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Mack S, Coassin S, Rueedi R, Yousri NA, Seppälä I, Gieger C, Schönherr S, Forer L, Erhart G, Marques-Vidal P, Ried JS, Waeber G, Bergmann S, Dähnhardt D, Stöckl A, Raitakari OT, Kähönen M, Peters A, Meitinger T, Strauch K, Kedenko L, Paulweber B, Lehtimäki T, Hunt SC, Vollenweider P, Lamina C, Kronenberg F. A genome-wide association meta-analysis on lipoprotein (a) concentrations adjusted for apolipoprotein (a) isoforms. J Lipid Res 2017; 58:1834-1844. [PMID: 28512139 PMCID: PMC5580897 DOI: 10.1194/jlr.m076232] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 05/04/2017] [Indexed: 12/13/2022] Open
Abstract
High lipoprotein (a) [Lp(a)] concentrations are an independent risk factor for cardiovascular outcomes. Concentrations are strongly influenced by apo(a) kringle IV repeat isoforms. We aimed to identify genetic loci associated with Lp(a) concentrations using data from five genome-wide association studies (n = 13,781). We identified 48 independent SNPs in the LPA and 1 SNP in the APOE gene region to be significantly associated with Lp(a) concentrations. We also adjusted for apo(a) isoforms to identify loci affecting Lp(a) levels independently from them, which resulted in 31 SNPs (30 in the LPA, 1 in the APOE gene region). Seven SNPs showed a genome-wide significant association with coronary artery disease (CAD) risk. A rare SNP (rs186696265; MAF ∼1%) showed the highest effect on Lp(a) and was also associated with increased risk of CAD (odds ratio = 1.73, P = 3.35 × 10−30). Median Lp(a) values increased from 2.1 to 91.1 mg/dl with increasing number of Lp(a)-increasing alleles. We found the APOE2-determining allele of rs7412 to be significantly associated with Lp(a) concentrations (P = 3.47 × 10−10). Each APOE2 allele decreased Lp(a) by 3.34 mg/dl corresponding to ∼15% of the population’s mean values. Performing a gene-based test of association, including suspected Lp(a) receptors and regulators, resulted in one significant association of the TLR2 gene with Lp(a) (P = 3.4 × 10−4). In summary, we identified a large number of independent SNPs in the LPA gene region, as well as the APOE2 allele, to be significantly associated with Lp(a) concentrations.
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Affiliation(s)
- Salome Mack
- Division of Genetic Epidemiology, Department of Medical Genetics, Molecular and Clinical Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Stefan Coassin
- Division of Genetic Epidemiology, Department of Medical Genetics, Molecular and Clinical Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Rico Rueedi
- Department of Computational Biology, University of Lausanne, 1015 Lausanne, Switzerland.,Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| | - Noha A Yousri
- Department of Physiology and Biophysics, Weill Cornell Medical College-Qatar, Doha, Qatar.,Department of Computer and Systems Engineering, Alexandria University, 21526 Alexandria, Egypt
| | - Ilkka Seppälä
- Department of Clinical Chemistry, Fimlab Laboratories and University of Tampere School of Medicine, 33520 Tampere, Finland
| | - Christian Gieger
- Institute of Genetic Epidemiology, Helmholtz Zentrum München-German Research Center for Environmental Health, 85764 Neuherberg, Germany.,Institute of Epidemiology II, Helmholtz Zentrum München-German Research Center for Environmental Health, 85764 Neuherberg, Germany.,Research Unit of Molecular Epidemiology, Helmholtz Zentrum München-German Research Center for Environmental Health, 85764 Neuherberg, Germany
| | - Sebastian Schönherr
- Division of Genetic Epidemiology, Department of Medical Genetics, Molecular and Clinical Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Lukas Forer
- Division of Genetic Epidemiology, Department of Medical Genetics, Molecular and Clinical Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Gertraud Erhart
- Division of Genetic Epidemiology, Department of Medical Genetics, Molecular and Clinical Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Pedro Marques-Vidal
- Department of Medicine, Internal Medicine, Lausanne University Hospital, 1015 Lausanne, Switzerland
