Mitochondrial DNA damage can promote atherosclerosis independently of reactive oxygen species through effects on smooth muscle cells and monocytes and correlates with higher-risk plaques in humans.

TitleMitochondrial DNA damage can promote atherosclerosis independently of reactive oxygen species through effects on smooth muscle cells and monocytes and correlates with higher-risk plaques in humans.
Publication TypeJournal Article
Year of Publication2013
AuthorsYu, E, Calvert, PA, Mercer, JR, Harrison, J, Baker, L, Figg, NL, Kumar, S, Wang, JC, Hurst, LA, Obaid, DR, Logan, A, West, NEJ, Clarke, MCH, Vidal-Puig, A, Murphy, MP, Bennett, MR
JournalCirculation
Volume128
Issue7
Pagination702-12
Date Published2013 Aug 13
ISSN1524-4539
KeywordsAdiposity, Adult, Aged, Animals, Apolipoproteins E, Apoptosis, Atherosclerosis, Cells, Cultured, Cytokines, DNA Adducts, DNA Damage, DNA Polymerase gamma, DNA, Mitochondrial, DNA-Directed DNA Polymerase, Electron Transport, Female, Humans, Hyperlipidemias, Leukocytes, Male, Mice, Mice, Inbred C57BL, Mice, Knockout, Middle Aged, Mitochondria, Monocytes, Muscle, Smooth, Vascular, Myocytes, Smooth Muscle, Oxygen Consumption, Plaque, Atherosclerotic, Radiation Chimera, Reactive Oxygen Species, Risk
Abstract

BACKGROUND: Mitochondrial DNA (mtDNA) damage occurs in both circulating cells and the vessel wall in human atherosclerosis. However, it is unclear whether mtDNA damage directly promotes atherogenesis or is a consequence of tissue damage, which cell types are involved, and whether its effects are mediated only through reactive oxygen species.METHODS AND RESULTS: mtDNA damage occurred early in the vessel wall in apolipoprotein E-null (ApoE(-/-)) mice, before significant atherosclerosis developed. mtDNA defects were also identified in circulating monocytes and liver and were associated with mitochondrial dysfunction. To determine whether mtDNA damage directly promotes atherosclerosis, we studied ApoE(-/-) mice deficient for mitochondrial polymerase-γ proofreading activity (polG(-/-)/ApoE(-/-)). polG(-/-)/ApoE(-/-) mice showed extensive mtDNA damage and defects in oxidative phosphorylation but no increase in reactive oxygen species. polG(-/-)/ApoE(-/-) mice showed increased atherosclerosis, associated with impaired proliferation and apoptosis of vascular smooth muscle cells, and hyperlipidemia. Transplantation with polG(-/-)/ApoE(-/-) bone marrow increased the features of plaque vulnerability, and polG(-/-)/ApoE(-/-) monocytes showed increased apoptosis and inflammatory cytokine release. To examine mtDNA damage in human atherosclerosis, we assessed mtDNA adducts in plaques and in leukocytes from patients who had undergone virtual histology intravascular ultrasound characterization of coronary plaques. Human atherosclerotic plaques showed increased mtDNA damage compared with normal vessels; in contrast, leukocyte mtDNA damage was associated with higher-risk plaques but not plaque burden.CONCLUSIONS: We show that mtDNA damage in vessel wall and circulating cells is widespread and causative and indicates higher risk in atherosclerosis. Protection against mtDNA damage and improvement of mitochondrial function are potential areas for new therapeutics.

DOI10.1161/CIRCULATIONAHA.113.002271
Alternate JournalCirculation
Citation Key10.1161/CIRCULATIONAHA.113.002271
PubMed ID23841983
Grant ListRG/08/009/25841 / / British Heart Foundation / United Kingdom
FS/10/70/28507 / / British Heart Foundation / United Kingdom
MC_UU_12012/2 / / Medical Research Council / United Kingdom
G0800784 / / Medical Research Council / United Kingdom
MC_UU_12012/5 / / Medical Research Council / United Kingdom
FS/13/3/30038 / / British Heart Foundation / United Kingdom
MC_U105663142 / / Medical Research Council / United Kingdom
G0600717 / / Medical Research Council / United Kingdom
FS/09/005/26845 / / British Heart Foundation / United Kingdom
G1000847 / / Medical Research Council / United Kingdom
PG/11/57/29003 / / British Heart Foundation / United Kingdom