Remote ischemic conditioning mitigates diffuse traumatic brain injury via specialized pro-resolving mediators

项目摘要 笨拙的身体姿势会导致手臂或腿“睡着”。一旦重新定位，血液就会回流到 四肢，神经在失去氧气和电解液后自发恢复功能。在睡梦中， 缺血肢体内的细胞和分子过程可能产生生物活性的恢复和再生 在再灌流时静脉释放的化合物。故意、间歇性限制的方法 流向肢体的血流被称为远程缺血调节(RIC)，它可以通过简单且成本低廉的方式实现- 在肢体上有效地使用止血带，在预定的时间内持续几个周期。RIC可以保护 脑和其他器官免受缺血、手术和创伤事件的影响，无论是在给药之前还是之后 这件事。事实上，我们的团队已经证明RIC减少了创伤性脑损伤的生物标记物。 损伤(TBI)患者。在临床前心脏骤停和脑缺血中，RIC保留了组织病理学和 使用损伤前或损伤后RIC，改善功能结局。到目前为止，水稻的基本机制 疗效尚不清楚，人们提出了十几种相互矛盾的机制。颅脑损伤和其他后天神经系统疾病 损伤具有相同的继发性损伤过程，包括炎症和氧化应激，这些过程一直是 神经保护策略的重复靶点。我们提出了一类源于脂肪酸的内源性脂质， 作为RIC疗效的分子机制，被称为特殊的前分解介体(SPM)。SPM， 包括分解素、脂氧素和保护素的分子家族，在此之后从脂双层中释放 缺血，积极消炎，在弥漫性脑损伤中具有神经保护作用，假定生物稳定性为 通过血液向大脑和脂质结构传递血脑屏障的通透性。在这项提案中，我们 实验性弥漫性脑损伤后RIC保护神经功能的假设 SPM，它可以减轻损伤引起的炎症。为了检验这一假设，我们将RIC序列应用于 成年小鼠后肢，先用中线液压冲击伤造成弥漫性脑损伤，然后再用水冲击致伤。目标1 将评估RIC序列在保留神经、认知和情感功能方面的效果 伤后21天时间疗程。目标2，使用目标1中确定的最有效的RIC序列，将 证明RIC可以减弱小胶质细胞的激活，作为炎症的指标，并产生SPM作为 用液相色谱-串联质谱法和商业酶联免疫吸附试验测定血浆中的。 这些目标的结果将确定改善弥漫性神经预后所必需的RIC序列 TBI。进一步，我们探索SPM的产生作为靶向小胶质细胞激活的分子机制。 需要直接证据来支持RIC作为一种治疗方法来治疗估计为1.7的 在美国发生的百万TBI。最终，RIC可以作为一种成本效益高且可行的治疗方法。 用于提供内源性修复和修复化合物，如SPM，以改善创伤性脑损伤的预后。

Project Summary Awkward body positions lead to an arm or leg ‘falling asleep.’ Upon repositioning, blood rushes back into the limb, with nerves spontaneously regaining function after being deprived of oxygen and electrolytes. While asleep, cellular and molecular processes within the ischemic limb may produce bioactive restorative and regenerative compounds that are released intravenously upon reperfusion. The method of intentional, intermittent restriction of blood flow to a limb is called Remote Ischemic Conditioning (RIC), which can be achieved by simple and cost- effective application of a tourniquet to a limb for several cycles of pre-determined duration. RIC can protect the brain and other organs from ischemic, surgical, and traumatic events, whether administered prior to or following the event. In fact, our team has demonstrated that RIC reduced biomarkers of acute damage in traumatic brain injury (TBI) patients. In pre-clinical cardiac arrest and cerebral ischemia, RIC preserves histopathology and improves functional outcome, using either pre-injury or post-injury RIC. To date, the mechanisms underlying RIC efficacy are unknown, with a dozen conflicting mechanisms proposed. TBI and other acquired neurological injuries share secondary injury processes, including inflammation and oxidative stress, which have been repeated targets of neuroprotective strategies. We propose a class of endogenous lipids derived from fatty acids, called Specialized Pro-Resolving Mediators (SPMs), as the molecular mechanism for RIC efficacy. SPMs, including the molecular families of resolvins, lipoxins, and protectins, are released from lipid bilayers after ischemia, actively resolve inflammation, and are neuroprotective in diffuse TBI, with the assumed biostability to travel in blood to the brain and the lipid structure for blood-brain barrier permeability. In this proposal, we hypothesize that RIC preserves neurological function following experimental diffuse TBI by producing SPMs, which mitigate injury-induced inflammation. To test the hypothesis, we apply RIC sequences to the hind limb of adult mice, first before and then after diffuse TBI induced by midline fluid percussion injury. Aim 1 will evaluate the efficacy of RIC sequences on preserving neurological, cognitive, and affective function over a 21 day time course post-injury. Aim 2, using the most effective sequence of RIC identified in Aim 1, will demonstrate that RIC attenuates microglial activation as an index of inflammation and produces SPMs as measured in plasma by liquid chromatography-coupled tandem mass spectrometry and commercial ELISA. Results from these aims will identify the RIC sequence necessary to improve neurological outcome from diffuse TBI. Further, we explore the production of SPMs as the molecular mechanism that targets microglial activation. Direct evidence is necessary to support the efficacy of RIC as a therapeutic approach to treat the estimated 1.7 million TBIs that occur in the United States. Ultimately, RIC could serve as a cost-effective and feasible therapy for delivering endogenous restorative and reparative compounds, such as SPMs, to improve outcome from TBI.