Dataset Information

Mitochondrial DNA copy number is associated with all-cause mortality and cardiovascular events in patients with peripheral arterial disease.

ABSTRACT:

Background

Dysfunctional mitochondria have an influence on inflammation and increased oxidative stress due to an excessive production of reactive oxygen species. The mitochondrial DNA copy number (mtDNA-CN) is a potential biomarker for mitochondrial dysfunction and has been associated with various diseases. However, results were partially contrasting which might have been caused by methodological difficulties to quantify mtDNA-CN.

Objective

We aimed to investigate whether mtDNA-CN is associated with peripheral arterial disease (PAD) as well as all-cause mortality and cardiovascular events during seven years of follow-up.

Methods

A total of 236 male patients with PAD from the Cardiovascular Disease in Intermittent Claudication (CAVASIC) study were compared with 249 age- and diabetes-matched controls. MtDNA-CN was measured with a well-standardized plasmid-normalized quantitative PCR-based assay determining the ratio between mtDNA-CN and nuclear DNA.

Results

Individuals in the lowest quartile of mtDNA-CN had a twofold increased risk for PAD which, however, was no longer significant after adjusting for leukocytes and platelets. About 67 of the 236 patients had already experienced a cardiovascular event at baseline and those in the lowest mtDNA-CN quartile had a 2.34-fold increased risk for these events (95% CI 1.08-5.13). During follow-up, 37 PAD patients died and 66 patients experienced a cardiovascular event. Patients in the lowest mtDNA-CN quartile had hazard ratios of 2.66 (95% CI 1.27-5.58) for all-cause-mortality and 1.82 (95% CI 1.02-3.27) for cardiovascular events compared with the combined quartile 2-4 (adjusted for age, smoking, CRP, diabetes, prevalent cardiovascular disease, leukocytes and platelets).

Conclusion

This investigation supports the hypothesis of mitochondrial dysfunction in peripheral arterial disease and shows an association of low mtDNA-CNs with all-cause-mortality and prevalent and incident cardiovascular disease in PAD patients with intermittent claudication.

SUBMITTER: Koller A

PROVIDER: S-EPMC7318579 | biostudies-literature | 2020 May

REPOSITORIES: biostudies-literature

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Publications

Mitochondrial DNA copy number is associated with all-cause mortality and cardiovascular events in patients with peripheral arterial disease.

Koller A A Fazzini F F Lamina C C Rantner B B Kollerits B B Stadler M M Klein-Weigel P P Fraedrich G G Kronenberg F F

Journal of internal medicine 20200209 5

<h4>Background</h4>Dysfunctional mitochondria have an influence on inflammation and increased oxidative stress due to an excessive production of reactive oxygen species. The mitochondrial DNA copy number (mtDNA-CN) is a potential biomarker for mitochondrial dysfunction and has been associated with various diseases. However, results were partially contrasting which might have been caused by methodological difficulties to quantify mtDNA-CN.<h4>Objective</h4>We aimed to investigate whether mtDNA-CN ...[more]

PMID: 32037598

Similar Datasets

Project description:BACKGROUND:Mitochondrial DNA copy number (mtDNA-CN) has been associated with a variety of aging-related diseases, including all-cause mortality. However, the mechanism by which mtDNA-CN influences disease is not currently understood. One such mechanism may be through regulation of nuclear gene expression via the modification of nuclear DNA (nDNA) methylation. METHODS:To investigate this hypothesis, we assessed the relationship between mtDNA-CN and nDNA methylation in 2507 African American (AA) and European American (EA) participants from the Atherosclerosis Risk in Communities (ARIC) study. To validate our findings, we assayed an additional 2528 participants from the Cardiovascular Health Study (CHS) (N?=?533) and Framingham Heart Study (FHS) (N?=?1995). We further assessed the effect of experimental modification of mtDNA-CN through knockout of TFAM, a regulator of mtDNA replication, via CRISPR-Cas9. RESULTS:Thirty-four independent CpGs were associated with mtDNA-CN at genome-wide significance (P?<?5?×?10-?8). Meta-analysis across all cohorts identified six mtDNA-CN-associated CpGs at genome-wide significance (P?<?5?×?10-?8). Additionally, over half of these CpGs were associated with phenotypes known to be associated with mtDNA-CN, including coronary heart disease, cardiovascular disease, and mortality. Experimental modification of mtDNA-CN demonstrated that modulation of mtDNA-CN results in changes in nDNA methylation and gene expression of specific CpGs and nearby transcripts. Strikingly, the "neuroactive ligand receptor interaction" KEGG pathway was found to be highly overrepresented in the ARIC cohort (P?=?5.24?×?10-?12), as well as the TFAM knockout methylation (P?= 4.41?×?10-?4) and expression (P?= 4.30?×?10-?4) studies. CONCLUSIONS:These results demonstrate that changes in mtDNA-CN influence nDNA methylation at specific loci and result in differential expression of specific genes that may impact human health and disease via altered cell signaling.

