血管平滑肌细胞与动脉粥样硬化斑块稳定性的研究进展

动脉粥样硬化(AS)斑块是否破裂与斑块内在特性密切相关.斑块脂质核心增大、炎症细胞浸润、纤维帽变薄及血管钙化极易导致斑块破裂.血管平滑肌细胞(VSMC)可发生表型转化,转化为巨噬细胞样细胞、泡沫细胞、间充质干细胞、成骨样细胞等多种类型,进而影响斑块稳定性.本文主要介绍VSMC表型转化及其与AS斑块稳定性之间的联系,为稳...     

血管平滑肌细胞对动脉粥样硬化形成的作用研究

动脉粥样硬化的形成是复杂且缓慢的过程。血管平滑肌细胞可分为合成型和收缩型,参与动脉粥样硬化的发生和发展。该文介绍血管平滑肌细胞外泌体、表型转化、离子通道、自噬以及细胞外高血糖状态对动脉粥样硬化形成的影响。     

血管平滑肌细胞移行及表型转换的分子机制

在动脉粥样硬化发生、发展的不同阶段,血管平滑肌细胞表型转换具有重要且可能是不同的病理生理学意义。文章复习了近年动脉粥样硬化病损内膜中血管平滑肌细胞来源、血管平滑肌细胞表型转换的分子机制及鉴别不同平滑肌细胞表型的标志性分子,以期为深入理解动脉粥样硬化的发病机制和相关研究提供有益认识。     

血管平滑肌细胞表型转化及相关信号转导机制探讨

血管平滑肌细胞增殖是血管成形术后再狭窄、动脉粥样硬化斑块形成的病理基础。血管平滑肌细胞增殖能力与其表型转化密切相关。对从血管平滑肌细胞表型转化的主要特征、标志物、信号转导机制进行了探讨。     

血管平滑肌细胞表型转化及相关机制

血管平滑肌细胞表型改变与动脉粥样硬化、介入后再狭窄等病理改变紧密相关。去分化的血管平滑肌细胞可分化为成骨型、炎症型或成纤维母细胞等表型。现从血管平滑肌细胞表型转化及相关机制进行探讨。     

血管平滑肌细胞表型转换对动脉粥样硬化的作用研究进展

在动脉粥样硬化的进程中,血管中膜平滑肌细胞发生表型转换、迁移、增殖,进入血管内膜,参与动脉粥样硬化斑块纤维帽及新生血管的生成。本文就当前关于血管平滑肌细胞表型转换对动脉粥样硬化作用的研究进展作一综述。     

原位杂交检测胰岛素样生长因子-1受体基因在动脉粥样硬化组织中的表达

为观察胰岛素样生长因子１受体基因在动脉粥样硬化组织中的表达及分布,建立实验性动脉粥样硬化家兔模型。采用人胰岛素样生长因子１受体ｃＲＮＡ探针进行组织原位杂交。结果发现,正常对照的家兔主动脉组织,仅在外膜显示有胰岛素样生长因子１受体ｍＲＮＡ的阳性表达,中膜及内膜均呈阴性;实验组主动脉的整个血管壁,包括外膜、中膜、新生内膜及动脉粥样硬化斑块组织均有胰岛素样生长因子１受体基因的表达。研究提示,增殖的血管平滑肌细胞、新生的内皮细胞及构成动脉粥样硬化斑块主要成分的泡沫细胞均为胰岛素样生长因子１受体ｍＲＮＡ表达的靶细胞,证实胰岛素样生长因子１受体基因参与动脉粥样硬化的发生。     

糖代谢紊乱与动脉粥样硬化

糖代谢紊乱为动脉粥样硬化的危险因素之一.研究表明:高血糖可直接作用于血管细胞,如血管内皮细胞、血管平滑肌细胞及血管炎症细胞等;另一方面,高血糖可导致相关基因发生化学修饰,上调基因的表达而促进单核巨噬细胞向泡沫细胞转化,作用于相应基因靶点促进巨噬细胞活化及动脉粥样斑块的形成.因此,血糖可能通过上述一种或多种作用机制促进动...     

