Hemolytic Complications in Babesia Infections

摘要： SCD表现出对感染的易感性增加，进而导致SCD特有的病理生理后遗症。 感染是这些患者的主要死亡原因，特别是在血液供应不发达的欠发达国家 有效的筛选。即使在美国，输血传播的病原体也可能是发病和死亡的主要威胁。 SCD受者的死亡率。肠道病毒是由病原体和宿主细胞对感染作出反应而产生的，并携带 使受感染宿主中的效应器分子异化的载体。溶血和贫血是两种常见的症状 伴随着许多传染病。虽然针对红细胞的寄生虫病尤其如此，如疟疾和 巴贝斯虫，这些并发症也见于许多其他感染。虽然目前的提案重点是巴贝西亚，但单一的 病原体，我们认为病原体来源的EV对宿主细胞的影响是许多疾病发病机制中的共同主题 感染性疾病和这项研究的结果可能对其他传染病引起的溶血性并发症有影响 探员们。SCD的溶血并发症是导致这些输血中死亡的主要病理因素。 因此，必须阐明在这些感染患者中出现较高程度溶血的原因。 来自寄生细胞的EV可以改变细胞膜，影响基因表达，并调节信号通路，从而 促进溶血。我们的总体目标是确定在感染过程中细胞外小泡驱动的溶血机制。 SCD，使用巴贝西亚作为我们的模型。假设：巴贝斯虫贫血在SCD中被夸大，因为EVS加速了 旁观者红细胞破坏和b)由于SCD的易感性增加到1)而加剧无效的红细胞生成 EV介导的旁观者红细胞的改变和补体调理导致直接/间接免疫 EV激活导致吞噬功能增强和诱导自身抗体3)EV介导的去核抑制 红系祖细胞在SCD骨髓造血中的作用。要深入了解这些分子和细胞过程，请使用 体内和体外SCD感染模型，我们将：1)阐明EV摄取介导直接溶血的机制 通过检测EV介导的SCD红细胞膜上导致溶血的改变2)阐明EV的作用机制 巨噬细胞极化和TLR信号通路激活对血管外溶血的调节作用 评价EVS诱导自身抗体的作用和机制及自身抗体的贡献 旁观者红细胞清除中的调理和/或补体结合3)阐明EV摄取的机制 通过定义EV诱导和感染的潜在分子机制来促进红细胞生成障碍- SCD骨髓红系祖细胞诱导的去核缺陷。我们提议的研究将产生更好的 了解肠道寄生虫在人类巴贝斯虫病发病机制中的作用 镰状细胞背景下可见的溶血。我们预计这些研究将导致诊断工具的改进，并提供 防治人类巴贝斯虫病贫血的新策略。

ABSTRACT: SCD exhibits increased susceptibility to infection which in turn leads to SCD-specific pathophysiological sequelae. Infection is the leading cause of death in these patients especially in less developed countries where the blood supply is not efficiently screened. Even in the US, transfusion transmitted pathogens can represent a major threat of morbidity and mortality to SCD recipients. EVs are produced by pathogens and host cells in response to infection and carry serve as vehicles for dissimilation of effector molecules in the infected host. Hemolysis and anemia are two common symptoms that accompany many infectious diseases. While particularly true of parasitic diseases that target red cells, like malaria and babesia, these complications are also seen in many other infections. While the current proposal focuses on babesia, a single pathogen, we believe that the impact of pathogen derived EVs on host cells is a common theme in the pathogenesis of many infectious diseases and results from this study can have implications for hemolytic complications caused by other infectious agents. Hemolytic complications in SCD are the major contributing pathology to fatalities seen in these transfusion transmissions, making it imperative to elucidate the reason for the higher degree of hemolysis seen in these infected patients. EVs derived from parasitized cells can alter cell membranes, impact gene expression and modulate signaling pathways to promote hemolysis. Our overall goal is to define mechanisms of extracellular vesicle driven hemolysis during infection in SCD, using Babesia as our model. Hypothesis: Babesia anemia is exaggerated in SCD because EVs accelerate a) bystander RBC destruction and b) exacerbate ineffective erythropoiesis due to the increased susceptibility of SCD to 1) EV-mediated alterations and complement opsonization of bystander RBCs resulting in direct /indirect lysis 2) immune activation by EVs resulting in increased phagocytosis and induction of autoAbs 3) EV mediated inhibition of enucleation of erythroid progenitors in SCD BM erythropoiesis. To gain insight into these molecular and cellular processes, using in vivo and in vitro SCD infection models, we will: 1) Elucidate mechanisms by which EV Uptake mediates direct hemolysis by examining EV mediated alterations in membranes of SCD RBCs that cause hemolysis 2) Elucidate mechanisms of EV modulation of extravascular hemolysis by examining macrophage polarization and TLR signaling pathway activation, assessing the role and mechanism of autoAb induction by EVs and determining the contribution of autoantibody opsonization and/or complement fixation in bystander RBC clearance 3) Elucidate mechanisms by which EV Uptake contributes to dyserythropoiesis by defining the underlying molecular mechanisms for both EV-induced and infection- induced enucleation defects in erythroid progenitor cells in SCD bone marrow. Our proposed studies will result in a better understanding of the role of parasite EVs in the pathogenesis associated with human babesiosis especially the hyper- hemolysis seen in the sickle cell context. We anticipate these studies will lead to the refinement of diagnostic tools and offer novel strategies to combat anemia in human babesiosis.