血管平滑肌细胞自噬与血管钙化关系的研究进展

细胞自噬是细胞利用溶酶体进行自身降解的生物学过程,是一种进化上高度保守的分解代谢过程,对于维持细胞稳态起着重要作用。血管钙化是广泛存在于动脉粥样硬化、糖尿病、终末期肾病等多种疾病中的共同病理表现,是影响心血管疾病死亡率的独立危险因素,目前尚缺乏有效的治疗手段。近年来发现血管平滑肌细胞(VSMCs)自噬可通过调节其降解活动及平滑肌细胞的成骨样分化,从而在调控血管钙化中发挥重要作用。本文就VSMCs自噬与血管钙化的最新研究进展做一综述。     

骨保护素与动脉粥样硬化和血管钙化

骨保护素(OPG)作为肿瘤坏死因子受体超家族成员,不仅是骨代谢的一个重要调节因子,还是重要的血管调节因子,能够保护血管内皮细胞,抑制血管钙化和动脉粥样硬化。冠状动脉粥样硬化性心脏病(冠心病)及外周动脉硬化疾病血清OPG水平及动脉壁中OPG含量明显升高,OPG在动脉粥样硬化的发生发展中可能起着重要的调节作用。但其确切的机制尚不清楚,可能是一种自我防御代偿机制,以对抗促动脉粥样硬化、血管钙化及血管损伤的其它因子。     

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。     

BMP-2 promotes phosphate uptake, phenotypic modulation, and calcification of human vascular smooth muscle cells

Vascular calcification is associated with increased risk of cardiovascular events that are the most common cause of death in patients with end-stage renal disease. Clinical and experimental studies indicate that hyperphosphatemia is a risk factor for vascular calcification and cardiovascular mortality in these patients. Our previous studies demonstrated that phosphate transport through the type III sodium-dependent phosphate cotransporter, Pit-1, was necessary for phosphate-induced calcification and osteochondrogenic phenotypic change in cultured human smooth muscle cells (SMC). BMP-2 is a potent osteogenic protein required for osteoblast differentiation and bone formation that has been implicated in vascular calcification. In the present study, we have examined the effects of BMP-2 on human SMC calcification in vitro. We found that treatment of SMC with BMP-2 enhanced elevated phosphate-induced calcification, but did not induce calcification under normal phosphate conditions. mRNAs for BMP receptors, including ALK2, ALK3, ALK6, BMPR-II, ActR-IIA and ActR-IIB were all detected in human SMCs. Mechanistically, BMP-2 dose-dependently stimulated phosphate uptake in SMC (200 ng/ml BMP-2 vs. vehicle: 13.94 vs. 7.09 nmol/30 min/mg protein, respectively). Real-time PCR and Western blot revealed the upregulation of Pit-1 mRNA and protein levels, respectively, by BMP-2. More importantly, inhibition of phosphate uptake by a competitive inhibitor of sodium-dependent phosphate cotransport, phosphonoformic acid, abrogated BMP-2-induced calcification. These results indicate that phosphate transport via Pit-1 is crucial in BMP-2-regulated SMC calcification. In addition, BMP-2-induced Runx2 and inhibited SM22 expression, indicating that it promotes osteogenic phenotype transition in these cells. Thus, BMP-2 may promote vascular calcification via increased phosphate uptake and induction of osteogenic phenotype modulation in SMC.     

Pathophysiology of vascular calcification: Pivotal role of cellular senescence in vascular smooth muscle cells

The accumulation of senescent cells within tissues can potentially lead to biological dysfunction and manifestation of disease associated with ageing. The majority of senescent cells display a commonly altered secretome similar to a wound healing response (termed the senescence-associated secretory phenotype or SASP), which could have deleterious implications on the tissue microenvironment. However, senescent cells also appear to have a cell-type (or even cell-strain) exclusive senescent phenotype (CESP), an area of research that is underexplored. One such CESP is the pro-calcificatory phenotype recently reported in senescent vascular smooth muscle cells (VSMCs). Senescent VSMCs have been shown to overexpress genes and proteins (including RUNX-2, alkaline phosphatase (ALP), type I collagen and BMP-2) associated with osteoblasts, leading to partial osteoblastic transdifferentiation. As such, it has been suggested that senescent VSMCs contribute to cardiovascular dysfunction through induction of vascular calcification. This review discusses recent findings on VSMC senescence and their potential role in the pathophysiology of vascular calcification.     

