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Koschinsky ML, Stroes ESG, Kronenberg F. Daring to dream: Targeting lipoprotein(a) as a causal and risk-enhancing factor. Pharmacol Res 2023; 194:106843. [PMID: 37406784 DOI: 10.1016/j.phrs.2023.106843] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 06/15/2023] [Accepted: 06/27/2023] [Indexed: 07/07/2023]
Abstract
Lipoprotein(a) [Lp(a)], a distinct lipoprotein class, has become a major focus for cardiovascular research. This review is written in light of the recent guideline and consensus statements on Lp(a) and focuses on 1) the causal association between Lp(a) and cardiovascular outcomes, 2) the potential mechanisms by which elevated Lp(a) contributes to cardiovascular diseases, 3) the metabolic insights on the production and clearance of Lp(a) and 4) the current and future therapeutic approaches to lower Lp(a) concentrations. The concentrations of Lp(a) are under strict genetic control. There exists a continuous relationship between the Lp(a) concentrations and risk for various endpoints of atherosclerotic cardiovascular disease (ASCVD). One in five people in the Caucasian population is considered to have increased Lp(a) concentrations; the prevalence of elevated Lp(a) is even higher in black populations. This makes Lp(a) a cardiovascular risk factor of major public health relevance. Besides the association between Lp(a) and myocardial infarction, the relationship with aortic valve stenosis has become a major focus of research during the last decade. Genetic studies provided strong support for a causal association between Lp(a) and cardiovascular outcomes: carriers of genetic variants associated with lifelong increased Lp(a) concentration are significantly more frequent in patients with ASCVD. This has triggered the development of drugs that can specifically lower Lp(a) concentrations: mRNA-targeting therapies such as anti-sense oligonucleotide (ASO) therapies and short interfering RNA (siRNA) therapies have opened new avenues to lower Lp(a) concentrations more than 95%. Ongoing Phase II and III clinical trials of these compounds are discussed in this review.
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Affiliation(s)
- Marlys L Koschinsky
- Robarts Research Institute, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Ontario, Canada; Department of Physiology & Pharmacology, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Ontario, Canada
| | - Erik S G Stroes
- Department of Vascular Medicine, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands
| | - Florian Kronenberg
- Institute of Genetic Epidemiology, Medical University of Innsbruck, Innsbruck, Austria.
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2
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Gianazza E, Zoanni B, Mallia A, Brioschi M, Colombo GI, Banfi C. Proteomic studies on apoB-containing lipoprotein in cardiovascular research: A comprehensive review. MASS SPECTROMETRY REVIEWS 2023; 42:1397-1423. [PMID: 34747518 DOI: 10.1002/mas.21747] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 08/05/2021] [Accepted: 08/16/2021] [Indexed: 06/07/2023]
Abstract
The complexity of cardiovascular diseases (CVDs), which remains the leading cause of death worldwide, makes the current clinical pathway for cardiovascular risk assessment unsatisfactory, as there remains a substantial unexplained residual risk. Simultaneous assessment of a large number of plasma proteins may be a promising tool to further refine risk assessment, and lipoprotein-associated proteins have the potential to fill this gap. Technical advances now allow for high-throughput proteomic analysis in a reproducible and cost-effective manner. Proteomics has great potential to identify and quantify hundreds of candidate marker proteins in a sample and allows the translation from isolated lipoproteins to whole plasma, thus providing an individual multiplexed proteomic fingerprint. This narrative review describes the pathophysiological roles of atherogenic apoB-containing lipoproteins and the recent advances in their mass spectrometry-based proteomic characterization and quantitation for better refinement of CVD risk assessment.
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Affiliation(s)
| | | | - Alice Mallia
- Centro Cardiologico Monzino, IRCCS, Milano, Italy
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3
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Matveyenko A, Matienzo N, Ginsberg H, Nandakumar R, Seid H, Ramakrishnan R, Holleran S, Thomas T, Reyes-Soffer G. Relationship of apolipoprotein(a) isoform size with clearance and production of lipoprotein(a) in a diverse cohort. J Lipid Res 2023; 64:100336. [PMID: 36706955 PMCID: PMC10006688 DOI: 10.1016/j.jlr.2023.100336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 01/16/2023] [Accepted: 01/22/2023] [Indexed: 01/26/2023] Open
Abstract
Lipoprotein(a) [Lp(a)] has two main proteins, apoB100 and apo(a). High levels of Lp(a) confer an increased risk for atherosclerotic cardiovascular disease. Most people have two circulating isoforms of apo(a) differing in their molecular mass, determined by the number of Kringle IV Type 2 repeats. Previous studies report a strong inverse relationship between Lp(a) levels and apo(a) isoform sizes. The roles of Lp(a) production and fractional clearance and how ancestry affects this relationship remain incompletely defined. We therefore examined the relationships of apo(a) size with Lp(a) levels and both apo(a) fractional clearance rates (FCR) and production rates (PR) in 32 individuals not on lipid-lowering treatment. We determined plasma Lp(a) levels and apo(a) isoform sizes, and used the relative expression of the two isoforms to calculate a "weighted isoform size" (wIS). Stable isotope studies were performed, using D3-leucine, to determine the apo(a) FCR and PR. As expected, plasma Lp(a) concentrations were inversely correlated with wIS (R2 = 0.27; P = 0.002). The wIS had a modest positive correlation with apo(a) FCR (R2 = 0.10, P = 0.08), and a negative correlation with apo(a) PR (R2 = 0.11; P = 0.06). The relationship between wIS and PR became significant when we controlled for self-reported race and ethnicity (SRRE) (R2 = 0.24, P = 0.03); controlling for SRRE did not affect the relationship between wIS and FCR. Apo(a) wIS plays a role in both FCR and PR; however, adjusting for SRRE strengthens the correlation between wIS and PR, suggesting an effect of ancestry.
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Affiliation(s)
- Anastasiya Matveyenko
- Department of Medicine, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Nelsa Matienzo
- Department of Medicine, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Henry Ginsberg
- Department of Medicine, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Renu Nandakumar
- Irving Institute for Clinical and Translational Research, Columbia University, New York, NY, USA
| | - Heather Seid
- Irving Institute for Clinical and Translational Research, Columbia University, New York, NY, USA
| | - Rajasekhar Ramakrishnan
- Center for Biomathematics, Department of Pediatrics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Steve Holleran
- Center for Biomathematics, Department of Pediatrics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Tiffany Thomas
- Department of Pathology and Cell Biology, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Gissette Reyes-Soffer
- Department of Medicine, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA.
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Fogacci F, Borghi C, Davinelli S, Scapagnini G, Cicero AFG. Impact of anti-oestrogen therapy on lipoprotein(a) in postmenopausal women: a systematic review and meta-analysis of double-blind placebo-controlled clinical studies. Endocrine 2022; 80:292-302. [PMID: 36542268 DOI: 10.1007/s12020-022-03287-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 12/13/2022] [Indexed: 12/24/2022]
Abstract
PURPOSE The potential mechanisms of endocrine therapy for thrombosis remain currently unclear, and more studies are warranted for further investigation and elucidation. However, high plasma concentration of lipoprotein(a) (Lp(a)) is a recognized prothrombotic factor. The aim of our study was to systematically evaluate the effect of different anti-oestrogen therapy on plasma Lp(a) level in postmenopausal women. METHODS A systematic literature search was conducted in multiple electronic databases to identify the randomized, double-blind, placebo-controlled clinical studies on this topic. Effect size for changes in Lp(a) was expressed as mean difference (MD) and 95% confidence intervals (CI). RESULTS Data were pooled from 10 clinical trials comprising 24 treatment arms, which included 2049 women (1128 women in the active-treated arms and 921 women in the control arms). Meta-analysis of data suggested that anti-oestrogen therapy in women significantly reduced Lp(a) [MD = -5.92% (95%CI: -9.05%,-2.8%)]. CONCLUSIONS This observation is of both clinical and pathophysiological relevance, also in view that the identification of molecular determinants and cellular pathways implicated in Lp(a) synthesis and metabolism is still of concern as a critical issue in lipidology and CV prevention.
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Affiliation(s)
- Federica Fogacci
- Hypertension and Cardiovascular Risk Research Group, Medical and Surgical Sciences Department, Sant'Orsola-Malpighi University Hospital, 40138, Bologna, Italy
| | - Claudio Borghi
- Hypertension and Cardiovascular Risk Research Group, Medical and Surgical Sciences Department, Sant'Orsola-Malpighi University Hospital, 40138, Bologna, Italy
- IRCCS Azienda Ospedaliero-Universitaria di Bologna, 40138, Bologna, Italy
| | - Sergio Davinelli
- Department of Medicine and Health Sciences, University of Molise, Campobasso, Italy
| | - Giovanni Scapagnini
- Department of Medicine and Health Sciences, University of Molise, Campobasso, Italy
| | - Arrigo F G Cicero
- Hypertension and Cardiovascular Risk Research Group, Medical and Surgical Sciences Department, Sant'Orsola-Malpighi University Hospital, 40138, Bologna, Italy.
- IRCCS Azienda Ospedaliero-Universitaria di Bologna, 40138, Bologna, Italy.
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Seo YH, Shin HY. Relationship between Lipoprotein(a) and Dyslipidemia in the Elderly over 60 Years. KOREAN JOURNAL OF CLINICAL LABORATORY SCIENCE 2022. [DOI: 10.15324/kjcls.2022.54.2.95] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Affiliation(s)
- Yo-Han Seo
- Department of Laboratory Medicine, Gwangju Veterans Hospital, Gwangju, Korea
| | - Hee-Young Shin
- Department of Biomedical Science, Chonnam National University Medical School, Gwangju, Korea
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Buchmann N, Ittermann T, Demuth I, Markus MRP, Völzke H, Dörr M, Friedrich N, Lerch MM, Santos RD, Schipf S, Steinhagen-Thiessen E. Lipoprotein(a) and Metabolic Syndrome. DEUTSCHES ARZTEBLATT INTERNATIONAL 2022; 119:270-276. [PMID: 35331368 PMCID: PMC9400195 DOI: 10.3238/arztebl.m2022.0153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 08/25/2021] [Accepted: 02/17/2022] [Indexed: 06/14/2023]
Abstract
BACKGROUND An inverse association between lipoprotein(a) (Lp[a]) and type 2 diabetes mellitus is well documented. However, data on the association of the metabolic syndrome (MetS) with Lp(a) are sparse. METHODS Cross-sectional data for MetS and Lp(a) were available for 5743 BASE-II and SHIP-0 participants (48.7% men; age 58 [20-85] years) (BASE, Berlin Aging Study; SHIP, Study of Health in Pomerania). The association of MetS and its components with Lp(a) was analyzed by means of median regression adjusted for age, sex, and study. Associations were evaluated for the total population as well as stratified by sex and menopausal status. RESULTS Overall, 27.6% (n = 1573) of the participants in the two studies had MetS and 22.5% (n = 1291) were premenopausal women. There was an inverse association between MetS and Lp(a) in the whole study sample (β = -11.9, 95% confidence interval [-21.3; -2.6]) as well as in men (β = -16.5 [-28.6; -4.3]). Participants with MetS (whole study sample) had 11.9 mmol/L lower Lp(a). Analogous results were found in postmenopausal women (β = -25.4 [-46.0; -4.8]). In premenopausal women with MetS, Lp(a) levels were higher by 39.1 mg/L on average [12.3; 65.9]) than in premenopausal women without MetS. CONCLUSION Hormonal aspects and menopausal alterations seem to affect the association between MetS and Lp(a), as the expected inverse association was not present in premenopausal women.
