Rheologic & Vascular Modulators in Sickle Vasoocclusion

描述(申请人提供)：我们假设，在镰状细胞性贫血中，血流动力学异常的来源不仅是异常的红细胞流变学(镰刀状和内皮黏附)，而且是继发于内皮功能障碍的微血管控制的紊乱。这项建议侧重于镰状细胞性贫血中微血管流量和血管闭塞的两个潜在调节剂。首先，缺氧、机械损伤(红细胞病态和粘连)和氧化应激(继发于短暂性脑缺血发作)引起的内皮功能障碍将影响微血管系统对流变学挑战的反应能力。其次，红细胞与血管内皮细胞的异常黏附不仅会导致血管内皮细胞损伤，而且还会在有利的环境中发生。这项修订建议的目的是利用转基因和基因敲除的镰刀鼠品系，在体内条件下研究镰刀背景下异常流变学、氧化应激和血管张力之间的关系。我们将测试以下特定假设：1)测试镰状血流异常和伴随的血流异常(例如，一过性血管闭塞事件)将导致氧化应激、微血管损伤和血管张力异常的假设。为了验证这一假说，我们将研究增强镰状(缺氧)的效果，检查补充精氨酸的效果，并评估选定的抗氧化剂的效果；2)测试红细胞密度和聚合物形成的遗传和实验调节将影响内皮从而影响微血管功能的假说。为了验证这一点，我们将确定抗镰刀状胎儿血红蛋白的效果和对红细胞密度的实验调节；3)验证体内红细胞黏附不仅有助于内皮损伤，而且在微血管阻塞中起关键作用的假说。为了验证这一假说，我们将重点研究内皮细胞激活、特异性黏附分子、低氧、一氧化氮、抗氧化剂的作用，并利用DNA微阵列技术寻找黏附诱导因子调控的基因。拟议的研究涉及具有微循环、血液学、生物化学、细胞生物学和分子生物学专业知识的科学家参与。这些研究有望阐明与人类镰状细胞疾病相关的新机制，并具有潜在的治疗意义。

DESCRIPTION (provided by applicant): We hypothesize that in sickle cell anemia, the source of hemodynamic abnormalities is not only abnormal red cell rheology (sickling and adhesion to endothelium), but a derangement of microvascular controls secondary to endothelial dysfunction. This proposal focuses on two potential modulators of microvascular flow and vasoocclusion in sickle cell anemia. First, endothelial dysfunction in response to hypoxia, mechanical injury (red cell sickling and adhesion), and oxidative stress (secondary to transient ischemic episodes) would affect the ability of microvasculature to respond to rheological challenge. Second, abnormal adherence of red cells to vascular endothelium would not only result in endothelial injury, but also in a prosickling environment. The objective of this revised proposal is to examine the relationship between abnormal rheology, oxidative stress and vascular tone under in vivo conditions in the sickle context, using transgenic and knockout sickle mouse lines. We will test the following specific hypotheses: 1) Test the hypothesis that sickling and attendant flow abnormalities (e.g., transient vasoocclusive events) will cause oxidative stress, microvascular injury and vascular tone abnormalities. To test this hypothesis, we will investigate the effect of enhanced sickling (hypoxia), examine the effect of arginine supplementation, and evaluate the effect of selected anti-oxidants; 2) Test the hypothesis that genetic and experimental modulations of red cell density and polymer formation will impact endothelium and thereby microvascular function. To test this aspect, we will determine the effects of anti-sickling fetal hemoglobin and experimental modulations of red cell density; 3) Test the hypothesis that red cell adhesion in vivo not only contributes to endothelial injury but plays a crucial role in microvascular obstruction. To test this hypothesis, we will focus on the role of endothelial activation, specific adhesion molecules, hypoxia, NO, anti-oxidants, and use DNA microarray technology to identify genes regulated by adhesion inducing factors. The proposed research involves participation of scientists with expertise in microcirculation, hematology, biochemistry, cell biology and molecular biology. These studies are expected to elucidate new mechanisms with relevance to human sickle cell disease and with potential therapeutic implications.