Altered Copper Metabolism as Theranostic Biomarker in Alzheimer's Disease

描述(申请人提供)：本提案的目的是确定铜代谢改变作为阿尔茨海默病(AD)早期诊断和治疗的一种新的治疗生物标志物的可行性和用途。铜是哺乳动物必需的营养元素，但过量的铜会对细胞产生毒性。铜的动态平衡受到一个由铜转运体和伴侣组成的微妙网络的严格调控。ATP7B基因突变导致肝豆状核变性，这是一种遗传性铜代谢紊乱，其特征是肝脏和神经症状，原因是铜在肝脏和大脑中过度积累。越来越多的证据表明铜代谢改变在AD发病机制中的作用。然而，由于缺乏实时评估体内铜通量的工具，人们对人脑中的实时铜代谢知之甚少。正电子发射断层扫描(PET)是一种实时评估活体铜通量的通用工具。以64CuCl2为示踪剂的PET/CT显示，ATP7B-/-基因敲除小鼠肝组织中~(64)C的蓄积增加。我们对Tau转基因AD模型小鼠脑组织中铜的代谢进行了检测，发现Tau Tau-P301L突变转基因小鼠脑组织中64Cu放射性显著高于正常对照小鼠脑组织中64Cu放射性。初步实验数据提示，铜蓄积改变有可能成为PET/CT早期诊断AD的一种新的生物标志物。此外，铜代谢的改变有可能成为早期应用铜调节疗法治疗AD的治疗靶点。在此，我们提出了用64CuCl2作为放射性示踪剂的PET/CT(64CuCl2-PET/CT)对Tau-P301L突变转基因小鼠脑内铜代谢随年龄变化的纵向评估。此外，我们还将探索铜代谢改变作为铜调控治疗Tau-P301L突变转基因小鼠的治疗靶点的可能性。本研究的具体目的是：1.利用64CuCl2-PET/CT对Tau-P301L突变转基因小鼠脑内~(64)Cu放射性活度随年龄的变化进行纵向评价，以确定铜代谢改变作为AD早期诊断新的生物标志物的可行性。目的：以64CuCl2为放射性示踪剂，通过microPET/CT检测克隆喹酚对Tau-P301L基因突变转基因小鼠铜代谢的影响及对脑组织NFT负荷的组织化学分析，探讨铜调控治疗AD的可能性。本研究结果可能为阐明铜代谢异常在AD发病机制中的作用提供新的理论依据，确定64CuCl2-PET/CT用于AD早期诊断的可行性，为进一步研究铜代谢异常作为早期铜调控治疗AD的治疗靶点提供依据。此外，铜代谢的改变有可能作为替代生物标志物，通过以64CuCl2为放射性示踪剂的PET/CT来监测其他抗AD药物的治疗效果。

DESCRIPTION (provided by applicant): The purpose of this proposal is to determine feasibility and use of altered copper metabolism as a new theranostic biomarker for early diagnosis and treatment of Alzheimer's disease (AD). Copper is an essential nutrient element in mammals, but excess of copper is cytotoxic. Copper homeostasis is tightly regulated by a delicate network of copper transporters and chaperons. Mutation of ATP7B gene causes Wilson's disease, an inherited copper metabolism disorder characterized by hepatic and neurological symptoms due to harmful effect of excess copper accumulation in live and brain. Emerging body of evidence suggests role of altered copper metabolism in pathogenesis of AD. However, little is known about real-time copper metabolism in human brains due to lack of a tool for real-time assessment of copper fluxes in vivo. Positron emission tomography (PET) is a versatile tool for real-time assessment of copper fluxes in live organism. Increased accumulation of 64C was demonstrated in liver of Atp7b -/- knockout mice, a mouse model of Wilson's disease, by PET/CT using 64CuCl2 as a radiotracer. We assessed copper metabolism in brain of Tau transgenic mouse model of AD and discovered that 64Cu radioactivity in brain tissues of Tau Tau- P301L mutant transgenic mice was significantly higher than 64Cu radioactivity in brain tissue of normal control mice. The data of our preliminary experiments suggested potentials of altered copper accumulation as a new biomarker for early diagnosis of AD by PET/CT. Additionally, altered copper metabolism holds potential as a therapeutic target for early treatment of AD with copper modulating therapy. Herein, we propose longitudinal assessment of age-dependent change of copper metabolism in brain of Tau-P301L mutant transgenic mice by PET/CT using 64CuCl2 as a radiotracer (64CuCl2-PET/CT). In addition, we will explore potential of altered copper metabolism as a therapeutic target for copper modulating therapy in Tau-P301L mutant transgenic mice. Our specific aims of this proposal are: Aim 1. To determine the feasibility of altered copper metabolism as a new biomarker for early diagnosis of AD based on longitudinal assessment of age-dependent change of 64Cu radioactivity in brain of Tau-P301L mutant transgenic mice using 64CuCl2 -PET/CT. Aim 2: To explore the therapeutic potentials of copper-modulating therapy in AD by monitoring effects of clioquinol on altered copper metabolism and improvement of Tauopathological changes in Tau-P301L mutant transgenic mice by microPET/CT using 64CuCl2 as a radiotracer and histolochemical analysis of NFT burden in mouse brain tissues. Outcome of this study may shed new light on the role of altered copper metabolism in pathogenesis of AD related to Taupathology, determine feasibility of using 64CuCl2-PET/CT for early diagnosis of AD, and provide evidence to support further study of altered copper metabolism as a therapeutic target for early treatment of AD by copper modulating therapy. Furthermore, altered copper metabolism holds potentials as a surrogate biomarker for monitoring therapeutic effects of other anti-AD drugs targeting tauopathies by PET/CT using 64CuCl2 as a radiotracer.