Division of Cardiovascular Medicine, Department of Medical and Health Sciences, Linköping University, Sweden.
Platelets. 2011;22(8):572-8. doi: 10.3109/09537104.2011.583300. Epub 2011 Jul 14.
Matrix metalloproteinases (MMPs), in particular MMP-9, have been introduced as novel biomarkers in coronary artery disease. Activated platelets are considered to be a major source of the highly elevated levels of MMPs that are detected in serum compared to plasma. The aim of this study was to clarify if activated platelets release MMPs-1, -2 and -9 as measured by enzyme-linked immunosorbent assays (ELISA). Isolated platelets (separated by several procedures) or platelet-rich plasma (PRP) were stimulated by collagen, thrombin or the TLR2 agonist Pam(3)CSK(4). The concentrations of MMPs-1,-2 and -9 in supernatants were determined by ELISA. In addition, a MMP-9 enzyme activity assay was used as well as immunofluorescent staining of MMPs-1,-2 and 9 in platelets. Isolated platelets stimulated by collagen, thrombin or Pam(3)CSK(4) released significant amounts of MMP-1 to the supernatant measured as either pro- or total-MMP-1. However, there was no detectable release of MMP-2 or -9 from isolated platelets. Collagen-stimulated platelets in PRP released MMP-2, but not -9. Before stimulation; platelets were positive for MMPs-1 and -2, but not -9, as assessed by immunofluorescence. Acting as positive controls, neutrophils were found to release significant amounts of MMP-9. Our findings indicate that activated platelets may be a major source of MMP-1 and to a minor extent MMP-2, in peripheral blood. However, in contrast to what has been argued in previous literature, platelets appear to be only negligible contributors to circulating MMP-9.
基质金属蛋白酶（MMPs），特别是 MMP-9，已被引入作为冠状动脉疾病的新型生物标志物。与血浆相比，激活的血小板被认为是血清中检测到的高度升高的 MMP 水平的主要来源。本研究的目的是阐明激活的血小板是否通过酶联免疫吸附测定（ELISA）释放 MMP-1、-2 和-9。通过胶原、凝血酶或 TLR2 激动剂 Pam(3)CSK(4)刺激分离的血小板（通过几种程序分离）或富含血小板的血浆（PRP）。通过 ELISA 测定上清液中 MMP-1、-2 和-9 的浓度。此外，还使用 MMP-9 酶活性测定以及血小板中 MMP-1、-2 和 9 的免疫荧光染色。胶原、凝血酶或 Pam(3)CSK(4)刺激的分离血小板向上清液中释放大量 MMP-1，无论是前体 MMP-1 还是总 MMP-1 均可测量。然而，从分离的血小板中未检测到 MMP-2 或-9 的释放。胶原刺激的 PRP 中的血小板释放 MMP-2，但不释放 MMP-9。在刺激之前；通过免疫荧光评估，血小板对 MMP-1 和 -2 呈阳性，但对 -9 呈阴性。作为阳性对照，发现中性粒细胞大量释放 MMP-9。我们的研究结果表明，在周围血液中，激活的血小板可能是 MMP-1 的主要来源，并且在较小程度上是 MMP-2 的来源。然而，与之前文献中的论点相反，血小板似乎对循环 MMP-9 的贡献微不足道。
