Epigenetics of Atherosclerosis: Emerging Mechanisms and Methods

Low expression of Notch1 may be associated with acute myocardial infarction

Background

The transmembrane protein Notch1 is associated with cell growth, development, differentiation, proliferation, apoptosis, adhesion, and the epithelial mesenchymal transition. Proteomics, as a research method, uses a series of sequencing techniques to study the composition, expression levels, and modifications of proteins. Here, the association between Notch1 and acute myocardial infarction (AMI) was investigated using proteomics, to assess the possibility of using Notch1 as a biomarker for the disease.

Methods

Fifty-five eligible patients with AMI and 74 with chronic coronary syndrome (CCS) were enrolled, representing the experimental and control groups, respectively. The mRNA levels were assessed using RT-qPCR and proteins were measured using ELISA, and the results were compared and analyzed.

Results

Notch1 mRNA levels were 0.52 times higher in the peripheral blood mononuclear cells of the AMI group relative to the CCS group (p < 0.05) while Notch1 protein levels were 0.63 times higher in peripheral blood plasma in AMI patients (p < 0.05). Notch1 levels were not associated with older age, hypertension, smoking, high abdominal-blood glucose, high total cholesterol, and high LDL in AMI. Logistic regression indicated associations between AMI and reduced Notch1 expression, hypertension, smoking, and high fasting glucose.

Conclusions

Notch1 expression was reduced in the peripheral blood of patients with AMI relative to those with CCS. The low expression of Notch1 was found to be an independent risk factor for AMI and may thus be an indicator of the disease.

Omics Approaches Unveiling the Biology of Human Atherosclerotic Plaques

Atherosclerosis is a chronic inflammatory disease of the arterial wall, characterized by the buildup of plaques with the accumulation and transformation of lipids, immune cells, vascular smooth muscle cells, and necrotic cell debris. Plaques with collagen-poor thin fibrous caps infiltrated by macrophages and lymphocytes are considered unstable because they are at the greatest risk of rupture and clinical events. However, the current histologic definition of plaque types may not fully capture the complex molecular nature of atherosclerotic plaque biology and the underlying mechanisms contributing to plaque progression, rupture, and erosion. The advances in omics technologies have changed the understanding of atherosclerosis plaque biology, offering new possibilities to improve risk prediction and discover novel therapeutic targets. Genomic studies have shed light on the genetic predisposition to atherosclerosis, and integrative genomic analyses expedite the translation of genomic discoveries. Transcriptomic, proteomic, metabolomic, and lipidomic studies have refined the understanding of the molecular signature of atherosclerotic plaques, aiding in data-driven hypothesis generation for mechanistic studies and offering new prospects for biomarker discovery. Furthermore, advancements in single-cell technologies and emerging spatial analysis techniques have unveiled the heterogeneity and plasticity of plaque cells. This review discusses key omics-based discoveries that have advanced the understanding of human atherosclerotic plaque biology, focusing on insights derived from omics profiling of human atherosclerotic vascular specimens.

The JMJD family of histone demethylase and their intimate links to cardiovascular disease

The incidence rate and mortality rate of cardiovascular disease rank first in the world. It is associated with various high-risk factors, and there is no single cause. Epigenetic modifications, such as DNA methylation or histone modification, actively participate in the initiation and development of cardiovascular diseases. Histone lysine methylation is a type of histone post-translational modification. The human Jumonji C domain (JMJD) protein family consists of more than 30 members. JMJD proteins participate in many key nuclear processes and play a key role in the specific regulation of gene expression, DNA damage and repair, and DNA replication. Importantly, increasing evidence shows that JMJD proteins are abnormally expressed in cardiovascular diseases, which may be a potential mechanism for the occurrence and development of these diseases. Here, we discuss the key roles of JMJD proteins in various common cardiovascular diseases. This includes histone lysine demethylase, which has been studied in depth, and less-studied JMJD members. Furthermore, we focus on the epigenetic changes induced by each JMJD member, summarize recent research progress, and evaluate their relationship with cardiovascular diseases and therapeutic potential.

Zhizi-Chuanxiong herb pair alleviates atherosclerosis progression in ApoE-/- mice by promoting the methylation of FGFR3 to inhibit MAPK/ERK-mediated apoptosis

ETHNOPHARMACOLOGICAL RELEVANCE

Gardenia Fructus (Gardenia jasminoides Ellis, Zhizi) and Chuanxiong Rhizoma (Ligusticum chuanxiong Hort., Chuanxiong) are both traditional Chinese medicines with vascular protective effects, which help detoxify and activate blood, and are clinically used to treat atherosclerosis (AS). Previously, Zhizi-Chuanxiong showed good efficacy in attenuating AS progression in rabbits. However, its potential mechanism is yet unclear.

AIM OF THE STUDY

This study aimed to investigate the mechanism of the Zhizi-Chuanxiong herb pair (ZCHP) in attenuating AS progression from the perspective of DNA methylation.

MATERIALS AND METHODS

An AS mouse model was developed with ApoE-/- mice fed a high-fat diet (HFD). The therapeutic effects and mechanisms of ZCHP in treating HFD-induced AS were identified using an automated biochemical analyzer, enzyme-linked immunosorbent assays, histopathology, methyl-capture sequencing (MC-seq), pyrosequencing, quantitative reverse transcription-polymerase chain reaction (RT-qPCR), western blotting, and TUNEL staining.

RESULTS

ZCHP attenuated the development of AS by reducing lipid levels and enhancing the stability of plaques and via anti-inflammation. MC-seq and Kyoto Encyclopedia of Genes and Genomes analysis revealed that ZCHP corrected the expressions of both aberrant hypomethylated and hypermethylated genes, which are involved in the mitogen-activated protein kinase (MAPK) signaling pathway. Protein-protein network interaction analysis and molecular docking showed that fibroblast growth factor 3 (FGFR3) and serine/threonine protein kinase (AKT1) were closely related to the MAPK signaling pathway among differentially methylated genes induced by ZCHP. Furthermore, pyrosequencing showed that ZCHP could induce FGFR3 hypermethylation and AKT1 hypomethylation in the promoter region, which was consistent with the MC-seq results. Molecular docking showed that the ZCHP was more tightly docked to FGFR3. Furthermore, RT-qPCR and western blotting showed that the mRNA and protein expression levels of FGFR3 decreased after treatment with ZCHP. Finally, western blotting showed that ZCHP suppressed the expression of phosphorylated MAPK and phosphorylated extracellular signal-regulated kinase (ERK), and TUNEL staining showed that ZCHP treatment could inhibit apoptosis in AS.

CONCLUSION

Our findings suggest that ZCHP can effectively attenuate AS progression by inhibiting MAPK/ERK signaling-mediated apoptosis via FGFR3 hypermethylation in the promoter region.

Functional role of Ash2l in oxLDL induced endothelial dysfunction and atherosclerosis

Endothelial injury and dysfunction in the artery wall fuel the process of atherosclerosis. As a key epigenetic regulator, Ash2l (Absent, small, or homeotic-Like 2) is involved in regulating vascular injury and its complications. However, the role of Ash2l in atherosclerosis has not yet been fully elucidated. Here, we found increased Ash2l expression in high-cholesterol diet-fed ApoE-/- mice and oxidized LDL (oxLDL) treated endothelial cells (ECs). Furthermore, Ash2l promoted the scavenger receptors transcription by catalyzing histone H3 lysine 4 (H3K4) trimethylation at the promoter region of transcription factor peroxisome proliferator-activated receptor-γ (PPARγ) and triggered the activation of the pro-inflammatory nuclear factor-kappa B (NF-κB) by enhancing interaction between CD36 and toll-like receptor 4 (TLR4). Meanwhile, enhanced expression of scavenger receptors drove more oxLDL uptake by ECs. In vivo studies revealed that ECs-specific Ash2l knockdown reduced atherosclerotic lesion formation and promoted fibrous cap stability in the aorta of ApoE-/- mice, which was partly associated with a reduced endothelial activation by suppressing scavenger receptors and the uptake of lipids by ECs. Collectively, our findings identify Ash2l as a novel regulator that mediates endothelial injury and atherosclerosis. Targeting Ash2l may provide valuable insights for developing novel therapeutic candidates for atherosclerosis.

Lifestyle and clinical factors as predictive indicators of cardiometabolic multimorbidity in Chinese adults: Baseline findings of the Beijing Health Management Cohort (BHMC) study

BACKGROUND

Cardiometabolic multimorbidity (CMM) is increasing globally as a result of lifestyle changes and the aging population. Even though previous studies have examined risk factors associated with CMM, there is a shortage of prediction models that can accurately identify high-risk individuals for early prevention.

METHODS

In the baseline survey of the Beijing Health Management Cohort, a total of 77,752 adults aged 18 years or older were recruited from 2020 to 2021. Data on lifestyle factors, clinical profiles, and diagnoses of diabetes, coronary heart disease, and stroke were collected. Logistic regression models were used to identify risk factors for CMM. Nomograms were developed to estimate an individual's probability of CMM based on the identified risk factors. The performance of the model was evaluated using the area under the receiver operating characteristic curve (AUC).

RESULTS

In men, the top three risk factors for CMM were hypertension (OR: 3.52, 95 % CI: 2.97-4.18), eating very fast (3.43, 2.27-5.16), and dyslipidemia (2.59, 2.20-3.06). In women, hypertension showed the strongest association with CMM (3.62, 2.90-4.52), followed by night sleep duration less than 5 h per day (2.41, 1.67-3.50) and dyslipidemia (1.91, 1.58-2.32). The ORs for holding passive and depressed psychological traits were 1.49 (95%CI: 1.08-2.06) in men and 1.58 (1.03-2.43) in women. Prediction models incorporating these factors demonstrated good discrimination in the test set, with AUC 0.84 (0.83-0.86) for men and 0.90 (0.89-0.91) for women. The sex-specific nomograms were established based on selected predictors.

CONCLUSIONS

Modifiable lifestyle factors, metabolic health and psychological trait are associated with the risk of CMM. The developed prediction models and nomograms could facilitate early identification of individuals at high-risk of CMM.

