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Beyond Lipoprotein(a) plasma measurements: Lipoprotein(a) and inflammation. Pharmacol Res 2021; 169:105689. [PMID: 34033878 PMCID: PMC9247870 DOI: 10.1016/j.phrs.2021.105689] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 05/18/2021] [Accepted: 05/19/2021] [Indexed: 12/20/2022]
Abstract
Genome wide association, epidemiological, and clinical studies have established high lipoprotein(a) [Lp(a)] as a causal risk factor for atherosclerotic cardiovascular disease (ASCVD). Lp(a) is an apoB100 containing lipoprotein covalently bound to apolipoprotein(a) [apo(a)], a glycoprotein. Plasma Lp(a) levels are to a large extent determined by genetics. Its link to cardiovascular disease (CVD) may be driven by its pro-inflammatory effects, of which its association with oxidized phospholipids (oxPL) bound to Lp(a) is the most studied. Various inflammatory conditions, such as rheumatoid arthritis (RA), systemic lupus erythematosus, acquired immunodeficiency syndrome, and chronic renal failure are associated with high Lp(a) levels. In cases of RA, high Lp(a) levels are reversed by interleukin-6 receptor (IL-6R) blockade by tocilizumab, suggesting a potential role for IL-6 in regulating Lp(a) plasma levels. Elevated levels of IL-6 and IL-6R polymorphisms are associated with CVD. Therapies aimed at lowering apo(a) and thereby reducing plasma Lp(a) levels are in clinical trials. Their results will determine if reductions in apo(a) and Lp(a) decrease cardiovascular outcomes. As we enter this new arena of available treatments, there is a need to improve our understanding of mechanisms. This review will focus on the role of Lp(a) in inflammation and CVD.
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Müller N, Schulte DM, Türk K, Freitag-Wolf S, Hampe J, Zeuner R, Schröder JO, Gouni-Berthold I, Berthold HK, Krone W, Rose-John S, Schreiber S, Laudes M. IL-6 blockade by monoclonal antibodies inhibits apolipoprotein (a) expression and lipoprotein (a) synthesis in humans. J Lipid Res 2015; 56:1034-42. [PMID: 25713100 DOI: 10.1194/jlr.p052209] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Indexed: 11/20/2022] Open
Abstract
Lipoprotein (a) [Lp(a)] is a highly atherogenic lipid particle. Although earlier reports suggested that Lp(a) levels are mostly determined by genetic factors, several recent studies have revealed that Lp(a) induction is also caused by chronic inflammation. Therefore, we aimed to examine whether cytokine blockade by monoclonal antibodies may inhibit Lp(a) metabolism. We found that interleukin 6 (IL-6) blockade by tocilizumab (TCZ) reduced Lp(a) while TNF-α-inhibition by adalimumab in humans had no effect. The specificity of IL-6 in regulating Lp(a) was further demonstrated by serological measurements of human subjects (n = 1,153) revealing that Lp(a) levels are increased in individuals with elevated serum IL-6. Transcriptomic analysis of human liver biopsies (n = 57) revealed typical IL-6 response genes being correlated with the LPA gene expression in vivo. On a molecular level, we found that TCZ inhibited IL-6-induced LPA mRNA and protein expression in human hepatocytes. Furthermore, examination of IL-6-responsive signal transducer and activator of transcription 3 binding sites within the LPA promoter by reporter gene assays, promoter deletion experiments, and electrophoretic mobility shift assay analysis showed that the Lp(a)-lowering effect of TCZ is specifically mediated via a responsive element at -46 to -40. Therefore, IL-6 blockade might be a potential therapeutic option to treat elevated Lp(a) serum concentrations in humans and might be a noninvasive alternative to lipid apheresis in the future.
