Epigenetic Mechanisms and Hypertension

Hypertension in an ageing population: Diagnosis, mechanisms, collateral health risks, treatments, and clinical challenges

Ageing population is considerably increasing worldwide, which is considered to reflect an improved quality of life. However, longevity in the human lifespan has increased the burden of late-life illnesses including cancer, neurodegeneration, and cardiovascular dysfunction. Of these, hypertension is the most common condition with huge health risks, with an increased prevalence among the elderly. In this review, we outline the current guidelines for defining hypertension and examine the detailed mechanisms underlying the relationship between hypertension and ageing-related outcomes, including sodium sensitivity, arterial stiffness, endothelial dysfunction, isolated systolic hypertension, white coat effect, and orthostatic hypertension. As hypertension-related collateral health risk increases among the elderly, the available management strategies are necessary to overcome the clinical treatment challenges faced among elderly population. To improve longevity and reduce adverse health effects, potential approaches producing crucial information into new era of medicine should be considered in the prevention and treatment of hypertension among elderly population. This review provides an overview of mechanisms underlying hypertension and its related collateral health risk in elderly population, along with multiple approaches and management strategies to improve the clinical challenges among elderly population.

Lactylation Modification in Cardiometabolic Disorders: Function and Mechanism

Cardiovascular disease (CVD) is recognized as the primary cause of mortality and morbidity on a global scale, and developing a clear treatment is an important tool for improving it. Cardiometabolic disorder (CMD) is a syndrome resulting from the combination of cardiovascular, endocrine, pro-thrombotic, and inflammatory health hazards. Due to their complex pathological mechanisms, there is a lack of effective diagnostic and treatment methods for cardiac metabolic disorders. Lactylation is a type of post-translational modification (PTM) that plays a regulatory role in various cellular physiological processes by inducing changes in the spatial conformation of proteins. Numerous studies have reported that lactylation modification plays a crucial role in post-translational modifications and is closely related to cardiac metabolic diseases. This article discusses the molecular biology of lactylation modifications and outlines the roles and mechanisms of lactylation modifications in cardiometabolic disorders, offering valuable insights for the diagnosis and treatment of such conditions.

DNA Methylation Mediated the Association of Body Mass Index With Blood Pressure in Chinese Monozygotic Twins

Obesity is an established risk factor for hypertension, but the mechanisms are only partially understood. We examined whether body mass index (BMI)-related DNA methylation (DNAm) variation would mediate the association of BMI with blood pressure (BP). We first conducted a genomewide DNA methylation analysis in monozygotic twin pairs to detect BMI-related DNAm variation and then evaluated the mediating effect of DNAm on the relationship between BMI and BP levels using the causal inference test (CIT) method and mediation analysis. Ontology enrichment analysis was performed for CpGs using the GREAT tool. A total of 60 twin pairs for BMI and systolic blood pressure (SBP) and 58 twin pairs for BMI and diastolic blood pressure (DBP) were included. BMI was positively associated with SBP (β = 1.86, p = .0004). The association between BMI and DNAm of 85 CpGs reached p < 1×10-4 level. Eleven BMI-related differentially methylated regions (DMRs) within LNCPRESS1, OGDHL, RNU1-44P, NPHS1, ECEL1P2, LLGL2, RNY4P15, MOGAT3, PHACTR3, and BAI2 were found. Of the 85 CpGs, 9 mapped to C10orf71-AS1, NDUFB5P1, KRT80, BAI2, ABCA2, PEX11G and FGF4 were significantly associated with SBP levels. Of the 9 CpGs, 2 within ABCA2 negatively mediated the association between BMI and SBP, with a mediating effect of -0.24 (95% CI [-0.65, -0.01]). BMI was also positively associated with DBP (β = 0.60, p = .0495). The association between BMI and DNAm of 193 CpGs reached p < 1×10-4 level. Twenty-five BMI-related DMRs within OGDHL, POU4F2, ECEL1P2, TTC6, SMPD4, EP400, TUBA1C and AGAP2 were found. Of the 193 CpGs, 33 mapped to ABCA2, ADORA2B, CTNNBIP1, KDM4B, NAA60, RSPH6A, SLC25A19 and STIL were significantly associated with DBP levels. Of the 33 CpGs, 12 within ABCA2, SLC25A19, KDM4B, PTPRN2, DNASE1, TFCP2L1, LMNB2 and C10orf71-AS1 negatively mediated the association between BMI and DBP, with a total mediation effect of -0.66 (95% CI [-1.07, -0.30]). Interestingly, BMI might also negatively mediate the association between the DNAm of most CpG mediators mentioned above and BP. The mediating effect of DNAm was also found when stratified by sex. In conclusion, DNAm variation may partially negatively mediate the association of BMI with BP. Our findings may provide new clues to further elucidate the pathogenesis of obesity to hypertension and identify new diagnostic biomarkers and therapeutic targets for hypertension.

Histone Modifications and Their Contributions to Hypertension

Essential hypertension, a multifaceted disorder, is a worldwide health problem. A complex network of genetic, epigenetic, physiological, and environmental components regulates blood pressure (BP), and any dysregulation of this network may result in hypertension. Growing evidence suggests a role for epigenetic factors in BP regulation. Any alterations in the expression or functions of these epigenetic regulators may dysregulate various determinants of BP, thereby promoting the development of hypertension. Histone posttranslational modifications are critical epigenetic regulators that have been implicated in hypertension. Several studies have demonstrated a clear association between the increased expression of some histone-modifying enzymes, especially HDACs (histone deacetylases), and hypertension. In addition, treatment with HDAC inhibitors lowers BP in hypertensive animal models, providing an excellent opportunity to design new drugs to treat hypertension. In this review, we discuss the potential contribution of different histone modifications to the regulation of BP.

The underlying mechanisms of DNA methylation in high salt memory in hypertensive vascular disease

This study demonstrates the effect and DNA methylation-related mechanisms of a high-salt diet and salt memory-induced hypertension and vasculopathy. Thirty Sprague Dawley rats were randomly divided into a control (CON) group (n = 6) and a modeling group (n = 24). A 12% NaCl solution (1 mL/100 g) was intragastrically administered for 60 consecutive days for modeling. An increase in blood pressure up to 140 mmHg was considered successful modeling. Twelve of fifteen successfully modeled rats were randomly selected and divided into a High Salt Diet (HSD) group and a High Salt Memory (HSM) group (n = 6). Rats in HSD group were intragastrically administered a 12% NaCl solution, while rats in HSM group were administered a 3% NaCl solution twice a day for 30 days. At the end of the intervention, blood pressure and the serum levels of ET-1, NO, TNF-α and IL-1β were measured. RRBS-heavy sulfite sequencing technology was selected for DNA methylation analysis. The systolic blood pressure of rats in the HSD group and HSM group was significantly higher than that in the CON group. Compared with those in the CON group, the serum levels of ET-1 in the HSM group and the serum levels of NO in the HSD group and HSM group were significantly increased. The methylation level of the CON group was lower than that of the HSD group and the HSM group, and there was no significant difference between the HSD group and the HSM group. The methylation level of Myoz3 was downregulated in the HSD group and HSM group. The methylation level of Fgd3 were upregulated in HSD group and downregulated in the HSM group. The methylation levels of AC095693.1, Adamts3, PDGFA and PDGFRα were downregulated in the HSD group and upregulated in the HSM group. According to the GO database, the differentially methylated genes were significantly enriched in the coordination of cell function, genetic development, and RNA transcription. There were three main metabolic pathways that were enriched in the differentially expressed genes between the groups: the PI3K-Akt signaling pathway, MAPK signaling pathway, and Hippo signaling pathway. Excessive salt intake may cause hypertension and vascular damage, and this damage may continue after the reduction of salt intake. Therefore, salt memory phenomenon exists, and this memory effect may be correlated with the levels of DNA methylation.

