SICKLE RBC, INTERMITTENT HYPOXIA AND VASCULAR PATHOLOGY

镰状红细胞独特的氧感应能力定义了镰状细胞病（SCD）病理，由镰状血红蛋白在低氧分压（PO2）下聚合引起。我们的长期目标是了解间歇性缺氧如何改变红细胞膜及其与血管内皮（E.C.）的相互作用。我们假设了一个新的事件链，其中间歇性缺氧会产生溶血磷脂酸（LPA），一种强大的脂质介质，暴露红色表面的磷脂酰丝氨酸（PS），并消耗血浆凝胶蛋白水平，LPA的缓冲蛋白。我们认为缺氧条件下由E.C.产生的一氧化氮（NO）和相关化合物会根据血红蛋白浓度和类型（HbS或HbF）影响这一过程。SCD中炎症介质分泌磷脂酶A2 （sPLA2）水平升高将进一步加剧这一过程，最终导致血管引流。为了解决红细胞- ec的这些方面。为了研究间歇性缺氧对镰状红细胞的影响，我们制定了以下具体目标：2。探讨间歇性缺氧对红细胞内皮相互作用的影响。探讨镰状细胞病患者及镰状细胞病小鼠模型间歇性缺氧的影响因素。为了实现这些目标，我们将采用多学科方法，利用生物化学和细胞生物学技术，在明确的体外间歇性缺氧条件下，在一个独特的培养系统中，单独或共同研究RBC和E.C.。我们将在体外测量LPA的生成并确定其作用，确定血浆肌动蛋白结合蛋白凝胶的LPA缓冲能力，并确定E.C.衍生NO及其衍生物的作用。我们将把体外研究数据与血管闭合性危象、中风和急性胸综合征的SCD患者以及我们的SCD小鼠模型中LPA、凝胶和NO足迹的体内研究结果联系起来。总之，我们的研究结果可能为SCD的治疗提供新的治疗方案。

The unique oxygen sensing capacity of the sickle red cell defines sickle cell disease (SCD) pathology resulting from the polymerization of sickle hemoglobin under low partial oxygen pressure (PO2). Our long term goal is to understand how intermittent hypoxia changes the red cell membrane and its interactions with vascular endothelium (E.C.). We hypothesize a novel chain of events in which intermittent hypoxia will generate lysophosphatidic acid (LPA), a powerful lipid mediator, exposes phosphatidyl serine (PS) on the red surface, and depletes plasma gelsolin levels, the buffer protein for LPA. We pose that nitric oxide (NO) and related compounds, generated by E.C. under hypoxia will affect this process depending on the hemoglobin concentration and type (HbS, or HbF). Increased levels of the inflammatory mediator secretory phospholipase A2 (sPLA2) in SCD will further exacerbate this process which will ultimately lead to vascular drainage. To address these aspects of RBC-E.C. interaction, we have developed the following specific aims: I. To investigate the effect of intermittent hypoxia on sickle red cells. II. To investigate intermittent hypoxia on red cell-endothelial interaction, and III. To evaluate factors of intermittent hypoxia in sickle cell patients and murine models of sickle cell disease. To accomplish these goals, we will use a multidisciplinary approach using biochemistry and cell biology techniques to study RBC and E.C. under well-defined conditions of intermittent hypoxia in vitro, in a unique incubation system, separately or together. We will measure the generation of LPA in vitro and define its role, determine the LPA buffering capacity of the plasma actin-binding protein gelsolin, and define the role for E.C. derived NO and its derivatives. We will relate the data of in vitro studies to in vivo findings of LPA, gelsolin and NO footprints in SCD patients with vasoocclusive crisis, stroke and acute chest syndrome as well as our murine model for SCD. Together, our results may indicate novel treatment regiments in the management of SCD.