Homocysteine-mediated expression of SAHH, DNMTs, MBD2, and DNA hypomethylation potential pathogenic mechanism in VSMCs

Association of plasma homocysteine with peripheral arterial disease in the hypertensive adults: A cross-sectional study

Increased plasma homocysteine (Hcy) has been identified as one of the important risk factors for cardiovascular disease. However, the association between plasma Hcy and peripheral artery disease (PAD) is still controversial. This study aimed to investigate the association between plasma Hcy and PAD and the potential modifier factors in Chinese hypertensive adults. A total of 25 300 hypertensive patients aged 18 years or older were included in the analysis in this cross-sectional study. The outcome was PAD, which defined as an ankle-brachial index ≤0.90 in either limb. Multiple logistic regression was used to analyze the relationship between plasma Hcy and PAD. The median plasma Hcy was 14.00 (interquartile range: 11.60-17.80) μmol/L. There was a significant positive association between plasma Hcy and PAD (per SD increment; OR: 1.13; 95% CI: 1.06-1.19). Patients in the upper plasma Hcy tertile (≥16.16 μmol/L) were associated with a 53% increased risk of PAD compared with patients in the lower tertile (<12.33 μmol/L) after adjustment for multiple potential confounders. Subgroup analyses showed the association between Hcy and PAD was robust among various strata. Among Chinese adults with hypertension, plasma Hcy is an independent risk factor for PAD. This finding may improve the risk stratification of PAD.

The Role of Clonal Hematopoiesis of Indeterminant Potential and DNA (Cytosine-5)-Methyltransferase Dysregulation in Pulmonary Arterial Hypertension and Other Cardiovascular Diseases

DNA methylation is an epigenetic mechanism that regulates gene expression without altering gene sequences in health and disease. DNA methyltransferases (DNMTs) are enzymes responsible for DNA methylation, and their dysregulation is both a pathogenic mechanism of disease and a therapeutic target. DNMTs change gene expression by methylating CpG islands within exonic and intergenic DNA regions, which typically reduces gene transcription. Initially, mutations in the DNMT genes and pathologic DNMT protein expression were found to cause hematologic diseases, like myeloproliferative disease and acute myeloid leukemia, but recently they have been shown to promote cardiovascular diseases, including coronary artery disease and pulmonary hypertension. We reviewed the regulation and functions of DNMTs, with an emphasis on somatic mutations in DNMT3A, a common cause of clonal hematopoiesis of indeterminant potential (CHIP) that may also be involved in the development of pulmonary arterial hypertension (PAH). Accumulation of somatic mutations in DNMT3A and other CHIP genes in hematopoietic cells and cardiovascular tissues creates an inflammatory environment that promotes cardiopulmonary diseases, even in the absence of hematologic disease. This review summarized the current understanding of the roles of DNMTs in maintenance and de novo methylation that contribute to the pathogenesis of cardiovascular diseases, including PAH.

The interplay of inflammation, exosomes and Ca2+ dynamics in diabetic cardiomyopathy

Diabetes mellitus is one of the prime risk factors for cardiovascular complications and is linked with high morbidity and mortality. Diabetic cardiomyopathy (DCM) often manifests as reduced cardiac contractility, myocardial fibrosis, diastolic dysfunction, and chronic heart failure. Inflammation, changes in calcium (Ca²⁺) handling and cardiomyocyte loss are often implicated in the development and progression of DCM. Although the existence of DCM was established nearly four decades ago, the exact mechanisms underlying this disease pathophysiology is constantly evolving. Furthermore, the complex pathophysiology of DCM is linked with exosomes, which has recently shown to facilitate intercellular (cell-to-cell) communication through biomolecules such as micro RNA (miRNA), proteins, enzymes, cell surface receptors, growth factors, cytokines, and lipids. Inflammatory response and Ca²⁺ signaling are interrelated and DCM  has been known to adversely affect many of these signaling molecules either qualitatively and/or quantitatively. In this literature review, we have demonstrated that Ca²⁺ regulators are tightly controlled at different molecular and cellular levels during various biological processes in the heart. Inflammatory mediators, miRNA and exosomes are shown to interact with these regulators, however how these mediators are linked to Ca²⁺ handling during DCM pathogenesis remains elusive. Thus, further investigations are needed to understand the mechanisms to restore cardiac Ca²⁺ homeostasis and function, and to serve as potential therapeutic targets in the treatment of DCM.

Study of wrist-ankle acupuncture therapy for optimizing anaesthesia scheme of painless gastroscopy and improving painless gastroscopy related complications

BACKGROUND

Painless gastroscopy is a widely used diagnostic and therapeutic technology in clinical practice. Propofol combined with opioids is a common drug for painless endoscopic sedation and anaesthesia. In clinical work, adverse drug reactions of anaesthesia schemes are often one of the important areas of concern for doctors and patients. With the increase in propofol dosage, the risk of serious adverse drug reactions, such as respiratory depression and hypotension, increases significantly; the use of opioids often causes gastrointestinal reactions in patients after examination, such as nausea, vomiting, delayed recovery of gastrointestinal function and other complications, which seriously affect their quality of life.

AIM

To observe the effect of wrist-ankle acupuncture therapy on the anaesthesia regimen and anaesthesia-related complications during and after painless gastroscopy examination.

METHODS

Two hundred patients were selected and randomly divided into a treatment group (n = 100) and a control group (n = 100). Both groups were routinely anaesthetized with the nalbuphine and propofol regimen, gastroscopy began after the patient lost consciousness, and given supportive treatment and vital sign monitoring. If the patient interrupted the surgery due to intraoperative torsion, intravenous propofol was used to relieve his or her discomfort. The treatment group received wrist-ankle acupuncture on this basis.

RESULTS

The general data before treatment, American Society of Anesthesiologist (ASA) grade and operation time between the two groups was no significant difference. The Wakeup time, and the Self-ambulation time in the treatment group was significantly faster than that in the control group (P < 0.05). The total dose of propofol in the treatment group was 109 ± 8.17 mg, significantly lower than that in the control group (P < 0.05). The incidence of respiratory depression and hypotension was not significantly different, but the incidence of hiccups was significantly lower than that in the control group (P < 0.05). After the examination, the incidence of nausea, vomiting, abdominal distension, and abdominal pain was 11%, 8%, 6%, and 5%, respectively, which was significantly lower than that in the control group (P < 0.05). In addition, both the operators and the patients were more satisfied with this examination, with no significant difference between the groups (P > 0.05).

CONCLUSION

Wrist-ankle acupuncture treatment can optimize the painless gastroscopy and anaesthesia scheme, reduces propofol total dose; shortens patient Wakeup time and Self-ambulation time, improves patient compliance and tolerance, is beneficial to clinical application.

Extracellular-superoxide dismutase DNA methylation promotes oxidative stress in homocysteine-induced atherosclerosis

In the present study, we investigate the effect of homocysteine (Hcy) on extracellular-superoxide dismutase (EC-SOD) DNA methylation in the aorta of mice, and explore the underlying mechanism in macrophages, trying to identify the key targets of Hcy-induced EC-SOD methylation changes. ApoE ^-/- mice are fed different diets for 15 weeks, EC-SOD and DNA methyltransferase 1 (DNMT1) expression levels are detected by RT-PCR and western blot analysis. EC-SOD methylation levels are assessed by ntMS-PCR. After EC-SOD overexpression or knockdown in macrophages, following the transfection of macrophages with pEGFP-N1-DNMT1, the methylation levels of EC-SOD are detected. Our data show that the concentrations of Hcy and the area of atherogenic lesions are significantly increased in ApoE ^-/- mice fed with a high-methionine diet, and have a positive correlation with the levels of superoxide anions, which indicates that Hcy-activated superoxide anions enhance the development of atherogenic lesions. EC-SOD expression is suppressed by Hcy, and the content of superoxide anion is increased when EC-SOD is silenced by RNAi in macrophages, suggesting that EC-SOD plays a major part in oxidative stress induced by Hcy. Furthermore, the promoter activity of EC-SOD is increased following transfection with the -1/-1100 fragment, and EC-SOD methylation level is significantly suppressed by Hcy, and more significantly decreased upon DNMT1 overexpression. In conclusion, Hcy may alter the DNA methylation status and DNMT1 acts as the essential enzyme in the methyl transfer process to disturb the status of EC-SOD DNA methylation, leading to decreased expression of EC-SOD and increased oxidative stress and atherosclerosis.

