mtDNA DAMPS: a pharmacologic target in multi-organ system failure

 描述(由申请人提供)：通过K08机制进行研究培训的申请来自一名创伤外科医生和重症护理专家，他已经担任了三年的助理教授。他现在提出了一个多维度的培训计划，旨在开启他作为一名基础和转化型外科医生兼科学家的学术生涯，并专注于创伤和重症监护医学中最普遍的问题之一，特别是多器官系统衰竭(MOSF)。培训计划--实际位于高度跨学科和资金充足的肺生物学中心，是该地区唯一的一级 1创伤中心-旨在为应聘者提供(1)核心知识和实验室技能，(2)研究方法和生物统计学方面的最新专业知识，以及(3)科学写作、演讲和学术领导技能。将结合教学课程、明智地出席现场和非现场研讨会和会议以及密集的实验室经验来实现这些目标。拟议的研究计划的动机是在MOF患者的护理方面存在两个明显的差距。首先，尽管部分由于复苏和支持性护理的进步，严重创伤的结果有所改善，但多脏器功能衰竭仍然是一个严重的临床问题，因为预防或逆转该综合征的药物策略尚未开发出来。其次，虽然线粒体和生物能功能障碍长期以来一直与严重损伤的反应有关，但整合细胞对全身炎症反应的关键哨兵分子(S)存在于这些线粒体和生物能异常中的前景以前从未被考虑过。因此，候选人的研究培训计划将测试线粒体DNA(MtDNA)作为管理MOF有害细胞反应的分子哨兵这一新概念。多条证据汇聚在这一观点上。线粒体基因组比核DNA对氧化损伤更敏感，这一观察结果的重要性因MOF光谱中的氧和氮(RS)活性物种的参与而得到强调。此外，使用转基因策略或新型平台药物对mtDNA修复效率的调节协调地决定了氧化剂或细菌挑战的培养细胞、分离的器官和完整动物的存活和功能。最具挑衅性的是，最近的证据表明mtDNA是MOF的细胞间介质。损伤后释放到循环中的线粒体基因组片段--称为线粒体DNA损伤相关分子模式(DAMPS)--可能通过TLR介导的炎症细胞和驻留细胞的激活，将损伤从损伤的初始位置传播到远处的器官(19)。由于线粒体DNA损伤处置的分子决定因素完全未被探索，拟议的研究将检验翻译上有意义的假设，即在严重创伤中，线粒体基因组的氧化碱基损伤导致线粒体DNA损伤导致血浆中线粒体DNA损伤，从而导致MOF的演变。对严重创伤患者、人类外周血单个核细胞(PBMCs)以及多器官功能衰竭啮齿动物模型的研究将：(1)确定严重创伤患者血浆mtDNA潮湿水平与多器官功能衰竭指数之间的关系；(2)检验人外周血单核细胞中氧化剂介导的线粒体DNA损伤和线粒体DNA修复动力学分别与线粒体DNA潮湿释放到细胞外环境呈正和负相关的假说；(3)确定在铜绿假单胞菌诱导的脓毒症大鼠模型中，新型平台药物是否能增加mtDNA修复和增强mtDNA潮湿降解，从而预防和逆转MOSF。总而言之，这项研究将提供第一个观察性证据，将血浆mtDNA抑制与严重受伤患者的脆弱人群中MOF的演变联系起来。然而，它最具创新性和重大贡献的是，通过提供概念证明，增强mtDNA修复和加速mtDNA湿降解的策略抑制了mtDNA湿积聚和器官衰竭的传播，从而确定了用于MOF的药物干预的孤立靶点。据信，在本培训计划结束时，候选人将处于有利地位，可以启动关于控制严重创伤中mtDNA DAMP介导的MOF的策略的第一批临床试验。此外，候选人将启动一项独立的实验室研究计划，其目标将是在分子水平上定义新的药理靶点，以控制创伤和其他疾病中线粒体DNA的潮湿处置，这些细胞间和细胞内介质在这些疾病中发挥致病作用。

 DESCRIPTION (provided by applicant): This application for research training via the K08 mechanism originates from a trauma surgeon and critical care specialist that has been an assistant professor for three years. He now proposes a multi-dimensional training program intended to launch his academic career as a basic and translational surgeon-scientist and focused on one of the most pervasive problems in trauma and critical care medicine, specifically, multiple organ system failure (MOSF). The training program - physically located in the highly interdisciplinary and well-funded Center for Lung Biology and in the region's only level 1 Trauma Center - is intended to provide the candidate with (1) core knowledge and laboratory skills, (2) state-of-the-art expertise in research methods and biostatistics, and (3) scientific writing, presentation, and academic leadership skills. A combination of didactic courses, judicious attendance at on-site and off-site seminars and meetings, and intense laboratory experiences will be utilized to achieve these goals. The proposed research plan is motivated by two striking gaps in the care of patients with MOSF. First, although outcomes of severe injury have improved partly as a consequence of advances in resuscitation and supportive care, MOSF remains a serious clinical problem because pharmacologic strategies to prevent or reverse the syndrome have yet to be developed. Second, while mitochondrial and bioenergetic dysfunction have long been incriminated in the response to severe injury, the prospect that key sentinel molecule(s) integrating cellular responses to systemic inflammation