Physico-chemical properties of low density lipoproteins isolated in an equilibrium density gradient

The tryptophanyls of total low density lipoproteins (LDL) (1.006-1.063 g/ml) from coronary heart disease (CHD) patients and subjects without CHD signs had different accessibility to fluorescence quenchers (I-and acrylamide). LDL were separated into subfractions in equilibrium density gradient. The coefficient of extinction , quantum yield and other spectral characteristics of LDL intrinsic fluorescence, rotational mobility of maleimide spin labels and fatty acid spin probe were different in LDL subfractions from healthy subjects. LDL subfractions with hydrated density 1.045-1.05 g/ml bound to B,E-receptors of cultured fibroblasts more effectively than did subfractions with density 1.01-1.03 g/ml. Structural differences of apo-B in the particles with different lipid to protein ratio are supposed.     

Low-density lipoprotein derived from atherosclerotic patients enhances macrophage cholesterol accumulation and in vitro platelet aggregation

The aims of our study were to assess the differences between plasma lipoproteins separated from five angiographically normal subjects and five patients with proven CHD. The patients with CHD had significantly higher levels of LDL-cholesterol and apo-B, and reduced levels of HDL-cholesterol and apo-Al. The biological characteristics of LDL and HDL from both groups of patients demonstrated that the LDL from the CHD patients enhanced platelet aggregation and increased cholesterol content and cholesterol esterification in MPM compared to the normal patients. HDL had no significant effect on MPM; however, there was an increased platelet aggregation with HDL derived from the CHD patients, while the HDL from the normal group decreased platelet aggregation. The data suggest that lipoproteins isolated from CHD patients are more atherogenic than lipoproteins from normal patients.     

Low density lipoproteins isolated from the blood of patients with ischemic heart disease induce accumulation of lipids in human aortic intima cells

Very low density lipoproteins (VLDL), low density lipoproteins (LDL) and high density lipoproteins (HDL) were isolated from the blood of healthy subjects and CHD patients. LDL from the blood of healthy individuals did not raise the intracellular lipid values within 24 h of cultivation. During intracellular lipid values within 24 h of cultivation. During the same incubation period. LDL obtained from the blood of CHD patients caused a 2- to 5-fold rise in cholesterol esters as well as a 1.5- to 3-fold rise in free cholesterol and triglycerides, while the intracellular phospholipid levels remained unchanged. In one of the three cases, the ability to raise the intracellular level of cholesterol esters was demonstrated by VLDL (500 micrograms/ml) derived from CHD patients blood. HDL did not affect the lipid levels in smooth muscle cells cultured from unaffected intima. The obtained data suggests that circulating LDL and, possibly, VLDL in the blood of CHD patients are capable of inducing the accumulation of fat in vascular wall cells.     

Low density lipoprotein metabolism in hypertriglyceridemic and normolipidemic patients with coronary heart disease

The turnover rates of low density lipoprotein-apolipoprotein B (LDL-apoB) were determined in 32 men with coronary heart disease (CHD) and 11 control men with normal plasma lipids. Thirty patients with CHD had normal levels of LDL-cholesterol (LDL-C); of these patients, 9 had hypertriglyceridemia and 21 had normal plasma lipids. Mean concentrations of total cholesterol and LDL-C were similar among the control subjects and CHD patients, although the latter had significantly lower HDL-C. In control subjects, transport rates and fractional catabolic rates (FCR) of LDL-B were 10.6 +/- 0.5 (SEM) mg/kg-day and 0.31 +/- 0.01 pools/day, respectively. In 10 hypertriglyceridemic patients with CHD, transport rates were 21.7 +/- 1.7 mg/kg-day, and FCRs averaged 0.56 +/- 0.06 pools/day; both were significantly higher than normal (P less than 0.05). Six normolipidemic patients also had abnormally high transport rates of LDL-apoB (19.4 +/- 2.8 mg/kg-day) and FCRs (0.51 +/- 0.03 pools/day); again both were higher than normal. The remaining 16 normolipidemic patients with CHD had normal transport rates (9.9 +/- 0.6 mg/kg-day) and FCRs (0.28 +/- 0.01 pools/day). Thus, hypertriglyceridemic patients with CHD and a portion of normolipidemic patients with CHD were characterized by increases in both transport and fractional catabolic rate of LDL-apoB; these abnormalities in LDL metabolism may have contributed to their coronary heart disease. However, the majority of normolipidemic patients with CHD did not show a distinct defect in their LDL metabolism.     

