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Macrophages bind LDL using heparan sulfate and the perlecan protein core. J Biol Chem 2021; 296:100520. [PMID: 33684447 PMCID: PMC8027565 DOI: 10.1016/j.jbc.2021.100520] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 03/03/2021] [Accepted: 03/04/2021] [Indexed: 12/25/2022] Open
Abstract
The retention of low-density lipoprotein (LDL) is a key process in the pathogenesis of atherosclerosis and largely mediated via smooth-muscle cell-derived extracellular proteoglycans including the glycosaminoglycan chains. Macrophages can also internalize lipids via complexes with proteoglycans. However, the role of polarized macrophage-derived proteoglycans in binding LDL is unknown and important to advance our understanding of the pathogenesis of atherosclerosis. We therefore examined the identity of proteoglycans, including the pendent glycosaminoglycans, produced by polarized macrophages to gain insight into the molecular basis for LDL binding. Using the quartz crystal microbalance with dissipation monitoring technique, we established that classically activated macrophage (M1)- and alternatively activated macrophage (M2)-derived proteoglycans bind LDL via both the protein core and heparan sulfate (HS) in vitro. Among the proteoglycans secreted by macrophages, we found perlecan was the major protein core that bound LDL. In addition, we identified perlecan in the necrotic core as well as the fibrous cap of advanced human atherosclerotic lesions in the same regions as HS and colocalized with M2 macrophages, suggesting a functional role in lipid retention in vivo. These findings suggest that macrophages may contribute to LDL retention in the plaque by the production of proteoglycans; however, their contribution likely depends on both their phenotype within the plaque and the presence of enzymes, such as heparanase, that alter the secreted protein structure.
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Pariente A, Peláez R, Pérez-Sala Á, Larráyoz IM. Inflammatory and cell death mechanisms induced by 7-ketocholesterol in the retina. Implications for age-related macular degeneration. Exp Eye Res 2019; 187:107746. [DOI: 10.1016/j.exer.2019.107746] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 07/25/2019] [Accepted: 07/25/2019] [Indexed: 12/16/2022]
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Lyssenko NN, Haider N, Picataggi A, Cipollari E, Jiao W, Phillips MC, Rader DJ, Chavali VRM. Directional ABCA1-mediated cholesterol efflux and apoB-lipoprotein secretion in the retinal pigment epithelium. J Lipid Res 2018; 59:1927-1939. [PMID: 30076206 DOI: 10.1194/jlr.m087361] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 06/21/2018] [Indexed: 12/15/2022] Open
Abstract
Cholesterol-containing soft drusen and subretinal drusenoid deposits (SDDs) occur at the basolateral and apical side of the retinal pigment epithelium (RPE), respectively, in the chorioretina and are independent risk factors for late age-related macular degeneration (AMD). Cholesterol in these deposits could originate from the RPE as nascent HDL or apoB-lipoprotein. We characterized cholesterol efflux and apoB-lipoprotein secretion in RPE cells. Human RPE cells, ARPE-19, formed nascent HDL that was similar in physicochemical properties to nascent HDL formed by other cell types. In highly polarized primary human fetal RPE (phfRPE) monolayers grown in low-lipid conditions, cholesterol efflux to HDL was moderately directional to the apical side and much stronger than ABCA1-mediated efflux to apoA-I at both sides; ABCA1-mediated efflux was weak and equivalent between the two sides. Feeding phfRPE monolayers with oxidized or acetylated LDL increased intracellular levels of free and esterified cholesterol and substantially raised ABCA1-mediated cholesterol efflux at the apical side. phfRPE monolayers secreted apoB-lipoprotein preferentially to the apical side in low-lipid and oxidized LDL-feeding conditions. These findings together with evidence from human genetics and AMD pathology suggest that RPE-generated HDL may contribute lipid to SDDs.
