ENDOTHELIAL DYSFUNCTION AND VASOOCCLUSION IN SICKLE CELL ANEMIA

血管闭塞危象是老年人发病和死亡的主要原因， 镰状细胞病（SCD）。分子级联导致了 血管流动仍然难以捉摸。血液流动缓慢，因此氧气 递送至组织很可能与镰状细胞的粘附有关 (SS)RBC至血管内皮，继发于 SCD常见的血瘀和/或炎症。SS RBC粘附可能 影响血液流动，通过促进，通过表面表达的反- 内皮细胞上的受体，SS RBC和 白细胞我们假设SS RBC粘附于内皮细胞， 细胞氧化应激（通过脂质过氧化物形成和 转录因子NF-κ B的激活），导致表面表达 (SE)细胞粘附分子（CAM）、ICAM-1、E-选择素 BCAM-1同样，感染/炎症导致CAM增加， 表情诱导的VCAM-1的SE导致较小的VCAM-1的更大的粘附。 致密SS RBC通过其α 4 β 1配体。坚持和 中性粒细胞和单核细胞随后的渗出是通过增加 CAM，其作为这些细胞上的整合素的反受体。因为 NF-κ B的活化部分通过脂质过氧化物产生， 氧化应激，如血管阻塞，e计划，以确定是否 bcl-2（一种脂质过氧化物抑制原癌基因）在 培养的人脐静脉内皮细胞（HUVEC）可防止脂质过氧化， 转染HUVEC后，脂质过氧化、NF-κ B活化和CAM诱导 与SS RBC一起孵育。 致密脱氧SS RBC在膜上显示磷脂酰丝氨酸（PS）。 红细胞双层的外部小叶，并通过PS粘附于HUVEC 受体，因此我们将确定是否LPS和细胞因子，诱导 PS受体表达，增强致密缺氧SS RBC粘附。 此外，缺氧增加单核细胞跨内皮迁移， 这可能会导致血管闭塞;因此，我们建议研究 缺氧诱导PMN和单核细胞渗出的机制。我们还将 检查SS RBC、LPS和细胞因子相互作用的机制 HUVEC改变CAM的表达，伴随着PMN的粘附， 单核细胞和增强的SS RBC粘附。而且还要 研究不同来源内皮细胞中CAM诱导 血管床（肺微血管、肺动脉和脑），以及 在这种感应作用中的电位差受各种剪切力的影响 应力，模拟各种血管床中普遍存在的条件。这些 已完成的研究将深入了解新的药理学和/或 分子方法来改善的临床表现 镰状细胞病的血管闭塞

Vasoocclusive crisis is the major cause of morbidity and mortality in sickle cell disease (SCD). The molecular cascade giving rise to slowed blood-vessel flow remains elusive. Slowing of blood flow and hence oxygen delivery to tissues very likely relates to the adherence of sickle cell (SS) RBC to vascular endothelium, localized tissue hypoxia secondary to blood stasis and/or inflammation common in SCD. SS RBC adherence may affect blood flow by promoting, via surface expression of counter- receptors on the endothelium, the additional binding of SS RBC and leukocytes. We hypothesize that SS RBC adherence to endothelium generates cellular oxidant stress (evidenced by lipid peroxide formation and activation of transcription factor NF-kb), leading to a surface expression (SE) of a subset of cell adhesion molecules (CAMs), ICAM-1, E- selectin and BCAM-1. Similarly, infection/inflammation causes an increase in CAM expression. The induced SE of VCAM-1 leads to a greater adherence of less dense SS RBC through their alpha4beta1 ligand. The adherence and subsequent diapedesis of PMN and monocytes occurs via the increased SE of CAMs, which act as counter-receptors for integrins on these cells. Because the activation of NF-kB occurs partly through lipid peroxides generated by oxidant stresses such as vasoocclusion, e plan to determine whether overexpression of bcl-2 (a lipid peroxide-suppressing protooncogene) in cultured human umbilical vein endothelial cells (HUVEC) will prevent lipid peroxidation, NF-Kb activation and a CAM induction when transfected HUVEC are incubated with SS RBC. Dense deoxygenated SS RBC display phosphatidylserine (PS) on the external leaflet of the RBC bilayer and adhere to HUVEC through the PS receptor, so we will determine whether LPS and cytokines, which induce the expression of PS receptor, potentiate dense deoxygenated SS RBC adherence. Additionally, hypoxia increases monocyte trans endothelial migration, which may contribute to vasoocclusion; thus we propose investigating the mechanism of hypoxia-induced diapedesis of PMN and monocytes. We will also examine the mechanism(s) by which SS RBC, LPS and cytokine interaction with HUVEC alters CAM expression, the concomitant adherence of PMN and monocytes, and the augmented SS RBC adherence. Moreover, we will investigate CAM induction in endothelial cells derived from distinct vascular beds (pulmonary microvessel, pulmonary artery and brain), and potential differences in such induction effected by various shear stresses, mimicking conditions prevalent in various vascular beds. These completed studies will provide insight into new pharmacological and/or molecular approaches to ameliorate the clinical manifestations of vasoocclusion in sickle cell disease.