DNA methylation and histone post-translational modifications in atherosclerosis and a novel perspective for epigenetic therapy

Atherosclerosis, which is a vascular pathology characterized by inflammation and plaque build-up within arterial vessel walls, acts as the important cause of most cardiovascular diseases. Except for a lipid-depository and chronic inflammatory, increasing evidences propose that epigenetic modifications are increasingly associated with atherosclerosis and are of interest from both therapeutic and biomarker perspectives. The chronic progressive nature of atherosclerosis has highlighted atherosclerosis heterogeneity and the fact that specific cell types in the complex milieu of the plaque are, by far, not the only initiators and drivers of atherosclerosis. Instead, the ubiquitous effects of cell type are tightly controlled and directed by the epigenetic signature, which, in turn, is affected by many proatherogenic stimuli, including low-density lipoprotein, proinflammatory, and physical forces of blood circulation. In this review, we summarize the role of DNA methylation and histone post-translational modifications in atherosclerosis. The future research directions and potential therapy for the management of atherosclerosis are also discussed. Video Abstract.

A 2-decade bibliometric analysis of epigenetics of cardiovascular disease: from past to present

BACKGROUND

Cardiovascular disease (CVD) remains a major health killer worldwide, and the role of epigenetic regulation in CVD has been widely studied in recent decades. Herein, we perform a bibliometric study to decipher how research topics in this field have evolved during the past 2 decades.

RESULTS

Publications on epigenetics in CVD produced during the period 2000-2022 were retrieved from the Web of Science Core Collection (WoSCC). We utilized Bibliometrix to build a science map of the publications and applied VOSviewer and CiteSpace to assess co-authorship, co-citation, co-occurrence, and bibliographic coupling. In total, 27,762 publications were included for bibliometric analysis. The yearly amount of publications experienced exponential growth. The top 3 most influential countries were China, the United States, and Germany, while the most cited institutions were Nanjing Medical University, Harbin Medical University, and Shanghai Jiao Tong University. Four major research trends were identified: (a) epigenetic mechanisms of CVD; (b) epigenetics-based therapies for CVD; (c) epigenetic profiles of specific CVDs; and (d) epigenetic biomarkers for CVD diagnosis/prediction. The latest and most important research topics, including "nlrp3 inflammasome", "myocardial injury", and "reperfusion injury", were determined by detecting citation bursts of co-occurring keywords. The most cited reference was a review of the current knowledge about how miRNAs recognize target genes and modulate their expression and function.

CONCLUSIONS

The number and impact of global publications on epigenetics in CVD have expanded rapidly over time. Our findings may provide insights into the epigenetic basis of CVD pathogenesis, diagnosis, and treatment.

Longitudinal dynamics of circulating miRNAs in a swine model of familial hypercholesterolemia during early atherosclerosis

Atherosclerosis is a complex progressive disease involving intertwined biological mechanisms. We aimed to identify miRNA expression dynamics at the early stages of atherosclerosis using a large swine model (Wisconsin Miniature Swine, WMS). A total of 18 female pigs; 9 familial hypercholesterolemic (WMS-FH) and 9 normal control swine (WMS-N) were studied. miRNA sequencing was performed on plasma cell-free RNA at 3, 6, and 9 months of age. RT-qPCR validated DE miRNAs in a new cohort of animals (n = 30) with both sexes. Gene ontology and mRNA targets for DE miRNAs were identified. In vivo multimodality imaging and histopathology were performed to document the presence of atherosclerosis at termination. 20, 19, and 9 miRNAs were significantly DE between the groups at months 3, 6, and 9, respectively. Most DE miRNAs and their target genes are involved in human atherosclerosis development. Coronary atherosclerosis was documented in 7/9 WMS-FH pigs. Control animals had no lesions. miR-138, miR-152, miR-190a, and miR-196a showed a significant diagnostic power at month 3, whereas miR-486, miR-126-3p, miR-335, and miR-423-5p were of significant diagnostic power at month 9. In conclusion, specific DE miRNAs with significant discriminatory power may be promising biomarkers for the early detection of coronary atherosclerosis.

The mechanism and targeted intervention of the HIF-1 pathway in improving atherosclerotic heart's sensitivity to ischemic postconditioning

BACKGROUND

IPoC possesses a preventive effect against IR injury in healthy myocardium, but IPoC's protective effect on atherosclerotic myocardium is controversial. The current investigation aims to determine whether IPoC remains protective in atherosclerotic myocardium subjected to ischemia-reperfusion (IR) injury; to explore the specific mechanisms by which IPoC exerts cardioprotection; to explore whether HIF-1 upregulation combined with IPoC could further the provide cardioprotection; and to gaze at the specific mechanism whereby combined treatment expert the cardioprotection.

METHODS

ApoE-/- mice fed with a high-fat diet (HFD) were used to develop a model of atherosclerosis. The myocardial IR model was induced by occlusion of the left anterior descending (LAD) artery for 45 min, followed by reperfusion for 120 min. The protection of IPoC in both healthy and atherosclerotic myocardium was evaluated by measuring oxidative stress, apoptosis, infarct size, pathology, mitochondrial dysfunction and morphology of myocardium. The specific mechanism by which IPoC exerts cardioprotection in healthy and atherosclerotic myocardium was observed by measuring the expression of proteins involved in HIF-1, APMK and RISK pathways. The effect of HIF-1α overexpression on the cardioprotection by IPoC was observed by intravenous AAV9 -HIF-1α injection.

RESULTS

In healthy ischemic myocardium, IPoC exerted myocardial protective effects (antioxidant, anti-apoptosis, and improved mitochondrial function) through the activation of HIF-1, AMPK and RISK pathways. In atherosclerotic ischemic myocardium, IPoC exerted cardioprotection only through the activation of HIF-1 pathway; however, HIF-1 overexpression combined IPoC restored the activation of AMPK and RISK pathways, thereby further alleviating the myocardial IR injury.

CONCLUSIONS

In the atherosclerotic state, the HIF-1 pathway is the intrinsic mechanism by which IPoC exerts cardioprotective effects. The combination of HIF-1 upregulation and IPoC has a significant effect in reducing myocardial injury, which is worth being promoted and advocated. In addition, HIF-1-AMPK and HIF-1-RISK may be two endogenous cardioprotective signalling pathways with great value, which deserve to be thoroughly investigated in the future.

Role of lncRNAs in Remodeling of the Coronary Artery Plaques in Patients with Atherosclerosis

INTRODUCTION

Cardiovascular diseases (CVDs) are the leading cause of death worldwide according to World Health Organization (WHO) data. Atherosclerosis is considered as a chronic inflammatory disease that develops in response to damage to the vascular intima-media layer in most cases. In recent years, epigenetic events have emerged as important players in the development and progression of CVDs. Since noncoding RNA (ncRNAs) are important regulators in the organization of the pathophysiological processes of the cardiovascular system, they have the potential to be used as therapeutic targets, diagnostic and prognostic biomarkers. In this study long noncoding RNA (lncRNA) and mRNA gene expression were compared between coronary atherosclerotic plaques (CAP) and the internal mammary artery (IMA)  which has the same genetic makeup and is exposed to the same environmental stress conditions with CAP in the same individual.

METHODS

lncRNA and mRNA gene expressions were determined using the microarray in the samples. Microarray results were validated by RT-qPCR. Differentially expressed genes (DEGs; lncRNAs and mRNAs) were determined by GeneSpring (Ver 3.0) [p values < 0.05 and fold change (FC) > 2]. DAVID bioinformatics program was used for Gene Ontology (GO) annotation and enrichment analyses of statistically significant genes between CAP and IMA tissue.

RESULTS AND CONCLUSIONS

In our study, 345 DEGs were found to be statistically significant (p < 0.05; FC > 2) between CAP and IMA. Of these, 65 were lncRNA and 280 were mRNA. Thirty-three lncRNAs were upregulated, while 32 lncRNAs were downregulated. Some of the important mRNAs are SPP1, CYP4B1, CHRDL1, MYOC, and ALKAL2, while some of the lncRNAs are LOC105377123, LINC01857, DIO3OS, LOC101928134, and KCNA3 between CAP and IMA tissue. We also identified genes that correlated with statistically significant lncRNAs. The results of this study are expected to be an important source of data in the development of new genetically based drugs to prevent atherosclerotic plaque. In addition, the data obtained may contribute to the explanation of the epigenetic mechanisms that play a role in the pathological basis of the process that protects the IMA from atherosclerosis.

Circ_0090231 knockdown protects vascular smooth muscle cells from ox-LDL-induced proliferation, migration and invasion via miR-942-5p/PPM1B axis during atherosclerosis

Atherosclerosis (AS) is a dominant pathological basis of cardiovascular disease. Circular RNAs (circRNAs) have been proposed to have crucial functions in regulating pathological progressions of AS. Hence, the aim of this study was to investigate the potential function of circ_0090231 in AS progression. Oxidized low densitylipoprotein (ox-LDL)-challenged vascular smooth muscle cells (VSMCs) were used for in vitro functional analysis. Levels of genes and proteins were measured by qRT-PCR and Western blot. The proliferation, migration and invasion were assessed using cell counting kit-8, 5-ethynyl-2'-deoxyuridine, and transwell assays. The interaction between miR-942-5p and circ_0090231 or PPM1B (Protein Phosphatase, Mg²⁺/Mn²⁺ Dependent 1B) was evaluated by dual-luciferase reporter and pull-down assays. Circ_0090231 is a stable circRNA, and was increased in the serum of AS patients and ox-LDL-challenged VSMCs. Functionally, silencing of circ_0090231 could reverse ox-LDL-induced proliferation, migration and invasion in VSMCs. Mechanistically, circ_0090231 directly targeted miR-942-5p, and PPM1B was a target of miR-942-5p. Besides, circ_0090231 sequestered miR-942-5p to release PPM1B expression, suggesting the circ_0090231/miR-942-5p/PPM1B axis. Further rescue experiments showed that miR-942-5p inhibition or ectopic overexpression of PPM1B dramatically attenuated the suppressing influences of circ_0090231 knockdown on VSMC proliferative, migratory and invasive abilities under ox-LDL treatment. Silencing of circ_0090231 could reverse ox-LDL-induced proliferation, migration and invasion in VSMCs via miR-942-5p/PPM1B axis, providing a theoretical basis for elucidating the mechanism of AS process.

