Extracellular Matrix (ECM) provides structural support and regulates growth factor bioavailability and cytokine activity, infl uencing cellular function and behaviour that modulates physiologic or pathologic aortic remodelling . Metalloproteinase (MMP) imbalance can stimulate proteolytic activity at the ECM level, resulting in tissue degeneration. Furthermore, MMPs activate a variety of non-matriculated elements, including cytokines and chemokines, infl ammatory processes.Most MMPs have the ability to activate MMP precursors, resulting in an enzymatic cascade capable of amplifying MMP proteolytic activity.Through the overexpression of MMP-9, infl ammatory infi ltrate is the primary source of local proteolytic activity.MMP-2 is physiologically expressed by mesenchymal cells in the middle layer of the aortic wall. These two gelatinases, which are largely expressed in AAA, are thought to be the primary proteolytic enzymes responsible for ECM degradation
