Vascular smooth muscle cell senescence in atherosclerosis

Markers of cell senescence have been identified in both the blood and vessel wall of patients with atherosclerosis. In particular, vascular smooth muscle cells (VSMCs) derived from human plaques show numerous features of senescence both in culture and in vivo. This review summarises the evidence for VSMC senescence in atherosclerosis, and outlines the mechanisms and triggers leading to their senescence.     

C反应蛋白促肺动脉平滑肌细胞增殖的机制研究

目的观察C反应蛋白(CRP)对培养的肺动脉平滑肌细胞(hPASMCs)增殖的影响,探讨CRP对肺血管疾病的可能作用。方法细胞培养液中,加CRP 0,5,10,20,50,100,200 mg/L培养,依次为Ctrl组、CRP 5组、CRP 10组、CRP 20组、CRP 50组、CRP 100组、CRP 200组。细胞培养液中先加入Wortmannin 1μmol/L,PD098059 20μmol/L和Bay117082 10μmol/L,依次为Wort组、PD组和Bay组,2 h后再加入CRP 100 mg/L培养24 h。各组均加入5'-溴脱氧尿嘧啶共培养4 h测细胞增殖,应用Western blot方法检测细胞外信号调节酶(ERK)1/2和蛋白激酶B(Akt)蛋白表达情况。以非变性凝胶电泳迁移率方法检测NF-κB的激活。结果 CRP刺激hPASMCs的增殖呈浓度依赖性。与Ctrl组比较,除CRP 10组外,各CRP组细胞增殖倍数的差异均有统计学意义(P<0.05,P<0.01),与CRP 100组比较,Wort组、PD组和Bay组细胞增值明显下降(P<0.01)。CRP呈浓度依赖性诱导NF-κB激活,与CRP 100组比较,Wort组和Bay组抑制NF-κB激活。与Ctrl组比较,CRP 10组起p-Akt和ERK1/2表达增加。与CRP 100组比较,Wort组p-Akt表达下降,PD组p-ERK1/2表达下降。结论 CRP浓度依赖性地促进hPASMCs的增殖。CRP通过激活信号通路磷脂酰肌醇3激酶/Akt,丝裂原活化蛋白激酶/ERK1/2和NF-κB介导促增殖作用。     

血管平滑肌细胞表型转化与血管钙化

血管钙化是一种由细胞所介导、主动的生物矿化过程,可增加心血管疾病的患病率和死亡率,并严重危害人类的健康和生活。越来越多的研究证实血管平滑肌细胞(Vascular smooth muscle cell,VSMC)及表型转化（phenotypic switching）在血管钙化的发生发展中具有重要作用。本文将阐述VSMC的表型转化,向骨/软骨化表型转化不同时期的标志蛋白分子,并探讨其表型转化的调控因素,进而深入认识血管钙化的发病过程。     

Vascular smooth muscle cell phenotypes in primary pulmonary hypertension.

Primary pulmonary hypertension (PPH) is associated with specific structural alterations, including cellular intimal thickening, intimal fibrosis, and plexiform lesions. To determine the phenotypes of smooth muscle cells (SMCs) in such lesions, the authors conducted an immunohistochemical analysis of lung tissues from two patients with PPH, using two antimuscle actin antibodies, HHF35 and CGA7, and two anti-SMC myosin heavy chain markers, anti-SM1 and anti-SM2 antibodies and related antibodies. Cells that stained positive (+) with HHF35, CGA7, anti-SM1, and anti-SM2 were considered to be SMCs of a mature state. Conversely, those that stained positive with HHF35 and anti-SM1, but weakly positive (+/-) or negative (-) with CGA7 and anti-SM2, were considered to be SMCs exhibiting an immature state. Cellular intimal thickening was composed of SMCs of an immature phenotype (HHF35+, CGA7+/-, SM1+, SM2+/-), accompanied by the expression of fibronectin and the presence of macrophages; intimal fibrosis contained mature SMCs (HHF35+, CGA7+, SM1+, SM2+); and plexiform lesion consisted of proliferative endothelial cells (von Willebrand factor-positive cells, proliferating cell nuclear antigen-positive cells) and underlying immature SMCs (HHF35+, CGA7-, SM1+, SM2-) associated with fibronectin expression and macrophage infiltration. These findings suggest that smooth muscle cells with specific phenotypes may contribute to the development of specific vascular lesions in primary pulmonary hypertension.     

