Innate Immune Mechanisms Governing Subclinical Malaria in Children

控制儿童亚临床疟疾的先天免疫机制

• 批准号: 10460703
• 负责人: Douglas T Golenbock
• 金额: $ 73.77万
• 依托单位: CASE WESTERN RESERVE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10460703
• 关键词: 15 year old; ATAC-seq; Address; Affect; Africa; Africa South of the Sahara; Age; Agonist; Anopheles Genus; Anti-Inflammatory Agents; Area; Binding Sites; Biological Assay; Biomass; Blood; Blood specimen; Cells; Child; Chromatin; Chronic; Clinical; Communities; Complex; County; Culicidae; Cytokine Gene; Cytometry; DNA; DNA sequencing; Data; Development; Disease; Elements; Enhancers; Enrollment; Epidemiology; Epigenetic Process; Equilibrium; Fever; Gene Expression; Gene Expression Profile; Genes; Goals; High-Throughput Nucleotide Sequencing; Homeostasis; Immune; Immunomodulators; In Vitro; Individual; Infection; Inflammation Mediators; Inflammatory; Inflammatory Response; Innate Immune Response; Interferon Type II; Interferons; Interleukin-1 Receptors; Interleukin-10; Interleukin-6; Kenya; Knowledge; Legal patent; Longitudinal cohort study; Malaria; Measurement; Modification; Parasitemia; Parasites; Pathway interactions; Peripheral Blood Mononuclear Cell; Plasma; Plasmodium falciparum; Population; Production; Proteins; Public Health; RNA analysis; Regulator Genes; Regulatory Pathway; Regulatory T-Lymphocyte; Research; Role; School-Age Population; Site; Source; Specificity; Symptoms; T-Lymphocyte Subsets; TNF gene; Testing; Tissue-Specific Gene Expression; Toll-like receptors; Transposase; Work; adaptive immunity; age group; antagonist; chromatin immunoprecipitation; cohort; comparison group; cytokine; effector T cell; epigenetic marker; epigenome; innate immune mechanisms; innate immune pathways; insight; monocyte; promoter; response; rural area; sex; transcription factor; transcriptome sequencing; transmission process; vector; vector mosquito

ABSTRACT Subclinical (asymptomatic) malaria with Plasmodium falciparum (Pf) is common in children who live in moderate- to-high transmission areas of sub-Saharan Africa. Although subclinical malaria may be submicroscopic, affected school-age children (ages 8-15 years) often have positive blood smears that include millions of parasites per mL of blood. While subclinical malaria is typically attributed to acquired adaptive immunity that tightly controls the Pf biomass, patent parasitemia (blood smear+) exceeds any reasonable estimate of the pyrogenic threshold. How is it possible to remain without fever and overt malaria symptoms with patent parasitemia? In contrast to symptomatic malaria, temporally persistent (chronic) subclinical malaria seems to be maintained by a complex balance of pro-inflammatory and anti-inflammatory cytokines and immune cells. The scientific premise of this proposal is that epigenetic modifications of innate immune cells, including blood monocytes (Mo), modulate inflammatory pathways underlying subclinical malaria. Furthermore, we hypothesize that an immune homeostasis network involving anti-inflammatory Pf-induced type 1 T regulatory cells (Tr1) and IL-10 as well as enhanced IL-1RA production suppress innate immune inflammatory pathways. Subclinical malaria is of high epidemiologic significance as parasitemia persists for months in schoolchildren who serve as the major reservoir of gametocytes required to sustain Pf transmission to local anopheline vectors. Indeed, it is estimated that ~ 60% of new mosquito infections can be attributed to this demographic. To test our hypotheses, we will enroll Kenyan schoolchildren (ages 8-15) in a longitudinal cohort study to compare and analyze differences in immune parameters between those with A) chronic subclinical malaria (Pf+ smear at baseline and who remain afebrile despite repeatedly smear+ x 16 weeks) relative to B) children who develop febrile clinical malaria up to 2 weeks after an afebrile Pf+ smear. The specificity of immune parameters for chronic Pf exposure in these cohorts will be interrogated by comparison to age and sex matched children residing in a nearby highlands area where malaria endemicity is ~ zero. PBMC and isolated Mo from children will be analyzed by RNA-seq to determine activated gene expression pathways. We will define the differences in immune cell subsets, the transcription factors that are activated and their effector cytokine expression profiles using mass cytometry (CyTOF). In addition, we will use chromatin immunoprecipitation (ChIP) DNA sequencing to determine if the epigenomes of children with chronic subclinical malaria are modified in order to silence proinflammatory genes or conversely, to activate anti-inflammatory ones. Finally, we will identify and compare by Assay for Transposase-Accessible Chromatin with high-throughput Sequencing (ATAC-seq) open chromatin sites in key gene expression pathways in Mo from the comparator groups and align these regions with RNA-seq data from the same child. The successful completion of this project should give us new and important insights as to the mechanism of subclinical malaria and how this disease state can be modified to facilitate malaria eradication.