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Affiliation(s)
- Nike Müller
- Department I of Internal Medicine, University of Kiel, Kiel, Germany
| | - Dominik M Schulte
- Department I of Internal Medicine, University of Kiel, Kiel, Germany Cluster of Excellence Inflammation at Interfaces, University of Kiel, Kiel, Germany
| | - Kathrin Türk
- Department I of Internal Medicine, University of Kiel, Kiel, Germany
| | - Sandra Freitag-Wolf
- Institute of Medical Informatics and Statistics, University of Kiel, Kiel, Germany
| | - Jochen Hampe
- Department of Medicine I, University Hospital Carl Gustav Carus, University of Dresden, Dresden, Germany
| | - Rainald Zeuner
- Department I of Internal Medicine, University of Kiel, Kiel, Germany
| | - Johann O Schröder
- Department I of Internal Medicine, University of Kiel, Kiel, Germany Cluster of Excellence Inflammation at Interfaces, University of Kiel, Kiel, Germany
| | - Ioanna Gouni-Berthold
- Center for Endocrinology, Diabetes and Preventive Medicine, University of Cologne, Cologne, Germany
| | - Heiner K Berthold
- Department of Internal Medicine and Geriatrics, Bielefeld Evangelical Hospital, Bielefeld, Germany
| | - Wilhelm Krone
- Center for Endocrinology, Diabetes and Preventive Medicine, University of Cologne, Cologne, Germany
| | - Stefan Rose-John
- Cluster of Excellence Inflammation at Interfaces, University of Kiel, Kiel, Germany Institute of Biochemistry, University of Kiel, Kiel, Germany
| | - Stefan Schreiber
- Department I of Internal Medicine, University of Kiel, Kiel, Germany Cluster of Excellence Inflammation at Interfaces, University of Kiel, Kiel, Germany
| | - Matthias Laudes
- Department I of Internal Medicine, University of Kiel, Kiel, Germany Cluster of Excellence Inflammation at Interfaces, University of Kiel, Kiel, Germany
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Mooser V, Berger MM, Tappy L, Cayeux C, Marcovina SM, Darioli R, Nicod P, Chioléro R. Major reduction in plasma Lp(a) levels during sepsis and burns. Arterioscler Thromb Vasc Biol 2000; 20:1137-42. [PMID: 10764684 DOI: 10.1161/01.atv.20.4.1137] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Plasma levels of lipoprotein(a) [Lp(a)], an atherogenic particle, vary widely between individuals and are highly genetically determined. Whether Lp(a) is a positive acute-phase reactant is debated. The present study was designed to evaluate the impact of major inflammatory responses on plasma Lp(a) levels. Plasma levels of C-reactive protein (CRP), low density lipoprotein cholesterol, Lp(a), and apolipoprotein(a) [apo(a)] fragments, as well as urinary apo(a), were measured serially in 9 patients admitted to the intensive care unit for sepsis and 4 patients with extensive burns. Sepsis and burns elicited a major increase in plasma CRP levels. In both conditions, plasma concentrations of Lp(a) declined abruptly and transiently in parallel with plasma low density lipoprotein cholesterol levels and closely mirrored plasma CRP levels. In 5 survivors, the nadir of plasma Lp(a) levels was 5- to 15-fold lower than levels 16 to 18 months after the study period. No change in plasma levels of apo(a) fragments or urinary apo(a) was noticed during the study period. Turnover studies in mice indicated that clearance of Lp(a) was retarded in lipopolysaccharide-treated animals. Taken together, these data demonstrate that Lp(a) behaves as a negative acute-phase reactant during major inflammatory response. Nongenetic factors have a major, acute, and unexpected impact on Lp(a) metabolism in burns and sepsis. Identification of these factors may provide new tools to lower elevated plasma Lp(a) levels.
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Affiliation(s)
- V Mooser
- Department of Medicine, CHUV University Hospital, Lausanne, Switzerland.
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Abstract
Lipoprotein(a) [Lp(a)] is a genetically determined risk factor for atherosclerotic vascular disease. Several studies have described a correlation between high Lp(a) plasma levels and coronary heart disease, stroke, and peripheral atherosclerosis. In healthy individuals Lp(a) plasma concentrations are almost exclusively controlled by the apolipoprotein(a) [apo(a)] gene locus on chromosome 6q2.6-q2.7. More than 30 alleles at this highly polymorphic gene locus determine a size polymorphism of apo(a). There exists an inverse correlation between the size (molecular weight) of apo(a) isoforms and Lp(a) plasma concentrations. Average Lp(a) levels are high in individuals with low molecular weight isoforms and low in those with high molecular weight isoforms. Mean Lp(a) plasma levels are elevated over controls in patients with renal disease. Patients with nephrotic syndrome exhibit excessively high Lp(a) plasma concentrations, which can be reduced with antiproteinuric treatment. The mechanism underlying this elevation is unclear, but the general increase in protein synthesis caused by the liver due to high urinary protein loss is a likely explanation. Patients with end-stage renal disease (ESRD) also have elevated Lp(a) levels. These are even higher in patients treated by continuous ambulatory peritoneal dialysis than in those receiving hemodialysis. Lipoprotein(a) concentrations decrease to values observed in controls matched for apo(a) type following renal transplantation. This clearly demonstrates the nongenetic origin of Lp(a) elevation in ESRD. Both the increase in ESRD and the decrease following renal transplantation are apo(a) phenotype dependent. Only patients with high molecular weight phenotypes show the described changes in Lp(a) levels. In patients with low molecular weight types the Lp(a) concentrations remain unchanged during both phases of renal disease. As in the general population, Lp(a) is a risk factor for cardiovascular events in ESRD patients. In this patient group the apo(a) phenotype seems to be equally or better predictive of the degree of atherosclerosis than is Lp(a) concentration. Further prospective studies will be necessary to confirm these observations. Whether Lp(a) also plays a key role in the pathogenesis and progression of renal diseases needs further study. Controversial data on the role of the kidney in Lp(a) metabolism result from insufficient sample sizes of several studies. Due to the broad range and skewed distribution of Lp(a) plasma concentrations, large study groups must be investigated to obtain reliable results.
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Affiliation(s)
- F Kronenberg
- Institute of Medical Biology and Human Genetics, University of Innsbruck, Austria
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