Innate Immune Mechanisms Governing Subclinical Malaria in Children

摘要 亚临床(无症状)疟疾合并恶性疟(PF)常见于生活在中等偏僻地区的儿童。 到撒哈拉以南非洲的高传播区。虽然亚临床疟疾可能是亚微观的，但影响 学龄儿童(8-15岁)通常有阳性的血液涂片，每毫升含有数百万个寄生虫 鲜血。而亚临床疟疾通常归因于获得了严格控制PF的获得性免疫 生物量、显性寄生虫血症(血涂片+)超过任何合理的致热阈值。多么 是否有可能保持无发热和明显的疟疾症状，并伴有明显的寄生虫血症？与之形成鲜明对比的是 有症状的疟疾，暂时持续的(慢性)亚临床疟疾似乎由一种复杂的 促炎和抗炎细胞因子和免疫细胞的平衡。这其中的科学前提是 认为先天免疫细胞的表观遗传修饰，包括血液单核细胞(Mo)，可以调节 亚临床疟疾潜在的炎症途径。此外，我们假设一种免疫力 涉及抗炎因子诱导的1型T调节细胞(TR1)和IL-10以及 IL-1RA的产生增强抑制了先天免疫炎症途径。亚临床疟疾发病率高 寄生虫血症在作为主要宿主的学龄儿童中持续数月的流行病学意义 维持PF传播到局部按蚊载体所需的配子体的数量。的确，据估计~ 60%的新蚊子感染可以归因于这一人群。为了检验我们的假设，我们将注册 肯尼亚学龄儿童(8-15岁)在纵向队列研究中比较和分析免疫差异 A)慢性亚临床疟疾(PF+基线涂片)和仍未发烧的患者之间的参数 尽管反复涂片+x 16周)相对于B)发展为发热临床疟疾长达2周的儿童 在一次不发烧的PF+涂片之后。这些队列中慢性PF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审问 疟疾的流行度为零。对儿童的PBMC和分离的钼进行RNA-seq分析，以确定 激活基因表达途径。我们将定义免疫细胞亚群的差异，即转录 用质量细胞术(CyTOF)分析被激活的因子及其效应细胞因子的表达谱。在……里面 此外，我们将使用染色质免疫沉淀(ChIP)DNA测序来确定 患有慢性亚临床疟疾的儿童被修改以沉默促炎基因，或者相反， 来激活抗炎因子。最后，我们将通过检测来鉴定和比较转座酶可访问的 染色质高通量测序(ATAC-SEQ)在关键基因表达途径中开放染色质位置 并将这些区域与来自同一子代的RNA-SEQ数据进行比对。这个 这一项目的成功完成应该会给我们提供新的和重要的见解，以了解 亚临床疟疾以及如何改变这种疾病状态以促进根除疟疾。

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.