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The average intake of the essential trace element selenium (Se) is below the recommendation in most European countries, possibly causing sub-optimal expression of selenoproteins. It is still unclear how a suboptimal Se status may affect health. To mimic this situation, mice were fed one of three physiologically relevant amounts of Se. We focused on the liver, the organ most sensitive to changes in the Se supply indicated by hepatic glutathione peroxidase activity. In addition, liver is the main organ for synthesis of methyl groups and glutathione via one-carbon metabolism. Accordingly, the impact of Se on global DNA methylation, methylation capacity, and gene expression was assessed. We observed higher global DNA methylation indicated by LINE1 methylation, and an increase of the methylation potential as indicated by higher S-adenosylmethionine (SAM)/S-adenosylhomocysteine (SAH) ratio and by elevated mRNA expression of serine hydroxymethyltransferase in both or either of the Se groups. Furthermore, increasing the Se supply resulted in higher plasma concentrations of triglycerides. Hepatic expression of glycolytic and lipogenic genes revealed consistent Se-dependent up-regulation of glucokinase. The sterol regulatory element-binding transcription factor 1 (Srebf1) was also up-regulated by Se. Both effects were confirmed in primary hepatocytes. In contrast to the overall Se-dependent increase of methylation capacity, the up-regulation of Srebf1 expression was paralleled by reduced local methylation of a specific CpG site within the Srebf1 gene. Thus, we provided evidence that Se-dependent effects on lipogenesis involve epigenetic mechanisms., (Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: Deficiencies of folate, vitamins B12 and D are common age-related conditions. Vitamin B12 and folate are necessary for DNA methylation. Telomeres appear to be regulated by DNA methylation. Here, we study the effect of B vitamins supplementation on telomere length and global DNA methylation in a prospective study., Methods: In total, 60 elderly subjects were supplemented for 1 year with either vitamin B12, B6, folate, vitamin D and calcium (group A n = 31) or only vitamin D and calcium (group B n = 29). LINE-1 methylation, relative telomere length (T/S), vitamin B12, folate, homocysteine (tHcy) , 5-methyltetrahydrofolate (5-methylTHF), S-adenosylhomocysteine (SAH), S-adenosylmethionine (SAM), cystathionine and vitamin D were quantified before and after supplementation., Results: At baseline, tHcy was high, vitamin D was low, and T/S did not differ between groups A and B. Vitamin supplementation increased LINE-1 methylation in group A at site 317 but reduced LINE-1 methylation in group B at site 327. There was no correlation between T/S and LINE-1 methylation at baseline. Multiple backward regression analysis revealed baseline tHcy and 5-methylTHF are significant predictors of T/S. After supplementation in group B but not in group A, LINE-1 methylation correlated inversely with T/S, and LINE-1 methylation variation was an independent predictor of T/S variation. B vitamins decreased tHcy significantly in group A. Multiple backward regression analysis showed 5-methylTHF in group A and tHcy in group B were significant predictors for LINE-1 methylation. At baseline, the lower LINE-1 methylation observed in subjects with 5-methylTHF >10 nmol/l was in agreement with a reduced methyl group transfer due to a lower SAM formation. In group B, an increase in telomere length was correlated with lower LINE-1 methylation. Subjects with hyperhomocysteinemia >12 µmol/L had compared to those with normal tHcy a reduced LINE-1 methylation accompanied by a higher SAM and SAH (that inhibits demethylation of SAM) as well as lower 5-methylTHF. Additionally, subjects with tHcy > 12 µmol/L had longer telomeres when compared with subjects having tHcy < 12 µmol/L., Conclusions: The results suggest a possible effect of B vitamins for telomere biology in blood cells. Suboptimal B vitamins status and hyperhomocysteinemia are associated with altered DNA methylation and telomere length. These data have to be confirmed in future studies.

Human monocytes are a heterogeneous cell population consisting of 3 subsets: classical CD14++CD16-, intermediate CD14++CD16+ and nonclassical CD14+CD16++ monocytes. Via poorly characterized mechanisms, intermediate monocyte counts rise in chronic inflammatory diseases, among which chronic kidney disease is of particular epidemiologic importance. DNA methylation is a central epigenetic feature that controls hematopoiesis. By applying next-generation Methyl-Sequencing we now tested how far the 3 monocyte subsets differ in their DNA methylome and whether uremia induces DNA methylation changes in differentiating monocytes. We found that each monocyte subset displays a unique phenotype with regards to DNA methylation. Genes with differentially methylated promoter regions in intermediate monocytes were linked to distinct immunological processes, which is in line with results from recent gene expression analyses. In vitro, uremia induced dysregulation of DNA methylation in differentiating monocytes, which affected several transcription regulators important for monocyte differentiation (e.g., FLT3, HDAC1, MNT) and led to enhanced generation of intermediate monocytes. As potential mediator, the uremic toxin and methylation inhibitor S-adenosylhomocysteine induced shifts in monocyte subsets in vitro, and associated with monocyte subset counts in vivo. Our data support the concept of monocyte trichotomy and the distinct role of intermediate monocytes in human immunity. The shift in monocyte subsets that occurs in chronic kidney disease, a proinflammatory condition of substantial epidemiological impact, may be induced by accumulation of uremic toxins that mediate epigenetic dysregulation.

