Increased Plasma Levels of MMP-9 are Associated with Abdominal Aortic Aneurysms

Abstract

Previous investigators have identified disease-specific elevations of the metalloelastase, MMP-9, in aneurysm tissue biopsies. We hypothesized that circulating MMP-9 might also be elevated in patients with aneurysms. The purpose of this study was to compare plasma and aortic tissue MMP-9 levels in patients with infrarenal aneurysms (AAA), patients with symptomatic aortoiliac occlusive disease (AOD), and normals (NA). Methods Sandwich ELISA was used to measure plasma MMP-9 in patients with AAA (n = 22; mean age, 72.7 years), AOD (n = 9; 60.5 years), and NA (n = 8; 35.3 years). MMP-9 levels were also measured in 48-hour superna-tants of organ culture tissue explants from patients with AAA (n = 10; 66.2 years), AOD (n = 5; 50.4 years), and organ donors (n = 7; 48.1 years). Results were reported as mean ± SE and analyzed using ANOVA with multivariate regression. Results Plasma MMP-9 levels were significantly higher in patients with AAA (85.66 ± 11.64 ng/ml) than in AOD patients (25.75 ± 4.159 ng/ml; p < 0.001) or NA (13.16 ± 1.94 ng/ml; p < 0.001). No significant difference in plasma MMP-9 levels between AOD and NA was identified. Patients with multiple aneurysms had significantly higher levels than did patients with an isolated AAA (134.68 ± 17.5 vs 71.03 ± 10.7; p < 0.04). In organ culture, AAA and AOD tissue explants produced significantly higher levels of MMP-9 (3218.5 ± 1115.2 and 1283.1 ± 310.6 ng/gm aortic tissue) than did NA explants (6.14 ± 2.3 ng/gm aortic tissue; p < 0.0001). No significant difference in MMP-9 production between AAA and AOD explants was identified. Conclusions Plasma MMP-9 levels are significantly higher in AAA patients than AOD patients or normal volunteers. Patients with multiple aneurysms have higher levels than those with an isolated AAA. Organ culture studies suggest that diseased aortic tissue is the source of MMP-9. Previous investigators have identified disease-specific elevations of the metalloelastase, MMP-9, in aneurysm tissue biopsies. We hypothesized that circulating MMP-9 might also be elevated in patients with aneurysms. The purpose of this study was to compare plasma and aortic tissue MMP-9 levels in patients with infrarenal aneurysms (AAA), patients with symptomatic aortoiliac occlusive disease (AOD), and normals (NA). Sandwich ELISA was used to measure plasma MMP-9 in patients with AAA (n = 22; mean age, 72.7 years), AOD (n = 9; 60.5 years), and NA (n = 8; 35.3 years). MMP-9 levels were also measured in 48-hour superna-tants of organ culture tissue explants from patients with AAA (n = 10; 66.2 years), AOD (n = 5; 50.4 years), and organ donors (n = 7; 48.1 years). Results were reported as mean ± SE and analyzed using ANOVA with multivariate regression. Plasma MMP-9 levels were significantly higher in patients with AAA (85.66 ± 11.64 ng/ml) than in AOD patients (25.75 ± 4.159 ng/ml; p < 0.001) or NA (13.16 ± 1.94 ng/ml; p < 0.001). No significant difference in plasma MMP-9 levels between AOD and NA was identified. Patients with multiple aneurysms had significantly higher levels than did patients with an isolated AAA (134.68 ± 17.5 vs 71.03 ± 10.7; p < 0.04). In organ culture, AAA and AOD tissue explants produced significantly higher levels of MMP-9 (3218.5 ± 1115.2 and 1283.1 ± 310.6 ng/gm aortic tissue) than did NA explants (6.14 ± 2.3 ng/gm aortic tissue; p < 0.0001). No significant difference in MMP-9 production between AAA and AOD explants was identified. Plasma MMP-9 levels are significantly higher in AAA patients than AOD patients or normal volunteers. Patients with multiple aneurysms have higher levels than those with an isolated AAA. Organ culture studies suggest that diseased aortic tissue is the source of MMP-9.