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Lorey MB, Öörni K, Kovanen PT. Modified Lipoproteins Induce Arterial Wall Inflammation During Atherogenesis. Front Cardiovasc Med 2022; 9:841545. [PMID: 35310965 PMCID: PMC8927694 DOI: 10.3389/fcvm.2022.841545] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 01/26/2022] [Indexed: 12/15/2022] Open
Abstract
Circulating apolipoprotein B-containing lipoproteins, notably the low-density lipoproteins, enter the inner layer of the arterial wall, the intima, where a fraction of them is retained and modified by proteases, lipases, and oxidizing agents and enzymes. The modified lipoproteins and various modification products, such as fatty acids, ceramides, lysophospholipids, and oxidized lipids induce inflammatory reactions in the macrophages and the covering endothelial cells, initiating an increased leukocyte diapedesis. Lipolysis of the lipoproteins also induces the formation of cholesterol crystals with strong proinflammatory properties. Modified and aggregated lipoproteins, cholesterol crystals, and lipoproteins isolated from human atherosclerotic lesions, all can activate macrophages and thereby induce the secretion of proinflammatory cytokines, chemokines, and enzymes. The extent of lipoprotein retention, modification, and aggregation have been shown to depend largely on differences in the composition of the circulating lipoprotein particles. These properties can be modified by pharmacological means, and thereby provide opportunities for clinical interventions regarding the prevention and treatment of atherosclerotic vascular diseases.
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Affiliation(s)
- Martina B. Lorey
- Atherosclerosis Research Laboratory, Wihuri Research Institute, Helsinki, Finland
- Molecular and Integrative Biosciences, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Katariina Öörni
- Atherosclerosis Research Laboratory, Wihuri Research Institute, Helsinki, Finland
- Molecular and Integrative Biosciences, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
- *Correspondence: Katariina Öörni
| | - Petri T. Kovanen
- Atherosclerosis Research Laboratory, Wihuri Research Institute, Helsinki, Finland
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2
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Öörni K, Kovanen PT. Aggregation Susceptibility of Low-Density Lipoproteins-A Novel Modifiable Biomarker of Cardiovascular Risk. J Clin Med 2021; 10:1769. [PMID: 33921661 PMCID: PMC8074066 DOI: 10.3390/jcm10081769] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 03/31/2021] [Accepted: 04/13/2021] [Indexed: 01/07/2023] Open
Abstract
Circulating low-density lipoprotein (LDL) particles enter the arterial intima where they bind to the extracellular matrix and become modified by lipases, proteases, and oxidizing enzymes and agents. The modified LDL particles aggregate and fuse into larger matrix-bound lipid droplets and, upon generation of unesterified cholesterol, cholesterol crystals are also formed. Uptake of the aggregated/fused particles and cholesterol crystals by macrophages and smooth muscle cells induces their inflammatory activation and conversion into foam cells. In this review, we summarize the causes and consequences of LDL aggregation and describe the development and applications of an assay capable of determining the susceptibility of isolated LDL particles to aggregate when exposed to human recombinant sphingomyelinase enzyme ex vivo. Significant person-to-person differences in the aggregation susceptibility of LDL particles were observed, and such individual differences largely depended on particle lipid composition. The presence of aggregation-prone LDL in the circulation predicted future cardiovascular events in patients with atherosclerotic cardiovascular disease. We also discuss means capable of reducing LDL particles' aggregation susceptibility that could potentially inhibit LDL aggregation in the arterial wall. Whether reductions in LDL aggregation susceptibility are associated with attenuated atherogenesis and a reduced risk of atherosclerotic cardiovascular diseases remains to be studied.
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Affiliation(s)
- Katariina Öörni
- Wihuri Research Institute, 00290 Helsinki, Finland;
- Molecular and Integrative Biosciences Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, 00014 Helsinki, Finland
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3
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Ruuth M, Janssen LG, Äikäs L, Tigistu-Sahle F, Nahon KJ, Ritvos O, Ruhanen H, Käkelä R, Boon MR, Öörni K, Rensen PC. LDL aggregation susceptibility is higher in healthy South Asian compared with white Caucasian men. J Clin Lipidol 2019; 13:910-919.e2. [DOI: 10.1016/j.jacl.2019.09.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 08/20/2019] [Accepted: 09/22/2019] [Indexed: 12/13/2022]
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4
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Öörni K, Lehti S, Sjövall P, Kovanen PT. Triglyceride-Rich Lipoproteins as a Source of Proinflammatory Lipids in the Arterial Wall. Curr Med Chem 2019; 26:1701-1710. [DOI: 10.2174/0929867325666180530094819] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 12/27/2017] [Accepted: 01/01/2018] [Indexed: 12/11/2022]
Abstract
Apolipoprotein B –containing lipoproteins include triglyceride-rich lipoproteins
(chylomicrons and their remnants, and very low-density lipoproteins and their remnants) and
cholesterol-rich low-density lipoprotein particles. Of these, lipoproteins having sizes below
70-80 nm may enter the arterial wall, where they accumulate and induce the formation of
atherosclerotic lesions. The processes that lead to accumulation of lipoprotein-derived lipids
in the arterial wall have been largely studied with a focus on the low-density lipoprotein particles.
However, recent observational and genetic studies have discovered that the triglyceriderich
lipoproteins and their remnants are linked with cardiovascular disease risk. In this review,
we describe the potential mechanisms by which the triglyceride-rich remnant lipoproteins can
contribute to the development of atherosclerotic lesions, and highlight the differences in the
atherogenicity between low-density lipoproteins and the remnant lipoproteins.
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Affiliation(s)
| | - Satu Lehti
- Wihuri Research Institute, Helsinki, Finland
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5
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Håversen L, Sundelin JP, Mardinoglu A, Rutberg M, Ståhlman M, Wilhelmsson U, Hultén LM, Pekny M, Fogelstrand P, Bentzon JF, Levin M, Borén J. Vimentin deficiency in macrophages induces increased oxidative stress and vascular inflammation but attenuates atherosclerosis in mice. Sci Rep 2018; 8:16973. [PMID: 30451917 PMCID: PMC6242955 DOI: 10.1038/s41598-018-34659-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 09/27/2018] [Indexed: 12/14/2022] Open
Abstract
The aim was to clarify the role of vimentin, an intermediate filament protein abundantly expressed in activated macrophages and foam cells, in macrophages during atherogenesis. Global gene expression, lipid uptake, ROS, and inflammation were analyzed in bone-marrow derived macrophages from vimentin-deficient (Vim-/-) and wild-type (Vim+/+) mice. Atherosclerosis was induced in Ldlr-/- mice transplanted with Vim-/- and Vim+/+ bone marrow, and in Vim-/- and Vim+/+ mice injected with a PCSK9 gain-of-function virus. The mice were fed an atherogenic diet for 12-15 weeks. We observed impaired uptake of native LDL but increased uptake of oxLDL in Vim-/- macrophages. FACS analysis revealed increased surface expression of the scavenger receptor CD36 on Vim-/- macrophages. Vim-/- macrophages also displayed increased markers of oxidative stress, activity of the transcription factor NF-κB, secretion of proinflammatory cytokines and GLUT1-mediated glucose uptake. Vim-/- mice displayed decreased atherogenesis despite increased vascular inflammation and increased CD36 expression on macrophages in two mouse models of atherosclerosis. We demonstrate that vimentin has a strong suppressive effect on oxidative stress and that Vim-/- mice display increased vascular inflammation with increased CD36 expression on macrophages despite decreased subendothelial lipid accumulation. Thus, vimentin has a key role in regulating inflammation in macrophages during atherogenesis.
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Affiliation(s)
- Liliana Håversen
- Department of Molecular and Clinical Medicine/Wallenberg Laboratory, University of Gothenburg, and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Jeanna Perman Sundelin
- Strategic planning and operations, Cardiovascular and metabolic diseases, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - Adil Mardinoglu
- Science for Life Laboratory, KTH - Royal Institute of Technology, Stockholm, Sweden
- Centre for Host-Microbiome Interactions, Dental Institute, King's College London, London, SE1 9RT, United Kingdom
| | - Mikael Rutberg
- Department of Molecular and Clinical Medicine/Wallenberg Laboratory, University of Gothenburg, and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Marcus Ståhlman
- Department of Molecular and Clinical Medicine/Wallenberg Laboratory, University of Gothenburg, and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Ulrika Wilhelmsson
- Department of Clinical Neuroscience/Center for Brain Repair, University of Gothenburg, Gothenburg, Sweden
| | - Lillemor Mattsson Hultén
- Department of Molecular and Clinical Medicine/Wallenberg Laboratory, University of Gothenburg, and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Milos Pekny
- Department of Clinical Neuroscience/Center for Brain Repair, University of Gothenburg, Gothenburg, Sweden
| | - Per Fogelstrand
- Department of Molecular and Clinical Medicine/Wallenberg Laboratory, University of Gothenburg, and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Jacob Fog Bentzon
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark, and Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain
| | - Malin Levin
- Department of Molecular and Clinical Medicine/Wallenberg Laboratory, University of Gothenburg, and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Jan Borén
- Department of Molecular and Clinical Medicine/Wallenberg Laboratory, University of Gothenburg, and Sahlgrenska University Hospital, Gothenburg, Sweden.
