Aberrant RBC SNO transport and endothelial adhesion in sepsis

在重症患者中，贫血是一个公认的不良结局的危险因素，但矛盾的是，自由红细胞 与限制性策略相比，这些患者的输血并不能改善结局， 保持中度贫血在储存过程的早期发生的变化可能会损害 红细胞功能我们已经确定了红细胞储存第一天的功能和生化变化， 有助于血库的促粘附作用。最近，我们发现了一种新的机制， 健康的人RBC输出一氧化氮（NO）衍生物S-亚硝基硫醇（SNO），以对抗内皮细胞 红细胞在体外和小鼠体内的粘附。RBC储存后，RBC SNO输出降低。研究 为了研究这一通路的生理意义，我们设计了一种小鼠， 从内皮细胞中被诱导性地删除。来自该小鼠的EC如预测的那样不好地输入SNO，并且RBC 输血后这些小鼠肺中的粘附增加。在患有脓毒症的小鼠中（对 严重感染），我们发现即使RBC SNO含量升高，RBC SNO输出也减少。我们 假设在脓毒症中，细胞间SNO转运缺乏，促进RBC（天然或 输注）和中性粒细胞。我们将通过实现这些具体目标来检验这一假设： 1.确定脓毒症对抗粘附SNO从RBC输出的影响。我们发现盲肠切除后 在结扎穿孔（CLP）中，鼠RBC输出抗粘附SNO的能力是缺陷的。我们将测试 是否SNO缺乏和促粘附作用在这个脓毒症模型是相关的，如通过测试救援 使用细胞外CSNO（S-亚硝基半胱氨酸）。我们将测试一个RBC群体的SNO输出是否可以 以旁分泌方式影响其他RBC的粘附性。与退伍军人中人类败血症的相关性将是 通过研究患者RBC在基础和缺氧时输出SNO的LAT 1依赖性能力进行测试。 2.确定LAT 1介导的SNO输出对中性粒细胞粘附的影响。中性粒细胞粘附 内皮是对感染的免疫应答中的关键早期事件。抗粘附NO/SNO含量丰富 败血症，并可能限制器官损伤。我们将确定LAT 1和SNO输出在调节 中性粒细胞的粘附性。我们将确定红细胞SNO输出在调节细胞粘附中的作用。 中性粒细胞我们将鉴定介导LAT 1/SNO敏感性的粘附受体和反受体。 中性粒细胞粘附最后，我们将确定LAT 1介导的SNO输出（和EC SNO输入）在 嗜中性粒细胞的粘附性。 3.确定红细胞和中性粒细胞的SNO输出在小鼠粘附和外渗中的作用 CLP诱导的脓毒症模型。我们将测量红细胞和中性粒细胞的粘附，以及 器官损伤，继发于CLP的脓毒症中EC LAT 1有条件缺陷的小鼠。康贝特人将以 自体或异源红细胞输注对脓毒症（CLP后）小鼠SNO输出影响 能力（LAT 1缺失或抑制剂）。鉴于我们证明红细胞储存的促粘附作用 可以减轻红细胞重亚硝基化，我们将研究的影响，红细胞SNO增强小鼠 脓毒症（CLP）诱导的细胞粘附和器官损伤模型。 许多支持疗法和其他疗法在脓毒症中失败，包括因贫血而输红细胞， 在败血症中有临床意义的合并症。我们的创新机制专注于改变细胞间SNO 运输，促进识别以车辆RBC形式实现的可翻译解决方案 输血

In critically ill patients, anemia is a well-established risk factor for poor outcomes but, paradoxically, liberal RBC transfusion in these patients does not improve outcomes as compared with a restrictive strategy in which patients remain moderately anemic. Changes taking place very early in the storage process may contribute by impairing RBC function. We have identified functional and biochemical changes in the first day of RBC storage that contribute to a proadhesive effect of blood banking. Most recently, we identified a novel mechanism whereby healthy human RBCs export the nitric oxide (NO) derivative, S-nitrosothiol (SNO), to oppose endothelial adhesion of RBCs in vitro and in vivo in mice. This RBC SNO export is depressed after RBC storage. To study the physiological significance of this pathway, we engineered a mouse in which the responsible SNO transporter is inducibly deleted from endothelial cells. ECs from this mouse import SNO poorly as predicted, and RBC adhesion is increased in the lungs of these mice after transfusion. In mice with sepsis (injurious response to serious infection), we find that RBC export of SNO is decreased even though RBC SNO content is elevated. We hypothesize that in sepsis, intercellular SNO transport is deficient, promoting the adhesivity of RBCs (native or transfused) and neutrophils. We will test this hypothesis by accomplishing these Specific Aims: 1. Determine the influence of sepsis on antiadhesive SNO export from RBCs. We find that after cecal ligation and puncture (CLP), the ability of murine RBCs to export antiadhesive SNO is deficient. We will test whether the SNO deficiency and proadhesive effect in this sepsis model are related, such as by testing rescue using extracellular CSNO (S-nitrosocysteine). We will test whether SNO export by one RBC population can influence the adhesivity of other RBCs in paracrine fashion. The relevance to human sepsis in Veterans will be tested by studying the LAT1-dependent ability of patient RBCs to export SNO basally and in hypoxia. 2. Determine the influence of LAT1-mediated SNO export on neutrophil adhesion. Neutrophil adhesion to the endothelium is a key early event in immune responses to infection. Antiadhesive NO/SNO is abundant in sepsis and may limit organ damage. We will determine the role of LAT1 and SNO export in modulating the adhesivity of neutrophils. We will determine the role of RBC SNO export in modulating the adhesion of neutrophils. We will identify the adhesion receptors and counterreceptors mediating LAT1/SNO-sensitive neutrophil adhesion. Finally, we will determine the role of LAT1-mediated SNO export (and EC SNO import) in the adhesivity of adoptively transferred neutrophils. 3. Determine the role of SNO export by RBCs and neutrophils in adhesion and extravasation in a mouse model of CLP-induced sepsis. We will measure the adhesion of both RBCs and neutrophils, and indices of organ injury, in sepsis secondary to CLP in our mice conditionally deficient in EC LAT1. We will determine the influence in septic (post-CLP) mice of autologous or heterologous RBC transfusion as a function of SNO export competence (LAT1 deletion or inhibitors). Given our demonstration that the proadhesive effect of RBC storage can be mitigated by RBC renitrosylation, we will investigate the influence of RBC SNO augmentation in a mouse model of sepsis (CLP)-induced cellular adhesion and organ injury. Numerous supportive and other therapies have failed in sepsis, including RBC transfusion for anemia, a clinically significant comorbidity in sepsis. Our innovative mechanistic focus on altered intercellular SNO transport, facilitates the identification of translatable solutions made possible in the form of vehicle RBC transfusates.