Fat mass and obesity-associated protein attenuates lipid accumulation in macrophage foam cells and alleviates atherosclerosis in apolipoprotein E-deficient mice

Epigenetic regulation of diverse regulated cell death modalities in cardiovascular disease: Insights into necroptosis, pyroptosis, ferroptosis, and cuproptosis

Cell death constitutes a critical component of the pathophysiology of cardiovascular diseases. A growing array of non-apoptotic forms of regulated cell death (RCD)-such as necroptosis, ferroptosis, pyroptosis, and cuproptosis-has been identified and is intimately linked to various cardiovascular conditions. These forms of RCD are governed by genetically programmed mechanisms within the cell, with epigenetic modifications being a common and crucial regulatory method. Such modifications include DNA methylation, RNA methylation, histone methylation, histone acetylation, and non-coding RNAs. This review recaps the roles of DNA methylation, RNA methylation, histone modifications, and non-coding RNAs in cardiovascular diseases, as well as the mechanisms by which epigenetic modifications regulate key proteins involved in cell death. Furthermore, we systematically catalog the existing epigenetic pharmacological agents targeting novel forms of RCD and their mechanisms of action in cardiovascular diseases. This article aims to underscore the pivotal role of epigenetic modifications in precisely regulating specific pathways of novel RCD in cardiovascular diseases, thus offering potential new therapeutic avenues that may prove more effective and safer than traditional treatments.

Insights into the m6A demethylases FTO and ALKBH5 : structural, biological function, and inhibitor development

N6-methyladenosine (m6A) is dynamically regulated by methyltransferases (termed "writers") and demethylases (referred to as "erasers"), facilitating a reversible modulation. Changes in m6A levels significantly influence cellular functions, such as RNA export from the nucleus, mRNA metabolism, protein synthesis, and RNA splicing. They are intricately associated with a spectrum of pathologies. Moreover, dysregulation of m6A modulation has emerged as a promising therapeutic target across many diseases. m6A plays a pivotal role in controlling vital downstream molecules and critical biological pathways, contributing to the pathogenesis and evolution of numerous conditions. This review provides an overview of m6A demethylases, explicitly detailing the structural and functional characteristics of FTO and ALKBH5. Additionally, we explore their distinct involvement in various diseases, examine factors regulating their expression, and discuss the progress in inhibitor development.

Comprehensive review on lipid metabolism and RNA methylation: Biological mechanisms, perspectives and challenges

Adipose tissue plays a crucial role in maintaining energy balance, regulating hormones, and promoting metabolic health. To address disorders related to obesity and develop effective therapies, it is essential to have a deep understanding of adipose tissue biology. In recent years, RNA methylation has emerged as a significant epigenetic modification involved in various cellular functions and metabolic pathways. Particularly in the realm of adipogenesis and lipid metabolism, extensive research is ongoing to uncover the mechanisms and functional importance of RNA methylation. Increasing evidence suggests that RNA methylation plays a regulatory role in adipocyte development, metabolism, and lipid utilization across different organs. This comprehensive review aims to provide an overview of common RNA methylation modifications, their occurrences, and regulatory mechanisms, focusing specifically on their intricate connections to fat metabolism. Additionally, we discuss the research methodologies used in studying RNA methylation and highlight relevant databases that can aid researchers in this rapidly advancing field.

RNA modifications in cellular metabolism: implications for metabolism-targeted therapy and immunotherapy

Cellular metabolism is an intricate network satisfying bioenergetic and biosynthesis requirements of cells. Relevant studies have been constantly making inroads in our understanding of pathophysiology, and inspiring development of therapeutics. As a crucial component of epigenetics at post-transcription level, RNA modification significantly determines RNA fates, further affecting various biological processes and cellular phenotypes. To be noted, immunometabolism defines the metabolic alterations occur on immune cells in different stages and immunological contexts. In this review, we characterize the distribution features, modifying mechanisms and biological functions of 8 RNA modifications, including N6-methyladenosine (m6A), N6,2'-O-dimethyladenosine (m6Am), N1-methyladenosine (m1A), 5-methylcytosine (m5C), N4-acetylcytosine (ac4C), N7-methylguanosine (m7G), Pseudouridine (Ψ), adenosine-to-inosine (A-to-I) editing, which are relatively the most studied types. Then regulatory roles of these RNA modification on metabolism in diverse health and disease contexts are comprehensively described, categorized as glucose, lipid, amino acid, and mitochondrial metabolism. And we highlight the regulation of RNA modifications on immunometabolism, further influencing immune responses. Above all, we provide a thorough discussion about clinical implications of RNA modification in metabolism-targeted therapy and immunotherapy, progression of RNA modification-targeted agents, and its potential in RNA-targeted therapeutics. Eventually, we give legitimate perspectives for future researches in this field from methodological requirements, mechanistic insights, to therapeutic applications.

