Platelets release matrix metalloproteinase-2 in the coronary circulation of patients with acute coronary syndromes: possible role in sustained platelet activation.

Aims. To investigate whether selected matrix metalloproteinases (MMPs) are released in the coronary circulation of patients with acute coronary syndrome (ACS), whether this release is related to platelet activation, and if it contributes to sustained platelet activation. Methods and Results. Blood from the aorta (Ao) and the coronary sinus (Cs) was obtained from 21 controls (non cardiac chest pain), 24 stable angina (SA) and 30 ACS patients, before performing PTCA. Selected MMPs, some platelet activation- and atheroma-related markers, and the platelet activation-potentiating activity of plasma were measured. Total MMP-2, active MMP-2, and MMP-9 were released in the coronary circulation of patients with ACS, but not of those with SA or controls. Similarly, transcoronary gradients of TG and PF4, two platelet-specific proteins, and of sCD40L and sPLA2, markers of inflammation and platelet activation, were higher in ACS patients than in the other groups. In contrast, plasma MCP-1, a platelet-unrelated marker of atherogenesis, was not increased in the Cs compared with Ao in any of the groups. Transcoronary gradients of both -TG and sPLA2 correlated with those of total and active MMP-2 in ACS, but not in controls or SA. Plasma from the Cs of ACS patients potentiated platelet activation, an effect suppressed by the specific MMP-2-inhibitor, TIMP-2. Conclusions. MMP-2 is released in the coronary circulation of ACS patients, derives in part from activated platelets, and it may contribute to sustained intracoronary platelet activation.