Abstract：
The molecular mechanisms of blood-brain barrier (BBB) disruption in the early stage after ischemic stroke are poorly understood. In the present study, we investigated the potential role of nicotinamide mononucleotide adenylyltransferase 1 (NMNAT1) in ischemia-induced BBB damage using an animal middle cerebral artery occlusion (MCAO) model of ischemic stroke. Recombinant human NMNAT1 (rh-NMNAT1) was administered intranasally and Sirtuin 1 (SIRT1) siRNA was administered by intracerebroventricular injection. Our results indicate that rh-NMNAT1 reduced infarct volume, improved functional outcome, and decreased BBB permeability in mice after ischemic stroke. Furthermore, rh-NMNAT1 prevented the loss of tight junction proteins (occludin and claudin-5) and reduced cell apoptosis in ischemic microvessels. NMNAT1-mediated BBB permeability was correlated with the elevation of nicotinamide adenine dinucleotide (NAD+)/NADH ratio and SIRT1 level in brain microvascular endothelial cells. In addition, rh-NMNAT1 treatment significantly decreased the levels of acetylated nuclear factor-κB, acetylated p53, and matrix metalloproteinase-9 in ischemic microvessels. Moreover, the protective effects of rh-NMNAT1 could be reversed by SIRT1 siRNA. In conclusion, these findings indicate that rh-NMNAT1 protects BBB integrity after cerebral ischemia via the NAD+/SIRT1 signaling pathway in brain microvascular endothelial cells. NMNAT1 may be a novel potential therapeutic target for reducing BBB disruption after ischemic stroke.
摘要：
缺血性卒中后早期血脑屏障（BBB）破坏的分子机制尚不清楚。在本研究中,我们使用动物大脑中动脉闭塞(MCAO)缺血性卒中模型,研究了烟酰胺单核苷酸腺苷酰转移酶1(NMNAT1)在缺血诱导的BBB损伤中的潜在作用.鼻内施用重组人NMNAT1(rh-NMNAT1),并通过侧脑室注射施用Sirtuin1(SIRT1)siRNA。我们的结果表明rh-NMNAT1减少了梗死体积，改善功能结果，小鼠缺血性中风后BBB通透性降低。此外，rh-NMNAT1可防止缺血微血管中紧密连接蛋白（occludin和claudin-5）的丢失并减少细胞凋亡。NMNAT1介导的BBB通透性与脑微血管内皮细胞中烟酰胺腺嘌呤二核苷酸（NAD）/NADH比率和SIRT1水平的升高有关。此外,rh-NMNAT1处理显著降低了乙酰化核因子-κB的水平,缺血微血管中的乙酰化p53和基质金属蛋白酶-9。此外，SIRT1siRNA可以逆转rh-NMNAT1的保护作用。总之,这些发现表明rh-NMNAT1通过脑微血管内皮细胞的NAD+/SIRT1信号通路保护脑缺血后BBB的完整性。NMNAT1可能是减少缺血性卒中后BBB破坏的新的潜在治疗靶标。
