Association between global leukocyte DNA methylation and cardiovascular risk in postmenopausal women

Blood-Based DNA Methylation Biomarkers to Identify Risk and Progression of Cardiovascular Disease

Non-communicable diseases (NCDs) are the leading cause of death worldwide, with cardiovascular disease (CVD) accounting for half of all NCD-related deaths. The biological onset of CVD may occur long before the development of clinical symptoms, hence the urgent need to understand the molecular alterations underpinning CVD, which would facilitate intervention strategies to prevent or delay the onset of the disease. There is evidence to suggest that CVD develops through a complex interplay between genetic, lifestyle, and environmental factors. Epigenetic modifications, including DNA methylation, serve as proxies linking genetics and the environment to phenotypes and diseases. In the past decade, a growing list of studies has implicated DNA methylation in the early events of CVD pathogenesis. In this regard, screening for these epigenetic marks in asymptomatic individuals may assist in the early detection of CVD and serve to predict the response to therapeutic interventions. This review discusses the current literature on the relationship between blood-based DNA methylation alterations and CVD in humans. We highlight a set of differentially methylated genes that show promise as candidates for diagnostic and prognostic CVD biomarkers, which should be prioritized and replicated in future studies across additional populations. Finally, we discuss key limitations in DNA methylation studies, including genetic diversity, interpatient variability, cellular heterogeneity, study confounders, different methodological approaches used to isolate and measure DNA methylation, sample sizes, and cross-sectional study design.

An Evaluation of DNA Methylation Levels and Sleep in Relation to Hot Flashes: A Cross-Sectional Study

Objectives: We aimed to evaluate the DNA methylation levels in perimenopausal and postmenopausal women, measured through Long Interspersed Element-1 (LINE-1) and Alu, and the sleep parameters in relation to the presence of hot flashes (HFs). Methods: This cross-sectional study included 30 peri- or postmenopausal women aged between 45 and 55. The menopausal status was determined according to STRAW + 10 criteria and all participants had a low cardiovascular disease (CVD) risk profile determined by Framingham risk score. The sample was divided into two groups based on the presence or absence of HFs documented in their medical history during their initial visit: Group 1 (n = 15) with HFs present and Group 2 (n = 15) with HFs absent. The patients had polysomnography test and HFs were recorded both by sternal skin conductance and self-report overnight. Genomic DNA was extracted from the women's blood and methylation status was analyzed by fluorescence-based real-time quantitative PCR. The quantified value of DNA methylation of a target gene was normalized by β-actin. The primary outcome was the variation in methylation levels of LINE-1 and Alu and sleep parameters according to the presence of HFs. Results: LINE-1 and Alu methylation levels were higher in Group 1 (HFs present), although statistically non-significant. LINE-1 methylation levels were negatively correlated with age. Sleep efficiency was statistically significantly lower for women in Group 1 (HFs present) (74.66% ± 11.16% vs. 82.63% ± 7.31%; p = 0.03). The ratio of duration of awakening to total sleep time was statistically significantly higher in Group 1 (HFs present) (22.38% ± 9.99% vs. 15.07% ± 6.93, p = 0.03). Objectively recorded hot flashes were significantly higher in Group 1 (4.00 ± 3.21 vs. 1.47 ± 1.46, p = 0.03). None of the cases in Group 2 self-reported HF despite objectively recorded HFs during the polysomnography. The rate of hot flash associated with awakening was 41.4% in the whole sample. Conclusions: Women with a history of hot flashes exhibited lower sleep efficiency and higher awakening rates. Although a history of experiencing hot flashes was associated with higher LINE-1 and Alu methylation levels, no statistical significance was found. Further studies are needed to clarify this association. This study was funded by the Scientific Research Projects Coordination Unit of Istanbul University-Cerrahpasa. Project number: TTU-2021-35629.