| | - Janina S Ried
- Institute of Genetic Epidemiology, Helmholtz Zentrum München-German Research Center for Environmental Health, 85764 Neuherberg, Germany
| | - Gerard Waeber
- Department of Medicine, Internal Medicine, Lausanne University Hospital, 1015 Lausanne, Switzerland
| | - Sven Bergmann
- Department of Computational Biology, University of Lausanne, 1015 Lausanne, Switzerland.,Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| | - Doreen Dähnhardt
- Division of Genetic Epidemiology, Department of Medical Genetics, Molecular and Clinical Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Andrea Stöckl
- Division of Genetic Epidemiology, Department of Medical Genetics, Molecular and Clinical Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Olli T Raitakari
- Department of Clinical Physiology, Turku University Hospital, 20520 Turku, Finland.,Research Centre of Applied and Preventive Cardiovascular Medicine, University of Turku, 20520 Turku, Finland
| | - Mika Kähönen
- Department of Clinical Physiology, Tampere University Hospital and University of Tampere, 33521 Tampere, Finland
| | - Annette Peters
- Institute of Epidemiology II, Helmholtz Zentrum München-German Research Center for Environmental Health, 85764 Neuherberg, Germany.,German Centre for Cardiovascular Research (DZHK), 80802 Munich, Germany.,German Center for Diabetes Research (DZD e.V.), 85764 Neuherberg, Germany
| | - Thomas Meitinger
- Institute of Human Genetics, Technische Universität München, 81675 München, Germany.,Institute of Human Genetics, Helmholtz Zentrum München-German Research Center for Environmental Health, 85764 Neuherberg, Germany.,Munich Cluster for Systems Neurology (SyNergy), 81377 Munich, Germany
| | - Konstantin Strauch
- Institute of Genetic Epidemiology, Helmholtz Zentrum München-German Research Center for Environmental Health, 85764 Neuherberg, Germany.,Institute of Medical Informatics, Biometry, and Epidemiology, Ludwig-Maximilians-Universität, 81377 Munich, Germany
| | | | - Ludmilla Kedenko
- First Department of Internal Medicine, Paracelsus Private Medical University, 5020 Salzburg, Austria
| | - Bernhard Paulweber
- First Department of Internal Medicine, Paracelsus Private Medical University, 5020 Salzburg, Austria
| | - Terho Lehtimäki
- Department of Clinical Chemistry, Fimlab Laboratories and University of Tampere School of Medicine, 33520 Tampere, Finland
| | - Steven C Hunt
- Cardiovascular Genetics Division, University of Utah School of Medicine, Salt Lake City, UT 84108.,Department of Genetic Medicine, Weill Cornell Medicine, Doha, Qatar
| | - Peter Vollenweider
- Department of Medicine, Internal Medicine, Lausanne University Hospital, 1015 Lausanne, Switzerland
| | - Claudia Lamina
- Division of Genetic Epidemiology, Department of Medical Genetics, Molecular and Clinical Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Florian Kronenberg
- Division of Genetic Epidemiology, Department of Medical Genetics, Molecular and Clinical Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria
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Abstract
PURPOSE OF REVIEW To provide an update of the literature describing the link between lipoprotein a and vascular disease. RECENT FINDINGS There is evidence that elevated plasma lipoprotein a levels are associated with coronary heart disease, stroke and other manifestations of atherosclerosis. Several mechanisms may be implicated, including proinflammatory actions and impaired fibrinolysis. SUMMARY Lipoprotein a potentially represents a useful tool for risk stratification in the primary and secondary prevention setting. However, there are still unresolved methodological issues regarding the measurement of lipoprotein a levels. Targeting lipoprotein a in order to reduce vascular risk is hampered by the lack of well tolerated and effective pharmacological interventions. Moreover, it has not yet been established whether such a reduction will result in fewer vascular events. The risk attributed to lipoprotein a may be reduced by aggressively tackling other vascular risk factors, such as low-density lipoprotein cholesterol.
