靶向巨噬细胞的PET分子探针的合成及其在动脉粥样硬化斑块模型上的显像研究

Assessing the vulnerability of atherosclerotic (AS) plaque effectively, and therefore choosing appropriate intervention is very critical to the prognosis of CVD patients. Previous studies have shown that P2X7 receptores were over-expressed in monocyte and macrophages, which are closely related to the formation of AS plaques and inflammation in the plaque. The aim of this study is to synthesize molecular probes that target to activated P2X7 receptors on macrophages, namely 18F-P2X7R inhibitor. In addition, in order to evaluate the effects of P2X7 receptor imaging, this project will synthesize 18F labeled Duramycin, as an apoptotic molecular probe it can monitor the apoptosis of macrophages in plaque by targeting PE on cell membrane based on our previous research results. by click reaction. Based on the theory that infiltration and apoptosis of macrophage in AS plaque is in a dynamic state, and they also influence each other, mutually contributing to the formation of AS vulnerable plaque. Therefore, this study will apply the two kinds of novel molecular probes targeting the proliferation and apoptosis of macrophages, namely 18F-P2X7RI, 18F-Duramycin, to dynamically and synchronously monitoring the proliferation and apoptosis of AS plaques progress of ApoE-/- mouse model in different periods. Hopefully, the formation mechanism of rupured plaque will be clarified, and then benefiting the accuracy of diagnosis of vulnerable plaque.

如何有效评估动脉粥样硬化（AS）斑块的易损性，并基于此选择适时及合适的干预手段，对心血管疾病高危患者预后至关重要。研究显示P2X7受体在单核细胞及巨噬细胞膜表达较高，且与AS斑块的形成、斑块内炎症反应密切相关。本研究拟合成新型18F标记的P2X7受体抑制剂并进行相关显像评估。另外，由于AS斑块内的巨噬细胞浸润及凋亡处于动态变化状态，两者相互影响、共同作用于AS易损斑块的形成。为了验证P2X7受体显像的有效性，本项目将采用点击化学方法来合成18F标记Duramycin分子探针通过监测斑块内巨噬细胞凋亡情况开展双靶点显像。因此，本项目将有效结合巨噬细胞增殖和凋亡两类新型分子探针，即18F-P2X7RI和18F-Duramycin，用来在体动态同步监测AS进展不同时期ApoE-/-模型小鼠体内斑块的巨噬细胞增殖与凋亡情况，从而对AS易损斑块形成机制进一步深入研究，并期望提高易损斑块诊断的准确性。

心血管疾病是世界范围内死亡的主要原因，占全球年度死亡人数的 31%，其中，动脉粥样硬化（Atherosclerosis，AS）斑块的破裂及继发血栓形成是心血管急性缺血事件发生的主要原因，AS 斑块的形成和发展过程非常复杂。当 AS 斑块内有大量激活的巨噬细胞等免疫细胞浸润时，这些细胞会分泌多种蛋白水解酶使 AS 斑块纤维帽变薄促使 AS 斑块不稳定性增加，使其容易发生破裂导致血栓形成和阻塞管腔等一系列缺血性事件的发生。癫痫是一种由中枢神经系统功能混乱所导致的疾病，在全世界范围内有1～2 %的人口遭受着癫痫的困扰。小胶质细胞的激活是癫痫发生过程中神经炎症的一个典型特征，也是诊断或药理性预防癫痫的潜在目标。研究发现发现 P2X7 受体介导的炎症反应在 AS 斑块形成和癫痫发生发展过程中起到关键作用。本研究制备了具有高纯度、高稳定性、高生物亲和力的18F-PTTP和18F-FTTM，对外周炎症模型、肺癌模型、 ApoE-/-基因敲除AS易损斑块模型鼠和癫痫大鼠模型进行活体 PET/CT显像，以探讨其用于炎症和肿瘤鉴别诊断、动脉粥样硬化斑块不稳定性的评估和癫痫病灶P2X7受体表达量监测。并通过体外病理、油红染色以及体外荧光成像进一步验证其靶向性。研究发现18F-PTTP可鉴别小鼠模型外周炎症和肺癌、18F-FTTM可用于监测、评估动脉粥样硬化易损斑块和癫痫灶P2X7受体表达水平。

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