Blood-brain barrier function after neonatal and pediatric experimental stroke

描述(申请人提供)：儿童中风是一个新兴领域。对人类的研究表明，儿童中风与新生儿中风不同，但没有动物模型可以帮助确定儿童中风的机制。不成熟显著影响损伤的神经炎性机制，正如我们在新生儿局灶性中风的啮齿动物模型和类似的成人模型中所显示的那样。此外，血脑屏障(BBB)的完整性在急性新生儿卒中中比成人卒中中保存得更好。虽然这一结论自相矛盾，但有几条证据支持这一结论，包括血脑屏障的功能和结构完整性，以及一系列血脑屏障蛋白的差异基因和蛋白质表达。一项研究表明，在幼年大鼠脑内炎症攻击后，血脑屏障受损，但在新生大鼠中没有，这表明血脑屏障对损伤的敏感性与年龄有关；因此，血脑屏障对新生儿和儿童中风的反应可能有很大差异。我们假设，儿童和新生儿卒中的机制不同，部分原因是血脑屏障的成熟状态不同。为了确定新生儿和幼年脑对中风的不同BBB反应，我们将重点研究发育调节的BBB机制，这些机制在新生啮齿动物中是“沉默的”，但在幼年啮齿动物中是活跃的。我们将使用我们的出生后7天(P7)大鼠和P9小鼠的局灶性卒中模型和幼年大鼠和小鼠的局灶性卒中模型来确定急性儿童动脉卒中后血脑屏障完整性是否受到干扰(目标1)，以及小胶质细胞/单核细胞是否对新生儿和儿童卒中后的血脑屏障通透性产生不同的影响(目标2)。BBB的功能和结构完整性将在有或没有卒中后紧密连接完整性的额外挑战的动物中确定。小胶质细胞激活与血脑屏障通透性(血管内示踪剂)之间的关系将通过中风后活的Cx3cr1GFP/+新生和幼鼠的双光子成像来确定。外周和脑巨噬细胞参与损伤和破坏血脑屏障的程度将在两个年龄组的新型Cx3cr1GFP/+/CCR2RFP/+敲入小鼠中确定。

DESCRIPTION (provided by applicant): Pediatric stroke is an emerging field. Research in humans suggests that pediatric stroke differs from neonatal stroke, but there are no animal models that can help identify the mechanisms of pediatric stroke. Immaturity markedly affects the neuroinflammatory mechanisms of injury, as we showed in a rodent model of neonatal focal stroke and in a similar model in the adult. Furthermore, blood-brain barrier (BBB) integrity is strikingly better preserved in acute neonatal stroke than in adult stroke. While paradoxical, this conclusion is supported by several lines of evidence, including the functional and structural integrity of the BBB and the differential gene and protein expression of an array of BBB proteins. A study showing the disrupted BBB in juvenile rats but not in newborn rats following an intracerebral inflammatory challenge suggested that the susceptibility of the BBB to injury is age- dependent; thus, the response of the BBB to neonatal and pediatric stroke may differ greatly. We hypothesize that the mechanisms of pediatric and neonatal stroke differ in part due to the distinct maturational status of the BBB. To identify the differential BBB response of neonatal and juvenile brain to stroke, we wil focus on developmentaly regulated BBB mechanisms that are "mute" in neonatal rodents but active in juvenile rodents. We wil use our wel-characterized focal stroke models in postnatal day 7 (P7) rats and P9 mice and focal stroke models in juvenile rats and mice to determine if BBB integrity is disturbed after acute pediatric arterial stroke (Aim 1), and if microglia/monocytes differentially affect BBB permeability after neonatal and pediatric stroke (Aim 2). The functional and structural integrity of the BBB will be determined in animals with and without the additional challenge of tight junction integrity after stroke. The relationship between microglial activation and BBB permeability (intravascular tracers) wil be determined by 2-photon imaging of living Cx3cr1GFP/+ neonatal and juvenile mice after stroke. The extent of the involvement of peripheral and brain macrophages in injury and in the disruption of the BBB will be determined in novel Cx3cr1GFP/+/CCR2RFP/+ knock-in mice in both age groups.