Transcriptome-wide N6-methyladenosine methylation profile of atherosclerosis in mice

BACKGROUND

Atherosclerosis (AS) is a critical pathological event during the progression of cardiovascular diseases. It exhibits fibrofatty lesions on the arterial wall and lacks effective treatment. N6-methyladenosine (m6A) is the most common modification of eukaryotic RNA and plays an important role in regulating the development and progression of cardiovascular diseases. However, the role of m6A modification in AS remains largely unknown. Therefore, in this study, we explored the transcriptome distribution of m6A modification in AS and its potential mechanism.

METHODS

Methylation Quantification Kit was used to detect the global m6A levels in the aorta of AS mice. Western blot was used to analyze the protein level of methyltransferases. Methylated RNA immunoprecipitation with next-generation sequencing (MeRIP-seq) and RNA sequencing (RNA-seq) were used to obtain the first transcriptome range analysis of the m6A methylene map in the aorta of AS mice, followed by bioinformatics analysis. qRT-PCR and MeRIP-qRT-PCR were used to measure the mRNA and m6A levels in target genes.

RESULTS

The global m6A and protein levels of methyltransferase METTL3 were significantly increased in the aorta of AS mice. However, the protein level of demethylase ALKBH5 was significantly decreased. Through MeRIP-seq, we obtained m6A methylation maps in AS and control mice. In total, 26,918 m6A peaks associated with 13,744 genes were detected in AS group, whereas 26,157 m6A peaks associated with 13,283 genes were detected in the control group. Peaks mainly appeared in the coding sequence (CDS) regions close to the stop codon with the RRACH motif. Moreover, functional enrichment analysis demonstrated that m6A-containing genes were significantly enriched in AS-relevant pathways. Interestingly, a negative correlation between m6A methylation abundance and gene expression level was found through the integrated analysis of MeRIP-seq and RNA-seq data. Among the m6A-modified genes, a hypo-methylated but up-regulated (hypo-up) gene Fabp5 may be a potential biomarker of AS.

CONCLUSIONS

Our study provides transcriptome-wide m6A methylation for the first time to determine the association between m6A modification and AS progression. Our study lays a foundation for further exploring the pathogenesis of AS and provides a new direction for the treatment of AS.

Identification and validation of hub genes involved in foam cell formation and atherosclerosis development via bioinformatics

Background

Foam cells play crucial roles in all phases of atherosclerosis. However, until now, the specific mechanisms by which these foam cells contribute to atherosclerosis remain unclear. We aimed to identify novel foam cell biomarkers and interventional targets for atherosclerosis, characterizing their potential mechanisms in the progression of atherosclerosis.

Methods

Microarray data of atherosclerosis and foam cells were downloaded from the Gene Expression Omnibus (GEO) database. Differentially expression genes (DEGs) were screened using the "LIMMA" package in R software. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis and Gene Ontology (GO) annotation were both carried out. Hub genes were found in Cytoscape after a protein-protein interaction (PPI) enrichment analysis was carried out. Validation of important genes in the GSE41571 dataset, cellular assays, and tissue samples.

Results

A total of 407 DEGs in atherosclerosis and 219 DEGs in foam cells were identified, and the DEGs in atherosclerosis were mainly involved in cell proliferation and differentiation. CSF1R and PLAUR were identified as common hub genes and validated in GSE41571. In addition, we also found that the expression of CSF1R and PLAUR gradually increased with the accumulation of lipids and disease progression in cell and tissue experiments.

Conclusion

CSF1R and PLAUR are key hub genes of foam cells and may play an important role in the biological process of atherosclerosis. These results advance our understanding of the mechanism behind atherosclerosis and potential therapeutic targets for future development.

Emerging Role and Mechanism of the FTO Gene in Cardiovascular Diseases

The fat mass and obesity-associated (FTO) gene was the first obesity-susceptibility gene identified through a genome-wide association study (GWAS). A growing number of studies have suggested that genetic variants of FTO are strongly associated with the risk of cardiovascular diseases, including hypertension and acute coronary syndrome. In addition, FTO was also the first N⁶-methyladenosine (m6A) demethylase, suggesting the reversible nature of m6A modification. m6A is dynamically deposited, removed, and recognized by m6A methylases, demethylases, and m6A binding proteins, respectively. By catalyzing m6A demethylation on mRNA, FTO may participate in various biological processes by modulating RNA function. Recent studies demonstrated that FTO plays a pivotal role in the initiation and progression of cardiovascular diseases such as myocardial fibrosis, heart failure, and atherosclerosis and may hold promise as a potential therapeutic target for treating or preventing a variety of cardiovascular diseases. Here, we review the association between FTO genetic variants and cardiovascular disease risk, summarize the role of FTO as an m6A demethylase in cardiovascular disorders, and discuss future research directions and possible clinical implications.

Identification of potential diagnostic biomarkers of atherosclerosis based on bioinformatics strategy

BACKGROUND

Atherosclerosis is the main pathological change in atherosclerotic cardiovascular disease, and its underlying mechanisms are not well understood. The aim of this study was to explore the hub genes involved in atherosclerosis and their potential mechanisms through bioinformatics analysis.

