Carbon monoxide inhibits apoptosis in vascular smooth muscle cells

OBJECTIVE: Carbon monoxide (CO) is generated from vascular smooth muscle cells via the degradation of heme by the enzyme heme oxygenase-1. Since smooth muscle cell apoptosis is associated with numerous vascular disorders, we investigated whether CO regulates apoptosis in vascular smooth muscle. METHODS AND RESULTS: Treatment of cultured rat aortic smooth muscle cells with a combination of cytokines (interleukin-1beta, 5 ng/ml; tumor necrosis factor-alpha, 20 ng/ml; interferon-gamma, 200 U/ml) for 48 h stimulated apoptosis, as demonstrated by DNA laddering, annexin V binding, and caspase-3 activation. However, the exogenous administration of CO inhibited cytokine-mediated apoptosis. The antiapoptotic action of CO was partially dependent on the activation of soluble guanylate cyclase and was associated with the inhibition of mitochondrial cytochrome c release and with the suppression of p53 expression. Incubation of smooth muscle cells with the cytokines also resulted in a pronounced increase in heme oxygenase-1 protein after 24 h of stimulation. The addition of the heme oxygenase inhibitor, zinc protoporphyrin-IX, or the CO scavenger, hemoglobin, stimulated apoptosis following 24 h of cytokine exposure. CONCLUSIONS: These results demonstrate that CO, either administered exogenously or endogenously derived from heme oxygenase-1 activity, inhibits vascular smooth muscle cell apoptosis. The ability of CO to block smooth muscle cell apoptosis may play an important role in blocking lesion formation at sites of vascular injury.     

血管平滑肌细胞凋亡的相关调控因子

血管平滑肌细胞（VSMC）凋亡参与了动脉粥样硬化及冠状动脉介入治疗术后再狭窄等心血管疾病的发生和发展过程,有关VSMC凋亡的研究已经成为冠心病防治研究的热点。细胞凋亡是多种基因参与且复杂的分子调控机制,多种细胞因子在此过程中发挥极其重要的作用。该文对有关VSMC凋亡的调控因子概况作一综述。     

腺病毒介导的HCY2基因对血管平滑肌细胞凋亡的诱导作用

目的　观察高同型半胱氨酸诱导基因HCY2对于平滑肌细胞的作用。方法　以复制缺陷型腺病毒作为载体 ,将HCY2基因转移到平滑肌细胞中。提取平滑肌细胞的DNA ,进行凝胶电泳及ELISA ,行DNA片段化分析。用流式细胞术观察平滑肌细胞的亚二倍体。结果　转染HCY2后平滑肌细胞的DNA断裂成相差 2 0 0bp左右的片段 ,流式细胞术测定时发现 ,位于亚二倍体区的平滑肌细胞明显增多。结论　HCY2基因能引起平滑肌细胞的凋亡。     

HMG-CoA reductase inhibitors induce apoptosis in neointima-derived vascular smooth muscle cells

In the context of atherogenesis and restenosis, vascular smooth muscle cell (SMC) proliferation and apoptosis play a crucial role. Inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase (statins) have been shown to inhibit the migration and proliferation of SMC, and to induce apoptosis in different cell types including SMC. However, it is not known whether these agents induce apoptosis in neointimal SMC. We investigated the effects of statin treatment on neointimal SMC as compared to medial cells by using trypan blue counting, MTT test, Annexin V staining, cell cycle analysis and a co-culture model. The incubation of neointimal or medial SMC with lovastatin reduced the MTT activity as well as the total cell number, and increased the amount of trypan blue positive cells, indicative of cell death. We tested by staining with Annexin V/propidium iodide, specific antibodies to active caspase-3, TUNEL reaction, and by the appearance of a sub-G1 peak, whether the observed increase in cell death was due to apoptosis. After treatment with lovastatin, programmed cell death was slightly increased in medial SMC, while neointimal cells showed a pronounced rate of apoptosis. In an attempt to mimic early phases of restenosis in vitro by seeding low density neointimal cells onto high density medial cells, we found that statin treatment induced cell death preferentially in the neointimal SMC. Our results suggest that statins enhance the rate of apoptosis in neointimal SMC, which may be an interesting feature to reduce restenosis after successful angioplasty.     