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Affiliation(s)
- Nikolaus Buchmann
- Department of Cardiology, Benjamin Franklin Campus, Charité – University Medical Center Berlin: Dr. med. Nikolaus Buchmann
| | - Till Ittermann
- Institute for Community Medicine, University Medical Center Greifswald: Dr. rer. med. Till Ittermann, Prof. Dr. med. Henry Völzke, Dr. rer. med. Sabine Schipf
| | - Ilja Demuth
- Biology of Aging Group, Department of Endocrinology and Metabolic Medicine (including Lipid Metabolism), Charité – University Medical Center Berlin, corporate member of Free University Berlin and Humboldt University of Berlin: Prof. Dr. rer. nat. Ilja Demuth, Prof. Dr. med. Elisabeth Steinhagen-Thiessen
- Berlin Institute for Health Research at Charité – University Medical Center Berlin, BCRT – Berlin Center for Regenerative Therapy: Prof. Dr. rer. nat. Ilja Demuth
| | - Marcello R. P. Markus
- Department of Internal Medicine B, University Medical Center Greifswald: Dr. med. Marcello R. P. Markus, Prof. Dr. med. Marcus Dörr
- German Center for Diabetes Research (DZD), Greifswald Site, Greifswald: Dr. med. Marcello R. P. Markus, Prof. Dr. med. Henry Völzke, Prof. Dr. med. Marcus Dörr, Dr. rer. med. Sabine Schipf
- German Center for Cardiovascular Research (DZHK), Greifswald Site, Greifswald: Dr. med. Marcello R. P. Markus, Prof. Dr. med. Henry Völzke, Prof. Dr. med. Marcus Dörr
| | - Henry Völzke
- Institute for Community Medicine, University Medical Center Greifswald: Dr. rer. med. Till Ittermann, Prof. Dr. med. Henry Völzke, Dr. rer. med. Sabine Schipf
- German Center for Diabetes Research (DZD), Greifswald Site, Greifswald: Dr. med. Marcello R. P. Markus, Prof. Dr. med. Henry Völzke, Prof. Dr. med. Marcus Dörr, Dr. rer. med. Sabine Schipf
- German Center for Cardiovascular Research (DZHK), Greifswald Site, Greifswald: Dr. med. Marcello R. P. Markus, Prof. Dr. med. Henry Völzke, Prof. Dr. med. Marcus Dörr
| | - Marcus Dörr
- Department of Internal Medicine B, University Medical Center Greifswald: Dr. med. Marcello R. P. Markus, Prof. Dr. med. Marcus Dörr
- German Center for Diabetes Research (DZD), Greifswald Site, Greifswald: Dr. med. Marcello R. P. Markus, Prof. Dr. med. Henry Völzke, Prof. Dr. med. Marcus Dörr, Dr. rer. med. Sabine Schipf
- German Center for Cardiovascular Research (DZHK), Greifswald Site, Greifswald: Dr. med. Marcello R. P. Markus, Prof. Dr. med. Henry Völzke, Prof. Dr. med. Marcus Dörr
| | - Nele Friedrich
- Institute for Clinical Chemistry and Laboratory Medicine, University Medical Center Greifswald: Dr. rer. med. Nele Friedrich
| | - Markus M. Lerch
- Department of Internal Medicine A, University Medical Center Greifswald: Prof. Dr. med. Markus M. Lerch
| | - Raul D. Santos
- Lipid Clinic, Heart Institute (InCor), Medical Teaching Hospital, University of São Paulo, Brazil: Prof. Raul D. Santos, MD, PhD
| | - Sabine Schipf
- Institute for Community Medicine, University Medical Center Greifswald: Dr. rer. med. Till Ittermann, Prof. Dr. med. Henry Völzke, Dr. rer. med. Sabine Schipf
- German Center for Diabetes Research (DZD), Greifswald Site, Greifswald: Dr. med. Marcello R. P. Markus, Prof. Dr. med. Henry Völzke, Prof. Dr. med. Marcus Dörr, Dr. rer. med. Sabine Schipf
| | - Elisabeth Steinhagen-Thiessen
- Biology of Aging Group, Department of Endocrinology and Metabolic Medicine (including Lipid Metabolism), Charité – University Medical Center Berlin, corporate member of Free University Berlin and Humboldt University of Berlin: Prof. Dr. rer. nat. Ilja Demuth, Prof. Dr. med. Elisabeth Steinhagen-Thiessen
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Clark JR, Gemin M, Youssef A, Marcovina SM, Prat A, Seidah NG, Hegele RA, Boffa MB, Koschinsky ML. Sortilin enhances secretion of apolipoprotein(a) through effects on apolipoprotein B secretion and promotes uptake of lipoprotein(a). J Lipid Res 2022; 63:100216. [PMID: 35469919 PMCID: PMC9131257 DOI: 10.1016/j.jlr.2022.100216] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 04/06/2022] [Accepted: 04/08/2022] [Indexed: 12/30/2022] Open
Abstract
Elevated plasma lipoprotein(a) (Lp(a)) is an independent, causal risk factor for atherosclerotic cardiovascular disease and calcific aortic valve stenosis. Lp(a) is formed in or on hepatocytes from successive noncovalent and covalent interactions between apo(a) and apoB, although the subcellular location of these interactions and the nature of the apoB-containing particle involved remain unclear. Sortilin, encoded by the SORT1 gene, modulates apoB secretion and LDL clearance. We used a HepG2 cell model to study the secretion kinetics of apo(a) and apoB. Overexpression of sortilin increased apo(a) secretion, while siRNA-mediated knockdown of sortilin expression correspondingly decreased apo(a) secretion. Sortilin binds LDL but not apo(a) or Lp(a), indicating that its effect on apo(a) secretion is likely indirect. Indeed, the effect was dependent on the ability of apo(a) to interact noncovalently with apoB. Overexpression of sortilin enhanced internalization of Lp(a), but not apo(a), by HepG2 cells, although neither sortilin knockdown in these cells or Sort1 deficiency in mice impacted Lp(a) uptake. We found several missense mutations in SORT1 in patients with extremely high Lp(a) levels; sortilin containing some of these mutations was more effective at promoting apo(a) secretion than WT sortilin, though no differences were found with respect to Lp(a) internalization. Our observations suggest that sortilin could play a role in determining plasma Lp(a) levels and corroborate in vivo human kinetic studies which imply that secretion of apo(a) and apoB are coupled, likely within the hepatocyte.
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Affiliation(s)
- Justin R Clark
- Department of Physiology & Pharmacology, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, ON, Canada
| | - Matthew Gemin
- Department of Chemistry & Biochemistry, University of Windsor, Windsor, ON, Canada
| | - Amer Youssef
- Robarts Research Institute, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, ON, Canada
| | | | - Annik Prat
- Institut de Recherches Cliniques de Montreal, Montréal, QC, Canada
| | - Nabil G Seidah
- Institut de Recherches Cliniques de Montreal, Montréal, QC, Canada
| | - Robert A Hegele
- Robarts Research Institute, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, ON, Canada; Department of Biochemistry, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, ON, Canada; Department of Medicine, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, ON, Canada
| | - Michael B Boffa
- Robarts Research Institute, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, ON, Canada; Department of Biochemistry, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, ON, Canada
| | - Marlys L Koschinsky
- Department of Physiology & Pharmacology, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, ON, Canada; Robarts Research Institute, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, ON, Canada.
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Chemello K, Blom DJ, Marais AD, Lambert G, Blanchard V. Genetic and Mechanistic Insights into the Modulation of Circulating Lipoprotein (a) Concentration by Apolipoprotein E Isoforms. Curr Atheroscler Rep 2022; 24:399-405. [PMID: 35355214 DOI: 10.1007/s11883-022-01016-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/04/2022] [Indexed: 01/04/2023]
Abstract
PURPOSE OF REVIEW Lipoprotein (a) [Lp(a)] is a highly atherogenic lipoprotein species. A unique feature of Lp(a) is the strong genetic determination of its concentration. The LPA gene is responsible for up to 90% of the variance in Lp(a), but other genes also have an impact. RECENT FINDINGS Genome-wide associations studies indicate that the APOE gene, encoding apolipoprotein E (apoE), is the second most important locus modulating Lp(a) concentrations. Population studies clearly show that carriers of the apoE2 variant (ε2) display reduced Lp(a) levels, the lowest concentrations being observed in ε2/ε2 homozygotes. This genotype can lead predisposed adults to develop dysbetalipoproteinemia, a lipid disorder characterized by sharp elevations in cholesterol and triglycerides. However, dysbetalipoproteinemia does not significantly modulate circulating Lp(a). Mechanistically, apoE appears to impair the production but not the catabolism of Lp(a). These observations underline the complexity of Lp(a) metabolism and provide key insights into the pathways governing Lp(a) synthesis and secretion.
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Affiliation(s)
- Kévin Chemello
- Laboratoire Inserm, UMR 1188 DéTROI, Université de La Réunion, 2 Rue Maxime Rivière, 97490, Sainte Clotilde, France
| | - Dirk J Blom
- Division of Lipidology and Cape Heart Institute, Department of Medicine, University of Cape Town, Cape Town, South Africa
| | - A David Marais
- Division of Chemical Pathology, Department of Pathology, University of Cape Town, Cape Town, South Africa
| | - Gilles Lambert
- Laboratoire Inserm, UMR 1188 DéTROI, Université de La Réunion, 2 Rue Maxime Rivière, 97490, Sainte Clotilde, France.
| | - Valentin Blanchard
- Laboratoire Inserm, UMR 1188 DéTROI, Université de La Réunion, 2 Rue Maxime Rivière, 97490, Sainte Clotilde, France.,Departments of Medicine, Centre for Heart Lung Innovation, Providence Healthcare Research Institute, St. Paul's Hospital, University of British Columbia, Vancouver, Canada
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Youssef A, Clark JR, Marcovina SM, Boffa MB, Koschinsky ML. Apo(a) and ApoB Interact Noncovalently Within Hepatocytes: Implications for Regulation of Lp(a) Levels by Modulation of ApoB Secretion. Arterioscler Thromb Vasc Biol 2022; 42:289-304. [PMID: 35045727 DOI: 10.1161/atvbaha.121.317335] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND Elevated plasma Lp(a) (lipoprotein(a)) levels are associated with increased risk for atherosclerotic cardiovascular disease and aortic valve stenosis. However, the cell biology of Lp(a) biosynthesis remains poorly understood, with the locations of the noncovalent and covalent steps of Lp(a) assembly unclear and the nature of the apoB-containing particle destined for Lp(a) unknown. We, therefore, asked if apo(a) and apoB interact noncovalently within hepatocytes and if this impacts Lp(a) biosynthesis. METHODS Using human hepatocellular carcinoma cells expressing 17K (17 kringle) apo(a), or a 17KΔLBS7,8 variant with a reduced ability to bind noncovalently to apoB, we performed coimmunoprecipitation, coimmunofluorescence, and proximity ligation assays to document intracellular apo(a):apoB interactions. We used a pulse-chase metabolic labeling approach to measure apo(a) and apoB secretion rates. RESULTS Noncovalent complexes containing apo(a)/apoB are present in lysates from cells expressing 17K but not 17KΔLBS7,8, whereas covalent apo(a)/apoB complexes are absent from lysates. 17K and apoB colocalized intracellularly, overlapping with staining for markers of endoplasmic reticulum trans-Golgi, and early endosomes, and less so with lysosomes. The 17KΔLBS7,8 had lower colocalization with apoB. Proximity ligation assays directly documented intracellular 17K/apoB interactions, which were dramatically reduced for 17KΔLBS7,8. Treatment of cells with PCSK9 (proprotein convertase subtilisin/kexin type 9) enhanced, and lomitapide reduced, apo(a) secretion in a manner dependent on the noncovalent interaction between apo(a) and apoB. Apo(a) secretion was also reduced by siRNA-mediated knockdown of APOB. CONCLUSIONS Our findings explain the coupling of apo(a) and Lp(a)-apoB production observed in human metabolic studies using stable isotopes as well as the ability of agents that inhibit apoB biosynthesis to lower Lp(a) levels.
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Affiliation(s)
- Amer Youssef
- Robarts Research Institute (A.Y., M.B.B., M.L.K.), Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Canada
| | - Justin R Clark
- Department of Physiology & Pharmacology (J.R.C., M.L.K.), Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Canada
| | | | - Michael B Boffa
- Robarts Research Institute (A.Y., M.B.B., M.L.K.), Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Canada.,Department of Biochemistry (M.B.B.), Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Canada
| | - Marlys L Koschinsky
- Robarts Research Institute (A.Y., M.B.B., M.L.K.), Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Canada.,Department of Physiology & Pharmacology (J.R.C., M.L.K.), Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Canada
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10
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Chan DC, Watts GF, Coll B, Wasserman SM, Marcovina SM, Barrett PHR. Lipoprotein(a) Particle Production as a Determinant of Plasma Lipoprotein(a) Concentration Across Varying Apolipoprotein(a) Isoform Sizes and Background Cholesterol-Lowering Therapy. J Am Heart Assoc 2020; 8:e011781. [PMID: 30897995 PMCID: PMC6509712 DOI: 10.1161/jaha.118.011781] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Background Elevated lipoprotein(a) (Lp(a)), a low‐density lipoprotein‐like particle bound to the polymorphic apolipoprotein(a) (apo(a)), may be causal for cardiovascular disease. However, the metabolism of Lp(a) in humans is poorly understood. Methods and Results We investigated the kinetics of Lp(a)‐apo(a) and low‐density lipoprotein‐apoB‐100 in 63 normolipidemic men. The fractional catabolic rate (FCR) and production rate PR) were studied. Plasma apo(a) concentration was significantly and inversely associated with apo(a) isoform size (r=−0.536, P<0.001) and apo(a) FCR (r=−0.363, P<0.01), and positively with apo(a) PR (r=0.877, P<0.001). There were no significant associations between the FCRs of apo(a) and low‐density lipoprotein‐apoB‐100. Subjects with smaller apo(a) isoform sizes (≤22 kringle IV repeats) had significantly higher apo(a) PR (P<0.05) and lower apo(a) FCR (P<0.01) than those with larger sizes. Plasma apo(a) concentration was significantly associated with apo(a) PR (r=0.930, P<0.001), but not with FCR (r=−0.012, P>0.05) in subjects with smaller apo(a) isoform size. In contrast, both apo(a) PR and FCR were significantly associated with plasma apo(a) concentrations (r=0.744 and −0.389, respectively, P<0.05) in subjects with larger isoforms. In multiple regression analysis, apo(a) PR and apo(a) isoform size were significant predictors of plasma apo(a) concentration independent of low‐density lipoprotein‐apoB‐100 FCR and background therapy with atorvastatin and evolocumab. Conclusions In normolipidemic men, the plasma Lp(a) concentration is predominantly determined by the rate of production of Lp(a) particles, irrespective of apo(a) isoform size and background therapy with a statin and a proprotein convertase subtilisin‐kexin type 9 inhibitor. Our findings underscore the importance of therapeutic targeting of the hepatic synthesis and secretion of Lp(a) particles. Lp(a) particle catabolism may only play a modest role in determining Lp(a) concentration in subjects with larger apo(a) isoform size. Clinical Trial Registration URL: http://www.clinicaltrials.gov. Unique identifier: NCT02189837.
