Neuroimmune Processes and Neuroplasticity in Chronic Spinal Cord Injury

慢性脊髓损伤的神经免疫过程和神经可塑性

基本信息

批准号：
9304368
负责人：
Harold David Shine
金额：
$ 34.19万
依托单位：
BAYLOR COLLEGE OF MEDICINE
依托单位国家：
美国
项目类别：
财政年份：
2015
资助国家：
美国
起止时间：
2015-07-01 至 2020-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9304368
关键词：
Acute Anatomy Antibodies Axon Behavioral Biological Assay Biological Preservation Cells Cervical Cervical spinal cord structure Chronic Collaborations Conditioned Culture Media Contralateral Contusions Corticospinal Tracts Data Databases Enzyme-Linked Immunosorbent Assay Forelimb Future Gene Expression Genes Genetic Gifts Growth Histologic Horns Immune Immunologics In Vitro Inflammatory Injectable Injection of therapeutic agent Injury Ipsilateral Laboratory Research Lead Lesion Letters Life Measurement Mediating Medicine Methods Microglia Modeling Molecular Monitor Motor Neurons Mus NTF3 gene Nerve Fibers Nervous system structure Neuraxis Neuroimmune Neuroimmunomodulation Neuronal Plasticity Neurotrophic Tyrosine Kinase Receptor Type 3 Neurotrophin 3 Ohio Pathway interactions Patients Phenotype Play Positioning Attribute Process Proteins RNA Rattus Recovery Recovery of Function Research Design Retrieval Role Services Site Small Interfering RNA Source Spinal Spinal cord injury Spinal cord injury patients Sum Techniques Technology Testing Therapeutic Time Tissues Translational Research Universities Viral Vector Wallerian Degeneration Work axon growth axonal sprouting base clinically relevant college design experimental study gene therapy improved improved functioning in vivo injured insight macrophage neurotrophic factor neurotropin next generation sequencing novel overexpression programs public health relevance recombinase-mediated cassette exchange repaired response sciatic nerve screening transcriptome transcriptome sequencing vector

项目摘要

DESCRIPTION (provided by applicant): Over two thirds of spinal cord injury (SCI) patients have anatomical preservation at the injury site, yet this preserved tissue is typically completely or partially dysfunctional. Therefore, to improve function in these patients, strategies are needed that enhance the function of the remaining connections by enabling the inherent plasticity of the CNS. We found an unanticipated interplay between a neurotrophin and cellular immune processes that may provide a means to promote plasticity after SCI. Moreover, we have evidence that this interplay may be exploited to induce neuroplasticity in chronic SCI. Our earlier work showed that unilateral viral-vector mediated over-expression of Neurotrophin-3 (NT-3) in lumbar motoneurons induced axon growth from the contralateral corticospinal tract (CST) towards the source of the NT-3. Subsequently, we showed that there is an immune component to the NT-3-induced axonal sprouting and that microglia are likely involved. This proposal will determine the role that microglia play in supporting post-SCI axonal growth and determine the molecular mechanisms involved. We hypothesize that NT-3 re-programs microglia that become activated during Wallerian degeneration, which then induce axonal sprouting of surviving CST axons. We have 3 aims that are the sum of close collaborations between SCI research laboratories of Baylor College of Medicine and the Ohio State University. In the first aim we will define the microglial-derived factors elicited by NT-3 that can stimulate axonal growth. Preliminary data show that NT-3 re-programs inflammatory macrophages and microglia to a less inflammatory state. We propose to use unbiased RNA-seq to identify candidate molecules in the microglia transcriptome that are induced by NT-3. This work will allow us to compile a database of potential molecules that may drive the CST sprouting response. In aim 2 we will determine whether NT-3 synergizes with microglia to enhance CST sprouting in vivo. Mouse genetics will be used to definitively prove a causal role for microglia in NT-3-induced axonal sprouting in vivo. Specifically, using Cre-lox technology, TrkC receptors will be selectively deleted in microglia. We predict that deleted TrkC in microglia will eliminate NT-3 re- programing of microglia and subsequently, their ability to promote axonal sprouting. In aim 3 we will use an acute and chronic rat unilateral pyramidotomy model to test, for the first time, if over-expression of NT-3 in the cervical spinal cord induces neuroplasticity and recovery of forelimb function. Additionally, we will test the effects of NT-3 over-expression in rats with cervical contusions. Th use of a more clinically-relevant vector and delivery method could lead to pre-translational research into the use of gene and cellular therapy for SCI. Practically, treatment for SCI must be effective after spontaneous functional recovery has plateaued, which could be months to years after the injury. Importantly, the studies proposed here target that chronic SCI window. Insights gained from these experiments have the potential to direct future therapeutic strategies to promote enhanced neuroplasticity and therefore increased functional recovery in patients with chronic SCI.

描述（由申请人提供）：超过三分之二的脊髓损伤（SCI）患者在损伤部位有解剖学保留，但这些保留的组织通常完全或部分功能障碍，因此，为了改善这些患者的功能，需要采取策略。通过启用中枢神经系统固有的可塑性来增强剩余连接的功能我们发现神经营养蛋白和细胞免疫过程之间存在意想不到的相互作用，这可能提供了一种促进脊髓损伤后可塑性的方法。我们早期利用它来诱导慢性 SCI 的神经可塑性。研究表明，单侧病毒载体介导的腰椎运动神经元中神经营养素 3 (NT-3) 的过度表达诱导轴突从对侧皮质脊髓束 (CST) 向 NT-3 的源头生长。 NT-3 诱导的轴突萌芽的免疫成分，并且小胶质细胞可能参与其中，该提议将确定小胶质细胞在支持 SCI 后轴突生长中所发挥的作用并确定。我们首创 NT-3 重新编程在沃勒变性期间被激活的小胶质细胞，然后诱导幸存的 CST 轴突萌发。我们有 3 个目标，这是贝勒学院 SCI 研究实验室之间密切合作的总和。医学博士和俄亥俄州立大学的第一个目标是定义 NT-3 引发的可刺激轴突生长的小胶质细胞衍生因子。我们建议使用无偏 RNA-seq 来识别小胶质细胞转录组中由 NT-3 诱导的候选分子。在目标 2 中，我们将确定 NT-3 是否与小胶质细胞协同作用以增强体内 CST 萌芽，从而明确证明其因果作用。具体而言，使用 Cre-lox 技术，小胶质细胞中的 TrkC 受体将被选择性删除，我们预测小胶质细胞中删除的 TrkC 将消除小胶质细胞的 NT-3 重新编程。在目标 3 中，我们将使用急性和慢性大鼠单侧锥体切开术模型来首次测试是否过度表达。此外，我们将测试 NT-3 在颈椎挫伤大鼠中过度表达的影响，使用更具临床相关性的载体和递送方法。实际上，SCI 的治疗必须在自发功能恢复稳定后有效，这可能是在损伤后数月至数年。本文提出的研究目标是从这些实验中获得的慢性 SCI 窗口有可能指导未来的治疗策略，以促进增强神经可塑性，从而增加慢性 SCI 患者的功能恢复。