Hypomethylation of ABCG1 in peripheral blood as a potential marker for the detection of coronary heart disease

BACKGROUND

Novel molecular biomarkers for the risk assessment and early detection of coronary heart disease (CHD) are urgently needed for disease prevention. Altered methylation of ATP-binding cassette subfamily G member 1 (ABCG1) has been implicated in CHD but was mostly studied in Caucasians. Exploring the potential relationship between ABCG1 methylation in blood and CHD among the Chinese population would yield valuable insights.

METHODS

Peripheral blood samples were obtained from a case-control study (287 CHD patients vs. 277 controls) and a prospective nested case-control study (171 CHD patients and 197 matched controls). DNA extraction and bisulfite-specific PCR amplification techniques were employed for sample processing. Quantitative assessment of methylation levels was conducted using mass spectrometry. Statistical analyses involved the utilization of logistic regression and nonparametric tests.

RESULTS

We found hypomethylation of ABCG1 in whole blood was associated with the risk of CHD in both studies, which was enhanced in heart failure (HF) patients, female and younger subjects. When combined with baseline characteristics, altered ABCG1 methylation showed improved predictive effect for differentiating CHD cases, ischemic cardiomyopathy (ICM) cases, younger than 60 years CHD cases, and female CHD cases from healthy controls (area under the curve (AUC) = 0.68, 0.71, 0.74, and 0.73, respectively).

CONCLUSIONS

We demonstrated a robust link between ABCG1 hypomethylation in whole blood and CHD risk in the Chinese population and provided novel evidence indicating that aberrant ABCG1 methylation in peripheral blood can serve as an early detection biomarker for CHD patients.

Impact of Plasmodium falciparum infection on DNA methylation of circulating immune cells

The regulation of immune cell responses to infection is a complex process that involves various molecular mechanisms, including epigenetic regulation. DNA methylation has been shown to play central roles in regulating gene expression and modulating cell response during infection. However, the nature and extent to which DNA methylation is involved in the host immune response in human malaria remains largely unknown. Here, we present a longitudinal study investigating the temporal dynamics of genome-wide in vivo DNA methylation profiles using 189 MethylationEPIC 850 K profiles from 66 children in Burkina Faso, West Africa, sampled three times: before infection, during symptomatic parasitemia, and after malaria treatment. The results revealed major changes in the DNA methylation profiles of children in response to both Plasmodium falciparum infection and malaria treatment, with widespread hypomethylation of CpGs upon infection (82% of 6.8 K differentially methylated regions). We document a remarkable reversal of CpG methylation profiles upon treatment to pre-infection states. These changes implicate divergence in core immune processes, including the regulation of lymphocyte, neutrophil, and myeloid leukocyte function. Integrative DNA methylation-mRNA analysis of a top differentially methylated region overlapping the pro-inflammatory gene TNF implicates DNA methylation of TNF cis regulatory elements in the molecular mechanisms of TNF regulation in human malaria. Our results highlight a central role of epigenetic regulation in mounting the host immune response to P. falciparum infection and in response to malaria treatment.

Integrative analysis of hepatic transcriptional profiles reveals genetic regulation of atherosclerosis in hyperlipidemic Diversity Outbred-F1 mice

Atherogenesis is an insipidus but precipitating process leading to serious consequences of many cardiovascular diseases (CVD). Numerous genetic loci contributing to atherosclerosis have been identified in human genome-wide association studies, but these studies have limitations in the ability to control environmental factors and to decipher cause/effect relationships. To assess the power of hyperlipidemic Diversity Outbred (DO) mice in facilitating quantitative trait loci (QTL) analysis of complex traits, we generated a high-resolution genetic panel of atherosclerosis susceptible (DO-F1) mouse cohort by crossing 200 DO females with C57BL/6J males carrying two human genes: encoding apolipoprotein E3-Leiden and cholesterol ester transfer protein. We examined atherosclerotic traits including plasma lipids and glucose in the 235 female and 226 male progeny before and after 16 weeks of a high-fat/cholesterol diet, and aortic plaque size at 24 weeks. We also assessed the liver transcriptome using RNA-sequencing. Our QTL mapping for atherosclerotic traits identified one previously reported female-specific QTL on Chr10 with a narrower interval of 22.73 to 30.80 Mb, and one novel male-specific QTL at 31.89 to 40.25 Mb on Chr19. Liver transcription levels of several genes within each QTL were highly correlated with the atherogenic traits. A majority of these candidates have already known atherogenic potential in humans and/or mice, but integrative QTL, eQTL, and correlation analyses further pointed Ptprk as a major candidate of the Chr10 QTL, while Pten and Cyp2c67 of the Chr19 QTL in our DO-F1 cohort. Finally, through additional analyses of RNA-seq data we identified genetic regulation of hepatic transcription factors, including Nr1h3, contributes to atherogenesis in this cohort. Thus, an integrative approach using DO-F1 mice effectively validates the influence of genetic factors on atherosclerosis in DO mice and suggests an opportunity to discover therapeutics in the setting of hyperlipidemia.

Epigenetic Mechanisms of Aging and Aging-Associated Diseases

Aging is an inevitable outcome of life, characterized by a progressive decline in tissue and organ function. At a molecular level, it is marked by the gradual alterations of biomolecules. Indeed, important changes are observed on the DNA, as well as at a protein level, that are influenced by both genetic and environmental parameters. These molecular changes directly contribute to the development or progression of several human pathologies, including cancer, diabetes, osteoporosis, neurodegenerative disorders and others aging-related diseases. Additionally, they increase the risk of mortality. Therefore, deciphering the hallmarks of aging represents a possibility for identifying potential druggable targets to attenuate the aging process, and then the age-related comorbidities. Given the link between aging, genetic, and epigenetic alterations, and given the reversible nature of epigenetic mechanisms, the precisely understanding of these factors may provide a potential therapeutic approach for age-related decline and disease. In this review, we center on epigenetic regulatory mechanisms and their aging-associated changes, highlighting their inferences in age-associated diseases.

Mitochondrial miRNA as epigenomic signatures: Visualizing aging-associated heart diseases through a new lens

Aging bears many hard knocks, but heart disorders earn a particular allusion, being the most widespread. Cardiovascular diseases (CVDs) are becoming the biggest concern to mankind due to sundry health conditions directly or indirectly related to heart-linked abnormalities. Scientists know that mitochondria play a critical role in the pathophysiology of cardiac diseases. Both environment and genetics play an essential role in modulating and controlling mitochondrial functions. Even a minor abnormality may prove detrimental to heart function. Advanced age combined with an unhealthy lifestyle can cause most cardiomyocytes to be replaced by fibrotic tissue which upsets the conducting system and leads to arrhythmias. An aging heart encounters far more heart-associated comorbidities than a young heart. Many state-of-the-art technologies and procedures are already being used to prevent and treat heart attacks worldwide. However, it remains a mystery when this heart bomb would explode because it lacks an alarm. This calls for a novel and effective strategy for timely diagnosis and a sure-fire treatment. This review article provides a comprehensive overture of prospective potentials of mitochondrial miRNAs that predict complicated and interconnected pathways concerning heart ailments and signature compilations of relevant miRNAs as biomarkers to plot the role of miRNAs in epigenomics. This article suggests that analysis of DNA methylation patterns in age-associated heart diseases may determine age-impelled biomarkers of heart disease.

Circulating microRNAs as potential biomarkers of early vascular damage in vitamin D deficiency, obese, and diabetic patients

Vitamin D3 deficiency, obesity, and diabetes mellitus (DM) have been shown to increase the risk of cardiovascular diseases (CVDs). However, the early detection of vascular damage in those patients is still difficult to ascertain. MicroRNAs (miRNAs) are recognized to play a critical role in initiation and pathogenesis of vascular dysfunction. Herein, we aimed to identify circulating miRNA biomarkers of vascular dysfunction as early predictors of CVDs. We have recruited 23 middle-aged Emiratis patients with the following criteria: A healthy control group with vitamin D ≥ 20ng, and BMI < 30 (C1 group = 11 individuals); A vitamin D deficiency (Vit D level ≤ 20 ng) and obese (BMI ≥ 30) group (A1 group = 9 patients); A vitamin D deficiency, obese, plus DM (A2 group = 3 patients). Arterial stiffness via pulse wave velocity (PWV) was measured and the whole transcriptome analysis with qPCR validation for miRNA in plasma samples were tested. PWV relative to age was significantly higher in A1 group 19.4 ± 4.7 m/s and A2 group 18.3 ± 1.3 m/s compared to controls 14.7 ± 2.1 m/s (p < 0.05). Similar patterns were also observed in the Augmentation pressure (AP) and Alx%. Whole RNA-Sequencing revealed miR-182-5p; miR-199a-5p; miR-193a-5p; and miR-155-5p were differentially over-expressed (logFC > 1.5) in high-risk patients for CVDs vs healthy controls. Collectively, our result indicates that four specific circulating miRNA signature, may be utilized as non-invasive, diagnostic and prognostic biomarkers for early vascular damage in patients suffering from vitamin D deficiency, obesity and DM.

