Prenatal metal mixtures and neurodevelopment: Role of placental extracellular microRNAs

项目摘要 神经发育和认知功能是最重要的公共卫生结果之一。损失 由于金属等毒素，生命早期的功能可能会产生终身影响。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， 易受影响的个体。我们将讨论产前金属暴露对神经发育的作用， 这项工作的总体目标是了解金属暴露如何影响胎盘线索，特别是 细胞外囊泡（EV）的释放，促进和指导神经发育。已经显示 胎盘滋养层主动释放EV，即，纳米大小的膜结合囊泡，在母体 和胎儿循环。EV将生物活性分子从滋养层运送到受体细胞，如 microRNAs（miRNAs）是母体组织支持胎儿发育的主要基因。在胎儿循环中，EV 可以穿过血脑屏障，特别是在胎儿大脑周围的屏障仍然存在的产前生活中。 多孔且可渗透。不仅胎盘是金属毒性的主要靶点，数据显示EV信号传导 对环境影响敏感，包括金属。到目前为止，还没有研究调查是否 在产前期间暴露于金属决定了循环EV信号的改变，反过来， 有助于诊断和预测神经发育的变化。值得注意的是，已知许多胎盘miRNAs 调节神经发育，并有显着的过度表达基因本体论术语相关， 神经发生我们认为子宫内金属暴露会破坏胎盘组织中正常的miRNA表达 以及它们在循环EV中的释放，从而改变神经干细胞增殖、自我更新和分化 在胎儿发育期间。反过来，我们提出，EV包装的miRNA在母体循环中， 怀孕反映了这种胎儿编程的早期生物学设置。我们将进行一系列协调一致的 人类研究和体外实验，以：1）表征适应不良神经发育的风险， 产前暴露于有毒金属及其混合物; 2）鉴定由肠病毒释放的EV包裹的miRNA， 胎盘通过母体血液进入这种新形式的产前信号， 妊娠期间抽取脐带血，出生时进行胎盘活检; 3）进行体外实验， EV包裹的miRNA是否在用单独的金属或它们的组合处理后由滋养层释放。 混合物;以及从金属处理的滋养层细胞释放的EV中的miRNA是否改变神经细胞的关键功能。 干细胞我们利用代际压力机制的程序设计（PRISM）队列， 对470名随访至48个月的儿童进行行为去抑制的前瞻性评估。虽然我们 提出潜在的理论途径，主要目标是寻找早期风险的生物标志物。然而，在这方面， 这些发现也可能促进我们对影响神经发育风险的分子途径的理解， 这对于制定预防策略和可能的治疗干预至关重要。

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.