Background: ADAMTS (a disintegrin and metalloproteinase with thrombospondin type 1 motifs) proteases might contribute to plaque destabilisation by weakening the fibrous cap. However, little is known about the expression of ADAMTS proteases in coronary atherosclerotic plaques.
Objective: To examine the expression of ADAMTS proteases in coronary atherectomy samples obtained from patients with acute myocardial infarction (AMI) or stable angina.
Methods: Atherectomy specimens were obtained from 34 patients with AMI (n=23) or stable angina (n=11) who underwent directional coronary atherectomy. The specimens were stained with H&E and analysed immunohistochemically using antibodies specific to ADAMTS-1, -4 and -5; versican cleavage products; and markers for endothelial cells, macrophages and smooth muscle cells.
Results: Baseline characteristics were similar between the two groups. The proportion of CD31 and CD68 immunopositive areas did not differ between the two groups, but the area immunopositive for smooth muscle α-actin was smaller in the AMI group. The relative area immunopositive for ADAMTS-1 in AMI (1.04% (IQR 0.59-2.09%)) was significantly greater than that in stable angina (0.24% (0.15-0.39%); p<0.001). In contrast, the proportion of areas immunopositive for ADAMTS-4 or -5 was similar in the two groups. Areas that stained for ADAMTS-1 largely overlapped with those positive for CD68 and versican cleavage products. The areas immunopositive for ADAMTS-1 were significantly correlated with CD68 immunostained areas (r=0.50, p=0.003).
Conclusions: ADAMTS-1, -4 and -5 were present in human coronary atherosclerotic plaques, and ADATS-1 was more strongly expressed in AMI plaques than in stable plaques. ADAMTS-1 may play a role in plaque instability.