Brunk D K, Hammer D A
School of Chemical Engineering, Cornell University, Ithaca, New York 14853, USA.
Biophys J. 1997 Jun;72(6):2820-33. doi: 10.1016/S0006-3495(97)78924-0.
Rolling of neutrophils over stimulated endothelial cells is a prerequisite to firm attachment and subsequent transendothelial migration during the inflammatory response. The selectin family of adhesion molecules are thought to mediate rolling by binding counter-receptors that present carbohydrates, such as sialyl Lewis(x) (sLe[x]). Recently we described a cell-free system for rolling using sLe(x)-coated microspheres and E-selectin molecules on inert substrates. We showed that sLe(x)-coated microspheres rolled over E-selectin-IgG chimera substrates with dynamics that are similar to those of leukocytes rolling over stimulated endothelium. In this paper we provide a thorough quantitative description of the dynamics of adhesion for this system. We find that particle rolling velocity increases with increasing wall shear stress and decreases with increasing E-selectin or sLe(x) surface densities. Large changes in the average rolling velocity can occur with small changes in sLe(x) or E-selectin density; however, rolling velocity is more sensitive to E-selectin surface coverage than to the number of sLe(x) molecules on the microspheres. Aided by dimensional analysis, we show that decreasing the wall shear stress or increasing either receptor (E-selectin) or ligand (sLe[x]) surface coverage results in an equivalent decrease in particle rolling velocity. In addition, we find that different Lewis carbohydrates are more effective in mediating rolling on E-selectin, with effectiveness following the trend sialyl Lewis(a) > sialyl Lewis(x) >> sulfated Lewis(x) >> Lewis(x). Rolling velocity fluctuated with time for all carbohydrate-selectin pairs tested, and the magnitude of the velocity fluctuations was linearly proportional to the mean rolling velocity for all combinations of E-selectin site density, sLe(x) site density, wall shear stress, and carbohydrate chemistry tested.
在炎症反应过程中，中性粒细胞在内皮细胞上滚动是其牢固黏附及随后跨内皮迁移的前提条件。黏附分子选择素家族被认为通过与呈现碳水化合物的反受体结合来介导滚动，比如唾液酸化路易斯寡糖（sLe[x]）。最近我们描述了一种无细胞系统，该系统利用包被有sLe[x]的微球和惰性底物上的E选择素分子来实现滚动。我们发现包被有sLe[x]的微球在E选择素 - IgG嵌合体底物上滚动，其动力学过程与白细胞在受刺激的内皮细胞上滚动相似。在本文中，我们对该系统的黏附动力学进行了全面的定量描述。我们发现颗粒滚动速度随着壁面剪应力的增加而增加，随着E选择素或sLe[x]表面密度的增加而降低。sLe[x]或E选择素密度的微小变化可能会导致平均滚动速度发生较大变化；然而，滚动速度对E选择素表面覆盖率的敏感度高于对微球上sLe[x]分子数量的敏感度。借助量纲分析，我们表明降低壁面剪应力或增加受体（E选择素）或配体（sLe[x]）表面覆盖率会导致颗粒滚动速度同等程度地降低。此外，我们发现不同的路易斯碳水化合物在介导E选择素上的滚动方面更有效，其有效性遵循唾液酸化路易斯寡糖（a）>唾液酸化路易斯寡糖（x）>>硫酸化路易斯寡糖（x）>>路易斯寡糖（x）的趋势。对于所有测试的碳水化合物 - 选择素对，滚动速度随时间波动，并且速度波动的幅度与E选择素位点密度、sLe[x]位点密度、壁面剪应力和碳水化合物化学性质的所有测试组合的平均滚动速度呈线性比例关系。