Traditional Therapeutics and Potential Epidrugs for CVD: Why Not Both?

Cardiovascular disease (CVD) is the leading cause of death worldwide. In addition to the high mortality rate, people suffering from CVD often endure difficulties with physical activities and productivity that significantly affect their quality of life. The high prevalence of debilitating risk factors such as obesity, type 2 diabetes mellitus, smoking, hypertension, and hyperlipidemia only predicts a bleak future. Current traditional CVD interventions offer temporary respite; however, they compound the severe economic strain of health-related expenditures. Furthermore, these therapeutics can be prescribed indefinitely. Recent advances in the field of epigenetics have generated new treatment options by confronting CVD at an epigenetic level. This involves modulating gene expression by altering the organization of our genome rather than altering the DNA sequence itself. Epigenetic changes are heritable, reversible, and influenced by environmental factors such as medications. As CVD is physiologically and pathologically diverse in nature, epigenetic interventions can offer a ray of hope to replace or be combined with traditional therapeutics to provide the prospect of addressing more than just the symptoms of CVD. This review discusses various risk factors contributing to CVD, perspectives of current traditional medications in practice, and a focus on potential epigenetic therapeutics to be used as alternatives.

The role of genetics in maternal susceptibility to preeclampsia in women of African ancestry

Racial disparities exist in the prevalence of preeclampsia (PE), with women of African ancestry suffering the highest rates of morbidity and mortality. Genetic changes may play a role in the preponderance of PE among women of African ancestry. This review discusses 30 genes with variants that have been studied in PE in women of African ancestry. These studies found that a single gene is not responsible for PE susceptibility as 13 genes have been implicated. These genes subserve endothelial, immune, hemodynamic, homeostatic, thrombophilic, oxidative stress, and lipid metabolic pathways. Notably, maternal-fetal gene interactions also contribute to the susceptibility of the disease. For instance, the maternal KIR AA genotype and paternally inherited fetal HLA-C2 genotype confer risk for developing PE. Additionally, genetic changes such as epigenetic modulation of expression of the MTHFR gene through DNA methylation is also associated with the occurrence of PE. In contrast, some genes such as the KIR B centromeric region protect against development of PE in some women. The soluble fms-like tyrosine kinase 1 (sFlt-1) contributes to the development of PE and is a potential novel therapeutic option for targeted gene silencing of anti-angiogenic sFLT-1 gene. Additionally, NOS3 gene is an important target for pharmacogenomics because it is responsible for the production of endothelial nitric oxide. In conclusion, maternal genetic and epigenetic variants confer susceptibility to PE, indicating the need for further studies to develop a screening tool incorporating maternal genetic variants to identify women at high risk for PE and offer them a preventive therapy.

Exploring the pathogenesis and treatment of IgA nephropathy based on epigenetics

IgA nephropathy is the most common primary glomerulonephritis worldwide. However, its exact cause remains unclear, with known genetic factors explaining only 11% of the variation. Recently, researchers have turned their attention to epigenetic abnormalities in immune-related diseases, recognizing their significance in IgA nephropathy's development and progression. This emerging field has revolutionized our understanding of epigenetics in IgA nephropathy research. Though in its early stages, studying IgA nephropathy's epigenetics holds promise for unraveling its pathogenesis and identifying new biomarkers and therapies. This review aims to comprehensively analyze epigenetics' role in IgA nephropathy's development and suggest avenues for potential therapeutic interventions. In the future, assessing and modulating epigenetics may become integral in diagnosing, tailoring treatments and assessing prognoses for IgA nephropathy.

Molecular and Epigenetic Control of Aldosterone Synthase, CYP11B2 and 11-Hydroxylase, CYP11B1

Aldosterone and cortisol serve important roles in the pathogenesis of cardiovascular diseases and metabolic disorders. Epigenetics is a mechanism to control enzyme expression by genes without changing the gene sequence. Steroid hormone synthase gene expression is regulated by transcription factors specific to each gene, and methylation has been reported to be involved in steroid hormone production and disease. Angiotensin II or potassium regulates the aldosterone synthase gene, CYP11B2. The adrenocorticotropic hormone controls the 11b-hydroxylase, CYP11B1. DNA methylation negatively controls the CYP11B2 and CYP11B1 expression and dynamically changes the expression responsive to continuous stimulation of the promoter gene. Hypomethylation status of the CYP11B2 promoter region is seen in aldosterone-producing adenomas. Methylation of recognition sites of transcription factors, including cyclic AMP responsive element binding protein 1 or nerve growth factor-induced clone B, diminish their DNA-binding activity. A methyl-CpG-binding protein 2 cooperates directly with the methylated CpG dinucleotides of CYP11B2. A low-salt diet, treatment with angiotensin II, and potassium increase the CYP11B2 mRNA levels and induce DNA hypomethylation in the adrenal gland. A close association between a low DNA methylation ratio and an increased CYP11B1 expression is seen in Cushing's adenoma and aldosterone-producing adenoma with autonomous cortisol secretion. Epigenetic control of CYP11B2 or CYP11B1 plays an important role in autonomic aldosterone or cortisol synthesis.

Epigenome-wide association study in Chinese monozygotic twins identifies DNA methylation loci associated with blood pressure

BACKGROUND

Hypertension is a crucial risk factor for developing cardiovascular disease and reducing life expectancy. We aimed to detect DNA methylation (DNAm) variants potentially related to systolic blood pressure (SBP) and diastolic blood pressure (DBP) by conducting epigenome-wide association studies in 60 and 59 Chinese monozygotic twin pairs, respectively.

METHODS

Genome-wide DNA methylation profiling in whole blood of twins was performed using Reduced Representation Bisulfite Sequencing, yielding 551,447 raw CpGs. Association between DNAm of single CpG and blood pressure was tested by applying generalized estimation equation. Differentially methylated regions (DMRs) were identified by comb-P approach. Inference about Causation through Examination of Familial Confounding was utilized to perform the causal inference. Ontology enrichment analysis was performed using Genomic Regions Enrichment of Annotations Tool. Candidate CpGs were quantified using Sequenom MassARRAY platform in a community population. Weighted gene co-expression network analysis (WGCNA) was conducted using gene expression data.

RESULTS

The median age of twins was 52 years (95% range 40, 66). For SBP, 31 top CpGs (p < 1 × 10^-4) and 8 DMRs were identified, with several DMRs within NFATC1, CADM2, IRX1, COL5A1, and LRAT. For DBP, 43 top CpGs (p < 1 × 10^-4) and 12 DMRs were identified, with several DMRs within WNT3A, CNOT10, and DAB2IP. Important pathways, such as Notch signaling pathway, p53 pathway by glucose deprivation, and Wnt signaling pathway, were significantly enriched for SBP and DBP. Causal inference analysis suggested that DNAm at top CpGs within NDE1, MYH11, SRRM1P2, and SMPD4 influenced SBP, while SBP influenced DNAm at CpGs within TNK2. DNAm at top CpGs within WNT3A influenced DBP, while DBP influenced DNAm at CpGs within GNA14. Three CpGs mapped to WNT3A and one CpG mapped to COL5A1 were validated in a community population, with a hypermethylated and hypomethylated direction in hypertension cases, respectively. Gene expression analysis by WGCNA further identified some common genes and enrichment terms.