reside in these mitochondrial and bioenergetic abnormalities has not previously been considered. Accordingly, the candidate's research training plan will test the novel concept that mitochondrial DNA (mtDNA) acts as a molecular sentinel governing deleterious cell responses in MOSF. Multiple lines of evidence converge on this idea. The mitochondrial genome is far more sensitive to oxidative damage than nuclear DNA, an observation whose significance is underscored by involvement of reactive species of oxygen and nitrogen (RS) across the spectrum of MOSF. Further, modulation of mtDNA repair efficiency using transgenic strategies or novel platform drugs coordinately dictate survival and function in oxidant or bacteria-challenged cultured cells, isolated organs, and intact animals. Most provocatively, recent evidence incriminates mtDNA as an intercellular mediator of MOSF. Fragments of the mitochondrial genome released into the circulation after injury - termed mtDNA Damage Associated Molecular Patterns (DAMPs) - may serve to propagate damage from the initial site of injury to distant organs through TLR-mediated activation of inflammatory and resident cells (19). Because molecular determinants of mtDNA DAMP disposition are entirely unexplored, the proposed research will test the translationally-significant hypothesis that in severe trauma, oxidative base damage to the mitochondrial genome causes plasma accumulation of mtDNA DAMPs resulting in the evolution of MOSF. Studies in severely injured human patients, human peripheral blood mononuclear cells (PBMCs), and in a rodent model of MOSF will: (1) Define relationships between plasma mtDNA DAMP levels and indices of MOSF in patients with severe trauma; (2) Test the hypothesis in human PBMCs that oxidant- mediated mtDNA damage and mtDNA repair kinetics are positively and negatively, respectively, associated with mtDNA DAMP release into the extracellular environment; and, (3) Determine if increased mtDNA repair and enhanced mtDNA DAMP degradation with novel platform drugs, prevents and reverses MOSF In a rat model of Pseudomonas aeruginosa-induced sepsis. Collectively, this research will provide the first observational evidence linking plasma mtDNA DAMPs to the evolution of MOSF in a vulnerable population of severely injured patients. However, its most innovative and significant contributions relate to the identification of isolated targets for pharmacologic intervention in MOSF by providing proof-of-concept that strategies to augment mtDNA repair and accelerate mtDNA DAMP degradation suppress mtDNA DAMP accumulation and propagation of organ failure. It is believed that at the end of this training program, the candidate will be well positined to launch the first clinical trials on strategies to control mtDNA DAMP- mediated MOSF in severe injury. In addition, the candidate will inaugurate an independent laboratory research program whose goal will be define at a molecular level novel pharmacologic targets to govern mtDNA DAMP disposition in trauma and other disorders for which these inter- and intracellular mediators play pathogenic role.