TGFbeta signaling, reactive astrogliosis and function after stroke

TGFbeta 信号传导、反应性星形胶质细胞增生和中风后的功能

• 批准号: 8453563
• 负责人: MARION S BUCKWALTER
• 金额: $ 6.45万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-06-01 至 2012-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8453563
• 关键词: Ablation; Acute; Affect; Astrocytes; Biological Assay; Brain; Brain Injuries; CCL2 gene; CCL7 gene; Caring; Cause of Death; Cells; Data; Exhibits; Genetic; Glial Fibrillary Acidic Protein; Glucose; Immune; Immune response; Immune system; Immunohistochemistry; In Vitro; Inflammation; Inflammatory; Inflammatory Response; Injury; Ischemia; Lead; Length; Measures; Medical; Molecular; Mus; Oxygen; Pathway interactions; Patients; Pattern; Pharmaceutical Preparations; Phenotype; Plasma; Process; Recovery; Recovery of Function; Reporter; Resolution; Role; Signal Transduction; Specificity; Staining method; Stains; Stroke; Testing; Time; Transforming Growth Factor beta; United States; astrogliosis; base; behavior test; brain cell; cell type; chemokine; cytokine; deprivation; disability; functional outcomes; immune function; improved; in vivo; inhibitor/antagonist; injured; insight; kinase inhibitor; macrophage; mouse model; neuroinflammation; neutrophil; public health relevance; research study; response; response to injury; small molecule; stroke recovery

DESCRIPTION (provided by applicant): Stroke is the leading cause of long-term disability in the United States. Although acute revascularization therapies can be used to abort or reduce stroke burden, there are currently no drugs that improve recovery after a stroke has happened. The inflammatory response is a promising target for such therapies as it occurs in the days and weeks after a stroke and can be both detrimental and beneficial. A major unanswered question is how the injured brain modulates immune responses, and if there are molecular pathways that can be utilized to exert beneficial or limit detrimental effects on functional recovery via modulating the overall immune response. Astrocytes are a key component of the brain's injury response - so-called "reactive astrocytes" are ubiquitous after brain injury. They are also increasingly recognized as key components of the brain's innate immune system. We propose to ask if Transforming Growth Factor Beta (TGF¿) signaling in astrocytes modulates inflammation after stroke because it is a master regulator of immune responses. TGF¿ can resolve immune responses after injury and drive immune cell phenotypes towards less inflammatory states. Our preliminary experiments show that TGF¿ signaling is increased in the brain after stroke, persists for weeks, and occurs in reactive astrocytes. To test if TGF¿'s function in reactive astrocytes mirror its role in other types of immune cells we constructed mice in which TGF¿ signaling is decreased only in astrocytes. We have found that primary astrocytes from these mice exhibit a more "pro-inflammatory" phenotype after oxygen- glucose deprivation, and the mice themselves demonstrate increased inflammatory responses after stroke. Based on this data we hypothesize that after stroke, TGF¿ signaling (1) occurs in reactive astrocytes, (2) limits the inflammatory response, and (3) improves functional recovery. We plan to test our hypothesis in three Specific Aims. In Aim 1 we will use reporter mice and immunohistochemistry to determine patterns of TGF¿ signaling after stroke. We hypothesize that there are increased responses to TGF-¿ for weeks after stroke, and that reactive astrocytes are responding to TGF¿ after stroke. In Aim 2 we will test the function of astrocytic TGF¿ signaling in the neuroinflammatory response to ischemia, using genetic and pharmacological approaches and in vivo and in vitro experiments to target TGF¿ signaling in astrocytes. We hypothesize that astrocytic TGF¿ signaling drives resolution of the immune response to stroke. In Aim 3 we will use a genetic mouse model to ask if stroke-induced astrocytic TGF¿ signaling is beneficial or detrimental for functional recovery. We predict that astrocytic TGF¿ signaling improves recovery from stroke. With the completion of the proposed experiments we will have defined the length and cell specificity of TGF¿ responses after stroke. We will gain insight into how astrocytes influence the immune response to stroke, and into the functional diversity of reactive astrocytes. Our findings may lead to therapies that will target the brain's immune responses and benefit patients who present for medical care in the days after stroke. PUBLIC HEALTH RELEVANCE: Stroke is the third leading cause of death in the US, and a leading cause of disability, and there are currently no drugs that improve recovery after stroke. Neuroinflammation affects many processes important for recovery from stroke and modulating neuroinflammation is therefore likely to be a way we can improve recovery from stroke. In this application we propose to study the effects of a master regulator of neuroinflammation, transforming growth factor beta, to determine how its effects in astrocytes can be manipulated to increase successful recovery from stroke.