黄芪和当归对血管平滑肌细胞表型标志基因表达和细胞增殖的影响

为了观察黄芪和当归对血管平滑肌细胞表型转化和增殖的影响，采用体外培养的血管平滑肌细胞，以碱性成纤维细胞生长因子诱导其表型转化和增殖，在此基础上，通过Northern和Western印迹法检测平滑肌细胞表型标志基因表达的变化，研究黄芪和当归注射液对碱性成纤维细胞生长因子上述效应的抑制作用。结果发现，碱性成纤维细胞生长因子可明显下调分化型标志基因平滑肌α-肌动蛋白的表达，上调去分化型标志基因平滑肌胚胎型肌球蛋白重链和骨桥蛋白表达，诱导原癌基因c-jun表达及促进血管平滑肌细胞DNA合成。黄芪和当归可上调分化型标志基因的表达活性，下调去分化型标志基因的表达，不同程度地抑制碱性成纤维细胞生长因子诱导的血管平滑肌细胞表型转化和DNA合成，有效抑制血管平滑肌细胞增殖，其作用机制可能与抑制碱性成纤维细胞生长因子诱导的c-jun基因表达有关。二者相比，当归的作用大于黄芪。结果提示，黄芪和当归可从多位点上拮抗碱性成纤维细胞生长因子促血管平滑肌细胞表型转化及细胞增殖。     

胰岛素对血管平滑肌α肌动蛋白基因变异的影响机制

胰岛素不仅能维持血管平滑肌细胞的静止形态,也能促进血管平滑肌细胞的迁移.胰岛素这种不同的效应是通过血管平滑肌细胞表型标志物α-平滑肌肌动蛋白实现的,因为α-平滑肌肌动蛋白在血管平滑肌细胞静止形态中高表达,而在血管平滑肌细胞迁移形态中低表达.胰岛素维持血管平滑肌细胞静止形态是通过磷脂酰肌醇激酶3途径实现的,而其促进血管平滑肌细胞迁移是通过活化蛋白激酶实现的.因此,在模拟胰岛素抵抗状态,即阻断磷脂酰肌醇激酶3信号通路并保留活化蛋白激酶信号通路,胰岛素可能失去维持血管平滑肌细胞的静止状态,取而代之的是促进血管平滑肌细胞的迁移.α-平滑肌肌动蛋白的变异能引发许多血管性疾病,包括冠心病、缺血性脑卒中等.α-平滑肌肌动蛋白的单基因也变异能引发弥漫性血管疾病,包含了动脉的阻塞及扩大,这在临床上对血管性疾病的研究和治疗有直接的指导作用.     

Methylation of the estrogen receptor-alpha gene promoter is selectively increased in proliferating human aortic smooth muscle cells

OBJECTIVE: Atherosclerosis is a multigenic process leading to the progressive occlusion of arteries of mid to large caliber. A key step of the atherogenic process is the proliferation and migration of vascular smooth muscle cells into the intimal layer of the arterial conduit. The phenotype of smooth muscle cells, once within the intima, is known to switch from contractile to de-differentiated, yet the regulation of this switch at the genomic level is unknown. Estrogen has been shown to regulate cell proliferation both for cancer cells and for vascular cells. However, methylation of the estrogen receptor-alpha gene (ERalpha) promoter blocks the expression of ERalpha, and thereby can antagonize the regulatory effect of estrogen on cell proliferation. We sought to determine whether methylation of the ERalpha is differentially and selectively regulated in contractile versus de-differentiated arterial smooth muscle cells. METHODS: We used Southern blot assay, combined bisulfite restriction analysis (Cobra) and restriction landmark genome scanning (RLGS-M) to determine the methylation status of ERalpha in human aortic smooth muscle cells, either in situ (normal aortic tissue, contractile phenotype), or the same cells explanted from the aorta and cultured in vitro (de-differentiated phenotype). Results: We provide evidence that methylation of the ERalpha in smooth muscle cells that display a proliferative phenotype is altered relative to the same cells studied within the media of non-atherosclerotic aortas. Thus, the ERalpha promoter does not appear to be methylated in situ (normal aorta), but becomes methylated in proliferating aortic smooth muscle cells. Using a screening technique, RLGS-M, we show that alteration in methylation associated with the smooth muscle cell phenotypic switch does not seem to require heightened activity of the methyltransferase enzyme, and appears to be selective for the ERalpha and a limited pool of genes whose CpG island becomes either demethylated or de novo methylated. CONCLUSIONS: Our data support the concept that the genome of aortic smooth muscle cells is responsive to environmental conditions, and that DNA methylation, in particular methylation of the ERalpha, could contribute to the switch in phenotype observed in these cells.     