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Affiliation(s)
- Dick C Chan
- 1 School of Medicine University of Western Australia Perth Australia.,2 School of Biomedical Science University of Western Australia Perth Australia
| | - Gerald F Watts
- 1 School of Medicine University of Western Australia Perth Australia.,3 The Lipid Disorders Clinic Department of Cardiology Royal Perth Hospital Perth Australia
| | | | | | - Santica M Marcovina
- 5 Northwest Lipid Metabolism and Diabetes Research Laboratories Division of Metabolism, Endocrinology, and Nutrition Department of Medicine University of Washington Seattle WA
| | - P Hugh R Barrett
- 2 School of Biomedical Science University of Western Australia Perth Australia.,6 Faculty of Medicine and Health University of New England Armidale New South Wales Australia
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11
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Bartens W, Nauck M, Schollmeyer P, Wanner C. Elevated Llpoprotein(A) and Fibrinogen Serum Levels Increase the Cardiovascular Risk in Continuous Ambulatory Peritoneal Dialysis Patients. Perit Dial Int 2020. [DOI: 10.1177/089686089601600109] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
ObjectiveTo analyze the relationship between lipoprotein(a) [Lp(a)] and fibrinogen as potential cardiovascular risk factors in patients on continuous ambulatory peritoneal dialysis (CAPD).PatientsA total of 47 uremic patients receiving CAPD, 21 with coronary artery disease (CAD), 26 without CAD.MeasurementsLp(a) levels were determined by an immunoradiometric assay. Since Lp(a) serum concentrations vary depending on the size, apoprotein(a) [apo(a)] isoforms were determined (Westernblot). Fibrinogen was quantified according to Clauss.ResultsThe mean Lp(a) serum concentration was 43 ± 5 mg/dL (SEM) (median 33 mg/dL) in CAPD patients and 21 ± 2 mg/dL (8 mg/dL) in controls (p < 0.01). Patients with low molecular weight apo(a) isoforms exhibited substantially elevated Lp(a) levels when compared with patients with high molecular isoforms (p < 0.01). In addition, we found elevated fibrinogen levels in the CAPD patients (538 ± 61 mg/dL) compared with healthy controls (288 ± 46 mg/dL). Twenty-one CAPD patients (45%) were suffering from CAD. Patients with CAD had higher Lp(a) levels (54 ± 5 mg/dL vs 34 ± 4 mg/dL) as well as higher fibrinogen concentrations (628 ± 59 mg/dL vs 459 ± 46 mg/dL). Furthermore, a positive correlation between the fibrinogen levels and the Lp(a) serum concentration was observed (r = 0.45, p = 0.01).ConclusionWe suggest that elevated Lp(a) levels are influenced by the allelic variation of the apo(a) isoform. In addition to the typical dyslipidemia found in CAPD patients, high levels of Lp(a) and fibrinogen may contribute to the elevated risk of coronary artery disease and other cardiovascular complications.
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Affiliation(s)
- Werner Bartens
- Department of Medicine, Divisions of Nephrology and Clinical Chemistry, University Clinic Freiburg, Würzburg, Germany
| | - Matthias Nauck
- Department of Medicine, Divisions of Nephrology and Clinical Chemistry, University Clinic Freiburg, Würzburg, Germany
| | - Peter Schollmeyer
- Department of Medicine, Divisions of Nephrology and Clinical Chemistry, University Clinic Freiburg, Würzburg, Germany
| | - Christoph Wanner
- Department of Medicine, Divisions of Nephrology and Clinical Chemistry, University Clinic Freiburg, Würzburg, Germany
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12
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Ma L, Chan DC, Ooi EMM, Marcovina SM, Barrett PHR, Watts GF. Apolipoprotein(a) Kinetics in Statin-Treated Patients With Elevated Plasma Lipoprotein(a) Concentration. J Clin Endocrinol Metab 2019; 104:6247-6255. [PMID: 31393573 DOI: 10.1210/jc.2019-01382] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 08/02/2019] [Indexed: 02/08/2023]
Abstract
BACKGROUND Lipoprotein(a) [Lp(a)] is a low-density lipoprotein‒like particle containing apolipoprotein(a) [apo(a)]. Patients with elevated Lp(a), even when treated with statins, are at increased risk of cardiovascular disease. We investigated the kinetic basis for elevated Lp(a) in these patients. OBJECTIVES Apo(a) production rate (PR) and fractional catabolic rate (FCR) were compared between statin-treated patients with and without elevated Lp(a). METHODS The kinetics of apo(a) were investigated in 14 patients with elevated Lp(a) and 15 patients with normal Lp(a) levels matched for age, sex, and body mass index using stable isotope techniques and compartmental modeling. All 29 patients were on background statin treatment. Plasma apo(a) concentration was measured using liquid chromatography-mass spectrometry. RESULTS The plasma concentration and PR of apo(a) were significantly higher in patients with elevated Lp(a) than in patients with normal Lp(a) concentration (all P < 0.01). The FCR of apo(a) was not significantly different between the groups. In univariate analysis, plasma concentration of apo(a) was significantly associated with apo(a) PR in both patient groups (r = 0.699 and r = 0.949, respectively; all P < 0.01). There was no significant association between plasma apo(a) concentration and FCR in either of the groups (r = 0.160 and r = -0.137, respectively). CONCLUSION Elevated plasma Lp(a) concentration is a consequence of increased hepatic production of Lp(a) particles in these patients. Our findings provide a kinetic rationale for the use of therapies that target the synthesis of apo(a) and production of Lp(a) particles in patients with elevated Lp(a).
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Affiliation(s)
- Louis Ma
- School of Biomedical Sciences, Faculty of Health and Medicine, University of Western Australia, Perth, Western Australia, Australia
- School of Medicine, Faculty of Health and Medicine, University of Western Australia, Perth, Western Australia, Australia
| | - Dick C Chan
- School of Biomedical Sciences, Faculty of Health and Medicine, University of Western Australia, Perth, Western Australia, Australia
- School of Medicine, Faculty of Health and Medicine, University of Western Australia, Perth, Western Australia, Australia
| | - Esther M M Ooi
- School of Biomedical Sciences, Faculty of Health and Medicine, University of Western Australia, Perth, Western Australia, Australia
| | - Santica M Marcovina
- Northwest Lipid Metabolism and Diabetes Research Laboratories, Division of Metabolism, Endocrinology, and Nutrition, Department of Medicine, University of Washington, Seattle, Washington
| | - P Hugh R Barrett
- Faculty of Medicine and Health, University of New England, Armidale, New South Wales, Australia
| | - Gerald F Watts
- School of Medicine, Faculty of Health and Medicine, University of Western Australia, Perth, Western Australia, Australia
- Lipid Disorders Clinic, Department of Cardiology, Royal Perth Hospital, Perth, Western Australia, Australia
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13
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Rawther T, Tabet F. Biology, pathophysiology and current therapies that affect lipoprotein (a) levels. J Mol Cell Cardiol 2019; 131:1-11. [DOI: 10.1016/j.yjmcc.2019.04.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 03/22/2019] [Accepted: 04/09/2019] [Indexed: 12/11/2022]
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14
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Tada H, Takamura M, Kawashiri MA. Lipoprotein(a) as an Old and New Causal Risk Factor of Atherosclerotic Cardiovascular Disease. J Atheroscler Thromb 2019; 26:583-591. [PMID: 31061262 PMCID: PMC6629747 DOI: 10.5551/jat.rv17034] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Lipoprotein(a) [Lp(a)], discovered in 1963, has been associated with atherosclerotic cardiovascular disease (ASCVD) independent of other traditional risk factors, including LDL cholesterol. Lp(a) is an apolipoprotein B (apoB)-containing lipoprotein, which contains an LDL-like particle. Unlike LDL, which is a primary therapeutic target to decrease ASCVD, current guidelines recommend measuring Lp(a) for risk assessments because there is no clear evidence demonstrating the clinical benefit of decreasing Lp(a) using classical drugs such as niacin. However, recent Mendelian randomization studies indicate that Lp(a) causally correlates with ASCVD. In addition, novel drugs, including PCSK9 inhibitors, as well as antisense oligonucleotide for apo(a), have exhibited efficacy in decreasing Lp(a) substantially, invigorating a discussion whether Lp(a) could be a novel therapeutic target for further ASCVD risk reduction. This review aims to provide current understanding, and future perspectives, of Lp(a), which is currently considered a mere biomarker but may emerge as a novel therapeutic target in future clinical settings.
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Affiliation(s)
- Hayato Tada
- Department of Cardiology, Kanazawa University Graduate School of Medical Science
| | - Masayuki Takamura
- Department of Cardiology, Kanazawa University Graduate School of Medical Science
| | - Masa-Aki Kawashiri
- Department of Cardiology, Kanazawa University Graduate School of Medical Science
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15
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Borrelli MJ, Youssef A, Boffa MB, Koschinsky ML. New Frontiers in Lp(a)-Targeted Therapies. Trends Pharmacol Sci 2019; 40:212-225. [PMID: 30732864 DOI: 10.1016/j.tips.2019.01.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 01/07/2019] [Accepted: 01/08/2019] [Indexed: 12/13/2022]
Abstract
Interest in lipoprotein (a) [Lp(a)] has exploded over the past decade with the emergence of genetic and epidemiological studies pinpointing elevated levels of this unique lipoprotein as a causal risk factor for atherosclerotic cardiovascular disease (ASCVD) and calcific aortic valve disease (CAVD). This review summarizes the most recent discoveries regarding therapeutic approaches to lower Lp(a) and presents these findings in the context of an emerging, although far from complete, understanding of the biosynthesis and catabolism of Lp(a). Application of Lp(a)-specific lowering agents to outcome trials will be the key to opening this new frontier in the battle against CVD.
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Affiliation(s)
- Matthew J Borrelli
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada
| | - Amer Youssef
- Robarts Research Institute, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada
| | - Michael B Boffa
- Robarts Research Institute, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada; Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada
| | - Marlys L Koschinsky
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada; Robarts Research Institute, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada.
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16
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Boffa MB, Koschinsky ML. Oxidized phospholipids as a unifying theory for lipoprotein(a) and cardiovascular disease. Nat Rev Cardiol 2019; 16:305-318. [DOI: 10.1038/s41569-018-0153-2] [Citation(s) in RCA: 114] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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17
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Abstract
Clinical trials have unequivocally shown that inhibition of proprotein convertase subtilisin/kexin type 9 (PCSK9) efficaciously and safely prevents cardiovascular events by lowering levels of LDL cholesterol. PCSK9 in the circulation is derived mainly from the liver, but the protein is also expressed in the pancreas, the kidney, the intestine and the central nervous system. Although PCSK9 modulates cholesterol metabolism by regulating LDL receptor expression in the liver, in vitro and in vivo studies have suggested that PCSK9 is involved in various other physiological processes. Although therapeutic PCSK9 inhibition could theoretically have undesired effects by interfering with these non-cholesterol-related processes, studies of individuals with genetically determined reduced PCSK9 function and clinical trials of PCSK9 inhibitors have not revealed clinically meaningful adverse consequences of almost completely eradicating PCSK9 from the circulation. The clinical implications of PCSK9 functions beyond lipid metabolism in terms of wanted or unwanted effects of therapeutic PCSK9 inhibition therefore appear to be limited. The objective of this Review is to describe the physiological role of PCSK9 beyond the LDL receptor to provide a rational basis for monitoring the effects of PCSK9 inhibition as these drugs gain traction in the clinic.
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Affiliation(s)
| | - Gilles Lambert
- Inserm UMR 1188 DéTROI, Université de La Réunion, Saint-Denis de La Réunion, France
| | - Bertrand Cariou
- L'institut du thorax, INSERM, CNRS, Université de Nantes, CHU Nantes, Nantes, France
| | - G Kees Hovingh
- Department of Vascular Medicine, Academisch Medisch Centrum, Amsterdam, Netherlands.
