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Sample records for density lipoprotein subclass

  1. Low density lipoprotein subclasses in Asian and Caucasian adolescent boys.

    PubMed

    Raschke, Verena; Elmadfa, Ibrahim; Bermingham, Margaret A; Steinbeck, Kate

    2006-01-01

    South Asian adults are known to have very high rates of Coronary heart disease (CHD) and insulin resistance and, even as adolescents, may show higher risk factors for CHD. The aim of this study was to investigate the prevalence of small, dense low density lipoprotein (sdLDL) subclasses in a cohort of adolescent boys. The specific objective was to investigate the relationship between measures of fatness, ethnicity and LDL diameter in this cohort. Preformed native (non-denaturing) polyacrylamide 3-13% gradient gels and a multipurpose vertical electrophoresis system were used for the separation of LDL sub-fractions in a single school year cohort of boys aged 15-16 years (n=135). Latex beads and thyroglobulin standards were used to construct a calibration curve in order to calculate LDL particle diameters by regression (Total Lab Software v1.11). ANOVA was used to compare LDL size among different ethnic groups (SPSS and Stat View). The study sample was comprised of 45.2% Caucasians, 41.5% East Asians and 13.3% from the Indian subcontinent (South Asians). There was a non-significant trend for South Asians to have a lower LDL diameter than either Caucasians or East Asian boys which was independent of % total body fat (%TBF) and body mass index (BMI). This is the first adolescent cohort to examine sdLDL which included Caucasians, East and South Asians. It appears that the higher risk profile for CHD and diabetes noted in South Asian adults may be evident even during adolescence. PMID:17077065

  2. Alterations of high density lipoprotein subclasses in obese subjects.

    PubMed

    Tian, Li; Jia, Lianqun; Mingde, Fu; Tian, Ying; Xu, Yanhua; Tian, Haoming; Yang, Yuye

    2006-08-01

    The object of this study was to investigate the characteristics of lipid metabolism in obese subjects, with particular emphasis on the alteration of HDL subclass contents and distributions. A population of 581 Chinese individuals was divided into four groups (25 underweight subjects, 288 of desirable weight, 187 overweight, and 45 obese) according to body mass index (BMI). Apoprotein A-I (apoA-I) contents of plasma HDL sub-classes were determined by 2-D gel electrophoresis associated with an immunodetection method. The concentrations of TG and the apoA-I content of pre-beta 1-HDL were significantly higher (P < 0.01 and P < 0.01, respectively), but the levels of HDL cholesterol, and the apoA-I contents of HDL2a and HDL2b were significantly lower (P < 0.01, P < 0.05, and P < 0.01, respectively) in obese subjects than in subjects having a desirable weight. Moreover, with the elevation of BMI, small-sized pre-beta 1-HDL increased gradually and significantly, whereas large-sized HDL2b decreased gradually and significantly. Meanwhile, the variations in HDL subclass distribution were more obvious with the elevation of TG levels in obese as well as overweight subjects. In addition, Pearson correlation analysis revealed that BMI and TG levels were positively correlated with pre-beta 1-HDL but negatively correlated with HDL2b. Multiple regression analysis also showed that TG concentrations were associated independently and positively with high pre-beta 1-HDL and independently and negatively with low HDL2b in obese and overweight subjects. The HDL particle size was smaller in obese and overweight subjects. The shift to smaller size was more obvious with the elevation of BMI and TG, especially TG levels. These observations, in turn, indicated that HDL maturation might be abnormal, and reverse cholesterol transport might be impaired. PMID:17120933

  3. The relationship between high density lipoprotein subclass profile and plasma lipids concentrations

    PubMed Central

    2010-01-01

    HDL particles posses multiple antiatherogenic activities and the identification and differentiation of individual HDL subclasses may be useful in documentation and understanding of metabolic changes of different HDL subclasses. The major plasma lipids exist and are transported in the form of lipoprotein complexes. Hence, alterations in plasma lipids levels can interfere with the composition, content, and distribution of plasma lipoprotein subclasses that affect atherosclerosis risk. The research review major discussed the relationship between plasma lipids levels and HDL subclasses distribution. The general shift toward smaller size of HDL particle size in HTG, HCL and MHL subjects, and the changes were more prominent with the elevation of TG and TC levels which imply that HDL maturation might be abnormal and RCT pathway might be weaken, and these changes were more seriously in MHL subjects. Plasma contents of small sized HDL particles significantly higher, whereas those of large sized HDL particles were significantly lower with elevation of TG/HDL-C and TC/HDL-C ratios. Increased in the TC/HDL-C ratio alone did not influence the distributions of HDL subclasses significantly when the TG/HDL-C ratio was low (TG/HDL-C ? 2.5). Hence, the TG/HDL-C ratio might be more sensitive to reflect the alteration of HDL subclass distribution than the TC/HDL-C ratio. In LDL-C/HDL-C ? 2.3 group, the pattern of distribution in HDL subclass was in agreement with the normolipidemic subjects. Moreover, considering the relative ease of measuring TC/HDL-C, TG/HDL-C and LDL-C/HDL-C ratios, as opposed to measuring HDL subclasses, these 3 ratios together may be a good indicator of HDL subclass distribution. The protective effect of increased apoA-I levels against the reduction of HDL2b caused by elevated TG concentration. On one hand, plasma HDL-C and apoA-I appear to play a coordinated role in the assembly of HDL particles and the determination of their contents among the total subjects. On the other hand, the apoA-I level might be a more powerful factor than HDL-C to influence the distribution of HDL subclasses in hyperlipidemic subjects. At the same time, from point of HDL subclasses distribution, the plasma lipids, apos concentrations and apos ratios should be considered while assessing the CHD risk. Abnormality of HDL subclasses distribution may result in accelerated atherosclerosis, therapeutic normalization of attenuated antiatherogenic HDL function in terms of both particle number and distribution of HDL particles is the target of innovative pharmacological approaches to large-sized HDL particles rising, including enhanced apoA-I levels. PMID:20950490

  4. High-Density Lipoprotein Particle Subclass Heterogeneity and Incident Coronary Heart Disease

    PubMed Central

    Akinkuolie, Akintunde O.; Paynter, Nina P.; Padmanabhan, Latha; Mora, Samia

    2014-01-01

    Background Raising the cholesterol of HDL particles is targeted as a cardiovascular disease prevention strategy. However, HDL particles are heterogeneous in composition and structure, which may relate to differences in antiatherogenic potential. We prospectively evaluated the association of HDL subclasses, defined by a recently proposed nomenclature, with incident coronary heart disease (CHD). Methods and Results Baseline HDL particle concentrations were measured by nuclear magnetic resonance spectroscopy and categorized into five subclasses (very large, large, medium, small, and very small) among 26,332 initially healthy women. During a median follow-up of 17 years, 969 cases of incident CHD (myocardial infarction, revascularization, and CHD death) were ascertained. In Cox models that adjusted for age, race/ethnicity, blood pressure, smoking, postmenopausal status, and hormone therapy, associations with incident CHD were inverse (p-trend<0.0001) for concentrations of very large (hazard ratio [HR] for top versus bottom quartile 0.49, 95% confidence interval [CI] 0.41–0.60), large (0.54, 0.45–0.64), and medium (0.69, 0.58–0.83) HDL subclasses. Conversely, HRs (95% CIs) for small and very small HDL were 1.22 (1.01–1.46, p-trend=0.08) and 1.67 (1.39–2.02, p-trend<0.0001), respectively. However, after additionally adjusting for metabolic and lipoprotein variables, associations for the spectrum of large, medium, and small HDL subclasses were inverse (p-trend<0.05 for large and small, and 0.07 for medium), while subclasses at either end of the spectrum were not associated with CHD (p-trend=0.97 for very large and 0.21 for very small HDL). Conclusion In this prospective study, associations with incident CHD differed by HDL particle subclass, which may be relevant for developing HDL-modulating therapies. PMID:24248942

  5. Low density lipoprotein subclasses and response to a low-fat diet in healthy men

    SciTech Connect

    Krauss, R.M.; Dreon, D.M.

    1994-11-01

    Lipid and lipoprotein response to reduced dietary fat intake was investigated in relation to differences in distribution of LDL subclasses among 105 healthy men consuming high-fat (46%) and low-fat (24%) diets in random order for six weeks each. On high-fat, 87 subjects had predominantly large, buoyant LDL as measured by gradient gel electrophoresis and confirmed by analytic ultracentrifugation (pattern A), while the remainder had primarily smaller, denser LDL (pattern B). On low-fat, 36 men changed from pattern A to B. Compared with the 51 men in the stable A group, men in the stable B group (n = 18) had a three-fold greater reduction in LDL cholesterol and significantly greater reductions in plasma apoB and mass of intermediate (LDL II) and small (LDL III) LDL subtractions measured by analytic ultracentrifugation. In both stable A and change groups, reductions in LDL-cholesterol were not accompanied by reduced plasma apoB, consistent with the observation of a shift in LDL particle mass from larger, lipid-enriched (LDL I and II) to smaller, lipid-depleted (LDL III and IV) subfractions, without significant change in particle number. Genetic and environmental factors influencing LDL subclass distributions thus may also contribute substantially to interindividual variation in response to a low-fat diet.

  6. High-Density Lipoprotein Subclasses and Noncardiovascular, Noncancer Chronic Inflammatory-Related Events Versus Cardiovascular Events: The Multi-Ethnic Study of Atherosclerosis

    PubMed Central

    Duprez, Daniel A; Otvos, James; Tracy, Russell P; Feingold, Kenneth R; Greenland, Philip; Gross, Myron D; Lima, Joao A C; Mackey, Rachel H; Neaton, James D; Sanchez, Otto A; Jacobs, David R

    2015-01-01

    Background High-density lipoprotein (HDL) particles have properties beyond reverse cholesterol transport. We hypothesized that their protection extends to inflammation-related disease. The predictive value of HDL particle subclasses and inflammatory markers was studied for noncardiovascular, noncancer chronic inflammation–related death and hospitalization, and for incident cardiovascular disease (CVD). Methods and Results A multiethnic, multicenter, prospective observational study was conducted in 6475 men and women (aged 45 to 84 years) free of known CVD at baseline with median follow-up of 10.1 years. Fasting venous samples were analyzed for baseline lipid profile and lipoprotein particles. We focused on the HDL family of variables (small-, medium-, and large-diameter HDL particles and HDL cholesterol). Analyses identified the sum of small- plus medium-diameter HDL particles as important. Small- plus medium-diameter HDL particles were inversely associated with diagnostic code–based noncardiovascular, noncancer chronic inflammation–related death and hospitalization (n=1054) independent of covariates: relative risk per SD 0.85 (95% CI: 0.79 to 0.91, P<0.0001). Small- plus medium-diameter HDL particles were also associated with adjudicated fatal and nonfatal coronary heart disease events (n=423): relative risk per SD 0.88 (95% CI 0.77 to 0.98, P=0.02). Conclusions Small- plus medium-diameter HDL particles are an independent predictor for noncardiovascular, noncancer chronic inflammation–related death and hospitalization and for coronary heart disease events in subjects initially free of overt CVD. These findings support the hypothesis that smaller HDL particles of diameter <9.4 nm have anti-inflammatory properties in the general population. PMID:26370448

  7. Lipoprotein subclasses and coronary artery calcium in postmenopausal women from the healthy women study.

    PubMed

    Mackey, Rachel H; Kuller, Lewis H; Sutton-Tyrrell, Kim; Evans, Rhobert W; Holubkov, Richard; Matthews, Karen A

    2002-10-17

    Lipoprotein subclass levels may improve the prediction of cardiovascular disease (CAD) in individuals beyond the risk assessment provided by conventional enzymatically determined lipid levels. The objective of this study was to evaluate the associations between nuclear magnetic resonance (NMR) spectroscopy-determined lipoprotein subclasses and coronary calcification in postmenopausal women, and to determine whether the associations were independent of conventional lipid measures. Coronary artery calcification (CAC) was measured by electron beam computed tomography, and lipoprotein subclasses were determined by NMR spectroscopy (Liposcience, Inc., Raleigh, NC), in 286 healthy women (mean age = 61.7), at 8 years postmenopause. CAC was analyzed as categories 0, 1 to 99, and > or =100. The mean CAC was 53 (range, 0 to 1,175), and 54% of the women had 0 scores. Large high-density lipoprotein (HDL) was inversely associated with CAC category, but small HDL was not. All very low-density lipoprotein (VLDL) subclasses-small, medium, and large-were positively associated with CAC (p <0.01). Small low-density lipoprotein (LDL) was positively associated with CAC (p <0.01), but medium and large LDL were not. Smaller LDL particle size (p <0.01) and higher levels of LDL particles (p <0.001) were associated with higher CAC category. In separate ordinal logistic regression models, small LDL, LDL particles, and large VLDL were each positively associated (p <0.05) with higher CAC after adjustment for age, systolic blood pressure (SBP), current smoking, and conventional measures of LDL cholesterol, HDL cholesterol, and triglycerides. These results suggest that the measurement of lipoprotein subclasses may improve the prediction of CAD in postmenopausal women beyond that provided by the conventional lipid panel and CAD risk factors. PMID:12419483

  8. Lipoprotein subclasses and endogenous sex hormones in women at midlife

    PubMed Central

    El Khoudary, Samar R.; Brooks, Maria M.; Thurston, Rebecca C.; Matthews, Karen A.

    2014-01-01

    The objective of this work was to evaluate the associations between levels of endogenous sex hormones in women at midlife and lipoprotein subclasses. One hundred and twenty women (68 late peri-/postmenopausal and 52 pre-/early perimenopausal) from the Study of Women’s Health Across the Nation (Pittsburgh site) were included. Lipoprotein subclasses were quantified using NMR spectroscopy. Participants (57.5% White and 42.5% Black) were 50.4 ± 1.9 years old. Adjusting for age, race, cycle day of blood draw, BMI, physical activity, and alcohol consumption, a negative correlation was found between estradiol (E2) and medium-small LDL particle (LDL-P) concentration (ρ = −0.19, P = 0.04). Further, E2 was positively correlated with HDL particle (HDL-P) size (ρ = 0.22, P = 0.02). For sex hormone binding globulin (SHBG), independent negative correlation was found with total small LDL-P concentration. SHBG was also positively correlated with LDL-P and HDL-P sizes (P < 0.05 for all). For free androgen index (FAI), positive correlations were found with concentrations of total VLDL particles, total LDL-Ps, and total small LDL-Ps. Additionally, FAI was negatively correlated with large HDL-P concentration, and HDL-P and LDL-P sizes (P < 0.05 for all). Lower levels of E2 and SHBG, and higher levels of FAI were associated with a more atherogenic profile of lipoprotein subclasses. Sex hormone levels at midlife may increase women’s risk of coronary heart disease. PMID:24852168

  9. Expression of human apolipoprotein A-I in transgenic mice results in reduced plasma levels of murine apolipoprotein A-I and the appearance of two new high density lipoprotein size subclasses

    SciTech Connect

    Rubin, E.M.; Ishida, B.Y.; Clift, S.M.; Krauss, R.M. )

    1991-01-15

    In Western societies high density lipoprotein (HDL) levels correlate inversely with the risk for coronary heart disease. The primary protein component of both human and mouse HDL is apolipoprotein A-I (apoAI), which comprises {gt}70% of HDL protein and 30% of HDL mass. Human HDLs include particles of several distinct size subpopulations, wheras HDLs from inbred C57BL/6 mice contain a single population of particles. To study the regulation of apoAI expression and its role in HDL assembly, we created transgenic C57BL/6 mice containing the human apoAI gene. Two independent lines of transgenic mice with approximately twice the normal plasma levels of total apoAI were studied. The level of mouse apoAI is reduced {gt}4-fold in both transgenic lines, comprising only 4% of total plasma apoAI levels in one transgenic line and 13% in the other. The authors demonstrate that the mechanism responsible for the decrease in mouse apoAI is posttranscriptional. Parallel to the replacement of mouse with human apoAI, the single HDL species normally present in the plasma of C57BL/6 is replaced by two HDL subclasses similar in size to human HDL{sub 2b} and HDL{sub 3a}. The changes in murine apolipoprotein levels and HDL subclass size are inherited by all transgenic offspring of the two founder animals. These results suggest a dominant role of apoAI in determining the HDL particle size distribution and a mechanism involving expression of human apoAI transgenes that alters the plasma levels of mouse apoAI.

  10. Particle Numbers of Lipoprotein Subclasses and Arterial Stiffness among Middle-aged men from the ERA JUMP study

    PubMed Central

    Vishnu, Abhishek; Choo, Jina; Masaki, Kamal H.; Mackey, Rachel H.; Barinas-Mitchell, Emma; Shin, Chol; Willcox, Bradley J.; El-Saed, Aiman; Seto, Todd B.; Fujiyoshi, Akira; Miura, Katsuyuki; Lee, Sunghee; Sutton-Tyrrell, Kim; Kuller, Lewis H.; Ueshima, Hirotsugu; Sekikawa, Akira

    2013-01-01

    We examined the association between serum lipoprotein subclasses and the three measures of arterial stiffness i.e. (i) carotid-femoral pulse wave velocity (cfPWV) which is a gold standard measure of central arterial stiffness, (ii) brachial-ankle PWV (baPWV) which is emerging as a combined measure of central and peripheral arterial stiffness, and (iii) femoral-ankle PWV (faPWV) which is a measure of peripheral arterial stiffness. Among a population-based sample of 701 apparently healthy Caucasian, Japanese American and Korean men aged 40–49 years, concentrations of lipoprotein particles were assessed by nuclear magnetic resonance (NMR) spectroscopy, and PWV was assessed with an automated waveform analyzer (VP2000, Omron, Japan). Multiple linear regressions were performed to analyze the association between each NMR lipoprotein subclasses and PWV measures, after adjusting for cardiovascular risk factors and other confounders. A cut-off of p<0.01 was used for determining significance. All PWV measures had significant correlations with total and small low-density lipoprotein particle number (LDL-P) (all p<0.0001) but not LDL-cholesterol (LDL-C) (all p>0.1), independent of race and age. In multivariate regression analysis, no NMR lipoprotein subclass was significantly associated with cfPWV (all p>0.01). However, most NMR lipoprotein subclasses had significant associations with both baPWV and faPWV (p<0.01). In this study of healthy middle-aged men, as compared to cfPWV, both baPWV and faPWV had stronger associations with particle numbers of lipoprotein subclasses. Our results may suggest that both baPWV and faPWV are related to arterial stiffness and atherosclerosis, whereas cfPWV may represent arterial stiffness alone. PMID:23823580

  11. [Low density lipoprotein apheresis].

    PubMed

    Zaliūnas, Remigijus; Slapikas, Rimvydas; Gustiene, Olivija; Siurkus, Jonas; Vaitkus, Eduardas

    2003-01-01

    Increased blood cholesterol concentration is one of the main factors in ischemic heart disease, development of which is determined by atherosclerotic changes in coronary vessels. Diet and treatment with 3-hydroxi-3-metilglutaril coenzyme A (HMG-CoA) reductase inhibitors helps to reduce low density lipoprotein cholesterol (LDL-Ch) blood concentration up to recommended level of 3.0 mmol/l in most patients but in some patients particularly with familial dyslipidemias cholesterol concentration remains increased even after treatment with maximal doses of lipid-regulating agents or their combinations. The most frequently used mechanical methods of cholesterol removal from blood include the procedures of extracorporeal apheresis. Low density lipoprotein (LDL) apheresis not only significantly reduces the blood concentrations of total cholesterol (TCh), and LDL-Ch, lipoprotein (a) (Lp(a) and fibrinogen but also stops the progression of atherosclerosis in coronary vessels. PMID:14704503

  12. Association of Height and Pubertal Timing with Lipoprotein Subclass Profile: Exploring the Role of Genetic and Environmental Effects

    PubMed Central

    Jelenkovic, Aline; Bogl, Leonie H.; Rose, Richard J.; Kangas, Antti J.; Soininen, Pasi; Ala-Korpela, Mika; Kaprio, Jaakko; Silventoinen, Karri

    2016-01-01

    Objectives Little is known about the relationship between growth and lipoprotein profile. We aimed to analyze common genetic and environmental factors in the association of height from late childhood to adulthood and pubertal timing with serum lipid and lipoprotein subclass profile. Methods A longitudinal cohort of Finnish twin pairs (FinnTwin12) was analyzed using self-reported height at 11–12, 14, 17 years and measured stature at adult age (21–24 years). Data were available for 719 individual twins including 298 complete pairs. Serum lipids and lipoprotein subclasses were measured by proton nuclear magnetic resonance spectroscopy. Multivariate variance component models for twin data were fitted. Cholesky decomposition was used to partition the phenotypic covariation among traits into additive genetic and unique environmental correlations. Results In men, the strongest associations for both adult height and puberty were observed with total cholesterol, low-density lipoprotein cholesterol, intermediate-density lipoprotein cholesterol, and low-density lipoprotein particle subclasses (max. r = −0.19). In women, the magnitude of the correlations was weaker (max. r = −0.13). Few associations were detected between height during adolescence and adult lipid profile. Early onset of puberty was related to an adverse lipid profile, but delayed pubertal development in girls was associated with an unfavorable profile, as well. All associations were mediated mainly by additive genetic factors, but unique environmental effects cannot be disregarded. Conclusions Early puberty and shorter adult height relate to higher concentrations of atherogenic lipids and lipoprotein particles in early adulthood. Common genetic effects behind these phenotypes substantially contribute to the observed associations. PMID:23649903

  13. Hypertriglyceridemia and unusual lipoprotein subclass distributions associated with late pregnancy

    SciTech Connect

    Forte, T.M.; Kretchmer, N.; Silliman, K. )

    1991-03-15

    In the human adult population elevated plasma triglyceride (TG) levels are associated with decreased high density lipoprotein-cholesterol (HDL-C) levels and decreased HDL and LDL particle sizes. Late pregnancy is a hypertriglyceridemic state where little is known about LDL and HDL subpopulation distribution. Plasma lipids, apolipoproteins (apo) and lipoprotein subpopulations were examined in 36 pregnant women at 36 wk pregnancy and 6 wk postpartum and correlated with HDL and LDL size. There was a significant decrease in LDL diameter at 36 wk pre, 25 {plus minus} 0.7 nm compared, with 6 wk post, 26.4 {plus minus} 0.8 nm. A total of 97% of the 36 wk pre subjects had small dense LDL which paralleled increases in apoB concentration. Unlike LDL HDL at 36 wks pre showed a significant increase in larger sized particles where HDL{sub 2b} predominated. There was a positive correlation between HDL{sub 2b} mass and apoAl and HDL-C concentrations. Late pregnancy is a metabolic state where the predominance of large, HDL{sub 2b} particles is discordant with the predominance of small LDL and elevated TG. This annual metabolic pattern may in part be due to hormonal changes occurring in late pregnancy.

  14. Lipoprotein subclasses in genetic studies: The Berkeley Data Set

    SciTech Connect

    Krauss, R.M.; Williams, P.T.; Blanche, P.J.; Cavanaugh, A.; Holl, L.G.; Austin, M.A.

    1992-10-01

    Data from the Berkeley Data Set was used to investigate familial correlations of HDL-subclasses. Analysis of the sibling intraclass correlation coefficient by HDL particle diameter showed that sibling HDL levels were significantly correlated for HDL{sub 2b}, HDL{sub 3a} and HDL{sub 3b} subclasses. The percentage of the offsprings` variance explained by their two parents. Our finding that parents and offspring-have the highest correlation for HDL{sub 2b} is consistent with published reports that show higher heritability estimates for HDL{sub 2} compared with HDL{sub 3}{minus} cholesterol.

  15. HDL cholesterol subclasses, myocardial infarction, and mortality in secondary prevention: the lipoprotein investigators collaborative

    PubMed Central

    Martin, Seth S.; Khokhar, Arif A.; May, Heidi T.; Kulkarni, Krishnaji R.; Blaha, Michael J.; Joshi, Parag H.; Toth, Peter P.; Muhlestein, Joseph B.; Anderson, Jeffrey L.; Knight, Stacey; Li, Yan; Spertus, John A.; Jones, Steven R.

    2015-01-01

    Aims High-density lipoprotein (HDL) is highly heterogeneous and the link of its subclasses to prognosis remains controversial. We aimed to rigorously examine the associations of HDL subclasses with prognosis in secondary prevention. Methods and results We collaboratively analysed data from two, complementary prospective cohorts: the TRIUMPH study of 2465 acute myocardial infarction patients, and the IHCS study of 2414 patients who underwent coronary angiography. All patients had baseline HDL subclassification by vertical-spin density gradient ultracentrifugation. Given non-linearity, we stratified by tertiles of HDL-C and its two major subclasses (HDL2-C, HDL3-C), then compared multivariable-adjusted hazard ratios for mortality and mortality/myocardial infarction. Patients were middle-aged to elderly (TRIUMPH: 58.2 ± 12.2 years; IHCS: 62.6 ± 12.6 years), and the majority were men (TRIUMPH: 68.0%; IHCS: 65.5%). IHCS had lower mean HDL-C levels (34.6 ± 10.1 mg/dL) compared with TRIUMPH (40 ± 10.6 mg/dL). HDL3-C accounted for >3/4 of HDL-C (mean HDL3-C/HDL-C 0.78 ± 0.05 in both cohorts). During 2 years of follow-up in TRIUMPH, 226 (9.2%) deaths occurred, while death/myocardial infarction occurred in 401 (16.6%) IHCS patients over 5 years. No independent associations with outcomes were observed for HDL-C or HDL2-C. In contrast, the lowest tertile of HDL3-C was independently associated with >50% higher risk in each cohort (TRIUMPH: with middle tertile as reference, fully adjusted HR for mortality of HDL3-C, 1.57; 95% CI, 1.13–2.18; IHCS: fully adjusted HR for mortality/myocardial infarction, 1.55; 95% CI, 1.20–2.00). Conclusion In secondary prevention, increased risk for long-term hard clinical events is associated with low HDL3-C, but not HDL2-C or HDL-C, highlighting the potential value of subclassifying HDL-C. PMID:24980493

  16. Apo E-containing lipoproteins in low or high density lipoprotein deficiency.

    PubMed

    Gibson, J C; Rubinstein, A; Brown, W V; Ginsberg, H N; Greten, H; Norum, R; Kayden, H

    1985-01-01

    Apolipoprotein (apo) E-containing subfractions of very low density lipoprotein (VLDL), intermediate density lipoprotein (IDL), and high density lipoprotein (HDL) have been described in normolipidemic and hyperlipidemic subjects. These lipoproteins exist, however, in the presence of large amounts of apo A-I- and apo B-containing lipoproteins so that it has been difficult to assess the independence of these apo E-containing subclasses from the major lipoprotein classes. The present study has approached this question by taking advantage of three hypolipidemic states in which one or more of the major apolipoproteins is deficient or absent. After separating lipoproteins from whole plasma by molecular sieve chromatography followed by radioimmunoassay of column fractions, we found that two subjects with abetalipoproteinemia had no apo E-containing lipoproteins the size of VLDL or IDL and all the plasma apo E was in a fraction of large HDL. Two subjects with Tangier disease and two with familial apo A-I/C-III deficiency had extremely low levels of HDL cholesterol and of apo A-I-containing lipoproteins. In spite of the absence of classical HDL, a major fraction of apo E-containing lipoproteins was reproducibly observed at the elution volume characteristic of large HDL and was identical to that found in normal subjects. These data thus suggest the existence of apo E-containing lipoproteins that are the size of HDL and are not dependent upon the presence of either apo B or apo A-I. While studies in normal subjects indicate that apo E is associated with other apolipoproteins in HDL, further investigations will be needed to determine the full composition of these apo E-containing lipoproteins in the lipoprotein-deficient patients described in this report. PMID:3925935

  17. Associations between intensive diabetes therapy and NMR-determined lipoprotein subclass profiles in type 1 diabetes.

    PubMed

    Zhang, Ying; Jenkins, Alicia J; Basu, Arpita; Stoner, Julie A; Lopes-Virella, Maria F; Klein, Richard L; Lyons, Timothy J

    2016-02-01

    Our objective is to define differences in circulating lipoprotein subclasses between intensive versus conventional management of type 1 diabetes during the randomization phase of the Diabetes Control and Complications Trial (DCCT). NMR-determined lipoprotein subclass profiles (NMR-LSPs), which estimate molar subclass concentrations and mean particle diameters, were determined in 1,294 DCCT subjects after a median of 5 years (interquartile range: 4-6 years) of randomization to intensive or conventional diabetes management. In cross-sectional analyses, we compared standard lipids and NMR-LSPs between treatment groups. Standard total, LDL, and HDL cholesterol levels were similar between randomization groups, while triglyceride levels were lower in the intensively treated group. NMR-LSPs showed that intensive therapy was associated with larger LDL diameter (20.7 vs. 20.6 nm, P = 0.01) and lower levels of small LDL (median: 465 vs. 552 nmol/l, P = 0.007), total IDL/LDL (mean: 1,000 vs. 1,053 nmol/l, P = 0.01), and small HDL (mean: 17.3 vs. 18.6 μmol/l, P < 0.0001), the latter accounting for reduced total HDL (mean: 33.8 vs. 34.8 μmol/l, P = 0.01). In conclusion, intensive diabetes therapy was associated with potentially favorable changes in LDL and HDL subclasses in sera. Further research will determine whether these changes contribute to the beneficial effects of intensive diabetes management on vascular complications. PMID:26658239

  18. Oxidized Low-Density Lipoprotein

    PubMed Central

    Parthasarathy, Sampath; Raghavamenon, Achuthan; Garelnabi, Mahdi Omar; Santanam, Nalini

    2012-01-01

    Oxidized low-density lipoprotein (Ox-LDL) has been studied for over 25 years. Numerous pro- and anti-atherogenic properties have been attributed to Ox-LDL. Yet, Ox-LDL has neither been defined nor characterized, as its components and composition change depending on its source, method of preparation, storage, and use. It contains unoxidized and oxidized fatty acid derivatives both in the ester and free forms, their decomposition products, cholesterol and its oxidized products, proteins with oxidized amino acids and cross-links, and polypeptides with varying extents of covalent modification with lipid oxidation products, and many others. It seems to exist in vivo in some form not yet fully characterized. Until its pathophysiological significance, and how it is generated in vivo are determined, the nature of its true identity will be only of classical interest. In this review, its components, their biological actions and methods of preparation will be discussed. PMID:20013192

  19. High-density lipoproteins delivering interleukin-15.

    PubMed

    Ochoa, Maria C; Melero, Ignacio; Berraondo, Pedro

    2013-04-01

    Circulating lipoproteins may offer interesting properties as therapeutic carriers for cytokines and hormones, in terms of both stability and bio-distribution. The fusion of apolipoprotein A-I with interleukin-15 (IL-15) targets the latter to high-density lipoproteins (HDLs). The bioactivity of this chimera can be further enhanced by creating triple fusions with IL-15 receptor α domain involved in IL-15 trans-presentation. PMID:23734302

  20. Low-Density Lipoprotein Apheresis

    PubMed Central

    2007-01-01

    Executive Summary Objective To assess the effectiveness and safety of low-density lipoprotein (LDL) apheresis performed with the heparin-induced extracorporeal LDL precipitation (HELP) system for the treatment of patients with refractory homozygous (HMZ) and heterozygous (HTZ) familial hypercholesterolemia (FH). Background on Familial Hypercholesterolemia Familial hypercholesterolemia is a genetic autosomal dominant disorder that is caused by several mutations in the LDL-receptor gene. The reduced number or absence of functional LDL receptors results in impaired hepatic clearance of circulating low-density lipoprotein cholesterol (LDL-C) particles, which results in extremely high levels of LDL-C in the bloodstream. Familial hypercholesterolemia is characterized by excess LDL-C deposits in tendons and arterial walls, early onset of atherosclerotic disease, and premature cardiac death. Familial hypercholesterolemia occurs in both HTZ and HMZ forms. Heterozygous FH is one of the most common monogenic metabolic disorders in the general population, occurring in approximately 1 in 500 individuals1. Nevertheless, HTZ FH is largely undiagnosed and an accurate diagnosis occurs in only about 15% of affected patients in Canada. Thus, it is estimated that there are approximately 3,800 diagnosed and 21,680 undiagnosed cases of HTZ FH in Ontario. In HTZ FH patients, half of the LDL receptors do not work properly or are absent, resulting in plasma LDL-C levels 2- to 3-fold higher than normal (range 7-15mmol/L or 300-500mg/dL). Most HTZ FH patients are not diagnosed until middle age when either they or one of their siblings present with symptomatic coronary artery disease (CAD). Without lipid-lowering treatment, 50% of males die before the age of 50 and 25% of females die before the age of 60, from myocardial infarction or sudden death. In contrast to the HTZ form, HMZ FH is rare (occurring in 1 case per million persons) and more severe, with a 6- to 8-fold elevation in plasma LDL-C levels (range 15-25mmol/L or 500-1000mg/dL). Homozygous FH patients are typically diagnosed in infancy, usually due to the presence of cholesterol deposits in the skin and tendons. The main complication of HMZ FH is supravalvular aortic stenosis, which is caused by cholesterol deposits on the aortic valve and in the ascending aorta. The average life expectancy of affected individuals is 23 to 25 years. In Ontario, it is estimated that there are 13 to 15 cases of HMZ FH. An Ontario clinical expert confirmed that 9 HMZ FH patients have been identified to date. Diagnosis There are 2 accepted clinical diagnostic criterion for the diagnosis of FH: the Simon Broome FH Register criteria from the United Kingdom and the Dutch Lipid Network criteria from the Netherlands. The criterion supplement cholesterol levels with clinical history, physical signs and family history. DNA-based-mutation-screening methods permit a definitive diagnosis of HTZ FH to be made. However, given that there are over 1000 identified mutations in the LDL receptor gene and that the detection rates of current techniques are low, genetic testing becomes problematic in countries with high genetic heterogeneity, such as Canada. Treatment The primary aim of treatment in both HTZ and HMZ FH is to reduce plasma LDL-C levels in order to reduce the risk of developing atherosclerosis and CAD. The first line of treatment is dietary intervention, however it alone is rarely sufficient for the treatment of FH patients. Patients are frequently treated with lipid-lowering drugs such as resins, fibrates, niacin, statins and cholesterol absorption-inhibiting drugs (ezetimibe). Most HTZ FH patients require a combination of drugs to achieve or approach target cholesterol levels. A small number of HTZ FH patients are refractory to treatment or intolerant to lipid-lowering medication. According to clinical experts, the prevalence of refractory HTZ FH in Ontario is between 1 to 5%. Using the mean of 3%, it is estimated that there are approximately 765 refractory HTZ FH patients in Ontario, of which 115 are diagnosed and 650 are undiagnosed. Drug therapy is less effective in HMZ FH patients since the effects of the majority of cholesterol-lowering drugs are mediated by the upregulation of LDL receptors, which are often absent or function poorly in HMZ FH patients. Some HMZ FH patients may still benefit from drug therapy, however this rarely reduces LDL-C levels to targeted levels. Existing Technology: Plasma Exchange An option currently available in Ontario for FH patients who do not respond to standard diet and drug therapy is plasma exchange (PE). Patients are treated with this lifelong therapy on a weekly or biweekly basis with concomitant drug therapy. Plasma exchange is nonspecific and eliminates virtually all plasma proteins such as albumin, immunoglobulins, coagulation factors, fibrinolytic factors and HDL-C, in addition to acutely lowering LDL-C by about 50%. Blood is removed from the patient, plasma is isolated, discarded and replaced with a substitution fluid. The substitution fluid and the remaining cellular components of the blood are then returned to the patient. The major limitation of PE is its nonspecificity. The removal of HDL-C prevents successful vascular remodeling of the areas stenosed by atherosclerosis. In addition, there is an increased susceptibility to infections, and costs are incurred by the need for replacement fluid. Adverse events can be expected to occur in 12% of procedures. Other Alternatives Surgical alternatives for FH patients include portocaval shunt, ileal bypass and liver transplantation. However, these are risky procedures and are associated with a high morbidity rate. Results with gene therapy are not convincing to date. The Technology Being Reviewed: LDL Apheresis An alternative to PE is LDL apheresis. Unlike PE, LDL apheresis is a selective treatment that removes LDL-C and other atherogenic lipoproteins from the blood while minimally impacting other plasma components such as HDL-C, total serum protein, albumin and immunoglobulins. As with PE, FH patients require lifelong therapy with LDL apheresis on a weekly/biweekly basis with concomitant drug therapy. Heparin-Induced Extracorporeal LDL Precipitation Heparin-induced extracorporeal LDL precipitation (HELP) is one of the most widely used methods of LDL apheresis. It is a continuous closed-loop system that processes blood extracorporeally. It operates on the principle that at a low pH, LDL and lipoprotein (a) [Lp(a)] bind to heparin and fibrinogen to form a precipitate which is then removed by filtration. In general, the total duration of treatment is approximately 2 to 3 hours. Results from early trials indicate that LDL-C concentration is reduced by 65% to 70% immediately following treatment in both HMZ and HTZ FH and then rapidly begins to rise. Typically patients with HTZ FH are treated every 2 weeks while patients with HMZ FH require weekly therapy. Heparin-induced extracorporeal LDL precipitation also produces small transient decreases in HDL-C, however levels generally return to baseline within 2 days. After several months of therapy, long-term reductions in LDL-C and increases in HDL-C have been reported. In addition to having an impact on plasma cholesterol concentrations, HELP lowers plasma fibrinogen, a risk factor for atherosclerosis, and reduces concentrations of cellular adhesion molecules, which play a role in early atherogenesis. In comparison with PE, HELP LDL apheresis does not have major effects on essential plasma proteins and does not require replacement fluid, thus decreasing susceptibility to infections. One study noted that adverse events were documented in 2.9% of LDL apheresis treatments using the HELP system compared with 12% using PE. As per the manufacturer, patients must weigh at least 30kgs to be eligible for treatment with HELP. Regulatory Status The H.E.L.P.® System (B.Braun Medizintechnologie GmbH, Germany) has been licensed by Health Canada since December 2000 as a Class 3 medical device (Licence # 26023) for performing LDL apheresis to acutely remove LDL from the plasma of 3 high-risk patient populations for whom diet has been ineffective and maximum drug therapy has either been ineffective or not tolerated. The 3 patient groups are as follows: Functional hypercholesterolemic homozygotes with LDL-C >500 mg/dL (>13mmol/L); Functional hypercholesterolemic heterozygotes with LDL-C >300 mg/dL (>7.8mmol/L); Functional hypercholesterolemic heterozygotes with LDL-C >200 mg/dL (>5.2mmol/L) and documented CAD No other LDL apheresis system is currently licensed in Canada. Review Strategy The Medical Advisory Secretariat systematically reviewed the literature to assess the effectiveness and safety of LDL apheresis performed with the HELP system for the treatment of patients with refractory HMZ and HTZ FH. A standard search methodology was used to retrieve international health technology assessments and English-language journal articles from selected databases. The GRADE approach was used to systematically and explicitly make judgments about the quality of evidence and strength of recommendations. Summary of Findings The search identified 398 articles published from January 1, 1998 to May 30, 2007. Eight studies met the inclusion criteria. Five case series, 2 case series nested within comparative studies, and one retrospective review, were included in the analysis. A health technology assessment conducted by the Alberta Heritage Foundation for Medical Research, and a review by the United States Food and Drug Administration were also included. Large heterogeneity among the studies was observed. Studies varied in inclusion criteria, baseline patient characteristics and methodology. Overall, the mean acute1 relative decrease in LDL-C with HELP LDL apheresis ranged from 53 to 77%. The mean acute relative reductions ranged as follows: total cholesterol (TC) 47 to 64%, HDL-C +0.4 to -29%, triglycerides (TG) 33 to 62%, Lp(a) 55 to 68% and fibrinogen 56 to 65%. The mean chronic2 relative decreases in LDL-C and TC with HELP LDL apheresis ranged from 9 to 46% and 5 to 34%, respectively. Familial hypercholesterolemia patients treated with HELP did not achieve the target LDL-C value set by international guidelines (LDL-C < 2.5mmol/L, 100mg/dL). The chronic mean relative increase in HDL-C ranged from 12 to 27%. The ratio of LDL:HDL and the ratio of TC:HDL are 2 measures that have been shown to be important risk factors for cardiac events. In high-risk patients, the recommended target LDL:HDL ratio is less than or equal to 2, and the target TC:HDL ratio is less than 4. In the studies that reported chronic lipid changes, the LDL:HDL and TC:HDL ratios exceeded targeted values. Three studies investigated the effects of HELP on coronary outcomes and atherosclerotic changes. One noted that twice as many lesions displayed regression in comparison to those displaying progression. The second study found that there was a decrease in Agatston scores3 and in the volume of coronary calcium. The last study noted that 2 of 5 patients showed regression of coronary atherosclerosis, and 3 of the 5 patients showed no change as assessed by a global change score. Adverse effects were typically mild and transient, and the majority of events were related to problems with vascular access. Of the 3 studies that provided quantitative information, the proportion of adverse events ranged from 2.9 to 5.1%. GRADE Quality of Evidence In general, studies were of low quality, i.e., case series studies (Tables 1-3). No controlled studies were identified and no studies directly compared the effectiveness of the HELP system with PE or with diet and drug therapy. Conducting trials with a sufficiently large control group would not have been feasible or acceptable given that HELP represents a last alternative in these patients who are resistant to conventional therapeutic strategies. A major limitation is that there is limited evidence on the effectiveness and safety of HELP apheresis in HMZ FH patients. However, it is unlikely that better-quality evidence will become available, given that HMZ FH is rare and LDL apheresis is a last therapeutic option for these patients. Lastly, there is limited data on the long-term effects of LDL apheresis in FH patients. No studies with HELP were identified that examined long-term outcomes such as survival and cardiovascular events. The absence of this data may be attributed to the rarity of the condition, and the large number of subjects and long duration of follow-up that would be needed to conduct such trials. Table 1: Homozygous Familial Hypercholesterolemia - Lipid Outcomes Number ofStudies Study Design Quality of Studies Consistency Directness OtherModifyingFactors OverallQuality of Evidence 1 Case series=Low Low + Yes Sparse data Very low 1 Retrospective review=Low Table 2: Heterozygous Familial Hypercholesterolemia - Lipid Outcomes Number ofStudies Study Design Quality of Studies Consistency Directness Other Modifying Factors Overall Quality of Evidence 7+FDA Case series=Low Low + Yes Not applicable Low 1 Retrospective review=Low Table 3: Heterozygous Familial Hypercholesterolemia - Coronary Artery Disease Outcomes Number ofStudies Study Design Quality of Studies Consistency Directness Other Modifying Factors Overall Quality of Evidence 2+FDA Case series=Low Low + Yes Not applicable Low 1 Retrospective review=Low Economic Analysis A budget-impact analysis was conducted to forecast future costs for PE and HELP apheresis in FH patients. All costs are reported in Canadian dollars. Based on epidemiological data of 13 HMZ, 115 diagnosed HTZ and 765 cases of all HTZ patients (diagnosed + undiagnosed), the annual cost of weekly treatment was estimated to be $488,025, $4,332,227 and $24,758,556 respectively for PE. For HELP apheresis, the annual cost of weekly treatment was estimated to be $1,025,338, $9,156,209 and $60,982,579 respectively. Costs for PE and HELP apheresis were halved with a biweekly treatment schedule. The cost per coronary artery disease death avoided over a 10-year period in HTZ FH-diagnosed patients was also calculated and estimated to be $37.5 million and $18.7 million for weekly and biweekly treatment respectively, when comparing HELP apheresis with PE and with no intervention. Although HELP apheresis costs twice as much as PE, it helped to avoid 12 deaths compared with PE and 22 deaths compared with no intervention, over a period of 10 years. Ontario Health System Impact Analysis Low-density lipoprotein apheresis using the HELP system is currently being funded by the provinces of Quebec and Alberta. The program in Quebec has been in operation since 2001 and is limited to the treatment of HMZ FH patients. The Alberta program is relatively new and is currently treating HMZ FH patients, but it is expanding to include refractory HTZ FH patients. Low-density lipoprotein apheresis is a lifelong treatment and requires considerable commitment on the part of the patient, and the patient’s family and physician. In addition, the management of FH continues to evolve. With the advent of new more powerful cholesterol-lowering drugs, some HTZ patients may be able to sufficiently control their hypercholesterolemia. Nevertheless, according to clinical experts, HMZ patients will likely always require LDL apheresis. Given the substantial costs associated with LDL apheresis, treatment has been limited to HMZ FH patients. However, LDL apheresis could be applied to a much larger population, which would include HTZ FH patients who are refractory to diet and drug therapy. HTZ FH patients are generally recruited in a more advanced state, demonstrate a longer natural survival than HMZ FH patients and are older. Conclusions For HMZ FH patients, the benefits of LDL apheresis clearly outweigh the risks and burdens. According to GRADE, the recommendation would be graded as strong, with low- to very low-quality evidence (Table 4). In both HMZ and HTZ FH patients, there is evidence of overall clinical benefit of LDL apheresis from case series studies. Low-density lipoprotein apheresis has several advantages over the current treatment of PE, including decreased exposure to blood products, decreased risk of adverse events, conservation of nonatherogenic and athero-protective components, such as HDL-C and lowering of other atherogenic components, such as fibrinogen. In contrast to HMZ FH patients, there remains a lot of uncertainty in the social/ethical acceptance of this technology for the treatment of refractory HTZ FH patients. In addition to the substantial costs, it is unknown whether the current health care system could cope with the additional demand. There is uncertainty in the estimates of benefits, risks and burdens. According to GRADE, the recommendation would be graded as weak with low- to very-low-quality evidence (Table 5). Table 4: GRADE Recommendation - Homozygous Patients Benefits Risks Burdens Overall clinical benefit     Consistency with social/ethical values     Affordable     Health system feasibility     GRADE of recommendation: Strong recommendation, low-quality or very-low-quality evidence Benefits clearly outweigh risk and burdens Case series study designs Strong, but may change when higher-quality evidence becomes available Table 5: GRADE Recommendation - Heterozygous Patients Benefits Risks Burdens Overall clinical benefit   Less affordable     Questionable health system feasibility     Unknown if consistent with social/ethical values GRADE of recommendation: Weak recommendation, low-quality or very-low-quality evidence Uncertainty in the estimates of benefits, risks and burden, which these may be closely balanced Case series study designs Very weak; other alternatives may be equally reasonable PMID:23074505

  1. Six new loci associated with blood low-density lipoprotein cholesterol, high-density lipoprotein cholesterol or triglycerides in humans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol are risk factors for cardiovascular disease and blood triglycerides reflect key metabolic processes including sensitivity to insulin. Blood lipoprotein and lipid concentrations are heritable. To date, the identification o...

  2. Alcohol alters low density lipoprotein composition and metabolism

    SciTech Connect

    Hoinacki, J.; Brown, J.; Dawson, M.; Deschenes, R.; Mulligan, J. )

    1991-03-11

    Two separate studies were conducted to examine the effect of ethanol (EtOH) dose on atherogenic low density lipoprotein (LDL) subfractions and LDL metabolism in vivo. In the first study, male, atherosclerosis-susceptible squirrel monkeys were divided in three treatments: controls fed liquid diet, and low and high alcohol groups given liquid diet with vodka substituted for carbohydrate at 12% and 24% of calories, respectively. After 6 months, LDL subclasses (LDL{sub 1a}, LDL{sub 1b} and LDL{sub 2}) were isolated by density gradient ultracentrifugation and polyacrylamide gradient gel electrophoresis, and their lipid and protein composition was determined. Low dose EtOH had no effect on LDL subfraction distribution while 24% EtOH resulted in an increase in the larger (LDL{sub 1a} and LDL{sub 1b}), buoyant subspecies without affecting the level of the more atherogenic, smaller, denser LDL{sub 2} particles. In the second study, {sup 125}I-LDL apolipoprotein B (apo B) was injected intravenously into Control and High EtOH monkeys and kinetic analyses were performed. Although the absolute catabolic rate (LDL production) was not altered, High EtOH primates showed a reduction in the fractional catabolic rate and a longer LDL apoB residence time.

  3. Beginning to understand high-density lipoproteins.

    PubMed

    Santos-Gallego, Carlos G; Badimon, Juan J; Rosenson, Robert S

    2014-12-01

    This article reconciles the classic view of high-density lipoproteins (HDL) associated with low risk for cardiovascular disease (CVD) with recent data (genetics studies and randomized clinical trials) casting doubt over the widely accepted beneficial role of HDL regarding CVD risk. Although HDL cholesterol has been used as a surrogate measure to investigate HDL function, the cholesterol content in HDL particles is not an indicator of the atheroprotective properties of HDL. Thus, more precise measures of HDL metabolism are needed to reflect and account for the beneficial effects of HDL particles. Current and emerging therapies targeting HDL are discussed. PMID:25432389

  4. Speciated High-Density Lipoprotein Biogenesis and Functionality.

    PubMed

    Rosales, C; Davidson, W S; Gillard, B K; Gotto, A M; Pownall, H J

    2016-05-01

    Plasma high-density lipoprotein cholesterol (HDL-C) concentration is a negative risk factor for atherosclerotic cardiovascular disease (CVD). Despite this, most attempts to raise plasma HDL-C concentrations in a cardioprotective way have failed. Recently, hypotheses about the atheroprotective effects of HDL have shifted away from quantity to quality, mostly HDL function in reverse cholesterol transport. Plasma HDL from CVD patients is a poorer acceptor of cellular cholesterol than plasma from healthy controls, independent of plasma HDL-C concentrations. The function of HDL is likely determined by two other factors, stability and composition. The kinetic instability of HDL, which varies according to subclass, is a likely determinant of its reactivity in response to many HDL-modifying activities. HDL composition is also heterogeneous and variable; all HDL particles contain apo AI but only about two-thirds contain apo AII. This occurs despite the fact that apo AI and apo AII are hepatically secreted on separate HDL that later fuse in plasma. HDL also contains traces of other proteins, some of which have not yet been associated with HDL function. One minor HDL species are those that are secreted with intact signal peptides, which enhances their binding to HDL; these HDL have special properties that are independent of cholesterol transport. Here, we review and provide a perspective about what is currently known about speciated HDL biogenesis in the context of health and disease. PMID:27005803

  5. Regulation of high-density lipoprotein metabolism.

    PubMed

    Rye, Kerry-Anne; Barter, Philip J

    2014-01-01

    There is compelling evidence from human population studies that plasma levels of high-density lipoprotein (HDL) cholesterol correlate inversely with cardiovascular risk. Identification of this relationship has stimulated research designed to understand how HDL metabolism is regulated. The ultimate goal of these studies has been to develop HDL-raising therapies that have the potential to decrease the morbidity and mortality associated with atherosclerotic cardiovascular disease. However, the situation has turned out to be much more complex than originally envisaged. This is partly because the HDL fraction consists of multiple subpopulations of particles that vary in terms of shape, size, composition, and surface charge, as well as in their potential cardioprotective properties. This heterogeneity is a consequence of the continual remodeling and interconversion of HDL subpopulations by multiple plasma factors. Evidence that the remodeling of HDLs may impact on their cardioprotective properties is beginning to emerge. This serves to highlight the importance of understanding not only how the remodeling and interconversion of HDL subpopulations is regulated but also how these processes are affected by agents that increase HDL levels. This review provides an overview of what is currently understood about HDL metabolism and how the subpopulation distribution of these lipoproteins is regulated. PMID:24385508

  6. High-density lipoproteins in stroke.

    PubMed

    Meilhac, Olivier

    2015-01-01

    Besides their well-documented function of reverse transport of cholesterol, high-density lipoproteins (HDLs) display pleiotropic effects due to their antioxidant, antithrombotic, anti-inflammatory and antiapoptotic properties that may play a major protective role in acute stroke, in particular by limiting the deleterious effects of ischaemia on the blood-brain barrier (BBB) and on the parenchymal cerebral compartment. HDLs may also modulate leukocyte and platelet activation, which may also represent an important target that would justify the use of HDL-based therapy in acute stroke. In this review, we will present an update of all the recent findings in HDL biology that could support a potential clinical use of HDL therapy in ischaemic stroke. PMID:25523000

  7. Computational Lipidology: Predicting Lipoprotein Density Profiles in Human Blood Plasma

    PubMed Central

    Hbner, Katrin; Schwager, Thomas; Winkler, Karl; Reich, Jens-Georg; Holzhtter, Hermann-Georg

    2008-01-01

    Monitoring cholesterol levels is strongly recommended to identify patients at risk for myocardial infarction. However, clinical markers beyond bad and good cholesterol are needed to precisely predict individual lipid disorders. Our work contributes to this aim by bringing together experiment and theory. We developed a novel computer-based model of the human plasma lipoprotein metabolism in order to simulate the blood lipid levels in high resolution. Instead of focusing on a few conventionally used predefined lipoprotein density classes (LDL, HDL), we consider the entire protein and lipid composition spectrum of individual lipoprotein complexes. Subsequently, their distribution over density (which equals the lipoprotein profile) is calculated. As our main results, we (i) successfully reproduced clinically measured lipoprotein profiles of healthy subjects; (ii) assigned lipoproteins to narrow density classes, named high-resolution density sub-fractions (hrDS), revealing heterogeneous lipoprotein distributions within the major lipoprotein classes; and (iii) present model-based predictions of changes in the lipoprotein distribution elicited by disorders in underlying molecular processes. In its present state, the model offers a platform for many future applications aimed at understanding the reasons for inter-individual variability, identifying new sub-fractions of potential clinical relevance and a patient-oriented diagnosis of the potential molecular causes for individual dyslipidemia. PMID:18497853

  8. Serum n−6 fatty acids and lipoprotein subclasses in middle-aged men: the population-based cross-sectional ERA-JUMP Study123

    PubMed Central

    Ueshima, Hirotsugu; Curb, J David; Shin, Chol; Evans, Rhobert W; El-Saed, Aiman; Kadowaki, Takashi; Okamura, Tomonori; Nakata, Katsumi; Otake, Teruo; Miura, Katsuyuki; Abbott, Robert D; Sutton-Tyrrell, Kim; Edmundowicz, Daniel; Kuller, Lewis H; Sekikawa, Akira

    2010-01-01

    Background: The associations of serum omega-6 (n−6) fatty acids with lipoprotein subclasses at the population level are uncertain. Objective: We aimed to examine associations between major n−6 fatty acids [ie, linoleic acid (LA, 18:2n−6) and arachidonic acid (AA, 20:4n−6)] and the lipoprotein subclasses VLDL, LDL, and HDL. Design: We conducted a cross-sectional study in 1098 participants using population-based data from US white, Japanese American, Japanese, and Korean men aged 40–49 y. Serum fatty acids were analyzed by capillary gas-liquid chromatography. Lipoprotein subclasses were measured by nuclear magnetic resonance spectroscopy. Multiple linear regression models as a function of each fatty acid were used after adjustment for age, population, body mass index, pack-years of smoking, alcohol consumption, diabetes, hypertension, and omega-3 (n−3) and trans fatty acids. Results: Serum LA was inversely associated with large VLDL (β = −0.62, P < 0.001), total LDL (β = −22.08, P < 0.001), and small LDL (β = −31.89, P < 0.001) particle concentrations and VLDL size (β = −0.72, P < 0.001). Serum LA was positively associated with large HDL particle concentration (β = 0.21, P < 0.001) and HDL size (β = 0.03, P < 0.001). The patterns of association of AA with large VLDL and large HDL particle concentrations were comparable with those of LA. Conclusions: At the population level, higher serum concentrations of LA were significantly associated with lower concentrations of total LDL particles. Higher serum concentrations of LA and AA were significantly associated with a lower concentration of large VLDL particles and a higher concentration of large HDL particles. These associations were consistent across the population groups. This trial was registered at clinicaltrials.gov as NCT00069797. PMID:20357040

  9. High-Density Lipoproteins: Nature's Multifunctional Nanoparticles.

    PubMed

    Kuai, Rui; Li, Dan; Chen, Y Eugene; Moon, James J; Schwendeman, Anna

    2016-03-22

    High-density lipoproteins (HDL) are endogenous nanoparticles involved in the transport and metabolism of cholesterol, phospholipids, and triglycerides. HDL is well-known as the "good" cholesterol because it not only removes excess cholesterol from atherosclerotic plaques but also has anti-inflammatory and antioxidative properties, which protect the cardiovascular system. Circulating HDL also transports endogenous proteins, vitamins, hormones, and microRNA to various organs. Compared with other synthetic nanocarriers, such as liposomes, micelles, and inorganic and polymeric nanoparticles, HDL has unique features that allow them to deliver cargo to specific targets more efficiently. These attributes include their ultrasmall size (8-12 nm in diameter), high tolerability in humans (up to 8 g of protein per infusion), long circulating half-life (12-24 h), and intrinsic targeting properties to different recipient cells. Various recombinant ApoA proteins and ApoA mimetic peptides have been recently developed for the preparation of reconstituted HDL that exhibits properties similar to those of endogenous HDL and has a potential for industrial scale-up. In this review, we will summarize (a) clinical pharmacokinetics and safety of reconstituted HDL products, (b) comparison of HDL with inorganic and other organic nanoparticles, PMID:26889958

  10. High-density lipoprotein mimetics: promises and challenges.

    PubMed

    Sviridov, Dmitri; Remaley, Alan T

    2015-12-15

    The concept of lipoprotein mimetics was developed and extensively tested in the last three decades. Most lipoprotein mimetics were designed to recreate one or several functions of high-density lipoprotein (HDL) in the context of cardiovascular disease; however, the application of this approach is much broader. Lipoprotein mimetics should not just be seen as a set of compounds aimed at replenishing a deficiency or dysfunctionality of individual elements of lipoprotein metabolism but rather as a designer concept with remarkable flexibility and numerous applications in medicine and biology. In the present review, we discuss the fundamental design principles used to create lipoprotein mimetics, mechanisms of their action, medical indications and efficacy in animal models and human studies. PMID:26613945

  11. Hemodynamics alter arterial low-density lipoprotein metabolism

    SciTech Connect

    Warty, V.S.; Calvo, W.J.; Berceli, S.A.; Pham, S.M.; Durham, S.J.; Tanksale, S.K.; Klein, E.C.; Herman, I.M.; Borovetz, H.S. )

    1989-10-01

    We have investigated the role of hemodynamic factors on low-density lipoprotein transport and metabolism in the intact arterial wall. Freshly excised canine carotid blood vessels were exposed to well-defined pulsatile flow in vitro for continuous periods up to 20 hours. We chose to impose the following hemodynamic conditions on our test carotid arteries: normotension, hypertension (at physiologic flow conditions), and hypertension coupled with elevated flow of canine serum perfusate. In several experiments the effect of endothelial denudation was examined in carotid arteries exposed to normotensive pulsatile flow. A trapped ligand method was used for quantitating low-density lipoprotein uptake and metabolism in the arterial wall. The distribution of both intact and degraded low-density lipoprotein fractions was determined from measurements of radiolabelled low-density lipoprotein activity within thin radial sections of perfused arteries. Our results suggest that both hypertensive hemodynamic simulations exacerbate the uptake of low-density lipoprotein within the arterial wall (by a factor of three to nine). The percentage of low-density lipoprotein that undergoes irreversible degradation falls from 41% under normotensive conditions to below 30% when hypertensive conditions are imposed, indicating that degradative processes are not proportionally elevated with the accelerated influx. A similar pattern is observed for deendothelialized vessels.

  12. Lipoprotein lipase enhances the binding of chylomicrons to low density lipoprotein receptor-related protein.

    PubMed Central

    Beisiegel, U; Weber, W; Bengtsson-Olivecrona, G

    1991-01-01

    Chylomicron catabolism is known to be initiated by the enzyme lipoprotein lipase (triacylglycero-protein acylhydrolase, EC 3.1.1.34). Chylomicron remnants, produced by lipolysis, are rapidly taken up by the liver via an apolipoprotein E (apoE)-mediated, receptor-dependent process. The low density lipoprotein (LDL) receptor-related protein (LRP) has been suggested as the potential apoE receptor. We have analyzed the binding of human chylomicrons to HepG2 cells in the absence and presence of lipoprotein lipase. Bovine and human lipoprotein lipases were able to increase the specific binding of the chylomicrons by up to 30-fold. This effect was not dependent on lipolysis but appeared to be due to the lipase protein itself. It was not found when a structurally unrelated, bacterial lipase was used. Using beta-migrating very low density lipoproteins (beta-VLDLs), known as a good ligand for LRP, binding studies were performed on LDL receptor-negative human fibroblasts. The binding was increased 40-fold by addition of lipoprotein lipase. Crosslinking experiments on cells with 125I-labeled apoE liposomes or lipoprotein lipase showed that both proteins were able to bind to LRP on the cell surface. The binding of apoE to LRP was highly increased by the addition of lipase. We conclude that lipoprotein lipase strongly enhances the binding of apoE-containing lipoproteins to LRP and therefore might play an important role in chylomicron catabolism not only because of its lipolytic activity but also because of its structural properties. Images PMID:1656440

  13. Suppression of diet-induced atherosclerosis in low density lipoprotein receptor knockout mice overexpressing lipoprotein lipase.

    PubMed Central

    Shimada, M; Ishibashi, S; Inaba, T; Yagyu, H; Harada, K; Osuga, J I; Ohashi, K; Yazaki, Y; Yamada, N

    1996-01-01

    Lipoprotein lipase (LPL) is a key enzyme in the hydrolysis of triglyceride-rich lipoproteins. Conflicting results have been reported concerning its role in atherogenesis. To determine the effects of the overexpressed LPL on diet-induced atherosclerosis, we have generated low density lipoprotein receptor (LDLR) knockout mice that overexpressed human LPL transgene (LPL/LDLRKO) and compared their plasma lipoproteins and atherosclerosis with those in nonexpressing LDLR-knockout mice (LDLRKO). On a normal chow diet, LPL/LDLRKO mice showed marked suppression of mean plasma triglyceride levels (32 versus 236 mg/dl) and modest decrease in mean cholesterol levels (300 versus 386 mg/dl) as compared with LDLRKO mice. Larger lipoprotein particles of intermediate density lipoprotein (IDL)/LDL were selectively reduced in LPL/LDLRKO mice. On an atherogenic diet, both mice exhibited severe hypercholesterolemia. But, mean plasma cholesterol levels in LPL/ LDLRKO mice were still suppressed as compared with that in LDLRKO mice (1357 versus 2187 mg/dl). Marked reduction in a larger subfraction of IDL/LDL, which conceivably corresponds to remnant lipoproteins, was observed in the LPL/LDLRKO mice. LDLRKO mice developed severe fatty streak lesions in the aortic sinus after feeding with the atherogenic diet for 8 weeks. In contrast, mean lesion area in the LPL/LDLRKO mice was 18-fold smaller than that in LDLRKO mice. We suggest that the altered lipoprotein profile, in particular the reduced level of remnant lipoproteins, is mainly responsible for the protection by LPL against atherosclerosis. Images Fig. 1 Fig. 3 PMID:8692976

  14. High Density Lipoprotein Metabolism in Man

    PubMed Central

    Blum, Conrad B.; Levy, Robert I.; Eisenberg, Shlomo; Hall, Marshall; Goebel, Robert H.; Berman, Mones

    1977-01-01

    The turnover of 125I-high density lipoprotein (HDL) was examined in a total of 14 studies in eight normal volunteers in an attempt to determine the metabolic relationship between apolipoproteins A-I (apoA-I) and A-II (apoA-II) of HDL and to define further some of the determinants of HDL metabolism. All subjects were first studied under conditions of an isocaloric balanced diet (40% fat, 40% carbohydrate). Four were then studied with an 80% carbohydrate diet, and two were studied while receiving nicotinic acid (1 g three times daily) and ingesting the same isocaloric balanced diet. The decay of autologous 125I-HDL and the appearance of urinary radioactivity were followed for at least 2 wk in each study. ApoA-I and apoA-II were isolated by Sephadex G-200 chromatography from serial plasma samples in each study. The specific activities of these peptides were then measured directly. It was found that the decay of specific activity of apoA-I and apoA-II were parallel to one another in all studies. The mean half-life of the terminal portion of decay was 5.8 days during the studies with a balanced diet. Mathematical modeling of the decay of plasma radioactivity and appearance of urinary radioactivity was most consistent with a two-compartment model. One compartment is within the plasma and exchanges with a nonplasma component. Catabolism occurs from both of these compartments. With a balanced isocaloric diet, the mean synthetic rate for HDL protein was 8.51 mg/kg per day. HDL synthesis was not altered by the high carbohydrate diet and was only slightly decreased by nicotinic acid treatment. These perturbations had effects on HDL catabolic pathways that were reciprocal in many respects. With an 80% carbohydrate diet, the rate of catabolism from the plasma compartment rose by a mean of 39.1%; with nicotinic acid treatment, it fell by 42.2%. Changes in the rate of catabolism from the second compartment were generally opposite those in the rate of catabolism from the plasma compartment, suggesting that these two catabolic pathways may be reciprocally regulated. Images PMID:197124

  15. Human plasma very low density lipoprotein carries Indian hedgehog.

    PubMed

    Queiroz, Karla C S; Tio, Rene A; Zeebregts, Clark J; Bijlsma, Maarten F; Zijlstra, Felix; Badlou, Bahram; de Vries, Marcel; Ferreira, Carmen V; Spek, C Arnold; Peppelenbosch, Maikel P; Rezaee, Farhad

    2010-11-01

    Hedgehog is one of the major morphogens and fulfils critical functions in both the development and maintenance of the vasculature. Hedgehog is highly hydrophobic and its diffusion toward target tissues remains only partly understood. In Drosophila, hedgehog transport via lipophorins is relevant for development, but neither the presence nor a function for a mammalian Hedgehog carried by human plasma lipoproteins has been established. We investigated the presence of Hedgehog on lipoprotein particles and determined its importance for maintaining the endothelium. LTQ-Orbitrap XL analysis of defined plasma lipoproteins revealed that Indian Hedgehog (Ihh) is present in the human very low density lipoprotein (VLDL) fraction but not in other plasma lipoprotein fractions (low density lipoprotein (LDL) and high density lipoprotein (HDL)). Using the same approach, neither Sonic Hedgehog nor Desert Hedgehog could be detected in plasma lipoprotein fractions. Most likely, primary white adipocytes are the source of Ihh loading on VLDL as both transcriptome as well as immunofluorescence analysis showed high expression of Ihh in these cells. Additionally, we show that the endothelial compartment is most likely to be affected by the presence of Ihh on VLDL. Indeed, VLDL increased survival of primary endothelial cells, suggesting that Ihh transport by VLDL is important for maintaining the human endothelium. In conclusion, our study shows that VLDL carries Ihh throughout the body in mammals and Hedgehog signaling by human plasma VLDL particles may affect blood vessel pathophysiology. A combination of three state-of-the-art technologies, proteomics, genomics, and confocal microscopy, appeared to be a powerful tool for analyzing plasma lipoprotein-associated proteins. PMID:20839884

  16. Lipopolysaccharide Is Transferred from High-Density to Low-Density Lipoproteins by Lipopolysaccharide-Binding Protein and Phospholipid Transfer Protein

    PubMed Central

    Levels, J. H. M.; Marquart, J. A.; Abraham, P. R.; van den Ende, A. E.; Molhuizen, H. O. F.; van Deventer, S. J. H.; Meijers, J. C. M.

    2005-01-01

    Lipopolysaccharide (LPS), the major outer membrane component of gram-negative bacteria, is a potent endotoxin that triggers cytokine-mediated systemic inflammatory responses in the host. Plasma lipoproteins are capable of LPS sequestration, thereby attenuating the host response to infection, but ensuing dyslipidemia severely compromises this host defense mechanism. We have recently reported that Escherichia coli J5 and Re595 LPS chemotypes that contain relatively short O-antigen polysaccharide side chains are efficiently redistributed from high-density lipoproteins (HDL) to other lipoprotein subclasses in normal human whole blood (ex vivo). In this study, we examined the role of the acute-phase proteins LPS-binding protein (LBP) and phospholipid transfer protein (PLTP) in this process. By the use of isolated HDL containing fluorescent J5 LPS, the redistribution of endotoxin among the major lipoprotein subclasses in a model system was determined by gel permeation chromatography. The kinetics of LPS and lipid particle interactions were determined by using Biacore analysis. LBP and PLTP were found to transfer LPS from HDL predominantly to low-density lipoproteins (LDL), in a time- and dose-dependent manner, to induce remodeling of HDL into two subpopulations as a consequence of the LPS transfer and to enhance the steady-state association of LDL with HDL in a dose-dependent fashion. The presence of LPS on HDL further enhanced LBP-dependent interactions of LDL with HDL and increased the stability of the HDL-LDL complexes. We postulate that HDL remodeling induced by LBP- and PLTP-mediated LPS transfer may contribute to the plasma lipoprotein dyslipidemia characteristic of the acute-phase response to infection. PMID:15784577

  17. Lipolytic degradation of human very low density lipoproteins by human milk lipoprotein lipase: the identification of lipoprotein B as the main lipoprotein degradation product.

    PubMed

    Alaupovic, P; Wang, C S; McConathy, W J; Weiser, D; Downs, D

    1986-01-01

    Although the direct conversion of very low density lipoproteins (VLDL) into low density (LDL) and high density (HDL) lipoproteins only requires lipoprotein lipase (LPL) as a catalyst and albumin as the fatty acid acceptor, the in vitro-formed LDL and HDL differ chemically from their native counterparts. To investigate the reason(s) for these differences, VLDL were treated with human milk LPL in the presence of albumin, and the LPL-generated LDL1-, LDL2-, and HDL-like particles were characterized by lipid and apolipoprotein composition. Results showed that the removal of apolipoproteins B, C, and E from VLDL was proportional to the degree of triglyceride hydrolysis with LDL2 particles as the major and LDL1 and HDL + VHDL particles as the minor products of a complete in vitro lipolysis of VLDL. In comparison with native counterparts, the in vitro-formed LDL2 and HDL + VHDL were characterized by lower levels of triglyceride and cholesterol ester and higher levels of free cholesterol and lipid phosphorus. The characterization of lipoprotein particles present in the in vitro-produced LDL2 showed that, as in plasma LDL2, lipoprotein B (LP-B) was the major apolipoprotein B-containing lipoprotein accounting for over 90% of the total apolipoprotein B. Other, minor species of apolipoprotein B-containing lipoproteins included LP-B:C-I:E and LP-B:C-I:C-II:C-III. The lipid composition of in vitro-formed LP-B closely resembled that of plasma LP-B. The major parts of apolipoproteins C and E present in VLDL were released to HDL + VHDL as simple, cholesterol/phospholipid-rich lipoproteins including LP-C-I, LP-C-II, LP-C-III, and LP-E. However, some of these same simple lipoprotein particles were present after ultracentrifugation in the LDL2 density segment because of their hydrated density and/or because they formed, in the absence of naturally occurring acceptors (LP-A-I:A-II), weak associations with LP-B. Thus, the presence of varying amounts of these cholesterol/phospholipid-rich lipoproteins in the in vitro-formed LDL2 appears to be the main reason for their compositional difference from native LDL2. These results demonstrate that the formation of LP-B as the major apolipoprotein B-containing product of VLDL lipolysis only requires LPL as a catalyst and albumin as the fatty acid acceptor. However, under physiological circumstances, other modulating agents are necessary to prevent the accumulation and interaction of phospholipid/cholesterol-rich apolipoprotein C- and E-containing particles. PMID:3080947

  18. Characterization of chick serum lipoproteins isolated by density gradient ultracentrifugation.

    PubMed

    Rodriguez-Vico, F; Lopez, J M; Castillo, M; Zafra, M F; Garcia-Peregrin, E

    1992-01-01

    Serum lipoproteins from 12h fasted male chicks (15-day-old) were separated into 20 fractions by isopycnic density gradient ultracentrifugation. A new procedure was described by collecting the different fractions from the bottom of tube instead of by aspiration from the meniscus of each tube. Analyses of chemical composition of serum lipoproteins have permitted to reevaluate the density limits of major classes: VHDL, d greater than 1.132 g/ml; HDL, d 1.132-1.084 g/ml; LDL, d 1.084-1.038; IDL, d 1.038-1.022; and VLDL d less than 1.022. HDL fractions clearly predominated (approx. 77% of total lipoproteins) while IDL and VLDL were present at low percentage. LDL was the fraction richest in cholesterol; triacylglycerol content clearly increased from HDL to VLDL, while protein content decreased. All the chemical components of chick serum lipoproteins were accumulated in HDL, although triacylglycerol was relatively distributed in all the lipoprotein classes. PMID:1380327

  19. A Novel Anti-Inflammatory Effect for High Density Lipoprotein

    PubMed Central

    Cameron, Scott J.; Morrell, Craig N.; Bao, Clare; Swaim, AnneMarie F.; Rodriguez, Annabelle; Lowenstein, Charles J.

    2015-01-01

    High density lipoprotein has anti-inflammatory effects in addition to mediating reverse cholesterol transport. While many of the chronic anti-inflammatory effects of high density lipoprotein (HDL) are attributed to changes in cell adhesion molecules, little is known about acute signal transduction events elicited by HDL in endothelial cells. We now show that high density lipoprotein decreases endothelial cell exocytosis, the first step in leukocyte trafficking. ApoA-I, a major apolipoprotein of HDL, mediates inhibition of endothelial cell exocytosis by interacting with endothelial scavenger receptor-BI which triggers an intracellular protective signaling cascade involving protein kinase C (PKC). Other apolipoproteins within the HDL particle have only modest effects upon endothelial exocytosis. Using a human primary culture of endothelial cells and murine apo-AI knockout mice, we show that apo-AI prevents endothelial cell exocytosis which limits leukocyte recruitment. These data suggest that high density lipoprotein may inhibit diseases associated with vascular inflammation in part by blocking endothelial exocytosis. PMID:26680360

  20. The High-Density Lipoprotein Puzzle: Why Classic Epidemiology, Genetic Epidemiology, and Clinical Trials Conflict?

    PubMed

    Rosenson, Robert S

    2016-05-01

    Classical epidemiology has established the incremental contribution of the high-density lipoprotein (HDL) cholesterol measure in the assessment of atherosclerotic cardiovascular disease risk; yet, genetic epidemiology does not support a causal relationship between HDL cholesterol and the future risk of myocardial infarction. Therapeutic interventions directed toward cholesterol loading of the HDL particle have been based on epidemiological studies that have established HDL cholesterol as a biomarker of atherosclerotic cardiovascular risk. However, therapeutic interventions such as niacin, cholesteryl ester transfer protein inhibitors increase HDL cholesterol in patients treated with statins, but have repeatedly failed to reduce cardiovascular events. Statin therapy interferes with ATP-binding cassette transporter-mediated macrophage cholesterol efflux via miR33 and thus may diminish certain HDL functional properties. Unraveling the HDL puzzle will require continued technical advances in the characterization and quantification of multiple HDL subclasses and their functional properties. Key mechanistic criteria for clinical outcomes trials with HDL-based therapies include formation of HDL subclasses that improve the efficiency of macrophage cholesterol efflux and compositional changes in the proteome and lipidome of the HDL particle that are associated with improved antioxidant and anti-inflammatory properties. These measures require validation in genetic studies and clinical trials of HDL-based therapies on the background of statins. PMID:26966281

  1. Effects of human low and high density lipoproteins on the binding of rat intermediate density lipoproteins to rat liver membranes

    SciTech Connect

    Brissette, L.; Nol, S.P.

    1986-05-25

    Upon incubation with rat liver membranes, radioiodinated rat intermediate density lipoproteins (IDL) interacted with at least two binding sites having a low and a high affinity as demonstrated by the curvilinear Scatchard plots obtained from the specific binding data. The purpose of our work was to identify the nature of these binding sites. Human low density lipoproteins (LDL), contain apolipoprotein B only, and human high density lipoproteins (HDL3), containing neither apolipoprotein B nor E, were both capable of decreasing the specific binding of rat /sup 125/I-IDL. The Scatchard analysis clearly revealed that only the low affinity component was affected by the addition of these human lipoproteins. In fact, the low affinity binding component gradually decreased as the amount of human LDL or HDL3 increased in the binding assay. At a 200-fold excess of human LDL or HDL3, the low affinity binding was totally masked, and the Scatchard plot of the specific /sup 125/I-IDL binding became linear. Only the high affinity binding component was left, enabling a precise measurement of its binding parameters. In a series of competitive displacement experiments in which the binding assay contained a 200-fold excess of human LDL or HDL3, only unlabeled rat IDL effectively displaced the binding of rat /sup 125/I-IDL. We conclude that the low affinity binding of rat IDL to rat liver membranes is due to weak interactions with unspecified lipoprotein binding sites. The camouflage of these sites by human lipoproteins makes possible the study of IDL binding to the high affinity component which likely represents the combined effect of IDL binding to both the remnant and the LDL receptors.

  2. 21 CFR 866.5600 - Low-density lipoprotein immunological test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Low-density lipoprotein immunological test system. 866.5600 Section 866.5600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... the low-density lipoprotein in serum and other body fluids. Measurement of low-density lipoprotein...

  3. 21 CFR 866.5600 - Low-density lipoprotein immunological test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Low-density lipoprotein immunological test system. 866.5600 Section 866.5600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... the low-density lipoprotein in serum and other body fluids. Measurement of low-density lipoprotein...

  4. 21 CFR 866.5600 - Low-density lipoprotein immunological test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Low-density lipoprotein immunological test system. 866.5600 Section 866.5600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... the low-density lipoprotein in serum and other body fluids. Measurement of low-density lipoprotein...

  5. 21 CFR 866.5600 - Low-density lipoprotein immunological test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Low-density lipoprotein immunological test system. 866.5600 Section 866.5600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... the low-density lipoprotein in serum and other body fluids. Measurement of low-density lipoprotein...

  6. 21 CFR 866.5600 - Low-density lipoprotein immunological test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Low-density lipoprotein immunological test system. 866.5600 Section 866.5600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... the low-density lipoprotein in serum and other body fluids. Measurement of low-density lipoprotein...

  7. [THE BECOMING IN PHYLOGENESIS OF TRANSFER IN INTERCELLULAR MEDIUM AND ACTIVE ABSORPTION OF POLYENOIC FATTY ACIDS BY CELLS SEQUENTIALLY OF HIGH DENSITY LIPOPROTEINS, LOW DENSITY LIPOPROTEINS AND HIGH DENSITY APOE-LIPOPROTEINS].

    PubMed

    Titov, V N

    2015-06-01

    After more than half-century of different conceptions, the theory of general pathology was used to substantiate that all lipoproteins are bi-layer:lipid by their structure. The main function of high density lipoproteins as of all lipoproteins is transfer of fatty acids to cells and only in second turn taking away of spirit cholesterol from cells. At the stages of phylogenesis high density lipoproteins, low density lipoproteins and very low density lipoproteins began to function in a subsequent way. The fatty acids were transferred by low density lipoproteins in polar lipids at passive absorption by cells. Later on, lipoproteins transfer fatty acids in non-polar ethers with spirits glycerin and spirit cholesterol. The cells absorb them by receptor endocytosis. The hepatocytes secret in blood palmitic, oleic, linoleic and linoleic very low density lipoproteins. The palmitic and oleic very low density lipoproteins absorb physiologically insulin-dependent cells apoE/B-100 = endocytosis. The linoleic and linoleic very low density lipoproteins after transition of polyethers cholesterol from high density lipoproteins turn into low density lipoproteins. The cells absorb them by apoB-100 = endocytosis. The formation of chylomicrons occurs in blood and hepatocytes absorb them by the way of apoB/E-48 = endocytosis. The absorption of poly-unsaturated fatty acids by cells with apoB-100 = endocytosis form sensitivity of animals to exogenous hyper spirit cholesterol and absorption of poly-unsaturated fatty acids by apoE/A-I = receptors form corresponding resistance. The ApoE in lipoproteins form cooperative ligands--apoE/B-48 for chylomicrons, apoE/B-100 for very low density lipoproteins and apoE/A-I for high density lipoproteins. The chylomicrons in blood form apoB-48 from complexes of triglycerides secreted by enterocytes. These views change conceptions of pathogenesis and prevention of atherosclerosis, metabolic syndrome and resistance to insulin whose pathogenesis is unified by disorder of transfer in intercellular medium and absorption of fatty acids by cells. PMID:26466444

  8. High-Density Lipoproteins and the Immune System

    PubMed Central

    Kaji, Hidesuke

    2013-01-01

    High-density lipoprotein (HDL) plays a major role in vasodilation and in the reduction of low-density lipoprotein (LDL) oxidation, inflammation, apoptosis, thrombosis, and infection; however, HDL is now less functional in these roles under certain conditions. This paper focuses on HDL, its anti-inflammation behavior, and the mechanisms by which HDL interacts with components of the innate and adaptive immune systems. Genome-wide association studies (GWAS) and proteomic studies have elucidated important molecules involved in the interaction between HDL and the immune system. An understanding of these mechanisms is expected to be useful for the prevention and treatment of chronic inflammation due to metabolic syndrome, atherosclerosis, or various autoimmune diseases. PMID:23431458

  9. Small, dense low-density lipoprotein: risk or myth?

    PubMed

    Le, Ngoc-Anh

    2003-01-01

    Based on the particle diameter of the major subpopulation of low-density lipoprotein (LDL) in plasma, an individual may be classified either as having phenotype A (desirable phenotype; large, buoyant LDL) or phenotype B (high risk; small, dense LDL). This article reviews the clinical significance of LDL particle diameter determination and proposes a strategy for incorporating this information in the new guidelines of the National Cholesterol Education Program's Adult Treatment Panel III. PMID:12562538

  10. Low-Density Lipoprotein Sensor Based on Molecularly Imprinted Polymer.

    PubMed

    Chunta, Suticha; Suedee, Roongnapa; Lieberzeit, Peter A

    2016-01-19

    Increased level of low-density lipoprotein (LDL) strongly correlates with incidence of coronary heart disease. We synthesized novel molecularly imprinted polymers (MIP) as biomimetic specific receptors to establish rapid analysis of LDL levels. For that purpose the ratios of monomers acrylic acid (AA), methacrylic acid (MAA), and N-vinylpyrrolidone (VP), respectively, were screened on 10 MHz dual-electrode quartz crystal microbalances (QCM). Mixing MAA and VP in the ratio 3:2 (m/m) revealed linear sensor characteristic to LDL cholesterol (LDL-C) from 4 to 400 mg/dL or 0.10-10.34 mmol/L in 100 mM phosphate-buffered saline (PBS) without significant interference: high-density lipoprotein (HDL) yields 4-6% of the LDL signal, very-low-density-lipoprotein (VLDL) yields 1-3%, and human serum albumin (HSA) yields 0-2%. The LDL-MIP sensor reveals analytical accuracy of 95-96% at the 95% confidence interval with precision at 6-15%, respectively. Human serum diluted 1:2 with PBS buffer was analyzed by LDL-MIP sensors to demonstrate applicability to real-life samples. The sensor responses are excellently correlated to the results of the standard technique, namely, a homogeneous enzymatic assay (R(2) = 0.97). This demonstrates that the system can be successfully applied to human serum samples for determining LDL concentrations. PMID:26643785

  11. Purification of very high density lipoproteins by differential density gradient ultracentrifugation.

    PubMed

    Haunerland, N H; Ryan, R O; Law, J H; Bowers, W S

    1987-03-01

    Differential density gradient ultracentrifugation procedures, utilizing a vertical rotor, were developed for the preparative purification of very high density lipoproteins (VHDL, density greater than 1.21 g/ml). The VHDLs of several insect species were purified as follows. An initial density gradient ultracentrifugation step removed lipoproteins of lower density from the VHDL-fraction, which partially separated from the nonlipoproteins present in the infranatant. A complete separation was achieved by a second centrifugation step employing a modified gradient system. The use of a vertical rotor and specially designed discontinuous gradients allows a relatively fast, efficient, and economical isolation of the class of very high density lipoproteins. Similar gradient systems should be useful for the detection and purification of VHDLs from other sources. PMID:3578796

  12. A prominent large high-density lipoprotein at birth enriched in apolipoprotein C-I identifies a new group of infancts of lower birth weight and younger gestational age

    SciTech Connect

    Kwiterovich Jr., Peter O.; Cockrill, Steven L.; Virgil, Donna G.; Garrett, Elizabeth; Otvos, James; Knight-Gibson, Carolyn; Alaupovic, Petar; Forte, Trudy; Farwig, Zachlyn N.; Macfarlane, Ronald D.

    2003-10-01

    Because low birth weight is associated with adverse cardiovascular risk and death in adults, lipoprotein heterogeneity at birth was studied. A prominent, large high-density lipoprotein (HDL) subclass enriched in apolipoprotein C-I (apoC-I) was found in 19 percent of infants, who had significantly lower birth weights and younger gestational ages and distinctly different lipoprotein profiles than infants with undetectable, possible or probable amounts of apoC-I-enriched HDL. An elevated amount of an apoC-I-enriched HDL identifies a new group of low birth weight infants.

  13. Data on carotid intima-media thickness and lipoprotein subclasses in type 1 diabetes from the Diabetes Control and Complications Trial and the Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC).

