Vincenzo Grimaldi

High glucose downregulates endothelial progenitor cell number via SIRT1

Increasing evidence indicates that mammalian SIRT1 mediates calorie restriction and influences lifespan regulating a number of biological molecules such as FoxO1. SIRT1 controls the angiogenic activity of endothelial cells via deacetylation of FoxO1. Endothelial dysfunction and reduced new blood vessel growth in diabetes involve a decreased bioactivity of endothelial progenitor cells (EPCs) via repression of FoxO1 transcriptional activity. The relative contribution of SIRT1 with respect to the direct effects of high glucose on EPC number is poorly understood. We report that treatment of EPCs with high glucose for 3 days determined a consistent downregulation of EPC positive to DiLDL/lectin staining and, interestingly, this was associated with reduced SIRT1 expression levels and enzyme activity, and increased acetyl-FoxO1 expression levels. Moreover, EPCs responded to high glucose with major changes in the expression levels of cell metabolism-, cell cycle-, and oxidative stress-related genes or proteins. Proteomic analysis shows increased expression of nicotinamide phosphoribosyl transferase and mitochondrial superoxide dismutase whereas a glucose-related heat shock protein is reduced. These findings show that SIRT1 is a critical modulator of EPCs dysfunction during alteration of glucose metabolism.

Epigenetic control of autoimmune diseases: from bench to bedside.

Genome-wide association studies have revealed several genes predisposing to autoimmunity, however, concordance rates in monozygotic twins are significantly below 50% for several autoimmune diseases. The limited presence of a strong genetic association only in some patients supports that other non-genetic mechanisms are active in these pathologies. Epigenetic modifications such as DNA methylation, histone modification, and microRNA signaling regulate gene expression and are sensitive to external stimuli and they might be as bridging between genetic and environmental factors. Some evidence has highlighted the involvement of epigenetic alterations in the pathogenesis of various autoimmune diseases giving rise to great expectations among clinicians and researchers. The direct role of these alterations in the initiation/progression of autoimmune diseases is still unclear. The knowledge in depth of these pathogenic and epigenetic mechanisms will increase the possibility of the control and/or prevention of autoimmune diseases through the use of drugs that target epigenetic pathways. Moreover, we could use epigenetic-related biomarkers to follow this complicated framework (for example H3K4me3 and miRNA-155 are among those proposed biomarkers). This article reviews current understanding of the epigenetic involvement in the field of autoimmune diseases especially in systemic lupus erythematosus, rheumatoid arthritis, sclerosis multiple and type 1 diabetes.

Epigenetic-related therapeutic challenges in cardiovascular disease

Progress in human genetic and genomic research has led to the identification of genetic variants associated with specific cardiovascular diseases (CVDs), but the pathogenic mechanisms remain unclear. Recent studies have analyzed the involvement of epigenetic mechanisms such as DNA methylation and histone modifications in the development and progression of CVD. Preliminary work has investigated the correlations between DNA methylation, histone modifications, and RNA-based mechanisms with CVDs including atherosclerosis, heart failure (HF), myocardial infarction (MI), and cardiac hypertrophy. Remarkably, both in utero programming and postnatal hypercholesterolemia may affect the epigenetic signature in the human cardiovascular system, thereby providing novel early epigenetic-related pharmacological insights. Interestingly, some dietary compounds, including polyphenols, cocoa, and folic acid, can modulate DNA methylation status, whereas statins may promote epigenetic-based control in CVD prevention through histone modifications. We review recent findings on the epigenetic control of cardiovascular system and new challenges for therapeutic strategies in CVDs.

Functional impairment of hematopoietic progenitor cells in patients with coronary heart disease

The circulating form of endothelial progenitors cells (EPCs) are derivated from bone marrow (BM)‐derived hematopoietic stem cells (HSCs). Enhanced mobilization of EPCs was shown to be linked to cardiac diseases. This study investigated whether reduced EPC levels in advanced coronary heart disease (CHD) are secondary to a functional exhaustion of HSCs in the BM or to reduced mobilization. Number and functional properties of EPCs were assessed in 15 healthy controls, and 40 patients with CHD. The colony‐forming unit (CFU) capacity of BM‐derived mononuclear cells and the CD34+ HSC number were examined in four healthy volunteers, and 15 CHD patients. EPC number was reduced in CHD patients (P < 0.01 vs. controls). Moreover, the migratory capacity was significantly impaired in EPCs of CHD patients (P < 0.05 vs. controls). On multivariate analysis, CHD was an independent predictor of functional EPC impairment. CFUs were reduced in CHD patients (59.6 ± 21.2 vs. 75.4 ± 25.8 in controls, P < 0.05). CHD was also predictor of impaired CFU capacity. In this small clinical study, CHD is associated with selective impairment of HSC function in the BM and in the peripheral blood, which may contribute to impairment of cardiac function.

