Near infrared fluorescence imaging of reactive oxygen species in Alzheimer's disease

阿尔茨海默病(AD)是一种不可逆转的神经退行性疾病，其进展密切相关 与氧化应激有关。长期以来，人们一直推测，体内的活性氧物种(ROS)水平 AD脑中的AD值远高于健康人脑。然而，来自生物的证据很少。研究 提示一个恶性循环围绕着淀粉样β蛋白(Aβ)和Tau的产生/聚集，小胶质细胞 反应、炎症反应和ROS的产生。在这个循环中，ROS物种扮演着核心角色。许多 临床试验表明，药物可以有效地与Aβ结合并消除Aβ斑块，但没有一项试验 已经显示出明显的改善认知的好处。尽管如此，尚不清楚AβS的撤职能否 导致治疗过程中脑组织ROS水平的变化。从根本上批判性地回答这些问题 重要问题，在此应用中，我们建议使用近红外荧光(NIRF)成像来 在临床前动物模型中监测活体AD脑中ROS在疾病进展和治疗过程中的变化。 受发光棒化学原理的启发，我们设计了一种近红外探测器CRANAD-61 罗斯。在荧光棒中，草酸酯与过氧化氢反应产生化学发光。在CRANAD-61中，草酸盐 部分被用来与ROS反应，从而产生波长漂移。我们的体外数据 结果表明，CRANAD-61对各种ROS高度敏感，反应迅速。在与 ROS，它的激发和发射波长发生显著变化，这种变化可以被利用 双波长成像。我们首次发现，阿尔茨海默病患者大脑中ROS水平随年龄增长而增加 可以用我们的近红外成像方法进行监测。 在这一应用中，我们建议通过将激发/发射扩展到 使其适用于近红外窗口中的双波长成像。然后，我们将使用优化的探测器来 监测转基因小鼠阿尔茨海默病进展过程中及A-β治疗过程中ROS的变化 抗体。我们将调查降低β的治疗是否可以导致ROS的减少，以及 AD应考虑β降低与抗氧化或抗炎治疗相结合 治疗。我们研究的答案将改进和指导AD治疗方案的范例。

Alzheimer's disease (AD) is an irreversible neurodegenerative disorder, whose progression is closely associated with oxidative stress. It has long been speculated that the reactive oxygen species (ROS) level in AD brains is much higher than that in healthy brains. However, evidence from living beings is rare. Studies suggest that a vicious cycle revolves around amyloid beta (Aβ) and Tau production/aggregation, microglia responses, inflammatory responses, and ROS production. In this cycle, ROS species play a central role. Many clinical trials indicate that drugs can effectively engage with Aβ and remove Aβ plaques, but none of the trials have shown clear benefits of improving cognition. Nonetheless, it is not clear whether the removal of Aβs can lead to the changes of ROS levels in brains during the therapy. To answer these fundamental and critically important questions, in this application, we propose to use Near Infrared Fluorescence (NIRF) imaging to monitor ROS changes in living AD brains during disease progression and therapy in preclinical animal models. Inspired by the chemistry of glow sticks, we have designed a NIRF probe, termed CRANAD-61 for detecting ROS. In glow sticks, oxalate esters react with H2O2 to produce chemiluminescence. In CRANAD-61, an oxalate moiety was utilized to react with ROS and to consequentially produce wavelength shifting. Our in vitro data showed that CRANAD-61 was highly sensitive and rapidly responsive to various ROS. Upon reacting with ROS, its excitation and emission wavelengths significantly shifted, and this shifting could be harnessed for dual-wavelength imaging. We showed that, for the first time, age-related increases in ROS levels in AD brains could be monitored with our NIRF imaging method. In this application, we propose to further structurally optimize CRANAD-61 by extending excitation/emission to make them suitable for dual-wavelength imaging in the NIR window. We will then use the optimized probe to monitor the changes of ROS during the progression of AD in transgenic mice, and during therapy with an Aβ antibody. We will investigate whether Aβ-lowering treatment can lead to a decrease of ROS, and whether a combination of Aβ-reduction and anti-oxidant or anti-inflammation therapies should be considered for AD treatment. The answers from our studies will improve and guide the paradigm of AD therapy regimens.