Endothelin-1 plus oxidized low-density lipoprotein, but neither alone, increase human monocyte adhesion to endothelial cells.

Endothelin-1 is a potent vasoconstrictor and mitogenic peptide that is implicated in the atherosclerosis of apolipoprotein E-deficient mice and may promote atherogenesis in humans. We hypothesized that endothelin-1 might promote the adhesion of monocytes to endothelial cells, a key early event in atherosclerosis. We investigated the adhesion of primary human monocytes (isolated by elutriation) to human umbilical vein endothelial cell cultures after incubation with endothelin-1 (0.1 and 0.01 nM; approximately physiological concentrations), copper-oxidized low-density lipoprotein (LDL) (0.1 mg/ml) and a combination of the two. After a 4 h incubation with 0.1 or 0.01 nM endothelin-1 combined with oxidized LDL, adhesion was increased to 120+/-4% (P<0.001 compared with control) and 118+/-4% (P<0.002) respectively, whereas neither substance alone increased adhesion (92-104% of control values; not significant). Neither endothelin receptor A blockade nor co-incubation with anti-fibronectin antibody inhibited the pro-adhesive effects of endothelin-1 plus oxidized LDL (115+/-7% and 115+/-3% of control compared with 120+/-4% respectively; not significant). Endothelial cell expression of intercellular adhesion molecule-1, vascular adhesion molecule-1 and E-selectin were unchanged throughout the experiment. Therefore physiological concentrations of endothelin-1 and oxidized LDL may act synergistically to increase the adhesion of human monocytes to endothelial cells, contributing in part to the observed pro-atherogenic effects of endothelin-1.     

Angiotensin II type 1 receptor antagonists inhibit basal as well as low-density lipoprotein and platelet-activating factor-stimulated human monocyte chemoattractant protein-1

Monocyte chemoattractant protein-1 (MCP-1) is a potent chemotactic agent for monocytes and other cells and is thought to be involved in atherosclerosis, recruiting monocytes to the subendothelial space or to the site of inflammation. Angiotensin II has been demonstrated, at least in animal models, to stimulate MCP-1 expression. We investigated the effect of the angiotensin II type 1 (AT1) receptor antagonists irbesartan and losartan on MCP-1 production by freshly isolated human monocytes. Irbesartan and losartan inhibited basal MCP-1 production in a dose-dependent manner. Low-density lipoprotein (LDL) stimulated MCP-1 in a concentration-dependent manner, with 200 microg/ml LDL protein giving a 2-fold increase in MCP-1. Irbesartan and losartan dose dependently blocked LDL-stimulated MCP-1. An angiotensin II type 2 receptor antagonist, S-(+)-1-([4-(dimethylamino)-3-methylphenyl]methyl)-5-(diphenylacetyl)-4,5,6,7-tetrahydro-1H-imidazo(4,5-c)pyridine-6-carboxylic acid (PD123319), had no significant effect on basal MCP-1 levels or LDL-stimulated MCP-1. After noting homology between the AT1 receptor and the platelet-activating factor (PAF) receptor, we showed that irbesartan inhibited both [3H]PAF binding to human monocytes and carbamyl-PAF stimulation of MCP-1. However, irbesartan affinity for the PAF receptor was 700 times less than PAF, suggesting that there may be another mechanism for irbesartan inhibition of PAF-stimulated MCP-1. This is the first report showing that AT1 receptor antagonists inhibit basal as well as LDL- and PAF-stimulated MCP-1 production in freshly isolated human monocytes.     

Minimally modified low-density lipoprotein induces monocyte adhesion to endothelial connecting segment-1 by activating beta1 integrin

