Tissue factor pathway inhibitor-2 gene methylation is associated with low expression in carotid atherosclerotic plaques

Methyl donor diet attenuates intimal hyperplasia after vascular injury in rats

Environmental factors, particularly dietary habits, play an important role in cardiovascular disease susceptibility and progression through epigenetic modification. Previous studies have shown that hyperplastic vascular intima after endarterectomy is characterized by genome-wide hypomethylation. The purpose of this study was to investigate whether methyl donor diet affects intimal hyperplasia and the possible mechanisms involved. Intimal hyperplasia was induced in SD rats by carotid artery balloon injury. From 8 d before surgery to 28 d after surgery, the animals were fed a normal diet (ND) or a methyl donor diet (MD) supplemented with folic acid, vitamin B12, choline, betaine, and zinc. Carotid artery intimal hyperplasia was observed by histology, the effect of MD on carotid protein expression was analyzed by proteomics, functional clustering, signaling pathway, and upstream-downstream relationship of differentially expressed proteins were analyzed by bioinformatics. Results showed that MD attenuated balloon injury-induced intimal hyperplasia in rat carotid arteries. Proteomic analysis showed that there were many differentially expressed proteins in the common carotid arteries of rats fed with two different diets. The differentially expressed proteins are mainly related to the composition and function of the extracellular matrix (EMC), and changes in the EMC can lead to vascular remodeling by affecting fibrosis and stiffness of the blood vessel wall. Changes in the levels of vasculotropic proteins such as S100A9, ILF3, Serpinh1, Fbln5, LOX, HSPG2, and Fmod may be the reason why MD attenuates intimal hyperplasia. Supplementation with methyl donor nutrients may be a beneficial measure to prevent pathological vascular remodeling after injury.

DNA methylation changes and inflammaging in aging-associated diseases

Aging as an inevitable phenomenon is associated with pervasive changes in physiological functions. There is a relationship between aging and the increase of several chronic diseases. Most age-related disorders are accompanied by an underlying chronic inflammatory state, as demonstrated by local infiltration of inflammatory cells and greater levels of proinflammatory cytokines in the bloodstream. Within inflammaging, many epigenetic events, especially DNA methylation, change. During the aging process, due to aberrations of DNA methylation, biological processes are disrupted, leading to the emergence or progression of a variety of human diseases, including cancer, neurodegenerative disorders, cardiovascular disease and diabetes. The focus of this review is on DNA methylation, which is involved in inflammaging-related activities, and how its dysregulation leads to human disorders.

Epigenetic Control of Vascular Smooth Muscle Cell Function in Atherosclerosis: A Role for DNA Methylation

Atherosclerosis is a complex vascular inflammatory disease in which multiple cell types are involved, including vascular smooth muscle cells (VSMCs). In response to vascular injury and inflammatory stimuli, VSMCs undergo a "phenotypic switching" characterized by extracellular matrix secretion, loss of contractility, and abnormal proliferation and migration, which play a key role in the progression of atherosclerosis. DNA methylation modification is an important epigenetic mechanism that plays an important role in atherosclerosis. Studies investigating abnormal DNA methylation in patients with atherosclerosis have determined a specific DNA methylation profile, and proposed multiple pathways and genes involved in the etiopathogenesis of atherosclerosis. Recent studies have also revealed that DNA methylation modification controls VSMC function by regulating gene expression involved in atherosclerosis. In this review, we summarize the recent advances regarding the epigenetic control of VSMC function by DNA methylation in atherosclerosis and provide insights into the development of VSMC-centered therapeutic strategies.