    PubMed

    Basu, Arpita; Jenkins, Alicia J; Zhang, Ying; Stoner, Julie A; Klein, Richard L; Lopes-Virella, Maria F; Timothy Garvey, W; Lyons, Timothy J

    2016-03-01

    Type 1 diabetes (T1DM) is associated with increased risk of macrovascular complications. We examined longitudinal associations of serum conventional lipids and nuclear magnetic resonance (NMR)-determined lipoprotein subclasses with carotid intima-media thickness (IMT) in adults with T1DM (n=455) enrolled in the Diabetes Control and Complications Trial (DCCT). Data on serum lipids and lipoproteins were collected at DCCT baseline (1983-89) and were correlated with common and internal carotid IMT determined by ultrasonography during the observational follow-up of the DCCT, the Epidemiology of Diabetes Interventions and Complications (EDIC) study, at EDIC 'Year 1' (199-1996) and EDIC 'Year 6' (1998-2000). This article contains data on the associations of DCCT baseline lipoprotein profiles (NMR-based VLDL & chylomicrons, IDL/LDL and HDL subclasses and 'conventional' total, LDL-, HDL-, non-HDL-cholesterol and triglycerides) with carotid IMT at EDIC Years 1 and 6, stratified by gender. The data are supplemental to our original research article describing detailed associations of DCCT baseline lipids and lipoprotein profiles with EDIC Year 12 carotid IMT (Basu et al. in press) [1]. PMID:26759826

  14. Data on carotid intima-media thickness and lipoprotein subclasses in type 1 diabetes from the Diabetes Control and Complications Trial and the Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC)

    PubMed Central

    Basu, Arpita; Jenkins, Alicia J.; Zhang, Ying; Stoner, Julie A.; Klein, Richard L.; Lopes-Virella, Maria F.; Timothy Garvey, W.; Lyons, Timothy J.

    2015-01-01

    Type 1 diabetes (T1DM) is associated with increased risk of macrovascular complications. We examined longitudinal associations of serum conventional lipids and nuclear magnetic resonance (NMR)-determined lipoprotein subclasses with carotid intima-media thickness (IMT) in adults with T1DM (n=455) enrolled in the Diabetes Control and Complications Trial (DCCT). Data on serum lipids and lipoproteins were collected at DCCT baseline (1983–89) and were correlated with common and internal carotid IMT determined by ultrasonography during the observational follow-up of the DCCT, the Epidemiology of Diabetes Interventions and Complications (EDIC) study, at EDIC ‘Year 1’ (199–1996) and EDIC ‘Year 6’ (1998–2000). This article contains data on the associations of DCCT baseline lipoprotein profiles (NMR-based VLDL & chylomicrons, IDL/LDL and HDL subclasses and ‘conventional’ total, LDL-, HDL-, non-HDL-cholesterol and triglycerides) with carotid IMT at EDIC Years 1 and 6, stratified by gender. The data are supplemental to our original research article describing detailed associations of DCCT baseline lipids and lipoprotein profiles with EDIC Year 12 carotid IMT (Basu et al. in press) [1]. PMID:26759826

  15. A short-run new analytical ultracentrifugal micromethod for determining low-density lipoprotein sub-fractions using Schlieren refractometry.

    PubMed

    Bozóky, Z; Fülöp, L; Köhidai, L

    2001-01-01

    We have developed a new analytical ultracentrifugal micromethod for the determination of serum low-density lipoprotein (LDL) subclasses directly from ultracentrifugal Schlieren scans. We have used special software for the analysis of this type of single-spin density-gradient ultracentrifugation. The flotation of LDL patterns was obtained by underlayering a physiological salt solution with serum or isolated lipoprotein fractions raised to a density of 1.3 g/mL in the spinning ultracentrifugation capillary band-forming cell. The repeated analysis of Schlieren curves of the same sample from 10 to 100 microL in the 60-100 min full-speed interval time resulted in quite reproducible results. We obtained quantitative results by measuring the Schlieren areas between the sample curves and the reference baseline curve by using computerised numerical and graphic techniques. The decomposition of the integrated curve was carried out using a nonlinear regression program followed by deconvolution algorithm analysis in order to determine the parameters of the composing Gaussian subclasses. The LDL particle concentrations were calculated from the area under the integral of the Gaussian curve using a calibration data constant. The flotation range of the LDL Schlieren curves in the cell was identified with serum from which LDL had been removed by means of precipitation reagents and with centrifugation of isolated LDL aliquots. With this technique, we measured the concentration of LDL and analysed its polydispersity without the need for preceding sequential isolation of the LDL. On the basis of the Schlieren curves, the LDL samples were either physically paucidisperse, having a symmetrical peak within a narrow density range, or were polydisperse, showing an asymmetrical pattern distributed over a broader density region. The described method proved to be useful for a clear and immediate visual presentation of the concentration values of the LDL and for the identification of the heterogeneity of LDL variants without the need for the preparative isolation of that density class. PMID:11288837

  16. High Density Lipoprotein and it’s Dysfunction

    PubMed Central

    Eren, Esin; Yilmaz, Necat; Aydin, Ozgur

    2012-01-01

    Plasma high-density lipoprotein cholesterol(HDL-C) levels do not predict functionality and composition of high-density lipoprotein(HDL). Traditionally, keeping levels of low-density lipoprotein cholesterol(LDL-C) down and HDL-C up have been the goal of patients to prevent atherosclerosis that can lead to coronary vascular disease(CVD). People think about the HDL present in their cholesterol test, but not about its functional capability. Up to 65% of cardiovascular death cannot be prevented by putative LDL-C lowering agents. It well explains the strong interest in HDL increasing strategies. However, recent studies have questioned the good in using drugs to increase level of HDL. While raising HDL is a theoretically attractive target, the optimal approach remains uncertain. The attention has turned to the quality, rather than the quantity, of HDL-C. An alternative to elevations in HDL involves strategies to enhance HDL functionality. The situation poses an opportunity for clinical chemists to take the lead in the development and validation of such biomarkers. The best known function of HDL is the capacity to promote cellular cholesterol efflux from peripheral cells and deliver cholesterol to the liver for excretion, thereby playing a key role in reverse cholesterol transport (RCT). The functions of HDL that have recently attracted attention include anti-inflammatory and anti-oxidant activities. High antioxidant and anti-inflammatory activities of HDL are associated with protection from CVD. This review addresses the current state of knowledge regarding assays of HDL functions and their relationship to CVD. HDL as a therapeutic target is the new frontier with huge potential for positive public health implications. PMID:22888373

  17. Diet and low-density lipoprotein particle size.

    PubMed

    Desroches, Sophie; Lamarche, Benoît

    2004-11-01

    Small, dense low-density lipoprotein (LDL) particles are being increasingly recognized as an important risk factor for cardiovascular disease. This paper provides an overview of how different diets and macronutrients modulate the LDL size phenotype. Data reviewed indicated that several components of the LDL size phenotype should be measured concurrently in order to fully appreciate the impact of diet on this complex trait. Data also suggested that numerous dietary elements have a significant impact on several characteristics of the LDL size phenotype, thus providing further evidence to the concept that specific dietary modifications can beneficially alter cardiovascular disease risk beyond their known and demonstrated effects on plasma LDL cholesterol concentrations. PMID:15485591

  18. Relative atherogenicity and predictive value of non-high-density lipoprotein cholesterol for coronary heart disease

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although low-density lipoprotein cholesterol (LDL-C) is a well-established atherogenic factor for coronary heart disease, it does not completely represent the risk associated with atherogenic lipoproteins in the presence of high triglyceride (TG) levels. Constituent lipoproteins constituting non–hig...

  19. LIPOPROTEIN LIPASE RELEASES ESTERIFIED OXYLIPINS FROM VERY LOW-DENSITY LIPOPROTEINS.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Defects in lipoprotein metabolism alter the lipoprotein distribution of oxidized PUFAs, and we speculate that lipoprotein lipase (LpL) is a determinant in the release of VLDL-associated oxylipins. Here, using 12 wk old normolipidemic (lean) and hyperlipidemic (obese) Zucker-rats, we measured PUFA al...

  20. An evaluation of serum high density lipoproteins-phospholipids.

    PubMed

    Ide, H; Tsuji, M; Shimada, M; Kondo, T; Fujiya, S; Asanuma, Y; Agishi, Y

    1988-07-01

    Phospholipids in high density lipoproteins (HDL) is being used as a negative risk indicator of atherosclerosis. Phospholipids in HDL may not demonstrate the actual level of HDL-phospholipids when determined by the precipitation or ultracentrifugal methods, because HDL fractions contain very high density lipoproteins (VHDL) and albumin. In the present study, the true level of phospholipids in HDL was estimated using high performance liquid chromatography (HPLC), and it was compared with the level of phospholipids in HDL determined by the precipitation method. Sera from 18 healthy subjects were used as materials. In the HPLC method, the HDL fraction was extracted making sure that it contained no free albumin, which is albumin not bound to phospholipids. The HDL fraction was separated into subfractions. It was found that phospholipids in the VHDL fraction make a 20.2 +/- 7.3% (mean +/- S.D.) part of the total HDL-phospholipids. A large part of the VHDL fraction was constituted of albumin-bound phospholipids. A significant correlation was observed between HDL-phospholipids determined by the precipitation method, which contain albumin, and the actual HDL fraction phospholipids determined by HPLC, which do not contain VHDL (r = 0.903, p less than 0.01). These results suggest that HDL-phospholipids values determined by the precipitation method give useful clinical data. PMID:3176021

  1. Protein carbamylation renders high-density lipoprotein dysfunctional

    PubMed Central

    2012-01-01

    Aim Carbamylation of proteins through reactive cyanate has been demonstrated to predict an increased cardiovascular risk. Cyanate is formed in vivo by break-down of urea and at sites of inflammation by the phagocyte protein myeloperoxidase. Since myeloperoxidase (MPO) associates with high-density lipoprotein (HDL) in human atherosclerotic intima, we examined in the present study whether cyanate specifically targets HDL. Results Mass spectrometry analysis revealed that protein carbamylation is a major post-translational modification of HDL. The carbamyllysine content of lesion derived HDL was more than 20-fold higher in comparison to 3-chlorotyrosine levels, a specific oxidation product of MPO. Notable, the carbamyllysine content of lesion-derived HDL was 5 to 8-fold higher when compared to lesion derived low-density lipoprotein (LDL) or total lesion protein and increased with lesion severity. Importantly, the carbamyllysine content of HDL, but not of LDL, correlated with levels of 3-chlorotyrosine, suggesting MPO mediated carbamylation in the vessel wall. Remarkably, one carbamyllysine residue per HDL associated apolipoprotein A-I was sufficient to induce cholesterol accumulation and lipid droplet formation in macrophages through a pathway requiring the HDL receptor scavenger receptor class B, type I. Conclusion The present results raise the possibility that HDL carbamylation contributes to foam cell formation in atherosclerotic lesions. PMID:21235354

  2. Novel therapies focused on the high-density lipoprotein particle.

    PubMed

    van Capelleveen, Julian C; Brewer, H Bryan; Kastelein, John J P; Hovingh, G Kees

    2014-01-01

    Cardiovascular disease (CVD) remains a major burden for morbidity and mortality in the general population, despite current efficacious low-density lipoprotein-cholesterol-lowering therapies. Consequently, novel therapies are required to reduce this residual risk. Prospective epidemiological studies have shown that high-density lipoprotein-cholesterol (HDL-C) levels are inversely correlated with cardiovascular disease risk, and this initiated the quest for HDL-C-increasing therapies. Consequently, several different targets in HDL metabolism have been identified. Initial studies addressing the effect of cholesteryl ester transfer protein inhibition on cardiovascular disease outcome have been discontinued for reasons of futility or increased mortality. As of yet, 2 cholesteryl ester transfer protein inhibitors are still in phase III studies. Other HDL-based interventions, such as apolipoprotein A1-based compounds, ABC-transporter upregulators, selective peroxisome proliferator-activated receptor modulators and lecithin-cholesterol acyltransferase-based therapy, hold great promise for the future. The aim of this review is to provide a comprehensive overview of HDL-targeted pharmaceutical strategies in humans, both in early development as well as in late stage clinical trials. PMID:24385512

  3. Effect of dietary fat saturation on plasma lipoproteins and high density lipoprotein metabolism of the rhesus monkey.

    PubMed Central

    Chong, K S; Nicolosi, R J; Rodger, R F; Arrigo, D A; Yuan, R W; MacKey, J J; Georas, S; Herbert, P N

    1987-01-01

    Rhesus monkeys were fed corn or coconut oil-based diets for 3-6 mo to determine effects on the composition of all lipoprotein classes and on the metabolism of high density lipoproteins (HDL). Major findings included the following. Coconut oil feeding increased concentrations of all classes of plasma lipoproteins without altering lipoprotein size, suggesting an increase in particle number. The percentage of saturated fatty acids in the cholesteryl esters (CE) of low density lipoproteins (LDL) and HDL reached 40% with coconut oil feeding. This value probably constitutes a minimum estimate of the CE which were of intracellular rather than intraplasmic origin. The CE in LDL and HDL were nearly identical suggesting virtually complete equilibration by the core lipid transfer reaction. The CE in very low density lipoproteins, in contrast, were significantly more saturated than those in LDL and HDL irrespective of diet. Lower HDL levels on the corn oil diet were associated with higher fractional catabolic rates for both apolipoprotein A-I (0.42 vs. 0.31 d-1) and apolipoprotein A-II (0.45 vs. 0.30 d-1). Images PMID:3102555

  4. Six new loci associated with blood low-density lipoprotein cholesterol, high-density lipoprotein cholesterol or triglycerides in humans.

    PubMed

    Kathiresan, Sekar; Melander, Olle; Guiducci, Candace; Surti, Aarti; Burtt, Noël P; Rieder, Mark J; Cooper, Gregory M; Roos, Charlotta; Voight, Benjamin F; Havulinna, Aki S; Wahlstrand, Björn; Hedner, Thomas; Corella, Dolores; Tai, E Shyong; Ordovas, Jose M; Berglund, Göran; Vartiainen, Erkki; Jousilahti, Pekka; Hedblad, Bo; Taskinen, Marja-Riitta; Newton-Cheh, Christopher; Salomaa, Veikko; Peltonen, Leena; Groop, Leif; Altshuler, David M; Orho-Melander, Marju

    2008-02-01

    Blood concentrations of lipoproteins and lipids are heritable risk factors for cardiovascular disease. Using genome-wide association data from three studies (n = 8,816 that included 2,758 individuals from the Diabetes Genetics Initiative specific to the current paper as well as 1,874 individuals from the FUSION study of type 2 diabetes and 4,184 individuals from the SardiNIA study of aging-associated variables reported in a companion paper in this issue) and targeted replication association analyses in up to 18,554 independent participants, we show that common SNPs at 18 loci are reproducibly associated with concentrations of low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and/or triglycerides. Six of these loci are new (P < 5 x 10(-8) for each new locus). Of the six newly identified chromosomal regions, two were associated with LDL cholesterol (1p13 near CELSR2, PSRC1 and SORT1 and 19p13 near CILP2 and PBX4), one with HDL cholesterol (1q42 in GALNT2) and five with triglycerides (7q11 near TBL2 and MLXIPL, 8q24 near TRIB1, 1q42 in GALNT2, 19p13 near CILP2 and PBX4 and 1p31 near ANGPTL3). At 1p13, the LDL-associated SNP was also strongly correlated with CELSR2, PSRC1, and SORT1 transcript levels in human liver, and a proxy for this SNP was recently shown to affect risk for coronary artery disease. Understanding the molecular, cellular and clinical consequences of the newly identified loci may inform therapy and clinical care. PMID:18193044

  5. Liver disease alters high-density lipoprotein composition, metabolism and function.

    PubMed

    Trieb, Markus; Horvath, Angela; Birner-Gruenberger, Ruth; Spindelboeck, Walter; Stadlbauer, Vanessa; Taschler, Ulrike; Curcic, Sanja; Stauber, Rudolf E; Holzer, Michael; Pasterk, Lisa; Heinemann, Akos; Marsche, Gunther

    2016-07-01

    High-density lipoproteins (HDL) are important endogenous inhibitors of inflammatory responses. Functional impairment of HDL might contribute to the excess mortality experienced by patients with liver disease, but the effect of cirrhosis on HDL metabolism and function remain elusive. To get an integrated measure of HDL quantity and quality, we assessed several metrics of HDL function using apolipoprotein (apo) B-depleted sera from patients with compensated cirrhosis, patients with acutely decompensated cirrhosis and healthy controls. We observed that sera of cirrhotic patients showed reduced levels of HDL-cholesterol and profoundly suppressed activities of several enzymes involved in HDL maturation and metabolism. Native gel electrophoresis analyses revealed that cirrhotic serum HDL shifts towards the larger HDL2 subclass. Proteomic assessment of isolated HDL identified several proteins, including apoA-I, apoC-III, apoE, paraoxonase 1 and acute phase serum amyloid A to be significantly altered in cirrhotic patients. With regard to function, these alterations in levels, composition and structure of HDL were strongly associated with metrics of function of apoB-depleted sera, including cholesterol efflux capability, paraoxonase activity, the ability to inhibit monocyte production of cytokines and endothelial regenerative activities. Of particular interest, cholesterol efflux capacity appeared to be strongly associated with liver disease mortality. Our findings may be clinically relevant and improve our ability to monitor cirrhotic patients at high risk. PMID:27106140

  6. Cholesterol transfer from normal and atherogenic low density lipoproteins to Mycoplasma membranes

    SciTech Connect

    Mitschelen, J.J.; St. Clair, R.W.; Hester, S.H.

    1981-01-01

    The purpose of this study was to determine whether the free cholesterol of hypercholesterolemic low density lipoprotein from cholesterol-fed nonhuman primates has a greater potential for surface transfer to cell membranes than does the free cholesterol of normal low density lipoprotein. The low density lipoproteins were isolated from normal and hypercholesterolemic rhesus and cynomolgus monkeys, incubated with membranes from Acholeplasma laidlawii, a mycoplasma species devoid of cholesterol in its membranes, and the mass transfer of free cholesterol determined by measuring membrane cholesterol content. Since these membranes neither synthesize nor esterify cholesterol, nor degrade the protein or cholesterol ester moieties of low density lipoprotein, they are an ideal model with which to study differences in the cholesterol transfer potential of low density lipoprotein independent of the uptake of the intact low density lipoprotein particle. These studies indicate that, even though there are marked differences in the cholesterol composition of normal and hypercholesterolemic low density lipoproteins, this does not result in a greater chemical potential for surface transfer of free cholesterol. Consequently, if a difference in the surface transfer of free cholesterol is responsible for the enhanced ability of hypercholesterolemic low density lipoprotein to promote cellular cholesterol accumulation and, perhaps, also atherosclerosis, it must be the result of differences in the interaction to the hypercholesterolemic low density lipoprotein with the more complicated mammalian cell membranes, rather than differences in the chemical potential for cholesterol transfer.

  7. Reliability of low-density lipoprotein cholesterol, non-high-density lipoprotein cholesterol, and apolipoprotein B measurement.

    PubMed

    Contois, John H; Warnick, G Russell; Sniderman, Allan D

    2011-01-01

    There is little understanding of the reliability of laboratory measurements among clinicians. Low-density lipoprotein cholesterol (LDL-C) measurement is the cornerstone of cardiovascular risk assessment and prevention, but it is fraught with error. Therefore, we have reviewed issues related to accuracy and precision for the measurement of LDL-C and the related markers non-high-density lipoprotein cholesterol (non-HDL-C) and apolipoprotein B. Despite the widespread belief that LDL-C is standardized and reproducible, available data suggest that results can vary significantly as the result of methods from different manufacturers. Similar problems with direct HDL-C assays raise concerns about the reliability of non-HDL-C measurement. The root cause of method-specific bias relates to the ambiguity in the definition of both LDL and HDL, and the heterogeneity of LDL and HDL particle size and composition. Apolipoprotein B appears to provide a more reliable alternative, but assays for it have not been as rigorously tested as direct LDL-C and HDL-C assays. PMID:21784371

  8. Both hypothyroidism and hyperthyroidism enhance low density lipoprotein oxidation.

    PubMed

    Sundaram, V; Hanna, A N; Koneru, L; Newman, H A; Falko, J M

    1997-10-01

    Hypothyroidism is frequently associated with hypercholesterolemia and an increased risk for atherosclerosis, whereas hyperthyroidism is known to precipitate angina or myocardial infarction in patients with underlying coronary heart disease. We have shown previously that L-T4 functions as an antioxidant in vitro and inhibits low density lipoprotein (LDL) oxidation in a dose-dependent fashion. The present study was designed to evaluate the changes in LDL oxidation in subjects with hypothyroidism and hyperthyroidism. Fasting blood samples for LDL oxidation analyses, lipoprotein determinations, and thyroid function tests were collected at baseline and after the patients were rendered euthyroid. The lag phase (mean +/- SEM hours) of the Cu+2-catalyzed LDL oxidation in the hypothyroid state and the subsequent euthyroid states were 4 +/- 0.0.65 and 14 +/- 0.68 h, respectively (P < 0.05). The lag phase during the hyperthyroid phase was 6 +/- 0.55 h, and that during the euthyroid phase was 12 +/- 0.66 h (P < 0.05). The total and LDL cholesterol levels were higher in hypothyroidism than in euthyroidism and were lower in hyperthyroidism than in the euthyroid state. We conclude that LDL has more susceptibility to oxidation in both the hypothyroid and hyperthyroid states. Thus, the enhanced LDL oxidation may play a role in the cardiac disease process in both hypothyroidism and hyperthyroidism. PMID:9329379

  9. Distinct Hepatic Receptors for Low Density Lipoprotein and Apolipoprotein E in Humans

    NASA Astrophysics Data System (ADS)

    Hoeg, Jeffrey M.; Demosky, Stephen J.; Gregg, Richard E.; Schaefer, Ernst J.; Brewer, H. Bryan

    1985-02-01

    Since the liver is a central organ for lipid and lipoprotein synthesis and catabolism, hepatic receptors for specific apolipoproteins on plasma lipoproteins would be expected to modulate lipid and lipoprotein metabolism. The role of hepatic receptors for low density lipoproteins and apolipoprotein E-containing lipoproteins was evaluated in patients with complementary disorders in lipoprotein metabolism: abetalipoproteinemia and homozygous familial hypercholesterolemia. In addition, hepatic membranes from a patient with familial hypercholesterolemia were studied and compared before and after portacaval shunt surgery. The results establish that the human liver has receptors for apolipoproteins B and E. Furthermore, in the human, hepatic receptors for low density lipoproteins and apolipoprotein E are genetically distinct and can undergo independent control.

  10. Effects of high-density lipoproteins on storage at 4 degrees C of fowl spermatozoa.

    PubMed

    Blesbois, E; Hermier, D

    1990-11-01

    Qualitative and quantitative characterization of lipoproteins found in seminal plasma from domestic cocks was performed after isolation by density gradient ultracentrifugation. Trigyceride-rich lipoproteins (very low, intermediate- and low density lipoproteins) were not detectable in seminal plasma. High-density lipoproteins (HDL), identified on the basis of size, chemical composition and protein moiety, were present at a concentration of 66 micrograms/ml. A fraction possibly corresponding to VHDL (very high density lipoproteins, 77% protein, 23% lipid) was also detected but appeared contaminated by a protein-rich opalescent material. Since HDL contains mostly phospholipid and cholesterol, the physiological role of these lipoproteins on the storage of fowl spermatozoa was studied. Replacing seminal plasma with a solution containing chicken HDL at physiological concentration (66 micrograms/ml) had no effect on fertilizing ability of spermatozoa stored at 4 degrees C for 24 h. However, higher concentrations of HDL (560 micrograms/ml) had deleterious effects on spermatozoa stored in vitro. PMID:2250247

  11. Tetravalent vanadium mediated oxidation of low density lipoprotein.

    PubMed

    Dickson, C; Stern, A

    1990-01-01

    1. Tetravalent vanadium causes oxidation of low density lipoprotein (LDL) as manifest by protein degradation and lipid peroxidation. 2. Oxidative modification of the apolipoprotein B-100 is paralleled by the formation of thiobarbituric acid reactive substance and fluorescent chromolipid production. 3. The metal chelators ethylenediamine tetracetic acid and desferrioxamine, and the alcohols, ethanol and isopropanol inhibit the oxidation of LDL by tetravalent vanadium. No inhibition is observed with superoxide dismutase, catalase or mannitol. 4. The data suggest that aldehydes formed during the process of lipid peroxidation induced by tetravalent vanadium react with the proteins in LDL to form fluorescent chromolipids and that the oxidative process originates within the hydrophobic domain of LDL. PMID:2112099

  12. Cell death induced by peroxidized low-density lipoprotein: endopepsis.

    PubMed

    Fossel, E T; Zanella, C L; Fletcher, J G; Hui, K K

    1994-03-01

    Peroxidized low-density lipoprotein (p-LDL) has been previously demonstrated to be preferentially cytotoxic to certain malignant cells compared to normal cells of the same type. We present evidence that p-LDL is at least partially taken up through the LDL receptor and that it becomes localized in lysosomes. The integrity of lysosomes of p-LDL-treated cells is compromised, and leakage of their contents into the cytosol occurs. This leakage occurs early and precedes mitochondrial dysfunction. Brefeldin A inhibits this leakage, perhaps by interfering with the traffic between endosomes and lysosomes. Electron micrographs taken at various times suggest a mechanism of cell death which resembles certain aspects of the broad definition of apoptosis. However, we suggest that the cell death observed following p-LDL-induced release of lysosomal contents is essentially unique, with released lysosomal enzymes degrading the cell from within. We suggest that this process should be described as endopepsis. PMID:8118812

  13. Antioxidant properties of macrophages toward low-density lipoprotein.

    PubMed

    Baoutina, A; Dean, R T; Jessup, W

    2001-01-01

    Oxidative modification of low-density lipoprotein (LDL) has been implicated in atherosclerosis. Intensive scientific efforts over the last two decades have focused on the elucidation of the mechanisms by which LDL is oxidized in vivo. A wealth of in vitro studies has demonstrated that the cell types present in atherosclerotic lesions, including monocyte/macrophages, quantitatively one of the most important cell types in plaque development, promote LDL oxidation. The mechanisms of cellular prooxidant activities have been extensively investigated. Fewer studies have addressed possible protective properties of the cells in LDL oxidation. This review summarizes recent observations of antioxidant, and potentially antiatherogenic, activities of macrophages toward LDL, including macrophage-mediated detoxification of lipid and protein hydroperoxides, metal sequestration and the generation of compounds with antioxidant properties. These activities could contribute to the net effect of macrophages on deleterious LDL oxidation and to the complex role of these cells in lesion development. PMID:11413045

  14. Change in composition of high density lipoprotein during gemfibrozil therapy.

    PubMed

    Sorisky, A; Ooi, T C; Simo, I E; Meuffels, M; Hindmarsh, J T; Nair, R

    1987-10-01

    We investigated the high density lipoprotein cholesterol (HDL-C) response in 20 middle-aged males during a 12-week course of gemfibrozil. Three aspects of the increase in HDL-C (25%) were studied and our observations are as follows: (1) subfraction analysis showed that HDL3-C rose earlier and to a larger extent (28%) than HDL2-C (15%), (2) analysis of variance group--time interaction effect and correlation studies of HDL-C and total triglycerides suggest the increase in HDL-C was due to a direct effect of gemfibrozil on HDL metabolism, and (3) HDL-C was the only one of 4 HDL components to increase. Apoprotein A-I (apo A-I) and HDL-phospholipid (HDL-PL) did not change, and HDL-triglyceride (HDL-TG) decreased. This pattern is consistent with a change in composition of HDL, i.e. cholesterol enrichment and triglyceride depletion. PMID:3118893

  15. High-density lipoprotein and prostate cancer: an overview.

    PubMed

    Kotani, Kazuhiko; Sekine, Yoshitaka; Ishikawa, Shizukiyo; Ikpot, Imoh Z; Suzuki, Kazuhiro; Remaley, Alan T

    2013-09-01

    Prostate cancer is a common disease in modern, developed societies and has a high incidence and mortality. High-density lipoprotein cholesterol (HDL-C) has recently received much attention as a possible risk marker of prostate cancer development and prognosis. In the present article, we summarized findings from epidemiologic studies of the association between HDL-C and prostate cancer. Low HDL-C level was found to be a risk and prognostic factor of prostate cancer in several epidemiologic studies, although the overall linkage between HDL and prostate cancer has not been definitively established. The mechanisms for this association remain uncertain; however, limited data from experimental studies imply a possible role of HDL in the pathophysiology of prostate cancer. More epidemiologic research, in combination with experimental studies, is needed in this field. PMID:23985823

  16. Novel therapeutic agents for lowering low density lipoprotein cholesterol.

    PubMed

    Joy, Tisha R

    2012-07-01

    Elevated low density lipoprotein cholesterol (LDL-C) levels have been associated with an increased risk for cardiovascular disease (CVD). Despite a 25-30% reduction in CVD risk with LDL-C reducing strategies, there is still a significant residual risk. Moreover, achieving target LDL-C values in individuals at high CVD risk is sometimes limited because of tolerability and/or efficacy. Thus, novel therapeutic agents are currently being developed to lower LDL-C levels further. This review will highlight some of these therapeutic agents including anti-sense oligonucleotides focused on apolipoprotein B, proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, microsomal triglyceride transfer protein inhibitors, and thyromimetics. For each therapeutic class, an overview of the mechanism of action, pharmacokinetic data, and efficacy/safety evidence will be provided. PMID:22465160

  17. Biominetic High Density Lipoproteins for the Delivery of Therapeutic Oligonucleotides

    NASA Astrophysics Data System (ADS)

    Tripathy, Sushant

    Advances in nanotechnology have brought about novel inorganic and hybrid nanoparticles with unique physico-chemical properties that make them suitable for a broad range of applications---from nano-circuitry to drug delivery. A significant part of those advancements have led to ground-breaking discoveries that have changed the approaches to formulation of therapeutics against diseases, such as cancer. Now-a-days the focus does not lie solely on finding a candidate small-molecule therapeutic with minimal adverse effects, but researchers are looking up to nanoparticles to improve biodistribution and biocompatibility profile of clinically proven therapeutics. The plethora of conjugation chemistries offered by currently extant inorganic nanoparticles have, in recent years, led to great leaps in the field of biomimicry---a modality that promises high biocompatibility. Further, in the pursuit of highly specific therapeutic molecules, researchers have turned to silencing oligonucleotides and some have already brought together the strengths of nanoparticles and silencing oligonucleotides in search of an efficacious therapy for cancer with minimal adverse effects. This dissertation work focuses on such a biomimetic platform---a gold nanoparticle based high density lipoprotein biomimetic (HDL NP), for the delivery of therapeutic oligonucleotides. The first chapter of this body of work introduces the molecular target of the silencing oligonucleotides---VEGFR2, and its role in the progression of solid tumor cancers. The background information also covers important aspects of natural high density lipoproteins (HDL), especially their innate capacity to bind and deliver exogenous and endogenous silencing oligonucleotides to tissues that express their high affinity receptor SRB1. We subsequently describe the synthesis of the biomimetic HDL NP and its oligonucleotide conjugates, and establish their biocompatibility. Further on, experimental data demonstrate the efficacy of silencing oligonucleotides conjugated HDL NPs in regulating the expression and function of VEGFR2 in cultured endothelial cells. Finally, the efficacy of the conjugates in two animal models of angiogenesis is presented.

  18. Fitness, Heart Disease, and High-Density Lipoproteins: A Look at the Relationships.

    ERIC Educational Resources Information Center

    McCunney, Robert J.

    1987-01-01

    The role of fitness in preventing coronary heart disease is explored. Research on high-density lipoprotein, which has been found to be one of the most critical determinants of risk, is reviewed. The relationship between fitness, high-density lipoprotein, and coronary heart disease is assessed, and clinical implications are spelled out. (MT)

  19. Degradation of high density lipoprotein in cultured rat luteal cells

    SciTech Connect

    Rajan, V.P.; Menon, K.M.J.

    1986-03-01

    In rat ovary luteal cells, degradation of high density lipoprotein (HDL) to tricholoracetic acid (TCA)-soluble products accounts for only a fraction of the HDL-derived cholesterol used for steroidogenesis. In this study the authors have investigated the fate of /sup 125/I)HDL bound to cultured luteal cells using pulse-chase technique. Luteal cell cultures were pulse labeled with (/sup 125/I)HDL/sub 3/ and reincubated in the absence of HDL. By 24 h about 50% of the initallay bound radioactivity was released into the medium, of which 60-65% could be precipitated with 10% TCA. Gel filtration of the chase incubation medium on 10% agarose showed that the amount of TCA-soluble radioactivity was nearly completely accounted for by a sharp peak in the low molecular weight region which was identified as 96% monoiodotyrosine by paper chromatography. The TCA-precipitable radioactivity was nearly completely accounted for by a sharp peak in the low molecular weight region which was identified as 96% monoiodotyrosine by paper chromatography. The TCA-precipitable radioactivity eluted over a wide range of molecular weights (15,000-80,000), and there was very little intact HDL present. Electrophoresis of the chase medium showed that component of the TCA-precipitable portion had mobility similar to apo AI. Lysosomal inhibitors of receptor-mediated endocytosis had no effect on the composition or quantity of radioactivity released during chase incubation. The results show that HDL/sub 3/ binding to luteal cells is followed by complete degradation of the lipoprotein, although the TCA-soluble part does not reflect the extent of degradation.

  20. Lipoprotein receptors in copper-deficient rats: high density lipoprotein binding to liver membranes

    SciTech Connect

    Hassel, C.A.; Lei, K.Y.; Marchello, J.A.

    1986-03-05

    In copper-deficient rats, the observed hyperlipoproteinemia was mainly due to the elevation in high density lipoproteins (HDL). This study was designed to determine whether an impairment in the binding of HDL to liver membrane is responsible for the hyperlipoproteinemia. Sixty male Sprague-Dawley rats were randomly divided into 2 treatments, namely copper (Cu) deficient and adequate (less than 1 and 8 mg Cu/kg of diet). After 8 weeks, plasma, heart and liver tissues were obtained. Reduction in liver Cu content and elevation in heart to body weight ratio and plasma cholesterol confirmed that rats fed the test diet were Cu-deficient. Plasma HDL isolated from both Cu-deficient and control rats were iodinated and bound to liver membranes prepared from rats of each treatment. Binding of /sup 125/I-HDL was competitively inhibited by unlabelled rat HDL from both treatments, but not by human LDL. Scatchard analysis of specific binding data showed that maximal /sup 125/I-HDL binding (per mg membrane protein) to membranes prepared from Cu-deficient rats was not lower than controls. Furthermore, the amount of /sup 125/I-HDL from deficient rats specifically bound to liver membranes prepared from either treatment was not less than the amount of /sup 125/I-HDL from control rats bound to the same membranes. The data suggest that the hyperlipoproteinemia in Cu-deficient rats may not have resulted from a decrease in the number of hepatic HDL binding sites.

  1. Effects of high density lipoprotein subfractions on cholesterol homeostasis in human fibroblasts and arterial smooth muscle cells.

    PubMed

    Oram, J F

    1983-01-01

    Ultracentrifugally isolated high density lipoprotein (HDL) particles of d greater than 1.125 g/ml promote net transport of cholesterol from cultured cells. Consequently, when cultured human fibroblasts and arterial smooth muscle cells were incubated with HDL3 (d = 1.125-1.21 g/ml) and "very high" density lipoprotein (VHDL, d = 1.21-1.25 g/ml), low density lipoprotein (LDL) receptor activity was induced and the rate of LDL degradation by the cells was increased. Enhancement of LDL degradation by HDL3 and VHDL was sustained over incubation periods of 5 days at medium LDL concentrations greater than needed to saturate the LDL receptors. Even during these long-term incubations with LDL, HDL3 and VHDL caused marked reductions in cellular cholesterol content. Thus, an increase in the rate of cholesterol transport from cells may lead to a steady-state decrease in cellular cholesterol content and a sustained increase in the rate of clearance of LDL from the extracellular fluid. In contrast to the effects of HDL3 and VHDL, the major subclasses of HDL2 (HDL2b, d = 1.063-1.100 g/ml; HDL2a, d = 1.100-1.125 g/ml) did not promote net cholesterol transport from cells. Moreover, by apparent direct blockage of the effects that HDL3 and VHDL had on cholesterol transport, HDL2 reversed the increased rate of LDL degradation induced by HDL3 and VHDL. These results suggest that the relative proportion of HDL subfractions in the extracellular fluid may be an important determinant of both the rate of cholesterol transport from cells and the rate of receptor-mediated catabolism of LDL. PMID:6312947

  2. Lysis of Trypanosoma brucei by a toxic subspecies of human high density lipoprotein.

    PubMed

    Hajduk, S L; Moore, D R; Vasudevacharya, J; Siqueira, H; Torri, A F; Tytler, E M; Esko, J D

    1989-03-25

    Trypanosoma brucei brucei is an important pathogen of domestic cattle in sub-Saharan Africa and is closely related to the human sleeping sickness parasites, Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense. However, T. b. brucei is non-infectious to humans. The restriction of the host range of T. b. brucei results from the sensitivity of the parasite to lysis by toxic human high density lipoproteins (HDL) (Rifkin, M. R. (1978) Proc. Natl. Acad. Sci. U.S.A. 75, 3450-3454). We show in this report that trypanosome lytic activity is not a universal feature of all human HDL particles but rather that it is associated with a minor subclass of HDL. We have purified the lytic activity about 8,000-fold and have identified and characterized the subspecies of HDL responsible for trypanosome lysis. This class of HDL has a relative molecular weight of 490,000, a buoyant density of 1.21-1.24 g/ml, and a particle diameter of 150-210 A. It contains apolipoproteins AI, AII, CI, CII, and CIII, and monoclonal antibodies against apo-AI and apo-AII inhibit trypanocidal activity. In addition to these common apolipoproteins, the particles also contain at least three unique proteins, as measured by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under nonreducing conditions. Treatment of the particles with dithiothreitol resulted in the disappearance of two of the proteins and abolished trypanocidal activity. Two-dimensional gel electrophoresis showed that these proteins were a disulfide-linked trimer of 45,000, 36,000, and 13,500-Da polypeptides and dimers of the 36,000- and 13,500-Da polypeptides or of 65,000- and 8,500-Da polypeptides. Studies on the lysis of T. b. brucei by the purified particle suggest that the lytic pathway may involve the uptake of the trypanocidal subspecies of HDL by endocytosis. PMID:2494183

  3. Native low density lipoprotein promotes lipid raft formation in macrophages

    PubMed Central

    SONG, JIAN; PING, LING-YAN; DUONG, DUC M.; GAO, XIAO-YAN; HE, CHUN-YAN; WEI, LEI; WU, JUN-ZHU

    2016-01-01

    Oxidized low-density lipoprotein (LDL) has an important role in atherogenesis; however, the mechanisms underlying cell-mediated LDL oxidation remain to be elucidated. The present study investigated whether native-LDL induced lipid raft formation, in order to gain further insight into LDL oxidation. Confocal microscopic analysis revealed that lipid rafts were aggregated or clustered in the membrane, which were colocalized with myeloperoxidase (MPO) upon native LDL stimulation; however, in the presence of methyl-β-cyclodextrin (MβCD), LDL-stimulated aggregation, translocation, and colocalization of lipid rafts components was abolished.. In addition, lipid raft disruptors MβCD and filipin decreased malondialdehyde expression levels. Density gradient centrifugation coupled to label-free quantitative proteomic analysis identified 1,449 individual proteins, of which 203 were significantly upregulated following native-LDL stimulation. Functional classification of the proteins identified in the lipid rafts revealed that the expression levels of translocation proteins were upregulated. In conclusion, the results of the present study indicated that native-LDL induced lipid raft clustering in macrophages, and the expression levels of several proteins were altered in the stimulated macrophages, which provided novel insights into the mechanism underlying LDL oxidation. PMID:26781977

  4. Effect of a Moderate Fat Diet With and Without Avocados on Lipoprotein Particle Number, Size and Subclasses in Overweight and Obese Adults: A Randomized, Controlled Trial

    PubMed Central

    Wang, Li; Bordi, Peter L.; Fleming, Jennifer A.; Hill, Alison M.; Kris‐Etherton, Penny M.

    2015-01-01

    Background Avocados are a nutrient‐dense source of monounsaturated fatty acids (MUFA) that can be used to replace saturated fatty acids (SFA) in a diet to lower low density lipoprotein cholesterol (LDL‐C). Well‐controlled studies are lacking on the effect of avocado consumption on cardiovascular disease (CVD) risk factors. Methods and Results A randomized, crossover, controlled feeding trial was conducted with 45 overweight or obese participants with baseline LDL‐C in the 25th to 90th percentile. Three cholesterol‐lowering diets (6% to 7% SFA) were fed (5 weeks each): a lower‐fat diet (LF: 24% fat); 2 moderate‐fat diets (34% fat) provided similar foods and were matched for macronutrients and fatty acids: the avocado diet (AV) included one fresh Hass avocado (136 g) per day, and the moderate‐fat diet (MF) mainly used high oleic acid oils to match the fatty acid content of one avocado. Compared with baseline, the reduction in LDL‐C and non‐high‐density lipoprotein (HDL) cholesterol on the AV diet (−13.5 mg/dL, −14.6 mg/dL) was greater (P<0.05) than the MF (−8.3 mg/dL, −8.7 mg/dL) and LF (−7.4 mg/dL, −4.8 mg/dL) diets. Furthermore, only the AV diet significantly decreased LDL particle number (LDL‐P, −80.1 nmol/L, P=0.0001), small dense LDL cholesterol (LDL3+4, −4.1 mg/dL, P=0.04), and the ratio of LDL/HDL (−6.6%, P<0.0001) from baseline. Conclusions Inclusion of one avocado per day as part of a moderate‐fat, cholesterol‐lowering diet has additional LDL‐C, LDL‐P, and non‐HDL‐C lowering effects, especially for small, dense LDL. Our results demonstrate that avocados have beneficial effects on cardio‐metabolic risk factors that extend beyond their heart‐healthy fatty acid profile. Clinical Trial Registration URL: http://www.clinicaltrials.gov. Unique identifier: NCT01235832. PMID:25567051

  5. Isolation and Characterization of an Abnormal High Density Lipoprotein in Tangier Disease

    PubMed Central

    Assmann, Gerd; Herbert, Peter N.; Fredrickson, Donald S.; Forte, Trudy

    1977-01-01

    The nature of the high density lipoproteins has been investigated in five patients homozygous for Tangier disease (familial high density lipoprotein deficiency). It has been established that Tangier high density lipoproteins, as isolated by ultracentrifugation, are morphologically heterogenous and contain several proteins (Apo B, albumin, and Apo A-II). An abnormal lipoprotein has been isolated from the d = 1.063-1.21 g/ml ultracentrifugal fraction by agarose-column chromatography which contains apoprotein A-II as the sole protein constituent. In negative-stain electron microscopy, these lipoproteins appeared as spherical particles 55-75 Å in diameter. By a variety of criteria (immunochemical, polyacrylamide electrophoresis, amino acid composition, and fluorescence measurements), apoprotein A-I the major apoprotein of normal high density lipoproteins and the C apoproteins were absent from this lipoprotein. As demonstrated by 125I very low density lipoprotein incubation experiments with Tangier plasma, C apoproteins did not associate with lipoproteins of d = 1.063-1.21 g/ml. Tangier apoprotein A-II, isolated to homogeneity by delipidation of the apoprotein A-II-containing lipoprotein or Sephadex G-200 guanidine-HCl chromatography of the d = 1.063-1.21 g/ml fraction, was indistinguishable from control apoprotein A-II with respect to amino acid composition and migration of tryptic peptides in urea-polyacrylamide electrophoresis. The ability of Tangier apoprotein A-II to bind phospholipid was demonstrated by in vitro reconstitution experiments and morphological and chemical analysis of lipid-protein complexes. It is concluded that normal high density lipoproteins, as defined by polypeptide composition and morphological appearance, are absent from Tangier plasma and that as a consequence, the impairment of C apoprotein metabolism contributes to the hypertriglyceridemia and fasting chylomicronemia observed in these patients. Images PMID:194920

  6. Low High-Density Lipoprotein and Risk of Myocardial Infarction

    PubMed Central

    Ramirez, A.; Hu, P. P.

    2015-01-01

    Low HDL is an independent risk factor for myocardial infarction. This paper reviews our current understanding of HDL, HDL structure and function, HDL subclasses, the relationship of low HDL with myocardial infarction, HDL targeted therapy, and clinical trials and studies. Furthermore potential new agents, such as alirocumab (praluent) and evolocumab (repatha) are discussed. PMID:26692765

  7. Low High-Density Lipoprotein and Risk of Myocardial Infarction.

    PubMed

    Ramirez, A; Hu, P P

    2015-01-01

    Low HDL is an independent risk factor for myocardial infarction. This paper reviews our current understanding of HDL, HDL structure and function, HDL subclasses, the relationship of low HDL with myocardial infarction, HDL targeted therapy, and clinical trials and studies. Furthermore potential new agents, such as alirocumab (praluent) and evolocumab (repatha) are discussed. PMID:26692765

  8. Acrolein Impairs the Cholesterol Transport Functions of High Density Lipoproteins

    PubMed Central

    Chadwick, Alexandra C.; Holme, Rebecca L.; Chen, Yiliang; Thomas, Michael J.; Sorci-Thomas, Mary G.; Silverstein, Roy L.; Pritchard, Kirkwood A.; Sahoo, Daisy

    2015-01-01

    High density lipoproteins (HDL) are considered athero-protective, primarily due to their role in reverse cholesterol transport, where they transport cholesterol from peripheral tissues to the liver for excretion. The current study was designed to determine the impact of HDL modification by acrolein, a highly reactive aldehyde found in high abundance in cigarette smoke, on the cholesterol transport functions of HDL. HDL was chemically-modified with acrolein and immunoblot and mass spectrometry analyses confirmed apolipoprotein crosslinking, as well as acrolein adducts on apolipoproteins A-I and A-II. The ability of acrolein-modified HDL (acro-HDL) to serve as an acceptor of free cholesterol (FC) from COS-7 cells transiently expressing SR-BI was significantly decreased. Further, in contrast to native HDL, acro-HDL promotes higher neutral lipid accumulation in murine macrophages as judged by Oil Red O staining. The ability of acro-HDL to mediate efficient selective uptake of HDL-cholesteryl esters (CE) into SR-BI-expressing cells was reduced compared to native HDL. Together, the findings from our studies suggest that acrolein modification of HDL produces a dysfunctional particle that may ultimately promote atherogenesis by impairing functions that are critical in the reverse cholesterol transport pathway. PMID:25849485

  9. Micro-RNAs and High-Density Lipoprotein Metabolism.

    PubMed

    Canfrán-Duque, Alberto; Lin, Chin-Sheng; Goedeke, Leigh; Suárez, Yajaira; Fernández-Hernando, Carlos

    2016-06-01

    Improved prevention and treatment of cardiovascular diseases is one of the challenges in Western societies, where ischemic heart disease and stroke are the leading cause of death. Early epidemiological studies have shown an inverse correlation between circulating high-density lipoprotein-cholesterol (HDL-C) and cardiovascular diseases. The cardioprotective effect of HDL is because of its ability to remove cholesterol from plaques in the artery wall to the liver for excretion by a process known as reverse cholesterol transport. Numerous studies have reported the role that micro-RNAs (miRNA) play in the regulation of the different steps in reverse cholesterol transport, including HDL biogenesis, cholesterol efflux, and cholesterol uptake in the liver and bile acid synthesis and secretion. Because of their ability to control different aspects of HDL metabolism and function, miRNAs have emerged as potential therapeutic targets to combat cardiovascular diseases. In this review, we summarize the recent advances in the miRNA-mediated control of HDL metabolism. We also discuss how HDL particles serve as carriers of miRNAs and the potential use of HDL-containing miRNAs as cardiovascular diseases biomarkers. PMID:27079881

  10. Ethanol enhances de novo synthesis of high density lipoprotein cholesterol

    SciTech Connect

    Cluette, J.E.; Mulligan, J.J.; Noring, R.; Doyle, K.; Hojnacki, J.

    1984-05-01

    Male squirrel monkeys fed ethanol at variable doses were used to assess whether alcohol enhances de novo synthesis of high density lipoprotein (HDL) cholesterol in vivo. Monkeys were divided into three groups: 1) controls fed isocaloric liquid diet; 2) low ethanol monkeys fed liquid diet with vodka substituted isocalorically for carbohydrate at 12% of calories; and 3) High Ethanol animals fed diet plus vodka at 24% of calories. High Ethanol primates had significantly higher levels of HDL nonesterified cholesterol than Control and Low Ethanol animals while serum glutamate oxaloacetate transaminase was similar for the three treatments. There were no significant differences between the groups in HDL cholesteryl ester mass or specific activity following intravenous injection of labeled mevalonolactone. By contrast, High Ethanol monkeys had significantly greater HDL nonesterified cholesterol specific activity with approximately 60% of the radioactivity distributed in the HDL/sub 3/ subfraction. This report provides the first experimental evidence that ethanol at 24% of calories induces elevations in HDL cholesterol in primates through enhanced de novo synthesis without adverse effects on liver function.

  11. Cigarette smoking impairs hepatic uptake of high density lipoproteins.

    PubMed

    Mulligan, J J; Cluette, J E; Kew, R R; Stack, D J; Hojnacki, J L

    1983-05-16

    The effect of chronic inhalation of cigarette smoke on hepatic uptake of high density lipoproteins (HDL) in White Carneau pigeons was examined. Four treatment groups included: 1) Shelf Control birds fed a chow diet and retained in their cages; 2) Sham pigeons fed a cholesterol-saturated fat diet and exposed to fresh air by a smoking machine; 3) Low nicotine-low carbon monoxide (LoLo) animals also fed the cholesterol diet and exposed to low concentrations of these cigarette smoke products; and 4) High nicotine-high carbon monoxide (HiHi) birds fed the cholesterol diet and subjected to high concentrations of these components. Livers from both smoke exposed groups contained significantly more triglyceride than those from Sham animals while livers from HiHi birds alone had elevated concentrations of protein. Liver slices from LoLo and HiHi pigeons incorporated significantly less HDL 3H free and esterified cholesterol and HDL 14C apoprotein from media during in vitro incubation than livers from Sham birds. Impaired hepatic uptake of HDL suggests a permanent alteration in liver function resulting from chronic exposure to tobacco smoke and may represent one mechanism by which cigarette smoking attenuates HDL's anti-atherogenic properties. PMID:6847683

  12. In vivo protection against endotoxin by plasma high density lipoprotein.

    PubMed Central

    Levine, D M; Parker, T S; Donnelly, T M; Walsh, A; Rubin, A L

    1993-01-01

    Overwhelming bacterial infection is accompanied by fever, hypotension, disseminated intravascular coagulation, and multiple organ failure leading to death in 30-80% of cases. These classical symptoms of septic shock are caused by potent cytokines that are produced in response to endotoxin released from Gram-negative bacteria. Treatments with antibodies and receptor antagonists to block endotoxin or cytokine mediators have given mixed results in clinical trials. High density lipoprotein (HDL) is a natural component of plasma that is known to neutralize endotoxin in vitro. We report here that raising the plasma HDL concentration protects mice against endotoxin in vivo. Transgenic mice with 2-fold-elevated plasma HDL levels had more endotoxin bound to HDL, lower plasma cytokine levels, and improved survival rates compared with low-HDL mice. Intravenous infusion of HDL also protected mice, but only when given as reconstituted HDL prepared from phospholipid and either HDL apoprotein or an 18-amino acid peptide synthesized to mimic the structure of apolipoprotein A-I of HDL. Intact plasma HDL was mildly toxic, and HDL apoprotein was ineffective. The effectiveness of the reconstituted peptide renders very unlikely any significant contribution to protection by trace proteins in apo-HDL. These data suggest a simple leaflet insertion model for binding and neutralization of lipopolysaccharide by phospholipid on the surface of HDL. Plasma HDL may normally act to protect against endotoxin; this protection may be augmented by administration of reconstituted HDL or reconstituted peptides. Images Fig. 1 Fig. 2 Fig. 3 PMID:8265667

  13. High-density lipoprotein, beta cells, and diabetes .

    PubMed

    von Eckardstein, Arnold; Widmann, Christian

    2014-08-01

    High-density lipoproteins (HDLs) exert a series of potentially beneficial effects on many cell types including anti-atherogenic actions on the endothelium and macrophage foam cells. HDLs may also exert anti-diabetogenic functions on the beta cells of the endocrine pancreas, notably by potently inhibiting stress-induced cell death and enhancing glucose-stimulated insulin secretion. HDLs have also been found to stimulate insulin-dependent and insulin-independent glucose uptake into skeletal muscle, adipose tissue, and liver. These experimental findings and the inverse association of HDL-cholesterol levels with the risk of diabetes development have generated the notion that appropriate HDL levels and functionality must be maintained in humans to diminish the risks of developing diabetes. In this article, we review our knowledge on the beneficial effects of HDLs in pancreatic beta cells and how these effects are mediated. We discuss the capacity of HDLs to modulate endoplasmic reticulum stress and how this affects beta-cell survival. We also point out the gaps in our understanding on the signalling properties of HDLs in beta cells. Hopefully, this review will foster the interest of scientists in working on beta cells and diabetes to better define the cellular pathways activated by HDLs in beta cells. Such knowledge will be of importance to design therapeutic tools to preserve the proper functioning of the insulin-secreting cells in our body. PMID:24903496

  14. High Density Lipoprotein Cholesterol Increasing Therapy: The Unmet Cardiovascular Need

    PubMed Central

    Cimmino, Giovanni; Ciccarelli, Giovanni; Morello, Alberto; Ciccarelli, Michele; Golino, Paolo

    2015-01-01

    Despite aggressive strategies are now available to reduce LDL-cholesterol, the risk of cardiovascular events in patients with coronary artery disease remains substantial. Several preclinical and clinical studies have shown that drug therapy ultimately leads to a regression of the angiographic lesions but also results in a reduction in cardiovascular events. The dramatic failure of clinical trials evaluating the cholesterol ester transfer protein (CEPT) inhibitors, torcetrapib and dalcetrapib, has led to considerable doubt about the value of the current strategy to raise high-density lipoprotein cholesterol (HDL-C) as a treatment for cardiovascular disease. These clinical results, as well as animal studies, have revealed the complexity of HDL metabolism, assessing a more important role of functional quality compared to circulating quantity of HDL. As a result, HDL-based therapeutic interventions that maintain or enhance HDL functionality, such as improving its main property, the reverse cholesterol transport, require closer investigation. In this review, we will discuss HDL metabolism and function, clinical-trial data available for HDL-raising agents, and potential strategies for future HDL-based therapies. PMID:26535185

  15. High-density lipoprotein endocytosis in endothelial cells

    PubMed Central

    Fruhwürth, Stefanie; Pavelka, Margit; Bittman, Robert; Kovacs, Werner J; Walter, Katharina M; Röhrl, Clemens; Stangl, Herbert

    2013-01-01

    AIM: To describe the way stations of high-density lipoprotein (HDL) uptake and its lipid exchange in endothelial cells in vitro and in vivo. METHODS: A combination of fluorescence microscopy using novel fluorescent cholesterol surrogates and electron microscopy was used to analyze HDL endocytosis in great detail in primary human endothelial cells. Further, HDL uptake was quantified using radio-labeled HDL particles. To validate the in vitro findings mice were injected with fluorescently labeled HDL and particle uptake in the liver was analyzed using fluorescence microscopy. RESULTS: HDL uptake occurred via clathrin-coated pits, tubular endosomes and multivesicular bodies in human umbilical vein endothelial cells. During uptake and resecretion, HDL-derived cholesterol was exchanged at a faster rate than cholesteryl oleate, resembling the HDL particle pathway seen in hepatic cells. In addition, lysosomes were not involved in this process and thus HDL degradation was not detectable. In vivo, we found HDL mainly localized in mouse hepatic endothelial cells. HDL was not detected in parenchymal liver cells, indicating that lipid transfer from HDL to hepatocytes occurs primarily via scavenger receptor, class B, type I mediated selective uptake without concomitant HDL endocytosis. CONCLUSION: HDL endocytosis occurs via clathrin-coated pits, tubular endosomes and multivesicular bodies in human endothelial cells. Mouse endothelial cells showed a similar HDL uptake pattern in vivo indicating that the endothelium is one major site of HDL endocytosis and transcytosis. PMID:24340136

  16. Targeting high-density lipoproteins: update on a promising therapy.

    PubMed

    Verdier, Cline; Martinez, Laurent O; Ferrires, Jean; Elbaz, Meyer; Genoux, Annelise; Perret, Bertrand

    2013-11-01

    Numerous epidemiological studies have demonstrated the atheroprotective roles of high density lipoproteins (HDL), so that HDL is established as an independent negative risk factor. The protective effect of HDL against atherosclerosis is mainly attributed to their capacity to bring peripheral excess cholesterol back to the liver for further elimination into the bile. In addition, HDL can exert other protective functions on the vascular wall, through their anti-inflammatory, antioxidant, antithrombotic and cytoprotective properties. HDL-targeted therapy is thus an innovative approach against cardiovascular risk and atherosclerosis. These pleiotropic atheroprotective properties of HDL have led experts to believe that "HDL-related therapies" represent the most promising next step in fighting against atherosclerosis. However, because of the heterogeneity of HDL functions, targeting HDL is not a simple task and HDL therapies that lower cardiovascular risk are NOT yet available. In this paper, an overview is presented about the therapeutic strategies currently under consideration to raise HDL levels and/or functions. Recently, clinical trials of drugs targeting HDL-C levels have disappointingly failed, suggesting that HDL functions through specific mechanisms should be targeted rather than increasing per se HDL levels. PMID:24074699

  17. Is the oxidation of high-density lipoprotein lipids different than the oxidation of low-density lipoprotein lipids?

    PubMed

    Thomas, M J; Chen, Q; Zabalawi, M; Anderson, R; Wilson, M; Weinberg, R; Sorci-Thomas, M G; Rudel, L L

    2001-02-13

    This article gives detailed insight into the kinetics of high-density lipoprotein (HDL) oxidation catalyzed by azobis(2-amidinopropane).dihydrochloride (ABAP) or by copper. ABAP initialized oxidation of human HDL 3-4 times faster than non-human primate HDL with a similar composition. The oxidizability of non-human primate HDL was 1000 times lower than the oxidizability calculated from rate constants derived from liposome oxidation, suggesting that there is a slow step in HDL oxidation not present in liposomes. Saturable binding of copper to HDL was a significant feature of copper-catalyzed oxidation. Binding constants (K(m)) for non-human primate HDL were 2-3-fold lower than those for human HDL. Copper-catalyzed oxidation of non-human primate HDL was slower than that of human HDL, but human HDL(2) and HDL(3) oxidized at about the same rate. Overall, the kinetics describing the oxidation of HDL were mechanistically similar to those reported for LDL, suggesting that HDL lipids were as easily oxidized as LDL lipids and that HDL will be easily oxidized in vivo when exposed to agents that oxidize LDL. PMID:11327832

  18. Green tea catechins prevent low-density lipoprotein oxidation via their accumulation in low-density lipoprotein particles in humans.

    PubMed

    Suzuki-Sugihara, Norie; Kishimoto, Yoshimi; Saita, Emi; Taguchi, Chie; Kobayashi, Makoto; Ichitani, Masaki; Ukawa, Yuuichi; Sagesaka, Yuko M; Suzuki, Emiko; Kondo, Kazuo

    2016-01-01

    Green tea is rich in polyphenols, including catechins which have antioxidant activities and are considered to have beneficial effects on cardiovascular health. In the present study, we investigated the effects of green tea catechins on low-density lipoprotein (LDL) oxidation in vitro and in human studies to test the hypothesis that catechins are incorporated into LDL particles and exert antioxidant properties. In a randomized, placebo-controlled, double-blind, crossover trial, 19 healthy men ingested green tea extract (GTE) in the form of capsules at a dose of 1 g total catechin, of which most (>99%) was the gallated type. At 1 hour after ingestion, marked increases of the plasma concentrations of (-)-epigallocatechin gallate and (-)-epicatechin gallate were observed. Accordingly, the plasma total antioxidant capacity was increased, and the LDL oxidizability was significantly reduced by the ingestion of GTE. We found that gallated catechins were incorporated into LDL particles in nonconjugated forms after the incubation of GTE with plasma in vitro. Moreover, the catechin-incorporated LDL was highly resistant to radical-induced oxidation in vitro. An additional human study with 5 healthy women confirmed that GTE intake sufficiently increased the concentration of gallated catechins, mainly in nonconjugated forms in LDL particles, and reduced the oxidizability of LDL. In conclusion, green tea catechins are rapidly incorporated into LDL particles and play a role in reducing LDL oxidation in humans, which suggests that taking green tea catechins is effective in reducing atherosclerosis risk associated with oxidative stress. PMID:26773777

  19. Biodegradable synthetic high-density lipoprotein nanoparticles for atherosclerosis.

    PubMed

    Marrache, Sean; Dhar, Shanta

    2013-06-01

    Atherosclerosis remains one of the most common causes of death in the United States and throughout the world because of the lack of early detection. Macrophage apoptosis is a major contributor to the instability of atherosclerotic lesions. Development of an apoptosis targeted high-density lipoprotein (HDL)-mimicking nanoparticle (NP) to carry contrast agents for early detection of vulnerable plaques and the initiation of preventative therapies that exploit the vascular protective effects of HDL can be attractive for atherosclerosis. Here, we report the construction of a synthetic, biodegradable HDL-NP platform for detection of vulnerable plaques by targeting the collapse of mitochondrial membrane potential that occurs during apoptosis. This HDL mimic contains a core of biodegradable poly(lactic-co-glycolic acid), cholesteryl oleate, and a phospholipid bilayer coat that is decorated with triphenylphosphonium (TPP) cations for detection of mitochondrial membrane potential collapse. The lipid layer provides the surface for adsorption of apolipoprotein (apo) A-I mimetic 4F peptide, and the core contains diagnostically active quantum dots (QDs) for optical imaging. In vitro uptake, detection of apoptosis, and cholesterol binding studies indicated promising detection ability and therapeutic potential of TPP-HDL-apoA-I-QD NPs. In vitro studies indicated the potential of these NPs in reverse cholesterol transport. In vivo biodistribution and pharmacokinetics indicated favorable tissue distribution, controlled pharmacokinetic parameters, and significant triglyceride reduction for i.v.-injected TPP-HDL-apoA-I-QD NPs in rats. These HDL NPs demonstrate excellent biocompatibility, stability, nontoxic, and nonimmunogenic properties, which prove to be promising for future translation in early plaque diagnosis and might find applications to prevent vulnerable plaque progression. PMID:23671083

  20. Reconstituted High-Density Lipoprotein Modulates Activation of Human Leukocytes

    PubMed Central

    Kropf, Alain; Miescher, Sylvia; Spycher, Martin O.; Rieben, Robert

    2013-01-01

    An anti-inflammatory effect of reconstituted High Density Lipoprotein (rHDL) has been demonstrated in atherosclerosis and in sepsis models. An increase of adhesion molecules as well as tissue factor expression on endothelial cells in response to inflammatory or danger signals are attenuated by the treatment with rHDL. Here we show the inhibitory effect of rHDL on the activation of human leukocytes in a whole blood assay as well as on monocyte-derived human dendritic cells (DC). Multiplex analysis of human whole blood showed that phytohaemagglutinin (PHA)-induced secretion of the cytokines IL-1β, IL-1RA, IL-2R, IL-6, IL-7, IL-12(p40), IL-15 and IFN-α was inhibited. Furthermore, an inhibitory effect on the production of the chemokines CCL-2, CCL-4, CCL-5, CXCL-9 and CXCL-10 was observed. Activation of granulocytes and CD14+ monocytes by PHA is inhibited dose-dependently by rHDL shown as decreased up-regulation of ICAM-1 surface expression. In addition, we found a strong inhibitory effect of rHDL on toll-like receptor 2 (TLR2)- and TLR4-mediated maturation of DC. Treatment of DC with rHDL prevented the up-regulation of cell surface molecules CD80, CD83 and CD86 and it inhibited the TLR-driven activation of inflammatory transcription factor NF-κB. These findings suggest that rHDL prevents activation of crucial cellular players of cellular immunity and could therefore be a useful reagent to impede inflammation as well as the link between innate and adaptive immunity. PMID:23967171

  1. Biodegradable synthetic high-density lipoprotein nanoparticles for atherosclerosis

    PubMed Central

    Marrache, Sean; Dhar, Shanta

    2013-01-01

    Atherosclerosis remains one of the most common causes of death in the United States and throughout the world because of the lack of early detection. Macrophage apoptosis is a major contributor to the instability of atherosclerotic lesions. Development of an apoptosis targeted high-density lipoprotein (HDL)-mimicking nanoparticle (NP) to carry contrast agents for early detection of vulnerable plaques and the initiation of preventative therapies that exploit the vascular protective effects of HDL can be attractive for atherosclerosis. Here, we report the construction of a synthetic, biodegradable HDL-NP platform for detection of vulnerable plaques by targeting the collapse of mitochondrial membrane potential that occurs during apoptosis. This HDL mimic contains a core of biodegradable poly(lactic-co-glycolic acid), cholesteryl oleate, and a phospholipid bilayer coat that is decorated with triphenylphosphonium (TPP) cations for detection of mitochondrial membrane potential collapse. The lipid layer provides the surface for adsorption of apolipoprotein (apo) A-I mimetic 4F peptide, and the core contains diagnostically active quantum dots (QDs) for optical imaging. In vitro uptake, detection of apoptosis, and cholesterol binding studies indicated promising detection ability and therapeutic potential of TPP-HDL-apoA-I-QD NPs. In vitro studies indicated the potential of these NPs in reverse cholesterol transport. In vivo biodistribution and pharmacokinetics indicated favorable tissue distribution, controlled pharmacokinetic parameters, and significant triglyceride reduction for i.v.-injected TPP-HDL-apoA-I-QD NPs in rats. These HDL NPs demonstrate excellent biocompatibility, stability, nontoxic, and nonimmunogenic properties, which prove to be promising for future translation in early plaque diagnosis and might find applications to prevent vulnerable plaque progression. PMID:23671083

  2. Biomimetic High-Density Lipoproteins from a Gold Nanoparticle Template

    NASA Astrophysics Data System (ADS)

    Luthi, Andrea Jane

    For hundreds of years the field of chemistry has looked to nature for inspiration and insight to develop novel solutions for the treatment of human diseases. The ability of chemists to identify, mimic, and modifiy small molecules found in nature has led to the discovery and development of many important therapeutics. Chemistry on the nanoscale has made it possible to mimic natural, macromolecular structures that may also be useful for understanding and treating diseases. One example of such a structure is high-density lipoprotein (HDL). The goal of this work is to use a gold nanoparticle (Au NP) as a template to synthesize functional mimics of HDL and characterize their structure and function. Chapter 1 details the structure and function of natural HDL and how chemistry on the nanoscale provides new strategies for mimicking HDL. This Chapter also describes the first examples of using nanoparticles to mimic HDL. Chapter 2 reports the synthesis and characterization of biomimetic HDL using different sizes of Au NPs and different surface chemistries and how these variables can be used to tailor the properties of biomimetic HDL. From these studies the optimal strategy for synthesizing biomimetic HDL was determined. In Chapter 3, the optimization of the synthesis of biomimetic HDL is discussed as well as a full characterization of its structure. In addition, the work in this chapter shows that biomimetic HDL can be synthesized on a large scale without alterations to its structure or function. Chapter 4 focuses on understanding the pathways by which biomimetic HDL accepts cholesterol from macrophage cells. The results of these studies demonstrate that biomimetic HDL is able to accept cholesterol by both active and passive pathways of cholesterol efflux. In Chapter 5 the preliminary results of in vivo studies to characterize the pharmacokinetics and pharmacodynamics of biomimetic HDL are presented. These studies suggest that biomimetic HDL traffics through tissues prone to atherosclerosis and that it has the potential to remove cholesterol from macrophages in the body.

  3. High-density lipoprotein and atherosclerosis: Roles of lipid transporters

    PubMed Central

    Uehara, Yoshinari; Saku, Keijiro

    2014-01-01

    Various previous studies have found a negative correlation between the risk of cardiovascular events and serum high-density lipoprotein (HDL) cholesterol levels. The reverse cholesterol transport, a pathway of cholesterol from peripheral tissue to liver which has several potent antiatherogenic properties. For instance, the particles of HDL mediate to transport cholesterol from cells in arterial tissues, particularly from atherosclerotic plaques, to the liver. Both ATP-binding cassette transporters (ABC) A1 and ABCG1 are membrane cholesterol transporters and have been implicated in mediating cholesterol effluxes from cells in the presence of HDL and apolipoprotein A-I, a major protein constituent of HDL. Previous studies demonstrated that ABCA1 and ABCG1 or the interaction between ABCA1 and ABCG1 exerted antiatherosclerotic effects. As a therapeutic approach for increasing HDL cholesterol levels, much focus has been placed on increasing HDL cholesterol levels as well as enhancing HDL biochemical functions. HDL therapies that use injections of reconstituted HDL, apoA-I mimetics, or full-length apoA-I have shown dramatic effectiveness. In particular, a novel apoA-I mimetic peptide, Fukuoka University ApoA-I Mimetic Peptide, effectively removes cholesterol via specific ABCA1 and other transporters, such as ABCG1, and has an antiatherosclerotic effect by enhancing the biological functions of HDL without changing circulating HDL cholesterol levels. Thus, HDL-targeting therapy has significant atheroprotective potential, as it uses lipid transporter-targeting agents, and may prove to be a therapeutic tool for atherosclerotic cardiovascular diseases. PMID:25349649

  4. Itinerary of high density lipoproteins in endothelial cells.

    PubMed

    Perisa, Damir; Rohrer, Lucia; Kaech, Andres; von Eckardstein, Arnold

    2016-02-01

    High density lipoprotein (HDL) and its main protein component apolipoprotein A-I (ApoA-I) have multiple anti-atherogenic functions. Some of them are exerted within the vessel wall, so that HDL needs to pass the endothelial barrier. To elucidate their itinerary through endothelial cells (ECs), we labelled ApoA-I and HDL either fluorescently or with 1.4nm nanogold and investigated their cellular localization by using immunofluorescent microscopy (IFM) and electron microscopy (EM). HDL as well as ApoA-I is taken up by ECs into the same route of intracellular trafficking. Time kinetics and pulse chase experiments revealed that HDL is trafficked through different vesicles. HDL partially co-localized with LDL, albumin, and transferrin. HDL did not co-localize with clathrin and caveolin-1. Fluorescent HDL was recovered at small proportions in early endosomes and endosome to trans-golgi network vesicles but not at all in recycling endosomes, in late endosomes or lysosomes. EM identified HDL mainly in large filled vesicles which however upon IFM did not colocalize with markers of multivesicular bodies or autophagosomes. The uptake or cellular distribution of HDL was altered upon pharmacological interference with cytochalasine D, colchicine and dynasore. Blockage of fluid phase uptake with Amiloride or EIPA did not reduce the uptake of HDL. Neither did we observe any co-localization of HDL with dextran as the marker of fluid phase uptake. In conclusion, HDL and ApoA-I are internalized and trafficked by endothelial cells through a non-classical endocytic route. PMID:26577406

  5. Increased Very Low Density Lipoprotein Secretion, Hepatic Steatosis, and Insulin Resistance

    PubMed Central

    Choi, Sung Hee; Ginsberg, Henry N

    2011-01-01

    Insulin resistance (IR) not only affects regulation of carbohydrate metabolism, but all aspects of lipid and lipoprotein metabolism. IR is associated with increased secretion of very low density lipoproteins (VLDL) and increased plasma triglycerides, as well as hepatic steatosis, despite the increased VLDL secretion. Here, we link IR with increased VLDL secretion and hepatic steatosis at both the physiologic and molecular levels. Increased VLDL secretion, together with the downstream effects on high density lipoprotein cholesterol and low density lipoprotein size is pro-atherogenic. Hepatic steatosis is a risk for steatohepatitis and cirrhosis. Understanding the complex inter-relationship between IR and these abnormalities of liver lipid homeostasis may provide insights relevant to new therapies for these increasing clinical problems. PMID:21616678

  6. Human Endothelial Progenitor Cells Internalize High-Density Lipoprotein

    PubMed Central

    Srisen, Kaemisa; Rhrl, Clemens; Meisslitzer-Ruppitsch, Claudia; Ranftler, Carmen; Ellinger, Adolf; Pavelka, Margit; Neumller, Josef

    2013-01-01

    Endothelial progenitor cells (EPCs) originate either directly from hematopoietic stem cells or from a subpopulation of monocytes. Controversial views about intracellular lipid traffic prompted us to analyze the uptake of human high density lipoprotein (HDL), and HDL-cholesterol in human monocytic EPCs. Fluorescence and electron microscopy were used to investigate distribution and intracellular trafficking of HDL and its associated cholesterol using fluorescent surrogates (bodipy-cholesterol and bodipy-cholesteryl oleate), cytochemical labels and fluorochromes including horseradish peroxidase and Alexa Fluor 568. Uptake and intracellular transport of HDL were demonstrated after internalization periods from 0.5 to 4 hours. In case of HDL-Alexa Fluor 568, bodipy-cholesterol and bodipy-cholesteryl oleate, a photooxidation method was carried out. HDL-specific reaction products were present in invaginations of the plasma membrane at each time of treatment within endocytic vesicles, in multivesicular bodies and at longer periods of uptake, also in lysosomes. Some HDL-positive endosomes were arranged in form of strings of pearl- like structures. HDL-positive multivesicular bodies exhibited intensive staining of limiting and vesicular membranes. Multivesicular bodies of HDL-Alexa Fluor 568treated EPCs showed multilamellar intra-vacuolar membranes. At all periods of treatment, labeled endocytic vesicles and organelles were apparent close to the cell surface and in perinuclear areas around the Golgi apparatus. No HDL-related particles could be demonstrated close to its cisterns. Electron tomographic reconstructions showed an accumulation of HDL-containing endosomes close to the trans-Golgi-network. HDL-derived bodipy-cholesterol was localized in endosomal vesicles, multivesicular bodies, lysosomes and in many of the stacked Golgi cisternae and the trans-Golgi-network Internalized HDL-derived bodipy-cholesteryl oleate was channeled into the lysosomal intraellular pathway and accumulated prominently in all parts of the Golgi apparatus and in lipid droplets. Subsequently, also the RER and mitochondria were involved. These studies demonstrated the different intracellular pathway of HDL-derived bodipy-cholesterol and HDL-derived bodipy-cholesteryl oleate by EPCs, with concomitant. PMID:24386159

  7. High-density lipoprotein proteome dynamics in human endotoxemia

    PubMed Central

    2011-01-01

    Background A large variety of proteins involved in inflammation, coagulation, lipid-oxidation and lipid metabolism have been associated with high-density lipoprotein (HDL) and it is anticipated that changes in the HDL proteome have implications for the multiple functions of HDL. Here, SELDI-TOF mass spectrometry (MS) was used to study the dynamic changes of HDL protein composition in a human experimental low-dose endotoxemia model. Ten healthy men with low HDL cholesterol (0.7+/-0.1 mmol/L) and 10 men with high HDL cholesterol levels (1.9+/-0.4 mmol/L) were challenged with endotoxin (LPS) intravenously (1 ng/kg bodyweight). We previously showed that subjects with low HDL cholesterol are more susceptible to an inflammatory challenge. The current study tested the hypothesis that this discrepancy may be related to differences in the HDL proteome. Results Plasma drawn at 7 time-points over a 24 hour time period after LPS challenge was used for direct capture of HDL using antibodies against apolipoprotein A-I followed by subsequent SELDI-TOF MS profiling. Upon LPS administration, profound changes in 21 markers (adjusted p-value < 0.05) were observed in the proteome in both study groups. These changes were observed 1 hour after LPS infusion and sustained up to 24 hours, but unexpectedly were not different between the 2 study groups. Hierarchical clustering of the protein spectra at all time points of all individuals revealed 3 distinct clusters, which were largely independent of baseline HDL cholesterol levels but correlated with paraoxonase 1 activity. The acute phase protein serum amyloid A-1/2 (SAA-1/2) was clearly upregulated after LPS infusion in both groups and comprised both native and N-terminal truncated variants that were identified by two-dimensional gel electrophoresis and mass spectrometry. Individuals of one of the clusters were distinguished by a lower SAA-1/2 response after LPS challenge and a delayed time-response of the truncated variants. Conclusions This study shows that the semi-quantitative differences in the HDL proteome as assessed by SELDI-TOF MS cannot explain why subjects with low HDL cholesterol are more susceptible to a challenge with LPS than those with high HDL cholesterol. Instead the results indicate that hierarchical clustering could be useful to predict HDL functionality in acute phase responses towards LPS. PMID:21711511

  8. Association of the Endotoxin Antagonist E5564 with High-Density Lipoproteins In Vitro: Dependence on Low-Density and Triglyceride-Rich Lipoprotein Concentrations

    PubMed Central

    Wasan, Kishor M.; Sivak, Olena; Cote, Richard A.; MacInnes, Aaron I.; Boulanger, Kathy D.; Lynn, Melvyn; Christ, William J.; Hawkins, Lynn D.; Rossignol, Daniel P.

    2003-01-01

    The objective of this study was to determine the distribution profile of the novel endotoxin antagonist E5564 in plasma obtained from fasted human subjects with various lipid concentrations. Radiolabeled E5564 at 1 μM was incubated in fasted plasma from seven human subjects with various total cholesterol (TC) and triglyceride (TG) concentrations for 0.5 to 6 h at 37°C. Following these incubations, plasma samples were separated into their lipoprotein and lipoprotein-deficient fractions by ultracentrifugation and were assayed for E5564 radioactivity. TC, TG, and protein concentrations in each fraction were determined by enzymatic assays. Lipoprotein surface charge within control and phosphatidylinositol-treated plasma and E5564’s influence on cholesteryl ester transfer protein (CETP) transfer activity were also determined. We observed that the majority of E5564 was recovered in the high-density lipoprotein (HDL) fraction. We further observed that incubation in plasma with increased levels of TG-rich lipoprotein (TRL) lipid (TC and TG) concentrations resulted in a significant increase in the percentage of E5564 recovered in the TRL fraction. In further experiments, E5564 was preincubated in human TRL. Then, these mixtures were incubated in hypolipidemic human plasma for 0.5 and 6 h at 37°C. Preincubation of E5564 in purified TRL prior to incubation in human plasma resulted in a significant decrease in the percentage of drug recovered in the HDL fraction and an increase in the percentage of drug recovered in the TRL and low-density lipoprotein fractions. These findings suggest that the majority of the drug binds to HDLs. Preincubation of E5564 in TRL prior to incubation in normolipidemic plasma significantly decreased the percentage of drug recovered in the HDL fraction. Modifications to the lipoprotein negative charge did not alter the E5564 concentration in the HDL fraction. In addition, E5564 does not influence CETP-mediated transfer activity. Information from these studies could be used to help identify the possible components of lipoproteins which influence the interaction of E5564 with specific lipoprotein particles. PMID:12936976

  9. Low density lipoprotein delays clearance of triglyceride-rich lipoprotein by human subcutaneous adipose tissue

    PubMed Central

    Bissonnette, Simon; Salem, Huda; Wassef, Hanny; Saint-Pierre, Nathalie; Tardif, Annie; Baass, Alexis; Dufour, Robert; Faraj, May

    2013-01-01

    Delayed clearance of triglyceride-rich lipoprotein (TRL) by white adipose tissue (WAT) promotes hypertriglyceridemia and elevated apoB-lipoproteins, which are primarily in the form of LDL. This study examines whether LDL promotes delayed clearance of TRL by WAT. Following the ingestion of a 13C-triolein-labeled high-fat meal, obese women with high plasma apoB (> median 0.93 g/l, N = 11, > 98% as IDL/LDL) had delayed clearance of postprandial 13C-triglyceride and 13C-NEFA over 6 h compared with controls. AUC6 h of plasma 13C-triglyceride and 13C-NEFA correlated with plasma apoB but not with LDL diameter or adipocyte area. There was no group difference in 13C-triolein oxidation rate, which suggests lower 13C-NEFA storage in peripheral tissue in women with high apoB. Ex vivo/in vitro plasma apoB correlated negatively with WAT 3H-lipid following a 4 h incubation of women's WAT with synthetic 3H-triolein-TRL. LDL-differentiated 3T3-L1 adipocytes had lower 3H-TRL hydrolysis and 3H-NEFA storage. Treatment of women's WAT with their own LDL decreased 3H-TRL hydrolysis and 3H-NEFA uptake. Finally, LDL, although not an LPL substrate, reduced LPL-mediated 3H-TRL hydrolysis as did VLDL and HDL. Exposure to LDL decreases TRL clearance by human WAT ex vivo. This may promote production of apoB-lipoproteins and hypertriglyceridemia through a positive-feedback mechanism in vivo. PMID:23417739

  10. Softness of atherogenic lipoproteins: a comparison of very low density lipoprotein (VLDL) and low density lipoprotein (LDL) using elastic incoherent neutron scattering (EINS).

    PubMed

    Mikl, Christian; Peters, Judith; Trapp, Marcus; Kornmueller, Karin; Schneider, Wolfgang J; Prassl, Ruth

    2011-08-31

    Apolipoprotein B100 (apoB100)-containing plasma lipoproteins (LDL and VLDL) supply tissues and cells with cholesterol and fat. During lipolytic conversion from VLDL to LDL the size and chemical composition of the particles change, but the apoB100 molecule remains bound to the lipids and regulates the receptor mediated uptake. The molecular physical parameters which control lipoprotein remodeling and enable particle stabilization by apoB100 are largely unknown. Here, we have compared the molecular dynamics and elasticities of VLDL and LDL derived by elastic neutron scattering temperature scans. We have determined thermal motions, dynamical transitions, and molecular fluctuations, which reflect the temperature-dependent motional coupling between lipid and protein. Our results revealed that lipoprotein particles are extremely soft and flexible. We found substantial differences in the molecular resiliences of lipoproteins, especially at higher temperatures. These discrepancies not only can be explained in terms of lipid composition and mobility but also suggest that apoB100 displays different dynamics dependent on the lipoprotein it is bound to. Hence, we suppose that the inherent conformational flexibility of apoB100 permits particle stabilization upon lipid exchange, whereas the dynamic coupling between protein and lipids might be a key determinant for lipoprotein conversion and atherogenicity. PMID:21790144

  11. Effect of proteolysis of low-density serum lipoproteins on their interaction with macrophages

    SciTech Connect

    Karmanskii, I.M.; Kovaleva, G.G.; Viktorova, L.N.; Shpikiter, V.O.

    1987-01-01

    The authors previously postulated, on the basis of changes observed in the structural stability of low-density lipoproteins during treatment with pepsin or aortic cathepsin, that enzymatic modifications may lead to potentiation of the atherogenic properties of the lipoproteins. They also reported that treatment of lipoproteins with trypsin causes an increase in their binding with aortic glycosaminoglycans and to increased degradation by fibroblasts of patients with hereditary hypercholesterolemia. Limited proteolysis of lipoproteins with pepsin facilitated their binding with fibronectin. In this paper the authors investigate the uptake and degradation of low-density lipoproteins by macrophages after their limited hydrolysis by pepsin, an analog of tissue cathepsin D. The lipoproteins were isolated from the serum of healthy blood donors by ultracentrifugation. Iodination of the proteins with I 125 was carried out by the iodine monochloride method. Uptake and retention of the labelled lipoprotein were measured with a gamma counter. The increased uptake of the proteins, partially hydrolized by pepsin, was accompanied by their more intense degradation by macrophages.

  12. High-density lipoprotein cholesterol subfractions and lecithin: cholesterol acyltransferase activity in collegiate soccer players.

    PubMed

    Imamura, H; Nagata, A; Oshikata, R; Yoshimura, Y; Miyamoto, N; Miyahara, K; Oda, K; Iide, K

    2013-05-01

    Many of the published data on the lipid profile of athletes is based on studies of endurance athletes. The data on soccer players are rare. The purpose of this study was to examine serum high-density lipoprotein cholesterol subfractions and lecithin:cholesterol acyltransferase activity in collegiate soccer players. 31 well-trained male collegiate soccer players were divided into 2 groups: 16 defenders and 15 offenders. They were compared with 16 sedentary controls. Dietary information was obtained with a food frequency questionnaire. The subjects were all non-smokers and were not taking any drug known to affect the lipid and lipoprotein metabolism. The offenders had significantly higher high-density lipoprotein cholesterol, high-density lipoprotein2 cholesterol, and apolipoprotein A-I than the defenders and controls, whereas the defenders had the significantly higher high-density lipoprotein2 cholesterol than the controls. Both groups of athletes had significantly higher lecithin:cholesterol acyltransferase activity than the controls. The results indicate that favorable lipid and lipoprotein profile could be obtained by vigorous soccer training. PMID:23152129

  13. Obstructive jaundice leads to accumulation of oxidized low density lipoprotein in human liver tissue.

    PubMed

    Comert, Mustafa; Ustundag, Yucel; Tekin, Ishak Ozel; Gun, Banu Dogan; Barut, Figen

    2006-08-21

    Oxidized low density lipoprotein (ox-LDL) molecule is one of the most important modified lipoproteins produced during the oxidative stress. Modified lipoproteins have been defined as being part of the immune inflammatory mechanisms in association with oxidant stress. We have reported the accumulation of ox-LDL in Balb/c mice liver after bile duct ligation previously. Here, we investigated this finding in human beings with obstructive jaundice. Our study demonstrates that obstructive jaundice results in tremendous accumulation of ox-LDL in the liver tissue of patients. PMID:16937517

  14. Synthesis and properties of the very-low-density-lipoprotein receptor and a comparison with the low-density-lipoprotein receptor.