We have shown previously that treatment of human aortic endothelial cells (HAECs) with minimally modified low-density lipoprotein (MM-LDL) induces monocyte but not neutrophil binding. This monocyte binding was not mediated by endothelial E-selectin, P-selectin, vascular cell adhesion molecule-I, or intercellular adhesion molecule-I, suggesting an alternative monocyte-specific adhesion molecule. We now show that moncytic alpha4beta1 integrins mediate binding to MM-LDL-treated endothelial cells. We present data suggesting that the expression of the connecting segment-1 (CS-1) domain of fibronectin (FN) is induced on the apical surface of HAEC by MM-LDL and is the endothelial alpha4beta1 ligand in MM-LDL-treated cells. Although the levels of CS-1 mRNA and protein were not increased, we show that MM-LDL treatment causes deposition of FN on the apical surface by activation of beta1integrins, particularly those associated with alpha5 integrins.Activation of beta1 by antibody 8A2 also induced CS-1-mediated monocyte binding. Confocal microscopy demonstrated the activated beta1 and CS-1colocalize in concentrated filamentous patches on the apical surface of HAEC. Both anti-CS-1 and an antibody to activated beta1 showed increased staining on the luminal endothelium of human coronary lesions with active monocyte entry. These results suggest the importance of these integrin ligand interactions in human atherosclerosis.     

LOX-1, the receptor for oxidized low-density lipoprotein identified from endothelial cells: implications in endothelial dysfunction and atherosclerosis

Lectin-like oxidized low-density lipoprotein (LDL) receptor-1 (LOX-1) was initially identified as the major receptor for oxidized LDL (OxLDL) in endothelial cells. Its inducible expression in macrophages and smooth muscle cell was also observed. LOX-1 is a Type II membrane protein with a typical C-type lectin structure at the extracellular C-terminus. It can be cleaved by an unknown protease at the extracellular juxtamembrane region to release the soluble form of LOX-1. The extracellular domains of LOX-1 are post-translationally modified by N-linked glycosylation. Mutagenesis studies revealed that the lectin domain of LOX-1 is the functional domain that recognizes the LOX-1 ligand. The C-terminal end residues and several conserved positively charged residues spanning the lectin domain are essential for OxLDL binding. LOX-1 activation by OxLDL causes endothelial changes that are characterized by activation of nuclear factor-kappaB through an increased reactive oxygen species, subsequent induction of adhesion molecules, and endothelial apoptosis. In vitro, expression of LOX-1 is induced by many inflammatory cytokines, oxidative stress, hemodynamic stimuli, and OxLDL. In vivo, the expression is enhanced in pro-atherogenic settings including, hypertension, hyperlipidemia, and diabetes, and, indeed, is accumulated in the atherosclerotic and glomerulosclerotic lesions. LOX-1 binds multiple classes of ligands that are implicated in the pathogenesis of atherosclerosis. Besides OxLDL, LOX-1 can recognize apoptotic/aged cells, activated platelets, and bacteria, implying versatile physiological functions. Taken together, all these findings support the possible contribution of LOX-1 to the pathogenesis of vascular disorders, particularly atherosclerosis. Development of antagonists for LOX-1 might be a good therapeutic approach to vascular diseases.     

Cilostazol suppresses superoxide production and expression of adhesion molecules in human endothelial cells via mediation of cAMP-dependent protein kinase-mediated maxi-K channel activation

This study shows whether increased intracellular cAMP level by cilostazol is directly coupled to its maxi-K channel activation in human endothelial cells. Cilostazol (1 microM) increased the K+ currents in the human endothelial cells by activating maxi-K channels, which was abolished by iberiotoxin (100 nM), a maxi-K channel blocker. On incubation of human coronary artery endothelial cells with tumor necrosis factor-alpha (TNF-alpha) (50 ng/ml), monocyte adhesion significantly increased with increased superoxide generation and expression of vascular cell adhesion molecule-1 (VCAM-1) and monocyte chemoattractant protein-1 (MCP-1) accompanied by increased degradation of inhibitory kappaBalpha in cytoplasm and activation of nuclear factor-kappaB p65 in nucleus. All these variables were significantly suppressed by cilostazol (10 microM), which was antagonized by iberiotoxin (1 microM) and (9R,10S,12S)-2,3,9,10,11,12-hexahydro-10-hydroxy-9-methyl-1-oxo-9,12-epoxy-1H-diindolo[1,2,3-fg:3',2',1'-kl]pyrrolo[3,4-l] [1,6]benzodiazocine-10-carboxylic acid hexyl ester (KT 5720) (300 nM, cAMP-dependent protein kinase inhibitor), but not by (9S,10R,12R)-2,3,9,10,11,12-hexahydro-10-methoxy-2,9-dimethyl-1-oxo-9,12-epoxy-1H-diindo-lo[1,2,3-fg:3',2',1'-kl]pyrrolo[3,4-I][1,6]benzodiazocine-10-carboxylic acid methyl ester (KT 5823) (300 nM, cGMP-dependent protein kinase inhibitor). In the human endothelial cells transfected with siRNA-targeting maxi-K channels, cilostazol did not suppress the superoxide generation, VCAM-1 and MCP-1 expressions, and monocyte adhesion as contrasted with the wild-type cells. These findings were similarly evident with (3S)-(+)-(5-chloro-2-methoxyphenyl)-1,3-dihydro-3-fluoro-6-(trifluoromethyl)-2H-indole-2-one (BMS-204352), a maxi-K channel opener, and forskolin and dibutyryl cAMP. In conclusion, increased cAMP level by cilostazol is directly coupled to its maxi-K channel opening action via protein kinase activation in human endothelial cells, thereby suppressing TNF-alpha-stimulated superoxide production and expression of adhesion molecules.     

