Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital/Harvard Medical School, Room 2301, Building 149, Charlestown, Boston, Massachusetts 02129,United States.
School of Engineering, China Pharmaceutical University, Nanjing 210009, China.
Anal Chem. 2023 Sep 26;95(38):14261-14270. doi: 10.1021/acs.analchem.3c02358. Epub 2023 Sep 15.
Bioluminescence imaging has changed the daily practice of preclinical research on cancer and other diseases over the last few decades; however, it has rarely been applied in preclinical research on Alzheimer's disease (AD). In this Article, we demonstrated that bioluminescence imaging could be used to report the levels of amyloid beta (Aβ) species in vivo. We hypothesized that AkaLumine, a newly discovered substrate for luciferase, could bind to Aβ aggregates and plaques. We further speculated that the Aβ aggregates/fibrils/plaques could be considered as "functional amyloids", which have a reservoir function to sequester and release AkaLumine to control the bioluminescence intensity, which could be used to report the levels of Aβs. Our hypotheses have been validated via in vitro solution tests, mimic studies with brain tissues and mice, two-photon imaging with AD mice, and in vivo bioluminescence imaging using transgenic AD mice that were virally transduced with AkaLuciferase (AkaLuc), a new luciferase that generates bioluminescence in the near-infrared window. As expected, compared to the control group, we observed that the Aβ group showed lower bioluminescence intensity due to AkaLumine sequestering at early time points, while higher intensity was due to AkaLumine releasing at later time points. Lastly, we demonstrated that this method could be used to monitor AD progression and the therapeutic effectiveness of avagacestat, a well-studied gamma-secretase inhibitor. Importantly, a good correlation ( = 0.81) was established between in vivo bioluminescence signals and Aβ burdens of the tested AD mice. We believe that our approach can be easily implemented into daily imaging experiments and has tremendous potential to change the daily practice of preclinical AD research.
生物发光成像是过去几十年中癌症和其他疾病的临床前研究的日常实践发生了改变的主要因素；然而，它在阿尔茨海默病（AD）的临床前研究中很少被应用。在这篇文章中，我们证明了生物发光成像可以用于体内报告淀粉样β（Aβ）物质的水平。我们假设，AkaLumine，一种新发现的荧光素酶底物，可以与 Aβ 聚集体和斑块结合。我们进一步推测，Aβ 聚集体/原纤维/斑块可以被认为是“功能性淀粉样蛋白”，它们具有储库功能，可以隔离和释放 AkaLumine 来控制生物发光强度，从而可以用于报告 Aβ 的水平。我们的假设已经通过体外溶液测试、脑组织和小鼠的模拟研究、AD 小鼠的双光子成像以及使用经病毒转导 AkaLuciferase（AkaLuc）的转基因 AD 小鼠的体内生物发光成像得到验证，AkaLuc 是一种在近红外窗口产生生物发光的新型荧光素酶。正如预期的那样，与对照组相比，我们观察到 Aβ 组在早期时间点由于 AkaLumine 被隔离而表现出较低的生物发光强度，而在稍后的时间点由于 AkaLumine 释放而表现出较高的强度。最后，我们证明该方法可用于监测 AD 的进展和 avagacestat 的治疗效果，avagacestat 是一种研究充分的γ-分泌酶抑制剂。重要的是，在体内生物发光信号与测试 AD 小鼠的 Aβ 负担之间建立了良好的相关性（=0.81）。我们相信，我们的方法可以很容易地应用于日常成像实验中，并具有极大的潜力改变 AD 的临床前研究的日常实践。
