Department of Vascular, The Third Hospital of Jilin University, Jilin University, Changchun, 130033 Jilin, China.
Department of Neurosurgery, The Third Hospital of Jilin University, Jilin University, Changchun, 130033 Jilin, China.
Exp Neurol. 2020 Nov;333:113411. doi: 10.1016/j.expneurol.2020.113411. Epub 2020 Jul 21.
Exosomes secreted by microglia have been found to play a role in neurovascular unit injury under the ischemic/hypoxic state. However, the modulatory effect of exosomes shuttled miRNAs produced by microglia in endothelial cells remains undefined. Here, an oxygen-glucose deprivation (OGD) model was constructed both in microglia and brain microvascular endothelial cells (BMEC). The exosomes secreted by microglia were isolated, and the exosomal miRNA profile was detected. Next, gain- and loss- functions of miR-424-5p, one of the most differentially expressed miRNAs in microglia derived exosomes, were conducted in BMEC. The results demonstrated that exosomes from OGD-activated microglia aggravated OGD induced BMEC viability and integrity damage as well as the loss of vascular formation. While the damaging effects were markedly attenuated by inhibiting miR-424-5p. In addition, miR-424-5p overexpression significantly aggravated OGD induced BMEC damage and permeability. Mechanistically, bioinformatics analysis indicated that miR-424-5p targeted the FGF2 mediated STAT3 signaling pathway, which was verified via dual luciferase activity assay and RIP experiment. Furthermore, in vivo experiments in the middle cerebral artery occlusion (MCAO) model mice were conducted. The results revealed that inhibition of miR-424-5p markedly reduced neurological dysfunctions and endothelial cell injury induced by MCAO. The above results confirmed that exosomes from OGD activated microglia induced significant cell damage and permeability of BMEC, in which the upregulated miR-424-5p in the exosomes functioned by regulating FGF2/STAT3 pathway.
小胶质细胞分泌的外泌体在缺血/缺氧状态下的神经血管单元损伤中发挥作用已得到证实。然而，小胶质细胞来源的外泌体穿梭 miRNA 对内皮细胞的调节作用尚不清楚。在这里，我们构建了小胶质细胞和脑微血管内皮细胞（BMEC）的氧葡萄糖剥夺（OGD）模型。分离小胶质细胞分泌的外泌体，并检测外泌体中的 miRNA 谱。接下来，在 BMEC 中进行了小胶质细胞来源的外泌体中表达差异最大的 miRNA 之一 miR-424-5p 的功能获得和缺失实验。结果表明，OGD 激活的小胶质细胞来源的外泌体加重了 OGD 诱导的 BMEC 活力和完整性损伤以及血管形成的丧失。而 miR-424-5p 的抑制则显著减轻了这种损伤作用。此外，miR-424-5p 的过表达显著加重了 OGD 诱导的 BMEC 损伤和通透性增加。机制上，生物信息学分析表明 miR-424-5p 靶向 FGF2 介导的 STAT3 信号通路，该通路通过双荧光素酶活性测定和 RIP 实验得到验证。此外，在大脑中动脉阻塞（MCAO）模型小鼠中进行了体内实验。结果表明，miR-424-5p 的抑制显著减轻了 MCAO 引起的神经功能障碍和内皮细胞损伤。上述结果证实，OGD 激活的小胶质细胞来源的外泌体诱导了 BMEC 的显著细胞损伤和通透性增加，其中外泌体中上调的 miR-424-5p 通过调节 FGF2/STAT3 通路发挥作用。
