Transport of neurotrophic cytokines after spinal cord injury

脊髓损伤后神经营养细胞因子的转运

• 批准号: 7022220
• 负责人: Weihong Pan
• 金额: $ 23.24万
• 依托单位: LSU PENNINGTON BIOMEDICAL RESEARCH CTR
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-03-01 至 2008-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7022220
• 关键词: behavior test; blood brain barrier; cytokine; cytokine receptors; epidermal growth factor; laboratory mouse; leukemia inhibitory factor; membrane permeability; methylprednisolone; nervous system disorder chemotherapy; nervous system regeneration; neuronal transport; neurotrophic factors; nonhuman therapy evaluation; radiotracer; receptor expression; receptor mediated endocytosis; spinal cord injury; transcytosis

Adequate neurotrophic support is essential for spinal cord regeneration; however, production of neurotrophins and neurotrophic cytokines at the site of spinal cord injury (SCI) is insufficient. The blood-brain/blood-spinal cord barrier (BBB/BSCB) mediates permeation of selective neurotrophic cytokines from the periphery. We propose that the transport system for leukemia inhibitory factor (LIF) at the BSCB is upregulated after SCI, and that enhanced transport of LIF benefits functional recovery. To test the hypothesis that LIF crosses the BSCB by receptor-related transport and that the transport system is upregulated after SCI, we will measure blood-to-spinal cord transfer of 12SI-LIF, test the effects of different classes of transport inhibitors, and compare the results with that of epidermal growth factor (125I-EGF). We expect that 12SI-LIF entry will be decreased by a LIF receptor antibody whereas 12SI-EGF entry will be decreased by polycationic peptides and dansylcadaverin but not by an EGF receptor antibody. This will support the concept that LIF crosses the BSCB by receptor-mediated transport while EGF does so by adsorptive endocytosis. We will further determine spinal cord uptake of 125I-LIF and 1251-EGF in various regions and time course after injury, compare the results with those of permeability markers (radioactively labeled albumin and inulin as indicators of barrier disruption), and test the effects of receptor antibodies and endocytosis inhibitors on the increased radiotracer uptake after SCI. We expect that SCI upregulates receptor-related transport (for LIF) without affecting adsorptive transcytosis (for EGF), and that enhanced LIF transport correlates with increased endothelial LIFRalpha receptor expression. To test the hypothesis that LIF benefits spinal cord regeneration after crossing the BSCB, we will determine histological and electrophysiological evidence of axonal regeneration. We expect that tract tracing, neurofilament staining, and intraspinal conduction of evoked potentials will be increased by LIF treatment after peripheral delivery when its transport is upregulated. These changes will coincide with improved behavioral performance. To test the hypothesis that methylprednisolone potentiates the therapeutic effects of LIF and upregulates LIF transport, we will examine not only these regeneration parameters but also transport efficacy after methylprednisolone or combined treatment. By completing these studies, we will have demonstrated that transport of neurotrophic cytokines after SCI can be modulated to facilitate functional restoration. Therefore, the BBB/BSCB is not a simple barrier but also a gate for spinal cord regeneration. Understanding the mechanisms of cytokine transport at this regulatory interface would help in the design of new approaches to treat SCI.

充足的神经营养支持对于脊髓再生至关重要；然而，脊髓损伤（SCI）部位神经营养因子和神经营养细胞因子的产生不足。血脑/血脊髓屏障（BBB/BSCB）介导选择性神经营养细胞因子从外周的渗透。我们认为 SCI 后 BSCB 的白血病抑制因子 (LIF) 转运系统上调，并且 LIF 转运的增强有利于功能恢复。为了检验 LIF 通过受体相关转运穿过 BSCB 以及 SCI 后转运系统上调的假设，我们将测量 12SI-LIF 的血液至脊髓转运，测试不同类别转运抑制剂的作用，并比较 结果与表皮生长因子（125I-EGF）的结果相同。我们预计 LIF 受体抗体会减少 12SI-LIF 进入，而聚阳离子肽和丹酰尸蛋白会减少 12SI-EGF 进入，但 EGF 受体抗体不会减少。这将支持 LIF 通过受体介导的转运穿过 BSCB 而 EGF 通过吸附内吞作用穿过 BSCB 的概念。我们将进一步测定脊髓损伤后各区域和时间过程对125I-LIF和1251-EGF的摄取，并将结果与​​渗透性结果进行比较 标记物（放射性标记的白蛋白和菊粉作为屏障破坏的指标），并测试受体抗体和内吞作用抑制剂对 SCI 后放射性示踪剂摄取增加的影响。我们预计 SCI 上调受体相关转运（对于 LIF）而不影响吸附转胞吞作用（对于 EGF），并且增强的 LIF 转运与内皮 LIFRα 受体表达增加相关。为了检验 LIF 在穿过 BSCB 后有利于脊髓再生的假设，我们将确定轴突再生的组织学和电生理学证据。我们期望纤维束追踪、神经丝染色和 外周分娩后，当诱发电位的转运上调时，LIF 治疗会增加椎管内诱发电位的传导。这些变化将与行为表现的改善同时发生。为了检验甲泼尼龙增强 LIF 的治疗效果并上调 LIF 转运的假设，我们不仅将检查这些再生参数，还将检查甲泼尼龙或联合治疗后的转运功效。通过完成这些研究，我们将证明 SCI 后神经营养细胞因子的转运可以被调节以促进功能恢复。因此，BBB/BSCB不是一个简单的屏障，而是脊髓再生的大门。了解细胞因子在此调节界面的转运机制将有助于设计治疗 SCI 的新方法。