粥样斑块稳定化及其调血脂治疗

脂质浸润是粥样斑块形成的中心环节。斑块由脂质核心及纤维帽二部分构成，核心中含有胆固醇、胆固醇脂及泡沫细胞；纤维帽则由增殖的平滑肌细胞、胶原，也有部分泡沫细胞组成。斑块核心脂质的进一步积聚可使斑块增大，使冠状动脉阻塞程度加重，并可能导致斑块破裂。在斑块病变形成过程中，有血管壁平滑肌细胞增生，并可从动脉中层向内膜下层移行，同时伴胶原增生。而增生移行的平滑肌细胞以及来自血液的单核细胞在病变局部可吞噬大量脂质，形成7粥样斑块的重要组成成分——泡沫细胞。降脂药物种类很多，通过不同机制使血清低密度脂蛋白胆固…     

脂多糖通过上调SSAO活性抑制泡沫细胞ABCA1表达和促进细胞内脂质蓄积

目的探讨脂多糖(LPS)是否通过调节氨基脲敏感性胺氧化酶(SSAO)活性改变血管平滑肌细胞源性泡沫细胞三磷酸腺苷结合盒转运体A1(ABCA1)蛋白质的表达和脂质蓄积。方法氧化型低密度脂蛋白(ox-LDL)孵育小鼠主动脉平滑肌原代细胞使其泡沫化,不同浓度LPS和SSAO抑制剂氨基脲(SEM)处理细胞6 h后,高效液相色谱分析细胞SSAO活性、总胆固醇、游离胆固醇和胆固醇酯含量,葡萄糖氧化酶-过氧化物酶法检测培养基葡萄糖含量,荧光分光光度计检测过氧化氢(H2O2)含量,液体闪烁计数器检测细胞内胆固醇流出,Western blot检测ABCA1蛋白质表达的变化。结果 LPS增加泡沫细胞SSAO活性,促进葡萄糖消耗,增加H2O2生成,SEM作用后完全抑制此作用;LPS抑制细胞ABCA1蛋白质的表达,细胞内胆固醇流出减少,细胞总胆固醇、游胆固醇与胆固醇酯增加;SEM作用后部分抑制LPS的这种作用。结论 LPS下调ABCA1蛋白质表达而促进细胞内脂质蓄积与SSAO活性增加相关。     

apelin与动脉粥样硬化的关系

apelin是新近发现的脂肪因子，可通过多种途径参与动脉粥样硬化的发展。其可能机制是参与胰岛素抵抗和脂代谢异常，进而影响动脉粥样硬化的发展；直接影响血管内皮细胞的炎性反应状态，促进单核细胞向血管内皮细胞黏附、迁移；促进细胞内胆固醇流出，减少泡沫细胞的形成；增加斑块稳定性，抑制斑块破裂及血栓形成。深入研究apelin与动脉粥样硬化的关系将为动脉粥样硬化的防治提供新靶点。     

Nε-羧甲基赖氨酸通过RAGE促进平滑肌细胞源性泡沫细胞形成

目的研究Nε-羧甲基赖氨酸(CML)对平滑肌细胞泡沫化中脂质外流的影响,探讨其在促进平滑肌细胞泡沫化中的作用和机制。方法使用组织贴块法从C57BL/6J小鼠主动脉中提取原代血管平滑肌细胞并进行鉴定;将第3~9代的原代平滑肌细胞分为对照组,氧化型低密度脂蛋白(ox-LDL)(50 mg/L)模型组,1、10、100μmol/L的CML与ox-LDL共刺激组,通过NBD-胆固醇流出实验检测CML对泡沫细胞胆固醇流出率的影响,通过胆固醇含量测定试剂盒测定细胞内总胆固醇(TC)、游离胆固醇(FC)和胆固醇酯(CE)水平;将原代血管平滑肌细胞分为四组:对照组、ox-LDL模型组、ox-LDL+CML组、RAGE siRNA沉默组(ox-LDL+CML+siRAGE组)并进行刺激,通过Western blot检测糖基化终末产物受体(RAGE)和胆固醇流出调节子ABCA1的表达;通过油红O染色和油红萃取实验检测各组平滑肌细胞泡沫化程度。结果与对照组相比,不同浓度CML明显升高平滑肌细胞内TC、CE和FC的含量;胆固醇流出实验表明胆固醇流出率随CML浓度升高而降低;Western blot实验表明与对照组相比,加入CML后RAGE明显升高,ABCA1明显降低,ox-LDL+CML+siRAGE组RAGE的表达降低,并且ABCA1降低水平减少;油红O染色显示ox-LDL能够促使平滑肌细胞内脂质蓄积,CML能够增强其作用,抑制RAGE表达后CML作用减弱。结论 CML通过RAGE抑制脂质外流,促进平滑肌细胞源性泡沫细胞形成。     