Antioxidants increase number of progenitor endothelial cells through multiple gene expression pathways

To date, there is no report on the effect of antioxidants on endothelial progenitor cells (EPCs). This study shows that in vitro incubation of EPCs with vitamin C and E reverted the already well documented lowering effect of TNF-α on EPC number and increased p-p38 expression levels. In order to document major changes of gene expression levels and gain insight into signalling pathways, microarray analysis was performed and a significant variation of the expression of 5389 genes in EPCs following antioxidant treatment was detected. Also in vivo evidence is provided about the positive effect of antioxidant vitamins on EPCs, since vitamin C and E supplementation potentiated the physical training-induced increase of EPC number and VEGF levels. Together, these data indicate that antioxidant treatment ameliorates EPC number and causes major changes of gene expression within these cells in vitro. Furthermore, concomitant antioxidant supplementation and physical training in vivo raised the levels of circulating EPCs and serum VEGF more than physical training alone.

Effect of red wine antioxidants and minor polyphenolic constituents on endothelial progenitor cells after physical training in mice

Circulating endothelial progenitor cells (EPCs) play a significant role in regeneration of damaged blood vessels. Levels and functional activities of EPCs are noticeable altered by risk factors for coronary heart disease (CHD) and compounds that can prevent or ameliorate EPC dysfunction are currently of special clinical interest. Here, we evaluate the effects of red wine (RW) on EPCs in C57BL/6J mice subjected to physical exercise. FACS computed counting showed a significant increase of EPC number (P<0.05) in mice after short-term supplementation with RW. VEGF serum concentration was significantly increased by physical training in the presence or absence of RW supplementation (P<0.001). These in vivo observations support previous in vitro observation of the beneficial effect of RW in the modulation of EPC levels.

Detrimental effects of Bartonella henselae are counteracted by L-arginine and nitric oxide in human endothelial progenitor cells.

The recruitment of circulating endothelial progenitor cells (EPCs) might have a beneficial effect on the clinical course of several diseases. Endothelial damage and detachment of endothelial cells are known to occur in infection, tissue ischemia, and sepsis. These detrimental effects in EPCs are unknown. Here we elucidated whether human EPCs internalize Bartonella henselae constituting a circulating niche of the pathogen. B. henselae invades EPCs as shown by gentamicin protection assays and transmission electron microscopy (TEM). Dil-Ac-LDL/lectin double immunostaining and fluorescence-activated cell sorting (FACS) analysis of EPCs revealed EPC bioactivity after infection with B. henselae. Nitric oxide (NO) and its precursor l-arginine (l-arg) exert a plethora of beneficial effects on vascular function and modulation of immune response. Therefore, we tested also the hypothesis that l-arg (1–30 mM) would affect the infection of B. henselae or tumor necrosis factor (TNF) in EPCs. Our data provide evidence that l-arg counteracts detrimental effects induced by TNF or Bartonella infections via NO (confirmed by DETA-NO and L-NMMA experiments) and by modulation of p38 kinase phosphorylation. Microarray analysis indicated several genes involved in immune response were differentially expressed in Bartonella-infected EPCs, whereas these genes returned in steady state when cells were exposed to sustained doses of l-arg. This mechanism may have broad therapeutic applications in tissue ischemia, angiogenesis, immune response, and sepsis.

Identification of valid reference housekeeping genes for gene expression analysis in tumor neovascularization studies

IntroductionReal time RT-PCR is a widely used technique to evaluate and confirm gene expression data obtained in different cell systems and experimental conditions. However, there are many conflicting reports about the same gene or sets of gene expression. A common method is to report the interest gene expression relative to an internal control, usually a housekeeping gene (HKG), which should be constant in cells independently of experimental conditions.Materials and MethodsIn this study, the expression stability of ten HKGs was considered in parallel in two cell systems (endothelial and osteosarcoma cells): beta actin (ACTB), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), TATA box binding protein (TBP), hypoxanthine phosphoribosyl-transferase 1 (HPRT1), Cyclophilin A (PPIA), beta-2-microglobulin (B2M), glucuronidase beta (GUSB), eukaryotic translation elongation factor 1 alpha1 (EEF1A1), transferrin receptor (TFRC), ribosomal protein S18 (RPS18). In order to study the stability of candidate reference genes, data have been also analyzed by several algorithms (geNorm, NormFinder, BestKeeper and delta-Ct method).Results and Conclusions The overall analysis obtained by the comprehensive ranking showed that RPS18 and PPIA are appropriate internal reference genes for tumor neovascularization studies where it is necessary to analyze both systems at the same time.

Novel epigenetic-based therapies useful in cardiovascular medicine.

Epigenetic modifications include DNA methylation, histone modifications, and microRNA. Gene alterations have been found to be associated with cardiovascular diseases, and epigenetic mechanisms are continuously being studied to find new useful strategies for the clinical management of afflicted patients. Numerous cardiovascular disorders are characterized by the abnormal methylation of CpG islands and so specific drugs that could inhibit DNA methyltransferase directly or by reducing its gene expression (e.g., hydralazine and procainamide) are currently under investigation. The anti-proliferative and anti-inflammatory properties of histone deacetylase inhibitors and their cardio-protective effects have been confirmed in preclinical studies. Furthermore, the regulation of the expression of microRNA targets through pharmacological tools is still under development. Indeed, large controlled trials are required to establish whether current possible candidate antisense microRNAs could offer better therapeutic benefits in clinical practice. Here, we updated therapeutic properties, side effects, and feasibility of emerging epigenetic-based strategies in cardiovascular diseases by highlighting specific problematic issues that still affect the development of large scale novel therapeutic protocols.

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.