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Kishimoto Y, Saita E, Ohmori R, Kondo K, Momiyama Y. High plasma concentrations of vanin-1 in patients with coronary artery disease. Heart Vessels 2024; 39:10-17. [PMID: 37582951 DOI: 10.1007/s00380-023-02305-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Accepted: 08/09/2023] [Indexed: 08/17/2023]
Abstract
Vanin-1 is a pantetheinase that hydrolyzes pantetheine to pantothenic acid and cysteamine. Vanin-1 has become recognized to be associated with oxidative stress and inflammation. In animal models, vanin-1 was reported to accelerate atherosclerosis. However, no study has reported blood vanin-1 concentrations in patients with coronary artery disease (CAD). We investigated plasma vanin-1 concentrations in 388 patients undergoing elective coronary angiography for suspected CAD. Patients with acute coronary syndrome were excluded. Of the 388 study patients, CAD was found in 207 patients [1-vessel (1-VD), n = 88; 2-vessel (2-VD), n = 66; and 3-vessel disease (3-VD), n = 53]. Plasma vanin-1 concentrations were higher in patients with CAD than in those without CAD (median 0.59 vs. 0.46 ng/mL, P < 0.005). Vanin-1 concentrations in patients without CAD and those with 1-VD, 2-VD, and 3-VD were 0.46, 0.58, 0.57, and 0.61 ng/mL, respectively, and were highest in 3-VD (P < 0.05). A high vainin-1 concentration (> 0.48 ng/mL) was found in 46% of patients without CAD, 61% of 1-VD, 65% of 2-VD, and 66% of 3-VD (P < 0.01). Vanin-1 concentrations significantly correlated with the number of stenotic coronary segments (r = 0.14, P < 0.02). In the multivariate analysis, vanin-1 concentration was a significant factor associated with CAD independent of atherosclerotic risk factors. The odds ratio for CAD was 1.63 (95%CI = 1.04-2.55) for the high vanin-1 concentration of > 0.48 ng/mL. Thus, plasma vanin-1 concentrations in patients with CAD were found to be high and to be associated with the presence and severity of CAD.
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Affiliation(s)
- Yoshimi Kishimoto
- Department of Food Science and Human Nutrition, Setsunan University, Osaka, Japan
| | - Emi Saita
- Research Institute of Environmental Medicine, Nagoya University, Aichi, Japan
| | - Reiko Ohmori
- Faculty of Regional Design, Utsunomiya University, Tochigi, Japan
| | | | - Yukihiko Momiyama
- Department of Cardiology, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro-ku, Tokyo, 152-8902, Japan.
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2
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Speeckaert R, Bulat V, Speeckaert MM, van Geel N. The Impact of Antioxidants on Vitiligo and Melasma: A Scoping Review and Meta-Analysis. Antioxidants (Basel) 2023; 12:2082. [PMID: 38136202 PMCID: PMC10740621 DOI: 10.3390/antiox12122082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2023] [Revised: 11/14/2023] [Accepted: 11/20/2023] [Indexed: 12/24/2023] Open
Abstract
Reactive oxygen species (ROS) generated during melanogenesis make melanocytes particularly vulnerable to oxidative stress, influencing their survival and melanin synthesis. Oxidative stress, significantly present in vitiligo and recently also detected in melasma, triggers inflammatory cascades and melanogenesis, making antioxidants a promising therapeutic avenue. A systematic search was conducted on Embase and Pubmed to study the efficacy of antioxidants for treating vitiligo and/or melasma. Meta-analysis was performed to assess the difference in Melasma Severity Index (MASI) scores between baseline and follow-up. Various antioxidants like polypodium leucotomos, ginkgo biloba, catalase/superoxide dismutase, and vitamin E have potential in vitiligo. For melasma, vitamin C, silymarin, and niacinamide were among those showing promise in reducing pigmentation, with vitamin C displaying significant effects in meta-analysis. Different antioxidants improve both vitiligo and melasma, with an increased minimal erythema dose (MED) following UV exposure being significant for vitiligo and tyrosinase inhibition being crucial for melasma. However, the efficacy of individual antioxidants varies, and their exact mechanisms, especially in stimulating melanocyte proliferation and anti-inflammatory pathways, require further investigation to understand better and optimize their use.
