Targeting Sphingosine to Treat Brain Injury

 描述（由申请人提供）： 创伤性脑损伤（TBI）是我国士兵伤亡的重要原因，使他们中的许多人严重运动残疾和认知障碍。目前还没有针对脑创伤的药物干预措施，主要是因为脑损伤的分子和细胞机制尚不清楚。我们目前对TBI发病机制的理解表明，兴奋性毒性、氧化应激、炎症事件和线粒体功能障碍之间在细胞水平上存在动态相互作用，这种相互作用发生在数天、数周和数月内。令人信服的证据表明，线粒体损伤在决定结果中起着至关重要的作用，因为线粒体参与调节氧化应激，炎症反应和细胞死亡。拟议的研究旨在确定线粒体损伤的机制，重点是毒性鞘脂鞘氨醇作为脑创伤后线粒体功能障碍的原因的新作用。我们的初步和已发表的研究表明，TBI引起线粒体鞘氨醇的持续上调，这可能会影响许多线粒体功能，导致原发性损伤后持续的线粒体功能障碍。拟议研究的长期目标是开发一种基于减弱TBI后鞘氨醇依赖性脑损伤的神经保护策略。我们建议的中心假设是TBI诱导的鞘氨醇在线粒体中的积累导致线粒体功能障碍，导致神经细胞损伤和继发性脑损伤。我们计划通过追求2个具体目标来验证我们的假设：1）确定中性神经酰胺酶介导的线粒体鞘氨醇产生和脑损伤的机制; 2）确定酸性鞘磷脂酶依赖的线粒体鞘氨醇积累和脑损伤的机制。Fingolimod是FDA批准的用于治疗多发性硬化症的药物，Reclast是FDA批准的用于治疗骨质疏松症的药物，将用于抑制鞘氨醇产生，减少脑损伤并在TBI后保留脑功能。我们将使用多学科和综合的方法，结合体外和体内研究，在小鼠模型TBI与现代药理学，生物化学和生物能量学方法。一种强大的、最先进的方法，串联质谱法，将用于评估鞘脂产生酶的活性和鞘脂谱的精确测量。拟议的研究将帮助我们破译新的鞘氨醇介导的TBI机制，并将导致有效的治疗策略的发展，以保护大脑免受二次损伤，改善脑功能恢复与TBI退伍军人。

 DESCRIPTION (provided by applicant): Traumatic brain injury (TBI) accounts for a significant number of casualties sustained by our soldiers, leaving many of them with substantial motor disabilities and cognitive impairments. There are no pharmacological interventions for brain trauma, mainly because the molecular and cellular mechanisms comprising brain injury remain unclear. Our current understanding of the pathogenesis of TBI suggests a dynamic interplay at the cellular level between excitotoxicity, oxidative stress, inflammatory events, and mitochondrial dysfunction, which occurs over days, weeks and months. Compelling evidence suggests that mitochondrial damage plays a crucial and central role in determining the outcome, since mitochondria are involved in regulating oxidative stress, inflammatory response, and cell death. The proposed studies are aimed at determining the mechanisms of mitochondrial damage focusing on a novel role of a toxic sphingolipid, sphingosine, as a cause of mitochondrial dysfunction following brain trauma. Our preliminary and published studies suggest that TBI provokes continued up-regulation of mitochondrial sphingosine, which could impact a number of mitochondrial functions, leading to persisting mitochondrial dysfunction after the primary insult. The long-term goal of the proposed studies is to develop a neuroprotective strategy based on attenuating sphingosine-dependent brain impairment after TBI. The central hypothesis of our proposal is that TBI-induced accumulation of sphingosine in mitochondria results in mitochondrial dysfunction, leading to neural cell injury and secondary brain damage. We plan to test our hypothesis by pursuing 2 specific aims: 1) Determine the mechanisms of the neutral ceramidase-mediated mitochondrial sphingosine generation and brain injury; 2) Determine the mechanisms of the acid sphingomyelinase-dependent mitochondrial sphingosine accumulation and brain injury. Fingolimod, an FDA- approved drug for treatment of multiple sclerosis, and Reclast, an FDA-approved drug for treatment of osteoporosis, will be utilized to inhibit sphingosine generation, reducing brain damage and preserving the brain function after TBI. We will use a multi-disciplinary and integrative approach, combining in vitro and in vivo studies in a mouse model of TBI with modern pharmacological, biochemical and bioenergetics methodologies. A powerful, state-of-the-art methodology, tandem mass spectrometry, will be utilized for assessment of sphingolipid- producing enzyme activities and precise measurement of the sphingolipid profile. The proposed studies will help us decipher novel sphingosine-mediated mechanisms of TBI and will lead to the development of effective therapeutic strategies to protect the brain from secondary injury, improving brain function recovery for Veterans with TBI.