Metabolic and purinergic immune regulation

项目摘要/摘要： 败血症是导致死亡的主要原因，每年全球有500多万人死于败血症。脓毒症涉及 免疫功能障碍，其特征是过度炎症，导致多器官功能障碍 综合征(MODS)。同时，免疫抑制和T细胞功能障碍会损害宿主免疫。 防御，导致细菌感染的不受阻碍的传播。尽管在这方面做了大量的研究工作 过去所有改善败血症预后的尝试都失败了，也没有有效的治疗方法可用。 这些令人失望的结果清楚地表明，需要更好地了解潜在的 导致脓毒症免疫功能障碍的机制。 这个实验室的重点是确定引起免疫的分子和细胞机制。 创伤、重症监护和脓毒症患者的功能障碍。我们的长期目标是发现新的药理作用 预防过度炎症和免疫抑制的策略导致发病率和 脓毒症的死亡率。我们发现了调节中性粒细胞和T细胞的新信号机制 代表了恢复脓毒症患者免疫动态平衡的有希望的治疗靶点。这些小说 信号机制通过细胞内ATP的释放和自分泌反馈来调节细胞功能 与钙信号和线粒体协同作用的兴奋性和抑制性嘌呤能受体 新陈代谢，微调宿主防御所需的免疫细胞反应。我们发现亚细胞 线粒体和嘌呤能受体的定位和不同激活对于 中性粒细胞和T细胞功能。干扰这些信号过程会损害这些细胞的能力 检测和消除入侵的病原体。我们发现，这些新的细胞信号通路在 脓毒症患者，因为这些患者的循环中积累了过多的系统性三磷酸腺苷 干扰调节免疫细胞功能的自分泌嘌呤能信号机制。此外, 我们发现，脓毒症损害了线粒体，线粒体为这些嘌呤能信号机制提供了ATP。 在拟议的MIRA项目中，我们计划继续我们的研究，以定义分子和细胞 导致脓毒症免疫功能障碍的机制。NAD是一种核苷酸，其功能是作为辅酶 许多新陈代谢过程。我们将研究脓毒症患者NAD水平下降是否以及如何导致败血症 脓毒症患者的线粒体功能障碍、免疫缺陷和不良预后。我们将研究是否增加了 CD38在脓毒症中的表达与NAD消耗量增加以及NAD消耗量是否有关 剥夺sirtuins防止线粒体损伤和防止免疫细胞所需的辅酶 功能障碍。此外，我们还将研究嘌呤能信号如何参与激活和运输 T细胞和中性粒细胞内的线粒体以及这些调节机制在脓毒症中是如何受损的。 最后，我们将探索CD38、NAD和sirtuins如何通过药物干预在 以恢复脓毒症患者的线粒体功能、嘌呤能信号和免疫稳态。 拟议的工作是创新的，可能是范式转换，因为它关注的是 线粒体是免疫细胞的中枢调节器，线粒体功能障碍是潜在的 败血症时免疫功能受损的问题。我们建议以创新的方式利用这一知识 补充线粒体健康和嘌呤能信号从而恢复免疫功能的治疗 从细胞内。这种方法优于以往旨在拦截刺激性免疫的策略。 细胞信号失败是因为这些策略进一步扰乱了免疫动态平衡和 寄主抗击感染。

Project Summary/Abstract: Sepsis is a leading cause of death that kills more than 5 million people annually word-wide. Sepsis involves immune dysfunction that is characterized by excessive inflammation that causes multiple organ dysfunction syndrome (MODS). At the same time, immunosuppression and T cell dysfunction impair host immune defenses, resulting in the unimpeded spread of bacterial infections. Despite intense research efforts in the field, all previous attempts to improve outcome in sepsis have failed and no effective treatments are available. These disappointing results clearly demonstrate the need for a better understanding of the underlying mechanisms that cause immune dysfunction in sepsis. The focus of this laboratory has been to determine the molecular and cellular mechanisms that cause immune dysfunction in trauma, critical care, and sepsis patients. Our long-term goal is to identify novel pharmacological strategies that can prevent excessive inflammation and the immunosuppression responsible for morbidity and mortality in sepsis. We discovered novel signaling mechanisms that regulate neutrophils and T cells and that represent promising therapeutic targets to restore immune homeostasis in sepsis patients. These novel signaling mechanisms regulate cell functions by cellular ATP release and by autocrine feedback through excitatory and inhibitory purinergic receptors that act in synergy with Ca2+ signaling and mitochondrial metabolism to fine-tune the immune cell responses needed for host defense. We found that the subcellular localization and differential activation of mitochondria and purinergic receptors are essential for proper neutrophil and T cell functions. Interfering with these signaling processes impairs the ability of these cells to detect and eliminate invading pathogens. We found that these novel cell signaling pathways are impaired in sepsis patients because excessive systemic ATP that accumulates in the circulation of these patients interferes with the autocrine purinergic signaling mechanisms that regulate immune cell functions. In addition, we found that sepsis impairs the mitochondria that provide the ATP for these purinergic signaling mechanisms. In the proposed MIRA project, we plan to continue our studies in order to define the molecular and cellular mechanisms that lead to immune dysfunction in sepsis. NAD is a nucleotide that functions as a coenzyme for many metabolic processes. We will examine whether and how declining NAD levels in sepsis contribute to mitochondrial dysfunction, immune defects, and poor outcome in sepsis. We will study whether increased expression of CD38 in sepsis is responsible for increased NAD consumption and whether NAD consumption deprives sirtuins of the coenzyme they need to prevent mitochondrial damage and prevent immune cell dysfunction. In addition, we will study how purinergic signaling contributes to the activation and trafficking of mitochondria within T cells and neutrophils and how these regulatory mechanisms are impaired in sepsis. Finally, we will explore how CD38, NAD, and sirtuins can be targeted with pharmacological interventions in order to restore mitochondrial function, purinergic signaling, and immune homeostasis in sepsis patients. The proposed work is innovative and possibly paradigm shifting because it focuses on the novel concept that mitochondria are central regulators of immune cells and that mitochondrial dysfunction is the underlying problem that impairs immune function in sepsis. We propose to exploit this knowledge with innovative treatments that replenish mitochondrial health and purinergic signaling and thereby restore immune function from within the cell. This approach is superior to previous strategies aimed at intercepting stimulatory immune cell signals that failed because these strategies further disrupted immune homeostasis and the ability of the host to fight infections.