RBC-derived microparticles function in cerebral malaria

红细胞衍生的微粒在脑型疟疾中的作用

• 批准号: 8582899
• 负责人: Irene Gramaglia
• 金额: $ 9.75万
• 依托单位: LA JOLLA INFECTIOUS DISEASE INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-01 至 2015-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8582899
• 关键词: Address; Adhesions; Affect; Arginine; Biological Availability; Biological Markers; Blood - brain barrier anatomy; Blood Platelets; Budgets; C57BL/6 Mouse; Cell membrane; Cells; Cerebral Malaria; Cerebrum; Cessation of life; Citrulline; Clinical Trials; Complex; Consensus; Data; Development; Disease; Dose; Encapsulated; Environment; Erythrocytes; Exhibits; Flow Cytometry; Functional disorder; Funding; Gases; Grant; Guidelines; Hemoglobin; Hemoglobin concentration result; Human; Image Analysis; Immune response; Impaired cognition; In Vitro; Inbred BALB C Mice; Individual; Infection; Infectious Agent; Injection of therapeutic agent; Institutes; Link; Malaria; Mass Spectrum Analysis; Mediating; Methemoglobin; Modeling; Molecular; Morbidity - disease rate; Mus; Nitric Oxide; Nitric Oxide Donors; Parasites; Pathogenesis; Patients; Phosphatidylserines; Plasmodium; Plasmodium falciparum; Play; Production; Psychotic Disorders; Qualifying; Relative (related person); Reporting; Research; Research Personnel; Research Project Grants; Resistance; Resources; Role; Sampling; Solutions; Spectrometry; Testing; Time; United States National Institutes of Health; Vascular System; Work; cell type; chemotherapy; improved; in vitro Model; in vivo; inhaled nitric oxide; innovation; killings; meetings; mortality; prevent; programs; public health relevance; theories

DESCRIPTION (provided by applicant): Cerebral malaria (CM) pathogenesis is due to a complex interaction between the vascular system, the immune response, and parasite sequestration. We have reported that administration of compounds that restore NO bioavailability (nitric oxide [NO] donor, NO gas, arginine and citrulline) protect all recipients fom experimental CM (ECM); NO gas and arginine are currently undergoing clinical trials as adjunctive therapy for CM. There are, however, no biomarkers to gauge whether the adjunctive therapy is restoring NO bioavailability. We propose that RBC-derived microparticles (RMPs) play a critical role in reducing NO bioavailability during eCM and hence mediating pathogenesis. While free hemoglobin (Hb) is rapidly degraded, Hb contained within RMPs circulates for extended periods of time and has a 1,000-fold greater NO scavenging than intact RBCs. Determining whether RMPs function in eCM pathogenesis represents a defined pilot RO3 research project with significant potential to provide preliminary data for a RO1 proposal. This proposal is significant because it will improve understanding and definition of CM pathogenesis (which is required to develop other adjunctive therapies aimed at protecting CM patients from the host response leading to death, cognitive impairment, and psychoses while the anti-parasite treatment kills Plasmodium falciparum), determine mechanisms of action of an adjunctive therapy undergoing clinical trials, and determine biomarkers for tracking NO bioavailability in malaria patients. Our group played a central role in defining that low NO bioavailability and microparticles are critical for eCM pathogenesis. We now extend our innovative research to link these 2 required mechanisms of pathogenesis. We hypothesize that RMPs play a critical role in the development of ECM by lowering nitric oxide (NO) bioavailability due to NO scavenging by hemoglobin. To address this hypothesis, we use the P. berghei- ANKA (PbA) infection of mice as a model for CM. Our data indicate that (i) low NO bioavailability is critical for eCM pathogenesis, (ii) MPs are critical for the development of eCM, and (iii) RMP numbers are markedly elevated in human CM and eCM. The contribution of RMPs to CM pathogenesis, however, remains to be determined. We therefore propose a limited RO3 project to test this hypothesis. In aim 1, we propose to analyze RMP's and unpackaged Hb's ability to scavenge NO in groups of (i) eCM-susceptible, (ii) eCM- resistant, eCM protected ([iii] inhaled NO and [iv] citrulline) mice infected with PbA and (v) eCM susceptible mice infected with non-eCM inducing P. berghei K173 (PbK). These studies determine the relative importance to low NO bioavailability during eCM of RMPs versus unpackaged Hb. In aim 2, we abrogate the production of ABCA1 in RBCs, which prevents the formation of MPs only in this cell type; comparison of survival of these mice to controls determines the importance of RMPs to eCM pathogenesis. We will also compare the pathogenic consequences of injecting equimolar doses of RMPs, unpackaged oxyHb, metHb, and intact RBCs into groups (i)-(v) of Aim 1 to assess the importance of the states of Hb to eCM pathogenesis. By comparing the results of our studies with eCM-protective NO therapy and vehicle control, we will not only define new mechanisms of action for inhaled NO and citrulline but also elucidate important pathological mechanisms in cerebral dysfunction that are amenable to treatment. These studies are significant because they directly address the pathogenic mechanisms of an important but often overlooked disease that kills millions of people and define the mechanisms of action of a potential therapy to rescue those presenting with cerebral malaria from their disease. Our team, comprising Dr. Gramaglia, Dr. Grau, Dr. Parks, and Dr. Torbett, has the expertise and research environment to perform the proposed studies.