PARP1 deficiency protects against hyperglycemia-induced neointimal hyperplasia by upregulating TFPI2 activity in diabetic mice

Diabetes mellitus (DM) promotes neointimal hyperplasia, characterized by dysregulated proliferation and accumulation of vascular smooth muscle cells (VSMCs), leading to occlusive disorders, such as atherosclerosis and stenosis. Poly (ADP-ribose) polymerase 1 (PARP1), reported as a crucial mediator in tumor proliferation and transformation, has a pivotal role in DM. Nonetheless, the function and potential mechanism of PARP1 in diabetic neointimal hyperplasia remain unclear. In this study, we constructed PARP1 conventional knockout (PARP1^−/−) mice, and ligation of the left common carotid artery was performed to induce neointimal hyperplasia in Type I diabetes mellitus (T1DM) mouse models. PARP1 expression in the aorta arteries of T1DM mice increased significantly and genetic deletion of PARP1 showed an inhibitory effect on the neointimal hyperplasia. Furthermore, our results revealed that PARP1 enhanced diabetic neointimal hyperplasia via downregulating tissue factor pathway inhibitor (TFPI2), a suppressor of vascular smooth muscle cell proliferation and migration, in which PARP1 acts as a negative transcription factor augmenting TFPI2 promoter DNA methylation. In conclusion, these results suggested that PARP1 accelerates the process of hyperglycemia-induced neointimal hyperplasia via promoting VSMCs proliferation and migration in a TFPI2 dependent manner.

Toward an understanding of tissue factor pathway inhibitor-2 as a novel serodiagnostic marker for clear cell carcinoma of the ovary

AIMS

Tissue factor pathway inhibitor (TFPI)-2 has recently emerged as a serodiagnostic marker for patients with epithelial ovarian cancer (EOC), especially clear cell carcinoma (CCC). This review discusses the biological properties of TFPI-2 and why serum levels are elevated in CCC patients.

METHODS

A comprehensive literature search was conducted in PubMed up until March, 2021.

RESULTS

TFPI-2 is a Kunitz-type protease inhibitor and negatively regulates the enzymatic activities, such as plasmin. TFPI-2 has been characterized as a tumor suppressor gene and was frequently downregulated through promoter hypermethylation in various human cancers. In contrast, TFPI-2 was overexpressed only in CCC. TFPI-2 may be involved in the pathophysiology of CCC, possibly through regulation of coagulation system, stabilization of extracellular matrix (ECM), and induction of intracellular signal transduction. TFPI-2 suppresses tissue factor-induced hypercoagulation in a hypoxic environment. TFPI-2, secreted by CCC cells, platelets, and adjacent vascular endothelial cells, may suppress tumor growth and invasion through ECM remodeling. Nuclear TFPI-2 may suppress matrix metalloproteinase production via transcription factors and modulate caspase-mediated cell apoptosis. CCC cells may upregulate the TFPI-2 expression to adapt to survival in the demanding environment. TFPI-2 is secreted by CCC cells and enters the systemic circulation, resulting in elevated blood levels.

DISCUSSION

Serum TFPI-2 reflects the overexpression of TFPI-2 in CCC tissues and is a potential serodiagnostic marker. Further research is needed to explore the expression, clinical significance, biological function, and potential mechanism of TFPI-2 in CCC.

DNA Methylation in Atherosclerosis: A New Perspective

Atherosclerotic cardiovascular diseases, in which atherosclerosis (AS) is the main pathologic basis, are currently the primary diseases leading to human deaths. Emerging evidence showed that DNA methylation, which could affect the transcription and expression of critical regulatory genes, has key roles in AS. Aberrant DNA methylation including aberrant hypomethylation and hypermethylation plays key roles in endothelial-cell dysfunction, macrophage inflammation, abnormal proliferation of vascular smooth muscle cells, plaque rupture, and thrombosis in AS. Chinese herbal medicines, including single compounds and formulations, showed light on the treatment of AS through regulating the aberrant DNA methylation in AS. Targeting the aberrant DNA methylation may be one of the most important treatment strategies in the cure and prevention of AS. In this review, we focus on the relationship between DNA methylation and AS, as well as the beneficial effects of Chinese herbal medicines on DNA methylation in AS.

