Inflammatory Mechanisms of Brain - Lymphatic Signaling in Stroke

脑部炎症机制 - 中风时的淋巴信号传导

• 批准号: 9920224
• 负责人: Kazuhide Hayakawa
• 金额: $ 37.22万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2022-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9920224
• 关键词: Astrocytes; Back; Biological Assay; Biological Markers; Biology; Blood Vessels; Brain; Brain Edema; Brain Injuries; CCL23 gene; CD 200; Cell Culture Techniques; Cell Survival; Cells; Cerebral Ischemia; Cerebrospinal Fluid; Cervical lymph node group; Data; Dextrans; Drainage procedure; Electron Microscopy; Endothelial Cells; Endothelium; Etiology; Evans blue stain; Exposure to; Glucose; Image; Immune; Immune response; Immune system; In Vitro; Inflammation; Inflammatory; Infusion procedures; Interferons; Interruption; Ischemia; Knowledge; Lymphangiogenesis; Lymphatic; Lymphatic Endothelial Cells; Lymphatic Endothelium; Lymphatic System; Macrophage Activation; Migration Assay; Molecular; Mus; Myelin; Neurological outcome; Operative Surgical Procedures; Oryctolagus cuniculus; Outcome; Oxygen; Pathway interactions; Pericytes; Peripheral; Permeability; Pharmacology; Phenotype; Publishing; Rattus; Reporter; Signal Transduction; Small Interfering RNA; Stains; Stroke; System; TLR4 gene; Techniques; Testing; Therapeutic; Tracer; Transgenic Organisms; Travel; Tube; Vascular Endothelial Growth Factor C; Water; Western Blotting; X-Ray Computed Tomography; base; brain endothelial cell; brain parenchyma; chemokine; cytokine; deprivation; experimental study; gray matter; improved; in vivo; in vivo Model; inhibitor/antagonist; kinase inhibitor; loss of function; lymph nodes; lymphatic drainage; lymphatic pump; macrophage; matrigel; migration; monocyte; mouse model; neuroinflammation; neurovascular injury; neurovascular unit; neutralizing antibody; notch protein; novel; post stroke; potential biomarker; prevent; recruit; response; screening; spatiotemporal; stroke outcome; stroke therapy; systemic inflammatory response; targeted biomarker; tool; white matter; white matter damage

Inflammatory Mechanisms of Brain-Lymphatic Signaling in Stroke After stroke, the peripheral immune system becomes activated, and these systemic inflammatory responses are known to amplify brain injury and worsen outcomes. But a major gap in knowledge remains. It is unclear how the stroke-damaged brain sends signals to the periphery. Recently, it has been suggested that some type of specialized lymphatic drainage system may exist in the CNS. Back in 1995, we had used CT imaging to show that tracers injected into rabbit brain can directly drain into the cervical lymph nodes in vivo (Hunter et al, Neuropath Appl Neurobiol 1995). We now propose that this brain-to-cervical-lymph node connection may provide a potential pathway for inflammatory crosstalk between brain and systemic responses after stroke. Based on our pilot data, we propose the hypothesis that after stroke, the injured neurovascular unit releases signals that drain into the cervical lymph node and activate macrophages thus worsening neuroinflammation and stroke outcomes: (i) after focal ischemia, brain astrocytes/pericytes/endothelial cells secrete VEGF-C into CSF; (ii) VEGF-C travels into cervical lymph nodes, enhances pro-inflammatory signals in lymphatic endothelium, and induces M1-like macrophage polarization and recruitment; (iii) M1-like macrophages then contribute to further neuroinflammation and brain injury in both gray and white matter. We will test this hypothesis in three integrated aims, using a combination of molecular tools, cell culture, and in vivo models. In Aim 1, we assess and compare mechanisms for how astrocytes, pericytes and brain endothelial cells release VEGF-C after oxygen-glucose deprivation. In Aim 2, we investigate mechanisms that underlie the ability of VEGF-C to induce inflammation in lymphatic endothelium and activate macrophages. In Aim 3, we will use mouse models of focal cerebral ischemia to confirm these brain-to-lymphatic signals in vivo, and examine therapeutic approaches that may interrupt this pathway to improve stroke outcomes. To assess causality in our pathways, we will conduct gain and loss-of-function experiments using a combination of cell culture, in vivo mouse models, pharmacologic inhibitors, molecular techniques including siRNA and transgenics, long-term neurological outcomes, and imaging. This project should define a novel mechanism wherein the damaged neurovascular unit communicates with peripheral lymphatics after stroke. Our findings may provide a new conceptual framework for seeking potential stroke targets and biomarkers in the lymphatic system. Finally, this project may also help open up new collaborative crosstalk between stroke biology and the well established field of lymphatic vascular biology.

卒中脑淋巴信号的炎症机制 中风后，外周免疫系统被激活，这些全身炎症反应 已知会放大脑损伤并恶化结果。但在知识方面仍然存在一个重大差距。目前还不清楚 中风损伤的大脑是如何向外周发送信号的。 最近，有人提出，某些类型的特殊淋巴引流系统可能存在于 中枢神经系统。早在1995年，我们就使用CT成像技术显示，注射到兔脑中的示踪剂可以直接引流 进入活体的颈部淋巴结(Hunter等人，Neuroath Appl Neurobiol，1995)。我们现在建议，这 脑到颈淋巴结的连接可能提供了一条潜在的途径，导致炎性串扰 中风后的大脑和全身反应。 基于我们的先导数据，我们提出了一个假设，即中风后，受损的神经血管单位释放 信号流入颈部淋巴结并激活巨噬细胞，从而加重神经炎症 和卒中结局：(1)局灶性脑缺血后，脑星形胶质细胞/周细胞/内皮细胞分泌VEGF-C到 脑脊液；(Ii)血管内皮生长因子-C进入颈部淋巴结，增强淋巴中的促炎信号 内皮，并诱导M1样巨噬细胞极化和募集；(Iii)M1样巨噬细胞 会进一步加重灰质和白质的神经炎症和脑损伤。我们将对此进行测试 使用分子工具、细胞培养和活体模型相结合的三个综合目标的假说。 在目标1中，我们评估和比较了星形胶质细胞、周细胞和脑内皮细胞 缺氧缺糖后释放血管内皮生长因子-C。在目标2中，我们研究了 血管内皮生长因子C诱导淋巴管内皮细胞炎症和激活巨噬细胞的能力。在《目标3》中，我们将 利用局灶性脑缺血的小鼠模型，在活体内确认这些脑-淋巴信号，并检查 可能阻断这一途径以改善中风预后的治疗方法。为了评估我们的 途径，我们将使用细胞培养的组合进行体内获得和功能丧失的实验 小鼠模型，药物抑制剂，包括siRNA和转基因在内的分子技术，长期 神经学结果和成像。 这个项目应该定义一种新的机制，在这种机制中，受损的神经血管单位与 中风后的外周淋巴管。我们的发现可能会为挖掘潜力提供一个新的概念框架 淋巴系统中的中风靶点和生物标记物。最后，这个项目还可能有助于开辟新的 中风生物学和公认的淋巴管生物学领域之间的协作串扰。