Plasma Homocysteine Level Is Independently Associated With Conventional Atherogenic Lipid Profile and Remnant Cholesterol in Adults

Background

Homocysteine (Hcy) is an independent risk factor for cardiovascular disease, while mechanisms are unclear. Despite inconsistent and limited, epidemiological and experimental studies indicated that hyperhomocysteinemia (HHcy) affected lipid metabolism. This study aims to investigate the association of plasma Hcy with traditional lipid profiles and remnant cholesterol (RC) in Chinese adults.

Methods

In total, 7,898 subjects aged 20–79 years who underwent a physical examination at Beijing Chao-Yang Hospital in Beijing were included in this study. Fasting plasma total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), apolipoprotein A1 (ApoA1), apolipoprotein B (ApoB), lipoprotein (a) [Lp(a)], Hcy, and other metabolic risk factors were measured by routine automated laboratory methods. RC was calculated as TC minus HDL-C and LDL-C. The linear regression model and logistic regression model were used to assess the relationship between Hcy and lipids after adjusting potential confounders.

Results

Of the subjects, the median level of plasma Hcy was 13.0 μmol/L and 32.3% had HHcy. Plasma Hcy was negatively associated with HDL-C, ApoA1, and Lp(a) and positively associated with TG levels after adjusting age, sex, body mass index, blood pressure, alanine transaminase, aspartate transaminase, creatinine, uric acid, and glucose. HHcy significantly increased the risk of low HDL-C [odds ratio (OR) 1.26; 95%CI (1.11–1.44); p &lt; 0.001]. The net mediation effects of ApoA1 on the relationship between Hcy and HDL-C before and after adjusting confounders were 46.9 and 30.6%, respectively. More interestingly, the RC level was significantly elevated in subjects with HHcy after adjusting other influencing factors (p = 0.025). Hcy presented a positive correlation with RC levels after adjusting the above confounding factors (β = 0.073, p = 0.004), and the correlation was still significant even after controlling other lipids, including TG, LDL-C, HDL-C, ApoA1, ApoB, and Lp(a).

Conclusion

Our study showed that plasma Hcy was not only significantly associated with conventional atherogenic lipids but also independently correlated with RC levels beyond other lipids after controlling potential confounders. This finding proposes that identifying Hcy-related dyslipidemia risk, both traditional lipids and RC residual risk, is clinically relevant as we usher in a new era of targeting Hcy-lowering therapies to fight against dyslipidemia or even cardiovascular disease.

A Liquid Biopsy-Based Approach for Monitoring Treatment Response in Post-Operative Colorectal Cancer Patients

Monitoring the therapeutic response of colorectal cancer (CRC) patients is crucial to determine treatment strategies; therefore, we constructed a liquid biopsy-based approach for tracking tumor dynamics in non-metastatic (nmCRC) and metastatic (mCRC) patients (n = 55). Serial blood collections were performed during chemotherapy for measuring the amount and the global methylation pattern of cell-free DNA (cfDNA), the promoter methylation of SFRP2 and SDC2 genes, and the plasma homocysteine level. The average cfDNA amount was higher (p < 0.05) in nmCRC patients with recurrent cancer (30.4 ± 17.6 ng) and mCRC patients with progressive disease (PD) (44.3 ± 34.5 ng) compared to individuals with remission (13.2 ± 10.0 ng) or stable disease (12.5 ± 3.4 ng). More than 10% elevation of cfDNA from first to last sample collection was detected in all recurrent cases and 92% of PD patients, while a decrease was observed in most patients with remission. Global methylation level changes indicated a decline (75.5 ± 3.4% vs. 68.2 ± 8.4%), while the promoter methylation of SFRP2 and SDC2 and homocysteine level (10.9 ± 3.4 µmol/L vs. 13.7 ± 4.3 µmol/L) presented an increase in PD patients. In contrast, we found exact opposite changes in remission cases. Our study offers a more precise blood-based approach to monitor the treatment response to different chemotherapies than the currently used markers.

A primer on metabolic memory: why existing diabesity treatments fail

Despite massive government and private sector investments into prevention of cardiovascular disease, diabetes mellitus and obesity, efforts have largely failed, and the burden of cost remains in the treatment of downstream morbidity and mortality, with overall stagnating outcomes. A new paradigm shift in the approach to these patients may explain why existing treatment strategies fail, and offer new treatment targets. This review aims to provide a clinician-centred primer on metabolic memory, defined as the sum of irreversible genetic, epigenetic, cellular and tissue-level alterations that occur with long-time exposure to metabolic derangements.

Current progress on the mechanisms of hyperhomocysteinemia-induced vascular injury and use of natural polyphenol compounds

Cardiovascular disease is one of the most common diseases in the elderly population, and its incidence has rapidly increased with the prolongation of life expectancy. Hyperhomocysteinemia is an independent risk factor for various cardiovascular diseases, including atherosclerosis, and damage to vascular function plays an initial role in its pathogenesis. This review presents the latest knowledge on the mechanisms of vascular injury caused by hyperhomocysteinemia, including oxidative stress, endoplasmic reticulum stress, protein N-homocysteinization, and epigenetic modification, and discusses the therapeutic targets of natural polyphenols. Studies have shown that natural polyphenols in plants can reduce homocysteine levels and regulate DNA methylation by acting on oxidative stress and endoplasmic reticulum stress-related signaling pathways, thus improving hyperhomocysteinemia-induced vascular injury. Natural polyphenols obtained via daily diet are safer and have more practical significance in the prevention and treatment of chronic diseases than traditional drugs.

Aberrantly Methylated-Differentially Expressed Genes Identify Novel Atherosclerosis Risk Subtypes

Increasing evidence has indicated that modulation of epigenetic mechanisms, especially methylation and long-non-coding RNA (lncRNA) regulation, plays a pivotal role in the process of atherosclerosis; however, few studies focused on revealing the epigenetic-related subgroups during atherosclerotic progression using unsupervised clustering analysis. Hence, we aimed to identify the epigenetics-related differentially expressed genes associated with atherosclerosis subtypes and characterize their clinical utility in atherosclerosis. Eighty samples with expression data (GSE40231) and 49 samples with methylation data (GSE46394) from a large artery plaque were downloaded from the GEO database, and aberrantly methylated-differentially expressed (AMDE) genes were identified based on the relationship between methylation and expression. Furthermore, we conducted weighted correlation network analysis (WGCNA) and co-expression analysis to identify the core AMDE genes strongly involved in atherosclerosis. K-means clustering was used to characterize two subtypes of atherosclerosis in GSE40231, and then 29 samples were recognized as validation dataset (GSE28829). In a blood sample cohort (GSE90074), chi-square test and logistic analysis were performed to explore the clinical implication of the K-means clusters. Furthermore, significance analysis of microarrays and prediction analysis of microarrays (PAM) were applied to identify the signature AMDE genes. Moreover, the classification performance of signature AMDE gene-based classifier from PAM was validated in another blood sample cohort (GSE34822). A total of 1,569 AMDE mRNAs and eight AMDE long non-coding RNAs (lncRNAs) were identified by differential analysis. Through the WGCNA and co-expression analysis, 32 AMDE mRNAs and seven AMDE lncRNAs were identified as the core genes involved in atherosclerosis development. Functional analysis revealed that AMDE genes were strongly related to inflammation and axon guidance. In the clinical analysis, the atherosclerotic subtypes were associated with the severity of coronary artery disease and risk of adverse events. Eight genes, including PARP15, SERGEF, PDGFD, MRPL45, UBR1, STAU1, WIZ, and LSM4, were selected as the signature AMDE genes that most significantly differentiated between atherosclerotic subtypes. Ultimately, the area under the curve of signature AMDE gene-based classifier for atherosclerotic subtypes was 0.858 and 0.812 in GSE90074 and GSE34822, respectively. This study identified the AMDE genes (lncRNAs and mRNAs) that could be implemented in clinical clustering to recognize high-risk atherosclerotic patients.