Exercise-induced redox modulation as a mediator of DNA methylation in health maintenance and disease prevention

The evidence for physical activity (PA) as a major public health preventive approach and a potent medical therapy has increased exponentially in the last decades. The biomolecular mechanisms supporting the associations between PA and/or structured exercise training with health maintenance and disease prevention are not completely characterized. However, increasing evidence pointed out the role of epigenetic modifications in exercise adaptation and health-enhancing PA throughout life, DNA methylation being the most intensely studied epigenetic modification induced by acute and chronic exercise. The current data on the modulation of DNA methylation determined by physically active behavior or exercise interventions points out genes related to energy regulation, mitochondrial function, and biosynthesis, as well as muscle regeneration, calcium signaling pathways, and brain plasticity, all consistent with the known exercise-induced redox signaling and/or reactive oxygen species (ROS) unbalance. Thus, the main focus of this review is to discuss the role of ROS and redox-signaling on DNA methylation profile and its impact on exercise-induced health benefits in humans.

Proteomic and Global DNA Methylation Modulation in Lipid Metabolism Disorders with a Marine-Derived Bioproduct

Dyslipidemia is a significant risk factor for cardiovascular disease and stroke. Our recent findings showed that RCI-1502, a bioproduct derived from the muscle of the European S. pilchardus, has lipid-lowering effects in the liver and heart in high-fat diet (HFD) fed mice. In the present follow-up study, we investigated the therapeutic potential of RCI-1502 on gene expression and DNA methylation in HFD-fed mice and in patients with dyslipidemia. Using LC-MS/MS, we identified 75 proteins in RCI-1502 that are primarily involved in binding and catalytic activity and which regulate pathways implicated in cardiovascular diseases. In HFD-fed mice, RCI-1502 treatment significantly reduced the expression of cardiovascular disease-related genes, including vascular cell adhesion molecule and angiotensin. RCI-1502 also decreased DNA methylation levels, which were elevated in HFD-fed mice, to levels similar to those in control animals. Furthermore, peripheral blood leukocyte DNA from dyslipidemic patients exhibited higher DNA methylation levels than healthy individuals, suggesting a potential association with cardiovascular risk. Serum analysis also revealed that RCI-1502 treatment regulated cholesterol and triglyceride levels in patients with dyslipidemia. Our findings appear to suggest that RCI-1502 is an epigenetic modulator for the treatment of cardiovascular diseases, specifically in individuals with dyslipidemia.

Increasing Specificity of Targeted DNA Methylation Editing by Non-Enzymatic CRISPR/dCas9-Based Steric Hindrance

As advances in genome engineering inch the technology towards wider clinical use-slowed by technical and ethical hurdles-a newer offshoot, termed "epigenome engineering", offers the ability to correct disease-causing changes in the DNA without changing its sequence and, thus, without some of the unfavorable correlates of doing so. In this review, we note some of the shortcomings of epigenetic editing technology-specifically the risks involved in the introduction of epigenetic enzymes-and highlight an alternative epigenetic editing strategy using physical occlusion to modify epigenetic marks at target sites without a requirement for any epigenetic enzyme. This may prove to be a safer alternative for more specific epigenetic editing.

DNA methylation and cardiovascular disease in humans: a systematic review and database of known CpG methylation sites

BACKGROUND

Cardiovascular disease (CVD) is the leading cause of death worldwide and considered one of the most environmentally driven diseases. The role of DNA methylation in response to the individual exposure for the development and progression of CVD is still poorly understood and a synthesis of the evidence is lacking.

RESULTS

A systematic review of articles examining measurements of DNA cytosine methylation in CVD was conducted in accordance with PRISMA (preferred reporting items for systematic reviews and meta-analyses) guidelines. The search yielded 5,563 articles from PubMed and CENTRAL databases. From 99 studies with a total of 87,827 individuals eligible for analysis, a database was created combining all CpG-, gene- and study-related information. It contains 74,580 unique CpG sites, of which 1452 CpG sites were mentioned in ≥ 2, and 441 CpG sites in ≥ 3 publications. Two sites were referenced in ≥ 6 publications: cg01656216 (near ZNF438) related to vascular disease and epigenetic age, and cg03636183 (near F2RL3) related to coronary heart disease, myocardial infarction, smoking and air pollution. Of 19,127 mapped genes, 5,807 were reported in ≥ 2 studies. Most frequently reported were TEAD1 (TEA Domain Transcription Factor 1) and PTPRN2 (Protein Tyrosine Phosphatase Receptor Type N2) in association with outcomes ranging from vascular to cardiac disease. Gene set enrichment analysis of 4,532 overlapping genes revealed enrichment for Gene Ontology molecular function "DNA-binding transcription activator activity" (q = 1.65 × 10^-11) and biological processes "skeletal system development" (q = 1.89 × 10^-23). Gene enrichment demonstrated that general CVD-related terms are shared, while "heart" and "vasculature" specific genes have more disease-specific terms as PR interval for "heart" or platelet distribution width for "vasculature." STRING analysis revealed significant protein-protein interactions between the products of the differentially methylated genes (p = 0.003) suggesting that dysregulation of the protein interaction network could contribute to CVD. Overlaps with curated gene sets from the Molecular Signatures Database showed enrichment of genes in hemostasis (p = 2.9 × 10^-6) and atherosclerosis (p = 4.9 × 10^-4).