Fenofibrate modifies human vascular smooth muscle proteoglycans and reduces lipoprotein binding

Aims/hypothesis Vascular disease in type 2 diabetes is associated with an up-regulation of atherogenic growth factors, which stimulate matrix synthesis including proteoglycans. We have examined the direct actions of fenofibrate on human vascular smooth muscle cells (VSMCs) and have specifically investigated proteoglycan synthesis and binding to LDL.Methods Proteoglycans synthesised by human VSMCs treated with fenofibrate (30 µmol/l) were assessed for binding to human LDL using a gel mobility shift assay, metabolically labelled with [³⁵S]-sulphate and quantitated by cetylpyridinium chloride. They were then assessed for electrophoretic mobility by SDS-PAGE, for size by gel filtration, for sulphation pattern by fluorophore-assisted carbohydrate electrophoresis, and for glycosaminoglycan (GAG) composition by enzyme digestion.Results Proteoglycans synthesised in the presence of fenofibrate showed an increase in the half-maximum saturation concentration of LDL from 36.8±12.4 µg/ml to 77.7±17 µg/ml under basal conditions, from 24.9±4.6 µg/ml to 39.1±6.1 µg/ml in the presence of TGF-1, and from 9.5±4.4 µg/ml to 31.1±3.4 µg/ml in the presence of platelet-derived growth factor/insulin. Fenofibrate treatment in the presence of TGF-1 inhibited the incorporation of [³⁵S]-sulphate into secreted and cell-associated proteoglycans synthesised by human VSMCs by 59.2% (p<0.01) and 39.8% (p<0.01) respectively. The changes in sulphate incorporation following treatment with fenofibrate were associated with a concentration-related increase in the electrophoretic mobility due to a reduction in GAG length. There was no change in the sulphation pattern; however, there was an alteration in the disaccharide composition of the GAGs.Conclusions/interpretation Fenofibrate modifies the structure of vascular proteoglycans by reducing the length of the GAG chains and GAG composition, resulting in reduced binding to human LDL, a mechanism which may lead to a reduction of atherosclerosis and cardiovascular disease in people with diabetes treated with fenofibrate.     

Relationship between serum osteoprotegerin and vascular calcifications in hemodialysis patients

Background

Uremia is a vasculopathic process, and both cardiac calcification and vascular calcification seen from the early stages of chronic kidney disease. Osteoprotegerin could play a crucial role in atherosclerotic plaque formation, maturation and calcification. The goal of this study was to determine the relationship of serum osteoprotegerin with vascular calcification in patients with end stage kidney disease who were maintained on regular hemodialysis.

白细胞介素-6对兔血管平滑肌细胞产生C反应蛋白的影响

目的:探讨白细胞介素-6(IL-6)能否诱导体外原代培养的兔血管平滑肌细胞(VSMCs)产生C反应蛋白(CRP)。方法:体外原代培养新西兰兔腹主动脉VSMCs。分别用白细胞介素(IL)-6(10 ng/ml)、IL-1β25 ng/ml或IL-6(10 ng/ml)+IL-1β(25 ng/ml)刺激VSMCs 48 h。对照组用等体积的IL-6的溶剂孵育48 h。反转录聚合酶链反应(RT-PCR)和免疫印迹法(Western blot)分别检测培养细胞CRP mRNA和蛋白的表达情况。结果:对照组的原代VSMCs未见CRP的产生。VSMCs与IL-6单独孵育48 h后,CRP mRNA的表达量是对照组的(3.50±1.17)倍,能产生少量CRP,与对照组相比有差异。单独应用IL-1β不能诱导VSMCs产生CRP,但是在IL-1β和IL-6的联合刺激下,CRP mRNA表达量是对照组的(5.92±1.30)倍,CRP的合成亦达最大值。结论:IL-6能诱导原代培养的兔VSMCs产生CRP。尽管单独应用IL-1β不能刺激VSMCs产生CRP,但是它却能显著增强IL-6诱导CRP的表达。     

Inflammatory stimuli upregulate Rho-kinase in human coronary vascular smooth muscle cells

