The Role of Interferon-gamma in the Regulation of Hematopoietic Stem Cells

描述（由申请人提供）：候选人：我非常积极，非常有资格在儿科传染病领域从事学术医学事业。我毕业于哈佛大学、圣路易斯华盛顿大学医学科学家培训项目和贝勒医学院（BCM）儿科住院医师项目，在整个学术培训过程中，我一直追求卓越。我的动机是希望改善美国和全世界感染性疾病儿童的医疗保健。我相信，通过研究病原体与宿主免疫反应之间的相互作用，护理领域将取得进展。宿主免疫应答的细胞最终来源于骨髓中的造血干细胞（HSC）。在我的奖学金期间，我利用了麻省理工学院在干细胞生物学领域的机构优势，从事造血干细胞研究。我打算联合收割机结合我以前的经验，在微生物的发病机制与干细胞的研究，研究感染对HSC功能的影响。这项研究将立即应用于从骨髓移植中恢复的患者。此外，这项工作将导致对慢性感染（如严重病毒感染和结核病）导致的骨髓抑制的深入了解和潜在干预措施。研究职业发展计划：我将利用休斯顿的一系列教育和研究资源来加强我的研究职业发展。在生物医学科学的研究生课程中，我将参加癌症生物学和免疫学新研究的课程。我将获得生物统计学，研究行为和道德方面的专业知识，以及显微镜和流式细胞术的最新技术。我将参加传染病、免疫学和干细胞生物学领域的地方、国家和国际会议。我已经与德克萨斯儿童医院的血液肿瘤学家建立了合作关系，并将与他们一起研究感染对人类骨髓样本的影响。除了这些培训活动，我将继续与我的导师玛格丽特·古德尔博士进行富有成效的研究。古德尔博士是一位全国公认的干细胞生物学家，在造血干细胞调控方面具有专业知识。古德尔博士领导着一个非常富有成效的研究小组，她的指导技能也得到了认可，并且是最近更新的T32资助的PI。古德尔博士为我提供了完整的研究工具，空间和科学指导，这将确保我成功地过渡到一个独立的研究生涯。此外，我和我的儿科传染病部门已经投资于我的研究职业发展，保证我100%的保护时间在终身制助理教授的位置在我的奖学金在补助金期间的前两年完成。研究项目：在感染过程中，外周免疫细胞被消耗，必须由祖细胞补充。造血干细胞（HSC）是这些祖细胞中最早的，并且它们在生物体的整个生命中保持多能性和自我更新潜力。令人惊讶的是，人们对HSC如何感知和响应全身感染知之甚少。在这个建议中，我描述了使用慢性鸟分枝杆菌感染的小鼠模型，以了解先天免疫反应引发的HSC功能的变化。我的初步数据表明，造血干细胞在M。禽流感病毒感染，并且该过程依赖于干扰素-3（IFN 3）及其下游效应物Irgm 1（免疫相关GTIgM）。我建议通过进行M.在缺乏IFN 3信号通路组分的小鼠中，包括IFN 3、IFN 3R 1和Stat 1缺陷型小鼠中的禽流感感染。此外，我将确定是否可以单独由IFN 3刺激触发HSC增殖。由于已知干扰素诱导蛋白Irgm 1参与小鼠巨噬细胞的自噬，我们怀疑并证实自噬发生在感染小鼠的HSC中。为了进一步探索这一发现，我们建议研究自噬是否依赖于小鼠HSC中的Irgm 1，以及这个过程是否参与HSC的调控。具体来说，我们将研究自噬是否发生在感染Irgm 1缺陷小鼠的HSC中，我们将确定自噬抑制剂存在下HSC增殖和/或功能是否发生变化。最后，我们将确定干扰素信号传导和自噬是否对从骨髓移植患者中分离的人HSC具有功能意义。这些研究的意义在于，它们将阐明免疫系统在感染期间触发外周免疫细胞库补充的机制。了解感染对造血干细胞的直接和长期影响，对骨髓移植后恢复期患者的治疗有直接意义。此外，这些研究将导致使用干扰素或自噬抑制剂作为再生障碍性贫血和严重病毒和分枝杆菌感染引起的骨髓抑制的治疗药物的关键信息。我的工作和未来的职业生涯将专注于HSC如何应对感染，这是一种基本的生理反应，在疾病状态下可能会异常，被感染性病原体破坏，或被用于治疗目的。

DESCRIPTION (provided by applicant): The Candidate: I am highly motivated and exceptionally qualified to pursue a career in academic medicine in the field of Pediatric Infectious Diseases. A graduate of Harvard University, the Medical Scientist Training Program at Washington University in St. Louis, and the Pediatrics Residency Program at Baylor College of Medicine (BCM), I have pursued excellence throughout my academic training. I am motivated by a desire to improve the medical care of children with infectious diseases, both in the United States and throughout the world. I believe that advances in care will arise from studying the interactions between pathogens and the host immune response. Cells of the host immune response are ultimately derived from hematopoietic stem cells (HSCs) in bone marrow. I have capitalized on the institutional strength of BCM in the field of stem cell biology to pursue hematopoietic stem cell research during my fellowship. I intend to combine my prior experience in microbial pathogenesis with stem cell research to study the effect of infections on HSC function. This research will have immediate application for patients recovering from bone marrow transplantation. Furthermore, this work will lead to insight and potential interventions for myelosuppression as a result of chronic infections such as severe viral infections and tuberculosis. Research Career Development Plan: I will utilize an array of educational and research resources in Houston to strengthen my research career development. Within the BCM graduate programs in biomedical sciences, I will enroll in courses on new research in cancer biology and immunology. I will gain expertise in biostatistics, research conduct and ethics, and state-of-the-art technology in microscopy and flow cytometry. I will participate in local, national, and international meetings in the fields of infectious diseases, immunology, and stem cell biology. I have established a