Blood-brain barrier function after neonatal and pediatric experimental stroke

描述（由申请人提供）：儿科卒中是一个新兴领域。对人类的研究表明，小儿中风不同于新生儿中风，但没有动物模型可以帮助确定小儿中风的机制。正如我们在新生儿局灶性中风啮齿动物模型和成人类似模型中所显示的那样，不成熟明显影响损伤的神经炎症机制。此外，血脑屏障（BBB）的完整性在急性新生儿中风中比在成人中风中得到更好的保护。虽然自相矛盾，这一结论是由几个证据，包括BBB的功能和结构的完整性和差异基因和蛋白质表达的一系列BBB蛋白支持。一项研究显示，在脑内炎症激发后，幼龄大鼠中的BBB被破坏，但新生大鼠中没有，这表明BBB对损伤的易感性是年龄依赖性的;因此，BBB对新生儿和儿科卒中的反应可能有很大差异。我们推测，儿童和新生儿中风的机制不同，部分原因是由于不同的成熟状态的血脑屏障。为了确定新生儿和青少年脑对卒中的不同BBB反应，我们将重点关注发育调节的BBB机制，这些机制在新生儿啮齿动物中是“沉默的”，但在青少年啮齿动物中是活跃的。我们将在出生后第7天（P7）大鼠和P9小鼠中使用我们良好表征的局灶性卒中模型，并在幼年大鼠和小鼠中使用局灶性卒中模型，以确定急性小儿动脉卒中后BBB完整性是否受到干扰（目标1），以及小胶质细胞/单核细胞是否在新生儿和小儿卒中后对BBB通透性产生差异性影响（目标2）。将在卒中后存在和不存在紧密连接完整性的额外挑战的动物中确定BBB的功能和结构完整性。小胶质细胞活化和BBB通透性（血管内示踪剂）之间的关系将通过中风后活的Cx 3cr 1GFP/+新生和幼年小鼠的双光子成像来确定。将在两个年龄组的新型Cx 3cr 1GFP/+/CCR 2 RFP/+敲入小鼠中确定外周和脑巨噬细胞参与损伤和破坏BBB的程度。

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.