Malaria Pathogenesis in young children and vaccine discovery

幼儿疟疾发病机制和疫苗发现

• 批准号: 10272178
• 负责人: Patrick Duffy
• 金额: $ 54.52万
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10272178
• 关键词: Adhesions; Adolescent; Adult; African; Alanine; Anemia; Animal Model; Animals; Antibodies; Antigen-Antibody Complex; Antigenic Variation; Antigens; Apoptosis; Binding; Blood; Burn injury; CXCR4 Receptors; Cells; Cerebral Malaria; Child; Clinical Trials; Comparative Study; Complement; Complication; Consumption; Deoxyribonucleases; Disease; Drops; Endothelium; Epitopes; Erythrocytes; Erythropoiesis; Future; Glutamic Acid; Haptoglobins; Hemolysis; Hepatocyte; Human; Immune response; Immunity; Immunology; Individual; Infection; Inflammatory; Inflammatory Response; Integration Host Factors; Life; Longitudinal cohort study; Macaca; Macaca fascicularis; Macaca mulatta; Malaria; Malaria Vaccines; Mediating; Methods; Microbe; Migration Inhibitory Factor; Modeling; Mus; Nature; Outcome; Parasitemia; Parasites; Parasitology; Pathogenesis; Patients; Pediatric cohort; Plasma; Plasmodium; Plasmodium falciparum; Predisposition; Pregnancy; Primates; Problem Solving; Production; Proteins; Proteome; Publications; Raja; Reporting; Resistance; Reticulocytes; Rhesus; Risk; Role; Structure; Surface; Surface Antigens; Tissues; Vaccinated; Vaccines; circulating DNA; comparative; density; design; experience; extracellular; genetic regulatory protein; high risk; improved; malaria infection; malarial anemia; mortality; neutrophil; nonhuman primate; offspring; parasite invasion; pathogen; release factor; screening; trend; vaccine discovery

In FY20, we reported human and animal studies to investigate malaria immunology and pathogenesis. Highlighted in this years summary are results from our publications. 1. Rodrigues DSA, Prestes EB, Silva LDS, Pinheiro AAS, Francischetti I, Saraiva E, Neto HAP, Bozza MT. 'CXCR4 and MIF are required for neutrophil extracellular trap release triggered by Plasmodium-infected erythrocytes in press with PLoS Pathogens. In press. Neutrophil extracellular trap (NET) evolved as an unique effector mechanism contributing to resistance against infection, that can also promote tissue damage in inflammatory conditions. Malaria infection can trigger NET release, but the mechanisms and consequences of NET formation in this context remain poorly characterized. Here we show that Plasmodium-infected erythrocytes cause the formation of NET by neutrophils from healthy donors in a mechanism dependent on the C-X-C chemokine receptor type 4 (CXCR4), activated by macrophage migration inhibitory Factor (MIF) release by infected erythrocytes. Patients suffering from cerebral malaria had increased amounts of circulating DNA, paralleled by increased NE activity in plasma. Importantly, mice infected P. berghei ANKA, a model of cerebral malaria, also had high amounts of circulating DNA, while treatment with DNAse increased parasitemia and accelerated mortality, indicating a role for NET in resistance against Plasmodium infection. 2. Raj DK, Mohapatra AD, Jnawali A, Zuromski J, Jha A, Cham-Kpu G, Sherman B, Rudlaff RM, Nixon CE, Hilton N, Oleinikov AV, Chesnokov O, Merritt J, Pond-Tor S, Burns L, Jolly G, Mamoun CB, Kabyemala E, Muehlenbachs A, Lambert L, Orr-Gonzalez S, Gndig NF, Fidock DA, Park S, Dvorin JD, Pardi N, Weissman D, Mui BL, Tam YK, Friedman JF, Fried M, Duffy PE, Kurtis JD. Anti-PfGARP activates programmed cell death of parasites and reduces severe malaria. Nature. 