Intraventricular Hemorrhage Disrupts the Blood Brain Barrier in Premature Infants

摘要 脑室出血(IVH)仍然是早产儿的主要神经系统并发症，导致 脑性瘫痪、脑积水和认知缺陷。目前还没有有效的治疗方法来预防这些疾病 患有IVH的婴儿。IVH引发脑室周围生发基质和邻近白质的炎症， 导致少突胶质细胞前体细胞(OPC)成熟停滞和髓鞘形成失败。此外， 脑脊液产生增加，同时脑脊液流动受阻，导致脑积水。IVH- 诱发性损伤可能会破坏血脑屏障(BBB)和血-脑脊液屏障的完整性和功能 (BCB)，允许髓系细胞渗透到大脑中，并从其中渗出液体，从而使病情恶化 IVH的后果。1-磷酸鞘氨醇(S1P)是一种脂质介质，也是血脑屏障和血脑屏障的关键调节因子 功能。S1P结合并刺激G蛋白偶联受体(S1PR1至S1PR5)。S1PR1贡献 对血管的成熟，调节粘连和紧密连接的组装和功能，并限制贩运 血脑屏障上的免疫细胞。相反，S1PR2促进免疫反应，增加血脑屏障通透性， 并促进白细胞进入大脑。因此，结构性表达的S1PR1拮抗S1PR2，后者 常在血脑屏障的病理条件下诱发。S1PR1激活和S1PR2抑制都提供 脑损伤模型中的神经保护。然而，S1PR1和S1PR2在BBB和BCB损伤中的作用， 脑积水和脑白质损伤在IVH新生儿中尚不清楚。我们的中心假设是：i)IVH 会诱导炎症，扰乱BBB和BCB，改变BBB和BCB中S1PR1和S1PR2的表达 人和兔的BCB和II)受体亚型对S1PR1和S1PR2信号的调制- 特定的药物将恢复血脑屏障和血脑屏障的完整性，最大限度地减少脑部炎症，并逆转脑白质 IVH早产兔脑损伤与脑积水我们将在兔模型中检验这些假设。 甘油诱发的IVH和人类早产儿的尸检样本。在目标1中，我们将确定 IVH对血脑屏障和血脑屏障通透性及免疫细胞跨血脑屏障和血脑屏障渗透的影响 内皮紧密和粘连连接，内皮细胞转运和关键转运蛋白，以及c)转录 脑室周围脑区和脉络丛毛细血管内皮细胞的变化。观察到的 兔制造的将在有和没有IVH的早产儿的尸检样本中得到验证。在目标2和3中， 我们将评估S1PR1和S1PR2调节对a)BBB和BCB通透性、内皮紧密性的影响 并附着连接组装，内皮细胞跨细胞和转录组，b)免疫细胞浸润， 脑室增大，以及c)髓鞘形成和神经行为。我们还将确定S1PR1和S1PR2是否 信号通过Sonic Hedgehog和Rho-Rock影响黏附和紧密连接以及髓鞘形成 分别是路径。这些研究将加强我们对成熟大脑中S1P生物学的理解 加快开发新的治疗方法，以最大限度地减少IVH幸存者的脑白质损伤和脑积水。

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.