描述（由适用提供）：中风是美国长期残疾的主要原因。尽管急性血运重建疗法可用于中止或减少中风烧伤，但目前尚无药物改善中风后的恢复。炎症反应是中风后几天和几周发生的这种疗法的承诺靶标，可能是有害和有益的。一个主要的未解决的问题是受伤的大脑如何调节免疫回报，以及是否存在可以利用的分子途径来通过调节整体免疫响应来对功能恢复产生有益或有害的影响。星形胶质细胞是大脑损伤反应的关键组成部分 - 所谓的“反应性星形胶质细胞”在脑损伤后无处不在。它们也越来越被认为是大脑先天免疫系统的关键组成部分。我们建议询问中风后星形胶质细胞调制注射中转化生长因子β（TGF。）信号传导，因为它是免疫反应的主要调节剂。 TGF损伤后可以解决免疫复杂，并将免疫细胞表型驱动到炎症状态较低的状态。我们的初步实验表明，中风后大脑中的TGF信号持续数周，并且发生在反应性星形胶质细胞中。为了测试反应性星形胶质细胞中TGF的功能是否反映了其在其他类型的免疫电池中的作用，我们构建了小鼠，其中TGF partight仅在星形胶质细胞中降低TGF。我们发现，来自这些小鼠的原代星形胶质细胞在氧气剥夺后暴露了更“促炎”的表型，而小鼠本身表现出了中风后炎症反应的增加。基于这些数据，我们假设中风后，TGF¿信号（1）发生在反应性星形胶质细胞中，（2）限制炎症反应，（3）改善功能恢复。我们计划以三个具体目标来检验我们的假设。在AIM 1中，我们将使用报告基因小鼠和免疫组织化学来确定中风后TGF信号的模式。我们假设中风后数周的TGF- - 对TGF-的反应增加，并且反应性星形胶质细胞在中风后对TGF响应。在AIM 2中，我们将使用遗传和药物方法，体内和体外实验来测试星形细胞TGF信号在对缺血的神经炎症反应中的信号传导的功能，以靶向星形胶质细胞中的TGF信号。我们假设星形胶质细胞TGF信号传导可驱动对中风的免疫反应的分辨率。在AIM 3中，我们将使用遗传小鼠模型询问中风诱导的星形细胞TGF信号是否对功能恢复有益或有害。我们预测星形细胞TGF信号会改善中风的恢复。随着提出的实验的完成，我们将定义中风后TGF响应的长度和细胞特异性。我们将深入了解星形胶质细胞如何影响中风的免疫响应以及反应性星形胶质细胞的功能多样性。我们的发现可能会导致疗法，该疗法将针对大脑的免疫调查，并使中风后几天出席医疗服务的患者受益。 公共卫生相关性：中风是美国第三大死亡原因，也是残疾的主要原因，目前没有药物可以改善中风后的恢复。神经炎症会影响许多对于从中风恢复和调节神经炎症至关重要的过程，因此很可能是我们可以改善中风恢复的一种方式。在此应用中，我们建议研究神经炎症的主要调节剂，转化生长因子β，以确定如何操纵其在星形胶质细胞中的影响以增加中风的成功恢复。