METHODS

Three microarray datasets from Gene Expression Omnibus (GEO) identified robust differentially expressed genes (DEGs) by robust rank aggregation (RRA). We performed connectivity map (CMap) analysis and functional enrichment analysis on robust DEGs and constructed a protein‒protein interaction (PPI) network using the STRING database to identify the hub gene using 12 algorithms of cytoHubba in Cytoscape. Receiver operating characteristic (ROC) analysis was used to assess the diagnostic potency of the hub genes.The CIBERSORT algorithm was used to perform immunocyte infiltration analysis and explore the association between the identified biomarkers and infiltrating immunocytes using Spearman's rank correlation analysis in R software. Finally, we evaluated the expression of the hub gene in foam cells.

RESULTS

A total of 155 robust DEGs were screened by RRA and were revealed to be mainly associated with cytokines and chemokines by functional enrichment analysis. CD52 and IL1RN were identified as hub genes and were validated in the GSE40231 dataset. Immunocyte infiltration analysis showed that CD52 was positively correlated with gamma delta T cells, M1 macrophages and CD4 memory resting T cells, while IL1RN was positively correlated with monocytes and activated mast cells. RT-qPCR results indicate that CD52 and IL1RN were highly expressed in foam cells, in agreement with bioinformatics analysis.

CONCLUSIONS

​This study has established that CD52 and IL1RN may play a key role in the occurrence and development of atherosclerosis, which opens new lines of thought for further research on the pathogenesis of atherosclerosis.

Associations of genetic markers of diabetes mellitus with carotid atherosclerosis: a community-based case-control study

BACKGROUND

Diabetes mellitus (DM) is a well-established determinant of atherosclerosis and cardiovascular diseases (CVD). Recently, genome-wide association studies (GWAS) identified several single nucleotide polymorphism (SNP) significantly correlated with DM. The study aimed to explore the relationships of the top significant DM SNPs with carotid atherosclerosis (CA).

METHODS

We used a case-control design and randomly selected 309 cases and 439 controls with and without, respectively, carotid plaque (CP) from a community-based cohort. Eight recent GWAS on DM in East Asians reported hundreds of SNPs with genome-wide significance. The study used the top significant DM SNPs, with a p-value < 10^-16, as the candidate genetic markers of CA. The independent effects of these DM SNPs on CA were assessed by multivariable logistic regression analyses to control the effects of conventional cardio-metabolic risk factors.

RESULTS

Multivariable analyses showed that, 9 SNPs, including rs4712524, rs1150777, rs10842993, rs2858980, rs9583907, rs1077476, rs7180016, rs4383154, and rs9937354, showed promising associations with the presence of carotid plaque (CP). Among them, rs9937354, rs10842993, rs7180016, and rs4383154 showed significantly independent effects. The means (SD) of the 9-locus genetic risk score (9-GRS) of CP-positive and -negative subjects were 9.19 (1.53) and 8.62 (1.63), respectively (p < 0.001). The corresponding values of 4-locus GRS (4-GRS) were 4.02 (0.81) and. 3.78 (0.92), respectively (p < 0.001). The multivariable-adjusted odds ratio of having CP for per 1.0 increase in 9-GRS and 4-GRS were 1.30 (95% CI 1.18-1.44; p = 4.7 × 10^-7) and 1.47 (95% CI 1.74-9.40; p = 6.1 × 10^-5), respectively. The means of multi-locus GRSs of DM patients were similar to those of CP-positive subjects and higher than those of CP-negative or DM-negative subjects.

CONCLUSIONS

We identified 9 DM SNPs showing promising associations with CP. The multi-locus GRSs may be used as biomarkers for the identification and prediction of high-risks subjects for atherosclerosis and atherosclerotic diseases. Future studies on these specific SNPs and their associated genes may provide valuable information for the preventions of DM and atherosclerosis.

N6-methyladenosine in macrophage function: a novel target for metabolic diseases

N6-methyladenosine (m⁶A) is one of the most prevalent internal transcriptional modifications. Evidence has highlighted changes in m⁶A in metabolic disorders and various metabolic diseases. However, the precise mechanisms of these m⁶A changes in such conditions are not understood. Macrophages are crucial for the innate immune system and exert either beneficial or harmful roles in metabolic disease. Notably, m⁶A was found to be closely related to macrophage phenotype and dysfunction. In this review, we summarize m⁶A in macrophage function from the perspective of macrophage development, activation, and polarization, pyroptosis, and metabolic disorders. Furthermore, we discuss how m⁶A-mediated macrophage function affects metabolic diseases, including atherosclerosis and nonalcoholic fatty liver disease (NAFLD). Finally, we discuss challenges and prospects for m⁶A in macrophage and metabolic diseases with the aim of providing guidance for the treatment of metabolic diseases.