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18
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Beukhof CM, Massolt ET, Visser TJ, Korevaar TIM, Medici M, de Herder WW, Roeters van Lennep JE, Mulder MT, de Rijke YB, Reiners C, Verburg FA, Peeters RP. Effects of Thyrotropin on Peripheral Thyroid Hormone Metabolism and Serum Lipids. Thyroid 2018; 28:168-174. [PMID: 29316865 DOI: 10.1089/thy.2017.0330] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Subclinical hypothyroidism is associated with dyslipidemia and atherosclerosis. Whether these effects are in part mediated via direct effects of thyrotropin (TSH) on peripheral thyroid hormone (TH) metabolism and/or concentrations of serum lipids is not clear. OBJECTIVE This study examined whether TSH has direct effects on peripheral TH metabolism and serum lipids. METHODS Eighty-two patients with differentiated thyroid cancer were retrospectively analyzed. All patients had undergone total thyroidectomy and 131I remnant ablation. During follow-up, two successive injections of recombinant human TSH (rhTSH) were administered to patients on a stable dose of levothyroxine. In all patients, TSH, thyroxine (T4), free T4 (fT4), triiodothyronine (T3), reverse T3 (rT3), total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, apolipoprotein B, lipoprotein(a), and triglyceride levels were measured immediately before the first and approximately 72 hours after the second injection of rhTSH. RESULTS After rhTSH stimulation, T3 values decreased (from 1.91 to 1.81 nmol/L; p < 0.001). T4, fT4, and rT3 did not change. After rhTSH, median apolipoprotein B increased from 0.90 to 0.92 g/L (p = 0.03), lipoprotein(a) from 0.21 to 0.24 g/L (p < 0.001), and triglycerides from 1.98 to 2.50 mmol/L (p < 0.001). Serum high-density lipoprotein cholesterol decreased from 0.98 to 0.81 mmol/L (p < 0.001). Multiple regression analysis showed that the changes in lipids were most closely associated with the decrease in T3 levels. CONCLUSIONS TSH has direct effects on peripheral TH metabolism by decreasing T3 levels in levothyroxine-treated thyroidectomized patients. This decrease in T3 levels is accompanied by unfavorable changes in serum lipids.
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Affiliation(s)
- Carolien M Beukhof
- 1 Department of Internal Medicine, Academic Center for Thyroid Diseases, University Medical Center , Rotterdam, The Netherlands
| | - Elske T Massolt
- 1 Department of Internal Medicine, Academic Center for Thyroid Diseases, University Medical Center , Rotterdam, The Netherlands
| | - Theo J Visser
- 1 Department of Internal Medicine, Academic Center for Thyroid Diseases, University Medical Center , Rotterdam, The Netherlands
| | - Tim I M Korevaar
- 1 Department of Internal Medicine, Academic Center for Thyroid Diseases, University Medical Center , Rotterdam, The Netherlands
| | - Marco Medici
- 1 Department of Internal Medicine, Academic Center for Thyroid Diseases, University Medical Center , Rotterdam, The Netherlands
| | - Wouter W de Herder
- 1 Department of Internal Medicine, Academic Center for Thyroid Diseases, University Medical Center , Rotterdam, The Netherlands
| | | | - Monique T Mulder
- 2 Department of Vascular Medicine, University Medical Center , Rotterdam, The Netherlands
| | - Yolanda B de Rijke
- 1 Department of Internal Medicine, Academic Center for Thyroid Diseases, University Medical Center , Rotterdam, The Netherlands
- 3 Department of Clinical Chemistry, Erasmus MC, University Medical Center , Rotterdam, The Netherlands
| | - Christoph Reiners
- 4 Department of Nuclear Medicine, University Hospital Wuerzburg , Wuerzburg, Germany
| | - Frederik A Verburg
- 4 Department of Nuclear Medicine, University Hospital Wuerzburg , Wuerzburg, Germany
- 5 Department of Nuclear Medicine, University Hospital Marburg , Marburg, Germany
| | - Robin P Peeters
- 1 Department of Internal Medicine, Academic Center for Thyroid Diseases, University Medical Center , Rotterdam, The Netherlands
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Ferretti G, Bacchetti T, Simental-Mendía LE, Reiner Ž, Banach M, Sahebkar A. Raloxifene Lowers Plasma Lipoprotein(a) Concentrations: a Systematic Review and Meta-analysis of Randomized Placebo-Controlled Trials. Cardiovasc Drugs Ther 2018; 31:197-208. [PMID: 28265881 DOI: 10.1007/s10557-017-6721-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
BACKGROUND AND AIMS Lipoprotein(a) (Lp(a)) is a proatherogenic plasma lipoprotein and an independent risk factor for atherosclerotic cardiovascular disease. We investigated the effects of raloxifene, selective estrogen receptor modulator, on circulating Lp(a) levels in postmenopausal women using a systematic review and meta-analysis of randomized controlled trials (RCTs). METHODS To identify relevant studies, electronic databases (PUBMED, Scopus, Web of Science, and Google Scholar) were searched by up to May 2015 to find controlled trials exploring the effects of oral raloxifene treatment on plasma Lp(a) levels in postmenopausal women. A random-effects model and generic inverse variance method were used for quantitative data synthesis. RESULTS Overall, seven eligible RCTs with ten treatment arms were included in this meta-analysis. Meta-analysis suggested a significant reduction of Lp(a) levels after treatment with raloxifene (standardized mean difference (SMD) -0.42; 95% CI -0.65, -0.19; p < 0.001), which may be considered as a medium effect size. When the studies were categorized according to the administered dose, there was a significant effect in both subsets of studies with administered doses ≤60 mg/day (SMD -0.43; 95% CI -0.73, -0.13; p = 0.004) and >60 mg/day (SMD -0.36; 95% CI -0.68, -0.05; p = 0.025). No significant association between the changes in plasma concentrations of Lp(a) with dose and baseline Lp(a) levels was found in the random-effects meta-regression analysis. However, a significant inverse association was observed between the Lp(a)-lowering effect of raloxifene and duration of treatment (p = 0.001). CONCLUSIONS Results of the present meta-analysis showed a reduction in plasma Lp(a) concentrations of postmenopausal women with oral raloxifene treatment.
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Affiliation(s)
- Gianna Ferretti
- Dipartimento di Scienze cliniche Specialistiche ed Odontostomatologiche, Università Politecnica delle Marche, Ancona, Italy
| | - Tiziana Bacchetti
- Dipartimento di Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Ancona, Italy
| | | | - Željko Reiner
- Department of Internal Medicine, University Hospital Center Zagreb, University of Zagreb School of Medicine, Kišpatićeva 12, Zagreb, Croatia
| | - Maciej Banach
- Department of Hypertension, WAM University Hospital in Lodz, Medical University of Lodz, Zeromskiego 113, Lodz, Poland
| | - Amirhossein Sahebkar
- Biotechnology Research Center, Mashhad University of Medical Sciences, Mashhad, Iran. .,Neurogenic Inflammation Research Center, Mashhad University of Medical Sciences, Mashhad, Iran. .,School of Medicine, University of Western Australia, Perth, Iran.
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20
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Kawashiri MA, Nohara A, Higashikata T, Tada H, Nakanishi C, Okada H, Konno T, Sakata K, Hayashi K, Inazu A, Mabuchi H, Yamagishi M. Impact of evolocumab treatment on low-density lipoprotein cholesterol levels in heterozygous familial hypercholesterolemic patients withdrawing from regular apheresis. Atherosclerosis 2017; 265:225-230. [DOI: 10.1016/j.atherosclerosis.2017.09.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 09/06/2017] [Accepted: 09/08/2017] [Indexed: 11/28/2022]
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21
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Thomas T, Zhou H, Karmally W, Ramakrishnan R, Holleran S, Liu Y, Jumes P, Wagner JA, Hubbard B, Previs SF, Roddy T, Johnson-Levonas AO, Gutstein DE, Marcovina SM, Rader DJ, Ginsberg HN, Millar JS, Reyes-Soffer G. CETP (Cholesteryl Ester Transfer Protein) Inhibition With Anacetrapib Decreases Production of Lipoprotein(a) in Mildly Hypercholesterolemic Subjects. Arterioscler Thromb Vasc Biol 2017; 37:1770-1775. [PMID: 28729361 PMCID: PMC5567403 DOI: 10.1161/atvbaha.117.309549] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 07/04/2017] [Indexed: 12/22/2022]
Abstract
OBJECTIVE Lp(a) [lipoprotein (a)] is composed of apoB (apolipoprotein B) and apo(a) [apolipoprotein (a)] and is an independent risk factor for cardiovascular disease and aortic stenosis. In clinical trials, anacetrapib, a CETP (cholesteryl ester transfer protein) inhibitor, causes significant reductions in plasma Lp(a) levels. We conducted an exploratory study to examine the mechanism for Lp(a) lowering by anacetrapib. APPROACH AND RESULTS We enrolled 39 participants in a fixed-sequence, double-blind study of the effects of anacetrapib on the metabolism of apoB and high-density lipoproteins. Twenty-nine patients were randomized to atorvastatin 20 mg/d, plus placebo for 4 weeks, and then atorvastatin plus anacetrapib (100 mg/d) for 8 weeks. The other 10 subjects were randomized to double placebo for 4 weeks followed by placebo plus anacetrapib for 8 weeks. We examined the mechanisms of Lp(a) lowering in a subset of 12 subjects having both Lp(a) levels >20 nmol/L and more than a 15% reduction in Lp(a) by the end of anacetrapib treatment. We performed stable isotope kinetic studies using 2H3-leucine at the end of each treatment to measure apo(a) fractional catabolic rate and production rate. Median baseline Lp(a) levels were 21.5 nmol/L (interquartile range, 9.9-108.1 nmol/L) in the complete cohort (39 subjects) and 52.9 nmol/L (interquartile range, 38.4-121.3 nmol/L) in the subset selected for kinetic studies. Anacetrapib treatment lowered Lp(a) by 34.1% (P≤0.001) and 39.6% in the complete and subset cohort, respectively. The decreases in Lp(a) levels were because of a 41% reduction in the apo(a) production rate, with no effects on apo(a) fractional catabolic rate. CONCLUSIONS Anacetrapib reduces Lp(a) levels by decreasing its production. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NCT00990808.
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Affiliation(s)
- Tiffany Thomas
- From the Columbia University, New York (T.T., W.K., R.R., S.H., H.N.G., G.R.-S.); Merck & Co, Inc, Kenilworth, NJ (H.Z., Y.L., P.J., J.A.W., B.H., S.F.P., T.R., A.O.J.-L., D.E.G.); University of Washington, Seattle (S.M.M.); and University of Pennsylvania, Philadelphia (D.J.R., J.S.M.)
| | - Haihong Zhou
- From the Columbia University, New York (T.T., W.K., R.R., S.H., H.N.G., G.R.-S.); Merck & Co, Inc, Kenilworth, NJ (H.Z., Y.L., P.J., J.A.W., B.H., S.F.P., T.R., A.O.J.-L., D.E.G.); University of Washington, Seattle (S.M.M.); and University of Pennsylvania, Philadelphia (D.J.R., J.S.M.)
| | - Wahida Karmally
- From the Columbia University, New York (T.T., W.K., R.R., S.H., H.N.G., G.R.-S.); Merck & Co, Inc, Kenilworth, NJ (H.Z., Y.L., P.J., J.A.W., B.H., S.F.P., T.R., A.O.J.-L., D.E.G.); University of Washington, Seattle (S.M.M.); and University of Pennsylvania, Philadelphia (D.J.R., J.S.M.)
| | - Rajasekhar Ramakrishnan
- From the Columbia University, New York (T.T., W.K., R.R., S.H., H.N.G., G.R.-S.); Merck & Co, Inc, Kenilworth, NJ (H.Z., Y.L., P.J., J.A.W., B.H., S.F.P., T.R., A.O.J.-L., D.E.G.); University of Washington, Seattle (S.M.M.); and University of Pennsylvania, Philadelphia (D.J.R., J.S.M.)
| | - Stephen Holleran
- From the Columbia University, New York (T.T., W.K., R.R., S.H., H.N.G., G.R.-S.); Merck & Co, Inc, Kenilworth, NJ (H.Z., Y.L., P.J., J.A.W., B.H., S.F.P., T.R., A.O.J.-L., D.E.G.); University of Washington, Seattle (S.M.M.); and University of Pennsylvania, Philadelphia (D.J.R., J.S.M.)
| | - Yang Liu
- From the Columbia University, New York (T.T., W.K., R.R., S.H., H.N.G., G.R.-S.); Merck & Co, Inc, Kenilworth, NJ (H.Z., Y.L., P.J., J.A.W., B.H., S.F.P., T.R., A.O.J.-L., D.E.G.); University of Washington, Seattle (S.M.M.); and University of Pennsylvania, Philadelphia (D.J.R., J.S.M.)
| | - Patricia Jumes
- From the Columbia University, New York (T.T., W.K., R.R., S.H., H.N.G., G.R.-S.); Merck & Co, Inc, Kenilworth, NJ (H.Z., Y.L., P.J., J.A.W., B.H., S.F.P., T.R., A.O.J.-L., D.E.G.); University of Washington, Seattle (S.M.M.); and University of Pennsylvania, Philadelphia (D.J.R., J.S.M.)