Interaction between tissue factor pathway inhibitor-2 gene polymorphisms and environmental factors associated with coronary atherosclerosis in a Chinese Han

To investigate the association of single nucleotide polymorphisms (SNPs) within tissue factor pathway inhibitor-2 (TFPI-2) gene polymorphisms and additional gene-environment interaction with coronary atherosclerosis risk. Generalized multifactor dimensionality reduction (GMDR) was used to screen the best interaction combination among 4 SNPs, smoking and alcohol drinking. Logistic regression was performed to investigate association between 4 SNPs within TFPI-2 gene and coronary atherosclerosis risk. Coronary atherosclerosis risk was significantly higher in carriers with the A allele of rs34489123 within TFPI-2 gene than those with GG genotype (GA+AA versus GG), adjusted OR (95% CI) = 1.70 (1.20-2.31), and was also higher in carriers with the G allele of rs4264 within TFPI-2 gene than those with AA genotype (AG+GG versus AA), adjusted OR (95% CI) = 1.62 (1.21-2.11). GMDR model shown the best models for gene-environment interaction were rs34489123 and smoking after adjusting the covariates, which scored 10 out of 10 for cross-validation consistency and 0.0010 for the sign test. Heavy LD was found for SNPs rs34489123 and rs59805398 (D' value was more than 0.8). Compared to control individuals, the AG haplotypes appeared to be significantly associated with increased coronary atherosclerosis risk, OR (95% CI) = 1.73 (1.22-2.32). We found that the A allele of rs34489123 and the G allele of rs4264 within TFPI-2 gene, interaction between rs34489123 and smoking and AG haplotypes were all associated with increased coronary atherosclerosis risk.

Epigenetic Regulation of Vascular Aging and Age-Related Vascular Diseases

Vascular aging refers to the structural and functional defects that occur in the aorta during the aging process and is characterized by increased vascular cell senescence, vascular dyshomeostasis, and vascular remodeling. Vascular aging is a major risk factor for vascular diseases. However, the current understanding of the biological process of vascular aging and age-related diseases is insufficient. Epigenetic regulation can influence gene expression independently of the gene sequence and mainly includes DNA methylation, histone modifications, and RNA-based gene regulation. Epigenetic regulation plays important roles in many physiological and pathophysiological processes and may explain some gaps in our knowledge regarding the interaction between genes and diseases. In this review, we summarize recent advances in the understanding of the epigenetic regulation of vascular aging and age-related diseases in terms of vascular cell senescence, vascular dyshomeostasis, and vascular remodeling. Moreover, the possibility of targeting epigenetic regulation to delay vascular aging and treat age-related vascular diseases is also discussed.

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

BACKGROUND

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

MATERIAL/METHODS

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

RESULTS

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

CONCLUSIONS

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

Conditional knockout of tissue factor pathway inhibitor 2 in vascular endothelial cells accelerates atherosclerotic plaque development in mice

BACKGROUND

Tissue factor pathway inhibitor-2 (TFPI-2) regulates matrix metalloproteinases activation and extracellular matrix degradation. Over-expression of TFPI-2 enhances atherosclerotic plaque stability. The aim of this study is to investigate the effect of conditional knockout (KO) of TFPI-2 in vascular endothelial cells on the initiation and development of atherosclerotic plaque.

METHODS

A Cre/mloxP conditional KO system and Tek-Cre mice were used to generate offsprings with monoallelic deletion of the TFPI-2 gene in endothelial cells. TFPI-2(fl/+)/Tek-Cre mice, TFPI-2(fl/+) mice and ApoE(-/-) mice (n=6 for each group) were included. Arteries were obtained. HE, EVG and anti-α-SMA staining were used to examine the morphology of vessel and plaque. Protein expression and phosphorylation were detected by Western blot or immunohistochemistry.

RESULTS

TFPI-2(fl/+)/Tek-Cre mice were generated. TFPI-2 level decreased to 40.68% in TFPI-2(fl/+)/Tek-Cre group. TFPI-2(fl/+)/Tek-Cre developed plaques when no plaque was found in TFPI-2(fl/+) mice. Compared with ApoE(-/-) group, TFPI-2(fl/+)/Tek-Cre group has smaller plaque area, decreased lipid content and less buried fibrous cap layers. MMP-2 and MMP-9 in TFPI-2(fl/+)/Tek-Cre group was higher than in TFPI-2(fl/+)group. The phosphorylation of PPAR-α and PPAR-γ was decreased in TFPI-2(fl/+)/Tek-Cre group.

