ABCA1, TCF7, NFATC1, PRKCZ and PDGFA DNA methylation as potential epigenetic-sensitive targets in acute coronary syndrome via network analysis

Background

Acute coronary syndrome (ACS) is the most severe clinical manifestation of coronary heart disease and the leading cause of death worldwide.

Purpose

To perform an epigenome-wide analysis in circulating CD4+ and CD8+ T cells of ACS patients and healthy subjects (HS) enrolled in the DIANA clinical trial (NCT04371809) in order to identify differentially methylated genes (DMGs).

Methods

Genomic DNA was extracted from CD4+ and CD8+ T cells of all subjects and sequenced by the reduced representation bisulfite sequencing (RRBS) platform. Functional pathway analysis was performed and significant DMGs were selected for gene expression validation by qRT-PCR in ACS patients and HS. GeneMANIA was used to built a prediction gene network. Correlation analyses between molecular data and clinical variables were performed.

Results

In CD4+ T cells we identified 61 differentially methylated regions (DMRs) associated to 57 annotated genes of which 53% (n=32) were hyper- and 47% (n=29) were hypo-methylated in ACS patients vs HS. In CD8+ T cells we identified 613 DMRs associated to 569 annotated genes of which 28% (n=173) were hyper- and 72% (n=440) were hypo-methylated between two groups. In both cell type of ACS patients, 175 DMRs were associated to 157 annotated genes of which 41% (n=72) were hyper- and 59% (n=103) were hypo-methylated. From functional analysis, we selected the top 5 DMGs in the prevalent pathways with the highest differential of methylation values. Specifically, we considered 6 hub genes: NFATC1, TCF7, PDGFA, PRKCB, PRKCZ and ABCA1 and determined their respective expression levels by q-RT-PCR. We found a significant up-regulation of the selected genes in ACS patients vs HS (P<0.001 for all comparisons). Correlation analysis showed both common and cell specific correlation patterns. In CD4+ T cells, PDGFA promoter methylation was negatively correlated with CK-MB concentrations (r=−0.79, P=0.018). ABCA1, TCF7, PDGFA and PRKCZ gene expression was positively associated to CK-MB concentrations (r=0.75, P=0.03; r=0.760, P=0.029; r=0.72, P=0.044; r=0.74, P=0.035, respectively).

Conlusions

This study is the first single-base resolution map of DNA methylome by RRBS in CD4+ and CD8+ T cells, providing specific methylation signatures that could help to clarify the role of aberrant methylation in ACS pathogenesis, and provide the basis for the search of novel epigenetic-sensitive biomarkers in the prevention and early diagnosis of this pathology.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Italian Ministry of Health;Italian Ministry of Research and University

Integrated analysis of DNA methylation profile in HLA-G gene and imaging in coronary heart disease

Aims

Immune endothelial inflammation, underlie coronary heart disease (CHD) related phenotypes, could provide new insight into the pathobiology of the disease. We investigated DNA methylation level of the unique CpG island of HLA-G gene in CHD patients and evaluated the correlation with cardiac computed tomography angiography (CCTA) features.

Methods

Thirty-two patients that underwent CCTA for suspected CHD were enrolled for this study. Obstructive CHD group included fourteen patients, in which there was a stenosis greater than or equal to 50% in one or more of the major coronary arteries detected; whereas subjects with Calcium (Ca) Score=0, uninjured coronaries and with no obstructive CHD were considered as control subjects (Ctrls) (n=18). For both groups, DNA methylation profile of the whole 5'UTR-CpG island of HLA-G was measured. The plasma soluble HLA-G (sHLA-G) levels were detected in all subjects by specific ELISA assay. Statistical analysis was performed using R software.

Results

For the first time, our study reported that 1) a significant hypomethylation characterized three specific fragments (B, C and F) of the 5'UTR-CpG island (p=0.05) of HLA-G gene in CHD patients compared to Ctrl group; 2) hypomethylation level of one specific fragment positively correlated with coronary Ca score, a relevant parameter of CCTA (p<0.05) between two groups.

Conclusions

Our results showed that reduced levels of circulating HLA-G molecules could derive from epigenetic marks inducing hypomethylation of specific regions into 5'UTR-CpG island of HLA-G gene in CHD patients with obstructive coronary stenosis vs non critical stenosis group.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Italian Minister of Health

P6431Association of circulating miR-765, miR-93-5p and miR-433-3p with obstructive coronary heart disease evaluated by cardiac computed tomography

Background

Although advances in diagnosis, treatment and prognosis, coronary heart disease (CHD) is still the most prevalent cause of mortality and morbidity worldwide. Thus, there is still the need to identify both novel diagnostic and prognostic biomarkers to improve the clinical decision-making and help to stratify patients for early preventive treatment. Epigenetic-sensitive mechanisms may be related both to pathogenesis and prognosis of CHD. Among the epigenetic hallmarks, microRNAs (miRNAs), acting as flexible modulators of gene expression, could represent attractive candidate biomarkers useful in clinical practice.