A Cross-sectional Study on the Relationship Between Homocysteine and Lipid Profiles Among Chinese Population from Hunan

Previous studies have explored the relationship between homocystein (Hcy) and lipid profiles. However, the results from these studies have been inconsistent. The current study investigated the correlation between Hcy and lipid profiles in Chinese community-based population. The participants were composed of 4012 Chinese people aged 30-92 years old, who were recruited from rural and urban communities in the Hunan Province. Non-parametric test and logistic regression were used to examine the distribution of Hcy and lipid profiles (triglyceride [TG], total cholesterol [TC], low-density lipoprotein cholesterol [LDL-C], high-density lipoprotein cholesterol [HDL-C]) and the relationship between them. The median age of subjects was 54.50 years old, and 40.98% were male. Median Hcy was 13.20 μmol/L, and 35.39% had hyperhomocysteinemia (HHcy). Median TG was 1.51 mmol/L, TC was 4.77 mmol/L, LDL-C was 2.62 mmol/L, and HDL-C was 1.27 mmol/L. In multivariable logistic regression analysis, HHcy was associated with high levels of TG (OR_male = 2.240, p < 0.001; OR_female = 2.539, p < 0.001), TC (OR_male = 2.237, p < 0.001; OR_female = 2.202, p < 0.001), and LDL-C (OR_male = 1.413, p = 0.010; OR_female = 1.617, p < 0.001) in the different sexes population and low level of HDL-C in females (OR = 1.326, p = 0.023) after adjusting for confounders. HHcy was independently associated with an increasing risk of low HDL-C among females. The regression analysis showed that HHcy was also associated with hypertriglyceridemia, hypercholesterolemia, and high level of LDL-C in males and females from Chinese community-based population, which provides a basis for the treatment and prevention of abnormal lipid metabolism.

Epigenetic control of atherosclerosis via DNA methylation: A new therapeutic target?

Atherosclerosis is a disease in which lipid-laden plaques are developed inside the vessel walls of arteries. The immune system is activated, resulting in inflammation and oxidative stress. Endothelial cells (ECs) are activated, arterial smooth muscle cells (SMCs) proliferate, macrophages are activated, and foam cells are developed, leading to dysfunctional ECs. Epigenetic regulatory mechanisms, including DNA methylation, histone modifications, and microRNAs are involved in the modulation of genes that play distinct roles in several aspects of cell biology and physiology, hence linking environmental stimuli to gene regulation. Recent research has investigated the involvement of DNA methylation in the etiopathogenesis of atherosclerosis, and several studies have documented the role of this mechanism in various aspects of the disease. Regulation of DNA methylation plays a critical role in the integrity of ECs, SMC proliferation and formation of atherosclerotic lesions. In this review, we seek to clarify the role of DNA methylation in the development of atherosclerosis through different mechanisms.

Joint Association of Serum Homocysteine and High-Sensitivity C-Reactive Protein with Arterial Stiffness in Chinese Population: A 12-Year Longitudinal Study

BACKGROUND

Elevated plasma homocysteine (Hcy) and high-sensitivity C-reactive protein (hsCRP) levels are independent risk factors for cardiovascular diseases. However, it is unclear whether the coexistence of these conditions accelerates the risk of arterial stiffness. Our study aimed to evaluate the association of combined Hcy and hsCRP with arterial stiffness in Chinese middle-aged adults.

MATERIAL/METHODS

We conducted a 12-year longitudinal study in 220 individuals in Hanzhong, China, from 2005 to 2017. The average age at follow-up was 41.83 ± 3.10 years. Demographic information, medical history, anthropometric measurements, and blood pressure as well as urine and fasting blood samples, including Hcy, hsCRP, and brachial-ankle pulse wave velocity (baPWV) were measured and analyzed.

RESULTS

BaPWV levels showed a linear growth trend with the increasing of hsCRP (p for trend <0.01). The ORs in the highest quartile compared to the lowest quartile were 1.985 (95% CI 0.776-5.077; p = 0.152) and 3.960 (95% CI 1.468-10.684; p= 0.007) for Hcy and hsCRP, respectively. When Hcy and hsCRP were combined, subjects in both the highest quartile of Hcy and hsCRP (Hcy ≥15.50 μmol/L and hsCRP ≥0.82 μmol/L) had a 12.68-fold increased risk of developing arterial stiffness at the 12-year follow-up compared to those in the lowest quartile of Hcy and hsCRP (Hcy ≤9.91 μmol/L and hsCRP ≤0.19 μmol/L) after adjusting for potential confounders.

CONCLUSIONS

The present study demonstrated that the combination of elevated serum Hcy and hsCRP may contribute to an increased risk of arterial stiffness.

Epigenetic regulation of sulfur homeostasis in plants

Plants have evolved sophisticated mechanisms for adaptation to fluctuating availability of nutrients in soil. Such mechanisms are of importance for plants to maintain homeostasis of nutrient elements for their development and growth. The molecular mechanisms controlling the homeostasis of nutrient elements at the genetic level have been gradually revealed, including the identification of regulatory factors and transporters responding to nutrient stresses. Recent studies have suggested that such responses are controlled not only by genetic regulation but also by epigenetic regulation. In this review, we present recent studies on the involvement of DNA methylation, histone modifications, and non-coding RNA-mediated gene silencing in the regulation of sulfur homeostasis and the response to sulfur deficiency. We also discuss the potential effect of sulfur-containing metabolites such as S-adenosylmethionine on the maintenance of DNA and histone methylation.

RBPJ binds to consensus and methylated cis elements within phased nucleosomes and controls gene expression in human aortic smooth muscle cells in cooperation with SRF

Given our previous demonstration that RBPJ binds a methylated repressor element and regulates smooth muscle cell (SMC)-specific gene expression, we used genome-wide approaches to identify RBPJ binding regions in human aortic SMC and to assess RBPJ's effects on chromatin structure and gene expression. RBPJ bound to consensus cis elements, but also to TCmGGGA sequences within Alu repeats that were less transcriptionally active as assessed by DNAse hypersensitivity, H3K9 acetylation, and Notch3 and RNA Pol II binding. Interestingly, RBPJ binding was frequently detected at the borders of open chromatin, and a large fraction of genes induced or repressed by RBPJ depletion were associated with this cluster of RBPJ binding sites. RBPJ binding dramatically co-localized with serum response factor (SRF) and RNA seq experiments in RBPJ- and SRF-depleted SMC demonstrated that these factors interact functionally to regulate the contraction and inflammatory gene programs that help define SMC phenotype. Finally, we showed that RBPJ bound preferentially to phased nucleosomes independent of active chromatin marks and to cis elements positioned at the beginning and middle of the nucleosome dyad. These novel findings add important insight into RBPJ's role in chromatin structure and gene expression in SMC.