Mast cell chymase induces apoptosis of vascular smooth muscle cells

In human coronary atheromas, the numbers of degranulated mast cells and of apoptotic smooth muscle cells (SMCs) are increased. Accordingly, the possibility exists that mast cells participate in the regulation of SMC apoptosis in the lesions. Mast cells isolated from the serosal cavities of rats were stimulated to release their secretory granules. The neutral protease chymase, present in the exocytosed granules, was found to induce apoptosis when added to rat aortic SMCs in culture. The chymase-induced apoptosis of SMCs was detected by flow cytometry, microscopic analysis of cellular morphology, terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL), and electrophoretic demonstration of DNA laddering. Chymase induced SMC apoptosis in a dose- and time- dependent manner, and its proteolytic activity was essential for the proapoptotic effect. In addition to rat chymase, recombinant human chymase was also found to induce apoptosis of human coronary artery SMCs in culture. These results suggest that mast cells may participate in the apoptotic regulation of SMCs in atherosclerotic lesions.     

YC-1 prevents sodium nitroprusside-mediated apoptosis in vascular smooth muscle cells

OBJECTIVE: Nitric oxide signaling pathways are of central importance in both the maintenance of vascular homeostasis and the progression of vascular disease. Since smooth muscle cell apoptosis is associated with numerous vascular disorders, the authors investigated whether YC-1, a soluble guanylyl cyclase (sGC) activator, regulates apoptosis in vascular smooth muscle cells (VSMC). METHODS AND RESULTS: Sodium nitroprusside (SNP) (1 mM) induced cGMP (guanosine 3':5'-cyclic monophosphate)-independent apoptosis in rat vascular smooth muscle cells using MTT assay and TUNEL-reaction techniques. Furthermore, sodium nitroprusside induced apoptosis via Bcl-2 down-regulation, cytochrome c release reaction, and caspase-3 activation by Western blotting analysis and enzymatic assay methods. YC-1 abolished these apoptotic signaling cascades and prevented apoptosis through a cGMP-involved pathway, and phosphatidylinositol (PI) 3-kinase behaved a downstream event in this pathway. CONCLUSIONS: These results suggest that YC-1 inhibits sodium nitroprusside-induced vascular smooth muscle cells apoptosis via a cGMP- and phosphatidylinositol 3-kinase-involved inhibition on Bcl-2 down-regulation/cytochrome c release/caspase-3 activation cascades. The ability of YC-1 to prevent smooth muscle cell apoptosis may play an important role in blocking lesion formation at sites of vascular injury.     

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.     

组织因子途径抑制物基因转移对大鼠血管平滑肌细胞凋亡的影响

目的 研究组织因子途径抑制物(TFPI)基因转移对大鼠血管平滑肌细胞(VSMC)凋亡的影响,探讨其抑制血管成形术后再狭窄的机制.方法 在体外培养的大鼠VSMC中分别转染含有人TFPI基因的重组腺病毒(Ad-TFPI)、含β-半乳糖苷酶基因的重组腺病毒(Ad-LacZ)或PBS.通过RT-PCR方法检测外源TFPI基因的表达.细胞计数和MTT法测定细胞生长情况.电镜技术、流式细胞仪和TUNEL法分别检测细胞凋亡情况.结果 基因转移后3 d在VSMC中检测到TFPI mRNA的表达.细胞计数结果显示第1、3、5天各组细胞数无明显差异,而第7天Ad-TFPI组细胞数明显少于Ad-LacZ组和PBS组(P＜0.05).MTT结果显示基因转移后第1、3、5天各组细胞的吸光度值比较差异无统计学意义,而第7天Ad-TFPI组的吸光度值明显低于Ad-LacZ组(P＜0.05)和PBS组(P＜0.01).流式细胞仪检测结果显示基因转移后3、5、7 d Ad-TFPI组细胞早期凋亡结果均高于Ad-LacZ组.基因转移后3 d和7 d,Ad-TFPI组TUNEL阳性率分别为(10.82±1.57)%和(16.95±2.01)%,明显高于Ad-LacZ组(3.46±0.93)%和(5.11±1.29)%(P＜0.05).透射电镜结果显示基因转移后3、5、7 d Ad-TFPI组细胞逐渐出现体积变小、线粒体轻度肿胀、核固缩以及凋亡小体形成,而Ad-LacZ组则无明显改变.结论 TFPI基因转移能够显著诱导体外培养的大鼠VSMC发生凋亡,可能是其抑制血管成形术后再狭窄的机制之一.     

