TGFbeta signaling, reactive astrogliosis and function after stroke

中风是美国长期残疾的主要原因。虽然急性血运重建 治疗可用于流产或减少中风负担，目前还没有改善恢复的药物 在中风发生后。炎症反应是这种治疗的有希望的靶点，因为它发生在 在中风后的几天和几周内，这可能是有害的，也可能是有益的。一个主要的未解之谜是 受伤的大脑如何调节免疫反应，以及是否有分子途径可以用来 通过调节整体免疫应答对功能恢复发挥有益或限制有害作用。 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无处不在。 脑损伤后它们也越来越被认为是大脑先天免疫的关键组成部分。 系统我们想知道星形胶质细胞中的转化生长因子β（TGF β）信号是否调节了 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方向。 states.我们的初步实验表明，TGF β信号在中风后大脑中增加，持续时间为 周，并发生在反应性星形胶质细胞中。为了测试TGF β s在反应性星形胶质细胞中的功能是否反映了其在其他神经细胞中的作用， 我们构建了小鼠，其中TGF β信号仅在星形胶质细胞中减少。我们有 发现这些小鼠的原代星形胶质细胞在氧葡萄糖刺激后表现出更促炎的表型， 剥夺，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（1）发生在反应性星形胶质细胞中，（2） 限制炎症反应，和（3）改善功能恢复。我们计划在2015年 三个具体目标。在目标1中，我们将使用报告小鼠和免疫组织化学来确定 中风后的TGF β信号传导我们假设，在治疗后的几周内， 中风后，反应性星形胶质细胞对TGF β有反应。在目标2中，我们将测试 应用遗传学和药理学方法研究星形胶质细胞TGF β信号在缺血神经炎症反应中的作用 方法以及体内和体外实验来靶向星形胶质细胞中的TGF β信号传导。我们假设 星形胶质细胞TGF β信号传导驱动对中风的免疫应答的消退。在目标3中，我们将使用遗传 小鼠模型，以询问中风诱导的星形胶质细胞TGF β信号传导对功能性 复苏我们预测星形胶质细胞TGF β信号传导促进中风恢复。 随着实验的完成，我们将确定TGF β的长度和细胞特异性， 中风后的反应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， 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的治疗方法。 免疫反应，并使中风后几天内接受医疗护理的患者受益。

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 brainʼs injury response ¿ so-called ¿reactive astrocytes¿ are ubiquitous after brain injury. They are also increasingly recognized as key components of the brainʼs innate immune system. We propose to ask if Transforming Growth Factor Beta (TGFbeta) signaling in astrocytes modulates inflammation after stroke because it is a master regulator of immune responses. TGFbeta can resolve immune responses after injury and drive immune cell phenotypes towards less inflammatory states. Our preliminary experiments show that TGFbeta signaling is increased in the brain after stroke, persists for weeks, and occurs in reactive astrocytes. To test if TGFbetaʼs function in reactive astrocytes mirror its role in other types of immune cells we constructed mice in which TGFbeta signaling is decreased only in astrocytes. We have found that primary astrocytes from these mice exhibit a more ¿pro-inflammatory¿ phenotype after oxygenglucose deprivation, and the mice themselves demonstrate increased inflammatory responses after stroke. Based on this data we hypothesize that after stroke, TGFbeta 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 TGFbeta signaling after stroke. We hypothesize that there are increased responses to TGF-beta for weeks after stroke, and that reactive astrocytes are responding to TGFbeta after stroke. In Aim 2 we will test the function of astrocytic TGFbeta signaling in the neuroinflammatory response to ischemia, using genetic and pharmacological approaches and in vivo and in vitro experiments to target TGFbeta signaling in astrocytes. We hypothesize that astrocytic TGFbeta 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 TGFbeta signaling is beneficial or detrimental for functional recovery. We predict that astrocytic TGFbeta signaling improves recovery from stroke. With the completion of the proposed experiments we will have defined the length and cell specificity of TGFbeta 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 brainʼs immune responses and benefit patients who present for medical care in the days after stroke.