Epigenetic Regulation of Macrophage Polarization in Cardiovascular Diseases

Cardiovascular diseases (CVDs) are the leading cause of hospitalization and death worldwide, especially in developing countries. The increased prevalence rate and mortality due to CVDs, despite the development of several approaches for prevention and treatment, are alarming trends in global health. Chronic inflammation and macrophage infiltration are key regulators of the initiation and progression of CVDs. Recent data suggest that epigenetic modifications, such as DNA methylation, posttranslational histone modifications, and RNA modifications, regulate cell development, DNA damage repair, apoptosis, immunity, calcium signaling, and aging in cardiomyocytes; and are involved in macrophage polarization and contribute significantly to cardiac disease development. Cardiac macrophages not only trigger damaging inflammatory responses during atherosclerotic plaque formation, myocardial injury, and heart failure but are also involved in tissue repair, remodeling, and regeneration. In this review, we summarize the key epigenetic modifications that influence macrophage polarization and contribute to the pathophysiology of CVDs, and highlight their potential for the development of advanced epigenetic therapies.

RNA methylation in vascular disease: a systematic review

Despite the rise in morbidity and mortality associated with vascular diseases, the underlying pathophysiological molecular mechanisms are still unclear. RNA N6-methyladenosine modification, as the most common cellular mechanism of RNA regulation, participates in a variety of biological functions and plays an important role in epigenetics. A large amount of evidence shows that RNA N6-methyladenosine modifications play a key role in the morbidity caused by vascular diseases. Further research on the relationship between RNA N6-methyladenosine modifications and vascular diseases is necessary to understand disease mechanisms at the gene level and to provide new tools for diagnosis and treatment. In this study, we summarize the currently available data on RNA N6-methyladenosine modifications in vascular diseases, addressing four aspects: the cellular regulatory system of N6-methyladenosine methylation, N6-methyladenosine modifications in risk factors for vascular disease, N6-methyladenosine modifications in vascular diseases, and techniques for the detection of N6-methyladenosine-methylated RNA.

The Mechanism and Role of N6-Methyladenosine (m6A) Modification in Atherosclerosis and Atherosclerotic Diseases

N6-methyladenosine (m6A) modification is a newly discovered regulatory mechanism in eukaryotes. As one of the most common epigenetic mechanisms, m6A's role in the development of atherosclerosis (AS) and atherosclerotic diseases (AD) has also received increasing attention. Herein, we elucidate the effect of m6A on major risk factors for AS, including lipid metabolism disorders, hypertension, and hyperglycemia. We also describe how m6A methylation contributes to endothelial cell injury, macrophage response, inflammation, and smooth muscle cell response in AS and AD. Subsequently, we illustrate the m6A-mediated aberrant biological role in the pathogenesis of AS and AD, and analyze the levels of m6A methylation in peripheral blood or local tissues of AS and AD, which helps to further discuss the diagnostic and therapeutic potential of m6A regulation for AS and AD. In summary, studies on m6A methylation provide new insights into the pathophysiologic mechanisms of AS and AD, and m6A methylation could be a novel diagnostic biomarker and therapeutic target for AS and AD.

The Role of N6-Methyladenosine Modification in Microvascular Dysfunction

Microvascular dysfunction (MVD) has long plagued the medical field despite improvements in its prevention, diagnosis, and intervention. Microvascular lesions from MVD increase with age and further lead to impaired microcirculation, target organ dysfunction, and a mass of microvascular complications, thus contributing to a heavy medical burden and rising disability rates. An up-to-date understanding of molecular mechanisms underlying MVD will facilitate discoveries of more effective therapeutic strategies. Recent advances in epigenetics have revealed that RNA methylation, an epigenetic modification, has a pivotal role in vascular events. The N⁶-methylation of adenosine (m⁶A) modification is the most prevalent internal RNA modification in eukaryotic cells, which regulates vascular transcripts through splicing, degradation, translation, as well as translocation, thus maintaining microvascular homeostasis. Conversely, the disruption of the m⁶A regulatory network will lead to MVD. Herein, we provide a review discussing how m⁶A methylation interacts with MVD. We also focus on alterations of the m⁶A regulatory network under pathological conditions. Finally, we highlight the value of m⁶A regulators as prognostic biomarkers and novel therapeutic targets, which might be a promising addition to clinical medicine.

Emerging roles of the RNA modifications N6-methyladenosine and adenosine-to-inosine in cardiovascular diseases

Cardiovascular diseases lead the mortality and morbidity disease metrics worldwide. A multitude of chemical base modifications in ribonucleic acids (RNAs) have been linked with key events of cardiovascular diseases and metabolic disorders. Named either RNA epigenetics or epitranscriptomics, the post-transcriptional RNA modifications, their regulatory pathways, components, and downstream effects substantially contribute to the ways our genetic code is interpreted. Here we review the accumulated discoveries to date regarding the roles of the two most common epitranscriptomic modifications, N6-methyl-adenosine (m6A) and adenosine-to-inosine (A-to-I) editing, in cardiovascular disease.