Histone modification landscape and the key significance of H3K27me3 in myocardial ischaemia/reperfusion injury

Histone modifications play crucial roles in the pathogenesis of myocardial ischaemia/reperfusion (I/R) injury. However, a genome-wide map of histone modifications and the underlying epigenetic signatures in myocardial I/R injury have not been established. Here, we integrated transcriptome and epigenome of histone modifications to characterize epigenetic signatures after I/R injury. Disease-specific histone mark alterations were mainly found in H3K27me3-, H3K27ac-, and H3K4me1-marked regions 24 and 48 h after I/R. Genes differentially modified by H3K27ac, H3K4me1 and H3K27me3 were involved in immune response, heart conduction or contraction, cytoskeleton, and angiogenesis. H3K27me3 and its methyltransferase polycomb repressor complex 2 (PRC2) were upregulated in myocardial tissues after I/R. Upon selective inhibition of EZH2 (the catalytic core of PRC2), the mice manifest improved cardiac function, enhanced angiogenesis, and reduced fibrosis. Further investigations confirmed that EZH2 inhibition regulated H3K27me3 modification of multiple pro-angiogenic genes and ultimately enhanced angiogenic properties in vivo and in vitro. This study delineates a landscape of histone modifications in myocardial I/R injury, and identifies H3K27me3 as a key epigenetic modifier in I/R process. The inhibition of H3K27me3 and its methyltransferase might be a potential strategy for myocardial I/R injury intervention.

Silencing of Long Noncoding RNA TUG1 Ameliorates Atherosclerosis-Induced Myocardial Injury by Upregulating microRNA-30b-3p and Downregulating Brd4

ABSTRACT

Long noncoding RNAs and microRNAs (miRNAs) are emerging biomarkers involved in human diseases, and we focused on the roles of long noncoding RNA taurine upregulated gene 1 (TUG1) and miR-30b-3p in the related mechanisms of atherosclerosis-induced myocardial injury. ApoE-deficient mice were fed with high-fat diet to establish atherosclerotic models and then were subjected to either TUG1 downregulation or miR-30b-3p upregulation treatment. The serum myocardial enzymes, inflammatory biomarkers, pathological changes, intramyocardial macrophage infiltration, and apoptosis of cardiomyocytes in atherosclerotic mice were determined. The expression of TUG1, miR-30b-3p, and bromodomain protein 4 (Brd4) in atherosclerotic models was evaluated. Moreover, the correlations of TUG1, miR-30b-3p, and Brd4 were verified. TUG1 and Brd4 were increased while miR-30b-3p was decreased in atherosclerotic mice. The silenced TUG1 or elevated miR-30b-3p attenuated atherosclerosis-induced myocardial injury mainly by reducing serum myocardial enzyme content and inflammatory response, improving pathological changes, and preventing macrophage infiltration and cardiomyocyte apoptosis in atherosclerotic mice. Mechanistically, TUG1 could competitively bind with miR-30b-3p to prevent the degradation of its target gene Brd4. This study reveals that the silencing of TUG1 ameliorates atherosclerosis-induced myocardial injury by upregulating miR-30b-3p and downregulating Brd4, which may provide novel targets for atherosclerosis treatment.

Long Noncoding RNA TPRG1-AS1 Suppresses Migration of Vascular Smooth Muscle Cells and Attenuates Atherogenesis via Interacting With MYH9 Protein

BACKGROUND

Migration of human aortic smooth muscle cells (HASMCs) contributes to the pathogenesis of atherosclerosis. This study aims to functionally characterize long noncoding RNA TPRG1-AS1 (tumor protein p63 regulated 1, antisense 1) in HASMCs and reveal the underlying mechanism of TPRG1-AS1 in HASMCs migration, neointima formation, and subsequent atherosclerosis.

METHODS

The expression of TPRG1-AS1 in atherosclerotic plaques was verified a series of in silico analysis and quantitative real-time polymerase chain reaction analysis. Northern blot, rapid amplification of cDNA ends and Sanger sequencing were used to determine its full length. In vitro transcription-translation assay was used to investigate the protein-coding capacity of TPRG1-AS1. RNA fluorescent in situ hybridization was used to confirm its subcellular localization. Loss- and gain-of-function studies were used to investigate the function of TPRG1-AS1. Furthermore, the effect of TPRG1-AS1 on the pathological response was evaluated in carotid balloon injury model, wire injury model, and atherosclerosis model, respectively.

RESULTS

TPRG1-AS1 was significantly increased in atherosclerotic plaques. TPRG1-AS1 did not encode any proteins and its full length was 1279nt, which was bona fide a long noncoding RNA. TPRG1-AS1 was mainly localized in cytoplasmic and perinuclear regions in HASMCs. TPRG1-AS1 directly interacted with MYH9 (myosin heavy chain 9) protein in HASMCs, promoted MYH9 protein degradation through the proteasome pathway, hindered F-actin stress fiber formation, and finally inhibited HASMCs migration. Vascular smooth muscle cell-specific transgenic overexpression of TPRG1-AS1 significantly reduced neointima formation, and attenuated atherosclerosis in apolipoprotein E knockout (Apoe^-/-) mice.

CONCLUSIONS

This study demonstrated that TPRG1-AS1 inhibited HASMCs migration through interacting with MYH9 protein and consequently suppressed neointima formation and atherosclerosis.

Molecular hallmarks of long non-coding RNAs in aging and its significant effect on aging-associated diseases

Aging is linked to the deterioration of many physical and cognitive abilities and is the leading risk factor for Alzheimer's disease. The growing aging population is a significant healthcare problem globally that researchers must investigate to better understand the underlying aging processes. Advances in microarrays and sequencing techniques have resulted in deeper analyses of diverse essential genomes (e.g., mouse, human, and rat) and their corresponding cell types, their organ-specific transcriptomes, and the tissue involved in aging. Traditional gene controllers such as DNA- and RNA-binding proteins significantly influence such programs, causing the need to sort out long non-coding RNAs, a new class of powerful gene regulatory elements. However, their functional significance in the aging process and senescence has yet to be investigated and identified. Several recent researchers have associated the initiation and development of senescence and aging in mammals with several well-reported and novel long non-coding RNAs. In this review article, we identified and analyzed the evolving functions of long non-coding RNAs in cellular processes, including cellular senescence, aging, and age-related pathogenesis, which are the major hallmarks of long non-coding RNAs in aging.

Identification of distinct circulating microRNAs in acute ischemic stroke patients with type 2 diabetes mellitus

Stroke is the second leading cause of global mortality and continued efforts aim to identify predictive, diagnostic, or prognostic biomarkers to reduce the disease burden. Circulating microRNAs (miRNAs) have emerged as potential biomarkers in stroke. We performed comprehensive circulating miRNA profiling of ischemic stroke patients with or without type 2 diabetes mellitus (T2DM), an important risk factor associated with worse clinical outcomes in stroke. Serum samples were collected within 24 h of acute stroke diagnosis and circulating miRNAs profiled using RNA-Seq were compared between stroke patients with T2DM (SWDM; n = 92) and those without T2DM (SWoDM; n = 98). Our analysis workflow involved random allocation of study cohorts into discovery (n = 96) and validation (n = 94) datasets. Five miRNAs were found to be differentially regulated in SWDM compared to SWoDM patients. Hsa-miR-361-3p and -664a-5p were downregulated, whereas miR-423-3p, -140-5p, and -17-3p were upregulated. We also explored the gene targets of these miRNAs and investigated the downstream pathways associated with them to decipher the potential pathways impacted in stroke with diabetes as comorbidity. Overall, our novel findings provide important insights into the differentially regulated miRNAs, their associated pathways and potential utilization for clinical benefits in ischemic stroke patients with diabetes.

Bioinformatic analysis and experimental validation identified DNA methylation–Related biomarkers and immune-cell infiltration of atherosclerosis

Background: DNA methylation is an important form of epigenetic regulation and is closely related to atherosclerosis (AS). The purpose of this study was to identify DNA methylation–related biomarkers and explore the immune-infiltrate characteristics of AS based on methylation data.

Methods: DNA methylation data of 15 atherosclerotic and paired healthy tissues were obtained from Gene Expression Omnibus database. Differential methylation positions (DMPs) and differential methylation regions (DMRs) were screened by the ChAMP R package. The methylation levels of DMPs located on CpG islands of gene promoter regions were averaged. The limma R package was used to screen differentially methylated genes in the CpG islands of the promoter regions. The diagnostic values of the methylation levels were evaluated using the pROC R package. The EpiDISH algorithm was applied to quantify the infiltration levels of seven types of immune cells. Subsequently, three pairs of clinical specimens of coronary atherosclerosis with Stary’s pathological stage III were collected, and the methylation levels were detected by the methylation-specific PCR (MS-PCR) assay. Western blot was performed to detect the protein expression levels of monocyte markers.

Results: A total of 110, 695 DMPs, and 918 DMRs were screened in the whole genome. Also, six genes with significant methylation differences in the CpG islands of the promoter regions were identified, including 49 DMPs. In total, three genes (GRIK2, HOXA2, and HOXA3) had delta beta greater than 0.2. The infiltration level of monocytes was significantly upregulated in AS tissues. MS-PCR assay confirmed the methylation status of the aforementioned three genes in AS samples. The Western blot results showed that the expression levels of the monocyte marker CD14 and M1-type macrophage marker CD86 were significantly increased in AS while M2-type macrophage marker protein CD206 was significantly decreased.

Conclusion: This study identified potential DNA methylation–related biomarkers and revealed the role of monocytes in early AS.

Quality assessment and Q-markers discovery of Tongsaimai tablet by integrating serum pharmacochemistry and network pharmacology for anti-atherosclerosis benefit

Background

The limited therapeutic outcomes of atherosclerosis (AS) have allowed, traditional Chinese medicine has been well established as an alternative approach in ameliorating AS and associated clinical syndromes. Clinically, Tongsaimai tablet (TSMT), a commercial Chinese patent medicine approved by CFDA, shows an obvious therapeutic effect on AS treatment. However, its effective mechanism and quality control still need thorough and urgent exploration.

Methods

The mice were orally administered with TSMT and their serum was investigated for the absorbed compounds using serum pharmacochemistry via the UPLC-Q-Exactive Orbitrap/MS analysis was employed to investigate these absorbed compounds in serum of mice orally administrated with TSMT. Based on these absorbed prototype compounds in serum derived from TSMT, a component-target-disease network was constructed using network pharmacology strategy, which elucidated the potential bioactive components, effective targets, and molecular mechanisms of TSMT against AS. Further, the screened compounds from the component-target network were utilized as the quality control (QC) markers, determining multi-component content determination and HPLC fingerprint to assess quality of nine batches of TSMT samples.

