Role of lipoprotein peroxidation in the pathogenesis of atherosclerosis.

Oxidative modification of low-density lipoprotein (LDL) has been shown to alter its properties in a way that tends to increase its atherogenicity. Cultured arterial endothelial cells and smooth muscle cells can promote LDL oxidation in vitro. Several recent studies have provided evidence for the presence of oxidized LDL in atherosclerotic lesions. Furthermore, treatment of atherosclerosis-prone rabbits with an antioxidant was found to slow the progression of aortic lesions. Additional experimental work is required to determine if LDL oxidation is indeed an important causal step in atherogenesis in humans, but the preliminary data are encouraging and offer the potential for a new approach to the prevention and therapy of atherosclerosis.     

血脂康对高脂血症患者低密度脂蛋白颗粒和氧化型低密度脂蛋白的影响

目的探讨血脂康对高脂血症患者低密度脂蛋白(LDL)颗粒和氧化型低密度脂蛋白(ox-LDL)的影响。方法连续入选未服用降脂药物治疗的受试人群40例(其中高脂血症患者20例,健康受试者20例),分为血脂康组(n=20例)和对照组(n=20例)。Lipoprint脂蛋白分类检测仪对LDL颗粒进行分类。治疗8周后比较两组治疗前后LDL颗粒和ox-LDL的变化。结果与治疗前相比,治疗后血脂康组的血清低密度脂蛋白胆固醇(LDLC)、总胆固醇(TC)、甘油三酯(TG)和载脂蛋白B的浓度显著降低(P0. 05),小颗粒LDLC的浓度和小颗粒LDL的百分比均降低(P0. 05)。经血脂康治疗后,ox-LDL的浓度显著降低(P0. 05)。结论血脂康治疗8周可显著改善高脂血症患者的血脂谱,并降低致动脉粥样硬化性小颗粒LDLC浓度和百分比,同时减少氧化应激反应。     

植物凝集素样氧化型低密度脂蛋白受体-1与动脉粥样硬化

植物凝集素样氧化型低密度脂蛋白受体-1（lectin-likeoxidizedlow-densitylipoprotein receptor-1, LOX-1）是氧化型低密度脂蛋白（oxidized low-density lipoproteins, oxLDL）的主要受体之一。近年来的研究表明,LOX-1不仅可以结合、中和以及降解oxLDL,还能与一些非氧化脂蛋白和凋亡的血细胞结合,通过激活血小板、诱导炎症反应、促进血管平滑肌细胞增殖和迁移等多种途径参与动脉粥样硬化进程。文章从LOX-1的结构、功能及其与脂质代谢、动脉粥样硬化发病机制间的关系等方面,对相关研究进展进行了综述。     

氧化型低密度脂蛋白对可诱导共刺激分子在人外周血T细胞表达的影响

目的:探讨可诱导共刺激分子(ICOS)在人外周血T细胞的表达及氧化低密度脂蛋白(ox-LDL)的干预作用。方法:以人外周血T细胞为实验模型,通过间接免疫荧光法、RT-PCR和Western blot等方法,观察ox-LDL对人外周血T细胞表达ICOS的影响。结果:①ICOS表达于人外周血T细胞膜,荧光信号呈点状散在分布于细胞表面。RT-PCR检测显示,ICOS mRNA的扩增片段位于相当于Marker 368 bp的位置。Western blot检测显示,ICOS的分子量约为55 kD。②ox-LDL刺激组ICOS的吸光度(A)值高于空白对照组,提示ox-LDL能够明显增加人外周血T细胞中的ICOS mRNA和其蛋白的表达(P0.05)。结论:ICOS表达于人外周血T细胞表面,ox-LDL能够上调ICOSmRNA和其蛋白的表达,这可能是动脉粥样硬化的免疫学发病机制之一。     