    PubMed Central

    Patel, D D; Forder, R A; Soutar, A K; Knight, B L

    1997-01-01

    The properties of the very-low-density lipoprotein (VLDL) receptor have been studied in Chinese hamster ovary (CHO) cells stably transfected with human VLDL-receptor cDNA and compared with those of the low-density lipoprotein (LDL) receptor expressed under the same conditions. Immunoblotting showed that the cells produced a mature VLDL receptor protein, of apparent Mr 123000 on non-reduced and 158000 on reduced gels, that was less extensively glycosylated than the LDL receptor. The VLDL receptor was more slowly processed than the LDL receptor, with only approx. 70% of the precursor being converted into the mature protein. Nevertheless, the majority of the receptor in the cells was in the mature form, and most of this was present on the cell surface. The human VLDL receptor bound rabbit very-low-density lipoprotein with beta electrophoretic mobility (betaVLDL), but not human LDL, and uptake through the receptor led to stimulation of oleate incorporation into cholesteryl esters. At 37 degrees C, the characteristics of VLDL-receptor-mediated uptake and degradation of betaVLDL were essentially the same as those mediated by the LDL receptor. However, the VLDL receptor apparently did not show the increase in affinity and decrease in binding of betaVLDL on cooling to 4 degrees C that was exhibited by the LDL receptor. Thus the overexpressed VLDL receptor in CHO cells appears to behave as a lipoprotein receptor with similar, but not identical, properties to the LDL receptor. PMID:9182693

  15. Effects of 1,2-cyclohexanedione modification on the metabolism of very low density lipoprotein apolipoprotein B: potential role of receptors in intermediate density lipoprotein catabolism

    SciTech Connect

    Packard, C.J.; Boag, D.E.; Clegg, R.; Bedford, D.; Shepherd, J.

    1985-09-01

    The conversion of very low density (VLDL) to low density lipoproteins (LDL) is a two-step process. The first step is mediated by lipoprotein lipase, but the mechanism responsible for the second is obscure. In this study we examined the possible involvement of receptors at this stage. Apolipoprotein B (apoB)-containing lipoproteins were separated into three fractions, VLDL (Sf 100-400), an intermediate fraction IDL (Sf 12-100), and LDL (Sf 0-12). Autologous 125I-labeled VLDL and 131I-labeled 1,2-cyclohexanedione-modified VLDL were injected into the plasma of four normal subjects and the rate of transfer of apoB radioactivity was followed through IDL to LDL. Modification did not affect VLDL to IDL conversion. Thereafter, however, the catabolism of modified apoB in IDL was retarded and its appearance in LDL was delayed. Hence, functional arginine residues (and by implication, receptors) are required in this process. Confirmation of this was obtained by injecting 125I-labeled IDL and 131I-labeled cyclohexanedione-treated IDL into two additional subjects. Again, IDL metabolism was delayed by approximately 50% as a result of the modification. These data are consistent with the view that receptors are involved in the metabolism of intermediate density lipoprotein.

  16. Lipoprotein binding and endosomal itinerary of the low density lipoprotein receptor-related protein in rat liver

    SciTech Connect

    Lund, H.; Takahashi, K.; Hamilton, R.L.; Havel, R.J. )

    1989-12-01

    The high affinity of {sup 45}Ca binding to the low density lipoprotein receptor (LDL-R) and the LDL-R-related protein (LRP) was utilized to study the subcellar distribution of these two proteins in rat liver. Like the LDL-R, LRP was manyfold enriched in rat liver endosomal membranes with a relative distribution in early and late endosomal compartments consistent with recycling between endosomes and the cell surface. The high concentration of LRP in hepatic endosomal membranes greatly facilitated demonstration of Ca-dependent binding of apolipoprotein E- and B-containing lipoproteins in ligand blots. LRP was severalfold more abundant than the LDL-R in hepatic parenchymal cells, showed extensive degradation in hepatic endosomes, and was found in high concentrations in the Golgi apparatus and endoplasmic reticulum. These data suggest a high a rate of synthesis of LRP that appeared to be unaffected by treatment of rats with estradiol. The repeating cysteine-rich A-motif found in the ligand-binding domain of LRP appeared to be responsible for Ca binding by LRP, LDL-R, and complement factor C9 and accounted for immunological cross-reactivity among these proteins. The data suggest an extensive proteolytic processing of this protein and are consistent with a functional role of LRP in lipoprotein metabolism.

  17. Plasma lipoprotein metabolism in lean and in fat chickens produced by divergent selection for plasma very low density lipoprotein concentration.

    PubMed

    Griffin, H; Acamovic, F; Guo, K; Peddie, J

    1989-08-01

    Plasma lipoprotein metabolism was studied in vivo in two lines of chickens produced by selection for high and low plasma very low density lipoprotein (VLDL) concentration. Rates of VLDL secretion were measured by determining the rate of accumulation of triglyceride in the plasma after intravenous injection of anti-lipoprotein lipase antibody. The clearance of VLDL-triglyceride and its uptake into liver and adipose tissue was examined using radioactively labeled VLDL synthesized in vivo. The rate of VLDL secretion was about threefold higher in the high-VLDL line as compared to the leaner, low VLDL-line (6.7 vs 2.1 mumol VLDL triglyceride/h per ml of plasma). The clearance of VLDL from the circulation of the low VLDL line was much faster than that of the high VLDL line (t1/2 of 3.7 and 13.6 min, respectively). The proportion of administered radiolabel taken up by the abdominal fat pad was substantially greater in the fat line than in the lean line (11.9 vs 4.8%, respectively). Lipoprotein lipase activities in leg muscle and heart were consistently greater in the low-VLDL line and beta-hydroxybutyrate concentrations in the plasma of the low-VLDL line were significantly greater than those in the high-VLDL line (0.86 vs 0.48 mumol/ml). The results show that the approximately tenfold difference in plasma VLDL concentration between lines is primarily due to markedly different rates of hepatic VLDL production and that selection has made a major effect on partitioning of VLDL triglyceride between adipose and other tissues.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2769076

  18. Comparison of soymilk and probiotic soymilk effects on serum high-density lipoprotein cholesterol and low-density lipoprotein cholesterol in diabetic Wistar rats

    PubMed Central

    Babashahi, Mina; Mirlohi, Maryam; Ghiasvand, Reza; Azadbakht, Leila

    2015-01-01

    BACKGROUND Soy milk (SM) and its fermented products are identified as rich sources of bioactive compounds helping to manage and to reduce the risk of chronic disease. This study aimed to compare the effects of SM and probiotic SM (PSM) consumption on serum low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) in diabetic Wistar rats. METHODS Probiotic SM was prepared by fermentation of the plain SM with a native strain of Lactobacillus plantarum. 20 streptozotocin-nicotinamide-induced diabetic Wistar rats were divided into two groups based on the type of administered SM (SM group and PSM group). The animals were fed with 1 ml/day of either soy or PSM for 21 days. The serum lipoprotein levels were analyzed at baseline and the end of the intervention period. RESULTS HDL-C increased significantly in PSM group. Furthermore, this group showed more percent of change in increased HDL-C in compression with SM group (P < 0.050). Regarding LDL-C level, rats fed with SM was not significantly different from the PSM group (P < 0.050); though, this biomarker was reduced in both group. CONCLUSION Probiotic SM could modulate blood lipoprotein levels. Thus, it may be considered in managing diabetes complications and atherosclerotic risks. PMID:26261455

  19. Simvastatin and preparation of polyunsaturated phospholipids produce similar changes in the phospholipid composition of high-density lipoproteins during hypercholesterolemia.

    PubMed

    Ozerova, I N; Akhmedzhanov, N M; Perova, N V; Paramonova, I V

    2005-02-01

    We studied the phospholipid composition of high-density lipoproteins in patients with coronary heart disease and hypercholesterolemia treated with simvastatin (Zocor, inhibitor of the key enzyme of cholesterol synthesis) and preparation of polyunsaturated phospholipids (lipostabil forte). Simvastatin produced a hypolipidemic effect and modulates the phospholipid composition of high-density lipoproteins (similarly to lipostabil forte). These changes contribute to functional activity of high-density lipoproteins in the reverse cholesterol transport. PMID:16027809

  20. Acetaldehyde binding increases the catabolism of rat serum low-density lipoproteins

    SciTech Connect

    Savolainen, M.J.; Baraona, E.; Lieber, C.S.

    1987-03-02

    Acetaldehyde was found to form adducts with rat serum lipoproteins. The binding of (/sup 14/C)acetaldehyde to lipoproteins was studied at low concentrations which are known to exist during ethanol oxidation. The amount of lipoprotein adducts was a linear function of acetaldehyde concentration up to 250 ..mu..M. Incubation of rat plasma low-density lipoproteins (LDL) with 200 ..mu..M acetaldehyde increased the disappearance rate of the /sup 3/H-label from the cholesterol ester moiety of LDL injected into normal rats. The data show that even low concentrations of acetaldehyde are capable of affecting LDL metabolism. These findings may provide an explanation for the low concentrations of serum LDL in alcoholics. The alcohol-induced hyperlipidemia includes either a lack of increase or a decrease in the low-density lipoprotein (LDL) concentration, but the underlying mechanism is not known. It has been shown previously, that the acetylation of lysine residues of LDL apoprotein (apoB) by acetanhydride leads to rapid uptake of LDL particles by macrophages through a non-LDL receptor pathway. Since acetaldehyde, the first toxic metabolite of ethanol, is a chemically reactive compound capable of binding to proteins, they tested whether acetaldehyde forms adducts with serum lipoproteins and subsequently alters the catabolism of LDL. 19 references, 2 figures, 1 table.

  1. Surface Density-Induced Pleating of a Lipid Monolayer Drives Nascent High-Density Lipoprotein Assembly.

    PubMed

    Segrest, Jere P; Jones, Martin K; Catte, Andrea; Manchekar, Medha; Datta, Geeta; Zhang, Lei; Zhang, Robin; Li, Ling; Patterson, James C; Palgunachari, Mayakonda N; Oram, Jack F; Ren, Gang

    2015-07-01

    Biogenesis of high-density lipoproteins (HDL) is coupled to the transmembrane protein, ATP-binding cassette transporter A1 (ABCA1), which transports phospholipid (PL) from the inner to the outer membrane monolayer. Using a combination of computational and experimental approaches, we show that increased outer lipid monolayer surface density, driven by excess PL or membrane insertion of amphipathic helices, results in pleating of the outer monolayer to form membrane-attached discoidal bilayers. Apolipoprotein (apo)A-I accelerates and stabilizes the pleats. In the absence of apoA-I, pleats collapse to form vesicles. These results mimic cells overexpressing ABCA1 that, in the absence of apoA-I, form and release vesicles. We conclude that the basic driving force for nascent discoidal HDL assembly is a PL pump-induced surface density increase that produces lipid monolayer pleating. We then argue that ABCA1 forms an extracellular reservoir containing an isolated pressurized lipid monolayer decoupled from the transbilayer density buffering of cholesterol. PMID:26095027

  2. Do free radicals play causal role in atherosclerosis? Low density lipoprotein oxidation and vitamin E revisited

    PubMed Central

    Niki, Etsuo

    2011-01-01

    Lipid peroxidation induced by free radicals has been implicated in the pathogenesis of various diseases. Numerous in vitro and animal studies show that oxidative modification of low density lipoprotein (LDL) is an important initial event of atherosclerosis. Vitamin E and other antioxidants inhibit low density lipoprotein oxidation efficiently in vitro, however, human clinical trials with vitamin E have not yielded positive results. The mixed results for vitamin E effect may be ascribed primarily to the two factors. Firstly low density lipoprotein oxidation proceeds by multiple pathways mediated not only by free radicals but also by other non-radical oxidants and vitamin E is effective only against free radical mediated oxidation. Secondly, in contrast to animal experiments, vitamin E is given at the latter stage where oxidation is no more important. Free radicals must play causal role in pathogenesis of atherosclerosis and vitamin E should be effective if given at right time to right subjects. PMID:21297905

  3. Structure of heparin fragments with high affinity for lipoprotein lipase and inhibition of lipoprotein lipase binding to alpha 2-macroglobulin-receptor/low-density-lipoprotein-receptor-related protein by heparin fragments.

    PubMed Central

    Larnkjaer, A; Nykjaer, A; Olivecrona, G; Thøgersen, H; Ostergaard, P B

    1995-01-01

    Heparin-derived deca- and octa-saccharides were subjected to affinity chromatography on lipoprotein lipase-Sepharose and the fractions eluted at high salt concentration were analysed by strong-anion-exchange chromatography. Two high-affinity decasaccharides were isolated and the structure determined by one- and two-dimensional 1H-n.m.r. spectroscopy. The affinities of 3H-labelled low-molecular-mass heparin and size-fractionated deca-, octa-, and hexa-saccharides for lipoprotein lipase immobilized on microtitre plates were determined from saturation curves. From competition experiments the affinities of unlabelled heparins and pure deca- and hexa-saccharide fragments were determined. The binding was size- and charge-dependent, but structural dependency was also indicated. Thus substitution of a 2-O-sulphated L-iduronic acid with D-glucuronic acid was less important than the sulphation pattern of the D-glucosamine residue for affinity for lipoprotein lipase. Heparin inhibits binding of lipoprotein lipase to alpha 2-macroglobulin-receptor/low-density-lipoprotein receptor-related protein. The effects of size, charge and structure for this inhibition were studied. The ability of the heparin fragments to inhibit binding correlated with their affinity for lipoprotein lipase. This indicates that the inhibition of the binding of lipoprotein lipase to alpha 2-macroglobulin-receptor/low-density-lipoprotein receptor-related protein by heparin is exclusively mediated by binding of heparin to lipoprotein lipase. PMID:7717977

  4. Isolation and partial characterization of high-density lipoprotein HDL1 from rat plasma by gradient centrifugation.

    PubMed Central

    Lusk, L T; Walker, L F; DuBien, L H; Getz, G S

    1979-01-01

    The lipoproteins isolated from rat plasma by flotation in the density range 1.019-1.063 g/ml were further characterized. Using rate zonal ultracentrifugation, we isolated two lipoproteins in almost equal proportions from this density range. Similar isolations may be accomplished with density gradients in a swinging-bucket rotor. On isopycnic-density-gradient ultracentrifugation one component banded at rho = 1.031 g/ml and the other at rho = 1.054 g/ml. More that 98% of the apoprotein of the lighter component was B protein, and hence this particle is LD (low-density) lipoprotein. Of the apoproteins of the rho = 1.054 g/ml particles, designated lipoprotein HDL1, over 60% was arginine-rich peptide, and the remainder was A-I, A-IV and C peptides. The molecular weight of these lipoproteins determined by agarose column chromatography was 2.36 x 10(6) for LD lipoprotein and 1.30 x 10(6) for lipoprotein HDL1. On electron microscopy the radius of LD lipoprotein was 14.0 nm and that of lipoprotein HDL1 was 10.0 nm, in contrast with molecular radii of 10.4 nm and 8.4 nm respectively determined from the gel-permeation-chromatography data. The lipid and phospholipid composition of both particles was determined. Lipoprotein HDL1 was notable for both the concentration of its esterified cholesterol, which was similar to that of LD lipoprotein, and the low triacylglycerol content, resembling that of HD lipoprotein. The possible origin of lipoprotein HDL1 is discussed. Images Fig. 1. PMID:230819

  5. High- and low-density lipoproteins enhance infection of Trypanosoma cruzi in vitro.

    PubMed

    Prioli, R P; Rosenberg, I; Pereira, M E

    1990-01-15

    Trypanosoma cruzi exhibits a developmentally regulated neuraminidase activity that is inhibited by high-density lipoprotein (HDL). We report here that the infection of culture cells by T. cruzi trypomastigotes is enhanced by HDL in a dose-dependent manner. The enhanced infection is prevented by Vibrio cholerae neuraminidase, an enzyme whose activity is not inhibited by HDL, suggesting that sialic acid is involved in T. cruzi-host interaction. Similar enhancement of infection is also produced by low-density lipoprotein (LDL), which inhibits T. cruzi neuraminidase as well as HDL. Further evidence that the enhancement is due to lipoproteins is provided by the fact that infection of host cells in lipoprotein-deficient medium is less than in normal medium; it can be restored to the higher level by the addition of HDL, LDL or both to the lipoprotein-deficient medium. In view of these results, we propose that HDL and LDL regulate T. cruzi infection in mammalian hosts by inhibiting the parasite neuraminidase activity. PMID:2183047

  6. Investigations on the transport and metabolism of high density lipoprotein cholesteryl esters in African green monkeys

    SciTech Connect

    Sorci-Thomas, M.G.

    1984-01-01

    The metabolic fate of circulating high density lipoprotein cholesteryl esters was studied in African green monkeys to determine the significance of the lipid transfer reaction on the catabolism of lipoprotein cholesteryl esters. A method of doubly labeling both moieties of lipoprotein cholesteryl esters with (/sup 3/He)cholesteryl oleate and cholesteryl (/sup 14/C)oleate was developed for the purpose of studying plasma cholesteryl ester metabolism in vivo. In these studies the total plasma (/sup 3/He)cholesterol turnover resulted in production rates, which ranged from 10-17 mg/kg day, similar to previously reported values in African green monkeys and in normal lipoproteinemic humans. In contrast to the production rates calculated from the decay of plasma /sup 3/He-radioactivity, the production rates calculated from lipoproteins labeled with cholesteryl (/sup 14/C)oleate were approximately 2-3 times greater. In addition to these studies, a plasma cholesteryl ester transacylation activity was demonstrated in vitro when HDL containing doubly labeled cholesteryl esters were incubated with fresh plasma. These results demonstrated that high density lipoprotein cholesteryl esters undergo transacylation in vitro, resulting in release and reesterification of free (/sup 3/H)cholesterol.

  7. Rotational diffusion of the low-density lipoprotein-receptor complex

    NASA Astrophysics Data System (ADS)

    Tilley, Leann M.; Li, Q. T.; Sawyer, William H.; Morrison, John R.; Fidge, Noel H.

    1990-05-01

    Time-resolved phosphorescence anisotropy. has been used to assess the rotational dynamics of human serum lipoproteins labeled with phosphorescent probes of high triplet yield. Covalent labeling of apolipoprotein B with erythrosin revealed the existence of segmental motion of labeled domains within the particle as well as global rotation of the particles. The binding of the low density lipoprotein to cell surface receptors resulted in a freezing of the global motion but the maintenance of faster motion of domains within the apolipoprotein. Labeling of the lipid phase of the low density lipoproteins with an eosinyl fatty acid also revealed the existence of two motions. The shorter time constant was attributed to the motion of the chromophore within the lipoprotein particle, while the longer time constant represented the global tumbling of the particle in solution. To examine the the physical state of the lipid phase in lipoproteins, the steady-state fluorescence anisotropy of n-(9-anthroyloxy) fatty acids was examined in microemulsions and phospholipid bilayers. The phase transition in the surface monolayer of the microemulsion is significantly less cooperative than the same transition in a bilayer vesicle. Moreover, the rate at which cholesterol transfers from a donor structure to an acceptor is much faster for the microemulsion than for the bilayer vesicle. These results indicate differences in the packing of phospholipids in the monolayer of the microemulsion as compared to the external leaflet of the bilayer vesicle.

  8. Genome-wide association studies identified novel loci for non-high-density lipoprotein cholesterol and its postprandial lipemic response

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Non-high-density lipoprotein cholesterol (NHDL) is an independent and superior predictor of CVD risk as compared to low-density lipoprotein alone. It represents a spectrum of atherogenic lipid fractions with possibly a distinct genomic signature. We performed genome-wide association studies (GWAS) t...

  9. Distribution and Kinetics of Lipoprotein-Bound Endotoxin

    PubMed Central

    Levels, J. H. M.; Abraham, P. R.; van den Ende, A.; van Deventer, S. J. H.

    2001-01-01

    Lipopolysaccharide (LPS), the major glycolipid component of gram-negative bacterial outer membranes, is a potent endotoxin responsible for pathophysiological symptoms characteristic of infection. The observation that the majority of LPS is found in association with plasma lipoproteins has prompted the suggestion that sequestering of LPS by lipid particles may form an integral part of a humoral detoxification mechanism. Previous studies on the biological properties of isolated lipoproteins used differential ultracentrifugation to separate the major subclasses. To preserve the integrity of the lipoproteins, we have analyzed the LPS distribution, specificity, binding capacity, and kinetics of binding to lipoproteins in human whole blood or plasma by using high-performance gel permeation chromatography and fluorescent LPS of three different chemotypes. The average distribution of O111:B4, J5, or Re595 LPS in whole blood from 10 human volunteers was 60% (±8%) high-density lipoprotein (HDL), 25% (±7%) low-density lipoprotein, and 12% (±5%) very low density lipoprotein. The saturation capacity of lipoproteins for all three LPS chemotypes was in excess of 200 μg/ml. Kinetic analysis however, revealed a strict chemotype dependence. The binding of Re595 or J5 LPS was essentially complete within 10 min, and subsequent redistribution among the lipoprotein subclasses occurred to attain similar distributions as O111:B4 LPS at 40 min. We conclude that under simulated physiological conditions, the binding of LPS to lipoproteins is highly specific, HDL has the highest binding capacity for LPS, the saturation capacity of lipoproteins for endotoxin far exceeds the LPS concentrations measured in clinical situations, and the kinetics of LPS association with lipoproteins display chemotype-dependent differences. PMID:11292694

  10. Direct Low Density Lipoprotein Cholesterol and Glycated Albumin Levels in Type 2 Diabetes Mellitus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diabetes mellitus is a major risk factor for coronary heart disease (CHD), renal failure, retinopathy, and neuropathy. Lowering glycosylated hemoglobin (HbA1c) as well as low-density lipoprotein-cholesterol (LDL-C) have been associated with a decreased risk of these complications. The aim in this st...

  11. Glycated albumin and direct low density lipoprotein cholesterol levels in type 2 diabetes mellitus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diabetes mellitus is a major risk factor for coronary heart disease (CHD), renal failure, retinopathy, and neuropathy. Lowering glycosylated hemoglobin (HbA1c) as well as low-density lipoprotein-cholesterol (LDL-C) has been associated with a decreased risk of these complications. We evaluated the ut...

  12. Total and High-Density Lipoprotein Cholesterol in Adults with Mental Retardation.

    ERIC Educational Resources Information Center

    Rimmer, James H.; Kelly, Luke E.

    1990-01-01

    The study evaluated the total cholesterol and high density lipoprotein cholesterol of 40 adults (mean age 37.5 years) with mental retardation residing at an intermediate care facility. Results indicated that 59 percent of the males and 68 percent of the females were at moderate to high risk for coronary heart disease. (DB)

  13. Low density lipoprotein receptor related protein 1 variant interacts with saturated fatty acids in Puerto Ricans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Low density lipoprotein related receptor protein 1 (LRP1) is a multi-functional endocytic receptor that is highly expressed in adipocytes and the hypothalamus. Animal models and in vitro studies support a role for LRP1 in adipocyte metabolism and leptin signaling, but genetic polymorphisms have not ...

  14. BENEFITS OF REDUCING LOW DENSITY LIPOPROTEIN CHOLESTEROL CONCENTRATIONS TO <100 MG/DL

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An elevated low density lipoprotein cholesterol (LDL-C) level is an independent risk factor for premature coronary heart disease (CHD), with a value of $160 mg/dL designated as high-risk by the National Cholesterol Education Program Adult Treatment Panels I and II. Goals of therapy for all patients...

  15. In vitro incorporation of radiolabeled cholesteryl esters into high and low density lipoproteins

    SciTech Connect

    Terpstra, A.H.; Nicolosi, R.J.; Herbert, P.N. )

    1989-11-01

    We have developed and validated a method for in vitro incorporation of radiolabeled cholesteryl esters into low density (LDL) and high density lipoproteins (HDL). Radiolabeled cholesteryl esters dissolved in absolute ethanol were mixed with LDL or HDL in the presence of lipoprotein-deficient serum (LPDS) as a source of core lipid transfer activity. The efficiency of incorporation was dependent on: (a) the core lipid transfer activity and quantity of LPDS, (b) the mass of added radiolabeled cholesteryl esters, (c) the length of incubation, and (d) the amount of acceptor lipoprotein cholesterol. The tracer incorporation was documented by repeat density gradient ultracentrifugation, agarose gel electrophoresis, and precipitation with heparin-MnCl2. The radiolabeling conditions did not affect the following properties of the lipoproteins: (1) chemical composition, (2) electrophoretic mobility on agarose gels, (3) hydrated density, (4) distribution of apoproteins on SDS gels, (5) plasma clearance rates, and (6) immunoprecipitability of HDL apoproteins A-I and A-II. Rat HDL containing radiolabeled cholesteryl esters incorporated in vitro had plasma disappearance rates identical to HDL radiolabeled in vivo.

  16. Reconstituted high-density lipoprotein neutralizes gram-negative bacterial lipopolysaccharides in human whole blood.

    PubMed Central

    Parker, T S; Levine, D M; Chang, J C; Laxer, J; Coffin, C C; Rubin, A L

    1995-01-01

    We have tested hypotheses relating lipoprotein structure to function as measured by the relative ability to neutralize endotoxin by comparing natural human lipoproteins, a chemically defined form of reconstituted high-density lipoprotein (R-HDL), and a lipid emulsion (Intralipid). The human whole-blood system was used as an in vitro model of lipopolysaccharide (LPS) binding protein and CD14-dependent activation of cytokine production. When lipoproteins were compared on the basis of protein content, R-HDL was most effective in reducing tumor necrosis factor alpha (TNF-alpha) production followed in order by very low density lipoprotein, low-density lipoprotein, Intralipid, and natural HDL. However, when these particles were compared by protein, phospholipid, cholesterol, or triglyceride content by stepwise linear regression analysis, only phospholipid was correlated to effectiveness (r2 = 0.873; P < 0.0001). Anti-CD14 monoclonal antibodies MY4 and 3C10 inhibited LPS binding protein and CD14-dependent activation of TNF-alpha production by LPS at LPS concentrations up to approximately 1.0 ng/ml. R-HDL (2 mg of protein per ml) blocked TNF-alpha production by LPS from both smooth- and rough-type gram-negative bacteria at concentrations up to 100 ng of LPS per ml but had little effect on heat-killed gram-positive Staphylococcus aureus and no effect on other LPS-independent stimuli tested. These results support our hypothesis that LPS is neutralized by binding to phospholipid on the surface of R-HDL and demonstrate that R-HDL is a potent inhibitor of the induction of TNF-alpha by LPS from both rough- and smooth-form gram-negative bacteria in whole human blood. PMID:7528733

  17. Metabolism of apolipoproteins A-I and A-II in human high-density lipoprotein: a mathematical approach for analysis of their specific activity decay curves

    SciTech Connect

    Atmeh, R.F.

    1987-12-01

    The differential rate equations describing the compartmental model of human high-density lipoprotein (HDL) were integrated by means of Laplace transforms and an exponential equation was obtained for each of the three compartments. These equations were used to fit the observed plasma decay data and give estimates for the rate constants of the system by means of a written computer program. Furthermore, these estimates were used to calculate the exponential constants of the integrated equations. Consequently, the amount of label in any of the intravascular, extravascular, and urine compartments can be calculated as a fraction of the original dose of label at any time point. This method was tested using data for the (AI)HDL subclass because it contains only apolipoprotein A-I as the major apolipoprotein and does not contain apolipoprotein A-II. The calculated plasma and urine radioactivity data were compared with the experimentally obtained data from two normolipoproteinemic subjects and found to be in good agreement. The significance of this method is its application to the analysis of the decay data of the individual apolipoproteins of (AI + AII) HDL subclass where the urinary radioactivity data resulting from the individual apolipoprotein breakdown on the native particle cannot be measured experimentally at present. Such data are essential for the detailed calculation of the kinetic parameters of these apolipoproteins.

  18. Intact human ceruloplasmin oxidatively modifies low density lipoprotein.

    PubMed Central

    Ehrenwald, E; Chisolm, G M; Fox, P L

    1994-01-01

    Ceruloplasmin is a plasma protein that carries most of the copper found in the blood. Although its elevation after inflammation and trauma has led to its classification as an acute phase protein, its physiological role is uncertain. A frequently reported activity of ceruloplasmin is its ability to suppress oxidation of lipids. In light of the intense recent interest in the oxidation of plasma LDL, we investigated the effects of ceruloplasmin on the oxidation of this lipoprotein. In contrast to our expectations, highly purified, undegraded human ceruloplasmin enhanced rather than suppressed copper ion-mediated oxidation of LDL. Ceruloplasmin increased the oxidative modification of LDL as measured by thiobarbituric acid-reacting substances by at least 25-fold in 20 h, and increased electrophoretic mobility, conjugated dienes, and total lipid peroxides. In contrast, ceruloplasmin that was degraded to a complex containing 115- and 19-kD fragments inhibited cupric ion oxidation of LDL, as did commercial preparations, which were also degraded. However, the antioxidant capability of degraded ceruloplasmin in this system was similar to that of other proteins, including albumin. The copper in ceruloplasmin responsible for oxidant activity was not removed by ultrafiltration, indicating a tight association. Treatment of ceruloplasmin with Chelex-100 removed one of seven copper atoms per molecule and completely blocked oxidant activity. Restoration of the copper to ceruloplasmin also restored oxidant activity. These data indicate that ceruloplasmin, depending on the integrity of its structure and its bound copper, can exert a potent oxidant rather than antioxidant action on LDL. Our results invite speculation that ceruloplasmin may be in part responsible for oxidation of LDL in blood or in the arterial wall and may thus have a physiological role that is quite distinct from what is commonly believed. Images PMID:8163654

  19. Enzymatic Modification of Plasma Low Density Lipoproteins in Rabbits: A Potential Treatment for Hypercholesterolemia

    NASA Astrophysics Data System (ADS)

    Labeque, Regine; Mullon, Claudy J. P.; Ferreira, Joao Paulo M.; Lees, Robert S.; Langer, Robert

    1993-04-01

    Phospholipase A_2 (EC 3.1.1.4) hydrolyzes certain phospholipids of low density lipoprotein (LDL). Plasma clearance of phospholipase A_2-modified human LDL is up to 17 times faster than that of native human LDL in hypercholesterolemic rabbits. Modification of blood lipoproteins of hypercholesterolemic rabbits was performed by using an extracorporeal circuit containing immobilized phospholipase A_2. After 90-min treatments, nearly 30% decreases in plasma cholesterol concentrations were observed. Erythrocyte, leukocyte, and platelet counts showed no net change after treatment. This technique does not require any fluid replacement or sorbent regeneration and offers a potential approach for lowering serum cholesterol and LDL levels.

  20. A very-high-density lipoprotein with clotting ability from hemolymph of sand crayfish, Ibacus ciliatus.

    PubMed

    Komatsu, M; Ando, S

    1998-03-01

    A very-high-density lipoprotein (VHDL) with a density of 1.27-1.29 g/ml was the most abundant lipoprotein in the hemolymph of the sand crayfish Ibacus ciliatus. The VHDL isolated by a density gradient ultracentrifugation consisted of 94% protein and 6% lipid reflecting its high density, and phospholipid was a predominant lipid component. The VHDL had an apolipoprotein of molecular mass 195 kDa and its N-terminal amino acid sequence was identified as follows: LQPGLEYQYRYNGRVAA. This sequence was similar to those of clotting proteins from the spiny lobster Panulirus interruptus and the freshwater crayfish Pacifastacus leniusculus. Transglutaminase and Ca2+ also induced the VHDL to clot. Considering large amounts of VHDL in the hemolymph of sand crayfish, the VHDL not only functions as lipid carrier but plays an important role in the defense process of crustacea. PMID:9571775

  1. Low density lipoprotein fraction assay for cardiac disease risk

    DOEpatents

    Krauss, Ronald M.; Blanche, Patricia J.; Orr, Joseph

    1999-01-01

    A variable rate density gradient electrophoric gel is described which separate LDL subfractions with the precision of ultracentrifugation techniques. Also, an innovative bottom inlet mixing chamber particularly useful for producing these gels is described.

  2. Low density lipoprotein fraction assay for cardiac disease risk

    DOEpatents

    Krauss, R.M.; Blanche, P.J.; Orr, J.

    1999-07-20

    A variable rate density gradient electrophoric gel is described which separates LDL subfractions with the precision of ultracentrifugation techniques. Also, an innovative bottom inlet mixing chamber particularly useful for producing these gels is described. 8 figs.

  3. Dietary palmitic acid (16:0) enhances high density lipoprotein cholesterol and low density lipoprotein receptor mRNA abundance in hamsters.

    PubMed

    Lindsey, S; Benattar, J; Pronczuk, A; Hayes, K C

    1990-11-01

    In order to examine the qualitative effect of different fats and specific fatty acids on plasma lipids and lipoprotein metabolism, six low fat, cholesterol-free diets were fed to young male hamsters (10/group) for a 4-week period. Fat blends were formulated with coconut oil, palm oil, soybean oil, high oleic acid safflower oil, butter, corn oil, and canola oil. Diets contained 13% energy as fat and dietary polyunsaturate/saturate ratios ranged from 0.12 to 1.04, one of which incorporated the American Heart Association-recommended concentrations of saturates, monoenes, and polyenes and another reflected the current American Fat Blend. In three diets the polyunsaturate/monounsaturate/saturate ratio was held constant while only the 12:0, 14:0, and 16:0 were varied. Plasma lipoproteins and apoproteins were assessed in conjunction with the abundance of specific hepatic and intestinal mRNA for the low density lipoproteins (LDL) receptor and various apolipoproteins associated with cholesterol metabolism. The plasma cholesterol response was lowest with the American Heart Association blend and equally elevated by the more saturated, low polyene diets (polyunsaturate/saturate, 0.12-0.38). Replacing 12:0 plus 14:0 from coconut oil with 16:0 as palm oil induced a significant increase in high density lipoprotein (HDL) cholesterol with a trend toward decreased LDL. These shifts in lipoprotein cholesterol were corroborated by measures of the LDL/HDL ratio, the plasma apolipoprotein B/apolipoprotein A1 ratio, and differences in the synthesis of apolipoproteins and the LDL receptor based on estimates of the mRNA for these proteins in the liver and gut, using specific cDNA probes for apolipoprotein A1, apolipoprotein B, apolipoprotein E, and the LDL receptor. Although it has been suggested that dietary polyenes lower total plasma cholesterol, including HDL, and that saturated fat increases both these pools of cholesterol, the current data represents the first evidence that a specific saturated fatty acid, i.e., palmitic acid, may enhance HDL production. PMID:2236108

  4. Negatively Cooperative Binding of High Density Lipoprotein to the HDL Receptor SR-BI†

    PubMed Central

    Nieland, Thomas J.F.; Xu, Shangzhe; Penman, Marsha; Krieger, Monty

    2011-01-01

    Scavenger receptor class B, type I (SR-BI) is a high-density lipoprotein (HDL) receptor, which also binds low density lipoprotein (LDL), and mediates the cellular selective uptake of cholesteryl esters from lipoproteins. SR-BI also is a co-receptor for hepatitis C virus and a signaling receptor that regulates cell metabolism. Many investigators have reported that lipoproteins bind to SR-BI via a single class of independent (not interacting), high affinity binding sites (one site model). We have re-investigated the ligand concentration dependence of 125I-HDL binding to SR-BI and SR-BI-mediated specific uptake of [3H]CE from [3H]CE-HDL using an expanded range of ligand concentrations (<1 µg protein/ml, lower than previously reported). Scatchard and non-linear least squares model fitting analyses of the binding and uptake data were both inconsistent with a single class of independent binding sites binding univalent lipoprotein ligands. The data are best fit by models in which SR-BI has either two independent classes of binding sites, or one class of sites exhibiting negative cooperativity due to either classic allostery or ensemble effects (‘ lattice model’). Similar results were observed for LDL. Application of the ‘infinite dilution’ dissociation rate method established that the binding of 125I-HDL to SR-BI at 4 °C exhibits negative cooperativity. The unexpected complexity of the interactions of lipoproteins with SR-BI should be taken into account when interpreting the results of experiments that explore the mechanism(s) by which SR-BI mediates ligand binding, lipid transport and cell signaling. PMID:21254782

  5. Assembly and secretion of hepatic very-low-density lipoprotein.

    PubMed Central

    Gibbons, G F

    1990-01-01

    In contrast to water-soluble fuels such as glucose or ketone bodies, the use of lipids as an energy source for tissues has required the development of complex structures for their transport through the aqueous plasma. In the case of endogenously synthesized triacylglycerol this is achieved by the assembly and secretion of hepatic VLDL which provides the necessary stability in an aqueous medium. An essential component of this assembly process is apo B. Dietary changes which require an increase in hepatic VLDL secretion appear to be accompanied by increases in the availability of functional apo B. Interesting questions relate to: (a) the intracellular site(s) of triacylglycerol association with apo B, and (b) the mechanism(s) by which the availability of functional apo B at this site responds to metabolic and hormonal signals which reflect dietary status and, thus, the need to secrete triacylglycerol. As regards the latter, although in some cases changes in apo B synthesis occur in response to VLDL secretion hepatic apo B mRNA levels appear to be quite stable in vitro. Intracellular switching of apo B between the secretory and degradative pathways may be important in controlling VLDL assembly and post-translational modifications of the apoprotein may also play a role by influencing its ability to bind to triacylglycerol. Transport is not the only problem associated with the utilization of a concentrated energy source such as triacylglycerol and the complex problems of waste product disposal and recycling have to be dealt with. In the case of triacylglycerol, potentially toxic waste products include atherogenic remnants and LDL. The overall problem, then, in the long-term, involves the development of a 'safe' means of utilizing triacylglycerol and this requirement accounts for much of the complexity of plasma lipoprotein metabolism. In this area, the rat could teach the human a few tricks. One of these appears to be the utilization of hepatic apo B48 rather than apo B100 for VLDL assembly in response to increases in the extrahepatic utilization of hepatically synthesized triacylglycerol. Under these conditions, the remnants of hepatic triacylglycerol utilization by peripheral tissues are cleared from the plasma much more readily via a process which seems to involve the cycling of more triacylglycerol back to the liver than that which occurs in humans. The means by which this is achieved, though, are obscure and may involve a chylomicron remnant receptor, the nature of which, itself, remains controversial.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2188646

  6. Lipoprotein(a) Catabolism Is Regulated by Proprotein Convertase Subtilisin/Kexin Type 9 through the Low Density Lipoprotein Receptor*

    PubMed Central

    Romagnuolo, Rocco; Scipione, Corey A.; Boffa, Michael B.; Marcovina, Santica M.; Seidah, Nabil G.; Koschinsky, Marlys L.

    2015-01-01

    Elevated levels of lipoprotein(a) (Lp(a)) have been identified as an independent risk factor for coronary heart disease. Plasma Lp(a) levels are reduced by monoclonal antibodies targeting proprotein convertase subtilisin/kexin type 9 (PCSK9). However, the mechanism of Lp(a) catabolism in vivo and the role of PCSK9 in this process are unknown. We report that Lp(a) internalization by hepatic HepG2 cells and primary human fibroblasts was effectively reduced by PCSK9. Overexpression of the low density lipoprotein (LDL) receptor (LDLR) in HepG2 cells dramatically increased the internalization of Lp(a). Internalization of Lp(a) was markedly reduced following treatment of HepG2 cells with a function-blocking monoclonal antibody against the LDLR or the use of primary human fibroblasts from an individual with familial hypercholesterolemia; in both cases, Lp(a) internalization was not affected by PCSK9. Optimal Lp(a) internalization in both hepatic and primary human fibroblasts was dependent on the LDL rather than the apolipoprotein(a) component of Lp(a). Lp(a) internalization was also dependent on clathrin-coated pits, and Lp(a) was targeted for lysosomal and not proteasomal degradation. Our data provide strong evidence that the LDLR plays a role in Lp(a) catabolism and that this process can be modulated by PCSK9. These results provide a direct mechanism underlying the therapeutic potential of PCSK9 in effectively lowering Lp(a) levels. PMID:25778403

  7. [Beta amyloid in blood and cerebrospinal fluid is associated with high density lipoproteins].

    PubMed

    Kudinova, N V; Kudinov, A R; Berezov, T T

    1996-01-01

    Cerebrovascular and parenchymal amyloid deposits found in brains of Alzheimer's disease, Down's syndrome and normal aging are mainly composed of aggregated amyloid beta protein (A beta), a unique peptide 39 to 44 amino acids long. A similar but soluble A beta (s A beta) has been identified in plasma, cerebrospinal fluid (CSF) and cell supernatants, indicating that it is a normal protein. We report here that s A beta in normal human plasma and CSF is complexed to high density lipoprotein (HDL) 3 and very high density lipoprotein (VHDL). Biotinylated synthetic peptide A beta 1-40 was traced in normal human plasma in in vitro experiments. Both tracer biotin-labeled A beta 1-40 and native s A beta were specifically recovered in HDL3 and VHDL as it was assessed in immunoprecipitation experiments of purified plasma lipoproteins and lipoprotein depleted plasma. This fact prompted us to ascertain whether the interaction of s A beta with HDL does occur in normal human CSF in vivo. For this purpose normals human CSF was fractionated by means of sequential flotation ultracentrifugation. The presence of s A beta in the resulting lipoprotein fractions as well as in the lipoprotein depleted CSF was analysed by immunoblot analysis, electron and immune-electron microscopy and native size exclusion chromatography. Immunoblot analysis with 6E10 monoclonal anti-A beta antibodies revealed s A beta association with all HDL subspecies of CSF, primarily HDL3 and VHDL and immunoelectron microscopy confirmed an association of s A beta with CSF-HDL particles of 16.8 + 3.2 nm. Native size exclusion chromatography followed by immunoblot analysis with antibodies against A beta and different apoliproproteins indicated an association of s A beta with HDL complexes of approximately 200 kDa molecular weight. Soluble A beta association with HDL3 and VHDL may be involved in maintaining the solubility of A beta in biological fluids and points to a possible role of lipoproteins and lipoprotein lipid in the biology of aminoloidogenic peptides. PMID:9139461

  8. Detection of haptoglobin in the high-density lipoprotein and the very high-density lipoprotein fractions from sera of calves with experimental pneumonia and cows with naturally occurring fatty liver.

    PubMed

    Katoh, N; Nakagawa, H

    1999-02-01

    In addition to the lipoprotein-deficient d > 1.25 fraction, haptoglobin was detected in the high-density lipoprotein (HDL) and the very high-density lipoprotein (VHDL) fractions from sera of calves with experimental pneumonia and cows with naturally occurring fatty liver. It was not found in the chylomicrons, very low-density lipoprotein and low-density lipoprotein fractions. Washing of the HDL fraction did not decrease the haptoglobin concentration. Transferrin and immunoglobulin G were immunoblotted to examine the possibility of contamination of the lipoprotein fractions by the d > 1.25 fraction. The two serum proteins were detected only in the d > 1.25 fraction, not in any lipoprotein fractions. The distribution pattern of haptoglobin in the lipoprotein fractions was distinct from that of serum albumin. Concentrations of haptoglobin in the HDL fractions from pneumonic sera were largely proportional to those in whole sera. Cholesteryl ester concentrations were decreased in sera from calves with pneumonia, as in cows with fatty liver. A protein immunologically related to hemoglobin was also detected in particular in the VHDL fractions from sera of both groups. These results suggest that haptoglobin or a complex with the hemoglobin-like protein may have a role or roles related to the lipid metabolism. PMID:10081748

  9. [THE LIPOLYSIS IN PHYLOGENETICALLY EARLY LIPOPROTEINS OF LOW DENSITY AND MORE LATER LIPOPROTEINS OF VERY LOW DENSITY: FUNCTION AND DIAGNOSTIC VALUE OF APOE AND APOC-III].

    PubMed

    Rozhkova, T A; Titov, V N; Amelyushkina, V A; Kaba, S I; Kukhartchuk, V V

    2015-12-01

    According to phylogenetic theory of general pathology, the function of low density lipoproteins (LDL) and hydrolysis of triglycerides (TG) in them under the effect of hepatic glycerol hydrolase apoC-III (HGH) developed at much earlier stages of phylogenesis than functioning of insulin-dependent phylogenetically late very low density lipoproteins (VLDL). For millions ofyears, lipolysis and HGH+apoC-III have activated transfer of polyenic fatty acids (FA) in the form of cholesteryl polyesters (CLE) from high density lipoproteins (HDL) to linoleic and linolenic LDL under the effect of cholesteryl ester transfer protein. It is reasonable to suggest that hepatocytes physiologically secrete oleic and palmitic VLDL and linoleic and linolenic LDL. Cells uptake ligand oleic and palmitic VLVL by apoE/B-100 receptor-mediated endocytosis. Physiologically, VLDL are not converted to LDL. If hepatocytes secrete palmitic VLDL in greater amounts than oleic VLDL upon slow hydrolysis ofpalmitic TG and under the effect of postheparinic lipoprotein lipase+apoC-II, only some proportion of palmitic TG is uptaken by cells as VLDL, and the rest is converted in ligand-free palmitic LDL These LDL increase plasma contents of TG and LDL-cholesterol and form small dense palmitic LDL. Expression of HGH+apoC-III synthesis compensates TG hydrolysis in nonphysiological palmitic LDL. In vivo, apoC-III is neither physiological no pathological inhibitor of lipolysis. Increase in plasma apoC-III content is an indicator of accumulation of non-physiological palmitic LDL and atherosclerosis-atheromatosis risk factor ApoE content ofpalmitic LDL increases together with apoC-III, i.e., apoE in ligand VLDL is not internalized via apoE/B-100 endocytosis. An increase in apoC-III and apoE contents are reliable in vivo tests for the rise inpalmitic FA, palmitic TG and excessive secretion of palmitic VLDL by hepatocytes. ApoC-III and apoE contents in LDL are additional tests to evaluate the efficiency of atherosclerosis prevention when physiological function of trophology and biological reaction of exotrophy are normalized. PMID:27032246

  10. High-density lipoprotein cholesterol as an independent risk factor in cardiovascular disease: assessing the data from Framingham to the Veterans Affairs High--Density Lipoprotein Intervention Trial.

    PubMed

    Boden, W E

    2000-12-21

    The Framingham Heart Study found that high-density lipoprotein cholesterol (HDL-C) was the most potent lipid predictor of coronary artery disease risk in men and women >49 years of age. The Air Force/Texas Coronary Atherosclerosis Prevention Study (AFCAPS/TexCAPS), in which subjects were randomized to treatment with lovastatin or placebo, also reported a striking benefit of treatment, particularly in patients with HDL-C < or =35 mg/dL at baseline. Treatment with lovastatin was associated with a remarkable 45% reduction in events for this group. The Veterans Affairs HDL Intervention Trial (VA-HIT) randomized subjects to gemfibrozil or placebo. A high proportion of enrolled subjects with low HDL-C also had characteristics of the dysmetabolic syndrome. HDL-C likewise increased by 6% on treatment, total cholesterol was reduced by 4% and triglycerides by 31%. There was no change in low-density lipoprotein cholesterol (LDL-C) levels. These changes in lipid were associated with a cumulative 22% reduction in the trial primary endpoint of all-cause mortality and nonfatal myocardial infarction (MI). Additionally, significant reductions in secondary endpoints including death from coronary artery disease, nonfatal MI, stroke, transient ischemic attack, and carotid endarterectomy were associated with the increase in HDL-C. In VA-HIT, for every 1% increase in HDL-C, there was a 3% reduction in death or MI, a therapeutic benefit that eclipses the benefit associated with LDL-C reduction. PMID:11374850

  11. Macrophage metalloproteinases degrade high-density-lipoprotein-associated apolipoprotein A-I at both the N- and C-termini.

    PubMed Central

    Eberini, Ivano; Calabresi, Laura; Wait, Robin; Tedeschi, Gabriella; Pirillo, Angela; Puglisi, Lina; Sirtori, Cesare R; Gianazza, Elisabetta

    2002-01-01

    Atheromatous plaques contain various cell types, including macrophages, endothelial cells and smooth-muscle cells. To investigate the possible interactions between secreted matrix metalloproteinases and high-density lipoprotein (HDL) components, we tested the above cell types by culturing them for 24 h. HDL(3) (HDL subfractions with average sizes of between 8.44 nm for HDL(3A) and 7.62 nm for HDL(3C)) were then incubated in their cell-free conditioned media. Proteolytic degradation of apolipoprotein A-I was observed with macrophages, but not with endothelial-cell- or muscle-cell-conditioned supernatant. Absence of calcium or addition of EDTA to incubation media prevented all proteolytic processes. The identified apolipoprotein A-I fragments had sizes of 26, 22, 14 and 9 kDa. Two-dimensional electrophoresis and MS resolved the 26 and the 22 kDa components and identified peptides resulting from both N- and C-terminal cleavage of apolipoprotein A-I. The higher abundance of C- than N-terminally cleaved peptides agrees with data in the literature for a fully structured alpha-helix around Tyr(18) compared with an unstructured region around Gly(185) and Gly(186). The flexibility in the latter region of apolipoprotein A-I may explain its susceptibility to proteolysis. In our experimental set-up, HDL(3C) was more extensively degraded than the other HDL(3) subclasses (HDL(3A) and HDL(3B)). Proteolytic fragments produced by metalloproteinase action were shown by gel filtration and electrophoresis to be neither associated with lipids nor self-associated. PMID:11879189

  12. Measurement issues related to lipoprotein heterogeneity.

    PubMed

    Otvos, James D; Jeyarajah, Elias J; Cromwell, William C

    2002-10-17

    In clinical practice, the coronary artery disease (CAD) risk associated with high levels of low-density lipoprotein (LDL) or low levels of high-density lipoprotein (HDL) is assessed not by measuring LDL and HDL particles directly, but by measuring the amount of cholesterol carried by these lipoproteins. It is not generally appreciated how much the amount of cholesterol per particle varies from person to person, especially for LDL, because of differences in the relative amounts of cholesterol ester and triglycerides in the particle core as well as differences in particle diameter. As a consequence of the magnitude and prevalence of this lipid compositional variability, even the most accurate lipoprotein cholesterol measurements will, for many individuals, provide an inaccurate measure of the number of circulating lipoprotein particles and the CAD risk they confer. Nuclear magnetic resonance (NMR) spectroscopy offers an efficient new means of measuring lipoprotein levels in plasma, with quantification based not on cholesterol content, but on the amplitudes of spectral signals emitted by lipoprotein subclasses of different size. Because the subclass signal amplitudes are not influenced by cholesterol compositional variability, they provide a direct measure of lipoprotein particle concentrations. NMR data from the Framingham Offspring Study demonstrate a significant "disconnect" between LDL cholesterol and LDL particle concentrations in patients with low levels of HDL cholesterol. The results imply that a substantial portion of the excess CAD risk of patients with low HDL stems from an unrecognized excess of LDL particles containing less cholesterol than normal. Patients with this abnormality would benefit from LDL-lowering therapy but are not identified as candidates for such treatment on the basis of traditional LDL cholesterol tests. PMID:12419478

  13. Simplified method for the diameter sizing of serum low-density lipoprotein using polyacrylamide gradient gel electrophoresis.

    PubMed

    Tsukamoto, Hideko; Takei, Izumi; Ishii, Keiko; Watanabe, Kiyoaki

    2004-01-01

    The appearance of small, dense, low-density lipoprotein in serum has been demonstrated to be associated with increased risk of coronary artery disease. The molecular diameter of low-density lipoprotein is usually measured on the basis of mobility differences on polyacrylamide gel electrophoresis. However, since mobility assessed by this method is seriously affected by the increased levels of serum free fatty acids associated with hypertriglyceridemia, we used polyacrylamide gradient gel electrophoresis to eliminate the interference by fatty acids and devised a simple, precise method of polyacrylamide gradient gel electrophoresis to measure the diameter of small, dense, low-density lipoproteins in serum. We used apoferritin and thyroglobulin, which have a molecular diameter of 12.2 nm and 17.0 nm, respectively, and standard low-density lipoprotein particles having a diameter of 25.7 and 27.0 nm as calibrators, estimated by measurement of negative staining of electron microscopy. We also included apoferritin as an internal standard for polyacrylamide gradient gel electrophoresis. The only stain used was Coomassie brilliant blue, and it was used for lipoprotein staining. When we used low-density lipoprotein of 25.73 nm in diameter as a quality control specimen, the coefficient of variation of the size measurements obtained by our method was less than 1.2%. The new method markedly improved the laboratory procedure for measuring the diameter of low-density lipoproteins. PMID:15497465

  14. Macrophages can decrease the level of cholesteryl ester hydroperoxides in low density lipoprotein.

    PubMed

    Baoutina, A; Dean, R T; Jessup, W

    2000-01-21

    Murine and human macrophages rapidly decreased the level of cholesteryl ester hydroperoxides in low density lipoprotein (LDL) when cultured in media non-permissive for LDL oxidation. This process was proportional to cell number but could not be attributed to the net lipoprotein uptake. Macrophage-mediated loss of lipid hydroperoxides in LDL appears to be metal ion-independent. Degradation of cholesteryl linoleate hydroperoxides was accompanied by accumulation of the corresponding hydroxide as the major product and cholesteryl keto-octadecadienoate as a minor product, although taken together these products could not completely account for the hydroperoxide consumption. Cell-conditioned medium possessed a similar capacity to remove lipid hydroperoxides as seen with cellular monolayers, suggesting that the activity is not an integral component of the cell but is secreted from it. The activity of cell-conditioned medium to lower the level of LDL lipid hydroperoxides is associated with its high molecular weight fraction and is modulated by the availability of free thiol groups. Cell-mediated loss of LDL cholesteryl ester hydroperoxides is facilitated by the presence of alpha-tocopherol in the lipoprotein. Together with our earlier reports on the ability of macrophages to remove peroxides rapidly from oxidized amino acids, peptides, and proteins as well as to clear selectively cholesterol 7-beta-hydroperoxide, results presented in this paper provide evidence of a potential protective activity of the cell against further LDL oxidation by removing reactive peroxide groups in the lipoprotein. PMID:10636856

  15. A multiexon deletion in the human low density lipoprotein receptor gene causes familial hypercholesterolemia

    SciTech Connect

    Mandel`shtam, M.Yu.; Lipovetskii, B.M.; Shvartsman, A.L.; Gaitskhoki, V.S.

    1995-02-01

    Familial hypercholesterolemia (FH) is a widespread human disease. FH is caused by a disturbance in the catabolism of low density lipoproteins (LDL), which results from mutations in the LDL receptor gene (LDLR). The majority of mutations in the LDLR locus is represented by large-scale reorganizations in the above gene. In this study, we describe a novel 5 kb deletion, which eliminates exons 4 to 6 in the LDLR gene. 16 refs., 2 figs., 1 tab.

  16. Familial massive tendon xanthomatosis with decreased high-density lipoprotein-mediated cholesterol efflux.

    PubMed

    Matsuura, Fumihiko; Hirano, Ken-ichi; Koseki, Masahiro; Ohama, Tohru; Matsuyama, Akifumi; Tsujii, Ken-ichi; Komuro, Ryutaro; Nishida, Makoto; Sakai, Naohiko; Hiraoka, Hisatoyo; Nakamura, Tadashi; Yamashita, Shizuya

    2005-08-01

    We experienced a family with novel massive tendon xanthomatosis which can be excluded from known disease causing xanthomatosis. The proband was a 58-year-old man who had necrosis in his massive Achilles tendon xanthoma. Three of 5 brothers including him and his nephew had the same clinical phenotype. The systemic tendon xanthomatosis became apparent around 30 years of their age. The proband and his elder brother had mild elevations of serum total cholesterol level (251 and 228 mg/dL, respectively). The low-density lipoprotein receptor activity of the proband's lymphocytes was normal. Neither plant sterol nor cholestanol level was increased in the proband's plasma. Magnetic resonance image of the proband's Achilles tendon demonstrated a massive expansion of the soft tissue with salami sausage-like appearance in his heels (50 mm in thickness). The physiological function of macrophages (MPhi) from the patients was investigated to clarify the mechanism for the formation of xanthomatosis. There was no significant difference in the uptake of oxidized low-density lipoprotein between the proband's MPhi and the control. High-density lipoprotein 3-mediated cholesterol efflux from the patients' MPhi (n = 2) was significantly reduced compared with the controls (n = 3), whereas there was no difference in apolipoprotein (apo) A-I-mediated cholesterol efflux between the patients' MPhi and the controls. Furthermore, there was no reduction of the messenger RNA levels of ATP-binding cassette transporter 1 (ABCA1), which is involved in apo A-I-mediated cholesterol efflux, in the proband's MPhi compared with the control. The present study demonstrates that the mechanism for the formation of novel familial massive tendon xanthomatosis may be, at least in part, associated with decreased high-density lipoprotein 3, but not free apo A-I-mediated cholesterol efflux from MPhi in vivo. PMID:16092061

  17. Plasma lipoprotein composition in alcoholic hepatitis: accumulation of apolipoprotein E-rich high density lipoprotein and preferential reappearance of "light'-HDL during partial recovery.

    PubMed

    Weidman, S W; Ragland, J B; Sabesin, S M

    1982-05-01

    Abnormal lipoproteins accumulate in the plasma of alcoholic hepatitis patients in association with a deficiency of the cholesterol esterifying enzyme, lecithin:cholesterol acyl-transferase. Most of these abnormal lipoproteins are found in the d > 1.006 g/ml density fraction. To investigate the composition and morphology of the lipoproteins at various times during the illness in four patients, we have employed density gradient ultracentrifugation combined with analyses of gradient fractions by polyacrylamide gel electrophoresis, electroimmunoassay, and electron microscopy. At the onset of the illness, plasma cholesteryl esters ranged from 19-34% of total cholesterol; high density lipoprotein (HDL) cholesterol and apoA-I, the major HDL apoprotein, were <10% of normal; and most of the d > 1.006 g/ml triglycerides and phospholipids were found in the LDL density region. A linear correlation (r = 0.964, P < 0.001) was found between the d > 1.006 g/ml apoB concentration and the summation of the triglyceride and esterified cholesterol for that fraction, indicating a constant ratio of apoB to the summation of these two "core lipids". ApoA-I was primarily found in the fraction d > 1.18 g/ml (HDL(3) and VHDL) but not at all in the HDL(2) density range of the gradient. No cholesteryl esters were present in the apoA-I containing fractions. In contrast to normal, large amounts of apoE accumulated in lipoproteins isolated at d 1.055-1.114 g/ml. The apoE-rich fractions contained primarily phospholipids and unesterified cholesterol; they appeared by electron microscopy to be mixtures of spherical particles, vesicular particles, and chains of bilamellar discs. Analyses of the density gradient fractions by SDS polyacrylamide gel electrophoresis under reducing conditions indicated that apoA-II levels and distribution paralleled apoA-I, not apoE, providing evidence against appreciable concentrations of apoE-apoA-II complexes. During partial recovery from alcoholic hepatitis in three patients, the d > 1.006 g/ml unesterified cholesterol and triglyceride levels decreased, while esterified cholesterol, HDL-cholesterol, and apoA-I levels increased. The first HDL fractions to reappear were lipoproteins with HDL(2) density characteristics, as evidenced by simultaneous increases of apoA-I, apoA-II, cholesteryl esters and phospholipids. Lipoproteins with HDL(3) density characteristics appeared later. Long-term (6-10 months) follow-up studies indicated a substantial elevation of HDL cholesterol and apoA-I in three of the four patients that appeared to have resulted from further increases in their HDL(2)-like subspecies. The above results illustrate the diversity of abnormal lipoproteins in alcoholic hepatitis and the ability of density gradient ultra-centrifugation combined with lipid and apolipoprotein quantitation, electron microscopy, and polyacrylamide gel electrophoresis to partially resolve those lipoproteins in the d > 1.006 g/ml plasma fraction.-Weidman, S. W., J. B. Ragland, and S. M. Sabesin. Plasma lipoprotein composition in alcoholic hepatitis: accumulation of apolipoprotein E-rich high density lipoprotein and preferential reappearance of "light"-HDL during partial recovery. PMID:7097121

  18. Amphiphilic polyvinyl alcohol adsorbent for the removal of low-density lipoprotein.

    PubMed

    Yu, Yao Ting; Zhu, Huijun; Wang, Shenqi

    2015-04-01

    Spacer can effectively reduce the steric hindrance and synergistic effect of the hydrophilic and hydrophobic ligands immobilized in adsorbents can improve the specific adsorption for low-density lipoprotein (LDL). In this paper, in order to improve the adsorption capacity for the Low-density lipoprotein-cholesterol (LDL-C), specifically, amphiphilic adsorbent based on polyvinyl alcohol (PVA) containing cholesterol ligand and sulfonic dextran ligands was synthesized. All kinds of factors affecting the synthesis yield and adsorption properties were studied in detail. Results showed that the amphiphilic PVA adsorbent has higher adsorption capacity for total cholesterol (TC), (LDL-C), triglyceride (TG), and lower adsorption capacity, and percentage for high-density lipoprotein-cholesterol (HDL-C), while the ligand ratio of cholesterol to sulfonic ligands is 1.57:1, the adsorption percentage and adsorption capacity for TC, LDL-C, TG, and HDL-C were 54.4%, 67.6%, 42.5%, 10.4% and 4.02, 3.612, 2.154, 0.168 mg/g, respectively. PMID:24813224

  19. Low-density lipoprotein cholesterol level and statin use among Medicare beneficiaries with diabetes mellitus.

    PubMed

    Qualls, Laura G; Hammill, Bradley G; Maciejewski, Matthew L; Curtis, Lesley H; Jones, W Schuyler

    2016-05-01

    At the time of this study, guidelines recommended a primary goal of low-density lipoprotein cholesterol level less than 100 mg/dL for all patients, an optional goal of low-density lipoprotein cholesterol less than 70 mg/dL for patients with overt cardiovascular disease and statins for patients with diabetes and overt cardiovascular disease and patients 40 years and older with diabetes and at least one risk factor for cardiovascular disease. This study examined statin use and achievement of lipid goals among 111,730 Medicare fee-for-service beneficiaries 65 years and older in 2011. Three-quarters of patients met the low-density lipoprotein cholesterol goal of less than 100 mg/dL. Patients with cardiovascular disease were more likely to meet the goal than those without, not controlling for other differences. Patients on a statin were more likely to meet the goal. There is considerable opportunity for improvement in cholesterol management in high-risk patients with diabetes mellitus. PMID:26802221

  20. Practical technique to quantify small, dense low-density lipoprotein cholesterol using dynamic light scattering

    NASA Astrophysics Data System (ADS)

    Trirongjitmoah, Suchin; Iinaga, Kazuya; Sakurai, Toshihiro; Chiba, Hitoshi; Sriyudthsak, Mana; Shimizu, Koichi

    2016-02-01

    Quantification of small, dense low-density lipoprotein (sdLDL) cholesterol is clinically significant. We propose a practical technique to estimate the amount of sdLDL cholesterol using dynamic light scattering (DLS). An analytical solution in a closed form has newly been obtained to estimate the weight fraction of one species of scatterers in the DLS measurement of two species of scatterers. Using this solution, we can quantify the sdLDL cholesterol amount from the amounts of the low-density lipoprotein cholesterol and the high-density lipoprotein (HDL) cholesterol, which are commonly obtained through clinical tests. The accuracy of the proposed technique was confirmed experimentally using latex spheres with known size distributions. The applicability of the proposed technique was examined using samples of human blood serum. The possibility of estimating the sdLDL amount using the HDL data was demonstrated. These results suggest that the quantitative estimation of sdLDL amounts using DLS is feasible for point-of-care testing in clinical practice.

  1. Predicting the structure of apolipoprotein A-I in reconstituted high-density lipoprotein disks.

    PubMed Central

    Phillips, J C; Wriggers, W; Li, Z; Jonas, A; Schulten, K

    1997-01-01

    In reconstituted high-density lipoproteins, apolipoprotein A-I and phosphatidylcholines combine to form disks in which the amphipathic alpha-helices of apolipoprotein A-1 bind to the edge of a lipid bilayer core, shielding the hydrophic lipid tails from the aqueous environment. We have employed experimental data, sequence analysis, and molecular modeling to construct an atomic model of such a reconstituted high-density lipoprotein disk consisting of two apolipoprotein A-I proteins and 160 palmitoyloleoylphosphatidylcholine lipids. The initial globular domain (1-47) of apolipoprotein A-I was excluded from the model, which was hydrated with an 8-A shell of water molecules. Molecular dynamics and simulated annealing were used to test the stability of the model. Both head-to-tail and head-to-head forms of a reconstituted high-density lipoprotein were simulated. In our simulations the protein contained and adhered to the lipid bilayer while providing good coverage of the lipid tails. Images FIGURE 1 FIGURE 3 FIGURE 4 FIGURE 5 FIGURE 7 FIGURE 8 PMID:9370429

  2. Practical technique to quantify small, dense low-density lipoprotein cholesterol using dynamic light scattering

    NASA Astrophysics Data System (ADS)

    Trirongjitmoah, Suchin; Iinaga, Kazuya; Sakurai, Toshihiro; Chiba, Hitoshi; Sriyudthsak, Mana; Shimizu, Koichi

    2016-04-01

    Quantification of small, dense low-density lipoprotein (sdLDL) cholesterol is clinically significant. We propose a practical technique to estimate the amount of sdLDL cholesterol using dynamic light scattering (DLS). An analytical solution in a closed form has newly been obtained to estimate the weight fraction of one species of scatterers in the DLS measurement of two species of scatterers. Using this solution, we can quantify the sdLDL cholesterol amount from the amounts of the low-density lipoprotein cholesterol and the high-density lipoprotein (HDL) cholesterol, which are commonly obtained through clinical tests. The accuracy of the proposed technique was confirmed experimentally using latex spheres with known size distributions. The applicability of the proposed technique was examined using samples of human blood serum. The possibility of estimating the sdLDL amount using the HDL data was demonstrated. These results suggest that the quantitative estimation of sdLDL amounts using DLS is feasible for point-of-care testing in clinical practice.

  3. [THE EFFECT OF SATINS: ACTIVATION OF LIPOLYSIS AND ABSORPTION BY INSULIN-DEPENDED CELLS LIPOPROTEINS OF VERY LOW DENSITY, INCREASING OF BIO-AVAILABILITY OF POLYENOIC FATTY ACIDS AND DECREASING OF CHOLESTEROL OF LIPOPROTEINS OF LOW DENSITY].

    PubMed

    Titov, V N; Malyshev, P P; Amelyushkina, V A; Aripovsky, A V; Smirnov, G P; Polevaya, T Yu; Kabo, S I; Kukhartchuk, V V

    2015-10-01

    The Russian cardiologic R&D production complex of Minzdrav of Russia, 121552 Moscow, Russia The statins are synthetic xenobiotics alien to animal cells. They are unlikely capable to manifest pleiotropic effect. It is feasible to evaluate effect of statins by stages: a) initially a specific inhibition of synthesis of cholesterol alcohol; b) further indirect activation of hydrolysis of triglycerides in lipoproteins of very low density; c) nonspecific activation of cells' receptor absorption of palmitic and oleic lipoproteins of very low density and then d) linoleic and linolenic lipoproteins of low density with all polyenoic fatty acids. On balance, statins activate absorption ofpolyenoic fatty acids by cells. Just they manifest physiological, specific pleiotropic effect. The statins inhibit synthesis of pool of cholesterol alcohol-lipoproteins of very low density condensed between phosphatidylcholines in polar mono-layer phosphatidylcholines+cholesterol alcohol on surface oftriglycerides. The low permeability of mono-layer separates substrate-triglycerides in lipoproteins of very low density and post-heparin lipoprotein lipase in hydrophilic blood plasma. The higher is ratio cholesterol alcohol/phosphatidylcholines in mono-layer of lipoproteins of very low density the slower is lipolysis, formation of ligand lipoproteins of very low density and their absorption by cells under apoB-100-endocytosis. The statins normalize hyperlipemia by force of a) activation of absorption oflipoproteins of very low density by insulin-depended cells and b) activation of absorption of lipoproteins of low density by all cells, increasing of bio-availability of polyenoic fatty acids, activation of apoB-100-endocytosis. The limitation in food of content of palmitic saturated fatty acid and increasing of content of ω-3 polyenoic fatty acids improve "bio-availability" of polyenoic fatty acids and their absorption by cells and also decreases cholesterol alcohol/phosphatidylcholines and biological pleiotropic effect of essential polyenoic fatty acids. According our opinion, atherosclerosis is intracellular deficiency of polyenoic fatty acids. The value of cholesterol alcohol-lipoproteins of low density is equimolar to content of lipoproteins of low density in blood which under low bio-availability can't to absorb cells byforce of apoB-100-endocytosis. PMID:26841664

  4. Total and High-Density Lipoprotein Cholesterol in Adults: National Health and Nutrition Examination Survey, 2011-2012

    MedlinePlus

    ... density Lipoprotein Cholesterol in Adults: National Health and Nutrition Examination Survey, 2011–2012 Recommend on Facebook Tweet ... Associate Director for Science Division of Health and Nutrition Examination Surveys Kathryn S. Porter, M.D., M.S., Director ...

  5. VALUE OF HIGH-DENSITY LIPOPROTEIN (HDL) SUBPOPULATIONS IN PREDICTING RECURRENT CARDIOVASCULAR EVENTS IN THE VETERANS AFFAIRS HDL INTERVENTION TRIAL

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To test the hypothesis whether determination of high-density lipoprotein (HDL) subpopulations provides more power to predict recurrent cardiovascular disease (CVD) events (nonfatal myocardial infarction, coronary heart disease death, and stroke) than traditional risk factors in the Veterans Affairs ...

  6. Single Step Reconstitution of Multifunctional High-Density Lipoprotein-Derived Nanomaterials Using Microfluidics

    PubMed Central

    Kim, YongTae; Fay, Francois; Cormode, David P.; Sanchez-Gaytan, Brenda L.; Tang, Jun; Hennessy, Elizabeth J.; Ma, Mingming; Moore, Kathryn; Farokhzad, Omid C.; Fisher, Edward Allen; Mulder, Willem J. M.; Langer, Robert; Fayad, Zahi A.

    2014-01-01

    High-density lipoprotein (HDL) is a natural nanoparticle that transports peripheral cholesterol to the liver. Reconstituted high-density lipoprotein (rHDL) exhibits antiatherothrombotic properties and is being considered as a natural treatment for cardiovascular diseases. Furthermore, HDL nanoparticle platforms have been created for targeted delivery of therapeutic and diagnostic agents. The current methods for HDL reconstitution involve lengthy procedures that are challenging to scale up. A central need in the synthesis of rHDL, and multifunctional nanomaterials in general, is to establish large-scale production of reproducible and homogeneous batches in a simple and efficient fashion. Here, we present a large-scale microfluidics-based manufacturing method for single-step synthesis of HDL-mimicking nanomaterials (µHDL). µHDL is shown to have the same properties (e.g., size, morphology, bioactivity) as conventionally reconstituted HDL and native HDL. In addition, we were able to incorporate simvastatin (a hydrophobic drug) into µHDL, as well as gold, iron oxide, quantum dot nanocrystals or fluorophores to enable its detection by computed tomography (CT), magnetic resonance imaging (MRI), or fluorescence microscopy, respectively. Our approach may contribute to effective development and optimization of lipoprotein-based nanomaterials for medical imaging and drug delivery. PMID:24079940

  7. Unique features of high-density lipoproteins in the Japanese: in population and in genetic factors.

    PubMed

    Yokoyama, Shinji

    2015-04-01

    Despite its gradual increase in the past several decades, the prevalence of atherosclerotic vascular disease is low in Japan. This is largely attributed to difference in lifestyle, especially food and dietary habits, and it may be reflected in certain clinical parameters. Plasma high-density lipoprotein (HDL) levels, a strong counter risk for atherosclerosis, are indeed high among the Japanese. Accordingly, lower HDL seems to contribute more to the development of coronary heart disease (CHD) than an increase in non-HDL lipoproteins at a population level in Japan. Interestingly, average HDL levels in Japan have increased further in the past two decades, and are markedly higher than in Western populations. The reasons and consequences for public health of this increase are still unknown. Simulation for the efficacy of raising HDL cholesterol predicts a decrease in CHD of 70% in Japan, greater than the extent by reducing low-density lipoprotein cholesterol predicted by simulation or achieved in a statin trial. On the other hand, a substantial portion of hyperalphalipoproteinemic population in Japan is accounted for by genetic deficiency of cholesteryl ester transfer protein (CETP), which is also commonly unique in East Asian populations. It is still controversial whether CETP mutations are antiatherogenic. Hepatic Schistosomiasis is proposed as a potential screening factor for historic accumulation of CETP deficiency in East Asia. PMID:25849946

  8. Unique Features of High-Density Lipoproteins in the Japanese: In Population and in Genetic Factors

    PubMed Central

    Yokoyama, Shinji

    2015-01-01

    Despite its gradual increase in the past several decades, the prevalence of atherosclerotic vascular disease is low in Japan. This is largely attributed to difference in lifestyle, especially food and dietary habits, and it may be reflected in certain clinical parameters. Plasma high-density lipoprotein (HDL) levels, a strong counter risk for atherosclerosis, are indeed high among the Japanese. Accordingly, lower HDL seems to contribute more to the development of coronary heart disease (CHD) than an increase in non-HDL lipoproteins at a population level in Japan. Interestingly, average HDL levels in Japan have increased further in the past two decades, and are markedly higher than in Western populations. The reasons and consequences for public health of this increase are still unknown. Simulation for the efficacy of raising HDL cholesterol predicts a decrease in CHD of 70% in Japan, greater than the extent by reducing low-density lipoprotein cholesterol predicted by simulation or achieved in a statin trial. On the other hand, a substantial portion of hyperalphalipoproteinemic population in Japan is accounted for by genetic deficiency of cholesteryl ester transfer protein (CETP), which is also commonly unique in East Asian populations. It is still controversial whether CETP mutations are antiatherogenic. Hepatic Schistosomiasis is proposed as a potential screening factor for historic accumulation of CETP deficiency in East Asia. PMID:25849946

  9. Current guidelines for high-density lipoprotein cholesterol in therapy and future directions

    PubMed Central

    Subedi, Bishnu H; Joshi, Parag H; Jones, Steven R; Martin, Seth S; Blaha, Michael J; Michos, Erin D

    2014-01-01

    Many studies have suggested that a significant risk factor for atherosclerotic cardiovascular disease (ASCVD) is low high-density lipoprotein cholesterol (HDL-C). Therefore, increasing HDL-C with therapeutic agents has been considered an attractive strategy. In the prestatin era, fibrates and niacin monotherapy, which cause modest increases in HDL-C, reduced ASCVD events. Since their introduction, statins have become the cornerstone of lipoprotein therapy, the benefits of which are primarily attributed to decrease in low-density lipoprotein cholesterol. Findings from several randomized trials involving niacin or cholesteryl ester transfer protein inhibitors have challenged the concept that a quantitative elevation of plasma HDL-C will uniformly translate into ASCVD benefits. Consequently, the HDL, or more correctly, HDL-C hypothesis has become more controversial. There are no clear guidelines thus far for targeting HDL-C or HDL due to lack of solid outcomes data for HDL specific therapies. HDL-C levels are only one marker of HDL out of its several structural or functional properties. Novel approaches are ongoing in developing and assessing agents that closely mimic the structure of natural HDL or replicate its various functions, for example, reverse cholesterol transport, vasodilation, anti-inflammation, or inhibition of platelet aggregation. Potential new approaches like HDL infusions, delipidated HDL, liver X receptor agonists, Apo A-I upregulators, Apo A mimetics, and gene therapy are in early phase trials. This review will outline current therapies and describe future directions for HDL therapeutics. PMID:24748800

  10. Impaired Fasting Glucose and Impaired Glucose Tolerance Have Distinct Lipoprotein and Apolipoprotein Changes: The Insulin Resistance Atherosclerosis Study

    PubMed Central

    Hartnett, Sara; Hanley, Anthony J.; Rewers, Marian J.; Wagenknecht, Lynne E.; Karter, Andrew J.; Haffner, Steven M.

    2013-01-01

    Context: Cardiovascular risk is increased in individuals with impaired glucose tolerance (IGT) and impaired fasting glucose (IFG); however, those with IGT appear to be at greater risk. Lipoprotein abnormalities occur also in the prediabetic state. Objective: The authors examined lipoprotein composition in IGT and IFG. Design and Setting: Cross-sectional analysis of a large epidemiological study was done. Participants: The Insulin Resistance Atherosclerosis Study had a total of 1107 participants. Main measures: Lipoproteins and apolipoproteins were measured by conventional methods and lipoprotein composition by nuclear magnetic resonance spectroscopy. Results: Compared with normal glucose tolerance, apolipoprotein B (105.2 vs 99.8 mg/dL, P < .05) was high in isolated IFG, triglyceride (1.48 vs 1.16 mmol/L, P < .001) was high in isolated IGT, and high-density lipoprotein cholesterol was low in combined IFG/IGT (1.12 vs 1.26 mmol/L, P < .001). Nuclear magnetic resonance spectroscopy revealed additional changes: increased total low-density lipoprotein (LDL) particles (1190 vs 1096 nmol/L, P < .01) in isolated IFG; increased large very-low-density lipoprotein (3.61 vs 2.47 nmol/L, P < .01) and small LDL subclass particles (665 vs 541 nmol/L, P < .05) and decreased large LDL subclass particles (447 vs 513 nmol/L, P < .01) in isolated IGT; and decreased large high-density lipoprotein subclass particles in combined IFG/IGT (4.24 vs 5.39 μmol/L, P < .001). Conclusions: Isolated IFG is characterized by increased apolipoprotein B and total LDL particles, whereas isolated IGT is associated with increased triglycerides, large very-low-density lipoprotein subclass particles, and structural remodeling of LDL particles. These results may help to explain differences in cardiovascular disease risk in the prediabetic state. PMID:23450048

  11. The elevation of plasma concentration of high-density lipoprotein cholesterol in mice fed with protein from proso millet.

    PubMed

    Nishizawa, N; Fudamoto, Y

    1995-02-01

    We examined the effects of dietary proso-millet protein on plasma concentration of high-density lipoprotein (HDL) cholesterol in mice. The results confirmed also, in this animal, the elevation of plasma concentration of HDL cholesterol without the involvement in raising the concentration of low-density lipoprotein cholesterol like those with rats reported in our previous paper. This would suggest a beneficial effect of millet protein on cholesterol metabolism. PMID:7766034

  12. Immunohistochemical detection of a very high density lipoprotein (VHDL) in ovarian follicles of Triatoma infestans.

    PubMed

    González, M S; Ronderos, J R; Rimoldi, O J; Brenner, R R

    2001-04-01

    The ability of Triatoma infestans ovarian follicles to synthesize a very high-density lipoprotein (VHDL) has been examined by immunohistochemical methods. This kind of lipoprotein can be envisaged as a storage hexameric protein present in the hemolymph of some insect species. VHDL immunoreactivity is observed in oocytes at different stages of maturation. The antigen is present in the oocyte cytoplasm as well as in the follicular epithelial cells. The immunopositive reaction in the apical surface of follicle cells suggests both a VHDL synthesis and a secretion process. Furthermore, VHDL seems to be stored into oocyte in yolk granules. On the contrary, no immunopositive reaction is observed in the intracellular spaces between follicle cells, suggesting that VHDL is not incorporated from hemolymph into the oocyte. PMID:11387873

  13. Ascorbic acid protects lipids in human plasma and low-density lipoprotein against oxidative damage

    SciTech Connect

    Frei, B. )

    1991-12-01

    The authors exposed human blood plasma and low-density lipoprotein (LDL) to many different oxidative challenges and followed the temporal consumption of endogenous antioxidants in relation to the initiation of oxidative damage. Under all types of oxidizing conditions, ascorbic acid completely protects lipids in plasma and LDL against detectable peroxidative damage as assessed by a specific and highly sensitive assay for lipid peroxidation. Ascorbic acid proved to be superior to the other water-soluble plasma antioxidants bilirubin, uric acid, and protein thiols as well as to the lipoprotein-associated antioxidants alpha-tocopherol, ubiquinol-10, lycopene, and beta-carotene. Although these antioxidants can lower the rate of detectable lipid peroxidation, they are not able to prevent its initiation. Only ascorbic acid is reactive enough to effectively intercept oxidants in the aqueous phase before they can attack and cause detectable oxidative damage to lipids.

  14. The low density lipoprotein receptor-related protein (LRP) 1 and its function in lung diseases.

    PubMed

    Wujak, L; Markart, P; Wygrecka, M

    2016-07-01

    The low density lipoprotein receptor-related protein (LRP) 1 is a ubiquitously expressed, versatile cell surface transmembrane receptor involved in embryonic development and adult tissue homeostasis. LRP1 binds and endocytoses a broad spectrum of over 40 ligands identified thus far, including lipoproteins, extracellular matrix proteins, proteases and protease/inhibitor complexes and growth factors. Interactions with other membrane receptors and intracellular adaptors/scaffolding proteins allow LRP1 to modulate cell migration, survival, proliferation and (trans) differentiation. Because LRP1 displays a wide-range of interactions and activities, its expression and function is temporally and spatially tightly controlled. It is not, therefore, surprising that deregulation of LRP1 production and/or activity is observed in several diseases. In this review, we will systematically examine the evidence for the role of LRP1 in human pathologies placing special emphasis on LRP1-mediated pathogenesis of the lung. PMID:26926950

  15. The HDL hypothesis: does high-density lipoprotein protect from atherosclerosis?

    PubMed Central

    Vergeer, Menno; Holleboom, Adriaan G.; Kastelein, John J. P.; Kuivenhoven, Jan Albert

    2010-01-01

    There is unequivocal evidence of an inverse association between plasma high-density lipoprotein (HDL) cholesterol concentrations and the risk of cardiovascular disease, a finding that has led to the hypothesis that HDL protects from atherosclerosis. This review details the experimental evidence for this “HDL hypothesis”. In vitro studies suggest that HDL has a wide range of anti-atherogenic properties but validation of these functions in humans is absent to date. A significant number of animal studies and clinical trials support an atheroprotective role for HDL; however, most of these findings were obtained in the context of marked changes in other plasma lipids. Finally, genetic studies in humans have not provided convincing evidence that HDL genes modulate cardiovascular risk. Thus, despite a wealth of information on this intriguing lipoprotein, future research remains essential to prove the HDL hypothesis correct. PMID:20371550

  16. Current status and future directions in lipid management: emphasizing low-density lipoproteins, high-density lipoproteins, and triglycerides as targets for therapy

    PubMed Central

    Lin, Yun; Mousa, Shaymaa S; Elshourbagy, Nabil; Mousa, Shaker A

    2010-01-01

    Current lipid management guidelines are focused on decreasing low-density lipoprotein (LDL-C) levels as the primary target for reducing coronary heart disease (CHD) risk. Yet, many recent studies suggest that low levels of high-density lipoprotein (HDL-C) are a major independent risk factor for cardiovascular diseases. According to several clinical trials, a 1% increase in HDL-C is associated with a 0.7%–3% decrease in CHD events. The direct link between high levels of triglycerides (TG) and CHD, on the other hand, is less well defined. A large reduction in TG is needed to show a difference in CHD events, especially in men. Evidence for a shift in lipid management toward targeting both LDL-C and HDL-C as primary targets for therapy is presented. Currently, the 3-hydroxy-3-methylgutaryl coenzyme A reductase inhibitors (HMG-CoA reductase inhibitors) have proven to significantly decrease LDL-C levels, reduce CHD morbidity/mortality and improve overall survival. However, improvement of survival with statins may be due to other pleiotropic effects beyond LDL-C lowering. Fibric acid derivatives and niacin are primarily used to increase HDL-C levels, although with side effects. Future therapies targeting HDL-C may have profound results on reducing CHD morbidity and mortality. This article highlights existing and future targets in lipid management and is based on available clinical data. There is an urgent need for new treatments using a combination of drugs targeting both LDL-C and HDL-C. Such treatments are expected to have a superior outcome for dyslipidemia therapy, along with TG management. PMID:20234782

  17. Suppression by diets rich in fish oil of very low density lipoprotein production in man.

    PubMed Central

    Nestel, P J; Connor, W E; Reardon, M F; Connor, S; Wong, S; Boston, R

    1984-01-01

    The highly polyunsaturated fatty acids in fish oils lower the plasma triglyceride concentration. We have studied the effect of a diet rich in fish oil on the rate of production of the triglyceride-transporting very low density lipoprotein (VLDL). Seven subjects, five normal and two with hypertriglyceridemia received up to 30% of daily energy needs from a fish oil preparation that was rich in eicosapentaenoic acid and docosahexaenoic acid, omega-3 fatty acids with five and six double bonds, respectively. Compared with a diet similarly enriched with safflower oil (in which the predominant fatty acid is the omega-6 linoleic acid, with two double bonds), the fish oil diet lowered VLDL lipids and B apoprotein concentrations profoundly. High density lipoprotein lipids and A1 apoprotein were also lowered, but the effect on low density lipoprotein (LDL) concentration was inconsistent. The daily production or flux of VLDL apoprotein B, calculated from reinjected autologous 125I-labeled lipoprotein, was substantially less in six subjects studied after 3 wk of fish oil, compared with after safflower oil. This effect on flux was more consistent than that on the irreversible fractional removal rate, which was increased in the four normolipidemic but inconsistent in the hypertriglyceridemic subjects. This suggests that fish oil reduced primarily the production of VLDL. The daily production of VLDL triglyceride, calculated from the kinetics of the triglyceride specific radioactivity-time curves after [3H]glycerol was injected, also showed very substantial reductions in five subjects studied. The marked suppression in VLDL apoprotein B and VLDL triglyceride formation was found not to be due to diminished plasma total free fatty acid or plasma eicosapentaenoic flux, calculated during constant infusions of [14C]eicosapentaenoic acid and [3H]oleic acid in four subjects. In two subjects there was presumptive evidence for substantial independent influx of LDL during the fish oil diet, based on the precursor-product relationship between the intermediate density lipoprotein and LDL apoprotein B specific radioactivity-time curves. PMID:6736254

  18. HIV/HCV coinfection ameliorates the atherogenic lipoprotein abnormalities of HIV infection

    PubMed Central

    WHEELER, Amber L.; SCHERZER, Rebecca; LEE, Daniel; DELANEY, Joseph A. C.; BACCHETTI, Peter; SHLIPAK, Michael G.; SIDNEY, Stephen; GRUNFELD, Carl; TIEN, Phyllis C.