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Ikewaki K, Cain W, Thomas F, Shamburek R, Zech LA, Usher D, Brewer HB, Rader DJ. Abnormal in vivo metabolism of apoB-containing lipoproteins in human apoE deficiency. J Lipid Res 2004; 45:1302-11. [PMID: 15102883 DOI: 10.1194/jlr.m400020-jlr200] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The present study was undertaken to elucidate the metabolic basis for the increased remnants and lipoprotein(a) [Lp(a)] and decreased LDL apolipoprotein B (apoB) levels in human apoE deficiency. A primed constant infusion of (13)C(6)-phenylalanine was administered to a homozygous apoE-deficient subject. apoB-100 and apoB-48 were isolated, and tracer enrichments were determined by gas chromatography-mass spectrometry, then kinetic parameters were calculated by multicompartmental modeling. In the apoE-deficient subject, fractional catabolic rates (FCRs) of apoB-100 in VLDL and intermediate density lipoprotein and apoB-48 in VLDL were 3x, 12x, and 12x slower than those of controls. On the other hand, the LDL apoB-100 FCR was increased by 2.6x. The production rate of VLDL apoB-100 was decreased by 45%. In the Lp(a) kinetic study, two types of Lp(a) were isolated from plasma with apoE deficiency: buoyant and normal Lp(a). (125)I-buoyant Lp(a) was catabolized at a slower rate in the patient. However, (125)I-buoyant Lp(a) was catabolized at twice as fast as (131)I-normal Lp(a) in the control subjects. In summary, apoE deficiency results in: 1) a markedly impaired catabolism of VLDL/chylomicron and their remnants due to lack of direct removal and impaired lipolysis; 2) an increased rate of catabolism of LDL apoB-100, likely due to upregulation of LDL receptor activity; 3) reduced VLDL apoB production; and 4) a delayed catabolism of a portion of Lp(a).
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Affiliation(s)
- Katsunori Ikewaki
- Molecular Disease Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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Mutalib M, Khaza’ai H, Peace H, Whiting P, Wahle K. Palm oil-enriched diets reduced plasma Lp(a) in volunteers with abnormally high concentrations: involvement of decreased triglyceride-rich APO(a). Nutr Res 2002. [DOI: 10.1016/s0271-5317(02)00379-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Rainwater DL, Kammerer CM, VandeBerg JL. Evidence that multiple genes influence baseline concentrations and diet response of Lp(a) in baboons. Arterioscler Thromb Vasc Biol 1999; 19:2696-700. [PMID: 10559013 DOI: 10.1161/01.atv.19.11.2696] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We investigated the response of lipoprotein(a) [Lp(a)] levels to dietary fat and cholesterol in 633 baboons fed a series of 3 diets: a basal diet low in cholesterol and fat, a high-fat diet, and a diet high in fat and cholesterol. Measurement of serum concentrations in samples taken while the baboons were sequentially fed the 3 diets allowed us to analyze 3 Lp(a) variables: Lp(a)(Basal), Lp(a)(RF) (response to increased dietary fat), and Lp(a)(RC) (response to increased dietary cholesterol in the high-fat environment). On average, Lp(a) concentrations significantly increased 6% and 28%, respectively, when dietary fat and cholesterol were increased (P<0.001). As expected, most of the variation in Lp(a)(Basal) was influenced by genes (h(2)=0.881). However, less than half of the variation in Lp(a)(RC) was influenced by genes (h(2)=0.347, P<0. 0001), whereas the increase due to dietary fat alone was not significantly heritable (h(2)=0.043, P=0.28). To determine whether Lp(a) phenotypic variation was due to variation in LPA, the locus encoding the apolipoprotein(a) [apo(a)] protein, we conducted linkage analyses by using LPA genotypes inferred from the apo(a) isoform phenotypes. All of the genetic variance in Lp(a)(Basal) concentration was linked to the LPA locus (log of the odds [LOD] score was 30.5). In contrast, linkage analyses revealed that genetic variance in Lp(a)(RC) was not linked to the LPA locus (LOD score was 0.036, P>0.5). To begin identifying the non-LPA genes that influence the Lp(a) response to dietary cholesterol, we tested, in bivariate quantitative genetic analyses, for correlation with low density lipoprotein cholesterol [LDLC; ie, non-high density lipoprotein cholesterol less the cholesterol contribution from Lp(a)]. LDLC(Basal) was weakly correlated with Lp(a)(Basal) (rho(P)=0.018). However, LDLC(RC) and Lp(a)(RC) were strongly correlated (rho(P)=0. 382), and partitioning the correlations revealed significant genetic and environmental correlations (rho(G)=0.587 and rho(E)=0.251, respectively). The results suggest that increasing both dietary fat and dietary cholesterol caused significant increases in Lp(a) concentrations and that the response to dietary cholesterol was mediated by a gene or suite of genes that appears to exert pleiotropic effects on LDLC levels as well. The gene(s) influencing Lp(a) response to dietary cholesterol is not linked to the LPA locus.
