Therapeutic Strategies for Neonatal Hypoxic-Ischemiic Encephalopathy

 描述（由申请人提供）：尽管近几十年来婴儿死亡率总体有所改善，但出生窒息的发病率基本保持不变，并给社会造成重大负担。在出生后6小时内诱导低温是新生儿缺氧缺血性脑损伤的公认治疗方法，但仍未得到充分利用 国际吧此外，在许多接受治疗的人中，神经和认知障碍持续到儿童晚期。因此，迫切需要找到单独使用或与低温一起使用的其他疗法。在一个新生儿HI动物模型，结果在脑损伤中观察到的足月新生儿相似，我们发现在初步实验中，注射天然存在的化学保护剂萝卜硫素或合成的三萜类化合物CDDO-EA HI损伤后提供了更强大的神经保护比其他十个候选药物以前在这个模型中测试。值得注意的是，这种保护超过了在HI后3-4小时的临床相关延迟时开始低温时观察到的保护。在中风和脑创伤的成人模型中，萝卜硫素和CDDO-EA导致转录因子Nrf 2易位到细胞核，在那里它结合到多个II期抗氧化剂和防御酶的基因启动子上的抗氧化反应元件。Nrf 2激活剂是新生儿HI的有吸引力的神经保护候选物，因为它们在上调抗氧化系统网络和下调炎症反应中具有多能作用。在目标1中，我们将在新生动物中测试各种剂量的莱菔硫烷和CDDO-EA。使用具有最佳神经保护作用的剂量和药物，我们通过对脆弱的感觉运动皮层、壳核、感觉丘脑和海马CA 3区中存活神经元的详细体视学分析，评估了神经保护的广泛治疗窗口。我们还将评估神经功能缺损和认知功能。到目前为止，初步数据表明，当在HI后5分钟或1小时给予激活剂时，雄性和雌性动物具有强大的神经保护作用。神经保护与行为改善相关。在目标2中，我们将研究Nrf 2激活剂的能力，在新生儿大脑的复氧设置，刺激核转位的Nrf 2和上调抗氧化酶的谷胱甘肽的合成和其抗氧化活性是至关重要的。此外，我们将确定药物减弱谷胱甘肽耗竭（新生儿HI中的一种关键抗氧化剂）的程度，以及治疗是否钝化氧化应激标志物并减少神经炎症。由于未成熟脑中的神经元以区域特异性方式通过不同形式的程序性坏死和凋亡死亡，我们将研究Nrf 2激活剂是否改善特定形式的细胞死亡信号传导。由于治疗性低温正在成为护理标准，在目标3中，我们将测试Nrf 2激活剂是否增加低温的疗效。根据STAIR和RIGOR指南，从这些详细的临床前研究中获得的数据预计将成为Nrf 2激活剂作为新生儿HI的唯一治疗或辅助治疗的基础。

 DESCRIPTION (provided by applicant): Despite overall improvements in infant mortality in recent decades, morbidity from birth asphyxia remains largely unchanged and causes a significant burden to society. Inducing hypothermia within 6 hours of birth is an accepted treatment for neonates that suffer hypoxic-ischemic (HI) brain injury, but it remains underutilized worldwide. Moreover, neurologic and cognitive disabilities persist into late childhood in many of those treated. Thus, a critical need persists to find other therapies to be used alone or with hypothermia. In a neonatal animal model of HI that results in cerebral injury similar to that observed in term newborns, we found in preliminary experiments that injection of the naturally occurring chemoprotectant sulforaphane or the synthetic triterpenoid CDDO-EA after HI injury provided more robust neuroprotection than ten other candidate drugs previously tested in this model. Remarkably, this protection exceeded that observed when hypothermia was initiated at a clinically relevant delay of 3-4 hours after HI. In adult models of stroke and brain trauma, sulforaphane and CDDO-EA cause translocation of the transcription factor Nrf2 to the nucleus, where it binds to the antioxidant response element on promoters of genes of multiple Phase II antioxidant and defense enzymes. Nrf2 activators are attractive neuroprotective candidates for neonatal HI because of their multipotent action in upregulating a network of antioxidant systems and downregulating the inflammatory response. In Aim 1, we will test various doses of sulforaphane and CDDO-EA in neonatal animals. Using the dose and drug with optimal neuroprotection, we assess a broad therapeutic window for neuroprotection with a detailed stereologic analysis of surviving neurons in the vulnerable sensorimotor cortex, putamen, sensory thalamus, and hippocampal CA3 regions. We will also assess neurologic deficits and cognitive function. Thus far, preliminary data indicate robust neuroprotection in males and females when the activators are administered 5 min or 1 h after HI. The neuroprotection is associated with behavioral improvements. In Aim 2, we will examine the ability of Nrf2 activators, in the setting of reoxygenation of the neonatal brain, to stimulate nuclear translocation of Nrf2 and to upregulate antioxidant enzymes that are critical for glutathione synthesis and its antioxidant activity. Furthermore, we will determine the degree to which the drug attenuates glutathione depletion, a critical antioxidant in neonatal HI, and whether treatment blunts markers of oxidative stress and reduces neuroinflammation. Because neurons in immature brain die by different forms of programmed necrosis and apoptosis in a region-specific manner, we will investigate whether Nrf2 activators ameliorate specific forms of cell death signaling. Because therapeutic hypothermia is becoming the standard of care, in Aim 3 we will test whether Nrf2 activators augment the efficacy of hypothermia. Data obtained from these detailed preclinical studies in accordance with the STAIR and RIGOR guidelines are expected to form the basis for possible translation of Nrf2 activators as a sole therapeutic or as an adjunct therapy to hypothermia for neonatal HI.