Targeting mitochondrial Complex I in neonatal hypoxia-ischemia

项目摘要 新生儿缺氧缺血性脑病(HIE)的特点是一系列旷日持久的 病理生理事件，如果不干预，将是毁灭性的。缺氧缺血性脑病可导致神经发育 延误、癫痫、认知和运动问题，或死亡。现行的婴儿临床护理标准 严重缺氧缺血(HI)的术语是低温。治疗性低温可降低死亡的可能性 并减少一些行为结果指标上的缺陷。然而，神经保护远未完成。这个 这项提议的主要目标是使用成熟的莱斯-万努奇HI啮齿动物模型来开发一种可翻译的 通过靶向线粒体复合体I改善神经保护的策略尽管复合体I的功能是 急性能量衰竭后恢复脑能量代谢所必需的活性氧(ROS) 在恢复期产生的复合体I会导致继发性损伤。细胞凋亡性死亡和 神经炎症也会导致缺氧缺血性脑损伤。目前尚不清楚这些机制是否 依赖于体内复杂的I类改变。我们发表的研究结果表明，临床前药物mdivi-1 抑制复杂的依赖I的ROS的产生，同时仅轻微和可逆地抑制线粒体 呼吸。我们的新数据表明，mdivi-1与复合体I的一个亚基存在直接相互作用。 1显著减少缺氧缺血后3天大鼠重度脑组织丢失的发生，并减少 3-硝基酪氨酸标记，氧化应激的标志，在海马区。从机制上讲，我们发现mdivi-1 与小胶质细胞中的复合体I相互作用，小胶质细胞是介导持续性神经炎的先天免疫细胞 新生儿缺氧缺血性脑病的反应。MDVI-1在体外和体内均显示出抑制小胶质细胞促炎反应的作用。 这项研究的中心假设是mdivi-1将额外增强低温神经保护。 在新生儿缺氧缺血性脑损伤模型中，通过减少复杂的i依赖的氧化应激。我们预测 对雄性和雌性动物都有好处，尽管可能是通过性二态机制。男性和 女性的主要细胞死亡途径不同，男性对慢性小胶质细胞的易感性更高。 HI后激活。一种新的显示神经发育正常的部分复合体I缺乏的小鼠模型 用来确定mdivi-1或低温的神经保护是否被适度减少的 组装复合体I的水平。这种遗传方法也将揭示复合体I功能障碍是否起作用。 对HI诱导的未成熟大脑中的细胞凋亡或神经炎症，无论性别。积极的结果将支持 临床用可逆复合I类抑制剂的开发，希望这类药物可以 最终通过减少新生儿缺氧缺血性脑病的破坏性后果来帮助数百万人。

Project Summary Neonatal hypoxic ischemic encephalopathy (HIE) is characterized by a protracted series of pathophysiological events that, without intervention, are devastating. HIE can result in neurodevelopmental delays, epilepsy, cognitive and motor issues, or death. The current standard of clinical care for infants born at term with severe hypoxia-ischemia (HI) is hypothermia. Therapeutic hypothermia reduces the likelihood of death and lessens deficits in some behavioral outcome measures. However, neuroprotection is far from complete. The major goal of this proposal is to use the well-established Rice-Vannucci HI rodent model to develop a translational strategy for improving neuroprotection by targeting mitochondrial Complex I. Although Complex I function is necessary for the recovery of brain energy metabolism after acute energy failure, reactive oxygen species (ROS) produced by Complex I during the recovery phase contribute to secondary injury. Apoptotic cell death and neuroinflammation also contribute to hypoxic-ischemic brain injury. It is unknown whether these mechanisms depend on Complex I alterations in vivo. Our published findings demonstrate that the preclinical drug mdivi-1 inhibits Complex I-dependent ROS production while only mildly and reversibly inhibiting mitochondrial respiration. Our new data suggest a direct interaction of mdivi-1 with a subunit of Complex I. We find that mdivi- 1 significantly reduces the occurrence of severe rat brain tissue loss measured 3 days after HI and decreases 3-nitrotyrosine labeling, a marker of oxidative stress, in the hippocampus,. Mechanistically, we find that mdivi-1 interacts with Complex I in microglia, the innate immune cells mediating the persistent neuroinflammatory response after neonatal HI. Mdivi-1 shows inhibition of microglial pro-inflammatory responses in vitro and in vivo. The central hypothesis of this study is that mdivi-1 will additively enhance hypothermic neuroprotection in neonatal hypoxic-ischemic brain injury models by reducing Complex I-dependent oxidative stress. We predict benefit in both male and female animals, though through potentially sexually dimorphic mechanisms. Males and females differ in dominant cell death pathways, and males exhibit greater vulnerability to chronic microglial activation after HI. A novel mouse model of partial Complex I deficiency showing normal neurodevelopment will be used to establish whether neuroprotection by mdivi-1 or hypothermia is occluded by a moderate reduction in the level of assembled Complex I. This genetic method will also reveal whether Complex I dysfunction contributes to HI-induced apoptosis or neuroinflammation in the immature brain of either sex. Positive outcomes will support the development of reversible Complex I inhibitors for clinical use, with the hope that this class of drugs may ultimately help millions by reducing the devastating consequences of neonatal hypoxic ischemic encephalopathy.