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6
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Helmke A, Casper J, Nordlohne J, David S, Haller H, Zeisberg EM, Vietinghoff S. Endothelial‐to‐mesenchymal transition shapes the atherosclerotic plaque and modulates macrophage function. FASEB J 2018; 33:2278-2289. [DOI: 10.1096/fj.201801238r] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Alexandra Helmke
- Division of Nephrology and HypertensionDepartment of Internal MedicineHannover Medical SchoolHannoverGermany
| | - Janis Casper
- Division of Nephrology and HypertensionDepartment of Internal MedicineHannover Medical SchoolHannoverGermany
| | - Johannes Nordlohne
- Division of Nephrology and HypertensionDepartment of Internal MedicineHannover Medical SchoolHannoverGermany
| | - Sascha David
- Division of Nephrology and HypertensionDepartment of Internal MedicineHannover Medical SchoolHannoverGermany
| | - Hermann Haller
- Division of Nephrology and HypertensionDepartment of Internal MedicineHannover Medical SchoolHannoverGermany
| | - Elisabeth M. Zeisberg
- Department of Cardiology and PneumologyUniversity Medical Center of GöttingenGöttingenGermany
- German Centre for Cardiovascular Research (DZHK)Partner Site GöttingenGöttingenGermany
| | - Sibylle Vietinghoff
- Division of Nephrology and HypertensionDepartment of Internal MedicineHannover Medical SchoolHannoverGermany
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7
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Nègre-Salvayre A, Augé N, Camaré C, Bacchetti T, Ferretti G, Salvayre R. Dual signaling evoked by oxidized LDLs in vascular cells. Free Radic Biol Med 2017; 106:118-133. [PMID: 28189852 DOI: 10.1016/j.freeradbiomed.2017.02.006] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Revised: 01/30/2017] [Accepted: 02/02/2017] [Indexed: 12/12/2022]
Abstract
The oxidative theory of atherosclerosis relies on the modification of low density lipoproteins (LDLs) in the vascular wall by reactive oxygen species. Modified LDLs, such as oxidized LDLs, are thought to participate in the formation of early atherosclerotic lesions (accumulation of foam cells and fatty streaks), whereas their role in advanced lesions and atherothrombotic events is more debated, because antioxidant supplementation failed to prevent coronary disease events and mortality in intervention randomized trials. As oxidized LDLs and oxidized lipids are present in atherosclerotic lesions and are able to trigger cell signaling on cultured vascular cells and macrophages, it has been proposed that they could play a role in atherogenesis and atherosclerotic vascular remodeling. Oxidized LDLs exhibit dual biological effects, which are dependent on extent of lipid peroxidation, nature of oxidized lipids (oxidized phospholipids, oxysterols, malondialdehyde, α,β-unsaturated hydroxyalkenals), concentration of oxidized LDLs and uptake by scavenger receptors (e.g. CD36, LOX-1, SRA) that signal through different transduction pathways. Moderate concentrations of mildly oxidized LDLs are proinflammatory and trigger cell migration and proliferation, whereas higher concentrations induce cell growth arrest and apoptosis. The balance between survival and apoptotic responses evoked by oxidized LDLs depends on cellular systems that regulate the cell fate, such as ceramide/sphingosine-1-phosphate rheostat, endoplasmic reticulum stress, autophagy and expression of pro/antiapoptotic proteins. In vivo, the intimal concentration of oxidized LDLs depends on the influx (hypercholesterolemia, endothelial permeability), residence time and lipid composition of LDLs, oxidative stress intensity, induction of defense mechanisms (antioxidant systems, heat shock proteins). As a consequence, the local cellular responses to oxidized LDLs may stimulate inflammatory or anti-inflammatory pathways, angiogenic or antiangiogenic responses, survival or apoptosis, thereby contributing to plaque growth, instability, complication (intraplaque hemorrhage, proteolysis, calcification, apoptosis) and rupture. Finally, these dual properties suggest that oxLDLs could be implicated at each step of atherosclerosis development, from early fatty streaks to advanced lesions, depending on the nature and concentration of their oxidized lipid content.
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Affiliation(s)
| | | | - Caroline Camaré
- Inserm UMR-1048, France; University of Toulouse, Faculty of Medicine, Biochemistry Dept, Toulouse, France; CHU Toulouse, Rangueil, Toulouse, France
| | | | | | - Robert Salvayre
- Inserm UMR-1048, France; University of Toulouse, Faculty of Medicine, Biochemistry Dept, Toulouse, France; CHU Toulouse, Rangueil, Toulouse, France.
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8
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Transcriptomic Analysis of THP-1 Macrophages Exposed to Lipoprotein Hydrolysis Products Generated by Lipoprotein Lipase. Lipids 2017; 52:189-205. [DOI: 10.1007/s11745-017-4238-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 02/02/2017] [Indexed: 11/25/2022]
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9
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von Scheidt M, Zhao Y, Kurt Z, Pan C, Zeng L, Yang X, Schunkert H, Lusis AJ. Applications and Limitations of Mouse Models for Understanding Human Atherosclerosis. Cell Metab 2017; 25:248-261. [PMID: 27916529 PMCID: PMC5484632 DOI: 10.1016/j.cmet.2016.11.001] [Citation(s) in RCA: 145] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 08/26/2016] [Accepted: 11/03/2016] [Indexed: 12/13/2022]
Abstract
Most of the biological understanding of mechanisms underlying coronary artery disease (CAD) derives from studies of mouse models. The identification of multiple CAD loci and strong candidate genes in large human genome-wide association studies (GWASs) presented an opportunity to examine the relevance of mouse models for the human disease. We comprehensively reviewed the mouse literature, including 827 literature-derived genes, and compared it to human data. First, we observed striking concordance of risk factors for atherosclerosis in mice and humans. Second, there was highly significant overlap of mouse genes with human genes identified by GWASs. In particular, of the 46 genes with strong association signals in CAD GWASs that were studied in mouse models, all but one exhibited consistent effects on atherosclerosis-related phenotypes. Third, we compared 178 CAD-associated pathways derived from human GWASs with 263 from mouse studies and observed that the majority were consistent between the species.
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Affiliation(s)
- Moritz von Scheidt
- Deutsches Herzzentrum München, Technische Universität München, 80333 Munich, Germany
| | - Yuqi Zhao
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Zeyneb Kurt
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Calvin Pan
- Departments of Medicine, Microbiology, and Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Lingyao Zeng
- Deutsches Herzzentrum München, Technische Universität München, 80333 Munich, Germany
| | - Xia Yang
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Heribert Schunkert
- Deutsches Herzzentrum München, Technische Universität München, 80333 Munich, Germany; Deutsches Zentrum für Herz- und Kreislauferkrankungen (DZHK), Partner Site Munich Heart Alliance, 80336 Munich, Germany
| | - Aldons J Lusis
- Departments of Medicine, Microbiology, and Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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10
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Lauriano ER, Pergolizzi S, Capillo G, Kuciel M, Alesci A, Faggio C. Immunohistochemical characterization of Toll-like receptor 2 in gut epithelial cells and macrophages of goldfish Carassius auratus fed with a high-cholesterol diet. FISH & SHELLFISH IMMUNOLOGY 2016; 59:250-255. [PMID: 27818343 DOI: 10.1016/j.fsi.2016.11.003] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 10/28/2016] [Accepted: 11/02/2016] [Indexed: 06/06/2023]
Abstract
Toll-like receptors (TLRs) are a group of pattern recognition molecules that play a crucial role in innate immunity. The structural conservation of the archaic TLR system suggests that the regulation of the immune response might be similar in fish and mammals. Several TLRs (TLR-1, -2, and -4) are expressed by activated macrophages, "foam cells" in human atherosclerotic lesions. To date, 20 different TLRs were identified in more than a dozen different fish species. In this study we found that feeding goldfish, Carrassius auratus, a high-cholesterol diet (HCD) resulted macrophage foam cell formation in the intestinal tissues. The expression of TLR2 has been found in foam cells and in the cytoplasm of enterocytes, however the staining was more intense at the apical surface of polarized intestinal epithelial cells and in the lamina propria. In the intestinal epithelial cells and in the lamina propria cells of the control fish the TLR2 was expressed at low levels. The intestinal epithelium is directly involved in the mucosal immune response through its expression of proinflammatory genes, release of inflammatory cytokines, and recruitment of inflammatory cells.
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Affiliation(s)
- E R Lauriano
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy
| | - S Pergolizzi
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy
| | - G Capillo
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy
| | - M Kuciel
- Department of Comparative Anatomy, Institute of Zoology, Jagiellonian University, Gronostajowa 9, 30-387 Krakow, Poland
| | - A Alesci
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy
| | - C Faggio
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy.
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11
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Physiology and pathophysiology of oxLDL uptake by vascular wall cells in atherosclerosis. Vascul Pharmacol 2016; 84:1-7. [PMID: 27256928 DOI: 10.1016/j.vph.2016.05.013] [Citation(s) in RCA: 178] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 04/26/2016] [Accepted: 05/28/2016] [Indexed: 01/09/2023]
Abstract
Atherosclerosis is a progressive disease in which endothelial cell dysfunction, macrophage foam cell formation, and smooth muscle cell migration and proliferation, lead to the loss of vascular homeostasis. Oxidized low-density lipoprotein (oxLDL) may play a pre-eminent function in atherosclerotic lesion formation, even if their role is still debated. Several types of scavenger receptors (SRs) such as SR-AI/II, SRBI, CD36, lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), toll-like receptors (TLRs) and others can promote the internalization of oxLDL. They are expressed on the surface of vascular wall cells (endothelial cells, macrophages and smooth muscle cells) and they mediate the cellular effects of oxLDL. The key influence of both oxLDL and SRs on the atherogenic process has been established in atherosclerosis-prone animals, in which antioxidant treatment and/or silencing of SRs has been shown to reduce atherogenesis. Despite some discrepancies, the indication from cohort studies that there is an association between oxLDL and cardiovascular (CV) events seems to point toward a role for oxLDL in atherosclerotic plaque progress and disruption. Finally, randomized clinical trials using antioxidants have demonstrated benefits only in high-risk patients, suggesting that additional proofs are still needed to better define the involvement of each type of modified LDL in the development of atherosclerosis.