ECM、MMPs与易损斑块及斑块破裂的关系

细胞外基质(ECM)是血管平滑肌细胞分泌和合成的,是正常血管壁的主要成分,基质金属蛋白酶(MMPs)是降解细胞外基质成分的主要酶类,研究表明纤维帽中平滑肌细胞合成ECM减少和蛋白溶解酶特别是MMPs降解ECM的增加,是斑块破裂的内在主要原因.本文就ECM、MMPs与斑块破裂的关系做一简单综述.     

荷脂细胞与胆固醇逆转运的研究进展

正动脉粥样硬化(atherosclerosis,AS)性心脑血管疾病是导致人类死亡的主要原因。动脉血管壁的粥样斑块是AS性疾病主要的病理表现。斑块部位泡沫细胞的逐渐增多导致斑块扩大及不稳定,进而促进了AS的发展。细胞内胆固醇摄取和流出的失衡是导致泡沫细胞形成的主要原因,促进细胞内胆固醇转运到细胞外,减轻粥样斑块负荷是近年国内外抗AS研究的热点。我们就近年来荷脂细胞的形成、胆固     

中药对动脉粥样硬化血管平滑肌细胞凋亡基因调控作用的研究进展

细胞凋亡(apoptosis)是普遍存在于人体组织细胞内的细胞死亡的形式之一,是不同于坏死的正常生理性的程序性细胞死亡。它参与体内细胞数量的调节,并清除体内无功能的细胞、对机体有害的细胞、突变的细胞以及受到损伤后不能存活的细胞。平滑肌细胞(SMC)是构成血管壁的重要成分,血管平滑肌细胞(VSMC)增殖形成AS,动脉粥样斑块病变是AS发生、发展的重要过程,但后期较严重的AS斑块中由于发生了细胞凋亡,而使纤维帽中的细胞大大减少,使斑块更易破裂。凋亡的发生需要外部信号和内部相关基因共同调控,外部信号通过第二信使进行传递。已经有研究…     

γ-干扰素对平滑肌细胞增殖与凋亡及基质金属蛋白酶活性的影响

目的 :通过研究γ 干扰素对平滑肌细胞增殖和凋亡以及对基质金属蛋白酶 (MMPs)活性的影响 ,了解其对粥样斑块稳定性的影响。　　方法 :①大鼠血管平滑肌细胞体外培养 ,加入不同浓度的γ 干扰素 (10U/ml、10 0U/ml、2 0 0U/ml) ,四甲基偶氮唑唑 (MTT)方法检测细胞的增殖 ,流式细胞仪检测细胞的凋亡。②大鼠腹腔巨噬细胞培养 ,加入不同浓度的γ 干扰素 ,用以明胶为底物的聚丙烯酰胺凝胶电泳酶谱法测定上清液中MMPs的活性。　　结果 :γ 干扰素可以抑制平滑肌细胞增殖 ,促进其凋亡 ,其作用随着浓度的增加而增强。γ 干扰素可使巨噬细胞产生的MMPs活性增强。　　结论 :粥样斑块中γ 干扰素由活化的T淋巴细胞产生 ,可以通过减少斑块内平滑肌细胞数量和增加纤维帽中细胞外基质的降解增加粥样斑块的不稳定性。     

肥大细胞和类胰蛋白酶与心血管疾病

肥大细胞分泌的类胰蛋白酶具有多种生物学活性。这些活性与某些心血管疾病的发生发展密切相关。实验证实,在扩张型心肌病和缺血性心肌病患者的心脏组织中,类胰蛋白酶的含量要高于正常心脏组织。活化的肥大细胞可以通过多种机制降解细胞外基质,其中类胰蛋白酶促进基质金属蛋白酶的生成起到了关键的作用。此外,类胰蛋白酶能够降解纤维蛋白原,诱导内皮细胞、成纤维细胞及平滑肌细胞的增殖,降解纤维连接蛋白。它的这些活性在动脉粥样硬化、血管重构和新生以及血管内皮细胞和平滑肌细胞凋亡的过程中均起到了重要的作用。     

