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（申请人提供）：早产儿容易出现脑瘫、癫痫、认知迟缓和行为问题，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）、感染或更常见的是两者的组合，在出生前导致产前中枢神经系统（CNS）损伤，并导致出生后神经元和少突胶质细胞长期丢失，最终导致神经回路形成受损。神经细胞损失主要是由于细胞凋亡导致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 是产前大脑发育所必需的，尤其是在妊娠后半期，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成。未结合的 EPOR 驱动神经细胞凋亡，而配体结合的 EPOR 激活生存信号通路。 EPO 还具有神经保护特性并能穿过血脑屏障。我们使用了由子宫动脉闭塞引起的产前短暂性全身性 HI 的既定模型，以及短暂性全身性 HI 加宫颈内脂多糖 (LPS) 的模型来模拟人类系统性产前 HI 损伤和组合缺血/炎症损伤。我们发现新生 EPO 治疗可逆转成年大鼠产前 HI 损伤后的组织学和功能缺陷。我们的试验数据揭示了 EPO 信号传导的一种新分子机制，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 的新型药物干预措施。我们发现，全身性产前 HI 似乎上调了最脆弱的神经细胞、神经元和少突胶质细胞上的神经细胞 EPOR，并且外源性新生儿 EPO 似乎可以增强产前 HI 后神经细胞的存活和过程形成。我们假设产前损伤会上调神经细胞上的 EPOR，并且如果没有足够的 EPO 存在，这些细胞就会发生凋亡。我们提出，在产前损伤后，新生儿外源性 EPO 可以拯救神经细胞，增强其存活和分化，最终改善回路形成，导致功能恢复。我们将使用带有和不带有宫颈内脂多糖 (LPS) 的产前 HI 模型来产生产前损伤来检验我们的假设。在目标 1 中，我们将定义 EPO、EPOR 的表达模式，并识别产前 HI 和 LPS 加 HI 后受损发育神经细胞中活跃的上下游信号分子。在目标 2 中，我们将使用剂量反应曲线和特定分子抑制剂来测试 EPO 信号传导是否在体外调节神经细胞存活和分化。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，以阐明 EPOR 的过度表达或沉默是否支持我们的预测。总之，这些研究将阐明 EPO 诱导产前损伤后神经细胞恢复的机制。他们将为早产儿使用新生儿促红细胞生成素这一有前景的治疗方案提供急需的临床前基础，并优化这些儿童无缺陷发育的机会。早产儿患有脑瘫、癫痫、认知迟缓和行为问题，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方法，即促红细胞生成素（一种目前用于治疗贫血的药物），因为 EPO 既可以提供神经保护，又可以增强最容易受到早产损伤的神经细胞的发育。