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残疾率和死亡率高的主要因素。心脏骤停会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，12/15-脂氧合酶（12/15-LOX）是其主要介质之一。在这个提议中，我们计划调查12/15- LOX对心脏骤停诱导的全脑缺血后血管损伤和神经细胞死亡的贡献。我们先前已经确定12/15-LOX是短暂局灶性缺血后迟发性神经元细胞死亡和血脑屏障渗漏的主要贡献者。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，我们将使用小鼠心脏骤停和全脑缺血模型来研究心脏骤停后12/15-LOX表达的增加。我们的中心假设指出，增加的血管和神经元12/15-LOX通过引起氧化应激，导致血管渗漏、水肿和神经元死亡而加剧脑损伤。我们的初步结果表明：a）12/15-LOX的表达在心脏骤停和复苏的小鼠模型中增加; B）12/15-LOX与MDA 2（氧化应激的标志物）以及FluoroJade B（细胞损伤的标志物）共定位; c）这些发现可以在全脑缺血模型中复制;和d）其中12/15-LOX已被遗传删除的小鼠在心脏骤停后显示出降低的损伤。我们建议在以下具体目标中研究小鼠全脑缺血模型中12/15-LOX上调的后果。在目的1中，我们表征了12/15-LOX在复苏的心脏骤停小鼠模型中的表达。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。目的二：研究12/15-LOX基因敲除对小鼠心脏骤停复苏后神经细胞死亡和水肿形成的保护作用。在目的3中，我们研究了用特异性抑制剂抑制12/15-LOX的抗氧化剂的保护潜力，并与治疗性低温治疗进行比较。我们将使用行为测试和组织学测量来确定短期和长期结果。严重的缺血和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在介导缺血性损伤中的作用可能导致治疗心脏骤停患者的新的治疗选择。

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.