动脉粥样硬化的表观遗传调控

表观遗传调控指的是在DNA序列不变的情况下基因表达发生的可遗传性改变。目前,已知的表观遗传调控的主要机制包括DNA甲基化、组蛋白修饰和非编码RNA。大量研究证实,在心血管疾病、肿瘤和自身免疫性疾病等方面表观遗传调控发挥着重要作用。近年来,越来越多的研究表明,表观遗传调控在动脉粥样硬化的疾病病程中发挥着重要作用。本文将围绕DNA甲基化、组蛋白修饰和非编码RNA这三种主要的表观遗传调控对血管平滑肌细胞的调节来探讨表观遗传调控在动脉粥样硬化进程中的重要作用。     

血管钙化的表观遗传调控

血管钙化是慢性肾病、糖尿病、高血压和动脉粥样硬化等疾病共同存在的血管病变,其是上述疾病患者心血管事件显著上升的重要危险因素。目前尚无有效药物可以预防或者逆转血管钙化。既往研究表明,血管钙化是一个主动的、可调控的、细胞介导的病理过程,高度类似于骨发生和骨代谢。血管平滑肌细胞向成骨样细胞转分化是血管钙化发生的关键机制。目前的研究表明,多种表观遗传调控途径参与血管钙化的病理进程。本文主要从DNA甲基化、组蛋白修饰和非编码RNA这三个层面综述血管钙化的表观遗传调控机制。靶向表观遗传调控因子有望为防治血管钙化提供新的策略。     

Smoothelin in vascular smooth muscle cells

Smoothelin-A and -B have only been found in fully differentiated contractile smooth muscle cells. They are increasingly used to monitor the smooth muscle cell differentiation process to a contractile or synthetic phenotype. Vascular-specific smoothelin-B is the first smooth muscle cell marker that disappears when vascular tissues are compromised, for example, in atherosclerosis or restenosis. Recently obtained data show that smoothelin deficiency results in a considerable loss of contractile potential and hence in impaired smooth muscle function and suggest that smoothelins are part of the contractile apparatus.     

力学敏感性microRNA在微重力环境致血管平滑肌细胞表型转换中的作用

血管平滑肌细胞（VSMCs）具有很强的可塑性，当外界环境因素变化时可发生“收缩表型”和“合成表型”之间的转换。VSMCs表型转换是血管损伤后修复、高血压、动脉粥样硬化等众多血管疾病发生与发展中的关键起始步骤。研究证实生长因子、转录因子、缺氧、机械应力等因素能够调节VSMCs的表型转换。此外，microRNAs被证实广泛参与了VSMCs表型转换的调节，特别地是存在一类microRNAs可以感受细胞外力学因素的改变从而参与调节VSMCs的表型转换。航天飞行中，微重力环境可通过力学敏感性microRNA调控脑动脉VSMCs的表型转换，最终导致航天飞行后心血管功能的失调。因此，力学敏感性microRNA可为航天飞行后心血管功能失调提供潜在的药物靶点，对长期载人航天的医学保障具有重要意义。     