人脐静脉内皮细胞中单核细胞趋化因子1表达与糖化白蛋白的影响

背景：研究表明，糖化白蛋白在内皮细胞凋亡过程中发挥重要作用，并通过增加丝裂原活化蛋白激酶、酪氨酸激酶活性和产生活性氧产物介导单核细胞趋化因子1。 目的：观察糖化白蛋白对培养的人脐静脉内皮细胞的单核细胞趋化因子1表达的影响。 设计、时间及地点：单一样本观察，于2006—05／11在东南大学心血管实验室完成。 材料：脐静脉内皮建株人脐静脉内皮细胞ECV304，引自中国科学院上海细胞生物研究所。 方法：实验分两部分，第一部分以糖化白蛋白（浓度为400mg／L）对人脐静脉内皮细胞分别干预0，8，16，24，48，72h；第二部分以不同浓度（100，200，400，800mg／L）的糖化白蛋白对人脐静脉内皮细胞干预24h。两部分实验均用无血清培养基RPMI 1640和不含牛血清白蛋白葡萄糖干预（浓度为400mg／L）的无血清培养基作为对照。 主要观察指标：四甲基偶氮唑盐微量酶反应比色法检测人脐静脉内皮细胞增殖，酶联免疫吸附法检测人脐静脉内皮细胞上清液单核细胞趋化因子1含量。 结果：①不同时间点糖化白蛋白对人脐静脉内皮细胞增殖的抑制作用依次为48h〉24h〉16h（相临时间点比较，P均〈0．05）；干预8h对细胞的抑制无明显作用，72h抑制作用弱于48h。②与RPMI1640组和牛血清白蛋白组相比，糖化白蛋白400mg／L及800mg／L对细胞的抑制作用明显增强（P〈0．05），并随着糖化白蛋白浓度的增高而增强。③用浓度为400mg／L的糖化白蛋白干预6h及12h，人脐静脉内皮细胞单核细胞趋化因子l表达持续升高（P〈0．05）；随着糖化白蛋白浓度加大，细胞的单核细胞趋化因子1表达进一步增高，800mg／L时达到最高峰。 结论：①糖化白蛋白以浓度、时间依赖方式抑制人脐静脉内皮细胞增殖，并在一定时间范围内呈时间依赖性地增加人脐静脉内皮细胞表达单核细胞趋化因子1表达。     

Azelnidipine, a new long-acting calcium-channel blocker, inhibits tumour necrosis factor-alpha-induced monocyte chemoattractant protein-1 expression in endothelial cells

Dihydropyridine-based calcium antagonists are among the most widely used drugs for the treatment of hypertension. Since azelnidipine is a highly lipid-soluble dihydropyridine-based calcium antagonist with high vascular affinity, it is conceivable that azelnidipine could play a protective role against atherosclerosis. The aim of this study was to determine whether azelnidipine could suppress the expression of monocyte chemoattractant protein-1, a principal chemokine which mediates the recruitment of monocytes to the vasculature, in tumour necrosis factor (TNF)-alpha-exposed human umbilical vein endothelial cells. TNF-alpha, at a concentration of 10 ng/ml, upregulated monocyte chemoattractant protein-1 mRNA levels about seven-fold. Azelnidipine, 10 nmol/l, was found to inhibit the TNF-alpha-induced upregulation of monocyte chemoattractant protein-1 mRNA levels in human umbilical vein endothelial cells significantly. Furthermore, azelnidipine suppressed TNF-alpha-induced monocyte chemoattractant protein-1 production by human umbilical vein endothelial cells. This study demonstrates a novel beneficial aspect of azelnidipine, whereby azelnidipine could play a protective role against atherosclerosis by suppressing monocyte chemoattractant protein-1 overexpression in endothelial cells.     