| | - John A Wagner
- From the Columbia University, New York (T.T., W.K., R.R., S.H., H.N.G., G.R.-S.); Merck & Co, Inc, Kenilworth, NJ (H.Z., Y.L., P.J., J.A.W., B.H., S.F.P., T.R., A.O.J.-L., D.E.G.); University of Washington, Seattle (S.M.M.); and University of Pennsylvania, Philadelphia (D.J.R., J.S.M.)
| | - Brian Hubbard
- From the Columbia University, New York (T.T., W.K., R.R., S.H., H.N.G., G.R.-S.); Merck & Co, Inc, Kenilworth, NJ (H.Z., Y.L., P.J., J.A.W., B.H., S.F.P., T.R., A.O.J.-L., D.E.G.); University of Washington, Seattle (S.M.M.); and University of Pennsylvania, Philadelphia (D.J.R., J.S.M.)
| | - Stephen F Previs
- From the Columbia University, New York (T.T., W.K., R.R., S.H., H.N.G., G.R.-S.); Merck & Co, Inc, Kenilworth, NJ (H.Z., Y.L., P.J., J.A.W., B.H., S.F.P., T.R., A.O.J.-L., D.E.G.); University of Washington, Seattle (S.M.M.); and University of Pennsylvania, Philadelphia (D.J.R., J.S.M.)
| | - Thomas Roddy
- From the Columbia University, New York (T.T., W.K., R.R., S.H., H.N.G., G.R.-S.); Merck & Co, Inc, Kenilworth, NJ (H.Z., Y.L., P.J., J.A.W., B.H., S.F.P., T.R., A.O.J.-L., D.E.G.); University of Washington, Seattle (S.M.M.); and University of Pennsylvania, Philadelphia (D.J.R., J.S.M.)
| | - Amy O Johnson-Levonas
- From the Columbia University, New York (T.T., W.K., R.R., S.H., H.N.G., G.R.-S.); Merck & Co, Inc, Kenilworth, NJ (H.Z., Y.L., P.J., J.A.W., B.H., S.F.P., T.R., A.O.J.-L., D.E.G.); University of Washington, Seattle (S.M.M.); and University of Pennsylvania, Philadelphia (D.J.R., J.S.M.)
| | - David E Gutstein
- From the Columbia University, New York (T.T., W.K., R.R., S.H., H.N.G., G.R.-S.); Merck & Co, Inc, Kenilworth, NJ (H.Z., Y.L., P.J., J.A.W., B.H., S.F.P., T.R., A.O.J.-L., D.E.G.); University of Washington, Seattle (S.M.M.); and University of Pennsylvania, Philadelphia (D.J.R., J.S.M.)
| | - Santica M Marcovina
- From the Columbia University, New York (T.T., W.K., R.R., S.H., H.N.G., G.R.-S.); Merck & Co, Inc, Kenilworth, NJ (H.Z., Y.L., P.J., J.A.W., B.H., S.F.P., T.R., A.O.J.-L., D.E.G.); University of Washington, Seattle (S.M.M.); and University of Pennsylvania, Philadelphia (D.J.R., J.S.M.)
| | - Daniel J Rader
- From the Columbia University, New York (T.T., W.K., R.R., S.H., H.N.G., G.R.-S.); Merck & Co, Inc, Kenilworth, NJ (H.Z., Y.L., P.J., J.A.W., B.H., S.F.P., T.R., A.O.J.-L., D.E.G.); University of Washington, Seattle (S.M.M.); and University of Pennsylvania, Philadelphia (D.J.R., J.S.M.)
| | - Henry N Ginsberg
- From the Columbia University, New York (T.T., W.K., R.R., S.H., H.N.G., G.R.-S.); Merck & Co, Inc, Kenilworth, NJ (H.Z., Y.L., P.J., J.A.W., B.H., S.F.P., T.R., A.O.J.-L., D.E.G.); University of Washington, Seattle (S.M.M.); and University of Pennsylvania, Philadelphia (D.J.R., J.S.M.)
| | - John S Millar
- From the Columbia University, New York (T.T., W.K., R.R., S.H., H.N.G., G.R.-S.); Merck & Co, Inc, Kenilworth, NJ (H.Z., Y.L., P.J., J.A.W., B.H., S.F.P., T.R., A.O.J.-L., D.E.G.); University of Washington, Seattle (S.M.M.); and University of Pennsylvania, Philadelphia (D.J.R., J.S.M.)
| | - Gissette Reyes-Soffer
- From the Columbia University, New York (T.T., W.K., R.R., S.H., H.N.G., G.R.-S.); Merck & Co, Inc, Kenilworth, NJ (H.Z., Y.L., P.J., J.A.W., B.H., S.F.P., T.R., A.O.J.-L., D.E.G.); University of Washington, Seattle (S.M.M.); and University of Pennsylvania, Philadelphia (D.J.R., J.S.M.).
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22
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Reyes-Soffer G, Ginsberg HN, Ramakrishnan R. The metabolism of lipoprotein (a): an ever-evolving story. J Lipid Res 2017; 58:1756-1764. [PMID: 28720561 DOI: 10.1194/jlr.r077693] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 07/18/2017] [Indexed: 02/06/2023] Open
Abstract
Lipoprotein (a) [Lp(a)] is characterized by apolipoprotein (a) [apo(a)] covalently bound to apolipoprotein B 100. It was described in human plasma by Berg et al. in 1963 and the gene encoding apo(a) (LPA) was cloned in 1987 by Lawn and colleagues. Epidemiologic and genetic studies demonstrate that increases in Lp(a) plasma levels increase the risk of atherosclerotic cardiovascular disease. Novel Lp(a) lowering treatments highlight the need to understand the regulation of plasma levels of this atherogenic lipoprotein. Despite years of research, significant uncertainty remains about the assembly, secretion, and clearance of Lp(a). Specifically, there is ongoing controversy about where apo(a) and apoB-100 bind to form Lp(a); which apoB-100 lipoproteins bind to apo(a) to create Lp(a); whether binding of apo(a) is reversible, allowing apo(a) to bind to more than one apoB-100 lipoprotein during its lifespan in the circulation; and how Lp(a) or apo(a) leave the circulation. In this review, we highlight past and recent data from stable isotope studies of Lp(a) metabolism, highlighting the critical metabolic uncertainties that exist. We present kinetic models to describe results of published studies using stable isotopes and suggest what future studies are required to improve our understanding of Lp(a) metabolism.
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Affiliation(s)
- Gissette Reyes-Soffer
- Departments of Medicine Columbia University College of Physicians and Surgeons, New York, NY 10032
| | - Henry N Ginsberg
- Departments of Medicine Columbia University College of Physicians and Surgeons, New York, NY 10032
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23
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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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24
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The complexity of lipoprotein (a) lowering by PCSK9 monoclonal antibodies. Clin Sci (Lond) 2017; 131:261-268. [DOI: 10.1042/cs20160403] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 11/15/2016] [Accepted: 11/16/2016] [Indexed: 01/04/2023]
Abstract
Since 2012, clinical trials dedicated to proprotein convertase subtilisin kexin type 9 (PCSK9) inhibition with monoclonal antibodies (mAbs) have unambiguously demonstrated robust reductions not only in low-density lipoprotein (LDL) cholesterol (LDL-C) but also in lipoprotein (a) [Lp(a)] levels. The scientific literature published prior to those studies did not provide any evidence for a link between PCSK9 and Lp(a) metabolism. More recent investigations, either in vitro or in vivo, have attempted to unravel the mechanism(s) by which PCSK9 mAbs reduce circulating Lp(a) levels, with some showing a specific implication of the LDL receptor (LDLR) in Lp(a) clearance whereas others found no significant role for the LDLR in that process. This elusive pathway appears clearly distinct from that of the widely prescribed statins that also enhance LDLR function but do not lower circulating Lp (a) levels in humans. So how does PCSK9 inhibition with mAbs reduce Lp(a)? This still remains to be established.
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25
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Diffenderfer MR, Lamon-Fava S, Marcovina SM, Barrett PHR, Lel J, Dolnikowski GG, Berglund L, Schaefer EJ. Distinct metabolism of apolipoproteins (a) and B-100 within plasma lipoprotein(a). Metabolism 2016; 65:381-90. [PMID: 26975530 PMCID: PMC4795479 DOI: 10.1016/j.metabol.2015.10.031] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 10/28/2015] [Accepted: 10/31/2015] [Indexed: 11/30/2022]
Abstract
OBJECTIVES Lipoprotein(a) [Lp(a)] is mainly similar in composition to LDL, but differs in having apolipoprotein (apo) (a) covalently linked to apoB-100. Our purpose was to examine the individual metabolism of apo(a) and apoB-100 within plasma Lp(a). MATERIALS AND METHODS The kinetics of apo(a) and apoB-100 in plasma Lp(a) were assessed in four men with dyslipidemia [Lp(a) concentration: 8.9-124.7nmol/L]. All subjects received a primed constant infusion of [5,5,5-(2)H3] L-leucine while in the constantly fed state. Lp(a) was immunoprecipitated directly from whole plasma; apo(a) and apoB-100 were separated by gel electrophoresis; and isotopic enrichment was determined by gas chromatography/mass spectrometry. RESULTS Multicompartmental modeling analysis indicated that the median fractional catabolic rates of apo(a) and apoB-100 within Lp(a) were significantly different at 0.104 and 0.263 pools/day, respectively (P=0.04). The median Lp(a) apo(a) production rate at 0.248nmol/kg·day(-1) was significantly lower than that of Lp(a) apoB-100 at 0.514nmol/kg·day(-1) (P=0.03). CONCLUSION Our data indicate that apo(a) has a plasma residence time (11days) that is more than twice as long as that of apoB-100 (4days) within Lp(a), supporting the concept that apo(a) and apoB-100 within plasma Lp(a) are not catabolized from the bloodstream as a unit in humans in the fed state.
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Affiliation(s)
- Margaret R Diffenderfer
- Cardiovascular Nutrition Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, 711 Washington Street, Boston, MA 02111, USA.
| | - Stefania Lamon-Fava
- Cardiovascular Nutrition Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, 711 Washington Street, Boston, MA 02111, USA.
| | - Santica M Marcovina
- Northwest Lipid Metabolism and Diabetes Research Laboratories, University of Washington, 401 Queen Anne Avenue North, Seattle, WA 98109, USA.
| | - P Hugh R Barrett
- School of Medicine and Pharmacology and Faculty of Engineering, Computing and Mathematics, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
| | - Julian Lel
- Cardiovascular Nutrition Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, 711 Washington Street, Boston, MA 02111, USA.
| | - Gregory G Dolnikowski
- Mass Spectrometry Unit, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, 711 Washington Street, Boston, MA 02111, USA.
| | - Lars Berglund
- Clinical and Translational Science Center, University of California, Davis, 2921 Stockton Boulevard, Suite 1400, Sacramento, CA 95817, USA.
| | - Ernst J Schaefer
- Cardiovascular Nutrition Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, 711 Washington Street, Boston, MA 02111, USA.
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26
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Damluji AA, El-Maouche D, Alsulaimi A, Martin P, Shamburek RD, Goldberg RB, Baum SJ, de Marchena EJ. Accelerated atherosclerosis and elevated lipoprotein (a) after liver transplantation. J Clin Lipidol 2015; 10:434-7. [PMID: 27055975 DOI: 10.1016/j.jacl.2015.12.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2015] [Revised: 11/29/2015] [Accepted: 12/17/2015] [Indexed: 11/29/2022]
Abstract
Cumulative evidence suggests that lipoprotein(a) [Lp(a)] exerts an independent effect on the initiation and progression of atherosclerotic cardiovascular disease. The genetically mediated expression of apolipoprotein(a), which is the key structural and functional component of Lp(a), occurs in hepatocytes with subsequent extracellular Lp(a) assembly at the hepatic cell surface. Here, we describe a case of elevated Lp(a) concentrations identified after (and likely acquired by) orthotopic liver transplantation that contributed to accelerated atherosclerotic cardiovascular disease despite intensive therapeutic interventions. This case study represents an important example to include Lp(a) screening in routine lipid panel testing for all liver transplant donors and recipients; to reduce unanticipated and debilitating cardiovascular morbidity and mortality.
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Affiliation(s)
- Abdulla A Damluji
- Cardiovascular Division and Elaine and Sydney Sussman Cardiac Catheterization Laboratories, University of Miami, Miller School of Medicine, Miami, FL, USA
| | - Diala El-Maouche
- Division of Endocrinology, Diabetes, and Metabolism, University of Miami, Miller School of Medicine, Miami, FL, USA; National Institutes of Health, Bethesda, MD, USA
| | - Ali Alsulaimi
- Cardiovascular Division and Elaine and Sydney Sussman Cardiac Catheterization Laboratories, University of Miami, Miller School of Medicine, Miami, FL, USA
| | - Paul Martin
- Division of Hepatology, University of Miami, Miller School of Medicine, Miami, FL, USA
| | | | - Ronald B Goldberg
- Division of Endocrinology, Diabetes, and Metabolism, University of Miami, Miller School of Medicine, Miami, FL, USA
| | - Seth J Baum
- Cardiovascular Division and Elaine and Sydney Sussman Cardiac Catheterization Laboratories, University of Miami, Miller School of Medicine, Miami, FL, USA
| | - Eduardo J de Marchena
- Cardiovascular Division and Elaine and Sydney Sussman Cardiac Catheterization Laboratories, University of Miami, Miller School of Medicine, Miami, FL, USA.