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Affiliation(s)
- Reinhart Speeckaert
- Department of Dermatology, Ghent University Hospital, Corneel Heymanslaan 10, 9000 Ghent, Belgium
| | - Vedrana Bulat
- Department of Dermatology, University Hospital Centre Zagreb, 10000 Zagreb, Croatia
| | | | - Nanja van Geel
- Department of Dermatology, Ghent University Hospital, Corneel Heymanslaan 10, 9000 Ghent, Belgium
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3
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Al-U'datt DGF, Tranchant CC, Alu'datt M, Abusara S, Al-Dwairi A, AlQudah M, Al-Shboul O, Hiram R, Altuntas Y, Jaradat S, Alzoubi KH. Inhibition of transglutaminase 2 (TG2) ameliorates ventricular fibrosis in isoproterenol-induced heart failure in rats. Life Sci 2023; 321:121564. [PMID: 36931499 DOI: 10.1016/j.lfs.2023.121564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Revised: 03/06/2023] [Accepted: 03/06/2023] [Indexed: 03/17/2023]
Abstract
AIMS Transglutaminase (TG) inhibitors represent promising therapeutic interventions in cardiac fibrosis and related dysfunctions. However, it remains unknown how TG inhibition, TG2 in particular, affects the signaling systems that drive pathological fibrosis. This study aimed to examine the effect TG inhibition by cystamine on the progression of isoproterenol (ISO)-induced cardiac fibrosis and dysfunction in rats. MATERIALS AND METHODS Cardiac fibrosis was established by intraperitoneal injection of ISO to rats (ISO group), followed by 6 weeks of cystamine injection (ISO + Cys group). The control groups were administered normal saline alone or with cystamine. Hemodynamics, lipid profile, liver enzymes, urea, and creatinine were assessed in conjunction with heart failure markers (serum NT-proANP and cTnI). Left ventricular (LV) and atrial (LA) fibrosis, total collagen content, and mRNA expression of profibrotic markers including TG2 were quantified by Masson's trichrome staining, LC-MS/MS and quantitative PCR, respectively. KEY FINDINGS Cystamine administration to ISO rats significantly decreased diastolic and mean arterial pressures, total cholesterol, triglycerides, LDL, liver enzymes, urea, and creatinine levels, while increasing HDL. NT-proANP and cTnI serum levels remained unchanged. In LV tissues, significant reductions in ISO-induced fibrosis and elevated total collagen content were achieved after cystamine treatment, together with a reduction in TG2 concentration. Reduced mRNA expression of several profibrotic genes (COL1A1, FN1, MMP-2, CTGF, periostin, CX43) was also evidenced in LV tissues of ISO rats upon cystamine administration, whereas TGF-β1 expression was depressed in LA tissues. Cystamine decreased TG2 mRNA expression in the LV of control rats, while LV expression of TG2 was relatively low in ISO rats irrespective of cystamine treatment. SIGNIFICANCE TG2 inhibition by cystamine in vivo exerted cardioprotective effects against ISO-induced cardiac fibrosis in rats decreasing the LV abundance of several profibrotic markers and the content of TG2 and collagen, suggesting that TG2 pharmacological inhibition could be beneficial to alleviate cardiac fibrosis.
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Affiliation(s)
- Doa'a G F Al-U'datt
- Department of Physiology and Biochemistry, Faculty of Medicine, Jordan University of Science and Technology, Irbid 22110, Jordan.
