What is the role of matrix metalloproteinases (MMPs) in the pathogenesis of abdominal aortic aneurysm (AAA)?

Updated: Jan 08, 2019
  • Author: Saum A Rahimi, MD, FACS; Chief Editor: Vincent Lopez Rowe, MD  more...
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Answer

In AAA, the aortic media appears to degrade by way of a proteolytic process. This implies an increase in the concentration of proteolytic enzymes relative to the concentration of their inhibitors in the abdominal aorta as the individual ages.

Some research has focused on the role of the metalloproteinases, a group of zinc-dependent enzymes responsible for tissue remodeling. Reports have documented increased expression and activity of matrix metalloproteinases (MMPs) in people with AAAs. MMPs and other proteases have been shown to be secreted into the extracellular matrix of AAAs by macrophages and aortic smooth-muscle cells.

MMPs and their inhibitors are present in normal aortic tissue and are responsible for vessel-wall remodeling. Aneurysmal tissue tends to demonstrate increased MMP activity and decreased inhibitor activity, which favor the degradation of elastin and collagen. The mechanism that tips the balance in favor of degradation of elastin and collagen in the aortic wall of AAAs by MMPs and other proteases is not yet known.


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