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Affiliation(s)
- Nicholas N Lyssenko
- Division of Translational Medicine and Human Genetics, Department of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Naqi Haider
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA
| | - Antonino Picataggi
- Division of Translational Medicine and Human Genetics, Department of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Eleonora Cipollari
- Division of Translational Medicine and Human Genetics, Department of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Wanzhen Jiao
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA
| | - Michael C Phillips
- Division of Translational Medicine and Human Genetics, Department of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Daniel J Rader
- Division of Translational Medicine and Human Genetics, Department of Medicine, University of Pennsylvania, Philadelphia, PA.,Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
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Yang X, Li Y, Li Y, Ren X, Zhang X, Hu D, Gao Y, Xing Y, Shang H. Oxidative Stress-Mediated Atherosclerosis: Mechanisms and Therapies. Front Physiol 2017; 8:600. [PMID: 28878685 PMCID: PMC5572357 DOI: 10.3389/fphys.2017.00600] [Citation(s) in RCA: 262] [Impact Index Per Article: 37.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 08/03/2017] [Indexed: 12/14/2022] Open
Abstract
Atherogenesis, the formation of atherosclerotic plaques, is a complex process that involves several mechanisms, including endothelial dysfunction, neovascularization, vascular proliferation, apoptosis, matrix degradation, inflammation, and thrombosis. The pathogenesis and progression of atherosclerosis are explained differently by different scholars. One of the most common theories is the destruction of well-balanced homeostatic mechanisms, which incurs the oxidative stress. And oxidative stress is widely regarded as the redox status realized when an imbalance exists between antioxidant capability and activity species including reactive oxygen (ROS), nitrogen (RNS) and halogen species, non-radical as well as free radical species. This occurrence results in cell injury due to direct oxidation of cellular protein, lipid, and DNA or via cell death signaling pathways responsible for accelerating atherogenesis. This paper discusses inflammation, mitochondria, autophagy, apoptosis, and epigenetics as they induce oxidative stress in atherosclerosis, as well as various treatments for antioxidative stress that may prevent atherosclerosis.
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Affiliation(s)
- Xinyu Yang
- Guang'anmen Hospital, Chinese Academy of Chinese Medical SciencesBeijing, China.,Key Laboratory of Chinese Internal Medicine of the Ministry of Education, Dongzhimen Hospital, Beijing University of Chinese MedicineBeijing, China
| | - Yang Li
- Department of Cardiology, General Hospital of People's Liberation ArmyBeijing, China
| | - Yanda Li
- Guang'anmen Hospital, Chinese Academy of Chinese Medical SciencesBeijing, China
| | - Xiaomeng Ren
- Guang'anmen Hospital, Chinese Academy of Chinese Medical SciencesBeijing, China.,Key Laboratory of Chinese Internal Medicine of the Ministry of Education, Dongzhimen Hospital, Beijing University of Chinese MedicineBeijing, China
| | - Xiaoyu Zhang
- Key Laboratory of Chinese Internal Medicine of the Ministry of Education, Dongzhimen Hospital, Beijing University of Chinese MedicineBeijing, China
| | - Dan Hu
- Masonic Medical Research LaboratoryUtica, NY, United States
| | - Yonghong Gao
- Key Laboratory of Chinese Internal Medicine of the Ministry of Education, Dongzhimen Hospital, Beijing University of Chinese MedicineBeijing, China
| | - Yanwei Xing
- Guang'anmen Hospital, Chinese Academy of Chinese Medical SciencesBeijing, China
| | - Hongcai Shang
- Key Laboratory of Chinese Internal Medicine of the Ministry of Education, Dongzhimen Hospital, Beijing University of Chinese MedicineBeijing, China
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5
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Mechanism of inflammation in age-related macular degeneration: an up-to-date on genetic landmarks. Mediators Inflamm 2013; 2013:435607. [PMID: 24369445 PMCID: PMC3863457 DOI: 10.1155/2013/435607] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 09/28/2013] [Indexed: 12/13/2022] Open
Abstract
Age-related macular degeneration (AMD) is the most common cause of irreversible visual impairment among people over 50 years of age, accounting for up to 50% of all cases of legal blindness in Western countries. Although the aging represents the main determinant of AMD, it must be considered a multifaceted disease caused by interactions among environmental risk factors and genetic backgrounds. Mounting evidence and/or arguments document the crucial role of inflammation and immune-mediated processes in the pathogenesis of AMD. Proinflammatory effects secondary to chronic inflammation (e.g., alternative complement activation) and heterogeneous types of oxidative stress (e.g., impaired cholesterol homeostasis) can result in degenerative damages at the level of crucial macular structures, that is photoreceptors, retinal pigment epithelium, and Bruch's membrane. In the most recent years, the association of AMD with genes, directly or indirectly, involved in immunoinflammatory pathways is increasingly becoming an essential core for AMD knowledge. Starting from the key basic-research notions detectable at the root of AMD pathogenesis, the present up-to-date paper reviews the best-known and/or the most attractive genetic findings linked to the mechanisms of inflammation of this complex disease.