CONCLUSION

This review highlights the current state of knowledge on significant relationship between DNA methylation and CVD in humans. An open-access database has been compiled of reported CpG methylation sites, genes and pathways that may play an important role in this relationship.

Association of nutritional glycaemic indices with global DNA methylation patterns: results from the Moli-sani cohort

BACKGROUND

High dietary glycaemic index (GI) and load (GL) have been associated with increased risk of various cardiometabolic conditions. Among the molecular potential mechanisms underlying this relationship, DNA methylation has been studied, but a direct link between high GI and/or GL of diet and global DNA methylation levels has not been proved yet. We analyzed the associations between GI and GL and global DNA methylation patterns within an Italian population.

RESULTS

Genomic DNA methylation (5mC) and hydroxymethylation (5hmC) levels were measured in 1080 buffy coat samples from participants of the Moli-sani study (mean(SD) = 54.9(11.5) years; 52% women) via ELISA. A 188-item Food Frequency Questionnaire was used to assess food intake and dietary GI and GL for each participant were calculated. Multiple linear regressions were used to investigate the associations between dietary GI and GL and global 5mC and 5hmC levels, as well as the proportion of effect explained by metabolic and inflammatory markers. We found negative associations of GI with both 5mC (β (SE) = - 0.073 (0.027), p = 0.007) and 5hmC (- 0.084 (0.030), p = 0.006), and of GL with 5mC (- 0.14 (0.060), p = 0.014). Circulating biomarkers did not explain the above-mentioned associations. Gender interaction analyses revealed a significant association of the gender-x-GL interaction with 5mC levels, with men showing an inverse association three times as negative as in women (interaction β (SE) = - 0.16 (0.06), p = 0.005).

CONCLUSIONS

Our findings suggest that global DNA methylation and hydroxymethylation patterns represent a biomarker of carbohydrate intake. Based on the differential association of GL with 5mC between men and women, further gender-based separate approaches are warranted.

Identification of an Epigenetic Signature for Coronary Heart Disease in Postmenopausal Women’s PBMC DNA

Menopause is accompanied with an increased risk of cardiovascular disease. DNA methylation may have a significant impact on postmenopausal women's development of coronary heart disease. DNA methylation alterations in peripheral blood mononuclear cells (PBMCs) from women with coronary heart disease and healthy controls were detected using the Illumina Infinium MethylationEPIC BeadChip platform in this work. We employed Sangerbox technology and the GO and KEGG databases to further study the pathogenesis of coronary heart disease in postmenopausal women. After that, we used functional epigenetic module analysis and Cytoscape to remove the hub genes from the protein–protein interaction networks. Five genes (FOXA2, PTRD, CREB1, CTNAP2, and FBN2) were the hub genes. Lipid accumulation, endothelial cell failure, inflammatory responses, monocyte recruitment and aggregation, and other critical biological processes were all influenced by these genes. Finally, we employed methylation-specific PCR to demonstrate that FOXA2 was methylated at a high level in postmenopausal women with coronary heart disease. To better understand coronary heart disease in postmenopausal women's molecular mechanisms, our study examine the major factors contributing to the state of DNA methylation modification, which will help discover novel diagnostic tools and treatment options.

Global DNA methylation mediates the association between serum perfluorooctane sulfonate and carotid intima-media thickness in young and middle-aged Taiwanese populations

PURPOSE

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are a group of synthetic chemicals used in the manufacture of many everyday products. Previous reports have shown PFAS exposure may contribute to cardiovascular diseases (CVD). Recent studies have also identified a critical role for DNA methylation, a model of epigenetic regulation, in the pathogenesis of CVD. Additionally, PFAS has been shown to affect DNA methylation. Our previous study reported the positive association between serum perfluorooctane sulfonate (PFOS) levels and mean carotid intima-media thickness (CIMT), a biomarker of arteriosclerosis, in a cohort composed of adolescent and young adult Taiwanese. However, the contribution of DNA methylation in the mechanism of PFOS-induced arteriosclerosis has never been explored in previous literature.