Recent studies have demonstrated that upregulated Rho-kinase plays an important role in the pathogenesis of arteriosclerosis and vasospasm in both animals and humans. However, little is known about the molecular mechanism(s) involved in the Rho-kinase upregulation. Since inflammatory mechanisms have been implicated in the pathogenesis of arteriosclerosis and vasospasm, we examined whether inflammatory stimuli upregulate Rho-kinase in vitro and in vivo. In cultured human coronary vascular smooth muscle cells (hcVSMC), inflammatory stimuli, such as angiotensin II and interleukin-1beta, increased Rho-kinase expression (at both mRNA and protein levels) and function (as evaluated by the extent of the phosphorylation of the ERM (the ezrin/radixin/moesin) family, substrates of Rho-kinase) in a time- and concentration-dependent manner. The expression of Rho-kinase was inhibited by blockades of protein kinase C (PKC) (by either GF109253 or prolonged treatment with phorbol myristate acetate for 24 h) and an adenovirus-mediated gene transfer of dominant-active Ikappa-B, suggesting an involvement of PKC and NF-kappaB in the intracellular signal transduction pathway for the Rho-kinase expression. Furthermore, coronary vascular lesion formation (characterized by medial thickening and perivascular fibrosis) induced by a long-term administration of angiotensin II was markedly suppressed in NF-kappaB(-/-) mice with reduced expression and activity of Rho-kinase in vivo. These results indicate that the expression and function of Rho-kinase are upregulated by inflammatory stimuli (e.g. angiotensin II and IL-1beta) in hcVSMC with an involvement of PKC and NF-kappaB both in vitro and in vivo.     

7-Ketocholesterol predisposes human aorta smooth muscle cells to Fas-mediated death

Human vascular smooth muscle cells (HVSMCs) are resistant to Fas-mediated death under normal physiological conditions. However, HVSMC death by activation of the receptor pathway was reported in the atherosclerotic lesions. In this study, we investigated whether 7-ketocholesterol, one of the major cholesterol oxides in the lesions, altered resistance of HVSMC to Fas-mediated death pathway. Cross-linking of Fas receptor with agonistic anti-Fas antibody (CH11) in the presence of 7-ketocholesterol induced death in human aorta smooth muscle cells (HAoSMC) as detected by morphology, viability, and DNA fragmentation. The agonistic anti-Fas antibody, however, did not induce death in the presence of 7alpha-hydroxycholesterol or cholesterol. The HAoSMC death was significantly inhibited by an antagonistic Fas receptor (FasR) antibody and by expression of dominant negative Fas-associated death domain containing protein (DN-FADD) using adenoviruses. Activation of caspase-3 was observed in HAoSMC destined to death. HAoSMC death was significantly inhibited by pharmacological caspase inhibitor, z-VAD and z-DEVD, and baculovirus caspase inhibitor p35. 7-Ketocholesterol impaired mitochondrial transmembrane potential and ATP production. Overexpression of bcl-xL also significantly inhibited HAoSMC death. In dying HAoSMC, bax was translocated from the cytosol to mitochondria and cytochrome c was released from mitochondria into the cytosol. This is the first report demonstrating implication of the oxysterol in Fas-mediated death pathway. The present study proposes that 7-ketocholesterol would contribute to loss of HVSMC in the atherosclerotic lesions by altering resistance to receptor-mediated death pathway.     

匹伐他汀对血管平滑肌细胞金属基质蛋白酶9表达的影响

目的 观察金属基质蛋白酶9(MMP-9)在动脉粥样硬化组织中的分布及匹伐他汀对TNF-α刺激血管平滑肌细胞MMP-9 蛋白和mRNA 表达的影响.方法 病理标本取自外科择期手术病例,行常规病理和免疫组织化学检查;对照组动脉标本取自非正常死亡健康成人尸体及非血管病变切除标本;血管平滑肌细胞取自开放手术切除的主动脉中膜.实验为5 组,对照组和4 个实验组.实验各组平滑肌细胞在给予TNF-α刺激前预先加入不同浓度的匹伐他汀(分别为1 ng/ml、10 ng/ml、100 ng/ml、500 ng/ml),测定其MMP-9 蛋白和mRNA 表达.结果 免疫组化检测显示,实验组动脉硬化组织TNF-α和MMP-9 蛋白分布明显增加,主要集中在炎性细胞聚集处,与对照组比较差异有统计学意义;MMP-9 的分布与TNF-α明显相关.匹伐他汀呈浓度依赖方式抑制TNF-α诱导平滑肌细胞MMP-9 蛋白和mRNA 表达;MMP-9 蛋白表达分别减少10.5%、24.1%、46.0%和61.0%,mRNA 表达分别减少9%、21%、35%和46%,差异有统计学意义.结论 动脉硬化组织中MMP-9 分布与TNF-α明显相关,提示动脉粥样硬化组织中MMP-9 增加与其他细胞因子相互影响有关.预先给予匹伐他汀可以呈现浓度依赖方式显示抑制TNF-α诱导的血管平滑肌细胞MMP-9 蛋白和mRNA 表达,提示他汀类药物可以通过抑制MMP-9 表达,延缓、稳定动脉粥样硬化病变,早期干预效果更好.     

