reducing the level of leukocytes, may contribute to a reduction in protease activity.2. The decrease in the level of proteases in patients with CD and UC in remission may be a marker suggesting the patients’ response to the treatment.