银杏黄酮苷元对ox-LDL诱导的人脐静脉内皮细胞P-选择素、LOX-1表达的影响

目的：探讨银杏黄酮苷元（ginkgetin aglycone,GA）对氧化低密度脂蛋白（oxidized-low density lipoprotein,ox-LDL）诱导的人脐静脉内皮细胞P-选择素和植物血凝素样氧化低密度脂蛋白受体-1（lectin—like oxidized low density lipoprotein receptor-1,LOX-1）表达的影响。方法：培养人脐静脉内皮细胞株ECV304,分为对照组、ox-LDL组、LOX-1拮抗剂聚肌苷酸加ox-LDL混合刺激组（聚肌苷酸组）、不同含量GA加ox-LDL混合刺激组（GA6．25mg／L组、GA12．5mg／L组、GA25mg／L组和GA50mg／L）,通过逆转录聚合酶链式反应检测P-选择素mRNA和LOX-1mRNA表达,用ELISA检测各组培养基上清中P-选择素蛋白含量,辣根过氧化物酶免疫组织化学法检测LOX．1蛋白,并作比较。结果：OX-LDL上调内皮细胞P-选择素和LOX-1表达（P〈0．05）;6．25～50mg／LGA明显抑制OX-LDL诱导的内皮细胞P-选择素mRNA和LOX．1mRNA和蛋白表达（P〈0．05）;聚肌苷酸可部分或完全阻断OX-LDL诱导的内皮细胞P．选择素mRNA、LOX-1mRNA及其蛋白表达（P〈0．05）。结论：GA通过抑制LOX-1表达而降低内皮细胞合成和分泌黏附分子P-选择素,这可能是其抗动脉粥样硬化的机制之一。     

Statins modulate oxidized low-density lipoprotein-mediated adhesion molecule expression in human coronary artery endothelial cells: role of LOX-1

LOX-1, a receptor for oxidized low-density lipoprotein (ox-LDL), plays a critical role in endothelial dysfunction and atherosclerosis. LOX-1 activation also plays an important role in monocyte adhesion to endothelial cells. A number of studies show that 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) reduce total LDL cholesterol and exert a cardioprotective effect. We examined the modulation of LOX-1 expression and its function by two different statins, simvastatin and atorvastatin, in human coronary artery endothelial cells (HCAECs). We observed that ox-LDL (40 microg/ml) treatment up-regulated the expression of E- and P-selectins, VCAM-1 and ICAM-1 in HCAECs. Ox-LDL mediated these effects via LOX-1, since antisense to LOX-1 mRNA decreased LOX-1 expression and subsequent adhesion molecule expression. Pretreatment of HCAECs with simvastatin or atorvastatin (1 and 10 microM) reduced ox-LDL-induced expression of LOX-1 as well as adhesion molecules (all P < 0.05). A high concentration of statins (10 microM) was more potent than the low concentration (1 microM) (P < 0.05). Both statins reduced ox-LDL-mediated activation of the redox-sensitive nuclear factor-kappaB (NF-kappaB) but not AP-1. These observations indicate that LOX-1 activation plays an important role in ox-LDL-induced expression of adhesion molecules. Inhibition of expression of LOX-1 and adhesion molecules and activation of NF-kappaB may be another mechanism of beneficial effects of statins in vascular diseases.     

