Harmful effects of transfusion of older stored red cells: iron and inflammation

描述（由申请人提供）： 流行病学研究表明，输注储存时间较长的血液与死亡率、严重感染、多器官衰竭和住院时间的增加有关。我们的研究是基于一个总体假设，即输血储存的血液的不良反应是由于急性运送血红蛋白铁到单核细胞-巨噬细胞系统。根据目前的FDA标准，如果多达25%的红细胞在24小时内被清除，则储存的红细胞（RBC）单位在临床上可接受用于输血，从而向单核细胞-巨噬细胞系统递送大量剂量的铁。我们假设，急性暴露于这些大量血红蛋白铁所产生的促氧化作用诱导促炎细胞因子反应，这可能导致在人体研究中观察到的严重后果。我们使用充分表征的小鼠模型进行的临床前研究表明，输注储存较久的RBC可将血红蛋白铁急性递送至脾、肾和肝，诱导强烈的促炎细胞因子应答，并与内毒素（标准脓毒症模型）的作用协同作用，以增强和延长细胞因子风暴。因此，当前提案的主要目标是确定这些新的临床前观察结果在人体中的相关性。 为此，我们建议对健康志愿者和血红蛋白病患者进行仔细对照的前瞻性研究。我们将首先研究健康个体，以避免先前对危重病或手术患者进行的研究中存在的混杂因素，这些研究检查了输注较旧储存的RBC是否会产生不良反应。然后，我们将通过研究定期接受简单输血的镰状细胞病或β地中海贫血稳定患者，将这些发现扩展到两种相关的人类疾病环境。由于这些患者接受慢性铁螯合治疗，可以安全地在短时间内停止治疗，这将使我们能够评估我们的新假设，即急性铁输送的作用。目的#1将检验将储存较久的RBC输注至健康人类志愿者体内诱导急性促炎细胞因子反应的假设。目的#2将检验以下假设：在患有镰状细胞病或2-地中海贫血的慢性输血患者中，输注较旧储存的RBC会诱导急性促炎反应。此外，我们将确定在这种情况下经常使用的其他标准RBC产品（即洗涤RBC和冻存RBC）是否会引起类似的影响。最后，目标#3将检验以下假设：用铁螯合剂治疗镰状细胞病和2-地中海贫血患者将预防由使用较旧储存的RBC的透析诱导的急性促炎反应。从完成本提案中获得的见解将对当前的输血医学实践产生直接影响，并将为开发合理设计的方法以提高人类供体RBC和人类输血治疗的质量提供基础。 公共卫生相关性： 该项目的最终目标是确定标准的、FDA批准的、单位的旧储存血液的输血是否在健康人类志愿者和患有两种重要和常见血液学疾病中的任一种的患者中诱导急性炎症状态：镰状细胞病和β地中海贫血。从完成本提案中获得的见解将对当前的输血实践产生直接影响，并将为开发合理设计的方法以提高人类供体血液和人类输血治疗的质量提供基础。

DESCRIPTION (provided by applicant): Epidemiological studies show that the transfusion of older stored blood is associated with increases in mortality, serious infections, multi-organ failure, and hospital length of stay. Our research is based on the overarching hypothesis that the adverse effects of the transfusion of stored blood result from the acute delivery of hemoglobin iron to the monocyte-macrophage system. By current FDA standards, a unit of stored red blood cells (RBC) is clinically acceptable for transfusion if as much as 25% of the RBC is cleared within 24 hours, thereby delivering a substantial dose of iron to the monocyte-macrophage system. We hypothesize that the pro-oxidant effects exerted by acute exposure to these massive amounts of hemoglobin iron induce a pro- inflammatory cytokine response that may lead to the serious consequences seen in human studies. Our pre- clinical studies using a well-characterized mouse model demonstrate that the transfusion of older stored RBC acutely delivers hemoglobin iron to the spleen, kidney, and liver, induces an intense pro-inflammatory cytokine response, and synergizes with the effects of endotoxin (a standard sepsis model) to enhance and prolong cytokine storm. Therefore, the main goal of the current proposal is to establish the relevance of these novel pre-clinical observations in humans. To this end, we propose carefully-controlled, prospective studies of healthy volunteers and patients with hemoglobinopathies. We will first study healthy individuals to avoid the confounding factors present in prior studies of critically-ill or surgical patients that examined whether transfusions of older stored RBC produce adverse effects. We will then extend these findings to two relevant human disease settings, by studying stable patients with either sickle cell disease or beta-thalassemia who regularly receive simple transfusions. Because these patients are treated with chronic iron-chelating therapy, which can be safely discontinued for short periods of time, this will allow us to evaluate our novel hypothesis implicating the role of acute iron delivery. Aim #1 will test the hypothesis that transfusion of older stored RBC into healthy human volunteers induces an acute pro-inflammatory cytokine response. Aim #2 will test the hypothesis that transfusion of older stored RBC induces an acute pro-inflammatory response in chronically transfused patients with either sickle cell disease or 2-thalassemia. In addition, we will determine whether other standard RBC products often used in this setting (i.e. washed RBC and cryopreserved RBC) induce similar effects. Finally, Aim #3 will test the hypothesis that treating sickle cell disease and 2-thalassemia patients with iron chelators will prevent the acute pro- inflammatory response induced by transfusing older stored RBC. The insights gained from completing this proposal will have an immediate impact on the current practice of transfusion medicine and will provide the foundation for developing rationally-designed approaches to improve the quality of human donor RBC and of human transfusion therapy. PUBLIC HEALTH RELEVANCE: The ultimate goal of this project is to determine whether transfusions of standard, FDA-approved, units of older stored blood induce an acute inflammatory state in healthy human volunteers and in patients with either of two important and common hematological disorders: sickle cell disease and beta-thalassemia. The insights gained from completing this proposal will have an immediate impact on the current practice of blood transfusion and will provide the foundation for developing rationally-designed approaches to improve the quality of human donor blood and of human transfusion therapy.