| | - Carole C Tranchant
- School of Food Science, Nutrition and Family Studies, Faculty of Health Sciences and Community Services, Université de Moncton, New Brunswick, Canada
| | - Muhammad Alu'datt
- Department of Nutrition and Food Technology, Faculty of Agriculture, Jordan University of Science and Technology, P.O. Box 3030, Irbid 22110, Jordan
| | - Sara Abusara
- Department of Physiology and Biochemistry, Faculty of Medicine, Jordan University of Science and Technology, Irbid 22110, Jordan
| | - Ahmed Al-Dwairi
- Department of Physiology and Biochemistry, Faculty of Medicine, Jordan University of Science and Technology, Irbid 22110, Jordan
| | - Mohammad AlQudah
- Department of Physiology and Biochemistry, Faculty of Medicine, Jordan University of Science and Technology, Irbid 22110, Jordan; Physiology Department, Arabian Gulf University, Manama, Bahrain
| | - Othman Al-Shboul
- Department of Physiology and Biochemistry, Faculty of Medicine, Jordan University of Science and Technology, Irbid 22110, Jordan
| | - Roddy Hiram
- Montreal Heart Institute and Department of Medicine, Université de Montréal, Montreal, Quebec, Canada
| | - Yasemin Altuntas
- Montreal Heart Institute and Department of Medicine, Université de Montréal, Montreal, Quebec, Canada
| | - Saied Jaradat
- Princess Haya Biotechnology Center, Jordan University of Science and Technology, Irbid 22110, Jordan
| | - Karem H Alzoubi
- Department of Pharmacy Practice and Pharmacotherapeutics, University of Sharjah, Sharjah, United Arab Emirates; Department of Clinical Pharmacy, Faculty of Pharmacy, Jordan University of Science and Technology, Irbid, Jordan
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4
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Ojo OO, Leake DS. Effects of lysosomal low density lipoprotein oxidation by ferritin on macrophage function. Free Radic Res 2022; 56:436-446. [PMID: 36217887 DOI: 10.1080/10715762.2022.2133703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
We have previously demonstrated that low density lipoprotein (LDL) can be oxidised by iron in the lysosomes of macrophages. Some of the iron content of lysosomes might be delivered through autophagy of ferritin (the main iron-storage protein in the body). We have now investigated the effects of ferritin-mediated LDL oxidation on macrophage function. The addition of ferritin to human THP-1 cells and human monocyte-derived macrophages increased lysosomal lipid peroxidation, as shown by LPO-Foam, a fluorescent probe targetted to lysosomes. Incubating THP-1 cells with ferritin and native LDL or LDL aggregated by sphingomyelinase, to allow their endocytosis and delivery to lysosomes, led to the formation of lysosomal ceroid (an advanced lipid oxidation product), indicative of lysosomal LDL oxidation. Incubating THP-1 cells with ferritin and LDL caused metabolic activation of the cells, as shown by increased extracellular acidification and oxygen consumption measured by a Seahorse analyser. LDL oxidised by ferritin in lysosomes might be released from macrophages when the cells die and lyse and affect neighbouring cells in atherosclerotic lesions. Adding LDL oxidised by ferritin at lysosomal pH (pH 4.5) to macrophages increased their intracellular reactive oxygen species formation, shown using dihydroethidium, and increased apoptosis. Ferritin might therefore contribute to LDL oxidation in the lysosomes of macrophages and have atherogenic effects.
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Affiliation(s)
- Oluwatosin O Ojo
- School of Biological Sciences and Institute for Cardiovascular and Metabolic Research, University of Reading, Reading, Berkshire, UK
| | - David S Leake
- School of Biological Sciences and Institute for Cardiovascular and Metabolic Research, University of Reading, Reading, Berkshire, UK
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5
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Björkegren JLM, Lusis AJ. Atherosclerosis: Recent developments. Cell 2022; 185:1630-1645. [PMID: 35504280 PMCID: PMC9119695 DOI: 10.1016/j.cell.2022.04.004] [Citation(s) in RCA: 305] [Impact Index Per Article: 152.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 03/30/2022] [Accepted: 04/01/2022] [Indexed: 12/13/2022]
Abstract
Atherosclerosis is an inflammatory disease of the large arteries that is the major cause of cardiovascular disease (CVD) and stroke. Here, we review the current understanding of the molecular, cellular, genetic, and environmental contributions to atherosclerosis, from both individual pathway and systems perspectives. We place an emphasis on recent developments, some of which have yielded unexpected biology, including previously unknown heterogeneity of inflammatory and smooth muscle cells in atherosclerotic lesions, roles for senescence and clonal hematopoiesis, and links to the gut microbiome.
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Affiliation(s)
- Johan L M Björkegren
- Department of Genetics and Genomic Sciences, Division of Cardiology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Department of Medicine, Huddinge, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
| | - Aldons J Lusis
- Department of Medicine/Division of Cardiology, Department of Microbiology, Immunology and Molecular Genetics, Department of Human Genetics, A2-237 Center for the Health Sciences, University of California, Los Angeles, Los Angeles, CA USA.