Transforming growth factor-betas and vascular disorders

Transforming growth factor-beta (TGF-beta) superfamily members, TGF-beta and bone morphogenetic proteins (BMPs), are potent regulatory cytokines with diverse functions on vascular cells. They signal through heteromeric type I and II receptor complexes activating Smad-dependent and Smad-independent signals, which regulate proliferation, differentiation, and survival. They are potent regulators of vascular development and vessel remodeling and play key roles in atherosclerosis and restenosis, regulating endothelial, smooth muscle cell, macrophage, T cell, and probably vascular calcifying cell responses. In atherosclerosis, TGF-beta regulates lesion phenotype by controlling T-cell responses and stimulating smooth muscle cells to produce collagen. It contributes to restenosis by augmenting neointimal cell proliferation and collagen accumulation. Defective TGF-beta signaling in endothelial cells attributable to mutations in endoglin or the type I receptor ALK-1 leads to hereditary hemorrhagic telangiectasia, whereas defective BMP signaling attributable to mutations in the BMP receptor II has been associated with development of primary pulmonary hypertension. The development of mouse models with either cell type-specific or general inactivation of TGF-beta/BMP signaling has started to reveal the importance of the regulatory network of TGF-beta/BMP pathways in vivo and their significance for atherosclerosis, hereditary hemorrhagic telangiectasia, and primary pulmonary hypertension. This review highlights recent findings that have advanced our understanding of the roles of TGF-beta superfamily members in regulating vascular cell responses and provides likely avenues for future research that may lead to novel pharmacological therapies for the treatment or prevention of vascular disorders.     

Promotion of vascular smooth muscle cell growth by homocysteine: a link to atherosclerosis.

Plasma homocysteine levels are elevated in 20-30% of all patients with premature atherosclerosis. Although elevated homocysteine levels have been recognized as an independent risk factor for myocardial infarction and stroke, the mechanism by which these elevated levels cause atherosclerosis is unknown. To understand the role of homocysteine in the pathogenesis of atherosclerosis, we examined the effect of homocysteine on the growth of both vascular smooth muscle cells and endothelial cells at concentrations similar to those observed in clinical studies. As little as 0.1 mM homocysteine caused a 25% increase in DNA synthesis, and homocysteine at 1 mM increased DNA synthesis by 4.5-fold in rat aortic smooth muscle cells (RASMC). In contrast, homocysteine caused a dose-dependent decrease in DNA synthesis in human umbilical vein endothelial cells. Homocysteine increased mRNA levels of cyclin D1 and cyclin A in RASMC by 3- and 15-fold, respectively, indicating that homocysteine induced the mRNA of cyclins important for the reentry of quiescent RASMC into the cell cycle. Furthermore, homocysteine promoted proliferation of quiescent RASMC, an effect markedly amplified by 2% serum. The growth-promoting effect of homocysteine on vascular smooth muscle cells, together with its inhibitory effect on endothelial cell growth, represents an important mechanism to explain homocysteine-induced atherosclerosis.     

Cadherins, RhoA, and Rac1 are differentially required for stretch-mediated proliferation in endothelial versus smooth muscle cells

Abnormal mechanical forces can trigger aberrant proliferation of endothelial and smooth muscle cells, as observed in the progression of vascular diseases such as atherosclerosis. It has been previously shown that cells can sense physical forces such as stretch through adhesions to the extracellular matrix. Here, we set out to examine whether cell-cell adhesions are also involved in transducing mechanical stretch into a proliferative response. We found that both endothelial and smooth muscle cells exhibited an increase in proliferation in response to stretch. Using micropatterning to isolate the role of cell-cell adhesion from cell-extracellular matrix adhesion, we demonstrate that endothelial cells required cell-cell contact and vascular endothelial cadherin engagement to transduce stretch into proliferative signals. In contrast, smooth muscle cells responded to stretch without contact to neighboring cells. We further show that stretch stimulated Rac1 activity in endothelial cells, whereas RhoA was activated by stretch in smooth muscle cells. Blocking Rac1 signaling by pharmacological or adenoviral reagents abrogated the proliferative response to stretch in endothelial cells but not in smooth muscle cells. Conversely, blocking RhoA completely inhibited the proliferative response in smooth muscle cells but not in endothelial cells. Together, these data suggest that vascular endothelial cadherin has an important role in mechanotransduction and that endothelial and smooth muscle cells use different mechanisms to respond to stretch.