doi: 10.1161/hh0701.089955
© 2001 American Heart Association, Inc.
Editorial |
Reactive Oxygen Species and Death
Oxidative DNA Damage in Atherosclerosis
From Addenbrooke’s Centre for Clinical Investigation, Addenbrooke’s Hospital, Cambridge, UK.
Correspondence to Martin R. Bennett, Addenbrooke’s Centre for Clinical Investigation, Box 110, Addenbrooke’s Hospital, Cambridge CB2 2QQ, UK. E-mail mrb{at}mole.bio.cam.ac.uk
Key Words: p53 • reactive oxygen species • DNA repair
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Introduction |
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 Top Introduction Oxidative Modification of LDLOxidative Damage to DNAReferences |
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Reactive oxygen species (ROS) (eg, superoxide, peroxide, and hydroxyl radicals) and reactive nitrogen species (eg, peroxynitrite) are generated in both atherogenesis and advanced atherosclerosis,1 particularly by macrophages.2 ROS have many actions, including oxidative modification of LDL and oxidative damage of DNA.
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Oxidative Modification of LDL |
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TopIntroductionOxidative Modification of LDLOxidative Damage to DNAReferences |
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Although LDL is essential to deliver cholesterol to tissues, increased LDL cholesterol is associated with increased risk of cardiovascular disease. Oxidative modification of LDL promotes recruitment and retention of monocytes3 with formation of fatty streaks, the earliest lesions in atherosclerosis.4 Both macrophages and vascular smooth muscle cells (VSMCs) bind oxidized LDL via specific scavenger receptors,5 6 forming foam cells. Macrophage foam cells contain potent oxidant-generating systems that target lipids, including myeloperoxidase, nitric oxide (NO) synthase, and 15-lipoxygenase, allowing increased recognition and uptake by macrophages, creating a positive feedback loop.
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Oxidative Damage to DNA |
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TopIntroductionOxidative Modification of LDLOxidative Damage to DNAReferences |
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ROS also induce oxidative damage of DNA, including strand breaks and base and nucleotide modifications, particularly in sequences with high guanosine content.7 Oxidative modification induces a robust repair response, characterized by excision of modified bases and nucleotides. Double-stranded DNA breaks also activate DNA repair enzymes, including ATM (mutated in ataxia telangiectasia) and ATR (ATM-related kinase). Both ATM and ATR directly phosphorylate and activate specific checkpoint kinases, such as chk2 and hCDS1, with subsequent phosphorylation of the tumor suppressor gene p53.
p53 is the commonest mutation in human cancer and has a major role in genomic surveillance. p53 stimulates base excision repair8 but also coordinates the cell’s response to damage. p53 phosphorylation stabilizes the protein and increases its transcriptional activity, inducing both growth arrest and apoptosis. Thus, ROS-induced DNA damage leads to p53 activation, and growth arrest and apoptosis after DNA damage depend partly on p53.
Although the presence of ROS within the atherosclerotic plaque is not disputed, the major target cells of ROS in vivo are unclear. In particular, ROS induce toxicity in many vascular cell types in culture.9 In view of this, the study by Martinet et al10 in this issue of Circulation Research provides important insights into the role of ROS in atherogenesis and plaque stability. These investigators demonstrated that cholesterol feeding of rabbits induces oxidative damage in plaques, manifested by expression of 8-oxo-G, an oxidative modification of guanine residues in DNA,7 DNA strand breaks, and apoptosis. A graded response was seen, the percentage of cells expressing markers being 8-oxo-G>strand breaks>apoptosis, consistent with fewer cells demonstrating increasing degrees of oxidative damage. These changes were associated with expression of DNA repair enzymes and p53. Importantly, these markers of oxidative damage were rapidly reversible with cholesterol lowering.
The study by Martinet et al10 follows a body evidence implicating p53 as a regulator of macrophage number in atherosclerosis. Macrophages seem to be the major dividing cell in advanced atherosclerosis, particularly after plaque rupture.11 p53 is expressed in inflammatory cell–rich areas of the plaque, and plaques in p53-null animals are more extensive and show increased cell proliferation compared with control animals, suggesting that p53 limits macrophage cell number.12 In addition, Martinet et al10 found a negative correlation between markers of cell proliferation and DNA damage or p53 expression.
