Biomechanics of P-selectin PSGL-1 bonds: Shear threshold and integrin-independent cell adhesion
Biomechanics of P-selectin PSGL-1 bonds: Shear threshold and integrin-independent cell adhesion
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DOI：
10.1529/biophysj.105.065789
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发表时间：
2006-03-01
影响因子：
3.4
通讯作者：
Neelamegham, S
中科院分区：
文献类型：
--
作者：
Xiao, ZH;Goldsmith, HL;Neelamegham, S
血小板与白细胞的粘连可能导致血栓形成和炎症。我们研究了悬液中未激活的中性粒细胞与凝血酶受体激活肽(TRAP)刺激的血小板或P-选择素珠(Ps-bead)之间的异型相互作用。采用锥板式粘度计，控制切变率为14~3000/S，用流式细胞仪和高速摄像显微镜分析血小板-中性粒细胞和珠中性粒细胞的粘附性。我们观察到，尽管P-选择素或P-选择素糖蛋白配体-1(P-选择素)或P-选择素糖蛋白配体-1(P-选择素糖蛋白配体-1)的阻断抗体单独抑制了血小板-中性粒细胞的黏附，但在140倍/S时，这些试剂完全阻断了3000/S的黏附。单独抗Mac-1在任何切变率下都不改变血小板-中性粒细胞的黏附率，但与选择素拮抗剂有协同作用，它取消了细胞结合。未受刺激的中性粒细胞以整合素非依赖的方式与Ps珠子和激活的血小板结合，这表明纯粹的选择素依赖的细胞黏附是可能的。为了支持这一点，在各种实验系统中，P-选择素或PSGL-1的拮抗剂在剪切下导致先前形成的血小板-中性粒细胞和PS-珠中性粒细胞聚集体解离，包括在全血检测中。在介质粘度和剪切速率不同的研究中，P-选择素PSGL-1结合的剪切阈值也在剪切速率下被注意到，当PS-小球与分离的中性粒细胞碰撞时，剪切阈值为100/S。根据描述线性剪切流中不同尺寸颗粒之间碰撞的生物物理计算，对结果进行了讨论。总体而言，我们的研究揭示了细胞黏附的整合素非依赖性机制和P-选择素PSGL-1相互作用的弱剪切阈值，这可能与生理相关。
Platelet-leukocyte adhesion may contribute to thrombosis and inflammation. We examined the heterotypic interaction between unactivated neutrophils and either thrombin receptor activating peptide ( TRAP)-stimulated platelets or P-selectin-bearing beads ( Ps-beads) in suspension. Cone-plate viscometers were used to apply controlled shear rates from 14 to 3000/s. Platelet-neutrophil and bead-neutrophil adhesion analysis was performed using both flow cytometry and high-speed video-microscopy. We observed that although blocking antibodies against either P-selectin or P-selectin glycoprotein ligand-1 ( PSGL-1) alone inhibited platelet-neutrophil adhesion by; 60% at 140/s, these reagents completely blocked adhesion at 3000/s. Anti-Mac-1 alone did not alter platelet-neutrophil adhesion rates at any shear rate, though in synergy with selectin antagonists it abrogated cell binding. Unstimulated neutrophils avidly bound Ps-beads and activated platelets in an integrin-independent manner, suggesting that purely selectin-dependent cell adhesion is possible. In support of this, antagonists against P-selectin or PSGL-1 caused dissociation of previously formed platelet-neutrophil and Ps-bead neutrophil aggregates under shear in a variety of experimental systems, including in assays performed with whole blood. In studies where medium viscosity and shear rate were varied, a shear threshold for P-selectin PSGL-1 binding was also noted at shear rates,100/s when Ps-beads collided with isolated neutrophils. Results are discussed in light of biophysical computations that characterize the collision between unequal-size particles in linear shear flow. Overall, our studies reveal an integrin-independent regime for cell adhesion and weak shear threshold for P-selectin PSGL-1 interactions that may be physiologically relevant.