Age induced enteric neural stem cell loss through Foxo3 dependent inflammation

描述（由申请人提供）：K08奖的申请描述了一个多学科的5年培训计划，以促进Laren Becker博士作为一名独立的学术医师和科学家的职业发展。该候选人是医学博士，2009年加入斯坦福大学胃肠病学系，现在寻求建立他的研究经验，以实现他的长期职业目标，成为一名独立研究者，指导神经胃肠病学和衰老的研究项目。该K08奖将为贝克尔博士提供必要的支持和保护时间，以完成以下培训目标：(1)成为神经胃肠病学、免疫学和衰老学方面的专家；(2)精通免疫学研究，包括掌握免疫表型和骨髓嵌合体的创造等技术；(3)掌握学术生涯所需的重要技能，包括科学写作和口头报告；(4)在第四年提交R01申请。为了实现这些目标，这位候选人组建了一个由胃肠道免疫学、衰老学和神经胃肠病学专家组成的强大指导团队，他们都曾成功地指导过年轻科学家。贝克尔博士的职业发展计划包括与他的导师和咨询委员会的定期会议、教学以及参加当地和国际会议。斯坦福大学是一所世界级的大学，在免疫学、干细胞和衰老研究方面具有特别的优势，是发展候选人学术生涯的理想环境。研究衰老会引起胃肠道功能的生理变化，从而导致许多与年龄相关的疾病。这些疾病的病因可能是多因素的，但肠神经系统（ENS）神经元的丢失和变性可能起作用。提出的研究是基于发现与年龄相关的认知能力下降可能是由于与中枢神经系统炎症相关的神经干细胞的损失。虽然尚不清楚肠内神经干细胞（ENSCs）的减少是否会导致肠内神经元随着年龄的增长而丧失，但ENSCs参与神经发生的发现支持了这一解释。有趣的是，Foxo3，一种与人类寿命相关的转录因子，最近被发现在炎症性疾病中发挥作用，包括克罗恩病和类风湿性关节炎。树突状细胞（dc）中Foxo3信号的缺失可增加IL-6的产生并引发炎症。根据初步数据发现，随着年龄的增长，ENS微环境中Foxo3表达下降，促炎细胞因子上升。我们假设，衰老增加炎症是由于dc中Foxo3信号的减少，从而通过功能性ensc的下降导致与年龄相关的ENS干扰。这个假设可以通过两种方式来解决。首先，我们将研究Foxo3在年龄依赖性ENSCs丢失中的作用。具体来说，候选人将评估是否1)dc中Foxo3的表达随着年龄的增长而下降，2)Foxo3缺乏导致ensc和肠神经元的过早丢失，以及3)免疫细胞中Foxo3缺乏（尤其是ensc）的缺失。其次，将研究年龄依赖性的Foxo3炎症调节如何影响ensc。具体来说，候选人将评估1)衰老是否会导致ENS微环境中的促炎细胞因子和免疫细胞增加，Foxo3缺乏是否会增加这些炎症变化，2)阻断促炎细胞因子IL-6是否会提高培养中ENSCs的存活率，以及3)在体内给药IL-6是否会提高ENSCs的存活率

DESCRIPTION (provided by applicant): This application for a K08 award describes a multidisciplinary 5-year training program to facilitate Dr. Laren Becker's career development as an independent academic physician-scientist. The candidate is a MD, PhD who joined the Gastroenterology Department at Stanford in 2009 and now seeks to build on his research experience to attain his long-term career goal of becoming an independent investigator, directing a research program in neurogastroenterology and aging. This K08 award will provide Dr. Becker with the support and protected time necessary to accomplish the following training objectives: (1) to become an expert in neurogastroenterology, immunology and aging, (2) to become proficient in immunology research including mastering techniques such as immunophenotyping and creation of bone marrow chimeras, (3) to acquire skills important for an academic career including scientific writing and oral presentation, and (4) to submit an R01 application during year 4. To achieve these goals, the candidate has assembled a strong mentoring team of experts in GI immunology, aging and neurogastroenterology-all of whom have successfully mentored young scientists. Dr. Becker's career development plan includes regular meetings with his mentors and advisory committee, didactics, and attendance at local and international meetings. Stanford, a world-class institution with particular strength in immunology, stem cell and aging research, is the ideal environment for developing the candidate's academic career. Research Aging causes physiologic changes in gastrointestinal intestinal function that contribute to many age-related disorders. The etiology of these disorders is likely multifactorial, but loss and degeneration of neurons in the enteric nervous system (ENS) likely plays a role. The proposed studies are predicated on the finding that age- associated cognitive decline is likely due to loss of neural stem cells related to central nervous system inflammation. While unknown whether a decline in enteric neural stem cells (ENSCs) contributes to loss of enteric neurons with aging, the discovery that ENSCs are involved in neurogenesis supports this interpretation. Interestingly, Foxo3, a transcription factors linked to longevity in humans was recently found to play a role in inflammatory disorders including Crohn's disease and Rheumatoid arthritis. Loss of Foxo3 signaling in dendritic cells (DCs) was found to increase IL-6 production and drive inflammation. Based on preliminary data which found both a decline in Foxo3 expression and rise in proinflammatory cytokines in the ENS microenvironment with aging, it is posited that aging increases inflammation due to reduction in Foxo3 signaling in DCs which in turn causes age-related ENS disturbances via a decline in functional ENSCs. This hypothesis will be addressed in two ways. First, the role of Foxo3 in age-dependent loss of ENSCs will be examined. Specifically, the candidate will assess whether 1) Foxo3 expression in DCs declines with aging, 2) Foxo3 deficiency leads to premature loss of ENSCs and enteric neurons, and 3) Foxo3 deficiency in immune cells in particular is responsible for loss in the ENS. Second, how age-dependent Foxo3 modulation of inflammation impacts ENSCs will be examined. Specifically, the candidate will evaluate whether 1) aging causes increased proinflammatory cytokines and immune cells in the ENS microenvironment and Foxo3 deficiency augments these inflammatory changes, 2) blocking the proinflammatory cytokine IL-6 will improve survival of ENSCs in culture, and 3) administration of IL-6 in vivo will inhibit neurogenesis. Successful completion of the proposed sudies will offer valuable new insights regarding the mechanism of age- related changes of the ENS. Additionally, it will provide proof of principle that immunomodulatory therapies have a role in age-associated gastrointestinal disorders. This proposal will serve as a platform for Dr. Becker to acquire additional training in GI immunology and aging, crucial to developing a research niche in neurogastroenterology. Additionally, this research will provide the foundation for future studies as an independent investigator including evaluating whether targeting inflammation via blockade of IL-6 in vivo can reverse age-related changes to the ENS, whether aging-induced inflammation plays a similar role in humans, and ultimately whether immunomodulatory therapies may serve as therapy for aging associated GI disorders.