Vascular smooth muscle cell motility: From migration to invasion

Over the past decade, extensive research has focused on identifying the molecular mechanisms and signal transduction pathways involved in the modulation of vascular smooth muscle cell phenotypes. In the present review, the characteristics of vascular smooth muscle cell (VSMC) phenotypes as they relate to cell migration are discussed based on insights from recent molecular findings. A central theme is the mechanisms involved in nonpathogenic VSMC migration during tissue repair versus VSMC invasion that leads to the development of vascular diseases. The issue of how various factors that are released locally following tissue injury influence cell migration will also be addressed.     

Aldosterone stimulates vascular smooth muscle cell proliferation via big mitogen-activated protein kinase 1 activation

The nongenomic effects of aldosterone have been implicated in the pathogenesis of various cardiovascular diseases. Aldosterone-induced nongenomic effects are attributable in part to the activation of extracellular signal-regulated kinase 1/2 (ERK1/2), a classical mitogen-activated protein (MAP) kinase. Big MAP kinase 1 (BMK1), a newly identified MAP kinase, has been shown to be involved in cell proliferation, differentiation, and survival. We examined whether aldosterone stimulates BMK1-mediated proliferation of cultured rat aortic smooth muscle cells (RASMCs). Mineralocorticoid receptor (MR) expression and localization were evaluated by Western blotting analysis and fluorolabeling methods. ERK1/2 and BMK1 activities were measured by Western blotting analysis with the respective phosphospecific antibodies. Cell proliferation was determined by Alamar Blue colorimetric assay. Aldosterone (0.1 to 100 nmol/L) dose-dependently activated BMK1 in RASMCs, with a peak at 30 minutes. To clarify whether aldosterone-induced BMK1 activation is an MR-mediated phenomenon, we examined the effect of eplerenone, a selective MR antagonist, on aldosterone-induced BMK1 activation. Eplerenone (0.1 to 10 micromol/L) dose-dependently inhibited aldosterone-induced BMK1 activation in RASMCs. Aldosterone also stimulated RASMC proliferation, which was inhibited by eplerenone. Aldosterone-mediated phenomena were concluded to be attributable to a nongenomic effect because cycloheximide failed to inhibit aldosterone-induced BMK1 activation. Transfection of dominant-negative MAP kinase/ERK kinase 5 (MEK5), which is an upstream regulator of BMK1, partially inhibited aldosterone-induced RASMC proliferation, which was almost completely inhibited by MEK inhibitor PD98059. In addition to the classical steroid activity, rapid nongenomic effects induced by aldosterone may represent an alternative etiology for vascular diseases such as hypertension.     

Monocyte activation by smooth muscle cell-derived matrices

Mononuclear phagocytes adhere to and penetrate the vessel wall endothelium and contact the subendothelial space prior to the development of the atherosclerotic plaque. In an attempt to model the early events of plaque development we used an elastin-rich, multicomponent, cell-derived matrix from neonatal rat aortic smooth muscle cells as a substratum for monocytes. Using this model, we show that human monocyte morphology and metabolism are markedly altered by the matrix substratum. When a mixed mononuclear cell population is seeded on matrix or plastic, only monocytes adhere to the matrix surface. In contrast, lymphocytes as well as monocytes adhere to the plastic surface. The matrix-adherent monocytes develop large intracellular granules and form extensive clusters of individual cells. Metabolically, these cells develop sodium fluoride resistant non-specific esterase activity and their media contain more growth factor activity and PGE2. Although total protein synthesis is equivalent in both cultures, the matrix contact induces an increase in specific proteins in the media. We also show that a purified alpha-elastin substratum induces some, but not all, of the monocyte changes seen when using the matrix substratum. Using the alpha-elastin substratum, there is selective adhesion of monocytes and increased growth factor activity, however, the cells are morphologically different from the matrix-adherent cells. Thus, the use of the smooth muscle cell-derived matrix, in conjunction with purified matrix components, serves as a model that can provide insight into the mechanisms of monocyte adhesion and stimulation by the matrix environment that exists in vivo. Such mechanisms may be particularly important in atherogenesis.     