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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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7
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Correia MJ, Pimpão AB, Fernandes DGF, Morello J, Sequeira CO, Calado J, Antunes AMM, Almeida MS, Branco P, Monteiro EC, Vicente JB, Serpa J, Pereira SA. Cysteine as a Multifaceted Player in Kidney, the Cysteine-Related Thiolome and Its Implications for Precision Medicine. Molecules 2022; 27:1416. [PMID: 35209204 PMCID: PMC8874463 DOI: 10.3390/molecules27041416] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 02/15/2022] [Accepted: 02/17/2022] [Indexed: 11/16/2022] Open
Abstract
In this review encouraged by original data, we first provided in vivo evidence that the kidney, comparative to the liver or brain, is an organ particularly rich in cysteine. In the kidney, the total availability of cysteine was higher in cortex tissue than in the medulla and distributed in free reduced, free oxidized and protein-bound fractions (in descending order). Next, we provided a comprehensive integrated review on the evidence that supports the reliance on cysteine of the kidney beyond cysteine antioxidant properties, highlighting the relevance of cysteine and its renal metabolism in the control of cysteine excess in the body as a pivotal source of metabolites to kidney biomass and bioenergetics and a promoter of adaptive responses to stressors. This view might translate into novel perspectives on the mechanisms of kidney function and blood pressure regulation and on clinical implications of the cysteine-related thiolome as a tool in precision medicine.
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Affiliation(s)
- Maria João Correia
- CEDOC, NOVA Medical School, Universidade Nova de Lisboa, 1169-056 Lisboa, Portugal; (M.J.C.); (A.B.P.); (J.M.); (C.O.S.); (M.S.A.); (P.B.); (E.C.M.); (J.S.)
| | - António B. Pimpão
- CEDOC, NOVA Medical School, Universidade Nova de Lisboa, 1169-056 Lisboa, Portugal; (M.J.C.); (A.B.P.); (J.M.); (C.O.S.); (M.S.A.); (P.B.); (E.C.M.); (J.S.)
| | - Dalila G. F. Fernandes
- Instituto de Tecnologia Química e Biológica António Xavier (ITQB NOVA), 2780-157 Oeiras, Portugal; (D.G.F.F.); (J.B.V.)
| | - Judit Morello
- CEDOC, NOVA Medical School, Universidade Nova de Lisboa, 1169-056 Lisboa, Portugal; (M.J.C.); (A.B.P.); (J.M.); (C.O.S.); (M.S.A.); (P.B.); (E.C.M.); (J.S.)
| | - Catarina O. Sequeira
- CEDOC, NOVA Medical School, Universidade Nova de Lisboa, 1169-056 Lisboa, Portugal; (M.J.C.); (A.B.P.); (J.M.); (C.O.S.); (M.S.A.); (P.B.); (E.C.M.); (J.S.)
| | - Joaquim Calado
- Centre for Toxicogenomics and Human Health (ToxOmics), Genetics, Oncology and Human Toxicology, Nova Medical School/Faculdade de Ciências Médicas, Universidade Nova de Lisboa, 1169-056 Lisboa, Portugal;
- Nephrology Department, Centro Hospitalar Universitário de Lisboa Central, 1069-166 Lisboa, Portugal
| | - Alexandra M. M. Antunes
- Centro de Química Estrutural, Institute of Molecular Sciences, Instituto Superior Técnico, 1049-001 Lisboa, Portugal;
| | - Manuel S. Almeida
- CEDOC, NOVA Medical School, Universidade Nova de Lisboa, 1169-056 Lisboa, Portugal; (M.J.C.); (A.B.P.); (J.M.); (C.O.S.); (M.S.A.); (P.B.); (E.C.M.); (J.S.)
- Hospital de Santa Cruz, Centro Hospitalar de Lisboa Ocidental, 2790-134 Carnaxide, Portugal
| | - Patrícia Branco
- CEDOC, NOVA Medical School, Universidade Nova de Lisboa, 1169-056 Lisboa, Portugal; (M.J.C.); (A.B.P.); (J.M.); (C.O.S.); (M.S.A.); (P.B.); (E.C.M.); (J.S.)
- Hospital de Santa Cruz, Centro Hospitalar de Lisboa Ocidental, 2790-134 Carnaxide, Portugal
| | - Emília C. Monteiro
- CEDOC, NOVA Medical School, Universidade Nova de Lisboa, 1169-056 Lisboa, Portugal; (M.J.C.); (A.B.P.); (J.M.); (C.O.S.); (M.S.A.); (P.B.); (E.C.M.); (J.S.)
| | - João B. Vicente
- Instituto de Tecnologia Química e Biológica António Xavier (ITQB NOVA), 2780-157 Oeiras, Portugal; (D.G.F.F.); (J.B.V.)
| | - Jacinta Serpa
- CEDOC, NOVA Medical School, Universidade Nova de Lisboa, 1169-056 Lisboa, Portugal; (M.J.C.); (A.B.P.); (J.M.); (C.O.S.); (M.S.A.); (P.B.); (E.C.M.); (J.S.)
