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、生物学途径及其调控的基本理解。在本申请中，我们建议开发成像方法来评估哮喘的气道炎症。哮喘是一种气道慢性炎症性疾病，涉及细胞和介质的相互作用，导致高水平的活性氧和氮（ROS，RNS）。细胞内谷胱甘肽的增加是对ROS/RNS的响应，并且是细胞对氧化环境耐受性的关键决定因素。我们和其他人已经表明，谷胱甘肽在哮喘气道中增加，并且水平随着哮喘加重而急剧变化。在这里，我们假设使用放射性药物99 mTc-HMPAO（锝99 m-hexamethylpropylene amine oxime）和单光子发射计算机断层扫描（SPECT）评估谷胱甘肽，将识别和定位哮喘肺部的炎症区域。在GSH存在下，亲脂性99 mTc-HMPAO定量转化为亲水性非扩散形式，因此保留在组织内，导致SPECT上的摄取值更大。在目的1中，我们优化了SPECT-HMPAO扫描的方法，并确定了哮喘小鼠模型中HMPAO摄取与GSH水平的关系。在目的2中，我们确定了哮喘患者和健康对照之间99 mTc-HMPAO摄取的差异，并确定了过敏原急性哮喘反应后99 mTc-HMPAO摄取的时间变化。在目标3中，我们定量具有高与低HMPAO摄取的肺区域的支气管镜样本中的炎症和谷胱甘肽水平，以验证SPECT-HMPAO图像对应于炎症部位。总的来说，我们的目标是开发一种创新的和科学合理的非侵入性方法来评估哮喘的局部炎症。炎症成像将是一个重大的进展，与哮喘研究和哮喘患者的临床护理密切相关。 公共卫生相关性：哮喘是一种气道炎症综合征，导致肺部气流阻塞。虽然定义为气道慢性炎症，但炎症评估不是常规的，并且除了通过侵入性支气管镜检查外，目前无法评估局部气道炎症。本研究的目的是开发一种基于肺内代谢物化学活性的非侵入性成像方法，用于评估哮喘局部炎症。具体而言，总谷胱甘肽，一种经历可逆还原氧化的肽，由于与慢性炎症相关的氧化应激而在哮喘肺中增加。我们计划使用放射性药物99 mTc-HMPAO（锝99 m-hexamethylpropylene amine oxime）和单光子发射计算机断层扫描（SPECT）成像来评估肺谷胱甘肽，以识别和量化哮喘中的炎症区域。在还原型谷胱甘肽存在下，亲脂性99 mTc-HMPAO定量转化为亲水性非扩散形式，并保留在组织内。我们计划在小鼠哮喘模型和人类哮喘患者中评估HMPAO-SPECT成像。这项研究的发现将揭示哮喘发病机制的新知识，并有可能改变我们未来在哮喘中进行临床转化研究的方式。

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.