Project description:ImportanceMitochondrial dysfunction is a core component of the aging process and may play a key role in atherosclerotic cardiovascular disease. Mitochondrial DNA copy number (mtDNA-CN), which represents the number of mitochondria per cell and number of mitochondrial genomes per mitochondrion, is an indirect biomarker of mitochondrial function.ObjectiveTo determine whether mtDNA-CN, measured in an easily accessible tissue (buffy coat/circulating leukocytes), can improve risk classification for cardiovascular disease (CVD) and help guide initiation of statin therapy for primary prevention of CVD.Design, setting, and participantsProspective, population-based cohort analysis including 21?870 participants (20?163 free from CVD at baseline) from 3 studies: Cardiovascular Health Study (CHS), Atherosclerosis Risk in Communities Study (ARIC), and Multiethnic Study of Atherosclerosis (MESA). The mean follow-up was 13.5 years. The study included 11?153 participants from ARIC, 4830 from CHS, and 5887 from MESA. Analysis of the data was conducted from March 10, 2014, to January 29, 2017.ExposuresMitochondrial DNA-CN measured from buffy coat/circulating leukocytes.Main outcomes and measuresIncident CVD, which combines coronary heart disease, defined as the first incident myocardial infarction or death owing to coronary heart disease, and stroke, defined as the first nonfatal stroke or death owing to stroke.ResultsOf the 21?870 participants, the mean age was 62.4 years (ARIC, 57.9 years; MESA, 62.4 years; and CHS, 72.5 years), and 54.7% of participants were women. The hazard ratios for incident coronary heart disease, stroke, and CVD associated with a 1-SD decrease in mtDNA-CN were 1.29 (95% CI, 1.24-1.33), 1.11 (95% CI, 1.06-1.16), and 1.23 (95% CI, 1.19-1.26). The associations persisted after adjustment for traditional CVD risk factors. Addition of mtDNA-CN to the 2013 American College of Cardiology/American Heart Association Pooled Cohorts Equations for estimating 10-year hard atherosclerosis CVD risk was associated with improved risk classification (continuous net reclassification index, 0.194; 95% CI, 0.130-0.258; P?<?.001). Mitochondrial DNA-CN further improved sensitivity and specificity for the 2013 American College of Cardiology/American Heart Association recommendations on initiating statin therapy for primary prevention of ASCVD (net 221 individuals appropriately downclassified and net 15 individuals appropriately upclassified).Conclusions and relevanceMitochondrial DNA-CN was independently associated with incident CVD in 3 large prospective studies and may have potential clinical utility in improving CVD risk classification.

Project description:In people without lower extremity peripheral artery disease (PAD), mitochondrial DNA copy number declines with aging, and this decline is associated with declines in mitochondrial activity and functional performance. However, whether lower extremity ischemia is associated with lower mitochondrial DNA copy number and whether mitochondrial DNA copy number is associated with the degree of functional impairment in people with PAD is unknown. In people with and without PAD, age 65 years and older, we studied associations of the ankle-brachial index (ABI) with mitochondrial DNA copy number and associations of mitochondrial DNA copy number with functional impairment. Calf muscle biopsies were obtained from 34 participants with PAD (mean age: 73.5 years (SD 6.4), mean ABI: 0.67 (SD 0.15), mean 6-minute walk distance: 1191 feet (SD 223)) and 10 controls without PAD (mean age: 73.1 years (SD 4.7), mean ABI: 1.14 (SD 0.07), mean 6-minute walk distance: 1387 feet (SD 488)). Adjusting for age and sex, lower ABI values were associated with higher mitochondrial DNA copy number, measured in relative copy number (ABI<0.60: 914, ABI 0.60-0.90: 731, ABI 0.90-1.50: 593; p trend=0.016). The association of mitochondrial DNA copy number with the 6-minute walk distance and 4-meter walking velocity differed significantly between participants with versus without PAD ( p-value for interaction=0.001 and p=0.015, respectively). The correlation coefficient between mitochondrial DNA copy number and the 6-minute walk distance was 0.653 ( p=0.056) among people without PAD and -0.254 ( p=0.154) among people with PAD and ABI < 0.90. In conclusion, lower ABI values are associated with increased mitochondrial DNA copy number. Associations of mitochondrial DNA copy number with the 6-minute walk distance and 4-meter walking velocity significantly differed between people with versus without PAD, with stronger positive associations observed in people without PAD than in people with PAD. The cross-sectional and exploratory nature of the analyses precludes conclusions regarding causal inferences. ClinicalTrials.gov Identifier: NCT02246660.

Dataset Information

Mitochondrial DNA copy number is associated with all-cause mortality and cardiovascular events in patients with peripheral arterial disease.

Background

Objective

Methods

Results

Conclusion

Publications

Mitochondrial DNA copy number is associated with all-cause mortality and cardiovascular events in patients with peripheral arterial disease.

Similar Datasets

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