Metformin Suppresses Hypopharyngeal Cancer Growth by Epigenetically Silencing Long Non-coding RNA SNHG7 in FaDu Cells

Local recurrence after therapy remains a challenging problem for hypopharyngeal cancer (HPC) due to the chemotherapy resistance. Metformin is associated with reduced cancer risk through promoting global DNA methylation in cancer cells by controlling S-adenosylhomocysteine (SAHH) activity. However, the mechanisms by which metformin inhibits HPC remain elusive. In this study, we aim to investigate the role of metformin in HPC and illustrate the mechanism by which metformin regulates long non-coding RNAs (lncRNAs) expression. CCK-8 and annexin-V/PI double staining were performed to analyze the cell viability and apoptosis. LncRNA microarray analysis, QPCR, methylation specific PCR, Western blot and RNA Immunoprecipitation were performed to analyze the molecular mechanism, Here, we report that metformin inhibits FaDu cell proliferation in time- and dose-dependent manner by suppressing lncRNA SNHG7. Further investigations revealed that SNHG7 interacted with SAHH and metformin decreased SNHG7 expression by activating SAHH activity. Increased SAHH activity resulted in upregulating DNMT1 expression, leading to hypermethylation of SNHG7 promotor. In addition, upregulation of SNHG7 was associated with advanced stage. The patients with high SNHG7 have lower overall survival than that of with low SNHG7. Interestingly, SNHG7 levels were higher in taxol resistant patients than in taxol sensitive patients. Metformin sensitizes FaDu cells to taxol and irradiation through decreasing SNHG7. In conclusion, our recent study demonstrates that metformin inhibits FaDu cell proliferation by decreasing SNHG7 expression via SAHH-mediated DNA methylation. These findings indicate that combined metformin with paclitaxel or irradiation would be a novel therapeutic strategy to overcome resistance and prevent recurrence in HPC.

Reduced MBD2 expression enhances airway inflammation in bronchial epithelium in COPD

Background

Chronic obstructive pulmonary disease (COPD) is a common inflammatory lung disease characterized by inflammatory cells activation and production of inflammatory mediators. Methyl-CpG-binding domain protein 2 (MBD2) plays an important role in diverse immunological disorders by regulating immune cell functions, such as differentiation and mediator secretion. However, the role of MBD2 in COPD remains unknown.

Methods

MBD2 protein expression in lung tissues of patients with COPD and cigarette smoke (CS)-exposed mice were evaluated by Western blot and immunohistochemistry. The role of MBD2 in cigarette smoke extract (CSE)-induction of inflammatory mediator expression in the human bronchial epithelial (HBE) cell line was assessed by silencing MBD2 expression in vitro. The involvement of signaling pathways in mediation of inflammation was tested with signaling inhibitors.

Results

Compared with controls, MBD2 expression was distinctly reduced in the bronchial epithelium of both patients with COPD and CS-exposed mice. Moreover, MBD2 expression was decreased in HBE after CSE stimulation in vitro. Moreover, MBD2 knockdown enhanced interleukin (IL)-6 and IL-8 expression in HBE in the presence and absence of CSE treatment by the ERK signaling pathway.

Conclusion

MBD2 protein expression was reduced in the airway epithelium of COPD. In HBE, this reduced expression was associated with increased levels of IL-6 and IL-8 mediated by the ERK pathway. These results suggest that MBD2 could contribute to chronic airway inflammation in COPD.

The epigenetic alterations of endogenous retroelements in aging

Endogenous retroelements, transposons that mobilize through RNA intermediates, include some of the most abundant repetitive sequences of the human genome, such as Alu and LINE-1 sequences, and human endogenous retroviruses. Recent discoveries demonstrate that these mobile genetic elements not only act as intragenomic parasites, but also exert regulatory roles in living cells. The risk of genomic instability represented by endogenous retroelements is normally counteracted by a series of epigenetic control mechanisms which include, among the most important, CpG DNA methylation. Indeed, most of the genomic CpG sites subjected to DNA methylation in the nuclear DNA are carried by these repetitive elements. As other parts of the genome, endogenous retroelements and other transposable elements are subjected to deep epigenetic alterations during aging, repeatedly observed in the context of organismal and cellular senescence, in human and other species. This review summarizes the current status of knowledge about the epigenetic alterations occurring in this large, non-genic portion of the genome in aging and age-related conditions, with a focus on the causes and the possible functional consequences of these alterations.

Epigenetic mechanisms in coronary artery disease: The current state and prospects

Coronary artery disease (CAD) is the leading cause of morbidity and mortality. CAD has both genetic and environmental causes. In the past two decades, the understanding of epigenetics has advanced swiftly and vigorously. It has been demonstrated that epigenetic modifications are associated with the onset and progression of CAD. This review aims to improve the understanding of the epigenetic mechanisms closely related to CAD and to provide a novel perspective on the onset and development of CAD. Epigenetic changes include DNA methylation, histone modification, microRNA and lncRNA, which are interrelated with critical genes and influence the expression of those genes. In addition, miRNA plays a diverse role in the pathological process of CAD. Numerous studies have found that some cardiac-specific miRNAs have potential as certain diagnostic biomarkers and treatment targets for CAD. In this review, the aberrant epigenetic mechanisms that contribute to CAD will be discussed. We will also provide novel insight into the epigenetic mechanisms that target CAD.

Role of glutathione in the regulation of epigenetic mechanisms in disease

Epigenetics is a rapidly growing field that studies gene expression modifications not involving changes in the DNA sequence. Histone H3, one of the basic proteins in the nucleosomes that make up chromatin, is S-glutathionylated in mammalian cells and tissues, making Gamma-L-glutamyl-L-cysteinylglycine, glutathione (GSH), a physiological antioxidant and second messenger in cells, a new post-translational modifier of the histone code that alters the structure of the nucleosome. However, the role of GSH in the epigenetic mechanisms likely goes beyond a mere structural function. Evidence supports the hypothesis that there is a link between GSH metabolism and the control of epigenetic mechanisms at different levels (i.e., substrate availability, enzymatic activity for DNA methylation, changes in the expression of microRNAs, and participation in the histone code). However, little is known about the molecular pathways by which GSH can control epigenetic events. Studying mutations in enzymes involved in GSH metabolism and the alterations of the levels of cofactors affecting epigenetic mechanisms appears challenging. However, the number of diseases induced by aberrant epigenetic regulation is growing, so elucidating the intricate network between GSH metabolism, oxidative stress and epigenetics could shed light on how their deregulation contributes to the development of neurodegeneration, cancer, metabolic pathologies and many other types of diseases.

Hyperhomocysteinaemia and vascular injury: advances in mechanisms and drug targets

Homocysteine is a sulphur-containing non-proteinogenic amino acid. Hyperhomocysteinaemia (HHcy), the pathogenic elevation of plasma homocysteine as a result of an imbalance of its metabolism, is an independent risk factor for various vascular diseases, such as atherosclerosis, hypertension, vascular calcification and aneurysm. Treatments aimed at lowering plasma homocysteine via dietary supplementation with folic acids and vitamin B are more effective in preventing vascular disease where the population has a normally low folate consumption than in areas with higher dietary folate. To date, the mechanisms of HHcy-induced vascular injury are not fully understood. HHcy increases oxidative stress and its downstream signalling pathways, resulting in vascular inflammation. HHcy also causes vascular injury via endoplasmic reticulum stress. Moreover, HHcy up-regulates pathogenic genes and down-regulates protective genes via DNA demethylation and methylation respectively. Homocysteinylation of proteins induced by homocysteine also contributes to vascular injury by modulating intracellular redox state and altering protein function. Furthermore, HHcy-induced vascular injury leads to neuronal damage and disease. Also, an HHcy-activated sympathetic system and HHcy-injured adipose tissue also cause vascular injury, thus demonstrating the interactions between the organs injured by HHcy. Here, we have summarized the recent developments in the mechanisms of HHcy-induced vascular injury, which are further considered as potential therapeutic targets in this condition.

LINKED ARTICLES

This article is part of a themed section on Spotlight on Small Molecules in Cardiovascular Diseases. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.8/issuetoc.

