Modulation of erythrocyte function by complement

描述(由申请人提供)：补体过度激活与多种病理疾病有关，包括疟疾、镰状细胞疾病、自身免疫性疾病、创伤损伤和败血症。在美国，仅败血症一项每年就导致超过21万人死亡，相关成本估计超过167亿美元。我们目前对脓毒症的理解是补体介导的宿主对感染的免疫反应是微循环障碍和严重器官损害的原因。红细胞(RBC)通过补体受体1(CR1)捕获补体调理颗粒，并将其运送到肝和脾的巨噬细胞，在维持非炎症性血管内环境中具有关键的、非多余的作用。我们发现，在补体过度激活的过程中，可溶性补体片段与血糖素A(GPA)的额外结合显着抑制红细胞膜的变形性，促进红细胞膜ATP的释放。我们的新数据挑战了经典的红细胞作为单一非炎性细胞的范式，揭示了在补体过度激活期间，红细胞不再维持非炎症环境，而积极促进促炎血管内环境。负责将红细胞转化为促炎细胞的机制尚不清楚。更好地了解红细胞“重新编程”为促炎细胞将有助于为败血症患者开发新的、有效的治疗方法。这项工作的长期目标是了解败血症期间红细胞和补体对组织和器官损害的贡献。我们的总体假设是，在过度的补体激活中，过量的补体片段与GPA的结合，通过一个关键的依赖于ATP的自分泌信号机制，将红细胞重新编程为促炎细胞。我们建议的总体目标是确定补体片段与GPA结合促进ATP释放和抑制RBC功能的机制。这些研究的理由是，我们揭示了补体对RBC功能的GPA介导的有害效应的独特和关键的嘌呤能需求，这表明RBC通过自分泌和旁分泌嘌呤能机制产生ATP，促进和维持炎症的血管内环境。我们研究的创新之处在于，我们发现了RBC-补体相互作用的一个新方面，这可能会对靶向治疗方法的有效性和设计产生重大影响，从而显著降低脓毒症的发病率和死亡率。我们的研究将对我们理解红细胞和嘌呤能信号作为与补体过度激活相关的病理情况下治疗的新靶点的潜力，以及我们对正常和病理情况下红细胞生物学的基本理解产生重大影响。

DESCRIPTION (provided by applicant): Excessive complement activation is associated with a wide spectrum of pathologies including malaria, sickle cell disease, autoimmune diseases, trauma injury, and sepsis. In the U.S., sepsis alone is responsible for over 210,000 deaths each year, with associated costs estimated at over $16.7 billion. Our current understanding of sepsis is that complement-mediated host immune responses to infection are responsible for microcirculatory distress and severe organ damage. Red blood cells (RBCs) have critical, non- redundant roles in maintaining a non-inflammatory intravascular environment by capturing complement- opsonized particles through complement receptor 1 (CR1) and delivering them to macrophages in the liver and spleen. We have found that during excessive complement activation the additional engagement of glycophorin A (GPA) by soluble complement fragments significantly inhibits RBC membrane deformability and promotes RBC ATP release. Our new data challenge the classic paradigm of RBCs as singularly non-inflammatory cells, revealing that during excessive complement activation, RBCs cease to maintain a non-inflammatory environment and actively promote a pro-inflammatory intravascular milieu. Mechanisms responsible for changing RBCs into proinflammatory cells have not been known. A better understanding of the "reprogramming" of RBCs into proinflammatory cells will allow the development of novel, effective therapies for septic patients. The long-term objective of this work is to understand the contribution of RBCs and complement to tissue and organ damage during sepsis. Our overall hypothesis is that during excessive complement activation, engagement of GPA by excess complement fragments reprograms RBCs into pro- inflammatory cells through a critical ATP-dependent autocrine signaling mechanism. The overall objective of our proposal is to determine the mechanisms by which engagement of GPA by complement fragments promote ATP release and inhibit RBC functions. The rational for these studies is that we have revealed a unique and crucial purinergic requirement for the GPA-mediated detrimental effect of complement on RBC functions, which suggests that RBC-generated ATP, through autocrine and paracrine purinergic mechanisms, promotes and maintains an inflammatory intravascular milieu. The innovation of our studies is that we have discovered a novel facet of RBC-complement interaction that may considerably impact the efficacy and design of targeted therapeutic approaches that will significantly lower the morbidity and mortality of sepsis. Our studies will have a significant impact on our understanding of the potential of RBCs and purinergic signaling as novel targets for therapy in pathological situation associated with excessive complement activation, as well as on our basic understanding of RBC biology in normal and pathological situations.