高脂血症兔主动脉内皮剥脱后c-myc基因的表达

本实验在喂高胆固醇饲料的基础上行兔主动脉内皮剥脱术，分别于内皮剥脱术后1、2、4和6周处死动物．观察动脉粥样硬化形成过程中兔主动脉形态、平滑肌细胞超微结构的变化和c－nryc基因表述规律．实验结果发现：内皮剥脱加高胆固醇饲料能在6周内形成较典型的粥样斑块，斑块肉细胞成分主要为平滑肌细胞源性泡沫细胞，巨噬细胞源性泡沫细胞少见。在动脉粥样硬化斑块形成过程申，平滑肌细胞发生表型改变，术后一周新生内膜的平滑肌细胞中肌丝成分减少，细胞器增多，此时C－myc基因表达最高．术后2、4周内膜平滑肌细胞内含有大量细胞器，肌丝成分少见，成为典型的的合成型细胞，从2周开始合成型细胞内已开始出现数个脂滴，且随时间延长而增加，至6周时这些细胞已充满大量脂满，细胞器亦减少。成为肌源性泡沫细胞，2周后，c-myc基因表达逐渐降低。这些结果提示：兔主动脉内皮细胞剥脱能诱导c-myc基因高表达，加速实验性动脉粥样硬化形成。     

不要低估血管平滑肌细胞在动脉粥样硬化斑块形成中的作用

血管内皮细胞、平滑肌细胞(SMC)和巨噬细胞共同参与动脉粥样硬化(As)斑块形成。近年研究表明,SMC来源的细胞占As斑块中细胞总数的70%以上。As斑块中的SMC通过自分泌细胞因子促进自身的增殖、迁移和炎症反应,通过旁分泌激活单核/巨噬细胞并将其募集到As损伤部位,同时通过其细胞膜表面表达的脂蛋白受体摄取脂质形成泡沫细胞。SMC在As斑块形成中扮演十分重要的角色,应进一步深化对SMC在As发生发展中的作用及作用机制的研究。     

Sphingomyelin biosynthesis and efflux correlates with cholesterol metabolism and is higher in vascular endothelial cells than in smooth muscle cells

We compared the metabolism of cellular phospholipids in bovineaortic endothelial and smooth muscle cells in culture [³H]Cholinewas incorporated in both cell types into phosphatidylcholine(86–90%) and sphingomyelin (10–14%) Endothelialcells demonstrated preferential efflux of sphingomyelin whichrepresented 22.5% of the radiolabelled phospholipids in theincubation medium while in smooth muscle cells it represented10%, so that after 7 days, the sphingomyelin b the medium represented40% and 16% of total synthesized sphingomyelin in endothelialand smooth muscle cells, respectively. Incorporation of [³H]choline by endothelial and smooth muscle cells was reduced inthe presence of serum, but not in the presence of lipoproteindeficient serum, indicating that cells can acquire phosphatidylcholineand sphingomyelin fron lipoproteins. Lipoproteins were shownalso to support the efflux of cellular radiolabelled phospholipidsfrom both cell types but at a higher degree from endothelialcells than from smooth muscle cells. Exposure of these culturesto cholesterol rich serum increased the synthesis of phosphatidylcholine,and to a higher extent of sphingomyelin, with concomitant decreasein the efflux of these two phospholipids. These results demonstratethe role of cholesterol in the regulation of phosphatidyl cholineand sphingomyelin biosynthesis and efflux in vascular cells.Furthermore, the higher efflux of sphingomyelin in endothelialcells than in smooth muscle cells may support the extensiveefflux of cholesterol observed in endothelial cells am indicatebiochemical differences in lipid metabolism between vascularendothelial and smooth muscle cells.     

Phagocytosis in atherosclerosis: Molecular mechanisms and implications for plaque progression and stability

Macrophages play a key role in atherosclerotic plaque destabilization and rupture. In this light, selective removal of macrophages may be beneficial for plaque stability. However, macrophages are phagocytic cells and thus have an important additional role in scavenging of modified lipoproteins, unwanted or dead cells and cellular debris via phagocytosis. The concept of phagocytosis as well as the underlying mechanisms is well defined but the effect of phagocytosis in terms of plaque stability remains poorly understood. Recent findings point towards a complex role of macrophage phagocytosis in atherogenesis. Macrophages are necessary for removal of apoptotic cells from plaques, but exert strong proatherogenic properties upon phagocytosis of lipoproteins, erythrocytes and platelets. Apart from heterophagy, autophagocytosis better known as autophagy may occur in advanced atherosclerotic plaques. Several lines of evidence indicate that autophagy is initiated in plaque smooth muscle cells as a result of cellular distress. Since autophagy is well recognized as a survival mechanism, autophagic smooth muscle cells in the fibrous cap may reflect an important feature underlying plaque stability. All together, phagocytosis is a crucial process involved in atherogenesis that may significantly affect the stability of the atherosclerotic plaque.     