CONCLUSIONS

A novel mouse model is presented and can be used to investigate the role of TFPI-2 in the process of atherosclerosis. Our findings suggest that monoallelic deletion of TFPI-2 gene in vascular endothelial cells leads to significant downregulation of TFPI-2. TFPI-2 deficiency may accelerate initiation of atherosclerotic lesion in mice. Elevated MMP-2 and 9 and decreased phosphorylation of PPAR-α and PPAR-γ may contribute to this phenotype.

Tissue Factor Pathway Inhibitor-2 Gene Polymorphisms Associate With Coronary Atherosclerosis in Chinese Population

Tissue factor pathway inhibitor-2 (TFPI-2) may play critical roles in the pathogenesis of atherosclerosis. In this study, we aimed to investigate the association between TFPI-2 gene polymorphisms and coronary atherosclerosis.Four hundred and seven patients with coronary atherosclerosis and 306 individuals with normal coronary artery were enrolled in the present study. Nine single-nucleotide polymorphisms (SNPs) (rs3763473, rs59805398, rs60215632, rs59999573, rs59740167, rs34489123, rs4517, rs4264, and rs4271) were detected with polymerase chain reaction-direct sequencing method. Severity of coronary atherosclerosis was assessed by Gensini score. After the baseline investigation, patients with coronary atherosclerosis were followed up for incidence of cardiovascular events (CVEs).Eight SNPs were in accordance with the Hardy-Weinberg equilibrium, and 8 haplotypes were constructed based on rs59999573, rs59740167, and rs34489123 after linkage disequilibrium and haplotype analysis. Two SNPs (rs59805398 and rs34489123) and 5 haplotypes correlated with coronary atherosclerosis even after adjustment by Gensini score. At follow-up (median 53 months, range 1-60 months), 85 patients experienced CVE. However, there was no strong association between the gene polymorphisms and the occurrence of CVE.Tissue factor pathway inhibitor-2 gene polymorphisms were associated with coronary atherosclerosis in the Chinese population, suggesting that the information about TFPI-2 gene polymorphisms was useful for assessing the risk of developing coronary atherosclerosis, but there was not enough evidence showing it could predict occurrence of CVE.

M1 and M2 macrophage proteolytic and angiogenic profile analysis in atherosclerotic patients reveals a distinctive profile in type 2 diabetes

This study aimed to investigate atherosclerotic mediators' expression levels in M1 and M2 macrophages and to focus on the influence of diabetes on M1/M2 profiles. Macrophages from 36 atherosclerotic patients (19 diabetics and 17 non-diabetics) were cultured with interleukin-1β (IL-1β) or IL-4 to induce M1 or M2 phenotype, respectively. The atherosclerotic mediators' expression was evaluated by quantitative reverse transcription-polymerase chain reaction (RT-PCR). The results showed that M1 and M2 macrophages differentially expressed mediators involved in proteolysis and angiogenesis processes. The proteolytic balance (matrix metalloproteinase-9 (MMP-9)/tissue inhibitor of metalloproteinase-1 (TIMP-1), MMP-9/plasminogen activator inhibitor-1 (PAI-1) and MMP-9/tissue factor pathway inhibitor-2 (TFPI-2) ratios) was higher in M1 versus M2, whereas M2 macrophages presented higher angiogenesis properties (increased vascular endothelial growth factor/TFPI-2 and tissue factor/TFPI-2 ratios). Moreover, M1 macrophages from diabetics displayed more important proangiogenic and proteolytic activities than non-diabetics. This study reveals that M1 and M2 macrophages could differentially modulate major atherosclerosis-related pathological processes. Moreover, M1 macrophages from diabetics display a deleterious phenotype that could explain the higher plaque vulnerability observed in these subjects.

