建立AD多探针MicroPET分子显像方法评价AAV1-Aβ-scFv治疗效果

The research on therapeutic drugs for Alzheimer’s disease (AD) has become hotspot currently, but the preclinical evaluation system remains suboptimal. PET molecular imaging,however, has not included in this system due to unsuitable animal models or molecular probes. Previously we obtained the anti-Aβ single chain antibody gene drug AAV1-Aβ-scFv, which can ameliorate cognitive function and pathological deterioration in animal models through intramuscular administration. But the effects of AAV1-Aβ-scFv on animal brain metabolism and τ protein pathological abnormality were unclear. Besides 18F-FDG for glucose imaging, this project develops novel positron probes 18F-FPA for propanoic acid tracing, 18F-T807 for hyperphosphated tau protein labeling, and 18F-AV45 for abnormal β amyloid deposition detecting. Based on these positron probes, the in vivo progressive changes of glucose metabolism, propanoic acid metabolism, hyperphosphated tau protein and abnormal deposition of β amyloid peptide in APP/PS1 transgenic mice and APP/PS1/τtransgenic rat brain are going to be investigated chronically by MicroPET imaging respectively, and multiple probes base MicroPET imaging method will be established. Further, multiple probes base MicroPET imaging method is employed to evaluate the therapeutic effect of AAV1-Aβ-scFv on animal AD. All data from this project is helpful to deepen understanding of AD pathogenesis and beneficial for therapeutic drugs of AD entering into clinical trials.

阿尔茨海默病(AD)治疗药物研究是当前热点，但临床前疗效评估体系不理想。PET分子显像因模型和探针的限制，未进入AD治疗药物临床前实验评估体系。我们前期研究获得基因治疗药物AAV1-Aβ-scFv，肌肉注射可以改善动物的认知功能障碍和病理指标，但对动物大脑内代谢受损、τ蛋白病理异常的作用不详。本研究首先在18F-FDG基础上，研制新型丙酸正电子探针18F-FPA、τ蛋白过磷酸化正电子探针18F-T807和β淀粉样肽异常沉积正电子探针18F-AV45；然后用MicroPET分别研究不同年龄APP/PS1转基因小鼠和APP/PS1/τ转基因大鼠AD模型大脑内葡萄糖代谢、丙酸代谢、τ蛋白过磷酸化和β淀粉样肽异常沉积的变化规律，建立AD多探针MicroPET分子显像方法；在此基础上评价AAV1-Aβ-scFv治疗动物AD的效果。实验结果将有助于加深AD发病机制的认识，推动AD治疗药物进入临床。

随着人口的老龄化，阿尔茨海默病的发病率越来越高，成为威胁人类健康和社会发展的主要疾病。目前对AD发病机制的认识非常有限，没有针对A D的有效治疗药物。可能是β淀粉样肽在大脑内的沉积驱动了AD的发生和发展，导致老年斑、神经纤维缠结和神经元死亡，最终患者表现出痴呆症状。.抗Aβ的单克隆抗体药物的发展经历了20年的研发，目前仍未能上市。其分子设计、药物临床前的实验动物评估指标有待改进。我们考虑抗体药物进入大脑后恒定区可能引起副作用，在药物设计时去除Fc段，得到Aβ-scFv。再通过腺相关病毒 （Adeno-associated virus，AAV）携带Aβ-scFv基因治疗给药（AAV-Aβ-scFv）促成抗体片断的持续表达，减少给药次数。随后制备肌肉注射血清1型重组AAV (AAV1)基因治疗药物 （AAV1-Aβ-scFv），抗体片段在肌肉分泌表达并进入血液循环系统，在外周形成网罗Aβ的 “陷阱”，促使大脑内Aβ向外周转移，保护神经元。最后建立一种更加精确和科学的AD药 物临床前的实验动物评估方法即多探针小动物正电子发射断层显像（MicroPET）来评价AAV1-Aβ-scFv的治疗效果。.本项目首先研制新型丙酸正电子探针18F-FPA、τ蛋白过磷酸化正电子探针18F-T807和β淀粉样肽异常沉积正电子探针18F-AV45；然后用MicroPET 分别研究不同年龄APP/PS1转基因小鼠和APP/PS1/τ转基因大鼠AD模型大脑内葡萄糖代谢、 丙酸代谢、τ蛋白过磷酸化和β淀粉样肽异常沉积的变化规律，在此基础上进一步评价 AAV1-Aβ-scFv治疗动物AD的效果。本项目开展的多探针MicroPET显像对于加深AD发病机制的认识，推动AD基因治疗药物的研究与改进具有重要意义。多探针MicroPET显像对其它AD治疗药物临床前疗效评价也具有借鉴意义。