MECHANISMS OF SICKLE ERYTHROCYTE/ENDOTHELIAL ADHESION

镰状红细胞/内皮粘附的机制

• 批准号: 6110138
• 负责人: TIMOTHY M WICK
• 金额: --
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-04-01 至 1999-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6110138
• 关键词: blood proteins; cell adhesion; cell adhesion molecules; cytokine; endotoxins; erythrocyte membrane; erythrocytes; fibrin; gene expression; human subject; human tissue; microcirculation; monoclonal antibody; plasmin; platelet activation; receptor; secretion; sickle cell anemia; sickle cell crisis; thrombin; tumor necrosis factor alpha; vascular endothelium; von Willebrand factor

Sickle cell disease is characterized by intermittent, localized microvascular occlusive crises. Hemoglobin-S deoxygenation leads to morphologic sickling and the formation of rigid erythrocytes which occlude capillaries and obstruct passage of subsequent red cells. Hemoglobin polymerization kinetics are such that the majority of erythrocytes traverse the microcirculation prior to morphologic sickling. However, delayed microvascular transit will increase the likelihood of intracapillary sickling, microvascular occlusion, and pain crisis. We hypothesize that erythrocyte adherence to vascular endothelium in the microcirculation delays erythrocyte transit sufficiently to initiate or propagate sickle cell vaso-occlusion. Erythrocyte/endothelial adherence is likely related to complex changes in the erythrocyte surface, the endothelium, and the vascular milieu. In vitro, sickle red cell adherence quantitatively correlates with the clinical severity of sickle cell disease. Furthermore, acute phase reactants, such as fibrinogen and high molecular weight vWF multimers as well as factors released from activated platelets, promote sickle red cell adherence. In addition, adhesion to large vessel and microvascular endothelium is qualitatively and quantitatively different. We propose to investigate the mechanism of adherence to venous, arterial, and microvascular endothelium during crisis and asymptomatic periods in order to identify plasma components and cell adhesion molecules which promote sickle erythrocyte adherence to cultured endothelium. It is also proposed to investigate the role of endothelial cell stimulation which may occur as a result of activation of coagulation, infection, or pregnancy in sickle patients. Endothelial cell activation would lead to modulation of cell adhesion molecule expression and/or secretion of adhesive proteins. In the proposed experiments, a dynamic in vitro adherence assay which incorporates the fluid shear forces present in the post-capillary venules in vivo will be utilized. Using this system, we will (i) characterize the difference in adhesion of sickle erythrocytes to endothelial cells from microvessels and umbilical vein by determining the effects of agonists and antagonists on adherence, (ii) determine the variability in sickle red cell adherence to endothelial cells from patient to patient and for individual patients during crisis and asymptomatic periods, (iii) identify plasma factors, including soluble factors released from activated platelets, which promote sickle erythrocyte adherence, and (iv) contrast the effects of agonists which presumably stimulate endothelial cells, such as thrombin, endotoxin, plasmin, fibrin(ogen), and TNF on adhesive protein secretion, cell adhesion molecule expression, and adherence.

镰状细胞病的特点是间歇性、局限性 微血管闭塞危机。 血红蛋白-S 脱氧导致 形态镰状化和刚性红细胞的形成 闭塞毛细血管并阻碍后续红细胞的通过。 血红蛋白聚合动力学使得大多数 红细胞在形态学之前穿过微循环 镰刀。 然而，微血管传输延迟会增加 毛细血管内镰状化、微血管闭塞和疼痛的可能性 危机。 我们假设红细胞粘附于血管 微循环中的内皮细胞延迟红细胞转运 足以引发或传播镰状细胞血管闭塞。 红细胞/内皮粘附可能与复杂的变化有关 在红细胞表面、内皮和血管环境中。 在体外，镰状红细胞粘附与 镰状细胞病的临床严重程度。 此外，急性期 反应物，例如纤维蛋白原和高分子量 vWF 多聚体 以及活化血小板释放的因子，促进镰状红 细胞粘附。 此外，对大血管和微血管的粘附 内皮在质量和数量上都有所不同。 我们建议 研究静脉、动脉和静脉的依从机制 危象期和无症状期的微血管内皮细胞 为了识别血浆成分和细胞粘附分子 促进镰状红细胞粘附于培养的内皮细胞。 这是 还提出研究内皮细胞刺激的作用 这可能是由于凝血激活、感染或 镰状细胞病患者怀孕。 内皮细胞活化会导致 调节细胞粘附分子的表达和/或分泌 粘附蛋白。 在所提出的实验中，动态体外 粘附测定结合了存在于液体中的流体剪切力 将利用体内毛细血管后微静脉。 使用这个系统，我们 将 (i) 表征镰状红细胞粘附的差异 通过测定微血管和脐静脉的内皮细胞 激动剂和拮抗剂对依从性的影响，(ii) 确定 镰状红细胞与内皮细胞粘附的变异性 在危机和危机期间，患者之间以及个体患者之间 无症状期，(iii) 识别血浆因素，包括可溶性 活化血小板释放的因子，促进镰状细胞病 红细胞粘附，以及（iv）对比激动剂的作用 可能会刺激内皮细胞，例如凝血酶、内毒素、 纤溶酶、纤维蛋白（原）和 TNF 对粘附蛋白分泌、细胞 粘附分子的表达和粘附。