ACTIVITIES OF PROTEASES IN PARIETAL THROMBUS OF AORTIC-ANEURYSM

Deterioration of the aortic wall resulting in formation of aneurysm ma y be evoked by increased activity of elastases, collagenases and lysos omal proteases. These enzymes come from macrophages and neutrophil gra nulocytes which are elements of the inflammatory reaction accompanying aneurysm. These cells may also come from parietal thrombus in the ane urysm lumen. The aim of this work was to determine activity of elastas e, cathepsin G, collagenase-like Pz-peptidase and cathepsins A, B, C, D and E in the parietal thrombus of aortic aneurysm. The thrombus was obtained from the lumen of the aortic aneurysm of six patients during operation. Protease activities were determined using specific substrat es at optimum pH. Retracted blood clot was a comparative material. The thrombus of aortic aneurysm showed two-five fold higher activity of e lastases, collagenase-like Pz-peptidase and cathepsins A, D and G in c omparison to the blood clot (P < 0.001). However, activity of cathepsi ns B, C and E in the thrombus was only slightly higher (P < 0.05). Pro longed effect of proteases coming from parietal thrombus on the aneury sm wall could evoke marked degradation of fibrillar proteins resulting in increase of aneurysm. (C) 1998 Elsevier Science B.V.