Spatial differences of matrix metalloproteinase-2 and matrix metalloproteinase-9 within abdominal aortic aneurysm wall and intraluminal thrombus

Formation of an abdominal aortic aneurysm is a complex process involving aortic wall degradation. the matrix metalloproteinases (mmps) mainly involved in this process are mmp-2 and mmp-9. most aneurysms contain an intraluminal thrombus. it is suggested that the thrombus’ thickness correlates with the risk of aneurysm rupture and may be a new prognostic factor. the purpose of the present study was to investigate enzyme protein levels in thick (a1) and thin (b1) segments of the thrombus and aneurysm wall sections a (adjacent to a1) and b (adjacent to b1). aneurysm samples from one aneurism sac were collected from 36 patients that underwent aneurysm repair. mmp-2,mmp-9 and a tissue inhibitor of metalloproteinases (timp-1) were measured using enzyme-linked-immunosorbent assay of protein extract. mmp-9 concentrations were significantly higher in b1 samples compared with a1 (113.4 ± 118.0 versus 63.0 ± 61.2,p = 0.004),a (113.4 ± 118.0 versus 31.7 ± 30.0,p < 0.001) or b (113.4 ± 118.0 versus 39.5 ± 41.5,p < 0.001). likewise mmp-9/timp-1 ratio was elevated in b1 compared with a1 (18.9 ± 27.8 versus 9.1 ± 10.6,p = 0.017),a (18.9 ± 27.8 versus 2.5 ± 2.2,p < 0.001) or b (18.9 ± 27.8 versus 3.6 ± 4.5,p < 0.001). mmp-2 and timp-1 were higher in a compared with a1 (18.4 ± 8.5 versus 7.2 ± 7.6,p < 0.001; 14.3 ± 5.9 versus 8.5 ± 5.4,p < 0.001,respectively) and b1 (18.4 ± 8.5 versus 5.2 ± 2.9,p < 0.001; 14.3 ± 5.9 versus 8.9 ± 4.9,p < 0.001,respectively) as well as in b compared with a1 (15.9 ± 7.3 versus 7.2 ± 7.6,p < 0.001; 13.0 ± 5.0 versus 8.5 ± 5.4,p < 0.001,respectively) and b1 (15.9 ± 7.3 versus 5.2 ± 2.9,p < 0.001; 13.0 ± 5.0 versus 8.9 ± 4.9,p = 0.003,respectively). there were significant correlations between thin thrombus timp-1 and thrombus thickness (β = –0.24,p = 0.021) and between thin thrombus mmp-9/timp-1 ratio and thrombus thickness (β = 1.75,p = 0.003). our study has revealed that the presence of thrombi with thin segments in the aneurysm sac,associated with higher proteolytic activity,could possibly be used as a potential indicator of a rupture site. © 2016,polish physiological society. all rights reserved.