Correlation of acetyl-coenzyme A carboxylase 1 with Th17 and Th1 cells, serving as a potential prognostic biomarker for acute ischemic stroke patients

Background

Acetyl‐coenzyme A carboxylase 1 (ACC1) regulates lipid homeostasis, T helper (Th) cell differentiation, oxidative stress, inflammation response, and neurological process, engaging in acute ischemic stroke (AIS) pathogenesis, while its clinical utility in AIS is unclear. Hence, this study intended to explore the correlation among blood ACC1, Th17, and Th1 cells, and ACC1’s potency as a prognostic biomarker for AIS management.

Methods

ACC1 in peripheral blood mononuclear cells (PBMCs) of 160 AIS patients and 30 controls were determined using RT‐qPCR; blood Th17 and Th1 cells in AIS patients were quantified by flow cytometry.

Results

ACC1 was increased in AIS patients compared with controls (median (interquartile range): 2.540 (1.753–3.548) vs. 0.980 (0.655–1.743), p < 0.001), which exhibited a good value to reflect AIS risk with the area under the curve of 0.872 (95% CI: 0.805–0.939). Moreover, ACC1 was positively linked with Th17 (r = 0.374, p < 0.001) and Th1 (r = 0.178, p = 0.024) cells in AIS patients. Additionally, ACC1 (r = 0.328, p < 0.001), Th17 (r = 0.272, p = 0.001), and Th1 cells (r = 0.195, p = 0.014) were positively associated with the National Institutes of Health Stroke Scale score in AIS patients. ACC1 high vs. low (p = 0.038) and Th17 high vs. low (p = 0.026) were related to shortened recurrence‐free survival (RFS) in AIS patients, while Th1 cells (p = 0.179) were not correlated with RFS. Whereas ACC1 (p = 0.248), Th17 (p = 0.079), and Th1 cells (p = 0.130) were not linked with overall survival (OS) in AIS patients.

Conclusion

Circulating ACC1 overexpression correlates with increased Th17, Th1 cells, NIHSS score, and shortened RFS in AIS patients.

m6A Methylation in Cardiovascular Diseases: From Mechanisms to Therapeutic Potential

Cardiovascular disease (CVD) is a leading cause of morbidity and mortality worldwide. Recent studies have shown that n6-methyladenosine (m6A) plays a major role in cardiovascular homeostasis and pathophysiology. These studies have confirmed that m6A methylation affects the pathophysiology of cardiovascular diseases by regulating cellular processes such as differentiation, proliferation, inflammation, autophagy, and apoptosis. Moreover, plenty of research has confirmed that m6A modification can delay the progression of CVD via the post-transcriptional regulation of RNA. However, there are few available summaries of m6A modification regarding CVD. In this review, we highlight advances in CVD-specific research concerning m6A modification, summarize the mechanisms underlying the involvement of m6A modification during the development of CVD, and discuss the potential of m6A modification as a therapeutic target of CVD.

N6-Methyladenosine Demethylase FTO (Fat Mass and Obesity-Associated Protein) as a Novel Mediator of Statin Effects in Human Endothelial Cells

BACKGROUND

N6-methyladenosine (m6A) plays a critical role in various biological processes. However, no study has addressed the role of m6A modification in the statin-induced protection of endothelial cells (ECs).

METHODS

Quantitative real-time polymerase chain reaction and Western blotting analyses were used to study the expression of m6A regulatory genes in atorvastatin-treated ECs. Gain- and loss-of-function assays, methylated RNA immunoprecipitation analysis, and dual-luciferase reporter assays were performed to clarify the function of FTO (fat mass and obesity-associated protein) in ECs.

RESULTS

Atorvastatin decreased FTO protein expression in ECs. The knockdown of FTO enhanced the mRNA and protein expression of KLF2 (Kruppel-like factor 2) and eNOS (endothelial NO synthase) but attenuated TNFα (tumor necrosis factor alpha)-induced VCAM-1 (vascular cell adhesion molecule 1) and ICAM-1 (intercellular adhesion molecule 1) expression, as well as the adhesion of monocytes to ECs. Conversely, FTO overexpression significantly upregulated the mRNA and protein levels of VCAM-1 and ICAM-1, downregulated those of KLF2 and eNOS, and strongly attenuated the atorvastatin-mediated induction of KLF2 and eNOS expression. Subsequent investigations demonstrated that KLF2 and eNOS are functionally critical targets of FTO. Mechanistically, FTO interacted with KLF2 and eNOS transcripts and regulated their expression in an m6A-dependent manner. After FTO silencing, KLF2 and eNOS transcripts with higher levels of m6A modification in their 3' untranslated regions were captured by YTHDF3 (YT521-B homology m6A RNA-binding protein 3), resulting in mRNA stabilization and the induction of KLF2 and eNOS protein expression.

CONCLUSIONS

FTO might serve as a novel molecular target to modulate endothelial function in vascular diseases.