A comparison of genome-wide DNA methylation patterns between different vascular tissues from patients with coronary heart disease

Epigenetic mechanisms of gene regulation in context of cardiovascular diseases are of considerable interest. So far, our current knowledge of the DNA methylation profiles for atherosclerosis affected and healthy human vascular tissues is still limited. Using the Illumina Infinium Human Methylation27 BeadChip, we performed a genome-wide analysis of DNA methylation in right coronary artery in the area of advanced atherosclerotic plaques, atherosclerotic-resistant internal mammary arteries, and great saphenous veins obtained from same patients with coronary heart disease. The resulting DNA methylation patterns were markedly different between all the vascular tissues. The genes hypomethylated in athero-prone arteries to compare with atherosclerotic-resistant arteries were predominately involved in regulation of inflammation and immune processes, as well as development. The great saphenous veins exhibited an increase of the DNA methylation age in comparison to the internal mammary arteries. Gene ontology analysis for genes harboring hypermethylated CpG-sites in veins revealed the enrichment for biological processes associated with the development. Four CpG-sites located within the MIR10B gene sequence and about 1 kb upstream of the HOXD4 gene were also confirmed as hypomethylated in the independent dataset of the right coronary arteries in the area of advanced atherosclerotic plaques in comparison with the other vascular tissues. The DNA methylation differences observed in vascular tissues of patients with coronary heart disease can provide new insights into the mechanisms underlying the development of pathology and explanation for the difference in graft patency after coronary artery bypass grafting surgery.

Epigenetic reprogramming in atherosclerosis

Recent data support the involvement of epigenetic alterations in the pathogenesis of atherosclerosis. The most widely investigated epigenetic mechanism is DNA methylation although also histone code changes occur during the diverse steps of atherosclerosis, such as endothelial cell proliferation, vascular smooth muscle cell (SMC) differentiation, and inflammatory pathway activation. In this review, we focus on the main genes that are epigenetically modified during the atherogenic process, particularly nitric oxide synthase (NOS), estrogen receptors (ERs), collagen type XV alpha 1 (COL15A1), vascular endothelial growth factor receptor (VEGFR), and ten-eleven translocation (TET), which are involved in endothelial dysfunction; gamma interferon (IFN-γ), forkhead box p3 (FOXP3), and tumor necrosis factor-α (TNF-α), associated with atherosclerotic inflammatory process; and p66shc, lectin-like oxLDL receptor (LOX1), and apolipoprotein E (APOE) genes, which are regulated by high cholesterol and homocysteine (Hcy) levels. Furthermore, we also discuss the role of non-coding RNAs (ncRNA) in atherosclerosis. NcRNAs are involved in epigenetic regulation of endothelial function, SMC proliferation, cholesterol synthesis, lipid metabolism, and inflammatory response.

Risk-Association of DNMT1 Gene Polymorphisms with Coronary Artery Disease in Chinese Han Population

Recently, a significant epigenetic component in the pathogenesis of Coronary Artery Disease (CAD) has been realized. Here, we evaluated the possible association of candidate Single Nucleotide Polymorphisms (SNPs) in the epigenetic-regulatory gene, DNA methyltransferase 1 (DNMT1), with CAD in Chinese Han population. Five tag SNPs (rs16999593, rs2336691, rs2228611, rs4804494, rs7253062) were analyzed by High Resolution Melt (HRM) method in 476 CAD patients and 478 controls. Overall, there were significant differences in the genotype and allele distributions of rs2228611 and rs2336691, between patients and controls. The minor A allele of rs2228611 was associated with a lower risk of CAD (p = 0.034); modest effect in the additive analysis but also marginal significance was found in the recessive model [ORadditive = 0.404 (0.184, 0.884), p = 0.023 and ORrecessive = 0.452 (0.213, 0.963), p = 0.040] after adjusting for confounders. While the rs2336691 A allele were associated with a higher risk of developing CAD (p = 0.037); borderline significant association in both additive and dominant models [ORadditive = 1.632 (1.030, 2.583), p = 0.037 and ORdominant = 1.599 (1.020, 2.507), p = 0.040]. In conclusion, these data provide the first evidence that occurrence of CAD may be moderated by genetic variation in the gene involved in the epigenetic machinery.

Arteriovenous fistula failure: is there a role for epigenetic regulation?

