Sickle Cell Disease G6PD

镰状细胞病 G6PD

• 批准号: 7828052
• 负责人: Jane A Leopold
• 金额: $ 18.65万
• 依托单位: BOSTON MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-05-04 至 2012-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7828052
• 关键词: Acute; Adenovirus Vector; Adhesions; Agonist; Aldosterone; Aldosterone Antagonists; Antioxidants; Aorta; Arginine; Atherosclerosis; Bioavailable; Biological Assay; Blood Flow Velocity; Blood Vessels; Boston; Calcium; Catheterization; Cell Adhesion Molecules; Cell Communication; Cell Volumes; Cell physiology; Cells; Centrifugation; Chronic; Clinical Research; Cyclic GMP; Dehydration; Disease; E-Selectin; Endothelial Cells; Endothelium; Enzymes; Erythrocytes; Exhibits; Exposure to; Functional disorder; Gene Transfer; Generations; Genetic; Glucosephosphate Dehydrogenase; Glucosephosphate Dehydrogenase Deficiency; Glutathione; Hemoglobin; Hemolysis; Hydrogen Peroxide; Hyperaldosteronism; Hypoxia; In Vitro; Individual; Infection; Intercellular Adhesion Molecules; Kidney; Lead; Measures; Mediating; Mesentery; Metabolism; Molecular; Mus; Muscle Rigidity; NADP; Nitric Oxide; Nitric Oxide Synthase; Organ; Oxidation-Reduction; Oxygen; Patients; Pentosephosphate Pathway; Phenotype; Physiologic pulse; Production; Protein Isoforms; Reactive Nitrogen Species; Reactive Oxygen Species; Renin; Reporting; Sickle Cell; Sickle Cell Anemia; Small Interfering RNA; Source; Superoxides; System; Testing; Variant; Vascular Cell Adhesion Molecule-1; Vascular Diseases; Vascular resistance; Video Microscopy; Wild Type Mouse; arteriole; cofactor; density; eplerenone; glucose-6-phosphate dehydrogenase A-; improved; in vivo; indexing; mouse model; overexpression; oxidant stress; polymerization; response; vascular inflammation

In patients with sickle cell disease (SCD), exposure to hypoxia and deoxygenation of intra-erythrocytic Hemoglobin S, or dehydration, results in hemoglobin polymerization, erythrocyte rigidity leading to microvascular occlusion, and end-organ damage. In addition, these individuals exhibit endothelial dysfunction that exists in the absence of overt atherosclerotic vascular disease. This vasculopathy is characterized by increased endothelial oxidant stress, decreased bioavailable nitric oxide (NO), and increased expression of adhesion molecules. While this phenomenon has been attributed, in part, to decreased NO owing to hemolysis and sequestration of NO by cell-free hemoglobin, accumulating evidence suggests that endothelial dysfunction in SCD may result from an aldosterone-mediated decrease in glucose-6-phosphate dehydrogenase (G6PD) activity. G6PD, the first and rate-limiting enzyme of the pentose phosphate pathway, is the principal source of NADPH, a reducing equivalent and cofactor for the endothelial isoform of nitric oxide synthase. As such, G6PD regulates endothelial redox state and NO production. In SCD, dehydration due to renal dysfunction is a common phenomenon; (sub)acute or chronic dehydration activates the renin-aldosterone system and clinical studies have shown that SCD patients have elevated levels of renin and aldosterone. Furthermore, elevated levels of aldosterone have been shown to increase intracellular Ca2+ stores and, thereby, may lead to Gardos channel activation, dehydration of erythrocytes, and increased adhesion to the endothelium to augment endothelial dysfunction. Hyperaldosteronism has been associated with endothelial dysfunction and vascular inflammation in the absence of erythrocyte adhesion, and, recently, we have shown that mildly elevated levels of aldosterone cause an acquired form of G6PD deficiency in cultured endothelial cells and in vivo, resulting in decreased G6PD expression and activity to increase oxidant stress, decrease bioavailable NO, and impair vascular reactivity. Although early studies reported no influence of G6PD deficiency on hemolysis in SCD patients, these studies examined individuals with the G6PD A- variant, who had only modest reductions in G6PD activity (Class III), and did not examine the consequences of concomitant genetic G6PD deficiency on endothelial function. We have found that an acquired G6PD deficiency, as occurs when aldosterone levels are mildly elevated, is associated with >80% reduction in G6PD activity, akin to a Class V deficiency, and this degree of G6PD deficiency is associated with significant endothelial dysfunction. As the central theme of this proposal, we, therefore, hypothesize that endothelial dysfunction associated with SCD results from aldosterone-mediated acquired G6PD deficiency. To examine this hypothesis, we propose the following specific aims: 1) Characterize the functional consequences of aldosterone-mediated acquired G6PD deficiency in SCD endothelial cells in vitro. 2) Determine the influence of aldosterone and decreased G6PD activity on erythrocyte-endothelial cell interactions in SCD in vitro. 3) Evaluate the influence of aldosterone-mediated acquired G6PD deficiency on endothelial function and vascular reactivity in vivo in a mouse model of SCD.