    2014-01-01

    Background Higher levels of small low-density lipoprotein (LDL) and lower levels of high-density lipoprotein (HDL) subclasses have been associated with increased risk of cardiovascular disease. The extent to which HIV infection and HIV/HCV coinfection are associated with abnormalities of lipoprotein subclasses is unknown. Methods Lipoprotein subclasses were measured by nuclear magnetic resonance (NMR) spectroscopy in plasma samples from 569 HIV-infected and 5948 control participants in the FRAM, CARDIA and MESA studies. Multivariable regression was used to estimate the association of HIV and HIV/HCV coinfection with lipoprotein measures with adjustment for demographics, lifestyle factors, and waist-to-hip ratio. Results Relative to controls, small LDL levels were higher in HIV-monoinfected persons (+381 nmol/L, p<.0001), with no increase seen in HIV/HCV coinfection (−16.6 nmol/L). Levels of large LDL levels were lower (−196 nmol/L, p<.0001) and small HDL were higher (+8.2 μmol/L, p<.0001) in HIV-monoinfection with intermediate values seen in HIV/HCV-coinfection. Large HDL levels were higher in HIV/HCV-coinfected persons relative to controls (+1.70 μmol/L, p<.0001), whereas little difference was seen in HIV-monoinfected persons (+0.33, p=0.075). Within HIV-infected participants, HCV was associated independently with lower levels of small LDL (−329 nmol/L, p<.0001) and small HDL (−4.6 μmol/L, p<.0001), even after adjusting for demographic and traditional cardiovascular risk factors. Conclusion HIV-monoinfected participants had worse levels of atherogenic LDL lipoprotein subclasses compared with controls. HIV/HCV coinfection attenuates these changes, perhaps by altering hepatic factors affecting lipoprotein production and/or metabolism. The effect of HIV/HCV coinfection on atherosclerosis and the clinical consequences of low small subclasses remain to be determined. PMID:24136113

  19. Peroxidase-dependent metal-independent oxidation of low density lipoprotein in vitro: a model for in vivo oxidation?

    PubMed Central

    Wieland, E; Parthasarathy, S; Steinberg, D

    1993-01-01

    Oxidative modification of low density lipoprotein is believed to be an important pathway by which the lipoprotein becomes atherogenic. The in vitro systems for oxidative modification of low density lipoprotein thus far described all appear to depend upon the presence in the medium of free transition metal ions (copper or iron). In vivo, on the other hand, these metals are present almost exclusively in tightly complexed forms that do not catalyze oxidative modification. The present studies describe oxidation of low density lipoprotein in a simple system that does not depend upon the presence of added free metal ions. It requires the presence of horseradish peroxidase and either hydrogen peroxide or lipid hydroperoxides. PMID:8327462

  20. Effect of Oxidation on the Structure of Human Low- and High-Density Lipoproteins

    PubMed Central

    Oliveira, Cristiano L.P.; Santos, Priscila R.; Monteiro, Andrea M.; Figueiredo Neto, Antonio M.

    2014-01-01

    This work presents a controlled study of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) structural changes due to in vitro oxidation with copper ions. The changes were studied by small-angle x-ray scattering (SAXS) and dynamic light scattering (DLS) techniques in the case of LDL and by SAXS, DLS, and Z-scan (ZS) techniques in the case of HDL. SAXS data were analyzed with a to our knowledge new deconvolution method. This method provides the electron density profile of the samples directly from the intensity scattering of the monomers. Results show that LDL particles oxidized for 18 h show significant structural changes when compared to nonoxidized particles. Changes were observed in the electrical density profile, in size polydispersity, and in the degree of flexibility of the APO-B protein on the particle. HDL optical results obtained with the ZS technique showed a decrease of the amplitude of the nonlinear optical signal as a function of oxidation time. In contrast to LDL results reported in the literature, the HDL ZS signal does not lead to a complete loss of nonlinear optical signal after 18 h of copper oxidation. Also, the SAXS results did not indicate significant structural changes due to oxidation of HDL particles, and DLS results showed that a small number of oligomers formed in the sample oxidized for 18 h. All experimental results for the HDL samples indicate that this lipoprotein is more resistant to the oxidation process than are LDL particles. PMID:24940777

  1. Low-density lipoprotein mimics blood plasma-derived exosomes and microvesicles during isolation and detection.

    PubMed

    Sódar, Barbara W; Kittel, Ágnes; Pálóczi, Krisztina; Vukman, Krisztina V; Osteikoetxea, Xabier; Szabó-Taylor, Katalin; Németh, Andrea; Sperlágh, Beáta; Baranyai, Tamás; Giricz, Zoltán; Wiener, Zoltán; Turiák, Lilla; Drahos, László; Pállinger, Éva; Vékey, Károly; Ferdinandy, Péter; Falus, András; Buzás, Edit Irén

    2016-01-01

    Circulating extracellular vesicles have emerged as potential new biomarkers in a wide variety of diseases. Despite the increasing interest, their isolation and purification from body fluids remains challenging. Here we studied human pre-prandial and 4 hours postprandial platelet-free blood plasma samples as well as human platelet concentrates. Using flow cytometry, we found that the majority of circulating particles within the size range of extracellular vesicles lacked common vesicular markers. We identified most of these particles as lipoproteins (predominantly low-density lipoprotein, LDL) which mimicked the characteristics of extracellular vesicles and also co-purified with them. Based on biophysical properties of LDL this finding was highly unexpected. Current state-of-the-art extracellular vesicle isolation and purification methods did not result in lipoprotein-free vesicle preparations from blood plasma or from platelet concentrates. Furthermore, transmission electron microscopy showed an association of LDL with isolated vesicles upon in vitro mixing. This is the first study to show co-purification and in vitro association of LDL with extracellular vesicles and its interference with vesicle analysis. Our data point to the importance of careful study design and data interpretation in studies using blood-derived extracellular vesicles with special focus on potentially co-purified LDL. PMID:27087061

  2. Cholesterol deposition in macrophages: foam cell formation mediated by cholesterol-enriched oxidized low density lipoprotein.

    PubMed

    Greenspan, P; Yu, H; Mao, F; Gutman, R L

    1997-01-01

    Oxidized low density lipoprotein (LDL) is thought to mediate the transformation of macrophages to cholesterol-rich foam cells. Yet convincing evidence for this process is lacking in vitro. We suggest that oxidized LDL-mediated foam cell formation is not seen in vitro because the cholesteryl ester content of LDL particles (oxidized in the presence of transition metals) is dramatically reduced. Thus, if oxidized LDL could be cholesterol-enriched prior to its addition to macrophages, this lipoprotein would be made more capable of inducing the cellular deposition of cholesteryl esters. When we enriched cupric sulfate-oxidized LDL with cholesterol by incubation of this lipoprotein with unesterified cholesterol/phosphatidylcholine liposomes and added it to mouse peritoneal macrophage cultures, we found that: a) the enrichment of oxidized LDL with cholesterol did not alter the extent of oxidized LDL degradation; b) the cells accumulated massive amounts of cholesteryl ester (148 microg/mg cell protein) and unesterified cholesterol (260 microg/mg cell protein) after 24 h of incubation; and c) Sephacryl S-1000 chromatography of the cholesterol-enriched oxidized LDL verified the formation of large oxidized LDL-unesterified cholesterol/phosphatidylcholine complexes. These results demonstrate that oxidized LDL, when cholesterol-enriched, can mediate the formation of macrophage foam cells in culture PMID:9034204

  3. ANALYSIS OF DRUG INTERACTIONS WITH VERY LOW DENSITY LIPOPROTEIN BY HIGH PERFORMANCE AFFINITY CHROMATOGRAPHY

    PubMed Central

    Sobansky, Matthew R.; Hage, David S.

    2014-01-01

    High-performance affinity chromatography (HPAC) was utilized to examine the binding of very low density lipoprotein (VLDL) with drugs, using R/S-propranolol as a model. These studies indicated that two mechanisms existed for the binding of R- and S-propranolol with VLDL. The first mechanism involved non-saturable partitioning of these drugs with VLDL, which probably occurred with the lipoprotein's non-polar core. This partitioning was described by overall affinity constants of 1.2 (± 0.3) × 106 M-1 for R-propranolol and 2.4 (± 0.6) × 106 M-1 for S-propranolol at pH 7.4 and 37 °C. The second mechanism occurred through saturable binding by these drugs at fixed sites on VLDL, such as represented by apolipoproteins on the surface of the lipoprotein. The association equilibrium constants for this saturable binding at 37 °C were 7.0 (± 2.3) × 104 M-1 for R-propranolol and 9.6 (± 2.2) × 104 M-1 for S-propranolol. Comparable results were obtained at 20 °C and 27 °C for the propranolol enantiomers. This work provided fundamental information on the processes involved in the binding of R- and S-propranolol to VLDL, while also illustrating how HPAC can be used to evaluate relatively complex interactions between agents such as VLDL and drugs or other solutes. PMID:25103529

  4. Low-density lipoprotein mimics blood plasma-derived exosomes and microvesicles during isolation and detection

    PubMed Central

    Sódar, Barbara W; Kittel, Ágnes; Pálóczi, Krisztina; Vukman, Krisztina V; Osteikoetxea, Xabier; Szabó-Taylor, Katalin; Németh, Andrea; Sperlágh, Beáta; Baranyai, Tamás; Giricz, Zoltán; Wiener, Zoltán; Turiák, Lilla; Drahos, László; Pállinger, Éva; Vékey, Károly; Ferdinandy, Péter; Falus, András; Buzás, Edit Irén

    2016-01-01

    Circulating extracellular vesicles have emerged as potential new biomarkers in a wide variety of diseases. Despite the increasing interest, their isolation and purification from body fluids remains challenging. Here we studied human pre-prandial and 4 hours postprandial platelet-free blood plasma samples as well as human platelet concentrates. Using flow cytometry, we found that the majority of circulating particles within the size range of extracellular vesicles lacked common vesicular markers. We identified most of these particles as lipoproteins (predominantly low-density lipoprotein, LDL) which mimicked the characteristics of extracellular vesicles and also co-purified with them. Based on biophysical properties of LDL this finding was highly unexpected. Current state-of-the-art extracellular vesicle isolation and purification methods did not result in lipoprotein-free vesicle preparations from blood plasma or from platelet concentrates. Furthermore, transmission electron microscopy showed an association of LDL with isolated vesicles upon in vitro mixing. This is the first study to show co-purification and in vitro association of LDL with extracellular vesicles and its interference with vesicle analysis. Our data point to the importance of careful study design and data interpretation in studies using blood-derived extracellular vesicles with special focus on potentially co-purified LDL. PMID:27087061

  5. Low-Density Lipoprotein Modified by Myeloperoxidase in Inflammatory Pathways and Clinical Studies

    PubMed Central

    Vanhamme, Luc; Roumeguère, Thierry; Zouaoui Boudjeltia, Karim

    2013-01-01

    Oxidation of low-density lipoprotein (LDL) has a key role in atherogenesis. Among the different models of oxidation that have been studied, the one using myeloperoxidase (MPO) is thought to be more physiopathologically relevant. Apolipoprotein B-100 is the unique protein of LDL and is the major target of MPO. Furthermore, MPO rapidly adsorbs at the surface of LDL, promoting oxidation of amino acid residues and formation of oxidized lipoproteins that are commonly named Mox-LDL. The latter is not recognized by the LDL receptor and is accumulated by macrophages. In the context of atherogenesis, Mox-LDL accumulates in macrophages leading to foam cell formation. Furthermore, Mox-LDL seems to have specific effects and triggers inflammation. Indeed, those oxidized lipoproteins activate endothelial cells and monocytes/macrophages and induce proinflammatory molecules such as TNFα and IL-8. Mox-LDL may also inhibit fibrinolysis mediated via endothelial cells and consecutively increase the risk of thrombus formation. Finally, Mox-LDL has been involved in the physiopathology of several diseases linked to atherosclerosis such as kidney failure and consequent hemodialysis therapy, erectile dysfunction, and sleep restriction. All these issues show that the investigations of MPO-dependent LDL oxidation are of importance to better understand the inflammatory context of atherosclerosis. PMID:23983406

  6. Lipid and apolipoprotein distribution as a function of density in equine plasma lipoprotein.

    PubMed

    Le Goff, D; Pastier, D; Hannan, Y; Petit, E; Ayrault-Jarrier, M; Nouvelot, A

    1989-01-01

    1. Equine lipoproteins were isolated from plasma by density gradient ultracentrifugation and apolipoprotein composition determined by SDS-polyacrylamide gel electrophoresis. 2. VLDL and IDL were present at low concentration (0.2 mg/ml). Two apoB components of Mr corresponding to human apoB-100 and one apoB-48-like component were represented in VLDL fraction. 3. LDL-1 and LDL-2 subfractions have displayed an almost equal concentration (0.4 mg/ml). Two apoB-100-like components were the major apolipoproteins in each fraction. Small amounts of apoB-48-like component were detectable in LDL-1 and LDL-2. 4. HDL-2 represented a major class of equine lipoproteins (1.8 mg/ml). ApoA-1-like component was the dominant protein in HDL-1, HDL-2 and HDL-3. Dimeric apoA-II-like components were slightly represented in HDL subfractions. 5. HDL-3 displayed the same apolipoprotein pattern as HDL-1 and HDL-2, but two further minor proteins of Mr 20,000 and 14,000 were detected. 6. VHDL represented a minor class of lipoprotein (0.2 mg/ml). ApoA-I-like component was the major apolipoprotein of VHDL. Small amounts of apoA-IV-like, apoE-like, and Mr 55,000 protein were detectable. 7. ApoC-like of Mr lower than 10,000 was represented in all equine lipoprotein classes. PMID:2776430

  7. Low-density lipoprotein cholesterol versus particle number in middle school children

    PubMed Central

    Mietus-Snyder, Michele; Drews, Kimberly L.; Otvos, James D.; Willi, Steven M.; Foster, Gary D.; Jago, Russell; Buse, John B.

    2013-01-01

    Objectives To characterize lipids and lipoproteins in a diverse school-based cohort and identify features associated with discordance between low-density lipoprotein cholesterol (LDL-C) and LDL particle (LDL-P). Study design Sixth grade children enrolled in the HEALTHY trial (n=2,384; mean age 11.3 ± 0.6 yr; 54.2% female) were evaluated for standard lipids, lipoprotein particles measured by nuclear magnetic resonance, and homeostatic model of insulin resistance (HOMA-IR). Characteristics of subgroups with values of LDL-C and LDL-P discordant by >20 percentile units, an amount reasoned to be clinically significant, were compared. Results Four hundred twenty-eight (18%) of children were in the LDL-P < LDL-C subgroup and 375 (16%) in the LDL-P > LDL-C subgroup. Those with LDL-P > LDL-C had significantly higher BMI, waist circumference, HOMA-IR, triglycerides, systolic and diastolic blood pressure, and reflected a greater Hispanic ethnic composition but fewer of black race than both the concordant (LDL-P ≅ LDL-C) and opposite discordant (LDL-P < LDL-C) subgroups. Conclusions There is as much lipoprotein cholesterol compositional heterogeneity in 6th graders as has been described in adults and a discordant atherogenic phenotype of LDL-P > LDL-C, common in obesity, is often missed when only LDL-C is considered. Conversely, many children with moderate-risk cholesterol measures (75th to 99th percentile) have a lower LDL particle burden. PMID:23415622

  8. Postprandial Changes in High Density Lipoproteins in Rats Subjected to Gavage Administration of Virgin Olive Oil

    PubMed Central

    Martínez-Beamonte, Roberto; Navarro, María A.; Acin, Sergio; Guillén, Natalia; Barranquero, Cristina; Arnal, Carmen; Surra, Joaquín; Osada, Jesus

    2013-01-01

    Background and Aims The present study was designed to verify the influence of acute fat loading on high density lipoprotein (HDL) composition, and the involvement of liver and different segments of small intestine in the changes observed. Methods and Results To address these issues, rats were administered a bolus of 5-ml of extra-virgin olive oil and sacrificed 4 and 8 hours after feeding. In these animals, lipoproteins were analyzed and gene expressions of apolipoprotein and HDL enzymes were assessed in duodenum, jejunum, ileum and liver. Using this experimental design, total plasma and HDL phospholipids increased at the 8-hour-time-point due to increased sphingomyelin content. An increase in apolipoprotein A4 was also observed mainly in lipid-poor HDL. Increased expression of intestinal Apoa1, Apoa4 and Sgms1 mRNA was accompanied by hepatic decreases in the first two genes in liver. Hepatic expression of Abcg1, Apoa1bp, Apoa2, Apoe, Ptlp, Pon1 and Scarb1 decreased significantly following fat gavage, while no changes were observed for Abca1, Lcat or Pla2g7. Significant associations were also noted for hepatic expression of apolipoproteins and Pon1. Manipulation of postprandial triglycerides using an inhibitor of microsomal transfer protein -CP-346086- or of lipoprotein lipase –tyloxapol- did not influence hepatic expression of Apoa1 or Apoa4 mRNA. Conclusion All these data indicate that dietary fat modifies the phospholipid composition of rat HDL, suggesting a mechanism of down-regulation of hepatic HDL when intestine is the main source of those particles and a coordinated regulation of hepatic components of these lipoproteins at the mRNA level, independently of plasma postprandial triglycerides. PMID:23383120

  9. Roles of apolipoproteins B and E in the cellular binding of very low density lipoproteins.

    PubMed Central

    Krul, E S; Tikkanen, M J; Cole, T G; Davie, J M; Schonfeld, G

    1985-01-01

    Apoproteins B and E both interact with cellular low density lipoprotein (LDL) apolipoprotein B and E (apo B,E)-receptors, and very low density lipoproteins (VLDL) contain both apo B and apo E. Our aim was to study the relative importance of apo B and apo E in the binding of VLDL subfractions to cells. Two monoclonal anti-LDL-apo B antibodies (464B1B3 and 464B1B6, 2a and 2b, respectively) and two anti-apo E antibodies (1506 A1.4 and 1907 F6.4) were used to inhibit lipoprotein-cell interactions. In confirmation of previous findings, the binding and degradation of 125I-LDL by human fibroblasts were inhibited approximately 90% by antibodies 2a or 2b or the antigen-binding fragments of 2a, whereas the cellular processing of 125I-VLDL3 (Sf20-60), 125I-VLDL2 (Sf60-120), and 125I-VLDL1 (Sf greater than 120) were inhibited by only approximately 50%, approximately 25%, and less than 10%, respectively. The VLDL1-3 and LDL-dependent intracellular esterification of cholesterol with [3H]oleate were inhibited to a similar extent. Other monoclonal anti-human apo B antibodies inhibited lipoprotein-cell interactions much less effectively and nonimmune IgG isolated from mouse serum did not inhibit at all. 20-fold excesses of LDL produced about the same patterns of inhibition of degradation of 125I-VLDL1-3 and LDL by cells as did antibodies 2a and 2b, whereas homologous unlabeled VLDL1-3 in like amounts inhibited the matched 125I-VLDL subfraction more effectively. Two anti-apo E monoclonal antibodies and a polyclonal anti-apo E antibody inhibited cell-mediated degradation of and lipoprotein-dependent cholesterol esterification by VLDL1 but not VLDL3 or LDL. The results suggest that receptor recognition sites on apo E in preference to sites on apo B mediate the cellular binding of hypertriglyceridemic VLDL1. However, the proportion of particles bound via apo B seems to increase as VLDL decreases in size toward LDL, and virtually all of LDL binding is mediated by apo B. Images PMID:3973009

  10. High density lipoprotein plasma fractions inhibit aortic fatty streaks in cholesterol-fed rabbits.

    PubMed

    Badimon, J J; Badimon, L; Galvez, A; Dische, R; Fuster, V

    1989-03-01

    The effects of in vivo administration of high density lipoprotein-very high density lipoprotein (HDL-VHDL) on the development of aortic fatty streaks were studied in cholesterol-fed rabbits. The rabbits received a 0.5% cholesterol-rich diet for 8 weeks. During this period, the HDL-VHDL group was intravenously administered with 50 mg/week of homologous HDL-VHDL protein; the control group received normal saline (0.9% NaCl). HDL-VHDL fraction was obtained at density range 1.063 to 1.25 gm/ml by ultracentrifugation of normal rabbit plasma. Along the study, plasma lipid levels followed a similar profile in both groups. At the completion of the study, atherosclerotic-like lipid-rich lesions covered 37.9 +/- 6% (X +/- SEM) of the intimal aortic surface in the control group, and 14.9 +/- 2.1% in the treated group (p less than 0.001). The values of total and free cholesterol, esterified cholesterol, and phospholipids deposited within vessel wall were significantly lower in the aortas of the HDL-VHDL treated group than those in the control group. Cholesterol accumulation in the livers was also significantly lower (p less than 0.01) in the treated group than in the control. We concluded that administration of homologous HDL-VHDL lipoprotein fraction to cholesterol-fed rabbits, dramatically inhibited the extent of aortic fatty streaks and lowered lipid deposition in the arterial wall and liver without modification of the plasma lipid levels. PMID:2927083

  11. Counterpoint: Low-Density Lipoprotein Cholesterol Targets Are Not Needed in Lipid Treatment Guidelines.

    PubMed

    Robinson, Jennifer G; Ray, Kausik

    2016-04-01

    On the basis of accumulating evidence, low-density lipoprotein cholesterol (LDL-C) treat-to-goal approaches no longer seem to be the best way to optimize lipid-modifying therapy to prevent atherosclerotic cardiovascular disease (ASCVD). The potential for a net ASCVD risk reduction benefit is a more individualized approach to clinical decision making and may better inform patient preferences. However, risk estimation tools will need to be developed to facilitate more personalized CVD risk estimation in statin-treated patients. In the meantime, LDL-C thresholds rather than targets may aid in determining which patients might benefit from additional LDL-C-lowering therapy beyond statins. PMID:26988588

  12. Myeloperoxidase/nitrite-mediated lipid peroxidation of low-density lipoprotein as modulated by flavonoids.

    PubMed

    Kostyuk, Vladimir A; Kraemer, Tilo; Sies, Helmut; Schewe, Tankred

    2003-02-27

    In the presence of a H(2)O(2)-generating system, myeloperoxidase (MPO) caused conjugated diene formation in low-density lipoprotein (LDL), indicating lipid peroxidation which was dependent on nitrite but not on chloride. The oxidation of LDL was inhibited by micromolar concentrations of flavonoids such as (-)-epicatechin, quercetin, rutin, taxifolin and luteolin, presumably via scavenging of the MPO-derived NO(2) radical. The flavonoids served as substrates of MPO leading to products with distinct absorbance spectra. The MPO-catalyzed oxidation of flavonoids was accelerated in the presence of nitrite. PMID:12606047

  13. Synthetic Nano-Low Density Lipoprotein as Targeted Drug DeliveryVehicle for Glioblastoma Multiforme

    SciTech Connect

    Nikanjam, Mina; Blakely, Eleanor A.; Bjornstad, Kathleen A.; Shu,Xiao; Budinger, Thomas F.; Forte, Trudy M.

    2006-06-14

    This paper discribes a synthetic low density lipoprotein(LDL) made by complexing a 29 amino acid that consists of a lipid bindingdomain and the LDL receptor binding domain with a lipid microemulsion.The nano-LDL particles were intermdiate in size between LDL and HDL andbound to LDL receptors on GBM brain tumor cells. Synthetic nano-LDLuptake by GBM cells was LDL receptor specific and dependent on cellreceptor number. It is suggested that these synthetic particles can serveas a delivery vehicle for hydophobic anti-tumor drugs by targeting theLDL receptor.

  14. Synthetic high-density lipoprotein-like nanoparticles for cancer therapy

    PubMed Central

    Foit, Linda; Giles, Francis J.; Gordon, Leo I.; Thaxton, C. Shad

    2015-01-01

    Summary High-density lipoproteins (HDLs) are a diverse group of natural nanoparticles that are most well-known for their role in cholesterol transport. However, HDLs have diverse functions that provide significant opportunities for cancer therapy. Presented is a focused review of the ways that synthetic versions of HDL have been used as targeted therapies for cancer, and as vehicles for the delivery of diverse therapeutic cargo to cancer cells. As such, synthetic HDLs are likely to play a central role in the development of next generation cancer therapies. PMID:25487833

  15. Changes in remnant and high-density lipoproteins associated with hormone therapy and progression of coronary artery disease in postmenopausal women

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of hormone therapy (HT) on the plasma concentration of remnant lipoprotein cholesterol (RLP-C) and high density lipoprotein (HDL) subpopulations and the contribution of HT-related changes in these lipoproteins to the progression of coronary heart disease (CHD) were examined in 256 postmen...

  16. A-IMilano apoprotein. Decreased high density lipoprotein cholesterol levels with significant lipoprotein modifications and without clinical atherosclerosis in an Italian family.

    PubMed Central

    Franceschini, G; Sirtori, C R; Capurso, A; Weisgraber, K H; Mahley, R W

    1980-01-01

    Significant hypertriglyceridemia with a very marked decrease of high density lipoproteins (HDL)-cholesterol levels (7-14 mg/dl) was detected in three members (father, son, and daughter) of an Italian family. The three affected individuals did not show any clinical signs of atherosclerosis, nor was the atherosclerotic disease significantly present in the family. Lipoprotein lipase and lecithin:cholesterol acyltransferase activites were normal or slightly reduced. Morphological and compositional studies of HDL in the subjects showed a significant enlargement of the lipoprotein particles (approximately 120 vs. approximately 94 A for control HDL) and a concomitant increase in the triglyceride content. Analytical isoelectric focusing of HDL apoproteins provided evidence for multiple isoproteins in the apoprotein(apo)-A-I range, with nine different bands being detected instead of the usual four bands observed in normal subjects. Two-dimensional immunoelectrophoresis against apo-A antiserum indicated a clear reduction of apo-A in the alpha electrophoretic region, with splitting of the protein "peak." The observation in otherwise clinically healthy subjects of hypertriglyceridemia, reduced HDL-cholesterol, and marked apoprotein abnormalities, without a significant incidence of atherosclerotic disease in the family suggests this is a new disease entity in the field of lipoprotein pathology, very probably related to an altered amino acid composition of the apo-A-I protein (see Weisgraber et al. 1980. J. Clin. Invest. 66: 901-907). Images PMID:7430351

  17. Lower Low-Density Lipoprotein Cholesterol Levels Are Associated with Severe Dengue Outcome.

    PubMed

    Biswas, Hope H; Gordon, Aubree; Nuñez, Andrea; Perez, Maria Angeles; Balmaseda, Angel; Harris, Eva

    2015-01-01

    Dengue virus (DENV) is a flavivirus of worldwide importance, with approximately 4 billion people across 128 countries at risk of infection, and up to 390 million infections and 96 million clinically apparent cases estimated annually. Previous in vitro studies have shown that lipids and lipoproteins play a role in modifying virus infectivity. However, the relationship between development of severe dengue and total cholesterol, high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C), respectively, is unclear. We analyzed data from 789 laboratory-confirmed dengue cases and 447 other febrile illnesses (OFI) in a prospective pediatric hospital-based study in Managua, Nicaragua between August 2005 and January 2013, using three different classifications of dengue severity: World Health Organization (WHO) 1997, WHO 2009, and standardized intervention categories. Total serum cholesterol and LDL-C levels decreased over the course of illness and were generally lower with increasing dengue severity, regardless of classification scheme. Greater decreases in LDL-C than HDL-C were observed among dengue-positive patients compared to patients with OFI and among severe dengue compared to mild dengue cases. Furthermore, daily cholesterol levels declined with daily albumin blood levels. To examine the effect of cholesterol at presentation on subsequent risk of development of severe dengue, relative risks and 95% confidence intervals were calculated using multivariable modified Poisson models. We found that lower total serum cholesterol and LDL-C levels at presentation were associated with subsequent risk of developing dengue hemorrhagic fever/dengue shock syndrome using the WHO 1997 dengue severity classification, and thus that the reduction in LDL-C is likely driving the decreases observed in total serum cholesterol levels among dengue-positive patients. Our results suggest that cholesterol blood levels are important correlates of dengue pathophysiology and should be explored as part of a prognostic biomarker panel for severe dengue. PMID:26334914

  18. Receptor-mediated uptake of low density lipoprotein stimulates bile acid synthesis by cultured rat hepatocytes

    SciTech Connect

    Junker, L.H.; Davis, R.A. )

    1989-12-01

    The cellular mechanisms responsible for the lipoprotein-mediated stimulation of bile acid synthesis in cultured rat hepatocytes were investigated. Adding 280 micrograms/ml of cholesterol in the form of human or rat low density lipoprotein (LDL) to the culture medium increased bile acid synthesis by 1.8- and 1.6-fold, respectively. As a result of the uptake of LDL, the synthesis of (14C)cholesterol from (2-14C)acetate was decreased and cellular cholesteryl ester mass was increased. Further studies demonstrated that rat apoE-free LDL and apoE-rich high density lipoprotein (HDL) both stimulated bile acid synthesis 1.5-fold, as well as inhibited the formation of (14C)cholesterol from (2-14C)acetate. Reductive methylation of LDL blocked the inhibition of cholesterol synthesis, as well as the stimulation of bile acid synthesis, suggesting that these processes require receptor-mediated uptake. To identify the receptors responsible, competitive binding studies using 125I-labeled apoE-free LDL and 125I-labeled apoE-rich HDL were performed. Both apoE-free LDL and apoE-rich HDL displayed an equal ability to compete for binding of the other, suggesting that a receptor or a group of receptors that recognizes both apolipoproteins is involved. Additional studies show that hepatocytes from cholestyramine-treated rats displayed 2.2- and 3.4-fold increases in the binding of apoE-free LDL and apoE-rich HDL, respectively. These data show for the first time that receptor-mediated uptake of LDL by the liver is intimately linked to processes activating bile acid synthesis.

  19. Lower Low-Density Lipoprotein Cholesterol Levels Are Associated with Severe Dengue Outcome

    PubMed Central

    Biswas, Hope H.; Gordon, Aubree; Nuñez, Andrea; Perez, Maria Angeles; Balmaseda, Angel; Harris, Eva

    2015-01-01

    Dengue virus (DENV) is a flavivirus of worldwide importance, with approximately 4 billion people across 128 countries at risk of infection, and up to 390 million infections and 96 million clinically apparent cases estimated annually. Previous in vitro studies have shown that lipids and lipoproteins play a role in modifying virus infectivity. However, the relationship between development of severe dengue and total cholesterol, high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C), respectively, is unclear. We analyzed data from 789 laboratory-confirmed dengue cases and 447 other febrile illnesses (OFI) in a prospective pediatric hospital-based study in Managua, Nicaragua between August 2005 and January 2013, using three different classifications of dengue severity: World Health Organization (WHO) 1997, WHO 2009, and standardized intervention categories. Total serum cholesterol and LDL-C levels decreased over the course of illness and were generally lower with increasing dengue severity, regardless of classification scheme. Greater decreases in LDL-C than HDL-C were observed among dengue-positive patients compared to patients with OFI and among severe dengue compared to mild dengue cases. Furthermore, daily cholesterol levels declined with daily albumin blood levels. To examine the effect of cholesterol at presentation on subsequent risk of development of severe dengue, relative risks and 95% confidence intervals were calculated using multivariable modified Poisson models. We found that lower total serum cholesterol and LDL-C levels at presentation were associated with subsequent risk of developing dengue hemorrhagic fever/dengue shock syndrome using the WHO 1997 dengue severity classification, and thus that the reduction in LDL-C is likely driving the decreases observed in total serum cholesterol levels among dengue-positive patients. Our results suggest that cholesterol blood levels are important correlates of dengue pathophysiology and should be explored as part of a prognostic biomarker panel for severe dengue. PMID:26334914

  20. Effects of Statins on High-Density Lipoproteins: A Potential Contribution to Cardiovascular Benefit

    PubMed Central

    Jones, Peter

    2008-01-01

    Purpose The objective was to systematically review clinical trial data on the effects of statins on high-density lipoproteins (HDL) and to examine the possibility that this provides cardiovascular benefits in addition to those derived from reductions in low-density lipoproteins (LDL). Methods The PubMed database was searched for publications describing clinical trials of atorvastatin, pravastatin, rosuvastatin, and simvastatin. On the basis of predefined criteria, 103 were selected for review. Results Compared with placebo, statins raise HDL, measured as HDL-cholesterol (HDL-C) and apolipoprotein A-I (apo A-I); these elevations are maintained in the long-term. In hypercholesterolemia, HDL-C is raised by approximately 4% to 10%. The percentage changes are greater in patients with low baseline levels, including those with the common combination of high triglycerides (TG) and low HDL-C. These effects do not appear to be dose-related although there is evidence that, with the exception of atorvastatin, the changes in HDL-C are proportional to reductions in apo B-containing lipoproteins. The most likely explanation is a reduced rate of cholesteryl ester transfer protein (CETP)-mediated flow of cholesterol from HDL. There is some evidence that the statin effects on HDL reduce progression of atherosclerosis and risk of cardiovascular disease independently of reductions in LDL. Conclusion Statins cause modest increases in HDL-C and apo A-I probably mediated by reductions in CETP activity. It is plausible that such changes independently contribute to the cardiovascular benefits of the statin class but more studies are needed to further explore this possibility. PMID:18553127

  1. Genetic risk scores associated with baseline lipoprotein subfraction concentrations do not associate with their responses to fenofibrate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lipoprotein subclass concentrations are modifiable markers of cardiovascular disease risk. Fenofibrate is known to show beneficial effects on lipoprotein subclasses, but little is known about the role of genetics in mediating the responses of lipoprotein subclasses to fenofibrate. A recent genomewid...

  2. Neutrophil–lymphocyte ratio is associated with low high-density lipoprotein cholesterol in healthy young men

    PubMed Central

    Tok, Duran; Ozenc, Salim

    2014-01-01

    Objective: It has been reported that the neutrophil–lymphocyte ratio is significantly elevated in patients with low high-density lipoprotein cholesterol (<35 mg/dL). But in this study, some patients had hypertension that may have affected the neutrophil–lymphocyte ratio. This study consisted of 1274 asymptomatic healthy young men. In contrast with the previous study, we investigated the neutrophil–lymphocyte ratio in healthy young men with low high-density lipoprotein cholesterol compared with controls. Methods: We studied 1274 asymptomatic young males (military personnel screening) who underwent routine health check-up. Of them, 102 subjects had low high-density lipoprotein cholesterol. Results: The neutrophil–lymphocyte ratio was significantly higher among the men with low high-density lipoprotein cholesterol than that of the control group (P < 0.001). Conclusion: We conclude that the neutrophil–lymphocyte ratio is significantly elevated in asymptomatic healthy young men with low high-density lipoprotein cholesterol compared with control participants. PMID:26770725

  3. Low-density lipoprotein-mimicking nanoparticles for tumor-targeted theranostic applications.

    PubMed

    Lee, Jeong Yu; Kim, Jin-Ho; Bae, Ki Hyun; Oh, Mi Hwa; Kim, Youngwook; Kim, Jee Seon; Park, Tae Gwan; Park, Keunchil; Lee, Jung Hee; Nam, Yoon Sung

    2015-01-14

    This study introduces multifunctional lipid nanoparticles (LNPs), mimicking the structure and compositions of low-density lipoproteins, for the tumor-targeted co-delivery of anti-cancer drugs and superparamagnetic nanocrystals. Paclitaxel (4.7 wt%) and iron oxide nanocrystals (6.8 wt%, 11 nm in diameter) are co-encapsulated within folate-functionalized LNPs, which contain a cluster of nanocrystals with an overall diameter of about 170 nm and a zeta potential of about -40 mV. The folate-functionalized LNPs enable the targeted detection of MCF-7, human breast adenocarcinoma expressing folate receptors, in T2 -weighted magnetic resonance images as well as the efficient intracellular delivery of paclitaxel. Paclitaxel-free LNPs show no significant cytotoxicity up to 0.2 mg mL(-1) , indicating the excellent biocompatibility of the LNPs for intracellular drug delivery applications. The targeted anti-tumor activities of the LNPs in a mouse tumor model suggest that the low-density lipoprotein-mimetic LNPs can be an effective theranostic platform with excellent biocompatibility for the tumor-targeted co-delivery of various anti-cancer agents. PMID:25137631

  4. Lowering low-density lipoprotein cholesterol levels in patients with type 2 diabetes mellitus

    PubMed Central

    Bays, Harold E

    2014-01-01

    Type 2 diabetes mellitus (T2DM) is characterized by hyperglycemia, insulin resistance, and/or progressive loss of β-cell function. T2DM patients are at increased risk of micro- and macrovascular disease, and are often considered as representing an atherosclerotic coronary heart disease (CHD) risk equivalent. Interventions directed at glucose and lipid level control in T2DM patients may reduce micro- and macrovascular disease. The optimal T2DM agent is one that lowers glucose levels with limited risk for hypoglycemia, and with no clinical trial evidence of worsening CHD risk. Lipid-altering drugs should preferably reduce low-density lipoprotein cholesterol and apolipoprotein B (apo B) and have evidence that the mechanism of action reduces CHD risk. Statins reduce low-density lipoprotein cholesterol and apo B and have evidence of improving CHD outcomes, and are thus first-line therapy for the treatment of hypercholesterolemia. In patients who do not achieve optimal lipid levels with statin therapy, or who are intolerant to statin therapy, add-on therapy or alternative therapies may be indicated. Additional available agents to treat hypercholesterolemic patients with T2DM include bile acid sequestrants, fibrates, niacin, and ezetimibe. This review discusses the use of these alternative agents to treat hypercholesterolemia in patients with T2DM, either as monotherapy or in combination with statin therapy. PMID:25045281

  5. alpha-tocopherol enrichment of high-density lipoproteins: stabilization of hydroperoxides produced during copper oxidation.

    PubMed

    Laureaux, C; Therond, P; Bonnefont-Rousselot, D; Troupel, S E; Legrand, A; Delattre, J

    1997-01-01

    In the aim to study the effect of an in vitro enrichment of high-density lipoprotein (HDL) with alpha-tocopherol in alcoholic solution on a copper-induced peroxidation, we monitored several markers of lipid peroxidation (alpha-tocopherol consumption, formation of conjugated dienes and of fatty acid hydroperoxides, production of thiobarbituric acid-reactive substances) and the integrity of apolipoprotein A-I. High-density lipoproteins (1.063 < d < 1.21) with a mean of 0.58 alpha-tocopherol molecules per HDL particle were enriched with alpha-tocopherol in alcoholic solution to obtain an average of 3.7 and 21 alpha-tocopherol molecules per HDL particle. HDL oxidation with 5 microM CuSO4 at 37 degrees C resulted in the total disappearance of endogenous alpha-tocopherol after 2 h, but after 24 h about 19% of alpha-tocopherol remained in the most enriched HDL. In agreement with the tocopherol-mediated peroxidation, the formation of conjugated dienes and of fatty acid hydroperoxides was very fast and increased with alpha-tocopherol concentration, whereas TBARS production decreased. These results showed that alpha-tocopherol enrichment stabilized the production of hydroperoxides in HDL and decreased the formation of secondary oxidation products. These latter products are known for deleterious effects towards apolipoproteins. This could explain why we observed that the apolipoprotein A-I of the most enriched HDL was only slightly altered after incubation with CuSO4. PMID:8958143

  6. High-Density Lipoprotein Mimetics: a Therapeutic Tool for Atherosclerotic Diseases.

    PubMed

    Ikenaga, Masahiro; Higaki, Yasuki; Saku, Keijiro; Uehara, Yoshinari

    2016-04-01

    Clinical trials and epidemiological studies have revealed a negative correlation between serum high-density lipoprotein (HDL) cholesterol levels and the risk of cardiovascular events. Currently, statin treatment is the standard therapy for cardiovascular diseases, reducing plasma low-density lipoprotein (LDL) cholesterol levels. However, more than half of the patients have not been able to receive the beneficial effects of this treatment.The reverse cholesterol transport pathway has several potential anti-atherogenic properties. An important approach to HDL-targeted therapy is the optimization of HDL cholesterol levels and function in the blood to enhance the removal of circulating cholesterol and to prevent or mitigate inflammation that causes atherosclerosis. Cholesteryl ester transfer protein inhibitors increase HDL cholesterol levels in humans, but whether they reduce the risk of atherosclerotic diseases is unknown. HDL therapies using HDL mimetics, including reconstituted HDL, apolipoprotein (Apo) A-IMilano, ApoA-I mimetic peptides, or full-length ApoA-I, are highly effective in animal models. In particular, the Fukuoka University ApoA-I-mimetic peptide (FAMP) effectively removes cholesterol via the ABCA1 transporter and acts as an anti-atherosclerotic agent by enhancing the biological functions of HDL without elevating HDL cholesterol levels.Our literature review suggests that HDL mimetics have significant atheroprotective potential and are a therapeutic tool for atherosclerotic diseases. PMID:26830201

  7. Low Density Lipoprotein-Containing Circulating Immune Complexes: Role in Atherosclerosis and Diagnostic Value

    PubMed Central

    Sobenin, Igor A.; Salonen, Jukka T.; Zhelankin, Andrey V.; Melnichenko, Alexandra A.; Kaikkonen, Jari; Bobryshev, Yuri V.; Orekhov, Alexander N.

    2014-01-01

    It has been suggested that low density lipoprotein-containing circulating immune complexes (LDL-CIC) play a role in atherogenesis and are involved in the formation of early atherosclerotic lesion. These complexes, as well as anti-LDL autoantibodies, have been found in the blood and in the atherosclerotic lesions of patients with different cardiovascular diseases, as well as in the blood of animals with experimental atherosclerosis. It can be suggested that the presence of anti-LDL antibodies in the blood is a result of immune response induced by lipoprotein modification. LDL-CIC differs from native LDL in many aspects. It has much lower sialic acid content, smaller diameter, and higher density and is more electronegative than native LDL. Fraction of LDL-CICs is fundamental to the serum atherogenicity manifested at the cellular level. LDL-CIC, unlike native LDL, is able to induce intracellular accumulation of neutral lipids, especially esterified cholesterol, in cells cultured from uninvolved human aortic intima and in macrophage cultures. After removal of LDL-CIC, the CHD patient's sera lose their atherogenic properties. Titer of LDL-CIC in blood serum significantly correlates with progression of atherosclerosis in human in vivo and has the highest diagnostic value among other measured serum lipid parameters. Elevated CIC-cholesterol might well be a possible risk factor of coronary atherosclerosis. PMID:25054132

  8. Generation in Human Plasma of Misfolded, Aggregation-Prone Electronegative Low Density Lipoprotein

    PubMed Central

    Greco, Giulia; Balogh, Gabor; Brunelli, Roberto; Costa, Graziella; De Spirito, Marco; Lenzi, Laura; Mei, Giampiero; Ursini, Fulvio; Parasassi, Tiziana

    2009-01-01

    Abstract Human plasma contains small amounts of a low density lipoprotein in which apoprotein is misfolded. Originally identified and isolated by means of anion-exchange chromatography, this component was subsequently described as electronegative low density lipoprotein (LDL)(−), with increased concentrations associated with elevated cardiovascular disease risk. It has been recognized recently as the trigger of LDL amyloidogenesis, which produces aggregates similar to subendothelial droplets observed in vivo in early atherogenesis. Although LDL(−) has been produced in vitro through various manipulations, the mechanisms involved in its generation in vivo remain obscure. By using a more physiological model, we demonstrate spontaneous, sustained and noticeable production of LDL(−) during incubation of unprocessed human plasma at 37°C. In addition to a higher fraction of amyloidogenic LDL(−), LDL purified from incubated plasma contains an increased level of lysophospholipids and free fatty acids; analysis of LDL lipids packing shows their loosening. As a result, during plasma incubation, lipid destabilization and protein misfolding take place, and aggregation-prone particles are generated. All these phenomena can be prevented by inhibiting calcium-dependent secretory phospholipases A2. Our plasma incubation model, without removal of reaction products, effectively shows a lipid-protein interplay in LDL, where lipid destabilization after lipolysis threatens the apoprotein's structure, which misfolds and becomes aggregation-prone. PMID:19619478

  9. Effect of apolipoprotein E-free high density lipoproteins on cholesterol metabolism in cultured pig hepatocytes

    SciTech Connect

    Bachorik, P.S.; Virgil, D.G.; Kwiterovich, P.O. Jr.

    1987-10-05

    We studied cholesterol synthesis from (/sup 14/C)acetate, cholesterol esterification from (/sup 14/C)oleate, and cellular cholesterol and cholesteryl ester levels after incubating cells with apoE-free high density lipoproteins (HDL) or low density lipoproteins (LDL). LDL suppressed synthesis by up to 60%, stimulated esterification by up to 280%, and increased cell cholesteryl ester content about 4-fold. Esterification increased within 2 h, but synthesis was not suppressed until after 6 h. ApoE-free HDL suppressed esterification by about 50% within 2 h. Cholesterol synthesis was changed very little within 6 h, unless esterification was maximally suppressed; synthesis was then stimulated about 4-fold. HDL lowered cellular unesterified cholesterol by 13-20% within 2 h and promoted the removal of newly synthesized cholesterol and cholesteryl esters. These changes were transient; by 24 h, both esterification and cellular unesterified cholesterol returned to control levels, and cholesteryl esters increased 2-3-fold. HDL core lipid was taken up selectively from /sup 125/I-labeled (/sup 3/H)cholesteryl ester- and ether-labeled HDL. LDL core lipid uptake was proportional to LDL apoprotein uptake. The findings suggest that 1) the cells respond initially to HDL or LDL with changes in esterification, and 2) HDL mediates both the removal of free cholesterol from the cell and the delivery of HDL cholesteryl esters to the cell.

  10. Novel Changes in Discoidal High Density Lipoprotein Morphology: A Molecular Dynamics Study

    PubMed Central

    Catte, Andrea; Patterson, James C.; Jones, Martin K.; Jerome, W. Gray; Bashtovyy, Denys; Su, Zhengchang; Gu, Feifei; Chen, Jianguo; Aliste, Marcela P.; Harvey, Stephen C.; Li, Ling; Weinstein, Gilbert; Segrest, Jere P.

    2006-01-01

    ApoA-I is a uniquely flexible lipid-scavenging protein capable of incorporating phospholipids into stable particles. Here we report molecular dynamics simulations on a series of progressively smaller discoidal high density lipoprotein particles produced by incremental removal of palmitoyloleoylphosphatidylcholine via four different pathways. The starting model contained 160 palmitoyloleoylphosphatidylcholines and a belt of two antiparallel amphipathic helical lipid-associating domains of apolipoprotein (apo) A-I. The results are particularly compelling. After a few nanoseconds of molecular dynamics simulation, independent of the starting particle and method of size reduction, all simulated double belts of the four lipidated apoA-I particles have helical domains that impressively approximate the x-ray crystal structure of lipid-free apoA-I, particularly between residues 88 and 186. These results provide atomic resolution models for two of the particles produced by in vitro reconstitution of nascent high density lipoprotein particles. These particles, measuring 95 Å and 78 Å by nondenaturing gradient gel electrophoresis, correspond in composition and in size/shape (by negative stain electron microscopy) to the simulated particles with molar ratios of 100:2 and 50:2, respectively. The lipids of the 100:2 particle family form minimal surfaces at their monolayer-monolayer interface, whereas the 50:2 particle family displays a lipid pocket capable of binding a dynamic range of phospholipid molecules. PMID:16581834

  11. Novel mutations of low-density lipoprotein receptor gene in China patients with familial hypercholesterolemia.

    PubMed

    Fan, Liang-liang; Lin, Min-jie; Chen, Ya-qin; Huang, Hao; Peng, Dao-quan; Xia, Kun; Zhao, Shui-ping; Xiang, Rong

    2015-05-01

    Familial hypercholesterolaemia (FH) is an autosomal dominant genetic disorder, associated with elevated level of serum low-density lipoprotein-cholesterol (LDL-C), which can lead to premature cardiovascular disease (CVD). Mutations in low density lipoprotein receptor (LDLR) and proprotein convertase subtilisin/kexin type 9 (PCSK9) have been identified to be the underlying cause of this disease. Genetic research of FH has already been extensively studied all over the world. However, reports of FH mutations in the Chinese population are still limited. In this paper, 20 unrelated FH families were enrolled to detect the candidate gene variants in Chinese FH population by DNA direct sequencing. We identified 12 LDLR variants in 13 FH probands. Importantly, we first reported two unique mutations (c.2000_2000 delG/p.C667LfsX6 and c.605T>C/p.F202S) in LDLR gene. Our discoveries expand the spectrum of LDLR mutations and contribute to the genetic diagnosis and counseling for FH patients. PMID:25846081

  12. Helicobacter pylori Infection is Associated with Elevated Low Density Lipoprotein Cholesterol Levels in Elderly Koreans

    PubMed Central

    Kim, Hack-Lyoung; Jeon, Han Ho; Park, In Young; Choi, Jin Man; Kang, Ji Sun

    2011-01-01

    This study was conducted to investigate the association between Helicobacter pylori (H. pylori) infection and the lipid profile among elderly Koreans. A total of 462 subjects (mean age 66.2 ± 7.6 yr, 84% males) who underwent health check-up were investigated. Each subject underwent gastroduodenoscopy with gastric mucosal biopsy, and H. pylori infection was determined by histopathological examination using the updated Sydney System score. The presence of H. pylori infection was significantly associated with the elevated serum levels of total cholesterol and low density lipoprotein (LDL) cholesterol (P < 0.05 for each) in univariate analysis. H. pylori infection was not associated with triglyceride and high density lipoprotein (HDL) cholesterol levels (P > 0.05 for each). After controlling confounders, multiple logistic regression analysis showed that the odds ratio of H. pylori infection for high LDL cholesterol level (> 140 mg/dL) was 3.113 (95% confidence interval, 1.364-7.018; P = 0.007). There were no significant associations between the presence of H. pylori infection and elevated total cholesterol levels (> 200 mg/dL) in this model (P = 0.586). The results of this study demonstrate that H. pylori infection is associated with the elevated serum LDL cholesterol levels in elderly Koreans, supporting the hypothesis that H. pylori plays a role in promoting atherosclerosis by modifying lipid metabolism. PMID:21532857

  13. Effect of Extended-Release Niacin on High-Density Lipoprotein (HDL) Functionality, Lipoprotein Metabolism, and Mediators of Vascular Inflammation in Statin-Treated Patients

    PubMed Central

    Yadav, Rahul; Liu, Yifen; Kwok, See; Hama, Salam; France, Michael; Eatough, Ruth; Pemberton, Phil; Schofield, Jonathan; Siahmansur, Tarza J; Malik, Rayaz; Ammori, Basil A; Issa, Basil; Younis, Naveed; Donn, Rachelle; Stevens, Adam; Durrington, Paul; Soran, Handrean

    2015-01-01

    Background The aim of this study was to explore the influence of extended-release niacin/laropiprant (ERN/LRP) versus placebo on high-density lipoprotein (HDL) antioxidant function, cholesterol efflux, apolipoprotein B100 (apoB)-containing lipoproteins, and mediators of vascular inflammation associated with 15% increase in high-density lipoprotein cholesterol (HDL-C). Study patients had persistent dyslipidemia despite receiving high-dose statin treatment. Methods and Results In a randomized double-blind, placebo-controlled, crossover trial, we compared the effect of ERN/LRP with placebo in 27 statin-treated dyslipidemic patients who had not achieved National Cholesterol Education Program-ATP III targets for low-density lipoprotein cholesterol (LDL-C). We measured fasting lipid profile, apolipoproteins, cholesteryl ester transfer protein (CETP) activity, paraoxonase 1 (PON1) activity, small dense LDL apoB (sdLDL-apoB), oxidized LDL (oxLDL), glycated apoB (glyc-apoB), lipoprotein phospholipase A2 (Lp-PLA2), lysophosphatidyl choline (lyso-PC), macrophage chemoattractant protein (MCP1), serum amyloid A (SAA) and myeloperoxidase (MPO). We also examined the capacity of HDL to protect LDL from in vitro oxidation and the percentage cholesterol efflux mediated by apoB depleted serum. ERN/LRP was associated with an 18% increase in HDL-C levels compared to placebo (1.55 versus 1.31 mmol/L, P<0.0001). There were significant reductions in total cholesterol, triglycerides, LDL cholesterol, total serum apoB, lipoprotein (a), CETP activity, oxLDL, Lp-PLA2, lyso-PC, MCP1, and SAA, but no significant changes in glyc-apoB or sdLDL-apoB concentration. There was a modest increase in cholesterol efflux function of HDL (19.5%, P=0.045), but no change in the antioxidant capacity of HDL in vitro or PON1 activity. Conclusions ERN/LRP reduces LDL-associated mediators of vascular inflammation, but has varied effects on HDL functionality and LDL quality, which may counter its HDL-C-raising effect. Clinical Trial Registration URL: http://www.clinicaltrials.gov. Unique identifier: NCT01054508. PMID:26374297

  14. A simple and sensitive method for lipoprotein and lipids profiles analysis of individual micro-liter scale serum samples.

    PubMed

    Yang, Liu; Fan, Baoyan; Yang, Kangmin; Zhu, Haibo

    2012-02-01

    A simple and sensitive method to determine lipoprotein and lipids profiles in micro-liter scale individual serum sample is not presently available. Traditional lipoprotein separation techniques either by ultra-centrifugation or by liquid chromatography methods have their disadvantages in both lipoprotein separation and lipids component quantification. In this study we used small volume needing size-exclusion fast protein liquid chromatography to separate different lipoprotein subclasses in 50μL serum. And lipids contents, such as cholesterol, cholesterol ester and triacylglycerol, were measured by using two different fluorescence-based lipid detection methods. With this method, very low density lipoprotein, low density lipoprotein and high density lipoprotein could be easily separated, and follow-up lipid detection was completed by simple kinds of reactions. Serum lipoprotein and lipids profiling from C57BL/6 mice (n=5) and human (n=5) were analyzed. The elution profiles of five individuals were highly reproducible, and there were lipoprotein and lipids distribution variations between C57BL/6 mice and human beings. In conclusion, this method which combined small volume needing size-exclusion fast protein liquid chromatography and fluorescence-based lipids measurement, provided a simple, efficient, integrity and reproducible procedure for determining serum lipoprotein and lipids profiles in micro-liter scale levels. It becomes possible that determination of lipoprotein profiles and gaining information of lipids in different lipoproteins can be accomplished simultaneously. PMID:22155352

  15. Characterization of high density lipoprotein binding to human adipocyte plasma membranes.

    PubMed Central

    Fong, B S; Rodrigues, P O; Salter, A M; Yip, B P; Despres, J P; Angel, A; Gregg, R E

    1985-01-01

    Freshly isolated human adipocytes showed specific uptake of 125I-labeled human high density lipoprotein (HDL2 and HDL3), a portion of which could be released by subsequent incubation with excess unlabeled ligand. To study the mechanism of HDL binding, sucrose gradient-purified adipocyte plasma membranes were incubated with radioiodinated lipoprotein particles under equilibrium conditions in the absence (total binding) or presence (nonspecific binding) of 100-fold excess unlabeled ligand. Specific binding of HDL2 and HDL3, calculated by subtracting nonspecific from total binding, was Ca++ independent, unaffected by EDTA, and not abolished by pronase treatment of the membranes. Modification of HDL3 by reductive methylation or cyclohexanedione treatment also failed to affect its binding to adipocyte plasma membranes. High salt concentration (200 mM NaCl) inhibited specific binding of HDL2 and HDL3 but had no effect on LDL binding. A significant portion of 125I-HDL2 or 125I-HDL3 binding was consistently inhibited by adding excess unlabeled LDL, but this inhibition was incomplete as compared with a similar molar excess of unlabeled HDL2 or HDL3. The role of apoproteins (apo) in HDL binding to adipocyte membranes was examined by comparing binding of HDL2 and HDL3 isolated from normal, abetalipoproteinemic (abeta) and apo E-deficient (apo E0) plasma. Specific binding was observed with all normal and mutant HDL particles. Furthermore, a significant portion (61-78%) of abeta-HDL2, apo E0-HDL2, and apo E0-HDL3 binding was inhibited by adding 100-fold excess of unlabeled low density lipoproteins (LDL). The cross-competition of LDL and HDL binding was confirmed by the ability of normal, abeta, and apo E0-HDL2 to completely inhibit 125I-LDL binding. These data suggest that HDL binding is independent of apo E and that the responsible apoprotein(s) of HDL complete with LDL-apo B for binding to the same or closely related site in the adipocyte plasma membrane. Normal and apo E0-HDL3 binding was also completely inhibited by normal HDL2, which suggested that HDL2 and HDL3 probably bind to the same site. Scatchard analysis of normal HDL2, normal HDL3, and apo E0-HDL3 binding data best fitted a one-component binding profile with similar equilibrium dissociation constants (40-96 nM). HDL3 binding was found to be effectively inhibited by anti-human apo AI or anti-human apo AII, but not by anti-human apo B antisera. This binding was also unaffected by monoclonal anti-human apo B or E antibodies known to inhibit binding of apo B or apo E containing lipoprotein to the LDL receptor of cultured fibroblasts. These findings, taken together, suggest that human fat cells possess HDL binding sites with apo AI and /or apo AII specificity. The significant but partial inhibition of HDL2 and HDL3 binding by LDL along with the complete inhibition of LDL binding by HDL2 and HDL3 tends to exclude a single binding site that interacts both lipoproteins and favors the interpretation that LDL and HDL particles bind to multiple recognition sites or to different conformation of the same lipoprotein binding domain on the human fat cell. Images PMID:2989332

  16. Effects of maximal doses of atorvastatin versus rosuvastatin on small dense low-density lipoprotein cholesterol levels

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maximal doses of atorvastatin and rosuvastatin are highly effective in lowering low-density lipoprotein (LDL) cholesterol and triglyceride levels; however, rosuvastatin has been shown to be significantly more effective than atorvastatin in lowering LDL cholesterol and in increasing high-density lipo...

  17. Structural Insights into High Density Lipoprotein: Old Models and New Facts

    PubMed Central

    Gogonea, Valentin

    2016-01-01

    The physiological link between circulating high density lipoprotein (HDL) levels and cardiovascular disease is well-documented, albeit its intricacies are not well-understood. An improved appreciation of HDL function and overall role in vascular health and disease requires at its foundation a better understanding of the lipoprotein's molecular structure, its formation, and its process of maturation through interactions with various plasma enzymes and cell receptors that intervene along the pathway of reverse cholesterol transport. This review focuses on summarizing recent developments in the field of lipid free apoA-I and HDL structure, with emphasis on new insights revealed by newly published nascent and spherical HDL models constructed by combining low resolution structures obtained from small angle neutron scattering (SANS) with contrast variation and geometrical constraints derived from hydrogen–deuterium exchange (HDX), crosslinking mass spectrometry, electron microscopy, Förster resonance energy transfer, and electron spin resonance. Recently published low resolution structures of nascent and spherical HDL obtained from SANS with contrast variation and isotopic labeling of apolipoprotein A-I (apoA-I) will be critically reviewed and discussed in terms of how they accommodate existing biophysical structural data from alternative approaches. The new low resolution structures revealed and also provided some answers to long standing questions concerning lipid organization and particle maturation of lipoproteins. The review will discuss the merits of newly proposed SANS based all atom models for nascent and spherical HDL, and compare them with accepted models. Finally, naturally occurring and bioengineered mutations in apoA-I, and their impact on HDL phenotype, are reviewed and discuss together with new therapeutics employed for restoring HDL function. PMID:26793109

  18. Identification of Critical Paraoxonase 1 Residues Involved in High Density Lipoprotein Interaction.

    PubMed

    Gu, Xiaodong; Huang, Ying; Levison, Bruce S; Gerstenecker, Gary; DiDonato, Anthony J; Hazen, Leah B; Lee, Joonsue; Gogonea, Valentin; DiDonato, Joseph A; Hazen, Stanley L

    2016-01-22

    Paraoxonase 1 (PON1) is a high density lipoprotein (HDL)-associated protein with atherosclerosis-protective and systemic anti-oxidant functions. We recently showed that PON1, myeloperoxidase, and HDL bind to one another in vivo forming a functional ternary complex (Huang, Y., Wu, Z., Riwanto, M., Gao, S., Levison, B. S., Gu, X., Fu, X., Wagner, M. A., Besler, C., Gerstenecker, G., Zhang, R., Li, X. M., Didonato, A. J., Gogonea, V., Tang, W. H., et al. (2013) J. Clin. Invest. 123, 3815-3828). However, specific residues on PON1 involved in the HDL-PON1 interaction remain unclear. Unambiguous identification of protein residues involved in docking interactions to lipid surfaces poses considerable methodological challenges. Here we describe a new strategy that uses a novel synthetic photoactivatable and click chemistry-taggable phospholipid probe, which, when incorporated into HDL, was used to identify amino acid residues on PON1 that directly interact with the lipoprotein phospholipid surface. Several specific PON1 residues (Leu-9, Tyr-185, and Tyr-293) were identified through covalent cross-links with the lipid probes using affinity isolation coupled to liquid chromatography with on-line tandem mass spectrometry. Based upon the crystal structure for PON1, the identified residues are all localized in relatively close proximity on the surface of PON1, defining a domain that binds to the HDL lipid surface. Site-specific mutagenesis of the identified PON1 residues (Leu-9, Tyr-185, and Tyr-293), coupled with functional studies, reveals their importance in PON1 binding to HDL and both PON1 catalytic activity and stability. Specifically, the residues identified on PON1 provide important structural insights into the PON1-HDL interaction. More generally, the new photoactivatable and affinity-tagged lipid probe developed herein should prove to be a valuable tool for identifying contact sites supporting protein interactions with lipid interfaces such as found on cell membranes or lipoproteins. PMID:26567339

  19. Tissue sites of degradation of high density lipoprotein apolipoprotein A-IV in rats

    SciTech Connect

    Dallinga-Thie, G.M.; Van 't Hooft, F.M.; Van Tol, A.

    1986-05-01

    The in vivo metabolism of high density lipoprotein (HDL), labeled by incorporation of /sup 125/I-apolipoprotein (apo) A-IV, was studied in the rat and compared with the metabolism of HDL labeled with 131I-apo A-I. The /sup 125/I-apo A-IV labeled HDL was obtained by adding small amounts of radioiodinated apo A-IV to rat serum, followed by separation of the different lipoprotein fractions by chromatography on 6% agarose columns in order to avoid stripping of apolipoproteins by ultracentrifugation. Under both in vitro and in vivo conditions, the /sup 125/I-apo A-IV remained an integral component of HDL and was not exchanged to other lipoproteins, including the free apo A-IV fraction. The serum half-life, measured at between 8 and 28 hours after intravenous injection of labeled HDL, was 8.5 +/- 0.5 hours for HDL apo A-IV and 10.2 +/- 0.7 hours for HDL apo A-I. The tissue sites of catabolism of HDL apo A-IV and HDL apo A-I were analyzed in the leupeptin-model. Only the kidneys and liver showed a significant leupeptin-dependent accumulation of radioactivity. At 4 hours after injection of 125I-apo A-IV/131I-apo A-I labeled HDL, 3.5% +/- 1.0% and 8.4% +/- 2.0% of HDL apo A-IV and 4.6% +/- 1.3% and 2.6% +/- 0.6% of the HDL apo A-I were accumulated in a leupeptin-dependent process in the kidneys and liver, respectively. Immunocytochemical studies revealed that the renal localization of apo A-IV was intracellular and confined to the epithelial cells of the proximal tubuli.

  20. Retraction note: Correlation Between High-Density Lipoprotein and Monocyte Subsets in Patients with Stable Coronary Heart Disease.

    PubMed

    Stefano, George B

    2016-01-01

    In the article entitled, "Correlation Between High-Density Lipoprotein and Monocyte Subsets in Patients with Stable Coronary Heart Disease" which was published in Medical Science Monitor 2015;21: 3129-3135, sections in the text have been directly copied from a previously published article, entitled, "Small high-density lipoprotein is associated with monocyte subsets in stable coronary artery disease", Krychtiuk KA, Kastl SP, Pfaffenberger S, Pongratz T, Hofbauer SL, Wonnerth A, Katsaros KM, Goliasch G, Gaspar L, Huber K, Maurer G, Dostal E, Oravec S, Wojta J, Speidl WS  in Atherosclerosis 2014 Dec;237(2):589-96. Thus owing to duplicity of text, the article is being retracted. Reference: 1. Shaoyan Jiang, Dan Li, Jian Li, Yi An Correlation Between High-Density Lipoprotein and Monocyte Subsets in Patients with Stable Coronary Heart Disease Medical Science Monitor 2015;21: 3129-3135 DOI 10.12659/MSM.894485. PMID:26853100

  1. Postprandial lipoprotein metabolism; VLDL vs chylomicrons

    PubMed Central

    Nakajima, Katsuyuki; Nakano, Takamitsu; Tokita, Yoshiharu; Nagamine, Takeaki; Inazu, Akihiro; Kobayashi, Junji; Mabuchi, Hiroshi; Stanhope, Kimber L.; Havel, Peter J.; Okazaki, Mitsuyo; Ai, Masumi; Tanaka, Akira

    2012-01-01

    Since Zilversmit first proposed postprandial lipemia as the most common risk of cardiovascular disease, chylomicrons (CM) and CM remnants have been thought to be the major lipoproteins which are increased in the postprandial hyperlipidemia. However, it has been shown over the last two decades that the major increase in the postprandial lipoproteins after food intake occurs in the very low density lipoprotein (VLDL) remnants (apoB100 particles), not CM or CM remnants (apoB48 particles). This finding was obtained using the following three analytical methods; isolation of remnant-like lipoprotein particles (RLP) with specific antibodies, separation and detection of lipoprotein subclasses by gel permeation HPLC and determination of apoB48 in fractionated lipoproteins by a specific ELISA. The amount of the apoB48 particles in the postprandial RLP is significantly less than the apoB100 particles, and the particle sizes of apoB48 and apoB100 in RLP are very similar when analyzed by HPLC. Moreover, CM or CM remnants having a large amount of TG were not found in the postprandial RLP. Therefore, the major portion of the TG which is increased in the postprandial state is composed of VLDL remnants, which have been recognized as a significant risk for cardiovascular disease. PMID:21531214

  2. [Cholesterol bound to high density lipoproteins: critical review of the methods of analysis and personal data].

    PubMed

    Orso Giacone, G

    1982-01-01

    It is widely known that atherosclerosis through its complication, i.e. heart and brain infarction, is at the present the main cause of death. The atherosclerotic process has been shown in correlation with hyperlipemia especially as far as the plasma lipoprotein cholesterol level is concerned. A preminent role in removing cholesterol from tissues and arterial walls then in preventing atherosclerosis is played by a specific class of plasma lipoproteins, the high density lipoproteins (HDL). Since the HDL-colesterol level seems to have an inverse correlation with the atherosclerotic disease it is of primary importance to define a reliable and reproducible technique to measure it. One of the aims of this paper was to examine the different methods now available for such a determination. This analysis has underlined the discrepancy among the reference values reported in the literature. However, all the authors agree that only the simultaneous measurement of total and HDL-colesterol levels is of prognostic value. Personal studies are here reported on the relationship between total and HDL-colesterol levels and risk factor of cardiovascular diseases. The two mentioned laboratory analyses have been performed on blood samples from 250 between male and female human subjects of different age. The obtained results show that the highest HDL-colesterol concentrations determined by a lipoprotein precipitation procedure with dextran sulphate, are typical in the first ten years of life both in male and in female, while the lowest levels of plasma HDL-cholesterol have been evintiated during the fifth decade of life, when the total cholesterol and the risk of cardiovascular complications rich the highest values. In a following set of investigations, the already examined blood parameters together with the risk factor values have been examined in two groups of subjects, the first one represented by adult healthy persons the second one by patients of similar age from a cardiovascular division. The mean levels of total colesterol have been shown similar in both the experimental groups, while plasma HDL-cholesterol is significantly higher in the healthy group. This discrepancy is the cause of definitively higher risk factors in the hospitalized patients. In conclusion, the reported data furtherly stress that the total cholesterol values do not give "per se" any indication of atherogenic risk. They are useful only when examined together with the HDL-cholesterol levels. From that the opportunity to always include the determination of plasma HDL-cholesterol screening lipemic profiles. PMID:7137764

  3. Serum Paraoxonase 1 Activity Is Associated with Fatty Acid Composition of High Density Lipoprotein

    PubMed Central

    Boshtam, Maryam; Pourfarzam, Morteza; Ani, Mohsen; Naderi, Gholam Ali; Basati, Gholam; Mansourian, Marjan; Dinani, Narges Jafari; Asgary, Seddigheh; Abdi, Soheila

    2013-01-01

    Introduction. Cardioprotective effect of high density lipoprotein (HDL) is, in part, dependent on its related enzyme, paraoxonase 1 (PON1). Fatty acid composition of HDL could affect its size and structure. On the other hand, PON1 activity is directly related to the structure of HDL. This study was designed to investigate the association between serum PON1 activity and fatty acid composition of HDL in healthy men. Methods. One hundred and forty healthy men participated in this research. HDL was separated by sequential ultracentrifugation, and its fatty acid composition was analyzed by gas chromatography. PON1 activity was measured spectrophotometrically using paraxon as substrate. Results. Serum PON1 activity was directly correlated with the amount of stearic acid and dihomo-gamma-linolenic acid (DGLA). PON1/HDL-C was directly correlated with the amount of miristic acid, stearic acid, and DGLA and was inversely correlated with total amount of ω6 fatty acids of HDL. Conclusion. The fatty acid composition of HDL could affect the activity of its associated enzyme, PON1. As dietary fats are the major determinants of serum lipids and lipoprotein composition, consuming some special dietary fatty acids may improve the activity of PON1 and thereby have beneficial effects on health. PMID:24167374

  4. Underappreciated opportunities for high-density lipoprotein particles in risk stratification and potential targets of therapy.

    PubMed

    Rosenson, Robert S; Davidson, Michael H; Le, Ngoc-Anh; Burkle, Jaime; Pourfarzib, Ray

    2015-02-01

    The inverse relationship between high-density lipoprotein cholesterol (HDL-C) concentrations and coronary heart disease risk is well established. As a result, in recent years there have been significant resources focused on identifying therapies that raise HDL-C and ultimately reduce cardiovascular events. Unfortunately, a number of trials aimed at increasing HDL-C have failed to show improved outcomes, and hence, have cast doubt on the importance of HDL-C as a therapeutic target. HDL-C, however, is only one measure of HDL. HDL levels can also been estimated by quantifying apolipoprotein A-I (apoA-I) levels using enzyme immunoassay or by measuring HDL particle number (HDL-P) using nuclear magnetic resonance spectroscopy (NMR) or ion mobility. While these surrogate measures are correlated, they are not comparable. Lipoprotein-altering therapies have been shown to have different effects on HDL-C, apoA-I and HDL-P and several studies have demonstrated that HDL-P is a stronger predictor of coronary heart disease risk than HDL-C and/or apoA-I. This paper will review available evidence supporting the use of HDL-P as the biomarker of choice to assess the contribution of HDL to cardiovascular risk and as the primary goal of HDL-raising therapies. PMID:25702642

  5. Dysfunctional High-Density Lipoprotein: An Innovative Target for Proteomics and Lipidomics

    PubMed Central

    Salazar, Juan; Olivar, Luis Carlos; Ramos, Eduardo; Chávez-Castillo, Mervin; Rojas, Joselyn; Bermúdez, Valmore

    2015-01-01

    High-Density Lipoprotein-Cholesterol (HDL-C) is regarded as an important protective factor against cardiovascular disease, with abundant evidence of an inverse relationship between its serum levels and risk of cardiovascular disease, as well as various antiatherogenic, antioxidant, and anti-inflammatory properties. Nevertheless, observations of hereditary syndromes featuring scant HDL-C concentration in absence of premature atherosclerotic disease suggest HDL-C levels may not be the best predictor of cardiovascular disease. Indeed, the beneficial effects of HDL may not depend solely on their concentration, but also on their quality. Distinct subfractions of this lipoprotein appear to be constituted by specific protein-lipid conglomerates necessary for different physiologic and pathophysiologic functions. However, in a chronic inflammatory microenvironment, diverse components of the HDL proteome and lipid core suffer alterations, which propel a shift towards a dysfunctional state, where HDL-C becomes proatherogenic, prooxidant, and proinflammatory. This heterogeneity highlights the need for further specialized molecular studies in this aspect, in order to achieve a better understanding of this dysfunctional state; with an emphasis on the potential role for proteomics and lipidomics as valuable methods in the search of novel therapeutic approaches for cardiovascular disease. PMID:26634153

  6. High-density lipoprotein associated with secondary vitellogenesis in the hemolymph of the crayfish Cherax quadricarinatus.

    PubMed

    Yehezkel, G; Chayoth, R; Abdu, U; Khalaila, I; Sagi, A

    2000-11-01

    The high-density lipoproteins LPI and LPII were isolated from the hemolymph of the crayfish Cherax quadricarinatus by gradient ultracentrifugation and high-performance liquid chromatography (HPLC). Both lipoproteins contained a carotenoid moiety. LPI is comprised of a single polypeptide with an approximate molecular mass of 96 kDa. LPII was composed of two similar native components, LPIIa and LPIIb, both having polypeptides of 80 and 177 kDa. Both under natural conditions and after endocrine manipulations, LPI was present in males and in females, regardless of the female reproductive stage. LPII was present only in secondary-vitellogenic females, but not during the winter reproductive arrest period. LPII was also absent from young females that had received androgenic gland implants. LPII also appeared in the hemolymph of intersex individuals from which the androgenic gland had been removed. It is therefore suggested that LPII serves as a marker indicating the onset of secondary vitellogenesis in C. quad'iariicarintus females. PMID:11126772

  7. Lecithin/cholesterol acyltransferase induces estradiol esterification in high-density lipoprotein, increasing its antioxidant potential.

    PubMed

    Höckerstedt, Anna; Jauhiainen, Matti; Tikkanen, Matti J

    2004-10-01

    Endogenous estrogens protect against atherosclerosis, but the exact mechanisms remain unclear. One possibility is inhibition of lipoprotein oxidation. To act as antioxidants, estrogens reportedly need to be converted to lipophilic estrogen fatty acyl esters in a reaction catalyzed by lecithin/cholesterol acyltransferase (LCAT). To demonstrate directly that estradiol (E2) esters formed by LCAT and incorporated in high-density lipoprotein (HDL) increase its antioxidant potential, we investigated the copper-induced oxidation of purified HDL after incubations of: 1) HDL alone; 2) HDL in the presence of exogenous E2; 3) HDL in the presence of exogenous LCAT; 4) HDL in the presence of both E2 and LCAT; and 5) HDL in the presence of E2, LCAT, and the LCAT inhibitor DTNB. We used this in vitro model system with supraphysiological concentrations of E2 and purified LCAT to produce E2 ester-containing HDL particles for studies of oxidation resistance. The lag time of HDL oxidation significantly increased with increasing contents of HDL-associated E2 esters. In conclusion, our results clearly demonstrated the role of LCAT in E2 esterification and its involvement in antioxidant protection of HDL. Elucidation of the possible in vivo role of HDL-associated estrogen esters requires further critical studies including experiments with physiological hormone concentrations. PMID:15472210

  8. High density lipoproteins: Measurement techniques and potential biomarkers of cardiovascular risk

    PubMed Central

    Hafiane, Anouar; Genest, Jacques

    2015-01-01

    Plasma high density lipoprotein cholesterol (HDL) comprises a heterogeneous family of lipoprotein species, differing in surface charge, size and lipid and protein compositions. While HDL cholesterol (C) mass is a strong, graded and coherent biomarker of cardiovascular risk, genetic and clinical trial data suggest that the simple measurement of HDL-C may not be causal in preventing atherosclerosis nor reflect HDL functionality. Indeed, the measurement of HDL-C may be a biomarker of cardiovascular health. To assess the issue of HDL function as a potential therapeutic target, robust and simple analytical methods are required. The complex pleiotropic effects of HDL make the development of a single measurement challenging. Development of laboratory assays that accurately HDL function must be developed validated and brought to high-throughput for clinical purposes. This review discusses the limitations of current laboratory technologies for methods that separate and quantify HDL and potential application to predict CVD, with an emphasis on emergent approaches as potential biomarkers in clinical practice. PMID:26674734

  9. Optical Characterization of Europium Tetracycline Complex in the presence of Low Density Lipoprotein and its Applications

    NASA Astrophysics Data System (ADS)

    de Oliveira Silva, Flávia Rodrigues; Monteiro, Andrea Moreira; Neto, Antônio M. Figueiredo; Gidlund, Magnus A.; Gomes, Laércio; Junior, Nilson Dias Vieira; Courrol, Lilia Coronato

    2008-04-01

    Development of native Low Density Lipoprotein (LDL) biosensors is of great importance in clinical analysis because the LDL concentration, which is the main carrier of cholesterol, in the plasma, is a fundamental parameter for the prevention and diagnosis of a number of clinical disorders such as heart disease, hypertension and atherosclerosis. The optical properties of the Europium-Tetracycline Complex (EuTc) were investigated for the solutions containing LDL in their compositions. In this paper we show an enhancement in the europium luminescence of EuTc complex in the presence of LDL. The time-resolved fluorescence spectroscopy experimental results of the pure EuTc sample and samples with LDL (EuTc:LDL) reveal an increase in the europium emission lifetime in the lipoprotein-doped samples with respect to the pure EuTc sample. A calibration curve, reasonably well described by a linear function between 0 and 3 mg/mL of LDL, was obtained. The obtained limit of detection was 0.23 mg/mL. Sixteen blood plasma samples all of them contend approximately 90 mg/dL of LDL were studied and the LDL concentrations were calculated with our method. The average LDL concentration obtained was 94 mg/dL. The results show that the EuTc complex can be used as a sensor to determine LDL with fast response, compact design, and reproducible results.

  10. Gold Nanocrystal Labeling Allows Low Density Lipoprotein Imaging From The Subcellular To Macroscopic Level

    PubMed Central

    Allijn, Iris E.; Leong, Wei; Tang, Jun; Gianella, Anita; Mieszawska, Aneta J.; Fay, Francois; Ma, Ge; Russell, Stewart; Callo, Catherine B.; Gordon, Ronald E.; Korkmaz, Emine; Post, Jan Andries; Zhao, Yiming; Gerritsen, Hans C.; Thran, Axel; Proksa, Roland; Daerr, Heiner; Storm, Gert; Fuster, Valentin; Fisher, Edward A.; Fayad, Zahi A.; Mulder, Willem J.M.

    2013-01-01

    Low density lipoprotein (LDL) plays a critical role in cholesterol transport and is closely linked to the progression of several diseases. This motivates the development of methods to study LDL behavior from the microscopic to whole-body level. We have developed an approach to efficiently load LDL with a range of diagnostically active nanocrystals or hydrophobic agents. We performed focused experiments on LDL labeled with gold nanocrystals (Au-LDL). The labeling procedure had minimal effect on LDL size, morphology or composition. Biological function was found to be maintained from both in vitro and in vivo experiments. Tumor bearing mice were injected intravenously with LDL, DiR-LDL, Au-LDL or a gold-loaded nanoemulsion. LDL accumulation in the tumors was detected with whole body imaging methods, such as computed tomography (CT), spectral CT and fluorescence imaging. Cellular localization was studied with transmission electron microscopy (TEM) and fluorescence techniques. In conclusion, this LDL labeling procedure should permit the study of lipoprotein biointeractions in unprecedented detail. PMID:24127782

  11. Effect of chronic renal failure on high-density lipoprotein kinetics

    SciTech Connect

    Fuh, M.M.; Lee, C.M.; Jeng, C.Y.; Shen, D.C.; Shieh, S.M.; Reaven, G.M.; Chen, Y.D. )

    1990-05-01

    Plasma lipid and lipoprotein concentration and high density lipoprotein (HDL) kinetics were determined in control subjects and patients with chronic renal failure (CRF). Results demonstrated that plasma triglyceride (TG) concentration was significantly higher (P less than 0.001) in patients with CRF, associated with a significant increase in plasma VLDL-cholesterol (P less than 0.002) and a significant decrease (P less than 0.05) in plasma HDL-cholesterol concentration. The rate of removal of {sup 125}I-apoAI/HDL from plasma was slower (P less than 0.001) in the patients with CRF, resulting in an increase in the residence time of {sup 125}I-apoAI/HDL (P less than 0.001) and a decrease in the fractional catabolic rate (P less than 0.001). Since plasma apoAI concentration was lower in patients with CRF, total apoAI/HDL synthetic rate was also significantly (P less than 0.05) decreased. These data provide support for the view that low plasma HDL-cholesterol concentrations in patients with CRF are related to decreases in the synthetic rate of apoAI/HDL.

  12. Role of dietary supplements in lowering low-density lipoprotein cholesterol: a review.

    PubMed

    Nijjar, Prabhjot S; Burke, Frances M; Bloesch, Annette; Rader, Daniel J

    2010-01-01

    Coronary heart disease (CHD) remains a major source of morbidity and mortality. As the epidemic of obesity, diabetes, and hypertension continues to grow among young adults, the population at risk for atherosclerotic CHD is ever increasing. More than a century of laboratory and human findings link cholesterol levels with a propensity to develop atherosclerosis. Low-density lipoprotein (LDL) is the major atherogenic lipoprotein, and numerous clinical trials have shown the efficacy of lowering LDL-cholesterol (LDL-C) for reducing CHD risk. New trial data have resulted in LDL-C goals being lowered over time and expansion of the population of patients that are candidates for LDL-lowering therapy to decrease their lifetime risk of CHD. Although statins are relatively safe and well tolerated, there are still significant numbers of patients who cannot tolerate them and many others who only require mild LDL-C reduction and prefer nonprescription alternatives to statin therapy. A number of dietary supplements and functional foods have been suggested to reduce LDL-C levels, but only a few have withstood the rigors of randomized controlled trials. Here we review the evidence in support of dietary supplements and their LDL-C-lowering effects. We also review supplements that, after initial excitement about their purported effect, were not found to lower LDL-C significantly. PMID:21122657

  13. Metabolic imaging with gallium-68- and indium-111-labeled low-density lipoprotein

    SciTech Connect

    Moerlein, S.M.; Daugherty, A.; Sobel, B.E.; Welch, M.J. )

    1991-02-01

    Low-density lipoprotein (LDL) labeled with either gallium-68 ({sup 68}Ga) or indium-111 ({sup 111}In) was evaluated as a potential PET or SPECT radiopharmaceutical for determination of hepatic lipoprotein metabolism in rabbits. Gallium-68 or {sup 111}In was linked to LDL via diethylenetriaminepentaacetic acid (DTPA) with a 25-70% radiochemical yield. Studies in vivo that compared {sup 68}Ga- or {sup 111}In-DTPA-LDL with dilactitol-({sup 125}I)-tyramine LDL and 131I-LDL showed that both {sup 68}Ga- and {sup 111}In-labeled LDL behaved as residualizing radiotracers. Localization of radioactivity within the liver of normal rabbits was visualized clearly with ({sup 68}Ga)DTPA-LDL by PET and with ({sup 111}In)DTPA-LDL by gamma scintigraphy. Significant differences were observed in hepatic uptake of normal compared with hypercholesterolemic rabbits in which low-capacity LDL receptor-mediated catabolism was saturated. Gallium-68 and {sup 111}In-DTPA-LDL are attractive radiopharmaceuticals for noninvasive delineation of tissue LDL metabolism under normal and pathophysiologic conditions.

  14. Effects of estrogen on very low-density lipoprotein triglyceride metabolism in fed and fasted chicks

    SciTech Connect

    Park, J.R.

    1988-01-01

    A single injection of estrogen into growing chicks resulted in a marked elevation in plasma triglyceride (TG) followed by phospholipid (PL) and cholesterol (CH) in both fed and fasted chicks. Estrogen caused a development of massive fatty liver in fed chicks. Hepatic malic enzyme and glucose-6-phosphate dehydrogenase activities also increased significantly in fed chicks and, to a small extent, in fasted chicks. Very low density lipoproteins (VLDL) were barely detectable in the fasted control plasma. However, the VLDL concentration increased markedly upon estrogen injection, becoming the most prevalent lipoprotein in the plasma. The administration of estrogen resulted in an increase in oleic acid and a decrease in linoleic acid content except in the cholesteryl ester of VLDL and LDL. VLDL of estrogenized birds had {beta}-mobility on agarose gel electrophoresis, and they eluted in two peaks on agarose gel filtration chromatography. Both peaks on gel filtration exhibited the same {beta}-mobility on agarose gel electrophoresis. Nevertheless, the apoprotein composition of these two peaks were substantially different from each other; apo B was not present in the first peak VLDL. VLDL-TG kinetic studies conducted in vivo, using {sup 14}C-TG-VLDL prepared endogenously from control and estrogenized chicks revealed that VLDL-TG produced from the former had a higher fractional catabolic rate (FCR) than VLDL-TG from the latter.

  15. Protective effect of oleanolic acid on oxidized-low density lipoprotein induced endothelial cell apoptosis.

    PubMed

    Cao, Jianhua; Li, Guanghui; Wang, Meizhi; Li, Hui; Han, Zhiwu

    2015-10-01

    Oleanolic acid (3β-hydroxyolean-12-en-28-oic acid, OA) is a naturally-occurring triterpenoid with various promising pharmacological properties. The present study was conducted to determine the protective effects of OA against oxidized low-density lipoprotein (ox-LDL) induced endothelial cell apoptosis and the possible underlying mechanisms. Our results showed that ox-LDL significantly decreased cell viability and induced apoptosis in human umbilical vein endothelial cells (HUVECs). OA in the co-treatment showed a protective effect against ox-LDL induced loss in cell viability and an increase in apoptosis, which was associated with the modulating effect of OA on ox-LDL induced hypoxia-inducible factor 1α(HIF-1α) expression. Moreover, our results showed that the modulating effect of OA against ox-LDL induced HIF-1α expression was obtained via inhibition of lipoprotein receptor 1 (LOX-1)/reactive oxygen species (ROS) signaling. Collectively, we suggested that the protective effect of OA against ox-LDL induced HUVEC apoptosis might, at least in part, be obtained via inhibition of the LOX-1/ROS/HIF-1α signaling pathway. PMID:26559024

  16. Variability in alpha-tocopherol antioxidant activity in the core and surface layers of low- and high-density lipoproteins.

