Targeting mitochondrial Complex I in neonatal hypoxia-ischemia

项目摘要 新生儿缺氧缺血性脑病（HIE）的特点是一系列长期的， 病理生理事件，如果不干预，是毁灭性的。新生儿缺氧缺血性脑病可导致神经发育障碍 延迟、癫痫、认知和运动问题或死亡。目前对出生在以下年龄段的婴儿的临床护理标准 严重缺氧缺血（HI）术语是体温过低。治疗性低温降低了死亡的可能性 并减少某些行为结果测量的缺陷。然而，神经保护还远未完成。的 该提案的主要目标是使用完善的Rice-Vannucci HI啮齿动物模型来开发翻译的 通过靶向线粒体复合物I改善神经保护的策略。虽然复合体I的功能是 急性能量衰竭后脑能量代谢恢复所必需的活性氧（ROS） 复合物I在恢复阶段产生的蛋白质的释放导致继发性损伤。细胞凋亡和 神经炎症也有助于缺氧缺血性脑损伤。目前尚不清楚这些机制是否 取决于体内复合体I的改变。我们发表的研究结果表明，临床前药物mdivi-1 抑制复合物I依赖的ROS产生，同时仅轻度和可逆地抑制线粒体 呼吸我们的新数据表明mdivi-1与复合物I的亚基直接相互作用。我们发现姆迪维- 1显著降低HI后3天测量的严重大鼠脑组织损失的发生，并降低 3-硝基酪氨酸标记，氧化应激的标志物，在海马，。从机制上讲，我们发现MDIV 1 与小胶质细胞中的复合物I相互作用，小胶质细胞是介导持续性神经炎性细胞毒性的先天免疫细胞。 新生儿HI后的反应。Mdivi-1在体外和体内显示出对小胶质细胞促炎反应的抑制。 本研究的中心假设是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合物I依赖的氧化应激。我们预测 在雄性和雌性动物中都有益处，尽管是通过潜在的性二型机制。雄性和 女性在主要的细胞死亡途径上不同，男性对慢性小胶质细胞表现出更大的脆弱性。 HI后激活。一种显示正常神经发育的部分复合物I缺乏的新型小鼠模型将 用于确定MDIVI-1或低温的神经保护作用是否被MDIVI-1的适度降低所阻断。 组装的复合体I的水平。这种遗传学方法也将揭示复合体I功能障碍是否有助于 HI诱导的细胞凋亡或神经炎症在任何性别的未成熟的大脑。积极成果将支持 开发用于临床的可逆复合物I抑制剂，希望这类药物可以 通过减少新生儿缺氧缺血性脑病的破坏性后果，最终帮助数百万人。

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.