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12
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Gleissner CA. Translational atherosclerosis research: From experimental models to coronary artery disease in humans. Atherosclerosis 2016; 248:110-6. [DOI: 10.1016/j.atherosclerosis.2016.03.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 02/09/2016] [Accepted: 03/08/2016] [Indexed: 01/23/2023]
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13
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Lanatoside C Promotes Foam Cell Formation and Atherosclerosis. Sci Rep 2016; 6:20154. [PMID: 26821916 PMCID: PMC4731744 DOI: 10.1038/srep20154] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 12/30/2015] [Indexed: 12/18/2022] Open
Abstract
Lanatoside C’s impact on atherosclerosis is poorly understood. The present study was conducted to determine whether lanatoside C affects the development of atherosclerosis in apolipoprotein E-deficient (ApoE–/–) mice. ApoE–/– mice were administered either phosphate-buffered saline (PBS) containing 0.1% DMSO (the vehicle control group) or lanatoside C at low (1 mg/kg per day) or high (2 mg/kg per day) doses, and fed a Western diet for 12 weeks. Lanatoside C dose-dependently aggravated the development of atherosclerosis in the ApoE–/– mice compared with the vehicle control group. In an effort to determine the mechanism by which lanatoside C increased atherosclerosis, we found that lanatoside C significantly promoted the uptake of oxidised low-density lipoprotein (oxLDL) and increased foam-cell formation by upregulation of scavenger receptor class A (SR-A) and the class B scavenger receptor (CD36) in macrophages. Meanwhile, the effects of lanatoside C were abolished using small interfering RNA (siRNA) inhibition of peroxisome proliferator-activated receptors β/δ (PPARβ/δ). Overall, our data demonstrate that lanatoside C aggravates the development of atherosclerosis by inducing PPARβ/δ expression, which mediates upregulation of SR-A and CD36, and promotes oxLDL uptake and foam-cell formation.
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14
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Witztum JL. CEP Is an Important and Ubiquitous Oxidation Specific Epitope Recognized by Innate Pattern Recognition Receptors. Circ Res 2015; 117:305-8. [PMID: 26227873 DOI: 10.1161/circresaha.115.306928] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Joseph L Witztum
- From the Department of Medicine, University of California, San Diego.
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15
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Abstract
High-density lipoproteins (HDLs) exert many beneficial effects which may help to protect against the development or progression of atherosclerosis or even facilitate lesion regression. These activities include promoting cellular cholesterol efflux, protecting low-density lipoproteins (LDLs) from modification, preserving endothelial function, as well as anti-inflammatory and antithrombotic effects. However, questions remain about the relative importance of these activities for atheroprotection. Furthermore, the many molecules (both lipids and proteins) associated with HDLs exert both distinct and overlapping activities, which may be compromised by inflammatory conditions, resulting in either loss of function or even gain of dysfunction. This complexity of HDL functionality has so far precluded elucidation of distinct structure-function relationships for HDL or its components. A better understanding of HDL metabolism and structure-function relationships is therefore crucial to exploit HDLs and its associated components and cellular pathways as potential targets for anti-atherosclerotic therapies and diagnostic markers.
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Affiliation(s)
- Wijtske Annema
- Institute of Clinical Chemistry, University Hospital Zurich, Zurich, Switzerland,
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16
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Öörni K, Rajamäki K, Nguyen SD, Lähdesmäki K, Plihtari R, Lee-Rueckert M, Kovanen PT. Acidification of the intimal fluid: the perfect storm for atherogenesis. J Lipid Res 2014; 56:203-14. [PMID: 25424004 DOI: 10.1194/jlr.r050252] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Atherosclerotic lesions are often hypoxic and exhibit elevated lactate concentrations and local acidification of the extracellular fluids. The acidification may be a consequence of the abundant accumulation of lipid-scavenging macrophages in the lesions. Activated macrophages have a very high energy demand and they preferentially use glycolysis for ATP synthesis even under normoxic conditions, resulting in enhanced local generation and secretion of lactate and protons. In this review, we summarize our current understanding of the effects of acidic extracellular pH on three key players in atherogenesis: macrophages, apoB-containing lipoproteins, and HDL particles. Acidic extracellular pH enhances receptor-mediated phagocytosis and antigen presentation by macrophages and, importantly, triggers the secretion of proinflammatory cytokines from macrophages through activation of the inflammasome pathway. Acidity enhances the proteolytic, lipolytic, and oxidative modifications of LDL and other apoB-containing lipoproteins, and strongly increases their affinity for proteoglycans, and may thus have major effects on their retention and the ensuing cellular responses in the arterial intima. Finally, the decrease in the expression of ABCA1 at acidic pH may compromise cholesterol clearance from atherosclerotic lesions. Taken together, acidic extracellular pH amplifies the proatherogenic and proinflammatory processes involved in atherogenesis.
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17
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Linden F, Domschke G, Erbel C, Akhavanpoor M, Katus HA, Gleissner CA. Inflammatory therapeutic targets in coronary atherosclerosis-from molecular biology to clinical application. Front Physiol 2014; 5:455. [PMID: 25484870 PMCID: PMC4240064 DOI: 10.3389/fphys.2014.00455] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 11/04/2014] [Indexed: 01/13/2023] Open
Abstract
Atherosclerosis is the leading cause of death worldwide. Over the past two decades, it has been clearly recognized that atherosclerosis is an inflammatory disease of the arterial wall. Accumulating data from animal experiments have supported this hypothesis, however, clinical applications making use of this knowledge remain scarce. In spite of optimal interventional and medical therapy, the risk for recurrent myocardial infarction remains by about 20% over 3 years after acute coronary syndromes, novel therapies to prevent atherogenesis or treat atherosclerosis are urgently needed. This review summarizes selected potential molecular inflammatory targets that may be of clinical relevance. We also review recent and ongoing clinical trails that target inflammatory processes aiming at preventing adverse cardiovascular events. Overall, it seems surprising that translation of basic science into clinical practice has not been a great success. In conclusion, we propose to focus on specific efforts that promote translational science in order to improve outcome and prognosis of patients suffering from atherosclerosis.
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Affiliation(s)
- Fabian Linden
- Department of Cardiology, University of Heidelberg Heidelberg, Germany
| | - Gabriele Domschke
- Department of Cardiology, University of Heidelberg Heidelberg, Germany
| | - Christian Erbel
- Department of Cardiology, University of Heidelberg Heidelberg, Germany
| | | | - Hugo A Katus
- Department of Cardiology, University of Heidelberg Heidelberg, Germany
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LI XIUYING, ZHOU YUANDA, YU CHAO, YANG HUI, ZHANG CHENGZHI, YE YUN, XIAO SHUNLIN. Paeonol suppresses lipid accumulation in macrophages via upregulation of the ATP-binding cassette transporter A1 and downregulation of the cluster of differentiation 36. Int J Oncol 2014; 46:764-74. [DOI: 10.3892/ijo.2014.2757] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Accepted: 10/23/2014] [Indexed: 11/06/2022] Open
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Rao X, Zhong J, Maiseyeu A, Gopalakrishnan B, Villamena FA, Chen LC, Harkema JR, Sun Q, Rajagopalan S. CD36-dependent 7-ketocholesterol accumulation in macrophages mediates progression of atherosclerosis in response to chronic air pollution exposure. Circ Res 2014; 115:770-780. [PMID: 25186795 DOI: 10.1161/circresaha.115.304666] [Citation(s) in RCA: 133] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
RATIONALE Air pollution exposure has been shown to potentiate plaque progression in humans and animals. Our previous studies have suggested a role for oxidized lipids in mediating adverse vascular effect of air pollution. However, the types of oxidized lipids formed in response to air pollutants and how this occurs and their relevance to atherosclerosis are not fully understood. OBJECTIVE To investigate the mechanisms by which particulate matter <2.5 μm (PM2.5) induces progression of atherosclerosis. METHODS AND RESULTS Atherosclerosis-prone ApoE(-/-) or LDLR(-/-) mice were exposed to filtered air or concentrated ambient PM2.5 using a versatile aerosol concentrator enrichment system for 6 months. PM2.5 increased 7-ketocholesterol (7-KCh), an oxidatively modified form of cholesterol, in plasma intermediate density lipoprotein/low-density lipoprotein fraction and in aortic plaque concomitant with progression of atherosclerosis and increased CD36 expression in plaque macrophages from PM2.5-exposed mice. Macrophages isolated from PM2.5-exposed mice displayed increased uptake of oxidized lipids without alterations in their efflux capacity. Consistent with these finding, CD36-positive macrophages displayed a heightened capacity for oxidized lipid uptake. Deficiency of CD36 on hematopoietic cells diminished the effect of air pollution on 7-KCh accumulation, foam cell formation, and atherosclerosis. CONCLUSIONS Our results suggest a potential role for CD36-mediated abnormal accumulations of oxidized lipids, such as 7-KCh, in air pollution-induced atherosclerosis progression.
