动脉粥样硬化斑块OxHDL靶向MRI/NIRF多模态分子成像及应用的实验研究

Atherosclerosis (AS) induced acute cardiovascular and cerebrovascular events is the leading cause of mortality and morbidity worldwide. The plasma level of oxidative modification of High-density lipoprotein (OxHDL) was significantly increased in the progression of AS and was an important biomarker of vulnerable atherosclerotic plaque. However, the relationship between OxHDL within plaque and plaque stability and the relationship between dynamic changes of OxHDL within plaque and the AS progression and stability, especially in the process of HDL- elevated therapy is still not entirely clear. We have established successfully a carotid artery plaque model of ApoE-/- mice in previous study and synthesized targeted Ultrasmall superparamagnetic iron oxide nanoparticles (USPIO) molecular imaging probes as well as imaged OxLDL and LOX-1 in vivo MRI (Wen S, J Lipid Res, 2012; Wen S, Nanomedicine: NBM, 2013). Based these preliminary studies, ultrasmall superparamagnetic iron oxide nanoparticles and Near-infrared fluorescence dye (cy5.5) have been bind to anti-human OxHDL monoclonal antibody to syntheses an OxHDL-targeted MR/NIRF molecular imaging probe and 7.0T Micro-MR and near-infrared imaging system of small animals are used for in vivo OxHDL-targeted MRI/NIRF imaging of carotid artery atherosclerotic lesions of apoE-/- mice, for demonstrating the dynamic changes of OxHDL in atherosclerotic lesions after pitavastatin, niacin or pitavastatin plus niacin therapy and exploring the relationship between OxHDL within plaque and AS in vivo, in order to investigate the role of statin, HDL- elevated drugs niacin and statin plus niacin in atherosclerosis as well as provide experimental evidences for clinical HDL-targeted therapy. As we known, it is the first attempt for OxHDL-targeted in vivo MRI/NIRF imaging of atherosclerosis.

动脉粥样硬化（AS）引发的急性心脑血管事件是世界首位的死亡及致残原因。氧化修饰的HDL（OxHDL）血浆水平在AS进展过程中明显升高，是易损斑块的重要biomarker。然而，斑块内OxHDL与斑块稳定性的关系、斑块内OxHDL的动态变化，尤其是在升HDL-C治疗过程的动态变化仍不完全清楚。本研究以OxHDL为靶点，通过构建OxHDL靶向MRI/NIRF双模态分子探针，用7.0T MR 和近红外成像系统对ApoE-/-小鼠颈动脉AS斑块进行MRI/NIRF活体成像，并比较匹伐他汀、烟酸或匹伐他汀与烟酸联合后斑块内OxHDL的变化，以期在活体条件下动态研究OxHDL 与AS 的关系，为探讨他汀、升HDL-C药物及他汀类与升HDL-C药物联合治疗对AS 斑块中OxHDL的作用，为临床HDL靶向治疗提供实验依据。这将是AS斑块OxHDL靶向MRI/NIRF多模态分子成像的首次尝试。

动脉粥样硬化（AS）引发的急性心脑血管事件是世界首位的死亡及致残原因。氧化修饰的HDL（OxHDL）血浆水平在AS进展过程中升高，是易损斑块的重要biomarker。然而，斑块内OxHDL与斑块稳定性的关系、斑块内OxHDL的动态变化，尤其是在升HDL-C治疗过程的动态变化仍不完全清楚。本研究在既往实验经验的基础上成功制备了OxHDL靶向USPIO分子探针，体外实验证实制备的oxHDL靶向分子USPIO分子探针具有动脉粥样硬化靶向性，活体MRI成像结果证实oxHDL靶向USPIO分子探针可以靶向显示易损斑块（%NENH：-25%±25%），病理结果显示USPIO分子探针分布与动脉粥样硬化斑块内oxHDL的分布一致，证实了靶向USPIO分子探针的靶向特异性。同时，oxHDL的分布与动脉粥样硬化斑块内不稳定因子巨噬细胞（CD68）、金属基质蛋白酶9（MMP-9）一致。因此，我们可以推论，oxHDL靶向USPIO分子探针可以用于易损斑块的活体诊断，是易损斑块活体靶向MRI成像的重要工具。进一步研究显示，oxHDL靶向USPIO MRI靶向分子成像可以活体评估匹伐他汀、烟酸、匹伐他汀联合烟酸治疗动脉粥样硬化斑块的治疗疗效。研究结果显示，高脂饮食进展组斑块MRI信号较干预前降低明显（-30.83%±17.7%），烟酸治疗组斑块MRI信号降低率较高脂饮食组有轻度减少（-16.03±13.31%），两组间比较无统计学意义；匹伐他汀治疗组动脉粥样硬化斑块组MRI信号无明显信号减低（5.59%±18.96%）。匹伐他汀联合烟酸治疗组斑块MRI信号改变率与单纯匹伐他汀治疗组相仿（7.08%±14.33%）。我们的动物活体MRI研究结果对于临床上可以提供以下参考：匹伐他汀可以有效提高斑块稳定性；烟酸治疗对于提高斑块稳定性无显著作用，烟酸联合匹伐他汀治疗疗效与匹伐他汀单药疗效相仿，因此不建议单独使用烟酸或使用烟酸联合匹伐他汀治疗动脉粥样硬化斑块。据我们所知，使用活体MRI分子成像评估匹伐他汀、烟酸及匹伐他汀联合烟酸治疗的治疗疗效，尚属于首次报告，具有很好的科研创新性。