Imaging DTH, IFN gamma responses & GA in human arteries

人动脉迟发型变态反应、干扰素-γ反应和GA的成像移植物动脉硬化(GA)是心脏移植术后移植物晚期失败的主要原因。目前尚不存在可靠的非侵入性检测GA的工具，特别是其早期形式。常规进行冠状动脉造影术和心肌灌注成像，但对早期疾病的检测准确性有限。然而，检测到的新生内膜并不能预测临床病程。该项目的总体目标是根据免疫发病机制，开发非侵入性的、基于核成像的早期GA检测方法。我们的方法将与项目1和2的假设密切相关，即TH1细胞是GA反应的有力刺激因子，其机制是通过产生干扰素-γ，进而诱导趋化因子的产生、生长因子受体的表达和平滑肌细胞(SMC)的激活/增殖。我们最近建立了小动物成像模型，以病理状态下的调制膜标记为靶点，包括小鼠的动脉损伤模型。目前的具体建议包括：(1)定义已知的、精心选择的候选靶分子的表达水平，包括CXCR3和CCR5(T细胞)、PDGFbeta-R、Alphavbeta3和VCAM-1(内皮细胞和SMC)、IP-10和Mig(分泌)，在(A)细胞培养、(B)器官培养、(C)人到小鼠血管移植节段的SCID小鼠模型中，以及(D)慢性血管排斥的人标本；(2)利用多肽噬菌体展示文库和生物扫描，在体外、体外和体内筛选新的潜在成像配体，将噬菌体生物扫描定向到相同光谱的免疫激活细胞/组织；(3)标记选定的配体(抗体、多肽和其他小分子)，并利用放射免疫分析和放射自显影技术确定其体外和体内的药理学性质；以及(4)使用上文1-3中选择的有限数量的放射性示踪剂，在人动脉移植到SCID小鼠模型中进行基于伽玛相机的体内成像。明确的靶向成像方法将是未来以患者为基础的研究的基础。最终，检测GA早期致病特征的能力可能提供预后数据，并为移植患者的治疗产生新的范例。

Imaging DTH, IFN-gamma Responses and GA in Human Arteries. Graft arteriosclerosis (GA) is the major cause of late graft failure in cardiac transplantation. Reliable non-invasive tools for the detection of GA, specifically in its early form, do not currently exist. Coronary angiography and myocardial perfusion imaging are routinely performed but have limited detection accuracy for early disease. However, the detected neointima is not predictive of the clinical course. The overall goal of this project is to develop non-invasive, nuclear imaging-based modalities for early GA detection, based upon the immunopathogenesis. Our approaches will be closely linked to the Project 1 and 2 hypotheses, that TH1 cells are potent stimulators of the GA response through the elaboration of IFN-gamma which in turn, induces chemokine production, growth factor receptor expression and smooth muscle cell (SMC) activation/proliferation. We have recently established small animal imaging models which target modulated membrane markers in pathologic states, including an arterial injury model in mice. Specific proposals now include: (1) to define expression levels of known, carefully chosen candidates target molecules, including CXCR3 and CCR5 (T cells), PDGFbeta-R, alphavbeta3 and VCAM-1 (endothelial cells and SMC), IP- 10 and Mig (secreted), on CD4+ TH1 cells, IFN-gamma activated SMC and EC, in (a) cell culture, (b) organ culture, (c) human-to-mouse vascular transplant segments in a SCID mouse model, and (d) human specimens of chronic vascular rejection; (2) to select novel potential imaging ligands using a peptide phage display library and biopanning, in vitro, ex vivo, and in vivo, directing the phage biopanning at the same spectrum of immune-activated cells/tissues; (3) to radiolabel chosen ligands (antibodies, peptides and other small molecules) and determine their pharmacologic properties both in vitro and in vivo, using radioimmunoassays and autoradiography; and (4) to perform gamma camera-based in vivo imaging in the human arterial transplant to SCID mouse model, using a limited number of radiotracers selected in 1-3, above. Defined targeted imaging approaches will be the foundation for patient-based studies in the future. Ultimately, the ability to detect early pathogenetic features of GA may provide prognostic data and generate a new paradigm for treatment of transplant patients.