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NISHIKAWA Y, IBRAHIM HM, KAMEYAMA K, SHIGA I, HIASA J, XUAN X. Host Cholesterol Synthesis Contributes to Growth of Intracellular Toxoplasma gondii in Macrophages. J Vet Med Sci 2011; 73:633-9. [DOI: 10.1292/jvms.10-0496] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Yoshifumi NISHIKAWA
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine
| | - Hany M. IBRAHIM
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine
- Zoology Department, Faculty of Science, Minufiya University
| | - Kyohko KAMEYAMA
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine
| | - Ikumi SHIGA
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine
| | - Jun HIASA
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine
| | - Xuenan XUAN
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine
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Detection of oxysterols in oxidatively modified low density lipoprotein by MALDI-TOF MS. EUR J LIPID SCI TECH 2010. [DOI: 10.1002/ejlt.201000366] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Rodríguez IR, Larrayoz IM. Cholesterol oxidation in the retina: implications of 7KCh formation in chronic inflammation and age-related macular degeneration. J Lipid Res 2010; 51:2847-62. [PMID: 20567027 DOI: 10.1194/jlr.r004820] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
This review will discuss the formation and potential implications of 7-ketocholesterol (7KCh) in the retina. 7KCh is a proinflammatory oxysterol known to be present in high amounts in oxidized LDL deposits associated with atheromatous plaques. 7KCh is generated in situ in these lipoprotein deposits where it can accumulate and reach very high concentrations. In normal primate retina, 7KCh has been found associated with lipoprotein deposits in the choriocapillaris, Bruch's membrane, and the retinal pigment epithelium (RPE). In photodamaged rats, 7KCh has been found in the neural retina in areas of high mitochondrial content, ganglion cells, photoreceptor inner segments and synapses, and the RPE. Intermediates found by LCMS indicate 7KCh is formed via a free radical-mediated mechanism catalyzed by iron. 7KCh seems to activate several kinase signaling pathways that work via nuclear factor κB and cause the induction of vascular endothelial growth factor, interleukin (IL)-6, and IL-8. There seems to be little evidence of 7KCh metabolism in the retina, although some form of efflux mechanism may be active. The chronic mode of formation and the potent inflammatory properties of 7KCh indicate it may be an "age-related" risk factor in aging diseases such as atherosclerosis, Alzheimer's, and age-related macular degeneration.
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Affiliation(s)
- Ignacio R Rodríguez
- Mechanisms of Retinal Diseases Section, Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, Bethesda, MD 20892, USA.