    PubMed

    Cazzola, R; Cervato, G; Cestaro, B

    1999-01-01

    The effect of alpha-tocopherol enrichment of low- and high-density lipoproteins on Cu(2+)-catalyzed lipid peroxidation in the hydrophobic core and in the hydrophilic envelope of lipoproteins was investigated by using two pyrene derivatives, namely, cholesteryl pyrenyl hexanoate (P6Chol) and pyrene dodecanoyl sulfatide (P12CS). The progressive decrease in fluorescence of P6Chol was used to monitor lipid peroxidation in the core of LDL and HDL, whereas that of P12CS was used to follow lipid peroxidation in the envelope of both lipoproteins. alpha-Tocopherol enrichment of LDL and HDL was obtained by incubating blood plasma at 37 degrees C with different concentrations of the vitamin (25-500 microM) before lipoprotein separation. The incorporation of alpha-tocopherol in LDL and HDL presents a progressive, time-dependent increase up to 200 microM alpha-tocopherol, then a plateau up to 500 microM. In the envelopes, the added tocopherol causes a great decrease in the rate of peroxidation and a dramatic increase in the latency phase in both lipoproteins. In the cores the lengthening of latency phase resulting from alpha-tocopherol enrichment was by far greater in LDL than in HDL, and the decrease in the rate of peroxidation in both lipoproteins was less than in the envelopes. PMID:10360240

  17. Z-Scan Analysis: a New Method to Determine the Oxidative State of Low-Density Lipoprotein and Its Association with Multiple Cardiometabolic Biomarkers

    NASA Astrophysics Data System (ADS)

    de Freitas, Maria Camila Pruper; Figueiredo Neto, Antonio Martins; Giampaoli, Viviane; da Conceição Quintaneiro Aubin, Elisete; de Araújo Lima Barbosa, Milena Maria; Damasceno, Nágila Raquel Teixeira

    2016-01-01

    The great atherogenic potential of oxidized low-density lipoprotein has been widely described in the literature. The objective of this study was to investigate whether the state of oxidized low-density lipoprotein in human plasma measured by the Z-scan technique has an association with different cardiometabolic biomarkers. Total cholesterol, high-density lipoprotein cholesterol, triacylglycerols, apolipoprotein A-I and apolipoprotein B, paraoxonase-1, and glucose were analyzed using standard commercial kits, and low-density lipoprotein cholesterol was estimated using the Friedewald equation. A sandwich enzyme-linked immunosorbent assay was used to detect electronegative low-density lipoprotein. Low-density lipoprotein and high-density lipoprotein sizes were determined by Lipoprint® system. The Z-scan technique was used to measure the non-linear optical response of low-density lipoprotein solution. Principal component analysis and correlations were used respectively to resize the data from the sample and test association between the θ parameter, measured with the Z-scan technique, and the principal component. A total of 63 individuals, from both sexes, with mean age 52 years (±11), being overweight and having high levels of total cholesterol and low levels of high-density lipoprotein cholesterol, were enrolled in this study. A positive correlation between the θ parameter and more anti-atherogenic pattern for cardiometabolic biomarkers together with a negative correlation for an atherogenic pattern was found. Regarding the parameters related with an atherogenic low-density lipoprotein profile, the θ parameter was negatively correlated with a more atherogenic pattern. By using Z-scan measurements, we were able to find an association between oxidized low-density lipoprotein state and multiple cardiometabolic biomarkers in samples from individuals with different cardiovascular risk factors.

  18. Z-Scan Analysis: a New Method to Determine the Oxidative State of Low-Density Lipoprotein and Its Association with Multiple Cardiometabolic Biomarkers

    NASA Astrophysics Data System (ADS)

    de Freitas, Maria Camila Pruper; Figueiredo Neto, Antonio Martins; Giampaoli, Viviane; da Conceição Quintaneiro Aubin, Elisete; de Araújo Lima Barbosa, Milena Maria; Damasceno, Nágila Raquel Teixeira

    2016-04-01

    The great atherogenic potential of oxidized low-density lipoprotein has been widely described in the literature. The objective of this study was to investigate whether the state of oxidized low-density lipoprotein in human plasma measured by the Z-scan technique has an association with different cardiometabolic biomarkers. Total cholesterol, high-density lipoprotein cholesterol, triacylglycerols, apolipoprotein A-I and apolipoprotein B, paraoxonase-1, and glucose were analyzed using standard commercial kits, and low-density lipoprotein cholesterol was estimated using the Friedewald equation. A sandwich enzyme-linked immunosorbent assay was used to detect electronegative low-density lipoprotein. Low-density lipoprotein and high-density lipoprotein sizes were determined by Lipoprint® system. The Z-scan technique was used to measure the non-linear optical response of low-density lipoprotein solution. Principal component analysis and correlations were used respectively to resize the data from the sample and test association between the θ parameter, measured with the Z-scan technique, and the principal component. A total of 63 individuals, from both sexes, with mean age 52 years (±11), being overweight and having high levels of total cholesterol and low levels of high-density lipoprotein cholesterol, were enrolled in this study. A positive correlation between the θ parameter and more anti-atherogenic pattern for cardiometabolic biomarkers together with a negative correlation for an atherogenic pattern was found. Regarding the parameters related with an atherogenic low-density lipoprotein profile, the θ parameter was negatively correlated with a more atherogenic pattern. By using Z-scan measurements, we were able to find an association between oxidized low-density lipoprotein state and multiple cardiometabolic biomarkers in samples from individuals with different cardiovascular risk factors.

  19. Onset of lipoprotein-supported steroidogenesis in differentiating granulosa cells of rats: cellular events involved in mediating FSH-enhanced uptake of low-density lipoproteins

    SciTech Connect

    Foster, J.D.

    1987-01-01

    Luteal cells use lipoproteins as the main source of cholesterol in steroidogenesis. However, little is known about the mechanisms underlying hormonal control of lipoprotein uptake. Thus, the authors tested the hypothesis that FSH and androgens regulate low density lipoprotein (LDL)-supported steroidogenesis in maturing granulosa cells by affecting receptor-mediated endocytosis of LDL at a cellular level. For this, immature ovarian granulosa cells were cultured with or without hormones, compactin (de novo synthesis inhibitor), or unlabeled or labeled (/sup 125/I or gold particles) LDL. Nonhormone-treated cultures produced little progestin; FSH and FSH/androstenedione stimulated steroid secretion. Progestin production by hormone-, but not nonhormone-, treated cultures was decreased by compactin, suggesting that de novo synthesis provided sterol for steroidogenesis. EM quantitation of cells exposed to gold-LDL at 37/sup 0/C revealed that, compared to nonhormone-treated cells, FSH-treated cells (1) bound and internalized more gold-LDL, (2) had a smaller percentage of gold-LDL at their surfaces, (3) displayed a faster apparent rate of LDL internalization and delivery to lysosomes, and (4) contained more gold-labeled lysosomes. Data from biochemical studies in which /sup 125/I-LDL was used supported the morphological findings. In conclusion, this study demonstrates that FSH has important effects at the cellular level on LDL uptake, which seem to underlie the striking increase in progestin production accompanying granulosa cell differentiation.

  20. Purification and properties of a very high density lipoprotein from the hemolymph of the honeybee Apis mellifera.

    PubMed

    Shipman, B A; Ryan, R O; Schmidt, J O; Law, J H

    1987-04-01

    A larval-specific very high density lipoprotein (VHDL) has been isolated from the hemolymph of the honeybee Apis mellifera. VHDL was isolated by a combination of density gradient ultracentrifugation and gel filtration. The purified protein is a dimer of Mr 160,000 apoproteins as shown by chemical cross-linking with dimethyl suberimidate. N-Terminal sequence analysis indicates that the two polypeptide chains are identical. The holoprotein contains 10% lipid by weight and 2.6% covalently bound carbohydrate. A native Mr 330,000 species was obtained by gel permeation chromatography. Antiserum directed against VHDL was used to show that VHDL is distinct from other hemolymph proteins and appears to constitute a novel lipoprotein of unknown function. However, the lipoprotein is present in high amounts in hemolymph only at the end of larval life, suggesting a potential role in lipid transport and/or storage protein metabolism during metamorphosis. PMID:3109474

  1. High-Density Lipoprotein - A Hero, a Mirage, or a Witness?

    PubMed

    Sviridov, Dmitri

    2014-01-01

    Negative relationship between plasma high-density lipoprotein (HDL) levels and risk of cardiovascular disease (CVD) is a firmly established medical fact, but attempts to reproduce protective properties of HDL by pharmacologically elevating HDL levels were mostly unsuccessful. This conundrum presents a fundamental question: were the approaches used to raise HDL flawed or the protective effects of HDL are an epiphenomenon? Recent attempts to elevate plasma HDL were universally based on reducing HDL catabolism by blocking reverse cholesterol transport (RCT). Here, we argue that this mode of HDL elevation may be mechanistically different to natural mechanisms and thus be counterproductive. We further argue that independently of whether HDL is a driving force or a surrogate measure of the rate of RCT, approaches aimed at increasing HDL supply, rather than reducing its catabolism, would be most beneficial for speeding up RCT and improving protection against CVD. PMID:26664860

  2. Treating low high-density lipoprotein cholesterol: what is the evidence?

    PubMed Central

    Hage, Mirella P.

    2014-01-01

    Epidemiological studies have shown an inverse association between high-density lipoprotein cholesterol (HDL-C) and cardiovascular disease (CVD) risk. However, genetic and interventional studies have failed to consistently support this relationship. There is an increasing body of evidence that the function of HDL, including its antiatherogenic properties and its reverse cholesterol transport activity, has a greater impact on CVD risk compared with levels of HDL alone. Targeting HDL has become a growing interest. Nevertheless, raising HDL pharmacologically has failed to show a considerable, if any, impact on cardiovascular outcome. Efforts should focus on improving HDL quality in addition to raising HDL levels when developing new therapies. Ongoing and future research will help determine the most safe and effective approach to improve cardiovascular outcome and establish the safety, efficacy and impact on atherosclerosis of the emerging HDL-raising therapies. PMID:24696776

  3. Anticipatory role of high density lipoprotein and endothelial dysfunction: an overview.

    PubMed

    Eren, Esin; Yılmaz, Necat; Aydin, Ozgur; Ellidağ, Hamit Y

    2014-01-01

    High Density Lipoprotein (HDL) has been witnessed to possess a range of different functions that contribute to its atheroprotective effects. These functions are: the promotion of macrophage cholesterol efflux, reverse cholesterol transport, anti-inflammatory, anti-thrombotic, anti-apoptotic, pro-fibrinolytic and anti-oxidative functions. Paraoxonase 1 (PON1) is an HDL associated enzyme esterase/homocysteinethiolactonase that contributes to the anti-oxidant and anti-atherosclerotic capabilities of HDL. PON1 is directly involved in the etiopathogenesis of atherosclerosis through the modulation of nitric oxide (NO) bioavailability. The aim of this review is to summarize the role of HDL on endothelial homeostasis, and also to describe the recently characterized molecular pathways involved. PMID:25598849

  4. Hypercholesterolemia, low density lipoprotein receptor and proprotein convertase subtilisin/kexin-type 9

    PubMed Central

    Gu, Hong-mei; Zhang, Da-wei

    2015-01-01

    Abstract Atherosclerotic cardiovascular disease is the main cause of mortality and morbidity in the world. Plasma levels of low density lipoprotein cholesterol (LDL-C) are positively correlated with the risk of atherosclerosis. High plasma LDL concentrations in patients with hypercholesterolemia lead to build-up of LDL in the inner walls of the arteries, which becomes oxidized and promotes the formation of foam cells, consequently initiating atherosclerosis. Plasma LDL is mainly cleared through the LDL receptor (LDLR) pathway. Mutations in the LDLR cause familiar hypercholesterolemia and increase the risk of premature coronary heart disease. The expression of LDLR is regulated at the transcriptional level via the sterol regulatory element binding protein 2 (SREBP-2) and at the posttranslational levels mainly through proprotein convertase subtilisin/kexin-type 9 (PCSK9) and inducible degrader of the LDLR (IDOL). In this review, we summarize the latest advances in the studies of PCSK9. PMID:26445568

  5. 5-Lipoxygenase is not essential in macrophage-mediated oxidation of low-density lipoprotein.

    PubMed Central

    Jessup, W; Darley-Usmar, V; O'Leary, V; Bedwell, S

    1991-01-01

    The concentration-dependent effects of a series of lipoxygenase inhibitors and antioxidants on the macrophage-mediated oxidative modification of low-density lipoprotein (LDL) were measured. Their influence on macrophage 5-lipoxygenase pathway activity was also studied over the same concentration range. No correlation between inhibition of 5-lipoxygenase and of macrophage-mediated oxidation of LDL was observed. The capacity of the compounds to prevent cell-mediated modification of LDL could be explained in terms of their activity as either aqueous- or lipid-peroxyl radical scavengers. Two potent 5-lipoxygenase inhibitors (MK 886 and Revlon 5901), which had no radical-scavenging properties, were unable to block LDL modification. It is concluded that 5-lipoxygenase is not essential for LDL oxidation by macrophages. PMID:1883327

  6. Low Density Lipoprotein Receptor Related Proteins as Regulators of Neural Stem and Progenitor Cell Function

    PubMed Central

    Landowski, Lila M.; Young, Kaylene M.

    2016-01-01

    The central nervous system (CNS) is a highly organised structure. Many signalling systems work in concert to ensure that neural stem cells are appropriately directed to generate progenitor cells, which in turn mature into functional cell types including projection neurons, interneurons, astrocytes, and oligodendrocytes. Herein we explore the role of the low density lipoprotein (LDL) receptor family, in particular family members LRP1 and LRP2, in regulating the behaviour of neural stem and progenitor cells during development and adulthood. The ability of LRP1 and LRP2 to bind a diverse and extensive range of ligands, regulate ligand endocytosis, recruit nonreceptor tyrosine kinases for direct signal transduction and signal in conjunction with other receptors, enables them to modulate many crucial neural cell functions. PMID:26949399

  7. Pharmacogenetics of paraoxonase activity: elucidating the role of high-density lipoprotein in disease

    PubMed Central

    Kim, Daniel Seung; Marsillach, Judit; Furlong, Clement E; Jarvik, Gail P

    2014-01-01

    PON1 is a key component of high-density lipoproteins (HDLs) and is at least partially responsible for HDL's antioxidant/atheroprotective properties. PON1 is also associated with numerous human diseases, including cardiovascular disease, Parkinson's disease and cancer. In addition, PON1 metabolizes a broad variety of substrates, including toxic organophosphorous compounds, statin adducts, glucocorticoids, the likely atherogenic l-homocysteine thiolactone and the quorum-sensing factor of Pseudomonas aeruginosa. Numerous cardiovascular and antidiabetic pharmacologic agents, dietary macronutrients, lifestyle factors and antioxidant supplements affect PON1 expression and enzyme activity levels. Owing to the importance of PON1 to HDL function and its individual association with diverse human diseases, pharmacogenomic interactions between PON1 and the various factors that alter its expression and activity may represent an important therapeutic target for future investigation. PMID:24024900

  8. Roles of antibody against oxygenized low density lipoprotein in atherosclerosis: recent advances

    PubMed Central

    Zhang, Jing; Wang, Daxin; He, Shenghu

    2015-01-01

    Atherosclerosis is a chronic immune inflammatory disease. Atherosclerosis and relevant disease are threatening human life and health. Oxygenized low density lipoprotein (oxLDL) is a molecular basis in the pathogenesis of atherosclerosis and able to induce inflammation, stimulate immune system and interfere with lipid metabolism in the occurrence and development of atherosclerosis. Antibody against oxLDL has been an important molecule in the immune related pathogenesis of atherosclerosis. In available studies on atherosclerosis, antibody against oxLDL has been a focus, but how oxLDL acts to affect the atherosclerosis and relevant diseases, whether oxLDL is protective or detrimental, and whether oxLDL acts in different ways at different stages of atherosclerosis are still unclear. This paper focuses on the role of antibody against oxLDL in the atherosclerosis and relevant diseases, and summarizes the advances in this field, aiming to provide new clue and new methods for the therapy of atherosclerosis. PMID:26550105

  9. High systemic levels of low-density lipoprotein cholesterol: fuel to the flames in inflammatory osteoarthritis?

    PubMed

    de Munter, Wouter; van der Kraan, Peter M; van den Berg, Wim B; van Lent, Peter L E M

    2016-01-01

    There is increasing evidence that low-density lipoprotein (LDL) cholesterol plays a role in the pathology of OA. Specifically, oxidized LDL (oxLDL), which has been shown to play an essential role during development of atherosclerosis, could be involved in processes such as synovial inflammation, cartilage destruction and bone deformations. OxLDL can activate synovial cells such as macrophages, endothelial cells and synovial fibroblasts, resulting in release of growth factors, MMP and pro-inflammatory cytokines. In this review article, we discuss the role of LDL and oxLDL in OA joint pathology and share our viewpoint of possible mechanisms by which these proteins could influence the development and progression of OA. The proposed theory could provide insight into the aetiopathology of OA and give rise to new potential treatments. PMID:26231344

  10. Structural basis of human high-density lipoprotein formation and assembly at sub nanometer resolution.

    PubMed

    Sivashanmugam, Arun; Yang, Yunhuang; Murray, Victoria; McCullough, Christopher; Chen, Bin; Ren, Xuefeng; Li, Qianqian; Wang, Jianjun

    2008-01-01

    Human high-density lipoproteins (HDL) are protein/lipid particles of nanometer sizes. These nano particles are critical for transportation of the "bad cholesterol" from peripheral tissues back to the liver for clearance. An inverse correlation has been observed between the plasma HDL concentration and atherosclerosis. Furthermore, the HDL particle has also been utilized as a vehicle for drug delivery and for intracellular cell biology studies of membrane proteins. The structural basis of HDL formation and assembly, however, is poorly understood. Using high-resolution structural approaches, the formation and assembly of the HDL particle is being examined at atomic resolution, which is reviewed in this chapter. We will mainly focus on our own NMR studies of different apoAI conformations with a brief summary of previously published work by other laboratories. PMID:19195557

  11. Effects of soluble dietary fiber on low-density lipoprotein cholesterol and coronary heart disease risk.

    PubMed

    Bazzano, Lydia A

    2008-12-01

    Strong epidemiologic and experimental data suggest that increasing dietary fiber may help to lower low-density lipoprotein cholesterol (LDL-C) and decrease the risk of coronary heart disease. Recent studies have highlighted the role of dietary fiber, particularly water-soluble varieties, in decreasing the risk of cardiovascular disease. Several types of soluble fiber, including psyllium, beta-glucan, pectin, and guar gum, have been shown to decrease LDL-C in well-controlled intervention studies, whereas the soluble fiber content of legumes and vegetables has also been shown to decrease LDL-C. Current investigations continue to explore this area in depth and examine potential synergies between dietary fiber and other phytochemicals that may lower cholesterol. These studies, along with recent analyses of ongoing prospective cohort studies, have provided new insights into the probable protective role of dietary fiber in the development of coronary heart disease and other cardiovascular diseases. PMID:18937894

  12. Inhibitory effect of coumarins from Weigela subsessilis on low density lipoprotein oxidation.

    PubMed

    Thuong, Phuong Thien; Na, MinKyun; Su, Nguyen Duy; Seong, Rack Seon; Lee, Young Mi; Sok, Dai Eun; Bae, KiHwan

    2005-06-01

    Oxidation of low density lipoprotein (LDL) is thought to be a major factor in the pathophysiology of atherosclerosis. In the present study, we found that coumarins isolated from Weigela subsessilis (Caprifoliaceae) inhibited LDL oxidation mediated by either catalytic copper ions (Cu2+) or free radicals generated with the azo compound 2,2'-azobis-(2-amidinopropane)dihydrochloride (AAPH). Of the coumarins tested, scopoletin (1) and cleomiscosin A (2) increased the lag time of conjugated diene formation and inhibited the generation of thiobarbituric acid reactive substances (TBARS) in a dose-dependent manner. In addition, it was found that compounds 1 and 2 had the capacity to protect the fragmentation of apolipoprotein B-100 (apoB-100). These results suggest that W. subsessilis and its active coumarins, 1 and 2, may have a role to play in preventing the LDL oxidation involved in atherogenesis. PMID:15930753

  13. Serum cholesterol binding reserve and high density lipoprotein cholesterol in patients on maintenance hemodialysis.

    PubMed

    Perez, G O; Hsia, S L; Christakis, G; Burr, J

    1980-09-01

    Serum cholesterol binding reserve (SCBR, the capacity of the serum to solubilize additional cholesterol), high density lipoprotein cholesterol (HDL . Ch) and serum levels of cholesterol and triglycerides were measured in 53 chronically uremic patients (40 men and 13 women) undergoing maintenance hemodialysis. The values were compared with those of controls (149 men and 28 women) matched for serum lipid levels. Hypertriglyceridemia and decreased HDL . Ch were observed among the patients, confirming previous reports. SCBR values of the patients were not significantly different from those of controls except in a small subgroup of uremic diabeties, whose SCBR values were markedly decreased. There was a positive correlation between SCBR and the duration for which the patients had been maintained by hemodialysis. The results suggest that patients with higher SCBR values have a better prospect for surviving long duration of hemodialysis. PMID:7429416

  14. High density lipoprotein cholesterol: an evolving target of therapy in the management of cardiovascular disease

    PubMed Central

    Kapur, Navin K; Ashen, Dominique; Blumenthal, Roger S

    2008-01-01

    Since the pioneering work of John Gofman in the 1950s, our understanding of high density lipoprotein cholesterol (HDL-C) and its relationship to coronary heart disease (CHD) has grown substantially. Numerous clinical trials since the Framingham Study in 1977 have demonstrated an inverse relationship between HDL-C and one’s risk of developing CHD. Over the past two decades, preclinical research has gained further insight into the nature of HDL-C metabolism, specifically regarding the ability of HDL-C to promote reverse cholesterol transport (RCT). Recent attempts to harness HDL’s ability to enhance RCT have revealed the complexity of HDL-C metabolism. This review provides a detailed update on HDL-C as an evolving therapeutic target in the management of cardiovascular disease. PMID:18629371

  15. Pharmacogenetics of paraoxonase activity: elucidating the role of high-density lipoprotein in disease.

    PubMed

    Kim, Daniel Seung; Marsillach, Judit; Furlong, Clement E; Jarvik, Gail P

    2013-09-01

    PON1 is a key component of high-density lipoproteins (HDLs) and is at least partially responsible for HDL's antioxidant/atheroprotective properties. PON1 is also associated with numerous human diseases, including cardiovascular disease, Parkinson's disease and cancer. In addition, PON1 metabolizes a broad variety of substrates, including toxic organophosphorous compounds, statin adducts, glucocorticoids, the likely atherogenic L-homocysteine thiolactone and the quorum-sensing factor of Pseudomonas aeruginosa. Numerous cardiovascular and antidiabetic pharmacologic agents, dietary macronutrients, lifestyle factors and antioxidant supplements affect PON1 expression and enzyme activity levels. Owing to the importance of PON1 to HDL function and its individual association with diverse human diseases, pharmacogenomic interactions between PON1 and the various factors that alter its expression and activity may represent an important therapeutic target for future investigation. PMID:24024900

  16. Low-density lipoprotein cholesterol lowering therapies: what is on the horizon?

    PubMed

    Gadi, Ramprasad; Figueredo, Vincent M

    2015-01-01

    Elevated low-density lipoprotein cholesterol (LDL-C) levels are associated with an increased risk for cardiovascular disease (CVD). Statins have been the cornerstone of lipid therapy to lower LDL-C for the past two decades, but despite significant clinical efficacy in a majority of patients, a large residual risk remains for the development of initial or recurrent atherosclerotic CVD. In addition, owing to the side-effects, a significant percentage of patients cannot tolerate any statin dose or a high enough statin dose. Thus, novel therapeutic agents are currently being developed to lower LDL-C levels further. This review will highlight these novel therapeutic agents including antisense oligonucleotides focused on apolipoprotein B, proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, and microsomal triglyceride transfer protein inhibitors. For each therapeutic class, an overview of mechanism of action, pharmacokinetic data, and efficacy/safety evidence will be discussed. PMID:25379719

  17. Anticipatory Role of High Density Lipoprotein and Endothelial Dysfunction: An Overview

    PubMed Central

    Eren, Esin; Yılmaz, Necat; Aydin, Ozgur; Ellidağ, Hamit Y

    2014-01-01

    High Density Lipoprotein (HDL) has been witnessed to possess a range of different functions that contribute to its atheroprotective effects. These functions are: the promotion of macrophage cholesterol efflux, reverse cholesterol transport, anti-inflammatory, anti-thrombotic, anti-apoptotic, pro-fibrinolytic and anti-oxidative functions. Paraoxonase 1 (PON1) is an HDL associated enzyme esterase/homocysteinethiolactonase that contributes to the anti-oxidant and anti-atherosclerotic capabilities of HDL. PON1 is directly involved in the etiopathogenesis of atherosclerosis through the modulation of nitric oxide (NO) bioavailability. The aim of this review is to summarize the role of HDL on endothelial homeostasis, and also to describe the recently characterized molecular pathways involved. PMID:25598849

  18. High density lipoprotein and metabolic disease: Potential benefits of restoring its functional properties

    PubMed Central

    Klancic, Teja; Woodward, Lavinia; Hofmann, Susanna M.; Fisher, Edward A.

    2016-01-01

    Background High density lipoproteins (HDLs) are thought to be atheroprotective and to reduce the risk of cardiovascular disease (CVD). Besides their antioxidant, antithrombotic, anti-inflammatory, anti-apoptotic properties in the vasculature, HDLs also improve glucose metabolism in skeletal muscle. Scope of the review Herein, we review the functional role of HDLs to improve metabolic disorders, especially those involving insulin resistance and to induce regression of CVD with a particular focus on current pharmacological treatment options as well as lifestyle interventions, particularly exercise. Major conclusions Functional properties of HDLs continue to be considered important mediators to reverse metabolic dysfunction and to regress atherosclerotic cardiovascular disease. Lifestyle changes are often recommended to reduce the risk of CVD, with exercise being one of the most important of these. Understanding how exercise improves HDL function will likely lead to new approaches to battle the expanding burden of obesity and the metabolic syndrome. PMID:27110484

  19. The laying hen expresses two different low density lipoprotein receptor-related proteins.

    PubMed

    Stifani, S; Barber, D L; Aebersold, R; Steyrer, E; Shen, X; Nimpf, J; Schneider, W J

    1991-10-01

    We have identified, by a combination of ligand, 45Ca2+, and immunoblotting, two large membrane proteins akin to the mammalian so-called low density lipoprotein (LDL) receptor-related protein (LRP) in chicken tissues. LRP has thus far been demonstrated only in mammalian species where it is thought to act as a receptor for proteinase-alpha 2-macroglobulin complexes and/or chylomicron remnants, lipoproteins not produced in birds. One of the chicken LRPs was demonstrated in liver, and has the same apparent Mr and hallmark biochemical properties as rat liver LRP. The other chicken LRP is smaller (approximately 380 kDa) and is expressed in ovarian follicles, but is undetectable in liver. Immunological analysis demonstrated a lack of cross-reactivity between the two LRPs, as well as between them and the previously identified chicken oocyte-specific 95-kDa receptor for the yolk precursors, very low density lipoprotein, and vitellogenin (Stifani, S., Barber, D. L., Nimpf, J., and Schneider, W. J. (1989) Proc. Natl. Acad. Sci. U.S.A. 87, 1955-1959). As shown by ligand blotting, both chicken LRPs have the ability to interact with vitellogenin, a property they share not only with rat LRP, but also with mammalian LDL receptors. To obtain independent confirmation of the ligand blotting results, the smaller (follicular) LRP was purified and high-affinity binding of vitellogenin to it was demonstrated by a solid-phase filtration binding assay. Amino acid sequences of tryptic fragments of the smaller LRP were obtained, and its homology with human LRP demonstrated through unambiguous alignment of three fragments. Both chicken LRPs, the chicken oocyte 95-kDa receptor, as well as rat LRP, could be shown by ligand blotting to interact specifically with chicken serum alpha 2-macroglobulin. In addition, human apolipoprotein E, a ligand implicated in receptor-mediated metabolism of chylomicron remnants, also binds to the smaller chicken LRP, further emphasizing the similarities between LDL receptors and related proteins from a variety of species. In analogy to the known dichotomy of chicken LDL receptors, which is characterized by the production of the 95-kDa oocyte-specific receptor on one hand and a 130-kDa LDL receptor that is exclusively expressed in somatic cells (Hayashi, K., Nimpf, J., and Schneider, W. J. (1989) J. Biol. Chem. 264, 3131-3139), it appears that the smaller and larger chicken LRPs also may be restricted to the oocyte and somatic cells, respectively. PMID:1918027

  20. High-density Lipoprotein Particle Concentration and Subclinical Atherosclerosis of the Carotid Arteries in Japanese Men

    PubMed Central

    Zaid, Maryam; Fujiyoshi, Akira; Miura, Katsuyuki; Abbott, Robert D.; Okamura, Tomonori; Takashima, Naoyuki; Torii, Sayuki; Saito, Yoshino; Hisamatsu, Takashi; Miyagawa, Naoko; Ohkubo, Takayoshi; Kadota, Aya; Sekikawa, Akira; Maegawa, Hiroshi; Nakamura, Yasuyuki; Mitsunami, Kenichi; Ueshima, Hirotsugu

    2015-01-01

    Objective The association of high-density lipoprotein particle (HDL-P) with atherosclerosis may be stronger than that of HDL-cholesterol (HDL-C) and independent of conventional cardiovascular risk factors. Whether associations persist in populations at low risk of coronary heart disease (CHD) remains unclear. This study examines the associations of HDL-P and HDL-C with carotid intima-media thickness (cIMT) and plaque counts among Japanese men, who characteristically have higher HDL-C levels and a lower CHD burden than those in men of Western populations. Methods We cross-sectionally examined a community-based sample of 870 Japanese men aged 40-79 years, free of known clinical cardiovascular disease (CVD) and not on lipid-lowering medication. Participants were randomly selected among Japanese living in Kusatsu City in Shiga, Japan. Results Both HDL-P and HDL-C were inversely and independently associated with cIMT in models adjusted for conventional CHD risk factors, including low-density lipoprotein cholesterol (LDL-C) and diabetes. HDL-P maintained an association with cIMT after further adjustment for HDL-C (P<0.01), whereas the association of HDL-C with cIMT was noticeably absent after inclusion of HDL-P in the model. In plaque counts of the carotid arteries, HDL-P was significantly associated with a reduction in plaque count, whereas HDL-C was not. Conclusion HDL-P, in comparison to HDL-C, is more strongly associated with measures of carotid atherosclerosis in a cross-sectional study of Japanese men. Findings demonstrate that, HDL-P is a strong correlate of subclinical atherosclerosis even in a population at low risk for CHD. PMID:25687270

  1. Chitin-glucan fiber effects on oxidized low-density lipoprotein: a randomized controlled trial

    PubMed Central

    Bays, H E; Evans, J L; Maki, K C; Evans, M; Maquet, V; Cooper, R; Anderson, J W

    2013-01-01

    Background/objectives: Elevated oxidized low-density lipoprotein (OxLDL) may promote inflammation, and is associated with increased risk of atherosclerotic coronary heart disease and worsening complications of diabetes mellitus. The primary objective of this study was to evaluate the efficacy of chitin-glucan (CG), alone and in combination with a potentially anti-inflammatory olive oil (OO) extract, for reducing OxLDL in subjects with borderline to high LDL cholesterol (LDL-C) levels. Subjects/methods: This 6-week, randomized, double-blind, placebo-controlled study of a novel, insoluble fiber derived from the Aspergillus niger mycelium, CG, evaluated 130 subjects free of diabetes mellitus with fasting LDL-C 3.37–4.92 mmol/l and glucose ⩽6.94 mmol/l. Participants were randomly assigned to receive CG (4.5 g/day; n=33), CG (1.5 g/day; n=32), CG (1.5 g/day) plus OO extract (135 mg/day; n=30), or matching placebo (n=35). Results: Administration of 4.5 g/day CG for 6 weeks significantly reduced OxLDL compared with placebo (P=0.035). At the end of study, CG was associated with lower LDL-C levels relative to placebo, although this difference was statistically significant only for the CG 1.5 g/day group (P=0.019). CG did not significantly affect high-density lipoprotein cholesterol, triglycerides, glucose, insulin or F2-isoprostane levels. Adverse events did not substantively differ between treatments and placebo. Conclusions: In this 6-week study, CG (4.5 g/day) reduced OxLDL, an effect that might affect the risk for atherosclerosis. PMID:22948945

  2. Flow-cytometric determination of high-density-lipoprotein binding sites on human leukocytes

    SciTech Connect

    Schmitz, G.; Wulf, G.; Bruening, T.A.; Assmann, G.

    1987-12-01

    In this method, leukocytes were isolated from 6 mL of EDTA-blood by density-gradient centrifugation and subsequently incubated with rhodamine isothiocyanate (RITC)-conjugated high-density lipoproteins (HDL). The receptor-bound conjugate particles were determined by fluorescent flow cytometry and compared with /sup 125/I-labeled HDL binding data for the same cells. Human granulocytes express the highest number of HDL binding sites (9.4 x 10(4)/cell), followed by monocytes (7.3 x 10(4)/cell) and lymphocytes (4.0 x 10(4)/cell). Compared with conventional analysis of binding of /sup 125/I-labeled HDL in tissue-culture dishes, the present determination revealed significantly lower values for nonspecific binding. In competition studies, the conjugate competes for the same binding sites as /sup 125/I-labeled HDL. With the use of tetranitromethane-treated HDL3, which fails to compete for the HDL receptor sites while nonspecific binding is not affected, we could clearly distinguish between 37 degrees C surface binding and specific 37 degrees C uptake of RITC-HDL3, confirming that the HDL receptor leads bound HDL particles into an intracellular pathway rather than acting as a docking type of receptor. Patients with familial dysbetalipoproteinemia showed a significantly higher number of HDL binding sites in the granulocyte population but normal in lymphocytes and monocytes, indicating increased uptake of cholesterol-containing lipoproteins. In patients with familial hypercholesterolemia, HDL binding was increased in all three cell types, indicating increased cholesterol uptake and increased cholesterol synthesis. The present method allows rapid determination of HDL binding sites in leukocytes from patients with various forms of hyper- and dyslipoproteinemias.

  3. Surrogate Lipid Markers for Small Dense Low-Density Lipoprotein Particles in Overweight Youth

    PubMed Central

    Burns, Stephen F.; Lee, So Jung; Arslanian, Silva A.

    2013-01-01

    Objectives To determine if the ratio of triglycerides to high-density lipoprotein cholesterol (TG/HDL) and non–HDL cholesterol concentration could identify youth with small dense low-density lipoprotein (LDL). Study design One hundred forty-one (75 black and 66 white) overweight adolescents (9 to <18 years) had a fasting measurement of plasma lipids and LDL particle concentrations and size. Receiver operating characteristic curves were used to indicate the ability of different TG/HDL ratios and non–HDL cholesterol concentrations to identify overweight youth with atherogenic LDL concentration and size. Results Youth with a TG/HDL ratio of ≥3 vs <3 had higher concentrations of small dense LDL (1279.5 ± 60.1 vs 841.8 ± 24.2 nmol/L, P < .001) and smaller LDL particle size (20.3 ± 0.1 vs 21.2 ± 0.1 nm, P < .001). In receiver operating characteristic analyses a TG/HDL cut-point of 3 best predicted LDL concentration in white youth, and 2.5 in black youth. Non-HDL cholesterol cut-point of 120 mg/dL and 145 mg/dL predicted LDL particle concentration in white and in black youth, respectively. TG/HDL ratio with body mass index or waist circumference explained 71% and 79% of the variance, respectively, in total small LDL. Conclusions TG/HDL ratio and non-HDL cholesterol can identify overweight youth with atherogenic LDL particles. These easily obtained clinical lipid markers, in combination with body mass index and waist circumference, could be cost effective, in observational or interventional studies, for screening and follow-up of youth at heightened risk for atherogenic LDL. PMID:22809659

  4. Overexpression of LOXIN Protects Endothelial Progenitor Cells From Apoptosis Induced by Oxidized Low Density Lipoprotein.

    PubMed

    Veas, Carlos; Jara, Casandra; Willis, Naomi D; Pérez-Contreras, Karen; Gutierrez, Nicolas; Toledo, Jorge; Fernandez, Paulina; Radojkovic, Claudia; Zuñiga, Felipe A; Escudero, Carlos; Aguayo, Claudio

    2016-04-01

    Human endothelial progenitor cells (hEPC) are adult stem cells located in the bone marrow and peripheral blood. Studies have indicated that hEPC play an important role in the recovery and repair of injured endothelium, however, their quantity and functional capacity is reduced in several diseases including hypercholesterolemia. Recently, it has been demonstrated that hEPC express lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) and its activation by oxidized low-density lipoprotein (ox-LDL) induces cellular dysfunction and apoptosis. This study aimed to investigate whether overexpression of LOXIN, a truncated isoform of LOX-1 that acts as a dominant negative, plays a protective role against ox-LDL-induced apoptosis in hEPC. Human endothelial progenitor cells exposed to ox-LDL showed a significant increase in LOX-1 expression, and apoptosis began at ox-LDL concentrations above 50 μg/mL. All hEPC apoptosed at 200 μg/mL ox-LDL. High LOXIN expression was generated using adenoviral systems in hEPC and SiHa cells transduced with 100 colony-forming units per cell. Transduced LOXIN localized to the plasma membrane and blocked ox-LDL uptake mediated by LOX-1. Overexpression of LOXIN protected hEPC from ox-LDL-induced apoptosis, and therefore maybe a novel way of improving hEPC function and quantity. These results suggest that adenoviral vectors of LOXIN may provide a possible treatment for diseases related to ox-LDL and vascular endothelium dysfunction, including atherosclerosis. PMID:26771151

  5. S-adenosylmethionine increases circulating very-low density lipoprotein clearance in nonalcoholic fatty liver disease

    PubMed Central

    Martinez-Una, Maite; Varela-Rey, Marta; Mestre, Daniela; Fernandez-Ares, Larraitz; Fresnedo, Olatz; Fernandez-Ramos, David; Juan, Virginia Gutierrez-de; Martin-Guerrero, Idoia; Garcia-Orad, Africa; Luka, Zigmund; Wagner, Conrad; Lu, Shelly C; Garcia-Monzon, Carmelo; Finnell, Richard H; Aurrekoetxea, Igor; Buque, Xabier; Martinez-Chantar, M. Luz; Mato, Jose M.; Aspichueta, Patricia

    2014-01-01

    Background Very-low density-lipoproteins (VLDL) export lipids from liver to peripheral tissues and are the precursors of low-density-lipoproteins. Low levels of hepatic S-adenosylmethionine (SAMe) decrease triglyceride (TG) secretion in VLDL contributing to hepatosteatosis in methionine adenosyltransferase 1A knockout mice but nothing is known about the effect of SAMe over circulating VLDL metabolism. Objective We wanted to investigate whether excess SAMe could disrupt VLDL plasma metabolism and unravel the mechanisms involved. Methods Glycine N-methyltransferase (GNMT) knockout (KO), GNMT-PLIN2-KO and their respective wild types (WT) were used. A high fat diet (HFD) or a methionine deficient diet (MDD) was administrated to exacerbate or recover VLDL metabolism, respectively. Finally, 33 patients with nonalcoholic fatty-liver disease (NAFLD); 11 with hypertriglyceridemia and 22 with normal lipidemia were used in this study. Results We found that excess SAMe increases turnover of hepatic TG stores for secretion in VLDL in GNMT-KO mice, a model of NAFLD with high SAMe levels. The disrupted VLDL assembly resulted in the secretion of enlarged, phosphatidylethanolamine-poor, TG-and apoE-enriched VLDL-particles; special features that lead to increased VLDL clearance and decreased serum TG levels. Re-establishing normal SAMe levels restore VLDL secretion, features and metabolism. In NAFLD patients, serum TG levels are lower when hepatic GNMT-protein expression is decreased. Conclusion Excess hepatic SAMe levels disrupt VLDL assembly and features and increase circulating VLDL clearance which will cause increased VLDL-lipid supply to tissues and might contribute to the extrahepatic complications of NAFLD. Electronic word count: 235 PMID:25457203

  6. Residual Cardiovascular Risk in Chronic Kidney Disease: Role of High-density Lipoprotein

    PubMed Central

    Kon, Valentina; Yang, Haichun; Fazio, Sergio

    2016-01-01

    Although reducing low-density lipoprotein-cholesterol (LDL-C) levels with lipid-lowering agents (statins) decreases cardiovascular disease (CVD) risk, a substantial residual risk (up to 70% of baseline) remains after treatment in most patient populations. High-density lipoprotein (HDL) is a potential contributor to residual risk, and low HDL-cholesterol (HDL-C) is an established risk factor for CVD. However, in contrast to conventional lipid-lowering therapies, recent studies show that pharmacologic increases in HDL-C levels do not bring about clinical benefits. These observations have given rise to the concept of dysfunctional HDL where increases in serum HDL-C may not be beneficial because HDL loss of function is not corrected by or even intensified by the therapy. Chronic kidney disease (CKD) increases CVD risk, and patients whose CKD progresses to end-stage renal disease (ESRD) requiring dialysis are at the highest CVD risk of any patient type studied. The ESRD population is also unique in its lack of significant benefit from standard lipid-lowering interventions. Recent studies indicate that HDL-C levels do not predict CVD in the CKD population. Moreover, CKD profoundly alters metabolism and composition of HDL particles and impairs their protective effects on functions such as cellular cholesterol efflux, endothelial protection, and control of inflammation and oxidation. Thus, CKD-induced perturbations in HDL may contribute to the excess CVD in CKD patients. Understanding the mechanisms of vascular protection in renal disease can present new therapeutic targets for intervention in this population. PMID:26009251

  7. Trypanosome Lytic Factor, an Antimicrobial High-Density Lipoprotein, Ameliorates Leishmania Infection

    PubMed Central

    Samanovic, Marie; Molina-Portela, Maria Pilar; Chessler, Anne-Danielle C.; Burleigh, Barbara A.; Raper, Jayne

    2009-01-01

    Innate immunity is the first line of defense against invading microorganisms. Trypanosome Lytic Factor (TLF) is a minor sub-fraction of human high-density lipoprotein that provides innate immunity by completely protecting humans from infection by most species of African trypanosomes, which belong to the Kinetoplastida order. Herein, we demonstrate the broader protective effects of human TLF, which inhibits intracellular infection by Leishmania, a kinetoplastid that replicates in phagolysosomes of macrophages. We show that TLF accumulates within the parasitophorous vacuole of macrophages in vitro and reduces the number of Leishmania metacyclic promastigotes, but not amastigotes. We do not detect any activation of the macrophages by TLF in the presence or absence of Leishmania, and therefore propose that TLF directly damages the parasite in the acidic parasitophorous vacuole. To investigate the physiological relevance of this observation, we have reconstituted lytic activity in vivo by generating mice that express the two main protein components of TLFs: human apolipoprotein L-I and haptoglobin-related protein. Both proteins are expressed in mice at levels equivalent to those found in humans and circulate within high-density lipoproteins. We find that TLF mice can ameliorate an infection with Leishmania by significantly reducing the pathogen burden. In contrast, TLF mice were not protected against infection by the kinetoplastid Trypanosoma cruzi, which infects many cell types and transiently passes through a phagolysosome. We conclude that TLF not only determines species specificity for African trypanosomes, but can also ameliorate an infection with Leishmania, while having no effect on T. cruzi. We propose that TLFs are a component of the innate immune system that can limit infections by their ability to selectively damage pathogens in phagolysosomes within the reticuloendothelial system. PMID:19165337

  8. Apolipoprotein B100 quality control and the regulation of hepatic very low density lipoprotein secretion

    PubMed Central

    Fisher, Eric; Lake, Elizabeth; McLeod, Roger S

    2014-01-01

    Abstract Apolipoprotein B (apoB) is the main protein component of very low density lipoprotein (VLDL) and is necessary for the assembly and secretion of these triglyceride (TG)-rich particles. Following release from the liver, VLDL is converted to low density lipoprotein (LDL) in the plasma and increased production of VLDL can therefore play a detrimental role in cardiovascular disease. Increasing evidence has helped to establish VLDL assembly as a target for the treatment of dyslipidemias. Multiple factors are involved in the folding of the apoB protein and the formation of a secretion-competent VLDL particle. Failed VLDL assembly can initiate quality control mechanisms in the hepatocyte that target apoB for degradation. ApoB is a substrate for endoplasmic reticulum associated degradation (ERAD) by the ubiquitin proteasome system and for autophagy. Efficient targeting and disposal of apoB is a regulated process that modulates VLDL secretion and partitioning of TG. Emerging evidence suggests that significant overlap exists between these degradative pathways. For example, the insulin-mediated targeting of apoB to autophagy and postprandial activation of the unfolded protein response (UPR) may employ the same cellular machinery and regulatory cues. Changes in the quality control mechanisms for apoB impact hepatic physiology and pathology states, including insulin resistance and fatty liver. Insulin signaling, lipid metabolism and the hepatic UPR may impact VLDL production, particularly during the postprandial state. In this review we summarize our current understanding of VLDL assembly, apoB degradation, quality control mechanisms and the role of these processes in liver physiology and in pathologic states. PMID:25013401

  9. Metabolism of triglyceride-rich nascent rat hepatic high density lipoproteins

    SciTech Connect

    Winkler, K.E.; Marsh, J.B. )

    1989-07-01

    Nascent high density lipoprotein (HDL) and nascent very low density lipoprotein (VLDL) were isolated from rat livers that had been perfused with (3H)glycerol to label the triglyceride. When injected into intact rats, the labeled HDL-triglyceride disappeared as rapidly as the VLDL-triglyceride, with only 10% of the injected label remaining in the plasma after 30 min. The protein moiety of nascent HDL was labeled with (35S)methionine in a similar fashion and the labeled nascent HDL was separated into nonretained (NR) and retained (R) fractions by heparin-Sepharose affinity chromatography. When injected into rats, 55% of the injected label in nascent fraction NR and 72% of that in nascent fraction R was recovered from plasma at 30 min, compared to only 10% of the triglyceride label from unfractionated nascent HDL, indicating dissociation of triglyceride and apolipoprotein clearance. The plasma decay curves for both triglyceride and protein were biexponential. By 5 min, 15% of the 35S label remaining in plasma represented apoE and apoC that had been transferred from nascent HDL fractions NR and R to the d less than 1.063 g/ml fraction of plasma. Plasma HDL was labeled in vivo with (35S)methionine, separated into fractions NR and R, and the clearance of the two plasma HDL fractions was compared with that of the corresponding nascent HDL fractions. Except for a faster rate of removal of the nascent HDL fractions during the first 5 min, the serum decay curves were very similar.

  10. Metabolic fate of sphingomyelin of high-density lipoprotein in rat plasma

    SciTech Connect

    Bentejac, M.; Bugaut, M.; Delachambre, M.C.; Lecerf, J. )

    1990-10-01

    The metabolic fate of high density lipoprotein (HDL) sphingomyelin in plasma was studied in rats over a 24-hr period after injection of HDL containing sphingomyelin which was {sup 14}C-labeled in the stearic (18:0) or lignoceric acid (24:0) moiety and {sup 3}H-labeled in the choline methyl groups. Decay of label in plasma followed three phases. The first two phases were similar for both isotopes and both types of sphingomyelin (t1/2 approximately 10 and 110 min). However, during the third phase (from 10 hr after injection), {sup 3}H label disappeared more slowly than {sup 14}C label from 18:0 sphingomyelin, whereas the {sup 3}H/{sup 14}C ratio remained relatively constant when 24:0 sphingomyelin was used. Intact, doubly-labeled 18:0 sphingomyelin disappeared from HDL rapidly (t1/2 = 38 min) by tissue uptake and by transfer to very low density lipoprotein (VLDL). VLDL contained up to 12% of the sphingomyelin 1 hr after injection. This is the first demonstration of a transfer in vivo of sphingomyelin from HDL to VLDL. A similarly rapid transfer was also observed in vitro. Some nontritiated, ({sup 14}C)18:0 or ({sup 14}C)24:0 sphingomyelin was redistributed more slowly into HDL. Doubly-labeled phosphatidylcholine appeared in VLDL and HDL within 1 hr after injection and reached 1.8 and 2.1% of the injected {sup 14}C and {sup 3}H in VLDL at 1 hr, and 4.8 and 6.9% in HDL at 3 hr, respectively.

  11. Nonpharmacologic and pharmacologic alteration of high-density lipoprotein cholesterol: therapeutic approaches to prevention of atherosclerosis.

    PubMed

    Glueck, C J

    1985-11-01

    High-density lipoprotein (HDL) cholesterol, an independent coronary heart disease (CHD) risk factor, is inversely associated with CHD. Whether interventions to increase concentrations of HDL--particularly the HDL2, HDL3, and apolipoprotein A1 subfractions--will reduce the incidence of CHD in high-risk patients is thus an area of intense speculation. Both nonpharmacologic and pharmacologic regimens will raise HDL concentrations. Nonpharmacologic approaches include habitual high-level aerobic exercise and weight loss--both of these somewhat more effective in men than in women--cessation of cigarette smoking, and changing of dietary habits. A number of drugs have been found to elevate HDL cholesterol. These include the bile acid-binding resin cholestyramine, nicotinic acid, gemfibrozil, phenytoin, exogenous estrogens, and alcohol. Terbutaline has also been reported to raise HDL cholesterol. It is not yet known whether, and to what degree, pharmacologic and nonpharmacologic elevation of HDL cholesterol will retard or reverse the progression of atherosclerosis. Conversely, HDL cholesterol is lowered by a broad variety of drugs, including anabolic--androgenic steroids, exogenous progestins, and probucol, which are used therapeutically to reduce low-density lipoprotein (LDL) cholesterol. Some agents used to treat hypertension also reduce HDL cholesterol, especially thiazide diuretics and the beta blockers, with the possible exception of pindolol. In the antiadrenergic class of antihypertensive agents, reserpine and methyldopa lower HDL cholesterol, but the alpha blocker prazosin does not appear to affect HDL cholesterol. The alpha agonist guanabenz has no effect on HDL cholesterol, and the vasodilator carprazidil has been reported to raise HDL cholesterol. In light of these facts, investigations should be undertaken to determine whether the metabolic effects of antihypertensive agents blunt their beneficial effects on CHD.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2865887

  12. Low high-density lipoprotein cholesterol: current status and future strategies for management

    PubMed Central

    Singh, Vibhuti; Sharma, Rakesh; Kumar, Ajoy; Deedwania, Prakash

    2010-01-01

    Atherosclerotic cardiovascular disease is the foremost cause of death and disability in the Western world, and it is rapidly becoming so in the developing nations. Even though the use of statin therapy aiming at the low-density lipoprotein cholesterol (LDL) has significantly reduced cardiovascular events and mortality, substantial residual cardiac events still occur in those being treated to the currently recommended targets. In fact, residual risk is also seen in those who are treated “aggressively” such as the “high risk” patients so defined by the National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III). Consequently, one must look for the predictors of risk beyond LDL reduction. High-density lipoprotein cholesterol (HDL) is the next frontier. The protectiveness of elevated HDL against atherosclerosis is well described in the literature. HDL subdues several atherogenic processes, such as oxidation, inflammation, cell proliferation and thrombosis. It also helps mobilize the excess LDL via reverse cholesterol transport. Low levels of HDL have been shown to be independent predictors of risk. Thus, therapies to raise the HDL hold promise for additional cardiac risk reduction. In this regard, several randomized trials have recently tested this hypothesis, especially in patients at high risk. In addition to the use of aggressive lifestyle modification, clinical outcomes have been measured following augmentation of HDL levels with various treatment modalities, including aggressive statin therapy, combination therapy with fibrates and niacin, and direct HDL-raising drug treatments. These data for low HDL as an independent risk factor and as the new treatment target are reviewed in this paper. PMID:21127701

  13. Distribution of High-Density Lipoprotein Subfractions and Hypertensive Status: A Cross-Sectional Study.

    PubMed

    Zhang, Yan; Li, Sha; Xu, Rui-Xia; Guo, Yuan-Lin; Wu, Na-Qiong; Zhu, Cheng-Gang; Gao, Ying; Dong, Qian; Liu, Geng; Sun, Jing; Li, Jian-Jun

    2015-10-01

    The exact mechanisms of hypertension contributing to atherosclerosis have not been fully elucidated. Although multiple studies have clarified the association with low-density lipoprotein (LDL) subfractions, uncertainty remains about its relationship with high-density lipoprotein (HDL) subfractions. Therefore, we aimed to comprehensively determine the relationship between distribution of HDL subfractions and hypertensive status.A total of 953 consecutive subjects without previous lipid-lowering drug treatment were enrolled and were categorized based on hypertension history (with hypertension [n = 550] or without hypertension [n = 403]). Baseline clinical and laboratory data were collected. HDL separation was performed using the Lipoprint System.Plasma large HDL-cholesterol (HDL-C) and large HDL percentage were dramatically lower whereas the small HDL-C and small HDL percentage were higher in patients with hypertension (all P < 0.05). The antihypertensive drug therapy was not associated with large or small HDL subfractions (on treatment vs not on treatment, P > 0.05; combination vs single drug therapy, P > 0.05). However, the blood pressure well-controlled patients have significantly lower small HDL subfraction (P < 0.05). Moreover, large HDL-C and percentage were inversely whereas small HDL percentage was positively associated with incident hypertension after adjusting potential confounders (all P < 0.05). In the multivariate model conducted in patients with and without hypertension separately, the cardio-protective value of large HDL-C was disappeared in patients with hypertension (OR 95%CI: 1.011 [0.974-1.049]).The distribution of HDL subfractions is closely associated with hypertensive status and hypertension may potentially impact the cardio-protective value of large HDL subfraction. PMID:26512616

  14. Physical inactivity interacts with an endothelial lipase polymorphism to modulate high density lipoprotein cholesterol in the GOLDN study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    BACKGROUND: Plasma high density lipoprotein (HDL) cholesterol (HDL-C) concentration is highly heritable but is also modifiable by environmental factors including physical activity. HDL-C response to exercise varies among individuals, and this variability may be associated with genetic polymorphism...

  15. Genetic variation at the PCSK9 locus, low density lipoproteins, response to pravastatin and coronary heart disease: results from PROSPER

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Caucasian carriers of the T allele at R46L in the proprotein convertase subtilisin/kexin type 9 (PCSK9) locus have been reported to have 15% lower low-density lipoprotein (LDL) cholesterol (C) levels and 47% lower coronary heart disease (CHD) risk. Our objective was to examine two PCSK9 single nucle...

  16. Simulation of High Density Lipoprotein Behavior on a Few Layer Graphene Undergoing Non-Uniform Mechanical Load.

    PubMed

    Glukhova, Olga E; Prytkova, Tatiana R; Savostyanov, George V

    2016-04-21

    Effect of a nonuniform external mechanical load on high density lipoprotein (HDL) in aqueous medium was investigated using course-grained molecular dynamics simulations. The nonuniform load was achieved by a few layer graphene on one side and closed single-walled carbon nanotube (SWNT) (7, 7) on the opposite side of lipoprotein. The tube had a diameter of 1 nm and was oriented perpendicularly to the graphene. HDL was located between them. The tube was approaching to HDL on graphene deforming it. We considered two cases of the tube movement with velocities of 20 and 5 m/s. Coarse-grained (CG) molecular dynamics with application of the MARTINI force field for HDL and coarse-grained model with an all-atom (AA)/CG mapping ratio of 1.5 for carbon nanotube (CNT) (each CG bead was modeled by the 4-site CG benzene) were used. Coarse-grained model of HDL was received by method of self-assembly. HDL was static but not fixed that gave the possibility to compensate its external influence in some way. It was established that in water medium HDL interacted with graphene substrate. It was established that in water HDL interacts with graphene substrate, slightly flattening but retaining its shape of the whole. It was also observed that during the calculations HDL partially dodged nanotube. Lipoprotein belts unfolded on the graphene substrate in the way of the best compensation for the impact of nanotubes. Finally, we observed that the approaching tube has passed through the less dense medium of dipalmitoylphosphatidylcholine (DPPC) and its pressure on the macromolecule decreased. Inhomogeneity of the external exposure deformed HDL at approximately 10-50%. The character of deformation demonstrated that lipoprotein has viscoelastic properties similar to a fluid. The discovered ability of lipoprotein may help to establish mechanism of interaction of lipoproteins with arterial walls and dynamic behavior of lipoproteins in arterial intima. PMID:27046673

  17. Gestational diabetes mellitus modulates neonatal high-density lipoprotein composition and its functional heterogeneity.

    PubMed

    Sreckovic, Ivana; Birner-Gruenberger, Ruth; Besenboeck, Carolin; Miljkovic, Milica; Stojakovic, Tatjana; Scharnagl, Hubert; Marsche, Gunther; Lang, Uwe; Kotur-Stevuljevic, Jelena; Jelic-Ivanovic, Zorana; Desoye, Gernot; Wadsack, Christian

    2014-11-01

    Gestational diabetes mellitus (GDM) is related to neonatal macrosomia and an increased risk of vascular events. We hypothesized that GDM exerts qualitative effects on neonatal high-density lipoprotein (HDL). HDL was isolated from control (n=11) and GDM maternal/neonatal donors (n=9) and subjected to shotgun proteomics. Differences in HDL mobility were assessed by FPLC and native gel-electrophoresis. Paraoxonase (PON1) activity, cholesterol ester-transfer protein (CETP) mass and activity, phospholipid, triglyceride and cholesterol concentrations were quantified with commercial kits. Total anti-oxidative capacity and cholesterol efflux capability of HDLs were measured. Four proteins involved in lipid metabolism, inflammation and innate immunity were differentially expressed between controls and GDM neonates. ApoM (decreased, p<0.05) and SAA1 (increased, p<0.05) showed the same differences on both, maternal and neonatal GDM HDL. Lower PON1 protein expression was corroborated by lower activity (p<0.05) which in turn was associated with attenuated anti-oxidant capacity of GDM HDL. Protein changes were accompanied by increased levels of triglycerides and decreased levels of cholesterol esters, respectively. The observed differences in GDM HDL lipid moiety may be related to CETP mass and activity alterations. The rate of cholesterol efflux from term trophoblasts to maternal and from placental endothelial cells to neonatal GDM HDL was impaired (p<0.05). In conclusion, GDM causes changes in HDL composition and is intimately associated with impaired cholesterol efflux capability as well as diminished anti-oxidative particle properties. Remodeling of neonatal GDM HDL in utero supports the hypothesis that maternal conditions in pregnancy impact neonatal lipoprotein metabolism. PMID:25130684

  18. Oxidized Low Density Lipoprotein (LDL) Affects Hyaluronan Synthesis in Human Aortic Smooth Muscle Cells*

    PubMed Central

    Viola, Manuela; Bartolini, Barbara; Vigetti, Davide; Karousou, Evgenia; Moretto, Paola; Deleonibus, Sara; Sawamura, Tatsuya; Wight, Thomas N.; Hascall, Vincent C.; De Luca, Giancarlo; Passi, Alberto

    2013-01-01

    Thickening of the vessel in response to high low density lipoprotein(s) (LDL) levels is a hallmark of atherosclerosis, characterized by increased hyaluronan (HA) deposition in the neointima. Human native LDL trapped within the arterial wall undergoes modifications such as oxidation (oxLDL). The aim of our study is to elucidate the link between internalization of oxLDL and HA production in vitro, using human aortic smooth muscle cells. LDL were used at an effective protein concentration of 20–50 μg/ml, which allowed 80% cell viability. HA content in the medium of untreated cells was 28.9 ± 3.7 nmol HA-disaccharide/cell and increased after oxLDL treatment to 53.9 ± 5.6. OxLDL treatments doubled the transcripts of HA synthase HAS2 and HAS3. Accumulated HA stimulated migration of aortic smooth muscle cells and monocyte adhesiveness to extracellular matrix. The effects induced by oxLDL were inhibited by blocking LOX-1 scavenger receptor with a specific antibody (10 μg/ml). The cholesterol moiety of LDL has an important role in HA accumulation because cholesterol-free oxLDL failed to induce HA synthesis. Nevertheless, cholesterol-free oxLDL and unmodified cholesterol (20 μg/ml) induce only HAS3 transcription, whereas 22,oxysterol affects both HAS2 and HAS3. Moreover, HA deposition was associated with higher expression of endoplasmic reticulum stress markers (CHOP and GRP78). Our data suggest that HA synthesis can be induced in response to specific oxidized sterol-related species delivered through oxLDL. PMID:23979132

  19. Cholesterol-Dependent Anaplasma phagocytophilum Exploits the Low-Density Lipoprotein Uptake Pathway

    PubMed Central

    Xiong, Qingming; Lin, Mingqun; Rikihisa, Yasuko

    2009-01-01

    In eukaryotes, intracellular cholesterol homeostasis and trafficking are tightly regulated. Certain bacteria, such as Anaplasma phagocytophilum, also require cholesterol; it is unknown, however, how this cholesterol-dependent obligatory intracellular bacterium of granulocytes interacts with the host cell cholesterol regulatory pathway to acquire cholesterol. Here, we report that total host cell cholesterol increased >2-fold during A. phagocytophilum infection in a human promyelocytic leukemia cell line. Cellular free cholesterol was enriched in A. phagocytophilum inclusions as detected by filipin staining. We determined that A. phagocytophilum requires cholesterol derived from low-density lipoprotein (LDL), because its replication was significantly inhibited by depleting the growth medium of cholesterol-containing lipoproteins, by blocking LDL uptake with a monoclonal antibody against LDL receptor (LDLR), or by treating the host cells with inhibitors that block LDL-derived cholesterol egress from late endosomes or lysosomes. However, de novo cholesterol biosynthesis is not required, since inhibition of the biosynthesis pathway did not inhibit A. phagocytophilum infection. The uptake of fluorescence-labeled LDL was enhanced in infected cells, and LDLR expression was up-regulated at both the mRNA and protein levels. A. phagocytophilum infection stabilized LDLR mRNA through the 3′ UTR region, but not through activation of the sterol regulatory element binding proteins. Extracellular signal–regulated kinase (ERK) was up-regulated by A. phagocytophilum infection, and inhibition of its upstream kinase, MEK, by a specific inhibitor or siRNA knockdown, reduced A. phagocytophilum infection. Up-regulation of LDLR mRNA by A. phagocytophilum was also inhibited by the MEK inhibitor; however, it was unclear whether ERK activation is required for LDLR mRNA up-regulation by A. phagocytophilum. These data reveal that A. phagocytophilum exploits the host LDL uptake pathway and LDLR mRNA regulatory system to accumulate cholesterol in inclusions to facilitate its replication. PMID:19283084

  20. Relation of Black Race between High Density Lipoprotein Cholesterol Content, High Density Lipoprotein Particles and Coronary Events (From the Dallas Heart Study)

    PubMed Central

    Chandra, Alvin; Neeland, Ian J.; Das, Sandeep R.; Khera, Amit; Turer, Aslan T.; Ayers, Colby R.; McGuire, Darren K.; Rohatgi, Anand

    2015-01-01

    Therapies targeting high density lipoprotein cholesterol content (HDL-C) have not improved coronary heart disease (CHD) outcomes. HDL particle concentration (HDL-P) may better predict CHD. However, the impact of race/ethnicity on the relations between HDL-P and subclinical atherosclerosis/ incident CHD events has not been described. Participants from the Dallas Heart Study, a multiethnic, probability-based, population cohort of Dallas County adults had the following baseline measurements: HDL-C, HDL-P by nuclear magnetic resonance imaging (NMR), and coronary artery calcium (CAC) by electron beam computed tomography. Participants were followed for a median of 9.3 years for incident CHD events (composite of first myocardial infarction, stroke, coronary revascularization, or cardiovascular death). The study comprised 1977 participants free from CHD (51% women, 46% Black). In adjusted models, HDL-C was not associated with prevalent CAC (p=0.13) or incident CHD overall (HR per 1SD: 0.89, 95% CI 0.76–1.05). However, HDL-C was inversely associated with incident CHD among non-Black (adjusted HR per 1SD 0.67, 95% CI 0.46–0.97) but not Black participants (HR 0.94, 95% CI 0.78–1.13, pinteraction = 0.05). Conversely, HDL-P, adjusted for risk factors and HDL-C, was inversely associated with prevalent CAC (p=0.009) and with incident CHD overall (adjusted HR per 1SD: 0.73, 95% CI 0.62–0.86) with no interaction by Black race/ethnicity (pinteraction = 0.57). In conclusion, in contrast to HDL-C, the inverse relationship between HDL-P and incident CHD events is consistent across ethnicities. These findings suggest that HDL-P is superior to HDL-C in predicting both prevalent atherosclerosis as well as incident CHD events across a diverse population and should be considered as a therapeutic target. PMID:25661572

  1. Collagenase-3 binds to a specific receptor and requires the low density lipoprotein receptor-related protein for internalization

    NASA Technical Reports Server (NTRS)

    Barmina, O. Y.; Walling, H. W.; Fiacco, G. J.; Freije, J. M.; Lopez-Otin, C.; Jeffrey, J. J.; Partridge, N. C.

    1999-01-01

    We have previously identified a specific receptor for collagenase-3 that mediates the binding, internalization, and degradation of this ligand in UMR 106-01 rat osteoblastic osteosarcoma cells. In the present study, we show that collagenase-3 binding is calcium-dependent and occurs in a variety of cell types, including osteoblastic and fibroblastic cells. We also present evidence supporting a two-step mechanism of collagenase-3 binding and internalization involving both a specific collagenase-3 receptor and the low density lipoprotein receptor-related protein. Ligand blot analysis shows that (125)I-collagenase-3 binds specifically to two proteins ( approximately 170 kDa and approximately 600 kDa) present in UMR 106-01 cells. Western blotting identified the 600-kDa protein as the low density lipoprotein receptor-related protein. Our data suggest that the 170-kDa protein is a specific collagenase-3 receptor. Low density lipoprotein receptor-related protein-null mouse embryo fibroblasts bind but fail to internalize collagenase-3, whereas UMR 106-01 and wild-type mouse embryo fibroblasts bind and internalize collagenase-3. Internalization, but not binding, is inhibited by the 39-kDa receptor-associated protein. We conclude that the internalization of collagenase-3 requires the participation of the low density lipoprotein receptor-related protein and propose a model in which the cell surface interaction of this ligand requires a sequential contribution from two receptors, with the collagenase-3 receptor acting as a high affinity primary binding site and the low density lipoprotein receptor-related protein mediating internalization.

  2. Mass Spectrometry-Based Proteomic Study Makes High-Density Lipoprotein a Biomarker for Atherosclerotic Vascular Disease

    PubMed Central

    Yang, Chao-Yuh; Tsai, Fuu-Jen; Lin, Shih-Yi

    2015-01-01

    High-density lipoprotein (HDL) is a lipid and protein complex that consists of apolipoproteins and lower level HDL-associated enzymes. HDL dysfunction is a factor in atherosclerosis and decreases patient survival. Mass spectrometry- (MS-) based proteomics provides a high throughput approach for analyzing the composition and modifications of complex HDL proteins in diseases. HDL can be separated according to size, surface charge, electronegativity, or apoprotein composition. MS-based proteomics on subfractionated HDL then allows investigation of lipoprotein roles in diseases. Herein, we review recent developments in MS-based quantitative proteomic techniques, HDL proteomics and lipoprotein modifications in diseases, and HDL subfractionation studies. We also discuss future directions and perspectives in MS-based proteomics on HDL. PMID:26090384

  3. PFOS induced lipid metabolism disturbances in BALB/c mice through inhibition of low density lipoproteins excretion

    NASA Astrophysics Data System (ADS)

    Wang, Ling; Wang, Yu; Liang, Yong; Li, Jia; Liu, Yuchen; Zhang, Jie; Zhang, Aiqian; Fu, Jianjie; Jiang, Guibin

    2014-04-01

    Male BALB/c mice fed with either a regular or high fat diet were exposed to 0, 5 or 20 mg/kg perfluorooctane sulfonate (PFOS) for 14 days. Increased body weight, serum glucose, cholesterol and lipoprotein levels were observed in mice given a high fat diet. However, all PFOS-treated mice got reduced levels of serum lipid and lipoprotein. Decreasing liver glycogen content was also observed, accompanied by reduced serum glucose levels. Histological and ultrastructural examination detected more lipid droplets accumulated in hepatocytes after PFOS exposure. Moreover, transcripitonal activity of lipid metabolism related genes suggests that PFOS toxicity is probably unrelevant to PPARα's transcription. The present study demonstrates a lipid disturbance caused by PFOS and thus point to its role in inhibiting the secretion and normal function of low density lipoproteins.

  4. Quantitative studies of transfer in vivo of low density, Sf 12-60, and Sf 60-400 lipoproteins between plasma and arterial intima in humans

    SciTech Connect

    Shaikh, M.; Wootton, R.; Nordestgaard, B.G.; Baskerville, P.; Lumley, J.S.; La Ville, A.E.; Quiney, J.; Lewis, B. )

    1991-05-01

    To assess the potential of various plasma lipoprotein classes to contribute to the lipid content of the arterial intima, influx and efflux of these plasma lipoprotein fractions into and from the intima of human carotid arteries were measured in vivo. While low density lipoprotein (LDL) is known to transfer from plasma into the arterial wall, there is less information on the atherogenic potential of lipoproteins of intermediate density (Sf 12-60) or of very low density (Sf 60-400). Aliquots of the same lipoprotein (LDL, Sf 12-60 lipoprotein particles, or Sf 60-400 lipoprotein particles) iodinated with iodine-125 and iodine-131 were injected intravenously 18-29 hours and 3-6 hours, respectively, before elective surgical removal of atheromatous arterial tissue, and the intimal clearance of lipoproteins, lipoprotein influx, and fractional loss of newly entered lipoproteins were calculated. Intimal clearance of Sf 60-400 particles was not detectable (less than 0.3 microliter x hr-1 x cm-2), whereas the average value for both LDL and Sf 12-60 lipoprotein particles was 0.9 microliter x hr-1 x cm-2. Since the fractional loss of newly entered LDL and Sf 12-60 lipoprotein particles was also similar, the results suggest similar modes of entry and exit for these two particles. However, due to lower plasma concentrations of Sf 12-60 lipoproteins as compared with LDL, the mass influx of cholesterol in the Sf 12-60 particles was on the order of one 10th of that in LDL, and that of apolipoprotein B was about one 20th.

  5. Estimation of the low-density (beta) lipoproteins of serum in health and disease using large molecular weight dextran sulphate

    PubMed Central

    Walton, K. W.; Scott, P. J.

    1964-01-01

    Studies have been made of the factors affecting the specificity of the interaction between high molecular weight dextran sulphate and low-density lipoproteins, both in pure solution and in serum. The results have been used in the development of a simple assay method for the serum concentration of low-density lipoproteins in small volumes of serum. The results obtained by this assay procedure have been found to correlate acceptably with parallel estimations of low-density lipoproteins by an ultracentrifugal technique and by paper electrophoresis. The technique has been applied to a survey of serum levels of these proteins in a normal population. The results have been compared with data in the literature. Satisfactory agreement was found between mean levels, matched for age and sex, between the dextran sulphate method and those methods based ultimately on chemical estimation of one or more components of the isolated lipoproteins. A systematic difference was observed when the dextran sulphate method was compared with estimates based on analytical ultracentrifugation or turbidimetry using amylopectin sulphate. Some indication of the range of application of the dextran sulphate method in clinical chemistry is provided. Images PMID:14227432

  6. Purification and properties of the very high density lipoprotein from the hemolymph of adult Triatoma infestans.

    PubMed

    Rimoldi, O J; Soulages, J L; González, S M; Peluffo, R O; Brenner, R R

    1989-06-01

    The very high density lipoprotein (VHDL) of Triatoma infestans hemolymph from adult males has been isolated and purified by two-step density gradient ultracentrifugation. It appears to be homogeneous as judged by native polyacrylamide gel electrophoresis. The content of VHDL in hemolymph was estimated to be 8 mg protein/ml. The purified protein has a molecular weight (Mr) of 450,000, is composed of six subunits of Mr approximately equal to 77,000, and possesses a high content of aromatic amino acids. This protein is glycosylated and contains 3% of lipids by weight with a remarkable amount of free fatty acids (25% of total lipids). The T. infestans VHDL has a different lipid and amino acid composition from lipophorin. The lipid composition and the spectroscopic studies using cis-parinaric acid indicated a high fatty acid binding affinity. It has nine binding sites per mol of VHDL. Competence studies revealed that VHDL has its highest affinity for the binding of palmitic acid followed by stearic and arachidonic acids. PMID:2677201

  7. Lipopolysaccharide Is Cleared from the Circulation by Hepatocytes via the Low Density Lipoprotein Receptor

    PubMed Central

    Topchiy, Elena; Cirstea, Mihai; Kong, HyeJin Julia; Boyd, John H.; Wang, Yingjin; Russell, James A.; Walley, Keith R.

    2016-01-01

    Sepsis is the leading cause of death in critically ill patients. While decreased Proprotein Convertase Subtilisin/Kexin type 9 (PCSK9) function improves clinical outcomes in murine and human sepsis, the mechanisms involved have not been fully elucidated. We tested the hypothesis that lipopolysaccharide (LPS), the major Gram-negative bacteria endotoxin, is cleared from the circulation by hepatocyte Low Density Lipoprotein Receptors (LDLR)—receptors downregulated by PCSK9. We directly visualized LPS uptake and found that LPS is rapidly taken up by hepatocytes into the cell periphery. Over the course of 4 hours LPS is transported towards the cell center. We next found that clearance of injected LPS from the blood was reduced substantially in Ldlr knockout (Ldlr-/-) mice compared to wild type controls and, simultaneously, hepatic uptake of LPS was also reduced in Ldlr-/- mice. Specifically examining the role of hepatocytes, we further found that primary hepatocytes isolated from Ldlr-/- mice had greatly decreased LPS uptake. In the HepG2 immortalized human hepatocyte cell line, LDLR silencing similarly resulted in decreased LPS uptake. PCSK9 treatment reduces LDLR density on hepatocytes and, therefore, was another independent strategy to test our hypothesis. Incubation with PCSK9 reduced LPS uptake by hepatocytes. Taken together, these findings demonstrate that hepatocytes clear LPS from the circulation via the LDLR and PCSK9 regulates LPS clearance from the circulation during sepsis by downregulation of hepatic LDLR. PMID:27171436

  8. Familial defective apolipoprotein B-100: low density lipoproteins with abnormal receptor binding

    SciTech Connect

    Innerarity, T.L.; Weisgraber, K.H.; Arnold, K.S.; Mahley, R.W.; Krauss, R.M.; Vega, G.L.; Grundy, S.M.

    1987-10-01

    Previous in vivo turnover studies suggested that retarded clearance of low density lipoproteins (LDL) from the plasma of some hypercholesterolemic patients is due to LDL with defective receptor binding. The present study examined this postulate directly by receptor binding experiments. The LDL from a hypercholesterolemic patient (G.R.) displayed a reduced ability to bind to the LDL receptors on normal human fibroblasts. The G.R. LDL possessed 32% of normal receptor binding activity. Likewise, the G.R. LDL were much less effective than normal LDL in competing with /sup 125/I-labeled normal LDL for cellular uptake and degradation and in stimulating intracellular cholesteryl ester synthesis. The defect in LDL binding appears to be due to a genetic abnormality of apolipoprotein B-100: two brothers of the proband possess LDL defective in receptor binding, whereas a third brother and the proband's son have normally binding LDL. Further, the defect in receptor binding does not appear to be associated wit an abnormal lipid composition or structure of the LDL. Normal and abnormal LDL subpopulations were partially separated from plasma of two subjects by density-gradient ultracentrifugation, a finding consistent with the presence of a normal and a mutant allele. The affected family members appear to be heterozygous for this disorder, which has been designated familial defective apolipoprotein B-100. These studies indicate that the defective receptor binding results in inefficient clearance of LDL and the hypercholesterolemia observed in these patients.

  9. Bone and high-density lipoprotein: The beginning of a beautiful friendship

    PubMed Central

    Papachristou, Dionysios J; Blair, Harry C

    2016-01-01

    There is a tight link between bone and lipid metabolic pathways. In this vein, several studies focused on the exploration of high-density lipoprotein (HDL) in the pathobiology of bone diseases, with emphasis to the osteoarthritis (OA) and osteoporosis, the most common bone pathologies. Indeed, epidemiological and in vitro data have connected reduced HDL levels or dysfunctional HDL with cartilage destruction and OA development. Recent studies uncovered functional links between HDL and OA fueling the interesting hypothesis that OA could be a chronic element of the metabolic syndrome. Other studies have linked HDL to bone mineral density. Even though at epidemiological levels the results are conflicting, studies in animals as well as in vitro experiments have shown that HDL facilitates osteoblastogensis and bone synthesis and most probably affects osteoclastogenesis and osteoclast bone resorption. Notably, reduced HDL levels result in increased bone marrow adiposity affecting bone cells function. Unveiling the mechanisms that connect HDL and bone/cartilage homeostasis may contribute to the design of novel therapeutic agents for the improvement of bone and cartilage quality and thus for the treatment of related pathological conditions. PMID:26925377

  10. Lipopolysaccharide Is Cleared from the Circulation by Hepatocytes via the Low Density Lipoprotein Receptor.

    PubMed

    Topchiy, Elena; Cirstea, Mihai; Kong, HyeJin Julia; Boyd, John H; Wang, Yingjin; Russell, James A; Walley, Keith R

    2016-01-01

    Sepsis is the leading cause of death in critically ill patients. While decreased Proprotein Convertase Subtilisin/Kexin type 9 (PCSK9) function improves clinical outcomes in murine and human sepsis, the mechanisms involved have not been fully elucidated. We tested the hypothesis that lipopolysaccharide (LPS), the major Gram-negative bacteria endotoxin, is cleared from the circulation by hepatocyte Low Density Lipoprotein Receptors (LDLR)-receptors downregulated by PCSK9. We directly visualized LPS uptake and found that LPS is rapidly taken up by hepatocytes into the cell periphery. Over the course of 4 hours LPS is transported towards the cell center. We next found that clearance of injected LPS from the blood was reduced substantially in Ldlr knockout (Ldlr-/-) mice compared to wild type controls and, simultaneously, hepatic uptake of LPS was also reduced in Ldlr-/- mice. Specifically examining the role of hepatocytes, we further found that primary hepatocytes isolated from Ldlr-/- mice had greatly decreased LPS uptake. In the HepG2 immortalized human hepatocyte cell line, LDLR silencing similarly resulted in decreased LPS uptake. PCSK9 treatment reduces LDLR density on hepatocytes and, therefore, was another independent strategy to test our hypothesis. Incubation with PCSK9 reduced LPS uptake by hepatocytes. Taken together, these findings demonstrate that hepatocytes clear LPS from the circulation via the LDLR and PCSK9 regulates LPS clearance from the circulation during sepsis by downregulation of hepatic LDLR. PMID:27171436

  11. Bone and high-density lipoprotein: The beginning of a beautiful friendship.

    PubMed

    Papachristou, Dionysios J; Blair, Harry C

    2016-02-18

    There is a tight link between bone and lipid metabolic pathways. In this vein, several studies focused on the exploration of high-density lipoprotein (HDL) in the pathobiology of bone diseases, with emphasis to the osteoarthritis (OA) and osteoporosis, the most common bone pathologies. Indeed, epidemiological and in vitro data have connected reduced HDL levels or dysfunctional HDL with cartilage destruction and OA development. Recent studies uncovered functional links between HDL and OA fueling the interesting hypothesis that OA could be a chronic element of the metabolic syndrome. Other studies have linked HDL to bone mineral density. Even though at epidemiological levels the results are conflicting, studies in animals as well as in vitro experiments have shown that HDL facilitates osteoblastogensis and bone synthesis and most probably affects osteoclastogenesis and osteoclast bone resorption. Notably, reduced HDL levels result in increased bone marrow adiposity affecting bone cells function. Unveiling the mechanisms that connect HDL and bone/cartilage homeostasis may contribute to the design of novel therapeutic agents for the improvement of bone and cartilage quality and thus for the treatment of related pathological conditions. PMID:26925377

  12. Possible role of the Golgi apparatus in the assembly of very low density lipoprotein

    SciTech Connect

    Bamberger, M.J.; Lane, M.D. )

    1990-04-01

    Transit of newly synthesized triacyl(3H)-glycerol through organelles of the secretory system leading to assembly into nascent very low density lipoproteins (VLDLs) or to cytoplasmic storage was investigated in chick hepatocytes. Cells in monolayer culture were pulse-labeled with (2-3H)glycerol, and after different periods of chase with unlabeled glycerol, the movement of triacyl(3H)glycerol through the endoplasmic reticulum (ER) and Golgi and the incorporation into nascent VLDL and cytoplasmic triacylglycerol-rich vesicles (TGRVs) were determined. Initially, newly synthesized triacyl(3H)glycerol is tightly associated with the ER. Movement from the ER of triacyl(3H)glycerol destined for cytoplasmic storage (as TGRVs) is extremely rapid and virtually complete within 8 min of chase. After 8 min of chase, triacyl(3H)glycerol lost from organelles of the secretory system was accounted for entirely as triacyl(3H)glycerol secreted as VLDL. Comparison of the rates of movement of triacyl(3H)glycerol, apolipoprotein B, apolipoprotein II, and apolipoprotein A-I through the ER and Golgi and of their secretion in nascent VLDL suggests that assembly of triacyglycerol with apolipoproteins occurs in the Golgi. Experiments with permeabilized hepatocytes supplemented with cytosol show that newly synthesized triacyl(3H)glycerol and (3H)phospholipid moves from the ER through the full-density range of Golgi elements and is dependent upon supplementary ATP.

  13. [A history and review of cholesterol ester transfer protein inhibitors and their contribution to the understanding of the physiology and pathophysiology of high density lipoprotein].

    PubMed

    Corral, Pablo; Schreier, Laura

    2014-01-01

    There is irrefutable evidence that statins reduce the risk of cardiovascular events in a magnitude proportional to the intensity of the decrease in cholesterol transport by the low density lipoproteins. Despite this great advance there is still a residual risk of cardiovascular events. For this reason, an increase in the levels of high density lipoprotein is considered in order to boost the main action of this lipoprotein, which is reverse cholesterol transport. Distinct classes of evidence (epidemiological, genetic, and pathophysiological) show that the inhibition and/or modulation of cholesterol ester transfer protein increases plasma high density lipoprotein-cholesterol levels. The main reason for presenting this review is to look at the physiology of cholesterol ester transfer protein, its interrelationship with high density lipoproteins, and to give an update on the development of different cholesterol ester transfer protein inhibitor/modulator molecules. PMID:24094503

  14. ApoE and the role of very low density lipoproteins in adipose tissue inflammation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Our goal was too identify the role of triglyceride-rich lipoproteins and apoE, a major apolipoprotein in triglyceride-rich lipoproteins, in adipose tissue inflammation with high-fat diet induced obesity. Male apoE-/- and C57BL/6J wild-type mice fed high fat diets for 12 weeks were assessed for metab...

  15. Coronary atherosclerosis, low-density lipoproteins and markers of thrombosis, inflammation and endothelial dysfunction.

    PubMed

    Whayne, Thomas F

    2007-01-01

    Available information regarding the relation among atherosclerosis, low-density lipoproteins, markers of thrombosis, inflammation and endothelial dysfunction has accumulated, but is still very limited, making only minimal contributions to clinical decision-making. Many more clinical trials are needed, but unless there is a relationship between atherosclerosis prevention, specific markers and a pharmaceutical product, financial support for such trials will be difficult to obtain. The anti-inflammatory effect of statins is well established. Angiotensin-converting enzyme inhibitors are generally not thought of as having anti-inflammatory effects, but the European Trial on Reduction of Cardiac Events with Perindopril in Stable Coronary Artery Disease (EUROPA) study observed extensive RR reduction with perindopril. It was explained not simply by control of hypertension, but by reduced activity of multiple factors, supported by specific substudies. The 'cardiovascular continuum' is an excellent unifying term to explain atherosclerosis mechanisms, relate mechanisms to clinical understanding, and assist the clinician in selecting the appropriate prevention and control therapies. This so-called continuum actually describes a relationship among different biochemical, enzymatic and hormonal factors that affect the cardiovascular system. It can be seen in the downregulation of the angiotensin II receptor type 1 by statins, which contributes to hypertension control while lowering low-density lipoproteins. Peroxisome proliferator activator receptor-gamma also demonstrates the cardiovascular continuum with activation of the receptor by glitazones. The glitazones increase insulin sensitivity for diabetes control. Activation of the peroxisome proliferator activator receptor-gamma inhibits inflammation, which is possibly related to atherosclerosis, normalization of endothelial function, suppression of metalloproteinases and a decrease in smooth muscle cell migration. All of these effects may decrease atherosclerosis production while improving control of diabetes mellitus, a key disease in the cardiovascular continuum for development of atherosclerosis. Consideration of such interrelationships is just scratching the surface. Nevertheless, it can be seen that the complicated process of atherosclerosis development has a multifaceted explanation that has been minimally defined, but holds the key to prevention and control of this major medical problem faced in modern society. PMID:22477242

  16. Elevated High-Density Lipoprotein Cholesterol and Age-Related Macular Degeneration: The Alienor Study

    PubMed Central

    Cougnard-Grégoire, Audrey; Delyfer, Marie-Noëlle; Korobelnik, Jean-François; Rougier, Marie-Bénédicte; Le Goff, Mélanie; Dartigues, Jean-François; Barberger-Gateau, Pascale; Delcourt, Cécile

    2014-01-01

    Background Lipid metabolism and particularly high-density lipoprotein (HDL) may be involved in the pathogenic mechanism of age-related macular degeneration (AMD). However, conflicting results have been reported in the associations of AMD with plasma HDL and other lipids, which may be confounded by the recently reported associations of AMD with HDL-related genes. We explored the association of AMD with plasma lipid levels and lipid-lowering medication use, taking into account most of HDL-related genes associated with AMD. Methods The Alienor study is a population-based study on age-related eye diseases performed in 963 elderly residents of Bordeaux (France). AMD was graded from non mydriatic color retinal photographs in three exclusive stages: no AMD (n = 430 subjects, 938 eyes); large soft distinct drusen and/or large soft indistinct drusen and/or reticular drusen and/or pigmentary abnormalities (early AMD, n = 176, 247); late AMD (n = 40, 61). Associations of AMD with plasma lipids (HDL, total cholesterol (TC), Low-density lipoprotein (LDL), and triglycerides (TG)) were estimated using Generalized Estimating Equation logistic regressions. Statistical analyses included 646 subjects with complete data. Results After multivariate adjustment for age, sex, educational level, smoking, BMI, lipid-lowering medication use, cardiovascular disease and diabetes, and for all relevant genetic polymorphisms (ApoE2, ApoE4, CFH Y402H, ARMS2 A69S, LIPC rs10468017, LIPC rs493258, LPL rs12678919, ABCA1 rs1883025 and CETP rs3764261), higher HDL was significantly associated with an increased risk of early (OR = 2.45, 95%CI: 1.54–3.90; P = 0.0002) and any AMD (OR = 2.29, 95%CI: 1.46–3.59; P = 0.0003). Association with late AMD was far from statistical significance (OR = 1.58, 95%CI: 0.48–5.17; p = 0.45). No associations were found for any stage of AMD with TC, LDL and TG levels, statin or fibrate drug use. Conclusions This study suggests that elderly patients with high HDL concentration may be at increased risk for AMD and, further, that HDL dysfunction might be implicated in AMD pathogenesis. PMID:24608419

  17. The soluble form of Alzheimer's amyloid beta protein is complexed to high density lipoprotein 3 and very high density lipoprotein in normal human plasma.