氧化型低密度脂蛋白诱导肝窦内皮细胞植物血凝素样氧化型低密度脂蛋白受体1的表达

目的：探讨植物血凝素样氧化型低密度脂蛋白（ox-LDL）受体1（LOX-1）在肝窦内皮细胞（HSECs）中的表达和ox-LDL对其表达的调控作用。方法使用实时定量聚合酶链反应（RT-PCR）和Western blotting法从基因和蛋白水平检测未经处理HSECs 中LOX-1的表达。应用不同浓度ox-LDL（0、20、40、60、80和100 mg/L）对HSECs作用24 h并应用80 mg/L ox-LDL对HSECs作用不同时间（0、12、24和48 h）,作用后实时定量PCR检测HSECs内LOX-1 mRNA的表达水平,Western blotting法检测细胞内LOX-1蛋白表达。给予80 mg/L ox-LDL干预组多聚肌苷酸250 mg/L作用24 h后,测定LOX-1 mRNA和蛋白的表达。采用单因素方差分析及t检验进行数据分析。结果 LOX-1 mRNA和蛋白在HSECs中均有表达。20～80 mg/L ox-LDL组HSECs中LOX-1 mRNA、蛋白表达水平随ox-LDL剂量增加而升高,与剂量有明显相关性（F＝38.7、3.43,均P＜0.05）。与80 mg/L ox-LDL组相比,100 mg/L ox-LDL 组 LOX-1 mRNA、蛋白表达下降,差异有统计学意义（ t ＝23.75、18.26, P ＜0.05）。80 mg/L ox-LDL对HSECs作用时间在0～24 h时,随着时间延长,LOX-1 mRNA、蛋白表达递增,与ox-LDL作用时间有明显相关性（F＝2.36、0.33,均P＜0.05）。与作用24 h相比,作用48 h组HSECs中LOX-1 mRNA、蛋白表达下降（t＝69.21、36.27,均P＜0.05）。与80 mg/L ox-LDL组相比,多聚肌苷酸组中LOX-1 mRNA和蛋白表达降低,两组差异均有统计学意义（ t＝54.93、28.19,均P＜0.05）。结论LOX-1存在于HSECs。在一定浓度和时间范围内,ox-LDL对HSECs LOX-1的调控作用具有时间和浓度依赖性,而多聚肌苷酸可部分抑制这种效应。     

不同类型心绞痛患者低密度脂蛋白及氧化型低密度脂蛋白的比较研究

目的探讨血浆低密度脂蛋白胆固醇（LDL-C）和氧化型低密度脂蛋白（ox-LDL）与冠状动脉粥样硬化病变严重程度的关系。方法病例选择：冠状动脉痉挛组（CAS,n=31）,临床上具有胸痛表现、冠状动脉造影无显著狭窄并经过乙酰胆碱试验确诊的患者,根据痉挛血管形态分为节段性痉挛组和弥漫性痉挛组;稳定性心绞痛组（SAP,n=35）,为稳定的劳力型心绞痛患者,根据冠状动脉造影结果分为单支病变组和多支病变组;对照组（n=24）,为健康体检患者。各组于清晨空腹采取静脉血,采用全自动生化分析仪测定血浆LDL-C,用ELISA法检测血浆ox-LDL含量,分组比较其LDL．C及ox-LDL水平。结果血浆LDL-C水平SAP亚组[单支病变组（2．6±0．9）mmol／L,多支病变组（2．8±0．9）mmol／L]和CAS亚组[弥漫性痉挛组（3．2±0．5）mmol／L,节段性痉挛组（2．9±0．8）mmol／L]间差异无统计学意义,但均高于对照组[（2．2±0．5）mmol／L,P〈0．05];SAP组血浆ox-LDL含量[（575±219）μg/L]高于对照组[（218±35）μg/L,P〈0．01]和CAS组[（299±117）μg/L,P〈0．01],CAS组与对照组比较,差异无统计学意义（P〉0．05）;弥漫性痉挛组[（225±63）μg／L]、节段性痉挛组[（328±123）μg／L]、单支血管病组[（462±72）μg／L]、多支血管病变组[（672±92）μg／L]的血浆ox—LDL浓度逐步上升,各组间差异有统计学意义（P〈0．05）,与冠状动脉硬化程度呈一致趋势,而血浆LDL水平组间差异无统计学意义。结论血浆ox-LDL比LDL—C更能准确地预测冠状动脉粥样硬化的严重程度,调脂治疗应该更为重视降低ox-LDL,而不应单纯控制LDL水平。     

Gemfibrozil decreases autoantibodies against oxidized low-density lipoprotein in men with combined hyperlipidaemia

Hoogerbrugge N, Kerkhofs LGN, Jansen H (University Hospital Dijkzigt, Rotterdam, The Netherlands). Gemfibrozil decreases autoantibodies against oxidized low-density lipoprotein in men with combined hyperlipidaemia. J Intern Med 1998; 243 : 355–59.

