Background and Purpose-We studied matrix metalloproteinases (MMP) 2, 8, and 9 and extracellular matrix metalloproteinase inducer (EMMPRIN) levels in relation to carotid atherosclerotic plaque characteristics. Methods-Carotid atherosclerotic plaques (nϭ150) were stained and analyzed for the presence of collagen, smooth muscle cell (SMC), and macrophages. Adjacent segments were used to isolate total protein to assess MMP-2 and MMP-9 activities and gelatin breakdown, MMP-8 activity, and EMMPRIN levels. Results-Macrophage-rich lesions revealed higher MMP-8 and MMP-9 activities, whereas SMC-rich lesions showed higher MMP-2 activity. The levels of less glycosylated EMMPRIN-45kD were higher in SMC-rich lesions and lower in macrophage-rich plaques. EMMPRIN-45kD was associated with MMP-2 levels, whereas EMMPRIN-58kD was related to MMP-9 levels. Conclusions-MMP-2, MMP-8, and MMP-9 activities differed among carotid plaque phenotypes. Different EMMPRIN glycosylation forms are associated with either MMP-2 or MMP-9 activity, which suggests that EMMPRIN glycosylation may play a role in MMP regulation and plaque destabilization. Key Words: atherosclerosis Ⅲ carotid arteries Ⅲ carotid artery plaque Ⅲ endarterectomy Ⅲ inflammation Ⅲ matrix metalloproteinases A therosclerosis is characterized by remodeling of the extracellular matrix and the accumulation of lipids and inflammatory cells. 1 Advanced stable atherosclerotic plaques are rich in collagen and smooth muscle cells (SMCs), whereas a large lipid core covered by a thin fibrous cap with a dense inflammatory infiltrate characterizes unstable and ruptured plaques. 2 Increased expressions of matrix metalloproteinases (MMPs) 1, 2, 3, 7, 8, 9, and 13 are found in macrophages and in SMCs covering the shoulder regions of atherosclerotic plaques. 3 Extracellular MMP inducer (EMMPRIN) stimulates the production of different MMPs. 4 EMMPRIN has been identified in human macrophage-rich atheroma. 5 However, the relation of EMMPRIN with plaque characteristics and MMP expression remains to be elucidated. In the present study, carotid endarterectomy plaque characteristics were associated with MMP-2, MMP-8, and MMP-9 activities and EMMPRIN expression levels.
MethodsAthero-Express is an ongoing multicenter study in which carotid atherosclerotic specimen are obtained from patients undergoing endarterectomy. 6 Segments of the culprit lesion of each plaque were studied semiquantitatively for collagen content, SMCs, and macrophages and classified as no/minor or moderately/heavily stained. Moreover, an overall plaque phenotype was assigned to each lesion based on overall appearance.The adjacent segment was used to isolate total protein and MMP-2, MMP-8, and MMP-9. Total MMP activities were measured using the Biotrak activity assays RPN2631, RPN2635, and RPN2634, respectively (Amersham Biosciences). To determine pro-and active MMP-2 and MMP-9 levels in each plaque, zymography was performed as described elsewhere. 7 EMMPRIN expression levels were determined by Western blotting (sc-9753, Santa Cruz Bi...