Circulating autoantibodies to oxidized LDL correlate with arterial accumulation and depletion of oxidized LDL in LDL receptor-deficient mice

Autoantibodies to oxidized low density lipoprotein (OxLDL) are elevated in some human populations with increased risk of atherosclerosis. To determine whether autoantibody levels to epitopes of OxLDL reflect the extent of aortic atherosclerosis and the content of OxLDL, we measured IgG and IgM autoantibody titers to malondialdehyde (MDA)-LDL and copper-oxidized LDL (Cu-OxLDL) in 43 LDL receptor-deficient mice consuming atherogenic and regression diets. Antibody titers were correlated to percent atherosclerotic surface area, aortic weight, and aortic OxLDL content, measured as the in vivo uptake of (125)I-MDA2, a monoclonal antibody to MDA-LDL. All mice were fed an atherogenic diet for 6 months, and 1 group was euthanized. The other 3 groups were fed an atherogenic diet (fat/CHOL group), normal mouse chow (chow group), or mouse chow supplemented with vitamins E and C (chow+VIT group) for an additional 6 months. After dietary intervention, compared with their own baseline, autoantibody titers to MDA-LDL and Cu-OxLDL increased significantly in the fat/CHOL group, whereas they did not change or decreased significantly in the chow and chow+VIT groups. Aortic weight and surface area showed significant progression in the fat/CHOL group, mild progression in the chow group, and no progression in the chow+VIT group (P<0.001), whereas OxLDL content actually decreased in the latter 2 groups (P<0.001). Significant correlations were seen with MDA-LDL autoantibody titers and OxLDL content (IgM, R=0.64 and P=0.0009; IgG, R=0.52 and P=0.009), as well as with percent surface area and aortic weight. These data support the hypothesis that autoantibody titers to OxLDL reflect changes in OxLDL content in atherosclerotic lesions of LDL receptor-deficient mice. Whether autoantibody titers to OxLDL will provide similar valuable insights into the extent of human atherosclerosis, particularly anatomic measurements of plaque burden and OxLDL content, remains to be determined.     

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。     

Increased plasma 8-isoprostane levels in hypertensive subjects: the Tsurugaya Project.

To examine the relationship between 8-isoprostane and blood pressure, we measured plasma 8-isoprostane concentration and home blood pressure levels in an elderly Japanese population. Our study population comprised 569 subjects aged 70 years and over who were not receiving antihypertensive medication. On the basis of their blood pressure values, the participants were classified into three groups: normotensive (home blood pressure <135/85 mmHg), hypertensive (home blood pressure 135/85-160/90 mmHg), and severely hypertensive (home blood pressure > or =160/90 mmHg). The mean plasma 8-isoprostane level in the severely hypertensive group (21.1+/-5.2 pg/ml) was significantly higher than that in the normotensive (20.2+/-4.9 pg/ml) or hypertensive (19.7+/-5.1 pg/ml) group, and this result was unchanged when we adjusted for possible confounding factors such as age, sex, use of vitamin A, C or E supplements, smoking status, drinking status, body mass index, use of non-steroidal anti-inflammatory drugs, history of diabetes, hypercholesterolemia, home heart rate and serum creatinine level. Thus, the level of plasma 8-isoprostane appears to be elevated in older subjects with severe hypertension.     

非诺贝特对高胆固醇血症兔脂肪细胞摄取及降解氧化型低密度脂蛋白的影响

目的　观察兔脂肪细胞通过CD36摄取及降解氧化型低密度脂蛋白(OxLDL)的作用和非诺贝特对高胆固醇血症兔脂肪细胞OxLDL代谢的影响。方法　10只新西兰白兔给予高胆固醇饲料饲养8周后分为: (1)高胆固醇血症组:继续饲以高胆固醇饲料4周; (2)非诺贝特治疗组:在饲以高胆固醇饲料的基础上给予(30mg·kg-1·d-1 )非诺贝特4周。另选饲以普通饲料12周兔5只作为对照组。实验结束后,取皮下脂肪组织行脂肪细胞培养,放射配基法测定脂肪细胞对OxLDL的摄取及降解,RT PCR测定脂肪细胞CD36mRNA的表达。结果　喂饲胆固醇组血清总胆固醇、低密度脂蛋白胆固醇水平明显高于对照组(均P<0. 01),非诺贝特干预4周未对血脂产生影响,但能降低体重( -19%,P<0. 05 )。RT PCR示CD36在脂肪细胞分化过程中被诱导表达。放射配基实验发现兔脂肪细胞呈浓度依赖饱和型的摄取及降解OxLDL,细胞最大结合为2 065ng/mg细胞蛋白,解离常数(Kd)为4. 2mg/L;抗CD36抗体明显抑制脂肪细胞摄取(56% )及降解(54% )OxLDL;当125I OxLDL浓度为75mg/L时,对照组,高胆固醇组,非诺贝特治疗组脂肪细胞摄取125I OxLDL分别为3. 5, 2. 1, 2. 7μg/mg细胞蛋白, 降解125I OxLDL分别为2. 2, 1. 2,1. 7μg/mg细胞蛋白, 3组间差异有统计学意义(P<0. 05)。结论　CD36介导脂     

Associations of LDL size with in vitro oxidizability and plasma levels of in vivo oxidized LDL in Type 2 diabetic patients.

