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Mechanisms of Neonatal Erythropoietin Neuroprotection

新生儿促红细胞生成素神经保护机制

基本信息

批准号：
8437462
负责人：
SHENANDOAH ROBINSON
金额：
$ 24.56万
依托单位：
BOSTON CHILDREN'S HOSPITAL
依托单位国家：
美国
项目类别：
财政年份：
2008
资助国家：
美国
起止时间：
2008-07-01 至 2013-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8437462
关键词：
Mechanisms Neonatal Erythropoietin Neuroprotection

项目摘要

DESCRIPTION (provided by applicant): Children who are born very preterm are prone to cerebral palsy, epilepsy, cognitive delay and behavioral problems, but current interventions have failed to reduce the neurologic morbidity. Typically, systemic hypoxia- ischemia (HI), infection, or more commonly a combination of both, cause prenatal central nervous system (CNS) injury prior to birth with prolonged postnatal loss of neurons and oligodendrocytes, culminating in impaired circuit formation. Neural cell loss occurs primarily by apoptosis with failure of new waves of progenitors to survive. Erythropoietin (EPO) and its cognate receptor EPOR are required for prenatal brain development, especially in the second half of gestation, where EPO signaling locally regulates neural cell survival to prune neural cell overproduction. Unbound EPOR drives neural cells to apoptosis, while ligand- bound EPOR activates survival signaling pathways. EPO also has neuroprotective properties and crosses the blood-brain barrier. We used an established model of prenatal transient systemic HI from uterine artery occlusion, and transient systemic HI plus intracervical lipopolysaccharide (LPS) to mimic human systemic prenatal HI insults and combined ischemic/inflammatory insults. We found neonatal EPO treatment reverses the histological and functional deficits of adult rats after prenatal HI injury. Our pilot data reveal a novel molecular mechanism of EPO signaling that helps to explain the excess apoptosis that occurs after prenatal insults, and suggests a novel drug intervention using exogenous EPO in the neonatal period. We found that systemic prenatal HI appears to upregulate neural cell EPOR on the most vulnerable neural cells, neurons and oligodendrocytes, and that exogenous neonatal EPO appears to enhance survival and process formation by neural cells after prenatal HI. We hypothesize that prenatal insults upregulate EPOR on neural cells and that without adequate EPO present these cells undergo apoptosis. We propose that after prenatal insults neonatal exogenous EPO rescues neural cells, enhances their survival and differentiation, ultimately improving circuit formation, and leading to functional recovery. We will use our model of prenatal HI with and without intracervical lipopolysaccharide (LPS) to produce prenatal insults to test our hypothesis. In Aim 1 we will define the expression pattern of EPO, EPOR and identify the up and downstream signaling molecules active in damaged developing neural cells after prenatal HI, and LPS plus HI. In Aim 2 we will test the whether EPO signaling regulates neural cell survival and differentiation in vitro using dose-response curves and specific molecular inhibitors. Lastly, in Aim 3 we will manipulate the expression of EPOR in damaged developing neural cells to clarify whether over-expression or silencing of EPOR supports our predictions. Together, these studies will clarify the mechanism of EPO-induced neural cell recovery after prenatal injury. They will provide the much needed preclinical foundation for potentially translating this promising therapeutic option using neonatal EPO to infants born prematurely, and optimize the chance these children develop without deficits. Children who are born very preterm suffer from cerebral palsy, epilepsy, cognitive delay and behavioral problems, placing a tremendous burden on these children, their families, and society. Current interventions have failed to improve their outcome. To treat infants born preterm, we propose a novel drug intervention with erythropoietin, a drug currently used to treat anemia, as EPO both provides neuroprotection and enhances development of the neural cells most vulnerable to damage from preterm insults.

描述（由申请人提供）：早产儿容易发生脑瘫、癫痫、认知延迟和行为问题，但目前的干预措施未能降低神经系统发病率。通常，全身性缺氧-缺血（HI）、感染或更常见的两者的组合在出生前引起产前中枢神经系统（CNS）损伤，伴随神经元和少突胶质细胞的出生后长时间损失，最终导致回路形成受损。神经细胞损失主要通过凋亡发生，新一波祖细胞无法存活。促红细胞生成素（EPO）及其同源受体EPOR是产前脑发育所必需的，特别是在妊娠的后半期，其中EPO信号传导局部调节神经细胞存活以修剪神经细胞过度生产。未结合的EPOR驱动神经细胞凋亡，而配体结合的EPOR激活存活信号通路。EPO还具有神经保护特性并穿过血脑屏障。我们使用了一个建立的模型，产前短暂的全身性HI子宫动脉闭塞，短暂的全身性HI加脑内脂多糖（LPS）模拟人类全身性产前HI侮辱和联合缺血/炎症的侮辱。我们发现新生儿EPO治疗逆转了产前HI损伤后成年大鼠的组织学和功能缺陷。我们的试点数据揭示了EPO信号传导的一种新型分子机制，有助于解释产前损伤后发生的过度细胞凋亡，并提出了在新生儿期使用外源性EPO的新型药物干预。我们发现，系统性产前HI似乎上调神经细胞EPOR对最脆弱的神经细胞，神经元和少突胶质细胞，和外源性新生儿EPO似乎提高存活率和过程形成后，产前HI的神经细胞。我们推测，产前侮辱上调EPOR的神经细胞，没有足够的EPO目前这些细胞进行凋亡。我们认为，在产前损伤新生儿外源性EPO拯救神经细胞，提高他们的生存和分化，最终改善电路的形成，并导致功能恢复。我们将使用我们的产前HI模型，有和没有脑内脂多糖（LPS），以产生产前侮辱，以测试我们的假设。目的1：明确EPO、EPOR的表达模式，并鉴定产前HI和LPS + HI后受损发育神经细胞中激活的上下游信号分子。在目标2中，我们将测试是否EPO信号调节神经细胞的存活和分化在体外使用剂量反应曲线和特定的分子抑制剂。最后，在目标3中，我们将操纵受损发育神经细胞中EPOR的表达，以澄清EPOR的过表达或沉默是否支持我们的预测。总之，这些研究将阐明EPO诱导的产前损伤后神经细胞恢复的机制。他们将提供急需的临床前基础，以便将这种使用新生儿EPO的有前景的治疗选择转化为早产儿，并优化这些儿童无缺陷发育的机会。早产儿患有脑瘫，癫痫，认知延迟和行为问题，给这些孩子，他们的家庭和社会带来了巨大的负担。目前的干预措施未能改善其结果。为了治疗早产儿，我们提出了一种新的药物干预与促红细胞生成素，目前用于治疗贫血症的药物，因为EPO既提供神经保护，并增强最容易受到早产损伤的神经细胞的发育。