CONCLUSION

We detect many DNAm variants that may be associated with blood pressure in whole blood, particularly the loci within WNT3A and COL5A1. Our findings provide new clues to the epigenetic modification underlying hypertension pathogenesis.

Toward Precision Medicine: Circadian Rhythm of Blood Pressure and Chronotherapy for Hypertension - 2021 NHLBI Workshop Report

Healthy individuals exhibit blood pressure variation over a 24-hour period with higher blood pressure during wakefulness and lower blood pressure during sleep. Loss or disruption of the blood pressure circadian rhythm has been linked to adverse health outcomes, for example, cardiovascular disease, dementia, and chronic kidney disease. However, the current diagnostic and therapeutic approaches lack sufficient attention to the circadian rhythmicity of blood pressure. Sleep patterns, hormone release, eating habits, digestion, body temperature, renal and cardiovascular function, and other important host functions as well as gut microbiota exhibit circadian rhythms, and influence circadian rhythms of blood pressure. Potential benefits of nonpharmacologic interventions such as meal timing, and pharmacologic chronotherapeutic interventions, such as the bedtime administration of antihypertensive medications, have recently been suggested in some studies. However, the mechanisms underlying circadian rhythm-mediated blood pressure regulation and the efficacy of chronotherapy in hypertension remain unclear. This review summarizes the results of the National Heart, Lung, and Blood Institute workshop convened on October 27 to 29, 2021 to assess knowledge gaps and research opportunities in the study of circadian rhythm of blood pressure and chronotherapy for hypertension.

Epigenetic modifications and fetal programming: Molecular mechanisms to control hypertension inheritance

Cardiovascular diseases (CVD) are the number 1 cause of death in the United States and hypertension is a highly prevalent risk factor for CVD. It is estimated that up to 50 % of the hypertensive trait is genetically inherited while the other 50 % is determined by modifiable factors involving lifestyle, behaviors, and the environment. Interestingly, the hypertensive trait is induced or inhibited by epigenetic modifications modulated by modifiable factors. This review focused on the underlying mechanisms of stress, sleep deprivation, obesity and sedentarism as key players for epigenetic modifications contributing to the development of the hypertensive trait and, on the other hand, how epigenetic modifications induced by physical exercise and healthier habits may contribute to overturn and prevent the inheritance of hypertension trait. Furthermore, adversities during gestation and perinatal life also increase the risk for hypertension and CVD later in life, which can perpetuate the inheritance of the hypertensive trait whereas healthier habits during gestation and lactation may counteract fetal programming to improve the cardiovascular health of the progeny. Therefore, it is promising that a healthier lifestyle causes long-lasting epigenetic modifications and is transmitted to the next generation, strengthening the fight against the inheritance of hypertension.

MicroRNA-195a-5p Regulates Blood Pressure by Inhibiting NKCC2A

BACKGROUND

Previous studies showed that miR-195a-5p was among the most abundant microRNAs (miRNAs) expressed in the kidney.

METHODS

Lentivirus silencing of tumor necrosis factor-α (TNF) was performed in vivo and in vitro. Luciferase reporter assays confirmed that bumetanide-sensitive Na+-K+-2Cl- cotransporter isoform A (NKCC2A) mRNA is targeted and repressed by miR-195a-5p. Radiotelemetry was used to measure mean arterial pressure.

RESULTS

TNF upregulates mmu-miR-195a-5p, and -203 and downregulates mmu-miR-30c and -100 in the medullary thick ascending limb of male mice. miR-195a-5p was >3-fold higher in the renal outer medulla of mice given an intrarenal injection of murine recombinant TNF, whereas silencing TNF inhibited miR-195a-5p expression by ≈51%. Transient transfection of a miR-195a-5p mimic into medullary thick ascending limb cells suppressed NKCC2A mRNA by ≈83%, whereas transfection with Anti-miR-195a-5p increased NKCC2A mRNA. Silencing TNF in medullary thick ascending limb cells prevented increases in miR-195 induced by 400 mosmol/kg H2O medium, an effect reversed by transfection with a miR-195a-5p mimic. Expression of phosphorylated NKCC2 increased 1.5-fold in medullary thick ascending limb cells transfected with Anti-miR-195a-5p and a miR-195a-5p mimic prevented the increase, which was induced by silencing TNF in cells exposed to 400 mosmol/kg H2O medium after osmolality was increased by adding NaCl. Intrarenal injection of TNF suppressed NKCC2A mRNA, whereas injection of miR-195a-5p prevented the increase of NKCC2A mRNA abundance and phosphorylated NKCC2 expression when TNF was silenced. Intrarenal injection with miR-195a-5p markedly attenuated MAP after renal silencing of TNF in mice given 1% NaCl.

CONCLUSIONS

The study identifies miR-195a-5p as a salt-sensitive and TNF-inducible miRNA that attenuates NaCl-mediated increases in blood pressure by inhibiting NKCC2A.

Machine Learning Approximations to Predict Epigenetic Age Acceleration in Stroke Patients

Age acceleration (Age-A) is a useful tool that is able to predict a broad range of health outcomes. It is necessary to determine DNA methylation levels to estimate it, and it is known that Age-A is influenced by environmental, lifestyle, and vascular risk factors (VRF). The aim of this study is to estimate the contribution of these easily measurable factors to Age-A in patients with cerebrovascular disease (CVD), using different machine learning (ML) approximations, and try to find a more accessible model able to predict Age-A. We studied a CVD cohort of 952 patients with information about VRF, lifestyle habits, and target organ damage. We estimated Age-A using Hannum's epigenetic clock, and trained six different models to predict Age-A: a conventional linear regression model, four ML models (elastic net regression (EN), K-Nearest neighbors, random forest, and support vector machine models), and one deep learning approximation (multilayer perceptron (MLP) model). The best-performing models were EN and MLP; although, the predictive capability was modest (R² 0.358 and 0.378, respectively). In conclusion, our results support the influence of these factors on Age-A; although, they were not enough to explain most of its variability.

Sorting nexins: role in the regulation of blood pressure

Sorting nexins (SNXs) are a family of proteins that regulate cellular cargo sorting and trafficking, maintain intracellular protein homeostasis, and participate in intracellular signaling. SNXs are also important in the regulation of blood pressure via several mechanisms. Aberrant expression and dysfunction of SNXs participate in the dysregulation of blood pressure. Genetic studies show a correlation between SNX gene variants and the response to antihypertensive drugs. In this review, we summarize the progress in SNX-mediated regulation of blood pressure, discuss the potential role of SNXs in the pathophysiology and treatment of hypertension, and propose novel strategies for the medical therapy of hypertension.

