Intraventricular Hemorrhage Disrupts the Blood Brain Barrier in Premature Infants

摘要 脑室内出血（IVH）仍然是早产儿的主要神经系统并发症， 脑瘫脑积水和认知缺陷没有有效的治疗方法来预防这些疾病， 婴儿IVH IVH触发脑室周围生殖基质和邻近白色物质的炎症， 导致少突胶质细胞祖细胞（OPC）的成熟停滞和髓鞘形成失败。此外，委员会认为， CSF产生增加，同时CSF流动受阻，导致脑积水。IVH- 诱导的损伤可破坏血脑屏障（BBB）和血-CSF屏障的完整性和功能 (BCB)，允许骨髓细胞浸润大脑，并从其中渗出液体，从而使 IVH的后果1-磷酸鞘氨醇（S1 P）是一种脂质介质，是血脑屏障和血脑屏障的关键调节因子 功能S1 P结合并刺激G蛋白偶联受体（S1 PR 1至S1 PR 5）。S1 PR 1贡献 血管成熟，调节粘附和紧密连接的组装和功能，并限制 免疫细胞穿过血脑屏障相反，S1 PR 2促进免疫应答，增加BBB通透性， 并促进白细胞进入大脑。因此，组成型表达的S1 PR 1拮抗S1 PR 2， 通常在病理条件下在BBB中诱导。S1 PR 1激活和S1 PR 2抑制均提供 脑损伤模型中的神经保护作用。然而，S1 PR 1和S1 PR 2在BBB和BCB损伤中的作用， 脑积水和白色损害的发生率尚不清楚。我们的中心假设是：i）IVH 将诱导炎症，破坏BBB和BCB，并改变BBB中S1 PR 1和S1 PR 2的表达， 人和兔中的BCB和ii）受体亚型-BCB对S1 PR 1和S1 PR 2信号传导的调节 特异性试剂将恢复BBB和BCB的完整性，使脑炎症最小化，并逆转白色物质 IVH早产兔脑损伤及脑积水。我们将在一个兔子模型中测试这些假设， 甘油诱导的IVH和来自人类早产儿的尸检样品。在目标1中，我们将确定 IVH对a）BB B和BCB渗透性以及穿过BB B和BCB的免疫细胞浸润的影响，B） 内皮紧密连接和粘附连接、内皮转胞吞作用和关键转运蛋白，以及c）转录 脑室周围脑区和脉络丛毛细血管内皮的变化。的意见 将在患有和不患有IVH的早产儿的尸检样本中验证兔中制备的疫苗。在目标2和3中， 我们将评估S1 PR 1和S1 PR 2调节对a）BBB和BCB渗透性、内皮细胞紧密性、内皮细胞粘附性和内皮细胞粘附性的影响。 和粘附连接组装，内皮转胞吞和转录组，B）免疫细胞浸润， 脑室扩大，和c）髓鞘形成和神经行为。我们还将确定S1 PR 1和S1 PR 2是否 信号通过sonic hedgehog和Rho-ROCK影响粘附和紧密连接以及髓鞘形成 路，分别。这些研究将增强我们对成熟大脑中S1 P生物学的理解， 加速开发新的治疗方法，以尽量减少IVH幸存者的白色损伤和脑积水。

Abstract Intraventricular hemorrhage (IVH) remains a major neurological complication of prematurity that results in cerebral palsy, hydrocephalus, and cognitive deficits. No effective therapy exists to prevent these disorders in infants with IVH. IVH triggers inflammation in the periventricular germinal matrix and adjacent white matter, resulting in maturational arrest of oligodendrocyte progenitor cells (OPCs) and myelination failure. Moreover, there is increased CSF production and concurrent obstruction in CSF flow, which leads to hydrocephalus. IVH- induced injury may disrupt the integrity and function of the blood brain barrier (BBB) and blood-CSF barrier (BCB), allowing myeloid cells to infiltrate the brain, and fluids to exude from it, thus worsening the consequences of IVH. Sphingosine 1 phosphate (S1P) is a lipid mediator and a key regulator of BBB and BCB function. S1P binds and stimulates G-protein coupled receptors (S1PR1 through S1PR5). S1PR1 contributes to vessel maturation, regulates adherens and tight junction assembly and function, and limits trafficking of immune cells across the BBB. In contrast, S1PR2 promotes immune responses, increases BBB permeability, and facilitates leukocyte entry into the brain. Thus, constitutively-expressed S1PR1 antagonizes S1PR2, which is often induced under pathological conditions in the BBB. Both S1PR1 activation and S1PR2 inhibition offer neuroprotection in brain injury models. However, the role of S1PR1 and S1PR2 in BBB and BCB damage, hydrocephalus, and white matter injury is unclear in neonates with IVH. Our central hypotheses are: i) IVH will induce inflammation, disrupt the BBB and BCB, and alter S1PR1 and S1PR2 expressions in the BBB and BCB in both humans and rabbits and ii) modulation of S1PR1 and S1PR2 signaling by receptor subtype- specific agents will restore BBB and BCB integrity, minimize cerebral inflammation, and reverse white matter injury and hydrocephalus in preterm rabbits with IVH. We will test these hypotheses in a rabbit model of glycerol-induced IVH and autopsy samples from human premature infants. In Aim 1, we will determine the effect of IVH on a) BBB and BCB permeability and immune cell infiltration across the BBB and BCB, b) endothelial tight and adherens junction, endothelial transcytosis, and key transporters, and c) transcriptional changes in the capillary endothelium of the periventricular brain region and choroid plexus. The observations made in rabbit will be validated in autopsy samples from preterm infants with and without IVH. In Aim 2 and 3, we will evaluate the effect of S1PR1 and S1PR2 modulation on a) BBB and BCB permeability, endothelial tight and adherens junction assembly, endothelial transcytosis and transcriptome, b) immune cell infiltration, ventriculomegaly, and c) myelination and neurobehavior. We will also determine whether S1PR1 and S1PR2 signaling affect adherens and tight junction as well as myelination via sonic hedgehog and Rho-ROCK pathways, respectively. These studies will enhance our understanding of S1P biology in the maturing brain and hasten development of new therapies to minimize white matter injury and hydrocephalus in survivors of IVH.