APPROACH AND RESULTS

In this cross-sectional study, we included 1425 young and middle-aged Taiwanese individuals (12-63 years) to investigate the correlation between serum PFOS levels, 5mdC/dG (a global DNA methylation marker) and the mean CIMT. We showed that the positive association between serum PFOS levels, 5mdC/dG, and mean CIMT. The regression coefficients of mean CIMT with a one-unit increase in ln-PFOS concentration were higher when the levels of 5mdC/dG were above the 50th percentile in the multiple regression analysis. In the structural equation model (SEM), the results showed that serum PFOS levels were directly correlated with mean CIMT and indirectly correlated with CIMT through 5mdC/dG.

CONCLUSIONS

Our results showed that PFOS exposure has direct associations on arteriosclerosis and indirect direct associations on arteriosclerosis through DNA methylation. The results suggest that DNA methylation might regulate the relationship between PFOS and arteriosclerosis in the study subjects. Additional works are required to understand the causal inference between PFOS, DNA methylation, and arteriosclerosis.

Global DNA methylation mediates the association between urine mono-2-ethylhexyl phthalate and serum apoptotic microparticles in a young Taiwanese population

Di-(2-ethylhexyl) phthalate (DEHP) has been used as a plasticizer for decades. Recent research evidence has revealed that environmental factors can alter vascular endothelial cell function through DNA methylation. However, no previous in vitro/vivo study has explored the role of DNA methylation in DEHP exposure and vascular endothelial cell function. In the present study, we enrolled 793 subjects aged 12 to 30 years from a young Taiwanese cohort to investigate the association between mono-2-ethylhexyl phthalate (MEHP) (urine DEHP metabolite), 5mdC/dG (global DNA methylation marker), CD31⁺/CD42a^-, CD31⁺/CD42a⁺, and CD14 (apoptotic microparticles of vascular cells). In multiple regression analyses, the levels of mono-2-ethylhexyl phthalate (MEHP) were positively associated with 5mdC/dG and all three apoptotic microparticles. In addition, the regression coefficients between MEHP and the three types of apoptotic microparticles were higher when the 5mdC/dG levels were higher than the 50th percentile. In the structural equation model (SEM), we found that MEHP had a direct correlation with CD31⁺/CD42a^- and an indirect association with CD31⁺/CD42a^- through the effect of 5mdC/dG. Moreover, MEHP only had a direct association with CD31⁺/CD42a⁺ and an indirect association with CD14. In conclusion, the results show that global DNA methylation mediates the relationship between MEHP and apoptotic microparticles. These findings indicate that DNA methylation may play a role in the pathogenesis of DEHP-induced endothelial cell apoptosis in humans. Further studies are needed to clarify the causal inference.

Overview of Polyamines as Nutrients for Human Healthy Long Life and Effect of Increased Polyamine Intake on DNA Methylation

Polyamines, spermidine and spermine, are synthesized in every living cell and are therefore contained in foods, especially in those that are thought to contribute to health and longevity. They have many physiological activities similar to those of antioxidant and anti-inflammatory substances such as polyphenols. These include antioxidant and anti-inflammatory properties, cell and gene protection, and autophagy activation. We have first reported that increased polyamine intake (spermidine much more so than spermine) over a long period increased blood spermine levels and inhibited aging-associated pathologies and pro-inflammatory status in humans and mice and extended life span of mice. However, it is unlikely that the life-extending effect of polyamines is exerted by the same bioactivity as polyphenols because most studies using polyphenols and antioxidants have failed to demonstrate their life-extending effects. Recent investigations revealed that aging-associated pathologies and lifespan are closely associated with DNA methylation, a regulatory mechanism of gene expression. There is a close relationship between polyamine metabolism and DNA methylation. We have shown that the changes in polyamine metabolism affect the concentrations of substances and enzyme activities involved in DNA methylation. I consider that the increased capability of regulation of DNA methylation by spermine is a key of healthy long life of humans.