Summary of Known Genetic and Epigenetic Modification Contributed to Hypertension

Hypertension is a multifactorial disease due to a complex interaction among genetic, epigenetic, and environmental factors. Characterized by raised blood pressure (BP), it is responsible for more than 7 million deaths per annum by acting as a leading preventable risk factor for cardiovascular disease. Reports suggest that genetic factors are estimated to be involved in approximately 30 to 50% of BP variation, and epigenetic marks are known to contribute to the initiation of the disease by influencing gene expression. Consequently, elucidating the genetic and epigenetic mediators associated with hypertension is essential for better discernment of its pathophysiology. By deciphering the unprecedented molecular hypertension basis, it could help to unravel an individual's inclination towards hypertension which eventually could result in an arrangement of potential strategies for prevention and therapy. In the present review, we discuss known genetic and epigenetic drivers that contributed to the hypertension development and summarize the novel variants that have currently been identified. The effect of these molecular alterations on endothelial function was also presented.

Progress in molecular biology and translational science: Epigenetics in cardiovascular health and disease

Conrad Waddington's epigenetics landscape has provided a metaphorical framework for how cells progress from undifferentiated states to one of several discrete, distinct, differentiated cell fates. The understanding of epigenetics has evolved over time, with DNA methylation being the most studied epigenetic modification, followed by histone modifications and non-coding RNA. Cardiovascular diseases (CVD) are leading contributors to death worldwide, with the prevalence of CVDs increasing across the last couple of decades. Significant amount of resources being poured into researching key mechanisms and underpinnings of the various CVDs. These molecular studies looked at the genetics, epigenetics as well as the transcriptomics of various cardiovascular conditions, aiming to provide mechanistic insights. It has paved the way for therapeutics to be developed and in recent years, epi-drugs for the treatment of CVDs. This chapter aims to cover the various roles of epigenetics in the context of cardiovascular health and disease. The following will be examined in detail: the developments in basic experimental techniques used to study epigenetics, the role of epigenetics in various CVDs (hypertension, atrial fibrillation, atherosclerosis, and heart failure), and current advances in epi-therapeutics, providing a holistic view of the current concerted efforts in advancing the field of epigenetics in CVDs.

The Interaction of Trauma Exposure and DNA Methylation on Blood Pressure Among Black Women in the InterGEN Study

Objective

Despite evidence that trauma exposure is linked to higher risk of hypertension, epigenetic mechanisms (such as DNA methylation) by which trauma potentially influences hypertension risk among Black adults remain understudied.

Methods

Data from a longitudinal study of Black mothers were used to test the hypothesis that direct childhood trauma (ie, personal exposure) and vicarious trauma (ie, childhood trauma experienced by their children) would interact with DNA methylation to increase blood pressure (BP). Separate linear mixed effects models were fitted at each CpG site with the DNA methylation beta-value and direct and vicarious trauma as predictors and systolic and diastolic BP modeled as dependent variables adjusted for age, cigarette smoking, and body mass index. Interaction terms between DNA methylation beta-values with direct and vicarious trauma were added.

Results

The sample included 244 Black mothers with a mean age of 31.2 years (SD = ±5.8). Approximately 45% of participants reported at least one form of direct childhood trauma and 49% reported at least one form of vicarious trauma. Epigenome-wide interaction analyses found that no CpG sites passed the epigenome-wide significance level indicating the interaction between direct or vicarious trauma with DNAm did not influence systolic or diastolic BP.

Conclusions

This is one of the first studies to simultaneously examine whether direct or vicarious exposure to trauma interact with DNAm to influence BP. Although findings were null, this study highlights directions for future research that investigates epigenetic mechanisms that may link trauma exposure with hypertension risk in Black women.

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.

Advances in pathogenesis and treatment of essential hypertension

Hypertension is a significant risk factor for cardiovascular and cerebrovascular diseases and the leading cause of premature death worldwide. However, the pathogenesis of the hypertension, especially essential hypertension, is complex and requires in-depth studies. Recently, new findings about essential hypertension have emerged, and these may provide important theoretical bases and therapeutic tools to break through the existing bottleneck of essential hypertension. In this review, we demonstrated important advances in the different pathogenesis areas of essential hypertension, and highlighted new treatments proposed in these areas, hoping to provide insight for the prevention and treatment of the essential hypertension.

The potential impact of a probiotic: Akkermansia muciniphila in the regulation of blood pressure—the current facts and evidence

Akkermansia muciniphila (A. muciniphila) is present in the human gut microbiota from infancy and gradually increases in adulthood. The potential impact of the abundance of A. muciniphila has been studied in major cardiovascular diseases including elevated blood pressure or hypertension (HTN). HTN is a major factor in premature death worldwide, and approximately 1.28 billion adults aged 30–79 years have hypertension. A. muciniphila is being considered a next-generation probiotic and though numerous studies had highlighted the positive role of A. muciniphila in lowering/controlling the HTN, however, few studies had highlighted the negative impact of increased abundance of A. muciniphila in the management of HTN. Thus, in the review, we aimed to discuss the current facts, evidence, and controversy about the role of A. muciniphila in the pathophysiology of HTN and its potential effect on HTN management/regulation, which could be beneficial in identifying the drug target for the management of HTN.

The roles and mechanisms of epigenetic regulation in pathological myocardial remodeling

Pathological myocardial remodeling was still one of the leading causes of death worldwide with an unmet therapeutic need. A growing number of researchers have addressed the role of epigenome changes in cardiovascular diseases, paving the way for the clinical application of novel cardiovascular-related epigenetic targets in the future. In this review, we summarized the emerged advances of epigenetic regulation, including DNA methylation, Histone posttranslational modification, Adenosine disodium triphosphate (ATP)-dependent chromatin remodeling, Non-coding RNA, and RNA modification, in pathological myocardial remodeling. Also, we provided an overview of the mechanisms that potentially involve the participation of these epigenetic regulation.

The association between Alu hypomethylation and the severity of hypertension

Introduction

Epigenetic changes that cause genomic instability may be the basis of pathogenic processes of age-associated noncommunicable diseases (NCDs). Essential hypertension is one of the most common NCDs. Alu hypomethylation is an epigenetic event that is commonly found in elderly individuals. Epigenomic alterations are also found in age-associated NCDs such as osteoporosis and diabetes mellitus. Alu methylation prevents DNA from being damaged. Therefore, Alu hypomethylated DNA accumulates DNA damage and, as a result, causes organ function deterioration. Here, we report that Alu hypomethylation is a biomarker for essential hypertension.

Results

We investigated Alu methylation levels in white blood cells from normal controls, patients with prehypertension, and patients with hypertension. The hypertension group possessed the lowest Alu methylation level when classified by systolic blood pressure and diastolic blood pressure (P = 0.0002 and P = 0.0088, respectively). In the hypertension group, a higher diastolic blood pressure and a lower Alu methylation level were observed (r = -0.6278). Moreover, we found that changes in Alu hypomethylation in the four years of follow-up in the same person were directly correlated with increased diastolic blood pressure.

Conclusions

Similar to other age-associated NCDs, Alu hypomethylation is found in essential hypertension and is directly correlated with severity, particularly with diastolic blood pressure. Therefore, Alu hypomethylation may be linked with the molecular pathogenesis of high blood pressure and can be used for monitoring the clinical outcome of this disease.