血管去内皮损伤后平滑肌细胞凋亡的实验观察

目的 了解血管去内皮损伤后新内膜形成及平滑肌细胞(SMCs)凋亡的时相变化。方法用氮气干燥剥脱大鼠颈动脉内皮复制血管损伤模型,HE染色光镜形态计量内膜/中膜比(I/M),末端脱氧核苷酸转移酶(TdT)介导的荧光素d-uTP缺口末端标记(TRNEL)方法观察不同时间新内膜形成(I/M)及VSMC凋亡。结果 血管去内皮后四天,在SMCs增生形成的新内膜中有TUNEL法证实的细胞凋亡,I/M加比,凋亡指数(TUNELI)分别为0.12±0.06,2.4±1.98。在七天,内膜明显增厚(I/M为0.6±0.15,与四天比,P<0.05),TUNELI达到最大值(为9.3±3.8,与四天比,P<0.05)。到第14天,内膜明显增厚约为中膜的1.25倍(I/M比1.25±0.14,与七天比,P<0.05),TUNELI逐渐减小(为8.75±4.01;与七天比,P>0.05)。损伤后21天,内膜开始变薄(I/M比为0.98±0.41,与14天比,P<0.05),凋亡水平进一步下降(TUNELI为6.58±3.97,但差异无显著性,P=NS)。结论 血管壁对损伤刺激诱发增生反应的同时激活凋亡机制。凋亡调节血管壁细胞数和内膜增厚演变。细胞凋亡的平衡失调可能是动脉粥样硬化(AS)、再狭窄(RS)等血管疾病发生的机制之一。     

Overexpression of truncated IkappaBalpha induces TNF-alpha-dependent apoptosis in human vascular smooth muscle cells

Dysregulation of apoptosis is one of the likely underlying mechanisms of neointimal thickening, a disorder in which proinflammatory cytokines may influence the function of vascular smooth muscle cells (VSMCs) and contribute to atherogenesis. One of these cytokines, tumor necrosis factor-alpha (TNF-alpha), induces 2 possibly conflicting pathways, 1 leading to the activation of nuclear factor-kappaB (NF-kappaB) and the other leading to caspase-mediated apoptosis. We investigated whether specific inhibition of NF-kappaB affects TNF-alpha-dependent apoptosis in human VSMCs. To inhibit NF-kappaB activation specifically, we constructed a recombinant adenovirus vector expressing a truncated form of the inhibitor protein IkappaBalpha (AdexIkappaBDeltaN) that lacks the phosphorylation sites essential for activation of NF-kappaB. The IkappaBDeltaN was overexpressed by adenoviral infection and was resistant to stimulus-dependent degradation. Electromobility gel shift and luciferase assays demonstrated that overexpression of IkappaBDeltaN inhibited NF-kappaB activation induced by TNF-alpha or interleukin-1beta (IL-1beta). In cells overexpressing IkappaBDeltaN, TNF-alpha dramatically induced apoptosis, whereas IL-1beta had no effect. The induction was suppressed by treatment with a selective inhibitor of the caspase-3 family, Z-DEVD-fmk, and the overexpression of IkappaBDeltaN induced TNF-alpha-mediated caspase-3 and caspase-2 activity. These results indicate that overexpression of IkappaBDeltaN induces TNF-alpha-dependent apoptosis by efficient and specific suppression of NF-kappaB and upregulation of caspase-3 and caspase-2 activity in human VSMCs. Our findings suggest that adenovirus-mediated IkappaBDeltaN gene transfer may be useful in the treatment of disorders associated with inflammatory conditions, such as the response to vascular injury and atherosclerosis.     

tMfn基因2对大鼠血管平滑肌细胞凋亡的影响

目的:采用腺病毒介导的去除穿膜区序列的大鼠线粒体融合素基因2(tMfn2)感染血管平滑肌细胞(VSMCs),研究其促VSMCs凋亡的作用及其相关的信号通路。方法:用携带大鼠线粒体融合素基因2(Mfn2)的腺病毒(Adv-Mfn2-GFP)和携带tMfn2基因的腺病毒(Adv-tMfn2-GFP)感染VSMCs,采用激光共聚焦显微镜技术观察tMfn2和Mfn2的融合蛋白在细胞中的定位;细胞凋亡ELISA方法、TUNEL染色法研究Mfn2、tMfn2对VSMCs凋亡的影响;Western Blot方法研究tMfn2促进VSMCs凋亡的相关信号通路。结果:激光共聚焦显微镜成像技术证实tMfn2融合蛋白主要游离于细胞质内,而Mfn2融合蛋白主要位于线粒体外膜。采用ELISA方法证实Adv-tMfn2-GFP感染组促进VSMCs凋亡作用比Adv-Mfn2-GFP感染组更显著;Adv-tMfn2-GFP感染组TUNEL染色的凋亡细胞较Adv-Mfn2-GFP感染组明显增多(P<0.05)。Western Blot结果显示,与空白对照组相比,Adv-Mfn2-GFP感染组、Adv-tMfn2-GFP感染组对应的P-Akt条带明显减弱,且后者更显著(P<0.05)。结论:tMfn2由于去除了穿膜区序列,其表达产物主要游离于细胞质中,更易于通过Ras-PI3K/Akt信号通路,抑制Akt的磷酸化,促进VSMCs凋亡,且作用较Mfn2更明显。     

