Kang Yuan-Cheng, Zhang Li, Su Ying, Li Yue, Ren Wen-Lei, Wei Wen-Shi
Department of Neurology, Huadong Hospital, Fudan University, Shanghai, China.
Front Cell Neurosci. 2018 Jun 8;12:154. doi: 10.3389/fncel.2018.00154. eCollection 2018.
Microglia play an important role in the central nervous system as immune cells and are often activated by post-ischemic injury. MicroRNAs are small endogenous RNAs affecting many complex cellular biological functions that are involved in neurodegenerative and cerebrovascular diseases. Previous studies have shown that microRNA-26b (miR-26b) is downregulated in BV-2 cells exposed to oxygen-glucose deprivation (OGD). This study aimed to investigate how miR-26b regulates microglial activation and its neurotoxicity as well as the effect of miR-26b on vascular cognitive impairment (VCI). Here, we used PCR to detect the mRNA expression of miR-26b and cytokines, western blot for the protein expression of cytokines, and the live/dead assay for neuronal apoptosis. In addition, we employed a luciferase assay to identify the possible target genes of miR-26b. Furthermore, we studied the effects of cerebral ischemia by bilateral common carotid artery occlusion (BCCAO) in rats. We used staining to identify neurons and microglia, and we tested cognitive function by the T-maze test. Our results showed that OGD activated microglia and increased the expression of interleukin (IL)-6 and other cytokines. Similarly, BCCAO activated microglia and increased the expression of IL-6 in the hippocampal CA1 area. We further found that miR-26b decreased the number of activated microglia and targeted IL-6. Moreover, miR-26b expression attenuated microglial activation, inflammation, neurotoxicity and VCI. Our results suggested that miR-26b is involved in microglial activation and neurotoxicity in hypoxia/ischemia via IL-6. Therefore, increasing miR-26b expression may improve cognitive function.
小胶质细胞作为免疫细胞在中枢神经系统中发挥着重要作用，并且常被缺血性损伤激活。微小RNA是一类影响许多复杂细胞生物学功能的内源性小RNA，参与神经退行性疾病和脑血管疾病。先前的研究表明，在暴露于氧糖剥夺（OGD）的BV-2细胞中，微小RNA-26b（miR-26b）表达下调。本研究旨在探讨miR-26b如何调节小胶质细胞的激活及其神经毒性，以及miR-26b对血管性认知障碍（VCI）的影响。在此，我们使用聚合酶链反应（PCR）检测miR-26b和细胞因子的信使核糖核酸（mRNA）表达，使用蛋白质免疫印迹法检测细胞因子的蛋白质表达，并使用活/死检测法检测神经元凋亡。此外，我们采用荧光素酶检测法来鉴定miR-26b可能的靶基因。此外，我们通过双侧颈总动脉闭塞（BCCAO）研究了大鼠脑缺血的影响。我们使用染色来鉴定神经元和小胶质细胞，并通过T迷宫试验测试认知功能。我们的结果表明，OGD激活了小胶质细胞并增加了白细胞介素（IL）-6和其他细胞因子的表达。同样，BCCAO激活了小胶质细胞并增加了海马CA1区IL-6的表达。我们进一步发现，miR-26b减少了激活的小胶质细胞数量并靶向IL-6。此外，miR-26b的表达减弱了小胶质细胞的激活、炎症、神经毒性和VCI。我们的结果表明，miR-26b通过IL-6参与缺氧/缺血时的小胶质细胞激活和神经毒性。因此，增加miR-26b的表达可能会改善认知功能。
