多模态MRI监测米诺环素对缺血性脑卒中血脑屏障重塑的影响及其机制的实验研究

Minocycline plays neuroprotective effects and reduces reperfusion injury by inhibiting matrix metalloproteinases (MMPs) and microglia/ macrophage activity after cerebral ischemia. However, giving minocycline in different phases has different effects. Due to magnetic resonance imaging (MRI) can assess BBB permeability and new blood vessels after ischemia-reperfusion. In this study, we discuss the application of MRI to assess the effects of minocycline in remodeling of BBB and new vessels after stroke. 60 adult spontaneously hypertensive rats will have a 90 minutes transient middle cerebral artery occlusion, dividing into four groups randomly: early treatment group, late treatment group, saline group and vehicle group. MRI and neurologic function score will be performed after 2, 7, 14, 28 days after reperfusion. ADC, CBF, Ktrans values and the number of new vessels of infarct area and peri-infarct area will be measured. Pathologic specimens will be collected and a series of examinations will be undergone, including western blots, immunohistochemistry, immunofluorescence and gelatin zymography to get the expressed level of tight junction protein, inflammatory cytokines, anti-inflammatory cytokines, Iba-1(+) microglia, MMP2 and MMP9. In order to illustrate the neuroprotective effects of minocycline in different treatment phases, we will analysis the difference of imaging and pathologic findings between the four groups. And relevance analysis between imaging features and pathologic findings will be performed to explore the molecular mechanism of imaging features.

米诺环素通过金属基质蛋白酶类(MMPs)及小胶质细胞/巨噬细胞促发脑缺血再灌注后的血脑屏障(BBB)及血管重塑，从而发挥神经保护及恢复作用，不同时相给药具不同效果。MRI可以反映缺血脑组织BBB通透性及新生血管情况，因此我们假设MRI可以监测MC所促发的BBB及血管重塑过程，并指导临床用药。拟运用自发性高血压大鼠60只，随机分为四组：早期给药组，晚期给药组，生理盐水组及假手术组。再灌注后2、7、14及28天分别行MRI及行为学评分，测量梗死核心区及梗死周围区脑组织ADC值，CBF值，Ktrans值及半定量新生血管值。MRI扫描结束后分别行Westren blot，免疫组化，免疫荧光及明胶电泳。分析各组影像学及病理学指标是否存在统计学差异，揭示MC的神经保护作用及作用时相；并将影像学指标与病理学指标进行相关性分析，从而探讨影像学表现的分子病理学机制。

米诺环素（Minocycline）通过金属基质蛋白酶类（Matrix metalloproteinases, MMPs）及小胶质细胞/巨噬细胞促发脑缺血再灌注后的血脑屏障（Blood-brain barrier, BBB）及血管重塑，从而发挥神经保护及恢复作用，不同时相给药具不同效果。MRI 动态对比增强（Dynamic contrast-enhanced, DCE）及磁敏感加权成像（Susceptibility weighted imaging, SWI）技术可以定量/半定量反映缺血脑组织BBB通透性改变及新生血管情况，因此我们假设MRI可以监测MC所促发的BBB及血管重塑过程，并指导临床用药。为了阐明不同时相给药MC对脑缺血再灌注后BBB及血管重塑作用的影响，并探讨运用MRI进行无创性动态监测的可行性。本研究建立自发性高血压大鼠缺血再灌注模型60只，随机分为四组：早期给药组，晚期给药组，生理盐水组及假手术组。于再灌注后1、2、7及14天分别行MRI及神经功能行为学评分，测量梗死核心区及梗死周围区脑组织BBB通透性Ktrans、Ve、Kep定量值及半定量新生血管值。MRI扫描结束后每组随机选择实验对象分别行Westren blot，免疫组化，免疫荧光及明胶电泳，观察BBB及血管重塑情况、并测量调节通路中的重要物质的定量/半定量值。结果显示MC对脑卒中后神经功能恢复具保护作用，可促进BBB及血管重塑，并降低炎性因子、增加抗炎因子的表达水平，早期给药组较晚期给药组促进重塑作用更强；DCE及SWI结果与病理学结果具很好的相关性，DCE及SWI可以作为无创性监测MC促BBB及血管重塑的影像学新指标，DCE观察BBB重塑、SWI观察血管重塑效能更好。. 本项目资助发表论文6篇（SCI论文4篇，中文核心期刊论文2篇）获得实用型专利1项。研究成果以大会发言、壁报、摘要的形式在全国及省内学术会议中推广。项目投入经费37万元，支出 万元，各项支出基本与预算相符。剩余经费11余万元，剩余经费计划用于本项目研究后续支出。