Sickle Cell Adhesion

我们认为镰状细胞（SS）与血管内皮的异常相互作用是导致镰状细胞性贫血血管闭塞发展的起始事件。这是因为SS细胞粘附增加预期会导致微血管通过时间延迟、致密细胞捕获、红细胞镰状化增强和血管闭塞。我们认为SS细胞的粘附是多因素的，包括许多调节因子和受体-配体相互作用。在本研究中，我们将探讨SS细胞的“多因素性 粘附，并探讨其在体内血管闭塞中的作用。该提案将集中在特定的配体-受体相互作用，强调内皮细胞活化/损伤和红细胞异质性在SS细胞粘附中的作用。为此，我们将使用最先进的转基因敲除镰状小鼠模型和相关的离体检测系统，并探索干扰这种病理相互作用的治疗方法。使用活体技术和综合生理方法，我们将测试以下内容：1。检验内皮活化和损伤伴随着体内调节SS细胞与内皮粘附的特异性粘附分子表达的假设。为了验证这一假设，我们将研究粘附分子的作用，其表达可能受到内皮细胞活化和损伤的影响。我们将评估内皮血管性血友病因子（vWf），P-选择素，层粘连蛋白（基质蛋白）和内皮α V β 3整合素（几种粘附蛋白的受体）的作用。检验镰状细胞密度分类的特征在于粘附受体的异质性分布影响其粘附倾向的假设。为了验证这一假设，我们将研究镰状小鼠红细胞密度群体（reficulocytcs和致密细胞）的某些粘附受体，并评估其在粘附中的作用，重点是整合素相关蛋白（IAP或CD 47）的作用; 3.验证NO在体内调节红细胞粘附的假设。我们将通过以下方式检验这一假设：i）研究NO促进剂（例如，L-精氨酸补充）; ii）NO抑制作用的评价; iii）抗氧化剂疗法; iv）羟基脲疗法。因此，我们希望现在就能确定 减轻镰状细胞病中粘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.