Bone Marrow Functions of Novel Pro-Resolving Mediators

摘要 造血干细胞和祖细胞(HSPC)是一种罕见的自我更新骨髓(BM) 能够在生物体的整个生命周期内产生所有成熟血细胞的细胞。在成人中，静止的HSPC 居住在低氧骨髓生态位(1-4%O2生理性低氧)内，并能够快速进入 细胞周期和分化，以产生白细胞，以应对入侵的病原体。导师的实验室 发现炎症的消退是由新的介体和时间的产生控制的 阐明了专门化的促分解介体(SPM)，这是一个包括脂氧素(LX)在内的海龙类超家族， 溶血素(RV)、保护素(PD)和松脂素(MAR)。SPM生物合成的结构和功能 在导师的实验室建立，并得到其他人的确认。SPM是亚纳摩尔的，具有立体选择性 促进微生物清除和遏制的激动剂，同时通过加速宿主提高宿主存活率 解决机制。这项建议是基于正在进行的工作的新发现；我们利用国家- 最先进的代谢脂组学分析，生理性低氧下HSPC中的一个特定的SPM簇，包括 分解素D1(RvD1)、分解素D4(RvD4)、分解素E1(RvE1)、树脂素1(MaR1)和脂氧素B4(LXB4)。另外， 我们最近在健康人的骨髓中发现了一种新的SPM，Resolvin E4(RvE4)。体验到的纸巾 生理缺氧区，如BM，具有大量的SPM，其机制不明。因此，我们 建议严格检验以下假设：在生理性低氧中，专业前分解 BM产生的介体(SPM)对HSPC反应的从头开始和/或期间的调节至关重要 侵袭远端部位的感染，以及维持骨髓内环境的稳定。以下是目标 利用最先进的组学平台，如代谢组学(LC-MS/MS)、质量细胞学 (CyTOF)和单细胞RNA测序(sc-RNA-seq)在小鼠和人HSPC中：1)确定影响 生理缺氧对BM生态位(K99)内源新SPM产生的影响；2)建立调控机制 HSPC的分化和对SPM簇感染的反应，特别是RvD1、RvD4、MaR1和 新奇RvE4(K99/R00)。K99指导阶段将在布里格姆妇女医院和哈佛大学举行 在两位国际公认的科学家查尔斯·N·瑟汉教授的指导下， SPM结构及其功能的领头人和莱昂纳多·宗教授 造血术。一个科学委员会/合作者将进一步为Libreros博士提供建议，该委员会/合作者将涵盖不同的 研究提案的方方面面：马修·韦斯特博士、马克·佩雷拉博士和大卫·斯卡登教授。目标是 这项建议的目的是为申请者提供全面的科学和职业发展计划，包括 过渡到独立教师职位所需的技能(R00)。这些研究的结果将会产生 从根本上对SPM的功能和HSPC生物学中的新的前解析途径有了新的见解。 这些发现可以帮助开发血液系统疾病的新疗法，并提供基本的 了解在感染期间骨髓如何支持解决方案。

Abstract Hematopoietic stem cells and progenitors (HSPCs) are a rare population of self-renewing bone marrow (BM) cells that can generate all mature lineage blood cells for the lifespan of an organism. In adults, quiescent HSPCs reside within a hypoxic bone marrow niche (1-4% O2 physiologic hypoxia) and are capable of rapidly entering the cell cycle and differentiate to produce leukocytes in response to an invading pathogen. The mentor’s lab uncovered that resolution of inflammation is governed by spatial and temporal production of novel mediators and elucidated the specialized pro-resolving mediators (SPMs), a superfamily of autacoids that includes lipoxins (LX), resolvins (Rv), protectins (PD), and maresins (MaR). SPM biosynthesis structures and functions were established in the mentor’s lab and confirmed by others. SPMs are sub-nanomolar potent, stereoselective agonists that promote microbial clearance and containment, while enhancing host survival by accelerating host resolution mechanisms. This proposal is based on new findings from work in progress; we identified, using state- of-the-art metabololipidomics profiling, a specific SPM cluster in HSPC under physiologic hypoxia, which includes Resolvin D1 (RvD1), Resolvin D4 (RvD4), Resolvin E1 (RvE1), Maresin 1 (MaR1) and Lipoxin B4 (LXB4). Also, we recently identified a new SPM, Resolvin E4 (RvE4), in healthy human bone marrow. Tissues that experience physiologic hypoxic niches, such as BM, have high amounts of SPMs through undefined mechanisms. Thus, we propose to rigorously test the following hypothesis: In physiologic hypoxia, specialized pro-resolving mediators (SPMs) produced in BM are essential for regulating HSPC responses de novo and/or during infection at distal sites of invasion, as well as maintaining BM homeostasis. The following aims are proposed by using state-of-the-art omics platforms e.g., metabolipidomics (LC-MS/MS), mass cytometry (CyTOF) and single cell RNA sequencing (sc-RNA-seq) in murine and human HSPCs to: 1) determine the impact of physiologic hypoxia on endogenous novel SPM production in BM niche (K99), and 2) establish the regulation of HSPC differentiation and responses to infection by the SPM cluster, specifically RvD1, RvD4, MaR1 and the novel RvE4 (K99/R00). The K99 mentored phase will take place at Brigham and Women’s Hospital and Harvard Medical School under the mentorship of two internationally recognized scientists, Professor Charles N. Serhan, the leader in the structural elucidation of SPMs and their functions and Professor Leonardo Zon, the leader on hematopoiesis. Dr. Libreros will be further advised by a scientific committee/collaborator covering different aspects of the research proposal: Dr. Matthew Spite, Dr. Mark Perrella, and Professor David Scadden. The goal of this proposal is to provide a comprehensive scientific and career development plan for the applicant with the required skills to transition to an independent faculty position (R00). Results from these studies will yield fundamentally new insights into the functions of SPMs and novel pro-resolving pathways in HSPC biology. These discoveries can help develop novel treatments for hematological disorders and provide a basic understanding of how bone marrow supports resolution programs during infections.