Epigenetics is the study of heritable changes in gene expression or cellular phenotype that occur without alterations in the DNA sequence. In the past decade, epigenetics has been identified as a key regulator of gene expression and therefore is likely to play a major role in multiple disease processes. More importantly, we now recognize epigenetics to be a sensitive, dynamic, and reversible process that has opened the door to multiple novel diagnostic, prognostic, and therapeutic strategies for human diseases. The focus of this review, however, is to explore the potential role of epigenetics in arteriovenous fistula (AVF) maturation. AVF maturation failure is currently the single most important cause of dialysis vascular access dysfunction and most important is the result of a peri-anastomotic stenosis thought to be caused by a combination of neointimal hyperplasia and inadequate outward remodeling. At a pathogenetic level, however, AVF maturation failure is likely the end result of the interaction between hemodynamic stressors (injury) and the vascular response to these stressors; the latter being influenced by uremia, oxidative stress, and inflammation. Interestingly, these same factors (hemodynamic shear stress, oxidative stress, inflammation, and uremia) are also important mediators of epigenetic modifications. We therefore believe that epigenetic factors potentially could play an important role in the pathogenesis of AVF maturation failure. The current review therefore tries to unravel some of these critical biological connections, with an emphasis on the future development of epigenetic-based diagnostic and therapeutic strategies for AVF maturation failure (a clinical problem for which there are currently no effective therapeutic interventions).

Pregnancy complicated by obesity induces global transcript expression alterations in visceral and subcutaneous fat

Maternal obesity is a significant risk factor for development of both maternal and fetal metabolic complications. Increase in visceral fat and insulin resistance is a metabolic hallmark of pregnancy, yet not much is known how obesity alters adipose cellular function and how this may contribute to pregnancy morbidities. We sought to identify alterations in genome-wide transcription expression in both visceral (omental) and abdominal subcutaneous fat deposits in pregnancy complicated by obesity. Visceral and abdominal subcutaneous fat deposits were collected from normal weight and obese pregnant women (n = 4/group) at the time of scheduled uncomplicated cesarean section. A genome-wide expression array (Affymetrix Human Exon 1.0 st platform), validated by quantitative real-time PCR, was utilized to establish the gene transcript expression profile in both visceral and abdominal subcutaneous fat in normal weight and obese pregnant women. Global alteration in gene expression was identified in pregnancy complicated by obesity. These regions of variations led to identification of indolethylamine N-methyltransferase, tissue factor pathway inhibitor-2, and ephrin type-B receptor 6, not previously associated with fat metabolism during pregnancy. In addition, subcutaneous fat of obese pregnant women demonstrated increased coding protein transcripts associated with apoptosis as compared to lean counterparts. Global alteration of gene expression in adipose tissue may contribute to adverse pregnancy outcomes associated with obesity.

Methylation of FOXP3 in regulatory T cells is related to the severity of coronary artery disease

OBJECTIVES

Regulatory T (Treg) cells have been shown to play a protective role in experimental atherosclerosis. However, it is unclear whether Tregs can protect from rupture of vulnerable plaque in patients with atherosclerosis. Demethylation of the DNA encoding the transcription factor forkhead box P3 (FOXP3) was found to be essential for the stable maintenance of the suppressive properties of Tregs. We aimed to evaluate Treg levels in patients with acute coronary syndrome (ACS) using a method based on Treg-specific DNA demethylation within the FOXP3 gene.

METHODS AND RESULTS

Peripheral blood was collected to determine Treg levels by PCR-based DNA methylation analysis. We found that Treg levels were decreased in patients with ACS compared with normal coronary controls. The decrease in Tregs was associated with the severity of the ACS. Furthermore, up-regulation of DNA-methyltransferases was detected in CD4(+)CD25(+) Tregs obtained from ACS patients as compared to those from normal coronary controls. A dose-dependent increase in the methylation of the Treg-specific demethylated region in FOXP3 was observed in cultures of PBMCs with ox-LDL. Moreover, the ox-LDL-induced Treg effects could be restored by loading (-)-epigallocatechin-3-gallate, a methyltransferase inhibitor. Treatment of CD4(+)CD25(+) Tregs with ox-LDL resulted in a 41% increase in the methylation of FOXP3, a 66% of reduction in FOXP3 mRNA expression, and an increase in the expression of DNA methyltransferase 3a as well as 3b.