Telmisartan, an angiotensin II type 1 receptor blocker, inhibits advanced glycation end-product (AGE)-induced monocyte chemoattractant protein-1 expression in mesangial cells through downregulation of receptor for AGEs via peroxisome proliferator-activated receptor-gamma activation

Interaction between advanced glycation end-products (AGEs) and their receptor (RAGE) plays a central role in diabetic nephropathy pathogenesis. Pathophysiological crosstalk between the AGEs-RAGE system and angiotensin II (Ang II) is also involved in this disease. This study investigated the role of proliferator-activated receptor-gamma (PPAR-gamma)-modulating activity on inhibition of monocyte chemoattractant protein (MCP-1) expression. Telmisartan, an Ang II type 1 receptor blocker, downregulated RAGE mRNA and inhibited superoxide generation and MCP-1 gene expression in mesangial cells; these processes were blocked by GW9662, a PPAR-gamma inhibitor. Candesartan, an Ang II type 1 receptor blocker, did not suppress AGEs-induced superoxide generation. Telmisartan and the antioxidant, N-acetylcysteine, completely inhibited AGEs-induced MCP-1 overproduction by mesangial cells. These results suggest that telmisartan inhibits AGEs-signalling to MCP-1 expression in mesangial cells by downregulating RAGE gene expression and subsequent oxidative stress generation via PPAR-gamma activation. This study has demonstrated a unique benefit of telmisartan in that it may function as an anti-inflammatory agent against AGEs via PPAR-gamma activation and may play a protective role in diabetic nephropathy.     

Human monocyte colony-stimulating factor stimulates the gene expression of monocyte chemotactic protein-1 and increases the adhesion of monocytes to endothelial monolayers.

The stimulation of the human umbilical vein endothelial cell (HUVEC) with recombinant human monocyte-derived colony-stimulating factor (MCSF) increased the gene expression of monocyte chemotactic protein (MCP-1). Northern blot analysis indicated that 50 U/ml of MCSF is the optimal concentration for this effect. The elevation of MCP-1 mRNA started as early as 1 h after stimulation and was maintained for at least 8 h. An increased MCP-1 level in MCSF-treated HUVEC was also demonstrated at the protein level by immunocytochemical staining using a polyclonal MCP-1-specific antibody. HUVEC activated by 50 U/ml of MCSF for 5 h showed a stronger immunofluorescence staining than control cells. Micropipette separation of THP-1 monocytes from HUVEC showed that the activation of both THP-1 and endothelium by MCSF led to an increase in the separation force by more than three times (36.2 +/- 6.7 x 10(-4) vs. 9.6 +/- 3.6 x 10(-4) dyn). An increased adhesiveness was also observed after MCSF activation of peripheral blood monocytes and HUVEC (16.7 +/- 2.7 x 10(-4) vs. 5.2 +/- 0.9 x 10(-4) dyn). The increased adhesive force in both systems was blocked by the use of anti-MCP-1 (5.5 +/- 0.8 x 10(-4) and 6.8 +/- 1.1 x 10(-4) dyn). Similar results were obtained in experiments in which only HUVEC, but not monocytes, were activated by MCSF. This increased adhesion of untreated monocytes to MCSF-activated HUVEC was also blocked by the addition of anti-MCP-1. In contrast, experiments in which only THP-1 or peripheral blood monocytes, but not HUVEC, were treated with MCSF did not show a significant increase of adhesion between these cells. These results indicate that MCSF augments monocyte-endothelium interaction primarily by its action on the endothelial cell and that this function is probably mediated through an increased expression of MCP-1. The MCSF/MCP-1-dependent adhesive mechanism might be operative in the arterial wall in vivo to lead to the trapping of the infiltrated monocyte-macrophage in the subendothelial space during atherogenesis.     

Pioglitazone decreased CD40/CD40L expression on human umbilical vein endothelial cells induced by oxidized low-density lipoprotein

