Oxidative stress and epigenetic mortality risk score: associations with all-cause mortality among elderly people
Oxidative stress (OS) has been found to be related to accelerated aging and many aging-related health outcomes. Recently, an epigenetic “mortality risk score” (MS) based on whole blood DNA methylation at 10 mortality-related CpG sites has been demonstrated to be associated with all-cause mortality. This study aimed to address the association between OS and MS, and to assess and compare their performance in the prediction of all-cause mortality. For 1448 participants aged 50–75 of the German ESTHER cohort study, the MS was derived from the DNA methylation profiles measured by Illumina HumanMethylation450K Beadchip and the levels of two urinary OS markers, 8-isoprostane (8-iso) and oxidized guanine/guanosine [including 8-hydroxy-2′-deoxyguanosine (8-oxo)], were measured by ELISA kits. Associations between OS markers and the MS were evaluated by linear and ordinal logistic regression models, and their associations with all-cause mortality were examined by Cox regression models. Both OS markers were associated with the MS at baseline. The 8-iso levels and MS, but not 8-oxo levels, were associated with all-cause mortality during a median follow-up of 15.1 years. Fully-adjusted hazard ratios (95% CI) were 1.56 (1.13–2.16) for the 4th quartile of 8-iso levels compared with the 1st, 1.71 (1.27–2.29) and 2.92 (2.03–4.18) for the moderate and high MS defined by 2–5 and > 5 CpG sites with aberrant methylation compared with a MS of 0–1, respectively. After controlling for 8-iso levels, the hazard ratios of MS remained essentially unchanged while the association of 8-iso levels with mortality was attenuated. This study demonstrates that OS is highly associated with the epigenetic MS, and the latter at the same time has a higher predictive value for all-cause mortality.
KeywordsOxidative stress DNA methylation Mortality risk score Epigenetic epidemiology Aging All-cause mortality
The ESTHER study was supported by the Baden-Württemberg state Ministry of Science, Research and Arts (Stuttgart, Germany), the Federal Ministry of Education and Research (Berlin, Germany), and the Federal Ministry of Family Affairs, Senior Citizens, Women and Youth (Berlin, Germany). Measurements of the oxidative stress markers were partly funded by the German Research Foundation (DFG, Grant No.: SCHO 1545/3-1). Xu Gao and Xīn Gào are supported by the grant from the China Scholarship Council (CSC). The authors gratefully acknowledge contributions of DKFZ Genomics and Proteomics Core Facility, especially Melanie Bewerunge-Hudler and Matthias Schick, in the processing of DNA samples and performing the laboratory work, Dr. Jonathan Heiss for providing the estimation of leukocyte distribution and Ms. Chen Chen for the language assistance.
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Conflict of interests
The authors declare that they have no competing interests.
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