Bone morphogenetic proteins in vascular calcification

Vascular calcification is a common problem among the elderly and those with chronic kidney disease (CKD) and diabetes. The process of tunica media vascular calcification in CKD appears to involve a phenotypic change in the vascular smooth muscle cell (VSMC) resulting in cell-mediated mineralization of the extracellular matrix. The bone morphogenetic proteins (BMPs) are important regulators in orthotopic bone formation, and their localization at sites of vascular calcification raises the question of their role. In this review, we will discuss the actions of the BMPs in vascular calcification. Although the role of BMP-2 in vascular calcification is not proven, it has been the most studied member of the BMP family in this disease process. The role of BMP-2 may be through inducing osteoblastic differentiation of VSMCs through induction of MSX-2, or by inducing apoptosis of VSMCs, a process thought critical in the initiation of vascular calcification. Additionally, BMP-2 may be related to loss of regulation of the matrix Gla protein. A second BMP, BMP-7, less studied than BMP-2 may have opposing actions in vascular calcification. In postnatal life, BMP-7 is expressed primarily in the kidney, and expression is diminished by renal injury. BMP-7 is an important regulator of skeletal remodeling and the VSMC phenotype. BMP-7 restores skeletal anabolic balance in animal models of CKD with disordered skeletal modeling, also reducing serum phosphate in the process. BMP-7 also reverses vascular calcification in CKD, and reduction in vascular calcification is due, in part, to reduced serum phosphate, an important inducer of VSMC-mediated vascular mineralization and in part to direct actions on the VSMC.     

血管平滑肌细胞表型的成骨转换与血管钙化

血管钙化是血管壁中钙盐沉积的过程,导致血管硬化和失去弹性。它通常发生在中老年人,尤其是患有动脉粥样硬化、高血压、糖尿病和慢性肾脏疾病等疾病患者。血管钙化是一个主动的过程,其中平滑肌细胞的成骨转换是重要事件之一。这些细胞在钙化过程中释放钙离子,导致钙盐的沉积,形成钙化斑块。血管钙化受多种因素调节,包括高磷、高钙水平及氧化应激、机械应力等。此外,中医药研究在减轻血管钙化方面显示出潜力,例如灵芝孢子粉和其衍生物,三七、黄芩素、根皮素、雷公藤甲素等。这些研究为进一步理解和干预血管钙化提供了重要的证据,并揭示了一些潜在的抑制因子,可以作为未来治疗血管钙化的研究方向。     

护骨素与糖尿病及其血管并发症关系研究进展

糖尿病血管病变是糖尿病主要并发症,护骨素（OPG）与血管疾病密切相关.本文概述OPG的结构、表达调控、生物学作用,探讨OPG与糖尿病及其血管并发症（大、微血管并发症及内皮功能异常）的关系.     

Nicotine exposure alters human vascular smooth muscle cell phenotype from a contractile to a synthetic type

Objective: Cigarette smoking is a known risk factor for arteriosclerosis. In atheromatous plaques, vascular smooth muscle cells (VSMCs) display a phenotype that is different from the contractile type under normal conditions. Nicotine is the major pharmacological agent in cigarette smoke. However, any direct effect of nicotine on VSMCs remains uncertain. Because nicotine promotes VSMC migration, its phenotype may change due to nicotine. Approach and results: We used human aorta primary smooth muscle cells (HuAoSMCs), differentiated with transforming growth factor-β, to investigate changes in the protein levels of differentiation markers and in the activity of mitogen-activated protein kinases (MAPKs) after exposure to 0.1 μM of nicotine for 48 h. After nicotine exposure, the protein levels of myosin II 10 (2.93-fold) and β-actin (1.66-fold), synthetic type markers, were increased. In contrast, the levels of the contractile type markers, myosin II 11 (0.63-fold), high-molecular-weight caldesmon (0.40-fold) and SM22 (0.66-fold), which concern differentiated VSMC, were decreased. Moreover, nicotine exposure induced enhanced activation of p38 MAPK (1.30-fold) and extracellular signal-regulated kinase (1.91-fold). These results indicated that the phenotype of HuAoSMCs had changed to a synthetic-like type because of nicotine exposure. Thus, nicotine is one factor that can alter protein expression of differentiation markers in VSMCs. Besides, the increase of intracellular Ca²⁺ levels suggested that these effects of nicotine were mediated through nicotinic acetylcholine receptors. Conclusion: Nicotine has already been reported to promote VSMC migration from the tunica media to atheromatous plaques in the vascular intima. This phenomenon may occur because nicotine directly induces VSMC transformation from contractile type to synthetic-like type via nicotinic acetylcholine receptors and G protein-coupled receptors.     