Epigenetic regulation of TGF-β1 signalling in dilative aortopathy of the thoracic ascending aorta

The term 'epigenetics' refers to heritable, reversible DNA or histone modifications that affect gene expression without modifying the DNA sequence. Epigenetic modulation of gene expression also includes the RNA interference mechanism. Epigenetic regulation of gene expression is fundamental during development and throughout life, also playing a central role in disease progression. The transforming growth factor β1 (TGF-β1) and its downstream effectors are key players in tissue repair and fibrosis, extracellular matrix remodelling, inflammation, cell proliferation and migration. TGF-β1 can also induce cell switch in epithelial-to-mesenchymal transition, leading to myofibroblast transdifferentiation. Cellular pathways triggered by TGF-β1 in thoracic ascending aorta dilatation have relevant roles to play in remodelling of the vascular wall by virtue of their association with monogenic syndromes that implicate an aortic aneurysm, including Loeys-Dietz and Marfan's syndromes. Several studies and reviews have focused on the progression of aneurysms in the abdominal aorta, but research efforts are now increasingly being focused on pathogenic mechanisms of thoracic ascending aorta dilatation. The present review summarizes the most recent findings concerning the epigenetic regulation of effectors of TGF-β1 pathways, triggered by sporadic dilative aortopathy of the thoracic ascending aorta in the presence of a tricuspid or bicuspid aortic valve, a congenital malformation occurring in 0.5-2% of the general population. A more in-depth comprehension of the epigenetic alterations associated with TGF-β1 canonical and non-canonical pathways in dilatation of the ascending aorta could be helpful to clarify its pathogenesis, identify early potential biomarkers of disease, and, possibly, develop preventive and therapeutic strategies.

Relationship between plasma homocysteine level and lipid profiles in a community-based Chinese population

Background

Previous studies established a possible link among hyperhomocysteinemia (HHcy), dyslipidemia, and atherosclerosis. However, there was limited epidemic data concerning the relation between HHcy and lipid profiles, especially in community-based Chinese populations. This study aim to investigate the association of plasma homocysteine (Hcy) level with lipid profiles in a Chinese community-based population without lipid-lowering treatment.

Method

A total of 4660 Chinese subjects from a cohort of the Shijingshan district in Beijing were included in the analysis. Plasma total Hcy, serum lipid files including total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) as well as relevant metabolic risk factors were measured. Multivariate regression models adjusting for age, gender, smoking, drinking, physical activity, vitamin B supplement, body mass index, fasting blood glucose level, serum creatinine, systolic and diastolic blood pressure were used to evaluate associations of Hcy and lipid profiles.

Result

Subjects were 56.75 ± 8.91 years old, and 38.15% were male. Median (IQR) Hcy was 11.98 (10.00–14.93) μmol/L, and 24.4% had HHcy (defined as Hcy ≥ 15 μmol/L). Mean (SD) baseline TC was 5.34 ± 0.98 mmol/L, LDL-C was 3.27 ± 0.81 mmol/L, and HDL-C was 1.43 ± 0.38 mmol/L. Median (IQR) of TG was 1.28 (0.91–1.85) mmol/L. In multivariable linear-regression analyses, lnHcy (ln transformation for Hcy) level was positively associated with lnTG (adjusted β = 0.075, SE = 0.021, P = 0.001). Using Hcy < 15 μmol/L as a reference, HHcy was independently associated with both lnTG (adjusted β = 0.056, SE = 0.020, P = 0.004) and lnHDL (adjusted β = −0.018, SE = 0.009, P = 0.038). In multivariable logistic-regression analyses, HHcy was associated with increasing risk of low HDL-C (HDL-C < 1.04 mmol/L; adjusted odds ratio [OR] =1.406, 95% confidence interval [CI]: 1.143 – 1.728, P = 0.001) and hypertriglyceridemia (TG ≥ 1.7 mmol/L; adjusted OR = 1.293, 95% CI: 1.096–1.524, P = 0.002) after adjusting the confounders. However, there were no significant associations between Hcy and TC or LDL-C.

Conclusion

The present study showed that HHcy was independently associated with hypertriglyceridemia and low levels of HDL-C, which provides evidence that Hcy levels might affect HDL-C and TG metabolism.

Variable Methylation Potential in Preterm Placenta: Implication for Epigenetic Programming of the Offspring

Children born preterm are reported to be at increased risk of developing noncommunicable diseases in later life. Altered placental DNA methylation patterns are implicated in fetal programming of adult diseases. Our earlier animal studies focus on micronutrients (folic acid, vitamin B₁₂) and long-chain polyunsaturated fatty acids (LCPUFAs) that interact in the 1 carbon cycle, thereby influencing methylation reactions. Our previous studies in women delivering preterm show altered plasma levels of micronutrients and lower plasma LCPUFA levels. We postulate that alterations in the micronutrient metabolism may affect the regulation of enzymes, methionine adenosyltransferase ( MAT2A), and SAH-hydrolase ( AHCY), involved in the production of methyl donor S-adenosylmethionine (SAM), thereby influencing the methylation potential (MP) in the placenta of women delivering preterm. The present study, therefore, examines the mRNA, protein levels of enzymes ( MAT2A and AHCY), SAM, S-adenosylhomocysteine (SAH) levels, and global DNA methylation levels from preterm (n = 73) and term (n = 73) placentae. The enzyme messenger RNA (mRNA) levels were analyzed by real-time quantitative polymerase chain reaction, protein levels by enzyme-linked immunosorbent assay, and SAM-SAH levels by high-performance liquid chromatography. The mRNA levels for MAT2A and AHCY are higher ( P < .05 for both) in the preterm group as compared to the term group. S-Adenosylmethionine and SAH levels were similar in both groups, although SAM:SAH ratio was lower ( P < .05) in the preterm group as compared to the term group. The global DNA methylation levels were higher ( P < .05) in women delivering small for gestation age infants as compared to women delivering appropriate for gestation age infants at term. Our data showing lower MP in the preterm placenta may have implications for the epigenetic programming of the developing fetus.

miR-125b targets DNMT3b and mediates p53 DNA methylation involving in the vascular smooth muscle cells proliferation induced by homocysteine

MicroRNAs (miRNAs) are short non-coding RNA and play crucial roles in a wide array of biological processes, including cell proliferation, differentiation and apoptosis. Our previous studies found that homocysteine(Hcy) can stimulate the proliferation of vascular smooth muscle cells (VSMCs), however, the underlying mechanisms were not fully elucidated. Here, we found proliferation of VSMCs induced by Hcy was of correspondence to the miR-125b expression reduced both in vitro and in the ApoE knockout mice, the hypermethylation of p53, its decreased expression, and DNA (cytosine-5)-methyltransferase 3b (DNMT3b) up-regulated. And, we found DNMT3b is a target of miR-125b, which was verified by the Dual-Luciferase reporter assay and western blotting. Besides, the siRNA interference for DNMT3b significantly decreased the methylation level of p53, which unveiled the causative role of DNMT3b in p53 hypermethylation. miR-125b transfection further confirmed its regulative roles on p53 gene methylation status and the VSMCs proliferation. Our data suggested that a miR-125b-DNMT3b-p53 signal pathway may exist in the VSMCs proliferation induced by Hcy.

Epigenetic Regulation of Oxidative Stress in Ischemic Stroke

The prevalence and incidence of stroke rises with life expectancy. However, except for the use of recombinant tissue-type plasminogen activator, the translation of new therapies for acute stroke from animal models into humans has been relatively unsuccessful. Oxidative DNA and protein damage following stroke is typically associated with cell death. Cause-effect relationships between reactive oxygen species and epigenetic modifications have been established in aging, cancer, acute pancreatitis, and fatty liver disease. In addition, epigenetic regulatory mechanisms during stroke recovery have been reviewed, with focuses mainly on neural apoptosis, necrosis, and neuroplasticity. However, oxidative stress-induced epigenetic regulation in vascular neural networks following stroke has not been sufficiently explored. Improved understanding of the epigenetic regulatory network upon oxidative stress may provide effective antioxidant approaches for treating stroke. In this review, we summarize the epigenetic events, including DNA methylation, histone modification, and microRNAs, that result from oxidative stress following experimental stroke in animal and cell models, and the ways in which epigenetic changes and their crosstalk influence the redox state in neurons, glia, and vascular endothelial cells, helping us to understand the foregone and vicious epigenetic regulation of oxidative stress in the vascular neural network following stroke.