Predicting High Blood Pressure Using DNA Methylome-Based Machine Learning Models

DNA methylation modification plays a vital role in the pathophysiology of high blood pressure (BP). Herein, we applied three machine learning (ML) algorithms including deep learning (DL), support vector machine, and random forest for detecting high BP using DNA methylome data. Peripheral blood samples of 50 elderly individuals were collected three times at three visits for DNA methylome profiling. Participants who had a history of hypertension and/or current high BP measure were considered to have high BP. The whole dataset was randomly divided to conduct a nested five-group cross-validation for prediction performance. Data in each outer training set were independently normalized using a min–max scaler, reduced dimensionality using principal component analysis, then fed into three predictive algorithms. Of the three ML algorithms, DL achieved the best performance (AUPRC = 0.65, AUROC = 0.73, accuracy = 0.69, and F1-score = 0.73). To confirm the reliability of using DNA methylome as a biomarker for high BP, we constructed mixed-effects models and found that 61,694 methylation sites located in 15,523 intragenic regions and 16,754 intergenic regions were significantly associated with BP measures. Our proposed models pioneered the methodology of applying ML and DNA methylome data for early detection of high BP in clinical practices.

Novel mitochondrial tRNALeu(UUR) 3261A > g mutation in two pedigrees with essential hypertension

BACKGROUND

Essential hypertension (EH) was associated with mitochondrial tRNA mutations.

AIMS

This study was designed to assess the association between EH and mitochondrial dysfunction.

METHODS

A total of 30 individuals from two different Chinese families exhibit maternally inherited EH were assessed for genetic, clinical, and biochemical phenotypes pertaining to EH and mitochondrial functionality. These analyses included assessments of tRNA^Leu(UUR) 3261A > G mutation status, mitochondrial membrane permeability, mitochondria-associated ATP and reactive oxygen species (ROS) generation, and electron transport chain functionality.

RESULTS

EH was detected in 6 total analyzed members of the two families assessed in the present study, with its initial age of onset and presentation varying among patients. These patients with EH exhibited the tRNA^Leu(UUR) 3261A > G mutation and were of the B5 and D4 Eastern Asian mitochondrial haplogroups. This 3261A > G mutation was predicted to result in disruption of normal tRNA^Leu(UUR) activity owing to the destabilization of conserved base pairing (30A-40U). Consistent with this prediction, we found that cybrid cell lines exhibiting this 3261A > G mutation exhibited a ~49.05% decrease in baseline tRNA^Leu(UUR) levels. These cells additionally exhibited ~44.81% reductions in rates of mitochondrial translation.

CONCLUSIONS

To facilitate future molecular diagnosis, the 3261A > G mutation should be included in the list of hereditary risk factors. Our findings will aid in the counseling of EH families.

Gestational exposure to neighborhood police-reported crime and early childhood blood pressure in Durham, NC

Gestational exposure to police-reported crime is associated with adverse birth outcomes, but no previous research has evaluated the effects of gestational crime exposure on early childhood health or attempted to disentangle the health effects of neighborhood crime from the effects of neighborhood policing. Using data from 672 Newborn Epigenetics Study participants, we evaluate the effects of gestational exposure to violent crime and racialized drug policing on early childhood blood pressure. We demonstrate that violence and drug policing are consistently associated with increased blood pressure among children born to Black participants but not White or Latinx participants.

Emerging Roles and Mechanism of m6A Methylation in Cardiometabolic Diseases

Cardiometabolic diseases (CMDs) are currently the leading cause of death and disability worldwide, and their underlying regulatory mechanisms remain largely unknown. N6-methyladenosine (m6A) methylation, the most common and abundant epigenetic modification of eukaryotic mRNA, is regulated by m6A methyltransferase, demethylase, and the m6A binding protein, which affect the transcription, cleavage, translation, and degradation of target mRNA. m6A methylation plays a vital role in the physiological and pathological processes of CMDs. In this review, we summarize the role played by m6A methylation in CMDs, including obesity, hypertension, pulmonary hypertension, ischemic heart disease, myocardial hypertrophy, heart failure, and atherosclerosis. We also describe mechanisms that potentially involve the participation of m6A methylation, such as those driving calcium homeostasis, circadian rhythm, lipid metabolism, autophagy, macrophage response, and inflammation. m6A methylation and its regulators are expected to be targets for the treatment of CMDs.

Pharmacoepigenetics of hypertension: genome-wide methylation analysis of responsiveness to four classes of antihypertensive drugs using a double-blind crossover study design

Essential hypertension remains the leading risk factor of global disease burden, but its treatment goals are often not met. We investigated whether DNA methylation is associated with antihypertensive responses to a diuretic, a beta-blocker, a calcium channel blocker or an angiotensin receptor antagonist. In addition, since we previously showed an SNP at the transcription start site (TSS) of the catecholamine biosynthesis-related ACY3 gene to associate with blood pressure (BP) response to beta-blockers, we specifically analysed the association of methylation sites close to the ACY3 TSS with BP responses to beta-blockers. We conducted an epigenome-wide association study between leukocyte DNA methylation and BP responses to antihypertensive monotherapies in two hypertensive Finnish cohorts: the GENRES (https://clinicaltrials.gov/ct2/show/NCT03276598; amlodipine 5 mg, bisoprolol 5 mg, hydrochlorothiazide 25 mg, or losartan 50 mg daily) and the LIFE-Fin studies (https://clinicaltrials.gov/ct2/show/NCT00338260; atenolol 50 mg or losartan 50 mg daily). The monotherapy groups consisted of approximately 200 individuals each. We identified 64 methylation sites to suggestively associate (P < 1E-5) with either systolic or diastolic BP responses to a particular study drug in GENRES. These associations did not replicate in LIFE-Fin . Three methylation sites close to the ACY3 TSS were associated with systolic BP responses to bisoprolol in GENRES but not genome-wide significantly (P < 0.05). No robust associations between DNA methylation and BP responses to four different antihypertensive drugs were identified. However, the findings on the methylation sites close to the ACY3 TSS may support the role of ACY3 genetic and epigenetic variation in BP response to bisoprolol.

Novel methylation mark and essential hypertension

Background

Essential hypertension (EH) is an important risk factor for various cardiovascular, cerebral and renal disorders. It is a multi-factorial trait which occurs through complex interplay between genetic, epigenetic, and environmental factors. Even after advancement of technology and deciphering the involvement of multiple signalling pathways in blood pressure regulation, it still remains as a huge global concern.

Main body of the abstract

Genome-wide association studies (GWAS) have revealed EH-associated genetic variants but these solely cannot explain the variability in blood pressure indicating the involvement of additional factors. The etiopathogenesis of hypertension has now advanced to the level of epigenomics where aberrant DNA methylation is the most defined epigenetic mechanism to be involved in gene regulation. Though role of DNA methylation in cancer and other mechanisms is deeply studied but this mechanism is in infancy in relation to hypertension. Generally, 5-methylcytosine (5mC) levels are being targeted at both individual gene and global level to find association with the disease. But recently, with advanced sequencing techniques another methylation mark, N6-methyladenine (6mA) was found and studied in humans which was earlier considered to be absent in case of eukaryotes. Relation of aberrant 6mA levels with cancer and stem cell fate has drawn attention to target 6mA levels with hypertension too.

Conclusion

Recent studies targeting hypertension has suggested 6mA levels as novel marker and its demethylase, ALKBH1 as probable therapeutic target to prevent hypertension through epigenetic programming. This review compiles different methylation studies and suggests targeting of both 5mC and 6mA levels to cover role of methylation in hypertension in broader scenario.

Unique Associations of DNA Methylation Regions With 24-Hour Blood Pressure Phenotypes in Blacks

BACKGROUND

Epigenetic marks (eg, DNA methylation) may capture the effect of gene-environment interactions. DNA methylation is involved in blood pressure (BP) regulation and hypertension development; however, no studies have evaluated its relationship with 24-hour BP phenotypes (daytime, nighttime, and 24-hour average BPs).