Sialic acid content of human low density lipoproteins affects their interaction with cell receptors and intracellular lipid accumulation.

Low density lipoproteins (LDL) isolated from the plasma of patients with angiographically demonstrable coronary heart disease (CHD) induced accumulation of triglycerides, free cholesterol, and cholesteryl esters in cultured macrophages, smooth muscle cells, and endothelial cells derived from uninvolved intima of human aorta, but not in skin fibroblasts or hepatoma cells. The sialic acid content of LDL from CHD patients was 40-75% lower than that from healthy donors. There was a negative correlation between LDL sialic acid content and the LDL-induced accumulation of total intracellular cholesterol. Neuraminidase treatment of LDL from normal healthy donors produced sialic acid-depleted LDL (Ds-LDL) which was able to stimulate intracellular lipid accumulation. Neuraminidase treatment of LDL from CHD patients further increased its capacity to induce intracellular lipid accumulation. Sialic acid-poor LDL isolated by affinity chromatography of LDL from CHD patients induced a 2- to 4-fold increase of free and esterified cholesterol in human intimal smooth muscle cells. Binding, uptake, and degradation of 125I-labeled Ds-LDL by macrophages and endothelial cells were 1.5- to 2-fold higher than for native LDL. Binding and uptake of Ds-LDL was inhibited 64-93% by the addition of 20-fold excess acetylated LDL (Ac-LDL); in the inverse experiment, the level of inhibition was 35-54%. These data indicate that a sialic acid-poor form of LDL isolated from CHD patients can interact with both native and scavenger LDL receptors. A sialic acid-poor form of LDL may be a naturally occurring ligand that interacts with the scavenger receptor(s) on macrophages and endothelial cells.     

Additive Antiatherogenic Effects of CETP rs708272 on Serum LDL Subfraction Levels in Patients with CHD Under Statin Therapy

Recently, subfraction analysis of serum low density lipoprotein (LDL) is considered to be a better predictor of the risk of coronary heart disease (CHD) compared to the other lipid parameters. The aim of this study was to examine the effects of the HDL-associated Taq1B (rs708272) SNP of cholesterol ester transfer protein (CETP) gene on serum LDL subfractions in patients with CHD. Serum lipid levels were measured enzymatically and LDL subfraction analysis was carried out by the Lipoprint System (Quantimetrix, CA, USA). The CETP rs708272 SNP was studied in 66 healthy controls and 79 patients with CHD receiving statin therapy by the PCR–RFLP technique. The CHD patients had elevated antiatherogenic LDL-1 subfraction (p = 0.042), decreased atherogenic IDL-C subfraction (p = 0.023), and total IDL (p = 0.030) levels compared to the healthy controls. The CETP rs708272 Taq1B minor B2 allele was associated with increased levels of antiatherogenic LDL-1 (B2: 0.40 ± 0.20 vs. B1B1: 0.25 ± 0.08, p = 0.004) and large-LDL (LDL 1–2) subfractions in the CHD group (B2 allele: 0.68 ± 0.41 vs. B1B1: 0.42 ± 0.20; p < 0.05), while it was associated with reduced levels of the large-LDL subfraction in healthy subjects (B2 allele: 0.29 ± 0.14 vs. B1B1: 0.54 ± 0.24; p = 0.017). However, there was no statistically significant association between the CETP rs708272 SNP and small dense LDL subfraction (LDL 3–7) and lipoprotein levels (p > 0.05). Our findings have indicated that the CETP rs708272 SNP together with statin therapy may show a favorable effect on antiatherogenic LDL-1 and large-LDL subfractions in CHD patients with an atherogenic effect on large-LDL subfraction in healthy subjects. Based on these results, it can be concluded that the effects of the CETP variation on LDL subfraction could change in cardiometabolic events such as CHD and statin therapy.     

Surface binding and catabolism of low-density lipoprotein by circulating lymphocytes from patients with abetalipoproteinaemia, with observations on sterol synthesis in lymphocytes from one patient.

