Harness Germinal Matrix Hemorrhage

描述（由申请人提供）：生发基质出血（GMH）被定义为室管膜下脑组织内未成熟血管破裂。新生儿先天性流产是早产儿死亡和发病的主要原因，发生率约为每1 000例新生儿中3.5例。GMH的衰弱后果包括出血性脑积水的形成，导致脑萎缩和神经损伤。脑积水形成的一个主要原因是凝血酶，一种由颅内出血激活的凝血因子。凝血酶引发炎症反应、胶质形成和细胞外基质（ECM）蛋白的过量产生，从而阻塞脑室系统并损害脑脊液引流。凝血酶通过激活G蛋白偶联受体亚家族参与疤痕组织的增殖，称为蛋白酶激活受体（PARs）。一旦受到刺激，PARs会激活mTOR，据报道，mTOR会诱导ECM蛋白过量产生，从而导致脑脊液阻塞和引流受损。我们的第一个推论假设是，通过阻断PARs及其下游靶点，GMH后脑积水将减少。凝血酶还会导致脑室周围和脑室内血栓的形成，从而机械地损害脑脊液的循环和吸收，从而导致GMH后脑积水的形成。我们的第二个推论假设是，通过巨噬细胞激活来增强血凝块的溶解和清除，将有效地减少脑积水和随之而来的神经功能障碍。我们将实施过氧化物酶体增殖物激活受体γ (PPAR- γ)的药理激活，据报道，PPAR- γ可以增加红细胞的小胶质吞噬，从而减少残留的凝块大小。根据现有的成人脑出血文献和我们自己在实验性GMH后的初步观察，我们建议表征GMH诱导的脑损伤程度，并提供新的非侵入性治疗策略。我们的中心假设是，在新生儿GMH大鼠模型中，靶向凝血酶下游效应物（PARs和mTOR）和血栓清除（通过PPAR-?）将减少GMH诱导的脑积水并改善长期神经功能。我们将评估PARs和PPAR-？目的1将在一种新型GMH大鼠模型中研究凝血酶和凝块形成在出血性脑积水中的作用。我们假设GMH血凝块会损害脑脊液循环，凝血酶活性的增加会促进细胞外基质增殖，导致正常脑脊液动力学紊乱，导致脑积水和长期神经功能障碍的发展。目的2将确定凝血酶下游效应物（PARs和mTOR）在GMH诱导的脑积水中的作用。我们假设凝血酶激活PARs会通过mTOR激活导致细胞外基质蛋白过量产生，从而阻碍脑脊液引流并诱发脑积水。PAR抑制将减少细胞外基质增殖和脑积水。目的3将确定PPAR-？在GMH后血栓清除我们假设PPAR-？激活会激活小胶质细胞吞噬红细胞，从而减少血块和脑积水。本提案的长期目标是为GMH患者提供非侵入性治疗方法。

DESCRIPTION (provided by applicant): Germinal matrix hemorrhage (GMH) is defined as the rupture of immature blood vessels within the subependymal brain tissue. Occurring in approximately 3.5 per 1,000 births, GMH presents a leading cause of mortality and morbidity in premature infants. Debilitating consequences of GMH include the formation of post- hemorrhagic hydrocephalus, leading to brain atrophy and neurological impairments. A major causative factor of hydrocephalus formation is thrombin, a coagulation factor, activated by the intracranial bleed. Thrombin initiates inflammatory responses, gliosis and overproduction of extracellular matrix (ECM) proteins, which obstruct the cerebroventricular system and impair CSF drainage. Thrombin participates in the proliferation of scar tissue by activating a subfamily of G protein-coupled receptors, named proteinase-activated-receptors (PARs). Once stimulated, PARs will activate mTOR, which has been reported to induce overproduction of ECM proteins, thus resulting in obstruction and impaired CSF drainage. Our first corollary hypothesis is that by blocking PARs and their downstream targets, hydrocephalus will be reduced after GMH. Thrombin will also lead to the formation of peri- and intraventricular blood clots, which mechanically impair the circulation and absorption of CSF, thus leading to hydrocephalus formation after GMH. Our second corollary hypothesis is that enhancing blood clot resolution and clearance, via macrophage activation, will effectively reduce hydrocephalus and consequent neurological deficits after GMH. We will implement pharmacological activation of peroxisome proliferator-activated receptor gamma (PPAR-?), which has been reported to increase microglial phagocytosis of red blood cells, thus decreasing residual clot sizes. From existing literature on adult intracerebral hemorrhage and from our own preliminary observations after experimental GMH, we propose to characterize the extent of GMH-induced brain injury and provide novel non- invasive therapeutic strategies. Our central hypothesis is that targeting thrombin downstream effectors (PARs & mTOR) and clot clearance (via PPAR-?) will reduce GMH-induced hydrocephalus and improve long term neurological function in this neonatal GMH rat model. We will evaluate the implication of PARs and PPAR-? with respect to GMH pathology and therapy in the following aims: Aim 1 will investigate the role of thrombin and clot formation in post-hemorrhagic hydrocephalus in a novel GMH rat model. We hypothesize that GMH blood clots will impair the CSF circulation and an increase of thrombin activity will promote extracellular matrix proliferation, leading to disturbances in normal CSF dynamics and the development of hydrocephalus and long-term neurological deficits. Aim 2 will determine the role of thrombin downstream effectors (PARs & mTOR) in GMH induced hydrocephalus. We hypothesize that the activation of PARs by thrombin will cause the overproduction of extracellular matrix proteins, via mTOR activation, thus obstructing CSF drainage and inducing hydrocephalus. PAR inhibition will reduce extracellular matrix proliferation and hydrocephalus. Aim 3 will determine the role of PPAR-? in clot clearance after GMH. We hypothesize that PPAR-? activation will activate microglial phagocytosis of red blood cells, hence reducing blood clots and hydrocephalus. The long-term goals of this proposal are to provide non-invasive therapeutic approaches for GMH patients.