Protective mechanisms of ischemic postconditioning

描述(申请人提供)：目前急性中风缺乏有效的治疗方法，因此有必要探索最终可能导致临床应用的创新概念。一种这样的技术是缺血后处理。我们已经证明，快速和延迟缺血后处理都可以减少大鼠的脑梗塞。采用大鼠大脑中动脉远端(MCA)永久性闭塞30min的方法建立卒中动物模型。BCCA的释放允许部分再灌注，这类似于中风患者常见的临床病例。快速后处理在再灌流后即刻进行，延迟后处理在再灌流后5.5小时进行。尽管几个独立的研究小组证实了后处理的保护作用，但其潜在的保护机制尚不清楚。我们有初步数据显示，快速后处理可减弱ROS活性，这表明后处理与ROS减少之间存在相关性。ROS的减少是否真的有助于后处理的保护作用尚不清楚。此外，ROS活性直接导致神经元存活信号通路Akt/PRAS40的功能障碍，Akt功能障碍导致炎症。然而，Akt/PRAS40通路和炎症在缺血后处理保护作用中的作用尚未得到很好的研究。在这项拨款中，我们将首先确定参与后处理保护作用的ROS活动的亚细胞来源。然后，我们将在大鼠和PRAS40基因敲除小鼠中研究ROS减少与Akt/PRAS40活性的关系，这一研究从未在任何研究中使用过。最后，我们将研究Akt/PRAS40如何调节炎症反应，包括它对促炎因子HMGB1和COX-2的影响，以及新的Galectin-9/Tim-3炎症通路。通过这些研究，我们将填补我们对缺血后处理的保护机制和临床翻译方面的知识的重大空白。具体目的1.确定在缺血后处理保护作用中起关键作用的ROS减少的亚细胞调节源。具体目的2.研究抑制ROS能否提高Akt/PRAS40的活性。具体目的3.检测Akt/PRAS40通路对HMGB1和COX-2的促炎反应以及Galectin-9/Tim-3炎症通路的保护作用。 公共卫生相关性：中风后快速和延迟的后处理都可以减少缺血性损害，为中风治疗的研究开辟了一条新的途径，最终可能适用于中风患者。

DESCRIPTION (provided by applicant): The current lack of effective treatments for acute stroke necessitates exploring innovative concepts that may eventually lead to clinical applications. One such technique is ischemic postconditioning. We have demonstrated that both rapid and delayed ischemic postconditioning reduces infarction in rats. Stroke was induced by a 30 min bCCA occlusion plus permanent distal middle cerebral artery (MCA) occlusion. The bCCA release allows partial reperfusion, which mimics the frequent clinical cases that occur in stroke patients. Rapid postconditioning is applied immediately after reperfusion while delayed postconditioning is conducted 5.5 h after reperfusion. Despite confirmation of the protective effects of postconditioning by several independent research groups, the underlying protective mechanisms are not understood. We have preliminary data showing that rapid postconditioning attenuates reactive oxygen species (ROS) activity, suggesting a correlation between postconditioning and ROS reduction. Whether ROS reduction truly contributes to postconditioning's protective effects is not known. In addition, ROS activity directly results in dysfunction of the neuronal survival signaling pathway, Akt/PRAS40 pathway, and Akt dysfunction leads to inflammation. However, the roles of the Akt/PRAS40 pathway and inflammation in the protective effects of ischemic postconditioning have not been well studied. In this grant, we will first identify subcellular sources of ROS activity that are involved in postconditioning's protective effects. We will then study the relationship between ROS reduction and Akt/PRAS40 activity in both rats and PRAS40 knockout mice, which has never been used in any studies. Finally, we will study how Akt/PRAS40 regulates the inflammatory response, including its effects on the pro-inflammatory factors HMGB1 and Cox-2, and the novel galectin-9/Tim-3 inflammatory pathway. Through these studies, we will fill significant gaps in our knowledge about the protective mechanisms and clinical translation of ischemic postconditioning. Specific Aim 1. To identify the subcellular regulatory sources of ROS reduction that play critical roles in the protective effects of ischemic postconditioning. Specific Aim 2. To study whether ROS inhibition improves the Akt/PRAS40 activity. Specific Aim 3. To examine the protective effects of the Akt/PRAS40 pathway on the pro-inflammatory response of HMGB1 and Cox-2, and the galectin-9/Tim-3 inflammatory pathway. PUBLIC HEALTH RELEVANCE: Both rapid and delayed postconditioning after stroke reduce ischemic damage, opening up a new avenue for research in stroke treatment, which may eventually be clinically applicable for stroke patients.