Longitudinal Monitor of Microglia Activation After Stroke with SPION-enhanced MRI

 描述（由申请人提供）：使用SPION增强MRI对卒中后小胶质细胞活化的纵向监测摘要：小胶质细胞是脑内驻留的巨噬细胞，形成脑内免疫防御的第一道防线。新出现的证据表明，小胶质细胞活化和白细胞浸润在脑缺血的致病级联中起着重要作用：细胞反应决定缺血诱导的组织损伤的程度，但也是恢复期间组织修复和再生所必需的。尽管已有大量的实验和临床研究集中在激活的小胶质细胞用于研究局灶性脑缺血后的神经炎症，但仍然缺乏准确、有效和非侵入性的方法来监测中风恢复期间小胶质细胞的功能改变。我们的初步结果表明，小胶质细胞的活动参与了恢复， 脑卒中后神经血管重塑过程中血脑屏障（BBB）的完整性，从早期促炎（M1）到后期抗炎和组织修复（M2）阶段。我们建议验证小胶质细胞的功能改变从经典的早期促炎激活转变为后期生长因子表达的假设 参与神经血管重塑在这项提案中，我们将专注于应用一种新的技术，MRI检测小胶质细胞为目标的，超顺磁性纳米粒子在大鼠大脑中，以评估中风恢复过程中的小胶质细胞功能激活的改变。在本项目中，我们提出以下两个具体目标：AIM 1在中风后7、14和28天，用MRI和与小胶质细胞生物标志物缀合的纳米颗粒监测大鼠缺血脑中活性小胶质细胞的动态分布概况，和AIM 2来研究小胶质细胞在中风后功能改变过程中的分子和细胞变化-用组织学和生物化学方法观察脑损伤和恢复情况。该提案将联合收割机结合使用与抗Iba-1抗体缀合的纳米颗粒作为小胶质细胞的标记物，并使用MR成像来非侵入性地监测中风后大脑中炎症和小胶质细胞功能改变的时间分布。虽然外周和成像生物标志物的使用增加了中风的体内诊断的特异性和灵敏度，但能够非侵入性地监测中风受试者脑中炎症的纵向发展将具有很大的临床相关性。MRI广泛应用于医学，并广泛应用于临床实践。因此，用于成像活体中风脑内的炎症反应的MRI方法可以被广泛应用，并且将这些研究领域开放给大量的体内定量研究，其中可以确定和比较治疗的功效。这项研究将为监测中风和其他神经退行性疾病的进展和治疗提供一种新的实验方法，以支持临床上的直接后续应用。此外，这些研究的成功完成将增强我们对小胶质细胞功能改变和卒中后神经血管重塑中关键炎症事件的作用的理解。

 DESCRIPTION (provided by applicant): Longitudinal monitoring of microglial activation after stroke with SPION-enhanced MRI ABSTRACT: Microglia are the brain-resident macrophages that form the first line of immunological defense in the brain. Emerging evidence indicates that microglial activation and leukocyte infiltration play a major role in the pathogenic cascades of cerebral ischemia: cellular reactions determine the extent of ischemia-induced tissue damage but are also necessary for tissue repair and regeneration during recovery. Despite the existence of a number of prior experimental and clinical studies focusing on activated microglia for the study of neuroinflammation after focal cerebral ischemia, an accurate, efficacious, and non-invasive method for monitoring the functional alteration of microglia during stroke recovery is stil lacking. Our preliminary results suggest that microglial activity is involved in the restoration of the integrity of the blood-brain barrier (BBB) during neurovascular remodeling after stroke at all stages, ranging from the early pro-inflammatory (M1) to the later anti-inflammatory and tissue repair (M2) stages. We propose to test the hypothesis that the functional alteration of microglia shifts from a classical early pro-inflammatory activation to the later expression of growth factors involved in neurovascular remodeling. In this proposal we will focus on applying a novel technique for MRI detection of microglial-targeted, superparamagnetic nanoparticles in rat brain to evaluate the alteration of microglia functional activation during stroke recovery. In this projet, we propose the following two specific aims; AIM1 to monitor the dynamic distribution profile of active microglia in rat ischemic brain with MRI and nanoparticles conjugated with a biomarker to microglia at 7, 14, and 28 days after stroke, and AIM2 to study the molecular and cellular changes during functional alterations of microglia in response to stroke-induced brain injury and recovery with histological and biochemical approaches. This proposal will combine the use of nanoparticles conjugated to an anti-Iba-1 antibody as a marker of microglia with MR imaging to non-invasively monitor the temporal profile of inflammation and microglia functional alteration in the brain after a stroke. Although the use of peripheral and imaging biomarkers have increased the specificity and sensitivity of the in vivo diagnosis of stroke, it would be of great clinical relevance to be able to non-invasively monitor the longitudinal development of inflammation in the brain of stroke subjects. MRI is widely used in medicine and widely available in clinical practice. Thus, an MRI method for imaging the inflammatory response inside the living stroked brain could be widely applied and would open these research areas to a great number of quantitative investigations in vivo where the efficacy of treatments could be determined and compared. This research will provide a novel experimental approach for monitoring the progression and treatment of stroke and other neurodegeneration disorders in support of direct subsequent applications in the clinic. In addition, the successful completion of the proposed studies will enhance our understanding of the functional alteration of microglia and the role of the key inflammatory events in neurovascular remodeling following stroke.