    PubMed

    Koudinov, A; Matsubara, E; Frangione, B; Ghiso, J

    1994-12-15

    The amyloid fibrils of Alzheimer's neuritic plaques and cerebral blood vessels are mainly composed of aggregated forms of a 39 to 44 amino acids peptide, named amyloid beta (A beta). A similar although soluble form of A beta (sA beta) has been identified in plasma, cerebrospinal fluid and cell culture supernatants, indicating that it is produced under physiologic conditions. We report here that sA beta in normal human plasma is associated with lipoprotein particles, in particular to the HDL3 and VHDL fractions where it is complexed to ApoJ and, to a lesser extent, to ApoAI. This was assessed by immunoprecipitation experiments of purified plasma lipoproteins and lipoprotein-depleted plasma and confirmed by means of amino acid sequence analysis. Moreover, biotinylated synthetic peptide A beta 1-40 was traced in normal human plasma in in vitro experiments. As in the case of sA beta, biotinylated A beta 1-40 was specifically recovered in the HDL3 and VHDL fractions. This data together with the previous demonstration that A beta 1-40 is taken up into the brain via a specific mechanism and possibly as an A beta 1-40-ApoJ complex indicate a role for HDL3- and VHDL-containing ApoJ in the transport of the peptide in circulation and suggest their involvement in the delivery of sA beta across the blood-brain barrier. PMID:7802646

  18. The very-high-density lipoprotein fraction of rabbit plasma is rich in tissue-derived cholesterol.

    PubMed

    Nanjee, M N; Miller, N E

    1991-11-01

    When plasma from rabbits, which several weeks earlier had been infused with [3H]cholesterol, was subjected to equilibrium density gradient ultracentrifugation, the specific radioactivity of cholesterol in the very-high-density lipoprotein (VHDL) fraction (d 1.22-1.32 g/ml) was three to 8-fold greater (mean, 5.5-fold; P less than 0.001) than that in high-density lipoproteins (HDL; d 1.06-1.21 g/ml). On size exclusion chromatography of plasma, no increase in specific radioactivity was seen in particles smaller than HDL. These findings suggest that those apolipoprotein-lipid complexes that dissociate from HDL during ultracentrifugation to form the VHDL fraction contain proportionately more tissue-derived cholesterol than do those that are more tightly bound to HDL. PMID:1932106

  19. Thyroid hormone increases plasma cholesteryl ester transfer protein activity and plasma high-density lipoprotein removal rate in transgenic mice.

    PubMed

    Berti, J A; Amaral, M E; Boschero, A C; Nunes, V S; Harada, L M; Castilho, L N; Oliveira, H C

    2001-05-01

    Thyroid dysfunction produces multiple alterations in plasma lipoprotein levels, including high-density lipoprotein (HDL). Cholesteryl ester transfer protein (CETP) and hepatic lipase (HL) are important proteins that modulate the metabolism of HDL. Thus, the effect of thyroid hormone on the activities of CETP and of HL was investigated using hypothyroid and hyperthyroid CETP transgenic (Tg) and nontransgenic (nTg) mice. Hyperthyroid Tg mice plasma lipoprotein (LP) profile analysis showed a significant increase in the very-low-density lipoprotein (VLDL) fraction (P <.001) and decrease in the HDL fraction (P <.005), whereas in the hypothyroid Tg mice an increase in low-density lipoprotein (LDL) was observed (P <.02). CETP activity was measured as the transfer of (14)C-cholesteryl ester (CE) from labeled HDL to LDL by an isotopic assay indicative of mass. Hyperthyroid Tg mice had twice as much plasma CETP activity as compared with their controls, while in hypothyroid Tg mice plasma CETP activity did not change. The role of CETP in determining the changes in LP profile of hyperthyroid animals was confirmed by showing that nTg wild-type hyperthyroid and euthyroid mice exhibited the same percent cholesterol distribution in LP. Postheparin HL activity measured in hyperthyroid Tg mice was significantly reduced (P <.05). (3)H-cholesteryl oleoyl ether ((3)H-Cet)-HDL plasma fractional removal rate (FRR) was approximately 2-fold faster in the hyperthyroid Tg mice than in controls, but was not modified in hypothyroid animals. Tissue uptake of (3)H-Cet was examined in 10 tissue samples: levels were significantly increased in skeletal muscle and decreased in small intestine in hyperthyroid Tg mice, and decreased in the small intestine of hypothyroid Tg mice. In conclusion, the excess of thyroid hormone accelerates HDL metabolism in CETP transgenic mice mainly due to an increase in plasma CETP activity and independently from the HL activity. Hypothyroid status did not change CETP activity and HDL metabolism. PMID:11319713

  20. The LPS2 mutation in TRIF is atheroprotective in hyperlipidemic low density lipoprotein receptor knockout mice.

    PubMed

    Richards, M Rachel; Black, Audrey S; Bonnet, David J; Barish, Grant D; Woo, Connie W; Tabas, Ira; Curtiss, Linda K; Tobias, Peter S

    2013-02-01

    Signaling through MyD88, an adaptor utilized by all TLRs except TLR3, is pro-atherogenic; however, it is unknown whether signaling through TIR-domain-containing adaptor-inducing interferon-β (TRIF), an adaptor used only by TLRs 3 and 4, is relevant to atherosclerosis. We determined that the TRIF(Lps2) lack-of-function mutation was atheroprotective in hyperlipidemic low density lipoprotein (LDL) receptor knockout (LDLr(-/-)) mice. LDLr(-/-) mice were crossed with either TRIF(Lps2) or TLR3 knockout mice. After feeding an atherogenic diet for 10-15 wks, atherosclerotic lesions in the heart sinus and aorta were quantitated. LDLr(-/-) mice with TRIF(Lps2) were significantly protected from atherosclerosis. TRIF(Lps2) led to a reduction in cytokines secreted from peritoneal macrophages (M) in response to hyperlipidemia. Moreover, heart sinus valves from hyperlipidemic LDLr(-/-) TRIF(Lps2) mice had significantly fewer lesional M. However, LDLr(-/-) mice deficient in TLR3 showed some enhancement of disease. Collectively, these data suggest that hyperlipidemia resulting in endogenous activation of the TRIF signaling pathway from TLR4 leads to pro-atherogenic events. PMID:22637968

  1. In vivo metabolism of I-123 labeled semisynthetic low density lipoproteins

    SciTech Connect

    Harper, P.V.

    1990-12-01

    We previously observed that small model beta-strand peptides (MBPs) selectively bind to human low density lipoprotein (hLDL) in vitro, and that some MBPs can be labeled with I-123-tyramine cellobiose (I-123-TyC). We hypothesized that metabolism of semisynthetic hLDL should mimic that of covalently labeled native hLDL, and planned to evaluate the biodistribution in rabbits of semisynthetic hLDL; to determine effects of prior oxidation and acetylation of the adsorbing hLDL on binding of MBPs and upon biodistribution of semisynthetic particles; and to begin biodistribution studies with semisynthetic hLDL in human subjects, with the eventual goal of application to experimental and clinical nuclear imaging studies. We have synthesized a radioiodotyrosine-containing MBP, designated betay, as a more suitable adsorbant to hLDL thanradioiodine-TyC-MBP, and optimized conditions for preparing radioiodine-betaY:hLDL. In rabbits both betaY and betaY:hLDL complexes were cleared from the bloodstream much more rapidly than radioiodine-TyC-hLDL or In-111-hLDL, and betaY in either form showed a biodistribution pattern different from that of directly radiolabeled hLDL. Even though radioiodine-betaY can be quickly and easily produced, we conclude that neither betaY alone nor semisynthetic betaY:hLDL particles are likely to prove useful as tracers of hLDL metabolism in vivo.

  2. Enhanced Sphingomyelinase Activity Contributes to the Apoptotic Capacity of Electronegative Low-Density Lipoprotein.

    PubMed

    Ke, Liang-Yin; Chan, Hua-Chen; Chen, Chih-Chieh; Lu, Jonathan; Marathe, Gopal K; Chu, Chih-Sheng; Chan, Hsiu-Chuan; Wang, Chung-Ya; Tung, Yi-Ching; McIntyre, Thomas M; Yen, Jeng-Hsien; Chen, Chu-Huang

    2016-02-11

    Sphingomyelinase (SMase) catalyzes the degradation of sphingomyelin to ceramide. In patients with metabolic syndrome or diabetes, circulating plasma ceramide levels are significantly higher than in normal individuals. Our data indicate that electronegative low-density lipoprotein (LDL) shows SMase activity, which leads to increased ceramide levels that can produce pro-inflammatory effects and susceptibility to aggregation. According to sequence alignment and protein structure predictions, the putative catalytic site of SMase activity is in the α2 region of apoB-100. To identify specific post-translational modifications of apoB100 near the catalytic region, we performed data-independent, parallel-fragmentation liquid chromatography/mass spectrometry (LC/MS(E)), followed by data analysis with ProteinLynx GlobalServer v2.4. Results showed that the serine of apoB100 in electronegative LDL was highly O-glycosylated, including S(1732), S(1959), S(2378), S(2408), and S(2429). These findings may support the changing of the α-helix/β-pleated sheets ratio in protein structure analysis. Further study is necessary to confirm the activation of SMase activity by electronegative LDL. PMID:26766134

  3. High Density Lipoprotein Nanoparticles Deliver RNAi to Endothelial Cells to Inhibit Angiogenesis

    PubMed Central

    Tripathy, Sushant; Vinokour, Elena; McMahon, Kaylin M.; Volpert, Olga V.; Thaxton, C. Shad

    2014-01-01

    Systemic delivery of therapeutic nucleic acids to target cells and tissues outside of the liver remains a major challenge. We synthesized a biomimetic high density lipoprotein nanoparticle (HDL NP) for delivery of a cholesteryl modified therapeutic nucleic acid (RNAi) to vascular endothelial cells, a cell type naturally targeted by HDL. HDL NPs adsorb cholesteryl modified oligonucleotides and protect them from nuclease degradation. As proof of principle, we delivered RNAi targeting vascular endothelial growth factor receptor 2 (VEGFR2) to endothelial cells to effectively silence target mRNA and protein expression in vitro. In addition, data show that treatment strongly attenuated in vivo neovascularization measured using a standard angiogenesis assay and in hypervascular tumor allografts where a striking reduction in tumor growth was observed. For effective delivery, HDL NPs required the expression of the cell surface protein scavenger receptor type-B1 (SR-B1). No toxicity of HDL NPs was measured in vitro or after in vivo administration. Thus, by using a biomimetic approach to nucleic acid delivery, data demonstrate that systemically administered RNAi-HDL NPs target SR-B1 expressing endothelial cells to deliver functional anti-angiogenic RNAi as a potential treatment of cancer and other neo-vascular diseases. PMID:25400330

  4. Low-density lipoprotein transport in blood vessel walls of squirrel monkeys

    SciTech Connect

    Tompkins, R.G.; Yarmush, M.L.; Schnitzer, J.J.; Colton, C.K.; Smith, K.A.; Stemerman, M.B. )

    1989-08-01

    Transmural accumulations of low-density lipoprotein (LDL) were examined in the blood vessel walls of four squirrel monkeys. Vascular wall concentrations of LDL were measured using quantitative autoradiography after {sup 125}I-labeled LDL circulation for 30 min. Profiles of relative tissue concentration from different sections in the same region were similar to each other, and there was little animal-to-animal variation. Concentrations were highest near the luminal endothelium, lower near the medial-adventitial border, and lowest within the media. Profiles from different regions fell into three groups: (1) aortic samples had steep intimal concentration gradients and near-zero media concentrations; (2) the iliac, femoral, popliteal, and common carotid arteries had higher intimal concentrations than group 1 but had similar concentrations deep within the media; and (3) the cerebral and coronary arteries, inferior vena cava, and pulmonary artery had intimal concentrations that were similar to group 2, but the concentrations deep within the media were greater than either groups 1 or 2. Arterial bifurcation profiles from the inner wall and the outer walls were similar to each other and to profiles from the upstream and downstream areas. Out of 280 total sites examined, 15 examples of profiles with substantially increased concentrations near the luminal endothelium were found scattered throughout the cardiovascular system, demonstrating that there are focal regions throughout the cardiovascular system which have greatly increased {sup 125}I-LDL transendothelial permeability.

  5. Upregulation of Sestrin2 Expression Protects Against Macrophage Apoptosis Induced by Oxidized Low-Density Lipoprotein

    PubMed Central

    Hu, Hong-Juan; Shi, Ze-Ya; Lin, Xiao-Lin; Chen, San-Mei; Wang, Qing-Yan

    2015-01-01

    Sestrin2 is involved in a different cellular response to stress conditions. However, the function of Sestrin2 in the cardiovascular system remains unknown. In the present study, we tested whether Sestrin2 has a beneficial effect on macrophage cell apoptosis induced by oxidized low-density lipoprotein (oxLDL). We found that oxLDL induces expression of Sestrin2 in RAW264.7 cells in a time-dependent and dose-dependent manner. We also found that knockdown of Sestrin2 using small RNA interference promotes cell apoptosis and reactive oxygen species production induced by oxLDL. In addition, our results show that the c-Jun NH(2)-terminal kinase (JNK)/c-Jun pathway is activated by oxLDL. Inhibiting the activity of the JNK pathway abolishes the increase of Sestrin2 induced by oxLDL. These findings suggest that the inductive effect of Sestrin2 is mediated by the JNK/c-Jun pathway. Our results indicate that the induction of Sestrin2 acts as a compensatory response to oxLDL for survival, implying that stimulating expression of Sestrin2 might be an effective pharmacological target for the treatment of lipid-related cardiovascular diseases. PMID:25692450

  6. Effects of dietary factors on oxidation of low-density lipoprotein particles.

    PubMed

    Lapointe, Annie; Couillard, Charles; Lemieux, Simone

    2006-10-01

    Oxidized low-density lipoproteins (ox-LDLs) appear to play a significant role in atherogenesis. In fact, circulating ox-LDL concentrations have been recognized as a risk factor for cardiovascular disease (CVD). A higher intake of some nutrients and specific food compounds such as monounsaturated fatty acids (MUFAs), polyunsaturated fatty acids (PUFAs) and flavonoids have also been associated with a lower risk of CVD. These dietary factors could be associated to a lower risk of CVD through a reduction of the atherogenicity of LDL particles through limited oxidation. Therefore, the purpose of this article is to review human clinical studies that evaluated effects of dietary antioxidant vitamins, fatty acids (MUFA, PUFA) and specific flavonoid-rich foods on LDL particle oxidation and describe potential mechanisms by which dietary factors may prevent oxidation of LDL particles. Antioxidant vitamin supplements such as alpha-tocopherol and ascorbic acid as well as beta-carotene and fish-oil supplements have not been clearly demonstrated to prevent oxidation of LDL particles. Moreover, inconsistent documented effects of flavonoid-rich food such as olive oil, tea, red wine and soy on LDL particle oxidizability may be explained by difference in variety and quantity of flavonoid compounds used among studies. However, a healthy food pattern such as the Mediterranean diet, which includes a combination of antioxidant compounds and flavonoid-rich foods, appears effective to decrease LDL particle oxidizability, which may give some insight of the cardiovascular benefits associated with the Mediterranean diet. PMID:16517144

  7. Bile Acids Reduce Endocytosis of High-Density Lipoprotein (HDL) in HepG2 Cells

    PubMed Central

    Röhrl, Clemens; Eigner, Karin; Fruhwürth, Stefanie; Stangl, Herbert

    2014-01-01

    High-density lipoprotein (HDL) transports lipids to hepatic cells and the majority of HDL-associated cholesterol is destined for biliary excretion. Cholesterol is excreted into the bile directly or after conversion to bile acids, which are also present in the plasma as they are effectively reabsorbed through the enterohepatic cycle. Here, we provide evidence that bile acids affect HDL endocytosis. Using fluorescent and radiolabeled HDL, we show that HDL endocytosis was reduced in the presence of high concentrations of taurocholate, a natural non-cell-permeable bile acid, in human hepatic HepG2 and HuH7 cells. In contrast, selective cholesteryl-ester (CE) uptake was increased. Taurocholate exerted these effects extracellularly and independently of HDL modification, cell membrane perturbation or blocking of endocytic trafficking. Instead, this reduction of endocytosis and increase in selective uptake was dependent on SR-BI. In addition, cell-permeable bile acids reduced HDL endocytosis by farnesoid X receptor (FXR) activation: chenodeoxycholate and the non-steroidal FXR agonist GW4064 reduced HDL endocytosis, whereas selective CE uptake was unaltered. Reduced HDL endocytosis by FXR activation was independent of SR-BI and was likely mediated by impaired expression of the scavenger receptor cluster of differentiation 36 (CD36). Taken together we have shown that bile acids reduce HDL endocytosis by transcriptional and non-transcriptional mechanisms. Further, we suggest that HDL endocytosis and selective lipid uptake are not necessarily tightly linked to each other. PMID:25010412

  8. Structure of apolipoprotein A-I in spherical high density lipoproteins of different sizes

    PubMed Central

    Silva, R. A. Gangani D.; Huang, Rong; Morris, Jamie; Fang, Jianwen; Gracheva, Elena O.; Ren, Gang; Kontush, Anatol; Jerome, W. Gray; Rye, Kerry-Anne; Davidson, W. Sean

    2008-01-01

    Spherical high density lipoproteins (HDL)† predominate in human plasma. However, little information exists on the structure of the most common HDL protein, apolipoprotein (apo) A-I, in spheres vs. better studied discoidal forms. We produced spherical HDL by incubating reconstituted discoidal HDL with physiological plasma-remodeling enzymes and compared apoA-I structure in discs and spheres of comparable diameter (79–80 and 93–96 Å). Using cross-linking chemistry and mass spectrometry, we determined that the general structural organization of apoA-I was overall similar between discs and spheres, regardless of diameter. This was the case despite the fact that the 93 Å spheres contained three molecules of apoA-I per particle compared with only two in the discs. Thus, apoA-I adopts a consistent general structural framework in HDL particles—irrespective of shape, size and the number of apoA-Is present. Furthermore, a similar cross-linking pattern was demonstrated in HDL particles isolated from human serum. We propose the first experiment-based molecular model of apoA-I in spherical HDL particles. This model provides a new foundation for understanding how apoA-I structure modulates HDL function and metabolism. PMID:18719128

  9. High-density-lipoprotein subfraction 3 interaction with glycosylphosphatidylinositol-anchored proteins.

    PubMed Central

    Nion, S; Briand, O; Lestavel, S; Torpier, G; Nazih, F; Delbart, C; Fruchart, J C; Clavey, V

    1997-01-01

    To elucidate further the binding of high-density-lipoprotein subfraction 3 (HDL3) to cells, the involvement of glycosylphosphatidylinositol-anchored proteins (GPI-proteins) was studied. Treatment of cultured cells, such as fibroblasts or SK-MES-1 cells, with a phosphatidylinositol-specific phospholipase C (PI-PLC) significantly decreases specific HDL3 binding. Moreover, PI-PLC treatment of cultured cells or cellular plasma membrane fractions results in releasing proteins. These proteins have a soluble form and can also bind HDL3, as revealed by ligand blotting experiments with HDL3. In order to obtain enriched GPI-proteins, we used a detergent-free purification method to prepare a caveolar membrane fraction. In the caveolar fraction, we obtained, by ligand blotting experiments, the enrichment of two HDL3-binding proteins with molecular masses of 120 and 80 kDa. These proteins were also revealed in a plasma membrane preparation with two other proteins, with molecular masses of 150 and 104 kDa, and were sensitive to PI-PLC treatment. Electron microscopy also showed the binding of Au-labelled HDL3 inside the caveolar membrane invaginations. In SK-MES-1 cells, HDL3 are internalized into a particular structure, resulting in the accumulation and concentration of such specific membrane domains. To sum up, a demonstration has been made of the implication of GPI-proteins as well as caveolae in the binding of HDL3 to cells. PMID:9371696

  10. Ferritin protects endothelial cells from oxidized low density lipoprotein in vitro.

    PubMed Central

    Juckett, M. B.; Balla, J.; Balla, G.; Jessurun, J.; Jacob, H. S.; Vercellotti, G. M.

    1995-01-01

    Low density lipoprotein (LDL), if it becomes oxidized, develops several unique properties including the capacity to provoke endothelial cytotoxicity via metal-catalyzed free radical-mediated mechanisms. As were previously have shown that iron-catalyzed oxidant injury to endothelial cells can be attenuated by the addition of exogenous iron chelators such as the lazaroids and deferoxamine, we have examined whether the endogenous iron chelator, ferritin, might provide protection from oxidized LDL. LDL oxidized by iron-containing hemin and H2O2 is toxic to endothelial cells in a time- and dose-dependent fashion. Endothelial cell ferritin content is increased by pretreatment of cells with iron compounds or by the direct addition of exogenous apoferritin; ferritin-loaded cells are markedly resistant to the toxicity caused by oxidized LDL. Iron inactivation by ferritin depends on its ferroxidase activity. When a recombinant human ferritin heavy chain mutant, 222, which is devoid of ferroxidase activity, is added to endothelial cells, unlike the excellent protection afforded by the wild-type recombinant heavy chain, endothelial cells are not protected from oxidized LDL. To assess the in vivo relevance of our observation, we examined human coronary arteries of cardiac explants taken from patients with end-stage atherosclerosis. Large amounts of immunoreactive ferritin are focally detected in atherosclerotic lesions, specifically in the myofibroblasts, macrophages, and endothelium without a notable increase in Prussian blue-detectable iron. These findings suggest that ferritin may modulate vascular cell injury in vivo. Images Figure 3 Figure 4 PMID:7677189

  11. Antioxidant effects of 14 Chinese traditional medicinal herbs against human low-density lipoprotein oxidation

    PubMed Central

    Lin, Hsin-Hung; Charles, Albert Linton; Hsieh, Chang-Wei; Lee, Ya-Chi; Ciou, Jhih-Ying

    2014-01-01

    The relationship between the antioxidant activities and inhibitory effect of 14 Chinese medicinal herbs against oxidized low-density lipoprotein (LDL) formation was evaluated. Prolongation of the lag phase of LDL oxidation depended on the concentration of the herbs. The concentration of each herb that was able to prolong the lag time by about two-fold was calculated and expressed as doubling-time concentration. The lower the doubling-time concentration, the stronger the inhibitory effect exhibited toward LDL oxidation. Among them, Chrysanthemi Flos (Chrysanthemum morifolium ramat; 甘菊花 gān jú huā), Crataegi Fructus (Crataegus pinnatifida Bge. var. major N.E.Br.; 山楂 shān zhā), and Roselle (Hibiscus sabdariffa Linn.; 洛神 luò shén) showed significant inhibitory effects. Correlation coefficients between doubling-time concentration and radical-scavenging activities were high; the total phenolic content was also high. In conclusion, phenolic compounds contributed not only to antioxidant activities, but also to the inhibitory effect against LDL oxidation. Chrysanthemi Flos, Crataegi Fructus, and H. sabdariffa, with lower doubling-time concentrations, could be potent phytochemical agents to reduce LDL oxidation and prevent the progression of atherosclerosis. PMID:26151009

  12. Low-density Lipoprotein Improves Motility and Plasma Membrane Integrity of Cryopreserved Canine Epididymal Spermatozoa.

    PubMed

    Prapaiwan, N; Tharasanit, T; Punjachaipornpol, S; Yamtang, D; Roongsitthichai, A; Moonarmart, W; Kaeoket, K; Manee-In, S

    2016-05-01

    Cryopreservation of caudal epididymal spermatozoa is an effective technique to conserve genetic potentials of superior dogs when it is not possible to collect ejaculated spermatozoa. Although hen egg yolk is commonly supplemented into the semen extender, active substances within the egg yolk which protect sperm against cryoinjury remain to be discovered. Among its compositions, low-density lipoprotein (LDL) has been reported to have a cryoprotective property for sperm cryopreservation. However, the effects of LDL on dog epididymal spermatozoa during cryopreservation have not yet been investigated. This study aimed to investigate the effects of LDL on epididymal spermatozoa quality following cryopreservation and thawing. After routine castration of 12 dogs, caudal epididymides from individuals were separated from the testes and cut into a few pieces in a Tris-buffer. Spermatozoa recovered from each sample were examined at once for sperm quality and divided into six groups of extender: no LDL, 20% egg yolk, 4%, 8%, 16%, and 24% LDL, before cryopreservation. The sperm aliquots were then equilibrated and conventionally frozen. After thawing, sperm motility, morphology, plasma membrane integrity, and acrosome integrity were evaluated. The results revealed that 4% LDL and 20% egg yolk yielded significantly higher sperm motility (57.69% and 52.69%, respectively, p<0.05) than other LDLs. In addition, 4% LDL yielded the significantly highest plasma membrane integrity (70.54%, p<0.05). In conclusion, the supplementation of 4% LDL in Tris-glucose extender could be applied for cryopreservation of canine epididymal spermatozoa. PMID:26954170

  13. High Density Lipoproteins for the Systemic Delivery of short interfering RNA

    PubMed Central

    McMahon, Kaylin M.; Thaxton, C. Shad

    2014-01-01

    Introduction RNA interference (RNAi) is a powerful mechanism for gene silencing with the potential to greatly impact the development of new therapies for many human diseases. Short interfering RNAs (siRNAs) may be the ideal molecules for therapeutic RNAi. However, therapeutic siRNAs face significant challenges that must be overcome prior to widespread clinical use. Many efforts have been made to overcome the hurdles associated with systemic administration of siRNA; however, current approaches are still limited. As such, there is an urgent need to develop new strategies for siRNA delivery that have the potential to impact a broad spectrum of systemic diseases. Areas covered This review focuses on the promise of siRNA therapies and highlights current siRNA delivery methods. With an eye toward new strategies, this review first introduces high density lipoproteins (HDL) and their natural functions, and then transitions into how HDLs may provide significant opportunities as next generation siRNA delivery vehicles. Importantly, this review describes how synthetic HDLs leverage the natural ability of HDL to stabilize and deliver siRNAs. Expert Opinion HDLs are natural nanoparticles that are critical to understanding the systemic delivery of therapeutic nucleic acids, like siRNA. Methods to synthesize biomimetic HDLs are being explored and data demonstrate that this type of delivery vehicle may be highly beneficial for targeted and efficacious systemic delivery of siRNAs. PMID:24313310

  14. Uptake of low density lipoproteins by the hamster lung. Interactions with capillary endothelium

    SciTech Connect

    Nistor, A.; Simionescu, M.

    1986-12-01

    The mechanism by which the circulating low density lipoproteins (LDL) contribute to the lung surfactant cholesterol was investigated by perfusing the hamster lung in situ with LDL either radiolabeled or coupled to gold, or both. Part of (/sup 125/I)-LDL and (/sup 3/H)-cholesterol LDL were taken up by a specific process which was time- and concentration-dependent and reached saturation within 20 to 30 min of perfusion. Competition experiments and removal of receptor-bound LDL by heparin suggested that about 50% of LDL uptake is receptor-independent. Experiments using double labeled LDL showed a preferential uptake of /sup 3/H-cholesterol versus /sup 125/I by the lung both in situ and in vivo. LDL-gold particles (LDL-Au), recirculated through the isolated lung, bound to the endothelial luminal plasma membrane and to features potentially involved in receptor-mediated endocytosis (coated pits, coated vesicles, lysosomelike structures) and in transcytosis (plasmalemmal vesicles). The results suggest that LDL uptake by the lung takes place by both receptor-mediated and receptor-independent mechanisms. Cholesterol may be in part transferred to the lung without the apoprotein moiety; the alveolar capillary endothelium appears to be the first monitor of this complex process.

  15. Purification and Characterization of a Bovine Acetyl Low Density Lipoprotein Receptor

    NASA Astrophysics Data System (ADS)

    Kodama, Tatsuhiko; Reddy, Pranhitha; Kishimoto, Chiharu; Krieger, Monty

    1988-12-01

    The acetyl low density lipoprotein (LDL) receptor is expressed on macrophages and some endothelial cells and mediates macrophage--foam cell formation in culture. A 220-kDa acetyl LDL binding protein was partially purified from bovine liver membranes and was used to make a specific monoclonal antibody. The 220-kDa protein immunoprecipitated by this antibody retained binding activity, and the antibody was used to detect this protein in cells lining bovine liver sinusoids and on the surface of cultured bovine alveolar macrophages. In the human monocytic cell line THP-1, the expression of both acetyl LDL receptor activity and a 220-kDa acetyl LDL binding protein were dramatically induced in parallel after differentiation to a macrophage-like state induced by phorbol ester. The ligand specificity, tissue and cell-type specificity, and coinduction data indicated that this 220-kDa cell-surface binding protein is probably a receptor that mediates acetyl LDL endocytosis. The 220-kDa protein, which was purified 238,000-fold from bovine lung membranes to near homogeneity using monoclonal antibody affinity chromatography, is a trimer of 77-kDa subunits that contain asparagine-linked carbohydrate chains.

  16. Equilibrium and kinetic studies of the interactions of a porphyrin with low-density lipoproteins.

    PubMed Central

    Bonneau, Stéphanie; Vever-Bizet, Christine; Morlière, Patrice; Mazière, Jean-Claude; Brault, Daniel

    2002-01-01

    Low-density lipoproteins (LDL) play a key role in the delivery of photosensitizers to tumor cells in photodynamic therapy. The interaction of deuteroporphyrin, an amphiphilic porphyrin, with LDL is examined at equilibrium and the kinetics of association/dissociation are determined by stopped-flow. Changes in apoprotein and porphyrin fluorescence suggest two classes of bound porphyrins. The first class, characterized by tryptophan fluorescence quenching, involves four well-defined sites. The affinity constant per site is 8.75 x 10(7) M(-1) (cumulative affinity 3.5 x 10(8) M(-1)). The second class corresponds to the incorporation of up to 50 molecules into the outer lipidic layer of LDL with an affinity constant of 2 x 10(8) M(-1). Stopped-flow experiments involving direct LDL porphyrin mixing or porphyrin transfer from preloaded LDL to albumin provide kinetic characterization of the two classes. The rate constants for dissociation of the first and second classes are 5.8 and 15 s(-1); the association rate constants are 5 x 10(8) M(-1) s(-1) per site and 3 x 10(9) M(-1) s(-1), respectively. Both fluorescence and kinetic analysis indicate that the first class involves regions at the boundary between lipids and the apoprotein. The kinetics of porphyrin-LDL interactions indicates that changes in the distribution of photosensitizers among various carriers could be very sensitive to the specific tumor microenvironment. PMID:12496113

  17. Oxidized low-density lipoproteins induced inflammatory process during atherogenesis with aging

    NASA Astrophysics Data System (ADS)

    Larbi, Anis; Khalil, Abdelouahed; Douziech, Nadine; Guérard, Karl-Philippe; Fülöp, Tamàs

    2005-02-01

    Atherosclerosis is a chronic disease developing through decades with two life-threatening complications: myocardial infarction and stroke. Oxidized low-density lipoproteins (oxLDL) produced by oxidative modifications of LDL in the subendothelial space have been demonstrated to be critically involved in atherogenesis through their intensive pro-inflammatory activity. Recently, it was shown that oxLDL have an apoptosis-inducing effect in T cells depending on time and degree of oxidation. The goal of the current study is to elucidate the molecular mechanisms underlying the apoptotic-inducing effects of oxLDL on T lymphocytes. T cells of young and elderly subjects were incubated for various periods of time with LDL oxidized to various degrees. The proliferation, the apoptosis, the MAPK ERK1/2 activation and the expression of the Bcl-2 protein family members were measured upon different LDL treatments. Thus, more the LDL are oxidized more they induce apoptosis and this effect is highly accentuated with aging. The oxLDL decrease the activation of the surviving molecule ERK1/2 and modulate the ratio of Bax/Bcl-2 towards a pro-apoptotic profile, which is also accentuated with aging. These results partly explain why atherosclerosis is increasing with aging concomitantly to its complications.

  18. Effect of insulin on low-density-lipoprotein metabolism in human lymphocytes in vitro.

    PubMed Central

    Suresh, S; Warty, V; Virji, M; Sanghvi, A

    1986-01-01

    The metabolism of low-density lipoproteins (LDL) in vitro in the presence of insulin was studied in freshly isolated human peripheral-blood lymphocytes. Insulin appeared to decrease the binding affinity of 125I-LDL to its cell-surface receptor, without any change in apparent Vmax or in the number of LDL receptors. As a consequence, the absolute amounts of 125I-LDL internalized and degraded were lower in the presence of insulin than in its abscence, although the fraction of internalized 125I-LDL degraded in either instance was quite similar. 3-Hydroxy-3-methylglutaryl-CoA reductase activity, and hence cholesterol synthesis, were stimulated by insulin. This effect of insulin was independent of the inhibitory effect of LDL on cholesterol synthesis. At the same time, acid cholesterol esterase and acyl-CoA: cholesterol O-acetyltransferase activities were lower in cells incubated with insulin than in controls. The net effect of these metabolic alterations seems to be that cells accumulate greater quantities of free and esterified cholesterol when treated with insulin. PMID:3513764

  19. How Do PCSK9 Inhibitors Stack Up to Statins for Low-Density Lipoprotein Cholesterol Control?

    PubMed

    Zimmerman, Marj P

    2015-11-01

    Despite advances in the approach toward treating hypercholesterolemia and widespread access to statin medications, not all people are able to reach target low-density lipoprotein cholesterol (LDL-C) levels to reduce their cardiovascular risk. Some of the reasons include the inability to tolerate statin therapy, LDL-C levels that remain high even in the presence of statin therapy, and a familial disorder that is characterized by extremely high levels of LDL-C. A new therapeutic class, proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, represents a novel and promising approach to reducing LDL-C levels using a mechanism at the LDL receptor level. The recent approval of the first 2 PCSK9 inhibitors and the anticipated approval of the third agent in this class within approximately 1 year may provide clinicians powerful new weapons to lower LDL-C levels in patients who are not satisfactorily managed with statins. However, the results of long-term studies of the ability of these new medications to influence cardiovascular outcomes will not be known for several years. PMID:26702335

  20. How Do PCSK9 Inhibitors Stack Up to Statins for Low-Density Lipoprotein Cholesterol Control?

    PubMed Central

    Zimmerman, Marj P.

    2015-01-01

    Despite advances in the approach toward treating hypercholesterolemia and widespread access to statin medications, not all people are able to reach target low-density lipoprotein cholesterol (LDL-C) levels to reduce their cardiovascular risk. Some of the reasons include the inability to tolerate statin therapy, LDL-C levels that remain high even in the presence of statin therapy, and a familial disorder that is characterized by extremely high levels of LDL-C. A new therapeutic class, proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, represents a novel and promising approach to reducing LDL-C levels using a mechanism at the LDL receptor level. The recent approval of the first 2 PCSK9 inhibitors and the anticipated approval of the third agent in this class within approximately 1 year may provide clinicians powerful new weapons to lower LDL-C levels in patients who are not satisfactorily managed with statins. However, the results of long-term studies of the ability of these new medications to influence cardiovascular outcomes will not be known for several years. PMID:26702335

  1. Clinical efficacy and safety of evolocumab for low-density lipoprotein cholesterol reduction

    PubMed Central

    Henry, Courtney A; Lyon, Ronald A; Ling, Hua

    2016-01-01

    Multiple categories of medications have been developed to manage lipid profiles and reduce the risk of cardiovascular events in patients with heart disease. However, currently marketed medications have not solved the problems associated with preventing and treating cardiovascular diseases completely. A substantial population of patients cannot take advantage of statin therapy due to statin intolerance, heart failure, or kidney hemodialysis, suggesting a need for additional effective agents to reduce low-density lipoprotein cholesterol (LDL-C) levels. Proprotein convertase subtilisin/kexin type 9 (PCSK9) was discovered in 2003 and subsequently emerged as a novel target for LDL-C-lowering therapy. Evolocumab is a fully human monoclonal immunoglobulin G2 (IgG2) directed against human PCSK9. By inactivating PCSK9, evolocumab upregulates LDL receptors causing increased catabolism of LDL-C and the consequent reduction of LDL-C levels in blood. Overall, evolocumab has had notable efficacy, with LDL-C reduction ranging from 53% to 75% in monotherapy and combination therapies, and is associated with minor adverse effects. However, studies regarding the ability of evolocumab to reduce mortality as well as long-term safety concerns are limited. The fact that the drug was introduced at a cost much higher than the existing medications and shows a low incremental mortality benefit suggests that many payers will consider evolocumab to have an unfavorable cost–benefit ratio. PMID:27143910

  2. Bile acids reduce endocytosis of high-density lipoprotein (HDL) in HepG2 cells.

    PubMed

    Röhrl, Clemens; Eigner, Karin; Fruhwürth, Stefanie; Stangl, Herbert

    2014-01-01

    High-density lipoprotein (HDL) transports lipids to hepatic cells and the majority of HDL-associated cholesterol is destined for biliary excretion. Cholesterol is excreted into the bile directly or after conversion to bile acids, which are also present in the plasma as they are effectively reabsorbed through the enterohepatic cycle. Here, we provide evidence that bile acids affect HDL endocytosis. Using fluorescent and radiolabeled HDL, we show that HDL endocytosis was reduced in the presence of high concentrations of taurocholate, a natural non-cell-permeable bile acid, in human hepatic HepG2 and HuH7 cells. In contrast, selective cholesteryl-ester (CE) uptake was increased. Taurocholate exerted these effects extracellularly and independently of HDL modification, cell membrane perturbation or blocking of endocytic trafficking. Instead, this reduction of endocytosis and increase in selective uptake was dependent on SR-BI. In addition, cell-permeable bile acids reduced HDL endocytosis by farnesoid X receptor (FXR) activation: chenodeoxycholate and the non-steroidal FXR agonist GW4064 reduced HDL endocytosis, whereas selective CE uptake was unaltered. Reduced HDL endocytosis by FXR activation was independent of SR-BI and was likely mediated by impaired expression of the scavenger receptor cluster of differentiation 36 (CD36). Taken together we have shown that bile acids reduce HDL endocytosis by transcriptional and non-transcriptional mechanisms. Further, we suggest that HDL endocytosis and selective lipid uptake are not necessarily tightly linked to each other. PMID:25010412

  3. Secreted Progranulin Is a Homodimer and Is Not a Component of High Density Lipoproteins (HDL)*

    PubMed Central

    Nguyen, Andrew D.; Nguyen, Thi A.; Cenik, Basar; Yu, Gang; Herz, Joachim; Walther, Tobias C.; Davidson, W. Sean; Farese, Robert V.

    2013-01-01

    Progranulin is a secreted glycoprotein, and the GRN gene is mutated in some cases of frontotemporal dementia. Progranulin has also been implicated in cell growth, wound healing, inflammation, and cancer. We investigated the molecular nature of secreted progranulin and provide evidence that progranulin exists as a homodimer. Although recombinant progranulin has a molecular mass of ∼85 kDa by SDS-PAGE, it elutes in fractions corresponding to ∼170–180 kDa by gel-filtration chromatography. Additionally, recombinant progranulin can be intermolecularly cross-linked, yielding a complex corresponding to a dimer (∼180 kDa), and progranulins containing different epitope tags physically interact. In plasma, progranulin similarly forms complexes of ∼180–190 kDa. Although progranulin partially co-fractionated with high density lipoproteins (HDL) by gel-filtration chromatography, we found no evidence that progranulin in mouse or human plasma is a component of HDL either by ultracentrifugation or by lipid binding assays. We conclude that circulating progranulin exists as a dimer and is not likely a component of HDL. PMID:23364791

  4. Protein components of low-density lipoproteins purified from hen egg yolk.

    PubMed

    Jolivet, P; Boulard, C; Beaumal, V; Chardot, T; Anton, M

    2006-06-14

    To identify apoproteins present in purified low-density lipoproteins from hen egg yolk in relation with their emulsifying properties, they have been separated by SDS-PAGE. We identified two different proteins by liquid chromatography-tandem mass spectrometry analysis of the peptides obtained by the trypsin digestion of protein gel bands. Apovitellenin I was identified as a monomer and a dimer. Its amino acid sequence was totally confirmed, and molecular mass determination by liquid chromatography-mass spectrometry showed that it did not present post-translational modifications but only a slight heterogeneity by the loss of one or two amino acids at the C-terminal part of the protein. Apolipoprotein B was identified into seven bands corresponding to fragments resulting of a processing of the hen blood apo-B protein. The identity of the fragments was determined by the observation of the sequence coverage by trypsin peptides and the sequence alignment with homologous human blood apolipoprotein B-100. PMID:16756376

  5. High-density lipoprotein therapy inhibits Porphyromonas gingivalis-induced abdominal aortic aneurysm progression.

    PubMed

    Delbosc, Sandrine; Rouer, Martin; Alsac, Jean-Marc; Louedec, Liliane; Al Shoukr, Faisal; Rouzet, François; Michel, Jean-Baptiste; Meilhac, Olivier

    2016-04-01

    Clinical and experimental studies have highlighted the potential implication of periondontal bacteria contamination in the pathogenesis of abdominal aortic aneurysms (AAA). In addition to their role in reverse cholesterol transport, high-density lipoproteins (HDLs) display multiple functions, including anti-inflammatory and lipopolysaccharide scavenging properties. Low plasma levels of HDL-cholesterol have been reported in AAA patients. We tested the effect of a HDL therapy in Sprague-Dawley rat model of AAA, obtained by intraluminal elastase infusion followed by repeated injections of Porphyromonas gingivalis (Pg). HDLs, isolated by ultracentrifugation of plasma from healthy human volunteers, were co-injected intravenously (10 mg/kg) with Pg (1.107 Colony Forming Unit) one, eight and 15 days after elastase perfusion. Rats were sacrificed one week after the last injection. Our results show that Pg injections promote the formation of a persistent neutrophil-rich thrombus associated with increased aortic diameter in this AAA model. HDLs significantly reduced the increased AAA diameter induced by Pg. Histology showed the onset of a healing process in the Pg/HDL group. HDL injections also reduced neutrophil activation in Pg-injected rats associated with decreased cytokine levels in conditioned media and plasma. Scintigraphic analysis showed an intense uptake of 99mTc-HDL by the AAA suggesting that HDLs could exert their beneficial effect by acting directly on the thrombus components. HDL supplementation may therefore constitute a new therapeutic tool for AAA treatment. PMID:26676721

  6. High-density lipoproteins reduce palmitate-induced cardiomyocyte apoptosis in an AMPK-dependent manner.

    PubMed

    Spillmann, Frank; Trimpert, Christiane; Peng, Jun; Eckerle, Lars G; Staudt, Alexander; Warstat, Katrin; Felix, Stephan B; Pieske, Burkert; Tschpe, Carsten; Van Linthout, Sophie

    2015-10-16

    Palmitate has been implicated in the induction of cardiomyocyte apoptosis via reducing the activity of 5' AMP-activated protein kinase (AMPK). We sought to evaluate whether high-density lipoproteins (HDLs), known for their cardioprotective features and their potential to increase AMPK activity, can reduce palmitate-induced cardiomyocyte apoptosis and whether this effect is AMPK-dependent. Therefore, cardiomyocytes were isolated from adult Wistar rat hearts via perfusion on a Langendorff-apparatus and cultured in free fatty acid-free BSA control medium or 0.5mM palmitate medium in the presence or absence of HDL (5?g protein/ml) with or without 0.1?M of the AMPK-inhibitor compound S for the analysis of Annexin V/propidium, genes involved in apoptosis and fatty acid oxidation, and cardiomyocyte contractility. We found that HDLs decreased palmitate-induced cardiomyocyte apoptosis as indicated by a reduction in Annexin V-positive cardiomyocytes and an increase in Bcl-2 versus Bax ratio. Concomitantly, HDLs increased the palmitate-impaired expression of genes involved in fatty acid oxidation. Furthermore, HDLs improved the palmitate-impaired cardiomyocyte contractility. All effects were mediated in an AMPK-dependent manner, concluding that HDLs reduce palmitate-induced cardiomyocyte apoptosis, resulting in improved cardiomyocyte contractility through a mechanism involving AMPK. PMID:26362182

  7. Influence of long-chain polyunsaturated fatty acids on oxidation of low density lipoprotein.

    PubMed

    Wander, R C; Du, S H; Thomas, D R

    1998-08-01

    Enrichment of low density lipoprotein (LDL) with long-chain fatty acids, such as eicosapentaenoic acid (EPA; 20:5 n-3) and docosahexaenoic acid (DHA; 22:6 n-3) found in fish oil, is thought to increase its oxidative susceptibility although such an increase has not been clearly demonstrated. The purpose of this study was to determine the composition and fatty acid concentration of LDL obtained from postmenopausal women given a supplement of fish oil and relate these values to its oxidative susceptibility. Fish oil supplementation significantly increased LDL concentration of EPA (P = 0.0001) and DHA (P = 0.0001) and decreased that of linoleic acid P = 0.006). The concentration of free cholesterol, cholesterol ester, phospholipids and protein was unchanged while triglyceride concentration increased 8% (P = 0.02). Cu2+-mediated oxidation resulted in a shorter lag time, slower oxidation rate and similar concentrations of conjugated dienes of EPA/DHA-enriched LDL than EPA/DHA-unenriched LDL. Stepwise multiple regression indicated that the primary predictor of oxidative susceptibility of LDL was linoleic acid, even after enrichment with EPA and DHA. The oxidation rate of EPA/DHA-unenriched LDL correlated with the cholesteryl ester concentration (P = 0.003) while that of EPA/DHA-enriched correlated with the concentration of phospholipids (P = 0.03). These data suggest that EPA/DHA-enriched LDL have decreased oxidative susceptibility and that surface lipids may mediate its rate of oxidation. PMID:9774178

  8. Fluvastatin reduces modification of low-density lipoprotein in hyperlipidemic rabbit loaded with oxidative stress.

    PubMed

    Yamaguchi, Yu; Matsuno, Sachiko; Kagota, Satomi; Haginaka, Jun; Kunitomo, Masaru

    2002-02-01

    The in vivo antioxidant effect of fluvastain, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, was investigated using Watanabe heritable hyperlipidemic (WHHL) rabbits subjected to nicotine-free cigarette smoke extracts as oxidative stress. Fluvastatin was given orally at doses of 10 and 30 mg/kg per day for 5 months. The cigarette smoke extracts were prepared by bubbling the gas phase of smoke into phosphate-buffered saline and was injected daily into the rabbit ear vein. The rabbits chronically treated with the cigarette smoke extracts showed an increase in plasma lipid peroxide levels, estimated as thiobarbituric acid-reactive substances. Oxidative modification of plasma low-density lipoprotein (LDL) was assessed by anion-exchange high-performance liquid chromatographic analysis, LDL susceptibility to oxidation, LDL incorporation into macrophages and thiobarbituric acid-reactive substances levels in LDL. Treatment with fluvastatin significantly reduced these effects induced by the cigarette smoke extracts in a dose-related manner and exerted a cholesterol-lowering effect. At the end of the experiment, the cigarette smoke extracts caused accumulation of cholesteryl ester in the thoracic aorta, while fluvastatin significantly prevented this accumulation. These results indicate that fluvastatin can exert an antioxidant effect in vivo, with a strong effect on oxidative stress such as smoking, a major risk factor of atherosclerosis. PMID:11834252

  9. N-acetylcysteine inhibits in vivo oxidation of native low-density lipoprotein

    PubMed Central

    Cui, Yuqi; Narasimhulu, Chandrakala A.; Liu, Lingjuan; Zhang, Qingbin; Liu, Patrick Z.; Li, Xin; Xiao, Yuan; Zhang, Jia; Hao, Hong; Xie, Xiaoyun; He, Guanglong; Cui, Lianqun; Parthasarathy, Sampath; Liu, Zhenguo

    2015-01-01

    Low-density lipoprotein (LDL) is non-atherogenic, while oxidized LDL (ox-LDL) is critical to atherosclerosis. N-acetylcysteine (NAC) has anti-atherosclerotic effect with largely unknown mechanisms. The present study aimed to determine if NAC could attenuate in vivo LDL oxidation and inhibit atherosclerosis. A single dose of human native LDL was injected intravenously into male C57BL/6 mice with and without NAC treatment. Serum human ox-LDL was detected 30 min after injection, reached the peak in 3 hours, and became undetectable in 12 hours. NAC treatment significantly reduced serum ox-LDL level without detectable serum ox-LDL 6 hours after LDL injection. No difference in ox-LDL clearance was observed in NAC-treated animals. NAC treatment also significantly decreased serum ox-LDL level in patients with coronary artery diseases and hyperlipidemia without effect on LDL level. Intracellular and extracellular reactive oxidative species (ROS) production was significantly increased in the animals treated with native LDL, or ox-LDL and in hyperlipidemic LDL receptor knockout (LDLR−/−) mice that was effectively prevented with NAC treatment. NAC also significantly reduced atherosclerotic plaque formation in hyperlipidemic LDLR−/− mice. NAC attenuated in vivo oxidation of native LDL and ROS formation from ox-LDL associated with decreased atherosclerotic plaque formation in hyperlipidemia. PMID:26536834

  10. Nucleolin Acts as a Scavenger Receptor for Acetylated Low-Density Lipoprotein on Macrophages.

    PubMed

    Miki, Yuichi; Tachibana, Yoshihiro; Ohminato, Yukari; Fujiwara, Yasuyuki

    2015-01-01

    Although macrophage phagocytoses modified low-density lipoprotein (LDL), excessive accumulation of modified LDL induces macrophage foam cell formation, which is a feature of atherosclerotic plaque. Thus, the identification of scavenger receptor for modified LDL will provide better understanding of an atherosclerotic event. We recently showed that nucleolin expressed on macrophages acts as a scavenger receptor for various endogenous discarded products. Here, we investigated whether or not nucleolin is involved in the uptake of acetylated LDL (AcLDL). In contrast to normal LDL, AcLDL directly bound to immobilized nucleolin. AcLDL exhibited a higher affinity for macrophages than normal LDL. This binding of AcLDL was inhibited by anti-nucleolin antibody and antineoplastic guanine-rich oligonucleotide (AGRO), a nucleolin-specific oligonucleotide aptamer. In addition, AcLDL exhibited a higher affinity for HEK cells transfected with nucleolin than those without. Further, intracellular accumulation of AcLDL was also inhibited by anti-nucleolin antibody. The results of this study suggest that nucleolin expressed on macrophages is a receptor for AcLDL. PMID:26328500

  11. Low density lipoprotein aged in plasma forms clusters resembling subendothelial droplets: aggregation via surface sites.

    PubMed

    De Spirito, Marco; Brunelli, Roberto; Mei, Giampiero; Bertani, Francesca R; Ciasca, Gabriele; Greco, Giulia; Papi, Massimiliano; Arcovito, Giuseppe; Ursini, Fulvio; Parasassi, Tiziana

    2006-06-01

    In early phases of atherogenesis, droplets and vesicles accumulate in the subendothelial extracellular space of arterial intima. There is much evidence to suggest that these droplets, ranging between 100 and 400 nm, derive from modified low-density lipoprotein (LDL). In investigations of the formation mechanism of these droplets, LDL fusion was previously induced in vitro by proteolysis, lipolysis, oxidation, and vigorous shaking, but all treatments failed to reproduce the size distribution range of in vivo droplets, mostly resulting, instead, in particles with a diameter intermediate between that of one and two LDL. Our approach was meant to mimic LDL aging in plasma. LDL isolated from plasma that was incubated overnight at 37 degrees C is slightly modified in the secondary structure of its protein component and is primed to form very large aggregates according to a reaction-limited mechanism. This mechanism requires interactions between selected surface sites, whereas massive fusion is ruled out. In the frame of the general theory for colloids, the aggregation of LDL aged in plasma fulfills all the requirements of the reaction-limited mechanism, encompassing 1), exponential growth; 2), fractal structure, with the dimension of elementary constituent still consistent with a single LDL; and 3), extreme polydispersity of aggregates, with shape and dimension very close to that of droplets observed in vivo. PMID:16533854

  12. Low Density Lipoprotein Aged in Plasma Forms Clusters Resembling Subendothelial Droplets: Aggregation via Surface Sites

    PubMed Central

    De Spirito, Marco; Brunelli, Roberto; Mei, Giampiero; Bertani, Francesca R.; Ciasca, Gabriele; Greco, Giulia; Papi, Massimiliano; Arcovito, Giuseppe; Ursini, Fulvio; Parasassi, Tiziana

    2006-01-01

    In early phases of atherogenesis, droplets and vesicles accumulate in the subendothelial extracellular space of arterial intima. There is much evidence to suggest that these droplets, ranging between 100 and 400 nm, derive from modified low-density lipoprotein (LDL). In investigations of the formation mechanism of these droplets, LDL fusion was previously induced in vitro by proteolysis, lipolysis, oxidation, and vigorous shaking, but all treatments failed to reproduce the size distribution range of in vivo droplets, mostly resulting, instead, in particles with a diameter intermediate between that of one and two LDL. Our approach was meant to mimic LDL aging in plasma. LDL isolated from plasma that was incubated overnight at 37°C is slightly modified in the secondary structure of its protein component and is primed to form very large aggregates according to a reaction-limited mechanism. This mechanism requires interactions between selected surface sites, whereas massive fusion is ruled out. In the frame of the general theory for colloids, the aggregation of LDL aged in plasma fulfills all the requirements of the reaction-limited mechanism, encompassing 1), exponential growth; 2), fractal structure, with the dimension of elementary constituent still consistent with a single LDL; and 3), extreme polydispersity of aggregates, with shape and dimension very close to that of droplets observed in vivo. PMID:16533854

  13. Modifications of low-density lipoprotein induced by arterial proteoglycans and chondroitin-6-sulfate.

    PubMed

    Camejo, G; Hurt, E; Wiklund, O; Rosengren, B; López, F; Bondjers, G

    1991-04-15

    Association of low-density lipoproteins (LDL) with arterial chondroitin sulfate proteoglycans (CSPG) appears to contribute to their deposition in the extracellular intimal compartment and to its internalization by macrophages. CSPG and LDL interact by ionic bridges with formation of soluble and insoluble complexes. We studied the alterations on LDL structure induced by its association with arterial CSPG and other glycosaminoglycans (GAG). In soluble complexes, at low and at physiological ionic strength, arterial CSPG and sulfated GAG modify the kinetics of apoB-100 proteolysis by trypsin. However, less marked alterations in the peptide patterns were observed with proteinase V8 and almost none with thermolysin. This is indirect evidence that the presence of CSPG and GAG modified the exposure of polar regions of apoB-100 in LDL. Competitive binding experiments with agarose-bound heparin and soluble GAG also suggest that after formation of insoluble complexes with arterial CSPG and resolubilization the exposure of Lys, Arg-rich segments of apoB-100 is increased. Results from differential scanning calorimetry and differential thermal spectrophotometry showed that the CSPG and GAG-induced modifications reduced the thermal stability of the surface and core in LDL. If present in vivo, the structural alterations of polar segments of the LDL protein moiety may influence the outcome of its interaction with the arterial mesenchyma. PMID:2018799

  14. Investigation of low density lipoprotein subfractions as a coronary risk factor in normotriglyceridaemic men.

    PubMed

    Rajman, I; Kendall, M J; Cramb, R; Holder, R L; Salih, M; Gammage, M D

    1996-09-01

    There is an increasing interest in low density lipoprotein (LDL) subfractions since some of them are associated with a higher risk for coronary artery disease (CAD). Small LDL particles are particularly atherogenic and more of those are produced in hypertriglyceridaemia. However, high triglyceride concentrations are not the only explanation for the predominance of small LDL particles and other influences, including genetic factors, are also responsible for LDL particle size. We investigated LDL subfraction profiles in two groups: 46 men with and 21 men without CAD proven angiographically. For the separation of LDL subfractions, we used continuous disc polyacrylamide gel electrophoresis (PAGE) that is rapid and easier to perform than the other methods usually used which, although more precise in terms of measuring particle diameter, are much more demanding of time and equipment. The described method is suitable for routine use in assessing large numbers of patients. All studied men had triglyceride concentrations below 2.3 mmol/l. LDL scores were calculated on the basis of all LDL subfractions present in a particular profile; the higher the score, the greater the proportion of small LDL particles. LDL cholesterol (P < 0.05) and LDL score (P < 0.001) were the only significant discriminators between two groups. LDL score was significantly correlated with CAD, even after adjusting for triglyceride and HDL cholesterol concentrations and it was the best discriminant factor for the presence of CAD. PMID:8842354

  15. Association of atherogenic low-density lipoprotein subfractions with carotid atherosclerosis.

    PubMed

    Landray, M J; Sagar, G; Muskin, J; Murray, S; Holder, R L; Lip, G Y

    1998-05-01

    Patients with carotid atherosclerosis are at increased risk of both stroke and ischaemic heart disease. Low-density lipoprotein (LDL) is a heterogeneous group of particles, with small, dense particles being more atherogenic. We studied 79 patients (51 men, mean +/- SD age 62.4 +/- 11.7 years) referred for Doppler ultrasound assessment of the carotid arteries. Evidence of carotid atherosclerosis, defined as the presence of atherosclerotic plaque, stenosis or occlusion in one or more of the six carotid artery segments examined, was found in 44 patients (56%). LDL subfractions were analysed by disc polyacrylamide gel electrophoresis with prior ultracentrifugation of serum to remove chylomicrons. This method produces a LDL score; the higher the score, the greater the proportion of the more atherogenic LDL subfractions. Mean LDL score was significantly higher in diseased patients (mean +/- SD, 1.56 +/- 0.61) than the normal group (1.26 +/- 0.65) (t = 2.12, p = 0.037). There was no significant association between LDL score and severity of carotid artery stenosis. Age (adjusted odds ratio 1.09, 95% CI 1.03-1.15) and smoking history (2.09, 95% CI 1.10-3.98) predicted carotid atherosclerosis in logistic regression analysis, with LDL score achieving borderline significance (2.20, 95% CI 0.91-5.29). Small, dense LDL subfractions are associated with carotid atherosclerosis and may be a modifiable risk factor for stroke as well as ischaemic heart disease. PMID:9709468

  16. A Statin-Loaded Reconstituted High-Density Lipoprotein Nanoparticle Inhibits Atherosclerotic Plaque Inflammation

    PubMed Central

    Duivenvoorden, Raphaël; Tang, Jun; Cormode, David P.; Mieszawska, Aneta J.; Izquierdo-Garcia, David; Ozcan, Canturk; Otten, Maarten J.; Zaidi, Neeha; Lobatto, Mark E.; van Rijs, Sarian M.; Priem, Bram; Kuan, Emma L.; Martel, Catherine; Hewing, Bernd; Sager, Hendrik; Nahrendorf, Matthias; Randolph, Gwendalyn J.; Stroes, Erik S.G.; Fuster, Valentin; Fisher, Edward A.; Fayad, Zahi A.; Mulder, Willem J.M.

    2014-01-01

    Inflammation is a key feature of atherosclerosis and a target for therapy. Statins have potent anti-inflammatory properties but these cannot be fully exploited with oral statin therapy due to low systemic bioavailability. Here we present an injectable reconstituted high-density lipoprotein (rHDL) nanoparticle carrier vehicle that delivers statins to atherosclerotic plaques. We demonstrate the anti-inflammatory effect of statin-rHDL in vitro and show this effect is mediated through inhibition of the mevalonate pathway. We also apply statin-rHDL nanoparticles in vivo in an apolipoprotein E-knockout mouse model of atherosclerosis and show they accumulate in atherosclerotic lesions where they directly affect plaque macrophages. Finally we demonstrate that a three-month low-dose statin-rHDL treatment regimen inhibits plaque inflammation progression, while a one-week high-dose regimen markedly decreases inflammation in advanced atherosclerotic plaques. Statin-rHDL represents a novel potent atherosclerosis nanotherapy that directly affects plaque inflammation. PMID:24445279

  17. Atherogenic concentrations of low-density lipoprotein enhance endothelial cell generation of epoxyeicosatrienoic acid products.

    PubMed Central

    Pritchard, K. A.; Wong, P. Y.; Stemerman, M. B.

    1990-01-01

    To investigate the effects of protracted low-density lipoprotein (LDL) exposure on endothelial cell (EC) epoxyeicosatrienoic acid (EET) generation, human umbilical vein ECs were incubated in atherogenic concentrations of LDL (240 mg cholesterol per deciliter) (LDL-EC). After 4 days' incubation with LDL, EC were stimulated with human thrombin in the presence of 1-[14C]-arachidonic acid. Substantially more EET products were generated by LDL-ECs than by cells not exposed to high levels of LDL (C-EC). Thrombin stimulation caused LDL-EC to produce five- to eightfold more in 14,15-EET, 11,12-EET, 8,9-EET, and 5,6-EET, with 14,15-EET as the major product. This is the first demonstration, to date, that EETs can be induced in EC. Metapyrone (SKF-525A) markedly inhibited EC EET generation, indicating a role for the cytochrome P-450 enzyme system in human EC arachidonic acid metabolism. One EET product, 14,15-EET, has been found to be chemotactic and to promote adhesion of U937 cells, a human monocytic lymphoma cell line, to EC. Thus, protracted exposure to atherogenic LDL concentrations increases the generation of chemotactic and adhesion factors (ie, 14,15-EET) after thrombin stimulation, possibly through the cytochrome P-450 enzyme system. PMID:2356865

  18. Intercorrelations among plasma high density lipoprotein, obesity and triglycerides in a normal population

    SciTech Connect

    Albrink, M.J.; Krauss, R.M.; Lindgren, F.T.; von der Groeben, J.; Pan, S.; Wood, P.D.

    1980-01-01

    The interrelationships among fatness measures, plasma triglycerides and high density lipoproteins (HDL) were examined in 131 normal adult subjects: 38 men aged 27 to 46, 50 men aged 47 to 66, 29 women aged 27 to 46 and 24 women aged 47 to 66. None of the women were taking estrogens or oral contraceptive medication. The HDL concentration was subdivided into HDL/sub 2b/, HDL/sub 2a/ and HDL by a computerized fitting of the total schileren pattern to reference schlieren patterns. Anthropometric measures employed included skinfolds at 3 sites, 2 weight/height indices and 2 girth measurements. A high correlation was found among the various fatness measures. These measures were negatively correlated with total HDL, reflecting the negative correlation between fatness measures and HDL/sub 2/ (as the sum of HDL/sub 2a/ and /sub 2b/). Fatness measures showed no relationship to HDL/sub 3/. There was also an inverse correlation between triglyceride concentration and HDL/sub 2/. No particular fatness measure was better than any other for demonstrating the inverse correlation with HDL but multiple correlations using all of the measures of obesity improved the correlations. Partial correlations controlling for fatness did not reduce any of the significnt correlations between triglycerides and HDL/sub 2/ to insignificance. The weak correlation between fatness and triglycerides was reduced to insigifnicance when controlled for HDL/sub 2/.

  19. In vitro oxidative footprinting provides insight into apolipoprotein B-100 structure in low density lipoprotein

    PubMed Central

    Chakraborty, Sourav; Cai, Yang; Tarr, Matthew A.

    2015-01-01

    Low density lipoprotein (LDL) is a major cholesterol carrier in human blood. Oxidations of apolipoprotein B-100 (apo B-100, LDL protein) could be pro-atherogenic and play critical roles in early stages of plaque formation in the arterial wall. The structure of apo B-100 is still poorly understood, partially due to its size (550 KDa, 4563 amino acids). To gain an insight into LDL structure, we mapped the regions of apo B-100 in human LDL which were prone to oxidation using peroxynitrite and hypochlorite as probes. In this study, LDL was incubated with various concentrations of peroxynitrite and sodium hypochlorite in bicarbonate buffer. The LDL protein apo B-100 was delipidated, denatured, alkylated and subjected to tryptic digestion. Tryptic peptides were analyzed employing liquid chromatography – tandem mass spectrometry (LC-MS/MS). Database search was performed against the apo B-100 database (P04114) using “SEQUEST” algorithm to identify peroxynitrite and hypochlorite mediated oxidations markers nitrotyrosine, nitrotryptophan, hydroxy-tryptophan and 3-chlorotyrosine. Several site specific oxidations were identified in apo B-100 after treatment of intact LDL particles with the oxidants. We hypothesize that these regions could be accessible to oxidant and critical for early events in atherosclerotic plaque deposition. PMID:25176030

  20. Low-density Lipoprotein Improves Motility and Plasma Membrane Integrity of Cryopreserved Canine Epididymal Spermatozoa

    PubMed Central

    Prapaiwan, N.; Tharasanit, T.; Punjachaipornpol, S.; Yamtang, D.; Roongsitthichai, A.; Moonarmart, W.; Kaeoket, K.; Manee-in, S.

    2016-01-01

    Cryopreservation of caudal epididymal spermatozoa is an effective technique to conserve genetic potentials of superior dogs when it is not possible to collect ejaculated spermatozoa. Although hen egg yolk is commonly supplemented into the semen extender, active substances within the egg yolk which protect sperm against cryoinjury remain to be discovered. Among its compositions, low-density lipoprotein (LDL) has been reported to have a cryoprotective property for sperm cryopreservation. However, the effects of LDL on dog epididymal spermatozoa during cryopreservation have not yet been investigated. This study aimed to investigate the effects of LDL on epididymal spermatozoa quality following cryopreservation and thawing. After routine castration of 12 dogs, caudal epididymides from individuals were separated from the testes and cut into a few pieces in a Tris-buffer. Spermatozoa recovered from each sample were examined at once for sperm quality and divided into six groups of extender: no LDL, 20% egg yolk, 4%, 8%, 16%, and 24% LDL, before cryopreservation. The sperm aliquots were then equilibrated and conventionally frozen. After thawing, sperm motility, morphology, plasma membrane integrity, and acrosome integrity were evaluated. The results revealed that 4% LDL and 20% egg yolk yielded significantly higher sperm motility (57.69% and 52.69%, respectively, p<0.05) than other LDLs. In addition, 4% LDL yielded the significantly highest plasma membrane integrity (70.54%, p<0.05). In conclusion, the supplementation of 4% LDL in Tris-glucose extender could be applied for cryopreservation of canine epididymal spermatozoa. PMID:26954170

  1. Network-Based Analysis on Orthogonal Separation of Human Plasma Uncovers Distinct High Density Lipoprotein Complexes.

    PubMed

    Li, Hailong; Gordon, Scott M; Zhu, Xiaoting; Deng, Jingyuan; Swertfeger, Debi K; Davidson, W Sean; Lu, L Jason

    2015-08-01

    High density lipoprotein (HDL) particles are blood-borne complexes whose plasma levels have been associated with protection from cardiovascular disease (CVD). Recent studies have demonstrated the existence of distinct HDL subspecies; however, these have been difficult to isolate and characterize biochemically. Here, we present the first report that employs a network-based approach to systematically infer HDL subspecies. Healthy human plasma was separated into 58 fractions using our previously published three orthogonal chromatography techniques. Similar local migration patterns among HDL proteins were captured with a novel similarity score, and individual comigration networks were constructed for each fraction. By employing a graph mining algorithm, we identified 183 overlapped cliques, among which 38 were further selected as candidate HDL subparticles. Each of these 38 subparticles had at least two literature supports. In addition, GO function enrichment analysis showed that they were enriched with fundamental biological and CVD protective functions. Furthermore, gene knockout experiments in mouse model supported the validity of these subparticles related to three apolipoproteins. Finally, analysis of an apoA-I deficient human patient's plasma provided additional support for apoA-I related complexes. Further biochemical characterization of these putative subspecies may facilitate the mechanistic research of CVD and guide targeted therapeutics aimed at its mitigation. PMID:26057100

  2. The Effect of Acetaminophen on Oxidative Modification of Low-Density Lipoproteins in Hypercholesterolemic Rabbits

    PubMed Central

    Özsoy, Meral Baş; Pabuçcuoğlu, Aysun

    2007-01-01

    Oxidative modification of low-density lipoproteins (LDL) contributes to the pathology of atherosclerosis. Antioxidants may protect LDL against oxidative modification. Acetaminophen, a widely used analgesic and antipyretic agent, has significant antioxidant properties. However, there is little evidence to suggest that acetaminophen acts as an antioxidant for LDL oxidation in vivo. In this study, we investigated the in vivo effect of acetaminophen on LDL oxidation in hypercholesterolemic rabbits. The oxidative modification of LDL was identified by conjugated dienes and thiobarbituric acid-reactive substances (TBARS). In the cholesterol group which rabbits were fed a diet contained 1% g cholesterol for 8 weeks, TBARS contents and conjugated diene levels in the plasma and isolated LDL samples significantly increased compared with the control rabbits (p<0.05). However, in the cholesterol + acetaminophen group, the TBARS contents and conjugated diene levels were significantly lower than that of the cholesterol group (p<0.05). The results from in vitro studies also demonstrated that the LDL isolated from serum was oxidized by Cu++ ions and this oxidation reduced in the presence of acetaminophen. The reduced oxidative modification of LDL by acetaminophen may be of therapeutic value in preventing the development and progression of atherosclerosis. PMID:18392104

  3. Chitosan-modified carbon nanotubes-based platform for low-density lipoprotein detection.

    PubMed

    Ali, Md Azahar; Singh, Nawab; Srivastava, Saurabh; Agrawal, Ved V; John, Renu; Onoda, M; Malhotra, Bansi D

    2014-10-01

    We have fabricated an immunosensor based on carbon nanotubes and chitosan (CNT-CH) composite for detection of low density lipoprotein (LDL) molecules via electrochemical impedance technique. The CNT-CH composite deposited on indium tin oxide (ITO)-coated glass electrode has been used to covalently interact with anti-apolipoprotein B (antibody: AAB) via a co-entrapment method. The biofunctionalization of AAB on carboxylated CNT-CH surface has been confirmed by Fourier transform infrared spectroscopic and electron microscopic studies. The covalent functionalization of antibody on transducer surface reveals higher stability and reproducibility of the fabricated immunosensor. Electrochemical properties of the AAB/CNT-CH/ITO electrode have been investigated using cyclic voltammetric and impedimetric techniques. The impedimetric response of the AAB/CNT-CH/ITO immunoelectrode shows a high sensitivity of 0.953 Ω/(mg/dL)/cm(2) in a detection range of 0-120 mg/dL and low detection limit of 12.5 mg/dL with a regression coefficient of 0.996. The observed low value of association constant (0.34 M(-1)s(-1)) indicates high affinity of AAB/CNT-CH/ITO immunoelectrode towards LDL molecules. This fabricated immunosensor allows quantitative estimation of LDL concentration with distinguishable variation in the impedance signal. PMID:25201210

  4. Anti-Atherogenic Mechanisms of High Density Lipoprotein: Effects on Myeloid Cells

    PubMed Central

    Murphy, Andrew J.; Westerterp, Marit; Yvan-Charvet, Laurent; Tall, Alan R.

    2011-01-01

    In some settings increasing high density lipoprotein (HDL) levels has been associated with a reduction in experimental atherosclerosis. This has been most clearly seen in apolipoprotein A-I (apoA-I) transgenic mice or in animals infused with HDL or its apolipoproteins. A major mechanism by which these treatments are thought to delay progression or cause regression of atherosclerosis is by promoting efflux of cholesterol from macrophage foam cells. In addition, HDL has been described as having anti-inflammatory and other beneficial effects. Some recent research has linked anti-inflammatory effects to cholesterol efflux pathways but likely multiple mechanisms are involved. Macrophage cholesterol efflux may have a role in facilitating emigration of macrophages from lesions during regression. While macrophages can mediate cholesterol efflux by several pathways, studies in knockout mice or cells point to the importance of active efflux mediated by ATP binding cassette transporter (ABC) A1 and G1. In addition to traditional roles in macrophages, these transporters have been implicated in the control of hematopoietic stem cell proliferation, monocytosis and neutrophilia, as well as activation of monocytes and neutrophils. Thus, HDL and cholesterol efflux pathways may have important anti-atherogenic effects at all stages of the myeloid cell/monocyte/dendritic cell/macrophage lifecycle. PMID:21864714

  5. Fast determination of virgin olive oil phenolic metabolites in human high-density lipoproteins.

    PubMed

    Fernández-Ávila, C; Montes, R; Castellote, A I; Chisaguano, A M; Fitó, M; Covas, M I; Muñoz-Aguallo, D; Nyyssönen, K; Zunft, H J; López-Sabater, M C

    2015-07-01

    In recent years it has been confirmed that the consumption of olive oil prevents the oxidation of biomolecules owing to its monounsaturated fatty acids (MUFA) and phenolic content. The main objective of the study was to develop an ultra-high-performance liquid chromatography (UHPLC) tandem mass spectrometry (MS/MS) method for the determination of phenolic compounds in human high-density lipoprotein (HDL) samples. At the same time, the influence of olive oil consumption on the phenolic metabolite levels was evaluated in a European population. The participants were 51 healthy men, aged 20-60. They were randomized to two consecutive intervention periods with the administration of raw olive oil with low and high polyphenolic content. The UHPLC-MS/MS analytical method has been validated for hydroxytyrosol and homovanillic acid in terms of linearity (r(2)  = 0.99 and 1.00), repeatability (5.7 and 6.5%) reproducibility (6.2 and 7%), recovery (98 to 97%), limits of detection (1.7 to 1.8 ppb) and quantification (5.8 and 6.3 ppb).The levels of the studied metabolites increased significantly after high polyphenolic content virgin olive oil ingestion (p <0.05) compared with lowpolyphenolic content olive oil. Virgin olive oil consumption increases the levels of phenolic metabolites in HDL and thus provides human HDL with more efficient antioxidant protection. PMID:25425119

  6. Does Weight Loss Cause the Exercise-induced Increase in Plasma High Density Lipoproteins?

    PubMed Central

    Williams, Paul T.; Wood, Peter D.; Krauss, Ronald M.; Haskell, William L.; Vranizan, Karen M.; Blair, Steven N.; Terry, Richard; Farquhar, John W.

    2010-01-01

    Studies showing an increase in plasma concentration of high density lipoprotein cholesterol (HDL-C) with moderate exercise have usually rejected the role of body weight change in the HDL-C raising process, ostensibly because the amount of weight lost has been negligible. To investigate HDL-C changes more thoroughly, we followed initially sedentary middle-aged men randomly assigned to either a moderate running (N= 36) or a sedentary control (N = 28) group for one year. Among runners, one-year changes in plasma HDL-C concentrations correlated strongly with their body weight changes (r = - 0.53, P < 0.001). Curve-fitting procedures and regression analysis suggested that processes associated with weight change produce much of the plasma HDL-C changes induced by moderate exercise and that changes in HDL-C concentration predominantly reflect changes in the reputedly anti-atherogenic HDL2 sub-component. Further, the interaction between weight change and plasma HDL-C concentration was significantly different (P < 0.001) in exercisers and controls suggesting that the metabolic consequences of exercise-induced weight change are different from the consequences of weight change in the sedentary state. PMID:6870998

  7. Involvement of second messengers in regulation of the low-density lipoprotein receptor gene

    SciTech Connect

    Auwerx, J.H. . ECHEM Labs.); Chait, A.; Wolfbauer, G.; Deeb, S.S. . Dept. of Medicine)

    1989-06-01

    Transcription of the low-density lipoprotein receptor (LDL-R) gene in the human monocytic leukemic cell line THP-1 and in the human hepatocarcinoma cell line Hep-G2 is regulated by second messengers of the diacylglycerol-protein kinase C (DAG-PKC), inositol 1,4,5-triphosphate-Ca/sup 2+/, and cyclic AMP pathways. Exogeneous phospholipase C (which releases DAG and inositol 1,4,5-triphosphate), PKC activators (phorbol esters and DAG), Ca/sup 2+/ ionophores, and a cyclic AMP analog all transiently induced accumulation of LDL-R mRNA. The effects of these three signal-transducing pathways were to a large extend additive. Furthermore, PKC stimulation effected an increase in LDL binding, which suggested that the increase in LDL-R mRNA resulted in an increase in functional cell surface receptor activity. These results suggest that uptake of cholesterol by these cells is under control of both intracellular cholesterol levels and external signals.

  8. High Density Lipoprotein: A Novel Target for Anti-Restenosis Therapy

    PubMed Central

    Yin, Kai; Agrawal, Devendra K

    2014-01-01

    Restenosis is an integral pathological process central to the recurrent vessel narrowing after interventional procedures. Although the mechanisms for restenosis are diverse in different pathological conditions, endothelial dysfunction, inflammation, vascular smooth muscle cell (SMC) proliferation and myofibroblasts transition have been thought to play crucial role in the development of restenosis. Indeed, there is an inverse relationship between high-density lipoprotein (HDL) levels and risk for coronary heart disease (CHD). However, relatively studies on the direct assessment of HDL effect on restenosis are limited. In addition to involvement in the cholesterol reverse transport (RCT), many vascular protective effects of HDL, including protection of endothelium, anti-inflammation, anti-thrombus actions, inhibition of SMC proliferation, and regulation by adventitial effects may contribute to the inhibition of restenosis, though the exact relationships between HDL and restenosis remain to be elucidated. This review summarizes the vascular protective effects of HDL, emphasizing the potential role of HDL in intimal hyperplasia and vascular remodeling, which may provide novel prophylactic and therapeutic strategies for anti-restenosis. PMID:25043950

  9. Low-density lipoprotein particle number and risk for cardiovascular disease.

    PubMed

    Cromwell, William C; Otvos, James D

    2004-09-01

    The key role played by low-density lipoprotein (LDL) particles in the pathogenesis of coronary heart disease (CHD) is well accepted, as is the benefit of lowering LDL in high-risk patients. What remains controversial is whether we are using the best measure(s) of LDL to identify all individuals who would benefit from therapy. Many studies have shown that, at a given level of LDL cholesterol, individuals with predominantly small LDL particles (pattern B) experience greater CHD risk than those with larger-size LDL. However, it is not clear from this observation that small LDL particles are inherently more atherogenic than large ones because, at a given level of LDL cholesterol, individuals with small LDL have more LDL particles in total. The phenotype of small LDL particle size co-segregates with a cluster of metabolic factors, including elevated triglycerides and reduced HDL cholesterol, and in multivariate analyses has generally been found not to be independently associated with CHD risk. In contrast, LDL particle number measured by nuclear magnetic resonance has consistently been shown to be a strong, independent predictor of CHD. PMID:15296705

  10. Role of leptin on the expression of low density lipoprotein receptor

    PubMed Central

    Yadav, Naval Kishor; Arjuman, Albina; Chandra, Nimai C.

    2014-01-01

    Background & objectives: Leptin resistance oriented hyperleptinaemia is a common problem in obese subjects in association with hypercholesterolaemia. The most common target for hypercholesterolaemia is impaired low density lipoprotein receptor (LDLR). This study was carried out to investigate whether any alteration in LDLR expression could explain the occurrence of hypercholesterolaemia in the event of hyperleptinaemia. Methods: Expression of LDLR and SREBP2 (sterol regulatory element binding protein 2) were examined in HepG2 cells by RT-PCR and Western blotting. JAK2 inhibitor II was used to verify the effect of JAK-STAT (Janus Kinase-Signal Transducer and Activator of Transcription) pathway (common mediator for cytokine signaling). Co-localization of LDLR and insulin receptor (IR) was examined by confocal microscopy. Results: Leptin was found to reduce the expression of LDLR and its transcription factor SREBP2. On the other hand, a weak signal for stimulation of LDLR by leptin was noted to be mediated by JAK2 pathway. But the joint effect of the two signaling pathways kept LDLR only in depressed mode in presence of leptin. Confocal microscopy showed that LDLR made an intensively co-localized complex with insulin receptor in presence of leptin. Interpretation & conclusions: Our results show that though leptin stimulates LDLR expression very weakly through JAK-STAT signaling pathway, it mainly imposes inhibition on LDLR expression by inhibiting transcription factor SREBP2. The inter-association between LDLR and IR may be a reason to render LDLR functionally inactive in presence of leptin. PMID:25488447

  11. Aggregation and fusion of low-density lipoproteins in vivo and in vitro

    PubMed Central

    Gursky, Olga

    2014-01-01

    Low-density lipoproteins (LDLs, also known as ‘bad cholesterol’) are the major carriers of circulating cholesterol and the main causative risk factor of atherosclerosis. Plasma LDLs are 20- to 25-nm nanoparticles containing a core of cholesterol esters surrounded by a phospholipid monolayer and a single copy of apolipoprotein B (550 kDa). An early sign of atherosclerosis is the accumulation of LDL-derived lipid droplets in the arterial wall. According to the widely accepted ‘response-to-retention hypothesis’, LDL binding to the extracellular matrix proteoglycans in the arterial intima induces hydrolytic and oxidative modifications that promote LDL aggregation and fusion. This enhances LDL uptake by the arterial macrophages and triggers a cascade of pathogenic responses that culminate in the development of atherosclerotic lesions. Hence, LDL aggregation, fusion, and lipid droplet formation are important early steps in atherogenesis. In vitro, a variety of enzymatic and nonenzymatic modifications of LDL can induce these reactions and thereby provide useful models for their detailed analysis. Here, we summarize current knowledge of the in vivo and in vitro modifications of LDLs leading to their aggregation, fusion, and lipid droplet formation; outline the techniques used to study these reactions; and propose a molecular mechanism that underlies these pro-atherogenic processes. Such knowledge is essential in identifying endogenous and exogenous factors that can promote or prevent LDL aggregation and fusion in vivo and to help establish new potential therapeutic targets to decelerate or even block these pathogenic reactions. PMID:25197325

  12. Assessing the functional properties of high-density lipoproteins: an emerging concept in cardiovascular research.

    PubMed

    Triolo, Michela; Annema, Wijtske; Dullaart, Robin P F; Tietge, Uwe J F

    2013-06-01

    Although plasma concentrations of high-density lipoprotein (HDL) cholesterol correlate inversely with the incidence of atherosclerotic cardiovascular disease, results from recent epidemiological, genetic and pharmacological intervention studies resulted in a shift of concept. Rather than HDL cholesterol mass levels, the functionality of HDL particles is increasingly regarded as potentially clinically important. This review provides an overview of four key functional properties of HDL, namely cholesterol efflux and reverse cholesterol transport; antioxidative activities; anti-inflammatory activities; and the ability of HDL to increase vascular nitric oxide production resulting in vasorelaxation. Currently available assays are put into context with different HDL isolation procedures yielding compositional heterogeneity of the particle. Gathered knowledge on the impact of different disease states on HDL function is discussed together with potential underlying causative factors modulating HDL functionalities. In addition, a perspective is provided regarding how a better understanding of the determinants of (dys)functional HDL might impact clinical practice and the future design of rational and specific therapeutic approaches targeting atherosclerotic cardiovascular disease. PMID:23734809

  13. Nuclear imaging analysis of human low-density lipoprotein biodistribution in rabbits and monkeys

    SciTech Connect

    Hay, R.V.; Fleming, R.M.; Ryan, J.W.; Williams, K.A.; Stark, V.J.; Lathrop, K.A.; Harper, P.V. )

    1991-06-01

    We have evaluated the biodistribution of human low-density lipoprotein (LDL) radiolabeled with 99mTc or with {sup 123}I-tyramine cellobiose in rabbits and in rhesus monkeys. Biodistribution was assessed after intravenous injection of radiolabeled LDL by quantitative analysis of scintigrams, counting of excreta, and counting of tissues at necropsy. Both rabbits and monkeys showed lower renal uptake ({sup 123}I:99mTc {approximately} 1:3, as regional percent injected activity corrected for physical decay) and excretion (1:2 to 1:4), but higher hepatic (1.5:1 to 2:1) and cardiac (1.7:1 to 4:1) uptake of {sup 123}I than of 99mTc. Adrenals were visualized in normolipemic animals with {sup 123}I-tyramine cellobiose-LDL but not with 99mTc-LDL. Hyperlipemic animals showed increased cardiac (up to six-fold) and decreased hepatic activity (by 50%-60%) of both radionuclides. We conclude that {sup 123}I-tyramine cellobiose-LDL is better suited than 99mTc-LDL for dynamic studies of LDL metabolism in vivo.

