Therapeutic Strategies for Neonatal Hypoxic-Ischemiic Encephalopathy

 描述(申请人提供)：尽管近几十年来婴儿死亡率总体上有所改善，但出生窒息的发病率基本保持不变，并对社会造成重大负担。对于遭受缺氧缺血性脑损伤的新生儿，在出生后6小时内诱导低温是一种被接受的治疗方法，但它仍然没有得到充分利用 全世界。此外，在接受治疗的许多人中，神经和认知障碍一直持续到童年后期。因此，迫切需要找到其他单独使用或与低温联合使用的治疗方法。在一个与足月新生儿脑损伤相似的新生儿HI动物模型中，我们在初步实验中发现，在HI损伤后注射自然产生的化学保护剂萝卜硫素或合成三萜类CDDO-EA提供了比以前在该模型中测试的其他十种候选药物更强大的神经保护作用。值得注意的是，这种保护作用超过了在HI后3-4小时的临床相关延迟开始低温时观察到的保护作用。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Nrf2易位到细胞核，在那里它与多相抗氧化剂和防御酶基因启动子上的抗氧化反应元件结合。NRF2激活剂是新生儿缺氧缺血性脑病有吸引力的神经保护候选者，因为它们在上调抗氧化系统网络和下调炎症反应方面具有多项功能。在目标1中，我们将在新生动物身上测试不同剂量的萝卜硫素和CDDO-EA。使用具有最佳神经保护的剂量和药物，我们通过对脆弱的感觉运动皮质、壳核、感觉丘脑和海马CA3区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。我们还将评估神经缺陷和认知功能。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，男性和女性具有强大的神经保护作用。神经保护与行为改善有关。在目标2中，我们将研究Nrf2激活剂在新生儿大脑复氧的背景下，刺激Nrf2核转位和上调抗氧化酶的能力，这些酶对谷胱甘肽的合成及其抗氧化活性至关重要。此外，我们将确定该药物在多大程度上减轻谷胱甘肽的耗竭，谷胱甘肽是新生儿缺氧缺血性脑病的关键抗氧化剂，以及治疗是否削弱氧化应激标志和减少神经炎症。由于未成熟大脑中的神经元以不同形式的程序性坏死和凋亡以区域特有的方式死亡，我们将研究Nrf2激活剂是否改善特定形式的细胞死亡信号。由于治疗性低温正在成为护理的标准，在目标3中，我们将测试Nrf2激活剂是否增强了低温的疗效。根据STAIR和RIGOR指南，从这些详细的临床前研究中获得的数据有望成为可能将Nrf2激动剂转化为新生儿HI的唯一治疗方法或作为降温辅助治疗的基础。

 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.