BACKGROUND: The CD40/CD40 ligand pathway mediated inflammatory processes are important in atherogenesis and the formation of the intraplaque lipid pool. We tested the hypothesis that pioglitazone could decrease lectin-like oxLDL receptor-1 (LOX-1) and CD40/CD40L expression on human umbilical vein endothelial cells (HUVECs) induced by oxidized low-density lipoprotein (oxLDL). METHODS: HUVECs were incubated with oxLDL for 24h with or without pretreated by pioglitazone. Expression of CD40/CD40L on the cell surface was detected by flow cytometry. CD40/CD40L and LOX-1 mRNA expression were evaluated by RT-PCR. The expression of LOX-1 on HUVECs was determined by cell immunohistochemistry. RESULTS: OxLDL increased the expression of CD40 and CD40L in a dose- and time-dependent manner. Pretreatment of HUVECs with pioglitazone (1 and 10 micromol/l) for 60 min decreased the expression of CD40 mRNA induced by oxLDL by 16% and 52%, respectively (both P<0.05). Pretreatment of HUVECs with pioglitazone (1 and 10 micromol/l) for 60 min decreased the expression of CD40L mRNA induced by oxLDL by 16% and 43% (both P<0.05). Also, pretreatment of HUVECs with pioglitazone (1 and 10 micromol/l) for 60 min also significantly decreased CD40 and CD40L expression on HUVECs induced by oxLDL in a concentration-dependent manner. Pretreatment of HUVECs with pioglitazone (1 and 10 micromol/l) decreased oxLDL induced upregulation mRNA of LOX-1 by 11% and 28%, respectively. Furthermore, through immunohistochemistry, we found that pioglitazone could decrease the LOX-1 expression on HUVECs induced by oxLDL. CONCLUSION: Pioglitazone inhibited the upregulation of LOX-1 on HUVECs elicited by oxLDL and subsequently decreased HUVECs CD40/CD40L expression induced by oxLDL. These observations provided novel insight into a potential novel anti-inflammatory pathway of thiazolidinediones.     

银杏黄酮苷元干预兔颈总动脉损伤后内膜增生及血凝素样氧化低密度脂蛋白受体1的表达

背景:银杏叶提取物中的黄酮苷元具有较强的抗氧化活性,课题组前期实验证实可抑制氧化低密度脂蛋白诱导内皮细胞表达血凝素样氧化低密度脂蛋白受体1.目的:进一步探讨银杏黄酮苷元对兔颈总动脉内皮损伤后内膜增生和血凝素样氧化低密度脂蛋白受体1表达的影响.方法:将雄性新西兰大白兔随机分为对照组、假手术组、模型组和治疗组.对照组予普通饲料,其余各组予高脂饮食,假手术组仅作颈外动脉结扎,模型组和治疗组均球囊损伤右颈总动脉,治疗组损伤后用银杏黄酮苷元灌胃.4周后检测各组血脂水平,观察各组右颈总动脉形态,用免疫组织化学法和RT-PCR检测血凝素样氧化低密度脂蛋白受体1蛋白和mRNA表达.结果与结论:模型组术后4周内膜增生明显,有粥样斑块形成,血凝素样氧化低密度脂蛋白受体1表达明显增加(P<0.05).治疗组银杏黄酮苷元灌胃4周后内膜增生较轻,内膜面积,血凝素样氧化低密度脂蛋白受体1阳性细胞数和其基因表达水平均低于模型组(P<0.05),但血脂与模型组比较无差异.提示银杏黄酮苷元可减轻新生内膜增生及动脉粥样硬化病粥样斑块的形成,这种作用可能与抑制兔颈总动脉内皮损伤后血凝素样氧化低密度脂蛋白受体1的表达有关.     

普罗布考对氧化修饰低密度脂蛋白诱导的人内皮细胞TOLL样受体4表达及单核内皮细胞黏附功能的影响

目的:探讨普罗布考对氧化修饰低密度脂蛋白(oxidizedlowdensitylipoprotein,ox-LDL)诱导的人脐静脉内皮细胞TLR4表达及其黏附功能的影响,为进一步研究普罗布考抗动脉粥样硬化的机制,发现抗动脉粥样硬化形成的新靶点提供理论依据。方法:应用RT-PCR,WesternBlot技术检测了普罗布考对ox-LDL诱导的细胞TOLL样受体4(toll-likereceptor4,TLR4)表达的影响,同时用孟加拉玫瑰红活细胞染色法观察不同浓度普罗布考对ox-LDL诱导的人脐静脉内皮细胞(humanumbilicalveinendothelialcells,HUVECs)对单核细胞黏附的影响,并利用相关性检验分析两者间的相关性。结果:ox-LDL能明显上调HUVECsTLR4的表达,并呈一定的剂量依赖性(t=3.04～12.52,P<0.01)。普罗布考呈浓度依赖方式抑制ox-LDL诱导HUVECsTLR4表达,同时也能明显抑制ox-LDL诱导的HUVECs对单核细胞黏附(t=5.30,19.23,P<0.01)。相关性分析显示两者间有明显的正相关性(r=0.996,P<0.01)。结论:普罗布考除具有调脂作用外,尚可通过抑制ox-LDL诱导的内皮细胞TLR4受体的表达和抑制单核细胞与内皮细胞黏附聚集,发挥抗炎作用;TLR4可能成为防治动脉粥样硬化的新靶点。     