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27
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28
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Noureen A, Fresser F, Utermann G, Schmidt K. Sequence variation within the KIV-2 copy number polymorphism of the human LPA gene in African, Asian, and European populations. PLoS One 2015; 10:e0121582. [PMID: 25822457 PMCID: PMC4378929 DOI: 10.1371/journal.pone.0121582] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 02/13/2015] [Indexed: 11/18/2022] Open
Abstract
Amazingly little sequence variation is reported for the kringle IV 2 copy number variation (KIV 2 CNV) in the human LPA gene. Apart from whole genome sequencing projects, this region has only been analyzed in some detail in samples of European populations. We have performed a systematic resequencing study of the exonic and flanking intron regions within the KIV 2 CNV in 90 alleles from Asian, European, and four different African populations. Alleles have been separated according to their CNV length by pulsed field gel electrophoresis prior to unbiased specific PCR amplification of the target regions. These amplicons covered all KIV 2 copies of an individual allele simultaneously. In addition, cloned amplicons from genomic DNA of an African individual were sequenced. Our data suggest that sequence variation in this genomic region may be higher than previously appreciated. Detection probability of variants appeared to depend on the KIV 2 copy number of the analyzed DNA and on the proportion of copies carrying the variant. Asians had a high frequency of so-called KIV 2 type B and type C (together 70% of alleles), which differ by three or two synonymous substitutions respectively from the reference type A. This is most likely explained by the strong bottleneck suggested to have occurred when modern humans migrated to East Asia. A higher frequency of variable sites was detected in the Africans. In particular, two previously unreported splice site variants were found. One was associated with non-detectable Lp(a). The other was observed at high population frequencies (10% to 40%). Like the KIV 2 type B and C variants, this latter variant was also found in a high proportion of KIV 2 repeats in the affected alleles and in alleles differing in copy numbers. Our findings may have implications for the interpretation of SNP analyses in other repetitive loci of the human genome.
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Affiliation(s)
- Asma Noureen
- Division of Genetic Epidemiology, Department of Medical Genetics, Molecular and Clinical Pharmacology, Innsbruck Medical University, Innsbruck, Austria
- Division of Human Genetics, Department of Medical Genetics, Molecular and Clinical Pharmacology, Innsbruck Medical University, Innsbruck, Austria
| | - Friedrich Fresser
- Division of Human Genetics, Department of Medical Genetics, Molecular and Clinical Pharmacology, Innsbruck Medical University, Innsbruck, Austria
- Division of Translational Cell Genetics, Department of Medical Genetics, Molecular and Clinical Pharmacology, Innsbruck Medical University, Innsbruck, Austria
| | - Gerd Utermann
- Division of Human Genetics, Department of Medical Genetics, Molecular and Clinical Pharmacology, Innsbruck Medical University, Innsbruck, Austria
| | - Konrad Schmidt
- Division of Genetic Epidemiology, Department of Medical Genetics, Molecular and Clinical Pharmacology, Innsbruck Medical University, Innsbruck, Austria
- Division of Human Genetics, Department of Medical Genetics, Molecular and Clinical Pharmacology, Innsbruck Medical University, Innsbruck, Austria
- Centre de Recherches Médicales de Lambaréné, Albert Schweitzer Hospital, Lambaréné, Gabon
- Department for Tropical Medicine, Eberhard-Karls-University Tübingen, Tübingen, Germany
- * E-mail:
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29
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He Z, Peng Y, Duan W, Tian Y, Zhang J, Hu T, Cai Y, Feng Y, Li G. Aspirin regulates hepatocellular lipid metabolism by activating AMPK signaling pathway. J Toxicol Sci 2015; 40:127-36. [PMID: 25743752 DOI: 10.2131/jts.40.127] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Zhenxing He
- Department of Hepatopancreatobiliary Surgery, Nanchong Central Hospital, China
| | - Yong Peng
- Department of Hepatopancreatobiliary Surgery, Nanchong Central Hospital, China
| | - Wentao Duan
- Department of Hepatopancreatobiliary Surgery, Nanchong Central Hospital, China
| | - Yunhong Tian
- Department of Hepatopancreatobiliary Surgery, Nanchong Central Hospital, China
| | - Jian Zhang
- Department of Hepatopancreatobiliary Surgery, Nanchong Central Hospital, China
| | - Tao Hu
- Department of Hepatopancreatobiliary Surgery, Nanchong Central Hospital, China
| | - Yu Cai
- Department of Hepatopancreatobiliary Surgery, Nanchong Central Hospital, China
| | - Yuan Feng
- Department of Hepatopancreatobiliary Surgery, Nanchong Central Hospital, China
| | - Guangming Li
- Department of Oncology, Nanchong Central Hospital, China
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30
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Haring B, Wyler von Ballmoos MC, Appel LJ, Sacks FM. Healthy dietary interventions and lipoprotein (a) plasma levels: results from the Omni Heart Trial. PLoS One 2014; 9:e114859. [PMID: 25506933 PMCID: PMC4266632 DOI: 10.1371/journal.pone.0114859] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 10/21/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Increased lipoprotein(a) [Lp(a)] levels are associated with atherosclerotic cardiovascular disease. Studies of dietary interventions on changes in Lp(a) are sparse. We aimed to compare the effects of three healthy dietary interventions differing in macronutrient content on Lp(a) concentration. METHODS Secondary analysis of a randomized, 3-period crossover feeding study including 155 (89 blacks; 66 whites) individuals. Participants were given DASH-type healthy diets rich in carbohydrates [Carb], in protein [Prot] or in unsaturated fat [Unsat Fat] for 6 weeks each. Plasma Lp(a) concentration was assessed at baseline and after each diet. RESULTS Compared to baseline, all interventional diets increased mean Lp(a) by 2 to 5 mg/dl. Unsat Fat increased Lp(a) less than Prot with a difference of 1.0 mg/dl (95% CI, -0.5, 2.5; p = 0.196) in whites and 3.7 mg/dl (95% CI, 2.4, 5.0; p < 0.001) in blacks (p-value between races = 0.008); Unsat Fat increased Lp(a) less than Carb with a difference of -0.6 mg/dl, 95% CI, -2.1, 0.9; p = 0.441) in whites and -1.5 mg/dl (95% CI, -0.2, -2.8; p = 0.021) in blacks (p-value between races = 0.354). Prot increased Lp(a) more than Carb with a difference of 0.4 mg/dl (95% CI, -1.1, 1.9; p = 0.597) in whites and 2.2 mg/dl (95%CI, 0.9, 3.5; p = 0.001) in blacks (p-value between races = 0.082). CONCLUSION Diets high in unsaturated fat increased Lp(a) levels less than diets rich in carbohydrate or protein with greater changes in blacks than whites. Our results suggest that substitutions with dietary mono- and polyunsaturated fatty acids in healthy diets may be preferable over protein or carbohydrates with regards to Lp(a). TRIAL REGISTRATION Clinicaltrials.gov NCT00051350.
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Affiliation(s)
- Bernhard Haring
- Department of Internal Medicine I, Comprehensive Heart Failure Ctr, University of Würzburg, Bavaria, Germany
| | - Moritz C. Wyler von Ballmoos
- Department of Cardiothoracic Surgery, Froedtert Memorial Hospital & Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Lawrence J. Appel
- Welch Center for Prevention, Epidemiology, and Clinical Research, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Frank M. Sacks
- Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts, United States of America
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Zhou H, Castro-Perez J, Lassman ME, Thomas T, Li W, McLaughlin T, Dan X, Jumes P, Wagner JA, Gutstein DE, Hubbard BK, Rader DJ, Millar JS, Ginsberg HN, Reyes-Soffer G, Cleary M, Previs SF, Roddy TP. Measurement of apo(a) kinetics in human subjects using a microfluidic device with tandem mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2013; 27:1294-302. [PMID: 23681806 PMCID: PMC4944116 DOI: 10.1002/rcm.6572] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 02/20/2013] [Accepted: 03/14/2013] [Indexed: 05/15/2023]
Abstract
RATIONALE Apolipoprotein(a) [apo(a)] is the defining protein component of lipoprotein(a) [Lp(a)], an independent risk factor for cardiovascular disease. The regulation of Lp(a) levels in blood is poorly understood in part due to technical challenges in measuring Lp(a) kinetics. Improvements in the ability to readily and reliably measure the kinetics of apo(a) using a stable isotope labeled tracer is expected to facilitate studies of the role of Lp(a) in cardiovascular disease. Since investigators typically determine the isotopic labeling of protein-bound amino acids following acid-catalyzed hydrolysis of a protein of interest [e.g., apo(a)], studies of protein synthesis require extensive protein purification which limits throughput and often requires large sample volumes. We aimed to develop a rapid and efficient method for studying apo(a) kinetics that is suitable for use in studies involving human subjects. METHODS Microfluidic device and tandem mass spectrometry were used to quantify the incorporation of [(2)H3]-leucine tracer into protein-derived peptides. RESULTS We demonstrated that it is feasible to quantify the incorporation of [(2)H3]-leucine tracer into a proteolytic peptide from the non-kringle repeat region of apo(a) in human subjects. Specific attention was directed toward optimizing the multiple reaction monitoring (MRM) transitions, mass spectrometer settings, and chromatography (i.e., critical parameters that affect the sensitivity and reproducibility of isotopic enrichment measurements). The results demonstrated significant advantages with the use of a microfluidic device technology for studying apo(a) kinetics, including enhanced sensitivity relative to conventional micro-flow chromatography, a virtually drift-free elution profile, and a stable and robust electrospray. CONCLUSIONS The technological advances described herein enabled the implementation of a novel method for studying the kinetics of apo(a) in human subjects infused with [(2)H3]-leucine.
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Affiliation(s)
- Haihong Zhou
- Molecular Biomarkers-PPDM, Merck Sharp & Dohme Corp., Whitehouse Station, NJ, USA
| | - Jose Castro-Perez
- Molecular Biomarkers-PPDM, Merck Sharp & Dohme Corp., Whitehouse Station, NJ, USA
| | - Michael E. Lassman
- Clinical Development Laboratory, Merck Sharp & Dohme Corp., Whitehouse Station, NJ, USA
| | | | - Wenyu Li
- Molecular Biomarkers-PPDM, Merck Sharp & Dohme Corp., Whitehouse Station, NJ, USA
| | - Theresa McLaughlin
- Molecular Biomarkers-PPDM, Merck Sharp & Dohme Corp., Whitehouse Station, NJ, USA
| | - Xie Dan
- Molecular Biomarkers-PPDM, Merck Sharp & Dohme Corp., Whitehouse Station, NJ, USA
| | - Patricia Jumes
- Clinical Pharmacology, Merck Sharp & Dohme Corp., Whitehouse Station, NJ, USA
| | - John A. Wagner
- Clinical Pharmacology, Merck Sharp & Dohme Corp., Whitehouse Station, NJ, USA
| | - David E. Gutstein
- Clinical Pharmacology, Merck Sharp & Dohme Corp., Whitehouse Station, NJ, USA
| | - Brian K. Hubbard
- Molecular Biomarkers-PPDM, Merck Sharp & Dohme Corp., Whitehouse Station, NJ, USA
| | - Daniel J. Rader
- Division of Translational Medicine and Human Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - John S. Millar
- Division of Translational Medicine and Human Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | | | | | - Michele Cleary
- Molecular Biomarkers-PPDM, Merck Sharp & Dohme Corp., Whitehouse Station, NJ, USA
| | - Stephen F. Previs
- Molecular Biomarkers-PPDM, Merck Sharp & Dohme Corp., Whitehouse Station, NJ, USA
- Correspondence to: S. F. Previs, Molecular Biomarkers, Merck Sharp & Dohme Corp., 2015 Galloping Hill Road, Kenilworth, NJ 07033, USA.
| | - Thomas P. Roddy
- Molecular Biomarkers-PPDM, Merck Sharp & Dohme Corp., Whitehouse Station, NJ, USA
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32
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Enkhmaa B, Anuurad E, Zhang W, Abbuthalha A, Li XD, Dotterweich W, Pollard RB, Asmuth DM, Berglund L. HIV disease activity as a modulator of lipoprotein(a) and allele-specific apolipoprotein(a) levels. Arterioscler Thromb Vasc Biol 2012. [PMID: 23202367 DOI: 10.1161/atvbaha.112.300125] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
OBJECTIVE Mechanisms underlying the cardiovascular risk of lipoprotein(a) are poorly understood. We investigated the relationship of apolipoprotein(a) (apo(a)) size, lipoprotein(a), and allele-specific apo(a) levels with HIV disease activity parameters in a biethnic population. METHODS AND RESULTS Lipoprotein(a) and allele-specific apo(a) levels were determined in 139 white and 168 black HIV-positive patients. Plasma HIV RNA viral load and CD4+ T-cell count were used as surrogates for disease activity. Lipoprotein(a) and allele-specific apo(a) levels were higher in blacks than whites (for both P<0.001). Apo(a) allele size distribution was similar between the 2 ethnic groups, with a median apo(a) size of 28 kringle 4 repeats. Allele-specific apo(a) levels were positively associated with CD4+ T-cell count (P=0.027) and negatively with plasma HIV RNA viral load (P<0.001). Further, allele-specific apo(a) levels associated with smaller (<28 kringle 4) atherogenic apo(a) sizes were higher in subjects with CD4+ T-cell counts of ≥350 (P=0.002). CONCLUSIONS Allele-specific apo(a) levels were higher in subjects with high CD4+ T-cell count or low plasma HIV RNA viral load. The findings suggest that HIV disease activity reduced allele-specific apo(a) levels. Higher allele-specific apo(a) levels associated with atherogenic small apo(a) sizes might contribute to increased cardiovascular risk in HIV-positive subjects with improved disease status.