Objective: The adaptor protein p66Shc generates mitochondrial reactive oxygen species and translates oxidative signals into apoptosis. We aimed to analyze potential alterations in total methylation and in p66Shc activation in placental tissues from women delivering intrauterine growth restricted neonates (IUGR) versus appropriate for gestational age (AGA) and small for gestational age (SGA) neonates., Method: DNA methylation of the p66Shc promoter and of long interspersed nuclear elements (LINE-1), as a marker for total methylation, was quantified by automatic pyrosequencing in 15 IUGR, 25 AGA and 15 SGA placentas. Placental gene expression of p66Shc was determined by TaqMan real-time polymerase chain reaction., Results: No significant difference was found for LINE-1 methylation between IUGR, AGA and SGA newborns. DNA methylation of the p66Shc promoter was significantly decreased in the IUGR compared with the AGA group (p < 0.0001) and the SGA group (p < 0.0001). However, analysis of placental p66Shc gene expression did not show a significant difference between the three groups., Conclusion: It remains speculative if the decreased p66Shc promoter methylation might play a role in the pathophysiology of endothelial dysfunction and cardiovascular disease after IUGR., (© 2013 John Wiley & Sons, Ltd.)

Background: Disturbed DNA methylation is causally related to chronic diseases like cancer and atherosclerosis. B vitamins are cofactors required for methyl group synthesis and may therefore affect DNA methylation. Vitamin D has epigenetic effects. We tested if B and D vitamin supplementation has an effect on genomic long interspersed nuclear element-1 (LINE-1) methylation and the metabolites S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH)., Methods: Fifty subjects (median age 68.0 years) were supplemented with a daily oral dose of B vitamins (500 µg folic acid, 500 µg vitamin B12 and 50 mg vitamin B6), 1200 IU vitamin D and 456 mg calcium. Fasting blood samples were collected before and after 1 year of supplementation. LINE-1 methylation was determined in genomic DNA from blood cells as a surrogate for whole genome methylation. In addition, SAM, SAH and total homocysteine (tHcy) were measured in plasma samples., Results: Plasma homocysteine decreased significantly after supplementation (12.8 vs. 9.1 µmol/L; p<0.05), whereas SAM, SAH, the SAM/SAH ratio and LINE-1 methylation did not change significantly. LINE-1 methylation was not significantly correlated with SAH, homocysteine or B vitamins., Conclusions: Long-term vitamin B supplementation had no effect on LINE-1 methylation in blood cells nor on plasma levels of SAM and SAH. Vitamin B and D supplementation seems to have no effect on DNA methylation, especially in cases where no severe deficiency exists.

Background: Accelerated atherosclerosis is a hallmark of chronic kidney disease (CKD). Although the role of epigenetic dysregulation in atherosclerosis is increasingly appreciated, only a few studies focused on epigenetics in CKD-associated cardiovascular disease, virtually all of which assessed epigenetic dysregulation globally. We hypothesized that gene-specific epigenetic dysregulation in CKD exists, affecting genes pertinent to inflammation and atherosclerosis., Methods and Results: Ten clinically stable patients undergoing hemodialysis therapy and 10 healthy age- and sex-matched controls were recruited. Genome-wide analysis of DNA methylation was performed by SuperTAG methylation-specific digital karyotyping, in order to identify genes differentially methylated in CKD. Analysis of 27 043 436 tags revealed 4288 genomic loci with differential DNA methylation (P<10(-10)) between hemodialysis patients and control subjects. Annotation of UniTags to promoter databases allowed us to identify 52 candidate genes associated with cardiovascular disease and 97 candidate genes associated with immune/infection diseases. These candidate genes could be classified to distinct proatherogenic processes, including lipid metabolism and transport (eg, HMGCR, SREBF1, LRP5, EPHX2, and FDPS), cell proliferation and cell-cycle regulation (eg, MIK67, TP53, and ALOX12), angiogenesis (eg, ANGPT2, ADAMTS10, and FLT4), and inflammation (eg, TNFSF10, LY96, IFNGR1, HSPA1A, and IL12RB1)., Conclusions: We provide a comprehensive analysis of genome-wide epigenetic alterations in CKD, identifying candidate genes associated with proatherogenic and inflammatory processes. These results may spur further research in the field of epigenetics in kidney disease and point to new therapeutic strategies in CKD-associated atherosclerotic disease.