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Affiliation(s)
- D L Rainwater
- Department of Genetics, Southwest Foundation for Biomedical Research, San Antonio, TX 78245-0549, USA.
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Bigot E, Robert B, Bard JM, Mainard F. Lipoprotein (a) phenotype distribution in a population of bypass patients and its influence on lipoprotein (a) concentration. Clin Chim Acta 1997; 265:99-111. [PMID: 9352133 DOI: 10.1016/s0009-8981(97)00107-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A case control study was undertaken to compare the distribution of apolipoprotein (a) phenotypes in patients suffering from atherosclerosis and undergoing coronary bypass surgery with the distribution observed in adequately selected controls. Cases differed from controls for triglycerides (1.90 +/- 0.88 mmol l-1 and 1.16 +/- 0.79 mmol l-1, P < 0.0001, respectively), HDL cholesterol (1.15 +/- 0.34 mmol l-1 and 1.69 +/- 0.42 mmol l-1, P < 0.0001, respectively), apolipoprotein AI (1.31 +/- 0.24 g l-1 and 1.70 +/- 0.29 g l-1, P < 0.0001, respectively) and lipoprotein a (Lp(a)) (0.32 +/- 0.30 g l-1 and 0.19 +/- 0.20 g l-1, P < 0.0001, respectively). The apolipoprotein (a) phenotypes were distributed differently in cases and controls (chi 2 = 25.26, P < 0.0001) with a lower percentage of isoforms of larger size and a higher percentage of isoforms of smaller size in patients. The Lp(a) concentration remained significantly higher in patients than in controls for most of the phenotypes, suggesting that both a high Lp(a) concentration and a different apolipoprotein (a) size distribution could be involved in the development of atherosclerosis in this population. In addition, patients exhibiting the highest Lp(a) concentrations had higher levels of LDL cholesterol and apolipoprotein B than patients exhibiting the lowest Lp(a) concentrations. This feature was not observed in controls. By contrast, controls with the highest Lp(a) concentration had significantly higher triglyceride levels than controls with the lowest Lp(a) concentration. This feature was not observed in patients. Our results indicate that patients undergoing bypass surgery have higher Lp(a) concentrations than controls, this increase being not completely explained by the difference in apolipoprotein (a) phenotype distribution. The high Lp(a) concentration seems to be associated with different lipid profiles in patients than in controls.
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Affiliation(s)
- E Bigot
- UFR de Phamacie, Laboratoire de Biochimie et EA1160 Fonctions digestives et nutrition, Nantes, France
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7
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Tuck CH, Holleran S, Berglund L. Hormonal regulation of lipoprotein(a) levels: effects of estrogen replacement therapy on lipoprotein(a) and acute phase reactants in postmenopausal women. Arterioscler Thromb Vasc Biol 1997; 17:1822-9. [PMID: 9327783 DOI: 10.1161/01.atv.17.9.1822] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Estrogen lowers lipoprotein(a) [Lp(a)] levels, but the mechanisms involved have not been clarified. To address the relationship between estrogenic effects on Lp(a) and serum lipids, and on other plasma proteins of hepatic origin, 15 healthy postmenopausal women participated in a randomized, double-blinded, placebo-controlled, crossover study with 4 weeks of oral conjugated estrogens (0.625 mg/d) and placebo, separated by a 6-week period. Lp(a) levels decreased during estrogen treatment in 14 of the 15 subjects (mean decrease, 23%; P < .001). In response to estrogen, apolipoprotein A-I (apoA-I), HDL cholesterol, and triglyceride levels increased by 12% (P = .001), 11% (P < .001), and 10% (P = .02), respectively. Apolipoprotein B (apoB) and LDL cholesterol levels decreased by 7% (P = .01) and 12% (P = .03), respectively, ApoB, LDL cholesterol, and Lp(a) levels fell within 1 week of treatment, whereas apoA-I and HDL cholesterol levels rose more slowly. Levels of acid alpha 1-glycoprotein (AAG) and haptoglobin (HPT), two hepatically derived acute phase proteins, also decreased during estrogen treatment by 18% (P < .001) and 25% (P = .002), respectively. Although the changes in AAG and HPT in response to estrogen were highly correlated (r = .67, P = .009), we were unable to detect a correlation between change in either acute phase protein and change in Lp(a) (r = -.14 and -.24, P = .64 and .41). The lack of correlation between the changes in two acute phase reactants and Lp(a) suggests different underlying mechanisms for the effects of estrogen on these liver-derived proteins.
