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。虽然急性血运重建疗法可用于流产或减少卒中负担，但目前还没有药物可改善卒中后的恢复。炎症反应是此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，并且可能是有害的和有益的。一个主要的未回答的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用于通过调节整体免疫反应对功能恢复产生有益或限制有害影响。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。我们建议询问星形胶质细胞中的转化生长因子β（TGF β）信号传导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 β可以解决损伤后的免疫反应，并将免疫细胞表型推向炎症较少的状态。我们的初步实验表明，TGF β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反映了它在我们构建的其他类型免疫细胞中的作用，其中TGF β信号仅在星形胶质细胞中减少。我们已经发现，这些小鼠的原代星形胶质细胞在氧-葡萄糖剥夺后表现出更多的“促炎”表型，并且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 β信号传导（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。我们计划在三个具体目标中检验我们的假设。在目标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 β信号转导的模式。我们假设中风后数周内对TGF-β的反应增加，并且反应性星形胶质细胞在中风后对TGF-β有反应。在目标2中，我们将使用遗传和药理学方法以及体内和体外实验来测试星形胶质细胞中TGF <$信号传导在对缺血的神经炎症反应中的功能，以靶向星形胶质细胞中的TGF <$信号传导。我们假设星形胶质细胞TGF β信号传导驱动了对中风的免疫反应的解决。在目标3中，我们将使用遗传小鼠模型来询问中风诱导的星形胶质细胞TGF？信号传导对功能恢复是有益还是有害。我们预测星形胶质细胞的TGF β信号能改善中风的恢复。随着所提出的实验的完成，我们将确定中风后TGF β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对中风的免疫反应，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，并使中风后几天接受医疗护理的患者受益。 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，目前还没有改善中风后恢复的药物。神经炎症影响许多对中风恢复很重要的过程，因此调节神经炎症可能是我们改善中风恢复的一种方式。在本申请中，我们建议研究神经炎症的主要调节因子转化生长因子β的作用，以确定如何操纵其在星形胶质细胞中的作用以增加中风的成功恢复。