Surface binding of low-density lipoprotein (LDL), degradation of LDL protein and sterol synthesis were investigated in freshly isolated lymphocytes from normal and abetalipoproteinamic human subjects. LDL binding as a function of LDL concentration showed no evidence of the presence of high-affinity binding sites in fresh lymphocytes from either group of subjects. The rate of degradation of LDL protein by lymphocytes from the patients was no greater than that from the normal subjects and, in the fresh lymphocytes of the one patient studied, sterol synthesis was not increased. We conclude that the formation of LDL receptors and the synthesis of sterol in circulating lymphocytes are largely suppressed and that in normal subjects this may be due to the presence of some plasma constituent other than LDL, possibly the apoE protein. This conclusion is discussed in relation to the possible contribution of LDL receptors to the degradation of LDL protein in vivo.     

冠心病患者低密度脂蛋白与血小板GMP-140水平相关性研究

目的：探讨冠心病患者低密度脂蛋白与血小板功能活化产物GMP-140的关系。方法：应用酶联免疫分析法对120例研究对象进行了血浆LDL、GMP-140水平的测定,其中包括急性冠脉综合征组40例,稳定性心绞痛组40例,并与40例正常健康人作比较。结果：ACS患者血浆LDL和GMP-140水平均非常显著的高于正常人组（P〈0.01）,ACS组又高于SAP组（P〈0.05）,且血浆LDL与GMP-140水平呈正相关。结论：检测CHD患者血浆LDL和GMP-140水平的变化对CHD的发生和发展以及疗效和预后观察均具有重要的临床意义。     

Evaluation of Lp[a] and other independent risk factors for CHD in Asian Indians and their USA counterparts

Conventional risk factors for coronary heart disease (CHD) do not completely account for the observed increase in premature CHD in people from the Indian subcontinent or for Asian Indians who have immigrated to the USA. The objective of this study was to determine the effect of immigration to the USA on plasma levels of lipoprotein [a] (Lp[a]) and other independent risk factors for CHD in Asian Indians. Three subject groups were studied: group 1, 57 subjects living in India and diagnosed with CHD (CHD patients); group 2, 46 subjects living in India and showing no symptoms of CHD (control subjects); group 3, 206 Asian Indians living in the USA. Fasting blood samples were drawn to determine plasma levels of triglyceride (TG), total cholesterol (TC), low density lipoprotein [LDL cholesterol (LDL-Chol)], high density lipoprotein [HDL cholesterol (HDL-Chol)], apolipoprotein B-100 (apoB-100), and Lp[a]. Apolipoprotein [a] (apo[a]) size polymorphism was determined by immunoblotting. Plasma TG, apoB-100, and Lp[a] concentrations were higher in CHD patients than in control and USA groups. CHD patients had higher levels of TC and LDL-Chol and lower HDL-Chol than control subjects. However, the USA population had higher levels of TC, LDL-Chol, and apoB-100 and lower HDL-Chol than control subjects. Plasma Lp[a] levels were inversely correlated with the relative molecular weight of the more abundant of each subject's two apo[a] isoforms (MAI), and CHD patients showed higher frequencies of lower relative molecular weights among MAI. Our observed changes in lipid profiles suggest that immigrating to the USA may place Asian Indians at increased risk for CHD. This study suggests that elevated plasma Lp[a] confers genetic predisposition to CHD in Asian Indians, and nutritional and environmental factors further increase the risk of CHD. This is the first report implicating MAI size as a predictor for development of premature CHD in Asian Indians. Including plasma Lp[a] concentration and apo[a] phenotype in screening procedures may permit early detection and preventive treatment of CHD in this population.     

Desialylated low density lipoproteins--atherogenic lipoproteins occurring in blood of patients with coronary atherosclerosis

We have recently established that LDL of most patients with coronary atherosclerosis differ from the LDL of most healthy subjects by the ability to cause primary atherosclerotic changes, i.e. the accumulation of intracellular cholesterol in the cells of smooth muscle origin cultured from unaffected intima of human aorta. We assumed that patients LDL is modified lipoprotein differing from native LDL by chemical composition. It has been established in the present study that patients LDL has a substantially lower content of sialic acid as compared with the LDL of healthy subjects. Desialylation of native LDL of healthy subjects with neuraminidase makes them atherogenic, therefore, capable of causing the accumulation of intracellular cholesterol similarly to patients LDL.     

