Proteolysis of the abdominal aortic aneurysm wall and the association with rupture

Purpose: to investigate proteolysis of the abdominal aortic aneurysm (AAA) wall and the association with rupture. Methods: levels of matrix metalloproteinases (MMP-2 and MMP-9) and tissue inhibitor of metalloproteinases (TIMP-1 and TIMP-2) were measured in the walls of medium-sized (5-7 cm in diameter) ruptured AAA (rAAA) (n = 30) and large (greater than or equal to7 cm in diameter) asymptomatic AAA (aAAA) (n = 30). Results. MMP-2 levels (median, range) were significantly higher in the walls of large aAAA (165 ng/g,, AAA tissue, 50-840) than from medium-sized rAAA (110 ng/g AAA tissue, 47-547, p = 0.007). MMP-9 levels were significantly higher in the walls of medium-sized rAAA (107 ng/g AAA tissue, 19-582) than from large aAAA (55 ng/a AAA tissue, 11-278, p = 0,012). TIMP-1 and TIMP-2 levels were equivalent. There was a positive correlation between MMP-2 and the diameter of aAAA (r = 0.54, p = 0.002), but a negative correlation with MMP-9 (r = -0.44, p = 0.017). No significant correlations were found between aAAA diameter and TIMP-1 or TIMP-2. Conclusion: AAA rupture is associated with higher levels of MMP-9. There is no association with TIMP-1 or TIMP-2 levels. MMP-2 levels are positively, whereas MMP-9 levels are negatively, correlated with aAAA size. MMP-9 may play a role in the progression towards rupture, whereas MMP-2 may play a role in expansion.