髓过氧化物酶及基质金属蛋白酶的分子影像融合成像及其在多发性硬化临床前期和亚临床期诊断中的作用

Myeloperoxidase (MPO) is a key effector enzyme of myeloid inflammation and is found in multiple sclerosis (MS) plaques. Our preliminary research results showed that MR imaging probe MPO-Gd has been used to demonstrate MPO activity in vivo in brain of experimental autoimmune encephalomyelitis (EAE) mice, and fluorescence molecular tomography (FMT) has been used to track matrix metalloproteinases (MMPs) activity in vivo in EAE. However, it remains unclear if MPO-Gd can help detect preclinical inflammation at acute stage and detect subclinical lesions before relapse at chronic stage with higher sensitivity than diethylenetriaminepentaacetic acid (DTPA)-Gd when the blood-brain-barrier (BBB) is mostly closed. Here we investigate the effects of MPO activity inhibition in a murine model of demyelinating disease --EAE. We selectively inhibit MPO activity in the EAE using the specific irreversible MPO inhibitor 4-aminobenzoic acid hydrazide (ABAH) and track the changes in MPO and MMPs activity in vivo in these mice by fused molecular magnetic resonance imaging (MRI) and FMT imaging system using spicific MPO-Gd MRI contrast agent and MMPsense probe, try to detect the small inflammatory lesions before symptoms at preclinical and subclinical stage and treat EAE mice promptly, and prevent or postpone the permanent disabilities, and then track the treatment responses dynamically. Moreover, blocking MPO activity by MPO irreversible specific inhibitor, we aim to measure cytokines, myeloid cells and its subsets in EAE mice, and then investigate the interaction between myeloid cells and lymphocytes, as a result, we can further confirm the underlying immunomodulation roles of MPO and MMPs in the pathogenesis of EAE, therefore, can potentially provide preliminary theoretical basis for new drug development in human MS.

髓过氧化物酶(MPO)是髓系炎症的主要效应酶，存在于多发性硬化(MS)斑块中。我们的前期研究证实，MPO的靶向MR成像探针MPO-Gd可活体显示实验性自身免疫性脑脊髓炎(EAE)小鼠脑内的MPO活性，荧光分子断层成像可动态追踪小鼠脑内基质金属蛋白酶(MMPs)活性。相对于临床常规使用的DTPA-Gd,当血脑屏障处于关闭状态时，高特异性的MPO-Gd是否可发现处于临床前期和亚临床期的小病灶仍然未知。本研究通过分子影像融合成像结合高特异性的MPO-Gd和MMPs靶向分子探针无创性动态显示小鼠脑内MPO及MMPs活性，试图在临床前期及亚临床期发现病灶且及早给予治疗，以避免或推迟永久性残疾的发生，并对药物的治疗效果进行影像学评估。通过对细胞因子、髓系细胞及其亚群以及髓系细胞与淋巴细胞相互作用情况的研究进一步明确MPO和MMPs在小鼠EAE发生中的免疫调节机制，从而为MS的新药研发提供理论基础。

已有研究证实髓过氧化物酶(MPO)既可激活MMPs也可抑制MMPs的活性。然而，这一调节效应并未被在活体证实，目前也不清楚哪种通路与此相关。本研究的目的旨在探讨在活体炎性动物模型中，MPO是如何调节MMPs的。我们使用多发性硬化(MS)和神经炎症最常用的动物模型--实验性自身免疫性脑脊髓膜炎(EAE)进行研究，分别给予生理盐水和MPO特异性抑制剂4-ABAH对EAE小鼠进行治疗。在诱导动物后12天，通过使用MPO特异性的分子影像标记物MPO-Gd和MMP靶向的探针，对小鼠同时进行核磁共振成像(MRI)和荧光分子断层成像(FMT)。将生物化学检测指标和组织病理学结果进行相关性分析。通过MRI和FMT融合成像，我们发现抑制MPO后，MMP活性降低，说明MPO在活体内对MMP呈正向调节。活体的MMPSense探针的激活和MMP-9的活性与MPO-Gd阳性的病灶体积和疾病严重程度相关。体外的酶联免疫吸附实验(ELISA)和组织病理学实验亦证实MMP活性、MMP-9阳性细胞与MPO活性和MPO阳性细胞相关。总之，本研究首次证实多模态分子影像学成像可在活体动物内显示MPO对MMP的调节作用。这一技术可用于研究在活体中其他感兴趣生物分子的相互作用关系。

内容获取失败，请点击重试