Mechanisms of neurodegeneration by a fibrinogen-containing protein complex during traumatic brain injury

创伤性脑损伤期间含纤维蛋白原的蛋白质复合物引起神经退行性变的机制

• 批准号: 10027325
• 负责人: DAVID LOMINADZE
• 金额: $ 33.86万
• 依托单位: UNIVERSITY OF SOUTH FLORIDA
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-05-01 至 2023-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10027325
• 关键词: Mechanisms; neurodegeneration; fibrinogen; containing; protein

Project Summary This application addresses problems related to vascular cognition impairment (VCI). Particularly it aims to define mechanisms of vasculo-astrocyte functional connectivity that results in cognitive decline after inflammatory pathologies, e.g. traumatic brain injury (TBI). It is known that increased vascular permeability is involved in pathological alterations in neurovascular network such as accumulation of fibrinogen (Fg) and cellular prion protein (PrPC) leading to neuronal dysfunction and degeneration. However, critical factors that initiate these effects are not known. Our preliminary data indicated that TBI-induced an increase in blood level of Fg, called hyperfibrinogenemia (HFg), and enhanced cerebrovascular permeability to proteins mainly via caveolar transcytosis. This effect caused a greater deposition of Fg and increased formation of Fg and PrPC complex in vasculo-astrocyte interface, resulting in vasculo-astrocyte physical uncoupling and astrocyte activation leading to neuronal degeneration via overexpression of neurotrophic tyrosine receptor kinase B (TrkB) and formation of reactive oxygen species (ROS). These effects were associated with neuronal degeneration and reduction in short-term memory (STM) in mice after TBI. Importantly, treatment of mice with siRNA against caveolae membrane protein caveolin-1 (Cav-1) ameliorated TBI-induced memory reduction. Based on these data, we propose a novel hypothesis that TBI-mediated inflammation increases the blood level of Fg, which via binding to endothelial ICAM-1 activates caveolar protein transcytosis resulting in enhanced Fg deposition and formation of Fg-PrPC complex, which cause astrocyte activation, vasculo-astrocyte uncoupling and subsequent neuronal degeneration (via TrkB-ROS pathway) resulting in STM reduction. This compelling hypothesis provides the crucial link between vascular dysfunction and neuronal degeneration leading to cognition impairment during various cerebrovascular pathologies. The present study should reveal the fundamental, previously unknown mechanism for vasculo-astrocyte uncoupling (altered functional and physical connectivity) leading to neuronal degeneration and memory reduction after TBI. The hypothesis will be tested with three specific aims: (1) To define whether the HFg-mediated caveolar protein transcytosis enhances Fg deposition and Fg-PrPC complex formation in brain extravascular space during TBI. (2) To define whether the Fg-PrPC complex formation in vasculo-astrocyte interface causes vasculo-astrocyte uncoupling and neuronal degeneration leading to reduction in STM during TBI. (3) To define if diminishing caveolae formation in vascular endothelium and Fg-PrPC complex formation can ameliorate neuronal degeneration and STM reduction during TBI. Specific mechanisms of TBI-induced vasculo-astrocyte uncoupling and memory impairment, i.e. VCI, will be studied using cultured endothelial cells and astrocytes, and C57BL/6J wild type and transgenic HFg mice. Fg-PrPC complex and ROS formations, levels of TrkB, astrocyte activation, and neuronal degeneration assessed by NeuN will be evaluated by immunohistochemistry and Western blot. STM will be assessed by novel object recognition test, Barnes maze and Y-maze tests.

项目摘要 该应用程序解决了与血管认知障碍（VCI）有关的问题。它尤其是为了定义 Vasculo-Asstrocyte功能连通性的机制，导致炎症后认知能力下降 病理，例如创伤性脑损伤（TBI）。众所周知，增加的血管通透性涉及 神经血管网络中的病理改变，例如纤维蛋白原（FG）和细胞prion蛋白的积累 （PRPC）导致神经元功能障碍和变性。但是，发起这些影响的关键因素不是 已知。我们的初步数据表明，TBI引起的血液水平升高，称为高纤维蛋白原血症 （HFG），并主要通过caveolar跨介症增强对蛋白质的脑血管通透性。这种效果引起的 在Vasculo-Asstrocyte界面中FG的更大沉积以及FG和PRPC复合物的形成增加，结果 在Vasculo-Asstrocyte物理解偶联和星形胶质细胞激活中，导致神经元变性通过 神经营养酪氨酸受体激酶B（TRKB）的过表达和活性氧（ROS）的形成。 这些作用与小鼠的神经元变性和短期记忆（STM）的减少有关 TBI。重要的是，用siRNA治疗小鼠膜膜蛋白可窝蛋白1（CAV-1）改善 TBI引起的记忆减少。基于这些数据，我们提出了一个新的假设，即TBI介导 炎症增加了FG的血液水平，通过与内皮内皮ICAM-1结合激活Caveolar蛋白 转胞胞病，导致FG沉积和FG-PRPC复合物的形成增强，这引起星形胶质细胞 激活，Vasculo-Asstrocyte解偶联和随后的神经元变性（通过TRKB-ROS途径）导致 在STM降低中。这种引人入胜的假设提供了血管功能障碍与神经元之间的关键联系 变性导致各种脑血管病理期间的认知障碍。本研究 应揭示Vasculo-Asstrocyte解偶联的基本，以前未知的机制（改变 功能和物理连通性）导致TBI后神经元变性和记忆的减少。这 假设将以三个特定的目的进行测试：（1）定义HFG介导的小窝蛋白是否定义 TBI期间，跨经细胞增多增强了脑血后空间中的FG沉积和FG-PRPC复合物的形成。 （2） 为了定义Vasculo-Astrocyte界面中FG-PRPC复合物的形成是否导致Vasculo-Asstrocyte引起 解偶联和神经元变性导致TBI期间STM的减少。 （3）定义是否减少小窝 血管内皮和FG-PRPC复合物的形成可以改善神经元变性和STM TBI期间的减少。 TBI诱导的Vasculo-Astrocyte解偶联和记忆障碍的特定机制， 即VCI将使用培养的内皮细胞和星形胶质细胞以及C57BL/6J野生型和转基因HFG进行研究 老鼠。 FG-PRPC复合物和ROS形成，TRKB的水平，星形胶质细胞激活和神经元变性 通过NEUN评估将通过免疫组织化学和Western印迹评估。 STM将通过新颖 对象识别测试，巴恩斯迷宫和Y迷宫测试。