Proteolysis of the pericellular matrix: a novel element determining cell survival and death in the pathogenesis of plaque erosion and rupture

The 2 major general concepts about the cell biology of atherogenesis, growth of smooth muscle cells, and lipid accumulation in macrophages, ie, foam cell formation, have not been able to satisfactorily explain the genesis of acute coronary syndromes. Rather, the basic pathology behind the acute atherothrombotic events relates to erosion and rupture of unstable coronary plaques. At the cellular level, we now understand that a switch from cellular growth to cellular death, notably apoptosis, could be involved in turning at least some types of atherosclerotic plaques unstable. Because intimal cells require a proper matrix environment for normal function and survival, the vulnerability of an atherosclerotic plaque may critically depend on the integrity of the pericellular matrix of the plaque cells. In vitro studies have revealed that plaque-infiltrating inflammatory cells, such as macrophages, T-lymphocytes, and mast cells, by secreting a variety of proteases capable of degrading pericellular matrix components, induce death of endothelial cells and smooth muscle cells, and so provide a mechanistic explanation for inflammation-dependent plaque erosion and rupture. Thus, a novel link between inflammation and acute coronary syndromes is emerging. For a more explicit understanding of the role of proteases released by inflammatory cells in the conversion of a clinically silent plaque into a dangerous and potentially killing plaque, animal models of plaque erosion and rupture need to be established.     

Phenotypic High-Throughput Screening in Atherosclerosis Research: Focus on Macrophages

Atherosclerosis is a complex disease characterized by arterial lesions consisting of macrophage foam cells, smooth muscle cells, lymphocytes and other cell types. As atherosclerotic lesions mature, they can rupture and thereby trigger thrombosis that can result in tissue infarction. Macrophage foam cells develop in the subendothelial space when cells take up cholesterol from modified forms of low-density lipoprotein (LDL) and other apolipoprotein B-containing lipoproteins. Current therapies to limit atherosclerosis focus on altering the plasma lipid composition, most commonly by reducing circulating LDL levels. No current therapy is specifically designed to alter the cellular composition of atherosclerotic lesions. To address this deficit, phenotypic high-throughput drug screens have been developed to identify compounds that reduce the uptake of oxidized LDL by macrophages or to identify compounds that increase the efflux of cholesterol from macrophages. Additional phenotypic screens can be envisaged that address cellular processes in active atherosclerotic lesions including macrophage apoptosis and efferocytosis.     

Lipid markers for atherosclerosis

Atherogenesis results from the simultaneous occurrence of 2 important processes: platelet-endothelial interaction, with its consequences mediated by the platelet-derived growth factor, and lipid accumulation. Lipid accumulation results from the balance or imbalance of cellular uptake of lipoproteins versus the removal of cholesterol esters. Uptake results from activity of the low-density lipoprotein (LDL) receptor of smooth muscle cells and fibroblasts, modified LDL receptor and remnant receptors of macrophages. Cholesterol-ester removal is regulated by apolipoprotein A-l. Low levels of apolipoprotein A-l are found in most patients with clinically significant coronary artery disease, suggesting that defects in cellular cholesterol ester removal may play an important role in atherogenesis.     

Mast cell proteases: physiological tools to study functional significance of high density lipoproteins in the initiation of reverse cholesterol transport

The extracellular fluid of the intima is rich in lipid-poor species of high density lipoproteins (HDL) that promote efficient efflux of cholesterol from macrophages. Yet, during atherogenesis, cholesterol accumulates in macrophages, and foam cells are formed. We have studied proteolytic modification of HDL by mast cell proteases as a potential mechanism of reduced cholesterol efflux from foam cells. Mast cells are present in human atherosclerotic lesions and, when activated, they expel cytoplasmic granules that are filled with heparin proteoglycans and two neutral proteases, chymase and tryptase. Both proteases were found to specifically deplete in vitro the apoA-I-containing prebeta-migrating HDL (prebeta-HDL) and other lipid-poor HDL particles that contain only apoA-IV or apoE. These losses led to inhibition of the high-affinity component of cholesterol efflux from macrophage foam cells facilitated by the ATP-binding cassette transporter A1 (ABCA1). In contrast, the diffusional component of efflux promoted by alpha-HDL particles was not changed after proteolysis. Mast cell proteases are providing new insights into the role of extracellular proteolysis of HDL as an inhibiting principle of the initial steps of reverse cholesterol transport in the atherosclerotic intima, where many types of protease-secreting cells are present.     