2020 Jun;582(7810):104-108. doi: 10.1038/s41586-020-2220-1. Epub 2020 Apr 22. Malaria caused by Plasmodium falciparum remains the leading single-agent cause of mortality in children, yet the promise of an effective vaccine has not been fulfilled. Here, using our previously described differential screening method to analyse the proteome of blood-stage P. falciparum parasites, we identify P. falciparum glutamic-acid-rich protein (PfGARP) as a parasite antigen that is recognized by antibodies in the plasma of children who are relatively resistant-but not those who are susceptible-to malaria caused by P. falciparum. PfGARP is a parasite antigen of 80 kDa that is expressed on the exofacial surface of erythrocytes infected by early-to-late-trophozoite-stage parasites. We demonstrate that antibodies against PfGARP kill trophozoite-infected erythrocytes in culture by inducing programmed cell death in the parasites, and that vaccinating non-human primates with PfGARP partially protects against a challenge with P. falciparum. Furthermore, our longitudinal cohort studies showed that, compared to individuals who had naturally occurring anti-PfGARP antibodies, Tanzanian children without anti-PfGARP antibodies had a 2.5-fold-higher risk of severe malaria and Kenyan adolescents and adults without these antibodies had a twofold-higher parasite density. By killing trophozoite-infected erythrocytes, PfGARP could synergize with other vaccines that target parasite invasion of hepatocytes or the invasion of and egress from erythrocytes. 3. Raja AI, Brickley EB, Taaffe J, Ton T, Zhao Z, Bock KW, Orr-Gonzalez S, Thomas ML, Lambert LE, Moore IN, Duffy PE. A primate model of severe malarial anemia: a comparative pathogenesis study. Scientific Reports. 2019 Dec 12;9(1):18965. doi: 10.1038/s41598-019-55377-3. Severe malarial anaemia (SMA) is the most common life-threatening complication of Plasmodium falciparum infection in African children. SMA is characterised by haemolysis and inadequate erythropoiesis, and is associated with dysregulated inflammatory responses and reduced complement regulatory protein levels (including CD35). However, a deeper mechanistic understanding of the pathogenesis requires improved animal models. In this comparative study of two closely related macaque species, we interrogated potential causal factors for their differential and temporal relationships to onset of SMA. We found that rhesus macaques inoculated with blood-stage Plasmodium coatneyi developed SMA within 2 weeks, with no other severe outcomes, whereas infected cynomolgus macaques experienced only mild/ moderate anaemia. The abrupt drop in haematocrit in rhesus was accompanied by consumption of haptoglobin (haemolysis) and poor reticulocyte production. Rhesus developed a greater inflammatory response than cynomolgus macaques, and had lower baseline levels of CD35 on red blood cells (RBCs) leading to a significant reduction in the proportion of CD35+ RBCs during infection. Overall, severe anaemia in rhesus macaques infected with P. coatneyi has similar features to SMA in children. Our comparisons are consistent with an association of low baseline CD35 levels on RBCs and of early inflammatory responses with the pathogenesis of SMA. 4. Duffy PE. Immunity to Severe Malaria: PfEMP1 tags tell a tale. Cell Host & Microbe. 