Modulation of ADP-induced platelet activation by aspirin and pravastatin: role of lectin-like oxidized low-density lipoprotein receptor-1, nitric oxide, oxidative stress, and inside-out integrin signaling

Lectin-like oxidized low-density lipoprotein (LDL) receptor-1 (LOX-1), a receptor for oxidized-LDL, is up-regulated in activated endothelial cells, and it plays a role in atherothrombosis. However, its role in platelet aggregation is unclear. Both aspirin and HMG CoA reductase inhibitors (statins) reduce LOX-1 expression in endothelial cells. In this study, we investigated the effect of aspirin and pravastatin on LOX-1 expression on plate-lets. After ADP stimulation, mean fluorescence intensity of LOX-1 expression on platelets increased 1.5- to 2.0-fold. Blocking LOX-1 inhibited ADP-induced platelet aggregation in a concentration- and time-dependent manner. We also established that LOX-1 is important for ADP-stimulated inside-out activation of platelet alpha(IIb)beta(3) and alpha(2)beta(1) integrins (fibrinogen receptors). The specificity of this interaction was determined by arginine-glycine-aspartate-peptide inhibition. Furthermore, we found that LOX-1 inhibition of integrin activation is mediated by inhibition of protein kinase C activity. In other experiments, treatment with aspirin (1-10 mM) and pravastatin (1-5 microM) reduced platelet LOX-1 expression, with a synergistic effect of the combination of aspirin and pravastatin. Aspirin and pravastatin both reduced reactive oxygen species (ROS) released by activated platelets measured as malonyldialdehyde (MDA) release and nitrate/nitrite ratio. Aspirin and pravastatin also enhanced nitric oxide (NO) release measured as nitrite/nitrite + nitrate (NOx) ratio in platelet supernates. Small concentrations of aspirin and pravastatin had a synergistic effect on the inhibition of MDA release and enhancement of nitrite/NOx. Thus, LOX-1 is important for ADP-mediated platelet integrin activation, possibly through protein kinase C activation. Furthermore, aspirin and pravastatin inhibit LOX-1 expression on platelets in part by favorably affecting ROS and NO release from activated platelets.     

黄芪多糖对脂多糖诱导人THP21单核细胞MCP-1与IL-6表达的影响

目的通过研究黄芪多糖（astragalus polysaccharide,APS）对脂多糖（lipopolysaccharide,LPS）诱导人单核细胞株TI-IP21细胞趋化蛋白1（monocyte chemoattractant protein1,MCP-1）及白介素6（imerleukin．6,IL-6）的表达影响,探讨炎症状态下APS对单核细胞炎症因子表达的调控。方法体外培养人单核细胞THP21,以脂多糖刺激建立炎症细胞模型。以MTT法检测黄芪多糖对细胞的毒性,以荧光定量RT-PCR法检测黄芪多糖对THP21细胞MCP-1与IL-6mRNA水平表达的影响,以ELISA法检测黄芪多糖对THP21细胞MCP-1与IL-6细胞外分泌的影响。结果黄芪多糖在50、100、200μg／mL浓度下对THP21细胞均无明显毒性,100μg／mL的黄芪多糖明显抑制LPS诱导THP21细胞MCP-1与IL-6mRNA表达的增加及培养上清中MCP—1与IL-6的增加。结论黄芪多糖抑制脂多糖诱导的人单核细胞株THP21中MCP-1与IL-6的表达及分泌。     