- Instituto Português de Oncologia de Lisboa Francisco Gentil (IPOLFG), 1099-023 Lisboa, Portugal
| | - Sofia A. Pereira
- CEDOC, NOVA Medical School, Universidade Nova de Lisboa, 1169-056 Lisboa, Portugal; (M.J.C.); (A.B.P.); (J.M.); (C.O.S.); (M.S.A.); (P.B.); (E.C.M.); (J.S.)
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8
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Dasagrandhi D, Muthuswamy A, Swaminathan JK. Atherosclerosis: nexus of vascular dynamics and cellular cross talks. Mol Cell Biochem 2022; 477:571-584. [PMID: 34845570 DOI: 10.1007/s11010-021-04307-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 11/17/2021] [Indexed: 01/11/2023]
Abstract
Cardiovascular diseases (CVDs) are the foremost cause of mortality worldwide. Atherosclerosis is the underlying pathology behind CVDs. Atherosclerosis is manifested predominantly by lipid deposition, plaque formation, and inflammation in vascular intima. Initiation and progression of plaque require many years. With aging, atherosclerotic plaques become vulnerable. Localization of these plaques in the coronary artery leads to myocardial infarction. A complete understanding of the pathophysiology of this multifaceted disease is necessary to achieve the clinical goal to provide early diagnosis and the best therapeutics. The triggering factors of atherosclerosis are biomechanical forces, hyperlipidemia, and chronic inflammatory response. The current review focuses on crucial determinants involved in the disease, such as location, hemodynamic factors, oxidation of low-density lipoproteins, and the role of endothelial cells, vascular smooth muscle cells, and immune cells, and better therapeutic targets.
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Affiliation(s)
- Divya Dasagrandhi
- Drug Discovery and Molecular Cardiology Laboratory, Department of Bioinformatics, Bharathidasan University, Tiruchirappalli, 620024, India
| | - Anusuyadevi Muthuswamy
- Molecular Neurogerontology Laboratory, Department of Biochemistry, Bharathidasan University, Tiruchirappalli, 620024, India
| | - Jayachandran Kesavan Swaminathan
- Drug Discovery and Molecular Cardiology Laboratory, Department of Bioinformatics, Bharathidasan University, Tiruchirappalli, 620024, India.
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Ojo OO, Leake DS. Vitamins E and C do not effectively inhibit low density lipoprotein oxidation by ferritin at lysosomal pH. Free Radic Res 2021; 55:525-534. [PMID: 34396869 DOI: 10.1080/10715762.2021.1964494] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Low density lipoprotein (LDL) might be oxidized by iron in the lysosomes of macrophages in atherosclerotic lesions. We have shown previously that the iron-storage proteinferritin can oxidize LDL at lysosomal pH. We have now investigated the roles of the most important antioxidant contained in LDL, α-tocopherol (the main form of vitamin E) and of ascorbate (vitamin C), a major water-soluble antioxidant, on LDL oxidation by ferritin at lysosomal pH (pH 4.5). We incubated LDL with ferritin at pH 4.5 and 37 °C and measured its oxidation by monitoring the formation of conjugated dienes at 234 n min a spectrophotometer. α-Tocopherol is well known to inhibit LDL oxidation at pH 7.4, but enrichment of LDL with α-tocopherol was unable to inhibit LDL oxidation by ferritin at pH 4.5. Ascorbate had a complex effect on LDL oxidation by ferritin at lysosomal pH and exhibited both antioxidant and pro-oxidant effects. It had no antioxidant effect on partially oxidized LDL, only a pro-oxidant effect. Ascorbate completely inhibited LDL oxidation by copper at pH 7.4 for a long period, but in marked contrast did not inhibit LDL oxidation by copper at lysosomal pH. Dehydroascorbate, the oxidation product of ascorbate, had a pronounced pro-oxidant effect on LDL incubated with ferritin at pH 4.5. The inability of α-tocopherol and ascorbate to effectively inhibit LDL oxidation by ferritin at lysosomal pH might help to explain why the large clinical trials with these vitamins failed to show protection against cardiovascular diseases.
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Affiliation(s)
- Oluwatosin O Ojo
- School of Biological Sciences and Institute for Cardiovascular and Metabolic Research, University of Reading, Reading, Berkshire, UK
| | - David S Leake
- School of Biological Sciences and Institute for Cardiovascular and Metabolic Research, University of Reading, Reading, Berkshire, UK
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