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，输注较老储存的血液与死亡率、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最重要的假设，即输血的不良影响是由于血红蛋白铁急性输送到单核细胞-巨噬细胞系统造成的。根据FDA目前的标准，如果在24小时内清除多达25%的红细胞，从而向单核-巨噬细胞系统提供大量的铁，则临床上可以接受输血单位储存的红细胞。我们假设，急性暴露于这些大量的血红蛋白铁所产生的促氧化作用会诱导促炎细胞因子反应，这可能会导致人类研究中看到的严重后果。我们的临床前研究使用了一个具有良好特征的小鼠模型，表明输注较老的储存的RBC可以迅速地将血红蛋白铁输送到脾、肾和肝脏，诱导强烈的促炎细胞因子反应，并与内毒素(一种标准的脓毒症模型)的效果协同作用，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与人类的相关性。 为此，我们建议对健康志愿者和血红蛋白疾病患者进行仔细对照的前瞻性研究。我们将首先研究健康的个体，以避免在先前对危重病人或外科病人的研究中出现的混杂因素，这些研究检查输注较旧储存的红细胞是否会产生不良影响。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-地中海贫血的稳定患者，将这些发现扩展到两种相关的人类疾病背景。由于这些患者接受了慢性铁螯合疗法的治疗，这种疗法可以安全地在短时间内停止，这将使我们能够评估我们关于急性铁输送的作用的新假说。目的#1将验证这样的假设：将较老的储存红细胞输注到健康志愿者体内会诱导急性促炎细胞因子反应。目的#2将验证这样的假设，即输注较老储存的红细胞会在长期输血的镰状细胞病或2-地中海贫血患者中诱导急性促炎反应。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和冷冻保存RBC)是否会产生类似的效果。最后，目标3将验证这样一个假设，即用铁络合剂治疗镰状细胞病和2-地中海贫血患者将防止输注较旧储存的红细胞引起的急性促炎反应。完成这项提议所获得的见解将对目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红细胞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输注FDA批准的标准储存血液单位是否会在健康志愿者和患有两种重要和常见的血液疾病：镰状细胞疾病和β-地中海贫血的患者中诱导急性炎症状态。完成这项提议所获得的见解将对目前的输血做法产生直接影响，并将为制定合理设计的方法以提高人类献血和人类输血治疗的质量奠定基础。

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.