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Affiliation(s)
- Xiaoquan Rao
- Division of Cardiovascular Medicine, University of Maryland Baltimore, Maryland, USA
| | - Jixin Zhong
- Division of Cardiovascular Medicine, University of Maryland Baltimore, Maryland, USA
| | - Andrei Maiseyeu
- Division of Cardiovascular Medicine, University of Maryland Baltimore, Maryland, USA
| | - Bhavani Gopalakrishnan
- Department of Pharmacology, Davis Heart & Lung Research Institute, The Ohio State University, Columbus, Ohio, USA
| | - Frederick A Villamena
- Department of Pharmacology, Davis Heart & Lung Research Institute, The Ohio State University, Columbus, Ohio, USA
| | - Lung-Chi Chen
- The Department of Environmental Medicine, New York University School of Medicine, Tuxedo, New York, USA
| | - Jack R Harkema
- Center for Integrative Toxicology and Department of Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, Michigan, USA
| | - Qinghua Sun
- Department of Pharmacology, Davis Heart & Lung Research Institute, The Ohio State University, Columbus, Ohio, USA.,College of Public Health, The Ohio State University, Columbus, Ohio, USA
| | - Sanjay Rajagopalan
- Division of Cardiovascular Medicine, University of Maryland Baltimore, Maryland, USA
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Park YM. CD36, a scavenger receptor implicated in atherosclerosis. Exp Mol Med 2014; 46:e99. [PMID: 24903227 PMCID: PMC4081553 DOI: 10.1038/emm.2014.38] [Citation(s) in RCA: 348] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 03/17/2014] [Accepted: 04/08/2014] [Indexed: 12/17/2022] Open
Abstract
CD36 is a membrane glycoprotein that is present on various types of cells, including monocytes, macrophages, microvascular endothelial cells, adipocytes and platelets. Macrophage CD36 participates in atherosclerotic arterial lesion formation through its interaction with oxidized low-density lipoprotein (oxLDL), which triggers signaling cascades for inflammatory responses. CD36 functions in oxLDL uptake and foam cell formation, which is the initial critical stage of atherosclerosis. In addition, oxLDL via CD36 inhibits macrophage migration, which may be a macrophage-trapping mechanism in atherosclerotic lesions. The role of CD36 was examined in in vitro studies and in vivo experiments, which investigated various functions of CD36 in atherosclerosis and revealed that CD36 deficiency reduces atherosclerotic lesion formation. Platelet CD36 also promotes atherosclerotic inflammatory processes and is involved in thrombus formation after atherosclerotic plaque rupture. Because CD36 is an essential component of atherosclerosis, defining the function of CD36 and its corresponding signaling pathway may lead to a new treatment strategy for atherosclerosis.
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Affiliation(s)
- Young Mi Park
- Department of Molecular Medicine, Ewha Womans University School of Medicine, Seoul, Republic of Korea
- Ewha Global Top 5 Research Program, Ewha Womans University, Seoul, Republic of Korea
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Abstract
Atherosclerosis causes clinical disease through luminal narrowing or by precipitating thrombi that obstruct blood flow to the heart (coronary heart disease), brain (ischemic stroke), or lower extremities (peripheral vascular disease). The most common of these manifestations is coronary heart disease, including stable angina pectoris and the acute coronary syndromes. Atherosclerosis is a lipoprotein-driven disease that leads to plaque formation at specific sites of the arterial tree through intimal inflammation, necrosis, fibrosis, and calcification. After decades of indolent progression, such plaques may suddenly cause life-threatening coronary thrombosis presenting as an acute coronary syndrome. Most often, the culprit morphology is plaque rupture with exposure of highly thrombogenic, red cell–rich necrotic core material. The permissive structural requirement for this to occur is an extremely thin fibrous cap, and thus, ruptures occur mainly among lesions defined as thin-cap fibroatheromas. Also common are thrombi forming on lesions without rupture (plaque erosion), most often on pathological intimal thickening or fibroatheromas. However, the mechanisms involved in plaque erosion remain largely unknown, although coronary spasm is suspected. The calcified nodule has been suggested as a rare cause of coronary thrombosis in highly calcified and tortious arteries in older individuals. To characterize the severity and prognosis of plaques, several terms are used. Plaque burden denotes the extent of disease, whereas plaque activity is an ambiguous term, which may refer to one of several processes that characterize progression. Plaque vulnerability describes the short-term risk of precipitating symptomatic thrombosis. In this review, we discuss mechanisms of atherosclerotic plaque initiation and progression; how plaques suddenly precipitate life-threatening thrombi; and the concepts of plaque burden, activity, and vulnerability.
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Maiolino G, Rossitto G, Caielli P, Bisogni V, Rossi GP, Calò LA. The role of oxidized low-density lipoproteins in atherosclerosis: the myths and the facts. Mediators Inflamm 2013; 2013:714653. [PMID: 24222937 PMCID: PMC3816061 DOI: 10.1155/2013/714653] [Citation(s) in RCA: 179] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Accepted: 08/28/2013] [Indexed: 02/07/2023] Open
Abstract
The oxidative modification hypothesis of atherosclerosis, which assigns to oxidized low-density lipoproteins (LDLs) a crucial role in atherosclerosis initiation and progression, is still debated. This review examines the role played by oxidized LDLs in atherogenesis taking into account data derived by studies based on molecular and clinical approaches. Experimental data carried out in cellular lines and animal models of atherosclerosis support the proatherogenic role of oxidized LDLs: (a) through chemotactic and proliferating actions on monocytes/macrophages, inciting their transformation into foam cells; (b) through stimulation of smooth muscle cells (SMCs) recruitment and proliferation in the tunica intima; (c) through eliciting endothelial cells, SMCs, and macrophages apoptosis with ensuing necrotic core development. Moreover, most of the experimental data on atherosclerosis-prone animals benefiting from antioxidant treatment points towards a link between oxidative stress and atherosclerosis. The evidence coming from cohort studies demonstrating an association between oxidized LDLs and cardiovascular events, notwithstanding some discrepancies, seems to point towards a role of oxidized LDLs in atherosclerotic plaque development and destabilization. Finally, the results of randomized clinical trials employing antioxidants completed up to date, despite demonstrating no benefits in healthy populations, suggest a benefit in high-risk patients. In conclusion, available data seem to validate the oxidative modification hypothesis of atherosclerosis, although additional proofs are still needed.
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Affiliation(s)
- Giuseppe Maiolino
- Department of Medicine (DIMED), Internal Medicine 4, University of Padova, Via Giustiniani 2, 35128 Padova, Italy
| | - Giacomo Rossitto
- Department of Medicine (DIMED), Internal Medicine 4, University of Padova, Via Giustiniani 2, 35128 Padova, Italy
| | - Paola Caielli
- Department of Medicine (DIMED), Internal Medicine 4, University of Padova, Via Giustiniani 2, 35128 Padova, Italy
| | - Valeria Bisogni
- Department of Medicine (DIMED), Internal Medicine 4, University of Padova, Via Giustiniani 2, 35128 Padova, Italy
| | - Gian Paolo Rossi
- Department of Medicine (DIMED), Internal Medicine 4, University of Padova, Via Giustiniani 2, 35128 Padova, Italy
| | - Lorenzo A. Calò
- Department of Medicine (DIMED), Internal Medicine 4, University of Padova, Via Giustiniani 2, 35128 Padova, Italy
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Witztum JL, Lichtman AH. The influence of innate and adaptive immune responses on atherosclerosis. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2013; 9:73-102. [PMID: 23937439 DOI: 10.1146/annurev-pathol-020712-163936] [Citation(s) in RCA: 204] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Both the chronic development of atherosclerotic lesions and the acute changes in lesion phenotype that lead to clinical cardiovascular events are significantly influenced by the innate and adaptive immune responses to lipoprotein deposition and oxidation in the arterial wall. The rapid pace of discovery of mechanisms of immunologic recognition, effector functions, and regulation has significantly influenced the study of atherosclerosis, and our new knowledge is beginning to affect how we treat this ubiquitous disease. In this review, we discuss recent advances in our understanding of how innate and adaptive immunity contribute to atherosclerosis, as well as therapeutic opportunities that arise from this knowledge.
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Affiliation(s)
- Joseph L Witztum
- Department of Medicine, University of California, San Diego, La Jolla, California 92093;
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24
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Tsimikas S, Miyanohara A, Hartvigsen K, Merki E, Shaw PX, Chou MY, Pattison J, Torzewski M, Sollors J, Friedmann T, Lai NC, Hammond HK, Getz GS, Reardon CA, Li AC, Banka CL, Witztum JL. Human oxidation-specific antibodies reduce foam cell formation and atherosclerosis progression. J Am Coll Cardiol 2013; 58:1715-27. [PMID: 21982317 DOI: 10.1016/j.jacc.2011.07.017] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2011] [Revised: 07/11/2011] [Accepted: 07/11/2011] [Indexed: 12/31/2022]
Abstract
OBJECTIVES We sought to assess the in vivo importance of scavenger receptor (SR)-mediated uptake of oxidized low-density lipoprotein (OxLDL) in atherogenesis and to test the efficacy of human antibody IK17-Fab or IK17 single-chain Fv fragment (IK17-scFv), which lacks immunologic properties of intact antibodies other than the ability to inhibit uptake of OxLDL by macrophages, to inhibit atherosclerosis. BACKGROUND The unregulated uptake of OxLDL by macrophage SR contributes to foam cell formation, but the importance of this pathway in vivo is uncertain. METHODS Cholesterol-fed low-density lipoprotein receptor knockout (LDLR(-/-)) mice were treated with intraperitoneal infusion of human IK17-Fab (2.5 mg/kg) 3 times per week for 14 weeks. Because anti-human antibodies developed in these mice, LDLR(-/-)/low-density lipoprotein receptor Rag 1 double-knockout mice (lacking the ability to make immunoglobulins due to loss of T- and B-cell function) were treated with an adenoviral vector encoding adenovirus expressed (Adv)-IK17-scFv or control adenovirus-enhanced green fluorescent protein vector intravenously every 2 weeks for 16 weeks. RESULTS In LDLR(-/-) mice, infusion of IK17-Fab was able to sustain IK17 plasma levels for the first 8 weeks, but these diminished afterward due to increasing murine anti-IK17 antibody titers. Despite this, after 14 weeks, a 29% decrease in en face atherosclerosis was noted compared with phosphate-buffered saline-treated mice. In LDLR(-/-)/low-density lipoprotein receptor Rag 1 double-knockout mice, sustained levels of plasma IK17-scFv was achieved by Adv-IK17-scFv-mediated hepatic expression, which led to a 46% reduction (p < 0.001) in en face atherosclerosis compared with adenovirus-enhanced green fluorescent protein vector. Importantly, peritoneal macrophages isolated from Adv-IK17-scFv treated mice had decreased lipid accumulation compared with adenovirus-enhanced green fluorescent protein-treated mice. CONCLUSIONS These data support an important role for SR-mediated uptake of OxLDL in the pathogenesis of atherosclerosis and demonstrate that oxidation-specific antibodies reduce the progression of atherosclerosis, suggesting their potential in treating cardiovascular disease in humans.