collaboration with hematologist-oncologists at Texas Children's Hospital and will work with them to study the effects of infection on human bone marrow samples. Beyond these training activities, I will continue my highly productive research fellowship with my mentor Dr. Margaret Goodell. Dr. Goodell is a nationally recognized stem cell biologist with expertise in regulation of hematopoietic stem cells. While she directs a very productive research group, Dr. Goodell is also recognized for her mentoring skills and is the PI on a recently renewed T32 grant. Dr. Goodell has provided me the full complement of research tools, space, and scientific guidance that will ensure my success as I transition into an independent research career. Furthermore, BCM and my department of Pediatric Infectious Diseases have invested in my research career development by assuring me 100% protected time in a tenure-track assistant professor position at the completion of my fellowship during the first two years of the grant period. Research Project: During an infection, peripheral immune cells are consumed and must be replenished by progenitor cells. Hematopoietic stem cells (HSCs) are the earliest of these progenitors, and they maintain pluripotency and self-renewal potential throughout the life of an organism. Surprisingly little is known about how HSCs sense and respond to systemic infection. In this proposal, I describe the use of a mouse model of chronic Mycobacterium avium infection to understand changes in HSC function triggered by the innate immune response. My preliminary data suggest that HSCs are activated to proliferate during M. avium infection, and that the process is dependent on interferon-3 (IFN3) and its downstream effector Irgm1 (Immunity-related GTPase M). I propose to delineate the role of IFN3 in the HSC response to infection by conducting M. avium infections in mice lacking components of the IFN3 signaling pathway, including IFN3, IFN3R1, and Stat1- deficient mice. Furthermore, I will determine whether HSC proliferation can be triggered by IFN3 stimulation alone. Since the interferon-inducible protein Irgm1 is known to participate in autophagy in murine macrophages, we suspected and confirmed that autophagy occurs in HSCs of infected mice. To further explore this finding, we propose to investigate whether autophagy is dependent on Irgm1 in murine HSCs, and whether this process participates in HSC regulation. Specifically, we will investigate whether autophagy occurs in HSCs of infected Irgm1-deficient mice, and we will determine if HSC proliferation and/or function change in the presence of inhibitors of autophagy. Finally, we will determine whether interferon signaling and autophagy have functional significance for human HSCs isolated from bone marrow transplant patients. The significance of these studies is that they will elucidate the mechanisms by which the immune system triggers replenishment of the pool of peripheral immune cells during infection. Understanding the immediate and long-term effects of infection on HSCs has direct implications for treatment of patients recovering from bone marrow transplantation. Furthermore, these studies will lead to critical information about use of interferons or inhibitors of autophagy as therapeutic agents for aplastic anemia and myelosuppression due to severe viral and mycobacterial infections. My work and future career will focus on how HSCs respond to infection, a basic physiologic response that can be aberrant in disease states, disrupted by infectious pathogens, or co-opted for therapeutic purposes.