Polymorphisms in the NQO1, GSTT and GSTM genes are associated with coronary heart disease and biomarkers of oxidative stress

It was hypothesized that the presence of genetic polymorphisms that decrease activity of the detoxification enzymes glutathione-S-transferase (GST) and quinone oxido-reductase (NQO1) may contribute to heart disease and affect biomarkers of coronary health and oxidative stress. Sixty-seven patients with angiographically confirmed coronary heart disease (CHD) and 63 healthy controls were genotyped for polymorphisms in the GST isoforms Mu and Theta (GSTM and GSTT respectively) and NQO1. Participants' blood levels of homocysteine (Hcy), C-reactive protein (CRP), oxidized low density lipoprotein (LDL) and total antioxidant capacity (TAOX) were measured. TAOX levels were significantly lower in women than men (P < or = 0.001) and this finding was more marked in the control group (P < or = 0.001). Hcy levels were higher in CHD patients (P=0.003 vs. control) which was mostly attributed to female patients (P=0.034 case vs. control). GSTM polymorphisms were present with greater frequencies in CHD cases with the odds ratio (OR) for GSTM equal to 3.77 vs. control. CHD patients also have an increased incidence of both GSTM and GSTT null polymorphisms (OR=5.13). In contrast, NQO1 polymorphisms were protective in CHD patients (OR=0.18 vs. control), which when stratified for genotype was due to heterozygous individuals. Significantly higher C-reactive protein levels occurred in CHD patients with lower NQO1 activity (P=0.001), however, due to the large variations in CRP levels seen in CHD patients; the clinical importance of this difference is unclear. Smokers with the GSTM null polymorphism were more likely to have CHD than non-smokers expressing the GSTM null polymorphism (OR=3.54, P=0.079). We conclude that a lack of activity in the detoxification enzymes NQO1 and GSTM, and biomarker levels are strongly associated with coronary heart disease with sex as a mitigating factor.     

Changes in the surface potential of plasma lipoproteins in ischemic heart disease. Studied with spin probes

Changes in lipoprotein surface potentials were studied by a positively charged analog as a spin probe. Low density lipoproteins (LDL) and high density lipoproteins (subfractions HDL2 and HDL3) of patients with coronary heart disease (CHD) were studied. CHD patients have revealed a significant decrease (by 14.4 +/- 0.3 mV) in LDL and an increase (by 6.3 +/- 2.0 mV) in HDL3 negative surface potential, as compared to the control. The increase in HDL2 surface potential in CHD patients was insignificant (1.9 +/- +/- 2.5 mV). The possible role of LDL and HDL3 surface potential changes in the mechanism of interaction of these types of lipoproteins with vascular wall and blood cellular membranes and in pathogenesis of CHD and atherosclerosis is discussed.     

Peroxide modification of low density lipoproteins in ischemic heart disease

It is shown that the LDL peroxide lipid products level is 1.6-4 times higher in patients with the ischemic heart diseases (IHD) than in normal subjects. At the same time the LDL uptake by macrophages was identical in case of normal subjects and of IHD patients. It is suggested that the LDL premodification in the blood flow in the IHD patients promotes the further modification of LDL particles after their penetration into the vessel wall.     

Levels of apolipoprotein M are not associated with the risk of coronary heart disease in two independent case-control studies

Apolipoprotein M (apoM), a 25 kDa plasma protein belonging to the lipocalin protein family, is predominantly associated with HDL. Studies in mice have suggested apoM to be important for the formation of pre-beta-HDL and to increase cholesterol efflux from macrophage foam cells. Overexpression of human apoM in LDL receptor-deficient mice reduced the atherogenic effect of a cholesterol-rich diet. The aim of the present study was to investigate whether the apoM levels in man predict the risk for coronary heart disease (CHD). ApoM was measured in samples from two separate case-control studies. FINRISK '92 consisted of 255 individuals, of whom 80 developed CHD during follow-up and 175 were controls. The Copenhagen City Heart Study included 1,865 individuals, of whom 921 developed CHD during follow-up and 944 were controls. Correlation studies of apoM concentration with several analytes showed a marked positive correlation with HDL and total cholesterol as well as with apoA-I and apoB. There was no significant difference in mean apoM level between CHD and control subjects in either study. In conditional logistic regression analyses, apoM was not a predictor of CHD events, [odds ratio (95% CI) 0.97 (0.74-1.27) and 0.92 (0.84-1.02), respectively]. In conclusion, no association between apoM and CHD could be found in this study.     

