Noninvasive imaging of eosinophils

虽然他们只占哮喘患者的一小部分，但严重难治性哮喘(SRA)患者占与哮喘治疗相关的医疗费用的近一半。SRA似乎是一组具有不同亚型的异质性疾病，其特点是不同程度的粒细胞受累。这些不同的亚型可能解释了为什么有很大一部分SRA患者对吸入皮质类固醇治疗(ICS)没有反应。阳性反应的可能性似乎随着嗜酸性粒细胞的参与而增加；因此，确定粒细胞受累的类型，中性粒细胞和/或嗜酸性粒细胞，可能是重要的诊断辅助。目前，粒细胞鉴定是通过测量平均嗜酸性粒细胞含量来进行的，包括诱导痰或灌洗液分析。这两种技术都只提供了对肺部平均细胞负荷的估计，无法提供有关细胞密度或定位的具体信息。 我们的实验室在体内成像分子探针的开发方面拥有丰富的经验，在这项工作中，我们建议开发专门针对嗜酸性粒细胞的探针，以便能够在体内三维可视化炎症性哮喘中的嗜酸性粒细胞。我们将开发可通过正电子发射断层扫描(PET)的高灵敏度成像技术检测到的探针，并将这些探针应用于已知具有强大嗜酸性粒细胞反应的炎症性哮喘动物模型(卵白蛋白小鼠)。将开发针对嗜酸性粒细胞表面标志物Siglec-8的探针。探针将在溶液和细胞培养模型中进行评估，然后应用于哮喘卵清蛋白动物模型中的嗜酸性粒细胞成像。我们与一位在生产这些小鼠方面经验丰富的合作调查员合作，他们将进行组织学研究，以确认成像结果与动物体内嗜酸粒细胞定位的实际模式相匹配。体内细胞分布和密度的可视化将使我们更详细地了解这些细胞驻留在哪里，而不是简单的痰细胞计数；识别活性细胞在SRA中持续存在的位置，无论是在肺部还是在全身，可能会更好地理解为什么一些患者对治疗无效。基于细胞的成像有可能在未来取代更具侵入性的活组织检查。此外，嗜酸性粒细胞作为治疗干预的潜在靶点也引起了人们的兴趣。体内细胞成像的能力可以帮助设计治疗以及监测治疗的有效性。

Although they represent only a small fraction of asthma sufferers, patients with severe refractory asthma (SRA) account for nearly half of healthcare costs relating to asthma treatment. SRA appears to be a heterogeneous set of diseases with different subtypes, characterized by differential levels of granulocyte involvement. These different subtypes may account for why a significant subgroup of SRA patients does not respond to inhaled corticosteroid therapy (ICS). The potential for positive response appears to increase with eosinophil involvement; therefore, identification of the type of granulocyte involvement, neutrophil and/or eosinophil, can be an important diagnostic aid. Currently, granulocyte identification is performed by measures of average eosinophil content, including induced sputum or lavage analysis. Both techniques provide only an estimate of the average cell burden in the lungs and cannot give specific information about cell densities or localization. Our lab has extensive experience in the development of molecular probes for in vivo imaging, and in this work, we propose to develop probes specific for eosinophils to allow three-dimensional, in vivo visualization of eosinophils in inflammatory asthma. We will develop probes detectable by the highly sensitive imaging technique of Positron Emission Tomography (PET) and apply these to an animal model of inflammatory asthma (ovalbumin mouse) known to possess to a robust eosinophil response. Probes will be developed that are targeted to Siglec-8 a surface marker on eosinophils. Probes will be assessed in solution and cell culture models, then applied to image eosinophils in the ovalbumin animal model of asthma. We partner with a co-investigator experienced in the production of these mice who will perform histology to confirm that the imaging results match the actual pattern of eosinophil localization in the animal. The visualization of cell distribution and density in vivo will give us a more detailed understanding o where these cells reside compared to simple sputum cell counts; and identifying where active cells persist in SRA, both in the lung and systemically could lead to a better understanding of why some patients are refractory to treatment. Cell-based imaging has the potential to replace more invasive biopsies in the future. In addition, eosinophils have garnered interest as a potential target for therapeutic intervention. The ability to image the cells in vivo can aid in design of therapy as well as in monitoring the effectiveness of therapy.