van Zanten G H, Connolly T M, Schiphorst M E, de Graaf S, Slootweg P J, Sixma J J
Department of Haematology, University Hospital Utrecht, The Netherlands.
Arterioscler Thromb Vasc Biol. 1995 Sep;15(9):1424-31. doi: 10.1161/01.atv.15.9.1424.
Salivary glands of the leech Haementeria officinalis contain a protein, leech antiplatelet protein (LAPP). This protein was cloned and expressed in yeast and blocks collagen-mediated platelet aggregation and the adhesion of platelets to collagen-coated plates under static conditions. In the current study we investigated the effect of rLAPP on platelet deposition to collagen and collagen-rich surfaces under flow conditions. rLAPP completely inhibited platelet adhesion on collagen types I, III, and IV with IC50 values of 70, 600, and 90 nmol/L, respectively (shear rate = 1600 s-1). Approximately 10-fold more rLAPP was required to obtain a similar inhibition at a low shear rate of 375 s-1. rLAPP caused a concentration-dependent inhibition of binding of 125I-von Willebrand factor (vWF) to collagen type III and was able to displace prebound vWF even after 24 hours. Since platelet adhesion at low shear rate is less dependent on vWF than at high shear rate, this property of rLAPP may explain why less rLAPP is needed at high shear rate than at low shear rate to produce the same effect. Platelet adhesion to collagen type VI was only partially inhibited by rLAPP (maximal 44% with 3 mumol/L rLAPP). rLAPP also caused a pronounced inhibition of platelet deposition to cross sections of human atherosclerotic coronary arteries but had no effect on matrices of cultured human umbilical vein endothelial cells. rLAPP is a potent platelet adhesion inhibitor at high shear rate, which binds to collagen and works by inhibiting binding of vWF to collagen.
药用南美水蛭的唾液腺含有一种蛋白质，即水蛭抗血小板蛋白（LAPP）。该蛋白在酵母中被克隆并表达，在静态条件下可阻断胶原蛋白介导的血小板聚集以及血小板与胶原包被平板的黏附。在本研究中，我们研究了重组水蛭抗血小板蛋白（rLAPP）在流动条件下对血小板在胶原蛋白和富含胶原蛋白表面沉积的影响。rLAPP完全抑制血小板在I型、III型和IV型胶原蛋白上的黏附，其半数抑制浓度（IC50）值分别为70、600和90 nmol/L（剪切速率 = 1600 s-1）。在375 s-1的低剪切速率下，需要大约10倍量的rLAPP才能获得类似的抑制效果。rLAPP对125I-血管性血友病因子（vWF）与III型胶原蛋白的结合产生浓度依赖性抑制，甚至在24小时后仍能取代预先结合的vWF。由于低剪切速率下的血小板黏附比高剪切速率下对vWF的依赖性更小，rLAPP的这一特性可能解释了为什么在高剪切速率下比低剪切速率下需要更少的rLAPP就能产生相同的效果。rLAPP仅部分抑制血小板与VI型胶原蛋白的黏附（3 μmol/L rLAPP时最大抑制率为44%）。rLAPP还显著抑制血小板在人类动脉粥样硬化冠状动脉横截面上的沉积，但对培养的人脐静脉内皮细胞基质没有影响。rLAPP是一种在高剪切速率下有效的血小板黏附抑制剂，它与胶原蛋白结合并通过抑制vWF与胶原蛋白的结合发挥作用。
