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Evaluation of Serum Dipeptidyl Peptidase IV (DPP IV/CD26) Activity in Patients with Chronic Diseases

Dipeptidyl peptidase IV (DPP IV/CD26, EC 3.4.14.5) is a glycoprotein with multiple functions, present in membrane-bound and soluble form in biological fluids. As a serine protease, it could activate or inactivate biologically important peptides. A number of different proinflammatory peptides involved in chronic diseases pathogenesis, are substrates for DPP IV. Therefore, it could play an important role in the modulation of the immune response during inflammatory processes. The aim of this study was to evaluate the changes in serum DPP IV activity in adult patients with chronic diseases including inflammatory bowel diseases (IBD): Crohn’ s disease - CD and ulcerative colitis – UC ; and rheumatoid diseases: rheumatoid arthritis – RA, psoriatic arthritis – PA, and patients with osteoporosis - OP. The diagnosis of CD, UC, RA, PA and OP were established on the basis of clinical history, laboratory, endoscopic and histological data. The CD activity was evaluated using the Crohn´s Disease Activity Index, while the UC activity was evaluated by the Truelove and Witts’ classification. The control group included healthy blood donors. The serum DPP IV activity has been measured spectrofotometrically using Gly-Pro p-nitroanilide as substrate. Enzyme activities are expressed as international unit per liter of serum (U/L). Both serums DPP IV activities in patients with IBD, CD (36, 83 ± ; 9, 74 U/L) and UC (33, 87 ± ; 10, 69 U/L) were statistically significantly decreased compared with the levels in healthy controls (48, 37 ± ; 8, 94 U/L), (p<0, 001). No statistically significant difference in the serum DPP IV activity between patients with CD and UC was found. A statistically significant decrease in serum DPP IV was found in patients with rheumatoid arthritis (30, 45 +/- 3, 04 U/L) compared to the control group (48, 37 +/- 1, 10 U/L) (p<0, 001). In contrast, serum DPP IV activities in patients with psoriatic arthritis (49, 96 +/- 3, 80 U/L) and osteoporosis (43, 11 +/- 3, 9 U/L) were not statistically significantly different from healthy controls. The results of this study sustained the statement that the serum DPP IV is involved in the pathogenesis of chronic diseases. The serum DPP IV activity appears to be useful as an available, non-invasive marker in the diagnosis of the disease activity.

DPP IV/CD26; serum activity; chronic diseases

DOI: 10.1515/CCLM.2008.119