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Affiliation(s)
- Sotirios Tsimikas
- Department of Medicine, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0682, USA.
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25
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Barski OA, Xie Z, Baba SP, Sithu SD, Agarwal A, Cai J, Bhatnagar A, Srivastava S. Dietary carnosine prevents early atherosclerotic lesion formation in apolipoprotein E-null mice. Arterioscler Thromb Vasc Biol 2013; 33:1162-70. [PMID: 23559625 DOI: 10.1161/atvbaha.112.300572] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
OBJECTIVE Atherosclerotic lesions are associated with the accumulation of reactive aldehydes derived from oxidized lipids. Although inhibition of aldehyde metabolism has been shown to exacerbate atherosclerosis and enhance the accumulation of aldehyde-modified proteins in atherosclerotic plaques, no therapeutic interventions have been devised to prevent aldehyde accumulation in atherosclerotic lesions. APPROACH AND RESULTS We examined the efficacy of carnosine, a naturally occurring β-alanyl-histidine dipeptide, in preventing aldehyde toxicity and atherogenesis in apolipoprotein E-null mice. In vitro, carnosine reacted rapidly with lipid peroxidation-derived unsaturated aldehydes. Gas chromatography mass-spectrometry analysis showed that carnosine inhibits the formation of free aldehydes 4-hydroxynonenal and malonaldialdehyde in Cu(2+)-oxidized low-density lipoprotein. Preloading bone marrow-derived macrophages with cell-permeable carnosine analogs reduced 4-hydroxynonenal-induced apoptosis. Oral supplementation with octyl-D-carnosine decreased atherosclerotic lesion formation in aortic valves of apolipoprotein E-null mice and attenuated the accumulation of protein-acrolein, protein-4-hydroxyhexenal, and protein-4-hydroxynonenal adducts in atherosclerotic lesions, whereas urinary excretion of aldehydes as carnosine conjugates was increased. CONCLUSIONS The results of this study suggest that carnosine inhibits atherogenesis by facilitating aldehyde removal from atherosclerotic lesions. Endogenous levels of carnosine may be important determinants of atherosclerotic lesion formation, and treatment with carnosine or related peptides could be a useful therapy for the prevention or the treatment of atherosclerosis.
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Affiliation(s)
- Oleg A Barski
- Diabetes and Obesity Center, School of Medicine, University of Louisville, Louisville, KY 40202, USA.
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26
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Leibundgut G, Witztum JL, Tsimikas S. Oxidation-specific epitopes and immunological responses: Translational biotheranostic implications for atherosclerosis. Curr Opin Pharmacol 2013; 13:168-79. [PMID: 23541680 DOI: 10.1016/j.coph.2013.02.005] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 02/18/2013] [Accepted: 02/18/2013] [Indexed: 01/22/2023]
Abstract
Oxidation-specific epitopes (OSE), present on oxidized LDL (OxLDL), apoptotic cells, cell debris and modified proteins in the vessel wall, accumulate in response to hypercholesterolemia, and generate potent pro-inflammatory, disease-specific antigens. They represent an important class of 'danger associated molecular patterns' (DAMPs), against which a concerted innate immune response is directed. OSE are recognized by innate 'pattern recognition receptors', such as scavenger receptors present on dendritic cells and monocyte/macrophages, as well as by innate proteins, such as IgM natural antibodies and soluble proteins, such as C-reactive protein and complement factor H. These innate immune responses provide a first line of defense against atherosclerosis-specific DAMPs, and engage adaptive immune responses, provided by T and B-2 cells, which provide a more specific and definitive response. Such immune responses are ordinarily directed to remove foreign pathogens, such as those found on microbial pathogens, but when persistent or maladaptive, lead to host damage. In this context, atherosclerosis can be considered as a systemic chronic inflammatory disease initiated by the accumulation of OSE type DAMPs and perpetuated by maladaptive response of the innate and adaptive immune system. Understanding this paradigm leads to new approaches to defining cardiovascular risk and suggests new modes of therapy. Therefore, OSE have become potential targets of diagnostic and therapeutic agents. Human and murine OSE-targeting antibodies have been developed and are now being used as biomarkers in human studies and experimentally in translational applications of non-invasive molecular imaging of oxidation-rich plaques and immunotherapeutics.
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Affiliation(s)
- Gregor Leibundgut
- Department of Medicine, University of California San Diego, La Jolla, CA, USA
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27
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Parks BW, Black LL, Zimmerman KA, Metz AE, Steele C, Murphy-Ullrich JE, Kabarowski JH. CD36, but not G2A, modulates efferocytosis, inflammation, and fibrosis following bleomycin-induced lung injury. J Lipid Res 2013; 54:1114-23. [PMID: 23393303 DOI: 10.1194/jlr.m035352] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Macrophage G2A and CD36 lipid receptors are thought to mediate efferocytosis following tissue injury and thereby prevent excessive inflammation that could compromise tissue repair. To test this, we subjected mice lacking G2A or CD36 receptor to bleomycin-induced lung injury and measured efferocytosis, inflammation, and fibrosis. Loss of CD36 (but not G2A) delayed clearance of apoptotic alveolar cells (mean 78% increase in apoptotic cells 7 days postinjury), potentiated inflammation (mean 56% increase in lung neutrophils and 75% increase in lung KC levels 7 days postinjury, 51% increase in lung macrophages 14 days postinjury), and reduced lung fibrosis (mean 41% and 29% reduction 14 and 21 days postinjury, respectively). Reduced fibrosis in CD36(-/-) mice was associated with lower levels of profibrotic TH2 cytokines (IL-9, IL-13, IL-4), decreased expression of the M2 macrophage marker Arginase-1, and reduced interstitial myofibroblasts. G2A, on the other hand, was required for optimal clearance of apoptotic neutrophils during zymosan-induced peritoneal inflammation (50.3% increase in apoptotic neutrophils and 30.6% increase in total neutrophils 24 h following zymosan administration in G2A(-/-) mice). Thus, CD36 is required for timely removal of apoptotic cells in the context of lung injury and modulates subsequent inflammatory and fibrotic processes relevant to fibrotic lung disease.
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Affiliation(s)
- Brian W Parks
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA
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28
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Li XY, Kong LX, Li J, He HX, Zhou YD. Kaempferol suppresses lipid accumulation in macrophages through the downregulation of cluster of differentiation 36 and the upregulation of scavenger receptor class B type I and ATP-binding cassette transporters A1 and G1. Int J Mol Med 2012; 31:331-8. [PMID: 23232972 DOI: 10.3892/ijmm.2012.1204] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2012] [Accepted: 10/22/2012] [Indexed: 12/17/2022] Open
Abstract
The accumulation of foam cells in atherosclerotic lesions is a hallmark of early-stage atherosclerosis. Kaempferol has been shown to inhibit oxidized low-density lipoprotein (oxLDL) uptake by macrophages; however, the underlying molecular mechanisms are not yet fully investigated. In this study, we shown that treatment with kaempferol markedly suppresses oxLDL-induced macrophage foam cell formation, which occurs due to a decrease in lipid accumulation and an increase in cholesterol efflux from THP-1-derived macrophages. Additionally, the kaempferol treatment of macrophages led to the downregulation of cluster of differentiation 36 (CD36) protein levels, the upregulation of ATP-binding cassette (ABC) transporter A1 (ABCA1), scavenger receptor class B type I (SR-BI) and ABCG1 protein levels, while no effects on scavenger receptor A (SR-A) expression were observed. Kaempferol had similar effects on the mRNA and protein expression of ABCA1, SR-BI, SR-A, CD36 and ABCG1. The reduced CD36 expression following kaempferol treatment involved the inhibition of c-Jun-activator protein-1 (AP-1) nuclear translocation. The inhibition of AP-1 using the inhibitor, SP600125, confirmed this involvement, as the AP-1 inhibition significantly augmented the kaempferol-induced reduction in CD36 expression. Accordingly, the kaempferol-mediated suppression of lipid accumulation in macrophages was also augmented by SP600125. The increased expression of ABCA1, SR-BI and ABCG1 following kaempferol treatment was accompanied by the enhanced protein expression of heme oxygenase-1 (HO-1). This increase was reversed following the knockdown of the HO-1 gene using small hairpin RNA (shRNA). Moreover, the kaempferol-mediated attenuation of lipid accumulation and the promotion of cholesterol efflux was also inhibited by HO-1 shRNA. In conclusion, the c-Jun-AP‑1-dependent downregulation of CD36 and the HO-1-dependent upregulation of ABCG1, SR-BI and ABCA1 may mediate the beneficial effects of kaempferol on foam cell formation.
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Affiliation(s)
- Xiu-Ying Li
- Department of Pharmacy, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400010, P.R. China
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29
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Turner WW, Hartvigsen K, Boullier A, Montano EN, Witztum JL, VanNieuwenhze MS. Design and synthesis of a stable oxidized phospholipid mimic with specific binding recognition for macrophage scavenger receptors. J Med Chem 2012; 55:8178-82. [PMID: 22934615 DOI: 10.1021/jm300685s] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Macrophage scavenger receptors appear to play a major role in the clearance of oxidized phospholipid (OxPL) products. Discrete peptide-phospholipid conjugates with the phosphatidylcholine headgroup have been shown to exhibit binding affinity for these receptors. We report the preparation of a water-soluble, stable peptide-phospholipid conjugate (9) that possesses the necessary physical properties to enable more detailed study of the role(s) of OxPL in metabolic disease.
