Identification of biomarkers for biochemical, pathophysiological and neurological effects of high ammonia concentration on the central nervous system in a preclinical model of neonatal hyperammonemia

在新生儿高氨血症临床前模型中鉴定高氨浓度对中枢神经系统生化、病理生理学和神经学影响的生物标志物

• 批准号: 10302593
• 负责人: Nicholas Ah Mew
• 金额: $ 26.78万
• 依托单位: CHILDREN'S RESEARCH INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-18 至 2023-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10302593
• 关键词: Acute; Adult; Affect; Ammonia; Animal Model; Animals; Argininosuccinate lyase deficiency; Astrocytes; Biochemical; Biological Markers; Biotinidase Deficiency; Blood; Brain; Brain Edema; Brain Injuries; Cells; Cessation of life; Chemicals; Chronology; Citrulline; Citrullinemia; Coma; Complement; Cultured Cells; Data; Development; Disease; Electroencephalography; Epilepsy; Exposure to; Frequencies; Functional disorder; Glutamates; Glutamine; Goals; Holocarboxylase Synthetase Deficiency; Human; Hyperammonemia; Hyperargininemia; Hypoxia; Impairment; Infant; Intellectual functioning disability; Knock-out; Knockout Mice; Lead; Ligase; Liver; Long-Term Effects; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Maple Syrup Urine Disease; Measures; Metabolism; Methods; Modeling; Molecular; Monitor; Mus; N acetyl L glutamate; N-carbamylglutamate; Neonatal; Neonatal Brain Injury; Neuraxis; Neurocognitive Deficit; Neurologic; Neurologic Effect; Neuron-Specific Enolase; Newborn Animals; Organ; Ornithine Carbamoyltransferase; Outcome; Patient-Focused Outcomes; Patients; Pattern; Pharmaceutical Preparations; Pharmacotherapy; Phenotype; Pre-Clinical Model; Preclinical Testing; Protons; Recovery; Resources; Risk; Seizures; Serum; Severities; Signal Transduction; Stress; Supplementation; Symptoms; Testing; Toxic effect; Transplant Recipients; United States Health Resources and Services Administration; Validation; Water; Withdrawal; Zebrafish; awake; base; biomarker identification; brain abnormalities; brain electrical activity; drug testing; experience; experimental study; fatty acid oxidation; imaging study; improved outcome; injury recovery; insight; liver transplantation; mature animal; neonatal brain; neonatal mice; neonate; neuroprotection; neurotoxicity; novel; novel therapeutics; postnatal; preclinical evaluation; prevent; research clinical testing; screening panel; therapeutically effective; two photon microscopy