CONCLUSIONS

Our data demonstrate that reduction in Treg cells is associated with ACS in atherosclerotic patients. Epigenetic suppression of FOXP3 might lead to down-regulation of Treg cells, and in turn increase the risk of ACS.

Clinical relevance of epigenetic dysregulation in chronic kidney disease-associated cardiovascular disease

Across the spectrum of clinical medicine, the field of epigenetics has gained substantial scientific interest in recent years. Epigenetics refers to modifications in gene expression which are not explained by changes in DNA sequence. Classical components of epigenetic regulation comprise DNA methylation, histone modifications and RNA interference. In chronic kidney disease (CKD), several features of uraemia, such as hyperhomocysteinemia and inflammation, may contribute to changes in epigenetic gene regulation. It has been suggested that these changes may affect genes related to cardiovascular disease. Thereby, a uraemia-associated disturbance in epigenetic regulation may contribute to the substantial increase in cardiovascular morbidity in CKD patients. The present review aims to summarize current knowledge of epigenetic dysregulation in cardiovascular disease from a nephrological perspective, with a special focus on DNA methylation. We first describe the impact of altered epigenetic regulation in non-CKD-associated arteriosclerosis, and next characterize uraemic features which may affect epigenetic gene regulation in the context of cardiovascular disease. Finally, we conclude that substantial additional work is needed before epigenetic regulatory mechanisms may become therapeutic targets in CKD-associated cardiovascular disease.

Epigenetics: a tool to understand diet-related cardiovascular risk?

Cardiovascular disease (CVD) is a leading cause of mortality and is projected to hold its grim record as developing countries increase their wealth. Since specific nutritional habits are important risk factors for CVD, it is imperative to understand how ingredients of risk-associated diets convert a healthy cellular transcriptional program into a pathological one. Epigenetics has enriched our view of the genome by showing that DNA-associated regulatory proteins and RNAs, together with chemical modifications of the DNA itself, determine which parts of the DNA chain are transcribed or silent in a given phase of a cell's life. This complex biological entity--the epigenome--accounts for the enormous phenotypic diversity within a multicellular organism despite its unicellular origin. Crucially, the epigenome can be modified by diet and other exogenous factors, thus suggesting that epigenetic mechanisms might underlie pathological responses to CVD risk factors. Here, we will review the current knowledge of epigenetic mechanisms in diet-gene interactions and propose ways in which epigenetics might clarify the impact of genetic variants on CVD risk.

Circulating monocytes mirror the imbalance in TF and TFPI expression in carotid atherosclerotic plaques with lipid-rich and calcified morphology

BACKGROUND

Thrombogenicity of atherosclerotic plaque largely depends on plaque morphology and their content of tissue factor (TF) and tissue factor pathway inhibitor (TFPI). The relationship between morphological composition of plaque (lipid-rich or calcified) and expression of TF and TFPI in circulating blood monocytes and within the plaques is not characterized.

OBJECTIVE

To investigate whether lipid-rich (echolucent) or calcified (echogenic) morphology of carotid atherosclerotic plaques is associated with differences in TF and TFPI expression in circulating blood monocytes and within carotid atherosclerotic plaques.

METHODS

We studied levels of monocyte TF and TFPI mRNA and protein expression and association with traditional risk factors for atherosclerosis in asymptomatic subjects with echolucent (n=20) or echogenic (n=20) carotid plaques, or controls without carotid atherosclerosis (n=20) determined by ultrasonography. Sections of calcified or lipid-rich carotid plaques obtained from symptomatic patients were assessed for TF and TFPI antigen expression.

RESULTS

TF and TFPI surface presentation, surface TF/TFPI ratio, and TF activity were higher in monocytes obtained from subjects with echolucent than with echogenic plaques or controls without carotid atherosclerosis. Multiple regression analyses revealed inverse association between serum apoA1 and monocyte surface TF antigen expression (p=0.007), and positive association between serum apoB and monocyte surface TFPI expression (p=0.028). Sections from lipid-rich carotid plaques contained 2.5-fold more TF and 1.5-fold more TFPI antigens relative to calcified lesions, also yielding a higher TF/TFPI ratio.