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Affiliation(s)
- William W Turner
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102, USA
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Kim E, Febbraio M, Bao Y, Tolhurst AT, Epstein JM, Cho S. CD36 in the periphery and brain synergizes in stroke injury in hyperlipidemia. Ann Neurol 2012; 71:753-64. [PMID: 22718544 DOI: 10.1002/ana.23569] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVE Hyperlipidemia exacerbates ischemic stroke outcome and increases CD36 expression in the postischemic brain as well as in peripheral monocytes/macrophages. By exchanging bone marrow-derived cells between CD36-expressing and CD36-deficient mice, this study investigates the contribution of peripheral CD36 in comparison with that of brain CD36 to stroke pathology in hyperlipidemia. METHODS Following bone marrow transplantation, mice were fed a high-fat diet for 11 weeks and then subjected to ischemic stroke. Stroke outcome, expression of brain CD36, monocyte chemoattractant protein-1 (MCP-1), CCR2, and plasma MCP-1 levels were determined at 3 days postischemia. CD36 and CCR2 expression were also determined in splenocytes incubated with serum obtained from CD36-expressing or CD36-deficient mice. RESULTS Infiltrating immune cells from the periphery are the major source of CD36 in the postischemic brain and contribute to stroke-induced brain injury. This CD36 effect was dependent on the modulation of MCP-1 and CCR2 expression in peripheral immune cells as well as CD36-expressing cells in the host brain. INTERPRETATION This study demonstrates that CD36 expressed in the periphery and brain synergize in ischemic brain injury through regulation of the MCP-1/CCR2 chemokine axis in hyperlipidemic conditions.
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Affiliation(s)
- Eunhee Kim
- Burke-Cornell Medical Research Institute, White Plains, NY
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Chen CY, Ching LC, Liao YJ, Yu YB, Tsou CY, Shyue SK, Chen YMA, Lee TS. Deficiency of glycine N-methyltransferase aggravates atherosclerosis in apolipoprotein E-null mice. Mol Med 2012; 18:744-52. [PMID: 22415010 DOI: 10.2119/molmed.2011.00396] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Accepted: 03/07/2012] [Indexed: 12/22/2022] Open
Abstract
The mechanism underlying the dysregulation of cholesterol metabolism and inflammation in atherogenesis is not understood fully. Glycine N-methyltransferase (GNMT) has been implicated in hepatic lipid metabolism and the pathogenesis of liver diseases. However, little is known about the significance of GNMT in atherosclerosis. We showed the predominant expression of GNMT in foamy macrophages of mouse atherosclerotic aortas. Genetic deletion of GNMT exacerbated the hyperlipidemia, inflammation and development of atherosclerosis in apolipoprotein E-deficient mice. In addition, ablation of GNMT in macrophages aggravated oxidized low-density lipoprotein-mediated cholesterol accumulation in macrophage foam cells by downregulating the expression of reverse cholesterol transporters including ATP-binding cassette transporters-A1 and G1 and scavenger receptor BI. Furthermore, tumor necrosis factor-α-induced inflammatory response was promoted in GNMT-null macrophages. Collectively, our data suggest that GNMT is a crucial regulator in cholesterol metabolism and in inflammation, and contributes to the pathogenesis of atherosclerosis. This finding may reveal a potential therapeutic target for atherosclerosis.
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Affiliation(s)
- Chien-Yu Chen
- Department of Physiology, School of Medicine, National Yang-Ming University, Taipei, Taiwan
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32
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Boyle JJ, Christou I, Iqbal MB, Nguyen AT, Leung VWY, Evans PC, Liu Y, Johns M, Kirkham P, Haskard DO. Solid-phase immunoglobulins IgG and IgM activate macrophages with solid-phase IgM acting via a novel scavenger receptor a pathway. THE AMERICAN JOURNAL OF PATHOLOGY 2012; 181:347-61. [PMID: 22658487 DOI: 10.1016/j.ajpath.2012.03.040] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2011] [Revised: 02/26/2012] [Accepted: 03/20/2012] [Indexed: 01/21/2023]
Abstract
IgG may accelerate atherosclerosis via ligation of proinflammatory Fcγ receptors; however, IgM is unable to ligate FcγR and is often considered vasculoprotective. IgM aggravates ischemia-reperfusion injury, and solid-phase deposits of pure IgM, as seen with IgM-secreting neoplasms, are well known clinically to provoke vascular inflammation. We therefore examined the molecular mechanisms by which immunoglobulins can aggravate vascular inflammation, such as in atherosclerosis. We compared the ability of fluid- and solid-phase immunoglobulins to activate macrophages. Solid-phase immunoglobulins initiated prothrombotic and proinflammatory functions in human macrophages, including NF-κB p65 activation, H(2)O(2) secretion, macrophage-induced apoptosis, and tissue factor expression. Responses to solid-phase IgG (but not to IgM) were blocked by neutralizing antibodies to CD16 (FcγRIII), consistent with its known role. Macrophages from mice deficient in macrophage scavenger receptor A (SR-A; CD204) had absent IgM binding and no activation by solid-phase IgM. RNA interference-mediated knockdown of SR-A in human macrophages suppressed activation by solid-phase IgM. IgM binding to SR-A was demonstrated by both co-immunoprecipitation studies and the binding of fluorescently labeled IgM to SR-A-transfected cells. Immunoglobulins on solid-phase particles around macrophages were found in human plaques, increased in ruptured plaques compared with stable ones. These observations indicate that solid-phase IgM and IgG can activate macrophages and destabilize vulnerable plaques. Solid-phase IgM activates macrophages via a novel SR-A pathway.
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Affiliation(s)
- Joseph J Boyle
- Vascular Sciences Section, National Heart and Lung Institute, Imperial College London, London, United Kingdom.
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Bao Y, Wang L, Xu Y, Yang Y, Wang L, Si S, Cho S, Hong B. Salvianolic acid B inhibits macrophage uptake of modified low density lipoprotein (mLDL) in a scavenger receptor CD36-dependent manner. Atherosclerosis 2012; 223:152-9. [PMID: 22658257 DOI: 10.1016/j.atherosclerosis.2012.05.006] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Revised: 03/06/2012] [Accepted: 05/05/2012] [Indexed: 01/17/2023]
Abstract
CD36, a class B scavenger receptor, has been implicated in the pathogenesis of a host of vascular inflammatory diseases. Through a high-throughput screening (HTS) assay for CD36 antagonist, we previously identified salvianolic acid B (SAB), a hydrophilic component derived from the herb Danshen, as a potential candidate. Danshen, the dried roots of Salvia miltiorrhiza, has been widely used in China for the prevention and treatment of atherosclerosis-related disorders. Previous studies showed that SAB acted as an anti-oxidant by preventing lipid peroxidation and oxidized LDL (oxLDL) formation. The present study was to investigate the specificity and efficacy of SAB in the inhibition of CD36-mediated lipid uptake. SAB reduced modified LDL (mLDL) uptake in a dose-dependent manner in phorbol-12-myristate-13-acetate (PMA)-stimulated THP-1 and RAW 264.7 cells. In the CD36 silenced THP-1 cells, SAB had no effect in reducing mLDL uptake, whereas its overexpression in CHO cells reinstates the effect, indicating a specific involvement of SAB in antagonizing the CD36's function. Surface plasmon resonance (SPR) analysis revealed a direct binding of SAB to CD36 with a high affinity (K(D) = 3.74 μM), confirming physical interactions of SAB with the receptor. Additionally, SAB reduced oxLDL-induced CD36 gene expression in the cultured cell lines and primary macrophages. In ApoE KO mice fed a high fat diet, SAB reduced CD36 gene expression and lipid uptake in macrophages, showing its ability to antagonize CD36 pathways in vivo. These results demonstrate that SAB is an effective CD36 antagonist and suggest SAB as a potential anti-atherosclerotic agent.
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Affiliation(s)
- Yi Bao
- Key Laboratory of Biotechnology of Antibiotics of Ministry of Health, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
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Chen CY, Shyue SK, Ching LC, Su KH, Wu YL, Kou YR, Chiang AN, Pan CC, Lee TS. Wogonin promotes cholesterol efflux by increasing protein phosphatase 2B-dependent dephosphorylation at ATP-binding cassette transporter-A1 in macrophages. J Nutr Biochem 2011; 22:1015-21. [DOI: 10.1016/j.jnutbio.2010.08.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Revised: 08/16/2010] [Accepted: 08/31/2010] [Indexed: 11/26/2022]
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Lin CY, Lee TS, Chen CC, Chang CA, Lin YJ, Hsu YP, Ho LT. Endothelin-1 exacerbates lipid accumulation by increasing the protein degradation of the ATP-binding cassette transporter G1 in macrophages. J Cell Physiol 2011; 226:2198-205. [PMID: 21520072 DOI: 10.1002/jcp.22556] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Endothelin-1 (ET-1), a potent proatherogenic vasoconstrictive peptide, is known to promote macrophage foam cell formation via mechanisms that are not fully understood. Excessive lipid accumulation in macrophages is a major hallmark during the early stages of atherosclerotic lesions. Cholesterol homeostasis is tightly regulated by scavenger receptors (SRs) and ATP-binding cassette (ABC) transporters during the transformation of macrophage foam cells. The aim of this study was to investigate the possible mechanisms by which ET-1 affects lipid accumulation in macrophages. Our results demonstrate that oxidized low-density lipoprotein (oxLDL) treatment increases lipid accumulation in rat bone marrow-derived macrophages. Combined treatment with ET-1 and oxLDL significantly exacerbated lipid accumulation in macrophages as compared to treatment with oxLDL alone. The results of Western blotting show that ET-1 markedly decreased the ABCG1 levels via ET type A and B receptors and activation of the phosphatidylinositol 3-kinase pathway; however, ET-1 had no effect on the protein expression of CD36, SR-BI, SR-A, or ABCA1. In addition, real-time PCR analysis showed that ET-1 treatment did not affect ABCG1 mRNA expression. We also found that ET-1 decreases ABCG1 possibly due to the enhancement of the proteosome/calpain pathway-dependent degradation of ABCG1. Moreover, ET-1 significantly reduced the efficiency of the cholesterol efflux in macrophages. Taken together, these findings suggest that ET-1 may impair cholesterol efflux and further exacerbate lipid accumulation during the transformation of macrophage foam cells.