Darling: A Web Application for Detecting Disease-Related Biomedical Entity Associations with Literature Mining

Finding, exploring and filtering frequent sentence-based associations between a disease and a biomedical entity, co-mentioned in disease-related PubMed literature, is a challenge, as the volume of publications increases. Darling is a web application, which utilizes Name Entity Recognition to identify human-related biomedical terms in PubMed articles, mentioned in OMIM, DisGeNET and Human Phenotype Ontology (HPO) disease records, and generates an interactive biomedical entity association network. Nodes in this network represent genes, proteins, chemicals, functions, tissues, diseases, environments and phenotypes. Users can search by identifiers, terms/entities or free text and explore the relevant abstracts in an annotated format.

Epitranscriptome in Ischemic Cardiovascular Disease: Potential Target for Therapies

The global risk of cardiovascular disease, including ischemic disease such as stroke, remains high, and cardiovascular disease is the cause of one-third of all deaths worldwide. The main subjacent cause, atherosclerosis, is not fully understood. To improve early diagnosis and therapeutic strategies, it is crucial to unveil the key molecular mechanisms that lead to atherosclerosis development. The field of epitranscriptomics is blossoming and quickly advancing in fields like cancer research, nevertheless, poorly understood in the context of cardiovascular disease. Epitranscriptomic modifications are shown to regulate the metabolism and function of RNA molecules, which are important for cell functions such as cell proliferation, a key aspect in atherogenesis. As such, epitranscriptomic regulatory mechanisms can serve as novel checkpoints in gene expression during disease development. In this review, we describe examples of the latest research investigating epitranscriptomic modifications, in particular A-to-I editing and the covalent modification N⁶-methyladenosine and their regulatory proteins, in the context of cardiovascular disease. We additionally discuss the potential of these mechanisms as therapeutic targets and novel treatment options.

Critical roles of FTO-mediated mRNA m6A demethylation in regulating adipogenesis and lipid metabolism: Implications in lipid metabolic disorders

The goal this review is to clarify the effects of the fat mass and obesity-associated protein (FTO) in lipid metabolism regulation and related underlying mechanisms through the FTO-mediated demethylation of m⁶A modification. FTO catalyzes the demethylation of m⁶A to alter the processing, maturation and translation of the mRNAs of lipid-related genes. FTO overexpression in the liver promotes lipogenesis and lipid droplet (LD) enlargement and suppresses CPT-1–mediated fatty acid oxidation via the SREBP1c pathway, promoting excessive lipid storage and nonalcoholic fatty liver diseases (NAFLD). FTO enhances preadipocyte differentiation through the C/EBPβ pathway, and facilitates adipogenesis and fat deposition by altering the alternative splicing of RUNX1T1, the expression of PPARγ and ANGPTL4, and the phosphorylation of PLIN1, whereas it inhibits lipolysis by inhibiting IRX3 expression and the leptin pathway, causing the occurrence and development of obesity. Suppression of the PPARβ/δ and AMPK pathways by FTO-mediated m⁶A demethylation damages lipid utilization in skeletal muscles, leading to the occurrence of diabetic hyperlipidemia. m⁶A demethylation by FTO inhibits macrophage lipid influx by downregulating PPARγ protein expression and accelerates cholesterol efflux by phosphorylating AMPK, thereby impeding foam cell formation and atherosclerosis development. In summary, FTO-mediated m⁶A demethylation modulates the expression of lipid-related genes to regulate lipid metabolism and lipid disorder diseases.

Identification of potential therapeutic targets for atherosclerosis by analysing the gene signature related to different immune cells and immune regulators in atheromatous plaques

BACKGROUND

Atherosclerosis is a chronic inflammatory disease that affects multiple arteries. Numerous studies have shown the inherent immune diversity in atheromatous plaques and suggest that the dysfunction of different immune cells plays an important role in atherosclerosis. However, few comprehensive bioinformatics analyses have investigated the potential coordinators that might orchestrate different immune cells to exacerbate atherosclerosis.

METHODS

Immune infiltration of 69 atheromatous plaques from different arterial beds in GSE100927 were explored by single-sample-gene-set enrichment analysis (presented as ssGSEA scores), ESTIMATE algorithm (presented as immune scores) and CIBERSORT algorithm (presented as relative fractions of 22 types of immune cells) to divide these plaques into ImmuneScoreL cluster (of low immune infiltration) and ImmuneScoreH cluster (of high immune infiltration). Subsequently, comprehensive bioinformatics analyses including differentially-expressed-genes (DEGs) analysis, protein-protein interaction networks analysis, hub genes analysis, Gene-Ontology-terms and KEGG pathway enrichment analysis, gene set enrichment analysis, analysis of expression profiles of immune-related genes, correlation analysis between DEGs and hub genes and immune cells were conducted. GSE28829 was analysed to cross-validate the results in GSE100927.