Objectives

Gemfibrozil is the most widely used fibric acid for the management of combined hyperlipidaemia. It has beneficial effects in the prevention of coronary heart disease (CHD). The mechanisms by which it exerts this effect are not completely resolved. We studied whether gemfibrozil affects low-density lipoprotein (LDL) size and LDL oxidation parameters in males with a moderate combined hyperlipidaemia at high risk for progressive atherosclerosis.

Design

Open treatment with 2 × 600 mg gemfibrozil daily for 12 weeks.

Setting

Outpatient lipid clinic of a tertiary referral centre.

Subjects

Twenty-three patients with combined hyperlipidaemia and CHD or a positive family history for both CHD and hyperlipidaemia.

Main outcome measures

Effects on triglyceride (TG), autoantibodies to oxidized LDL, LDL pattern and resistance to oxidative modification.

Results

During treatment with gemfibrozil, plasma TG concentration decreased from 2.83 ± 0.85 to 2.02 ± 0.89 mmol L^?1 (P < 0.001). All but one patient were shown to have LDL pattern B. The LDL pattern did not change upon treatment with gemfibrozil. The resistance to oxidation, reflected in the lagtime during in-vitro oxidation slightly decreased from 105 ± 22 to 99 ± 18 min (P= 0.01). The concentration of autoantibodies against oxidized LDL indicates the rate of LDL oxidation in vivo. This concentration significantly decreased from 14.2 ± 9.9 to 13.1 ± 9.2 mg L^?1 (P < 0.01).

Conclusions

The beneficial effect of gemfibrozil in reducing CHD may at least in part depend on a decrease of the rate of LDL oxidation in vivo.

     

Melatonin protects against oxidized low-density lipoprotein-induced inhibition of nitric oxide production in human umbilical artery

We evaluated the antioxidative effect of melatonin on the oxidized low-density lipoprotein (LDL)-induced impairment of nitric oxide (NO) production in human umbilical artery, which may be the prime cause of endothelial dysfunction in pre-eclampsia. Umbilical artery sections with intact endothelium were obtained from healthy pregnant women who were delivered between 37 and 40 wk of gestation. The production of NO in the umbilical arteries was stimulated by adding L-arginine followed by incubation for 60 min. NO concentrations were estimated by measuring nitrite ions (NO(2) using high-performance liquid chromatography. LDL was oxidized by incubation with 5 microM CuSO(4) at 37 degrees C for 4 hr, followed by dialysis at 4 degrees C for 24 hr. Prior to the addition of L-arginine, the segments were treated with native or oxidized LDL (0, 50, 100, 200, 400 microg/mL), or were pre-treated with either mannitol (50 mM) or melatonin (20, 100, 500 microM) before adding oxidized LDL. Changes in L-arginine-induced NO(2)(-) production were expressed as a percentage of NO(2)(-) production at the end of pre-incubation. Treatment with oxidized LDL significantly reduced L-arginine-induced NO(2)(-) production (P<0.05), while NO(2)(-) production did not change by incubation with native LDL. Pre-treatment with melatonin significantly increased NO(2)(-) production that had been decreased by oxidized LDL (P<0.05). Similarly, pre-treatment with mannitol reversed the oxidized LDL-induced reduction in NO(2)(-) production (P<0.05). These results indicate that melatonin protects against oxidized LDL-induced inhibition of NO production in the endothelium of human umbilical arteries, most likely through its ability to scavenge hydroxyl radicals.     

Melatonin inhibits vasospastic action of oxidized low-density lipoprotein in human umbilical arteries

