12/15-Lipoxygenase and neurovascular damage following cardiac arrest

描述（由申请人提供）：缺血性脑损伤是导致心力衰竭后致残率和死亡率高的主要因素。心脏骤停导致海马和皮质的选择性细胞死亡，以及血管渗漏和水肿。氧化应激是缺血性脑损伤的主要特征，而12/15-脂氧合酶（12/15-LOX）是其主要介质之一。在本研究中，我们计划研究12/15- LOX在心脏骤停引起的全身缺血后血管损伤和神经元细胞死亡中的作用。我们之前已经确定12/15-LOX是短暂局灶性缺血后延迟神经元细胞死亡和血脑屏障渗漏的主要因素。此外，我们已经阐明了以12/15-LOX为中心的主要细胞死亡途径。在这里，我们将使用心脏骤停和全脑缺血小鼠模型来研究心脏骤停后12/15-LOX表达的增加。我们的中心假设认为，血管和神经元12/15-LOX的增加会引起氧化应激，导致血管渗漏、水肿和神经元死亡，从而加剧脑损伤。初步结果表明：a)心脏骤停复苏小鼠模型中12/15-LOX表达增加；b) 12/15-LOX与氧化应激标志物MDA2和细胞损伤标志物FluoroJade b共定位；C)这些发现可以在全脑缺血模型中复制；d)基因缺失12/15-LOX的小鼠在心脏骤停后损伤减轻。我们拟研究12/15-LOX上调对小鼠全脑缺血模型的影响，具体目的如下：在Aim 1中，我们描述了12/15-LOX在心脏骤停复苏小鼠模型中的表达。除了确定表达12/15-LOX的细胞类型外，我们还将研究氧化应激和细胞损伤的标志物。此外，我们将测量水肿和血管渗漏的水平。在Aim 2中，我们研究了12/15-LOX基因敲除对心脏骤停复苏小鼠模型神经细胞死亡和水肿形成的保护作用。在Aim 3中，我们研究了一种特定抑制剂在药理学上抑制12/15-LOX的保护潜力，并与低温治疗进行了比较。我们将通过行为测试和组织学测量来确定短期和长期的结果。严重的缺血再灌注损伤与心脏骤停和随后的心肺复苏有关。阐明12/15-LOX在缺血性损伤中的作用可能会为治疗心脏骤停患者带来新的治疗选择。

DESCRIPTION (provided by applicant): Ischemic brain damage is a major factor contributing to high rates of both disability and mortality following heart failure. Cardiac arrest leads to selective cell death in both hippocampus and cortex, as well as vascular leakage and edema. Oxidative stress is a major feature of ischemic brain damage, and 12/15-lipoxygenase (12/15-LOX) is one of its main mediators. In this proposal, we plan to investigate the contributions of 12/15- LOX to both vascular damage and neuronal cell death following global ischemia induced by cardiac arrest. We have previously established 12/15-LOX as a major contributor to delayed neuronal cell death and leakage of the blood - brain barrier following transient focal ischemia. In addition, we have elucidated a major cell death pathway centered on 12/15-LOX. Here, we will use mouse models of cardiac arrest and global cerebral ischemia to investigate increased 12/15-LOX expression after cardiac arrest. Our central hypothesis states that increased vascular and neuronal 12/15-LOX exacerbates brain damage by causing oxidative stress, leading to vascular leakage, edema, and the death of neurons. Our preliminary results show that a) expression of 12/15-LOX is increased in a mouse model of cardiac arrest and resuscitation; b) 12/15-LOX co-localizes with MDA2, a marker for oxidative stress, as well as FluoroJade B, a marker for cellular injury; c) these findings can be replicated in a model of global cerebral ischemia; and d) mice in which 12/15-LOX has been genetically deleted show reduced damage after cardiac arrest. We propose to study the consequences of 12/15-LOX up-regulation in mouse models of global ischemia in the following specific aims. In Aim 1, we characterize the expression of 12/15-LOX in a mouse model of cardiac arrest with resuscitation. Besides determining the cell types expressing 12/15-LOX, we will investigate markers of oxidative stress and cellular damage. In addition, we will measure levels of edema and vascular leakage. In Aim 2, we study the protection through 12/15-LOX gene knockout against neural cell death and edema formation in the mouse model of cardiac arrest and resuscitation. In Aim 3, we investigate the protective potential of pharmacologically inhibiting 12/15-LOX with a specific inhibitor, and compare with therapeutic hypothermia treatment. We will determine both short- and long-term outcome, using behavioral tests and histological measures. Severe ischemia and reperfusion injury is associated with cardiac arrest and subsequent cardiopulmonary resuscitation. Elucidating the role of 12/15-LOX in mediating ischemic damage may lead to novel therapeutic options in treating cardiac arrest patients.