TREM2 regulation of macrophages in spinal cord injury and CNS endogenous repair

TREM2对脊髓损伤和中枢神经系统内源性修复中巨噬细胞的调节

• 批准号: 8311626
• 负责人: PHILLIP G POPOVICH
• 金额: $ 30.5万
• 依托单位: OHIO STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-08-15 至 2014-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8311626
• 关键词: Adverse effects; Affect; Anti-Inflammatory Agents; Anti-inflammatory; Autoimmune Process; Autologous; Axon; Back; Behavioral; Biological Assay; Bone Marrow Cells; CNS autoimmune disease; Cell Differentiation process; Cells; Cessation of life; Chronic; Clinical Trials; Contusions; Corticospinal Tracts; Data; Demyelinations; Dorsal; Engineering; Environment; Genetic; Goals; Growth; Healed; Health Care Costs; Human; Inflammation; Inflammatory; Injury; Intravenous; Knock-out; Lesion; Lysophosphatidylcholines; Microglia; Modeling; Molecular; Motor; Myelin; Myelogenous; Myeloid Cells; Natural regeneration; Nerve Degeneration; Neurons; Paralysed; Patients; Peripheral Blood Mononuclear Cell; Phagocytosis; Phenotype; Population; Pre-Clinical Model; Protocols documentation; Reaction; Recovery; Recovery of Function; Regulation; Relative (related person); Sensory; Signal Pathway; Signal Transduction; Site; Spinal; Spinal Cord; Spinal cord injury; Spinal cord injury patients; Structure; Techniques; Testing; Therapeutic; Tissues; Toxic effect; Variant; Wound Healing; axon growth; axon regeneration; design; dorsal column; enzyme replacement therapy; gain of function; healing; human subject; improved; indexing; injured; loss of function; macrophage; monocyte; nervous system disorder; neuroprotection; neurotoxic; neurotoxicity; oligodendrocyte precursor; overexpression; precursor cell; receptor; regenerative; remyelination; repaired; research study; response; response to injury; spinal cord repair; tissue repair

DESCRIPTION (provided by applicant): Spinal cord injury (SCI) triggers a neuroinflammatory reaction that can aggravate tissue injury (e.g., neuronal death, axonal injury, demyelination) and promote repair (e.g., axon regeneration, remyelination, revascularization). Recently, functionally distinct subsets of macrophages, i.e., "M1" (pro-inflammatory) and "M2" (anti-inflammatory) cells have been identified at sites of SCI which may underlie the functional dichotomy. M1 macrophages are neurotoxic and dominate the injured spinal cord for several weeks post-injury. In contrast, M2 macrophages promote axon growth, even in the presence of inhibitory molecules (e.g. CSPG and myelin), without concomitant neurotoxicity. Unfortunately, M2 macrophages populate the injury site for only a few days, eventually becoming overwhelmed by M1 macrophages. Thus, the high M1:M2 ratio might explain why repair of the injured CNS is slow and inefficient relative to tissues in the periphery. We predict that the efficiency and magnitude of spinal cord repair will be improved by modulating the phenotype and function of macrophages that respond to the injury. We will test this hypothesis using genetic loss-of-function (knockout) and gain-of-function (lentiviral) techniques to manipulate expression of the triggering receptor expressed on myeloid cells-2 (TREM2) on resident microglia and myeloid precursor cells, i.e., cells that give rise to monocyte-derived macrophages (MDMs), since overexpressing TREM2 in macrophages induces an M2 phenotype. In Aim 1 we will examine how TREM2 overexpression or selective knockout on microglia vs. MDMs effects inflammation, motor recovery and anatomical indices of repair after contusive spinal cord injury. By using lentiviral constructs to overexpress TREM2 on MDMs in a model of dorsal spinal hemisection injury in Aim 2, we will determine if TREM2 manipulation influences macrophage effects on myelin/axon phagocytosis, axon regeneration and axonal retraction or "die-back" of injured axons. Using a model of focal intraspinal demyelination (lysolecithin) in conjunction with the gain of function protocols, we will determine if manipulating macrophage TREM2 affects OPC differentiation and remyelination within the spinal cord in Aim 3. The current proposal outlines proof-of-principle experiments that will advance our understanding of how a distinct molecular signaling pathway, i.e., TREM2, influences the natural course of CNS macrophage function after SCI. Importantly, if data from these studies indicate that manipulating TREM2 confers anatomical or functional benefits with minimal or no adverse effects on CNS structure or function, then it should be feasible to develop similar protocols for human clinical trials. Indeed, intravenous delivery of bone marrow cells (the primary technique to be used in the proposed studies) has already been tried in SCI patients and without adverse effects. Moreover, enzyme replacement therapies, using lentiviral transduction of autologous peripheral blood mononuclear cells, were shown to be safe and effective in human subjects.

描述(申请人提供)：脊髓损伤(SCI)触发神经炎症反应，可加重组织损伤(例如，神经元死亡、轴突损伤、脱髓鞘)并促进修复(例如，轴突再生、髓鞘再生、血管重建)。最近，在脊髓损伤部位发现了功能不同的巨噬细胞亚群，即“M1”(促炎)和“M2”(抗炎)细胞，这可能是功能二分法的基础。M1巨噬细胞具有神经毒性，在损伤后的几周内支配损伤的脊髓。相反，M2巨噬细胞促进轴突生长，即使在存在抑制分子(如CSPG和髓鞘)的情况下，也没有伴随的神经毒性。不幸的是，M2巨噬细胞只在损伤部位停留了几天，最终被M1巨噬细胞淹没。因此，高的M1/M2比率可能解释了为什么受损的中枢神经系统的修复相对于周围组织来说是缓慢和低效的。我们预测，通过调节对损伤做出反应的巨噬细胞的表型和功能，脊髓修复的效率和程度将得到改善。我们将使用遗传功能丧失(基因敲除)和功能获得(慢病毒)技术来操作驻留的小胶质细胞和髓系前体细胞上表达的触发受体2(TREM2)的表达，即产生单核细胞来源的巨噬细胞(MDM)的细胞，因为在巨噬细胞中过度表达TREM2会诱导M2表型。在目标1中，我们将研究TREM2在小胶质细胞上的过度表达或选择性敲除与MDM相比如何影响炎症、运动恢复和脊髓挫伤后修复的解剖指标。在AIM 2的脊髓背侧半横断损伤模型中，通过使用慢病毒载体在MDM上过表达TREM2，我们将确定TREM2操作是否影响巨噬细胞对髓鞘/轴突吞噬、轴突再生和轴突回缩或损伤轴突的“死亡”的影响。使用脊髓内局部脱髓鞘(溶血磷脂)的模型和功能方案的获得，我们将在目标3中确定操纵巨噬细胞TREM2是否影响脊髓内OPC的分化和再髓鞘形成。目前的提议概述了验证性实验，这些实验将促进我们对不同的分子信号通路，即TREM2，如何影响脊髓损伤后CNS巨噬细胞功能的自然过程的理解。重要的是，如果来自这些研究的数据表明，操纵TREM2赋予解剖学或功能上的好处，而对中枢神经系统的结构或功能的不良影响最小或没有，那么开发类似的人体临床试验方案应该是可行的。事实上，静脉注射骨髓细胞(建议研究中使用的主要技术)已经在脊髓损伤患者中进行了尝试，并且没有不良反应。此外，使用慢病毒转导自体外周血单核细胞的酶替代疗法在人类受试者中被证明是安全和有效的。