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Affiliation(s)
- C H Tuck
- Department of Medicine, Columbia University, New York, NY 10032, USA
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8
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Elisaf MS, Bairaktari ET, Tzallas CS, Siamopoulos KC. Lipoprotein (a) concentrations in patients with various dyslipidaemias. Ann Med 1997; 29:305-9. [PMID: 9375987 DOI: 10.3109/07853899708999352] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Although the genetic background is the most important determinant of lipoprotein (a) (Lp(a)) concentration other factors, such as coexistent dyslipidaemia, could modify its levels. We undertook the present study to examine the serum Lp(a) concentration in various dyslipidaemias and to reveal any correlation of serum Lp(a) concentration with the other lipid parameters in a large group of dyslipidaemic Greek patients. A total of 242 patients followed as outpatients in our lipid clinic were studied. The patients were stratified into four main groups. Patients with cholesterol levels greater than 5.17 mmol/L but normal triglycerides were regarded as hypercholesterolaemic (n=85), patients with triglycerides greater than 2.25 mmol/L but normal cholesterol levels as hypertriglyceridaemic (n=51), patients with both increased cholesterol and triglyceride levels as having mixed hyperlipidaemia (n=62), and finally patients with decreased (<0.90 mmol/L) high-density lipoprotein (HDL) cholesterol but normal cholesterol and triglyceride levels as having primary hypoalphalipoproteinaemia (n=44). Hypercholesterolaemic patients exhibited the highest serum Lp(a) levels, while hypertriglyceridaemic patients exhibited the lowest. Patients with mixed hyperlipidaemia had intermediate serum Lp(a) concentration, which was significantly higher than that of hypertriglyceridaemic patients but significantly lower than that of hypercholesterolaemic patients. Interestingly, patients with low serum HDL-cholesterol levels presented with low serum Lp(a) concentration similar to that of hypertriglyceridaemic patients. In hypercholesterolaemic patients no correlation was found between serum total and low-density lipoprotein (LDL) cholesterol nor apolipoprotein B (apoB) levels and Lp(a) concentration. On the contrary, in hypertriglyceridaemic patients an inverse correlation was observed between serum triglycerides and Lp(a) concentration. After dividing the hypertriglyceridaemic patients into one group with elevated (>1.3 g/L) serum apoB levels (n=32) and another group with normal apoB levels (n=19), we found that the median serum Lp(a) concentration was three times higher in hyperapoB patients compared to patients with normal apoB levels. We conclude that serum Lp(a) levels are different in various types of primary hyperlipidaemia and are modulated according to the type of lipid elevation.