描述（由申请人提供）：脑型疟疾（CM）的发病机制是由于血管系统、免疫反应和寄生虫隔离之间的复杂相互作用。我们已经报道，施用恢复NO生物利用度的化合物（一氧化氮[NO]供体、NO气体、精氨酸和瓜氨酸）保护所有接受者免于实验性CM（ECM）; NO气体和精氨酸目前正在进行CM的连续治疗的临床试验。然而，没有生物标志物来衡量连续治疗是否恢复NO的生物利用度。我们提出，RBC衍生的微粒（RMP）在降低ECM过程中NO的生物利用度并因此介导发病机制中起着关键作用。虽然游离血红蛋白（Hb）迅速降解，但RMP中含有的Hb循环时间延长，并且具有比完整RBC高1，000倍的NO清除能力。确定RMP是否在eCM发病机制中起作用代表了一个确定的试点RO 3研究项目，具有为RO 1提案提供初步数据的重大潜力。这一建议是有意义的，因为它将提高理解和定义CM发病机制（这是开发旨在保护CM患者免受导致死亡、认知障碍和精神病的宿主反应而抗寄生虫治疗杀死恶性疟原虫的其他预防性治疗所需要的），确定正在进行临床试验的预防性治疗的作用机制，并确定用于追踪疟疾患者NO生物利用度的生物标志物。我们的小组在确定低NO生物利用度和微粒对eCM发病机制至关重要方面发挥了核心作用。我们现在将我们的创新研究扩展到将这两种必要的发病机制联系起来。我们假设RMP通过血红蛋白清除NO而降低一氧化氮（NO）的生物利用度，在ECM的发展中发挥关键作用。为了解决这一假设，我们使用伯氏疟原虫- ANKA（PbA）感染小鼠作为CM的模型。我们的数据表明，（i）低NO生物利用度是关键的eCM发病机制，（ii）MP是关键的eCM的发展，和（iii）RMP数量显着升高，在人类CM和eCM。然而，RMP对CM发病机制的贡献仍有待确定。因此，我们提出了一个有限的RO 3项目来测试这一假设。在目的1中，我们建议分析RMP和未包装Hb在以下组中抑制NO的能力：（i）感染PbA的eCM敏感小鼠，（ii）感染PbA的eCM抗性小鼠，受eCM保护的（[iii]吸入NO和[iv]瓜氨酸）小鼠，以及（v）感染非eCM诱导伯氏疟原虫K173（PbK）的eCM敏感小鼠。这些研究确定了RMP与未包装Hb在eCM期间低NO生物利用度的相对重要性。在目标2中，我们废除了红细胞中ABCA 1的产生，其仅在该细胞类型中阻止MP的形成;将这些小鼠的存活率与对照组进行比较，确定了RMP对eCM发病机制的重要性。我们还将比较向目标1的组（i）-（v）中注射等摩尔剂量的RMP、未包装的oxyHb、metHb和完整RBC的致病后果，以评估Hb状态对eCM发病机制的重要性。通过将我们的研究结果与eCM保护性NO治疗和溶剂对照进行比较，我们不仅将确定吸入NO和瓜氨酸的新作用机制，还将阐明适合治疗的脑功能障碍的重要病理机制。这些研究意义重大，因为它们直接解决了一种重要但经常被忽视的疾病的致病机制，这种疾病导致数百万人死亡，并确定了一种潜在疗法的作用机制，以拯救那些患有脑型疟疾的人。我们的团队由Dr. Gramaglia、Dr. Grau、Dr. Parks和Dr. Torbett组成，拥有执行拟议研究的专业知识和研究环境。