Dysregulation of Neuronal Guidance Cue Netrin-1 in Accelerated AAA

简介（由申请人提供）：摘要Bhama Ramkhelawon博士在此奖项中培养了两个职业目标。近期目标是了解巨噬细胞引起的腹主动脉瘤（AAAs）炎症中神经元引导线索Netrin-1的表达，长期职业目标是成为一名能够领导研究的独立研究者，并将Netrin-1作为抑制AAA负担的新靶点的可能作用。AAA的特征是位于主动脉下段的主动脉直径bbb30 mm的局点扩张。每年大约进行25,000次AAA级修复，尽管在初级预防措施方面取得了进展，但在美国，AAA级每年仍导致1,13,000人死亡。以往的组织学研究表明，跨壁炎症表现为单核细胞/巨噬细胞的存在。这种炎症与基质金属蛋白酶（MMPs）通过降解弹性蛋白和胶原蛋白对主动脉壁的蛋白水解破坏有关。大量的研究深入探讨了与血管蛋白样破坏相关的机制。为了更好地理解预防治疗策略，了解广泛的生理病理是至关重要的。由于Mo在炎症的诱导和消退中都有重要的作用，我假设除了将它们募集到主动脉扩张的病灶部位的信号外，其他信号的表达也指向与这些细胞的层压破坏能力相关的高级途径。我们最近证明了神经元引导信号Netrin-1在促进动脉粥样硬化中的关键作用，通过阻断它们对CCL-19等退出信号的趋化性。有趣的是，我的初步数据显示，直接募集Mo的信号（IL-6和TNfa）也可以诱导小鼠和临床人类AAA标本中Netrin-1等保留线索的表达。我们提出了Netrin-1在非脂质环境中协调aaa诱导炎症的另一个创新作用。在这项资助中，我们将使用组织特异性或条件缺失Netrin-1的新型小鼠模型来确定这种引导线索如何改变Mo进入AAA位点的动态调节，并指导它们的极化。在受指导的研究阶段（K99），我将在纽约大学朗格尼医学中心的摩尔博士的指导下完成我正在进行的研究项目。我将在她的实验室获得关于AAA中Mo诱发性炎症的重要方面的专业知识。我将利用研究中心所有可用的设施，进行研究AAA所需的关键实验，从而专攻这一领域。摩尔博士将担任我的主要导师，监督我向独立研究员过渡的各个方面。我们共同制定了一项职业发展计划，其中包括在项目进展、手稿和拨款写作、动物饲养、会议出席方面的指导，以及在负责任的研究行为方面进行培训。此外，一个由四位共同导师组成的团队将为我提供互补的研究指导和帮助，这将大大提高和丰富我的研究技能。导师团队一起承诺指导我扩展我的研究兴趣和方法，并确保成功过渡到一个独立的研究者。在该奖项的独立阶段（R00），我将在AAA小鼠模型中使用纳米颗粒封装siRNA来测试沉默Netrin-1的治疗途径。我们期望通过靶向Netrin-1在体内成功地抑制与血管壁破坏相关的Mo炎症。这些实验将为有希望的手术替代方案提供关键见解，并将朝着应用于治疗AAA的未来药物开发的方向发展。

DESCRIPTION (provided by applicant): Abstract Dr. Bhama Ramkhelawon nourishes 2 career goals during this award. An immediate goal to gain knowledge into the expression of the neuronal guidance cue, Netrin-1 in macrophage-elicited inflammation in Abdominal Aortic Aneurysms (AAAs) and a long-term career goal to become an independent investigator capable of leading research and ascribe a possible role Netrin-1 as a novel target for development of therapies to curb the burden of AAA. AAA is characterized by a focal dilation of the aortic diameter >30 mm located in the infrarenal section of the aorta. Roughly 25,000 AAA repairs are performed each year, and despite progress in primary preventive measures, AAA still accounts for > 13,000 deaths annually in the United States. Previous histological studies have revealed that transmural inflammation is manifested by the presence of monocytes/macrophages. This inflammation is associated with the proteolytic destruction of the aortic wall through the degradation of elastin and collagen by matrix metalloproteinases (MMPs). Numerous studies have profoundly explored the mechanisms related to the proteolitic disruption of the blood vessel. To better appreciate preventive therapeutic strategies, it is crucial to understand the broad spectrum of the physiopathology. Since Mo have important roles in both the induction and resolution of inflammation, I hypothesize that in addition to signals directing their recruitment t the focal site of aortic dilation, other cues are expressed to orient the advanced avenues related to the laminal destructive capacity of these cells. We have recently demonstrated a critical role for the neuronal guidance cue, Netrin-1 in promoting atherosclerosis by blocking their chemotaxis to exit signals such as CCL-19. Interestingly, my preliminary data show that the signals (IL-6 and TNfa) that direct Mo recruitment can also induce the expression of retention cues such as Netrin-1 in both mice and clinical human AAA specimens. We propose another innovative role for Netrin-1 in orchestrating AAA-induced inflammation in a non-lipidemic environment. In this grant, we will use novel mouse models of tissue-specific or conditional deletion of Netrin-1 to determine how this guidance cue alters the dynamic regulation of Mo into AAA sites, and direct their polarization. During the mentored research phase (K99), I will complete my ongoing research projects under Dr. Moore's supervision at New York University Langone Medical Center. I will gain expertise in important aspects of Mo elicited inflammation in AAA in her laboratory. I will take the opportunity of all the facilities available at the research center to perform key experiments required to study AAA and hence specialize myself in this field. Dr. Moore will serve as Primary Mentor and oversee all aspects of my transition to become an Independent Researcher. Together we have elaborated a career development plan, which encompasses guidance in project progress, manuscript and grant writing, animal breeding, congress attendance and to perform training in the responsible conduct of research. In addition, a team of four Co-Mentors will provide me with complementary research guidance and help which will greatly enhance and diversify my research skill set. Together, the team of Mentors has pledged to guide me to extend my research interests and approaches, and to ensure a successful transition to an independent researcher. During the independent phase (R00) of this award, I will test the therapeutic avenues of silencing Netrin-1 by using nanoparticles encapsulating siRNA in the AAA mouse model. We expect to successfully dampen Mo inflammation associated with vessel wall destruction by targeting Netrin-1 in vivo. These experiments will provide key insights into promising surgery alternatives and will head toward translationally applied future drug development to treat AAA.