Role of stretch in activation of smooth muscle cell lineage

Mechanical force is a critical modulator of smooth muscle (SM) function and gene expression. Very little is known, however, about its contribution to SM myogenesis. This review presents and discusses what has been learned about the role of mechanical force in inducing SM myogenesis and some of the signaling mechanisms involved in this process.     

Vascular smooth muscle cell proliferation is effectively suppressed by the non-specific growth factor inhibitor suramin

The purpose of this study was to investigate the effects of the non-specific growth factor inhibitor suramin on smooth muscle cell proliferation in vitro and in vivo. Cultured vascular smooth muscle cells (VSMC) were stimulated by platelet-derived growth factor (PDGF) and cellular DNA synthesis assessed by [3H]-thymidine uptake. Suramin dose-dependently inhibited DNA synthesis in VSMC, and 100 microM of suramin completely suppressed the PDGF-AB-induced cellular DNA synthesis. Rabbit carotid arteries were injured by the balloon catheter, and then suramin locally delivered using a porous balloon catheter over ten minutes. Three weeks after the vascular injury, the extent of intimal thickening was compared between the suramin-treated and control rabbits. The neointimal formation triggered by balloon-mediated vascular injury was suppressed significantly and dose-dependently by locally infused suramin, and the intima to media area ratios of the control and 1 mM suramin-treated animals were 48.8+/-14.9 and 12.2+/-6.0%, respectively (p < 0.01. n = 6 for each group). These results suggest that one time local administration of suramin was sufficient to suppress neointimal formation after balloon-mediated vascular injury, and that pharmacological intervention targeting the growth factor's signaling pathways could be a promising approach to prevent smooth muscle cell proliferation in various proliferative vascular diseases.     

活性氧诱导血管平滑肌细胞衰老及脱氢表雄酮的干预研究

目的 观察三丁基过氧化氢(tert-butyl hydroperoxide,t-BHP)对血管平滑肌细胞(vascular smooth muscle cell,VSMC)衰老的诱导作用,及脱氢表雄酮(dehydroepiandrosterone,DHEA)的干预作用.方法 将VSMC分为4组:对照组、t-BHP刺激组(在80 μmol/L t-BHP的DMEM培养液中72 h);10 nmol/L DHEA干预组(给予t-BHP刺激前30 min先加用10 nmol/LDHEA);100 nmol/L DHEA干预组(给予t-BHP刺激前30 min先加用100 nmol/L DHEA).以衰老相关β-半乳糖苷酶活性和细胞的增殖能力两种衰老标志物为主要观察指标.其中衰老相关β-半乳糖苷酶活性采用免疫化学染色方法,流式细胞术检测细胞周期来反应细胞的增殖能力. 结果 经80 mmol/L的t-BHP持续作用72 h后,VSMC的G_0/G_1期细胞比例和SA-β半乳糖苷酶染色阳性细胞百分比增加[分别为(49.5±5.5)%和(89.4±3.4)%;(3.5±1.2)%和(75.3±4.3)%],差异有统计学意义(P<0.01).表明t-BHP成功诱导了VSMC衰老,而给予100 nmol/L DHEA干预后上述变化改善,为(71.3±3.9)%. 结论 随增龄,活性氧损害的累积可能是VSMC衰老的机制之一,DHEA可能通过抗氧化作用延缓VSMC的衰老.