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Affiliation(s)
- Chun-Yueh Lin
- Institute of Physiology, National Yang-Ming University, Taipei, Taiwan
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36
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Abstract
Vascular inflammation is associated with and in large part driven by changes in the leukocyte compartment of the vessel wall. Here, we focus on monocyte influx during atherosclerosis, the most common form of vascular inflammation. Although the arterial wall contains a large number of resident macrophages and some resident dendritic cells, atherosclerosis drives a rapid influx of inflammatory monocytes (Ly-6C(+) in mice) and other monocytes (Ly-6C(-) in mice, also known as patrolling monocytes). Once in the vessel wall, Ly-6C(+) monocytes differentiate to a phenotype consistent with inflammatory macrophages and inflammatory dendritic cells. The phenotype of these cells is modulated by lipid uptake, Toll-like receptor ligands, hematopoietic growth factors, cytokines, and chemokines. In addition to newly recruited macrophages, it is likely that resident macrophages also change their phenotype. Monocyte-derived inflammatory macrophages have a short half-life. After undergoing apoptosis, they may be taken up by surrounding macrophages or, if the phagocytic capacity is overwhelmed, can undergo secondary necrosis, a key event in forming the necrotic core of atherosclerotic lesions. In this review, we discuss these and other processes associated with monocytic cell dynamics in the vascular wall and their role in the initiation and progression of atherosclerosis.
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Affiliation(s)
- Klaus Ley
- Division of Inflammation Biology, La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037, USA.
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Miller YI, Choi SH, Wiesner P, Fang L, Harkewicz R, Hartvigsen K, Boullier A, Gonen A, Diehl CJ, Que X, Montano E, Shaw PX, Tsimikas S, Binder CJ, Witztum JL. Oxidation-specific epitopes are danger-associated molecular patterns recognized by pattern recognition receptors of innate immunity. Circ Res 2011; 108:235-48. [PMID: 21252151 DOI: 10.1161/circresaha.110.223875] [Citation(s) in RCA: 473] [Impact Index Per Article: 36.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Oxidation reactions are vital parts of metabolism and signal transduction. However, they also produce reactive oxygen species, which damage lipids, proteins and DNA, generating "oxidation-specific" epitopes. In this review, we discuss the hypothesis that such common oxidation-specific epitopes are a major target of innate immunity, recognized by a variety of "pattern recognition receptors" (PRRs). By analogy with microbial "pathogen-associated molecular patterns" (PAMPs), we postulate that host-derived, oxidation-specific epitopes can be considered to represent "danger (or damage)-associated molecular patterns" (DAMPs). We also argue that oxidation-specific epitopes present on apoptotic cells and their cellular debris provided the primary evolutionary pressure for the selection of such PRRs. Furthermore, because many PAMPs on microbes share molecular identity and/or mimicry with oxidation-specific epitopes, such PAMPs provide a strong secondary selecting pressure for the same set of oxidation-specific PRRs as well. Because lipid peroxidation is ubiquitous and a major component of the inflammatory state associated with atherosclerosis, the understanding that oxidation-specific epitopes are DAMPs, and thus the target of multiple arcs of innate immunity, provides novel insights into the pathogenesis of atherosclerosis. As examples, we show that both cellular and soluble PRRs, such as CD36, toll-like receptor-4, natural antibodies, and C-reactive protein recognize common oxidation-specific DAMPs, such as oxidized phospholipids and oxidized cholesteryl esters, and mediate a variety of immune responses, from expression of proinflammatory genes to excessive intracellular lipoprotein accumulation to atheroprotective humoral immunity. These insights may lead to improved understanding of inflammation and atherogenesis and suggest new approaches to diagnosis and therapy.
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Affiliation(s)
- Yury I Miller
- Department of Medicine-MC0682, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
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Faulin TDES, Cavalcante MF, Abdalla DSP. Role of electronegative LDL and its associated antibodies in the pathogenesis of atherosclerosis. ACTA ACUST UNITED AC 2010. [DOI: 10.2217/clp.10.52] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Silencing of either SR-A or CD36 reduces atherosclerosis in hyperlipidaemic mice and reveals reciprocal upregulation of these receptors. Cardiovasc Res 2010; 88:530-8. [DOI: 10.1093/cvr/cvq235] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Mandosi E, Fallarino M, Gatti A, Carnovale A, Rossetti M, Lococo E, Buchetti B, Filetti S, Lenti L, Morano S. Atorvastatin downregulates monocyte CD36 expression, nuclear NFkappaB and TNFalpha levels in type 2 diabetes. J Atheroscler Thromb 2010; 17:539-45. [PMID: 20134099 DOI: 10.5551/jat.2956] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
AIM Type 2 diabetes increases the risk for cardiovascular disease, and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) reduce cardiovascular events in these patients. The benefits of statin therapy cannot be explained only by the lipid-lowering effect. The aim of this study was to test the effect of atorvastatin therapy on CD36 scavenger receptor expression, nuclear factor-kappaB (NFkappaB) levels and markers of inflammation (C-reactive protein, CRP, Tumor Necrosis Factor-alpha, TNF-alpha) in circulating monocytes from diabetic patients. METHODS Twenty-two type 2 diabetic patients were treated for 8 weeks with atorvastatin (20 mg/day). At baseline and after treatment a blood sample was collected for measurement of glucose, lipid profile (total cholesterol, HDL, LDL cholesterol, triglycerides), glycated hemoglobin (HbA1c), CRP and for isolation of monocytes. RESULTS Atorvastatin decreased total (p<0.0001) and LDL (p<0.01), and incresased HDL choles-terol (p<0.02). CD36 surface protein expression (anti-CD36 fluorescein isothiocyanate-FITC) was reduced in circulating monocytes after atorvastatin therapy (p<0.02) while immunoblot analysis showed reduced nuclear and increased cytoplasm NFkappaB levels (p<0.05). Finally, TNFalpha production in lipopolysaccharide-activated monocytes from patients treated with atorvastatin was reduced (p<0.05). CONCLUSION These results suggest that atorvastatin therapy, beside lowering serum cholesterol levels, could exert anti-atherogenic and anti-inflammatory effects in type 2 diabetic patients.
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Affiliation(s)
- Elisabetta Mandosi
- Department of Clinical Sciences, Sapienza University of Rome, Rome, Italy
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Abstract
Excessive lipid accumulation in macrophages, also known as foam cell formation, is a key process during the development of atherosclerosis, leading to vascular inflammation and plaque growth. Recent studies have identified a new mechanism of macrophage lipid accumulation in which minimally oxidized low-density lipoprotein (mmLDL) and its active components, polyoxygenated cholesteryl ester hydroperoxides, are involved in endogenous activation of toll-like receptor-4 (TLR4), leading to recruitment of spleen tyrosine kinase (Syk), robust cytoskeletal rearrangements and macropinocytosis. In hyperlipidemic environments, mmLDL-induced, TLR4- and Syk-dependent macropinocytosis leads to substantial lipid accumulation in macrophages and monocytes, which may constitute an important mechanism of foam cell formation in atherosclerosis. A novel hypercholesterolemic zebrafish model of early stages of atherosclerosis was used to demonstrate that the TLR4 deficiency significantly reduces the in vivo rate of macrophage lipid accumulation in vascular lesions.
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Lu KY, Ching LC, Su KH, Yu YB, Kou YR, Hsiao SH, Huang YC, Chen CY, Cheng LC, Pan CC, Lee TS. Erythropoietin suppresses the formation of macrophage foam cells: role of liver X receptor alpha. Circulation 2010; 121:1828-37. [PMID: 20385932 DOI: 10.1161/circulationaha.109.876839] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND In addition to the hematopoietic effect of erythropoietin, increasing evidence suggests that erythropoietin also exerts protective effects for cardiovascular diseases. However, the role of erythropoietin and its underlying mechanism in macrophage foam cell formation are poorly understood. METHODS AND RESULTS Compared with wild-type specimens, erythropoietin was increased in atherosclerotic aortas of apolipoprotein E-deficient (apoE(-/-)) mice, mainly in the macrophage foam cells of the lesions. Erythropoietin levels in culture medium and macrophages were significantly elevated in response to oxidized low-density lipoprotein in a dose-dependent manner. Furthermore, erythropoietin markedly attenuated lipid accumulation in oxidized low-density lipoprotein-treated macrophages, a result that was due to an increase in cholesterol efflux. Erythropoietin treatment significantly increased ATP-binding cassette transporters (ABC) A1 and ABCG1 mRNA and protein levels without affecting protein expression of scavenger receptors, including scavenger receptor-A, CD36, and scavenger receptor-BI. The upregulation of ABCA1 and ABCG1 by erythropoietin resulted from liver X receptor alpha activation, which was confirmed by its prevention on expression of ABCA1 and ABCG1 after pharmacological or small interfering RNA inhibition of liver X receptor alpha. Moreover, the erythropoietin-mediated attenuation on lipid accumulation was abolished by such inhibition. Finally, reduced lipid accumulation and marked increase in ABCA1 and ABCG1 were demonstrated in erythropoietin-overexpressed macrophages. CONCLUSIONS Our data suggest that erythropoietin suppresses foam cell formation via the liver X receptor alpha-dependent upregulation of ABCA1 and ABCG1.
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Affiliation(s)
- Kuo-Yun Lu
- Department of Physiology, National Yang-Ming University, Taipei 112, Taiwan.
