Association between global leukocyte DNA methylation, renal function, carotid intima-media thickness and plasma homocysteine in patients with stage 2-4 chronic kidney disease.

Background. Patients with chronic kidney disease (CKD) have an increased risk of cardiovascular disease (CVD). Preliminary evidence suggests a role for global DNA hypomethylation in the pathogenesis of atherosclerotic complications in CKD. The aims of this study in patients with stage 2-4 CKD were (1) to assess the association between renal function and DNA methylation, (2) to assess the association between DNA methylation and two markers of atherosclerosis [common carotid intima-media thickness (CCA-IMT)] and brachial artery endothelium-dependent, flow-mediated dilatation (BA-FMD) and (3) to examine the effect of a multi-step treatment strategy on DNA methylation. Methods. In the Anti-Oxidant Therapy In Chronic Renal Insufficiency study (ATIC-study), 93 patients with stage 2-4 CKD were included. In a randomized, double-blind, placebo-controlled design, the treatment group received pravastatin to which vitamin E was added after 6 months and homocysteine-lowering B-vitamin therapy after another 6 months. DNA methylation was assessed using tandem mass spectrometry. CCA-IMT and BA-FMD were assessed using B-mode ultrasonagraphy. Results. At baseline, global DNA methylation was not associated with the estimated glomerular filtration rate (P = 0.32) or with CCA-IMT (P = 0.62) or BA-FMD (P = 0.51). No effect of the treatment strategy including B-vitamin on global DNA methylation was found either in the total study group or within separate strata of homocysteine concentration and renal function. Conclusion. In patients with stage 2-4 CKD, global DNA methylation is not associated with renal function or with CCA-IMT or BA-FMD. A treatment strategy that includes B-vitamins did not alter global DNA methylation in these patients. These data do not support the role of DNA hypomethylation in CKD-associated vascular disease in patients with stage 2-4 CKD.