Importantly, this study also demonstrates that macrophages are targets for ROS-induced DNA damage, themselves a major source of ROS. Indeed, previous studies have found that apoptotic macrophages in human atherosclerotic plaques are activated, express antigen, and are oxidatively stressed.13 Thus, local ROS generation may induce both macrophage growth arrest and apoptosis. The recent view of macrophages in atherosclerosis hypothesizes that activated macrophages promote plaque instability by secretion of metalloproteinases that degrade matrix and collagen.14 In addition, macrophage products containing NO can induce VSMC apoptosis,15 with consequent reduction in collagen synthesis. Thus, plaque stability has been considered to be a balance of negative effects of macrophages and positive effects of VSMCs; reduction in macrophage number by inhibiting proliferation or apoptosis would therefore be considered beneficial. Indeed, cholesterol lowering and treatment with HMGCoA reductase inhibitors, therapies with proven clinical benefit, reduce macrophage content of human16 and animal lesions.17
In contrast, recent studies showing that macrophage apoptosis colocalizes with plaque rupture in humans18 suggest that this viewpoint may misrepresent the complex plaque microenvironment. One explanation for colocalization is that macrophage apoptosis directly promotes necrotic core formation within advanced lesions. Thus, most apoptosis in advanced lesions occurs in macrophages located around the necrotic core.19 The necrotic core has the major procoagulant activity of the lesion, being partly attributable to microparticles formed by apoptosis of inflammatory cells.20 Colocalization of apoptotic macrophages with plaque rupture may therefore reflect apoptotic macrophages promoting core formation; rupture of plaques with more extensive cores may cause more extensive coagulation, vessel occlusion, and cardiac death. However, Kolodgie et al18 found that macrophage infiltration and apoptosis in the fibrous cap were associated with plaque rupture. This argues strongly that macrophage apoptosis, or processes that ultimately lead to apoptosis, promotes both atherogenesis (via core formation) and plaque instability, possibly by a separate effect in the fibrous cap. Thus, oxidative damage to macrophages may directly promote plaque rupture in addition to promoting necrotic core formation.
Rates of VSMC apoptosis are also increased in advanced atherosclerotic plaques versus normal vessels21 and in unstable versus stable lesions,22 suggesting that VSMC apoptosis promotes plaque rupture. VSMC apoptosis also promotes thrombosis23 and monocyte recruitment via expression of monocyte chemoattractants.24 Thus, VSMC apoptosis in advanced atherosclerosis seems to be uniformly detrimental. Although the triggers for plaque VSMC apoptosis are unknown, VSMC apoptosis occurs in areas of high macrophage content,19 macrophage cytokines and NO induce p53, VSMC apoptosis colocalizes with p53 expression, and p53 induces human plaque VSMC apoptosis.25 This suggests the attractive hypothesis that ROS-activated macrophages induce VSMC apoptosis through cytokine or NO induction of p53. Against this hypothesis, Martinet et al10 found that VSMC apoptosis occurred in cell-poor areas not associated with DNA synthesis or repair.
The findings by Martinet et al10 also help determine macrophage fate within plaques during cholesterol reduction. Many studies have demonstrated that macrophages disappear from lesions on cholesterol reduction. Clearly, cells may disappear by either cell death or emigration. Martinet et al found that oxidative damage, DNA strand breaks, and apoptosis are reduced during lesion regression, suggesting that macrophage numbers reduce by emigration. If macrophage apoptosis is detrimental to plaque stability, how macrophages leave plaques (apoptosis versus emigration) may determine clinical outcome. How monocytes migrate into the vessel wall has been intensively studied. In contrast, little is known about mechanisms of macrophage emigration. If macrophage reduction does determine plaque stability, then such mechanisms should also be an intensive area of study.
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Footnotes |
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The opinions expressed in this editorial are not necessarily those of the editors or of the American Heart Association.
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References |
|---|
|
TopIntroductionOxidative Modification of LDLOxidative Damage to DNAReferences |
|---|
1. Warnholtz A, Nickenig G, Schulz E, Macharzina R, Brasen JH, Skatchkov M, Heitzer T, Stasch JP, Griendling KK, Harrison DG, Bohm M, Meinertz T, Munzel T. Increased NADH-oxidase-mediated superoxide production in the early stages of atherosclerosis: evidence for involvement of the renin-angiotensin system. Circulation. 1999;99:2027–2033.
2. Kojda G, Harrison D. Interactions between NO and reactive oxygen species: pathophysiological importance in atherosclerosis, hypertension, diabetes and heart failure. Cardiovasc Res. 1999;43:562–571.[Medline] [Order article via Infotrieve]
3.
Quinn MT,
Parthasarathy S, Fong LG, Steinberg D. Oxidatively modified low density
lipoproteins: a potential role in recruitment and retention of
monocyte/macrophages during atherogenesis.
Proc Natl Acad Sci
U S A. 1987;84:2995–2998.
4.
Navab M, Berliner
JA, Watson AD, Hama SY, Territo MC, Lusis AJ, Shih DM, Van Lenten BJ,
Frank JS, Demer LL, Edwards PA, Fogelman AM. The yin and yang of
oxidation in the development of the fatty streak.
Arterioscler Thromb Vasc Biol. 1996;16:831–42.
5.
Ottnad E,
Parthasarathy S, Sambrano G, Ramprasad MP, Quehenberger O, Kondratenko
N, Green S, Steinberg D. A macrophage receptor for oxidised
low-density lipoprotein distinct from the receptor for acetyl
low-density lipoprotein: partial purification and role in recognition
of oxidatively damaged cells. Proc Natl
Acad Sci
U S A. 1995;92:1391–1395.