RESULTS

Immune-related pathways, including interferon-related pathways and PD-1 signalling, were highly enriched in the ImmuneScoreH cluster. HLA-related (except for HLA-DRB6) and immune checkpoint genes (IDO1, PDCD-1, CD274(PD-L1), CD47), RORC, IFNGR1, STAT1 and JAK2 were upregulated in the ImmuneScoreH cluster, whereas FTO, CRY1, RORB, and PER1 were downregulated. Atheromatous plaques in the ImmuneScoreH cluster had higher proportions of M0 macrophages and gamma delta T cells but lower proportions of plasma cells and monocytes (p < 0.05). CAPG, CECR1, IL18, IGSF6, FBP1, HLA-DPA1 and MMP7 were commonly related to these immune cells. In addition, the advanced-stage carotid plaques in GSE28829 exhibited higher immune infiltration than early-stage carotid plaques.

CONCLUSIONS

Atheromatous plaques with higher immune scores were likely at a more clinically advanced stage. The progression of atherosclerosis might be related to CAPG, IGSF6, IL18, CECR1, FBP1, MMP7, FTO, CRY1, RORB, RORC, PER1, HLA-DPA1 and immune-related pathways (IFN-γ pathway and PD-1 signalling pathway). These genes and pathways might play important roles in regulating immune cells such as M0 macrophages, gamma delta T cells, plasma cells and monocytes and might serve as potential therapeutic targets for atherosclerosis.

Potential regulatory role of epigenetic RNA methylation in cardiovascular diseases

Cardiovascular diseases (CVDs) are the leading cause of morbidity and mortality worldwide, especially in developing countries. To date, several approaches have been proposed for the prevention and treatment of CVDs. However, the increased risk of developing cardiovascular events that result in hospitalization has become a growing public health concern. The pathogenesis of CVDs has been analyzed from various perspectives. Recent data suggest that regulatory RNAs play a multidimensional role in the development of CVDs. Studies have identified several mRNA modifications that have contributed to the functional characterization of various cardiac diseases. RNA methylation, such as N6-methyladenosine, N1-methyladenosine, 5-methylcytosine, N7-methylguanosine, N4-acetylcytidine, and 2'-O-methylation are novel epigenetic modifications that affect the regulation of cell growth, immunity, DNA damage, calcium signaling, apoptosis, and aging in cardiomyocytes. In this review, we summarize the role of RNA methylation in the pathophysiology of CVDs and the potential of using epigenetics to treat such disorders.

RNA Modification by m6A Methylation in Cardiovascular Disease

Cardiovascular disease is currently the leading cause of death worldwide, and its underlying regulatory mechanisms remain largely unknown. N⁶-Methyladenosine (m⁶A) RNA methylation is an epigenetic modification involved in the splicing, nuclear export, translational regulation, and degradation of RNA. After the initial identification of m⁶A RNA methylation in 1974, the rise of next-generation sequencing technology to detect m⁶A throughout the transcriptome led to its renewed recognition in 2012. Since that time, m⁶A methylation has been extensively studied, and its functions, mechanisms, and effectors (e.g., METTL3, FTO, METTL14, WTAP, ALKBH5, and YTHDFs) in various diseases, including cardiovascular diseases, have rapidly been investigated. In this review, we first examine and summarize the molecular and cellular functions of m⁶A methylation and its readers, writers, and erasers in the cardiovascular system. Finally, we discuss future directions for m⁶A methylation research and the potential for therapeutic targeting of m⁶A modification in cardiovascular disease.

Therapeutic potential of ALKB homologs for cardiovascular disease

Cardiovascular diseases (CVDs) are the leading causes of human death. Recently, ALKB homologs, including ALKBH1-8 and FTO, have been found to have a variety of biological functions, such as histone demethylation, RNA demethylation, and DNA demethylation. These functions may regulate the physiological and pathological processes of CVDs, including inflammation, oxidative stress, cell apoptosis, and mitochondrial, endothelial, and fat metabolism dysfunction. In the present review, we summarize the biological functions of ALKB homologs and the relationship between the ALKB homologs and CVDs. Importantly, we discuss the roles of ALKB homologs in the regulation of oxidative stress, inflammation, autophagy, and DNA damage in CVDs, as well as the practical applications of ALKB homologs inhibitors or agonists in treating CVDs. In conclusion, the ALKBH family might be a promising target for CVDs therapy.

The critical roles of m6A modification in metabolic abnormality and cardiovascular diseases

N6-methyladenosine (m6A) RNA methylation is an emerging area of epigenetics, which is a reversible and dynamic modification mediating by ‘writers’ (methylase, adding methyl groups, METTL3, METTL14, and WTAP), ‘erasers’ (demethylase, deleting methyl groups, FTO and ALKBH5), and ‘readers’ (YTHDF1-3, YTHDC1 and YTHDC2). Recent studies in human, animal models and cell levels have disclosed a critical role of m6A modification in regulating the homeostasis of metabolic processes and cardiovascular function. Evidence from these studies identify m6A as a candidate of biomarker and therapeutic target for metabolic abnormality and cardiovascular diseases (CVD). Comprehensive understanding of the complexity of m6A regulation in metabolic diseases and CVD will be helpful for us to understand the pathogenesis of CVD. In this review, we discuss the regulatory role of m6A in metabolic abnormality and CVD. We will emphasize the clinical relevance of m6A dysregulation in CVD.

