Departments of Neurosurgery (N.I.M.-R., T.Z.T., T.C.C., S.L.G.), Keck School of Medicine, University of Southern California, Los Angeles.
Department of Pediatric Radiology, Texas Children's Hospital, Houston (K.B.G.).
Circ Res. 2020 Oct 9;127(9):e210-e231. doi: 10.1161/CIRCRESAHA.119.316317. Epub 2020 Aug 5.
Brain arteriovenous malformations (AVMs) are abnormal tangles of vessels where arteries and veins directly connect without intervening capillary nets, increasing the risk of intracerebral hemorrhage and stroke. Current treatments are highly invasive and often not feasible. Thus, effective noninvasive treatments are needed. We previously showed that AVM-brain endothelial cells (BECs) secreted higher VEGF (vascular endothelial growth factor) and lower TSP-1 (thrombospondin-1) levels than control BEC; and that microRNA-18a (miR-18a) normalized AVM-BEC function and phenotype, although its mechanism remained unclear.
To elucidate the mechanism of action and potential clinical application of miR-18a as an effective noninvasive treatment to selectively restore the phenotype and functionality of AVM vasculature.
The molecular pathways affected by miR-18a in patient-derived BECs and AVM-BECs were determined by Western blot, RT-qPCR (quantitative reverse transcription polymerase chain reaction), ELISA, co-IP, immunostaining, knockdown and overexpression studies, flow cytometry, and luciferase reporter assays. miR-18a was shown to increase TSP-1 and decrease VEGF by reducing PAI-1 (plasminogen activator inhibitor-1/SERPINE1) levels. Furthermore, miR-18a decreased the expression of BMP4 (bone morphogenetic protein 4) and HIF-1α (hypoxia-inducible factor 1α), blocking the BMP4/ALK (activin-like kinase) 2/ALK1/ALK5 and Notch signaling pathways. As determined by Boyden chamber assays, miR-18a also reduced the abnormal AVM-BEC invasiveness, which correlated with a decrease in MMP2 (matrix metalloproteinase 2), MMP9, and ADAM10 (ADAM metallopeptidase domain 10) levels. In vivo pharmacokinetic studies showed that miR-18a reaches the brain following intravenous and intranasal administration. Intranasal co-delivery of miR-18a and NEO100, a good manufacturing practices-quality form of perillyl alcohol, improved the pharmacokinetic profile of miR-18a in the brain without affecting its pharmacological properties. Ultra-high-resolution computed tomography angiography and immunostaining studies in an Mgp AVM mouse model showed that miR-18a decreased abnormal cerebral vasculature and restored the functionality of the bone marrow, lungs, spleen, and liver.
miR-18a may have significant clinical value in preventing, reducing, and potentially reversing AVM.
脑动静脉畸形（AVM）是动脉和静脉之间直接连接而没有中间毛细血管网的异常血管缠绕，增加了颅内出血和中风的风险。目前的治疗方法具有高度侵入性，并且通常不可行。因此，需要有效的非侵入性治疗方法。我们之前发现，与对照 BEC 相比，AVM-脑内皮细胞（BEC）分泌更高水平的 VEGF（血管内皮生长因子）和更低水平的 TSP-1（血栓调节蛋白-1）；并且微小 RNA-18a（miR-18a）可使 AVM-BEC 功能和表型正常化，尽管其机制尚不清楚。
阐明 miR-18a 作为一种有效的非侵入性治疗方法，选择性地恢复 AVM 血管的表型和功能的作用机制，并探讨其潜在的临床应用。
通过 Western blot、RT-qPCR（定量逆转录聚合酶链反应）、ELISA、co-IP、免疫染色、 knockdown 和过表达研究、流式细胞术和荧光素酶报告基因测定，确定了 miR-18a 在患者来源的 BEC 和 AVM-BEC 中影响的分子途径。miR-18a 通过降低 PAI-1（纤溶酶原激活物抑制剂-1/SERPINE1）水平来增加 TSP-1 和减少 VEGF。此外，miR-18a 降低了 BMP4（骨形态发生蛋白 4）和 HIF-1α（缺氧诱导因子 1α）的表达，阻断了 BMP4/ALK（激活素样激酶）2/ALK1/ALK5 和 Notch 信号通路。Boyden 室测定还表明，miR-18a 降低了异常 AVM-BEC 的侵袭性，这与 MMP2（基质金属蛋白酶 2）、MMP9 和 ADAM10（ADAM 金属肽酶结构域 10）水平的降低有关。体内药代动力学研究表明，miR-18a 经静脉和鼻内给药后可到达大脑。鼻内共递送 miR-18a 和 NEO100（一种良好生产规范质量的胡椒醇形式）可改善 miR-18a 在大脑中的药代动力学特征，而不影响其药理学特性。在 Mgp AVM 小鼠模型中的超高分辨率计算机断层血管造影和免疫染色研究表明，miR-18a 可减少异常脑血管并恢复骨髓、肺、脾和肝的功能。
miR-18a 在预防、减少和潜在逆转 AVM 方面可能具有重要的临床价值。
