Lee Ye-Ming, Lee Jie-Jen, Shen Ming-Yi, Hsiao George, Sheu Joen-Rong
Department of Surgery, Hsinchu Mackay Memorial Hospital, Hsinchu, Taiwan.
Eur J Pharmacol. 2006 May 10;537(1-3):52-8. doi: 10.1016/j.ejphar.2006.03.031. Epub 2006 Mar 17.
The intracellular mechanisms underlying the signaling pathways of activated matrix metalloproteinase-9 (MMP-9) in platelets are not yet completely understood. Therefore, the aim of this study was to further examine the effects of activated MMP-9 in preventing platelet aggregation. In this study, activated MMP-9 time-dependently (3-60 min) inhibited platelet aggregation in washed human platelet suspensions stimulated by agonists. However, activated MMP-9 had no significant effect on the binding of FITC-triflavin to the platelet glycoprotein IIb/IIIa complex. Triflavin is a specific antagonist of the glycoprotein IIb/IIIa complex purified from snake venom. Moreover, activated MMP-9 (21 and 90 ng/ml) markedly decreased the fluorescence intensity of platelet membranes tagged with diphenylhexatriene. The thrombin-evoked increase in pHi was inhibited in the presence of activated MMP-9 (21 and 90 ng/ml). In addition, activated MMP-9 (21 and 90 ng/ml) markedly reduced the electron spin resonance (ESR) signal intensity of hydroxyl radicals in collagen (1 mug/ml)-activated platelets. These results indicate that the antiplatelet activity of activated MMP-9 may involve the following pathways: (1) activated MMP-9 may initially induce conformational changes in platelet membranes and hydroxyl radical formation, leading to inhibition of platelet aggregation; and (2) activated MMP-9 also inhibits the Na(+)/H(+) exchanger, leading to reduced intracellular Ca(2+) mobilization, and ultimately to inhibition of platelet aggregation. This study further provides new insights concerning the effects of activated MMP-9 on platelet aggregation.
血小板中活化基质金属蛋白酶-9（MMP-9）信号通路的细胞内机制尚未完全明确。因此，本研究旨在进一步探究活化MMP-9在预防血小板聚集方面的作用。在本研究中，活化MMP-9在3 - 60分钟内呈时间依赖性地抑制了激动剂刺激的洗涤人血小板悬液中的血小板聚集。然而，活化MMP-9对异硫氰酸荧光素-三黄素与血小板糖蛋白IIb/IIIa复合物的结合没有显著影响。三黄素是从蛇毒中纯化得到的糖蛋白IIb/IIIa复合物的特异性拮抗剂。此外，活化MMP-9（21和90 ng/ml）显著降低了用二苯基己三烯标记的血小板膜的荧光强度。在存在活化MMP-9（21和90 ng/ml）的情况下，凝血酶引起的细胞内pH值升高受到抑制。另外，活化MMP-9（21和90 ng/ml）显著降低了胶原蛋白（1 μg/ml）激活的血小板中羟基自由基的电子自旋共振（ESR）信号强度。这些结果表明，活化MMP-9的抗血小板活性可能涉及以下途径：（1）活化MMP-9可能首先诱导血小板膜的构象变化和羟基自由基的形成，从而导致血小板聚集的抑制；（2）活化MMP-9还抑制钠/氢交换体，导致细胞内钙离子动员减少，最终抑制血小板聚集。本研究进一步为活化MMP-9对血小板聚集的作用提供了新的见解。
