Endothelial Cell Uptake of Infected Erythrocytes in Cerebral Malaria

 描述(申请人提供)：由恶性疟原虫引起的疟疾仍然是全球最大的传染病负担之一，每年感染超过2亿人，导致近70万人死亡。在几种可能的疾病表现中，脑型疟疾的生存结果最差。脑型疟疾以昏迷和神经功能障碍为特征，当寄生的红细胞(PRBC)隔离在脑血管系统时，随后会发生脑型疟疾。细胞黏附可通过阻塞外周血管、限制向组织的氧气输送以及引发重大炎症而导致疾病。脑pRBC隔离与血脑屏障的破坏有关，但介导脑型疟疾血管损伤的分子机制尚不清楚。宿主炎症反应起着主要作用，但对隔离相关的病理生理学有更全面的了解对于开发脑型疟疾的辅助治疗是必要的。最近的体外研究表明，人脑内皮细胞(ECs)通过形成一个类似内皮细胞突起的顶端杯状突起来摄取pRBC，该突起介导了白细胞的跨内皮细胞迁移(TEM)。ICAM1结合在透射电子显微镜下激活信号，诱导细胞骨架重塑和连接开放，以允许迁移通过或之间的内皮细胞。由于pRBC也与ICAM1结合，pRBC摄取中描述的杯状结构类似于跨细胞透射电子显微镜，我们假设pRBC细胞黏附可以错误地通过透射电子显微镜途径诱导摄取，这有助于脑型疟疾的病理。我们的目标是：1)探索杯状结构和内皮细胞摄取pRBC之间的关系，研究参与其中的受体，并比较不同的恶性疟原虫临床分离株诱导杯状结构形成的能力；2)确定pRBC诱导的CUPS和摄取如何促进EC屏障的破坏，无论这是通过开放连接的信号通路还是通过诱导细胞死亡来实现的。我们的长期目标是了解pRBC是如何诱导内皮细胞激活和血脑屏障破坏的，以促进治疗开发。不仅在白细胞透射电子显微镜途径的背景下表征内皮pRBC的摄取是一个新的想法，而且探索pRBC摄取对于理解和控制脑疟疾的病理具有重要的意义。

 DESCRIPTION (provided by applicant): Malaria due to Plasmodium falciparum remains one of the largest global infectious disease burdens, infecting over 200 million and killing nearly 700,000 people annually. Of several possible disease manifestations, cerebral malaria has the worst survival outcomes. Cerebral malaria, characterized by coma and neurological deficits, ensues when parasitized red blood cells (pRBCs) sequester in the cerebral vasculature. Cytoadherence can contribute to disease by obstructing peripheral blood vessels, limiting oxygen delivery to tissue, and inducing significant inflammation. Cerebral pRBC sequestration is linked to breakdown of the blood brain barrier, yet the molecular mechanisms mediating vascular damage in cerebral malaria are poorly understood. The host inflammatory response plays a major role, but a more complete understanding of sequestration-related pathophysiology is necessary to develop adjunct therapies for cerebral malaria. Recent in vitro findings demonstrate that human brain endothelial cells (ECs) take up pRBCs via formation of an apical cup resembling endothelial protrusions known to mediate leukocyte transendothelial migration (TEM). ICAM1 binding in TEM activates signaling that induces cytoskeletal remodeling and junction opening to allow for migration either through or between ECs. Since pRBCs also bind ICAM1 and the cup- formation described in pRBC uptake resembles that associated with transcellular TEM, we hypothesize that pRBC cytoadherence can mistakenly induce uptake via TEM pathways and that this contributes to the pathology of cerebral malaria. Our aims seek: 1) to explore the relationship between cup formation and pRBC uptake by ECs, investigating the receptors involved and comparing different clinical isolates of P. falciparum for their ability to induce cup formation; and 2) to determine how pRBC-induced cups and uptake contribute to disruption of the EC barrier, whether this occurs by signaling pathways that open junctions or by inducing cell death. Our long term goal is to understand how pRBCs induce endothelial activation and blood brain barrier breakdown in order to improve therapeutic development. Not only is characterizing endothelial pRBC uptake in the context of leukocyte TEM pathways a novel idea, but exploring pRBC uptake has significant implications for understanding and controlling cerebral malaria pathology.