抽象的 恶性疟原虫 (Pf) 引起的亚临床（无症状）疟疾在生活在中度地区的儿童中很常见。 撒哈拉以南非洲的高传播地区。尽管亚临床疟疾可能是亚微观的，但受影响的 学龄儿童（8-15 岁）的血涂片通常呈阳性，每毫升含有数百万个寄生虫 的血。虽然亚临床疟疾通常归因于严格控制 Pf 的获得性适应性免疫 生物量、明显的寄生虫血症（血涂片+）超过了热原阈值的任何合理估计。如何 是否有可能在患有明显的寄生虫血症的情况下保持不发烧和明显的疟疾症状？相比之下 有症状的疟疾，暂时持续（慢性）亚临床疟疾似乎是由一种复杂的机制维持的 促炎和抗炎细胞因子和免疫细胞的平衡。这样做的科学前提 该提议认为，先天免疫细胞（包括血液单核细胞（Mo））的表观遗传修饰可以调节 亚临床疟疾的炎症途径。此外，我们假设免疫 稳态网络涉及抗炎 Pf 诱导的 1 型 T 调节细胞 (Tr1) 和 IL-10 以及 IL-1RA 产生增强可抑制先天免疫炎症途径。亚临床疟疾发病率很高 流行病学意义，因为学童是寄生虫血症的主要宿主，寄生虫血症持续数月 维持 Pf 向局部按蚊载体传播所需的配子细胞数。确实，估计是~ 60% 的新蚊子感染可归因于这一人群。为了检验我们的假设，我们将注册 肯尼亚学童（8-15 岁）参与纵向队列研究，比较和分析免疫差异 A) 慢性亚临床疟疾患者（基线时 Pf+ 涂片与保持不发热者之间的参数 尽管反复涂片+ x 16周）相对于B）发展为发热性临床疟疾长达2周的儿童 不发热 Pf+ 涂片后。这些人群中慢性磷暴露的免疫参数的特异性将 通过与居住在附近高地地区的年龄和性别匹配的儿童进行比较来进行讯问 疟疾流行率为零。将通过 RNA-seq 分析来自儿童的 PBMC 和分离的 Mo，以确定 激活基因表达途径。我们将定义免疫细胞亚群、转录的差异 使用质谱流式细胞仪 (CyTOF) 分析被激活的因子及其效应细胞因子表达谱。在 此外，我们将使用染色质免疫沉淀 (ChIP) DNA 测序来确定表观基因组是否 对患有慢性亚临床疟疾的儿童进行改造，以沉默促炎基因，或者相反， 激活抗炎物质。最后，我们将通过转座酶可及性分析来识别和比较 高通量测序 (ATAC-seq) 染色质打开关键基因表达途径中的染色质位点 并将这些区域与来自同一孩子的 RNA-seq 数据进行比对。这 这个项目的成功完成应该给我们关于机制的新的、重要的见解。 亚临床疟疾以及如何改变这种疾病状态以促进根除疟疾。