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Affiliation(s)
- M S Elisaf
- Department of Internal Medicine, Medical School, University of Ioannina, Greece
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9
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Marcoux C, Lussier-Cacan S, Davignon J, Cohn JS. Association of Lp(a) rather than integrally-bound apo(a) with triglyceride-rich lipoproteins of human subjects. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1346:261-74. [PMID: 9219911 DOI: 10.1016/s0005-2760(97)00049-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The majority of apolipoprotein (a) [apo(a)] in plasma is characteristically associated with Lipoprotein (a) [Lp(a)], having a buoyant density (1.05-1.08 g/ml) intermediate between low density lipoproteins (LDL) and high density lipoproteins (HDL). In the fed (postprandial) state or in the presence of fasting (endogenous) hypertriglyceridemia, a small proportion of plasma apo(a) is found in the density < 1.006 g/ml fraction of plasma, associated with larger and less dense triglyceride-rich lipoproteins (TRL). In order to further characterize the presence of apo(a) in ultracentrifugally-separated TRL (UTC-TRL), this lipoprotein fraction was isolated from plasma obtained in the fed state (three hours after an oral fat load) from healthy normolipidemic subjects (Lp(a): 38 +/- 8 mg/dl (mean +/- S.E.), n = 4) and also from plasma obtained after an overnight fast from hypertriglyceridemic patients (plasma TG: 8.16 +/- 2.00 mmol/l, Lp(a): 41 +/- 3 mg/dl, n = 18). Apo(a) in 3 h-postprandial UTC-TRL (5 +/- 2% of total plasma apo(a)) and in hypertriglyceridemic UTC-TRL (8 +/- 2% total apo(a)) was separable by electrophoresis and/or gel chromatography (FPLC) from the majority of UTC-TRL lipid. Apo(a) in UTC-TRL fractions had slow pre-beta electrophoretic mobility and was isolated in a lipoprotein size-range smaller than VLDL and larger than LDL, consistent with it being Lp(a). Recentrifugation of UTC-TRL resulted in the majority of apo(a) being recovered in the density > 1.006 g/ml fraction. Addition of proline to plasma samples before ultracentrifugation (final concentration: 0.1 M) substantially reduced the amount of Lp(a) in UTC-TRL. TRL separated from plasma by FPLC contained less apo(a) (2-5% of total plasma apo(a)), but this apo(a) was also readily dissociable from TRL lipid, had slow pre-beta electrophoretic mobility, and was associated with a lipoprotein with the size of Lp(a). Our data suggest that apo(a) in the TRL fraction of subjects with postprandial triglyceridemia or endogenous hypertriglyceridemia is not an integral component of plasma VLDL or chylomicrons, but represents the presence of non-covalently bound Lp(a).
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Affiliation(s)
- C Marcoux
- Hyperlipidemia and Atherosclerosis Research Group, Clinical Research Institute of Montreal, Quebec, Canada
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10
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Evans RW, Bunker CH, Ukoli FA, Kuller LH. Lipoprotein (a) distribution in a Nigerian population. ETHNICITY & HEALTH 1997; 2:47-58. [PMID: 9395588 DOI: 10.1080/13557858.1997.9961814] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
OBJECTIVES To determine the distribution and determinants of lipoprotein (a) (Lp(a)) concentration among Nigerians. METHODS Subjects were recruited from civil servants living in Benin City, Nigeria. The height and weight of the individuals were measured and their use of alcohol and tobacco estimated by questionnaire. Laboratory analyses of blood samples involved Lp(a), total cholesterol (TC), high-density lipoprotein (HDLc), HDL2c, HDL3c, triglyceride (TG) and insulin. RESULTS The analyses indicate that the Lp(a) concentrations are elevated among Nigerian populations and more skewed towards high levels than is observed for caucasian and oriental groups. The median levels for Lp(a) were 24.0 mg dl-1 and 19.0 mg dl-1 for women and men, respectively. This difference was significant (P < 0.05) but after stratifying by age, only the 45-54 year-old group of women (30.1 mg dl-1) had significantly higher (p < 0.001) median concentrations of Lp(a) than men (18.4 mg dl-1). Age, 20-64, had no influence on Lp(a) levels in men but in women Lp(a) concentrations increased significantly with age (p < 0.05). Among males alcohol consumption, smoking and body mass index (BMI) were not related to Lp(a) concentrations but a significant effect (p < 0.05) was noted for waist-hip ratio (WHR). Among females no relationship was observed between Lp(a) levels and alcohol consumption, BMI and WHR. All serum lipids measured (TC, HDLc, HDL2c, HDL3c, low-density lipoprotein (LDLc), and TG) were correlated with Lp(a) concentrations among men. A significant association with TC and LDLc remained after correcting for Lp(a) cholesterol. Among women, the Lp(a) levels were associated with TC, HDLc, HDL3c, and LDLc but not with HDL2c, and TG. The correlations with TC and LDLc were not significant after correcting for Lp(a) cholesterol. Insulin did not correlate with Lp(a) levels in either men or women. CONCLUSIONS Lp(a) concentrations are high in Nigerians, particularly among women, and the association between the Lp(a) concentrations and other lipoproteins is stronger than in white populations.