在患有镰状细胞疾病（SCD）的患者中 血红蛋白S或脱水导致血红蛋白聚合，红细胞刚性导致 微血管阻塞和末端器官损伤。此外，这些人表现出内皮 在没有明显的动脉粥样硬化血管疾病的情况下存在的功能障碍。这种血管病是 其特征是内皮氧化剂应激增加，生物利用一氧化氮（NO）的降低，并且 粘附分子的表达增加。虽然这种现象已被部分归因于 由于溶血和无细胞无细胞血红蛋白的NO隔离而减少了NO，积累 有证据表明，SCD中的内皮功能障碍可能是由醛固酮介导的 葡萄糖-6-磷酸脱氢酶（G6PD）活性的降低。 G6PD，第一个且限制的 戊糖磷酸途径的酶是NADPH的主要来源，降低了当量 和一氧化氮合酶的内皮同工型的辅因子。因此，G6PD调节内皮 氧化还原状态，没有生产。在SCD中，肾功能障碍引起的脱水是一个常见的 现象; （子）急性或慢性脱水激活肾素 - 醛固酮系统和临床 研究表明，SCD患者的肾素和醛固酮水平升高。此外， 醛固酮水平升高已显示出增加细胞内Ca2+储存量，从而增加 可能导致Gardos通道激活，红细胞脱水，并增加对 内皮增加内皮功能障碍。甲醛烷二含与 在没有红细胞粘附的情况下，内皮功能障碍和血管炎症，以及 最近，我们已经表明，醛固酮的醛固酮水平较小，引起了G6PD的获得形式 培养的内皮细胞和体内缺乏，导致G6PD表达和活性降低 为了增加氧化应激，请降低生物利用NO，并损害血管反应性。虽然很早 研究报告说，G6PD缺乏对SCD患者溶血的影响，这些研究 检查了G6PD A-awiant的个体，他们的G6PD活动仅适度降低 （III类），并且没有检查伴随遗传G6PD缺乏对的后果 内皮功能。我们发现，如醛固酮时，获得的G6PD缺乏症 水平温和升高，与G6PD活性降低> 80％有关，类似于V类 缺乏症和G6PD缺乏程度与明显的内皮功能障碍有关。作为 因此，该提案的中心主题是，我们假设与内皮功能障碍相关 通过醛固酮介导的获得的G6PD缺乏症的SCD结果。 为了审查这一假设，我们提出了以下具体目的： 1）表征醛固酮介导的获得的G6PD缺乏的功能后果 体外SCD内皮细胞。 2）确定醛固酮和G6PD活性降低对红细胞 - 内皮细胞的影响 体外SCD中的相互作用。 3）评估醛固酮介导的获得的G6PD缺乏对内皮功能的影响 SCD小鼠模型中的体内血管反应性。