Mitochondrial DNA Damage and Inflammasome Activation in Vascular Inflammation

描述(申请人提供)：动脉粥样硬化性心脏病是美国主要的死亡原因。慢性炎症是这一过程的关键组成部分，对炎症的操纵可能会产生新的治疗方法。最近的研究强调，IL-1β是包括血管炎和动脉粥样硬化在内的慢性炎症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-1β。以往的研究表明IL-1β和细胞凋亡在斑块进展中起着关键作用，但这两个过程之间没有机制联系，IL-1β被激活的确切机制到目前为止还不清楚。我们最近发现了NLRP3炎性小体激活产生IL-1β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，危险信号导致线粒体功能障碍和线粒体中的ROS，导致受损(氧化)的线粒体DNA释放到胞浆中，在那里它与NLRP3炎症体结合并激活NLRP3炎症体，炎症小体是产生活性IL-1β的机制。基于这些最新的开创性发现，这个探索性的R21方案的主要目标是研究线粒体DNA损伤在细胞凋亡和IL-1β诱导中的作用，因为它与血管炎症和动脉粥样硬化有关，以找到预防和治疗这种疾病的新的、更有效的方法。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，以防止IL-1β(以及IL-18-另一种依赖NLRP3的细胞因子)的激活，而不是目前的策略，即在IL-1β已经释放并导致下游激活后中和IL-1β。基于这些关键发现，我们围绕以下中心假设提出了以下两个目标：血管炎症过程中发生的氧化mtDNA损伤激活NLRP3炎症体产生IL-1β，并在动脉粥样硬化形成中发挥促炎作用。抑制DNA氧化损伤将阻止NLRP3炎症体的激活，从而减少血管炎症和动脉粥样硬化。目的1-利用DNA损伤修复基因Ogg1缺失的小鼠建立高胆固醇饮食诱导的动脉粥样硬化模型，明确线粒体DNA损伤在NLRP3炎性小体激活过程中的作用。

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.