Paracrine effect of human vascular endothelial cells on human vascular smooth muscle cell proliferation: Transmembrane co-culture method

Summary To investigate the role endothelial cells have on underlying smooth muscle cell proliferation, human aortic vascular smooth muscle cells were co-cultured with human aortic endothelial cells at different cell densities, using a transmembrane co-culture method. Subconfluent endothelial cells subseeded at low (0.5 × 10⁴ cells/well) and medium densities (2.0 × 10⁴ cells/well) stimulated smooth muscle cell proliferation by 43 ± 14% (P < 0.01) and 39 ± 8% (P < 0.02), respectively. However, this stimulatory effect on smooth muscle cell proliferation was not evident in confluent endothelial cells subseeded at high cell density (8.0 × 10⁴ cells/well). Treatment of smooth muscle cells with trapidil, at 10^–6M, for anti-platelet derived growth factor (PDGF) effect or with endothelin-1 receptor blocker FR 139317, at 10^–6M failed to inhibit this stimulatory effect. These results imply that subconfluent human endothelial cells are able to exert a stimulatory effect on human smooth muscle cell proliferation, and that this endothelial paracrine growth effect may not be mediated by endothelin or PDGF.     

干扰SET8调节血管平滑肌细胞增殖、凋亡促进血管钙化

背景与目的血管平滑肌细胞(VSMC)凋亡在许多血管钙化疾病的病理过程中起关键作用。近期研究表明,赖氨酸甲基转移酶SET8参与调节细胞增殖、凋亡过程。文章旨在探寻SET8是否通过调节VSMC增殖、凋亡而影响血管钙化。方法体外培养原代大鼠VSMC,将VSMC随机分为正常对照组、空质粒组和SET8-shRNA组。以脂质体Lipofectamine~(TM)2000为载体,转染VSMC。采用茜素红染色法和钙含量测定法判断细胞钙化程度;采用MTT法检测三组细胞的增殖能力;实时荧光定量PCR、Western blot法检测三组细胞中增殖基因Survivin和凋亡基因Caspase-3的表达水平,分析干扰SET8对VSMC增殖、凋亡及其相关基因和蛋白表达的影响。结果 (1)干扰SET8可成功抑制VSMC中SET8蛋白的表达(P0.05)。(2)转染VSMC后,与正常对照组和空质粒组比较,SET8-shRNA组钙含量明显升高(P0.05)。(3)MTT结果显示,在第12 h、24 h、36 h、48 h,SET8-shRNA组VSMC的增殖能力较正常对照组和空质粒组明显降低(P0.05)。(4)实时荧光定量PCR和Western blot结果显示SET8-shRNA组Survivin的mRNA和蛋白表达较正常对照组和空质粒组明显下降,而Caspase-3的mRNA和蛋白表达则相反(P0.05)。结论干扰SET8能够增加促凋亡基因表达,抑制增殖基因表达,SET8有可能参与调节大鼠血管钙化。     

Glucocorticoids and protein kinase C regulate neutral endopeptidase 24.11 in human vascular smooth muscle cells

Neutral endopeptidase 24.11 (NEP) degrades vasoactive peptides, including natriuretic peptides, kinins, angiotensins, and endothelins. It contributes to the regulation of vascular tone and body fluid homeostasis. In the present study the expression of NEP was investigated in cultured human smooth muscle cells derived from umbilical veins (HSMC) and human coronary arteries (HCSMC). A constitutive NEP expression was found in growing and starved smooth muscle cells and was about 4 fold higher than in endothelial cells derived from umbilical veins. Treatment of smooth muscle cells with dexamethasone (0.01–0.1 μM Dex) and with the protein kinase C activator, phorbol myristate acetate (0.1 μM PMA), increased NEP mRNA by 3–4 fold and two fold, respectively. Dexamethasone (0.1 μM) and prednisolone (0.1 μM) increased protein concentrations of NEP and NEP‐activity after 3 days and continued to increase at 5 days, whereas PMA induced maximal increase of NEP concentrations after 48 hours. The effect of dexamethasone was concentration‐dependent and was comletely abolished by cycloheximide (10 μM), a protein synthesis inhibitor. The effect of PMA on NEP protein was completely blocked by protein kinase C inhibitors, calphostin C and H7 (both 10 μM). NEP 24.11 is constitutively expressed in human smooth muscle cells from unbilical veins and coronary arteries and is upregulated by glucocorticoids and by protein kinase C activation in these cells. Received: 17 March 1997, Returned for 1. revision: 5 May 1997, 1. Revision received: 31 July 1997, Accepted: 29 August 1997