Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, China (W.F., R.H., Z.Y, H.X., H.L., Y.J., J. Weng, J. Wang, S.W., Y.C., J.Z.).
China National Clinical Research Center for Neurological Diseases, Beijing (W.F., R.H., Z.Y, H.X., H.L., Y.J., J. Weng, J. Wang, S.W., Y.C., J.Z.).
Stroke. 2020 Jul;51(7):2197-2207. doi: 10.1161/STROKEAHA.120.030046. Epub 2020 Jun 3.
In unruptured brain arteriovenous malformations (bAVMs), microhemorrhage portends a higher risk of future rupture and may represent a transitional state along the continuum of destabilization. Exploration of the molecular and cellular mechanisms of microhemorrhage will provide a possible target for medical treatment to prevent bAVM bleeding.
We performed RNA sequencing analysis on 34 unruptured bAVM surgical samples. Functional pathway analysis was performed to identify potential signals associated with the microhemorrhagic phenotype. Candidate gene was then investigated in bAVM specimens by immunohistochemical staining. Several functional assays were used to investigate the effects of candidate genes on the phenotypic properties of cultured human umbilical vein endothelial cells. Then, Masson trichrome staining and immunofluorescence staining were used to evaluate the phenotypic and molecular changes in bAVM tissue.
Via RNA sequencing, we identified differential gene expression between 18 microhemorrhagic bAVMs and 16 nonmicrohemorrhagic bAVMs. TGFβ (transforming growth factor-beta)/BMP (bone morphogenetic protein) signaling was associated with the bAVM microhemorrhage group when SMAD6 (SMAD family member 6) was downregulated. Immunohistochemical staining showed that the vascular endothelium of microhemorrhagic bAVMs exhibited decreased SMAD6 expression. Functional assays revealed that SMAD6 downregulation promoted the formation of endothelial cell tubes with deficient cell-cell junctions and facilitated the acquisition of mesenchymal behavior by endothelial cells. Masson trichrome and immunofluorescence staining demonstrated that mesenchymal phenotype of endothelial cells is promoted in microhemorrhagic bAVMs.
TGFβ/BMP signaling mediated by SMAD6 in vascular endothelial cells is associated with microhemorrhagic bAVMs, and mesenchymal behavior of endothelial cells induced by SMAD6 downregulation is related with bAVM microhemorrhage.
在未破裂的脑动静脉畸形（bAVM）中，微出血预示着未来破裂的风险更高，并且可能代表沿着失稳连续体的过渡状态。探索微出血的分子和细胞机制将为预防 bAVM 出血的药物治疗提供可能的靶点。
我们对 34 例未破裂的 bAVM 手术样本进行了 RNA 测序分析。进行功能途径分析以确定与微出血表型相关的潜在信号。然后通过免疫组织化学染色研究候选基因在 bAVM 标本中的表达。使用几种功能测定来研究候选基因对培养的人脐静脉内皮细胞表型特性的影响。然后，使用 Masson 三色染色和免疫荧光染色来评估 bAVM 组织中的表型和分子变化。
通过 RNA 测序，我们在 18 例微出血 bAVM 和 16 例非微出血 bAVM 之间鉴定出差异基因表达。当 SMAD6（SMAD 家族成员 6）下调时，TGFβ（转化生长因子-β）/BMP（骨形态发生蛋白）信号与 bAVM 微出血组相关。免疫组织化学染色显示，微出血 bAVM 的血管内皮细胞表现出 SMAD6 表达降低。功能测定表明，SMAD6 下调促进了具有缺陷细胞-细胞连接的内皮细胞管的形成，并促进了内皮细胞获得间充质行为。Masson 三色和免疫荧光染色显示，微出血 bAVM 中内皮细胞的间充质表型得到促进。
血管内皮细胞中 SMAD6 介导的 TGFβ/BMP 信号与微出血 bAVM 相关，SMAD6 下调诱导的内皮细胞间充质行为与 bAVM 微出血相关。
