Imaging Activated Macrophages in the Lungs

描述(由申请人提供)：肺巨噬细胞对于启动对微生物和环境刺激的先天免疫反应、化解急性炎症和促进损伤后的修复至关重要。持续或失调的巨噬细胞激活在多种肺部疾病的发病机制中起着重要作用；然而，研究人类肺部疾病中多效性巨噬细胞群体的表型是复杂的，因为目前需要侵入性方法来获得足够数量的细胞。开发非侵入性识别激活的巨噬细胞的新方法可以促进对炎症性肺部疾病的更好的理解和治疗选择。炎症部位的巨噬细胞亚群表达高水平的叶酸受体？(Fr？)我们在小鼠身上的初步数据表明，FR？在正常的、静止的肺中不表达，但在气管内或全身用大肠杆菌脂多糖(LPS)治疗后，在一小部分巨噬细胞中表达上调。我们还鉴定了FR？在小鼠支气管肺发育不良(BPD)、肺纤维化和慢性阻塞性肺疾病(COPD)模型中肺巨噬细胞的表达。此外，我们发现COPD、特发性肺纤维化(IPF)和BPD患者的肺巨噬细胞表达FR？，而健康人的巨噬细胞表达极少。基于这种受体的表达，我们发现我们可以使用叶酸衍生物与荧光探针结合来成像小鼠肺中激活的巨噬细胞。在这项提议中，我们假设发展分子成像技术来识别激活的巨噬细胞的功能亚群将促进对炎症性肺部疾病的了解，并可能导致新的巨噬细胞靶向治疗。虽然我们的初步研究使用了光学成像技术，但为了适用于人类，我们计划开发正电子发射断层扫描(PET)技术来对激活的肺巨噬细胞成像。具体目标是：1)识别和表征活化的肺巨噬细胞上存在的特定细胞表面标志物，2)验证临床前成像方法以显示体内巨噬细胞的激活，以及3)开发基于PET的体内活化肺巨噬细胞成像的策略。总之，这些研究将优化基于FR？的成像探针。表达并探索存在于激活的巨噬细胞表面的新的成像靶点。然后，这些新策略可以应用于人类炎症性肺部疾病的研究。 公共卫生相关性：肺巨噬细胞在炎症性肺部疾病的发病机制中起关键作用。使用非侵入性方法对激活的巨噬细胞进行成像将允许频繁监测疾病进展和治疗反应。此外，可以开发识别激活的巨噬细胞的新方法，作为巨噬细胞靶向治疗的平台。因此，新的成像策略可以促进我们对儿童和成人肺部疾病的理解和最终的治疗。(摘要结束)

DESCRIPTION (provided by applicant): Lung macrophages are critical for initiating the innate immune response to microbial and environmental stimuli, resolving acute inflammation, and promoting repair following injury. Persistent or dysregulated macrophage activation plays an important role in the pathogenesis of multiple lung diseases; however, studying the phenotype of the pleiotropic macrophage population in human lung disease is complicated by the invasive methods currently required to obtain sufficient quantities of cells. Development of new methodologies to non- invasively identify activated macrophages could facilitate improved understanding and treatment options for inflammatory lung diseases. A subset of macrophages at sites of inflammation expresses high levels of the folate receptor ? (FR?). Our preliminary data in mice demonstrate that FR? is not expressed in normal, quiescent lungs but is up-regulated specifically in a subset of macrophages after intratracheal or systemic treatment with E. coli lipopolysaccharide (LPS). We also identified FR? expression in lung macrophages in mouse models of bronchopulmonary dysplasia (BPD), lung fibrosis, and chronic pulmonary obstructive disease (COPD). Further, we found that lung macrophages from humans with COPD, idiopathic pulmonary fibrosis (IPF), and BPD express FR?, whereas expression in healthy human macrophages is minimal. Based on expression of this receptor, we have found that we can image activated macrophages in mouse lungs using a folate derivative conjugated with a fluorescent probe. In this proposal, we hypothesize that developing molecular imaging techniques to identify functional subsets of activated macrophages will advance understanding of inflammatory lung diseases and could lead to novel, macrophage-targeted therapies. Although our preliminary studies have employed optical imaging techniques, for applicability to humans we plan to develop positron emission tomography (PET) techniques to image activated lung macrophages. Specific aims are to: 1) identify and characterize specific cell-surface markers present on activated lung macrophages, 2) validate pre-clinical imaging approaches to visualize macrophage activation in vivo, and 3) develop PET-based strategies for imaging activated lung macrophages in vivo. Together, these studies will optimize imaging probes based on FR? expression and explore new imaging targets present on the surface of activated macrophages. These new strategies can then be applied to the study of inflammatory lung diseases in humans. PUBLIC HEALTH RELEVANCE: Lung macrophages are key players in the pathogenesis of inflammatory lung diseases. Imaging activated macrophages using a non-invasive approach would allow frequent monitoring of disease progression and treatment response. In addition, new methodologies to identify activated macrophages could be developed as a platform for macrophage-targeted therapies. Thus, new imaging strategies could advance our understanding and eventually treatment of both pediatric and adult lung disease. (End of Abstract)