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Affiliation(s)
- R W Evans
- Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, PA 15261, USA
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Evans RW, Sankey SS, Hauth BA, Sutton-Tyrrell K, Kamboh MI, Kuller LH. Effect of sample storage on quantitation of lipoprotein(a) by an enzyme-linked immunosorbent assay. Lipids 1996; 31:1197-203. [PMID: 8934453 DOI: 10.1007/bf02524295] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
This study evaluated the effect of storage on the quantitation of lipoprotein (Lp)(a) in 25 serum samples. Aliquots of serum were stored for up to three years at either -20 degrees C or -70 degrees C and Lp(a) subsequently analyzed using an enzyme-linked immunosorbent assay kit. Concentrations of Lp(a) declined during storage, and the temperatures employed elicited significantly different (P < 0.05) values within 12 mon which further diverged during three years of storage. Compared to baseline values, significant decreases (P < 0.05) in Lp(a) levels were evident after six months of storage at -20 degrees C with apparent losses (geometric mean) reaching 36.9% (95% confidence interval: 30.9%, 42.9%) after three years. Similarly, significantly lower (P < 0.05) Lp(a) values were recorded after six months of storage at -70 degrees C and at three years the decrease (geometric mean) was 19.1% (95% confidence interval: 14.3%, 24.0%). The losses, after three years, in terms of the arithmetic mean were 53.5 and 26.2% at -20 and -70 degrees C, respectively. Phenotype analysis suggested that large isoforms are more susceptible to degradation than smaller moieties. This may be related to the observation that apparent losses are reduced in samples containing over 8 mg/dL Lp(a). Nevertheless, Lp(a) levels in stored samples retained a strong correlation with the baseline values. These results must be considered specific for the storage conditions and analytical procedures employed.
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Affiliation(s)
- R W Evans
- Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pennsylvania 15261, USA
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Hoppichler F, Kraft HG, Sandholzer C, Lechleitner M, Patsch JR, Utermann G. Lipoprotein(a) is increased in triglyceride-rich lipoproteins in men with coronary heart disease, but does not change acutely following oral fat ingestion. Atherosclerosis 1996; 122:127-34. [PMID: 8724119 DOI: 10.1016/0021-9150(96)05803-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Association of apo(a)/Lp(a) with triglyceride-rich lipoproteins (TGR-Lps) is determined by different factors that are poorly understood. Some previous studies suggested that apo(a) in TGR-Lps may affect the atherogenicity of the TGR particles. To study whether there are any peculiarities in postprandial (pp) Lp(a) metabolism, we have determined apo(a) phenotypes and Lp(a) concentrations in 46 subjects with coronary heart disease (CHD) and in six normolipidemic individuals at different time points (4, 6 and 8 h) following an oral fat tolerance test. While mean triglyceride concentration reached its maximum 6 h after a standardized fat meal, no change in total cholesterol and in mean Lp(a) plasma concentration was detected at any time point after the fat load. In 6 normolipidemic probands and in 8 patients with CHD, who were matched for apo(a) phenotype, lipoprotein levels, age and body weight, we followed the distribution of apo(a) in plasma density gradient fractions in the fasting and pp state. In the CHD patients a significant larger percentage of apo(a) reactivity was detected in TGR-Lps in the pre- as well as in the postprandial state, compared to control subjects. The fat intake did not induce a significant change of apo(a) reactivity in the TGR-Lp fractions in both groups. The apo(a) isoform-size and the Lp(a) plasma concentration in the fasting state had no influence on the individual variation of the Lp(a) concentration in pp TGR-Lp fractions. Our results provide evidence that TGR-Lp fractions of CHD patients are enriched in apo(a) reactivity compared to healthy controls, but do not support the hypothesis that Lp(a) acts atherogenically through a pp increase of its plasma concentration.
