Modulation of erythrocyte function by complement

描述（由申请人提供）：过度的补体激活与广泛的病理相关，包括疟疾、镰状细胞病、自身免疫性疾病、创伤损伤和败血症。在美国，仅败血症每年就导致超过21万人死亡，相关费用估计超过167亿美元。我们目前对败血症的理解是补体介导的宿主对感染的免疫反应是微循环窘迫和严重器官损伤的原因。红细胞（rbc）通过补体受体1 （CR1）捕获补体调理颗粒并将其传递给肝脏和脾脏的巨噬细胞，在维持非炎症性血管内环境中起着关键的、非冗余的作用。我们发现，在过量的补体激活过程中，可溶性补体片段对糖蛋白A （GPA）的额外参与显著抑制了红细胞膜的变形能力，并促进了红细胞ATP的释放。我们的新数据挑战了红细胞作为单一非炎症细胞的经典范式，揭示了在过度补体激活期间，红细胞停止维持非炎症环境，并积极促进促炎血管内环境。将红细胞转变为促炎细胞的机制尚不清楚。更好地理解红细胞“重编程”为促炎细胞将有助于开发新的、有效的治疗败血症患者的方法。这项工作的长期目标是了解红细胞和补体在败血症期间对组织和器官损伤的贡献。我们的总体假设是，在过度的补体激活过程中，过量补体片段对GPA的参与通过关键的atp依赖性自分泌信号机制将红细胞重编程为促炎细胞。我们建议的总体目标是确定补体片段参与GPA促进ATP释放和抑制RBC功能的机制。这些研究的理由是，我们已经揭示了gpa介导的补体对红细胞功能有害影响的独特而关键的嘌呤能需求，这表明红细胞产生的ATP，通过自分泌和旁分泌嘌呤能机制，促进和维持炎症血管内环境。我们研究的创新之处在于，我们发现了红细胞-补体相互作用的一个新方面，这可能会极大地影响靶向治疗方法的疗效和设计，从而显著降低败血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.