Innate Immune Activation in Malaria

描述（由申请人提供）：疟疾仍然是全世界疾病和死亡的主要原因。间日疟原虫疟疾是南美洲一个特别重要的发病原因。关于间日疟原虫疟疾发病机制的两个主要未解决的问题是：1)寄生虫中的哪些分子激活先天免疫系统并引起炎症；2)这些微生物产物连接的受体是什么。我们的研究表明，toll样受体（TLRs）主要通过髓样分化因子88 （MyD88）适配分子起作用，对疟疾的早期炎症反应和发病机制的启动至关重要。此外，我们有证据表明，人类疟疾患者的nod样受体（NLR）激活，炎性体形成和caspase- 1加工。我们假设在间日疟原虫感染时，吞噬细胞中的先天免疫受体负责由于toll样受体（TLRs）的高反应性和炎症小体的组装而引起的强烈的细胞素血症。然而，尽管我们对恶性疟原虫的研究使我们能够构建一个围绕寄生虫DNA传递到先天免疫传感器的疾病假设模型，但疟疾相关细胞素血症的最基本细节仍未得到很好的理解。我们进一步假设先天免疫反应导致先天免疫系统的启动，先天免疫系统通过核酸的吞噬或免疫复合物的形成触发细胞因子的产生。我们将评估(i)循环寄生虫DNA、抗核酸抗体以及免疫复合物（ic）的水平；（ii）含dna的ic通过吞噬细胞表达的核酸感应先天免疫受体触发细胞因子产生和caspase-1激活的免疫刺激活性；（iii）作为疟疾启动的指示，我们将寻找与TLRs、NLRs和IFN信号通路相关的基因表达以及间日疟原虫感染患者外周血单个核细胞（PBMCs）的反应性。因此，我们希望明确急性恶性疟原虫疟疾期间观察到的ic、促炎启动和炎性小体对全身炎症的贡献。我们希望鉴定疾病的免疫标记，其表达表明对间日疟原虫感染的发病机制至关重要的检查点。这些知识应有助于对疟疾期间炎症的分子基础有新的认识，并有助于改善疟疾患者的临床管理。最后，该项目将与哥伦比亚卡利国际医学研究和培训中心的Carolina Gallego-Marin博士合作完成，目的是发展她作为哥伦比亚独立调查员的职业生涯。这项研究将主要由LMIC合作者进行；最初，50%的工作将在CIDEIM完成，50%在马萨诸塞州完成，Gallego博士在南美的时间将逐渐增加，最终目标是向哥伦比亚的科学界出口尖端技术和专业知识。

DESCRIPTION (provided by applicant): Malaria remains a major cause of illness and death worldwide. Plasmodium vivax malaria is an especially important cause of morbidity in South America. Two major unresolved issues concerning the pathogenesis of P. vivax malaria are: 1) what molecules from the parasite activate the innate immune system and cause inflammation and, 2) what are the receptors that are ligated by these microbial products. Our studies suggest that Toll-like receptors (TLRs), acting primarily through the Myeloid Differentiation Factor 88 (MyD88) adaptor molecule, are critical for initiation of this early inflammatory response and pathogenesis of malaria. In addition, we have evidence of Nod-Like receptor (NLR) activation, inflammasome formation and processing of caspase- 1 in human patients during malaria. We hypothesize that upon P. vivax infection, innate immune receptors in phagocytes are responsible for the intense cytokinemia as a consequence of hyper-responsiveness of Toll-like receptors (TLRs), and the assembly of inflammasomes. However, the most basic details of malaria-related cytokinemia are not well understood, although our studies in P. falciparum allow us to construct a hypothetical model of disease surrounding the delivery of parasite DNA to innate immune sensors. We further hypothesize that the innate immune response results in priming of the innate immune system which triggers the production of cytokines via phagocytosis of nucleic acids of via formation of immune complexes. We will evaluate (i) the levels of circulating parasite DNA, anti-nucleic acid antibodies, as well as immunocomplexes (ICs); (ii) the immunostimulatory activity of DNA-containing ICs on triggering cytokine production and caspase-1 activation via nucleic acid sensing innate immune receptors expressed by phagocytes; and (iii) as indicative of malaria priming, we will look for the expression of genes related to the TLRs, NLRs and IFN signaling pathway as well as the responsiveness of peripheral blood mononuclear cells (PBMCs) from patients infected with P. vivax. Hence, we hope to define the contribution of ICs, pro-inflammatory priming, and inflammasomes on systemic inflammation observed during acute P. falciparum malaria. We hope to identify immunomarkers of disease, whose expression indicates checkpoints that are critical for the pathogenesis of P. vivax infection. Such knowledge should contribute to new insights on the molecular basis of inflammation during malaria and help to improve clinical management of malaria patients. Finally, this project will be done in collaboration with Dr. Carolina Gallego-Marin from CIDEIM (International Centre of Medical Research and Training) in Cali, Colombia, with the purpose of developing her career as an independent investigator in Colombia. The research will be performed primarily by the LMIC collaborator; initially 50% of the work will be done at CIDEIM and 50% in Massachusetts, and gradually the amount of time Dr. Gallego spends in South America will increase, with the ultimate goal of exporting cutting edge technology and expertise to the scientific community in Colombia.