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Larrayoz IM, Huang JD, Lee JW, Pascual I, Rodríguez IR. 7-ketocholesterol-induced inflammation: involvement of multiple kinase signaling pathways via NFκB but independently of reactive oxygen species formation. Invest Ophthalmol Vis Sci 2010; 51:4942-55. [PMID: 20554621 DOI: 10.1167/iovs.09-4854] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE 7-Ketocholesterol (7KCh) accumulates in oxidized lipoprotein deposits and is known to be involved in macrophage foam cell formation and atherosclerosis. 7-KCh is present in the primate retina and is associated with oxidized lipoprotein deposits located in the choriocapillaris, Bruch's membrane, and retinal pigment epithelium (RPE). 7-KCh can also be formed in the retina as a consequence of light-induced iron release. The purpose of this study was to examine the signaling pathways involved in the 7KCh-mediated inflammatory response focusing on three cytokines, VEGF, IL-6, and IL-8. METHODS ARPE-19 cells were treated with 7KCh solubilized in hydroxypropyl-β-cyclodextrin. Cytokines were quantified by qRT-PCR (mRNA) and ELISA (protein) using commercially available products. NFκB activation was determined by IκBα mRNA induction. RESULTS Treatment of ARPE-19 cells with 15 μM 7KCh markedly induced the expression of VEGF, IL-6, and IL-8. No increase in NOX-4 expression or ROS formation was detected. 7KCh induced the phosphorylation of ERK1/2 and p38MAPK, and inhibitors to these kinases markedly reduced the cytokine expression but did not affect the IκBα mRNA expression. By contrast, inhibition of PI3K and PKCζ significantly decreased the cytokine and IκBα mRNA expression. Inhibition of the IκB kinase complex essentially ablated all cytokine induction. CONCLUSIONS 7KCh induces cytokines via three kinase signaling pathways, AKT-PKCζ-NFκB, p38 MAPK, and ERK. The MAPK/ERK pathways seem to preferentially enhance cytokine induction downstream from NFκB activation. The results of this study suggest that 7KCh activates these pathways through interactions in the plasma membrane, but the mechanism(s) remains unknown.
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Affiliation(s)
- Ignacio M Larrayoz
- Mechanisms of Retinal Diseases Section, Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
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Determination of oxysterols in oxidatively modified low-density lipoprotein by semi-micro high-performance liquid chromatography with electrochemical detection. Anal Biochem 2009; 393:222-8. [PMID: 19563770 DOI: 10.1016/j.ab.2009.06.032] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Revised: 06/22/2009] [Accepted: 06/23/2009] [Indexed: 11/23/2022]
Abstract
A simple method for the determination of oxysterols was developed by semi-micro high-performance liquid chromatography with electrochemical detection (semi-micro HPLC-ECD). Semi-micro HPLC-ECD was established using a C30 microbore column, acetonitrile containing 50 mmol/L LiClO(4) as a mobile phase, and an applied potential at +2.8V versus Ag/AgCl. The current peak height was linearly related to the amount of sterol injected from 12.5 to 250 pmol (r>0.999) with a relative standard deviation (RSD) of less than 2.9% (n=6). This method was applied to the determination of seven oxysterols in oxidatively modified low-density lipoprotein (Ox-LDL). Oxysterols were determined with a recovery of more than 78.0% and an RSD of less than 2.9% (n=6) except for 7-ketocholesterol. 7-Ketocholesterol was determined as a sum of intact 7-ketocholesterol and its degradation product on saponification, cholesta-3,5-dien-7-one, with a recovery of 98.0% and an RSD of 2.5% (n=6). From these results, the current method enabled the simultaneous determination of seven oxysterols without any derivatization, providing a useful tool for the assessment of oxysterol contents in Ox-LDL.
