ABSTRACT
BACKGROUND: Coronary atherosclerotic disease remains the leading cause of death in the Western world. Although the exact sequence of events in this process is controversial, reactive oxygen and nitrogen species (RS) likely play an important role in vascular cell dysfunction and atherogenesis. Oxidative damage to the mitochondrial genome with resultant mitochondrial dysfunction is an important consequence of increased intracellular RS. METHODS AND RESULTS: We examined the contribution of mitochondrial oxidant generation and DNA damage to the progression of atherosclerotic lesions in human arterial specimens and atherosclerosis-prone mice. Mitochondrial DNA damage not only correlated with the extent of atherosclerosis in human specimens and aortas from apolipoprotein E(-/-) mice but also preceded atherogenesis in young apolipoprotein E(-/-) mice. Apolipoprotein E(-/-) mice deficient in manganese superoxide dismutase, a mitochondrial antioxidant enzyme, exhibited early increases in mitochondrial DNA damage and a phenotype of accelerated atherogenesis at arterial branch points. CONCLUSIONS: Mitochondrial DNA damage may result from RS production in vascular tissues and may in turn be an early event in the initiation of atherosclerotic lesions.
Subject(s)
Arteriosclerosis/metabolism , Mitochondria/metabolism , Tyrosine/analogs & derivatives , Animals , Aorta/metabolism , Aorta/pathology , Apolipoproteins E/deficiency , Apolipoproteins E/genetics , Arteriosclerosis/pathology , DNA Damage , DNA, Mitochondrial/metabolism , Disease Models, Animal , Disease Progression , Heterozygote , Homozygote , Humans , Immunohistochemistry , Mice , Mice, Inbred C57BL , Mice, Knockout , Phenotype , Reactive Oxygen Species/metabolism , Superoxide Dismutase/deficiency , Superoxide Dismutase/genetics , Tyrosine/biosynthesisABSTRACT
BACKGROUND: A shared feature among cardiovascular disease risk factors is increased oxidative stress. Because mitochondria are susceptible to damage mediated by oxidative stress, we hypothesized that risk factors (secondhand smoke and hypercholesterolemia) are associated with increased mitochondrial damage in cardiovascular tissues. METHODS AND RESULTS: Atherosclerotic lesion formation, mitochondrial DNA damage, protein nitration, and specific activities of mitochondrial proteins in cardiovascular tissues from age-matched C57 and apoE(-/-) mice exposed to filtered air or secondhand smoke were quantified. Both secondhand smoke and hypercholesterolemia were associated with significantly increased mitochondrial DNA damage and protein nitration. Tobacco smoke exposure also resulted in significantly decreased specific activities of mitochondrial enzymes. The combination of secondhand smoke and hypercholesterolemia resulted in increased atherosclerotic lesion formation and even greater levels of mitochondrial damage. CONCLUSIONS: These data are consistent with the hypothesis that cardiovascular disease risk factors cause mitochondrial damage and dysfunction.