METHODS

We examined the association of whole blood DNA methylation with 24-hour BP phenotypes and clinic BPs in a discovery cohort of 281 Blacks using reduced representation bisulfite sequencing. We developed a deep and region-specific methylation sequencing method, Bisulfite ULtrapLEx Targeted Sequencing and utilized it to validate our findings in a separate validation cohort (n=117).

RESULTS

Analysis of 38 215 DNA methylation regions (MRs), derived from 1 549 368 CpG sites across the genome, identified up to 72 regions that were significantly associated with 24-hour BP phenotypes. No MR was significantly associated with clinic BP. Two to 3 MRs were significantly associated with various 24-hour BP phenotypes after adjustment for age, sex, and body mass index. Together, these MRs explained up to 16.5% of the variance of 24-hour average BP, while age, sex, and BMI explained up to 11.0% of the variance. Analysis of one of the MRs in an independent cohort using Bisulfite ULtrapLEx Targeted Sequencing confirmed its association with 24-hour average BP phenotype.

CONCLUSIONS

We identified several MRs that explain a substantial portion of variances in 24-hour BP phenotypes, which might be excellent markers of cumulative effect of factors influencing 24-hour BP levels. The Bisulfite ULtrapLEx Targeted Sequencing workflow has potential to be suitable for clinical testing and population screenings on a large scale.

Fetal Undernutrition Programming, Sympathetic Nerve Activity, and Arterial Hypertension Development

A wealth of evidence showed that low birth weight is associated with environmental disruption during gestation, triggering embryotic or fetal adaptations and increasing the susceptibility of progeny to non-communicable diseases, including metabolic and cardiovascular diseases, obesity, and arterial hypertension. In addition, dietary disturbance during pregnancy in animal models has highlighted mechanisms that involve the genesis of arterial hypertension, particularly severe maternal low-protein intake (LP). Functional studies demonstrated that maternal low-protein intake leads to the renal decrease of sodium excretion and the dysfunction of the renin-angiotensin-aldosterone system signaling of LP offspring. The antinatriuretic effect is accentuated by a reduced number of nephron units and glomerulosclerosis, which are critical in establishing arterial hypertension phenotype. Also, in this way, studies have shown that the overactivity of the central and peripheral sympathetic nervous system occurs due to reduced sensory (afferent) renal nerve activity. As a result of this reciprocal and abnormal renorenal reflex, there is an enhanced tubule sodium proximal sodium reabsorption, which, at least in part, contributes directly to arterial hypertension development in some of the programmed models. A recent study has observed that significant changes in adrenal medulla secretion could be involved in the pathophysiological process of increasing blood pressure. Thus, this review aims to compile studies that link the central and peripheral sympathetic system activity mechanisms on water and salt handle and blood pressure control in the maternal protein-restricted offspring. Besides, these pathophysiological mechanisms mainly may involve the modulation of neurokinins and catecholamines pathways.

The severity of SARS-CoV-2 infection is dictated by host factors? Epigenetic perspectives

The emergence of COVID-19, caused by SARS-CoV-2 poses a significant threat to humans as it is highly contagious with increasing mortality. There exists a high degree of heterogeneity in the mortality rates of COVID-19 across the globe. There are multiple speculations on the varying degree of mortality. Still, all the clinical reports have indicated that preexisting chronic diseases like hypertension, diabetes, chronic obstructive pulmonary disease (COPD), kidney disorders, and cardiovascular diseases are associated with the increased risk for high mortality in SARS-CoV-2 infected patients. It is worth noting that host factors, mainly epigenetic factors could play a significant role in deciding the outcome of COVID-19 diseases. Over the recent years, it is evident that chronic diseases are developed due to altered epigenome that includes a selective loss/gain of DNA and histone methylation on the chromatin of the cells. Since, there is a high positive correlation between chronic diseases and elevated mortality due to SARS-CoV-2, in this review; we discuss the overall picture of the aberrant epigenome map in varying chronic ailments and its implications in COVID-19 disease severity and high mortality.

Recent advances in the epigenetics of bone metabolism

Osteoporosis is a common form of metabolic bone disease that is costly to treat and is primarily diagnosed on the basis of bone mineral density. As the influences of genetic lesions and environmental factors are increasingly studied in the pathological development of osteoporosis, regulated epigenetics are emerging as the important pathogenesis mechanisms in osteoporosis. Recently, osteoporosis genome-wide association studies and multi-omics technologies have revealed that susceptibility loci and the misregulation of epigenetic modifiers are key factors in osteoporosis. Over the past decade, extensive studies have demonstrated epigenetic mechanisms, such as DNA methylation, histone/chromatin modifications, and non-coding RNAs, as potential contributing factors in osteoporosis that affect disease initiation and progression. Herein, we review recent advances in epigenetics in osteoporosis, with a focus on exploring the underlying mechanisms and potential diagnostic/prognostic biomarker applications for osteoporosis.

Insights into the Mechanisms of Fetal Growth Restriction-Induced Programming of Hypertension

In recent decades, both clinical and animal studies have shown that fetal growth restriction (FGR), caused by exposure to adverse uterine environments, is a risk factor for hypertension as well as for a variety of adult diseases. This observation has shaped and informed the now widely accepted theory of developmental origins of health and disease (DOHaD). There is a plethora of evidence supporting the association of FGR with increased risk of adult hypertension; however, the underlying mechanisms responsible for this correlation remain unclear. This review aims to explain the current advances in the field of fetal programming of hypertension and a brief narration of the underlying mechanisms that may link FGR to increased risk of adult hypertension. We explain the theory of DOHaD and then provide evidence from both clinical and basic science research which support the theory of fetal programming of adult hypertension. In addition, we have explored the underlying mechanisms that may link FGR to an increased risk of adult hypertension. These mechanisms include epigenetic changes, metabolic disorders, vascular dysfunction, neurohormonal impairment, and alterations in renal physiology and function. We further describe sex differences seen in the developmental origins of hypertension and provide insights into the opportunities and challenges present in this field.

miR-204: Molecular Regulation and Role in Cardiovascular and Renal Diseases

The field of microRNA research has evolved from studies aiming to gauge the importance of microRNAs to those focusing on understanding a subset of specific microRNAs that have emerged as potent regulators of molecular systems and pathophysiological conditions. In this article, we review the molecular features and regulation of miR-204 and the growing body of evidence for an important role of miR-204 in the regulation of cardiovascular and renal physiology and pathophysiological processes. miR-204 exhibits a highly tissue-specific expression pattern, and miR-204 abundance is regulated by several transcriptional and posttranscriptional mechanisms. Strong evidence supports a role for miR-204 in attenuating pulmonary arterial hypertension and hypertensive and diabetic renal injury while promoting hypertension and endothelial dysfunction in a wide range of model systems. miR-204 may influence these disease processes by targeting several biological pathways in a tissue-specific manner. miR-204 is dysregulated in patients with cardiovascular and renal diseases. The unequivocal functional roles and clear clinical relevance indicate that miR-204 is a high-value microRNA in cardiovascular and renal diseases.

Dietary Sodium Restriction Results in Tissue-Specific Changes in DNA Methylation in Humans

[Figure: see text].