Purpose

We prospectively investigated the expression pattern of circulating miRNAs in patients undergoing Cardiac Computed Tomography (CCT) for suspected CHD (n=95) with the aim to integrate molecular findings with morphological and clinical parameters derived by CCT.

Methods

CCT was performed with a third-generation dual source multidetector computed tomography scanner. Peripheral venous blood samples were collected into EDTA after a 12 h fasting in the same day of CCT, before imaging execution and the levels of 42 selected plasmatic miRNAs were analyzed by qRT-PCR.

Results

Let-7c-5p, miR-765, miR-483-5p, miR-31-5p and miR-206 were upregulated in CHD patients (n=66) vs healthy subjects HS (n=29) as well as let-7c-5p, miR-765, miR- 483-5p showed higher expression in obstructive CHD (n=36) compared to no obstructive CHD patients (n=66). In addition, miR-93-5p and miR-433-3p showed an upregulation in patients with critical coronary stenosis. Multivariate regression analysis demonstrated that miR-765, miR-31-5p and miR-206 were independently associated with CHD also in combination with Framingham risk score. Relevantly, miR-765, miR-93-5p and miR-433-3p were obstructive CHD predictors. ROC curve analysis also revealed a good performance for miR-765, miR-93-5p and miR-433-3p on predicting CHD severity.

Circulating microRNA expression

Conclusions

Our study represents a combined epigenetic/imaging approach useful to support the diagnosis and prediction of CHD.

Acknowledgement/Funding

Italian Ministry of Health grants: “Giovani Ricercatori 2011-12” (project code GR-2011-02349436) and “Ricerca Corrente 2018”

P1514Evaluation of endothelial progenitor cells as cardiovascular prognostic biomarkers in hemodialysis patients

Background

Endothelial cells arise from endothelial progenitor cells (EPCs), which reside in bone marrow vascular niches, and are classified according to specific functional differences. Oxidative stress and inflammation lead to endothelial dysfunction that is a critical event in the initiation and progression of atherosclerotic plaques. Patients with chronic renal failure frequently show endothelial dysfunction and are at a greatly increased risk of developing atherosclerosis. Owing to their ability to partially restore vascular damage, both the number and functional changes in EPCs may be considered as useful prognostic biomarkers of cardiovascular events in hemodialysis (HD) patients.

Purpose

This study investigated EPC features and several biomarkers of systemic vascular inflammation and carotid atherogenesis in hemodialysis (HD) patients.

Methods

We studied 104 HD patients (males=55 and females 49, mean age: 51±12 years) and 40 healthy controls (males=20/females=20; mean age: 52±11 years). Isolated EPCs were cultured in the fibronectin-covered culture dishes and counted. EPC markers were studied by flow cytometry (FACS) by using anti-CD34, anti-CD133 and anti-vascular endothelial growth factor receptor 2 (VEGFR-2) antibodies. Serum levels of intercellular cell adhesion molecule (ICAM), vascular cell adhesion molecule (VCAM), IL-6, TNF-α, and asymmetric dimethyl-arginine (ADMA) were measured by ELISA method. Carotid intima-media thickness (CIMT) and ratio (CIMR) were also evaluated.

Results

In our experimental conditions, EPC number was decreased in HD patients when compared to controls (p<0.01). Expression of CD34 was significantly lower in the HD group (p<0.01). Interestingly, EPCs were significantly inversely correlated with serum TNF-α levels in HD patients (r=−0.388, p<0.01) but not in the control group (r=−0.133, p=NS). Furthermore, there was an inverse association between VEGFR-2 positive cells and serum TNF α levels (r=−0.401, p=0.002) in HD patients. In HD patients, there was a positive correlation between ICAM levels with CIMT (r=0.405, p=0.03) and CIMR was positively correlated with VCAM levels (r=0.377, p=0.01) and ADMA (r=0.233, p<0.05).

Conclusions

Our study shows that EPC number was decreased in HD patients and it was associated with systemic inflammation. TNF-α could activate inhibitory actions on EPC in HD patients. A significant relationship was present between ICAM/VCAM and carotid atherosclerosis, while this was not evident with EPC number. These pathogenic mechanisms can contribute to the high incidence of cardiovascular diseases in HD patients. However, further larger studies should investigate this working hypothesis.