  14. Fluorescence correlation spectroscopy to measure the metabolism of high-density lipoprotein

    NASA Astrophysics Data System (ADS)

    Deitrick, Russell; Gibson, Emily; Razzaghi, Hamid

    2009-10-01

    High-density lipoprotein (HDL), referred to as the ``good cholesterol'', carries free cholesterol to the liver to be filtered from the bloodstream and is important to our understanding of atherosclerosis. HDL is metabolized in part by the enzyme Endothelial Lipase (EL). With this project we will use fluorescence correlation spectroscopy (FCS) to study the metabolism of HDL by EL comparing wild type with different genetic mutations. FCS is an advanced microscopy technique in which we record fluctuations in the fluorescence of dye-labeled molecules (in this case, HDL labeled with Nile Red) as they freely diffuse through a small focal volume. This data can be analyzed mathematically using the cross-correlation function, from which we can ultimately ascertain much information. In our case, we are interested in the diffusion coefficient which, via the Stokes-Einstein relation for a sphere, we can determine the size of HDL as it undergoes the process of metabolism. Preliminary results seem to indicate that the metabolic process occurs very quickly, that the final size of HDL depends primarily on the concentration of EL, and that the wild and mutant variants of EL have a similar effectiveness. In following experiments, we hope to investigate these relationships further.

  15. Macrophage uptake of low-density lipoprotein modified by 4-hydroxynonenal. An ultrastructural study

    SciTech Connect

    Hoff, H.F.; Cole, T.B. )

    1991-02-01

    We have documented the ultrastructural characteristics of the uptake and processing by mouse peritoneal macrophages (MPM) of low-density lipoprotein (LDL) modified with 4-hydroxynonenal (HNE), an intermediate of lipid peroxidation. This was performed as part of a larger biochemical study assessing the role of LDL oxidation in lipid loading of macrophages during atherogenesis. Gold-labeled LDL that was modified with HNE leading to particle aggregation represented the morphologic probe used. When incubated with MPM, the probe became associated with short segments of cell membrane, probably derived from blebs or from lysed cells. At 37 degrees C there was a time-dependent increase in uptake by MPM, and at 4 hours the increase paralleled the degradation by MPM of 125I-labeled HNE-LDL-cAu. Clathrin-coated pits on the cell surface were consistently associated with probe. Uptake of probe appeared to occur via phagocytosis, because pseudopods frequently surrounded probe, and cytochalasin D quantitatively prevented probe uptake. A time-dependent increase was found in the number of gold particles per unit area within vacuoles, some of which were secondary lysosomes, based on acid phosphatase-positive staining. Thus, HNE-induced aggregation of LDL during oxidation, binding of aggregates to clathrin-coated pits on MPM, and subsequent phagocytosis may represent one of the ways lipid-laden foam cells are formed in vivo.

  16. Metabolism of low-density lipoprotein free cholesterol by human plasma lecithin-cholesterol acyltransferase

    SciTech Connect

    Fielding, P.E.; Miida, Takashi; Fielding, C.J. )

    1991-09-03

    The metabolism of cholesterol derived from ({sup 3}H) cholesterol-labeled low-density lipoprotein (LDL) was determined in human blood plasma. LDL-derived free cholesterol first appeared in large {alpha}-migrating HDL (HDL{sub 2}) and was then transferred to small {alpha}-HDL (HDL{sub 3}) for esterification. The major part of such esters was retained within HDL of increasing size in the course of lecithin-cholesterol acyltransferase (LCAT) activity; the balance was recovered in LDL. Transfer of preformed cholesteryl esters within HDL contributed little to the labeled cholesteryl ester accumulating HDL{sub 2}. When cholesterol for esterification was derived instead from cell membranes, a significantly smaller proportion of this cholesteryl ester was subsequently recovered in LDL. These data suggest compartmentation of cholesteryl esters within plasma that have been formed from cell membrane or LDL free cholesterol, and the role for HDL{sub 2} as a relatively unreactive sink for LCAT-derived cholesteryl esters.

  17. Antioxidant effects of 14 Chinese traditional medicinal herbs against human low-density lipoprotein oxidation.

    PubMed

    Lin, Hsin-Hung; Charles, Albert Linton; Hsieh, Chang-Wei; Lee, Ya-Chi; Ciou, Jhih-Ying

    2015-01-01

    The relationship between the antioxidant activities and inhibitory effect of 14 Chinese medicinal herbs against oxidized low-density lipoprotein (LDL) formation was evaluated. Prolongation of the lag phase of LDL oxidation depended on the concentration of the herbs. The concentration of each herb that was able to prolong the lag time by about two-fold was calculated and expressed as doubling-time concentration. The lower the doubling-time concentration, the stronger the inhibitory effect exhibited toward LDL oxidation. Among them, Chrysanthemi Flos (Chrysanthemum morifolium ramat; gān jú huā), Crataegi Fructus (Crataegus pinnatifida Bge. var. major N.E.Br.; shān zhā), and Roselle (Hibiscus sabdariffa Linn.; luò shén) showed significant inhibitory effects. Correlation coefficients between doubling-time concentration and radical-scavenging activities were high; the total phenolic content was also high. In conclusion, phenolic compounds contributed not only to antioxidant activities, but also to the inhibitory effect against LDL oxidation. Chrysanthemi Flos, Crataegi Fructus, and H. sabdariffa, with lower doubling-time concentrations, could be potent phytochemical agents to reduce LDL oxidation and prevent the progression of atherosclerosis. PMID:26151009

  18. Sphingomyelin in High-Density Lipoproteins: Structural Role and Biological Function

    PubMed Central

    Martínez-Beamonte, Roberto; Lou-Bonafonte, Jose M.; Martínez-Gracia, María V.; Osada, Jesús

    2013-01-01

    High-density lipoprotein (HDL) levels are an inverse risk factor for cardiovascular diseases, and sphingomyelin (SM) is the second most abundant phospholipid component and the major sphingolipid in HDL. Considering the marked presence of SM, the present review has focused on the current knowledge about this phospholipid by addressing its variable distribution among HDL lipoparticles, how they acquire this phospholipid, and the important role that SM plays in regulating their fluidity and cholesterol efflux from different cells. In addition, plasma enzymes involved in HDL metabolism such as lecithin–cholesterol acyltransferase or phospholipid transfer protein are inhibited by HDL SM content. Likewise, HDL SM levels are influenced by dietary maneuvers (source of protein or fat), drugs (statins or diuretics) and modified in diseases such as diabetes, renal failure or Niemann–Pick disease. Furthermore, increased levels of HDL SM have been shown to be an inverse risk factor for coronary heart disease. The complexity of SM species, described using new lipidomic methodologies, and their distribution in different HDL particles under many experimental conditions are promising avenues for further research in the future. PMID:23571495

  19. A statin-loaded reconstituted high-density lipoprotein nanoparticle inhibits atherosclerotic plaque inflammation

    NASA Astrophysics Data System (ADS)

    Duivenvoorden, Raphaël; Tang, Jun; Cormode, David P.; Mieszawska, Aneta J.; Izquierdo-Garcia, David; Ozcan, Canturk; Otten, Maarten J.; Zaidi, Neeha; Lobatto, Mark E.; van Rijs, Sarian M.; Priem, Bram; Kuan, Emma L.; Martel, Catherine; Hewing, Bernd; Sager, Hendrik; Nahrendorf, Matthias; Randolph, Gwendalyn J.; Stroes, Erik S. G.; Fuster, Valentin; Fisher, Edward A.; Fayad, Zahi A.; Mulder, Willem J. M.

    2014-01-01

    Inflammation is a key feature of atherosclerosis and a target for therapy. Statins have potent anti-inflammatory properties but these cannot be fully exploited with oral statin therapy due to low systemic bioavailability. Here we present an injectable reconstituted high-density lipoprotein (rHDL) nanoparticle carrier vehicle that delivers statins to atherosclerotic plaques. We demonstrate the anti-inflammatory effect of statin-rHDL in vitro and show that this effect is mediated through the inhibition of the mevalonate pathway. We also apply statin-rHDL nanoparticles in vivo in an apolipoprotein E-knockout mouse model of atherosclerosis and show that they accumulate in atherosclerotic lesions in which they directly affect plaque macrophages. Finally, we demonstrate that a 3-month low-dose statin-rHDL treatment regimen inhibits plaque inflammation progression, while a 1-week high-dose regimen markedly decreases inflammation in advanced atherosclerotic plaques. Statin-rHDL represents a novel potent atherosclerosis nanotherapy that directly affects plaque inflammation.

  20. ATM protects against oxidative stress induced by oxidized low-density lipoprotein

    PubMed Central

    Semlitsch, Michaela; Shackelford, Rodney E.; Zirkl, Sandra; Sattler, Wolfgang; Malle, Ernst

    2011-01-01

    Chronic oxidative stress is involved in the pathogenesis of multiple inflammatory diseases, including cardiovascular disease and atherosclerosis. The rare autosomal recessive disorder Ataxia-telangiectasia (A-T) is characterized by progressive cerebellar ataxia secondary to Purkinje cell death, immunodeficiency, and increased cancer incidence. ATM, the protein mutated in A-T, plays a key role in cellular DNA-damage responses. A-T cells show poor cellular anti-oxidant defences and increased oxidant sensitivity compared to normal cells, and ATM functions, in part, as an oxidative stress sensor. The oxidation of low-density lipoprotein (oxLDL) and its uptake by macrophages is an initiating step in the development of atherosclerosis. We demonstrate that oxLDL activates ATM and downstream p21 expression in normal fibroblasts and endothelial cells. In ATM-deficient fibroblasts oxLDL induces DNA double-strand breaks, micronuclei formation and causes chromosome breaks. Furthermore, oxLDL decreases cell viability and inhibits colony formation in A-T fibroblasts more effectively as compared to normal controls. Formation of oxLDL-induced reactive oxygen species is significantly higher in A-T, than normal fibroblasts. Last, pre-treatment of cells with ammonium pyrrolidine dithiocarbamate, a potent antioxidant and inhibitor of transcription factor nuclear factor ?B, reduces oxLDL-induced reactive oxygen species formation. Our data indicates that ATM functions in the defence against oxLDL-mediated cytotoxicity. PMID:21669554

  1. The myeloperoxidase product hypochlorous acid generates irreversible high-density lipoprotein receptor inhibitors

    PubMed Central

    Binder, Veronika; Ljubojevic, Senka; Haybaeck, Johannes; Holzer, Michael; El-Gamal, Dalia; Schicho, Rudolf; Pieske, Burkert; Heinemann, Akos; Marsche, Gunther

    2014-01-01

    Objective Elevated levels of advanced oxidation protein products (AOPPs) have been described in several chronic inflammatory diseases, like chronic renal insufficiency, rheumatoid arthritis and atherosclerosis. Recent findings revealed that AOPPs are inhibitors of the major high-density lipoprotein (HDL) receptor, scavenger receptor class B, type 1 (SR-BI). Here we investigated what oxidation induced structural alterations convert plasma albumin into an HDL-receptor inhibitor. Approach and Results Exposure of albumin to the physiological oxidant, hypochlorous acid, generated high affinity SR-BI ligands. Protection of albumin lysine-residues prior exposure to hypochlorous acid as well as regeneration of N-chloramines after oxidation of albumin completely prevented binding of oxidized albumin to SR-BI, indicating that modification of albumin lysine-residues is required to generate SR-BI ligands. Of particular interest, N-chloramines within oxidized albumin promoted irreversible binding to SR-BI, resulting in permanent receptor blockade. We observed that the SR-BI inhibitory activity of albumin isolated from chronic kidney disease patients correlated with the content of the myeloperoxidase-specific oxidation product 3-chlorotyrosine and was associated with alterations in the composition of HDL. Conclusion Given that several potential atheroprotective activities of HDL are mediated by SR-BI, the present results raise the possibility that oxidized plasma albumin, through permanent SR-BI blockade, contributes to the pathophysiology of cardiovascular disease. PMID:23493288

  2. Anti-psoriatic treatment extends beyond the skin: Recovering of high-density lipoprotein function

    PubMed Central

    Marsche, Gunther; Holzer, Michael; Wolf, Peter

    2016-01-01

    Epidemiological and clinical studies have shown a consistent association of psoriasis with systemic metabolic disorders including an increased prevalence of diabetes, obesity and cardiovascular disease. Psoriasis is accompanied by systemic inflammation and low levels of high-density lipoprotein (HDL)-cholesterol. Recent studies provided clear evidence that psoriasis affects HDL composition and function. HDL isolated from psoriatic patients showed a significantly impaired capability to mobilize cholesterol from macrophages, a crucial step in reverse cholesterol transport and markedly lower paraoxonase activity, a protein that co-transports with HDL in serum with well-known anti-atherogenic properties. Of particular interest, successful anti-psoriatic therapy significantly improved HDL composition and function independently of serum HDL-cholesterol levels. These novel findings suggest that the conventional approaches of evaluating cardiovascular risk in psoriasis may be in need of refinement. As these data argue for a loss of beneficial activities of HDL in psoriatic patients, altered HDL functionality should be considered when evaluating the lipid status of patients. PMID:24980461

  3. Structure-based Design Targeted at LOX-1, a Receptor for Oxidized Low-Density Lipoprotein

    NASA Astrophysics Data System (ADS)

    Thakkar, Shraddha; Wang, Xianwei; Khaidakov, Magomed; Dai, Yao; Gokulan, Kuppan; Mehta, Jawahar L.; Varughese, Kottayil I.

    2015-11-01

    Atherosclerosis related cardiovascular diseases continue to be the primary cause of mortality in developed countries. The elevated level of low density lipoprotein (LDL) is generally considered to be the driver of atherosclerosis, but recent years have seen a shift in this perception in that the vascular plaque buildup is mainly caused by oxidized LDL (ox-LDL) rather than native-LDL. The scavenger receptor LOX-1 found in endothelial cells binds and internalizes ox-LDL which leads to the initiation of plaque formation in arteries. Using virtual screening techniques, we identified a few potential small molecule inhibitors of LOX-1 and tested their inhibitory potential using differential scanning fluorimetry and various cellular assays. Two of these molecules significantly reduced the uptake of ox-LDL by human endothelial cells, LOX-1 transcription and the activation of ERK1/2 and p38 MAPKs in human endothelial cells. In addition, these molecules suppressed ox-LDL-induced VCAM-1 expression and monocyte adhesion onto human endothelial cells demonstrating their therapeutic potential.

  4. Synthetic High-Density Lipoprotein-Like Nanoparticles as Cancer Therapy

    PubMed Central

    McMahon, Kaylin M.; Foit, Linda; Angeloni, Nicholas L.; Giles, Francis J.; Gordon, Leo I.; Thaxton, C. Shad

    2015-01-01

    High-density lipoproteins (HDL) are diverse natural nanoparticles that carry cholesterol and are best known for the role that they play in cardiovascular disease. However, due to their unique targeting capabilities, diverse molecular cargo, and natural functions beyond cholesterol transport, it is becoming increasingly appreciated that HDLs are critical to cancer development and progression. Accordingly, this chapter highlights ongoing research focused on the connections between HDL and cancer in order to design new drugs and targeted drug delivery vehicles. Research is focused on synthesizing biomimetic HDL-like nanoparticles (NP) that can be loaded with diverse therapeutic cargo (e.g. chemotherapies, nucleic acids, proteins) and specifically targeted to cancer cells. Beyond drug delivery, new data is emerging that HDL-like NPs may be therapeutically active in certain tumor types, for example B cell lymphoma. Overall, HDL-like NPs are becoming increasingly appreciated as targeted, biocompatible, and efficient therapies for cancer, and may soon become indispensable agents in the cancer therapeutic armamentarium. PMID:25895867

  5. Apolipoprotein E isoform-specific binding to the low-density lipoprotein receptor

    PubMed Central

    Yamamoto, Taichi; Choi, Hyung Won; Ryan, Robert O.

    2008-01-01

    Apolipoprotein E (apoE) is a ligand for members of the low-density lipoprotein receptor (LDLR) family and functions in plasma cholesterol homeostasis. A fluorescence-based assay has been employed in molecular studies of receptor-ligand interactions. Competition experiments revealed isoform specific differences in binding of lipid-associated apoE N terminal (NT) domain to a recombinant soluble LDLR (sLDLR). In a similar manner, lipid associated, but not lipid-free, full-length apoE3 showed binding activity to sLDLR. The molecular chaperone, Receptor Associated Protein, inhibited apoE3-NT-phospholipid complex binding to sLDLR. Kinetic studies of apoE3-NT-phospholipid complex interaction with sLDLR revealed time dependent effects of apoE-NT isoform binding to sLDLR. The results reveal a discerning method for study of the molecular basis of ligand interactions that likely influence receptor function in maintenance of whole body cholesterol homeostasis. PMID:17923100

  6. High-density lipoprotein is a potential growth factor for adrenocortical cells

    SciTech Connect

    Murao, Koji . E-mail: mkoji@kms.ac.jp; Imachi, Hitomi; Cao, Wenming; Yu, Xiao; Li, Junhua; Yoshida, Kazuya; Ahmed, Rania A.M.; Matsumoto, Kensuke; Nishiuchi, Takamasa; Ishida, Toshihiko; Wong, Norman C.W.

    2006-05-26

    The entry of cholesterol contained within high-density lipoprotein (HDL) into adrenocortical cells is mediated by a human homologue of SR-BI, CD36, and LIMPII Analogous-1 (CLA-1) and thus augmenting their growth. To address the role of CLA-1, we created a mutant mCLA that lacked the C-terminal tail. HDL CE selective uptake by cells carrying the mCLA-1 receptor was fully active and equivalent to those transfected with full-length CLA-1 (fCLA-1). Expression of mCLA inhibited the proliferation of an adrenocortical cell line and the incorporation of [{sup 3}H]thymidine into the cells. This effect was sensitive to wortmannin, an inhibitor of phosphoinositide 3-kinase (PI3K). Our transcriptional studies revealed that the inhibitory action of mCLA required the transcriptional factor AP-1 and the effect of HDL on AP-1 activation was also abrogated by wortmannin. These findings raise the possibility that the inhibitors of the effects of HDL may be of therapeutic value for adrenocortical tumor.

  7. Clinical efficacy and safety of evolocumab for low-density lipoprotein cholesterol reduction.

    PubMed

    Henry, Courtney A; Lyon, Ronald A; Ling, Hua

    2016-01-01

    Multiple categories of medications have been developed to manage lipid profiles and reduce the risk of cardiovascular events in patients with heart disease. However, currently marketed medications have not solved the problems associated with preventing and treating cardiovascular diseases completely. A substantial population of patients cannot take advantage of statin therapy due to statin intolerance, heart failure, or kidney hemodialysis, suggesting a need for additional effective agents to reduce low-density lipoprotein cholesterol (LDL-C) levels. Proprotein convertase subtilisin/kexin type 9 (PCSK9) was discovered in 2003 and subsequently emerged as a novel target for LDL-C-lowering therapy. Evolocumab is a fully human monoclonal immunoglobulin G2 (IgG2) directed against human PCSK9. By inactivating PCSK9, evolocumab upregulates LDL receptors causing increased catabolism of LDL-C and the consequent reduction of LDL-C levels in blood. Overall, evolocumab has had notable efficacy, with LDL-C reduction ranging from 53% to 75% in monotherapy and combination therapies, and is associated with minor adverse effects. However, studies regarding the ability of evolocumab to reduce mortality as well as long-term safety concerns are limited. The fact that the drug was introduced at a cost much higher than the existing medications and shows a low incremental mortality benefit suggests that many payers will consider evolocumab to have an unfavorable cost-benefit ratio. PMID:27143910

  8. High-density lipoprotein-mediated transcellular cholesterol transport in mouse aortic endothelial cells.

    PubMed

    Miao, LiXia; Okoro, Emmanuel U; Cao, ZhiJan; Yang, Hong; Motley-Johnson, Evangeline; Guo, Zhongmao

    2015-09-18

    Accumulation of unesterified cholesterol-rich lipid vesicles in the subendothelial space contributes to atherogenesis. Transport of cholesterol from the subendothelial intima back to the circulating blood inhibits atherosclerosis development; however, the mechanism for this process has not been fully defined. Using cultured mouse aortic endothelial cells (MAECs), we observed that unesterified cholesterol can be transported across the endothelial cell monolayer from the basolateral to the apical compartment. Administration of high-density lipoprotein (HDL) or apolipoprotein AI (apoAI) to the apical compartment enhanced transendothelial cholesterol transport in a concentration-dependent manner. Knockdown of ATP-binding cassette transporter G1 (ABCG1) or scavenger receptor class B type I (SR-B1), or inhibition of SR-B1 diminished HDL-induced transendothelial cholesterol transport; while knockdown of ABCA1 reduced apoAI-mediated cholesterol transport. HDL enhanced phosphorylation of phosphatidylinositol 3-kinase (PI3K) and Akt in MAECs. However, inhibition of PI3K or Akt did not reduce HDL-induced transendothelial cholesterol transport. These results suggest that HDL enhances transendothelial cholesterol transport by activation of a mechanism involving ABCA1, ABCG1 and SR-B1 but not involving PI3K and Akt. PMID:26255968

  9. Proteoglycan form of macrophage colony-stimulating factor binds low density lipoprotein.

    PubMed

    Suzu, S; Inaba, T; Yanai, N; Kawashima, T; Yamada, N; Oka, T; Machinami, R; Ohtsuki, T; Kimura, F; Kondo, S

    1994-10-01

    We recently isolated a proteoglycan form of macrophage colony-stimulating factor (PG-M-CSF) that carries a chondroitin sulfate glycosaminoglycan chain. Here, we examined the interaction of PG-M-CSF with low density lipoprotein (LDL). When LDL preincubated with PG-M-CSF was fractionated by molecular size sieving chromatography, it was eluted earlier than untreated LDL. When LDL was preincubated with chondroitin sulfate-free 85-kD M-CSF instead of PG-M-CSF, the elution profile of LDL remained unchanged, indicating specific interaction between PG-M-CSF and LDL. The level of PG-M-CSF binding in the wells of a plastic microtitration plate precoated with LDL was significant, this binding being completely abolished by pretreatment of PG-M-CSF with chondroitinase AC, which degrades chondroitin sulfate. The addition of exogenous chondroitin sulfate or apolipoprotein B inhibited the binding of PG-M-CSF to LDL in a dose-dependent manner, indicating that the interaction between PG-M-CSF and LDL was mediated by the binding of the chondroitin sulfate chain of PG-M-CSF to LDL apolipoprotein B. PG-M-CSF was also demonstrated in the arterial wall, and there were increased amounts of PG-M-CSF in atherosclerotic lesions. The in vitro interaction between PG-M-CSF and LDL thus appears to have physiological significance. PMID:7929840

  10. Mechanisms responsible for hepatic very low density lipoprotein-apoB100 overproduction in Otsuka Long-Evans Tokushima fatty rats

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Overproduction of hepatic very low-density lipoprotein (VLDL)1 particles is a major abnormality of lipoprotein dysregulation in type 2 diabetes (T2D). We sought to examine the mechanisms linking systemic/hepatic inflammation associated with insulin resistance and apolipoprotein (apo) B100-containing...

  11. Oxidized low-density lipoprotein as a biomarker of cardiovascular diseases.

    PubMed

    Trpkovic, Andreja; Resanovic, Ivana; Stanimirovic, Julijana; Radak, Djordje; Mousa, Shaker A; Cenic-Milosevic, Desanka; Jevremovic, Danimir; Isenovic, Esma R

    2015-01-01

    Atherosclerosis is a life-long illness that begins with risk factors, which in turn contribute to the development of subclinical disease, followed by the establishment of overt cardiovascular disease (CVD). Thrombotic-occlusive complications of atherosclerosis are among the most widespread and costly health problems. Oxidized low-density lipoprotein (OxLDL) plays an important role in atherogenesis by promoting an inflammatory environment and lipid deposition in the arterial wall. As cardiovascular events occur in individuals without common risk factors, there is a need for additional tools that may help in CVD risk assessment and management. The use of biomarkers has improved diagnostic, therapeutic and prognostic outcome in cardiovascular medicine. This review elaborates on the value of circulating OxLDL as a biomarker of CVD. Three enzyme-linked immunosorbent assays (4E6, DLH3 and E06) using murine monoclonal antibodies for determination of OxLDL blood levels have been developed. However, none of these assays are currently approved for routine clinical practice. We identified studies investigating OxLDL in CVD (measured by 4E6, DLH3 or E06 assay) by searching the PubMed database. Circulating OxLDL was found to be associated with all stages of atherosclerosis, from early atherogenesis to hypertension, coronary and peripheral arterial disease, acute coronary syndromes and ischemic cerebral infarction. The results of studies investigating the usefulness of OxLDL for CVD prediction were also summarized. Furthermore, OxLDL was found to be associated with pathologic conditions linked to CVD, including diabetes mellitus, obesity and metabolic syndrome (MetS). In addition, we have addressed the mechanisms by which OxLDL promotes atherogenesis, and the effects of antiatherogenic treatments on circulating OxLDL. Finally, we highlight the evidence suggesting that lipoprotein (a) [Lp(a)] is the preferential carrier of oxidized phospholipids (OxPL) in human plasma. A strong association between OxPL/apoB level (representing the content of OxPL on apolipoprotein B-100 particles, measured by E06 assay) and Lp(a) has been determined. PMID:25537066

  12. High-Density Lipoprotein Function in Exudative Age-Related Macular Degeneration

    PubMed Central

    Pertl, Laura; Kern, Sabine; Weger, Martin; Hausberger, Silke; Trieb, Markus; Gasser-Steiner, Vanessa; Haas, Anton; Scharnagl, Hubert; Heinemann, Akos; Marsche, Gunther

    2016-01-01

    Purpose High-density lipoproteins (HDL) have long been implicated in the pathogenesis of age-related macular degeneration (AMD). However, conflicting results have been reported with regard to the associations of AMD with HDL-cholesterol levels. The present study is the first to assess HDL composition and metrics of HDL function in patients with exudative AMD and control patients. Methods Blood samples were collected from 29 patients with exudative AMD and 26 age-matched control patients. Major HDL associated apolipoproteins were determined in apoB-depleted serum by immunoturbidimetry or ELISA, HDL-associated lipids were quantified enzymatically. To get an integrated measure of HDL quantity and quality, we assessed several metrics of HDL function, including cholesterol efflux capacity, anti-oxidative and anti-inflammatory activities using apoB-depleted serum from study participants. Results In our study, we observed that the HDL associated acute phase protein serum amyloid A (SAA) was significantly increased in AMD patients (p<0.01), whereas all other assessed apolipoproteins including ApoA-I, apoA-II, apoC-II, apoC-III and apoE as well as major HDL associated lipids were not altered. HDL efflux capacity, anti-oxidative capacity and arylesterase activity were not different in AMD patients when compared with the control group. The ability of apoB-depleted serum to inhibit monocyte NF-κB expression was significantly improved in AMD patients (mean difference (MD) -5.6, p<0.01). Moreover, lipoprotein-associated phospholipase A2 activity, a marker of vascular inflammation, was decreased in AMD subjects (MD -24.1, p<0.01). Conclusions The investigated metrics of HDL composition and HDL function were not associated with exudative AMD in this study, despite an increased content of HDL associated SAA in AMD patients. Unexpectedly, anti-inflammatory activity of apoB-depleted serum was even increased in our study. Our data suggest that the investigated parameters of serum HDL function showed no significant association with exudative AMD. However, we cannot exclude that alterations in locally produced HDL may be part of the AMD pathogenesis. PMID:27171197

  13. Candidate genetic analysis of plasma high-density lipoprotein-cholesterol and severity of coronary atherosclerosis

    PubMed Central

    Chen, Suet Nee; Cilingiroglu, Mehmet; Todd, Josh; Lombardi, Raffaella; Willerson, James T; Gotto, Antonio M; Ballantyne, Christie M; Marian, AJ

    2009-01-01

    Background Plasma level of high-density lipoprotein-cholesterol (HDL-C), a heritable trait, is an important determinant of susceptibility to atherosclerosis. Non-synonymous and regulatory single nucleotide polymorphisms (SNPs) in genes implicated in HDL-C synthesis and metabolism are likely to influence plasma HDL-C, apolipoprotein A-I (apo A-I) levels and severity of coronary atherosclerosis. Methods We genotyped 784 unrelated Caucasian individuals from two sets of populations (Lipoprotein and Coronary Atherosclerosis Study- LCAS, N = 333 and TexGen, N = 451) for 94 SNPs in 42 candidate genes by 5' nuclease assays. We tested the distribution of the phenotypes by the Shapiro-Wilk normality test. We used Box-Cox regression to analyze associations of the non-normally distributed phenotypes (plasma HDL-C and apo A-I levels) with the genotypes. We included sex, age, body mass index (BMI), diabetes mellitus (DM), and cigarette smoking as covariates. We calculated the q values as indicators of the false positive discovery rate (FDR). Results Plasma HDL-C levels were associated with sex (higher in females), BMI (inversely), smoking (lower in smokers), DM (lower in those with DM) and SNPs in APOA5, APOC2, CETP, LPL and LIPC (each q ≤0.01). Likewise, plasma apo A-I levels, available in the LCAS subset, were associated with SNPs in CETP, APOA5, and APOC2 as well as with BMI, sex and age (all q values ≤0.03). The APOA5 variant S19W was also associated with minimal lumen diameter (MLD) of coronary atherosclerotic lesions, a quantitative index of severity of coronary atherosclerosis (q = 0.018); mean number of coronary artery occlusions (p = 0.034) at the baseline and progression of coronary atherosclerosis, as indicated by the loss of MLD. Conclusion Putatively functional variants of APOA2, APOA5, APOC2, CETP, LPL, LIPC and SOAT2 are independent genetic determinants of plasma HDL-C levels. The non-synonymous S19W SNP in APOA5 is also an independent determinant of plasma apo A-I level, severity of coronary atherosclerosis and its progression. PMID:19878569

  14. The Correlation between the Triglyceride to High Density Lipoprotein Cholesterol Ratio and Computed Tomography-Measured Visceral Fat and Cardiovascular Disease Risk Factors in Local Adult Male Subjects

    PubMed Central

    Park, Hye-Rin; Han, A Lum; Jeong, Yong Joon

    2015-01-01

    Background We studied the association between the triglyceride to high-density lipoprotein cholesterol ratio and computed tomography-measured visceral fat as well as cardiovascular risk factors among Korean male adults. Methods We measured triglycerides, high density lipoprotein cholesterol, body mass, waist circumference, fasting plasma glucose, hemoglobin A1c, systolic blood pressure, diastolic blood pressure, visceral fat, and subcutaneous fat among 372 Korean men. The visceral fat and subcutaneous fat areas were measured by computed tomography using a single computed tomography slice at the L4-5 lumbar level. We analyzed the association between the triglyceride to high density lipoprotein cholesterol ratio and visceral fat as well as cardiovascular risk factors. Results A positive correlation was found between the triglyceride to high density lipoprotein cholesterol ratio and variables such as body mass index, waist circumference, fasting plasma glucose, hemoglobin A1c, visceral fat, and the visceral-subcutaneous fat ratio. However, there was no significant correlation between the triglyceride to high density lipoprotein cholesterol ratio and subcutaneous fat or blood pressure. Multiple logistic regression analyses revealed significant associations between a triglyceride to high density lipoprotein cholesterol ratio ≥3 and diabetes, a body mass index ≥25 kg/m2, a waist circumference ≥90 cm, and a visceral fat area ≥100 cm2. The triglyceride to high density lipoprotein cholesterol ratio was not significantly associated with hypertension. Conclusion There were significant associations between the triglyceride to high density lipoprotein cholesterol ratio and body mass, waist circumference, diabetes, and visceral fat among a clinical sample of Korean men. In the clinical setting, the triglyceride to high density lipoprotein cholesterol ratio may be a simple and useful indicator for visceral obesity and cardiovascular disease. PMID:26634102

  15. Rosuvastatin Alters the Proteome of High Density Lipoproteins: Generation of alpha-1-antitrypsin Enriched Particles with Anti-inflammatory Properties.

    PubMed

    Gordon, Scott M; McKenzie, Benjamin; Kemeh, Georgina; Sampson, Maureen; Perl, Shira; Young, Neal S; Fessler, Michael B; Remaley, Alan T

    2015-12-01

    Statins lower plasma cholesterol by as much as 50%, thus reducing future cardiovascular events. However, the physiological effects of statins are diverse and not all are related to low density lipoprotein cholesterol (LDL-C) lowering. We performed a small clinical pilot study to assess the impact of statins on lipoprotein-associated proteins in healthy individuals (n = 10) with normal LDL-C (<130 mg/dL), who were treated with rosuvastatin (20 mg/day) for 28 days. Proteomic analysis of size-exclusion chromatography isolated LDL, large high density lipoprotein (HDL-L), and small HDL (HDL-S) fractions and spectral counting was used to compare relative protein detection before and after statin therapy. Significant protein changes were found in each lipoprotein pool and included both increases and decreases in several proteins involved in lipoprotein metabolism, complement regulation and acute phase response. The most dramatic effect of the rosuvastatin treatment was an increase in α-1-antirypsin (A1AT) spectral counts associated with HDL-L particles. Quantitative measurement by ELISA confirmed an average 5.7-fold increase in HDL-L associated A1AT. Molecular modeling predictions indicated that the hydrophobic reactive center loop of A1AT, the functional domain responsible for its protease inhibitor activity, is likely involved in lipid binding and association with HDL was found to protect A1AT against oxidative inactivation. Cell culture experiments, using J774 macrophages, demonstrated that the association of A1AT with HDL enhances its antiprotease activity, preventing elastase induced production of tumor necrosis factor α. In conclusion, we show that statins can significantly alter the protein composition of both LDL and HDL and our studies reveal a novel functional relationship between A1AT and HDL. The up-regulation of A1AT on HDL enhances its anti-inflammatory functionality, which may contribute to the non-lipid lowering beneficial effects of statins. PMID:26483418

  16. ?-Tocopheryl hydroquinone is an efficient multifunctional inhibitor of radical-initiated oxidation of low density lipoprotein?lipids

    PubMed Central

    Neuil, Ji?; Witting, Paul K.; Stocker, Roland

    1997-01-01

    As the oxidation of low density lipoprotein (LDL) lipids may be a key event in atherogenesis, there is interest in antioxidants as potential anti-atherogenic compounds. Here we report that ?-tocopheryl hydroquinone (?-TQH2) strongly inhibited or completely prevented the (per)oxidation of ubiquinol-10 (CoQ10H2), ?-tocopherol (?-TOH), and both surface and core lipids in LDL exposed to either aqueous or lipophilic peroxyl radicals, Cu2+, soybean lipoxygenase, or the transition metal-containing Hams F-10 medium in the absence or presence of human monocyte-derived macrophages. The antioxidant activity of ?-TQH2 was superior to that of several other lipophilic hydroquinones, including endogenous CoQ10H2, which is regarded as LDLs first line of antioxidant defence. At least three independent activities contributed to the antioxidant action of ?-TQH2. First, ?-TQH2 readily associated with LDL and instantaneously reduced the lipoproteins ubiquinone-10 to CoQ10H2, thereby maintaining this antioxidant in its active form. Second, ?-TQH2 directly intercepted aqueous peroxyl radicals, as indicated by the increased rate of its consumption with increasing rates of radical production, independent of LDLs content of CoQ10H2 and ?-TOH. Third, ?-TQH2 rapidly quenched ?-tocopheroxyl radical in oxidizing LDL, as demonstrated directly by electron paramagnetic resonance spectroscopy. Similar antioxidant activities were also seen when ?-TQH2 was added to high-density lipoprotein or the protein-free Intralipid, indicating that the potent antioxidant activity of ?-TQH2 was neither lipoprotein specific nor dependent on proteins. These results suggest that ?-TQH2 is a candidate for a therapeutic lipid-soluble antioxidant. As ?-tocopherylquinone is formed in vivo at sites of oxidative stress, including human atherosclerotic plaque, and biological systems exist that reduce the quinone to the hydroquinone, our results also suggest that ?-TQH2 could be a previously unrecognized natural antioxidant. PMID:9223282

  17. Simplified sizing of low-density lipoprotein using polyacrylamide gradient gel electrophoresis of plasma.

    PubMed

    Westhuyzen, J; Graham, S D; Rasiah, R L; Saltissi, D

    1997-01-01

    Low-density lipoprotein (LDL) particles can be separated into subfractions according to size by non-denaturing polyacrylamide gradient gel electrophoresis. Established research methods require specialised equipment and are frequently unsuited to the clinical laboratory. In this study, we utilised a colour flat bed scanner in conjunction with shareware image analysis software to compare LDL particle diameters of isolated LDL with LDL in whole plasma. LDL was isolated by ultracentrifugation and electrophoresed on 3-13% gels (Gradipore; Sydney, Australia) for 2400 Volt-hours in parallel with plasma and molecular size standards. Coomassie Blue-stained gels were scanned in reflexive mode using a colour flat-bed scanner and Adobe Photoshop 3.0 software. Density traces of each lane were obtained using NIH Image software (public domain, USA). LDL particle diameters were determined from calibration curves of the log of molecular diameter of standards against migration distance. There was a good correlation between LDL particle diameters obtained using isolated LDL and whole plasma (r = 0.87, P < 0.001; n = 22). However, the group means (+/- S.D.) (24.7 +/- 0.6 and 24.8 +/- 0.5 nm respectively) were statistically different on the paired t-test (P < 0.05). It is unclear whether this numerically small difference is due to alterations in LDL during the longer preparative procedures for LDL, or to matrix effects during electrophoresis of plasma samples. In conclusion, plasma samples stained with Coomassie Blue and scanned with a colour flat bed scanner can conveniently be used for LDL particle sizing by non-denaturing polyacrylamide gradient gel electrophoresis. PMID:9156560

  18. Modified Low Density Lipoprotein and Lipoprotein-Containing Circulating Immune Complexes as Diagnostic and Prognostic Biomarkers of Atherosclerosis and Type 1 Diabetes Macrovascular Disease

    PubMed Central

    Orekhov, Alexander N.; Bobryshev, Yuri V.; Sobenin, Igor A.; Melnichenko, Alexandra A.; Chistiakov, Dimitry A.

    2014-01-01

    In atherosclerosis; blood low-density lipoproteins (LDL) are subjected to multiple enzymatic and non-enzymatic modifications that increase their atherogenicity and induce immunogenicity. Modified LDL are capable of inducing vascular inflammation through activation of innate immunity; thus, contributing to the progression of atherogenesis. The immunogenicity of modified LDL results in induction of self-antibodies specific to a certain type of modified LDL. The antibodies react with modified LDL forming circulating immune complexes. Circulating immune complexes exhibit prominent immunomodulatory properties that influence atherosclerotic inflammation. Compared to freely circulating modified LDL; modified LDL associated with the immune complexes have a more robust atherogenic and proinflammatory potential. Various lipid components of the immune complexes may serve not only as diagnostic but also as essential predictive markers of cardiovascular events in atherosclerosis. Accumulating evidence indicates that LDL-containing immune complexes can also serve as biomarker for macrovascular disease in type 1 diabetes. PMID:25050779

  19. In vitro studies of PBT Nonwoven Fabrics adsorbent for the removal of low density lipoprotein from hyperlipemia plasma

    NASA Astrophysics Data System (ADS)

    Cao, Ye; Wang, Hong; Yang, Chao; Zhong, Rui; Lei, Yu; Sun, Kang; Liu, Jiaxin

    2011-06-01

    Polyanion ligands such as acrylic acid (AA) and heparin were grafted on PBT Nonwoven Fabrics (PBTNF) to study their effect on the adsorption of low density lipoprotein (LDL). These modified PBTNFs were characterized by Horizontal Attenuated Total Reflectance Fourier Transform Infrared spectroscopy and X-ray Photoelectron spectroscopy. The blood compatibilities of the modified PBTNFs were examined using in vitro hemolysis rate (HR), platelet adhesion, total protein (TP) and activated partial thromboplastin time. The results showed that direct immobilized heparin could improve PBTNF-PAA's blood compatibility and decrease the adsorption capability of useful high density lipoprotein, but would possess so low bioactivity that could not further improve the absorption of LDL and TC. Since the PBTNF-PAA55-Heparin adsorbent had quite good adsorption selectivity for these proteins, it can be an excellent candidate for depletion of LDL with good blood compatibility.

  20. A study of the abnormal lipoproteins in abetalipoproteinemia.

    PubMed Central

    Scanu, A M; Aggerbeck, L P; Kruski, A W; Lim, C T; Kayden, H J

    1974-01-01

    The serum lipoproteins of five patients with abetalipoproteinemia (ABL) were separated by ultracentrifugation and then analyzed either intact or after delipidation. In accord with previous findings, all of the patients lacked serum particles with the characteristics of normal low-density lipoproteins (LDL) and of the LDL apoprotein as assessed by immunochemical methods. Each patient exhibited on every examination an abnormal particle, "LDL", which had the flotational properties of LDL, the polypeptide makeup of high-density lipoproteins HDL, the spectral and morphological characteristics of neither LDL nor HDL, and a relatively low content of cholesteryl esters. The HDL were abnormal in having a marked decrease in their total plasma content, an altered proportion of the subclasses HDL2 and HDL3, and a peculiar polypeptide distribution, comprising both normal and additional components, usually not seen in normal controls. The patients also exhibited a decrease of plasma lecithin-cholesterol acyl transferase (LCAT) activity which probably accounted for the low content of cholesteryl esters in both "LDL" and HDL, and in turn for the unusual appearance of "LDL" on electron microscopy. It is concluded that ABL is a disorder affecting all serum lipoprotein classes. Whether the abetalipoproteinemia previously described and noted in the current studies is related to or independent of the abnormalities observed in the other lipoproteins was not established. How the deficiency of LCAT activity, observed in all patients studied, contributed to some of the observed structural lipoprotein abnormalities also remained undetermined. Images PMID:11344558

  1. Localization of the gene for high-density lipoprotein binding protein (HDLBP) to human chromosome 2q37

    SciTech Connect

    Xia, Y.R.; Klisak, I.; Sparkes, R.S.; Lusis, A.J.; Oram, J.

    1993-05-01

    The high-density lipoprotein binding protein (HDLbp) is a 110-kDa protein that specifically binds HDL molecules and may function in the removal of excess cellular cholesterol. As part of an effort to study the function of the protein and its possible role in cholesterol transport, the authors report the localization of the gene for HDLbp, designated HDLBP, to human chromosome 2q37 using analysis of somatic cell hybrids and in situ hybridization. 14 refs., 1 fig.

  2. Serum amyloid A stimulates macrophage foam cell formation via lectin-like oxidized low-density lipoprotein receptor 1 upregulation

    SciTech Connect

    Lee, Ha Young; Kim, Sang Doo; Baek, Suk-Hwan; Choi, Joon Hyuk; Cho, Kyung-Hyun; Zabel, Brian A.; Bae, Yoe-Sik; Mitochondria Hub Regulation Center, Dong-A University, Busan 602-714; Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul 135-710

    2013-03-29

    Highlights: ► SAA induced macrophage foam cell formation. ► SAA stimulated upregulation of lectin-like oxidized low-density lipoprotein receptor 1 (LOX1). ► SAA-induced LOX1 expression and foam cell formation is mediated by JNK/NF-κB signaling. ► HDL-conjugated SAA also stimulates foam cell formation via LOX1 upregulation. ► The finding reveals a novel mechanism of action of SAA in the pathogenesis of atherosclerosis. -- Abstract: Elevated levels of serum amyloid A (SAA) is a risk factor for cardiovascular diseases, however, the role of SAA in the pathophysiology of atherosclerosis remains unclear. Here we show that SAA induced macrophage foam cell formation. SAA-stimulated foam cell formation was mediated by c-jun N-terminal kinase (JNK) signaling. Moreover, both SAA and SAA-conjugated high density lipoprotein stimulated the expression of the important scavenger receptor lectin-like oxidized low-density lipoprotein receptor 1 (LOX1) via nuclear factor-κB (NF-κB). A LOX1 antagonist carrageenan significantly blocked SAA-induced foam cell formation, indicating that SAA promotes foam cell formation via LOX1 expression. Our findings therefore suggest that SAA stimulates foam cell formation via LOX1 induction, and thus likely contributes to atherogenesis.

  3. High-Density and Very-Low-Density Lipoprotein Have Opposing Roles in Regulating Tumor-Initiating Cells and Sensitivity to Radiation in Inflammatory Breast Cancer

    SciTech Connect

    Wolfe, Adam R.; Atkinson, Rachel L.; Reddy, Jay P.; Debeb, Bisrat G.; Larson, Richard; Li, Li; Masuda, Hiroko; Brewer, Takae; Atkinson, Bradley J.; Brewster, Abeena; Ueno, Naoto T.; Woodward, Wendy A.

    2015-04-01

    Purpose: We previously demonstrated that cholesterol-lowering agents regulate radiation sensitivity of inflammatory breast cancer (IBC) cell lines in vitro and are associated with less radiation resistance among IBC patients who undergo postmastectomy radiation. We hypothesized that decreasing IBC cellular cholesterol induced by treatment with lipoproteins would increase radiation sensitivity. Here, we examined the impact of specific transporters of cholesterol (ie lipoproteins) on the responses of IBC cells to self-renewal and to radiation in vitro and on clinical outcomes in IBC patients. Methods and Materials: Two patient-derived IBC cell lines, SUM 149 and KPL4, were incubated with low-density lipoproteins (LDL), very-low-density lipoproteins (VLDL), or high-density lipoproteins (HDL) for 24 hours prior to irradiation (0-6 Gy) and mammosphere formation assay. Cholesterol panels were examined in a cohort of patients with primary IBC diagnosed between 1995 and 2011 at MD Anderson Cancer Center. Lipoprotein levels were then correlated to patient outcome, using the log rank statistical model, and examined in multivariate analysis using Cox regression. Results: VLDL increased and HDL decreased mammosphere formation compared to untreated SUM 149 and KPL4 cells. Survival curves showed enhancement of survival in both of the IBC cell lines when pretreated with VLDL and, conversely, radiation sensitization in all cell lines when pretreated with HDL. In IBC patients, higher VLDL values (>30 mg/dL) predicted a lower 5-year overall survival rate than normal values (hazard ratio [HR] = 1.9 [95% confidence interval [CI]: 1.05-3.45], P=.035). Lower-than-normal patient HDL values (<60 mg/dL) predicted a lower 5-year overall survival rate than values higher than 60 mg/dL (HR = 3.21 [95% CI: 1.25-8.27], P=.015). Conclusions: This study discovered a relationship among the plasma levels of lipoproteins, overall patient response, and radiation resistance in IBC patients and IBC patient-derived cell lines. A more expansive study is needed to verify these observations.

  4. High-Density and Very-Low-Density Lipoprotein Have Opposing Roles in Regulating Tumor-Initiating Cells and Sensitivity to Radiation in Inflammatory Breast Cancer

    PubMed Central

    Wolfe, Adam R.; Atkinson, Rachel L.; Reddy, Jay P.; Debeb, Bisrat G.; Larson, Richard; Li, Li; Masuda, Hiroko; Brewer, Takae; Atkinson, Bradley J.; Brewster, Abeena; Ueno, Naoto T.; Woodward, Wendy A.

    2015-01-01

    Purpose We previously demonstrated that cholesterol-lowering agents regulate radiation sensitivity of inflammatory breast cancer (IBC) cell lines in vitro and are associated with less radiation resistance among IBC patients who undergo postmastectomy radiation. We hypothesized that decreasing IBC cellular cholesterol induced by treatment with lipoproteins would increase radiation sensitivity. Here, we examined the impact of specific transporters of cholesterol (ie lipoproteins) on the responses of IBC cells to self-renewal and to radiation in vitro and on clinical outcomes in IBC patients. Methods and Materials Two patient-derived IBC cell lines, SUM 149 and KPL4, were incubated with low-density lipoproteins (LDL), very-low-density lipoproteins (VLDL), or high-density lipoproteins (HDL) for 24 hours prior to irradiation (0–6 Gy) and mammosphere formation assay. Cholesterol panels were examined in a cohort of patients with primary IBC diagnosed between 1995 and 2011 at MD Anderson Cancer Center. Lipoprotein levels were then correlated to patient outcome, using the log rank statistical model, and examined in multivariate analysis using Cox regression. Results VLDL increased and HDL decreased mammosphere formation compared to untreated SUM 149 and KPL4 cells. Survival curves showed enhancement of survival in both of the IBC cell lines when pretreated with VLDL and, conversely, radiation sensitization in all cell lines when pretreated with HDL. In IBC patients, higher VLDL values (>30 mg/dL) predicted a lower 5-year overall survival rate than normal values (hazard ratio [HR] = 1.9 [95% confidence interval [CI]: 1.05–3.45], P=.035). Lower-than-normal patient HDL values (<60 mg/dL) predicted a lower 5-year overall survival rate than values higher than 60 mg/dL (HR = 3.21 [95% CI: 1.25–8.27], P=.015). Conclusions This study discovered a relationship among the plasma levels of lipoproteins, overall patient response, and radiation resistance in IBC patients and IBC patient-derived cell lines. A more expansive study is needed to verify these observations. PMID:25832697

  5. Low density lipoprotein receptor related protein 1 variant interacts with saturated fatty acids in Puerto Ricans

    PubMed Central

    Smith, Caren E.; Tucker, Katherine L.; Lee, Yu-Chi; Lai, Chao-Qiang; Parnell, Laurence D.; Ordovás, José M.

    2012-01-01

    Low density lipoprotein related receptor protein 1 (LRP1) is a multi-functional endocytic receptor that is highly expressed in adipocytes and the hypothalamus. Animal models and in vitro studies support a role for LRP1 in adipocyte metabolism and leptin signaling, but genetic polymorphisms have not been evaluated for obesity in people. We examined whether dietary fats (eg., saturated, polyunsaturated) modulated the association of LRP1 variants with anthropometric traits. We studied a population-based sample of Puerto Ricans (n=920, aged 45–74 y) living in the Boston area. In multivariable linear regression models, we dichotomized saturated fat intake and found significant interaction terms between total saturated fatty acids and LRP1 rs1799986 genotype for BMI (P=0.006) and hip (P=0.002). High intake of saturated fat was associated with higher BMI (P=0.001), waist (P=0.008) and hip (P=0.003) in minor allele carriers (CT+TT) compared to CC participants. Further analysis of dichotomized individual saturated fatty acids revealed that interactions were strongest for two individual longer chain fatty acids. High intake of palmitic acid (C16:0; P=0.0007) and high stearic acid intake (C18:0; P=0.005) were associated with higher BMI in T carriers. Interactions were not detected for polyunsaturated fatty acids. Gene-diet interactions at the LRP1 locus support the hypothesis that susceptibility to weight gain based on saturated fatty acids is modified by genotype and possibly by chain length. These results may facilitate the development of a panel of genetic candidates for use in optimizing dietary recommendations for obesity management. PMID:23404896

  6. Nicotine-Induced Expression of Low-Density Lipoprotein Receptor in Oral Epithelial Cells

    PubMed Central

    Ito, Satoshi; Gojoubori, Takahiro; Tsunoda, Kou; Yamaguchi, Yoko; Asano, Masatake; Goke, Eiji; Koshi, Ryosuke; Sugano, Naoyuki; Yoshinuma, Naoto; Komiyama, Kazuo; Ito, Koichi

    2013-01-01

    Background Nicotine use is one of the most important risk factors for the development of cardiovascular and periodontal diseases. Numerous reports have suggested the possible contribution of disturbed lipid metabolism for the development of both disease groups. Despite these observations, little is known about the relationship between tobacco smoking and the development of these diseases. Our previous microarray data revealed that nicotine induced low-density lipoprotein receptor (LDLR) expression in oral epithelial cells (OECs). The aim of the present study was to confirm nicotine-mediated LDLR induction and to elucidate the signaling mechanisms leading to the augmented expression of LDLR in OECs. Methods and Results LDLR and nicotinic acetylcholine receptor (nAChR) subunit expression was detected by real-time PCR. The production of LDLR was demonstrated by immunofluorescence staining. nAChR-mediated LDLR induction was examined by pre-incubation of the cells with its specific inhibitor, α-bungarotoxin (α-BTX). The functional importance of transcription factor specific protein 1 (Sp1) was examined by luciferase assay, mithramycin pre-incubation or by small interfering RNA (siRNA) transfection. The specific binding of Sp1 to R3 region of LDLR 5’-untranslated region was demonstrated with electrophoretic mobility shift assay (EMSA) and streptavidin-agarose precipitation assay followed by western blotting. The results confirmed that nicotine induced LDLR expression at the transcriptional level. Nicotine was sensed by nAChR and the signal was transduced by Sp1 which bound to the R3 region of LDLR gene. Augmented production of LDLR in the gingival epithelial cells was further demonstrated by immunofluorescence staining using the gingival tissues obtained from the smoking patients. Conclusions Taken together, the results suggested that nicotine might contribute to the development of both cardiovascular and periodontal diseases by inducing the LDLR in OECs thereby disturbing lipid metabolism. PMID:24358207

  7. Impaired High-Density Lipoprotein Anti-Oxidant Function Predicts Poor Outcome in Critically Ill Patients

    PubMed Central

    Schrutka, Lore; Goliasch, Georg; Meyer, Brigitte; Wurm, Raphael; Koller, Lorenz; Kriechbaumer, Lukas; Heinz, Gottfried; Pacher, Richard; Lang, Irene M

    2016-01-01

    Introduction Oxidative stress affects clinical outcome in critically ill patients. Although high-density lipoprotein (HDL) particles generally possess anti-oxidant capacities, deleterious properties of HDL have been described in acutely ill patients. The impact of anti-oxidant HDL capacities on clinical outcome in critically ill patients is unknown. We therefore analyzed the predictive value of anti-oxidant HDL function on mortality in an unselected cohort of critically ill patients. Method We prospectively enrolled 270 consecutive patients admitted to a university-affiliated intensive care unit (ICU) and determined anti-oxidant HDL function using the HDL oxidant index (HOI). Based on their HOI, the study population was stratified into patients with impaired anti-oxidant HDL function and the residual study population. Results During a median follow-up time of 9.8 years (IQR: 9.2 to 10.0), 69% of patients died. Cox regression analysis revealed a significant and independent association between impaired anti-oxidant HDL function and short-term mortality with an adjusted HR of 1.65 (95% CI 1.22–2.24; p = 0.001) as well as 10-year mortality with an adj. HR of 1.19 (95% CI 1.02–1.40; p = 0.032) when compared to the residual study population. Anti-oxidant HDL function correlated with the amount of oxidative stress as determined by Cu/Zn superoxide dismutase (r = 0.38; p<0.001). Conclusion Impaired anti-oxidant HDL function represents a strong and independent predictor of 30-day mortality as well as long-term mortality in critically ill patients. PMID:26978526

  8. Low-Density Lipoprotein Apheresis Ameliorates Renal Prognosis of Cholesterol Crystal Embolism.

    PubMed

    Ishiyama, Katsuya; Sato, Toshinobu; Taguma, Yoshio

    2015-08-01

    Drugs such as corticosteroids and statins have been used to treat cholesterol crystal embolism (CCE), but the prognosis remains poor. This study evaluated the efficacy of low-density lipoprotein apheresis (LDL-A) in patients with CCE. Patients with CCE who showed renal deterioration after vascular interventions were studied retrospectively. Information on demographic variables, clinical measurements, and medication use was collected. The outcomes were incidence of maintenance dialysis and mortality at 24 weeks. A total of 49 patients with CCE were included, among whom 37 (76%) were diagnosed pathologically and the remainder were diagnosed clinically. The median estimated GFR at baseline and at diagnosis were 40.5 and 13.4 mL/min per 1.73 m(2) , respectively. Corticosteroids were used in 42 patients (86%), statins in 30 patients (61%), and angiotensin-converting enzyme inhibitors and angiotensin receptor blockers in 29 patients (59%). LDL-A was performed in 25 patients (LDL-A group), and not in 24 patients (control group). Smoking (100% vs. 72%, P = 0.02), white blood cell count (8900/mm(3) vs. 7000/mm(3) ) and corticosteroid use (96% vs. 75%) were higher in the LDL-A group compared with the control group, but there were no differences in other demographic and clinical parameters between the groups. Patients in the LDL-A group had a lower incidence of maintenance dialysis (2/25 (8%) vs. 8/24 (33%), P < 0.05), and a trend towards lower mortality (2/25 (8%) vs. 7/24 (29%), P = 0.074). These results suggest that LDL-A decreases the risk of maintenance dialysis in severe renal CCE patients after vascular interventions. PMID:26386224

  9. Assessment of the Validity of the Double Superhelix Model for Reconstituted High Density Lipoproteins

    PubMed Central

    Jones, Martin K.; Zhang, Lei; Catte, Andrea; Li, Ling; Oda, Michael N.; Ren, Gang; Segrest, Jere P.

    2010-01-01

    For several decades, the standard model for high density lipoprotein (HDL) particles reconstituted from apolipoprotein A-I (apoA-I) and phospholipid (apoA-I/HDL) has been a discoidal particle ∼100 Å in diameter and the thickness of a phospholipid bilayer. Recently, Wu et al. (Wu, Z., Gogonea, V., Lee, X., Wagner, M. A., Li, X. M., Huang, Y., Undurti, A., May, R. P., Haertlein, M., Moulin, M., Gutsche, I., Zaccai, G., Didonato, J. A., and Hazen, S. L. (2009) J. Biol. Chem. 284, 36605–36619) used small angle neutron scattering to develop a new model they termed double superhelix (DSH) apoA-I that is dramatically different from the standard model. Their model possesses an open helical shape that wraps around a prolate ellipsoidal type I hexagonal lyotropic liquid crystalline phase. Here, we used three independent approaches, molecular dynamics, EM tomography, and fluorescence resonance energy transfer spectroscopy (FRET) to assess the validity of the DSH model. (i) By using molecular dynamics, two different approaches, all-atom simulated annealing and coarse-grained simulation, show that initial ellipsoidal DSH particles rapidly collapse to discoidal bilayer structures. These results suggest that, compatible with current knowledge of lipid phase diagrams, apoA-I cannot stabilize hexagonal I phase particles of phospholipid. (ii) By using EM, two different approaches, negative stain and cryo-EM tomography, show that reconstituted apoA-I/HDL particles are discoidal in shape. (iii) By using FRET, reconstituted apoA-I/HDL particles show a 28–34-Å intermolecular separation between terminal domain residues 40 and 240, a distance that is incompatible with the dimensions of the DSH model. Therefore, we suggest that, although novel, the DSH model is energetically unfavorable and not likely to be correct. Rather, we conclude that all evidence supports the likelihood that reconstituted apoA-I/HDL particles, in general, are discoidal in shape. PMID:20974855

  10. Cryoprotective effects of low-density lipoproteins, trehalose and soybean lecithin on murine spermatogonial stem cells.

    PubMed

    Wang, Peng; Li, Ying; Hu, Xiao-Chen; Cai, Xiao-Li; Hou, Li-Peng; Wang, Yan-Feng; Hu, Jian-Hong; Li, Qing-Wang; Suo, Li-Juan; Fan, Zhi-Guo; Zhang, Bo

    2014-05-01

    Spermatogonial stem cells (SSCs) have the ability to self-renew and offer a pathway for genetic engineering of the male germ line. Cryopreservation of SSCs has potential value for the treatment of male infertility, spermatogonial transplantation, and so on. In order to investigate the cryopreservation effects of different cryoprotectants on murine SSCs, 0.2 M of low-density lipoproteins (LDL), trehalose and soybean lecithin were added to the cryoprotective medium, respectively, and the murine SSCs were frozen at -80°C or -196°C. The results indicated that the optimal recovery rates of murine SSCs in the cryoprotective medium supplemented with LDL, trehalose and soybean lecithin were 92.53, 76.35 and 75.48% at -80°C, respectively. Compared with freezing at -196°C, the optimum temperature for improvement of recovery rates of frozen murine SSCs, cryopreservation in three different cryoprotectants at -80°C, were 17.11, 6.68 and 10.44% respectively. The recovery rates of murine SSCs in the cryoprotective medium supplemented with 0.2 M LDL were significantly higher than that of other cryoprotectants (P < 0.05). Moreover, the recovery rates were demonstrated to be greater at -80°C compared with at -196°C (P < 0.05). In conclusion, 0.2 M of LDL could significantly protect murine SSCs at -80°C. In the freezing-thawing process, LDL is responsible for the cryopreservation of murine SSCs because it can form a protective film at the surface of membranes. However, more research is needed to evaluate and understand the precise role of LDL during the freezing-thawing of SSCs. PMID:22974447

  11. Association of lipoarabinomannan with high density lipoprotein in blood: Implications for diagnostics

    DOE PAGESBeta

    Sakamuri, Rama Murthy; Price, Dominique N.; Lee, Myungsun; Cho, Sang Nae; Barry, Clifton E.; Via, Laura E.; Swanson, Basil I.; Mukundan, Harshini

    2013-02-14

    Understanding the pathophysiology of tuberculosis, and the bio-distribution of pathogen-associated molecules in the host is essential for the development of efficient methods of intervention. One of the key virulence factors in the pathology of tuberculosis infection is Lipoarabinomannan (LAM). Previously, we have demonstrated the reliable detection of LAM in urine from tuberculosis patients in a sandwich immunoassay format. We also applied an ultra-sensitive detection strategy developed for amphiphilic biomarkers, membrane insertion, to the detection of LAM with a limit of detection of 10 fM. Herein, we evaluate the application of membrane insertion to the detection of LAM in patient serum,more » and demonstrate that the circulating concentrations of ‘monomeric’ LAM in serum are very low, despite significantly higher concentrations in the urine. Using spiked samples, we demonstrate that this discrepancy is due to the association of LAM with high-density lipoprotein (HDL) nanodiscs in human serum. Indeed, pull-down of HDL nanodiscs from human serum allows for the recovery of HDL-associated LAM. These studies suggest that LAM is likely associated with carrier molecules such as HDL in the blood of patients infected with tuberculosis. Furthermore, this phenomenon may not be limited to LAM in that many pathogen-associated molecular patterns like LAM are amphiphilic in nature and may also be associated with host lipid carriers. Such interactions are likely to affect host–pathogen interactions, pathogen bio-distribution and clearance in the host, and must be thoroughly understood for the effective design of vaccines and diagnostics.« less

  12. High-Density Lipoprotein Function Measurement in Human Studies: Focus on Cholesterol Efflux Capacity.

    PubMed

    Rohatgi, Anand

    2015-01-01

    A low plasma level of high-density lipoprotein (HDL) cholesterol (HDL-C) is a major risk factor for the development of atherosclerotic cardiovascular disease (ASCVD). However, several observations have highlighted the shortcomings of using cholesterol content as the sole reflection of HDL metabolism. In particular, several large randomized controlled trials of extended release niacin and cholesteryl-ester transfer protein (CETP) inhibitors on background statin therapy have failed to show improvement in ASCVD outcomes despite significant increases in HDL-C. Reverse cholesterol transport (RCT) is the principal HDL function that impacts macrophage foam cell formation and other functions such as endothelial activation of endothelial nitric oxide synthase, monocyte adhesion, and platelet aggregation. Cholesterol efflux from macrophages to plasma/serum reflects the first critical step of RCT and is considered a key anti-atherosclerotic function of HDL. Whether this function is operative in humans remains to be seen, but recent studies assessing cholesterol efflux in humans suggest that the cholesterol efflux capacity (CEC) of human plasma or serum is a potent marker of ASCVD risk. This review describes the methodology of measuring CEC ex vivo from human samples and the findings to date linking CEC to human disease. Studies to date confirm that CEC can be reliably measured using stored human blood samples as cholesterol acceptors and suggest that CEC may be a promising new biomarker for atherosclerotic and metabolic diseases. Further studies are needed to standardize measurements and clarify the role CEC may play in predicting risk of developing disease and response to therapies. PMID:25968932

  13. Automated detection and tracking of individual and clustered cell surface low density lipoprotein receptor molecules.

    PubMed Central

    Ghosh, R N; Webb, W W

    1994-01-01

    We have developed a technique to detect, recognize, and track each individual low density lipoprotein receptor (LDL-R) molecule and small receptor clusters on the surface of human skin fibroblasts. Molecular recognition and high precision (30 nm) simultaneous automatic tracking of all of the individual receptors in the cell surface population utilize quantitative time-lapse low light level digital video fluorescence microscopy analyzed by purpose-designed algorithms executed on an image processing work station. The LDL-Rs are labeled with the biologically active, fluorescent LDL derivative dil-LDL. Individual LDL-Rs and unresolved small clusters are identified by measuring the fluorescence power radiated by the sub-resolution fluorescent spots in the image; identification of single particles is ascertained by four independent techniques. An automated tracking routine was developed to track simultaneously, and without user intervention, a multitude of fluorescent particles through a sequence of hundreds of time-lapse image frames. The limitations on tracking precision were found to depend on the signal-to-noise ratio of the tracked particle image and mechanical drift of the microscope system. We describe the methods involved in (i) time-lapse acquisition of the low-light level images, (ii) simultaneous automated tracking of the fluorescent diffraction limited punctate images, (iii) localizing particles with high precision and limitations, and (iv) detecting and identifying single and clustered LDL-Rs. These methods are generally applicable and provide a powerful tool to visualize and measure dynamics and interactions of individual integral membrane proteins on living cell surfaces. Images FIGURE 1 FIGURE 6 FIGURE 7 FIGURE 8 FIGURE 9 FIGURE 10 PMID:8061186

  14. High density lipoprotein from patients with valvular heart disease uncouples endothelial nitric oxide synthase.

    PubMed

    Chang, Feng-Jun; Yuan, Hai-Yun; Hu, Xiao-Xia; Ou, Zhi-Jun; Fu, Li; Lin, Ze-Bang; Wang, Zhi-Ping; Wang, Shen-Ming; Zhou, Li; Xu, Ying-Qi; Wang, Cui-Ping; Xu, Zhe; Zhang, Xi; Zhang, Chun-Xiang; Ou, Jing-Song

    2014-09-01

    Normal high density lipoprotein (HDL) protects vascular function; however these protective effects of HDL may absent in valvular heart disease (VHD). Because vascular function plays an important role in maintaining the circulation post-cardiac surgery and some patients are difficult to stabilize, we hypothesized that a deleterious vascular effect of HDL may contribute to vascular dysfunction in VHD patients following surgery. HDL was isolated from age-match 28 healthy subjects and 84 patients with VHD and during cardiac surgery. HDL pro-inflammation index was measured and the effects of HDL on vasodilation, protein interaction, generation of nitric oxide (NO) and superoxide were determined. Patients with VHD received either simvastatin (20mg/d) or routine medications, and endothelial effects of HDL were characterized. HDL inflammation index significantly increased in VHD patients and post-cardiac surgery. HDL from VHD patients and post-cardiac surgery significantly impaired endothelium-dependent vasodilation, inhibited both Akt and endothelial nitric oxide synthase (eNOS) phosphorylation at S1177, eNOS associated with heat shock protein 90 (HSP90), NO production and increased eNOS phosphorylation at T495 and superoxide generation. Simvastatin therapy partially reduced HDL inflammation index, improved the capacity of HDL to stimulate eNOS and Akt phosphorylation at S1177, eNOS associated with HSP90, NO production, reduced eNOS phosphorylation at T495 and superoxide generation, and improved endothelium-dependent vasodilation. Our data demonstrated that HDL from VHD patients and cardiac surgery contributed to endothelial dysfunction through uncoupling of eNOS. This deleterious effect can be reversed by simvastatin, which improves the vasoprotective effects of HDL. Targeting HDL may be a therapeutic strategy for maintaining vascular function and improving the outcomes post-cardiac surgery. PMID:24887036

  15. Lipoxygenase treatment render low-density lipoprotein susceptible to Cu2+-catalysed oxidation.

    PubMed Central

    Lass, A; Belkner, J; Esterbauer, H; Kühn, H

    1996-01-01

    Oxidative modification of low-density lipoprotein (LDL) has been implicated in foam-cell formation at all stages of atherosclerosis. Since transition metals and mammalian 15-lipoxygenases are capable of oxidizing LDL to its atherogenic form, a concerted action of these two catalysts in atherogenesis has been suggested. Cu2+-catalysed LDL oxidation is characterized by a kinetic lag period in which the lipophilic antioxidants are decomposed and by a complex mixture of unspecific oxidation products. We investigated the kinetics of the 15-lipoxygenase-catalysed oxygenation of LDL and found that the enzyme is capable of oxidizing LDL in the presence of the endogenous lipophilic antioxidants. In contrast with the Cu2+-catalysed reaction, no kinetic lag phase was detected. The pattern of products formed during short-term incubations was highly specific, with cholesterol-esterified (13S)-hydroperoxy-(9Z,11E)-octadecadinoic acid being the major product. However, after long-term incubations the product pattern was less specific. Preincubation with 15-lipoxygenase rendered human LDL more susceptible to Cu2+-catalysed oxidation as indicated by a dramatic shortening of the lag period. Addition of Cu2+ to lipoxygenase-treated LDL led to a steep decline in its antioxidant content and to a greatly reduced lag period. Interestingly, if normalized to a comparable hydroperoxide content, autoxidation and addition of exogenous hydroperoxy fatty acids both failed to overcome the lag period. The local peroxide concentrations in various LDL subcompartments will be discussed as a possible reason for this unexpected behaviour. PMID:8670073

  16. Abdominal adiposity, insulin resistance, and oxidized low-density lipoproteins in Latino adolescents.

    PubMed

    Ryder, Justin R; Vega-López, Sonia; Djedjos, Constantine S; Shaibi, Gabriel Q

    2013-01-01

    Abdominal obesity and insulin resistance (IR) place youth at higher risk for premature cardiovascular disease (CVD), but the underlying mechanisms are not clear. In adults, abdominal obesity and IR contribute to the oxidation of low-density lipoprotein (LDL). Whether similar mechanisms are operational in Latino adolescents is unknown. Therefore, we determined whether IR and abdominal adiposity are associated with higher oxLDL concentrations in Latino adolescents. Data from 123 Latino adolescents (16.3 ± 2.5 years; female = 74) were used for the present analysis. Participants were assessed for waist circumference, fasting serum oxLDL, and insulin sensitivity by the whole body insulin sensitivity index. In separate linear regression models adjusting for age and sex, both waist circumference and insulin sensitivity were significant predictors of oxLDL (β = 1.9; p = 0.002; R2 = 0.13, β = -1.7; p = 0.006; R2 = 0.11, respectively). When insulin sensitivity and waist circumference were included in the same model, both remained independent predictors of oxLDL (β = 1.7; p = 0.016 and, β = -1.5; p = 0.055, respectively; R2 = 0.16). These results suggest that insulin resistance and abdominal adiposity are associated with higher levels of LDL oxidation which may be a mechanism contributing to increased CVD risk in Latino adolescents. PMID:24238302

  17. Autoantibodies to low-density-lipoprotein-receptor-related protein 2 (LRP2) in systemic autoimmune diseases

    PubMed Central

    Ooka, Seido; Matsui, Toshihiro; Nishioka, Kusuki; Kato, Tomohiro

    2003-01-01

    We previously reported that autoantibodies (autoAbs) to the main epitope on CD69 reacted to its homologous amino acid sequence in low-density-lipoprotein-receptor-related protein 2 (LPR2), a multiligand receptor for protein reabsorption. In this study, we have investigated the prevalence, autoepitope distribution, and clinical significance of the autoAbs to LRP2 in patients with systemic autoimmune diseases. Using six recombinant proteins (F2–F7) for LRP2 and one for CD69, we detected autoAbs to LRP2 in sera of patients with rheumatoid arthritis (RA), systemic lupus erythematosus, Behçet's disease, systemic sclerosis, and osteoarthritis and then mapped autoepitopes by Western blotting. The autoAbs to LRP2 were detected in 87% of the patients with rheumatoid arthritis, 40% of those with systemic lupus erythematosus, 35% of those with systemic sclerosis, 15% of those with osteoarthritis, and 3% of those with Behçet's disease. Multiple epitopes on LRP2 were recognized by most of the anti-LRP2+ serum samples. All of the tested anti-CD69 autoAb+ samples reacted to LRP2-F3 containing the homologous sequence to the main epitope of CD69; however, only 38% of the anti-LRP2-F3+ samples reacted to CD69. Clinically, the existence of the autoAbs to LRP2-F4, -F5, and -F6 correlated with the presence of proteinuria in RA. This study revealed that LRP2 is a major autoantigen in RA. The autoAbs to LRP2 are probably produced by the antigen-driven mechanism and the autoimmunity to LRP2 may spread to include CD69. The anti-LRP2 autoAbs may play pathological roles by inhibiting the reabsorbing function of LRP2. PMID:12723989

  18. Cholesteryl Ester Hydroperoxides Are Biologically Active Components of Minimally Oxidized Low Density Lipoprotein*S⃞

    PubMed Central

    Harkewicz, Richard; Hartvigsen, Karsten; Almazan, Felicidad; Dennis, Edward A.; Witztum, Joseph L.; Miller, Yury I.

    2008-01-01

    Oxidation of low density lipoprotein (LDL) occurs in vivo and significantly contributes to the development of atherosclerosis. An important mechanism of LDL oxidation in vivo is its modification with 12/15-lipoxygenase (LO). We have developed a model of minimally oxidized LDL (mmLDL) in which native LDL is modified by cells expressing 12/15LO. This mmLDL activates macrophages inducing membrane ruffling and cell spreading, activation of ERK1/2 and Akt signaling, and secretion of proinflammatory cytokines. In this study, we found that many of the biological activities of mmLDL were associated with cholesteryl ester (CE) hydroperoxides and were diminished by ebselen, a reducing agent. Liquid chromatography coupled with mass spectroscopy demonstrated the presence of many mono- and polyoxygenated CE species in mmLDL but not in native LDL. Nonpolar lipid extracts of mmLDL activated macrophages, although to a lesser degree than intact mmLDL. The macrophage responses were also induced by LDL directly modified with immobilized 12/15LO, and the nonpolar lipids extracted from 12/15LO-modified LDL contained a similar set of oxidized CE. Cholesteryl arachidonate modified with 12/15LO also activated macrophages and contained a similar collection of oxidized CE molecules. Remarkably, many of these oxidized CE were found in the extracts of atherosclerotic lesions isolated from hyperlipidemic apoE–/– mice. These results suggest that CE hydroperoxides constitute a class of biologically active components of mmLDL that may be relevant to proinflammatory activation of macrophages in atherosclerotic lesions. PMID:18263582

  19. Functionalized low-density lipoprotein nanoparticles for in vivo enhancement of atherosclerosis on magnetic resonance images.

    PubMed

    Lowell, Andrew N; Qiao, Hui; Liu, Ting; Ishikawa, Takashi; Zhang, Hualei; Oriana, Sean; Wang, Miao; Ricciotti, Emanuela; FitzGerald, Garret A; Zhou, Rong; Yamakoshi, Yoko

    2012-11-21

    To allow visualization of macrophage-rich and miniature-sized atheromas by magnetic resonance (MR) imaging, we have converted low-density lipoprotein (LDL) into MR-active nanoparticles via the intercalation of a 1,4,7,10-tetraazacyclodecane-1,4,7-triacetic acid (DO3A) derivative and the subsequent coordination reaction with Gd(3+). After careful removal of nonchelated Gd(3+), an MR-active LDL (Gd(3+)-LDL) with a remarkably high payload of Gd(3+) (in excess of 200 Gd(3+) atoms per particle) and a high relaxivity (r(1) = 20.1 s(-1) mM(-1) per Gd(3+) or 4040 s(-1) mM(-1) per LDL) was obtained. Dynamic light-scattering photon correlation spectroscopy (DLS) and cryo transmission electron microscope (cryoTEM) images showed that Gd(3+)-LDL particles did not aggregate and remained of a similar size (25-30 nm) to native LDL. Intravenous injection of Gd(3+)-LDL into an atherosclerotic mouse model (ApoE(-/-)) resulted in an extremely high enhancement of the atheroma-bearing aortic walls at 48 h after injection. Free Gd(3+) dissociation from Gd(3+)-LDL was not detected over the imaging time window (96 h). Because autologous LDL can be isolated, modified, and returned to the same patient, our results suggest that MR-active LDL can potentially be used as a noninfectious and nonimmunogenic imaging probe for the enhancement of atheroplaques presumably via the uptake into macrophages inside the plaque. PMID:23075169

  20. Small high-density lipoprotein is associated with monocyte subsets in stable coronary artery disease

    PubMed Central

    Krychtiuk, Konstantin A.; Kastl, Stefan P.; Pfaffenberger, Stefan; Pongratz, Thomas; Hofbauer, Sebastian L.; Wonnerth, Anna; Katsaros, Katharina M.; Goliasch, Georg; Gaspar, Ludovit; Huber, Kurt; Maurer, Gerald; Dostal, Elisabeth; Oravec, Stanislav; Wojta, Johann; Speidl, Walter S.

    2014-01-01

    Objective: High-density lipoprotein (HDL) particles are heterogeneous in structure and function and the role of HDL subfractions in atherogenesis is not well understood. It has been suggested that small HDL may be dysfunctional in patients with coronary artery disease (CAD). Monocytes are considered to play a key role in atherosclerotic diseases. Circulating monocytes can be divided into three subtypes according to their surface expression of CD14 and CD16. Our aim was to examine whether monocyte subsets are associated with HDL subfractions in patients with atherosclerosis. Methods: We included 90 patients with angiographically stable CAD. Monocyte subsets were defined as classical monocytes (CD14++CD16-; CM), intermediate monocytes (CD14++CD16+; IM) and non-classical monocytes (CD14+CD16++; NCM). HDL subfractions were measured by electrophoresis on polyacrylamide gel. Results: Serum levels of small HDL correlated with circulating pro-inflammatory NCM and showed an inverse relationship to circulating CM independently from other lipid parameters, risk factors, inflammatory parameters or statin treatment regime, respectively. IM were not associated with small HDL. In particular, patients with small HDL levels in the highest tertile showed dramatically increased levels of NCM (14.7 ± 7% vs. 10.7 ± 5% and 10.8 ± 5%; p = 0.006) and a decreased proportion of CM (79.3 ± 7% vs. 83.7 ± 6% and 83.9 ± 6%; p = 0.004) compared to patients in the two lower tertiles. In contrast, intermediate HDL, large HDL and total HDL were not associated with monocyte subset distribution. Conclusion: Small HDL levels are associated with pro-inflammatory NCM and inversely correlated with CM. This may suggest that small HDL could have dysfunctional anti-inflammatory properties in patients with established CAD. PMID:25463093

  1. Evidence of association between plasma high-density lipoprotein cholesterol and risk factors for breast cancer.

    PubMed

    Boyd, N F; McGuire, V

    1990-03-21

    Females in western societies have higher plasma levels of high-density lipoprotein cholesterol (HDL-C) than males. The difference in plasma lipids between the sexes is believed to contribute to differences in risk of heart disease. The evidence reviewed here demonstrates that plasma levels of HDL-C are also associated with factors influencing risk of breast cancer, a leading cause of death in women in western societies. Both breast cancer risk and HDL-C levels are higher in women who live in northern European countries than in those who live in Asia, in women who have never been pregnant compared with those who have, and in women of higher socioeconomic status. HDL-C levels are also affected by several other known or suspected factors in breast cancer risk; these include dietary fat intake, alcohol consumption, endogenous hormones, and premenopausal leanness. Increases in any of these factors are known to increase the level of HDL-C. Preliminary work has also shown HDL-C levels to be higher in subjects with mammographic dysplasia and a family history of breast cancer. Further, in serum-free culture systems, HDL-C appears to possess biologic properties that may be relevant to carcinogenesis. In other areas, evidence of a relationship between increased HDL-C levels and increased breast cancer risk is either incomplete or contradictory. These areas include obesity (in the risk of postmenopausal breast cancer), use of exogenous hormones (oral contraceptives or postmenopausal estrogens), and physical exercise. In addition, both elevated and depressed levels of HDL-C have been reported in women with breast cancer. Our findings suggest an association between high HDL-C levels and the epidemiology of breast cancer risk. We recommend additional studies of plasma lipid level as a possible risk factor for this disease. PMID:2313717

  2. Electronegative Low-density Lipoprotein Increases Coronary Artery Disease Risk in Uremia Patients on Maintenance Hemodialysis.

    PubMed

    Chang, Chiz-Tzung; Wang, Guei-Jane; Kuo, Chin-Chi; Hsieh, Ju-Yi; Lee, An-Sean; Chang, Chia-Ming; Wang, Chun-Cheng; Shen, Ming-Yi; Huang, Chiu-Ching; Sawamura, Tatsuya; Yang, Chao-Yuh; Stancel, Nicole; Chen, Chu-Huang

    2016-01-01

    Electronegative low-density lipoprotein (LDL) is a recognized factor in the pathogenesis of coronary artery disease (CAD) in the general population, but its role in the development of CAD in uremia patients is unknown. L5 is the most electronegative subfraction of LDL isolated from human plasma. In this study, we examined the distribution of L5 (L5%) and its association with CAD risk in uremia patients.The LDL of 39 uremia patients on maintenance hemodialysis and 21 healthy controls was separated into 5 subfractions, L1-L5, with increasing electronegativity. We compared the distribution and composition of plasma L5 between uremia patients and controls, examined the association between plasma L5% and CAD risk in uremia patients, and studied the effects of L5 from uremia patients on endothelial function.Compared to controls, uremia patients had significantly increased L5% (P < 0.001) and L5 that was rich in apolipoprotein C3 and triglycerides. L5% was significantly higher in uremia patients with CAD (n = 10) than in those without CAD (n = 29) (P < 0.05). Independent of other major CAD risk factors, the adjusted odds ratio for CAD was 1.88 per percent increase in plasma L5% (95% CI, 1.01-3.53), with a near-linear dose-response relationship. Compared with controls, uremia patients had decreased flow-mediated vascular dilatation. In ex vivo studies with preconstricted rat thoracic aortic rings, L5 from uremia patients inhibited acetylcholine-induced relaxation. In cultured human endothelial cells, L5 inhibited endothelial nitric oxide synthase activation and induced endothelial dysfunction.Our findings suggest that elevated plasma L5% may induce endothelial dysfunction and play an important role in the increased risk of CAD in uremia patients. PMID:26765403

  3. Italian Multicenter Study on Low-Density Lipoprotein Apheresis: retrospective analysis (2007).

    PubMed

    Stefanutti, Claudia

    2010-02-01

    A retrospective study--the Italian Multicenter Study on Low-density Lipoprotein Apheresis (IMS-LDLa)--was carried out, which involved 19 centers for LDLa in Italy, distributed all over the country--in the north, center, south, and the major islands. The survey was conducted through two consecutive questionnaires, which can be downloaded online from a dedicated site. The total number of procedures performed until 2007 was 31 012, and the number of patients undergoing treatment until 2007 were 229. The treated patients still surviving consisted of 136 (74 males and 62 females); those surviving but not treated numbered 95, and those deceased numbered 14. The techniques utilized, listed by frequency of use, were the following: dextran sulfate cellulose adsorption, direct adsorption of lipids (DALI), heparin extracorporeal LDL precipitation, immunoadsorption, plasma-exchange, cascade filtration, and Lipocollect 200. The mean treated plasma and blood volumes per session were 3916.5 mL and 8735.1 mL, respectively. The most frequently utilized vascular access points were: venous 84.4% and arteriovenous fistula 15.5%. Hematoma by venipuncture (230 episodes), low outlet flow (125 episodes), and circuit coagulation (44 episodes) were reported as to be the most frequent side effects. In the second questionnaire (filled in by 19 centers) the centers were asked to report their data on: quality diagnosis of dyslipidemia and referents for genetic-molecular and clinical diagnosis, cholesterol-lowering drugs and dosages, typology of cardiovascular check-ups at the beginning of treatment and in follow-up, non-cholesterol-lowering drugs with priority for cardiologic drugs, including oral anti-coagulants, and, lastly, information related to the appropriateness of curing patients still under treatment with LDLa and, where possible, news on patients no longer under treatment. PMID:20438522

  4. Effect of uric acid and chemical analogues on oxidation of human low density lipoprotein in vitro.

    PubMed

    Schlotte, V; Sevanian, A; Hochstein, P; Weithmann, K U

    1998-11-01

    Oxidative modification of low density lipoprotein (LDL) is implicated in the early development of atherosclerosis. In the present study, attention has been focused toward the potential protective effects of uric acid and purine-based chemical analogues in copper-promoted oxidative changes to human LDL in vitro. Between 5-100 mumol/l uric acid protected LDL from oxidative degradation in a concentration dependent manner. However, 5 mumol/l were not capable of inhibiting the consumption of LDLs natural antioxidative components, alpha-tocopherol and beta-carotene, but led to a more than two-fold prolongation, up to 3 h, of the lag phase before onset of polyunsaturated acid (PUFA) oxidation. 100 mumol/l uric acid, which is still below the human serum level of 300 mumol/l, reduced consumption of alpha-tocopherol and beta-carotene by about 50% and largely suppressed PUFA oxidation for up to 4 h. A more lipophilic series of methyl analogues of uric acid exhibited less activity. Neither 1,3-dimethyl uric acid, nor the 1,3,7- or 1,7- or 3,7-methylated compounds, all at 100 mumol/l, exceeded the antioxidative potential of 10 mumol/l uric acid. At concentrations up to 100 mumol/l xanthine and its analogues lacked virtually any protective effects toward the LDL constituents. In conclusion, the present study indicates that uric acid at concentrations similar to its physiological levels, and also related analogues are able to suppress oxidative degradation of LDL components. In view of the various mechanisms underlying atherogenesis in vivo, the protective effect in terms of modulating redox reactions and oxidative events in the blood or at the arterial wall appears of potential importance. PMID:9823550

  5. The advantages of LDL (low density lipoproteins) in the cryopreservation of canine semen.

    PubMed

    Bencharif, D; Amirat, L; Anton, M; Schmitt, E; Desherces, S; Delhomme, G; Langlois, M-L; Barrire, P; Larrat, M; Tainturier, D

    2008-12-01

    A medium containing LDL (Low Density Lipoproteins, the cryoprotective component of chicken egg yolk) was compared with egg yolk for the preservation canine spermatozoa during the freeze-thaw process. Twenty sperm samples taken from 10 dogs were frozen in liquid nitrogen at -196 degrees C in seven different media: one control medium containing 20% egg yolk, and six test media containing 4%, 5%, 6%, 7%, 8%, and 10% LDL, respectively. Following thawing, sperm motility was assessed using a Hamilton-Thorne Sperm Analyser equipped with the CEROS 12 software. The percentage of motile spermatozoa was 55.3% in the 6% LDL medium (optimal concentration) compared with 27.7% in the egg yolk based medium (p<0.05). In comparison with the egg-yolk medium, the LDL medium also resulted in an improved preservation of spermatozoa during the freezing process (p<0.05) in terms of acrosomal integrity (FITC-PSA test), flagellar plasma membrane integrity (HOS test), and DNA integrity (Acridine Orange test). In addition, six Beagle bitches were inseminated twice, via the intra-uterine route, at an interval of 24h; 200x10(6) spermatozoa that had been previously frozen in the 6% LDL medium were used per insemination. All of the bitches became pregnant (gestation rate of 100%). In conclusion, the 6% LDL medium provides improved protection of the spermatozoa during the freeze-thaw process and a marked improvement in the motility parameters of canine spermatozoa in comparison with the control medium containing egg yolk alone. Finally, the use of LDL as a cryoprotectant for canine semen does not interfere with fertility. PMID:18817963

  6. [In vitro oxidation of low density lipoproteins in patients after ischemic stroke].