N6-methyladenosine demethylase FTO promotes M1 and M2 macrophage activation

Macrophage polarization is the driving force of various inflammatory diseases, especially those involved in M1/M2 imbalance. N6-methyladenosine (m⁶A) is the most prevalent internal mRNA modification in eukaryotes that affects multiple biological processes, including those involved developmental arrest and immune response. However, the role of m⁶A in macrophage polarization remains unclear. This study found that FTO silencing significantly suppressed both M1 and M2 polarization. FTO depletion decreased the phosphorylation levels of IKKα/β, IκBα and p65 in the NF-κB signaling pathway. The expression of STAT1 was downregulated in M1-polarized macrophages while the expression of STAT6 and PPAR-γ decreased in M2 polarization after FTO knockdown. The actinomycin D experiments showed that FTO knockdown accelerated mRNA decay of STAT1 and PPAR-γ. Furthermore, the stability and expression of STAT1 and PPAR-γ mRNAs increased when the m⁶A reader YTHDF2 was silenced. In conclusion, our results suggest that FTO knockdown inhibits the NF-κB signaling pathway and reduces the mRNA stability of STAT1 and PPAR-γ via YTHDF2 involvement, thereby impeding macrophage activation. These findings indicated a previously unrecognized link between FTO and macrophage polarization and might open new avenues for research into the molecular mechanisms of macrophage polarization-related diseases.

AMP-activated protein kinase: the current landscape for drug development

Since the discovery of AMP-activated protein kinase (AMPK) as a central regulator of energy homeostasis, many exciting insights into its structure, regulation and physiological roles have been revealed. While exercise, caloric restriction, metformin and many natural products increase AMPK activity and exert a multitude of health benefits, developing direct activators of AMPK to elicit beneficial effects has been challenging. However, in recent years, direct AMPK activators have been identified and tested in preclinical models, and a small number have entered clinical trials. Despite these advances, which disease(s) represent the best indications for therapeutic AMPK activation and the long-term safety of such approaches remain to be established.

Identification of biomarkers in macrophages of atherosclerosis by microarray analysis

BACKGROUND

Atherosclerotic cardiovascular disease (ASCVD) refers to a series of diseases caused by atherosclerosis (AS). It is one of the most important causes of death worldwide. According to the inflammatory response theory, macrophages play a critical role in AS. However, the potential targets associated with macrophages in the development of AS are still obscure. This study aimed to use bioinformatics tools for screening and identifying molecular targets in AS macrophages.

METHODS

Two expression profiling datasets (GSE7074 and GSE9874) were obtained from the Gene Expression Omnibus dataset, and differentially expressed genes (DEGs) between non-AS macrophages and AS macrophages were identified. Functional annotation of the DEGs was performed by analyzing the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes databases. STRING and Cytoscape were employed for constructing a protein-protein interaction network and analyzing hub genes.

RESULTS

A total of 98 DEGs were distinguished between non-AS macrophages and AS macrophages. The functional variations in DEGs were mainly enriched in response to hypoxia, respiratory gaseous exchange, protein binding, and intracellular, ciliary tip, early endosome membrane, and Lys63-specific deubiquitinase activities. Three genes were identified as hub genes, including KDELR3, CD55, and DYNC2H1.

CONCLUSION

Hub genes and DEGs identified by using microarray techniques can be used as diagnostic and therapeutic biomarkers for AS.

An Obesity Paradox: Increased Body Mass Index Is Associated with Decreased Aortic Atherosclerosis

Brodsky et al. (Cardiovasc Pathol 25(6), 515-520, 2016) recently have reported that there was an unexpected and highly significant inverse correlation between body mass index (BMI) and atherosclerosis of the aortas of morbidly obese decedents (BMI >40 kg/m²). In a series of 304 decedents, 65 of whom were morbidly obese, minimal or no atherosclerosis was seen in 46 of them (70%) versus 20 (30%) who had severe atherosclerosis (P = 0.008). This obesity paradox was unexpected and raises important questions about the etiology and pathogenesis of atherosclerosis, which will be the subject of this commentary. The concept of healthy versus unhealthy adiposity may in part provide an explanation for the "obesity paradox." Another factor that will be considered is the possible role of adipokines and their genetic determinants that may significantly reduce the risk of developing aortic atherosclerosis in morbidly obese individuals. Considering the marked variability in the pattern and extent of atherosclerosis of the aorta, hemodynamic factors and endothelial cell shear stress may be the most important determinants that might explain the obesity paradox that we have observed. Finally, the possible role of gut microbiota and inflammation as factors in the etiopathogenesis of atherosclerosis will be considered, but their importance is less clear than that of hemodynamic factors. We conclude with the remarkable finding that a 5300-year-old, well-preserved mummy of the "Iceman," Ötzi had atherosclerotic disease of a number of major arteries and the interesting questions that this raises.