We evaluated the antioxidant property of melatonin in countering the vasospastic effect of oxidized low-density lipoprotein (ox-LDL), which has been reported to be the most important risk factor for atherosclerosis and also may be linked to preeclampsia. Helical sections of umbilical arteries were obtained from human placentas at elective cesarean deliveries between 37 and 39 weeks of gestation. Changes in maximal tension induced by potassium chloride were measured in arterial sections with intact endothelium. ox-LDL (200 or 300 microg protein/mL) increased vascular tension by 15.6 +/- 2.3 or 31.9 +/- 4.0%, respectively. In contrast, native LDL only slightly increased vascular tension (2.7 +/- 1.0% for 200 microg protein/mL and 6.0 +/- 1.7% for 300 microg protein/mL). Pretreatment with L-N(G)-monomethyl-arginine (2 x 10(-4) M) significantly reduced the vasospastic effect of ox-LDL, as did pretreatment with mannitol (30 mM). Melatonin (10 microM) significantly reduced the vasospastic effect of ox-LDL. These findings suggest that ox-LDL potentiates vascular tension in the human umbilical artery, possibly by suppressing endothelial synthesis of nitric oxide. Melatonin significantly suppressed the vasospastic effect of ox-LDL, probably because it scavenges hydroxyl radical arising from ox-LDL.     

炎症反应在易损斑块中的作用及其机制研究进展

炎症反应在易损斑块的形成和进展中发挥重要作用,同时调控血管局部病变及全身炎症状态。一些促炎性细胞和炎症因子使斑块纤维帽的抗张强度降低,坏死脂质内核增大,血管机械稳定性丧失和斑块破裂;另一方面,炎症反应的激活和代谢紊乱也会引起内皮功能不全、斑块侵蚀进而导致血栓形成。该过程主要由巨噬细胞和淋巴细胞等多种炎症细胞参与,并受到多种因素调控,包括胆固醇结晶和脂质递质、血管剪切力、血管新生及斑块内出血等。此外,机体还存在一些抑炎性分子,能避免易损斑块向破裂或侵蚀进展。促炎和抗炎反应的平衡影响急性冠状动脉事件的发生。因此,以炎症反应为靶点,筛选出有易损斑块的患者并干预,或可减少急性冠状动脉事件的发生和改善预后,具有重要临床价值。     

氧化型低密度脂蛋白和同型半胱氨酸与冠状动脉病变的相关性研究

目的 通过研究冠状动脉粥样硬化性心脏病（冠心病）患者血浆氧化型低密度脂蛋白（oxidized low-densitylipoprotein cholesterol,OX-LDL-C）和同型半胱氨酸（homoeysteine,HCY）浓度与Gensini评分的相关性,探讨其对冠状动脉病变严重程度的预测价值.方法 选择疑似冠心病患者86例,据冠状动脉造影结果分为冠心病组（67例）及对照组（19例）,冠心病组根据Gensini评分分为轻度亚组（23例）、中度亚组（22例）和重度亚组（22例）.分析各组血浆OX-LDL-C和HCY浓度与Gensini评分的相关性.结果 （1）冠心病组与对照组血浆OX-LDL-C、HCY浓度比较,冠心病组较高,差异有统计学意义（P＜0.05）.（2） Gensini评分三个亚组间血浆OX-LDL-C和HCY浓度比较,差异有统计学意义（P＜0.05）;随着冠状动脉狭窄程度加重,血浆OX-LDL-C、HCY浓度有增高趋势,差异有统计学意义（P＜0.05）.（3） Gensini评分与血浆OX-LDL-C（r=0.805,P＜0.01）、HCY （r=0.700,P＜0.01）浓度呈正相关,且OX-LDL-C与Gensini评分相关性较HCY高;血浆OX-LDL-C与HCY浓度呈正相关（r=0.698,P＜0.01）.结论 血浆OX-LDL-C和HCY浓度与Gensini评分有关,血浆OX-LDL-C与HCY具有相关一致性,联合检测血浆OX-LDL-C和HCY浓度可更好地了解病情、指导治疗及判断预后.     

Oxidized low-density lipoprotein in plasma is a prognostic marker of subclinical atherosclerosis development in clinically healthy men

OBJECTIVE: To investigate the association between plasma oxidized low-density lipoprotein (OxLDL) and the progress of clinically silent atherosclerosis, as measured by ultrasound in the carotid arteries. DESIGN: Prospective, observational study with more than 3 years of follow-up. SETTING: One-centre study at university hospital. MATERIAL AND METHODS: The subjects (n = 326) were obtained by stratified sampling from a population sample of men who were 58 years old at baseline. Carotid artery intima-media thickness (IMT) was measured bilaterally by high-resolution B-mode ultrasound at baseline and after follow-up. Plasma OxLDL cholesterol concentrations and conventional cardiovascular risk factors were measured at study entry. Automated measurements of IMT were performed. Plaque occurrence and size were assessed (plaque status). Plasma OxLDL at entry was measured by a specific monoclonal antibody, mAb-4E6. RESULTS: OxLDL at entry, but not LDL cholesterol, was associated with the number and size of plaques at follow-up (P = 0.008), also after adjustment for plaque status at entry (P = 0.033). The plasma OxLDL concentration at entry was associated with change in carotid artery IMT (r = 0.17; P = 0.002) and in a stepwise multiple regression analysis this association remained after adjustment for other cardiovascular risk factors (P = 0.005). CONCLUSIONS: These results provide new information, supporting the concept that circulating OxLDL was associated with the silent phase of atherosclerosis progression in clinically healthy men independently of conventional risk factors.     