硝普钠对培养的猪主动脉平滑肌细胞增殖的影响

内皮细胞损伤和血管平滑肌细胞增殖在动脉粥样硬化发生过程中起关键作用，本工作作用离体冠状动脉实验证明硝普钠呈剂量依赖性松驰冠状动脉，且与内皮去除与否无关。用噻唑蓝比色法观察到硝普钠也能剂量依赖性抑制主动脉平滑肌细胞增殖。结果表明，ＮＯ对平滑肌细胞增殖具有调节作用。提示在临床上对于动脉粥样硬化及冠心病病人，长期使用硝普钠等与ＮＯ合成及释放有关的硝基化合物不仅可以缓解冠状动脉痉挛，而且还可抑制平滑肌细胞     

Macrophages and smooth muscle cells express lipoprotein lipase in human and rabbit atherosclerotic lesions.

Lipoprotein lipase (LPL; EC 3.1.1.34) may promote atherogenesis by producing remnant lipoproteins on the endothelial surface and by acting on lipoproteins in the artery wall. In vitro, smooth muscle cells and macrophages synthesize LPL, but in human carotid lesions only a few smooth muscle cells were reported to contain LPL protein. Endothelial cells do not synthesize LPL in vitro, but in normal arteries intense immunostaining for LPL is present on the endothelium. We used Northern blot analysis, in situ hybridization, and immunocytochemistry of human and rabbit arteries to determine cellular distribution and the site of the synthesis of LPL in atherosclerotic lesions. Northern blot analysis showed that LPL mRNA was detectable in macrophage-derived foam cells isolated from arterial lesions of "ballooned" cholesterol-fed rabbits. In situ hybridization studies of atherosclerotic lesions with an antisense riboprobe showed a strong hybridization signal for LPL mRNA in some, but not all, lesion macrophages, which were mostly located in the subendothelial and edge areas of the lesions. Also, some smooth muscle cells in lesion areas also expressed LPL mRNA. Immunocytochemistry of frozen sections of rabbit lesions with a monoclonal antibody to human milk LPL showed intense staining for LPL protein in macrophage-rich intimal lesions. The results suggest that lesion macrophages and macrophage-derived foam cells express LPL mRNA and protein. Some smooth muscle cells in the lesion areas also synthesize LPL. These data are consistent with an important role for LPL in atherogenesis.     

Insolubilization of low density lipoprotein induces cholesterol accumulation in cultured subendothelial cells of human aorta

Primary cultures of typical and modified smooth muscle cells isolated from the intima of human aorta were used to study the mechanism whereby low density lipoprotein (LDL) induces accumulation of intracellular cholesterol. Incubation of intimal cells with native LDL obtained from human plasma did not lead to deposition of total cholesterol. LDL added to the cultures simultaneously with hyaluronic acid, heparin, chondroitin sulfate, fibronectin, and mouse monoclonal antibody against LDL also failed to alter the cellular cholesterol. On the other hand, 24-h incubation of the cells with LDL in the presence of dextran sulfate, gelatin, particles of aortic elastin, particles of collagenase-resistant aortic matrix, goat polyclonal antibodies against LDL or latex beads caused a significant (1.5-7-fold) increase in total cholesterol. The compounds which stimulated cholesterol deposition are able to form precipitating complexes with LDL. On the contrary, the agents which failed to induce cholesterol accumulation were unable to insolubilize LDL. A direct correlation (r = 0.927) was found between the cholesterol content of the insoluble complex and the increment of cholesterol in the cultured cells. To find out whether LDL plays a specific role in the deposition of intracellular cholesterol, very low density lipoproteins and high density lipoproteins were used. These lipoproteins stimulated the accumulation of intracellular cholesterol in the presence of agents capable of forming insoluble associates with them. Our data suggest that insolubilization of lipoproteins is a key event in the LDL-mediated accumulation of intracellular cholesterol induced by various agents.