恒磁场对血管紧张素Ⅱ作用下人血管平滑肌细胞分泌与表达单核细胞趋化蛋白-1的影响

目的:观察不同强度恒磁场对血管紧张素Ⅱ(angiotensinⅡ,AngⅡ)作用下人血管平滑肌细胞(vascularsmoothmusclecells,VSMC)分泌与表达单核细胞趋化蛋白-1(monocytechemoattractantprotein-1,MCP-1)的影响。方法:采用体外培养第4～6代的人脐动脉VSMC,实验分为6组,即对照组、AngⅡ(1×10-6mol/L)组及AngⅡ+不同磁感应强度(1,5,10,50Gs)的恒磁场组。各组细胞于培养及恒磁场作用24h后收集标本,用酶联免疫吸附试验(enzyme-linkedimmunoadsordentassay,ELISA)检测MCP-1的分泌量,免疫细胞化学检测MCP-1的蛋白表达。结果:AngⅡ1×10-6mol/L刺激VSMC24h,MCP-1的分泌量显著增高(P<0.05);而1,5,10,50Gs恒磁场组细胞MCP-1的分泌量显著低于AngⅡ组(F=752.89,P<0.05)。AngⅡ1×10-6mol/L与VSMC孵育24h后,MCP-1的表达显著增加(P<0.05和对照组);而1,5,10,50Gs恒磁场组MCP-1的表达显著低于AngⅡ组(F=238.26,P<0.05)。结论:1～50Gs的恒磁场可拮抗AngⅡ的作用,抑制VSMC分泌与表达MCP-1。     

三七总皂苷对氧化型低密度脂蛋白诱导的人脐静脉内皮细胞血管细胞黏附分子1表达的影响水

背景:氧化低密度脂蛋白能诱导血管内皮细胞活化和黏附分子表达,在动脉粥样硬化形成早期起重要作用.三七总皂苷在心血管系统方面具有保护血管内皮细胞、显著改善动脉粥样硬化病变程度的药理作用.目的:验证三七总皂苷对氧化型低密度脂蛋白损伤内皮细胞后血管细胞黏附分子1的表达及与人单核细胞黏附的影响.设计、时间及地点:体外实验,分组对照,于2007-03/2008-05在北京中医药大学东直门医院中医内科学教育部重点实验室完成.材料:原代人脐静脉内皮细胞为美国Cascade Biologics公司产品;三七总皂苷(血塞通冻干粉针)为黑龙江珍宝岛制药有限公司产品,成分为三七总皂苷,批号:20040207.方法:以培养原代人脐静脉内皮细胞作为靶细胞.用氧化型低密度脂蛋白造成人脐静脉内皮细胞损伤模型.将培养的人脐静脉内皮细胞分为5组:氧化型低密度脂蛋白组(100 mg/L)、氧化型低密度脂蛋白+三七总皂苷组(终浓度分别为200,100,50 mg/L)、正常对照组.主要观察指标:光镜下观察细胞形态变化,四甲基偶氮唑盐法检测细胞活性;采用蛋白定量法检测人脐静脉内皮细胞与单核细胞的黏附率;用流式细胞仪测定人脐静脉内皮细胞的血管细胞黏附分子1的蛋白表达.结果:氧化型低密度脂蛋白作用人脐静脉内皮细胞后12,24 h时,人脐静脉内皮细胞损伤明显,细胞活性显著降低,人单核细胞与人脐静脉内皮细胞的黏附率显著升高,人脐静脉内皮细胞的血管细胞黏附分了1的蛋白表达水平也均明显升高,均明显高于正常对照组(P<0.05,P<0.01),而三七总皂苷能使氧化型低密度脂蛋白损伤的人脐静脉内皮细胞形态趋于正常,活性增强,并明显降低人单核细胞与人脐静脉内皮细胞的黏附率,以及显著降低血管细胞黏附分子1的蛋白的表达水平,与氧化型低密度脂蛋白组相比均有显著性差异(P<0.05,P<0.01),这种作用随着剂量的增加而增强.结论:三七总皂苷能通过下调血管细胞黏附分子1的表达抑制单核-血管内皮细胞黏附,从而发挥对血管内皮细胞的保护作用,这可能是其治疗动脉硬化闭塞症的机制之一.     

Role of vascular endothelial growth factor and monocyte chemoattractant protein-1 in the development of endothelial dysfunction in types 1 and 2 diabetes mellitus complicated by diabetic retinopathy

The paper presents the results of a study of the serum levels of monocyte chemoattractant protein-1 (MCP-1) and vascular endothelial growth factor (VEGF) in 120 patients with types 1 and 2 diabetes mellitus complicated by diabetic retinopathy. All the patients with diabetes have been ascertained to show a rise in the levels of MCP-1 and VEGF. Calculation of VEGF/MCP-1 ratio is proposed to evaluate vascular bed lesion in diabetic patients.