The role of nitric oxide synthase 3 in hemorrhagic shock after resuscitation with stored red blood cells

每年，全球约有7500万单位的血液被采集，其中约500万在德国。2009年，美国的输血量约为1500万个单位，输血前的平均储存期为18.2天。输血储存超过14天与多器官衰竭的发生率更高、住院时间延长和死亡率增加有关。我们的假设是，储存的血液在储存过程中和输血后，通过溶血和红细胞破裂释放到血浆中的血红蛋白清除一氧化氮(NO)会在受者身上引发严重的不良反应。这些不良反应包括血管收缩、炎症和血小板激活。在这项资助申请中，我们建议分析输血引起的炎症和血小板活化是否需要内皮细胞产生一氧化氮合成酶NOS3。NO水平降低与内皮功能障碍有关，内皮功能障碍是糖尿病和动脉粥样硬化患者的一种常见的既往疾病。我们将研究降低而不是缺失的血管NO水平是否会使小鼠对储存的红细胞输注的炎症和血小板激活效应敏感。在此基础上，在失血性休克小鼠模型上，我们将验证这样一种假说，即输注储存血通过增加血浆中非清除血红蛋白的水平，增强失血性休克和复苏相关的损伤。此外，这项拟议的研究将促进我们对降低血管NO水平是否足以增加失血性休克小鼠对储存血细胞复苏的敏感性的理解。这两个项目将有助于制定治疗战略，以保护输血接受者，特别是那些患有糖尿病、肥胖症、动脉粥样硬化或慢性饮酒等慢性并存疾病的人，以及接受储存血液输血的人。

Every year, about 75 million units of blood are collected worldwide, about 5 million of them in Germany. In the United States in 2009, about 15 million units of blood were transfused, with a mean duration of storage before transfusion of 18.2 days. Transfusion of blood stored for longer than 14 days is associated with a greater incidence of multiorgan failure, extended hospitalization, and an increased mortality rate. Our hypothesis is that nitric oxide (NO) scavenging by hemoglobin released into the plasma by hemolysis and red cell breakdown during storage and after transfusion of stored blood can trigger severe adverse reactions in the recipient. These adverse reactions include vasoconstriction, inflammation, and platelet activation. In this grant application we propose to analyze if endothelial NO production by the endothelial NO synthase NOS3 is required for the inflammation and platelet activation induced by transfusion of stored blood. Reduced NO levels are associated with endothelial dysfunction, a common pre-existing disorder in patients with diabetes and atherosclerosis. We will investigate whether reduced but not absent vascular NO levels sensitize mice to the inflammatory and platelet-activating effects of stored red blood cell transfusion. Based on this, in a mouse model with hemorrhagic shock, we will test the hypothesis that transfusion of stored blood, by increasing plasma levels of NO-scavenging hemoglobin, enhances the injury associated with hemorrhagic shock and resuscitation.The proposed studies will help to elucidate the physiological and pathophysiological mechanisms responsible for the adverse effects of transfusions with stored blood. In addition, the proposed research will advance our understanding whether reduced vascular NO levels are sufficient to increase the sensitivity of mice with hemorrhagic shock to resuscitation with stored blood cells. Both projects will help to develop therapeutic strategies to protect the transfusion recipients, especially those suffering from chronic comorbidities such as diabetes, obesity, atherosclerosis, or chronic alcohol consumption, and who receive stored blood transfusions.