Prenatal metal mixtures and neurodevelopment: Role of placental extracellular microRNAs

项目总结 神经发育和认知功能是最重要的公共卫生结果之一。损失 由于毒素，如金属，在生命早期的功能可能会产生终生影响。预防 胎儿起源的神经发育障碍由于缺乏早期检测的客观工具而受到阻碍 易感人群。我们将讨论产前金属暴露在神经发育中的作用，整合 这项工作的总体目标是了解金属暴露如何影响胎盘提示，特别是 释放细胞外小泡(EV)，促进和指导神经发育。事实证明， 胎盘滋养层细胞主动释放EVS，即纳米大小的膜结合囊泡。 和胎儿循环。电动汽车将生物活性分子从滋养层细胞运送到受体细胞，例如 MicroRNAs(MiRNAs)为母体组织提供支持胎儿发育的物质。在胎儿循环中，EVS 可以跨越血脑屏障，尤其是在胎儿大脑周围的屏障仍然存在的情况下 多孔性和渗透性。不仅胎盘是金属中毒的主要目标，数据显示EV信号 对环境影响很敏感，包括金属。到目前为止还没有一项研究调查 胎儿期接触金属决定了循环EV信号的变化，进而可能 帮助诊断和预测神经发育中的变化。值得注意的是，已知许多胎盘miRNAs 调节神经发育并显著过度表示与以下相关的基因本体论术语 神经发生。我们认为，子宫内金属暴露破坏了胎盘组织中正常的miRNA表达。 并在循环中的EVS中释放，从而改变神经干细胞的增殖、自我更新和分化 在胎儿发育过程中。反过来，我们认为EV包装的miRNAs在母体循环中 怀孕反映了这种胎儿编程的早期生物学环境。我们将开展一系列协调一致的 人体研究和体外实验，以：1)表征神经发育不良的风险 产前暴露于有毒金属及其混合物；2)识别EV包裹的miRNAs 胎盘对金属的反应通过母体血液获得这种新的产前信号形式 孕期、脐带血和出生时的胎盘活检；以及3)进行体外实验，以评估 滋养层细胞在单独的金属或其处理后是否释放EV包裹的miRNAs 混合物；以及金属处理滋养层细胞释放的EV中的miRNAs是否改变了神经的关键功能 干细胞。我们利用代际应激机制(PRISM)队列的编程 对N=470名48个月大的儿童进行行为去抑制的前瞻性评估。当我们 提出潜在的理论途径，首要目标是寻找早期风险的生物标志物。然而， 这些发现还可能促进我们对影响神经发育风险的分子途径的理解， 这将对制定预防战略和可能的治疗干预措施至关重要。

PROJECT SUMMARY Neurodevelopment and cognitive function are among the most important public health outcomes. Loss of functioning early in life due to toxins, such as metals, can have lifelong impacts. The prevention of neurodevelopmental disorders of fetal origin is impeded by the lack of objective tools for early detection of susceptible individuals. We will address the role of prenatal metal exposure on neurodevelopment, integrating this work with the overall goal of understanding how metal exposures impact placental cues, specifically release of extracellular vesicles (EVs), which facilitate and direct neurodevelopment. It has been shown that placental trophoblasts actively release EVs, i.e., nano-sized membrane-bound vesicles, in both the maternal and fetal circulation. EVs shuttle cargoes of bioactive molecules from trophoblasts to recipient cells, such as microRNAs (miRNAs) that prime maternal tissues to support fetal development. In the fetal circulation, EVs can cross the blood-brain barrier, particularly in prenatal life when the barrier around the fetal brain is still porous and permeable. Not only is the placenta a primary target of metal toxicities, data show that EV signaling is sensitive to environmental influences, including metals. No study to date has investigated whether exposures to metals during the prenatal period determine alterations of circulating EV signals that, in turn, may help to diagnose and predict alterations in neurodevelopment. Notably, many placental miRNAs are known to regulate neurodevelopment and have significant overrepresentation of Gene Ontology terms associated with neurogenesis. We propose that in utero metal exposure disrupt normal miRNA expression in placental tissue and their release in circulating EVs, thus altering neural stem cell proliferation, self-renewal and differentiation during fetal development. In turn, we propose that EV-packaged miRNAs in the maternal circulation in pregnancy reflect early biological settings of this fetal programming. We will conduct a coordinated series of human studies and in-vitro experiments to: 1) characterize the risk for maladaptive neurodevelopment from prenatal exposure to toxic metals and their mixtures; 2) identify EV-encapsulated miRNAs released by the placenta in response to metals by accessing this novel form of prenatal signaling through a maternal blood draw during pregnancy, cord blood, and placental biopsy at birth; and 3) conduct in-vitro experiments to assess whether EV-encapsulated miRNAs are released by trophoblasts after treatment with individual metals or their mixtures; and whether miRNAs in EVs released from metal-treated trophoblasts alter critical functions of neural stem cells. We leverage the PRogramming of Intergenerational Stress Mechanisms (PRISM) cohort with prospective assessment of behavioral disinhibition in N=470 children followed to age 48 months. While we propose underlying theoretical pathways, the primary goal is to search for biomarkers of early risk. However, findings may also advance our understanding of molecular pathways that influence neurodevelopmental risk, which will be critical for the development of preventative strategies and possible therapeutic interventions.