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Affiliation(s)
- Byambaa Enkhmaa
- Department of Internal Medicine, University of California, Davis, CA, USA
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33
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Chennamsetty I, Kostner KM, Claudel T, Vinod M, Frank S, Weiss TS, Trauner M, Kostner GM. Nicotinic acid inhibits hepatic APOA gene expression: studies in humans and in transgenic mice. J Lipid Res 2012; 53:2405-12. [PMID: 22930813 DOI: 10.1194/jlr.m029769] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Elevated plasma lipoprotein(a) (LPA) levels are recognized as an independent risk factor for cardiovascular diseases. Our knowledge on LPA metabolism is incomplete, which makes it difficult to develop LPA-lowering medications. Nicotinic acid (NA) is the main drug recommended for the treatment of patients with increased plasma LPA concentrations. The mechanism of NA in lowering LPA is virtually unknown. To study this mechanism, we treated transgenic (tg) APOA mice with NA and measured plasma APOA and hepatic mRNA levels. In addition, mouse and human primary hepatocytes were incubated with NA, and the expression of APOA was followed. Feeding 1% NA reduced plasma APOA and hepatic expression of APOA in tg-APOA mice. Experiments with cultured human and mouse primary hepatocytes in addition to reporter assays performed in HepG2 cells revealed that NA suppresses APOA transcription. The region between -1446 and -857 of the human APOA promoter harboring several cAMP response element binding sites conferred the negative effect of NA. In accordance, cAMP stimulated APOA transcription, and NA reduced hepatic cAMP levels. It is suggested that cAMP signaling might be involved in reducing APOA transcription, which leads to the lowering of plasma LPA.
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Suk Danik J, Rifai N, Buring JE, Ridker PM. Lipoprotein(a), hormone replacement therapy, and risk of future cardiovascular events. J Am Coll Cardiol 2008; 52:124-31. [PMID: 18598891 DOI: 10.1016/j.jacc.2008.04.009] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2007] [Revised: 03/02/2008] [Accepted: 04/02/2008] [Indexed: 02/07/2023]
Abstract
OBJECTIVES This study assesses whether the relationship of lipoprotein(a) [Lp(a)] with cardiovascular risk may be modified by concurrent hormone replacement therapy (HT). BACKGROUND Prior studies indicate that HT decreases plasma levels of Lp(a), but few have been powered to assess whether it modifies the relationship of Lp(a) with cardiovascular disease (CVD). METHODS Lipoprotein(a) at baseline was measured among 27,736 initially healthy women, of whom 12,075 indicated active HT use at the time of blood draw at study initiation and 15,661 did not. The risk of first-ever major cardiovascular event (nonfatal myocardial infarction, nonfatal cerebrovascular event, coronary revascularization, or cardiovascular death) over a 10-year period was assessed with Cox proportional hazard models according to Lp(a) levels and HT status and adjusted for potential confounding variables. RESULTS As anticipated, Lp(a) values were lower among women taking HT (median 9.4 mg/dl vs. 11.6 mg/dl, p < 0.0001). In women not taking HT, the hazard ratio of future CVD for the highest Lp(a) quintile compared with the lowest was 1.8 (p trend <0.0001), after adjusting for age, smoking, blood pressure, diabetes, body mass index, total cholesterol, high-density lipoprotein, C-reactive protein, and treatment arms of aspirin and vitamin E. In contrast, among women taking HT, there was little evidence of association with CVD (hazard ratio: 1.1, p trend = 0.18; interaction p value = 0.0009 between Lp(a) quintiles and HT on incident CVD). CONCLUSIONS The relationship of high Lp(a) levels with increased CVD is modified by HT. These data suggest that the predictive utility of Lp(a) is markedly attenuated among women taking HT and may inform clinicians' interpretation of Lp(a) values in such patients. (Women's Health Study [WHS]; NCT00000479).
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Affiliation(s)
- Jacqueline Suk Danik
- Donald W Reynolds Center for Cardiovascular Research, Brigham and Women's Hospital, Boston, Massachusetts 02215, USA.
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37
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Krause BR, Sliskovic DR, Ma Bocan T. Section Review—Cardiovascular & Renal: Emerging Therapies in Atherosclerosis. Expert Opin Investig Drugs 2008. [DOI: 10.1517/13543784.4.5.353] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Rosas S, Joffe M, Wolfe M, Brayman K, Rader DJ. Effects of renal replacement therapy on plasma lipoprotein(a) levels. Am J Nephrol 2008; 28:361-5. [PMID: 18057868 PMCID: PMC2786011 DOI: 10.1159/000112225] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2007] [Accepted: 10/15/2007] [Indexed: 02/05/2023]
Abstract
Patients with end-stage renal disease (ESRD) have significantly higher levels of lipoprotein(a) [Lp(a)] when compared to control populations. Elevated levels of Lp(a) may play a role in the high incidence of cardiovascular disease in ESRD. We conducted a prospective study to test the hypothesis that plasma levels of Lp(a) decline rapidly after renal transplantation proportional to the improvement in renal function, but are not affected by hemodialysis. All adults that initiated hemodialysis or received a renal transplant from our institution during a 10-month period were invited to participate in the study. Lp(a) levels were obtained immediately prior to the initiation of renal replacement therapy. In transplant recipients, repeat Lp(a) measures were done at 3 days, 5 days, 1 week, 2 weeks, 3 weeks and 4 weeks post-transplant. In hemodialysis patients, repeat Lp(a) measures were done after 3 months. We used a mixed effects model to analyze the effect of time, race and creatinine on Lp(a) after transplant. Lp(a) levels decreased rapidly after renal transplantation. Mean Lp(a) levels at 2 weeks were 35.3% lower than prior to transplantation. Each reduction of 50% in creatinine was associated with a 10.6% reduction in Lp(a) (p < 0.001). In contrast, there was no significant change in Lp(a) after initiation of hemodialysis. The rapid decrease of Lp(a) levels after renal transplantation provides support for a metabolic role of the kidney in Lp(a) catabolism and suggests that the increase in Lp(a) seen in chronic kidney disease is due to loss of functioning renal tissue.
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Affiliation(s)
- Sylvia Rosas
- Renal, Electrolyte and Hypertension Division, Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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39
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Anuurad E, Boffa MB, Koschinsky ML, Berglund L. Lipoprotein(a): A Unique Risk Factor for Cardiovascular Disease. Clin Lab Med 2006; 26:751-72. [PMID: 17110238 DOI: 10.1016/j.cll.2006.07.002] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Lipoprotein(a) (Lp(a)) is present in humans and primates. It has many properties in common with low-density lipoprotein, but contains a unique protein moiety designated apo(a), which is linked to apolipoprotein B-100 by a single disulfide bond. International standards for Lp(a) measurement and optimized Lp(a) assays insensitive to isoform size are not yet widely available. Lp(a) is a risk factor for coronary artery disease, and smaller size apo(a) is associated with coronary artery disease. The physiologic role of Lp(a) is unknown.
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Affiliation(s)
- Erdembileg Anuurad
- Department of Medicine, VA Northern California Health Care System, UCD Medical Center, University of California-Davis, 4150 V Street, Suite G400, Sacramento, CA 95817, USA
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Discepolo W, Wun T, Berglund L. Lipoprotein(a) and Thrombocytes: Potential Mechanisms Underlying Cardiovascular Risk. PATHOPHYSIOLOGY OF HAEMOSTASIS AND THROMBOSIS 2006; 35:314-21. [PMID: 16877880 DOI: 10.1159/000093224] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Plasma levels of lipoprotein(a), Lp(a), is an independent risk factor for cardiovascular disease. Lp(a) has many properties in common with low-density lipoprotein (LDL), including a cholesteryl ester-rich lipid core and the presence of one copy of apolipoprotein B-100; both apoB-100 and the lipid core are pro-atherogenic. In addition, Lp(a) contains a unique hydrophilic, carbohydrate-rich protein, apo(a), linked to apoB through a single disulfide bond connecting the C-terminal regions of the two proteins. The similarities between apolipoprotein(a), apo(a), and plasminogen has initiated numerous studies on the possible role of Lp(a) as a prothrombotic agent. Studies to date suggest that Lp(a) has antifibrinolytic and procoagulant properties. In this review, we summarize recent studies focused on the interaction between Lp(a) and platelets. Collectively, results to date illustrate that thrombogenicity associated with Lp(a) could be due to risk associated with the LDL moiety, with the apo(a) moiety, or from the combination of those in Lp(a). Present findings suggest that the various components of Lp(a) may impact to a varying degree on different underlying pathways involved in platelet activation and aggregation. On balance, results indicate an effect by Lp(a) on platelet function and future studies focused on specific Lp(a) components, such as the role of apo(a) and of the LDL-like lipid moiety, are needed.
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Abstract
Caffeine is the most widely consumed psychostimulant drug in the world that mostly is consumed in the form of coffee. Whether caffeine and/or coffee consumption contribute to the development of cardiovascular disease (CVD), the single leading cause of death in the US, is unclear.This article examines the effects of caffeine intake, both alone and via coffee consumption, on key blood markers of CVD risk: lipoproteins (cholesterol, triglycerides), fibrinogen (a biomarker of blood clotting) and C-reactive protein (CRP; a biomarker of inflammation). These blood markers and their role in the development of CVD are reviewed first. Studies examining caffeine and coffee effects on each of these blood markers are then presented. Next, biobehavioural moderators of the relationship between caffeine and/or coffee consumption and CVD are discussed, including genetics, sex and tobacco smoking. The literature indicates a strong relationship between boiled, unfiltered coffee consumption and elevated cholesterol levels; however, there is a critical gap in the literature regarding the effects of coffee or caffeine consumption on fibrinogen or CRP, which is an independent predictor of CVD risk. Available studies are limited by small samples sizes, inclusion of only men (or few women) and unrepresented age or ethnic groups. Thiere is a critical need for controlled laboratory and epidemiological studies that include fibrinogen and CRP markers of CVD risk before conclusions can be drawn regarding the health effects of caffeine and/or coffee in a normal, healthy population of men and women.
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Affiliation(s)
- Isabella M Rodrigues
- Department of Biobehavioral Health, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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42
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Cain WJ, Millar JS, Himebauch AS, Tietge UJF, Maugeais C, Usher D, Rader DJ. Lipoprotein [a] is cleared from the plasma primarily by the liver in a process mediated by apolipoprotein [a]. J Lipid Res 2005; 46:2681-91. [PMID: 16150825 DOI: 10.1194/jlr.m500249-jlr200] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The cellular and molecular mechanisms responsible for lipoprotein [a] (Lp[a]) catabolism are unknown. We examined the plasma clearance of Lp[a] and LDL in mice using lipoproteins isolated from human plasma coupled to radiolabeled tyramine cellobiose. Lipoproteins were injected into wild-type, LDL receptor-deficient (Ldlr-/-), and apolipoprotein E-deficient (Apoe-/-) mice. The fractional catabolic rate of LDL was greatly slowed in Ldlr-/- mice and greatly accelerated in Apoe-/- mice compared with wild-type mice. In contrast, the plasma clearance of Lp[a] in Ldlr-/- mice was similar to that in wild-type mice and was only slightly accelerated in Apoe-/- mice. Hepatic uptake of Lp[a] in wild-type mice was 34.6% of the injected dose over a 24 h period. The kidney accounted for only a small fraction of tissue uptake (1.3%). To test whether apolipoprotein [a] (apo[a]) mediates the clearance of Lp[a] from plasma, we coinjected excess apo[a] with labeled Lp[a]. Apo[a] acted as a potent inhibitor of Lp[a] plasma clearance. Asialofetuin, a ligand of the asialoglycoprotein receptor, did not inhibit Lp[a] clearance. In summary, the liver is the major organ accounting for the clearance of Lp[a] in mice, with the LDL receptor and apolipoprotein E having no major roles. Our studies indicate that apo[a] is the primary ligand that mediates Lp[a] uptake and plasma clearance.