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11
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Moreira EF, Larrayoz IM, Lee JW, Rodríguez IR. 7-Ketocholesterol is present in lipid deposits in the primate retina: potential implication in the induction of VEGF and CNV formation. Invest Ophthalmol Vis Sci 2008; 50:523-32. [PMID: 18936140 DOI: 10.1167/iovs.08-2373] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE 7-Ketocholesterol is a highly toxic oxysterol found in abundance in atherosclerotic plaques and is believed to play a critical role in atherosclerosis. The purpose of this study was to identify and localize 7-ketocholesterol (7kCh) in the primate retina and to examine the potential consequences of its presence in oxidized lipid deposits in the retina. METHODS Unsterified 7kCh was identified and quantified by high-performance liquid chromatography-mass spectrometry. Localization of 7kCh was performed by immunohistochemistry. VEGF induction was determined by qRT-PCR. Cell viability was determined by measuring cellular dehydrogenase activity. Analyses were performed using ARPE19 and human vascular endothelial cells (HMVECs). RESULTS 7-Ketocholesterol is localized mainly to deposits in the choriocapillaris and Bruch's membrane and on the surfaces of vascular endothelial cells of the neural retina. RPE/choriocapillaris regions contained approximately four times more 7kCh than the neural retina. In ARPE19 cells and HMVECs, oxidized LDL and 7kCh induced VEGF 8- to 10-fold above controls. Hypoxia inducible factor (HIF)-1alpha levels did not increase as a result of 7kCh treatment, suggesting an HIF-independent induction pathway. Cholesterol sulfate, a liver X receptor (LXR) antagonist, had marked attenuation of the 7kCh-mediated VEGF induction. LXR-specific siRNAs also reduced VEGF induction. Inhibition of NF-kappaB with BAY 11-7082 reduced IL-8 but not VEGF induction. CONCLUSIONS The location of 7-kCh in the retina and its induction of VEGF in cultured RPE cells and HMVECs suggest it may play a critical role in choroidal neovascularization. The pathway for VEGF induction seems to be independent of HIF-1alpha and NF-kappaB but seems to be partially regulated by LXRs.
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Affiliation(s)
- Ernesto F Moreira
- Section on Mechanisms of Retinal Diseases, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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12
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Di Benedetto R, Varì R, Scazzocchio B, Filesi C, Santangelo C, Giovannini C, Matarrese P, D'Archivio M, Masella R. Tyrosol, the major extra virgin olive oil compound, restored intracellular antioxidant defences in spite of its weak antioxidative effectiveness. Nutr Metab Cardiovasc Dis 2007; 17:535-545. [PMID: 16928436 DOI: 10.1016/j.numecd.2006.03.005] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2005] [Revised: 01/17/2006] [Accepted: 03/28/2006] [Indexed: 02/02/2023]
Abstract
BACKGROUND AND AIM Extra virgin olive oil has been associated with a reduced incidence of risk factors for coronary heart disease also owing to the presence of antioxidant biophenols. This study compared the protective effects of tyrosol and hydroxytyrosol, two biophenols greatly different in antioxidant power, on J774 A.1-mediated oxidation of LDL. METHODS AND RESULTS Cell-mediated oxidation of LDL was evaluated by TBARS formation, and relative electrophoretic mobility increase. Redox imbalance was studied by: (i) cytofluorimetric determination of intracellular ROS and GSH, and (ii) evaluation of GSH-related enzyme activities and gene expressions by colorimetric and RT-PCR analyses, respectively. The cellular uptake of the biophenols was evaluated by HPLC. Both biophenols inhibited cell-mediated oxidation of LDL but to a different extent (100% hydroxytyrosol vs 40% tyrosol), and counteracted the impairment of antioxidant cellular defence, i.e., GSH and related enzymes. Tyrosol was effective in inhibiting about 30% of ROS production only at later time-points (12h for superoxide, 24h for hydrogen peroxides). Interestingly, both biophenols were effective when added to the cells for 2h and removed before LDL treatment. This was probably related to cell-biophenol interactions: hydroxytyrosol was rapidly found inside the cells (1.12+/-0.05ng/mg cell protein) and disappeared within 18h, while tyrosol accumulated intracellularly with time (0.68+/-0.09 vs 1.72+/-0.13ng/mg cell protein at minute 5 and hour 18, respectively). CONCLUSIONS In spite of its weak antioxidant activity, tyrosol was effective in preserving cellular antioxidant defences, probably by intracellular accumulation. These findings give further evidence in favour of olive oil consumption to counteract cardiovascular diseases.