Results

A total of 164 individual components were identified in TSMT. Among them, 29 prototype compounds were found in serum of mice administrated with TSMT. Based on these candidate prototype components, 34 protein targets and 151 pathways related to AS were predicted, and they might significantly exhibit potential anti-AS mechanisms via synergistic regulations of lipid regulation, shear stress, and anti-inflammation, etc. Five potentially bioactive ingredients in TSMT, including Ferulic acid, Liquiritin, Senkyunolide I, Luteolin and Glycyrrhizic acid in quantity not less than 1.2798, 0.4716, 0.5419, 0.1349, 4.0386 mg/g, respectively, screened from the component-target-pathway network. Thereby, these indicated that these five compounds of TMST which played vital roles in the attenuation of AS could serve as crucial marker compounds for quality control.

Conclusions

Overall, based on the combination of serum pharmacochemistry and network pharmacology, the present study firstly provided a useful strategy to establish a quality assessment approach for TSMT by screening out the potential anti-AS mechanisms and chemical quality markers.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13020-022-00658-9.

Helicobacter pylori infection and DNMT3a polymorphism are associated with the presence of premature coronary artery disease and subclinical atherosclerosis. Data from the GEA Mexican Study

BACKGROUND

The association between H. pylori infection and coronary artery disease (CAD) is well-known. Alterations in DNA methylation in CAD have been reported, which can be induced by H. pylori through the DNA demethylases (DNMTs). The objective was to analyze the association and interaction of H. pylori infection and DMNT3a gene polymorphisms with premature CAD (pCAD) and subclinical atherosclerosis (SA).

METHODS

The study included 561 patients with pCAD, 318 subjects with SA, and 599 healthy controls. Antibodies against H. pylori and DNMT3a rs13420827, rs752208, and rs1550117 polymorphisms were determined.

RESULTS

The pCAD group presented the highest seroprevalence of H. pylori infection (87.7%) compared to the SA (74.5%, p = 1 × 10^-6) and the control group (63.1%, p = 7 × 10^-23). A significant association was observed between H. pylori infection and pCAD (OR = 2.729, p = 1.0 × 10^-6). The rs13420827 polymorphism was associated with a high risk of H. pylori infection in the whole population (p_additive = 0.009, p_dominant = 0.018, and p_codominant2 = 0.013) and in individuals with SA (p_additive = 0.003, p_dominant = 0.020, p_recessive = 0.013, and p_codominant2 = 0.005). The coexistence of H. pylori infection and the rs13420827GG genotype increases the risk of pCAD (p_interaction = 1.1 × 10^-5).

CONCLUSIONS

According to the model adjusted for more confounding variables, H. pylori infection was associated with almost three times the risk of developing pCAD. The rs13420827G allele was associated with an increased risk of H. pylori infection in the whole population and in individuals with SA. Individuals in whom H. pylori infection and the rs13420827GG genotype coexist are at increased risk of pCAD.

CHOP Increases TRIB3-Dependent miR-208 Expression to Potentiate Vascular Smooth Muscle Cell Proliferation and Migration by Downregulating TIMP3 in Atherosclerosis

BACKGROUND

C/EBP homologous protein (CHOP) has been identified as a suitable therapeutic target to combat atherosclerosis but the mechanism has not been fully studied. Here, we sought to define the role and underlying mechanism of CHOP in atherosclerosis.

METHODS

Mouse models of atherosclerosis in ApoE-/- mice were established by high-fat feeding, where miR-208 expression was determined. Then atherosclerotic plaque tissues were isolated from the model mice. Loss- and gain-function assays were performed on trypsinized vascular smooth muscle cells (VSMCs) to test the in vitro effect of CHOP in controlling the tribbles homologue 3 (TRIB3)/microRNA-208 (miR-208)/tissue inhibitor of metalloproteinases-3 (TIMP3) axis in atherosclerosis by determining cell proliferation and migration as well as blood lipid levels. Moreover, expression of α-smooth muscle actin (α-SMA) and type I collagen expression was determined using immunofluorescence staining to assess plaque stability in mice.

RESULTS

miR-208 expression was elevated in atherosclerosis samples and miR-208 overexpression promoted proliferation and migration of VSMCs but diminished plaque stability in mice. TIMP3 was targeted by miR-208, which could be abrogated by upregulation of TIMP3. In addition, CHOP increased TRIB3 expression to upregulate miR-208 and to downregulate TIMP3, which potentiated VSMC proliferation and migration in vitro and in vivo.

CONCLUSION

Taken together, inhibition of CHOP may inhibit the proliferation and migration of VSMCs as well as reduce the levels of TC, TG, and LDL-C but increase the level of HDL-C through the TRIB3/miR-208/TIMP3 axis, thereby inhibiting the progression of atherosclerosis.

Tackling Atherosclerosis via Selected Nutrition

The development and pathogenesis of atherosclerosis are significantly influenced by lifestyle, particularly nutrition. The modern level of science and technology development promote personalized nutrition as an efficient preventive measure against atherosclerosis. In this survey, the factors were revealed that contribute to the formation of an individual approach to nutrition: genetic characteristics, the state of the microbiota of the gastrointestinal tract (GIT) and environmental factors (diets, bioactive components, cardioprotectors, etc.). In the course of the work, it was found that in order to analyze the predisposition to atherosclerosis associated with nutrition, genetic features affecting the metabolism of nutrients are significant. The genetic features include the presence of single nucleotide polymorphisms (SNP) of genes and epigenetic factors. The influence of telomere length on the pathogenesis of atherosclerosis and circadian rhythms was also considered. Relatively new is the study of the relationship between chrono-nutrition and the development of metabolic diseases. That is, to obtain the relationship between nutrition and atherosclerosis, a large number of genetic markers should be considered. In this relation, the question arises: “How many genetic features need to be analyzed in order to form a personalized diet for the consumer?” Basically, companies engaged in nutrigenetic research and choosing a diet for the prevention of a number of metabolic diseases use SNP analysis of genes that accounts for lipid metabolism, vitamins, the body’s antioxidant defense system, taste characteristics, etc. There is no set number of genetic markers. The main diets effective against the development of atherosclerosis were considered, and the most popular were the ketogenic, Mediterranean, and DASH-diets. The advantage of these diets is the content of foods with a low amount of carbohydrates, a high amount of vegetables, fruits and berries, as well as foods rich in antioxidants. However, due to the restrictions associated with climatic, geographical, material features, these diets are not available for a number of consumers. The way out is the use of functional products, dietary supplements. In this approach, the promising biologically active substances (BAS) that exhibit anti-atherosclerotic potential are: baicalin, resveratrol, curcumin, quercetin and other plant metabolites. Among the substances, those of animal origin are popular: squalene, coenzyme Q10, omega-3. For the prevention of atherosclerosis through personalized nutrition, it is necessary to analyze the genetic characteristics (SNP) associated with the metabolism of nutrients, to assess the state of the microbiota of the GIT. Based on the data obtained and food preferences, as well as the individual capabilities of the consumer, the optimal diet can be selected. It is topical to exclude nutrients of which their excess consumption stimulates the occurrence and pathogenesis of atherosclerosis and to enrich the diet with functional foods (FF), BAS containing the necessary anti-atherosclerotic, and stimulating microbiota of the GIT nutrients. Personalized nutrition is a topical preventive measure and there are a number of problems hindering the active use of this approach among consumers. The key factors include weak evidence of the influence of a number of genetic features, the high cost of the approach, and difficulties in the interpretation of the results. Eliminating these deficiencies will contribute to the maintenance of a healthy state of the population through nutrition.

Studying Epigenetics of Cardiovascular Diseases on Chip Guide

Epigenetics is defined as the study of inheritable changes in the gene expressions and phenotypes that occurs without altering the normal DNA sequence. These changes are mainly due to an alteration in chromatin or its packaging, which changes the DNA accessibility. DNA methylation, histone modification, and noncoding or microRNAs can best explain the mechanism of epigenetics. There are various DNA methylated enzymes, histone-modifying enzymes, and microRNAs involved in the cause of various CVDs (cardiovascular diseases) such as cardiac hypertrophy, heart failure, and hypertension. Moreover, various CVD risk factors such as diabetes mellitus, hypoxia, aging, dyslipidemia, and their epigenetics are also discussed together with CVDs such as CHD (coronary heart disease) and PAH (pulmonary arterial hypertension). Furthermore, different techniques involved in epigenetic chromatin mapping are explained. Among these techniques, the ChIP-on-chip guide is explained with regard to its role in cardiac hypertrophy, a final form of heart failure. This review focuses on different epigenetic factors that are involved in causing cardiovascular diseases.

Evaluation of arterial stiffness and central blood pressure by oscillometric method in normotensive offspring of hypertensive parents

Children with a family history of hypertension have higher blood pressure and hypertensive pathophysiological changes begin before clinical findings. Here, the presence of arterial stiffness was investigated using central blood pressure measurement and pulse wave analysis in normotensive children with at least one parent with essential hypertension. Twenty-four-hour ambulatory pulse wave analysis monitoring was performed by oscillometric method in a study group of 112 normotensive children of hypertensive parents aged between 7 and 18 comparing with a control group of 101 age- and gender-matched normotensive children of normotensive parents. Pulse wave velocity, central systolic and diastolic blood pressure, systolic, diastolic and mean arterial blood pressure values were higher in the study group than the control group (p < 0.001, p = 0.002, p = 0.008, p = 0.001, p = 0.005, p = 0.001, p = 0.001, respectively). In all age groups (7-10, 11-14, and 15-18 years), pulse wave velocity was higher in the study group than the control group (p < 0.001). Pulse wave velocity was higher in children whose both parents are hypertensive compared to the children whose only mothers are hypertensive (p = 0.011). Pulse wave velocity values were positively correlated with age, weight, height, and body mass index (p < 0.05). Higher pulse wave velocity, central systolic and diastolic blood pressure values detected in the study group can be considered as early signs of hypertensive vascular changes. Pulse wave analysis can be a reliable, non-invasive, and reproducible method that can allow taking necessary precautions regarding lifestyle to prevent disease and target organ damage by detecting early hypertensive changes in genetically risky children.

