Plasminogen activators in abdominal aortic aneurysmal disease

Area of Science:

• Cardiovascular Biology
• Molecular Medicine
• Pathology

Background:

• Abdominal aortic aneurysms (AAA) are characterized by extracellular matrix (ECM) destruction in the aortic wall, notably elastin.
• The fibrinolytic system, involving plasminogen activators (PA) and plasmin, mediates ECM proteolysis.
• Plasmin can directly degrade ECM and activate matrix metalloproteases (MMP), while also enhancing macrophage-mediated ECM destruction.

Purpose of the Study:

• To investigate the role of plasminogen activators (PA) and matrix metalloproteases (MMP) in the pathogenesis of abdominal aortic aneurysms (AAA).
• To examine the localization and expression levels of PA and MMP in AAA tissue.
• To understand the synergistic interaction between macrophages, PA, and MMP in AAA-related aortic wall degradation.

Main Methods:

• Analysis of urokinase-type plasminogen activator (u-PA) and tissue-type plasminogen activator (t-PA) levels and localization in AAA tissue.
• Quantification of plasmin and matrix metalloprotease (MMP) levels in AAA tissue.
• Assessment of mRNA expression for PA and MMP in AAA compared to normal and atherosclerotic aorta.
• Localization of PA and MMP expression to macrophages within AAA tissue.

Main Results:

• Elevated levels of both u-PA and t-PA were documented in AAA tissue.
• u-PA and t-PA were localized to macrophages within the inflammatory infiltrate characteristic of AAA.
• Elevated mRNA expression of both PA types was observed in AAA compared to normal and atherosclerotic aorta.
• Plasmin and MMP levels were elevated in AAA tissue, with MMP expression also localized to macrophages.

Conclusions:

• The findings suggest a significant role for the fibrinolytic system, specifically PA, in AAA pathogenesis.
• Macrophages, PA, and MMP appear to act synergistically to degrade the aortic wall in AAA.
• Targeting these pathways may offer therapeutic strategies for managing AAA.