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Affiliation(s)
- Roberta Di Benedetto
- National Centre for Food Quality and Risk Assessment, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
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Masella R, Varì R, D'Archivio M, Di Benedetto R, Matarrese P, Malorni W, Scazzocchio B, Giovannini C. Extra virgin olive oil biophenols inhibit cell-mediated oxidation of LDL by increasing the mRNA transcription of glutathione-related enzymes. J Nutr 2004; 134:785-91. [PMID: 15051826 DOI: 10.1093/jn/134.4.785] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
It has been reported that oxidized LDL (oxLDL) are involved in the pathogenesis of atherosclerosis, and that macrophages as well as other cells of the arterial wall can oxidize LDL in vitro, depending on the balance between intracellular prooxidant generation and antioxidant defense efficiency. Because of their possible beneficial role in the prevention of atherosclerosis and other oxidative stress-associated diseases, phenolic compounds naturally occurring in vegetables, fruits, and beverages are receiving increased attention. In the present work, we investigated the mechanisms underlying the protective effect exerted by extra virgin olive oil biophenols, namely, protocatechuic acid and oleuropein, on LDL oxidation mediated by murine J774 A.1 macrophage-like cells. The biophenols were added to the cells with LDL and left in the medium during the entire experimental period, or for a period of 2 h and then removed from the medium before the addition of LDL. The effect of biophenols alone was also tested. In both experimental procedures, these antioxidants had the following effects: 1). completely prevented the J774 A.1-mediated oxidation of LDL; 2). counteracted the time-dependent variations in intracellular redox balance, inhibiting the production of O(2)(.-) and H(2)O(2) and the decrease in glutathione (GSH) content; 3). restored glutathione reductase (GR) and peroxidase (GPx) activities; and 4). restored the mRNA expression of gamma-glutamylcisteine synthetase (gammaGCS), GR, and GPx to control values. More importantly, we observed significant overtranscription and increased activities of two antioxidative enzymes, GPx and GR, compared with controls when the biophenols were present in the medium for 2 h and then removed before LDL exposure, or when the cells were exposed to the antioxidants alone for up to 24 h. Our findings suggest that the activation of mRNA transcription of GSH-related enzymes represents an important mechanism in phenolic antioxidative action.
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Affiliation(s)
- Roberta Masella
- Department of Metabolism, Istituto Superiore di Sanità, 00161 Rome, Italy.
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Nhan TQ, Liles WC, Chait A, Fallon JT, Schwartz SM. The p17 cleaved form of caspase-3 is present within viable macrophages in vitro and in atherosclerotic plaque. Arterioscler Thromb Vasc Biol 2003; 23:1276-82. [PMID: 12763761 DOI: 10.1161/01.atv.0000078602.54433.07] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE In vitro studies of macrophage death in response to oxidized LDL (oxLDL) were undertaken as a model for the formation of the necrotic core of atherosclerotic plaque. METHODS AND RESULTS Thioglycollate-elicited mouse peritoneal macrophages avidly incorporated both oxLDL and acetylated LDL (acLDL) to become foam cells. oxLDL-treated macrophages, but not acLDL-treated macrophages, showed nearly 100% death, with characteristics consistent with apoptosis, including cell surface phosphatidylserine exposure, intracellular caspase-3 activity, cleavage of caspase-3 substrates, and DNA fragmentation, as shown by TUNEL assay. The activated form of caspase-3 (p17 cleaved form) was present in attached, viable macrophages before exposure to oxLDL. This p17 form was also found in apparently viable as well as in TUNEL-positive cells within atherosclerotic lesions of chow-fed apolipoprotein E-deficient (ApoE-/-) mice. The amount of p17 caspase-3 was reduced by in vitro blockade of FasL with an FasL-blocking antibody and was absent in macrophages from lpr/lpr mice, which lack functional Fas. Moreover, lpr/lpr macrophages resisted oxLDL cytotoxicity. CONCLUSIONS The naturally occurring Fas-FasL induction of caspase-3 cleavage after macrophage attachment may represent an important physiologic mechanism that primes for cytotoxicity by oxLDL and possibly, other death-inducing molecules.