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Affiliation(s)
- William J Cain
- Department of Biological Sciences, University of Delaware, Newark, DE, USA.
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Jenner JL, Seman LJ, Millar JS, Lamon-Fava S, Welty FK, Dolnikowski GG, Marcovina SM, Lichtenstein AH, Barrett PHR, deLuca C, Schaefer EJ. The metabolism of apolipoproteins (a) and B-100 within plasma lipoprotein (a) in human beings. Metabolism 2005; 54:361-9. [PMID: 15736114 DOI: 10.1016/j.metabol.2004.10.001] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The metabolism of apolipoproteins (apo) (a) and B-100 within plasma lipoprotein (a) [Lp(a)] was examined in the fed state in 23 subjects aged 41 to 79 years who received a primed-constant infusion of [5,5,5-2H3] leucine over 15 hours. Lipoprotein (a) was isolated from the whole plasma using a lectin affinity-based method. Apolipoprotein (a) and apoB-100 were separated by gel electrophoresis, and tracer enrichment of each apolipoprotein was measured using gas chromatography/mass spectrometry. Data were fit to a multicompartmental model to determine fractional catabolic rates (FCRs) and secretion rates (SRs). The FCRs of apo(a) and apoB-100 (mean +/- SEM) within plasma Lp(a) were significantly different (0.220 +/- 0.030 pool/d and 0.416 +/- 0.040 pool/d, respectively; P < .001). Apolipoprotein (a) SR (0.50 +/- 0.08 mg/[kg per d]) was significantly lower than that of apoB-100 SR (1.53 +/- 0.22 mg/[kg per d]; P < .001) of Lp(a). Plasma concentrations of Lp(a) were correlated significantly with both apo(a) SR and apoB-100 SR (r = 0.837 and r = 0.789, respectively; P < .001) and negatively with apo(a) FCR and Lp(a) apoB-100 FCR (r = -0.547 and r = -0.717, respectively; P < .01). These data implicate different metabolic fates for apo(a) and apoB-100 within Lp(a) in the fed state. We therefore hypothesize that apo(a) does not remain covalently linked to a single apoB-100 lipoprotein but that it rather reassociates at least once with another apoB-100 particle, probably newly synthesized, during its plasma metabolism.
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Affiliation(s)
- Jennifer L Jenner
- Lipid Metabolism Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111, USA
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Abstract
Lipoprotein (a) [Lp(a)], is present only in humans, Old World nonhuman primates, and the European hedgehog. Lp(a) has many properties in common with low-density lipoprotein (LDL) but contains a unique protein, apo(a), which is structurally different from other apolipoproteins. The size of the apo(a) gene is highly variable, resulting in the protein molecular weight ranging from 300 to 800 kDa; this large variation may be caused by neutral evolution in the absence of any selection advantage. Apo(a) influences to a major extent metabolic and physicochemical properties of Lp(a), and the size polymorphism of the apo(a) gene contributes to the pronounced heterogeneity of Lp(a). There is an inverse relationship between apo(a) size and Lp(a) levels; however, this pattern is complex. For a given apo(a) size, there is a considerable variation in Lp(a) levels across individuals, underscoring the importance to assess allele-specific Lp(a) levels. Further, Lp(a) levels differ between populations, and blacks have generally higher levels than Asians and whites, adjusting for apo(a) sizes. In addition to the apo(a) size polymorphism, an upstream pentanucleotide repeat (TTTTA(n)) affects Lp(a) levels. Several meta-analyses have provided support for an association between Lp(a) and coronary artery disease, and the levels of Lp(a) carried in particles with smaller size apo(a) isoforms are associated with cardiovascular disease or with preclinical vascular changes. Further, there is an interaction between Lp(a) and other risk factors for cardiovascular disease. The physiological role of Lp(a) is unknown, although a majority of studies implicate Lp(a) as a risk factor.
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Affiliation(s)
- Lars Berglund
- Department of Medicine, University of California, Davis, UCD Medical Center, 4150 V Street, Suite G400, Sacramento, CA 95817, USA.
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Kronenberg F. Epidemiology, pathophysiology and therapeutic implications of lipoprotein(a) in kidney disease. Expert Rev Cardiovasc Ther 2004; 2:729-43. [PMID: 15350174 DOI: 10.1586/14779072.2.5.729] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Chronic kidney disease is associated with a tremendously increased risk for cardiovascular disease. Traditional risk factors for cardiovascular disease, however, show a diminished predictive power in these patients compared with the general population. This review provides an overview of lipoprotein(a), which is considered a nontraditional risk factor. The characteristic genetic and nongenetic changes of lipoprotein(a) in kidney disease are discussed and set into the context of risk prediction. In particular, genetically determined apolipoprotein(a) polymorphism is a powerful risk predictor for cardiovascular disease and total mortality in these patients. Finally, the limited interventional strategies available to lower lipoprotein(a) are considered.
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Affiliation(s)
- Florian Kronenberg
- Department of Medical Biology and Human Genetics, Innsbruck Medical University, Schöpfstr. 41, A-6020 Innsbruck, Austria.
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Tholstrup T, Samman S. Postprandial lipoprotein(a) is affected differently by specific individual dietary fatty acids in healthy young men. J Nutr 2004; 134:2550-5. [PMID: 15465746 DOI: 10.1093/jn/134.10.2550] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Lipoprotein(a) [Lp(a)] is considered a risk factor for coronary heart disease. Our aim was to investigate the effect of individual fatty acids on postprandial plasma Lp(a) and its association with lipemia and tissue plasminogen activator (t-PA). Five test fats dominated by (approximately 43% g/kg) stearic (S), palmitic (P), oleic, C18:1 trans (T), or linoleic acid were produced by interesterification. Sixteen young healthy men were served the individual test fats incorporated into meals (1g fat/kg body wt) after a 12-h fast in random order on different days, separated by 3-wk washout periods. Blood samples were drawn before and 2, 4, 6, and 8 h after eating. There was a pronounced increase in Lp(a) concentrations after intake of the test meals, and the test fats resulted in a difference in Lp(a) response (P < 0.001; diet x time interaction). However, T fat did not change Lp(a) during the time course studied. T fat resulted in less area under the plasma Lp(a) concentration curve compared to S and P fat (P </= 0.003). Test fat with saturated fatty acids resulted in the highest Lp(a) and lowest plasma triacylglycerol (TAG) response, with the reversed situation for T fat. There was no association between Lp(a) and t-PA. In conclusion, intake of meals high in individual dietary fatty acids increased postprandial plasma Lp(a) differently. There seems to be a complex regulatory role of plasma TAG on nonfasting plasma Lp(a) concentrations.
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Affiliation(s)
- Tine Tholstrup
- Research Department of Human Nutrition and Center for Advanced Food Studies, The Royal Veterinary and Agricultural University, Frederiksberg, Denmark.
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Ghorbanihaghjo A, Argani H, Rohbaninoubar M, Rashtchizadeh N. Effect of Nandrolone Decanoate on serum lipoprotein (a) and its isoforms in hemodialysis patients. Lipids Health Dis 2004; 3:16. [PMID: 15225379 PMCID: PMC455686 DOI: 10.1186/1476-511x-3-16] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2004] [Accepted: 06/29/2004] [Indexed: 11/15/2022] Open
Abstract
Malnutrition, anemia and increased atherosclerosis are the main causes of mortality in hemodialysis patients. Therapies designed to improve the disorders might therefore be expected to improve outcome. The effects of Nandrolone Decanoate (ND), in 64 stable hemodialysis patients, were studied with respect to the following parameters: nutritional status, hematological indexes, lipid profiles including serum levels of lipoprotein(a) [Lp(a)] in terms of differences in apolipoprotein(a) [apo(a)]. The patients were treated with ND at dose of 100 mg/I.M./week for 4 months. After 2 and 4 months of treatment the elevations in the serum levels of albumin (p < 0.0001), creatinine (p < 0.009), hemoglobin (p < 0.03), hematocrit (p < 0.03), cholesterol (p = 0.007) and triglyceride (p < 0.04) were noticed. Marked decrease in the concentration of high-density lipoprotein cholesterol (p = 0.007) and Lp(a) (p < 0.0001) were also found. These effects after 2 months of treatment withdrawal were relatively constant. By dividing patients according to the baseline Lp(a) levels and molecular weight of apo(a) isoform, it was noticed that the decrease in serum Lp(a) was significant in patients with high Lp(a) (>30 mg/dl) than those of with low Lp(a) (<30 mg/dl), irrespective of apo(a) molecular weight. It may be suggested that, ND has beneficial effect on nutritional status and treatment of anemia in hemodialysis patients. In spite the adverse effect of ND on lipid profile, it decreases Lp(a) mostly in patients with high serum Lp(a) preferently by the effect on apo(a) gene transcriptional activity.
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Affiliation(s)
- Amir Ghorbanihaghjo
- Department of Biochemistry, Drug Applied Research Center, Tabriz University of medical sciences, Tabriz, Iran
| | - Hassan Argani
- Department of Biochemistry, Drug Applied Research Center, Tabriz University of medical sciences, Tabriz, Iran
- Hemodialysis and Nephrology Division of Emam Hospital, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mohammad Rohbaninoubar
- Department of Biochemistry, Drug Applied Research Center, Tabriz University of medical sciences, Tabriz, Iran
| | - Nadereh Rashtchizadeh
- Department of Biochemistry, Drug Applied Research Center, Tabriz University of medical sciences, Tabriz, Iran
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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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Nassir F, Xie Y, Davidson NO. Apolipoprotein[a] secretion from hepatoma cells is regulated in a size-dependent manner by alterations in disulfide bond formation. J Lipid Res 2003; 44:816-27. [PMID: 12562843 DOI: 10.1194/jlr.m200451-jlr200] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Apolipoprotein[a] (apo[a]) is a large disulfide linked glycoprotein synthesized by hepatocytes. We have examined the role of disulfide bond formation in the processing of apo[a] using human and rat hepatoma cells expressing apo[a] isoforms containing varying numbers of kringle 4 (K4) domains, following treatment with DTT. Hepatoma cells expressing 6- or 9-K4 isoforms revealed approximately 90% inhibition of apo[a] secretion following DTT treatment, although larger isoforms containing 13- or 17-K4 domains demonstrated continued secretion (up to 30% of control values), suggesting that a fraction of the larger isoforms is at least partially DTT resistant. Wash-out experiments demonstrated that these effects were completely reversible for all isoforms studied, with no enhanced degradation associated with prolonged intracellular retention. DTT treatment was associated with enhanced binding of apo[a] with the endoplasmic reticulum-associated chaperone proteins calnexin, calreticulin, and BiP, which was reversible upon DTT removal. The chemical chaperone 6-aminohexanoic acid, previously demonstrated by others to rescue defective apo[a] secretion associated with alterations in glycosylation, failed to alter the secretion of apo[a] following DTT treatment. The demonstration that DTT modulates apo[a] secretion in a manner influenced by both the type and number of K4 repeats extends understanding of the mechanisms that regulate its exit from the endoplasmic reticulum.
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Affiliation(s)
- Fatiha Nassir
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
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Noto D, Pace A, Cefalù AB, Barbagallo CM, Rizzo M, Marino G, Emmanuele G, Travali S, Notarbartolo A, Averna M. Differential apolipoprotein(a) isoform expression in heterozygosity is an independent contributor to lipoprotein(a) levels variability. Clin Chim Acta 2003; 328:91-7. [PMID: 12559603 DOI: 10.1016/s0009-8981(02)00390-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND AND METHODS Lipoprotein(a) [Lp(a)] levels represent an independent risk factor for cardio- and cerebrovascular diseases. Since lipoprotein(a) levels show a wide variability even in subjects with similar apolipoprotein(a) isoforms, we investigated the contribution of apolipoprotein(a) heterozygosity to lipoprotein(a) variance. Lipoprotein(a) levels, apolipoprotein(a) isoforms identification and expression, and the correlation with other lipo-apolipoprotein parameters have been investigated in 628 subjects >18 years of age. RESULTS In our study, 246 subjects were found heterozygous for apolipoprotein(a) isoforms. Lipoprotein(a) levels were higher in females. About 40% of the subjects expressed the larger isoform more intensely than the dominant isoform. Lipoprotein(a) was correlated with apolipoprotein(a) dominant isoform size, HDL-cholesterol and smaller apolipoprotein(a) isoform expression rate. Lipoprotein(a) was independently correlated with the smaller apolipoprotein(a) isoform, with its expression rate and with LDL-cholesterol. The inclusion of the smaller apolipoprotein(a) expression rate in a multiple regression model explained at least an additional 4% of the lipoprotein(a) variance after correction for apolipoprotein(a) size. CONCLUSIONS The smaller isoforms are not always effectively dominant in heterozygosis since 40% of the subjects expressed more the larger isoform. The individual variability of apolipoprotein(a) isoform expression in heterozygosis could explain part of the lipoprotein(a) levels variability.
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Affiliation(s)
- Davide Noto
- Department of Internal Medicine and Geriatrics, University of Palermo, Palermo, Italy
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