Developing macrophage-based therapies for peripheral nerve injuries

摘要 周围神经损伤，无论是创伤、手术并发症或神经疾病造成的，都困扰着数百万人。 仅在美国，它就是造成世界各地残疾和痛苦的主要原因。这个 周围神经损伤的症状包括麻木、刺痛、肌肉无力、疼痛和步态障碍。 尽管迫切需要，但目前还没有批准的加速周围神经再生的治疗方法。 在受伤之后。尽管许多研究人员将他们对神经损伤的研究重点放在 周围神经本身，特别是神经元和雪旺细胞，我们采取了一种新的方法，并 重点研究免疫系统的组成部分--特别是巨噬细胞。免疫疗法，或称 操纵免疫系统来治疗人类疾病，是医学中一个快速增长的领域，它已经 显示出巨大的希望，特别是在治疗自身免疫性疾病和癌症方面。免疫疗法可能需要 多种形式，包括单抗、检查点抑制剂和调节性T淋巴细胞输注。 虽然巨噬细胞目前不用于治疗人类疾病，但也可以利用它来治疗选定的 疾病，周围神经损伤是由于血-神经屏障的破坏和 巨噬细胞在周围神经再生中的既定作用。建立在展示了 新陈代谢对巨噬细胞功能的重要性 正在研究一项改变对 关键代谢转运体，单羧酸转运体1(MCT1)，对巨噬细胞功能的影响。我们 最近发表的一篇论文显示，巨噬细胞中MCT1的选择性下调会损害 吞噬，减少促再生细胞因子的产生，并损害周围神经的恢复 受伤。更重要的是，从临床角度来看，我们还发现MCT1选择性上调在 巨噬细胞加速周围神经再生，静脉注射巨噬细胞 小鼠瞄准受损的神经并参与修复。基于这些结果，我们目前的提案将 探讨促进小鼠神经损伤后恢复的两种可能机制。在目标1中，我们将 脂质纳米粒体外转化巨噬细胞上调MCT1或促再生途径 分别表达MCT1和包裹黄芩苷，并检测是否过继细胞转移。 这些转化的巨噬细胞加速了神经修复和恢复。在目标2中，我们将测试这些 相同的脂质纳米粒在体内直接静脉注射后能够转化巨噬细胞 注射，可加速周围神经损伤的恢复。如果成功，这个实验中的 该提案不仅将验证加速损伤后神经恢复的新技术和目标，而且 还可能提供一种在其他巨噬细胞依赖条件下操纵巨噬细胞的试剂， 如无法愈合的皮肤伤口、肺或肝纤维化以及肌肉损伤。

Summary Peripheral nerve injuries, whether the result of trauma, surgical complications, or neuropathies, afflict millions of people in the United States alone and are a major cause of disability and suffering throughout the world. The symptoms of peripheral nerve injury include numbness, tingling, muscle weakness, pain, and gait dysfunction. Despite the critical need, there are currently no approved therapies to accelerate peripheral nerve regeneration following injury. Though many researchers are focusing their investigations of nerve injury on components of the peripheral nerve itself, particularly neurons and Schwann cells, we have taken a novel approach and are focusing on components of the immune system-- specifically macrophages. Immunotherapy, or the manipulation of the immune system to treat human diseases, is a rapidly growing area in medicine that has shown great promise, particularly in treating autoimmune diseases and cancer. Immunotherapies can take many forms, including monoclonal antibodies, checkpoint inhibitors, and regulatory T lymphocyte transfusions. Though not currently used for treating human diseases, macrophages could also be harnessed to treat select diseases, with peripheral nerve injuries being a potential target due to disruption of the blood-nerve barrier and the established role of macrophages in peripheral nerve regeneration. Building on research demonstrating the importance of metabolism for the function of macrophages, we are studying the impact of alterations in a critical metabolic transporter, monocarboxylate transporter 1 (MCT1), on the function of macrophages. We recently published a paper showing that downregulation of MCT1 selectively in macrophages impairs phagocytosis, reduces production of pro-regenerative cytokines, and impairs recovery from peripheral nerve injury. More importantly from a clinical perspective, we also found that upregulation of MCT1 selectively in macrophages accelerates peripheral nerve regeneration and that macrophages injected intravenously into mice target the injured nerve and participate in repair. Based on these results, our current proposal will investigate two potential mechanisms for accelerating nerve recovery from injury in mice. In Aim 1, we will transform macrophages ex vivo to upregulate MCT1 or pro-regenerative pathways with lipid nanoparticles expressing MCT1 plasmid or encapsulating baicalin, respectively, and test whether adoptive cell transfer of these transformed macrophages accelerates nerve repair and recovery. In Aim 2, we will test whether these same lipid nanoparticles are capable of transforming macrophages in vivo following direct intravenous injections, resulting in accelerated recovery from peripheral nerve injuries. If successful, the experiments in this proposal will not only validate a novel technique and target for accelerating nerve recovery following injury, but also potentially provide an agent for manipulating macrophages in other macrophage-dependent conditions, such as non-healing skin wounds, pulmonary or liver fibrosis, and muscle injuries.