Sickle Cell Adhesion

我们认为镰状细胞(SS)与血管内皮细胞的异常相互作用是导致镰状细胞贫血血管闭塞发生的始动事件。这是因为SS细胞粘附性增加预计会导致微血管传输时间延迟、密集细胞捕获、红细胞镰状增强和花瓶闭塞。我们假设SS细胞的黏附本质上是多因素的，涉及一系列的调节因素和受体-配体相互作用。在建议的研究中，我们将研究SS细胞的“多因素特性” 并探讨其在体内血管闭塞中的作用。这项建议将侧重于特定的配体-受体相互作用，强调内皮激活/损伤和红细胞异质性在SS细胞黏附中的作用。为此，我们将使用最先进的转基因敲除镰刀鼠模型和相关的体外检测系统，并探索干扰这种病理相互作用的治疗方法。利用活体技术和综合生理学方法，我们将检验以下几个方面：1.在体内验证内皮细胞激活和损伤伴随着调节SS细胞与内皮细胞黏附的特定黏附分子表达的假说。为了验证这一假设，我们将研究黏附分子的作用，其表达可能受到内皮激活和损伤的影响。我们将评估内皮von Willebrand因子(VWF)、P-选择素、层粘连蛋白(一种基质蛋白)和内皮αVbeta3整合素(几种黏附蛋白的受体)的作用；2.检验镰状细胞密度类的特征是黏附受体的异质性分布，影响其黏附倾向。为了验证这一假设，我们将研究镰刀形小鼠红细胞密度群体(回缩细胞和致密细胞)中的某些黏附受体，并评估它们在黏附中的作用，重点是整合素相关蛋白(IAP或CD47)的作用；3.检验体内NO将调节红细胞黏附的假说。我们将通过：i)NO促进剂(例如，L-精氨酸补充剂)的效果的调查；ii)NO抑制的效果的评估；iii)抗氧化治疗；iv)羟基尿素治疗来验证这一假设。因此，我们希望现在确定 减轻镰状细胞病中黏附诱导的血流异常和血管闭塞的治疗方法。

We propose that abnormal interaction of sickle (SS) cells with vascular endothelium is the initiating event leading to the development of vascular occlusion in sickle cell anemia. This is because increased SS cell adhesion is expected to result in delayed microvascular transit times, dense cell trapping, enhanced red cell sickling and vase-occlusion. We posit that SS cell adhesion is multifactorial in nature, involving a host of modulating factors and receptor-ligand interactions. In the proposed studies, we will examine the "multifactorial nature" of SS cell adhesion, and explore its role in vascular occlusion in vivo. This proposal will focus on specific ligand-receptor interactions, emphasizing the role of endothelial activation/damage and red cell heterogeneity in SS cell adhesion. To this end, we will use state-of-the-art transgenic-knockout sickle mouse models and relevant ex vivo assay systems, and explore therapeutic approaches that would interfere with this pathologic interaction. Using intravital techniques and an integrated physiological approach, we will test the following: 1. Test the hypothesis that endothelial activation and damage is accompanied by expression of specific adhesion molecules that modulate SS cell adhesion to endothelium in vivo. To test this hypothesis we will investigate the role of adhesion molecules whose expression is potentially affected by endothelial activation and damage. We will evaluate the role of endothelial von Willebrand factor (vWf), P-selectin, laminin (a matrix protein) and endothelial alphaVbeta3 integrin (a receptor to several adhesive proteins); 2. Test the hypothesis that sickle cell density classes are characterized by heterogenous distribution of adhesion receptors affecting their propensity to adhesion. To test this hypothesis, we will investigate sickle mouse red cell density populations (reficulocytcs and dense cells) for certain adhesion receptors and evaluate their role in adhesion, with emphasis on the role of integrin-associated protein (IAP or CD47); 3. Test the hypothesis that NO will modulate red cell adhesion in vivo. We will test this hypothesis by: i) Investigation of the effect of NO promoting agents (e.g., L-arginine supplementation); ii) Evaluation of the effect of NO inhibition; iii) anti-oxidant therapy; iv) hydroxyurea therapy. Thus, we expect to identify now therapeutic approaches to alleviate adhesion-induced flow abnormalities and vaso-occlusion in sickle cell disease.