Matrix metalloproteinases and coronary artery diseases

Matrix metalloproteinases (MMPs) play an important role in cardiovascular remodeling by degrading the extracellular matrix. Enhanced MMP expression has been detected in the atherosclerotic plaque, and activation of MMPs appears to be involved in the vulnerability of the plaque. Circulating MMP levels are elevated in patients with acute myocardial infarction and unstable angina. Increased MMP expression is also observed after coronary angioplasty, which is related to late loss index after the procedure. These observations suggest that MMP expression may be not only related to instability of the plaque, but also to the formation of restenotic lesions. The development of therapeutic drugs targeted specifically against MMPs may be useful in the prevention of atherosclerotic lesion development, plaque rupture, and restenosis.     

Negligible synergistic effect of β2-glycoprotein I on the reactivity of antioxidized low-density lipoprotein antibody to oxidized low-density lipoprotein

We conducted this study to investigate whether antioxidized low-density lipoprotein (a-oxLDL) is an antibody to cryptic and/or neo-antigen on β₂-glycoprotein I (GPI), which is introduced by binding to anionic phospholipid, similar to that of GPI-dependent anticardiolipin antibody (aCL) employing a-oxLDL ELISA. We found that no significant optical density differences existed among systemic lupus erythematosus patients, including cases with aCL and/or lupus anticoagulant positivity, before and after the addition of GPI. Our results suggest that a-oxLDL is not an antibody to denatured GPI, but rather to oxLDL. © 1996 Wiley-Liss, Inc.     

阿托伐他汀对氧化低密度脂蛋白诱导兔脂肪细胞表达凝血和纤溶因子的调节

目的探讨阿托伐他汀对氧化低密度脂蛋白(OX-LDL)诱导兔脂肪细胞分泌组织因子(TF)和纤溶酶原激活物抑制剂1(PAI-1)的影响。方法取正常兔脂肪组织分离培养脂肪细胞,实验设对照组、ox-LDL干预组、阿托伐他汀干预组及联合干预组,除对照组外,其余3组分别以不同终浓度的ox-LDL和阿托伐他汀进行单独或联合干预,孵育24h。用酶联免疫吸附法检测TF和PAI-1蛋白含量。逆转录聚合酶链反应测定脂肪细胞TF和PAI-1 mRNA表达。结果ox-LDL使脂肪细胞分泌TF和PAI-1显著增加,TF和PAI-1 mRNA表达升高,并呈剂量依赖性。阿托伐他汀呈浓度依赖性地抑制兔脂肪细胞TF下和PAI-1 mRNA表达及蛋白产生。联合干预组与ox-LDL组比较,阿托伐他汀使TF和PAI-1 mRNA表达及蛋白分泌降低,但仍高于对照组。结论阿托伐他汀对ox-LDL诱导的兔脂肪细胞表达凝血和纤溶因子异常具有显著的调节作用。     

Measurement of plasma oxidized low-density lipoprotein and its clinical implications

Oxidized low-density lipoprotein (OxLDL) has been shown to exist in human circulating plasma. Several groups including ours have developed methods for immunologically measuring OxLDL, which have been applied to several clinical, both cross-sectional and prospective, studies. These data clearly show that OxLDL levels correlate well with the severity of cardiovascular diseases. In particular, recent observations suggest that plasma OxLDL levels could be a useful marker for predicting future cardiovascular events; however, substantial differences exist among the different methods of OxLDL measurement. To evaluate the clinical data on circulating OxLDL, a proper understanding of the similarity, differences, and limitation of the methods is needed. This paper summarizes the characteristics of the methods used and recent clinical findings.