Lycopene,tomatoes, and the prevention of coronary heart disease

Coronary heart disease (CHD) is one of the primary causes of death in the Western world. The emphasis so far has been on the relationship between serum cholesterol levels and the risk of CHD. More recently, oxidative stress induced by reactive oxygen species (ROS) is also considered to play an important part in the etiology of this disease. Oxidation of the circulating low-density lipoprotein (LDL(ox)) is thought to play a key role in the pathogenesis of atherosclerosis and CHD. According to this hypothesis, macrophages inside the arterial wall take up the LDL(ox) and initiate the process of plaque formation. Dietary antioxidants such as vitamin E and beta-carotene have been shown in in vitro studies to prevent the formation of LDL(ox) and their uptake by microphages. In a recent study, healthy human subjects ingesting lycopene, a carotenoid antioxidant, in the form of tomato juice, tomato sauce, and oleoresin soft gel capsules for 1 week had significantly lower levels of LDL(ox) compared with controls. The antioxidant effects of lycopene have also been shown in four other human trials, including one where lycopene consumption reduced the levels of breath pentane. However, in one recent study, dietary supplementation with beta-carotene but not with lycopene was shown to inhibit LDL oxidation. The sources of lycopene used in most of these studies were either tomato products or lycopene extracted from tomatoes containing other carotenoids in various proportions. Therefore, it is not possible to attribute the effects solely to lycopene. Mechanisms other than the antioxidant properties of lycopene have also been shown to reduce the risk of CHD. Lycopene was shown to inhibit the activity of an essential enzyme involved in cholesterol synthesis in an in vitro and a small clinical study suggesting a hypocholesterolemic effect. Other possible mechanisms include enhanced LDL degradation, LDL particle size and composition, plaque rupture, and altered endothelial functions. Recent epidemiological studies have also shown an inverse relationship between tissue and serum levels of lycopene and mortality from CHD, cerebrovascular disease, and myocardial infraction. However, the most impressive population-based evidence comes from a multicenter case-control study where subjects from 10 European countries were evaluated for relationship between antioxidant status and acute myocardial infarctions. After adjusting for a range of dietary variables, only lycopene levels but not beta-carotene were found to be protective. At present, the role of lycopene in the prevention of CHD is strongly suggestive. Although the antioxidant property of lycopene may be one of the principal mechanism for its effect, other mechanisms may also be responsible. Controlled clinical and dietary intervention studies using well-defined subject populations and disease end points must be undertaken in the future to provide definitive evidence for the role of lycopene in the prevention of CHD. Mechanistic studies must also be initiated to understand the mode of lycopene action.     

Native and modified low-density-lipoprotein interaction with human platelets in normal and homozygous familial-hypercholesterolaemic subjects.

The binding of low-density lipoproteins (LDL) as well as LDL modified by cyclohexanedione (CHD-LDL) to gel-filtered platelets (GFP) and its effect on platelet function were studied in normal and in homozygous familial hypercholesterolaemic (HFH) subjects. Only normal-derived LDL could significantly compete with normal 125I-labelled LDL for binding to normal platelets. When GFP from normal subjects were incubated with normal LDL at concentrations of 25-200 micrograms of protein/ml, platelet aggregation in the presence of thrombin (0.5 i.u./ml) was increased by 65-186%. CHD-LDL, at similar concentrations, caused the opposite effect and decreased platelet aggregation by 26-47%. Both LDL and CHD-LDL (100 micrograms/ml) from HFH patients, when incubated with normal GFP, caused a significant reduction in platelet aggregation (33 and 50% respectively). When HFH-derived platelets were used, both patient LDL and CHD-LDL (but not the normal lipoprotein) could markedly compete with the patient 125I-labelled LDL for binding to the platelets. LDL and CHD-LDL (100 micrograms/ml) from normal subjects decreased aggregation of HFH-platelets by 52 and 85% respectively, while corresponding concentrations of LDL derived from HFH subjects (HFH-LDL) and CHD-LDL derived from HFH subjects (CHD-HFH-LDL) increased platelet aggregation by 165 and 65% respectively. The present results support the following conclusions: platelet activation by LDL in normal subjects is through the arginine-rich apoprotein-binding site; more than one binding site for LDL exists on platelets; under certain circumstances, LDL binding can cause a reduction in platelet activity; specificity for LDL binding to the platelets resides in different regions of the lipoprotein in HFH and in normal subjects. We have thus suggested a model for LDL-platelet interaction in normal and in HFH subjects.     

