Imaging Inflammation in Asthma

描述(由申请人提供)：本申请涉及广泛的挑战领域(06)：使能技术和特定的挑战主题，06-HL-103：开发新的成像方法来跟踪细胞，并准确测量完整细胞、组织和生物体中酶和代谢物的化学活性，以提高对细胞相互作用、生物途径及其调节的基本了解。在这一应用中，我们建议开发成像方法来评估哮喘的呼吸道炎症。哮喘是一种慢性呼吸道炎症性疾病，涉及细胞和介质的相互作用，导致高水平的活性氧和氮物种(ROS，RNS)。细胞内谷胱甘肽的增加是对ROS/RNS的一种反应，是细胞对氧化环境耐受性的关键决定因素。我们和其他人已经证明，哮喘呼吸道中的谷胱甘肽水平会增加，而且随着哮喘的加重，谷胱甘肽的水平会急剧变化。在这里，我们假设，使用放射性药物99mTC-HMPAO(技术99m-六甲基丙二胺肟)和单光子发射计算机断层扫描(SPECT)对谷胱甘肽的评估将识别和定位哮喘肺部的炎症区域。在GSH存在下，亲脂性99mTC-HMPAO定量转化为亲水的不可扩散形式，并因此保留在组织内，从而在SPECT上获得更大的摄取值。在目标1中，我们优化了SPECT-HMPAO扫描方法，并在哮喘小鼠模型中确定了HMPAO摄取与GSH水平的关系。在目标2中，我们确定了哮喘患者和健康对照组对99mTC-HMPAO摄取的差异，并确定了哮喘对变应原急性反应后摄取99mTC-HMPAO的时间变化(S)。在目标3中，我们对肺部高摄取和低摄取区域的支气管镜样本中的炎症和谷胱甘肽水平进行定量，以验证SPECT-HMPAO图像与炎症部位相对应。总体而言，我们的目标是开发一种创新的、科学合理的非侵入性方法来评估哮喘的局部炎症。炎症成像将是一项重要的进步，与哮喘研究和潜在的哮喘患者的临床护理密切相关。 与公共卫生相关：哮喘是一种呼吸道炎症综合征，导致肺部气流受阻。虽然被定义为慢性呼吸道炎症，但炎症评估并不是常规的，目前只有通过侵入性支气管镜检查才能评估区域性呼吸道炎症。我们在这项研究中的目标是开发一种基于肺内代谢物化学活动的非侵入性成像方法，用于评估哮喘的局部炎症。具体地说，总谷胱甘肽，一种经历可逆还原氧化的肽，在哮喘肺中由于与慢性炎症相关的氧化应激而增加。我们计划使用放射性药物99mTC-HMPAO(Technetium99m-六甲基丙烯胺肟)和单光子发射计算机断层扫描(SPECT)成像来评估肺谷胱甘肽，以识别和量化哮喘的炎症区域。在还原型谷胱甘肽存在下，亲脂性99mTC-HMPAO定量转化为亲水的不可扩散形式，并保留在组织中。我们计划在小鼠哮喘模型和人类哮喘患者模型中评估HMPAO-SPECT成像。这项研究的发现将揭示哮喘发病机制的新知识，并可能改变我们未来对哮喘进行临床翻译研究的方式。

DESCRIPTION (provided by applicant): This application addresses broad Challenge Area (06): Enabling Technologies and specific Challenge Topic, 06-HL-103: Develop new imaging methodologies to track cells and measure accurately the chemical activities of enzymes and metabolites in intact cells, tissues, and organisms to improve basic understanding of cellular interactions, biological pathways, and their regulation. In this application we propose to develop imaging methods to assess airway inflammation in asthma. Asthma is a chronic inflammatory disorder of the airways involving interaction of cells and mediators, which result in high levels of reactive oxygen and nitrogen species (ROS, RNS). Increase of intracellular glutathione is a response to ROS/RNS, and a critical determinant of cellular tolerance to oxidizing environments. We and others have shown that glutathione is increased in asthmatic airways and that levels change acutely with asthma exacerbations. Here, we hypothesize that assessment of glutathione using the radiopharmaceutical 99mTc-HMPAO (Technetium99m-hexamethylpropylene amine oxime) and single photon emission computed tomography (SPECT), will identify and localize regions of inflammation in asthmatic lungs. The lipophilic 99mTc-HMPAO is quantitatively converted to a hydrophilic nondiffusible form in the presence of GSH and thus retained within tissues leading to greater uptake values on SPECT. In aim 1, we optimize methods for SPECT-HMPAO scanning and determine the relationship of HMPAO uptake to GSH levels in a murine model of asthma. In aim 2, we identify differences in 99mTc- HMPAO uptake among asthmatics and healthy controls, and determine the temporal change(s) in 99mTc- HMPAO uptake following an acute asthmatic response to allergen. In aim 3, we quantitate inflammation and glutathione levels in bronchoscopic samples of lung regions that have high vs. low HMPAO uptake in order to validate that the SPECT-HMPAO image corresponds to sites of inflammation. Overall, our goal is to develop an innovative and scientifically sound noninvasive method for evaluation of regional inflammation in asthma. Inflammation imaging would be a significant advance highly relevant for asthma research and potentially the clinical care of asthmatic patients. PUBLIC HEALTH RELEVANCE: Asthma is a syndrome of airway inflammation that leads to obstruction of airflow to the lungs. Although defined as chronic inflammation of the airways, assessment of inflammation is not routine, and evaluation of regional airway inflammation is not currently possible except by invasive bronchoscopy. Our goal in this study is to develop a noninvasive imaging method based on chemical activities of metabolites in the lung for evaluation of regional inflammation in asthma. Specifically, total glutathione, a peptide that undergoes reversible reduction oxidation, is increased in asthmatic lungs due to the oxidative stress associated with chronic inflammation. We plan to assess lung glutathione using the radiopharmaceutical 99mTc-HMPAO (Technetium99m-hexamethylpropylene amine oxime) and single photon emission computed tomography (SPECT) imaging to identify and quantify regions of inflammation in asthma. The lipophilic 99mTc-HMPAO is quantitatively converted to a hydrophilic nondiffusible form in the presence of reduced glutathione and retained within tissues. We plan to evaluate HMPAO-SPECT imaging in murine models of asthma and human asthmatics. The discoveries from this study will reveal new knowledge of asthma pathogenesis and are likely to transform how we perform clinical-translational research studies in asthma in the future.