Mitochondrial DNA Damage and Inflammasome Activation in Vascular Inflammation

描述（由申请人提供）：动脉粥样硬化性心脏病是美国死亡的主要原因。慢性炎症是这一过程的关键组成部分，控制炎症可能会产生新的治疗方法。最近的研究表明，il -1 β是慢性炎症（包括血管炎和动脉粥样硬化）的关键炎症细胞因子，目前正在进行临床试验，以中和2型糖尿病和动脉粥样硬化中的il -1 β。先前的研究表明，il -1 β和细胞凋亡在斑块进展中起关键作用，但这两个过程之间没有机制联系，il -1 β被激活的确切机制目前尚不清楚。我们最近发现了NLRP3炎性体激活il -1 β产生的难以捉摸的机制，并将细胞凋亡和线粒体（Mt）氧化DNA损伤与这一途径联系起来。我们发现，诱导Mt功能障碍和Mt中的ROS的危险信号导致受损（氧化）的mtDNA被释放到细胞质中，在那里它结合并激活NLRP3炎症小体，活性il -1 β的产生机制。基于这些最近的开创性发现，本探索性R21提案的主要目标是研究mtDNA损伤在细胞凋亡和诱导il -1 β中的作用，因为它与血管炎症和动脉粥样硬化有关，以便找到新的更有效的方法来预防和治疗这种疾病。我们将操纵线粒体DNA修复系统，以研究其作为一种新的治疗策略的潜力，该策略将阻止il -1 β（以及IL-18-另一种nlrp3依赖性细胞因子）的激活，而不是当前的策略，即在il -1 β已经释放并导致下游激活后中和il -1 β。基于这些关键发现，我们提出以下两个目标，围绕中心假设，即血管炎症期间发生的氧化mtDNA损伤激活NLRP3炎症小体产生il -1 β，并在动脉粥样硬化中起促炎作用。抑制DNA氧化损伤可阻止NLRP3炎性体的激活，减少血管炎症和动脉粥样硬化。特异性目的1-利用缺乏DNA损伤修复基因Ogg1的小鼠，在饮食诱导的高胆固醇小鼠动脉粥样硬化模型中，确定线粒体DNA损伤在NLRP3炎性体激活过程中的作用。目的2：研究通过合成8-OH-dG阻断线粒体DNA诱导的NLRP3激活的治疗作用，并确定通过Ogg1基因转移增强Mt DNA修复的作用。

DESCRIPTION (provided by applicant): Atherosclerotic heart disease is the leading cause of death in the USA. Chronic inflammation is a key component of this process and manipulation of inflammation may yield novel treatments. Recent studies have highlighted IL-1beta, as a key inflammatory cytokine in chronic inflammation, including vasculitis and atherosclerosis, and clinical trials are underway to neutralize IL-1beta in type 2 diabetes and atherosclerosis. Previous studies showed a key role of IL-1beta and apoptosis in plaque progression, but no mechanistic connections were drawn between these two processes and the exact mechanism by which IL-1beta is activated was not known until now. We have recently discovered the elusive mechanism of NLRP3 inflammasome activation for IL-1beta production, and linked apoptosis and mitochondrial (Mt) oxidative DNA damage to this pathway. We showed that danger signals that induce Mt dysfunction and ROS in the Mt, result in damaged (oxidized) mtDNA that is released into the cytosol where it binds to and activates the NLRP3 inflammasome, the machinery by which active IL-1beta is made. Based on these recent seminal findings, the main goal of this exploratory R21 proposal is to investigate the role of mtDNA damage during apoptosis and induction of IL-1beta as it relates to vascular inflammation and atherosclerosis in order to find novel and more efficient ways to prevent and treat this disease. We will manipulate the mitochondrial DNA repair system to investigate its potential as a new treatment strategy that would prevent the activation of IL-1beta (as well as IL-18- the other NLRP3-dependent cytokine), as opposed to current strategies to neutralize IL-1beta after it is already released and led to downstream activation. Based upon these key findings, we propose the following two Aims focused around the central hypothesis that oxidative mtDNA damage that occurs during vascular inflammation activates the NLRP3 inflammasome for IL-1beta production and plays a proinflammatory role in atherogenesis. Inhibition of oxidative DNA damage will prevent NLRP3 inflammasome activation and result in decreased vascular inflammation and atherosclerosis. Specific AIM 1- To define the role of mitochondrial DNA damage during NLRP3 inflammasome activation in a diet-induced hypercholesterolemic mouse models of atherosclerosis using mice deficient in the DNA damage repair gene Ogg1.AIM 2- To investigate the therapeutic role of blocking mitochondrial DNA induced NLRP3 activation by synthetic 8-OH-dG administration and to determine the role of augmenting the Mt DNA repair with Ogg1 gene transfer.