Methylenetetrahydrofolate reductase gene polymorphism, global DNA methylation and blood pressure: a population based study from North India

BACKGROUND

Hypertension is a complex disorder affected by gene-environment interactions. Methylenetetrahydrofolate reductase (MTHFR) gene is one of the genes in One Carbon Metabolic (OCM) pathway that affects both blood pressure and epigenetic phenomenon. MTHFR C677T gene polymorphism leads to reduced methylation capacity via increased homocysteine concentrations. Global DNA methylation (5mC%) also gets affected in conditions such as hypertension. However, no study is found to understand hypertension in terms of both genetics and epigenetics. The present study aims to understand the relation between methylation, MTHFR C677T gene polymorphism and hypertension. It also tries to understand relation (if any) between methylation and anti-hypertensive drugs.

METHODS

This is a cross-sectional study where data were collected from a total of 1634 individuals of either sex in age group 35-65 years. Hypertensives (SBP ≥ 140 mm Hg and DBP ≥ 90 mm Hg) (on treatment/not on treatment) and absolute controls were 236 (cases) and 307 (controls), respectively. All the samples were subjected to MTHFR C677T gene polymorphism screening (PCR-RFLP) and global DNA methylation assay (ELISA based colorimetric assay). Results of both the analyses were obtained on 218 cases, 263 controls.

RESULTS

Median 5mC% was relatively lower among cases (p > 0.05) compared to controls, despite controlling for confounders (age, sex, smoking, alcohol, diet) (r2-0.92, p-0.08). Cases not on medication had significantly reduced 5mC% compared to controls (p < 0.05), despite adjusting for confounders (r2-0.857, p-0.01). Among cases (irrespective of treatment), there was a significant variation in 5mC% across the three genotypes i.e. CC, CT and TT, with no such variation among controls. Cases (not on medication) with TT genotype had significantly lower methylation levels compared to the TT genotype controls and cases (on medication) (p < 0.01).

CONCLUSION

Global DNA hypomethylation seems to be associated with hypertension and antihypertensive drugs seem to improve methylation. Hypertensive individuals with TT genotype but not on medication are more likely to be prone to global DNA hypomethylation. Important precursors in OCM pathway include micronutrients such as vitamin B-12, B-9 and B-6; their nutritional interventions (either dietary or supplement) may serve as strategies to prevent hypertension at population level. However, more epidemiological-longitudinal studies are needed for further validation.

Evaluation of the influence of global DNA methylation level in patients with acute coronary syndrome

DNA methylation is one of the mechanisms of epigenetic regulation and is observed in mammals to maintain a normal expression pattern of the genes. Aberrant profiles of DNA methylation have already been associated with cardiovascular diseases. We evaluated 190 patients with Acute Coronary Syndrome (ACS) and 75 patients without ACS (non-ACS). Patient severity was assessed by the TIMI risk score, and both levels of global DNA methylation (ACS = 190; non-ACS = 75), stratified in expected group (male ≥ 65 years; female ≥ 55 years) and early group (male < 65 years; female < 55 years). As results, the ACS and non-ACS groups showed different levels of global DNA methylation, and patients with ACS were more methylated (p = 0.0121). Patients with ACS, showed a difference (p < 0.0001) in methylation profiles between groups. The low TIMI group had a higher level of DNA methylation, while the intermediate / high group showed a decreased methylation pattern. A negative correlation was observed between the level of global methylation and the increase in age (p = 0.0387; r = -0.15), which became hypomethylated over the years. The hypermethylated global DNA profile by its association with the development of ACS can be a potential biomarker.

The association between urine di-(2-ethylhexyl) phthalate metabolites, global DNA methylation, and subclinical atherosclerosis in a young Taiwanese population

