Imaging and Treating Inflammation in Stroke by Targeting Myeloperoxidase

描述（由申请人提供）：卒中的治疗仅限于几种获批的治疗选择，如溶栓治疗，这些治疗必须在严格的短时间内进行，导致许多患者被排除在外。超过这个时间范围，有效的治疗选择就更少了。因此，扩展现有疗法和开发新的治疗选择将是非常可取的。已知炎症会延长缺血性脑损伤并对预后产生不利影响。尽管抗炎疗法在实验模型中可能有效，但迄今为止，人体试验尚未显示出明显的益处。虽然这种差异可能是多因素的，但一个促成因素可能与使用广泛的抗炎剂有关，而不是更集中的治疗，这些治疗针对特定的分子途径和酶，这些分子途径和酶被证明是有害的，同时保持炎症反应的有益作用。评估和实施新型抗炎治疗中风的一个主要障碍是缺乏一种非侵入性手段来跟踪中风期间炎症的演变，以观察靶向治疗在体内动物模型和人体中的影响。髓过氧化物酶（MPO）是一种由许多活化的炎症细胞分泌的高度氧化和破坏性酶，在中风病变中大量存在。我们已经表明，MR成像剂，双-5 HT-DTPA-Gd（MPO-Gd）是高度敏感和特异性检测MPO活性。我们发现，MPO-Gd成像可以报告和连续跟踪MPO活性，以获得以前只能从体外研究中获得的信息。MPO-Gd成像结果与梗死体积相关性良好，即使在闭塞后21天也能检测到梗死中的MPO活性。在初步研究中，用MPO抑制剂处理的野生型小鼠以及MPO缺陷型小鼠在第21天梗死体积显示出显著减少。因此，我们假设分泌型MPO是炎症和梗死蔓延的关键生物标志物，降低MPO活性将改善卒中结局。该提案的总体目标是研究MPO和炎症在卒中进展中的关系，并开发治疗方案，通过调节MPO活性/表达并结合溶栓治疗来限制炎症损伤。具体目标是：1）建立MPO作为卒中炎症的成像生物标志物，2）评估MPO作为卒中治疗靶点，3）确定MPO抑制和溶栓治疗之间的协同治疗方案。拟议的研究将提供一个平台，用于MPO分子成像在未来的研究中风炎症的基本病理生物学和旨在改变炎症的新的治疗干预措施的影响。最终，该提案的结果将为转化项目奠定基础，通过提供一种非侵入性方法来评估中风期间的炎症状态，改善对动物和人类新型抗炎疗法的评估，并为中风提供新的治疗靶点，从而使中风患者受益。 公共卫生相关性：由于MPO-Gd是高度稳定的，无毒的，并可用于成像MPO活性在广泛的临床重要的炎症性疾病，这些研究可能提供的MPO成像的应用基础，用于诊断评估人类炎症和MPO抑制新的治疗干预措施，以改善中风和其他疾病的结果。

DESCRIPTION (provided by applicant): Treatment of stroke is limited to a few approved therapeutic options, such as thrombolytic therapy, that have to be administered within rigid short timeframes resulting in the exclusion of many patients. Beyond the this timeframe even fewer effective treatment options exist. Therefore, extending current therapies and developing new treatment options would be highly desirable. Inflammation has been known to extend ischemic brain injury and adversely affect outcome. Although anti-inflammatory therapies can be effective in experimental models, thus far human trials have not shown a clear benefit. While the discrepancy is likely multifactorial, one contributing factor may be related to the use of broad anti-inflammatory agents rather than more focused therapies that target specific molecular pathways and enzymes demonstrated to be deleterious while maintaining the beneficial effects of the inflammatory response. A central obstacle in evaluating and implementing novel anti-inflammatory therapies for stroke is the lack of a noninvasive means to track the evolution of inflammation during stroke to observe the impact of targeted therapies in in vivo animal models and humans. Myeloperoxidase (MPO), a highly oxidizing and damaging enzyme secreted by many activated inflammatory cells, is found abundantly in stroke lesions. We have shown that the MR imaging agent, bis-5HT- DTPA-Gd (MPO-Gd) is highly sensitive and specific for detecting MPO activity. We found that MPO-Gd imaging can report and serially track MPO activity to obtain information that was previously only available from ex vivo studies. MPO-Gd imaging results correlated well with infarct volume and detected MPO activity in the infarct even 21 days post occlusion. In preliminary studies, wild-type mice treated with an MPO inhibitor as well as MPO deficient mice demonstrated substantial decrease in day 21 infarct volume. Therefore, we hypothesize that secreted MPO is a key biomarker for inflammation and infarct propagation, and that reducing MPO activity would improve stroke outcome. The overall goals of this proposal are to study the relationship between MPO and inflammation in stroke evolution and to develop treatment regimens to limit the inflammatory damage by modulating MPO activity/expression and in combination with thrombolytic therapy. The specific aims are 1) to establish MPO as an imaging biomarker for inflammation in stroke, 2) to assess MPO as a treatment target for stroke, and 3) to determine synergistic treatment regimens between MPO inhibition and thrombolytic therapy. The proposed investigations will provide a platform for the use of MPO molecular imaging in future investigations of basic pathobiology of inflammation in stroke and the impact of novel therapeutic interventions aimed at altering inflammation. Ultimately, the results of this proposal will set the stage for translational projects to benefit stroke patients by providing a noninvasive method to assess the inflammatory status during stroke, improving assessment of novel anti-inflammatory therapies in animals and in humans, and offering a new treatment target for stroke. PUBLIC HEALTH RELEVANCE: Because MPO-Gd is highly stable, nontoxic, and can be used to image MPO activity in a a wide range of clinically important inflammatory diseases, these investigations may provide the basis for application of MPO imaging for diagnostic evaluation of inflammation in humans and MPO inhibition for novel therapeutic interventions to improve outcome in stroke and other diseases.