Role of DNA methylation in cardiovascular diseases

A complex interplay between genetic and environmental factors is involved in the pathogenesis of cardiovascular diseases (CVDs). Environmental factors have crucial effects on the epigenetic trait of genes, which refers to a stably heritable phenotype resulting from changes in the chromosomes without alteration of the DNA sequence, but has profound effects on the cellular repertoire. Among the epigenetic patterns, DNA methylation is of great interest. DNA methylation occurs at both global and specific gene promoter levels and relates to atherosclerosis. Aberrant DNA methylation affects the transcription and expression of critical regulatory genes and induces a proatherogenic cellular phenotype, which plays key roles in endothelia cell dysfunction, abnormal vascular smooth muscle cell proliferation, extracellular matrix formation, and inflammation in CVDs. This review focuses on the contribution of DNA methylation in the pathogenesis of CVDs.

Effect of MTHFR Gene Polymorphism Impact on Atherosclerosis via Genome-Wide Methylation

BACKGROUND

Atherosclerosis seriously threats human health. Homocysteine is an independent risk factor closely related to DNA methylation. MTHFR C667T loci polymorphism is closely associated with homocysteine level. This study aimed to investigate the relationship among MTHFR C667T loci polymorphism, genome-wide methylation, and atherosclerosis.

MATERIAL/METHODS

Blood sample was collected from 105 patients with coronary atherosclerosis and 105 healthy controls. Pyrosequencing methylation was used to detect LINE-1 methylation level. Polymerase chain reaction-restriction enzyme fragment length polymorphism (PCR-RFLP) was used to test MTHFR.

RESULTS

LINE-1 methylation level in the patient group was significantly lower than in the controls (t=5.007, P<0.001). MTHFR C667T genotype distribution presented marked differences in the 2 groups. TT genotype carriers had significantly increased risk of atherosclerosis (OR=3.56, P=0.009). Three different genotypes of MTHFR C667T loci showed different LINE-1 methylation level between the 2 groups (P<0.01). LINE-1 methylation level in TT and CT genotype carriers was obviously lower than in CC genotype carriers (P<0.05).

CONCLUSIONS

MTHFR C667T loci polymorphism may affect atherosclerosis by regulating genome methylation level.

Folic acid attenuates the effects of amyloid β oligomers on DNA methylation in neuronal cells

PURPOSE

Alzheimer's disease (AD) is a highly prevalent type of dementia. The epigenetic mechanism of gene methylation provides a putative link between nutrition, one-carbon metabolism, and disease progression because folate deficiency may cause hypomethylation of promoter regions in AD-relevant genes. We hypothesized that folic acid supplementation may protect neuron cells from amyloid β (Aβ) oligomer-induced toxicity by modulating DNA methylation of APP and PS1 in AD models.

METHODS

Primary hippocampal neuronal cells and hippocampal HT-22 cells were incubated for 24 h with a combination of folic acid and either Aβ oligomers or vehicle and were then incubated for 72 h with various concentrations of folic acid. AD transgenic mice were fed either folate-deficient or control diets and gavaged daily with various doses of folic acid (0 or 600 μg/kg). DNA methyltransferase (DNMT) activity, cell viability, methylation potential of cells, APP and PS1 expression, and the methylation of the respective promoters were determined.

RESULTS

Aβ oligomers lowered DNMT activity, increased PS1 and APP expression, and decreased cell viability. Folic acid dose-dependently stimulated methylation potential and DNMT activity, altered PS1 and APP promoter methylation, decreased PS1 and APP expression, and partially preserved cell viability. Folic acid increased PS1 and APP promoter methylation in AD transgenic mice.

CONCLUSION

These results suggest a mechanism by which folic acid may prevent Aβ oligomer-induced neuronal toxicity.

Folic acid inhibits tau phosphorylation through regulation of PP2A methylation in SH-SY5Y cells

OBJECTIVES

Neurofibrillary tangles (NFTs), which are composed of intracellular filamentous aggregates of hyperphosphorylated tau protein, are one of the pathological hallmarks of Alzheimer's disease (AD). Because tau phosphorylation is regulated by phosphatases, abnormal metabolism of protein phosphatase 2A (PP2A) has been proposed to be a contributing factor to the disease process.

RESULTS

To determine the function of folic acid on tau phosphorylation, an in vitro model of human neuroblastoma cells (SH-SY5Y) were exposed to folic acid (0-40 μmol/L) for 96 h, in the presence or absence of the phosphoesterase inhibitor okadaic acid (OA) (10 nmol/L) for 9 h. The data of western blot showed tau phosphorylation at the Ser396 site in OA-incubated SH-SY5Y cells was inhibited by folic acid in a concentration-dependent manner, with the folic acid concentration of 40 μmol/L providing maximal inhibition. Folic acid can downregulate tau protein phosphorylation by inhibiting the demethylation reactions of PP2A. High folic acid concentrations (20 and 40 μmol/L) increased SAM:SAH ratios and cell viability.

CONCLUSION

Therefore, we can speculate that folate deficiency may be a cause of PP2A deregulation, which can in turn lead to expression of the abnormal hyperphosphorylated form of tau.

Towards a molecular systems model of coronary artery disease

Coronary artery disease (CAD) is a complex disease driven by myriad interactions of genetics and environmental factors. Traditionally, studies have analyzed only 1 disease factor at a time, providing useful but limited understanding of the underlying etiology. Recent advances in cost-effective and high-throughput technologies, such as single nucleotide polymorphism (SNP) genotyping, exome/genome/RNA sequencing, gene expression microarrays, and metabolomics assays have enabled the collection of millions of data points in many thousands of individuals. In order to make sense of such 'omics' data, effective analytical methods are needed. We review and highlight some of the main results in this area, focusing on integrative approaches that consider multiple modalities simultaneously. Such analyses have the potential to uncover the genetic basis of CAD, produce genomic risk scores (GRS) for disease prediction, disentangle the complex interactions underlying disease, and predict response to treatment.

Notable epigenetic role of hyperhomocysteinemia in atherogenesis

Atherosclerosis is associated with multiple genetic and modifiable risk factors. There is an increasing body of evidences to indicate that epigenetic mechanisms also play an essential role in atherogenesis by influencing gene expression. Homocysteine is a sulfur-containing amino acid formed during methionine metabolism. Elevated plasma level of homocysteine is generally termed as hyperhomocysteinemia. As a potential risk factor for cardiovascular diseases, hyperhomocysteinemia may initiate or motivate atherogenesis by modification of DNA methylation. The underlying epigenetic mechanism is still unclear with controversial findings. This review focuses on epigenetic involvement and mechanisms of hyperhomocysteinemia in atherogenesis. Considering the potential beneficial effects of anti-homocysteinemia treatments in preventing atherosclerosis, further studies on the role of hyperhomocysteinemia in atherogenesis are warranted.

Association of the histone-lysine N-methyltransferase MLL5 gene with coronary artery disease in Chinese Han people

BACKGROUND

MLL5, a member of the histone-lysine N-methyltransferase family, has been implicated in the control of the cell cycle progression and survival. The aim of this study was to explore the relationship between the interaction of histone-lysine N-methyltransferase MLL5 gene polymorphism and CAD in a Chinese Han population.

METHODS

Using a case-control study of Chinese CAD patients (n = 565) and healthy controls (n = 694), we investigated the MLL5 gene polymorphism by the use of polymerase chain reaction fragment length polymorphism (PCR-RFLP) analysis.