Methyltransferase-like 14 silencing relieves the development of atherosclerosis via m6A modification of p65 mRNA

To explore the METTL14-dependent m⁶A modification mechanism involved in the development of atherosclerosis. Oxidized low-density lipoprotein (ox-LDL) and the HUVEC cell line were used to establish an atherosclerosis cell model in vitro, and APOE^−/− mice fed a high-fat diet were used as the animal model. Cell viability and apoptosis were assessed using MTT assays and flow cytometry. The status of m⁶A in HUVECs was examined using MeRIP-qPCR. Oil Red O staining was used to evaluate the lesions or plaques on aortas separated from the target mice. METTL14 and METTL3 were upregulated in HUVECs after ox-LDL treatment. After transfection with si-METTL14, the bcl-2 expression level and the viability of ox-LDL-incubated cells increased, whereas the apoptosis rate and the expressions of Bax and cleaved caspase-3 decreased. However, the effect of METTL14 knockdown was reversed by p65 overexpression. After METTL14 knockdown, there was a decrease in the total m⁶A content in HUVECs, m⁶A modification, and p65 expression. The plaques and lesion areas on the high-fat diet APOE^−/− mouse aortas were smaller after METTL14 silencing. METTL14 reduced cell viability and promoted apoptosis of HUVECs, which were both induced by ox-LDL via m⁶A modification of p65. Knocking down METTL14 could inhibit the development of atherosclerosis in high-fat diet-treated APOE^−/− mice.

Integrated investigation of DNA methylation, gene expression and immune cell population revealed immune cell infiltration associated with atherosclerotic plaque formation

Background

The clinical consequences of atherosclerosis are significant source of morbidity and mortality throughout the world, while the molecular mechanisms of the pathogenesis of atherosclerosis are largely unknown.

Methods

In this study, we integrated the DNA methylation and gene expression data in atherosclerotic plaque samples to decipher the underlying association between epigenetic and transcriptional regulation. Immune cell classification was performed on the basis of the expression pattern of detected genes. Finally, we selected ten genes with dysregulated methylation and expression levels for RT-qPCR validation.

Results

Global DNA methylation profile showed obvious changes between normal aortic and atherosclerotic lesion tissues. We found that differentially methylated genes (DMGs) and differentially expressed genes (DEGs) were highly associated with atherosclerosis by being enriched in atherosclerotic plaque formation-related pathways, including cell adhesion and extracellular matrix organization. Immune cell fraction analysis revealed that a large number of immune cells, especially macrophages, activated mast cells, NK cells, and Tfh cells, were specifically enriched in the plaque. DEGs associated with immune cell fraction change showed that they were mainly related to the level of macrophages, monocytes, resting NK cells, activated CD4 memory T cells, and gamma delta T cells. These genes were highly enriched in multiple pathways of atherosclerotic plaque formation, including blood vessel remodeling, collagen fiber organization, cell adhesion, collagen catalogic process, extractable matrix assembly, and platelet activation. We also validated the expression alteration of ten genes associated with infiltrating immune cells in atherosclerosis.

Conclusions

In conclusion, these findings provide new evidence for understanding the mechanisms of atherosclerotic plaque formation, and provide a new and valuable research direction based on immune cell infiltration.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01259-z.

Diverse Epigenetic Regulations of Macrophages in Atherosclerosis

Emerging research on epigenetics has resulted in many novel discoveries in atherosclerosis (AS), an inflammaging-associated disease characterized by chronic inflammation primarily driven by macrophages. The bulk of evidence has demonstrated the central role of epigenetic machinery in macrophage polarization to pro- (M1-like) or anti-inflammatory (M2-like) phenotype. An increasing number of epigenetic alterations and their modifiers involved in reprogramming macrophages by regulating DNA methylation or histone modifications (e.g., methylation, acetylation, and recently lactylation) have been identified. They may act to determine or skew the direction of macrophage polarization in AS lesions, thereby representing a promising target. Here we describe the current understanding of the epigenetic machinery involving macrophage polarization, to shed light on chronic inflammation-driving onset and progression of inflammaging-associated diseases, using AS as a prototypic example, and discuss the challenge for developing effective therapies targeting the epigenetic modifiers against these diseases, particularly highlighting a potential strategy based on epigenetically-governed repolarization from M1-like to M2-like phenotype.

DNA Methylation Aberrant in Atherosclerosis

Atherosclerosis (AS) is a pathological process involving lipid oxidation, immune system activation, and endothelial dysfunction. The activated immune system could lead to inflammation and oxidative stress. Risk factors like aging and hyperhomocysteinemia also promote the progression of AS. Epigenetic modifications, including DNA methylation, histone modification, and non-coding RNA, are involved in the modulation of genes between the environment and AS formation. DNA methylation is one of the most important epigenetic mechanisms in the pathogenesis of AS. However, the relationship between the progression of AS and DNA methylation is not completely understood. This review will discuss the abnormal changes of DNA methylation in AS, including genome-wide hypermethylation dominating in AS with an increase of age, hypermethylation links with methyl supply and generating hyperhomocysteinemia, and the influence of oxidative stress with the demethylation process by interfering with the hydroxyl-methylation of TET proteins. The review will also summarize the current status of epigenetic treatment, which may provide new direction and potential therapeutic targets for AS.

Presence of periodontal pathogenic bacteria in blood of patients with coronary artery disease

It has been hypothesised that oral bacteria can migrate, through the blood, from the mouth to the arterial plaques, thus exacerbating atherosclerosis. This study compared bacteria present in the peripheral blood of individuals with and without coronary artery disease (CAD). RNA sequences obtained from blood were downloaded from GEO (GSE58150). Eight patients with coronary artery calcification (CAC) scoring > 500 and eight healthy individuals were analysed. After conducting quality control, the sequences were aligned to the hg38 reference genome using Hisat2. Bacterial taxa were analysed by inputting the unmapped sequences into Kraken. Ecological indices were calculated using Vegan. The package DESeq2 was used to compare the counts of bacteria per standard rank between groups. A total of 51 species were found only in patients with CAD and 41 were exclusively present in healthy individuals. The counts of one phylum, one class, three orders, two families and one genus were significantly different between the analysed groups (p < 0.00032, FDR < 10%), including the orders Cardiobacteriales, Corynebacteriales and Fusobacteriales. Twenty-three bacterial species belonging to the subgingival plaque bacterial complexes were also identified in the blood of individuals from both the groups; Fusobacterium nucleatum was significantly less frequent in patients with CAD (p = 0.0012, FDR = 4.8%). Furthermore, the frequency of another 11 bacteria differed significantly among patients with CAD than that among healthy individuals (p < 0.0030, FDR < 10%). These bacteria have not been previously reported in patients with atherosclerosis and periodontitis. The presence of members of the subgingival plaque bacterial complexes in the blood of patients with CAC supports the hypothesis that the periodontopathogens can be disseminated through the blood flow to other body parts where they may enhance inflammatory processes that can lead to the development or exacerbation of atherosclerosis.

Dysfunctional Vascular Endothelium as a Driver of Atherosclerosis: Emerging Insights Into Pathogenesis and Treatment

Atherosclerosis, the chronic accumulation of cholesterol-rich plaque within arteries, is associated with a broad spectrum of cardiovascular diseases including myocardial infarction, aortic aneurysm, peripheral vascular disease, and stroke. Atherosclerotic cardiovascular disease remains a leading cause of mortality in high-income countries and recent years have witnessed a notable increase in prevalence within low- and middle-income regions of the world. Considering this prominent and evolving global burden, there is a need to identify the cellular mechanisms that underlie the pathogenesis of atherosclerosis to discover novel therapeutic targets for preventing or mitigating its clinical sequelae. Despite decades of research, we still do not fully understand the complex cell-cell interactions that drive atherosclerosis, but new investigative approaches are rapidly shedding light on these essential mechanisms. The vascular endothelium resides at the interface of systemic circulation and the underlying vessel wall and plays an essential role in governing pathophysiological processes during atherogenesis. In this review, we present emerging evidence that implicates the activated endothelium as a driver of atherosclerosis by directing site-specificity of plaque formation and by promoting plaque development through intracellular processes, which regulate endothelial cell proliferation and turnover, metabolism, permeability, and plasticity. Moreover, we highlight novel mechanisms of intercellular communication by which endothelial cells modulate the activity of key vascular cell populations involved in atherogenesis, and discuss how endothelial cells contribute to resolution biology - a process that is dysregulated in advanced plaques. Finally, we describe important future directions for preclinical atherosclerosis research, including epigenetic and targeted therapies, to limit the progression of atherosclerosis in at-risk or affected patients.

Epigenome-Wide Histone Acetylation Changes in Peripheral Blood Mononuclear Cells in Patients with Type 2 Diabetes and Atherosclerotic Disease

There is emerging evidence of an association between epigenetic modifications, glycemic control and atherosclerosis risk. In this study, we mapped genome-wide epigenetic changes in patients with type 2 diabetes (T2D) and advanced atherosclerotic disease. We performed chromatin immunoprecipitation sequencing (ChIP-seq) using a histone 3 lysine 9 acetylation (H3K9ac) mark in peripheral blood mononuclear cells from patients with atherosclerosis with T2D (n = 8) or without T2D (ND, n = 10). We mapped epigenome changes and identified 23,394 and 13,133 peaks in ND and T2D individuals, respectively. Out of all the peaks, 753 domains near the transcription start site (TSS) were unique to T2D. We found that T2D in atherosclerosis leads to an H3K9ac increase in 118, and loss in 63 genomic regions. Furthermore, we discovered an association between the genomic locations of significant H3K9ac changes with genetic variants identified in previous T2D GWAS. The transcription factor 7-like 2 (TCF7L2) rs7903146, together with several human leukocyte antigen (HLA) variants, were among the domains with the most dramatic changes of H3K9ac enrichments. Pathway analysis revealed multiple activated pathways involved in immunity, including type 1 diabetes. Our results present novel evidence on the interaction between genetics and epigenetics, as well as epigenetic changes related to immunity in patients with T2D and advanced atherosclerotic disease.

