Background and Purpose-Previous studies have shown that atherosclerotic lesions express a number of matrix metalloproteinases (MMPs). Here we investigated whether transcript levels of MMP-1, -3, -7, -9, and -12 in carotid atherosclerotic plaques were correlated with histological features and clinical manifestations. Methods-Atherosclerotic plaques (nϭ50) removed from patients undergoing carotid endarterectomy were classified histologically using a system proposed by Virmani et al, and MMP-1, -3, -7, -9, and -12 transcript levels in these tissues were quantified by real-time reverse-transcriptase polymerase chain reaction. Results-Compared to plaques with a thick fibrous cap, those with a thin cap had a 7.8-fold higher MMP-1 transcript level (Pϭ0.006). MMP-3, -7, and -12 were 1.5-fold, 1.8-fold, and 2.1-fold, respectively, higher in thin cap plaques, but the differences did not reach statistical significance. MMP-12 transcript levels were significantly increased in ruptured plaques compared with lesions without cap disruption (Pϭ0.001). MMP-9 transcript levels were similar among the different types of lesion. MMP-1 and -12 transcript levels were significantly higher in plaques from patients with amaurosis fugax, than in those from asymptomatic patients (Pϭ0.029 and Pϭ0.008 for MMP-1 and MMP-12, respectively), than in those from patients with stroke (Pϭ0.027 and Pϭ0.001, respectively), and than in those from patients with transient ischemic attack (Pϭ0.046 and Pϭ0.008, respectively). Conclusions-These data support a role of MMP-1 and -12 in determining atherosclerotic plaque stability.

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The technique appears to represent a significant improvement in the management of this major complication of vascular surgery.