Di-(2-ethylhexyl) phthalate (DEHP) has been utilized in many products for years. DEHP exposure has been linked to cardiovascular diseases (CVD) and its risk factors. Recent evidence has found a crucial role for epigenetics, including DNA methylation, in CVD. Moreover, DEHP exposure has proved to alter DNA methylation in epidemiological studies. However, the interplay between DEHP exposure, global DNA methylation, and atherosclerosis has never been reported. In this current study, we enrolled 793 participants (12-30 years) from a Taiwanese population to investigate the association between concentrations of DEHP metabolites, 5mdC/dG (global DNA methylation marker) and the carotid intima-media thickness (CIMT). The results showed urine mono-2-ethylhexyl phthalate (MEHP) level was positively correlated with 5mdC/dG and CIMT, respectively. In logistic regression models, the odds ratios (OR) of thicker CIMT (greater than 75^th percentile) with one unit increase in ln-MEHP level was higher when levels of 5mdC/dG were above 50%. In structural equation model, the result showed urine MEHP levels are directly associated with CIMT. Moreover, MEHP had an indirect association with CIMT through the 5mdC/dG after adjusting other confounding effects. In the current study, urine DEHP metabolite levels were positively correlated with 5mdC/dG, and CIMT. Our results showed DEHP had a direct and indirect association with CIMT through the 5mdC/dG. The finding implies that DNA methylation may mediate the association between DEHP exposures and subclinical atherosclerosis in this young population. Future effort is needed to elucidate the causal relationship between DEHP exposure, DNA methylation and CVD.

Association of genetic and epigenetic variants in one-carbon metabolism gene with folate treatment response in hyperhomocysteinaemia

BACKGROUND

Folate supplementation treatment is the first-line therapy in hyperhomocysteinaemia (HHcy). Up to 40% of HHcy patients do not benefit from folate therapy. Genetic and epigenetic factors of one-carbon metabolism (1-CM) might be identified as a predictor of folate supplementation treatment response. In the present study, we attempt to identify whether genetic and epigenetic factors might predict folate treatment response.

METHODS

A total of 230 patients with HHcy were involved in this prospective cohort study. Differences between baseline concentrations and concentrations obtained at 90 days of treatment were calculated to evaluate the treatment response. General linear models and Pearson correlation was used to explore associations among single-nucleotide polymorphisms (SNPs), DNA methylation, and folate treatment response. Finally, mediation analysis was performed to investigate whether DNA methylation of MTRR mediates the association between SNPs and treatment response.

RESULTS

MTHFD rs1950902 and MTRR rs162036, rs1801394 was associated with the folate treatment response (P = 0.000, 0.048, and 0.043, respectively). CBS and CBS_2 DNA methylation was significantly associated with folate treatment response (P = 0.0009 and < 0.001). DNA methylation of MTHFR, MTR, and MTRR was also significantly associated with folate treatment response (P < 0.001). DNA methylation of MTRR and MTRR_1 mediated 40.71% and 40.47% of the effect of rs1801394 on folate treatment response, respectively.

CONCLUSIONS

Our results indicated that the 1-CM gene SNPs and DNA methylation was associated with folate treatment response and can be further evaluated relationship between SNPs and DNA methylation in 1-CM with treatment response in a larger sample.

Association of global DNA hypomethylation with post-operative cognitive dysfunction in elderly patients undergoing hip surgery

BACKGROUND

Post-operative cognitive dysfunction (POCD) is a decline of cognitive status that commonly occurs after surgery in elderly patients. Whether DNA methylation is associated with the development of POCD remains unclear.

METHODS

Subjects (N = 124) older than 65 years-of-age undergoing hip replacement surgery were enrolled. A battery of neuropsychiatric tests was used to examine the perioperative cognitive function of the patients. Early POCD was analyzed using the reliable change index (RCI), and subjects were diagnosed with POCD if RCI < -1.96. Peripheral leukocyte DNA was isolated, and DNA methylation was measured via 5-methylcytosine (mC) using Elisa.

RESULTS

Twenty-four patients (19.4%) developed early POCD. There was no difference in baseline 5-mC levels by POCD status. The 5-mC levels significantly decreased on day 7 after surgery in patients who developed early POCD (P = .004), but did not change in non-POCD patients. Moreover, post-operative 5-mC levels were significantly lower in POCD patients than those in non-POCD patients (P = .003). Bivariate logistic models adjusted for age, gender, BMI, duration of anesthesia, and education level clearly demonstrated an independent association between post-operative 5-mC level and early POCD.

CONCLUSIONS

Post-operative global hypomethylation of leukocyte DNA was associated with the development of early POCD.

TRIAL REGISTRATION

ClinicalTrial, NCT02965235. Registered 16 November 2016, https://www.clinicaltrials.gov/ct2/results?term=NCT02965235&rank=1#rowId0.

