Cell-free rolling mediated by L-selectin and sialyl Lewisx reveals the shear threshold effect
Cell-free rolling mediated by L-selectin and sialyl Lewisx reveals the shear threshold effect
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DOI：
10.1016/s0006-3495(00)76484-8
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发表时间：
2000-11-01
影响因子：
3.4
通讯作者：
Hammer, DA
中科院分区：
文献类型：
--
作者：
Greenberg, AW;Brunk, DK;Hammer, DA
粘附分子的选择素家族介导中性粒细胞对受刺激的内皮细胞的附着和滚动。炎症反应的这一步是；牢固依附和外渗的先决条件。我们已经报道了涂有唾液酸Lewis(x) （sLe(x)）的微球特异性地相互作用并在e -选择素和p -选择素底物上滚动（Brunk等）。1996年;罗杰斯等人，2000)。本文将无细胞系统的应用扩展到流动条件下l-选择素与sLe(x)相互作用的研究。我们发现sLe(x)微球特异性地与l -选择素底物相互作用并在其上滚动。滚动速度随壁面增大而增大；随l -选择素浓度的增加而降低。滚动速度很快，在25到225妈妈/秒之间，典型的l -选择素相互作用。轧制速度的变异性，由轧制速度的方差量化，与轧制速度成线性比例。轧制通量随壁剪应力和l -选择素位点密度的变化而变化。当l -选择素的密度为880个位点/cm(2)时，sLe(x)涂层微球的滚动通量相对于剪切应力在0.7达因/cm(2)时达到明显的最大值。这种行为，其中滚动相互作用的维持和促进选择需要剪应力高于阈值，被称为剪切阈值效应。我们发现，当l -选择素密度为800个位点/个时，这种效应的幅度最大(2)，并随着l -选择素位点密度的增加而逐渐减弱。我们的研究首次揭示了无细胞体系的剪切阈值效应，并首次揭示了剪切阈值效应对重组体系中l -选择素位点密度的依赖性。我们在无细胞系统中重建剪切阈值效应的能力强烈表明，该效应的起源是l-选择素与其配体相互作用的物理化学，并且在很大程度上消除了细胞特征，如可变形性或地形作为其原因。
The selectin family of adhesion molecules mediates attachment and rolling of neutrophils to stimulated endothelial cells. This step of the inflammatory response is; a prerequisite to firm attachment and extravasation. We have reported that microspheres coated with sialyl Lewis(x) (sLe(x)) interact specifically and roll over E-selectin and P-selectin substrates (Brunk et al.. 1996; Rodgers et al., 2000). This paper extends the use of the cell-free system to the study of the interactions between L-selectin and sLe(x) under flow. We find that sLe(x) microspheres specifically interact with and roll on L-selectin substrates. Rolling velocity increases with wall !;hear stress and decreases with increasing L-selectin density. Rolling velocities are fast, between 25 and 225 mum/s, typical of L-selectin interactions. The variability of rolling velocity, quantified by the variance in rolling velocity, scales linearly with rolling velocity. Rolling flux varies with both wall shear stress and L-selectin site density. At a density of L-selectin of 880 sites/mum(2), the rolling flux of sLe(x) coated microspheres goes through a clear maximum with respect to shear stress at 0.7 dyne/cm(2). This behavior, in which the maintenance and promotion of rolling interactions on selectins requires shear stress above a threshold value, is known as the shear threshold effect. We found that the magnitude of the effect is greatest at an L-selectin density of 800 sites/mum(2) and gradually diminishes with increasing L-selectin site density. Our study is the first to reveal the shear threshold effect with a cell free system and the first to show the dependence of the shear threshold effect on L-selectin site density in a reconstituted system. Our ability to recreate the shear threshold effect in a cell-free system strongly suggests the origin of the effect is in the physical chemistry of L-selectin interaction with its ligand, and largely eliminates cellular features such as deformability or topography as its cause.