Team Science: American Heart Association's Hypertension Strategically Focused Research Network Experience

In 2015, the American Heart Association awarded 4-year funding for a Strategically Focused Research Network focused on hypertension composed of 4 Centers: Cincinnati Children's Hospital, Medical College of Wisconsin, University of Alabama at Birmingham, and University of Iowa. Each center proposed 3 integrated (basic, clinical, and population science) projects around a single area of focus relevant to hypertension. Along with scientific progress, the American Heart Association put a significant emphasis on training of next-generation hypertension researchers by sponsoring 3 postdoctoral fellows per center over 4 years. With the center projects being spread across the continuum of basic, clinical, and population sciences, postdoctoral fellows were expected to garner experience in various types of research methodologies. The American Heart Association also provided a number of leadership development opportunities for fellows and investigators in these centers. In addition, collaboration was highly encouraged among the centers (both within and outside the network) with the American Heart Association providing multiple opportunities for meeting and expanding associations. The area of focus for the Cincinnati Children's Hospital Center was hypertension and target organ damage in children utilizing ambulatory blood pressure measurements. The Medical College of Wisconsin Center focused on epigenetic modifications and their role in pathogenesis of hypertension using human and animal studies. The University of Alabama at Birmingham Center's areas of research were diurnal blood pressure patterns and clock genes. The University of Iowa Center evaluated copeptin as a possible early biomarker for preeclampsia and vascular endothelial function during pregnancy. In this review, challenges faced and successes achieved by the investigators of each of the centers are presented.

Modeling Precision Cardio-Oncology: Using Human-Induced Pluripotent Stem Cells for Risk Stratification and Prevention

Purpose of Review

Cardiovascular toxicity is a leading cause of mortality among cancer survivors and has become increasingly prevalent due to improved cancer survival rates. In this review, we synthesize evidence illustrating how common cancer therapeutic agents, such as anthracyclines, human epidermal growth factors receptors (HER2) monoclonal antibodies, and tyrosine kinase inhibitors (TKIs), have been evaluated in cardiomyocytes (CMs) derived from human-induced pluripotent stem cells (hiPSCs) to understand the underlying mechanisms of cardiovascular toxicity. We place this in the context of precision cardio-oncology, an emerging concept for personalizing the prevention and management of cardiovascular toxicities from cancer therapies, accounting for each individual patient’s unique factors. We outline steps that will need to be addressed by multidisciplinary teams of cardiologists and oncologists in partnership with regulators to implement future applications of hiPSCs in precision cardio-oncology.

Recent Findings

Current prevention of cardiovascular toxicity involves routine screenings and management of modifiable risk factors for cancer patients, as well as the initiation of cardioprotective medications. Despite recent advancements in precision cardio-oncology, knowledge gaps remain and limit our ability to appropriately predict with precision which patients will develop cardiovascular toxicity. Investigations using patient-specific CMs facilitate pharmacological discovery, mechanistic toxicity studies, and the identification of cardioprotective pathways. Studies with hiPSCs demonstrate that patients with comorbidities have more frequent adverse responses, compared to their counterparts without cardiac disease. Further studies utilizing hiPSC modeling should be considered, to evaluate the impact and mitigation of known cardiovascular risk factors, including blood pressure, body mass index (BMI), smoking status, diabetes, and physical activity in their role in cardiovascular toxicity after cancer therapy. Future real-world applications will depend on understanding the current use of hiPSC modeling in order for oncologists and cardiologists together to inform their potential to improve our clinical collaborative practice in cardio-oncology.

Summary

When applying such in vitro characterization, it is hypothesized that a safety score can be assigned to each individual to determine who has a greater probability of developing cardiovascular toxicity. Using hiPSCs to create personalized models and ultimately evaluate the cardiovascular toxicity of individuals’ treatments may one day lead to more patient-specific treatment plans in precision cardio-oncology while reducing cardiovascular disease (CVD) morbidity and mortality.

Kidney and epigenetic mechanisms of salt-sensitive hypertension

Dietary salt intake increases blood pressure (BP) but the salt sensitivity of BP differs between individuals. The interplay of ageing, genetics and environmental factors, including malnutrition and stress, contributes to BP salt sensitivity. In adults, obesity is often associated with salt-sensitive hypertension. The children of women who experience malnutrition during pregnancy are at increased risk of developing obesity, diabetes and salt-sensitive hypertension as adults. Similarly, the offspring of mice that are fed a low-protein diet during pregnancy develop salt-sensitive hypertension in association with aberrant DNA methylation of the gene encoding type 1A angiotensin II receptor (AT_1AR) in the hypothalamus, leading to upregulation of hypothalamic AT_1AR and renal sympathetic overactivity. Ageing is also associated with salt-sensitive hypertension. In aged mice, promoter methylation leads to reduced kidney production of the anti-ageing factor Klotho and a decrease in circulating soluble Klotho. In the setting of Klotho deficiency, salt-induced activation of the vascular Wnt5a-RhoA pathway leads to ageing-associated salt-sensitive hypertension, potentially as a result of reduced renal blood flow and increased peripheral resistance. Thus, kidney mechanisms and aberrant DNA methylation of certain genes are involved in the development of salt-sensitive hypertension during fetal development and old age. Three distinct paradigms of epigenetic memory operate on different timescales in prenatal malnutrition, obesity and ageing.

DNA Methylation of the Angiotensinogen Gene, AGT, and the Aldosterone Synthase Gene, CYP11B2 in Cardiovascular Diseases

Angiotensinogen (AGT) and aldosterone play key roles in the regulation of blood pressure and are implicated in the pathogenesis of cardiovascular diseases. DNA methylation typically acts to repress gene transcription. The aldosterone synthase gene CYP11B2 is regulated by angiotensin II and potassium. DNA methylation negatively regulates AGT and CYP11B2 expression and dynamically changes in response to continuous promoter stimulation of each gene. High salt intake and excess circulating aldosterone cause DNA demethylation around the CCAAT-enhancer-binding-protein (CEBP) sites of the ATG promoter region, thereby converting the phenotype of AGT expression from an inactive to an active state in visceral adipose tissue and heart. A close association exists between low DNA methylation at CEBP-binding sites and increased AGT expression in salt-sensitive hypertensive rats. Salt-dependent hypertension may be partially affected by increased cardiac AGT expression. CpG dinucleotides in the CYP11B2 promoter are hypomethylated in aldosterone-producing adenomas. Methylation of recognition sequences of transcription factors, including CREB1, NGFIB (NR4A1), and NURR1 (NR4A2) diminish their DNA-binding activity. The methylated CpG-binding protein MECP2 interacts directly with the methylated CYP11B2 promoter. Low salt intake and angiotensin II infusion lead to upregulation of CYP11B2 expression and DNA hypomethylation in the adrenal gland. Treatment with the angiotensin II type 1 receptor antagonist decreases CYP11B2 expression and leads to DNA hypermethylation. A close association between low DNA methylation and increased CYP11B2 expression are seen in the hearts of patients with hypertrophic cardiomyopathy. These results indicate that epigenetic regulation of both AGT and CYP11B2 contribute to the pathogenesis of cardiovascular diseases.