Interference with lysophosphatidic acid receptor 5 ameliorates oxidized low-density lipoprotein-induced human umbilical vein endothelial cell injury by inactivating NOD-like receptor family, pyrin domain containing 3 inflammasome signaling

Endothelial cell damage induced by oxidized low-density lipoprotein (ox-LDL) plays an important role in the pathogenesis of atherosclerosis (AS). We aimed to explore the effects of lysophosphatidic acid receptor 5 (LPAR5) on ox-LDL-induced damage of human umbilical vein endothelial cells (HUVECs). After HUVECs exposed to ox-LDL, LPAR5 expression was detected by RT-qPCR and western blotting. Then, LPAR5 was silenced and cell viability was determined with a CCK-8 assay. ELISA was employed to analyze the contents of inflammatory factors. The levels of oxidative stress markers were examined by kits. The expression of proteins related to endothelium function, including CD31, α-SMA, iNOS and eNOS, was evaluated with RT-qPCR and western blotting. Additionally, the effects of LPAR5 deletion on the NLRP3 inflammasome signaling in HUVECs under ox-LDL condition were assessed by determining NLRP3, caspase-1 and ASC expression. Afterward, NLRP3 agonist MSU was adopted for exploring the regulation of LPAR5 on NLRP3 inflammasome signaling in ox-LDL HUVECs injury. Results revealed that ox-LDL led to a significant upregulation in LPAR5 expression. NLRP3 knockdown enhanced cell viability, inhibited inflammation and oxidative stress in HUVECs after ox-LDL exposure. Besides, the expression of CD31 and eNOS was increased while that of α-SMA and iNOS was decreased after LPAR5 silencing. Moreover, interference with LPAR5 remarkably downregulated NLRP3, caspase-1 and ASC expression. Furthermore, MSU addition partially abrogated the inhibitory effects of LPAR5 deletion on the inflammation, oxidative stress and endothelium dysfunction of HUVECs. To conclude, we demonstrated that LPAR5 silencing alleviates ox-LDL-induced HUVECs injury by inhibiting NLRP3 inflammasome signaling.

LncRNA SCIRT is downregulated in atherosclerosis and suppresses the proliferation of human aortic smooth muscle cells (HAOSMCs) by sponging miR-146a in cytoplasm

Background

SCIRT has been characterized as a key player in cancer biology, while its role in other human diseases is unclear. This study explored its role in atherosclerosis, with a specific focus on its interaction with SCIRT and miR-146a.

Methods

The expression of SCIRT and miR-146a in atherosclerosis-affected tissues and healthy tissues from 56 atherosclerosis patients were analyzed by RT-qPCR. The expression of SCIRT in nuclear and cytoplasm samples was detected by RNA fractionation assay. The direct interaction between SCIRT and miR-146a was detected by RNA pull-down assay. SCIRT and miR-146a were overexpressed in human aortic smooth muscle cells (HAOSMCs) to study the crosstalk between them. The role of SCIRT and miR-146a in the proliferation of HAOSMCs was analyzed with BrdU assay.

Results

SCIRT was downregulated by atherosclerosis, while miR-146a was upregulated by atherosclerosis. SCIRT was detected in both cytoplasm and nuclear samples, and it directly interacted with miR-146a. In HAOSMCs, overexpression of SCIRT and miR-146a did not affect the expression of each other. Interestingly, SCIRT suppressed the proliferation of HAOSMCs and reduced the enhancing effects of miR-146a on cell proliferation.

Conclusion

Therefore, SCIRT is downregulated in atherosclerosis and it suppresses the proliferation of HAOSMCs by sponging miR-146a in cytoplasm.

The proliferation and migration of atherosclerosis-related HVSMCs were inhibited by downregulation of lncRNA XIST via regulation of the miR-761/BMP9 axis

Atherosclerosis (AS) is a chronic inflammatory disease that can be caused by the proliferation and migration of human vascular smooth muscle cells (HVSMCs). Here, we found that lncRNA XIST was related to the abnormal proliferation and migration of HVSMCs, and thus, the mechanism by which XIST regulated HVSMCs was further investigated. HVSMCs were treated with oxidized low-density lipoprotein (ox-LDL, 100 μg/ml) as AS models. CCK8 assays, flow cytometry, Transwell assays and wound healing assays were applied to evaluate cell viability, cell cycle analysis, and cell migration, respectively. A dual-luciferase reporter assay was employed to verify the binding relationships between XIST and miR-761, miR-761, and BMP9. Ox-LDL induced the proliferation and migration of HVSMCs, upregulated the expression of XIST, downregulated miR-761 expression, and activated the BMP9/ALK1/endoglin pathway. Luciferase assays revealed that XIST sponged miR-761. XIST knockdown ameliorated ox-LDL-mediated effects in HVSMCs, which were largely abolished by miR-761 silencing. BMP9 was targeted-inhibited by miR-761. MiR-761 overexpression alleviated ox-LDL-mediated effects in HVSMCs. However, BMP9 overexpression abolished miR-761-mediated effects in HVSMCs treated with ox-LDL. Our findings suggested that XIST knockdown suppressed the proliferation and migration of HVSMCs by promoting miR-761, which targeted-inhibited the BMP9/ALK1/endoglin pathway.

Knockdown of lnc-KCNC3-3:1 Alleviates the Development of Atherosclerosis via Downregulation of JAK1/STAT3 Signaling Pathway

Background: Atherosclerosis is a major cause of coronary artery disease (CAD), and CAD is one of the main causes leading to death in most countries. It has been reported that lncRNAs play important roles in the development of atherosclerosis; thus, we aimed to explore lncRNAs that are closely related to the occurrence and development of atherosclerosis.

Methods: The data GSE113079 from the GEO database was used to explore the dysregulated lncRNAs in peripheral blood mononuclear cells (PBMCs) between 93 patients with CAD and 48 healthy controls. Next, RT-qPCR was performed to detect the level of lncRNAs in HUVEC cells and CCK-8 was performed to detect cell viability. Then, flow cytometry assays were used to determine the apoptosis of HUVEC. In addition, ELISA assay was used to measure the concentrations of triglyceride (TG), low density lipoprotein cholesterin (LDL-C), and high density lipoprotein cholesterol (HDL-C). Moreover, western blot assay was used to detect the expression of proteins.

Results: lnc-KCNC3-3:1 was significantly upregulated in PBMCs of patients with CAD. In addition, oxidized low density lipoprotein (oxLDL) notably inhibited the proliferation and induced the apoptosis of HUVEC, while this phenomenon was notably reversed by lnc-KCNC3-3:1 knockdown. Moreover, oxLDL significantly promoted the migration of HUVECs, which was significantly restored by knockdown of lnc-KCNC3-3:1. Moreover, lnc-KCNC3-3:1 siRNA1 could reverse oxLDL-induced HUVEC growth inhibition, and lnc-KCNC3-3:1 silencing could inhibit the expressions of p-JAK1 and p-STAT3 in oxLDL-treated HUVECs. Animal study revealed that knockdown of lnc-KCNC3-3:1 alleviated the symptom of atherosclerosis, and it could inhibit the expressions of p-JAK1, p-STAT3 and p-Akt in tissues of atherosclerosis mice.

Conclusion: Knockdown of lnc-KCNC3-3:1 alleviates the development of atherosclerosis via downregulation of JAK1/STAT3 signaling pathway. These data indicated that lnc-KCNC3-3:1 might serve as a potential target for the treatment of atherosclerosis.

A circular RNA, circUSP36, accelerates endothelial cell dysfunction in atherosclerosis by adsorbing miR-637 to enhance WNT4 expression

Atherosclerosis is a fatal disorder that is fundamental to various cardiovascular diseases and severely threatens people’s health worldwide. Several studies have demonstrated the role of circular RNAs (circRNAs) in the pathogenesis of atherosclerosis. circUSP36 acts as a key modulator in the progression of atherosclerosis, but the molecular mechanism underlying this role is as yet unclear. This study aimed to elucidate the mechanism by which circUSP36 exerts its function in an in vitro cell model of endothelial cell dysfunction, which is one of pathological features of atherosclerosis. The circRNA traits of circUSP36 were confirmed, and we observed high expression of circUSP36 in endothelial cells exposed to oxidized low-density lipoprotein (ox-LDL). Functional assays revealed that overexpression of circUSP36 suppressed proliferation and migration of ox-LDL-treated endothelial cells. In terms of its mechanism, circUSP36 adsorbed miR-637 by acting as an miRNA sponge. Moreover, enhanced expression of miR-637 abated the impact of circUSP36 on ox-LDL-treated endothelial cell dysregulation. Subsequently, the targeting relationship between miR-637 and WNT4 was predicted using bioinformatics tools and was confirmed via luciferase reporter and RNA pull-down assays. Notably, depletion of WNT4 rescued circUSP36-mediated inhibition of endothelial cell proliferation and migration. In conclusion, circUSP36 regulated WNT4 to aggravate endothelial cell injury caused by ox-LDL by competitively binding to miR-637; this finding indicates circUSP36 to be a promising biomarker for the diagnosis and therapy of atherosclerosis.

DNA Methylation Profile of the SREBF2 Gene in Human Fetal Aortas

Increasing evidence suggests that maternal cholesterol represents an important risk factor for atherosclerotic disease in offspring already during pregnancy, although the underlying mechanisms have not yet been elucidated. Eighteen human fetal aorta samples were collected from the spontaneously aborted fetuses of normal cholesterolemic and hypercholesterolemic mothers. Maternal total cholesterol levels were assessed during hospitalization. DNA methylation profiling of the whole SREBF2 gene CpG island was performed (p value <0.05). The Mann-Whitney U test was used for comparison between the 2 groups. For the first time, our study revealed that in fetal aortas obtained from hypercholesterolemic mothers, the SREBF2 gene shows 4 significant differentially hypermethylated sites in the 5'UTR-CpG island. This finding indicates that more effective long-term primary cardiovascular prevention programs need to be designed for the offspring of mothers with hypercholesterolemia. Further studies should be conducted to clarify the epigenetic mechanisms underlying the association between early atherogenesis and maternal hypercholesterolemia during pregnancy.

