SNO transport regulates endothelial adhesion of RBCs

项目摘要 红细胞（RBC）输注是昂贵的，并且是VA中最常进行的程序之一， 其他卫生保健设施。然而，越来越多的证据表明，许多贫血患者可能不会受益 红细胞输注后，即使在短期储存期间，血液功能也会下降。我们已经确定了一 红细胞通常将一氧化氮（NO）衍生信号输出到脉管系统的新机制， 促进血液本身的流动。S-亚硝基硫醇（SNO）是由前体NO在RBC中形成的硫醇加合物 与血红蛋白中氧合相关的变构转变一致。红细胞输出这些血管调节 “按需”使用SNO，以微调局部血流并防止RBC粘附于内皮 （EC）。初步研究首次表明，小载体SNOs的细胞间转运在 防止RBC粘附于EC。这些新的发现证明了血流调节的作用， RBC的细胞间SNO信号传导，以及储存后该功能的受损。我们将测试 假设SNO转运对红细胞的血管调节功能至关重要，其损失是可补救的 通过实现这些具体目的，“储留性病变”促进输血后肺部发病率：目的1： 确定RBC LAT 1在介导人RBC的SNO输出中的作用。一种特殊的管道， RBC输出SNO组尚未确定，但我们的初步研究表明RBC的重要作用 SNO导出中的LAT 1。我们将使用新的工具和药理学方法来确定LAT 1的作用， RBC SNO出口，以及扩大这一活动的措施。我们还将鉴定细胞内红细胞分子 有益的SNO恢复的目标。目的2：确定SNO通过LAT 1输入在内皮细胞中的作用。 细胞限制健康人红细胞的粘附性。我们证明了SNO可以在银行中恢复 红细胞后储存诱导的损失，和SNO恢复限制红细胞-EC粘附。我们将确定 LAT 1介导的内皮细胞的SNO输入是否是RBC SNO诱导的抗粘附作用所必需的， 使用遗传和药理学方法，并测试替代机制的作用。目标3： 确定LAT 1在人红细胞SNO小鼠模型中的储存敏感性效应中的作用 红细胞输血。我们开发了一种创新的人类红细胞输注小鼠模型， 临床表型如肺功能障碍。我们将使用活体显微镜，一种新的小鼠条件 缺乏EC LAT 1，以及输血液标记，以确定RBC SNO在限制输血后的作用 发病率，特别是红细胞粘附和降低血氧和组织O2输送。既天真， 将使用二次打击（在脂多糖之后输血）、急性和慢性模型。确定的作用 SNO在健康和疾病中从RBC到EC的信号传导中的转运是我们长期研究的下一个合乎逻辑的步骤。 长期科学目标：了解红细胞输出介体以调节其自身的机制 以满足组织的需要。预计这些研究将为输血实践的变化提供信息， 改善退伍军人患者的风险-收益平衡。

PROJECT SUMMARY Red blood cell (RBC) transfusion is costly, and is among the procedures most frequently performed in VA and other health care settings. Growing evidence, however, suggests that many anemic patients may not benefit from RBC transfusion, and that blood function declines even during short storage periods. We have identified a novel mechanism whereby RBCs normally export nitric oxide (NO)-derived signals to the vasculature, facilitating the flow of blood itself. S-nitrosothiols (SNOs) are thiol adducts formed in RBCs from precursor NO in concert with the oxygenation-linked allosteric transition in hemoglobin. RBCs export these vasoregulatory SNOs “on demand” in order to fine-tune regional blood flow and prevent RBC adhesion to the endothelium (ECs). Preliminary Studies show for the first time that intercellular transport of small carrier SNOs is critical in the prevention of RBC adhesion to ECs. These novel findings demonstrate the role of blood flow-regulating, intercellular SNO signaling by the RBC, and impairment in this function after storage. We will test the hypothesis that SNO transport is critical to the vasoregulatory function of RBCs, and its loss a remediable “storage lesion” promoting post-transfusion lung morbidity, by accomplishing these Specific Aims: Aim 1: Determine the role of RBC LAT1 in mediating SNO export by human RBCs. The specific conduit by which RBCs export SNO groups remains undetermined, but our Preliminary Studies indicate a significant role of RBC LAT1 in SNO export. We will use new tools and pharmacological approaches to determine the role of LAT1 in RBC SNO export, and measures to augment this activity. We will also identify intracellular RBC molecular targets of beneficial SNO restoration. Aim 2: Determine the role of SNO import via LAT1 in endothelial cells in limiting the adhesivity of healthy human RBCs. We showed that SNO can be restored in banked RBCs after storage-induced loss, and that SNO restoration limits RBC-EC adhesion. We will determine whether LAT1-mediated SNO import by ECs is necessary for the RBC SNO-induced antiadhesive effect by using genetic and pharmacological approaches, and test the role of alternative mechanisms. Aim 3: Determine the role of LAT1 in the storage-sensitive effects of RBC SNOs in mouse models of human RBC transfusion. We developed an innovative mouse model of human-RBC transfusion, recapitulating key clinical phenotypes such as lung dysfunction. We will use intravital microscopy, a novel mouse conditionally deficient in EC LAT1, and transfusate labeling to determine the role of RBC SNO in limiting post-transfusion morbidity, specifically RBC adhesion and depressed blood oxygenation and tissue O2 delivery. Both naïve and two-hit (transfusion after lipopolysaccharide), acute and chronic models will be used. Determining the role of SNO transport in signaling from RBCs to ECs in health and disease is the next logical step toward our long- term scientific objective: to understand the mechanisms whereby RBCs export mediators to regulate their own flow in response to tissue needs. These studies are expected to inform changes in transfusion practice to improve the risk-benefit balance for Veteran patients.