RESULTS

For total, the distribution of SNP1 (rs12671368) and SNP2 (rs2192932) genotypes showed a significant difference between CAD and control participants (P1 = 0.03, P2 = 0.02). For total the distribution of SNP1 (rs12671368) and SNP2 (rs2192932) alleles in the dominant model (GG vs. AA + AG) and the recessive model (AA vs. AG + GG) showed a significant difference between CAD and control participants (for allele: P1 < 0.01 and P2 = 0.05, for dominant model: P1 > 0.05 and P2 = 0.02, for recessive model: P1 = 0.03 and P2 = 0.78, respectively). For total the significant difference of the distribution of SNP1 and SNP2 in the dominant model and recessive model was retained after adjusting for covariates (for dominant model: SNP1 OR: 1.68, 95% confidence interval [CI]: 1.08-2.64, P = 0.02; SNP2 OR: 0.51, 95% CI: 0.36-0.72, P = 0.01; for recessive model: SNP1 OR: 1.84, 95% confidence interval [CI]: 1.28-2.64, P < 0.01; SNP2 OR: 0.65, 95% CI: 0.35-1.22, P = 0.18).

CONCLUSIONS

The GG genotype of rs12671368 and the AA genotype of rs2192932 in the MLL5 gene could be protective genetic markers of CAD.

Metabolic syndrome components are associated with DNA hypomethylation

BACKGROUND

Disturbances of DNA methylation have been associated with multiple diseases, including cardiovascular disease, cancer and, as some have suggested, glucometabolic disturbances. Our aim was to assess the association of the metabolic syndrome and its individual components with DNA methylation in a population-based study.

MATERIALS AND METHODS

In a human population (n = 738) stratified by age, sex and glucose metabolism, we explored associations of the metabolic syndrome according to National Cholesterol Education Program/Adult Treatment Panel-III criteria and its individual components (fasting glucose, high-density lipoprotein cholesterol, triglycerides, blood pressure, waist circumference) with global leukocyte DNA methylation. DNA methylation was measured as the methylcytosine/cytosine ratio in peripheral leukocytes using liquid chromatography-tandem mass spectrometry.

RESULTS

Individuals with the metabolic syndrome had relative DNA hypomethylation compared to participants without the syndrome (β = -0.05; p = 0.01). This association was mainly attributable to linear associations of two metabolic syndrome components with DNA methylation: fasting plasma glucose (β = -0.02; p = 0.004) and high-density lipoprotein cholesterol (β = 0.07; p = 0.004). People with type 2 diabetes or impaired glucose metabolism had DNA hypomethylation compared to normoglycemic individuals (β = -0.05; p = 0.004).

CONCLUSIONS

DNA hypomethylation is independently associated with hyperglycemia and low high-density lipoprotein cholesterol, both essential components of the metabolic syndrome. The potential implications and direction of possible causality require further study.

Homocysteine induces the expression of C-reactive protein via NMDAr-ROS-MAPK-NF-κB signal pathway in rat vascular smooth muscle cells

OBJECTIVE

Homocysteine (Hcy) is known as an independent risk factor for atherosclerosis. C-reactive protein (CRP) directly participates in initiation and progression of atherosclerosis. However, there is no direct evidence to demonstrate pro-inflammatory effect of Hcy on vascular smooth muscle cells (VSMCs) through CRP. In the present study, we examined the effect of Hcy on CRP expression and investigated the related mechanism in VSMCs.

METHODS AND RESULTS

Protein expression and secretion were detected by Western blot and ELISA, respectively. mRNA expression was detected by RT-PCR. Superoxide anion was detected by lucigenin chemiluminometry and the immunofluorescence staining was observed by a fluorescence microscope. The results revealed that Hcy significantly induced mRNA and protein expressions of CRP in VSMCs both in vitro and in vivo, and anti-IL-1β or anti-IL-6 neutralizing antibody alone or in combination partially reduced Hcy-induced CRP expression. Hcy increased the expression of NR1 subunit of N-methyl-d-aspartate receptor (NMDAr), and MK-801 alleviated Hcy-induced CRP expression in VSMCs. Further studies showed that Hcy-stimulated superoxide anion generation in VSMCs. Nevertheless, pretreatment of the cells with MK-801, TTFA and DPI significantly reduced Hcy-stimulated superoxide anion generation, and antioxidant NAC decreased Hcy-induced CRP expression in VSMCs. Additionally, PD98059, SB205380 or PDTC antagonized Hcy-induced CRP expression, and MK-801, NAC, PD98059 or SB205380 inhibited Hcy-activated phosphorylations of ERK1/2 and p38.

CONCLUSION

The present study demonstrates that Hcy is able to initiate an inflammatory response in VSMCs by stimulating CRP production, which is mediated through NMDAr-ROS-ERK1/2/p38-NF-κB signal pathway. These findings provide new evidence for a role of Hcy in pathogenesis of atherosclerosis.

Association between blood pressure and DNA methylation of retrotransposons and pro-inflammatory genes

BACKGROUND

Methylation of deoxyribonucleic acid (DNA) is an epigenetic regulator of gene expression that changes with age, but its contribution to aging-related disorders, including high blood pressure (BP), is still largely unknown. We examined the relation of BP to the methylation of retrotransposon sequences of DNA and of selected candidate genes.

METHODS

This investigation included 789 elderly participants in the Normative Aging Study, ranging in age from 55 to 100 years, who had longitudinal measurements of DNA methylation. In these subjects' DNA we measured the proportion of methylated sites in retrotransposable sequences and in pro-inflammatory genes, expressed as the percent of 5-methylated cytosines (%5mC) among all cytosines. From one to four methylation measurements were made for each subject between 1999 and 2009. We fit mixed-effects models, using repeated measures of BP as the outcome and DNA methylation as the explanatory variable, adjusting for confounding variables. We also fit a Bayesian mixed-effects structural equation model to account for heterogeneity in the effects of methylation sites within each gene.

RESULTS

An increase in inter-quartile range (IQR) in the methylation of Alu elements was associated with an increase of 0.97 mm Hg in diastolic blood pressure (DBP) (95% CI 0.32-1.57), but no such association was observed for long interspersed nuclear element-1 (LINE-1). We also found positive associations between DBP and methylation of the genes for toll-like receptor 2 (TLR2) and inducible nitric oxide synthase (iNOS), and a negative association between DBP and methylation of the gene for interferon-γ (IFN-γ). Associations between methylation and systolic blood pressure (SBP) were weaker than those between methylation and DBP. Bayesian mixed-effects structural equation model results were similar for both DBP and SBP models.

CONCLUSIONS

The results of our study suggest that changes in DNA methylation of some pro-inflammatory genes and retrotransposable elements are related to small changes in BP.

Hyperhomocysteinemia-Induced Monocyte Chemoattractant Protein-1 Promoter DNA Methylation by Nuclear Factor-κB/DNA Methyltransferase 1 in Apolipoprotein E-Deficient Mice

Hyperhomocysteinemia is considered to be a significant risk factor in atherosclerosis and plays an important role in it. The purpose of this study was to determine the molecular mechanism of blood monocyte chemoattractant protein-1 (MCP-1) promoter DNA hypomethylation in the formation of atherosclerosis induced by hyperhomocysteinemia, and to explore the effect of nuclear factor-κB (NF-κB)/DNA methyltransferase 1 (DNMT1) in this mechanism. The atherosclerotic effect of MCP-1 in apolipoprotein E–deficient (ApoE^−/−) and wild-type C57BL/6J mice was evaluated using atherosclerotic lesion area; serum NF-κB, MCP-1, and DNMT1 levels; and MCP-1 promoter DNA methylation expression. In vitro, the mechanism responsible for the effect of NF-κB/DNMT1 on foam cells was investigated by measuring NF-κB and DNMT1 levels to determine whether NF-κB/DNMT1 had an effect on gene expression. Compared with the control group, atherosclerotic lesions in ApoE^−/− mice fed a high methionine diet significantly increased, as did the expression of MCP-1. In vitro study showed that pyrrolidine dithiocarbamate treatment down-regulated levels of NF-κB and raised DNMT1 concentrations, confirming the effect of NF-κB/DNMT1 in the MCP-1 promoter DNA methylation process. In conclusion, our results suggest that through NF-κB/DNMT1, MCP-1 promoter DNA hypomethylation may play a key role in formation of atherosclerosis under hyperhomocysteinemia.