The regulation of vascular smooth muscle cell apoptosis

Apoptosis describes the morphological changes that identify a specific form of regulated cell death. Over recent years, the importance of either aberrant onset or suppression of apoptosis within tissues has become apparent and is associated with the development of several terminal diseases. Here we describe the relevance of apoptosis to the maintenance of vascular homeostasis. Specifically, we address the role of vascular smooth muscle cell death, how this may be regulated at the molecular level and whether any of these molecular mediators will provide targets for intervention in diseases such as atherosclerosis.     

乐卡地平对老年大鼠血管平滑肌细胞增殖和凋亡的影响

目的探讨大鼠血管平滑肌细胞(VSMCs)发生衰老过程中,乐卡地平对细胞增殖和凋亡的影响和作用机制。方法取原代培养的4月龄和24月龄Wistar大鼠VSMCs分别为青年组、老年组,青年和老年大鼠加乐卡地平10μmol/L处理24 h分为青年实验组和老年实验组。采用免疫荧光染色、Western blot法、流式细胞分析仪和Real-time共聚焦等技术检测各组细胞核内p21蛋白结构含量的变化、细胞的增殖及凋亡指数和凋亡率。结果与青年组比较,青年实验组大鼠VSMCs分裂指数明显下降,相差13倍(P<0.05)。与青年组大鼠比较,乐卡地平对老年组大鼠的细胞内钙的抑制作用更强。与老年组比较,老年实验组大鼠细胞分裂指数和凋亡指数降低,差异有统计学意义[(2.08±0.22)%vs(0.7±0.06)%,P<0.05],凋亡率明显下降,差异有统计学意义[(16.1±2.04)%vs(2.3±0.88)%,P<0.01]。与青年组和老年组比较,老年实验组大鼠细胞核内p21蛋白随乐卡地平剂量增加而增强,蛋白结构发生变化,增殖性核抗原表达减少。结论乐卡地平通过改变p21蛋白的结构和含量表达,从而抑制增殖性核抗原表达,抑制VSMCs的增殖,降低老年大鼠VSMCs凋亡,减缓衰老。     

白皮杉醇对过氧化氢诱导的血管平滑肌细胞凋亡的影响与机制

目的:研究白皮杉醇(PCT)对过氧化氢(H2O2)诱导的血管平滑肌细胞(VSMCs)凋亡的影响以及所涉及的相关分子机制。方法:组织贴块法培养SD大鼠VSMCs并进行不同分组与处理;MTT法检测各组VSMCs的存活率;LDH、超氧化物歧化酶(SOD)试剂盒测定各组VSMCs中LDH与SOD活力;Annexin V-PI染色检测各组VSMCs凋亡情况,Hoechst 33258染色观察各组VSMCs细胞核形态变化;Western blot检测各组VSMCs中凋亡相关蛋白(Bcl-2、Bax、caspase-3)及PI3K/AKT/eNOS通路蛋白表达水平。结果:不同浓度与时间过氧化氢(H2O2)处理VSMCs后使其存活率降低,而不同浓度PCT预处理可提高细胞存活率,差异有统计学意义(P<0.05、P<0.01或P<0.001)。与对照组相比,H2O2组VSMCs中LDH活力升高而SOD活力下降,细胞凋亡率增加,细胞中Bax、caspase-3蛋白表达升高而Bcl-2蛋白表达下降,p-PI3K、p-Akt、p-eNOS蛋白表达下降,且均呈剂量依赖关系;与H2O2组相比,PCT预处理组VSMCs LDH活力下降而SOD活力升高,细胞凋亡率降低,细胞中Bax、caspase-3下降,Bcl-2蛋白表达升高,p-PI3K、p-Akt、p-eNOS的蛋白表达升高,且均呈剂量依赖关系,差异有统计学意义(P<0.05或P<0.01)。结论:PCT对H2O2引起的VSMCs损伤有保护作用,其机制可能是抑制LDH活力、增强SOD活力以及增强PI3K/AKT/eNOS信号通路进而阻碍VSMCs凋亡的发生。