冠心病患者血浆CD69、DKK-1与血脂、炎性因子的关系及其诊断价值分析

摘要 目的：分析冠心病（CHD）患者血浆CD69、Wnt拮抗剂蛋白-1（DKK-1）与血脂、炎性因子的关系,并分析CD69和DKK1对于CHD患者的诊断价值。方法：选取2016年6月~2018年12月在我院诊治的CHD患者136例,根据Gensini评分分为轻度亚组、中度亚组、重度亚组,同时纳入与之年龄、性别匹配的冠状动脉造影正常者136例作为对照组。检测受试者血清炎性因子、血脂、及血浆CD69、DKK-1水平,分析CHD患者CD69、DKK-1水平与血脂、炎性因子、Gensini评分的相关性,采用受试者工作特征（ROC）曲线分析CD69和DKK1对于CHD患者的诊断价值。结果：CHD患者CD69、DKK-1、白细胞介素-10（IL-10)、白细胞介素-6（IL-6）、三酰甘油（TG）、总胆固醇（TC）、低密度脂蛋白（LDL）水平高于对照组,高密度脂蛋白（HDL）水平低于对照组（P<0.05）;随着冠脉狭窄病变程度的加重,CD69、DKK-1、IL-10、IL-6、TC、TG、LDL水平呈升高趋势,HDL水平呈降低趋势（P<0.05）。CHD患者CD69、DKK-1水平与IL-10、IL-6、TC、TG、LDL、Gensini评分均呈正相关,与HDL呈负相关（P<0.05）。ROC曲线分析结果显示,CD69、DKK-1联合检测诊断CHD的灵敏度、特异度分别为0.816、0.846。结论：CHD患者血浆DKK-1、CD69水平升高,与血脂、炎性因子和Gensini评分密切相关,两者联合检测可提高CHD诊断效能。     

Isolation of desialylated low density lipoproteins from the blood of patients with ischemic heart disease by affinity chromatography

The attempt was performed to isolate desialylated low density lipoproteins (LDL) from the blood of healthy subjects and patients with coronary heart disease by affinity chromatography with immobilized agglutinin of Ricinus communis, a lectin that interacts specifically with galactose residues. A part of LDL was bound to sorbent and could be replaced by galactose but not other saccharide constituents of the LDL molecule. Bound LDL subfraction had a 2-3-fold lower content of desialylated LDL in CAD patients was about 3-fold higher than in healthy subjects. Desialylated LDL induced a 2- to 4-fold increase of total cholesterol content in cultured human aortic intimal cells, whereas unbound LDL had no effect on intracellular cholesterol level. It is assumed that the subfraction of desialylated LDL may be responsible for the atherogenic properties of LDL in CAD patients.     

Isolation of atherogenic modified (desialylated) low density lipoprotein from blood of atherosclerotic patients: separation from native lipoprotein by affinity chromatography

A part of low density lipoproteins (LDL) isolated from the blood of healthy subjects and patients with coronary atherosclerosis bind to a Sepharose-linked Ricinus communis agglutinin, a lectin that interacts specifically with galactose residues. Bound LDL can be replaced by galactose, but not other saccharide constituents of the LDL molecule (mannose, glucose, N-acetylglucosamine, sialic acid). Bound LDL subfraction has a 2-3-fold lower content of sialic acid as compared with unbound LDL. The blood content of desialylated LDL in atherosclerotic patients was about 3-fold higher (1.5- to 6-fold) than in healthy subjects. Desialylated LDL induced a 2- to 4-fold more intensive accumulation of total cholesterol in cultured human aortic intimal cells. Unbound LDL had no effect on intracellular deposition of lipids. It is suggested that the subfraction of desialylated LDL may be responsible for the atherogenicity of LDL isolated from blood of atherosclerotic patients.