The potential role of homocysteine mediated DNA methylation and associated epigenetic changes in abdominal aortic aneurysm formation

Previous studies have suggested that homocysteine (Hcy) has wide-ranging biological effects, including accelerating atherosclerosis, impairing post injury endothelial repair and function, deregulating lipid metabolism and inducing thrombosis. However, the biochemical basis by which hyperhomocysteinemia (HHcy) contributes to cardiovascular diseases (CVDs) remains largely unknown. Several case-control studies have reported an association between HHcy and the presence of abdominal aortic aneurysms (AAA) and there are supportive data from animal models. Genotypic data concerning the association between variants of genes involved in the methionine cycle and AAA are conflicting probably due to problems such as reverse causality and confounding. The multifactorial nature of AAA suggests the involvement of additional epigenetic factors in disease formation. Elevated Hcy levels have been previously linked to altered DNA methylation levels in various diseases. Folate or vitamin B12 based methods of lowering Hcy have had disappointingly limited effects in reducing CVD events. One possible reason for the limited efficacy of such therapy is that they have failed to reverse epigenetic changes induced by HHcy. It is possible that individuals with HHcy have an "Hcy memory effect" due to epigenetic alterations which continue to promote progression of cardiovascular complications even after Hcy levels are lowered. It is possible that deleterious effect of prior, extended exposure to elevated Hcy concentrations have long-lasting effects on target organs and genes, hence underestimating the benefit of Hcy lowering therapies in CVD patients. Therapies targeting the epigenetic machinery as well as lowering circulating Hcy concentrations may have a more efficacious effect in reducing the incidence of cardiovascular complications.

The comprehensive effects of hyperlipidemia and hyperhomocysteinemia on pathogenesis of atherosclerosis and DNA hypomethylation in ApoE-/- mice

Atherosclerosis (AS) is a disease induced by multiple factors, including genetic and environmental elements. The aim of the present study is to investigate the comprehensive effects of high cholesterol, high methionine diet, and apolipoprotein E deficiency (ApoE(-/-)) on the pathogenesis of AS. ApoE(-/-) mice were fed with high cholesterol and methionine diet for 15 weeks to induce hyperlipidemia and hyperhomocysteinemia. The methylation levels of genomic DNA (gDNA) and B1 repetitive elements in aortic tissues were measured by both methylation-dependent restriction analysis and nested methylation-specific polymerase chain reaction (PCR). Methylation sequence-bias pattern was assayed by DNA methyl-accepting capacity with restriction endonuclease digestion. The mRNA expression of DNA methyltransferase-1, 3 (DNMT1, 3) was detected by real-time PCR. The concentrations of S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) were determined by high-performance liquid chromatography. The results showed hypomethylation of gDNA and B1 repetitive elements. The mRNA expression of DNMT1 was reduced. The levels of SAM, SAH, and SAM/SAH ratio were increased. The atherosclerotic lesion areas strongly correlated with the risk factors. The distribution of DNA demethylation was preferred to non-CpG islands, which may suggest the major impact of hypomethylation on DNA integrity and genomic instability. Overall, our data unequivocally showed that the comprehensive role of high cholesterol, high methionine diet, and ApoE(-/-) is not uniformly consistent with the role of a single risk factor. The DNA methylation pattern in AS is quite complex and depends on genetic background and many involved risk factors.

MicroRNA-152 mediates DNMT1-regulated DNA methylation in the estrogen receptor α gene

Background

Estrogen receptor α (ERα) has been shown to protect against atherosclerosis. Methylation of the ERα gene can reduce ERα expression leading to a higher risk for cardiovascular disease. Recently, microRNAs have been found to regulate DNA methyltransferases (DNMTs) and thus control methylation status in several genes. We first searched for microRNAs involved in DNMT-associated DNA methylation in the ERα gene. We also tested whether statin and a traditional Chinese medicine (San-Huang-Xie-Xin-Tang, SHXXT) could exert a therapeutic effect on microRNA, DNMT and ERα methylation.

Methodology/Principal Findings

The ERα expression was decreased and ERα methylation was increased in LPS-treated human aortic smooth muscle cells (HASMCs) and the aorta from rats under a high-fat diet. microRNA-152 was found to be down regulated in the LPS-treated HASMCs. We validated that microRNA-152 can knock down DNMT1 in HASMCs leading to hypermethylation of the ERα gene. Statin had no effect on microRNA-152, DNMT1 or ERα expression. On the contrary, SHXXT could restore microRNA-152, decrease DNMT1 and increase ERα expression in both cellular and animal studies.

Conclusions/Significance

The present study showed that microRNA-152 decreases under the pro-atherosclerotic conditions. The reduced microRNA-152 can lose an inhibitory effect on DNA methyltransferase, which leads to hypermethylation of the ERα gene and a decrease of ERα level. Although statin can not reverse these cascade proatherosclerotic changes, the SHXXT shows a promising effect to inhibit this unwanted signaling pathway.

Homocysteine promotes human endothelial cell dysfunction via site-specific epigenetic regulation of p66shc

AIMS

Hyperhomocysteinaemia is an independent risk factor for atherosclerotic vascular disease and is associated with vascular endothelial dysfunction. Homocysteine modulates cellular methylation reactions. P66shc is a protein that promotes oxidative stress whose expression is governed by promoter methylation. We asked if homocysteine induces endothelial p66shc expression via hypomethylation of CpG dinucleotides in the p66shc promoter, and whether p66shc mediates homocysteine-stimulated endothelial cell dysfunction.

METHODS AND RESULTS

Homocysteine stimulates p66shc transcription in human endothelial cells and hypomethylates specific CpG dinucleotides in the human p66shc promoter. Knockdown of p66shc inhibits the increase in reactive oxygen species, and decrease in nitric oxide, elicited by homocysteine in endothelial cells and prevents homocysteine-induced up-regulation of endothelial intercellular adhesion molecule-1. In addition, knockdown of p66shc mitigates homocysteine-induced adhesion of monocytes to endothelial cells. Inhibition of DNA methyltransferase activity or knockdown of DNA methyltransferase 3b abrogates homocysteine-induced up-regulation of p66shc. Comparison of plasma homocysteine in humans with coronary artery disease shows a significant difference between those with highest and lowest p66shc promoter CpG methylation in peripheral blood leucocytes.

CONCLUSION

Homocysteine up-regulates human p66shc expression via hypomethylation of specific CpG dinucleotides in the p66shc promoter, and this mechanism is important in homocysteine-induced endothelial cell dysfunction.

Cardiovascular disease risk factors and DNA methylation at the LINE-1 repeat region in peripheral blood from Samoan Islanders

Lower levels of LINE-1 methylation in peripheral blood have been previously associated with risk of developing non-communicable conditions, the most well-explored of these being cancer, although recent research has begun to link altered LINE-1 methylation and cardiovascular disease. We examined the relationship between LINE-1 methylation and factors associated with metabolic and cardiovascular diseases through quantitative bisulfite pyrosequencing in DNA from peripheral blood samples from participants of the Samoan Family Study of Overweight and Diabetes (2002-03). The sample included 355 adult Samoans (88 men and 267 women) from both American Samoa and Samoa. In a model including all sample participants, men had significantly higher LINE-1 methylation levels than women (p=0.04), and lower levels of LINE-1 methylation were associated with higher levels of fasting LDL (p=0.02) and lower levels of fasting HDL (p=0.009). The findings from this study confirm that DNA "global" hypomethylation, (as measured by methylation at LINE-1 repeats) observed previously in cardiovascular disease is associated with altered levels of LDL and HDL in peripheral blood. Additionally, these findings strongly argue the need for further research, particularly including prospective studies, in order to understand the relationship between LINE-1 DNA methylation measured in blood and risk factors for cardiovascular disease.