Extracellular Spermine Activates DNA Methyltransferase 3A and 3B

We first demonstrated that long-term increased polyamine (spermine, spermidine, putrescine) intake elevated blood spermine levels in mice and humans, and lifelong consumption of polyamine-rich chow inhibited aging-associated increase in aberrant DNA methylation, inhibited aging-associated pathological changes, and extend lifespan of mouse. Because gene methylation status is closely associated with aging-associated conditions and polyamine metabolism is closely associated with regulation of gene methylation, we investigated the effects of extracellular spermine supplementation on substrate concentrations and enzyme activities involved in gene methylation. Jurkat cells and human mammary epithelial cells were cultured with spermine and/or D,L-alpha-difluoromethylornithine (DFMO), an inhibitor of ornithine decarboxylase. Spermine supplementation inhibited enzymatic activities of adenosylmethionine decarboxylase in both cells. The ratio of decarboxylated S-adenosylmethionine to S-adenosyl-L-methionine increased by DFMO and decreased by spermine. In Jurkat cells cultured with DFMO, the protein levels of DNA methyltransferases (DNMTs) 1, 3A and 3B were not changed, however the activity of the three enzymes markedly decreased. The protein levels of these enzymes were not changed by addition of spermine, DNMT 3A and especially 3B were activated. We show that changes in polyamine metabolism dramatically affect substrate concentrations and activities of enzymes involved in gene methylation.

Global DNA methylation profiling in peripheral blood cells of South African women with gestational diabetes mellitus

Background/Objective: Recently, several studies have reported that DNA methylation changes in tissue are reflected in blood, sparking interest in the potential use of global DNA methylation as a biomarker for gestational diabetes mellitus (GDM). This study investigated whether global DNA methylation is associated with GDM in South African women. Methods: Global DNA methylation was quantified in peripheral blood cells of women with (n = 63) or without (n = 138) GDM using the MDQ1 Imprint® DNA Quantification Kit. Results: Global DNA methylation levels were not different between women with or without GDM and were not associated with fasting glucose or insulin concentrations. However, levels were 18% (p = 0.012) higher in obese compared to non-obese pregnant women and inversely correlated with serum adiponectin concentrations (p = 0.005). Discussion: Contrary to our hypothesis, global DNA methylation was not associated with GDM in our population. These preliminary findings suggest that despite being a robust marker of overall genomic methylation that offers opportunities as a biomarker, global DNA methylation profiling may not offer the resolution required to detect methylation differences in the peripheral blood cells of women with GDM. Moreover, global DNA methylation in peripheral blood cells may not reflect changes in placental tissue. Further studies in a larger sample are required to explore the candidacy of a more targeted approach using gene-specific methylation as a biomarker for GDM in our population.

Polyamine Metabolism and Gene Methylation in Conjunction with One-Carbon Metabolism

Recent investigations have revealed that changes in DNA methylation status play an important role in aging-associated pathologies and lifespan. The methylation of DNA is regulated by DNA methyltransferases (DNMT1, DNMT3a, and DNMT3b) in the presence of S-adenosylmethionine (SAM), which serves as a methyl group donor. Increased availability of SAM enhances DNMT activity, while its metabolites, S-adenosyl-l-homocysteine (SAH) and decarboxylated S-adenosylmethionine (dcSAM), act to inhibit DNMT activity. SAH, which is converted from SAM by adding a methyl group to cytosine residues in DNA, is an intermediate precursor of homocysteine. dcSAM, converted from SAM by the enzymatic activity of adenosylmethionine decarboxylase, provides an aminopropyl group to synthesize the polyamines spermine and spermidine. Increased homocysteine levels are a significant risk factor for the development of a wide range of conditions, including cardiovascular diseases. However, successful homocysteine-lowering treatment by vitamins (B6, B12, and folate) failed to improve these conditions. Long-term increased polyamine intake elevated blood spermine levels and inhibited aging-associated pathologies in mice and humans. Spermine reversed changes (increased dcSAM, decreased DNMT activity, aberrant DNA methylation, and proinflammatory status) induced by the inhibition of ornithine decarboxylase. The relation between polyamine metabolism, one-carbon metabolism, DNA methylation, and the biological mechanism of spermine-induced lifespan extension is discussed.