AIMS: Oxidative modification of low-density lipoprotein (LDL) is believed to be a key step in the genesis of atherosclerotic lesions. The presence of small, dense LDL is associated with accelerated atherosclerosis and is common in diabetic patients. The aim of this study was to investigate the relationship of in vitro LDL oxidizability and circulating in vivo oxidized LDL with LDL particle size in Type 2 diabetic patients and healthy control subjects. SUBJECTS AND METHODS: The study group consisted of 58 elderly well controlled Type 2 diabetic patients and 58 control subjects with normal glucose metabolism. LDL particle size was measured by high-performance gel-filtration chromatography. In vitro oxidizability of LDL was measured by monitoring conjugated diene formation and plasma levels of circulating oxidized LDL were determined by ELISA. RESULTS: In vitro susceptibility of LDL to oxidation was not related to plasma levels of in vivo oxidized LDL, nor to LDL particle size. In the diabetic patients, but not in the control group, an inverse relation between LDL size and in vivo oxidized LDL was observed (r=-0.35, P=0.007). This relation was strengthened after controlling for LDL-cholesterol concentration (r=-0.52, P<0.001). CONCLUSIONS: In agreement with the view that small, dense LDL accelerates atherosclerosis, an inverse relationship was observed between LDL size and circulating in vivo oxidized LDL in Type 2 diabetic patients. Our results also suggest that in vitro susceptibility to oxidation is not a suitable surrogate measure for in vivo LDL oxidation.     

Effect of insulin treatment on plasma oxidized LDL/LDL-cholesterol ratio in type 2 diabetic patients

OBJECTIVE: In type 2 diabetes mellitus, oxidized LDL/LDL-Cholesterol ratio, an accurate estimation of in vivo LDL oxidation, has been reported elevated and associated with macrovascular disease. Because insulin therapy induces significant modification of lipid metabolism, in type 2 diabetes, we evaluated the effect of insulin treatment on oxidized LDL/LDL-C ratio in type 2 diabetic patients and analyzed the results in comparison with the modifications induced by insulin on glycaemia, plasma lipids and LDL receptors. RESEARCH DESIGN AND METHODS: Plasma oxidized LDL concentrations were measured by sandwich ELISA in 21 type 2 diabetic patients before and 3 months after the introduction of insulin therapy, and in 27 age-matched controls. RESULTS: Type 2 diabetic patients had, compared to controls, significantly increased oxidized LDL/LDL-C ratio (P<0.0001). Three months after insulin treatment, oxidized LDL/LDL-C ratio was significantly reduced (21.1+/-4.7 vs. 24.0+/-5.8 U/mmol, P<0.01). This reduction was strongly associated, in multivariate analysis, with reduction of LDL(TG/cholesterol ratio) (P=0.008), and to a lesser extent with the decrease of LDL fructosamine (P=0.034), but not with the increase of the number of LDL receptors. CONCLUSIONS: In the present study we demonstrate for the first time a lowering effect of insulin therapy on oxidized LDL/LDL-C ratio in type 2 diabetic patients. This decrease is mainly associated with the reduction of LDL TG-enrichment, and to a lesser extent with the decrease of LDL glycation, but not with the insulin-induced increase in number of LDL receptors.     

Qualitative effect of fenofibrate and quantitative effect of atorvastatin on LDL profile in combined hyperlipidemia with dense LDL.