Targeting epigenetic modifiers to reprogramme macrophages in non-resolving inflammation-driven atherosclerosis

Epigenomic and epigenetic research has been providing several new insights into a variety of diseases caused by non-resolving inflammation, including cardiovascular diseases. Atherosclerosis (AS) has long been recognized as a chronic inflammatory disease of the arterial walls, characterized by local persistent and stepwise accelerating inflammation without resolution, also known as uncontrolled inflammation. The pathogenesis of AS is driven primarily by highly plastic macrophages via their polarization to pro- or anti-inflammatory phenotypes as well as other novel subtypes recently identified by single-cell sequencing. Although emerging evidence has indicated the key role of the epigenetic machinery in the regulation of macrophage plasticity, the investigation of epigenetic alterations and modifiers in AS and related inflammation is still in its infancy. An increasing number of the epigenetic modifiers (e.g. TET2, DNMT3A, HDAC3, HDAC9, JMJD3, KDM4A) have been identified in epigenetic remodelling of macrophages through DNA methylation or histone modifications (e.g. methylation, acetylation, and recently lactylation) in inflammation. These or many unexplored modifiers function to determine or switch the direction of macrophage polarization via transcriptional reprogramming of gene expression and intracellular metabolic rewiring upon microenvironmental cues, thereby representing a promising target for anti-inflammatory therapy in AS. Here, we review up-to-date findings involving the epigenetic regulation of macrophages to shed light on the mechanism of uncontrolled inflammation during AS onset and progression. We also discuss current challenges for developing an effective and safe anti-AS therapy that targets the epigenetic modifiers and propose a potential anti-inflammatory strategy that repolarizes macrophages from pro- to anti-inflammatory phenotypes.

Emerging Single-Cell Technological Approaches to Investigate Chromatin Dynamics and Centromere Regulation in Human Health and Disease

Epigenetic regulators play a crucial role in establishing and maintaining gene expression states. To date, the main efforts to study cellular heterogeneity have focused on elucidating the variable nature of the chromatin landscape. Specific chromatin organisation is fundamental for normal organogenesis and developmental homeostasis and can be affected by different environmental factors. The latter can lead to detrimental alterations in gene transcription, as well as pathological conditions such as cancer. Epigenetic marks regulate the transcriptional output of cells. Centromeres are chromosome structures that are epigenetically regulated and are crucial for accurate segregation. The advent of single-cell epigenetic profiling has provided finer analytical resolution, exposing the intrinsic peculiarities of different cells within an apparently homogenous population. In this review, we discuss recent advances in methodologies applied to epigenetics, such as CUT&RUN and CUT&TAG. Then, we compare standard and emerging single-cell techniques and their relevance for investigating human diseases. Finally, we describe emerging methodologies that investigate centromeric chromatin specification and neocentromere formation.

LncRNA SNHG12 regulates ox-LDL-induced endothelial cell injury by the miR-218-5p/IGF2 axis in atherosclerosis

Atherosclerosis (AS) is a cardiovascular disorder accompanied by endothelial dysfunction. Extensive evidence demonstrates the regulatory functions of long noncoding RNAs (lncRNAs) in cardiovascular disease, including AS. Here, the function of lncRNA small nucleolar RNA host gene 12 (SNHG12) in AS progression was investigated. A cell model of AS was established in human umbilical endothelial cells (HUVECs) using oxidative low-density lipoprotein (ox-LDL). CCK-8, flow cytometry, TUNEL, ELISA, and western blotting analyses were performed. Apolipoprotein E-deficient (apoE-/-) mice fed a Western diet were used as in vivo models of AS. RT-qPCR determined the levels of SNHG12, microRNA-218-5p (miR-218-5p) and insulin-like growth factor-II (IGF2). The molecular mechanisms were investigated using luciferase reporter and RNA pull-down assays. We found that SNHG12 and IGF2 expression levels were high and miR-218-5p expression levels were low in AS patients and ox-LDL-treated HUVECs. SNHG12 depletion attenuated ox-LDL-induced injury in HUVECs, whereas miR-218-5p suppression partially abated this effect. Moreover, IGF2 overexpression prevented the alleviative role of miR-218-5p in ox-LDL-treated HUVECs. SNHG12 upregulated IGF2 expression by sponging miR-218-5p. More importantly, SNHG12 increased proinflammatory cytokine production and augmented atherosclerotic lesions in vivo. Overall, SNHG12 promotes the development of AS by the miR-218-5p/IGF2 axis.

Osteopontin in Cardiovascular Diseases

Unprecedented advances in secondary prevention have greatly improved the prognosis of cardiovascular diseases (CVDs); however, CVDs remain a leading cause of death globally. These findings suggest the need to reconsider cardiovascular risk and optimal medical therapy. Numerous studies have shown that inflammation, pro-thrombotic factors, and gene mutations are focused not only on cardiovascular residual risk but also as the next therapeutic target for CVDs. Furthermore, recent clinical trials, such as the Canakinumab Anti-inflammatory Thrombosis Outcomes Study trial, showed the possibility of anti-inflammatory therapy for patients with CVDs. Osteopontin (OPN) is a matricellular protein that mediates diverse biological functions and is involved in a number of pathological states in CVDs. OPN has a two-faced phenotype that is dependent on the pathological state. Acute increases in OPN have protective roles, including wound healing, neovascularization, and amelioration of vascular calcification. By contrast, chronic increases in OPN predict poor prognosis of a major adverse cardiovascular event independent of conventional cardiovascular risk factors. Thus, OPN can be a therapeutic target for CVDs but is not clinically available. In this review, we discuss the role of OPN in the development of CVDs and its potential as a therapeutic target.

Deficiency of histone lysine methyltransferase SETDB2 in hematopoietic cells promotes vascular inflammation and accelerates atherosclerosis

Epigenetic modifications of the genome, including DNA methylation, histone methylation/acetylation, and noncoding RNAs, have been reported to play a fundamental role in regulating immune response during the progression of atherosclerosis. SETDB2 is a member of the KMT1 family of lysine methyltransferases, and members of this family typically methylate histone H3 Lys9 (H3K9), an epigenetic mark associated with gene silencing. Previous studies have shown that SETDB2 is involved in innate and adaptive immunity, the proinflammatory response, and hepatic lipid metabolism. Here, we report that expression of SETDB2 is markedly upregulated in human and murine atherosclerotic lesions. Upregulation of SETDB2 was observed in proinflammatory M1 but not antiinflammatory M2 macrophages. Notably, we found that genetic deletion of SETDB2 in hematopoietic cells promoted vascular inflammation and enhanced the progression of atherosclerosis in BM transfer studies in Ldlr-knockout mice. Single-cell RNA-Seq analysis in isolated CD45⁺ cells from atherosclerotic plaques from mice transplanted with SETDB2-deficient BM revealed a significant increase in monocyte population and enhanced expression of genes involved in inflammation and myeloid cell recruitment. Additionally, we found that loss of SETDB2 in hematopoietic cells was associated with macrophage accumulation in atherosclerotic lesions and attenuated efferocytosis. Overall, these studies identify SETDB2 as an important inflammatory cell regulator that controls macrophage activation in atherosclerotic plaques.

Pharmacological inhibition of EZH2 by GSK126 decreases atherosclerosis by modulating foam cell formation and monocyte adhesion in apolipoprotein E-deficient mice

Histone modifications play an important role in the occurrence and development of atherosclerosis in human and atherosclerosis-prone mice. Histone methylation in macrophages, monocytes and endothelial cells markedly influence the progression of atherosclerosis. However, it remains unclear whether treatment with a histone methyltransferase enhancer of zeste homolog 2 (EZH2) inhibitor may suppress atherosclerosis. The present study aimed to determine the effects of the EZH2 inhibitor, GSK126, on the suppression and regression of atherosclerosis in apolipoprotein E-deficient mouse models. In vitro, it was found that pharmacological inhibition of EZH2 by GSK126 markedly reduced lipid transportation and monocyte adhesion during atherogenesis, predominantly through increasing the expression levels of ATP-binding cassette transporter A1 and suppressing vascular cell adhesion molecule 1 in human THP-1 cells. In vivo, it was found that atherosclerotic plaques in GSK126-treated mice were significantly decreased when comparing with the vehicle-treated animals. These results indicated that the GSK126 has the ability to attenuate the progression of atherosclerosis by reducing macrophage foam cell formation and monocyte adhesion in cell and mouse models. In conclusion, the present study provided new insights into the molecular mechanism behind the action of GSK126 and suggested its therapeutic potential for the treatment of atherosclerosis.

Cell-specific epigenetic changes in atherosclerosis

Atherosclerosis is a disease of large and medium arteries that can lead to life-threatening cerebrovascular and cardiovascular consequences such as heart failure and stroke and is a major contributor to cardiovascular-related mortality worldwide. Atherosclerosis development is a complex process that involves specific structural, functional and transcriptional changes in different vascular cell populations at different stages of the disease. The application of single-cell RNA sequencing (scRNA-seq) analysis has discovered not only disease-related cell-specific transcriptomic profiles but also novel subpopulations of cells once thought as homogenous cell populations. Vascular cells undergo specific transcriptional changes during the entire course of the disease. Epigenetics is the instruction-set-architecture in living cells that defines and maintains the cellular identity by regulating the cellular transcriptome. Although different cells contain the same genetic material, they have different epigenomic signatures. The epigenome is plastic, dynamic and highly responsive to environmental stimuli. Modifications to the epigenome are driven by an array of epigenetic enzymes generally referred to as writers, erasers and readers that define cellular fate and destiny. The reversibility of these modifications raises hope for finding novel therapeutic targets for modifiable pathological conditions including atherosclerosis where the involvement of epigenetics is increasingly appreciated. This article provides a critical review of the up-to-date research in the field of epigenetics mainly focusing on in vivo settings in the context of the cellular role of individual vascular cell types in the development of atherosclerosis.