    PubMed

    Wehr, H; Ryglewicz, D; Rodo, M; Poźniak, M; Swiderska, M; Panczenko, B; Stajniak, A

    2000-01-01

    The aim of this work was the evaluation of low density lipoprotein (LDL) susceptibility to oxidation in the survivors of ischaemic stroke. The investigations were performed in 65 individuals at least three months after the onset of acute symptoms. In 24 patients stroke was caused by alterations in main cerebral arteries, in 19 by considerable narrowing of carotid artery, in 15 by alterations in small cerebral arteries with often accompanying hypertension and/or diabetes (lacunar stroke) and in 7 by embolism of cardiac origin in individuals with cardiac arrhythmia and coronary artery disease. The control group comprised 25 age matched persons without pathological symptoms. Plasma lipids and apolipoprotein B levels were determined as well as two antioxidants: alpha-tocopherol level and superoxide dismutase activity. The evaluation of lipid peroxidation was performed by determining thiobarbituric acid reacting substances (TBARS) and lipid peroxides (LPO) increase after 5 hours oxidation of isolated LDL in vitro in the presence of copper ions. The level of IgG directed against modified LDL was also evaluated. In the patients decreased HDL cholesterol level was observed as well as increased apolipoprotein B. In the group of thrombotic strokes high triglycerides were observed. alpha-tocopherol level was decreased in the group of cerebral strokes. The amounts of oxidation products did not differ between the whole group of patients after stroke and the controls. A significant increase concerned only the group of lacunar strokes. The evaluation of LDL susceptibility to oxidation in patients after stroke by measuring absorption at 234 nm and determining the time period necessary to the onset of intensive LDL oxidation will be the subject of a separate publication. PMID:10979539

  7. Direct Measurement of the Structure of Reconstituted High-Density Lipoproteins by Cryo-EM.

    PubMed

    Murray, Stephen C; Gillard, Baiba K; Ludtke, Steven J; Pownall, Henry J

    2016-02-23

    Early forms of high-density lipoproteins (HDL), nascent HDL, are formed by the interaction of apolipoprotein AI with macrophage and hepatic ATP-binding cassette transporter member 1. Various plasma activities convert nascent to mature HDL, comprising phosphatidylcholine (PC) and cholesterol, which are selectively removed by hepatic receptors. This process is important in reducing the cholesterol burden of arterial wall macrophages, an important cell type in all stages of atherosclerosis. Interaction of apolipoprotein AI with dimyristoyl (DM)PC forms reconstituted (r)HDL, which is a good model of nascent HDL. rHDL have been used as an antiathersclerosis therapy that enhances reverse cholesterol transport in humans and animal models. Thus, identification of the structure of rHDL would inform about that of nascent HDL and how rHDL improves reverse cholesterol transport in an atheroprotective way. Early studies of rHDL suggested a discoidal structure, which included pairs of antiparallel helices of apolipoprotein AI circumscribing a phospholipid bilayer. Another rHDL model based on small angle neutron scattering supported a double superhelical structure. Herein, we report a cryo-electron microscopy-based model of a large rHDL formed spontaneously from apolipoprotein AI, cholesterol, and excess DMPC and isolated to near homogeneity. After reconstruction we obtained an rHDL structure comprising DMPC, cholesterol, and apolipoprotein AI (423:74:1 mol/mol) forming a discoidal particle 360 Å in diameter and 45 Å thick; these dimensions are consistent with the stoichiometry of the particles. Given that cryo-electron microscopy directly observes projections of individual rHDL particles in different orientations, we can unambiguously state that rHDL particles are protein bounded discoidal bilayers. PMID:26743047

  8. Very Low Density Lipoprotein Metabolism in Patients with Chronic Kidney Disease

    PubMed Central

    Wang, Xuewen; Belani, Sharina; Coyne, Daniel W.; Fabbrini, Elisa; Reeds, Dominic N.; Patterson, Bruce W.; Mittendorfer, Bettina; Klein, Samuel

    2012-01-01

    Background Hypertriglyceridemia is a common metabolic complication of chronic kidney disease (CKD) and an important risk factor for coronary heart disease in this patient population. The mechanisms responsible for the development of hypertriglyceridemia in subjects with CKD are not clear. Methods We studied very low density lipoprotein triglyceride (VLDL-TG) and VLDL-apolipoprotein B-100 (VLDL-apoB-100) kinetics in vivo in 6 subjects with non-dialysis-dependent CKD (CKD-ND), 6 subjects with CKD treated with peritoneal dialysis (CKD-PD) and 24 sex-, age- and body mass index-matched control subjects with normal renal function (12 control subjects each matched with the CKD-ND and CKD-PD group, respectively). Results The secretion rates of VLDL-TG and VLDL-apoB-100 into plasma were not different between CKD-ND or CKD-PD and their respective control groups. The mean residence times of VLDL-TG and VLDL-apoB-100 in plasma, which represents the time VLDL-TG and VLDL-apoB-100 spend in the circulation after secretion by the liver, tended to be greater in subjects with CKD-ND than in control subjects (222 ± 38 vs. 143 ± 21 min, p = 0.07, and 352 ± 102 vs. 200 ± 20 min, p = 0.06, respectively) and were about two-fold greater in subjects with CKD-PD compared with their control group (248 ± 51 vs. 143 ± 21 min and 526 ± 116 vs. 182 ± 16 min, respectively; both p ≤ 0.01). Conclusion Impaired plasma clearance of VLDL-TG and VLDL-apoB-100 is the major abnormality associated with hypertriglyceridemia in patients with either CKD-ND or CKD-PD. PMID:22493604

  9. Agonistic Human Antibodies Binding to Lecithin-Cholesterol Acyltransferase Modulate High Density Lipoprotein Metabolism*

    PubMed Central

    Gunawardane, Ruwanthi N.; Fordstrom, Preston; Piper, Derek E.; Masterman, Stephanie; Siu, Sophia; Liu, Dongming; Brown, Mike; Lu, Mei; Tang, Jie; Zhang, Richard; Cheng, Janet; Gates, Andrew; Meininger, David; Chan, Joyce; Carlson, Tim; Walker, Nigel; Schwarz, Margrit; Delaney, John; Zhou, Mingyue

    2016-01-01

    Drug discovery opportunities where loss-of-function alleles of a target gene link to a disease-relevant phenotype often require an agonism approach to up-regulate or re-establish the activity of the target gene. Antibody therapy is increasingly recognized as a favored drug modality due to multiple desirable pharmacological properties. However, agonistic antibodies that enhance the activities of the target enzymes are rarely developed because the discovery of agonistic antibodies remains elusive. Here we report an innovative scheme of discovery and characterization of human antibodies capable of binding to and agonizing a circulating enzyme lecithin cholesterol acyltransferase (LCAT). Utilizing a modified human LCAT protein with enhanced enzymatic activity as an immunogen, we generated fully human monoclonal antibodies using the XenoMouseTM platform. One of the resultant agonistic antibodies, 27C3, binds to and substantially enhances the activity of LCAT from humans and cynomolgus macaques. X-ray crystallographic analysis of the 2.45 Å LCAT-27C3 complex shows that 27C3 binding does not induce notable structural changes in LCAT. A single administration of 27C3 to cynomolgus monkeys led to a rapid increase of plasma LCAT enzymatic activity and a 35% increase of the high density lipoprotein cholesterol that was observed up to 32 days after 27C3 administration. Thus, this novel scheme of immunization in conjunction with high throughput screening may represent an effective strategy for discovering agonistic antibodies against other enzyme targets. 27C3 and other agonistic human anti-human LCAT monoclonal antibodies described herein hold potential for therapeutic development for the treatment of dyslipidemia and cardiovascular disease. PMID:26644477

  10. Low-Density-Lipoprotein Particle Size Predicts a Poor Outcome in Patients with Atherothrombotic Stroke

    PubMed Central

    Song, Tae-Jin; Cho, Hyun-Ji; Chang, Yoonkyung; Youn, Minjung; Shin, Min-Jeong; Jo, Inho; Heo, Ji Hoe

    2015-01-01

    Background and Purpose Low-density lipoprotein (LDL) particle size is considered to be one of the more important cardiovascular risk factors, and small LDL particles are known to have atherogenic potential. The aim of this study was to determine whether LDL particle size is associated with stroke severity and functional outcome in patients with atherothrombotic stroke. Methods Between January 2009 and May 2011, 248 patients with first-episode cerebral infarction who were admitted to our hospital within 7 days after symptom onset were prospectively enrolled. LDL particle size was measured using the nondenaturing polyacrylamide gradient gel electrophoresis assay. Stroke severity was assessed by applying the National Institutes of Health Stroke Scale (NIHSS) at admission. Functional outcome was investigated at 3 months after the index stroke using the modified Rankin Scale (mRS), and poor functional outcome was defined as an mRS score of ≥3. Results The LDL particle size in the 248 patients was 25.9±0.9 nm (mean±SD). LDL particle size was inversely correlated with the degree of cerebral artery stenosis (p=0.010). Multinomial multivariate logistic analysis revealed that after adjustment for age, sex, and variables with p<0.1 in univariate analysis, LDL particle size was independently and inversely associated with stroke severity (NIHSS score ≥5; reference, NIHSS score 0-2; odds ratio=0.38, p=0.028) and poor functional outcome (odds ratio=0.44, p=0.038). Conclusions The results of this study demonstrate that small LDL particles are independently correlated with stroke outcomes. LDL particle size is thus a potential biomarker for the prognosis of atherothrombotic stroke. PMID:25628741

  11. Does high-density lipoprotein protect vascular function in healthy pregnancy?

    PubMed

    Sulaiman, Wan N Wan; Caslake, Muriel J; Delles, Christian; Karlsson, Helen; Mulder, Monique T; Graham, Delyth; Freeman, Dilys J

    2016-04-01

    The maternal adaptation to pregnancy includes hyperlipidaemia, oxidative stress and chronic inflammation. In non-pregnant individuals, these processes are usually associated with poor vascular function. However, maternal vascular function is enhanced in pregnancy. It is not understood how this is achieved in the face of the adverse metabolic and inflammatory environment. Research into cardiovascular disease demonstrates that plasma HDL (high-density lipoprotein), by merit of its functionality rather than its plasma concentration, exerts protective effects on the vascular endothelium. HDL has vasodilatory, antioxidant, anti-thrombotic and anti-inflammatory effects, and can protect against endothelial cell damage. In pregnancy, the plasma HDL concentration starts to rise at 10 weeks of gestation, peaking at 20 weeks. The initial rise in plasma HDL occurs around the time of the establishment of the feto-placental circulation, a time when the trophoblast plugs in the maternal spiral arteries are released, generating oxidative stress. Thus there is the intriguing possibility that new HDL of improved function is synthesized around the time of the establishment of the feto-placental circulation. In obese pregnancy and, to a greater extent, in pre-eclampsia, plasma HDL levels are significantly decreased and maternal vascular function is reduced. Wire myography studies have shown an association between the plasma content of apolipoprotein AI, the major protein constituent of HDL, and blood vessel relaxation. These observations lead us to hypothesize that HDL concentration, and function, increases in pregnancy in order to protect the maternal vascular endothelium and that in pre-eclampsia this fails to occur. PMID:26888561

  12. Elevated high-density lipoprotein cholesterol and cardiovascular mortality in maintenance hemodialysis patients

    PubMed Central

    Moradi, Hamid; Streja, Elani; Kashyap, Moti L.; Vaziri, Nosratola D.; Fonarow, Gregg C.; Kalantar-Zadeh, Kamyar

    2014-01-01

    Background High-density lipoprotein (HDL) confers protection against atherosclerosis by several different mechanisms. Although in the general population, increasing levels of HDL are associated with reduced cardiovascular (CV) mortality, this association is not well known in patients with chronic disease states such as end-stage renal disease. We hypothesize that the association of serum HDL concentration and its ratio to total cholesterol with all-cause and CV mortality in hemodialysis patients is different from the general population. Methods A 3-year (July 2004 to June 2007) cohort of 33 109 chronic hemodialysis patients was studied in the USA in the dialysis clinics where lipid profile was measured in at least 50% of all outpatients of the clinic during a given calendar quarter. Cox proportional hazard models were adjusted for demographics and casemix variables and cubic splines were plotted. Results Higher HDL concentrations up to 50 mg/dL were associated with better overall survival, while HDL at 60 mg/dL and above was associated with a rise in all-cause and CV mortality. All-cause and CV mortality hazard ratio was 1.28 (1.201.38) and 1.08 (1.011.16) for HDL <30 mg/dL and 1.05 (1.001.10) and 1.08 (1.001.16) for HDL ? 60 mg/dL, respectively (reference: HDL: 30<60 mg/dL). Conclusions In contrast to the general population, low total cholesterol to HDL ratio was associated with higher mortality in hemodialysis patients. A U-shaped association between HDL cholesterol level and all-cause and CV mortality exists in hemodialysis patients with HDL between 50 and <60 mg/dL exhibiting the best survival. The underlying mechanisms responsible for these seemingly paradoxical associations await further investigation. PMID:24574544

  13. Automated detection and tracking of individual and clustered cell surface low density lipoprotein receptor molecules.

    PubMed

    Ghosh, R N; Webb, W W

    1994-05-01

    We have developed a technique to detect, recognize, and track each individual low density lipoprotein receptor (LDL-R) molecule and small receptor clusters on the surface of human skin fibroblasts. Molecular recognition and high precision (30 nm) simultaneous automatic tracking of all of the individual receptors in the cell surface population utilize quantitative time-lapse low light level digital video fluorescence microscopy analyzed by purpose-designed algorithms executed on an image processing work station. The LDL-Rs are labeled with the biologically active, fluorescent LDL derivative dil-LDL. Individual LDL-Rs and unresolved small clusters are identified by measuring the fluorescence power radiated by the sub-resolution fluorescent spots in the image; identification of single particles is ascertained by four independent techniques. An automated tracking routine was developed to track simultaneously, and without user intervention, a multitude of fluorescent particles through a sequence of hundreds of time-lapse image frames. The limitations on tracking precision were found to depend on the signal-to-noise ratio of the tracked particle image and mechanical drift of the microscope system. We describe the methods involved in (i) time-lapse acquisition of the low-light level images, (ii) simultaneous automated tracking of the fluorescent diffraction limited punctate images, (iii) localizing particles with high precision and limitations, and (iv) detecting and identifying single and clustered LDL-Rs. These methods are generally applicable and provide a powerful tool to visualize and measure dynamics and interactions of individual integral membrane proteins on living cell surfaces. PMID:8061186

  14. Polymer-coated pH-responsive high-density lipoproteins.

    PubMed

    Kim, Hyungjin; Okamoto, Haruki; Felber, Arnaud E; Polomska, Anna; Morone, Nobuhiro; Heuser, John E; Leroux, Jean-Christophe; Murakami, Tatsuya

    2016-04-28

    Intracellular drug delivery by nanoparticles is often hampered by their endosomal entrapment followed by their degradation in the lysosomal compartment and/or exocytosis. Here, we show that internalization and endosomal escape of cargoes in a cationized natural nanocarrier, high-density lipoprotein (HDL), can be controlled in a pH-dependent manner through stable complexation with a membranolytic anionic block polymer. A genetically and chemically cationized form of HDL (catHDL) is prepared for the first time by both genetic fusion with YGRKKRRQRRR peptide and incorporation of 1,2-dioleoyloxy-3-(trimethylammonium)propane. Upon addition of poly(ethylene glycol)-block-poly(propyl methacrylate-co-methacrylic acid) (PA), catHDL yields inhibition of internalization at neutral pH and its subsequent recovery at mildly acidic pH. catHDL forms a stable discoidal-shape complex with PA (catHDL/PA) (ca. 50nm in diameter), even in the presence of serum. Significant enhancement of endosomal escape of a catHDL component is observed after a 1-h treatment of human cancer cells with catHDL/PA. Doxorubicin and curcumin, fluorescent anti-cancer drugs, encapsulated into catHDL/PA are also translocated outside of endosomes, compared with that into catHDL, and their cytotoxicities are enhanced inside the cells. These data suggest that catHDL/PA may have a potential benefit to improve the cellular delivery and endosomal escape of therapeutics under mildly acidic conditions such as in tumor tissues. PMID:26959846

  15. Low Density Lipoprotein Receptor Class A Repeats Are O-Glycosylated in Linker Regions*

    PubMed Central

    Pedersen, Nis Borbye; Wang, Shengjun; Narimatsu, Yoshiki; Yang, Zhang; Halim, Adnan; Schjoldager, Katrine Ter-Borch Gram; Madsen, Thomas Daugbjerg; Seidah, Nabil G.; Bennett, Eric Paul; Levery, Steven B.; Clausen, Henrik

    2014-01-01

    The low density lipoprotein receptor (LDLR) is crucial for cholesterol homeostasis and deficiency in LDLR functions cause hypercholesterolemia. LDLR is a type I transmembrane protein that requires O-glycosylation for stable expression at the cell surface. It has previously been suggested that LDLR O-glycosylation is found N-terminal to the juxtamembrane region. Recently we identified O-glycosylation sites in the linker regions between the characteristic LDLR class A repeats in several LDLR-related receptors using the “SimpleCell” O-glycoproteome shotgun strategy. Herein, we have systematically characterized O-glycosylation sites on recombinant LDLR shed from HEK293 SimpleCells and CHO wild-type cells. We find that the short linker regions between LDLR class A repeats contain an evolutionarily conserved O-glycosylation site at position −1 of the first cysteine residue of most repeats, which in wild-type CHO cells is glycosylated with the typical sialylated core 1 structure. The glycosites in linker regions of LDLR class A repeats are conserved in LDLR from man to Xenopus and found in other homologous receptors. O-Glycosylation is controlled by a large family of polypeptide GalNAc transferases. Probing into which isoform(s) contributed to glycosylation of the linker regions of the LDLR class A repeats by in vitro enzyme assays suggested a major role of GalNAc-T11. This was supported by expression of LDLR in HEK293 cells, where knock-out of the GalNAc-T11 isoform resulted in the loss of glycosylation of three of four linker regions. PMID:24798328

  16. Hepatic and very low-density lipoprotein fatty acids in obese offspring of overfed dams.

    PubMed

    Bouanane, Samira; Merzouk, Hafida; Benkalfat, Nacira Batoul; Soulimane, Nassima; Merzouk, Sid Ahmed; Gresti, Joseph; Tessier, Christian; Narce, Michel

    2010-12-01

    The combined effects of developmental programming and high-fat feeding at weaning on fatty acid metabolism of the offspring are not well known. In the present study, we aim at characterizing the influence of maternal and offspring's own diets on liver and very low-density lipoprotein (VLDL) lipids; fatty acid profiles of VLDL and liver phospholipids, triglycerides, and cholesteryl esters; and hepatic enzyme activities. Twenty obese male rats born to cafeteria diet-fed dams and 20 control rats born to control diet-fed dams were selected. At weaning, 10 rats of each group were fed control or cafeteria diet. Obese rats had a significant increase in serum glucose, insulin, leptin, VLDL apolipoprotein B100 and lipid levels, and hepatic fatty acid synthase and a reduction in acyl-coenzyme A oxidase and dehydrogenase activities compared with control pups at day 21 and day 90. Hepatic steatosis was apparent only at day 90. The proportions of saturated fatty acids and monounsaturated fatty acids and the oleic to stearic acid ratio were significantly increased, whereas polyunsaturated fatty acids and the arachidonic to linoleic acid ratio were decreased, in liver and VLDL lipids of obese pups compared with controls. The cafeteria diet at weaning induced more severe abnormalities in obese rats. In conclusion, maternal cafeteria diet induced a permanent reduction in hepatic β-oxidation and an increase in hepatic lipogenesis that caused liver steatosis and VLDL and fatty acid alterations in adult offspring. These preexisting alterations in offspring were worsened under a high-fat diet from weaning to adulthood. Nutritional recommendations in obesity must then target maternal and postnatal nutrition, especially fatty acid composition. PMID:20494379

  17. CD36 Binds Oxidized Low Density Lipoprotein (LDL) in a Mechanism Dependent upon Fatty Acid Binding*

    PubMed Central

    Jay, Anthony G.; Chen, Alexander N.; Paz, Miguel A.; Hung, Justin P.; Hamilton, James A.

    2015-01-01

    The association of unesterified fatty acid (FA) with the scavenger receptor CD36 has been actively researched, with focuses on FA and oxidized low density lipoprotein (oxLDL) uptake. CD36 has been shown to bind FA, but this interaction has been poorly characterized to date. To gain new insights into the physiological relevance of binding of FA to CD36, we characterized FA binding to the ectodomain of CD36 by the biophysical method surface plasmon resonance. Five structurally distinct FAs (saturated, monounsaturated (cis and trans), polyunsaturated, and oxidized) were pulsed across surface plasmon resonance channels, generating association and dissociation binding curves. Except for the oxidized FA HODE, all FAs bound to CD36, with rapid association and dissociation kinetics similar to HSA. Next, to elucidate the role that each FA might play in CD36-mediated oxLDL uptake, we used a fluorescent oxLDL (Dii-oxLDL) live cell assay with confocal microscopy imaging. CD36-mediated uptake in serum-free medium was very low but greatly increased when serum was present. The addition of exogenous FA in serum-free medium increased oxLDL binding and uptake to levels found with serum and affected CD36 plasma membrane distribution. Binding/uptake of oxLDL was dependent upon the FA dose, except for docosahexaenoic acid, which exhibited binding to CD36 but did not activate the uptake of oxLDL. HODE also did not affect oxLDL uptake. High affinity FA binding to CD36 and the effects of each FA on oxLDL uptake have important implications for protein conformation, binding of other ligands, functional properties of CD36, and high plasma FA levels in obesity and type 2 diabetes. PMID:25555908

  18. High-density lipoprotein-cholesterol: determining hygienic factors for intervention.

    PubMed

    Anzalone, D A; Anzalone, F L; Fos, P J

    1995-07-01

    Current guidelines of the Adult Treatment Panel on High-Density Lipoprotein-Cholesterol (HDL-C) emphasize the protective effect of HDL-C in reducing one's risk for coronary heart disease and recommend that individuals with serum HDL-C levels below 35 mg/dL utilize hygienic means to raise them. A cross-sectional study was performed to examine the relationship of the hygienic factors obesity (measured by percent body fat and body mass index), smoking, and aerobic exercise to HDL-C. The sample, consisting of 1701 male employees of a large aerospace hardware assembly plant, were evaluated by health risk appraisal and anthropometric measurement. Regression analysis revealed a significant negative relationship between body mass index, percent body fat, age, smoking and the level of HDL-C in the blood. Alcohol consumption was directly related to HDL-C, and Whites had a lower HDL-C than all other races combined. Aerobic exercise was not found to be significantly related to HDL-C. A model (multiple R2 = .1136) consisting of age, race, alcohol consumption, smoking, and body mass index fit the data well. These findings justify weight management and smoking cessation interventions for raising HDL-C. However, the role of aerobic exercise was not supported in this study as a means of raising HDL-C. Future studies should use maximum oxygen consumption as a measure of aerobic capacity, which may be a better indicator of aerobic exercise level. The role of medication and genetic and dietary factors in HDL-C management should also be explored. Although findings from this study support smoking cessation and weight management interventions, longitudinal research is needed to determine the most effective strategy for HDL-C management. PMID:7552471

  19. Dysregulation of low-density lipoprotein receptor contributes to podocyte injuries in diabetic nephropathy.

    PubMed

    Zhang, Yang; Ma, Kun Ling; Liu, Jing; Wu, Yu; Hu, Ze Bo; Liu, Liang; Liu, Bi Cheng

    2015-06-15

    Dyslipidemia plays crucial roles in the progression of diabetic nephropathy (DN). This study investigated the effects of high glucose on lipid accumulation in podocytes and explored its underlying mechanisms. Male db/m and db/db mice were fed a normal chow diet for 8 wk. Immortalised mouse podocytes were treated with or without high glucose for 24 h. The changes to the morphology and ultramicrostructures of the kidneys in mice were examined using pathological staining and electron microscopy. Intracellular lipid accumulation was evaluated by Oil Red O staining and a free cholesterol quantitative assay. The expressions of the molecules involved in low-density lipoprotein receptor (LDLr) pathway and podocyte injury were examined using immunofluorescent staining, real-time PCR, and Western blot. There were increased levels of plasma lipid, serum creatinine, and proteinuria in db/db mice compared with db/m mice. Moreover, there was significant mesangial matrix expansion, basement membrane thickening, podocyte foot process effacement, and phenotypic alteration in the db/db group. Additionally, lipid accumulation in the kidneys of db/db mice was increased due to increased protein expressions of LDLr, sterol regulatory element-binding protein (SREBP) cleavage-activating protein, and SREBP-2. These effects were further confirmed by in vitro studies. Interestingly, the treatment with LDLr siRNA inhibited lipid accumulation in podocytes and decreased the protein expression of molecules associated with phenotypic alteration in podocytes. High glucose disrupted LDLr feedback regulation in podocytes, which may cause intracellular lipid accumulation and alteration of podocyte phenotype, thereby accelerating DN progression. PMID:25921580

  20. Mimicry of High-Density Lipoprotein: Functional Peptide–Lipid Nanoparticles Based on Multivalent Peptide Constructs

    PubMed Central

    Zhao, Yannan; Imura, Tomohiro; Leman, Luke J.; Curtiss, Linda K.; Maryanoff, Bruce E.; Ghadiri, M. Reza

    2013-01-01

    We describe an approach for engineering peptide–lipid nanoparticles that function similarly to high-density lipoprotein (HDL). Branched, multivalent constructs, bearing multiple 23- or 16-amino-acid peptides, were designed, synthesized and combined with phospholipids to produce nanometer-scale discoidal HDL-like particles. A variety of biophysical techniques were employed to characterize the constructs, including size exclusion chromatography, analytical ultracentrifuge sedimentation, circular dichroism, transmission electron microscopy, and fluorescence spectroscopy. The nanoparticles functioned in vitro (human and mouse plasma) and in vivo (mice) to rapidly remodel large native HDLs into small lipid-poor HDL particles, which are key acceptors of cholesterol in reverse cholesterol transport. Fluorescent labeling studies showed that the constituents of the nanoparticles readily distributed into native HDLs, such that the peptide constructs coexisted with apolipoprotein A-I, the main structural protein in HDLs. Importantly, nanolipid particles containing multivalent peptides promoted efficient cellular cholesterol efflux and were functionally superior to those derived from monomeric peptides. The multivalent peptide-lipid nanoparticles were also remarkably stable toward enzymatic digestion in vitro and displayed long half-lives and desirable pharmacokinetic profiles in mice, providing a real practical advantage over previously studied linear or tandem helical peptides. Encouragingly, a two-week exploratory efficacy study in a widely used animal model for atherosclerosis research (LDLr-null mice) using nanoparticles constructed from a trimeric peptide demonstrated an exceptional 50% reduction in the plasma total cholesterol levels compared to the control group. Altogether, the studies reported here point to an attractive avenue for designing synthetic, HDL-like nanoparticles, with potential for treating atherosclerosis. PMID:23978057

  1. High Density Lipoprotein Structure–Function and Role in Reverse Cholesterol Transport

    PubMed Central

    Lund-Katz, Sissel

    2011-01-01

    High density lipoprotein (HDL) possesses important anti-atherogenic properties and this review addresses the molecular mechanisms underlying these functions. The structures and cholesterol transport abilities of HDL particles are determined by the properties of their exchangeable apolipoprotein (apo) components. ApoA-I and apoE, which are the best characterized in structural terms, contain a series of amphipathic α-helical repeats. The helices located in the amino-terminal two-thirds of the molecule adopt a helix bundle structure while the carboxy-terminal segment forms a separately folded, relatively disorganized, domain. The latter domain initiates lipid binding and this interaction induces changes in conformation; the α-helix content increases and the amino-terminal helix bundle can open subsequently. These conformational changes alter the abilities of apoA-I and apoE to function as ligands for their receptors. The apoA-I and apoE molecules possess detergent-like properties and they can solubilize vesicular phospholipid to create discoidal HDL particles with hydrodynamic diameters of ~10 nm. In the case of apoA-I, such a particle is stabilized by two protein molecules arranged in an anti-parallel, double-belt, conformation around the edge of the disc. The abilities of apoA-I and apoE to solubilize phospholipid and stabilize HDL particles enable these proteins to be partners with ABCA1 in mediating efflux of cellular phospholipid and cholesterol, and the biogenesis of HDL particles. ApoA-I-containing nascent HDL particles play a critical role in cholesterol transport in the circulation whereas apoE-containing HDL particles mediate cholesterol transport in the brain. The mechanisms by which HDL particles are remodeled by lipases and lipid transfer proteins, and interact with SR-BI to deliver cholesterol to cells, are reviewed. PMID:20213545

  2. Electronegative Low-density Lipoprotein Increases Coronary Artery Disease Risk in Uremia Patients on Maintenance Hemodialysis

    PubMed Central

    Chang, Chiz-Tzung; Wang, Guei-Jane; Kuo, Chin-Chi; Hsieh, Ju-Yi; Lee, An-Sean; Chang, Chia-Ming; Wang, Chun-Cheng; Shen, Ming-Yi; Huang, Chiu-Ching; Sawamura, Tatsuya; Yang, Chao-Yuh; Stancel, Nicole; Chen, Chu-Huang

    2016-01-01

    Abstract Electronegative low-density lipoprotein (LDL) is a recognized factor in the pathogenesis of coronary artery disease (CAD) in the general population, but its role in the development of CAD in uremia patients is unknown. L5 is the most electronegative subfraction of LDL isolated from human plasma. In this study, we examined the distribution of L5 (L5%) and its association with CAD risk in uremia patients. The LDL of 39 uremia patients on maintenance hemodialysis and 21 healthy controls was separated into 5 subfractions, L1–L5, with increasing electronegativity. We compared the distribution and composition of plasma L5 between uremia patients and controls, examined the association between plasma L5% and CAD risk in uremia patients, and studied the effects of L5 from uremia patients on endothelial function. Compared to controls, uremia patients had significantly increased L5% (P < 0.001) and L5 that was rich in apolipoprotein C3 and triglycerides. L5% was significantly higher in uremia patients with CAD (n = 10) than in those without CAD (n = 29) (P < 0.05). Independent of other major CAD risk factors, the adjusted odds ratio for CAD was 1.88 per percent increase in plasma L5% (95% CI, 1.01–3.53), with a near-linear dose–response relationship. Compared with controls, uremia patients had decreased flow-mediated vascular dilatation. In ex vivo studies with preconstricted rat thoracic aortic rings, L5 from uremia patients inhibited acetylcholine-induced relaxation. In cultured human endothelial cells, L5 inhibited endothelial nitric oxide synthase activation and induced endothelial dysfunction. Our findings suggest that elevated plasma L5% may induce endothelial dysfunction and play an important role in the increased risk of CAD in uremia patients. PMID:26765403

  3. Low-density lipoprotein receptor–related protein 5 governs Wnt-mediated osteoarthritic cartilage destruction

    PubMed Central

    2014-01-01

    Introduction Wnt ligands bind to low-density lipoprotein receptor–related protein (LRP) 5 or 6, triggering a cascade of downstream events that include β-catenin signaling. Here we explored the roles of LRP5 in interleukin 1β (IL-1β)- or Wnt-mediated osteoarthritic (OA) cartilage destruction in mice. Methods The expression levels of LRP5, type II collagen, and catabolic factors were determined in mouse articular chondrocytes, human OA cartilage, and mouse experimental OA cartilage. Experimental OA in wild-type, Lrp5 total knockout (Lrp5-/-) and chondrocyte-specific knockout (Lrp5fl/fl;Col2a1-cre) mice was caused by aging, destabilization of the medial meniscus (DMM), or intra-articular injection of collagenase. The role of LRP5 was confirmed in vitro by small interfering RNA–mediated knockdown of Lrp5 or in Lrp5-/- cells treated with IL-1β or Wnt proteins. Results IL-1β treatment increased the expression of LRP5 (but not LRP6) via JNK and NF-κB signaling. LRP5 was upregulated in human and mouse OA cartilage, and Lrp5 deficiency in mice inhibited cartilage destruction. Treatment with IL-1β or Wnt decreased the level of Col2a1 and increased those of Mmp3 or Mmp13, whereas Lrp5 knockdown ameliorated these effects. In addition, we found that the functions of LRP5 in arthritic cartilage were subject to transcriptional activation by β-catenin. Moreover, Lrp5-/- and Lrp5fl/fl;Col2a1-cre mice exhibited decreased cartilage destruction (and related changes in gene expression) in response to experimental OA. Conclusions Our findings indicate that LRP5 (but not LRP6) plays an essential role in Wnt/β-catenin-signaling-mediated OA cartilage destruction in part by regulating the expression levels of type II collagen, MMP3, and MMP13. PMID:24479426

  4. Roles of High-Density Lipoprotein Cholesterol in Patients With Acute Myocardial Infarction.

    PubMed

    Lee, Cheol Hyun; Woo, Jong Shin; Park, Chang Bum; Cho, Jin Man; Ahn, Young Keun; Kim, Chong Jin; Jeong, Myung Ho; Kim, Weon

    2016-05-01

    Many observational studies showed hogh-density lipoprotein cholesterol (HDL-C) is a strong inverse predictor of cardiovascular (CV) outcome. However, recent large clinical trials evaluating therapies to raise HDL-C level in those already on statin therapy have been discouraging. This complexity is not well-known.A total of 28,357 acute myocardial infarction (AMI) patients were enrolled in the Korea Acute Myocardial Infarction Registry (KAMIR), which was a prospective, multicenter, nationwide, web-based database of AMI in Korea. From this registry, we evaluated 3574 patients with AMI who have follow-up HDL-C level to investigate its association with clinical outcomes. The primary endpoint was the relationship between follow-up change in HDL-C and a 12-month composite of major adverse cardiac events (MACEs).Patients with initial HDL-C ≥ 40 mg/dL showed significantly lower rates of 12-month MACEs, especially cardiac and all-cause mortalities (P < 0.001). When patients were stratified into 4 groups according to the change of HDL-C, patients with decreasing HDL-C showed significantly higher rates of 12-month MACEs as comparable with patients with increasing HLD-C. A multivariate analysis indicated that HDL-C level was a significant predictor of CV events (hazard ratio, 1.38; 95% confidence interval, 1.12-1.71) after correcting for confounding variables.The follow-up change in HDL-C level was significantly related with CV outcomes in patients with AMI. PMID:27149442

  5. Complement C1q Reduces Early Atherosclerosis in Low-Density Lipoprotein Receptor-Deficient Mice

    PubMed Central

    Bhatia, Vinay K.; Yun, Sheng; Leung, Viola; Grimsditch, David C.; Benson, G. Martin; Botto, Marina B.; Boyle, Joseph J.; Haskard, Dorian O.

    2007-01-01

    We explored the role of the classic complement pathway in atherogenesis by intercrossing C1q-deficient mice (C1qa−/−) with low-density lipoprotein receptor knockout mice (Ldlr−/−). Mice were fed a normal rodent diet until 22 weeks of age. Aortic root lesions were threefold larger in C1qa−/−/Ldlr−/− mice compared with Ldlr−/− mice (3.72 ± 1.0% aortic root versus 1.1 ± 0.4%; mean ± SEM, P < 0.001). Furthermore, the cellular composition of lesions in C1qa−/−/Ldlr−/− was more complex, with an increase in vascular smooth muscle cells. The greater aortic root lesion size in C1qa−/−/Ldlr−/− mice occurred despite a significant reduction in C5b-9 deposition per lesion unit area, suggesting the critical importance of proximal pathway activity. Apoptotic cells were readily detectable by cleaved caspase-3 staining, terminal deoxynucleotidyl transferase dUTP nick-end labeling assay, and electron microscopy in C1qa−/−/Ldlr−/−, whereas apoptotic cells were not detected in Ldlr−/− mice. This is the first direct demonstration of a role for the classic complement pathway in atherogenesis. The greater lesion size in C1qa−/−/Ldlr−/− mice is consistent with the emerging homeostatic role for C1q in the disposal of dying cells. This study suggests the importance of effective apoptotic cell removal for containing the size and complexity of early lesions in atherosclerosis. PMID:17200212

  6. Drinking deep seawater decreases serum total and low-density lipoprotein-cholesterol in hypercholesterolemic subjects.

    PubMed

    Fu, Zhao-Yang; Yang, Feili Lo; Hsu, Hsin-Wen; Lu, Yi-Fa

    2012-06-01

    Drinking deep seawater (DSW) with high levels of magnesium (Mg) decreased serum lipids in animal studies. Therefore the effects of drinking DSW on blood lipids and its antioxidant capacity in hypercholesterolemic subjects were investigated. DSW was first prepared by a process of filtration and reverse osmosis, and then the concentrated DSW with high levels of Mg was diluted as drinking DSW. Forty-two hypercholesterolemic volunteers were randomly divided into three groups: reverse osmotic (RO) water, DSW (Mg: 395 mg/L, hardness 1410 ppm), and magnesium-chloride fortified (MCF) water (Mg: 386 mg/L, hardness 1430 ppm). The subjects drank 1050 mL of water daily for 6 weeks, and blood samples were collected and analyzed on weeks 0, 3, and 6. Drinking DSW caused a decrease in blood total cholesterol levels and this effect was progressively enhanced with time. Serum low-density lipoprotein-cholesterol (LDL-C) was also decreased by DSW. Further, total cholesterol levels of subjects in the DSW group were significantly lower than those in the MCF water or RO water groups. Compared with week 0, the DSW group had higher blood Mg level on weeks 3 and 6, but the Mg levels were within the normal range in all three groups. DSW consumption also lowered thiobarbituric acid-reactive substances (TBARS) values in serum. In conclusion, DSW was apparently effective in reducing blood total cholesterol and LDL-C, and also in decreasing lipid peroxidation in hypercholesterolemic subjects. PMID:22424458

  7. Glycomic analysis of high density lipoprotein shows a highly sialylated particle.

    PubMed

    Huang, Jincui; Lee, Hyeyoung; Zivkovic, Angela M; Smilowitz, Jennifer T; Rivera, Nancy; German, J Bruce; Lebrilla, Carlito B

    2014-02-01

    Many of the functional proteins and lipids in high density lipoprotein (HDL) particles are potentially glycosylated, yet very little is known about the glycoconjugates of HDL. In this study, HDL was isolated from plasma by sequential micro-ultracentrifugation, followed by glycoprotein and glycolipid analysis. N-Glycans, glycopeptides, and gangliosides were extracted and purified followed by analysis with nano-HPLC Chip quadrupole time of flight mass spectrometry and MS/MS. HDL particles were found to be highly sialylated. Most of the N-glycans (∼90%) from HDL glycoproteins were sialylated with one or two neuraminic acids (Neu5Ac). The most abundant N-glycan was a biantennary complex type glycan with two sialic acids (Hexose5HexNAc4Neu5Ac2) and was found in multiple glycoproteins using site-specific glycosylation analysis. The observed O-glycans were all sialylated, and most contained a core 1 structure with two Neu5Acs, including those that were associated with apolipoprotein CIII (ApoC-III) and fetuin A. GM3 (monosialoganglioside, NeuAc2-3Gal1-4Glc-Cer) and GD3 (disialoganglioside, NeuAc2-8NeuAc2-3Gal1-4Glc-Cer) were the major gangliosides in HDL. A 60% GM3 and 40% GD3 distribution was observed. Both GM3 and GD3 were composed of heterogeneous ceramide lipid tails, including d18:1/16:0 and d18:1/23:0. This report describes for the first time a glycomic approach for analyzing HDL, highlighting that HDL are highly sialylated particles. PMID:24417605

  8. Relation between high density lipoprotein cholesterol and coronary artery disease in asymptomatic men

    SciTech Connect

    Uhl, G.S.; Troxler, R.G.; Hickman, J.R. Jr.; Clark, D.

    1981-11-01

    The well established inverse relation of high density lipoprotein cholesterol (HDL) and the risk of coronary artery disease was tested in a cross-sectional group of 572 asymptomatic aircrew members who were being screened for risk of coronary artery disease. A battery of tests was performed, including determinations of fasting serum cholesterol, HDL cholesterol and triglycerides and performance of a maximal symptom-limited exercise tolerance test. Of the 572 patients, 132 also had an abnormal S-T segment response to exercise testing or were otherwise believed to have an increased risk of organic heart disease and subsequently underwent coronary angiography. Significant coronary artery disease was found in 16 men and minimal or subcritical coronary disease in 14; coronary angiograms were normal in the remaining 102 men. The remaining 440 men, who were believed to have a 1 percent chance of having coronary artery disease by sequential testing of risk factors and treadmill testing, had a mean cholesterol level of 213 mg/100 ml, a mean HDL cholesterol of 51 mg/100 ml and a mean cholesterol/HDL ratio of 4.4. The mean values of cholesterol, HDL cholesterol and cholesterol/HDL cholesterol did not differ significantly in men with normal angiographic finding and those with subcritical coronary disease. However, 14 of 16 men with coronary artery disease had a cholesterol/HDL ratio of 6.0 or more whereas only 4 men with normal coronary arteries had a ratio of 6.0 or more. Of the classical coronary risk factors evaluated, the cholesterol/HDL ratio of 6.0 or more had the highest odds ratio (172:1). It appears that determination of HDL cholesterol level helps to identify asymptomatic persons with a greater risk of having coronary artery disease.

  9. Nerve growth factor-mediated regulation of low density lipoprotein receptor-related protein promoter activation.

    PubMed

    Grana, Tomas R; LaMarre, Jonathan; Kalisch, Bettina E

    2013-03-01

    The mechanisms by which nerve growth factor (NGF) increases the level of low density lipoprotein receptor-related protein (LRP1) are not known. Administration of nitric oxide synthase (NOS) inhibitors modulates several of the neurotrophic actions of NGF, including TrkA signalling pathway activation, increases in gene expression and neurite outgrowth. The present study investigated whether NGF regulates the transcription of LRP1 as well as the role of NO and the individual TrkA signalling pathways in this action of NGF. PC12 cells were transfected with luciferase reporter constructs containing various sized fragments of the LRP1 promoter and treated with NGF (50 ng/mL) to establish whether NGF altered LRP transcription. NGF significantly increased luciferase activity in all LRP1 promoter construct-transfected cells with the NGF-responsive region of the promoter identified to be present in the first 1000 bp. The non-selective NOS inhibitor N(ω)-nitro-L-arginine methylester (L-NAME; 20 mM) had no effect on the NGF-mediated increase in luciferase activity, while the inducible NOS selective inhibitor s-methylisothiourea (S-MIU; 2 mM) attenuated the NGF-induced activation of the LRP1 promoter. Pretreatment of PC12 cells with 10 μM bisindolylmaleimide 1 (BIS-1) prevented the NGF-mediated increase in LRP1 promoter activation while 50 μM U0126 partially inhibited this response. In combination with S-MIU, all of the TrkA signalling pathway inhibitors blocked the ability of NGF to increase LRP1 transcription. These data suggest the NGF-mediated increase in LRP1 levels occurs, at least in part, at the level of transcription and that NO and the TrkA signalling pathways cooperate in the modulation of LRP1 transcription. PMID:23192564

  10. Molecular hydrogen stabilizes atherosclerotic plaque in low-density lipoprotein receptor-knockout mice.

    PubMed

    Song, Guohua; Zong, Chuanlong; Zhang, Zhaoqiang; Yu, Yang; Yao, Shutong; Jiao, Peng; Tian, Hua; Zhai, Lei; Zhao, Hui; Tian, Shuyan; Zhang, Xiangjian; Wu, Yun; Sun, Xuejun; Qin, Shucun

    2015-10-01

    Hydrogen (H(2)) attenuates the development of atherosclerosis in mouse models. We aimed to examine the effects of H(2) on atherosclerotic plaque stability. Low-density lipoprotein receptor-knockout (LDLR(-/-)) mice fed an atherogenic diet were dosed daily with H(2) and/or simvastatin. In vitro studies were carried out in an oxidized-LDL (ox-LDL)-stimulated macrophage-derived foam cell model treated with or without H(2). H(2) or simvastatin significantly enhanced plaque stability by increasing levels of collagen, as well as reducing macrophage and lipid levels in plaques. The decreased numbers of dendritic cells and increased numbers of regulatory T cells in plaques further supported the stabilizing effect of H(2) or simvastatin. Moreover, H(2) treatment decreased serum ox-LDL level and apoptosis in plaques with concomitant inhibition of endoplasmic reticulum stress (ERS) and reduction of reactive oxygen species (ROS) accumulation in the aorta. In vitro, like the ERS inhibitor 4-phenylbutyric acid, H(2) inhibited ox-LDL- or tunicamycin (an ERS inducer)-induced ERS response and cell apoptosis. In addition, like the ROS scavenger N-acetylcysteine, H(2) inhibited ox-LDL- or Cu(2+) (an ROS inducer)-induced reduction in cell viability and increase in cellular ROS. Also, H(2) increased Nrf2 (NF-E2-related factor-2, an important factor in antioxidant signaling) activation and Nrf2 small interfering RNA abolished the protective effect of H(2) on ox-LDL-induced cellular ROS production. The inhibitory effects of H(2) on the apoptosis of macrophage-derived foam cells, which take effect by suppressing the activation of the ERS pathway and by activating the Nrf2 antioxidant pathway, might lead to an improvement in atherosclerotic plaque stability. PMID:26117323

  11. Association of lipoarabinomannan with high density lipoprotein in blood: Implications for diagnostics

    SciTech Connect

    Sakamuri, Rama Murthy; Price, Dominique N.; Lee, Myungsun; Cho, Sang Nae; Barry, Clifton E.; Via, Laura E.; Swanson, Basil I.; Mukundan, Harshini

    2013-02-14

    Understanding the pathophysiology of tuberculosis, and the bio-distribution of pathogen-associated molecules in the host is essential for the development of efficient methods of intervention. One of the key virulence factors in the pathology of tuberculosis infection is Lipoarabinomannan (LAM). Previously, we have demonstrated the reliable detection of LAM in urine from tuberculosis patients in a sandwich immunoassay format. We also applied an ultra-sensitive detection strategy developed for amphiphilic biomarkers, membrane insertion, to the detection of LAM with a limit of detection of 10 fM. Herein, we evaluate the application of membrane insertion to the detection of LAM in patient serum, and demonstrate that the circulating concentrations of ‘monomeric’ LAM in serum are very low, despite significantly higher concentrations in the urine. Using spiked samples, we demonstrate that this discrepancy is due to the association of LAM with high-density lipoprotein (HDL) nanodiscs in human serum. Indeed, pull-down of HDL nanodiscs from human serum allows for the recovery of HDL-associated LAM. These studies suggest that LAM is likely associated with carrier molecules such as HDL in the blood of patients infected with tuberculosis. Furthermore, this phenomenon may not be limited to LAM in that many pathogen-associated molecular patterns like LAM are amphiphilic in nature and may also be associated with host lipid carriers. Such interactions are likely to affect host–pathogen interactions, pathogen bio-distribution and clearance in the host, and must be thoroughly understood for the effective design of vaccines and diagnostics.

  12. Plasma Nitration of High-Density and Low-Density Lipoproteins in Chronic Kidney Disease Patients Receiving Kidney Transplants

    PubMed Central

    Bakillah, Ahmed; Tedla, Fasika; Ayoub, Isabelle; John, Devon; Norin, Allen J.; Hussain, M. Mahmood; Brown, Clinton

    2015-01-01

    Background. Functional abnormalities of high-density lipoprotein (HDL) could contribute to cardiovascular disease in chronic kidney disease patients. We measured a validated marker of HDL dysfunction, nitrated apolipoprotein A-I, in kidney transplant recipients to test the hypothesis that a functioning kidney transplant reduces serum nitrated apoA-I concentrations. Methods. Concentrations of nitrated apoA-I and apoB were measured using indirect sandwich ELISA assays on sera collected from each transplant subject before transplantation and at 1, 3, and 12 months after transplantation. Patients were excluded if they have history of diabetes, treatment with lipid-lowering medications or HIV protease inhibitors, prednisone dose > 15 mg/day, nephrotic range proteinuria, serum creatinine > 1.5 mg/dL, or active inflammatory disease. Sera from 18 transplanted patients were analyzed. Four subjects were excluded due to insufficient data. Twelve and eight patients had creatinine < 1.5 mg/dL at 3 and 12 months after transplantation, respectively. Results. Nitrated apoA-I was significantly reduced at 12 months after transplantation (p = 0.039). The decrease in apoA-I nitration was associated with significant reduction in myeloperoxidase (MPO) activity (p = 0.047). In contrast to apoA-I, nitrated apoB was not affected after kidney transplantation. Conclusions. Patients with well-functioning grafts had significant reduction in nitrated apoA-I 12 months after kidney transplantation. Further studies are needed in a large cohort to determine if nitrated apoA-I can be used as a valuable marker for cardiovascular risk stratification in chronic kidney disease. PMID:26648662

  13. In silico modeling of the dynamics of low density lipoprotein composition via a single plasma sample.

    PubMed

    Jansen, Martin; Pfaffelhuber, Peter; Hoffmann, Michael M; Puetz, Gerhard; Winkler, Karl

    2016-05-01

    Lipoproteins play a key role in the development of CVD, but the dynamics of lipoprotein metabolism are difficult to address experimentally. This article describes a novel two-step combined in vitro and in silico approach that enables the estimation of key reactions in lipoprotein metabolism using just one blood sample. Lipoproteins were isolated by ultracentrifugation from fasting plasma stored at 4°C. Plasma incubated at 37°C is no longer in a steady state, and changes in composition may be determined. From these changes, we estimated rates for reactions like LCAT (56.3 µM/h), β-LCAT (15.62 µM/h), and cholesteryl ester (CE) transfer protein-mediated flux of CE from HDL to IDL/VLDL (21.5 µM/h) based on data from 15 healthy individuals. In a second step, we estimated LDL's HL activity (3.19 pools/day) and, for the very first time, selective CE efflux from LDL (8.39 µM/h) by relying on the previously derived reaction rates. The estimated metabolic rates were then confirmed in an independent group (n = 10). Although measurement uncertainties do not permit us to estimate parameters in individuals, the novel approach we describe here offers the unique possibility to investigate lipoprotein dynamics in various diseases like atherosclerosis or diabetes. PMID:27015744

  14. Non-High-Density Lipoprotein Cholesterol in Children with Diabetes: Proposed Treatment Recommendations Based on Glycemic Control, Body Mass Index, Age, Sex, and Generally Accepted Cut Points.

    PubMed

    Schwab, K Otfried; Doerfer, Jürgen; Hungele, Andreas; Scheuing, Nicole; Krebs, Andreas; Dost, Axel; Rohrer, Tilman R; Hofer, Sabine; Holl, Reinhard W

    2015-12-01

    Percentile-based non-high-density lipoprotein cholesterol levels were analyzed by glycemic control, weight, age, and sex of children with type 1 diabetes (n = 26,358). Ten percent of all children and 25% of overweight adolescent girls require both immediate lipid-lowering medication and lifestyle changes to achieve non-high-density lipoprotein cholesterol levels <120 mg/dL and cardiovascular risk reduction. PMID:26427965

  15. Preparation and investigation of 99m technetium-labeled low-density lipoproteins in rabbits with experimentally induced hypercholesterolemia.

    PubMed

    Bozóky, Z; Balogh, L; Máthé, D; Fülöp, L; Bertók, L; Jánoki, Gy A

    2004-04-01

    Low-density lipoproteins (LDL) were radiolabeled in atherosclerosis studies. The aim was to investigate the biodistribution and uptake of 99mTc-labeled LDL by atherosclerotic plaques in experimentally induced hyperlipidemia. Rabbits were fed a diet containing 2% cholesterol for 60 days to develop hyperlipidemia and atheromatous aortic plaques. A combination of preparative and analytical ultracentrifugation was used to investigate human LDL aliquots, to prepare radioactive-labeled lipoproteins and in rabbits with induced hyperlipidemia. Preparative density gradient centrifugation was applied for the simultaneous isolation of the major lipoprotein density classes, which form discrete bands of lipoproteins in the preparative tubes. The cholesterol and protein levels in the lipoprotein fractions were determined. LDL was subsequently dialysed against physiological solution and sterilized and apolipoprotein fragments and aggregates were eliminated by passage through a 0.22-micron filter. LDL was radiolabeled with 99mTc by using sodium dithionite as a reducing agent. Radiochemical purity and in vitro stability were controlled by paper chromatography in acetone. The labelling efficiency was 85-90% for human LDL. Two months after the start of cholesterol feeding, the total cholesterol in the blood serum had increased approximately 33-fold in comparison with the basal cholesterol content of hypercholesterolemic rabbits. Investigation of LDL was performed by Schlieren analysis after adjustment of the density of serum and underlayering by salt solution in a spinning ultracentrifugation capillary band-forming cell. Quantitative results were obtained by measuring the Schlieren areas between the sample curves and the reference baseline curve by means of computerized numerical and graphic techniques. In this manner we measured the concentrations of human LDL and analyzed rabbit LDL levels in induced hyperlipidemia. Gamma scintillation camera scanning of the rabbits was performed. Overnight fasted rabbits were injected in the marginal ear vein with 99mTc-labeled human LDL (4-10 mCi, 0.5-1.5 mg protein). The initial scintigram showing a typical blood-pool scan, gradually changing with time to an image of specific organ uptake of radioactivity by the liver, kidneys and brain and in the bladder. Gamma camera in vivo scintigraphy on rabbits revealed visible signals corresponding to atherosclerotic plaques in the aorta and carotid arteries. Our results show that 99mTc-LDL can be used to assess the organ distribution pattern of LDL in the rabbit, and to detect and localize areas of arterial atherosclerotic lesions. PMID:14663630

  16. Lipoprotein Apheresis.

    PubMed

    Moriarty, Patrick M; Hemphill, Linda

    2016-03-01

    Patients with familial hypercholesterolemia (FH) have early development of atherosclerosis and cardiovascular disease (CVD). Lipid level-lowering medications are not always successful in reducing increased low-density lipoprotein C (LDL-C) levels. Lipoprotein apheresis (LA) therapy has proven its clinical benefit in reducing CVD events for patients with FH with hypercholesterolemia. LA reduces LDL-C levels by more than 60% in patients with FH and reduces CVD events. LA also reduces Lp(a) levels and CVD events. LA reduces inflammatory markers and blood viscosity. PMID:26892996

  17. Lipoprotein apheresis.

    PubMed

    Moriarty, Patrick M; Hemphill, Linda

    2015-05-01

    Patients with familial hypercholesterolemia (FH) have early development of atherosclerosis and cardiovascular disease (CVD). Lipid level-lowering medications are not always successful in reducing increased low-density lipoprotein C (LDL-C) levels. Lipoprotein apheresis (LA) therapy has proven its clinical benefit in reducing CVD events for patients with FH with hypercholesterolemia. LA reduces LDL-C levels by more than 60% in patients with FH and reduces CVD events. LA also reduces Lp(a) levels and CVD events. LA reduces inflammatory markers and blood viscosity. PMID:25939293

  18. Loci of catabolism of beta-very low density lipoprotein in vivo delineated with a residualizing label, SVI-dilactitol tyramine

    SciTech Connect

    Daugherty, A.; Thorpe, S.R.; Lange, L.G.; Sobel, B.E.; Schonfeld, G.

    1985-11-25

    beta-Very low density lipoprotein (beta-VLDL) may be a major atherogenic lipoprotein, and knowledge of the sites of its catabolism should facilitate elucidation of mechanisms important in the regulation of its plasma concentrations. In this study, catabolic sites of beta-VLDL have been delineated in normolipidemic rabbits with a novel, radioiodinated, residualizing label, SVI-dilactitol tyramine ( SVI-DLT). Comparative studies of beta-VLDL and low density lipoprotein catabolism were performed with SVI-DLT conjugated to each lipoprotein and with lipoproteins iodine-labeled conventionally. Conjugation did not alter size distributions or charge characteristics of lipoprotein particles. The overall processing (binding and degradation) of lipoproteins by cultured rabbit skin fibroblasts was not influenced by SVI-DLT derivatization, suggesting that attachment of the label did not influence cell receptor-lipoprotein interactions. Furthermore, although degradation products of SVI-lipoproteins leaked out of the cells and into the medium, the degradation products of SVI-DLT lipoproteins were retained by the cells. The principal catabolic site of beta-VLDL in normolipidemic rabbits was found to be the liver with 54 +/- 4% of injected SVI retained in this organ 24 h after injection of SVI-DLT-beta-VLDL. When catabolism was normalized to tissue weight, the liver and adrenals were found to be approximately equally active in the metabolism of beta-VLDL. In agreement with results of other studies with residualizing labels, the principal organ of catabolism of SVI-DLT-LDL in vivo was the liver. The adrenals were the most highly catabolizing organ when results were normalized for tissue weight.

  19. Evidence for low high-density lipoprotein cholesterol levels in Australian indigenous peoples: a systematic review

    PubMed Central

    2014-01-01

    Background Low plasma high-density lipoprotein cholesterol (HDL-C) levels are a strong, independent, but poorly understood risk factor for cardiovascular disease (CVD). Although this atherogenic lipid abnormality has been widely reported in Australia’s Indigenous peoples, Aboriginal and Torres Strait Islanders, the evidence has not come under systematic review. This review therefore examines published data for Indigenous Australians reporting 1) mean HDL-C levels for both sexes and 2) factors associated with low HDL-C. Methods PubMed, Medline and Informit ATSI Health databases were systematically searched between 1950 and 2012 for studies on Indigenous Australians reporting mean HDL-C levels in both sexes. Retrieved studies were evaluated by standard criteria. Low HDL-C was defined as: <1.0 mmol/L. Analyses of primary data associating measures of HDL-C with other CVD risk factors were also performed. Results Fifteen of 93 retrieved studies were identified for inclusion. These provided 58 mean HDL-C levels; 29 for each sex, most obtained in rural/regional (20%) or remote settings (60%) and including 51–1641 participants. For Australian Aborigines, mean HDL-C values ranged between 0.81-1.50 mmol/L in females and 0.76-1.60 mmol/L in males. Two of 15 studies reported HDL-C levels for Torres Strait Islander populations, mean HDL-C: 1.00 or 1.11 mmol/L for females and 1.01 or 1.13 mmol/L for males. Low HDL-C was observed only in rural/regional and remote settings - not in national or urban studies (n = 3) in either gender. Diabetes prevalence, mean/median waist-to-hip ratio and circulating C-reactive protein levels were negatively associated with HDL-C levels (all P < 0.05). Thirty-four per cent of studies reported lower mean HDL-C levels in females than in males. Conclusions Very low mean HDL-C levels are common in Australian Indigenous populations living in rural and remote communities. Inverse associations between HDL-C and central obesity, diabetes prevalence and inflammatory markers suggest a particularly adverse CVD risk factor profile. An absence of sex dichotomy in HDL-C levels warrants further investigation. PMID:24888391

  20. Genetic analysis of long-lived families reveals novel variants influencing high density-lipoprotein cholesterol

    PubMed Central

    Feitosa, Mary F.; Wojczynski, Mary K.; Straka, Robert; Kammerer, Candace M.; Lee, Joseph H.; Kraja, Aldi T.; Christensen, Kaare; Newman, Anne B.; Province, Michael A.; Borecki, Ingrid B.

    2014-01-01

    The plasma levels of high-density lipoprotein cholesterol (HDL) have an inverse relationship to the risks of atherosclerosis and cardiovascular disease (CVD), and have also been associated with longevity. We sought to identify novel loci for HDL that could potentially provide new insights into biological regulation of HDL metabolism in healthy-longevous subjects. We performed a genome-wide association (GWA) scan on HDL using a mixed model approach to account for family structure using kinship coefficients. A total of 4114 subjects of European descent (480 families) were genotyped at ~2.3 million SNPs and ~38 million SNPs were imputed using the 1000 Genome Cosmopolitan reference panel in MACH. We identified novel variants near-NLRP1 (17p13) associated with an increase of HDL levels at genome-wide significant level (p < 5.0E-08). Additionally, several CETP (16q21) and ZNF259-APOA5-A4-C3-A1 (11q23.3) variants associated with HDL were found, replicating those previously reported in the literature. A possible regulatory variant upstream of NLRP1 that is associated with HDL in these elderly Long Life Family Study (LLFS) subjects may also contribute to their longevity and health. Our NLRP1 intergenic SNPs show a potential regulatory function in Encyclopedia of DNA Elements (ENCODE); however, it is not clear whether they regulate NLRP1 or other more remote gene. NLRP1 plays an important role in the induction of apoptosis, and its inflammasome is critical for mediating innate immune responses. Nlrp1a (a mouse ortholog of human NLRP1) interacts with SREBP-1a (17p11) which has a fundamental role in lipid concentration and composition, and is involved in innate immune response in macrophages. The NLRP1 region is conserved in mammals, but also has evolved adaptively showing signals of positive selection in European populations that might confer an advantage. NLRP1 intergenic SNPs have also been associated with immunity/inflammasome disorders which highlights the biological importance of this chromosomal region. PMID:24917880

  1. Allele-specific expression of the low density lipoprotein receptor gene

    SciTech Connect

    Minnich, A.; Lussier-Cacan, S.; Roy, M.

    1994-09-01

    Approximately 60% of familial hypercholesterolemia (FH) in French Canadians is due to a > 10 kb deletion of the promoter region of the gene encoding the low density lipoprotein (LDL) receptor (LDL-R), allowing determination of the influence of a single LDL-R allele on phenotypic expression of FH. Normal allele haplotypes of approximately 250 heterozygotes were determined with 7 RFLPs. In vitro maximal LDL-R activity of blood lymphocytes from a subset of approximately 150 heterozygotes, measured by immunocytofluorometry, was significantly higher (20 to 30%) in subjects with LDL-R normal allele haplotype G (n=11), and O (n=7) compared to the most frequent haplotype F (n=43), while no differences were observed among F, E (n=11), and the 2 other most prevalent haplotypes (n=43). LDL-R mRNA in these lymphocytes was significantly elevated 2.3-, 1.7-, and 1.8- fold, in G, O, and E, respectively, compared to F, while no significant differences were apparent between F and the other two most frequent haplotyes. Large interindividual variability in lymphocyte LDL-R mRNA levels and activity was observed even among subjects with the same LDL-R normal allele haplotype. However, maximally induced lymphocyte LDL-R mRNA levels correlated poorly with levels measured in freshly isolated cells (n=14). Relative to haplotype F (n=47 women (W), 39 men (M)), mean plasma LDL cholesterol levels adjusted for age and apolipoprotein E genotype were 5-10% lower in men and women with haplotypes G (n=16 W, 12 M) and O (n=8 W, 6 M), and 20% lower in 7 W with haplotype E. These results suggest that (1) normal LDL-R allele haplotype G and O may contain sequence variations which confer relatively high gene expression and (2) environmental and genetic influences other than the LDL-R gene contribute substantially to variability in LDL-R expression and plasma LDL cholesterol levels in French Canadian FH heterozygotes.

  2. Expression of low-density lipoprotein receptors in peripheral blood and tonsil B lymphocytes

    PubMed Central

    De Sanctis, J B; Blanca, I; Rivera, H; Bianco, N E

    1998-01-01

    B lymphocytes, purified from peripheral leucocytes from young normolipaemic humans, expressed and internalized low-density lipoprotein receptors (LDLR). The expression was assessed by a monoclonal anti-LDLR. The internalization of LDL was assessed by LDL labelled with 125I (125I-LDL) and 1,1′-dioctadecyl-3,3,3′,3′ tetramethyl-indocarboxycyanine perchlorate (LDL-DiI). The expression of LDLR, assessed by anti-LDLR, was: 38 ± 8% (n = 5) for fresh purified cells, 60 ± 10% (n = 12) for non-stimulated cells, 79 ± 5% (n = 10) for IL-2 (100 U/ml)-stimulated cells and 95 ± 5% (n = 8) for pokeweed mitogen (PWM) (1:200 dilution)-stimulated cells. The optimal concentrations of agonist were 100 U/ml of IL-2, and 1:200 dilution of PWM. IL-2 and PWM increased the internalization of LDL-DiI by 1.5-fold. The internalization of LDL-DiI was maximal at 60 μg of protein/ml (48 ± 8%). Scatchard analysis revealed a Kd of 3.2 ± 0.22 × 10−8 m and 2180 ± 190 binding sites in non-stimulated cells, a Kd of 7.73 ± 0.36 × 10−9 m and 12 500 ± 430 binding sites for IL-2 (100 U/ml)-stimulated cells, and a Kd of 7.2 ± 0.43 × 10−9 m and 13 250 ± 450 binding sites for PWM (1:200 dilution)-stimulated cells. Lineweaver–Burk analysis of LDL binding (LDL-DiI) revealed that the apparent Kd for non-stimulated cells was 1.3 ± 0.11 × 10−8 m, and 9.2 ± 0.2 × 10−9 m and 7.5 ± 0.25 × 10−9 m for IL-2- and PWM-stimulated cells, respectively. B lymphocytes from tonsils also showed a high expression of LDLR assessed with anti-LDLR (70 ± 6%). The high expression of LDLR and the avid internalization of LDL suggest that LDL may be important for B cell physiological responses. PMID:9717969

  3. Synthesis and Characterization of Biomimetic High Density Lipoprotein Nanoparticles To Treat Lymphoma

    NASA Astrophysics Data System (ADS)

    Damiano, Marina Giacoma

    High density lipoproteins (HDLs), natural nanoparticles that function as vehicles for cholesterol transport, have enhanced uptake by several human cancers. This uptake is mediated, in part, by the high affinity HDL receptor, scavenger receptor B-1 (SR-B1). More specifically, studies show that the rate of cellular proliferation of lymphoma, a cancer of the lymphocytes, is directly proportional to the amount of HDL-cholesterol available. Thus, targeting of HDL-cholesterol uptake by these cells could be an effective therapeutic approach that may have lower toxicity to healthy cells compared to conventional therapies. Biomimetic HDL can be synthesized using a gold nanoparticle template (HDL-AuNPs), which provides control over size, shape, and surface chemistry. Like their natural counterparts, HDL-AuNPs sequester cholesterol. However, since the gold nanoparticle replaces the cholesterol core of natural HDL, HDL-AuNPs inherently deliver less cholesterol. We show that HDL-AuNPs are able to induce dose dependent apoptosis in B cell lymphoma cell lines and reduce tumor volume following systemic administration to mice bearing B cell lymphoma tumors. Furthermore, HDL-AuNPs are neither toxic to healthy human lymphocytes (SR-B1-), nor to hepatocytes and macrophages (SR-B1+), which are cells naturally encountered by HDLs. Manipulation of cholesterol flux and targeting of SR-B1 are responsible for the efficacy of HDL-AuNPs against B cell lymphoma. HDL-AuNPs could be used to treat B cell lymphomas and other diseases that involve pathologic accumulation of cholesterol. Titanium dioxide nanoparticle (TiO2 NP) core HDLs (HDL-TiO 2 NPs) have been synthesized for high resolution cellular localization studies and for future use as a therapeutic and imaging agent. In initial studies, HDL-TiO(2 NPs display maximum uptake in B cell lymphoma cell lines. X-ray fluorescence microscopy studies show interaction between HDL-TiO2 NPs and cells 10 minutes after treatment and internalization after 1 hour. HDL-TiO2 NPs induce apoptosis in B cell lymphoma cell lines. These results suggest that HDL-TiO2 NPs may be used as therapeutics for lymphoma and other cancers by inducing apoptosis through manipulation of cellular cholesterol flux.

  4. Relationship between oxidized low-density lipoprotein antibodies and obesity in different glycemic situations

    PubMed Central

    Babakr, Abdullatif Taha; Elsheikh, Osman Mohamed; Almarzouki, Abdullah A; Assiri, Adel Mohamed; Abdalla, Badr Eldin Elsonni; Zaki, Hani Yousif; Fatani, Samir H; NourEldin, EssamEldin Mohamed

    2014-01-01

    Background Autoantibodies to oxidized low-density lipoprotein (oxLDL) are a heterogeneous group of antibodies that are controversially discussed to be either pathogenic or protective. Biochemical and anthropometric measurements correlated with increased levels of these antibodies are also controversial, especially in conditions of impaired glucose tolerance and type 2 diabetes mellitus. The present study was conducted to evaluate levels of oxLDL antibodies and their correlation with obesity in different glycemic situations. Methods Two hundred and seventy-four adult males were classified into three subgroups: group 1 (n=125), comprising a control group of nondiabetic subjects; group 2 (n=77), comprising subjects with impaired glucose tolerance; and group 3 (n=72), comprising patients with type 2 diabetes mellitus. Body mass index was calculated, and measurement of oxLDL and oxLDL antibodies was performed. Results Higher mean concentrations of oxLDL were found in the type 2 diabetes mellitus and impaired glucose tolerance groups (143.5±21.9 U/L and 108.7±23.7 U/L, respectively). The mean value for the control group was 73.5±27.5 U/L (P<0.001). Higher mean concentrations of anti-oxLDL antibodies were observed in the type 2 diabetes mellitus and impaired glucose tolerance groups (55.7±17.8 U/L and 40.4±17.6 U/L, respectively). The mean value for the control group was 20.4±10 U/L (P<0.001). Levels of anti-oxLDL antibodies were found to be positively and significantly correlated with body mass index in the control group (r=0.46), impaired glucose tolerance (r=0.51), type 2 diabetes mellitus group (r=0.46), and in the whole study population (r=0.44; P<0.001). Conclusion Anti-oxLDL antibody levels were increased in subjects with type 2 diabetes mellitus and impaired glucose tolerance and were positively correlated with obesity and body mass index. PMID:25368528

  5. Phosphorylcholine-Dependent Cross-Reactivity between Dental Plaque Bacteria and Oxidized Low-Density Lipoproteins

    PubMed Central

    Schenkein, Harvey A.; Berry, Collin R.; Purkall, Donald; Burmeister, John A.; Brooks, Carol N.; Tew, John G.

    2001-01-01

    Antibodies reactive with phosphorylcholine (PC) are ubiquitous in human sera, but the antigens stimulating their production and their function are not clear. Previous studies have shown that a significant proportion of dental plaque bacteria contain PC as determined by reactivity with PC-specific mouse myeloma proteins and monoclonal antibodies. Additionally, serum antibody concentrations of immunoglobulin (IgG) G anti-PC are higher in sera of individuals who have experienced periodontal attachment loss than those who are periodontally healthy. These data implicate the oral microflora as a source of antigen-stimulating anti-PC responses. Recent data also indicate that antibodies with specificity for PC are elevated in ApoE-deficient mice, a model for studies of athersclerosis, and that such antibodies bound oxidized low-density lipoproteins (LDL) (oxLDL) in atherosclerotic plaques. These data prompted the hypothesis that human anti-PC could bind to both oral bacteria and human oxLDL, and that these antigens are cross-reactive. We therefore examined the ability of human anti-PC to bind to PC-bearing strains of oral bacteria using enzyme-linked immunosorbent inhibition assays and by assessment of direct binding of affinity-purified human anti-PC to PC-bearing Actinobacillus actinomycetemcomitans. Our results indicated that PC-bearing strains of Streptococcus oralis, Streptococcus sanguis, Haemophilus aphrophilus, Actinomyces naeslundii, Fusobacterium nucleatum, and A. actinomycetemcomitans, as well as a strain of Streptococcus pneumoniae, absorbed up to 80% of anti-PC IgG antibody from human sera. Furthermore, purified anti-PC bound to a PC-bearing strain of A. actinomycetemcomitans but only poorly to a PC-negative strain. OxLDL also absorbed anti-PC from human sera, and oxLDL but not LDL reacted with up to 80% of the anti-PC in human sera. Furthermore, purified anti-PC bound directly to oxLDL but not to LDL. The data indicate that PC-containing antigens on a variety of common oral bacteria are cross-reactive with neoantigens expressed in oxLDL. We propose that PC-bearing dental plaque microorganisms may induce an antibody response to PC that could influence the inflammatory response associated with atherosclerosis. PMID:11598029

  6. Different responses to oxidized low-density lipoproteins in human polarized macrophages

    PubMed Central

    2011-01-01

    Background Oxidized low-density lipoprotein (oxLDL) uptake by macrophages plays an important role in foam cell formation. It has been suggested the presence of heterogeneous subsets of macrophage, such as M1 and M2, in human atherosclerotic lesions. To evaluate which types of macrophages contribute to atherogenesis, we performed cDNA microarray analysis to determine oxLDL-induced transcriptional alterations of each subset of macrophages. Results Human monocyte-derived macrophages were polarized toward the M1 or M2 subset, followed by treatment with oxLDL. Then gene expression levels during oxLDL treatment in each subset of macrophages were evaluated by cDNA microarray analysis and quantitative real-time RT-PCR. In terms of high-ranking upregulated genes and functional ontologies, the alterations during oxLDL treatment in M2 macrophages were similar to those in nonpolarized macrophages (M0). Molecular network analysis showed that most of the molecules in the oxLDL-induced highest scoring molecular network of M1 macrophages were directly or indirectly related to transforming growth factor (TGF)-β1. Hierarchical cluster analysis revealed commonly upregulated genes in all subset of macrophages, some of which contained antioxidant response elements (ARE) in their promoter regions. A cluster of genes that were specifically upregulated in M1 macrophages included those encoding molecules related to nuclear factor of kappa light polypeptide gene enhancer in B-cells (NF-κB) signaling pathway. Quantitative real-time RT-PCR showed that the gene expression of interleukin (IL)-8 after oxLDL treatment in M2 macrophages was markedly lower than those in M0 and M1 cells. HMOX1 gene expression levels were almost the same in all 3 subsets of macrophages even after oxLDL treatment. Conclusions The present study demonstrated transcriptional alterations in polarized macrophages during oxLDL treatment. The data suggested that oxLDL uptake may affect TGF-β1- and NF-κB-mediated functions of M1 macrophages, but not those of M0 or M2 macrophages. It is likely that M1 macrophages characteristically respond to oxLDL. PMID:21199582

  7. The low density lipoprotein receptor is not required for normal catabolism of Lp(a) in humans.

    PubMed Central

    Rader, D J; Mann, W A; Cain, W; Kraft, H G; Usher, D; Zech, L A; Hoeg, J M; Davignon, J; Lupien, P; Grossman, M

    1995-01-01

    Lipoprotein(a) [Lp(a)] is an atherogenic lipoprotein which is similar in structure to low density lipoproteins (LDL). The role of the LDL receptor in the catabolism of Lp(a) has been controversial. We therefore investigated the in vivo catabolism of Lp(a) and LDL in five unrelated patients with homozygous familial hypercholesterolemia (FH) who have little or no LDL receptor activity. Purified 125I-Lp(a) and 131I-LDL were simultaneously injected into the homozygous FH patients, their heterozygous FH parents when available, and control subjects. The disappearance of plasma radioactivity was followed over time. As expected, the fractional catabolic rates (FCR) of 131I-LDL were markedly decreased in the homozygous FH patients (mean LDL FCR 0.190 d-1) and somewhat decreased in the heterozygous FH parents (mean LDL FCR 0.294 d-1) compared with controls (mean LDL FCR 0.401 d-1). In contrast, the catabolism of 125I-Lp(a) was not significantly different in the homozygous FH patients (mean FCR 0.251 d-1), heterozygous FH parents (mean FCR 0.254 d-1), and control subjects (mean FCR 0.287 d-1). In summary, absence of a functional LDL receptor does not result in delayed catabolism of Lp(a), indicating that the LDL receptor is not a physiologically important route of Lp(a) catabolism in humans. Images PMID:7883987

  8. Accumulation of apolipoprotein E-rich high density lipoproteins in hyperalphalipoproteinemic human subjects with plasma cholesteryl ester transfer protein deficiency.

    PubMed Central

    Yamashita, S; Sprecher, D L; Sakai, N; Matsuzawa, Y; Tarui, S; Hui, D Y

    1990-01-01

    This study characterized the plasma lipoproteins of familial hyperalphalipoproteinemic patients with or without deficiency of cholesteryl ester transfer protein (CETP) activity. The subjects with CETP deficiency have increased levels of apolipoprotein (apo) E. The increased concentration of apo E in these subjects was correlated to the appearance of apo E-rich high density lipoproteins (HDL). Sodium dodecyl sulfate-polyacrylamide gel analysis revealed that these lipoproteins contained predominantly the apo E (82%) and little amount of apo A-I (18%). These apo E-rich HDL displayed a much higher affinity than human LDL in binding to LDL receptors on human fibroblasts. Furthermore, 3.5 times fewer apo E-rich HDL than LDL were required to saturate the receptors on fibroblasts. These data indicated that the apo E-rich HDL in CETP-deficient human subjects contained multiple copies of apo E and bound to the LDL receptor through multiple interactions. The apo E-rich HDL, with similar properties as cholesterol-induced apo E HDLc, were not detectable in normal human subjects or in hyperalphalipoproteinemic subjects with normal CETP activity. The apo E-containing HDL in the latter subjects were smaller and contained only small amounts of apo E (14%). The difference in apo E-containing HDL in these subjects suggests a correlation between CETP level and the appearance of apo E-rich HDL. Images PMID:2118552

  9. Overproduction of a kinetic subclass of VLDL-apoB, and direct catabolism of VLDL-apoB in human endogenous hypertriglyceridemia: an analytical model solution of tracer data

    SciTech Connect

    Eaton, R.P.; Allen, R.C.; Schade, D.S.

    1983-10-01

    To investigate the participation of the major apoprotein involved in triglyceride transport in the pathogenesis of endogenous hypertriglyceridemia, five kinetic studies of apoprotein B were conducted in volunteer normolipidemic subjects and six studies in four patients with endogenous hypertriglyceridemia. The transport of apoprotein B within four kinetic subclasses of very low density lipoprotein (VLDL), intermediate density lipoprotein (IDL), and low density lipoprotein (LDL) was studied by injection of (/sup 75/Se)selenomethionine. A 24-fold increase in the entry of newly synthesized apoprotein B at the initial kinetic subclass of the four-compartment VLDL delipidation sequence characterized the hypertriglyceridemic studies relative to normal subjects. Moreover, approximately 75 mg/kg per day of VLDL-B turnover reflected direct catabolism independent of conversion to IDL and/or to LDL, in contrast to the 8 mg/kg per day observed in controls. IDL-B was derived from VLDL-B in both normal and hypertriglyceridemic subjects, and was responsible for greater than 70% of all LDL-B synthesis. LDL-B pool size and turnover were indistinguishable in hypertriglyceridemic subjects from that observed in normal subjects. These studies suggest that two kinetic phenomena may characterize the pathophysiology of endogenous hypertriglyceridemia: a) over-production of apoB within a kinetic subclass of VLDL and b) preferential catabolism of hypertriglyceridemic VLDL without prior conversion to IDL/LDL.

  10. Biochemical and Functional Characterization of Charge-defined Subfractions of High-density Lipoprotein From Normal Adults

    PubMed Central

    Huang, Max T.; Chang, Chia-Ming; Chen, Chia-Ying; Shen, Ming-Yi; Liao, Hsin-Yi; Wang, Guei-Jane; Chen, Chu-Huang; Chen, Chao-Jung; Yang, Chao-Yuh

    2013-01-01

    High-density lipoprotein (HDL) is regarded as atheroprotective because it provides antioxidant and anti-inflammatory benefits and plays an important role in reverse cholesterol transport. In this paper, we outline a novel methodology for studying the heterogeneity of HDL. Using anion-exchange chromatography, we separated HDL from 6 healthy individuals into 5 subfractions (H1 through H5) with increasing charge and evaluated the composition and biologic activities of each subfraction. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis showed that apolipoprotein (apo) AI and apoAII were present in all 5 subfractions; apoCI was present only in H1; and apoCIII and apoE were most abundantly present in H4 and H5. HDL-associated antioxidant enzymes such as lecithin-cholesterol acyltransferase, lipoprotein-associated phospholipase A2, and paraoxonase 1 were most abundant in H4 and H5. Lipoprotein isoforms were analyzed in each subfraction by using matrix-assisted laser desorption–time of flight mass spectrometry. To quantify other proteins in the HDL subfractions, we used the isobaric tags for relative and absolute quantitation approach followed by nanoflow liquid chromatography–tandem mass spectrometry analysis. Most antioxidant proteins detected were found in H4 and H5. The ability of each subfraction to induce cholesterol efflux from macrophages increased with increasing HDL electronegativity, with the exception of H5, which promoted the least efflux activity. In conclusion, anion-exchange chromatography is an attractive method for separating HDL into subfractions with distinct lipoprotein compositions and biologic activities. By comparing the properties of these subfractions, it may be possible to uncover HDL-specific proteins that play a role in disease. PMID:24171625

  11. Influence of Native and Hypochlorite-Modified Low-Density Lipoprotein on Gene Expression in Human Proximal Tubular Epithelium

    PubMed Central

    Porubsky, Stefan; Schmid, Holger; Bonrouhi, Mahnaz; Kretzler, Matthias; Malle, Ernst; Nelson, Peter J.; Gröne, Hermann-Josef

    2004-01-01

    Inflammatory infiltrates can modify (lipo)proteins via hypochlorous acid/hypochlorite (HOCl/OCl−) an oxidant formed by the myeloperoxidase-H2O2-halide system. These oxidatively modified proteins emerge in tubuli in some proteinuric and interstitial diseases. Human proximal tubular cells (HK-2) were used to confirm the hypothesis of detrimental and differential impact of HOCl-modified low density lipoprotein (HOCl-LDL), an in vivo occurring lipoprotein modification exerting proatherogenic and proinflammatory capacity. HOCl-LDL showed dose-dependent antiproliferative effects in HK-2 cells. Small dedicated cDNA macroarrays were used to identify differentially regulated genes. A rapid increase in the expression of genes involved in reactive oxygen species metabolism and cell stress, eg, heme oxygenase-1, thioredoxin reductase, cytochrome b5 reductase, Gadd 153, amino acid transporter E16, and HSP70 was found after HOCl-LDL treatment of HK-2 cells. In parallel, genes involved in tissue remodeling and inflammation eg, CTGF, VCAM-1, IL-1β, MMP7, and VEGF were up-regulated. Quantitative RT-PCR verified differential expression of a subset of these genes in microdissected tubulointerstitia from patients with acute tubular damage, progressive proteinuric renal disease, and membranous glomerulonephritis (with declining renal function), but not in stable patients with proteinuria caused by minimal change disease. The demonstration of selective up-regulation of a subgroup of genes if proteinuria is accompanied by the presence of HOCl-modified (lipo)proteins support the potential pathophysiological role of the myeloperoxidase-H2O2-halide system and HOCl-LDL in renal disease. PMID:15161651

  12. Dietary Squalene Increases High Density Lipoprotein-Cholesterol and Paraoxonase 1 and Decreases Oxidative Stress in Mice

    PubMed Central

    Gabás-Rivera, Clara; Barranquero, Cristina; Martínez-Beamonte, Roberto; Navarro, María A.; Surra, Joaquín C.; Osada, Jesús

    2014-01-01

    Background and Purpose Squalene, the main hydrocarbon in the unsaponifiable fraction of virgin olive oil, is involved in cholesterol synthesis and it has been reported to own antiatherosclerotic and antiesteatosic effects. However, the squalene's role on lipid plasma parameters and the influence of genotype on this effect need to be addressed. Experimental Approaches Three male mouse models (wild-type, Apoa1- and Apoe- deficient) were fed chow semisynthetic diets enriched in squalene to provide a dose of 1 g/kg during 11 weeks. After this period, their plasma parameters and lipoprotein profiles were analyzed. Key Results Squalene administration at a dose of 1 g/kg showed decreased reactive oxygen species in lipoprotein fractions independently of the animal background and caused an specific increase in high density lipoprotein (HDL)-cholesterol levels, accompanied by an increase in phosphatidylcholine and paraoxonase 1 and no changes in apolipoproteins A1 and A4 in wild-type mice. In these mice, the cholesterol increase was due to its esterified form and associated with an increased hepatic expression of Lcat. These effects were not observed in absence of apolipoprotein A1. The increases in HDL- paraoxonase 1 were translated into decreased plasma malondialdehyde levels depending on the presence of Apolipoprotein A1. Conclusions and Implications Dietary squalene promotes changes in HDL- cholesterol and paraoxonase 1 and decreases reactive oxygen species in lipoproteins and plasma malondialdehyde levels, providing new benefits of its intake that might contribute to explain the properties of virgin olive oil, although the phenotype related to apolipoproteins A1 and E may be particularly relevant. PMID:25117703