Abstract Neonatal hyperammonemia (HA) from any cause, including several screenable disorders, results in brain injury leading to irreversible intellectual and developmental disabilities, and even death. Current therapies for HA are targeted at reducing blood ammonia levels; although they can prevent death from brain edema, they are inefficient at reducing or preventing brain damage. Our understanding of the mechanism of ammonia toxicity to the brain is based on experiments in cultured cells and adult animal models; HA disrupts glutamine, glutamate, and K+ metabolism in the astrocytes leading to osmotic stress and brain edema. However, it is not known how HA affects the developing brain because animal models suitable for studying molecular, biochemical, pathophysiological, and neurological effects of HA on the neonatal brain currently do not exist. We have created an animal model of inducible HA, the N-acetylglutamate synthase knockout (NAGSko) mouse. Homozygous knockout mice survive into adulthood and reproduces when treated with N-carbamylglutamate and citrulline, and develop HA when treatment is stopped. We propose to use the NAGSko mice as a model of inducible neonatal HA. Our goal is to establish biomarkers of HA that could be used in both preclinical and clinical testing of neuroprotection drugs. Our specific aims are: 1. To induce HA in neonatal NAGSko mice and determine whether associated MRS biochemical changes in their brains persist after ureagenesis has been normalized. We will induce HA in NAGSko mice at postnatal day 13 (P13) and measure metabolite differences in the brains of HA NAGSko mice and non-HA littermates during HA episode and 2 weeks post recovery from HA. Brain metabolites will be measured using proton magnetic resonance spectroscopy (1H-MRS). 2. To determine whether neonatal HA episode causes persistent abnormal astrocyte function that correlates with blood biomarkers of brain damage. We will use our novel NAGSko/ALDH1L1/GCamp5G-tdTm mice and 2-photon microscopy to monitor changes in Ca2+ signaling during neonatal HA episode and its long-term consequences on astrocytic Ca2+ signaling in awake animals, Changes in Ca2+ signaling will be correlated to serum biomarkers of brain injury S100B and NSE (neuron-specific enolase). 3. To determine whether neonatal HA episode causes persistent abnormal brain electrical activity. We will assess whether a neonatal HA episode increases frequency and severity of seizures after normalization of ureagenesis in the NAGSko mice. After validation, we plan to use EEG patterns, 1H-MRS and blood biomarkers of brain damage as biomarkers of HA in pre-clinical and clinical evaluation of drugs and therapies for the protection of the brain from ammonia toxicity. If successful, drugs that result from these trials will complement current treatment approaches and improve the outcome of patients with HA.

抽象的 来自任何原因的新生儿高症（HA），包括几种可筛选的疾病，导致脑损伤 导致不可逆转的智力和发展障碍，甚至导致死亡。 HA的当前疗法是 针对降低血液氨水的针对性；尽管它们可以防止大脑水肿死亡，但它们是 减少或预防脑损伤时效率低下。我们对氨毒性机理的理解 大脑基于培养细胞和成年动物模型的实验。 HA破坏谷氨酰胺，谷氨酸， 星形胶质细胞中的K+代谢导致渗透胁迫和脑水肿。但是，尚不知道如何 HA会影响发展中的大脑，因为动物模型适合研究分子，生化， HA目前不存在HA对新生儿大脑的病理生理和神经系统作用。我们有 创建了一种可诱导HA的动物模型，即N-乙酰谷氨酸合酶基因敲除（Nagsko）小鼠。 纯合子敲除小鼠在成年后生存，并在用N-核谷氨酸和 瓜氨酸，并在停止治疗时发展HA。我们建议将Nagsko小鼠用作 可诱导的新生儿HA。我们的目标是建立可以在临床前和临床上使用的HA的生物标志物 神经保护药物的测试。我们的具体目的是：1。在新生儿纳格斯科小鼠中诱导HA并确定 尿素发生后，相关的生物化学夫人是否持续存在。 我们将在产后第13天（P13）诱导Nagsko小鼠的HA，并测量大脑的代谢物差异 HA Nagsko小鼠和非HA同窝仔，HA发作后2周从HA中恢复。脑 代谢物将使用质子磁共振光谱（1H-MR）测量。 2。确定 新生儿HA发作是否引起与血液相关的持续异常星形胶质细胞功能 脑损伤的生物标志物。我们将使用我们的新颖Nagsko/aldh1l1/gcamp5g-tdtm小鼠和2 photon 显微镜检查新生儿HA发作期间Ca2+信号传导的变化及其长期后果 在清醒动物中的星形细胞Ca2+信号传导上，Ca2+信号的变化将与血清生物标志物相关 脑损伤S100B和NSE（神经元特异性烯醇酶）。 3。确定新生儿HA发作是否导致 持续异常的脑电活动。我们将评估新生儿HA发作是否增加频率 Nagsko小鼠尿素发生归一化后癫痫发作的严重程度。验证后，我们计划使用 EEG模式，1H-MR和脑损伤的血液标志物作为HA的生物标志物在临床前和临床中 评估药物和疗法以保护大脑免受氨毒性的保护。如果成功，毒品 这些试验的结果将补充当前治疗方法，并改善 HA的患者。