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（由申请人提供）：中风是美国长期残疾的主要原因。虽然急性血运重建术可用于中止或减轻中风负担，但目前还没有药物可以改善中风后的恢复。炎症反应是这类治疗的一个有希望的目标，因为它发生在中风后的几天和几周内，可能是有害的，也可能是有益的。一个悬而未决的主要问题是受伤的大脑如何调节免疫反应，以及是否有分子途径可以通过调节整体免疫反应来对功能恢复施加有益或限制有害的影响。星形胶质细胞是脑损伤反应的关键组成部分——所谓的“反应性星形胶质细胞”在脑损伤后普遍存在。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。我们提出询问星形胶质细胞中的转化生长因子β （TGF¿）信号是否调节中风后的炎症，因为它是免疫反应的主要调节剂。TGF¿可以解决损伤后的免疫反应，并驱动免疫细胞表型向较少的炎症状态发展。我们的初步实验表明，TGF¿信号在中风后的大脑中增加，持续数周，并发生在反应性星形胶质细胞中。为了测试TGF在反应性星形胶质细胞中的功能是否反映了其在其他类型免疫细胞中的作用，我们构建了仅在星形胶质细胞中TGF¿信号减少的小鼠。我们发现这些小鼠的初级星形胶质细胞在缺氧-葡萄糖剥夺后表现出更“促炎症”的表型，小鼠本身在中风后表现出增加的炎症反应。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)促进功能恢复。我们计划用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。我们假设中风后对TGF-¿的反应在数周内增加，并且反应性星形胶质细胞在中风后对TGF-¿有反应。在Aim 2中，我们将测试星形胶质细胞TGF¿信号在缺血神经炎症反应中的功能，使用遗传学和药理学方法以及体内和体外实验来靶向星形细胞中的TGF¿信号。我们假设星形细胞TGF¿信号驱动中风免疫反应的解决。在Aim 3中，我们将使用遗传小鼠模型来询问中风诱导的星形细胞TGF¿信号对功能恢复是否有益或有害。我们预测星形细胞TGF¿信号可以促进中风后的恢复。随着实验的完成，我们将确定脑卒中后TGF¿反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反应，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针对大脑免疫反应的治疗方法，并使中风后几天就诊的患者受益。