2019 Nov 13;26(5):571-573. doi: 10.1016/j.chom.2019.10.021. PfEMP1 is the major surface antigen of P. falciparum-infected erythrocytes, mediates endothelial adhesion, and displays extreme sequence diversity that underpins antigenic variation. In this issue of Cell Host & Microbe, Tessema et al. (2019) find that antibodies in sera from a pediatric cohort that bind a discrete PfEMP1 subset associate with protection from severe malaria and predict future risk. 5. Duffy PE. Structure solves the problem with malaria merozoite vaccines. Trends in Parasitology. 2019 Nov;35(11):855-857. doi: 10.1016/j.pt.2019.09.004. Malaria vaccines targeting merozoite invasion of erythrocytes have long held appeal but failed in clinical trials. Three structural studies of antibody-antigen complexes by Alanine et al., Urusova et al., and Rawlinson et al. define neutralizing and non-neutralizing epitopes in essential invasion proteins, leading to rational design of improved merozoite vaccines.

在第20财年，我们报告了研究疟疾免疫学和发病机理的人类和动物研究。在这几年中，摘要是我们出版物的结果。 1。RodriguesDSA，PRESTES EB，SILVA LDS，PINHEIRO AAS，FRANCISCHETTI I，SARAIVA E，NETO HAP，BOZZA MT。 'CXCR4和MIF是由PLOS病原体压机中质子感染的红细胞触发的中性粒细胞外陷阱释放所必需的。在印刷中。 中性粒细胞外陷阱（NET）演变为有助于感染的独特效应机制，这也可以在炎症条件下促进组织损伤。疟疾感染会触发净释放，但是在这种情况下，净形成的机制和后果仍然很差。在这里，我们表明，疟原虫感染的红细胞会导致健康供体的中性粒细胞形成净的净形成，这是一种依赖于巨噬细胞迁移抑制因子（MIF）释放的C-X-C趋化因子受体4型（CXCR4）的机制，被感染的红细胞感染抑制因子释放。患有脑疟疾的患者的循环DNA量增加，与血浆中NE活性增加相似。重要的是，感染了伯格（Berghei）的小鼠（一种脑疟疾模型）也具有大量的循环DNA，而用DNase进行治疗增加了寄生虫血症和加速死亡率，表明净作用在抵抗疟原虫感染中的作用。 2。RajDK，Mohapatra AD，Jnawali A，Zuromski J，Jha A，Cham-Kpu G，Sherman B，Sherman B，Rudlaff RM，Nixon CE，Hilton N，Hilton N，Oleinikov AV，Chesnokov O，Chesnokov O，Chesnokov O，Merritt J，Merritt J，Merritt J，Pond-tor l burns l burns l burns l burns L ，Jolly G，Mamoun CB，Kabyemala E，Muehlenbachs A，Lambert L，Orr-Gonzalez S，Gndig NF，Fidock DA，Park S，Dvorin JD，Pardi JD，Pardi N，Weissman D，Weissman D，Mui Bl，Mui Bl，Tam Yk，Tam Yk，Friedman Jf，Friedman Jf，Friedm jf，Fried Mied M. ，Duffy PE，Kurtis JD。抗PFGARP激活寄生虫的程序性细胞死亡，并减少严重的疟疾。自然。 2020 Jun; 582（7810）：104-108。 doi：10.1038/s41586-020-2220-1。 EPUB 2020年4月22日。 由恶性疟原虫引起的疟疾仍然是儿童死亡死亡率的主要原因，但尚未实现有效疫苗的承诺。在这里，使用我们先前描述的差异筛选方法来分析血阶段的恶性疟原虫寄生虫的蛋白质组，我们鉴定出恶性疟原虫谷氨酸酸性蛋白质（PFGARP）为寄生虫抗原，是儿童血浆中抗体识别的寄生虫抗原相对抗性的人，但不是那些因恶性疟原虫引起的疟疾症状的人。 PFGARP是一种80 kDa的寄生虫抗原，在被早期至肠道内寄生虫感染的红细胞外面表面表达。我们证明，针对PFGARP的抗体通过在寄生虫中诱导程序性细胞死亡杀死培养中感染的滋养体红细胞，并且用PFGARP疫苗接种了PFGARP的非人类灵长类动物，可以部分保护对恶性疟原虫的挑战。此外，我们的纵向队列研究表明，与自然发生抗PFGARP抗体的个体相比，没有抗PFGARP抗体的坦桑尼亚儿童具有严重的疟疾和肯尼亚青少年的2.5倍高2.5倍，而没有这些抗体， - 高寄生虫密度。通过杀死感染的滋养体红细胞，PFGARP可以与其他靶向寄生虫入侵肝细胞或从红细胞中侵袭和出口的疫苗协同作用。 3。Rajaai，Brickley EB，Taaffe J，Ton T，Zhao Z，Bock KW，Orr-Gonzalez S，Thomas ML，Lambert Le，Moore in，Duffy PE。严重疟疾贫血的灵长类动物模型：比较发病机理研究。科学报告。 2019年12月12日； 9（1）：18965。 doi：10.1038/s41598-019-55377-3。 严重的疟疾贫血（SMA）是非洲儿童恶性疟原虫感染的最常见生命的并发症。 SMA的特征是溶血和红细胞生成不足，并且与炎症反应失调和补体调节蛋白水平降低有关（包括CD35）。但是，对发病机理的更深入的理解需要改善动物模型。在对两个密切相关的猕猴物种的比较研究中，我们询问了潜在的因果因素，以使其差异和时间关系与SMA发作。我们发现，接种血液阶段疟原虫的恒河猕猴在2周内发生了SMA，没有其他严重的结果，而感染的cynomolgus猕猴只有轻度/中度贫血。恒河猴血细胞比容的突然下降，伴随着触觉球蛋白（溶血）和网状细胞不良的消费。恒河猴的炎症反应比cynomolgus猕猴更大，并且在红细胞（RBC）上的基线水平较低，导致感染过程中CD35+ RBC的比例显着降低。总体而言，感染P. Coatneyi的恒河猕猴的严重贫血与儿童的SMA具有相似的特征。我们的比较与RBC上低基线CD35水平以及SMA发病机理的早期炎症反应的相关性一致。 4。DuffyPE。对严重疟疾的免疫力：PFEMP1标签讲述了一个故事。细胞宿主和微生物。 2019年11月13日； 26（5）：571-573。 doi：10.1016/j.chom.2019.10.021。 PFEMP1是恶性疟原虫感染的红细胞的主要表面抗原，介导内皮粘附，并显示出抗原变异的极端序列多样性。在本期的细胞宿主和微生物中，Tessema等。 （2019年）发现，从儿科队列中的血清中的抗体结合了离散的PFEMP1子集与防止严重疟疾的保护并预测未来风险。 5。DuffyPE。结构解决了疟疾蛋白酶疫苗的问题。寄生虫学的趋势。 2019年11月； 35（11）：855-857。 doi：10.1016/j.pt.2019.09.004。 靶向红细胞梅洛氏菌入侵的疟疾疫苗长期以来一直具有吸引力，但在临床试验中失败。 Alanine等人，Urusova等人和Rawlinson等人对抗体 - 抗原复合物的三个结构研究。定义基本侵袭蛋白中中和和非中和表位，从而使改良的梅罗洛氏疫苗的理性设计。