Sex in basic research: concepts in the cardiovascular field

Women and men, female and male animals and cells are biologically different, and acknowledgement of this fact is critical to advancing medicine. However, incorporating concepts of sex-specific analysis in basic research is largely neglected, introducing bias into translational findings, clinical concepts and drug development. Research funding agencies recently approached these issues but implementation of policy changes in the scientific community is still limited, probably due to deficits in concepts, knowledge and proper methodology. This expert review is based on the EUGenMed project (www.eugenmed.eu) developing a roadmap for implementing sex and gender in biomedical and health research. For sake of clarity and conciseness, examples are mainly taken from the cardiovascular field that may serve as a paradigm for others, since a significant amount of knowledge how sex and oestrogen determine the manifestation of many cardiovascular diseases (CVD) has been accumulated. As main concepts for implementation of sex in basic research, the study of primary cell and animals of both sexes, the study of the influence of genetic vs. hormonal factors and the analysis of sex chromosomes and sex specific statistics in genome wide association studies (GWAS) are discussed. The review also discusses methodological issues, and analyses strength, weaknesses, opportunities and threats in implementing sex-sensitive aspects into basic research.

Genome-wide DNA methylome alterations in acute coronary syndrome

Acute coronary syndrome (ACS) is a common disease with high mortality and morbidity rates. The methylation status of blood DNA may serve as a potential early diagnosis and prevention biomarker for numerous diseases. The present study was designed to explore novel genome-wide aberrant DNA methylation patterns associated with ACS. The Infinium HumanMethylation450 assay was used to examine genome-wide DNA methylation profiles in 3 pairs of ACS and control group samples. Epigenome-wide DNA methylation, genomic distribution, Gene Ontology (GO) term and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed. The results were confirmed using methylation-specific polymerase chain reaction (MSP) and Sequenom MassARRAY analyses in ACS, stable coronary artery disease (SCAD) and control samples. A total of 11,342 differentially methylated (DM) 5′-C-phosphate-G-3′ (CpG) sites were identified, including 8,865 hypomethylated and 2,477 hypermethylated CpG sites in the ACS group compared with the control samples. They varied in frequency across genomic compartments, but were particularly notable in gene bodies and shores. The results of GO term and KEGG pathway enrichment analyses revealed that the methylated genes were associated with certain biological processes and pathways. Despite the considerable variability in methylation data, the candidate selected possessed significant methylation alteration in mothers against decapentaplegic homolog 3 (SMAD3) transcription start site 155 (Chr1:67356838-Chr1:67356942). MSP analysis from 81 ACS samples, 74 SCAD samples and 53 healthy samples, and Sequenom MassARRAY analysis, confirmed that differential CpG methylation of SMAD3 was significantly corrected with the reference results of the HumanMethylation450 array. The data identified an ACS-specific DNA methylation profile with a large number of novel DM CpG sites, some of which may serve as candidate markers for the early diagnosis of ACS.

Association between DNA methylation and coronary heart disease or other atherosclerotic events: A systematic review

BACKGROUND AND AIMS

The aim of this study was to perform a systematic review of the association between DNA methylation and coronary heart disease (CHD) or related atherosclerotic traits.

METHODS

A systematic review was designed. The condition of interest was DNA methylation, and the outcome was CHD or other atherosclerosis-related traits. Three DNA methylation approaches were considered: global methylation, candidate-gene, and epigenome-wide association studies (EWAS). A functional analysis was undertaken using the Ingenuity Pathway Analysis software.

RESULTS

In total, 51 articles were included in the analysis: 12 global methylation, 34 candidate-gene and 11 EWAS, with six studies using more than one approach. The results of the global methylation studies were inconsistent. The candidate-gene results were consistent for some genes, suggesting that hypermethylation in ESRα, ABCG1 and FOXP3 and hypomethylation in IL-6 were associated with CHD. The EWAS identified 84 genes showing differential methylation associated with CHD in more than one study. The probability of these findings was <1.37·10^-5. One third of these genes have been related to obesity in genome-wide association studies. The functional analysis identified several diseases and functions related to these set of genes: inflammatory, metabolic and cardiovascular disease.

CONCLUSIONS

Global DNA methylation seems to be not associated with CHD. The evidence from candidate-gene studies was limited. The EWAS identified a set of 84 genes highlighting the relevance of obesity, inflammation, lipid and carbohydrate metabolism in CHD. This set of genes could be prioritized in future studies assessing the role of DNA methylation in CHD.