INTRODUCTION: The association of elevated plasma triglyceride concentrations, decreased HDL-cholesterol, and dense LDL (dLDL) is referred to as the atherogenic lipoprotein phenotype. dLDL particularly plays a role in the metabolic syndrome and type 2 diabetes and may be one of the factors responsible for the increased risk for coronary artery disease in these patients. The effect of fenofibrate and atorvastatin on the LDL subfraction profile in patients with combined hyperlipidemia and a preponderance of dLDL was studied in a sequential design. METHODS: Six male patients with combined hyperlipidemia and dLDL received 160 mg/die supra-bioavailable fenofibrate. After a washout phase of 8 weeks all patients received 10 mg/die atorvastatin for another 8 weeks. At baseline, after fenofibrate, and after atorvastatin treatment LDL subfractions were analyzed by equilibrium density gradient ultracentrifugation. RESULTS: Treatment with atorvastatin and fenofibrate reduced serum cholesterol by 30 % and 21 % (p = 0.046) (p-values for differences between treatment groups), triglycerides by 32 % and 45 %, LDL cholesterol by 28 % and 16 %, and increased HDL cholesterol by 3 % and 6 %, respectively. Atorvastatin and fenofibrate treatment resulted in the following changes of apoB and LDL subfractions: LDL-1 (1.019 - 1.031 kg/L) - 31 % and + 15 % (p = 0.028); LDL-2 (1.031 - 1.034 kg/L) - 14 % and + 57 % (p = 0.028); LDL-3 (1.034 - 1.037 kg/L) - 20 % and + 30 % (p = 0.028); LDL-4 (1.037 - 1.040 kg/L) - 25 % and - 6 %; LDL-5 (1.040 - 1.044 kg/L) - 29 % and - 38 %; and LDL-6 (1.044 - 1.063 kg/L) - 39 % and - 55 % (p = 0.028). As a consequence, fenofibrate reduced LDL density significantly (p = 0.028 versus atorvastatin). CONCLUSIONS: Atorvastatin decreased all LDL-subfractions to a similar extent (quantitative effect) whereas fenofibrate reduced predominantly dLDL and changed the LDL profile towards medium dense LDL-particles (qualitative effect). Since medium dense LDL have a higher affinity to the LDL-receptor fenofibrate may have a higher antiatherogenic potential than assessed by the reduction of total LDL-cholesterol and triglycerides alone.     

Effects of a phytosterol-enriched dairy product on lipids, sterols and 8-isoprostane in hypercholesterolemic patients: a multicenter Italian study

Background and aimsPlant sterols, added to several food sources, lower serum cholesterol concentrations. Plant sterol-induced cholesterol lowering is paralleled by a mild decrease in plasma levels of the antioxidant β-carotene, the amount of this decrease being considered clinically non-significant. Whether the effect on lipid profile of daily consumption of plant sterol-enriched low-fat fermented milk (FM) is paralleled by a concomitant variation in a reliable marker of the oxidative burden like plasma isoprostane levels is unresolved.Methods and resultsThe effect of plant sterol consumption on plasma lipid and isoprostane levels of hypercholesterolemic patients was evaluated in a multicenter, randomized double blind study. Hypercholesterolemic patients consumed a FM daily for 6 weeks. Subjects were randomized to receive either 1.6 g of plant sterol-enriched FM (n = 60) or control FM product (n = 56). After 6 weeks of plant sterol-enriched FM consumption, LDL cholesterol was reduced from 166.2 ± 2.0 to 147.4 ± 2.8 mg/dL (p = 0.01). A significant reduction was observed for total cholesterol (from 263.5 ± 2.6 to 231.0 ± 3.2 mg/dL, p = 0.01). There was greater LDL cholesterol lowering among hypercholesterolemic patients with higher LDL cholesterol at baseline. We found a reduction of plasma 8-isoprostane in patients taking plant sterol-enriched FM (from 43.07 ± 1.78 to 38.04 ± 1.14 pg/ml, p = 0.018) but not in patients taking the control product (from 42.56 ± 2.12 to 43.19 ± 2.0 pg/ml, p = NS). Campesterol and β-sitosterol levels were not influenced by phytosterol consumption.ConclusionsDaily consumption of low-fat plant sterol dairy product favourably changes lipid profile by reducing LDL-cholesterol, and may also have an anti-oxidative effect through a reduction of plasma isoprostanes.     

Increased exhaled cysteinyl-leukotrienes and 8-isoprostane in aspirin-induced asthma

The pathogenesis of aspirin-induced asthma (AIA) has not yet been clearly elucidated, although eicosanoid metabolites appear to play an important role. We hypothesized that levels of eicosanoids in exhaled air condensate are abnormal in patients with AIA and that they change in patients receiving steroid therapy. We measured cysteinyl-leukotrienes (cys-LTs), prostaglandin E(2) (PGE(2)), and leukotriene B(4) (LTB(4)), and also 8-isoprostane as a marker of oxidative stress, by enzyme immunoassay in exhaled breath condensate from patients with AIA (17 steroid naive; mean age, 41 +/- 23 years; FEV(1), 63%pred), 26 patients with aspirin-tolerant asthma (ATA) (11 steroid naive; mean age, 47 +/- 18 years; FEV(1), 69%pred), and 16 healthy subjects (mean age, 45 +/- 17 years; FEV(1), 93%pred). Cys-LTs were significantly higher in steroid-naive patients with AIA compared with steroid-naive patients with ATA and healthy subjects (152.3 +/- 30.4 and 36.6 +/- 7.1 versus 19.4 +/- 2.8 pg/ml; p < 0.05 and p < 0.05, respectively). Steroid-naive patients with AIA also had higher levels of 8-isoprostane than normal subjects (131.8 +/- 31.0 versus 21.9 +/- 4.5 pg/ml; p < 0.05). There were significantly lower levels of both cys-LTs and 8-isoprostanes in steroid-treated patients with AIA. There was no difference in either the PGE(2) or LTB(4) level between the patient groups. This is the first study to show that cys-LTs and 8-isoprostanes are elevated in expired breath condensate of steroid-naive patients with AIA, and that cys-LTs are decreased in steroid-treated patients. Exhaled PGE(2) levels are not reduced, so that it is unlikely that a deficiency of PGE(2) is an important mechanism, whereas exhaled LTB(4) levels are unchanged, indicating an abnormality beyond 5-lipoxygenase.     

