Myeloid lineage targeting to improve recovery from injury and surgery: Cellular and molecular mechanisms

项目摘要 尽管每年有许多人在非致命性骨折后受到持续疼痛和骨折愈合不良的影响， 创伤和手术损伤仍然不清楚什么是深刻的多细胞的关键组成部分， 以及如何操纵它们以改善结果。特别是外周损伤 动员免疫系统来解决组织损伤，然而，持续的免疫激活可以 这是有害的，并有助于延迟愈合。骨髓系细胞在先天免疫中起着重要作用， 对损伤的反应-外周，如巨噬细胞，和中央，如卵黄囊衍生的小胶质细胞。但 骨髓系细胞对骨愈合、围手术期疼痛的时间和区域特异性贡献 和手术恢复情况尚待阐明。精确操作这些骨髓细胞， 在人类中不可能有因果关系。为了确定改善恢复的细胞和分子靶点，我们将 因此，利用临床上已知的骨科损伤小鼠模型。我们的核心假设是 有一个关键时期，在此期间，骨髓系细胞的参与对于正常恢复至关重要。 损伤;然而，以细胞因子释放和稳态功能丧失为标志的长期激活， 导致疼痛和骨愈合受损，最终增加长期残疾的风险。追求这个 基础工作，我们将使用分子和整个生物体的方法相结合，我们有 重要的专业知识，包括复杂骨科创伤的小鼠模型， 持续性疼痛和功能障碍，特异性转基因操作和骨纵向成像 和CNS组织。特别是，这种能力的融合使我们能够回答以下关键问题 知识差距：1）先天免疫反应有助于恢复，但其功能障碍是否可以 在体内监测，以确定在风险的个人？2)什么样的激活的骨髓细胞的分子特征- 谱系细胞可以靶向外周和中央，以改善结果？3)是骨髓系反应 与外周损伤的关系在进化上是保守的，因此与预防有关？拟议的研究建立 我们之前在慢性疼痛小鼠模型中的工作表明：1）骨髓靶向正电子 发射断层扫描配体可以追踪功能障碍的先天免疫激活，2）巨噬细胞的衰减 小胶质细胞活化可改善持续性疼痛; 3）新的标志物可用于区分浸润性疼痛和非浸润性疼痛。 巨噬细胞从常驻小胶质细胞在脊髓，从而阐明其独特的贡献。最后， 这些研究将确定髓系细胞如何可能是外周损伤之间的初始细胞联系， 骨愈合不良和严重的急性疼痛。若能顺利完成建议的研究， 了解隔室特异性巨噬细胞和小胶质细胞对损伤后愈合的影响， 具体的干预目标，并澄清何时以及在谁的这种治疗将提供最大的好处。

Project Summary Despite the number of people affected each year by persistent pain and poorly healed fractures after nonfatal traumatic and surgical injury it remains unclear what are the key components of the profound multicellular response to injury and how they can be manipulated to improve outcomes. In particular, peripheral injury mobilizes the immune system to resolve tissue damage, however, sustained immune activation can be detrimental and contribute to delayed healing. Myeloid-lineage cells are instrumental in the innate immune response to injury- peripherally, as macrophages, and centrally, as yolk sac-derived microglia. Nevertheless, the temporal and compartment-specific contributions of myeloid-lineage cells to bone healing, perioperative pain and surgical recovery have yet to be elucidated. Precise manipulation of these myeloid-lineage cells to establish causation is not possible in humans. To identify cellular and molecular targets for improving recovery we will therefore take advantage of a clinically informed mouse model of orthopaedic injury. Our central hypothesis is that there is a critical period during which myeloid-lineage cell involvement is crucial for proper recovery from injury; however, prolonged activation, marked by cytokine release and loss of homeostatic functions, can contribute to pain and impaired bone healing ultimately increasing the risk for long-term disability. To pursue this fundamental work, we will use a combination of molecular and whole organism approaches in which we have significant expertise including mouse models of complex orthopaedic trauma, affective-motivational readouts of persistent pain and functional impairment, specific transgenic manipulations and longitudinal imaging of bone and CNS tissues. In particular, this convergence of capabilities uniquely positions us to answer the following key knowledge gaps: 1) The innate immune response is instrumental to recovery, but can its dysfunction be monitored in vivo to identify at risk individuals? 2) What specific molecular signatures of activated myeloid- lineage cells can be targeted peripherally and centrally to improve outcomes? 3) Is the myeloid-lineage response to peripheral injury evolutionarily conserved and therefore translationally relevant? The proposed research builds on our previous work in a mouse model of chronic pain in which we showed that: 1) Myeloid-targeted positron emission tomography ligands can track dysfunctional innate immune activation, 2) Attenuation of macrophage and microglial activation can improve persistent pain, 3) New markers can be used to distinguish infiltrating macrophages from resident microglia in the spinal cord thus clarifying their unique contributions. Ultimately, these studies will establish how myeloid-lineage cells may be the initial cellular link between peripheral injury, poor bone healing and severe acute pain. Successful completion of the proposed studies will enhance our understanding of compartment-specific macrophage and microglia effects on healing after injury, identify cell- specific targets for intervention, and clarify when and in whom such treatments will provide the most benefit.