CONCLUSIONS

Our findings indicate that circulating monocytes of asymptomatic individuals with echolucent lipid-rich carotid atherosclerosis express an imbalance between TF and TFPI expression cohering with changes found within advanced carotid atherosclerotic plaques obtained from symptomatic patients.

Tissue factor pathway inhibitor 2 is induced by thrombin in human macrophages

Tissue factor pathway inhibitor 2 (TFPI2) is a serine protease inhibitor critical for the regulation of extracellular matrix remodeling and atherosclerotic plaque stability. Previously, we demonstrated that TFPI2 expression is increased in monocytes from patients with familial combined hyperlipidemia (FCH). To gain insight into the molecular mechanisms responsible for this upregulation, we examined TFPI2 expression in THP-1 macrophages exposed to lipoproteins and thrombin. Our results showed that TFPI2 expression was not affected by treatment with very low density lipoproteins (VLDL), but was induced by thrombin (10 U/ml) in THP-1 (1.9-fold increase, p<0.001) and human monocyte-derived macrophages (2.3-fold increase, p<0.005). The specificity of the inductive effect was demonstrated by preincubation with the thrombin inhibitors hirudin and PPACK, which ablated thrombin effects. TFPI2 induction was prevented by pre-incubation with MEK1/2 and JNK inhibitors, but not by the EGF receptor antagonist AG1478. In the presence of parthenolide, an inhibitor of NFκB, but not of SR-11302, a selective AP-1 inhibitor, thrombin-mediated TFPI2 induction was blunted. Our results also show that thrombin treatment increased ERK1/2, JNK and IκBα phosphorylation. Finally, we ruled out the possibility that TFPI2 induction by thrombin was mediated by COX-2, as preincubation with a selective COX-2 inhibitor did not prevent the inductive effect. In conclusion, thrombin induces TFPI2 expression by a mechanism involving ERK1/2 and JNK phosphorylation, leading finally to NFkB activation. In the context of atherosclerosis, thrombin-induced macrophage TFPI2 expression could represent a means of avoiding excessive activation of matrix metalloproteases at sites of inflammation.

Tissue factor pathway inhibitor-2 is downregulated by ox-LDL and inhibits ox-LDL induced vascular smooth muscle cells proliferation and migration

INTRODUCTION

Tissue factor pathway inhibitor-2 (TFPI-2) is a member of the Kunitz-type family of serine protease inhibitors, which inhibits several matrix metalloproteinases activity involved in extracellular matrix degradation. Studies have shown low TFPI-2 expression in the shoulder regions of atherosclerotic plaques. But studies evaluating its role in the progression of atherosclerotic plaque are scarce. Vascular smooth muscle cells (VSMCs) are important components of atherosclerotic plaques and oxidized low density lipoprotein (ox-LDL) is an important detrimental factor of atherosclerosis. The aim of this study is to elucidate the effect of TFPI-2 on smooth muscle cell proliferation and migration induced by ox-LDL.

METHODS

Retroviruses expressing human TFPI-2 were constructed. Cell proliferation was determined by CCK-8 assay. Cell apoptosis was analyzed by double staining of FITC-Annexin V and propidium iodide. Cell migration was studied through a Transwell chamber and with a scratch-wound assay. The matrix metalloproteinase-2 and -9 activities were analyzed by gelatin zymography. Phosphorylation of FAK was analyzed by western blot.

RESULTS

TFPI-2 over-expression of mRNA and protein was confirmed in infected cells. CCK-8 assay showed that TFPI-2 inhibit VSMCs proliferation induced by ox-LDL while without cytotoxicity to VSMCs. Transwell and scratch wound assay confirmed TFPI-2 over-expression can inhibit VSMC migration. Zymography assay showed that TFPI-2 can inhibit MMP-2, 9 activity induced by ox-LDL. Western blot assay showed TFPI-2 can inhibit cyclinD1 expression and FAK phosphorylation.

CONCLUSION

TFPI-2 over-expression may strongly inhibit the proliferation and migration of VSMCs and suppresses MMP-2, 9 activity induced by ox-LDL, making it a promising candidate for treatment of atherosclerotic process.