Exploring human milk oligosaccharides and malaria risk in breastfed infants

摘要 非洲的婴儿患疟疾的负担很重，其中大多数从出生到24岁都是母乳喂养的。 个月这些“突破性”疟疾感染可能表明母乳喂养的保护不充分。有一个 我们对母乳喂养介导的抗疟免疫及其相关因素的认识存在重大差距。我们 最近的初步数据表明，高浓度的特定人乳低聚糖（HMO）， 乌干达母亲的乳汁与婴儿患疟疾的风险之间存在差异。健康维护组织代表了第三大 母乳中丰富的成分，在婴儿摄入后，它们直接到达体循环， 通过特定的表面受体与先天免疫细胞接合。涉及离体刺激人细胞的研究， 细胞系证明HMO以几种方式调节巨噬细胞和单核细胞的功能。这包括 诱导抗炎或促炎反应，诱导或抑制单核细胞或巨噬细胞活化， 抑制增殖或迁移，以及增强吞噬作用。一项涉及婴儿的人类临床试验， 配方中的岩藻糖基乳糖（2 'FL）证实了2' FL的抗炎作用。 单核细胞功能与儿童疟疾高度相关，其涉及单核细胞失调和全身性 炎症我们的长期目标是阐明HMO在抗疟疾的早期先天免疫中的作用。 本项目的目的是确定母乳中HMO与婴儿血液、单核细胞 功能和母乳喂养婴儿的疟疾结果。核心假设是单核细胞的直接HMO调节 提示平衡对疾病或保护在小儿疟疾和具体的HMO水平的差异， 与不同的疟疾结果有关。这一假设将在两个具体目标中得到检验。目标1：招募出生队列 并前瞻性地收集包括疟疾结果和可溶性单核细胞活化浓度的健康元数据 标志物、细胞因子和趋化因子。将招募388对母婴的出生队列， 随访18个月以上，每月和婴儿患病期间采血进行疟疾诊断， 基于珠粒的细胞因子和趋化因子测定以及用于可溶性单核细胞活化标志物的ELISA。目标2：衡量 母乳和婴儿血浆中HMO的浓度，以评估其与单核细胞介质的相关性， 疟疾对婴儿的影响。我们将每月测量母乳和婴儿血浆中HMO的浓度， 在儿童疟疾发作期间，鉴定与特定单核细胞炎性细胞因子相关的HMO， 趋化因子和激活标记物，它们反过来与不同的疟疾结果有关。为了说明相关性 同一婴儿的多次测量之间的关系，疟疾结果之间的关系，具体的HMO， 将通过广义估计方程法评估单核细胞功能标志物，同时控制 协变量，如产妇年龄和产次、婴儿性别、采样季节和其他疟疾风险因素。团队带来了 在疟疾和HMO研究方面的经验，加上乌干达的研究人群。 总之，这些拟议的探索性研究将为HMO在疟疾中发挥的关键作用提供初步见解 先天免疫该项目将为HMO-单核细胞相互作用的更有力的机制研究奠定基础， 将为新型抗疟干预措施的设计提供信息。研究结果可推广到其他高负荷地区 疟疾在婴儿身上的传播推动该领域向前发展并产生可持续影响的潜力很大。

ABSTRACT There is a significant burden of malaria in young African infants - the majority of whom are breastfed from birth up to 24 months. These `break through' malaria infections probably indicate incomplete protection by breastfeeding. There is a significant gap in our knowledge about antimalarial immunity mediated by breastfeeding and the factors involved. Our recent preliminary data demonstrated that high concentrations of specific human milk oligosaccharides (HMOs) in Ugandan mothers' milk are differentially associated with malaria risk in their infants. HMOs represent the third most abundant component in breast milk which, upon ingestion by infants, reach the systemic circulation where they directly engage innate immune cells through specific surface receptors. Studies involving ex vivo stimulation of human cells and cell lines demonstrated that HMOs modulate the functions of macrophages and monocytes in several ways. This includes inducing anti-inflammatory or proinflammatory responses, inducing or inhibiting monocyte or macrophage activation, inhibition of proliferation or migration, and enhancing phagocytosis. A human clinical trial involving infants fed 2'- fucosyllactose (2'FL) in formula confirmed the anti-inflammatory effect of 2'FL. HMO-mediated modulation of monocyte function is highly relevant to pediatric malaria which involves monocyte dysregulation and systemic inflammation. Our long-term goal is to elucidate the role of HMOs in early innate immunity against malaria. The objective of this project is to determine the relationship between HMOs in breast milk and infant blood, monocyte function, and malaria outcomes in breast-fed infants. The central hypothesis is that direct HMO modulation of monocytes tips the balance towards disease or protection during pediatric malaria and that differences in levels of specific HMOs are linked to different malaria outcomes. This hypothesis will be tested in two Specific Aims. Aim 1: To recruit a birth cohort and prospectively collect health metadata including malaria outcomes and concentrations of soluble monocyte activation markers, cytokines and chemokines in infants. A birth cohort of 388 mother-infant pairs will be recruited and infants followed over 18 months with blood sampling every month and during infant illness for malaria diagnosis, multiplex bead-based cytokine and chemokine assays and ELISA for soluble monocyte activation markers. Aim 2: To measure concentrations of HMOs in mothers' milk and infant plasma to assess their association with monocyte mediators and malaria outcomes in infants. We will measure concentrations of HMOs in mothers' milk and infant plasma monthly and during pediatric malaria attacks to identify HMOs that are associated with specific monocyte inflammatory cytokines and chemokines and activation markers which are, in turn, linked to distinct malaria outcomes. To account for correlation between multiple measurements in the same infant, the relationships between malaria outcomes, specific HMOs, and markers of monocyte function will be assessed by Generalized Estimating Equation method while controlling for covariates such as maternal age and parity, infant sex, season of sampling and other malaria risk factors. The team brings experience in malaria and HMO research plus access to a study population in Uganda. Together, these proposed exploratory studies will provide preliminary insights on the crucial role that HMOs play in malaria innate immunity. This project will set the stage for more powered mechanistic studies of HMO-monocyte interactions which will inform the design of novel antimalarial interventions. The results are generalizable to other regions with a high burden of malaria in young infants. The potential to move the field forward and make a sustainable impact is high.