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Miller YI, Choi SH, Fang L, Tsimikas S. Lipoprotein modification and macrophage uptake: role of pathologic cholesterol transport in atherogenesis. Subcell Biochem 2010; 51:229-51. [PMID: 20213546 DOI: 10.1007/978-90-481-8622-8_8] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Low-density lipoprotein (LDL) is a major extracellular carrier of cholesterol and, as such, plays important physiologic roles in cellular function and regulation of metabolic pathways. However, under pathologic conditions of hyperlipidemia, oxidative stress and/or genetic disorders, specific components of LDL become oxidized or otherwise modified, and the transport of cholesterol by modified LDL is diverted from its physiologic targets toward excessive cholesterol accumulation in macrophages and the formation of macrophage "foam" cells in the vascular wall. This pathologic deposition of modified lipoproteins and the attendant pro-inflammatory reactions in the artery wall lead to the development of atherosclerotic lesions. Continued accumulation of immunogenic modified lipoproteins and a pro-inflammatory milieu result in the progression of atherosclerotic lesions, which may obstruct the arterial lumen and/or eventually rupture and thrombose, causing myocardial infarction or stroke. In this review, we survey mechanisms of LDL modification and macrophage lipoprotein uptake, including results of recent in vivo experiments, and discuss unresolved problems and controversial issues in this growing field. Future directions in studying foam cell formation may include introducing novel animal models, such as hypercholesterolemic zebrafish, enabling dynamic in vivo observation of macrophage lipid uptake.
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Affiliation(s)
- Yury I Miller
- Department of Medicine, University of California, San Diego, La Jolla, CA 92037-0682, USA.
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Montoya D, Cruz D, Teles RMB, Lee DJ, Ochoa MT, Krutzik SR, Chun R, Schenk M, Zhang X, Ferguson BG, Burdick AE, Sarno EN, Rea TH, Hewison M, Adams JS, Cheng G, Modlin RL. Divergence of macrophage phagocytic and antimicrobial programs in leprosy. Cell Host Microbe 2009; 6:343-53. [PMID: 19837374 DOI: 10.1016/j.chom.2009.09.002] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2009] [Revised: 08/06/2009] [Accepted: 08/31/2009] [Indexed: 12/15/2022]
Abstract
Effective innate immunity against many microbial pathogens requires macrophage programs that upregulate phagocytosis and direct antimicrobial pathways, two functions generally assumed to be coordinately regulated. We investigated the regulation of these key functions in human blood-derived macrophages. Interleukin-10 (IL-10) induced the phagocytic pathway, including the C-type lectin CD209 and scavenger receptors, resulting in phagocytosis of mycobacteria and oxidized low-density lipoprotein. IL-15 induced the vitamin D-dependent antimicrobial pathway and CD209, yet the cells were less phagocytic. The differential regulation of macrophage functional programs was confirmed by analysis of leprosy lesions: the macrophage phagocytosis pathway was prominent in the clinically progressive, multibacillary form of the disease, whereas the vitamin D-dependent antimicrobial pathway predominated in the self-limited form and in patients undergoing reversal reactions from the multibacillary to the self-limited form. These data indicate that macrophage programs for phagocytosis and antimicrobial responses are distinct and differentially regulated in innate immunity to bacterial infections.
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Affiliation(s)
- Dennis Montoya
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095, USA
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Bengtsson D, Björkbacka H. Atherosclerosis: cell biology and lipoproteins. Curr Opin Lipidol 2009; 20:355-6. [PMID: 19584595 DOI: 10.1097/mol.0b013e32832dd56d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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46
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TR4 nuclear receptor functions as a fatty acid sensor to modulate CD36 expression and foam cell formation. Proc Natl Acad Sci U S A 2009; 106:13353-8. [PMID: 19666541 DOI: 10.1073/pnas.0905724106] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Testicular orphan nuclear receptor 4 (TR4) is an orphan member of the nuclear receptor superfamily with diverse physiological functions. Using TR4 knockout (TR4(-/-)) mice to study its function in cardiovascular diseases, we found reduced cluster of differentiation (CD)36 expression with reduced foam cell formation in TR4(-/-) mice. Mechanistic dissection suggests that TR4 induces CD36 protein and mRNA expression via a transcriptional regulation. Interestingly, we found this TR4-mediated CD36 transactivation can be further enhanced by polyunsaturated fatty acids (PUFAs), such as omega-3 and -6 fatty acids, and their metabolites such as 15-hydroxyeico-satetraonic acid (15-HETE) and 13-hydroxy octa-deca dieonic acid (13-HODE) and thiazolidinedione (TZD)-rosiglitazone. Both electrophoretic mobility shift assays (EMSA) and chromatin immunoprecipitation (ChIP) assays demonstrate that TR4 binds to the TR4 response element located on the CD36 5'-promoter region for the induction of CD36 expression. Stably transfected TR4-siRNA or functional TR4 cDNA in the RAW264.7 macrophage cells resulted in either decreased or increased CD36 expression with decreased or increased foam cell formation. Restoring functional CD36 cDNA in the TR4 knockdown macrophage cells reversed the decreased foam cell formation. Together, these results reveal an important signaling pathway controlling CD36-mediated foam cell formation/cardiovascular diseases, and findings that TR4 transactivation can be activated via its ligands/activators, such as PUFA metabolites and TZD, may provide a platform to screen new drug(s) to battle the metabolism syndrome, diabetes, and cardiovascular diseases.
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Choi SH, Harkewicz R, Lee JH, Boullier A, Almazan F, Li AC, Witztum JL, Bae YS, Miller YI. Lipoprotein accumulation in macrophages via toll-like receptor-4-dependent fluid phase uptake. Circ Res 2009; 104:1355-63. [PMID: 19461045 DOI: 10.1161/circresaha.108.192880] [Citation(s) in RCA: 176] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Toll-like receptor (TLR)4 recognizes microbial pathogens, such as lipopolysaccharide, and mediates lipopolysaccharide-induced proinflammatory cytokine secretion, as well as microbial uptake by macrophages. In addition to exogenous pathogens, TLR4 recognizes modified self, such as minimally oxidized low-density lipoprotein (mmLDL). Here we report that mmLDL and its active components, cholesteryl ester hydroperoxides, induce TLR4-dependent fluid phase uptake typical of macropinocytosis. We show that mmLDL induced recruitment of spleen tyrosine kinase (Syk) to a TLR4 signaling complex, TLR4 phosphorylation, activation of a Vav1-Ras-Raf-MEK-ERK1/2 signaling cascade, phosphorylation of paxillin, and activation of Rac, Cdc42, and Rho. These mmLDL-induced and TLR4- and Syk-dependent signaling events and cytoskeletal rearrangements lead to enhanced uptake of small molecules, dextran, and, most importantly, both native and oxidized LDL, resulting in intracellular lipid accumulation. An intravenous injection of fluorescently labeled mmLDL in wild-type mice resulted in its rapid accumulation in circulating monocytes, which was significantly attenuated in TLR4-deficient mice. These data describe a novel mechanism leading to enhanced lipoprotein uptake in macrophages that would contribute to foam cell formation and atherosclerosis. These data also suggest that cholesteryl ester hydroperoxides are an endogenous ligand for TLR4. Because TLR4 is highly expressed on the surface of circulating monocytes in patients with chronic inflammatory conditions, and cholesteryl ester hydroperoxides are present in plasma, lipid uptake by monocytes in circulation may contribute to the pathological roles of monocytes in chronic inflammatory diseases.
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Affiliation(s)
- Soo-Ho Choi
- Department of Medicine, University of California at San Diego, 9500 Gilman Dr, La Jolla, CA 92093, USA
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48
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Affiliation(s)
- Linda K Curtiss
- Department of Immunology and Microbial Sciences, Scripps Research Institute, La Jolla, CA, USA
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Modes of defining atherosclerosis in mouse models: relative merits and evolving standards. Methods Mol Biol 2009; 573:1-15. [PMID: 19763919 DOI: 10.1007/978-1-60761-247-6_1] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Mouse models have become the most common model for defining mechanisms of atherosclerotic disease. Many genetic manipulations have enabled the development of atherosclerosis in mice due to either endogenous or diet-induced hypercholesterolemia. This availability of lesion-susceptible mice has facilitated many studies using pharmacological and genetic approaches. Unfortunately, this expansive literature on mouse atherosclerosis has generated many contradictions on the role of specific pathways. A contributor to these inconsistencies may be the multiple modes in which atherosclerosis is evaluated. Also, for each specific technique, there are no consistent standards applied to the measurements. This chapter will discuss the imaging, biochemical, and compositional modes of evaluating atherosclerosis with suggestions for standard execution of these techniques.
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Dushkin MI, Khoshchenko OM, Posokhova EN, Schvarts YS. Agonists of PPAR-alpha, PPAR-gamma, and RXR inhibit the formation of foam cells from macrophages in mice with inflammation. Bull Exp Biol Med 2008; 144:713-6. [PMID: 18683504 DOI: 10.1007/s10517-007-0413-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We studied the effect of agonists of peroxisome proliferator-activated receptors alpha and gamma and retinoid X receptors on the concentration and synthesis of lipids in macrophages of C57B1/6 mice with inflammation induced by intraperitoneal injection of zymosan. We revealed a significant increase in [1-14C]oleate incorporation into cholesterol esters and triglycerides, increase in the content of free cholesterol, cholesterol esters, and triglycerides, and formation of oil red-stained lipid inclusions in peritoneal macrophages 24 h after administration of zymosan in a dose of 50 mg/kg. Treatment with agonists of retinoid X receptors and peroxisome proliferator-activated receptors alpha and gamma 30 min before and 12 h after zymosan injection decreased the synthesis of triglycerides and cholesterol esters, reduced the content of free cholesterol, cholesterol esters, and triglycerides in macrophages, and prevented the formation of cytoplasmic lipid inclusions in macrophage-derived foam cells during inflammation.
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Affiliation(s)
- M I Dushkin
- Institute of Clinical Immunology, Siberian Division of the Russian Academy of Medical Sciences, Novosibirsk.
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