Distinguished effects of antiphospholipid antibodies and anti-oxidized LDL antibodies on oxidized LDL uptake by macrophages

Several interpretations have been made regarding the specificity of antiphospholipid antibodies and antibodies against oxidized low-density lipoprotein (oxLDL), but these are still controversial. In the present study, we delineated specificity of these two types of antibodies and analyzed their regulatory effect on oxLDL and/or beta( 2)-glycoprotein I (beta(2)GPI) binding to macrophages. Scavenger receptor-mediated binding of oxLDL (or its beta(2)GPI complexes) to macrophages was observed and the binding was partly prevented by beta( 2)GPI. The IgG monoclonal anti-beta(2)GPI antibody (WB-CAL-1), which was derived from NZW x BXSB F1 mouse (a model of antiphospholipid syndrome), significantly increased the oxLDL/beta(2)GPI binding to macrophages. In contrast, IgM anti-oxLDL natural antibody, EO6 (derived from apoe( -/-) mouse), prevented the binding. Different antigenic specificity of these antibodies to oxLDL and its beta(2)GPI complexes was also confirmed in TLC-ligand blot and ELISA. Thus, IgG anti-beta(2) GPI autoantibodies contribute to lipid metabolism (housekeeping of oxLDL by macrophages) whereas IgM natural anti-oxLDL antibodies may protect against atherogenesis. In addition, in vitro data suggest that relatively high dose of intravenous immunoglobulin preparations (mainly contain IgG anti-oxLDL antibodies) might also prevent atherogenesis by inhibiting the oxLDL binding to macrophages.     

Effects of amlodipine and candesartan on oxidized LDL level in patients with mild to moderate essential hypertension

Objective. To compare the effects of amlodipine and candesartan on oxidized low-density lipoprotein (OxLDL), conjugated dienes (CD) and baseline diene conjugation in circulating low-density lipoproteins (LDL-BDC) level during antihypertensive treatment. Methods. Forty-nine patients with untreated mild to moderate essential hypertension were recruited in a randomized double-blind study to receive a daily dose either of 8 mg candesartan or 5 mg amlodipine for 16 weeks. Blood pressure, OxLDL, CD, LDL-BDC, triglycerides (TG), total cholesterol and lipoprotein cholesterol were measured at baseline, at week 2 and at week 16. Results. During treatment, in addition to a significant decrease in systolic and diastolic blood pressure, high level of OxLDL decreased significantly reaching practically upper kit reference values. Both treatment groups were similar with regard to the studied parameters at all time points. At the same time serum TG, lipoprotein and total cholesterol levels as well as LDL-BDC did not change and CD levels did not exceed endemic normal. Decrease in both systolic and diastolic blood pressure was associated with decrease in LDL-BDC/LDL. Conclusions. Besides their antihypertensive effects, both candesartan and amlodipine are efficient drugs for reducing OxLDL level, being neutral with regard to serum lipids.     

COPD患者血清中8-异前列腺素的检测及其意义

目的研究慢性阻塞性肺疾病（COPD）患者血清中8-异前列腺素（8-isoPG）浓度的改变及临床意义。方法收集COPD患者（40例）急性发作期和缓解期以及正常对照组（30例）的血清,用酶标记法检测血清中8-isoPG,同时检测AECOPD患者的第一秒呼气容量（FEV1）、最大呼气流速（PEF）、pH值、PaCO2、PaO2及血白细胞总数。结果①COPD患者急性发作期8-isoPG为35.43±7.29ng/L,高于缓解期（24.71±8.25ng/L）及正常对照组（13.31±6.19ng/L）,P〈0.05;②COPD患者8-isoPG浓度与痰量呈正相关,r=0.217,P〈0.05。结论 COPD的急性发作期,8-isoPG升高反映了氧化应激增强。     

维生素E与维生素C联合治疗对糖耐量受损患者氧化低密度脂蛋白及C反应蛋白的作用

36例糖耐量受损（IGT）患者和33例正常对照的研究显示，IGT组的氧化低密度脂蛋白、C反应蛋白和丙二醛水平明显高于正常对照组。经8周维生素E（每日200mg）和维生素C（每日500mg）联合治疗，上述指标明显改善。