Background: p66Shc is a stress response protein and partially regulated by epigenetic modifications. Mice lacking p66Shc have reduced atherosclerosis, increased resistance to oxidative stress and a prolonged life time. The aim of the present study was to compare promoter methylation of the p66Shc gene between healthy controls and patients with end-stage renal disease (ESRD). There are two reasons for studying patients with ESRD. First, patients with ESRD have a disturbed homocysteine metabolism, and second an increased risk of morbidity and mortality from cardiovascular disease is a constant finding in these patients., Methods: In our study, we measured fasting levels of homocysteine, S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH) and 8-isoprostane in 22 patients and in 26 healthy, age- and sex-matched controls. The methylation of the p66Shc promoter and Line-1, as surrogate marker of whole genome methylation was quantified in peripheral blood mononuclear cells., Results: In comparison to the control group, homocysteine, SAM, SAH, 8-isoprostane and whole genome methylation were significantly elevated in ESRD patients, while the p66Shc promoter methylation was significantly reduced. A significant correlation was found between SAH and p66Shc promoter methylation in the patient group. This observation underlines the role of SAH as a potent inhibitor of methyltransferases. Using backward regression analysis, we demonstrated that 8-isoprostane has a significant influence on p66Shc promoter methylation. In the control group and in patients with ESRD, increasing 8-isoprostane levels were linked to an elevated promoter methylation., Conclusions: Under physiological conditions, based on the results of the control group, the p66Shc expression is more silenced through epigenetic modifications. The atherosclerotic risk is dramatically increased in ESRD patients; therefore, our experimental results of methylation are in accordance with the clinical situation.

Vegetarians have a lower intake of vitamin B12 than omnivores do. Vitamin B12 deficiency (holotranscobalamin II <35 pmol/L or methylmalonic acid >271 nmol/L) was found in 58% of 71 vegetarians studied. Higher homocysteine levels (>12 micromol/L) found in 45% indicate disturbed remethylation of homocysteine to methionine. The methylation of DNA is strongly linked to homocysteine metabolism. Since DNA methylation is an important epigenetic factor in the regulation of gene expression, alteration of the methylation pattern has been associated with aging, cancer, atherosclerosis and other diseases. Three observations indicate that DNA methylation could be diminished by a vegetarian lifestyle. The vegetarian diet has a low content of methionine, remethylation of homocysteine is reduced by vitamin B12 deficiency and elevated homocysteine levels can induce the generation of S-adenosylhomocysteine (SAH), a potent inhibitor of methyltransferases. In our study we observed a significant correlation between SAH and whole-genome methylation (r=-0.36, p<0.01). This observation underlines the role of SAH as a potent inhibitor of methyltransferases. The methylation status was not correlated with homocysteine or S-adenosylemethionine (SAM). These results indicate that the degree of methylation does not depend on the supply of methyl groups and that the reverse generation of SAH has no influence. In addition to whole-genome methylation, the specific promoter methylation of the p66Shc gene was studied. However, the latter did not correlate with SAH, SAM or homocysteine. Obviously, the promoter methylation of the p66Shc gene is controlled in a specific way, without following the general regulating influence of SAH. In conclusion, an inhibitory effect of SAH on whole-genome methylation was found, but from our data no interaction between vegetarian lifestyle and DNA methylation could be determined.

Background: p66 Shc is a stress response protein and partially regulated by epigenetic modifications. Mice lacking p66 Shc have reduced atherosclerosis, increased resistance to oxidative stress and a prolonged life time. The aim of the present study was to compare promoter methylation of the p66 Shc gene between healthy controls and patients with end-stage renal disease (ESRD). There are two reasons for studying patients with ESRD. First, patients with ESRD have a disturbed homocysteine metabolism, and second an increased risk of morbidity and mortality from cardiovascular disease is a constant finding in these patients. Methods: In our study, we measured fasting levels of homocysteine, S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH) and 8-isoprostane in 22 patients and in 26 healthy, age- and sex-matched controls. The methylation of the p66 Shc promoter and Line-1, as surrogate marker of whole genome methylation was quantified in peripheral blood mononuclear cells. Results: In comparison to the control group, homocysteine, SAM, SAH, 8-isoprostane and whole genome methylation were significantly elevated in ESRD patients, while the p66 Shc promoter methylation was significantly reduced. A significant correlation was found between SAH and p66 Shc promoter methylation in the patient group. This observation underlines the role of SAH as a potent inhibitor of methyltransferases. Using backward regression analysis, we demonstrated that 8-isoprostane has a significant influence on p66 Shc promoter methylation. In the control group and in patients with ESRD, increasing 8-isoprostane levels were linked to an elevated promoter methylation. Conclusions: Under physiological conditions, based on the results of the control group, the p66 Shc expression is more silenced through epigenetic modifications. The atherosclerotic risk is dramatically increased in ESRD patients; therefore, our experimental results of methylation are in accordance with the clinical situation. Clin Chem Lab Med 2007;45:1764–70. [ABSTRACT FROM AUTHOR]