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Affiliation(s)
- Thomas Q Nhan
- Department of Pathology, School of Medicine, University of Washington, Seattle, WA 98195, USA
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Ashidate K, Kawamura M, Tohda H, Miyazaki S, Hayashi H, Teramoto T, Hirata Y. Ascorbic acid augments cytotoxicity induced by oxidized low-density lipoprotein. J Atheroscler Thromb 2003; 10:7-12. [PMID: 12621158 DOI: 10.5551/jat.10.7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Although ascorbic acid (ASA) is known as a water-soluble antioxidant, we found that it accelerated the cytotoxicity induced by oxidized low-density lipoprotein (OxLDL) in vitro. This suggests that ASA may enhance the oxidation of LDL to augment the atherogenic activities of OxLDL under certain conditions. Thus, this study was designed to investigate the underlying mechanism that ASA enhances OxLDL-induced cytotoxicity. ASA enhanced the cytotoxicity of macrophage cell line (J774) induced by OxLDL in a dose-dependent manner, whose effect was more apparent in high glucose concentration in the medium. The ASA-induced enhancement in cytotoxicity was inhibited by the presence of lipid-soluble antioxidants, such as alpha-tocopherol and probucol, suggesting that the pro-cytotoxic effect by ASA is likely due to its pro-oxidant property. We also investigated the effects of ASA at different time points on the Cu2+-mediated oxidation of LDL. ASA decreased the rate of conjugated dienes formation when added at the early phase of oxidation, whereas it increased when added at the late phase of oxidation. These data suggest that ASA may act as a pro-oxidant under the condition of extensive LDL oxidation. To prevent oxidation stress, ASA would be better used together with lipid-soluble antioxidants for antioxidant therapies.
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Affiliation(s)
- Keiko Ashidate
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Tokyo Teishin Hospital, Tokyo, Japan
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Li D, Liu L, Chen H, Sawamura T, Mehta JL. LOX-1, an oxidized LDL endothelial receptor, induces CD40/CD40L signaling in human coronary artery endothelial cells. Arterioscler Thromb Vasc Biol 2003; 23:816-21. [PMID: 12637341 DOI: 10.1161/01.atv.0000066685.13434.fa] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Despite increasing appreciation that atherogenesis involves participation of inflammatory cells, information on mediators of communication between different constituents of atherosclerotic plaque remain incomplete. We examined the role of LOX-1, a receptor for oxidized (ox) LDL, in the expression of CD40/CD40L in cultured human coronary artery endothelial cells (HCAECs). METHODS AND RESULTS We observed that ox-LDL increased the expression of CD40 and CD40L in a concentration (10 to 80 microg/mL)- and time (1 to 24 hours)- dependent manner. These effects of ox-LDL were mediated by activation of LOX-1, because pretreatment of HCAECs with a blocking antibody to LOX-1 (JTX92) prevented the expression of CD40 and CD40L in response to ox-LDL (P<0.01). In parallel experiments, HCAECs were incubated with the protein kinase C (PKC) inhibitor bisindolylmaleimide I, and the cells were then exposed to ox-LDL. Both LOX-1 antibody and the PKC inhibitor inhibited PKC activation in response to ox-LDL (P<0.01). The PKC inhibitor also blocked the effects of ox-LDL on the expression of CD40 and CD40L (P<0.01). In additional experiments, we found that it is the PKCalpha, but not PKCbeta and PKCgamma, isoform that mediated ox-LDL-induced CD40 and CD40L upregulation. Further experiments showed that upregulation of CD40 mediated induction of proinflammatory genes, because CD40 antibody markedly reduced ox-LDL-induced TNF-alpha generation and P-selectin expression, whereas nonspecific mouse IgG had no effect. CONCLUSIONS These findings indicate that ox-LDL through its receptor LOX-1 triggers the CD40/CD40L signaling pathway that activates the inflammatory reaction in HCAECs. These observations provide novel insight into ox-LDL-mediated inflammation in atherosclerosis.
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Affiliation(s)
- Dayuan Li
- Department of Medicine, University of Arkansas for Medical Sciences and Central Arkansas Veterans Healthcare System, Little Rock, AR 72205, USA
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Owens J, Ramslerl B, Lawrence R. News in brief. Drug Discov Today 2001. [DOI: 10.1016/s1359-6446(01)01767-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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