6. Podrez EA, Febbraio M, Sheibani N, Schmitt D, Silverstein RL, Hajjar DP, Cohen PA, Frazier WA, Hoff HF, Hazen SL. Macrophage scavenger receptor CD36 is the major receptor for LDL modified by monocyte-generated reactive nitrogen species. J Clin Invest. 2000;105:1095–1108.[Medline] [Order article via Infotrieve]
7. Burney S, Niles JC, Dedon PC, Tannenbaum SR. DNA damage in deoxynucleosides and oligonucleotides treated with peroxynitrite. Chem Res Toxicol. 1999;12:513–520.[Medline] [Order article via Infotrieve]
8. Zhou J, Ahn J, Wilson SH, Prives C. A role for p53 in base excision repair. EMBO J. 2001;20:914–923.[Medline] [Order article via Infotrieve]
9.
Li PF, Dietz R, von
Harsdorf R. Differential effect of hydrogen peroxide and superoxide
anion on apoptosis and proliferation of vascular smooth muscle
cells. Circulation. 1997;96:3602–3609.
10.
Martinet W,
Knaapen MWM, De Meyer GRY, Herman AG, Kockx MM. Oxidative DNA damage
and repair in experimental atherosclerosis are reversed
by dietary lipid lowering. Circ
Res. 2001;88:733-739.
11.
Lutgens E, de
Muinck ED, Kitslaar PJ, Tordoir JH, Wellens HJ, Daemen MJ. Biphasic
pattern of cell turnover characterizes the progression from fatty
streaks to ruptured human atherosclerotic plaques.
Cardiovasc Res. 1999;41:473–479.
12. Guevara N, Kim H-S, Antonova E, Chan L. The absence of p53 accelerates atherosclerosis by increasing cell proliferation in vivo. Nat Med. 1999;5:335–339.[Medline] [Order article via Infotrieve]
13. Kinscherf R, Wagner M, Kamencic H, Bonaterra CA, Hou DM, Schiele RA, Deigner HP, Metz J. Characterization of apoptotic macrophages in atheromatous tissue of humans and heritable hyperlipidemic rabbits. Atherosclerosis. 1999;144:33–39.[Medline] [Order article via Infotrieve]
14. Galis ZS, Sukhova GK, Lark MW, Libby P. Increased expression of matrix metalloproteinases and matrix-degrading activity in vulnerable regions of human atherosclerotic plaques. J Clin Invest. 1994;94:2493–2503.
15.
Geng Y, Wu Q,
Muszynski M, Hansson G, Libby P. Apoptosis of vascular
smooth-muscle cells induced by in vitro stimulation with
interferon-
, tumor necrosis factor-
, and interleukin-1ß.
Arterioscler Thromb Vasc Biol. 1996;16:19–27.
16.
Crisby M,
Nordin-Fredriksson G, Shah PK, Yano J, Zhu J, Nilsson J.
Pravastatin treatment increases collagen content and
decreases lipid content, inflammation, metalloproteinases, and cell
death in human carotid plaques: implications for plaque stabilization.
Circulation. 2001;103:926–933.
17.
Aikawa M, Rabkin
E, Okada Y, Voglic SJ, Clinton SK, Brinckerhoff CE, Sukhova GK, Libby
P. Lipid lowering by diet reduces matrix metalloproteinase activity and
increases collagen content of rabbit atheroma: a potential
mechanism of lesion stabilization.
Circulation. 1998;97:2433–2444.
18.
Kolodgie FD,
Narula J, Burke AP, Haider N, Farb A, Hui-Liang Y, Smialek J, Virmani
R. Localization of apoptotic macrophages at the site of
plaque rupture in sudden coronary death.
Am J Pathol. 2000;157:1259–1268.
19.
Kockx MM, DeMeyer
G, Muhring J, Jacob W, Bult H, Herman AG. Apoptosis and related
proteins in different stages of human atherosclerotic plaques.
Circulation. 1998;97:2307–2315.
20.
Mallat Z, Hugel
B, Ohan J, Leseche G, Freyssinet JM, Tedgui A. Shed membrane
microparticles with procoagulant potential in human atherosclerotic
plaques: a role for apoptosis in plaque thrombogenicity.
Circulation. 1999;99:348–353.
21. Geng Y, Libby P. Evidence for apoptosis in advanced human atheroma: colocalization with interleukin-1ß converting enzyme. Am J Pathol. 1995;147:251–266.[Abstract]
22.
Bauriedel
G, Hutter R, Welsch U, Bach R, Sievert H, Luderitz B. Role of smooth
muscle cell death in advanced coronary primary lesions:
implications for plaque instability.
Cardiovasc Res. 1999;41:480–488.
23. Flynn P, Byrne C, Baglin T, Weissberg P, Bennett M. Thrombin generation by apoptotic vascular smooth muscle cells. Blood. 1997;89:4373–4384.
24. Schaub FJ, Han DK, Conrad Liles W, Adams LD, Coats SA, Ramachandran RK, Seifert RA, Schwartz SM, Bowen-Pope DF. Fas/FADD-mediated activation of a specific program of inflammatory gene expression in vascular smooth muscle cells. Nat Med. 2000;6:790–796.[Medline] [Order article via Infotrieve]
25.
Bennett MR,
Littlewood TD, Schwartz SM, Weissberg PL. Increased sensitivity of
human vascular smooth muscle cells from atherosclerotic plaque to
p53-mediated apoptosis. Circ
Res. 1997;81:591–599.
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