Placental Mediated Mechanisms of Perinatal Brain Injury

总结 在美国，围产期脑损伤（PBI）是婴儿死亡和长期残疾的主要原因 小儿对于大部分患有PBI的婴儿，中枢神经系统（CNS）损伤始于子宫内， 炎症（绒毛膜炎/CHORIO）和/或缺氧缺血。CHORIO有助于早产CNS 损伤，也是足月儿脑损伤（包括围产期中风）的常见独立危险因素。 然而，介导胎盘-胎儿-脑轴炎症的分子机制导致PBI， 这是一个知识上的差距。趋化因子（C-X-C基序）配体1（CXCL 1）及其受体（CXCR 2）具有 临床上与CHORIO有关，对中性粒细胞募集、神经细胞发育和 成人CNS损伤，尽管它们在PBI病理生理学中的具体作用完全不确定。我们建议 使用我们建立的与脉络膜相关的中枢神经系统损伤的独特模型来描述子宫内 炎症会导致PBI。我们的中心假设是，CXCL 1分泌的绒毛膜蜕膜在 脉络膜进入胎儿血液，超越胎盘-胎儿-胎儿脑轴，并通过 CXCR 2+神经细胞和嗜中性粒细胞募集导致发育中的CNS损伤。我们把那个CHORIO 是由过度的CXCL 1/CXCR 2信号传导所定义的，这在长时间内对神经细胞是有毒的。 神经发育期为了研究这个假设，我们将：1）测试CHORIO干扰 妊娠晚期关键期胎盘-胎儿-胎儿脑轴中CXCL 1/CXCR 2信号转导 中枢神经系统发育; 2）测试胎盘CXCL 1移位至胎儿大脑并调节中性粒细胞和 3）测试CXCL 1/CXCR 2信号转导的减弱在以下情况下保护神经细胞： 乔里奥。使用多重电致发光免疫分析（MECI）、流式细胞术（FC）和qPCR， 将研究CHORIO诱导的CXCL 1/CXCL 2信号传导是否是一个统一的炎症信号 通过胎盘-胎儿-胎儿脑轴的转导机制。使用体外分析，包括外泌体 分析，胎盘外植体和急性脑切片，我们将驱动CXCL 1/CXCR 2，并定义主要的 胎盘-胎儿-胎儿脑轴损伤的分子介质。使用免疫中和，microRNA， 药理学（SB 225002）和遗传学（CXCR 2 KO）方法，我们将描述CXCL 1/CXCR 2是否 是CHORIO后免疫细胞向CNS募集的必要和充分条件。我们预测， CHORIO后短暂的CXCR 2缺陷将减弱小胶质细胞活化和中性粒细胞募集， 减轻白色物质和神经元损伤，并改善磁共振显微结构的一致性 显像这些研究将是第一个将胎盘中异常的CXCL 1/CXCR 2信号传导联系起来的研究。 胎儿脑轴慢性损伤和受损的神经发育，并将确定新的目标， 为PBI高危婴儿提供治疗。

Summary In the United States, perinatal brain injury (PBI) is a major cause of infant mortality and long-term disability in children. For a large proportion of infants with PBI, central nervous system (CNS) injury begins in utero with inflammation (chorioamnionitis/CHORIO) and/or hypoxia-ischemia. CHORIO contributes to preterm CNS injury, and is also a common, independent risk factor for brain injury in term infants, including perinatal stroke. However, the molecular mechanisms mediating inflammation in the placenta-fetal-brain axis that cause PBI remains a gap in knowledge. The chemokine (C-X-C motif) ligand 1 (CXCL1) and its receptor (CXCR2) have been clinically implicated in CHORIO, and are essential to neutrophil recruitment, neural cell development and adult CNS injury, although their specific role in PBI pathophysiology is completely undefined. We propose to use our established and unique model of CNS injury associated with CHORIO to delineate how in utero inflammation precipitates PBI. Our central hypothesis is that CXCL1 secreted by the choriodecidua during CHORIO enters fetal blood, transcends the placenta-fetus-fetal brain axis, and through interactions on CXCR2+ neural cells and neutrophil recruitment, confers injury in the developing CNS. We posit that CHORIO is defined by excess CXCL1/CXCR2 signaling, which is toxic to neural cells over an extended neurodevelopmental period. To investigate this hypothesis we will: 1) Test that CHORIO disturbs CXCL1/CXCR2 signaling throughout the placenta-fetus-fetal brain axis during a critical period of late gestation CNS development; 2) Test that placental CXCL1 translocates to the fetal brain and modulates neutrophils and microglia; and 3) Test that attenuation of CXCL1/CXCR2 signal transduction protects neural cells following CHORIO. Using multiplex electrochemiluminescent immunoassay (MECI), flow cytometry (FC), and qPCR we will investigate whether CHORIO induced CXCL1/CXCL2 signaling is a unifying inflammatory signal transduction mechanism through the placenta-fetus-fetal brain axis. Using in vitro assays, including exosome analyses, placental explants and acute brain slices, we will drive CXCL1/CXCR2, and define the major molecular mediators of damage to the placenta-fetus-fetal brain axis. Using immunoneutralization, microRNA, pharmacological (SB225002), and genetic (CXCR2 KO) approaches, we will delineate whether CXCL1/CXCR2 is necessary and sufficient for immune cell recruitment to the CNS following CHORIO. We predict creating a transient CXCR2 deficiency following CHORIO will attenuate microglial activation and neutrophil recruitment, mitigate white matter and neuronal injury, and improve microstructural coherence on magnetic resonance imaging. These investigations will be the first to connect aberrant CXCL1/CXCR2 signaling in the placenta- fetal-brain axis to chronic injury and impaired neurodevelopment, and will define novel targets for directed therapies for infants at high risk for PBI.