DNA Methylation and Blood Pressure Phenotypes: A Review of the Literature

Genetic studies of DNA have been unable to explain a significant portion of the variance of the estimated heritability of blood pressure (BP). Epigenetic mechanisms, particularly DNA methylation, have helped explain additional biological processes linked to BP phenotypes and diseases. Candidate gene methylation studies and genome-wide methylation studies of BP have highlighted impactful cytosine-phosphate-guanine (CpG) markers across different ethnicities. Furthermore, many of these BP-related CpG sites are also linked to metabolism-related phenotypes. Integrating epigenome-wide association study data with other layers of molecular data such as genotype data (from single nucleotide polymorphism arrays or sequencing), other epigenetic data, and/or transcriptome data can provide additional information about the significance and complexity of these relationships. Recent data suggest that epigenetic changes can be consequences rather than causes of BP variation. Finally, these data can give insight into downstream effects of long-standing high BP (due to target organ damage (TOD)). The current review provides a literature overview of epigenetic modifications in BP and TOD. Recent studies strongly support the importance of epigenetic modifications, such as DNA methylation, in BP and TOD for relevant biological insights, reliable biomarkers, and possible future therapeutics.

Renal metabolism and hypertension

Hypertension is a leading risk factor for disease burden worldwide. The kidneys, which have a high specific metabolic rate, play an essential role in the long-term regulation of arterial blood pressure. In this review, we discuss the emerging role of renal metabolism in the development of hypertension. Renal energy and substrate metabolism is characterized by several important and, in some cases, unique features. Recent advances suggest that alterations of renal metabolism may result from genetic abnormalities or serve initially as a physiological response to environmental stressors to support tubular transport, which may ultimately affect regulatory pathways and lead to unfavorable cellular and pathophysiological consequences that contribute to the development of hypertension.

An Academic Clinician's Road Map to Hypertension Genomics: Recent Advances and Future Directions MMXX

At the dawn of the new decade, it is judicious to reflect on the boom of knowledge about polygenic risk for essential hypertension supplied by the wealth of genome-wide association studies. Hypertension continues to account for significant cardiovascular morbidity and mortality, with increasing prevalence anticipated. Here, we overview recent advances in the use of big data to understand polygenic hypertension, as well as opportunities for future innovation to translate this windfall of knowledge into clinical benefit.

Advances in Nutritional Epigenetics-A Fresh Perspective for an Old Idea. Lessons Learned, Limitations, and Future Directions

Nutritional epigenetics is a rapidly expanding field of research, and the natural modulation of the genome is a non-invasive, sustainable, and personalized alternative to gene-editing for chronic disease management. Genetic differences and epigenetic inflexibility resulting in abnormal gene expression, differential or aberrant methylation patterns account for the vast majority of diseases. The expanding understanding of biological evolution and the environmental influence on epigenetics and natural selection requires relearning of once thought to be well-understood concepts. This research explores the potential for natural modulation by the less understood epigenetic modifications such as ubiquitination, nitrosylation, glycosylation, phosphorylation, and serotonylation concluding that the under-appreciated acetylation and mitochondrial dependant downstream epigenetic post-translational modifications may be the pinnacle of the epigenomic hierarchy, essential for optimal health, including sustainable cellular energy production. With an emphasis on lessons learned, this conceptional exploration provides a fresh perspective on methylation, demonstrating how increases in environmental methane drive an evolutionary down regulation of endogenous methyl groups synthesis and demonstrates how epigenetic mechanisms are cell-specific, making supplementation with methyl cofactors throughout differentiation unpredictable. Interference with the epigenomic hierarchy may result in epigenetic inflexibility, symptom relief and disease concomitantly and may be responsible for the increased incidence of neurological disease such as autism spectrum disorder.

Anti-Hypertensive Potential and Epigenetics of Angiotensin II type 2 Receptor (AT2R)

BACKGROUND

Renin angiotensin system (RAS) is a critical pathway involved in blood pressure regulation. Octapeptide, angiotensin II (Ang II), is a biologically active compound of RAS pathway which mediates its action by binding to either angiotensin II type 1 receptor (AT1R) or angiotensin II type 2 receptor (AT2R). Binding of Ang II to AT1R facilitates blood pressure regulation, whereas AT2R is primarily involved in wound healing and tissue remodeling.

OBJECTIVES

Recent studies have highlighted the additional role of AT2R to counterbalance the detrimental effects of AT1R. Activation of angiotensin II type 2 receptor using AT2R agonist has shown the effect on natriuresis and release of nitric oxide. Additionally, AT2R activation has been found to inhibit angiotensin converting enzyme (ACE) and enhance angiotensin receptor blocker (ARB) activity. These findings highlight the potential of AT2R as a novel therapeutic target against hypertension.

CONCLUSION

The potential role of AT2R highlights the importance of exploring additional mechanisms that might be crucial for AT2R expression. Epigenetic mechanisms, including DNA methylation and histone modification, have been explored vastly with relation to cancer, but the role of such mechanisms in the expression of AT2R has recently gained interest.

MicroRNA-133a-Dependent Inhibition of Proximal Tubule Angiotensinogen by Renal TNF (Tumor Necrosis Factor)

We showed that intrarenal suppression of TNF (tumor necrosis factor) production under low salt (LS) conditions increases renal cortical AGT (angiotensinogen) mRNA and protein expression. Intrarenal injection of murine recombinant TNF attenuated increases of AGT in mice ingesting LS. Moreover, AGT mRNA and protein expression increased ≈6-fold and 2-fold, respectively, in mice ingesting LS that also received an intrarenal injection of a lentivirus construct that specifically silenced TNF in the kidney (U6-TNF-ex4). Silencing of TNF under normal salt and high salt (HS) conditions also resulted in increased AGT expression. Since renal TNF production decreases in response to LS and increases in response to HS, the data suggest that alterations in TNF production under these conditions modulate the degree of AGT expression. We also tested the hypothesis that TNF inhibits intrarenal AGT expression by a mechanism involving miR-133a. Expression of miR-133a decreased in mice given LS and increased in response to HS for 7 days. Intrarenal silencing of TNF reversed the effects of HS on miR-133a-dependent AGT expression. In contrast, intrarenal TNF administration increased miR-133a expression in the kidney. Collectively, the data suggest that miR-133a is a salt-sensitive microRNA that inhibits AGT in the kidney and is increased by TNF. The HS-induced increase in blood pressure observed following silencing of TNF was markedly reduced upon intrarenal administration of miR-133a suggesting that intrinsic effects of TNF in the kidney to limit the blood pressure response to HS include an increase in miR-133a, which suppresses AGT expression.

Plant-Based Diets and Hypertension

Hypertension is a global epidemic and a risk factor for many adverse outcomes, including cardiovascular disease, kidney disease, and death. Lifestyle plays a significant role in the development and maintenance of hypertension, and guidelines from several organizations recommend lifestyle modifications as first-line intervention for hypertensive patients. Data supporting the use of plant-based diets in the treatment of hypertension goes back almost a century. More recently, clinical trial data, including randomized controlled trials, have established plant-based diets as an effective lifestyle intervention for high blood pressure (BP). Plant-based diets differ from the standard American diet in a myriad of ways, with some substances being present in either substantially higher or lower amounts. Although the precise mechanism of a plant-based diet's beneficial effects on BP is unknown, many of these differences may be responsible. Attributes of a plant-based diet that may lower BP include a lower energy content leading to weight loss, a lower sodium content, an increased potassium content, reduced oxidative stress, higher bioavailability of the vasodilator nitric oxide, and beneficial effects on the microbiome. The evidenced-based benefits of plant-based diets in treating hypertension should lead providers to advocate for this dietary pattern for their patients.