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Affiliation(s)
- F Hoppichler
- Department of Internal Medicine, University Hospital Innsbruck, Austria
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13
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Schmidt HH, Genschel JC, Wagner S, Manns MP. Quantification of lipoprotein(a): comparison of an automated latex-enhanced nephelometric assay with an immunoenzymometric method. EUROPEAN JOURNAL OF CLINICAL CHEMISTRY AND CLINICAL BIOCHEMISTRY : JOURNAL OF THE FORUM OF EUROPEAN CLINICAL CHEMISTRY SOCIETIES 1996; 34:119-24. [PMID: 8833643 DOI: 10.1515/cclm.1996.34.2.119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Several studies indicate the relevance of lipoprotein(a) (Lp(a)) in the genesis of premature coronary artery disease. A simple method for determining the concentration of Lp(a) is therefore of great interest for assessing the risk of coronary artery disease in patients. We compared a new latex-enhanced immunonephelometric assay (Behringwerke AG, Marburg, Germany), using the Behring Nephelometer System 100, with an established immunoenzymometric assay (Immuno, Heidelberg, Germany). A total of 163 patients was studied. Intra- and inter-assay coefficients of variation were between 2.2% and 7.1%, and between 3.4% and 8.6%, depending on the concentration of Lp(a). The correlation between the studied assays was excellent (r = 0.93, y = 0.98x -1.57, Spearman rank, Passing & Bablok). When values above 1000 mg/l for Lp(a) were excluded, the correlation was even higher. Increased light scattering with particle size, which hitherto has been a disadvantage of the nephelometric technique, seems to be negligible using the improved latex-enhanced approach. In patients with triacylglycerol values above 4.5 mmol/l (n = 19) there was no interference with the Behring system, i.e. the results of the nephelometric method were not increasing, and they agreed with those of the immunoenzymometric assay. In conclusion, this new latex-enhanced nephelometric immunoassay represents a rapid and precise method for the quantification of Lp(a).
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Affiliation(s)
- H H Schmidt
- Abt. Gastroenterologie und Hepatologie, Medizinische Hochschule Hannover, Germany
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14
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Evidence that Lp[a] contains one molecule of apo[a] and one molecule of apoB: evaluation of amino acid analysis data. J Lipid Res 1996. [DOI: 10.1016/s0022-2275(20)37647-1] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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15
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Walek T, von Eckardstein A, Schulte H, Assmann G. Effect of hypertriglyceridaemia on lipoprotein (a) serum concentrations. Eur J Clin Invest 1995; 25:311-6. [PMID: 7628517 DOI: 10.1111/j.1365-2362.1995.tb01707.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Numerous studies have shown lipoprotein (a) [Lp(a)] serum levels above 0.3 gL-1 to be a genetically determined and independent risk factor for atherosclerotic vascular disease. In this study of sera from 1009 patients attending our lipid clinics, multivariate regression analysis revealed an inverse correlation between the serum concentrations of triglycerides (TG) and Lp(a) (r = -0.31; P < 0.001) as determined by electroimmunodiffusion. This was not observed in 1237 controls from a random population. Detailed analysis of the frequency distribution of Lp(a) levels at different degrees of hypertriglyceridaemia (HTG) revealed a decreasing dosage effect of HTG on Lp(a) serum levels. In 60% of patients with TG > 9.12 mmol L-1, this effect led to undetectable serum Lp(a) levels. Dilution of hypertriglyceridaemic samples with normotriglyceridaemic sera containing high levels of Lp(a) revealed that analytical interference in part accounts for the decreasing effect of TG-rich lipoproteins on Lp(a). Re-evaluation of 45 hypertriglyceridaemic samples by enzyme immunoassay and immunoblotting revealed the presence of small amounts of Lp(a) in several samples which were considered to be free of Lp(a) upon electroimmunodiffusion. We conclude that TG-rich lipoproteins interfere with the quantification of Lp(a), at least by electroimmunodiffusion. However, HTG may also decrease Lp(a) plasma concentrations in vivo, possibly by increased clearance of TG-rich Lp(a).
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Affiliation(s)
- T Walek
- Institut für Klinische Chemie und Laboratoriumsmedizin, Westfäliche-Wilhelms-Universität Münster, Germany
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