Reduced protease inhibitory capacity in patients with abdominal aortic aneurysms is reversed with surgical repair

Abstract Background: Abdominal aortic aneurysm (AAA) disease is a complex degenerative process that is associated with elevated proteolytic activity. This increased proteolytic activity may be linked to an imbalance in the protease regulatory mechanisms. We hypothesize that reduced AAA plasma inhibitory capacity is related to increased elastolytic activity observed in patients with AAA, which promotes matrix degradation in the aortic wall and AAA expansion. Methods: Preoperative plasma from patients with AAA (n = 86; mean age, 75 ± 8 years) and healthy controls (n = 30; mean age, 72 ± 10 years) was assayed for inhibitory capacity. Postoperative plasma inhibitory capacity was evaluated with comparison of the activity of porcine pancreatic elastase on succinylated elastin substrate, in the presence and absence of AAA and control plasma. Results: AAA plasma showed a significantly reduced capacity to inhibit porcine pancreatic elastase (71.31% ± 1.47%) compared with control plasma (85.52% ± 1.70%; P P P Conclusion: AAA plasma has a significantly reduced inhibitory capacity, which varies with aortic diameter and returns to control levels after surgical repair of the AAA. This suggests that protease regulation is a dynamic balance that changes with AAA progression and may play an important role in AAA progression. (J Vasc Surg 2002;35:792-7.)