Inflammatory Mechanisms of Brain - Lymphatic Signaling in Stroke

脑淋巴信号通路在脑卒中中的炎症机制 中风后，外周免疫系统被激活，这些全身炎症反应 会加重脑损伤恶化预后但在知识上仍然存在巨大差距。目前还不清楚 中风后受损的大脑是如何向外围发送信号的。 最近，有人提出，某些类型的专门淋巴引流系统可能存在于淋巴结中。 CNS。早在1995年，我们就使用CT成像显示，注入兔子大脑的示踪剂可以直接排出 进入体内颈部淋巴结（Hunter等，Neuropath Appl Neurobiol 1995）。我们现在建议， 脑-颈淋巴结连接可能提供了一个潜在的炎症交叉通路， 中风后的大脑和全身反应。 基于我们的试点数据，我们提出了这样的假设，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，从而恶化神经炎症 和中风结果：（i）在局灶性缺血后，脑星形胶质细胞/周细胞/内皮细胞分泌VEGF-C进入脑内。 （ii）VEGF-C进入颈部淋巴结，增强淋巴结中的促炎信号， 内皮，并诱导M1样巨噬细胞极化和募集;（iii）M1样巨噬细胞，然后 导致灰质和白色物质中的进一步神经炎症和脑损伤。我们将测试这个 在三个综合目标的假设，使用分子工具，细胞培养和体内模型的组合。 在目标1中，我们评估并比较了星形胶质细胞、周细胞和脑内皮细胞 氧糖剥夺后VEGF-C的释放。在目标2中，我们研究了 VEGF-C诱导淋巴内皮炎症和激活巨噬细胞的能力。在目标3中，我们 使用小鼠局灶性脑缺血模型来证实这些脑淋巴信号，并检查 治疗方法可能会中断这一途径，以改善中风的结果。为了评估因果关系， 途径，我们将进行增益和功能丧失的实验，使用细胞培养，在体内 小鼠模型，药理学抑制剂，分子技术，包括siRNA和转基因，长期 神经学结果和成像。 这个项目应该定义一个新的机制，其中受损的神经血管单位与 中风后的外周神经功能障碍我们的发现可能为寻找潜在的 淋巴系统中的中风靶点和生物标志物。最后，该项目还可能有助于开辟新的 中风生物学和淋巴血管生物学的成熟领域之间的协作串扰。

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.