Angiogenesis, thrombogenesis, endothelial dysfunction and angiographic severity of coronary artery disease

Angiogenic ability of human endothelial cells was decreased following senescence induction with hydrogen peroxide: possible role of vegfr-2/akt-1 signaling pathway

Background

Many attempts are used to discover mechanisms driving impaired angiogenesis in age-related diseases. Angiogenesis is highly regulated by different signaling pathways. Here, we investigated the angiogenesis potential of human endothelial cells (ECs) upon exposure to hydrogen peroxide (H2O2), a cellular senescent factor.

Results

Data showed that the wound healing rate of HUVECs decreased upon incubation with H2O2 (P < 0.05). LOX activity and NO production were decreased in H2O2 treated cells (P < 0.05). Expression of miR-126 and VEGFR-2 up-regulated, while expression of miR-373 and HSP-70 up = regulated in H2O2 -induced cells (P < 0.05). In addition, we found that protein levels of p-Akt-1, VCAM-1, MMP-9, and IL-6 decreased in treated cells (P < 0.05).

Conclusions

Our data showed that H2O2 reduced the angiogenic response of HUVECs in vitro, which may be due to impairment of the VEGFR-2 signaling pathway.

Endostatin as a Mediator Between Endothelial Function and Cognitive Performance in Those at Risk for Vascular Cognitive Impairment

Background:

Patients with coronary artery disease have an increased risk for developing vascular cognitive impairment. Endothelial function is often diminished and has been associated with lower cognitive performance in these patients. The link between endothelial function and cognition in coronary artery disease is not fully understood. Angiogenesis may play a role in mediating the association between endothelial function and cognition since angiogenic processes rely heavily on the endothelium.

Objective:

The aim of this study was to determine if markers of angiogenesis mediate the relationship between endothelial function and cognition in coronary artery disease patients.

Methods:

In 50 participants with coronary artery disease, endothelial function was assessed using peripheral arterial tonometry. Vascular endothelial growth factor (pro-angiogenic) and endostatin (anti-angiogenic) were measured in peripheral serum samples. Cognition was assessed using the Montreal Cognitive Assessment. A mediation analysis, using a bias corrected inferential bootstrapping method with 10,000 permutations, was used to determine if vascular endothelial growth factor or endostatin mediated an association between peripheral arterial tonometry measures and cognitive performance on the Montreal Cognitive Assessment.

Results:

Endostatin, but not vascular endothelial growth factor, mediated a relationship between endothelial function and cognitive performance when controlling for total years of education, body mass index, coronary artery bypass graft, stent, diabetes, and diuretic use. This analysis was also significant when delayed recall was substituted for the overall score on the Montreal Cognitive Assessment.

Conclusion:

These results suggest that endostatin mediates an association between endothelial function and cognitive performance in coronary artery disease.

Serum VEGF: Diagnostic Value of Acute Coronary Syndrome from Stable Angina Pectoris and Prognostic Value of Coronary Artery Disease

Background

Although the level of serum vascular endothelial growth factor (VEGF) is elevated in coronary artery disease (CAD) patients, its potential role in acute coronary syndrome (ACS) or stable angina pectoris (SAP) patients remains unclear.

Objectives

To evaluate diagnostic accuracy of serum VEGF in determining ACS patients from SAP and analyze the association of serum VEGF with coronary artery lesions in SAP or the GRACE score in ACS, which is involved in the poor prognosis of low serum VEGF.

Methods

248 CAD patients and 48 healthy subjects were enrolled in this study. Serum VEGF levels were detected by using ELISA. The Gensini score or GRACE score was calculated among SAP or ACS patients. All the patients were followed up for a period of 12 months (mean: 10.77 months).

Results

VEGF serum concentrations were higher in the ACS subgroup than in the SAP subgroup (P < 0.001) with diagnostic accuracy of ACS from SAP (AUC: 0.667, sensitivity: 68.5%, specificity: 60.1%, P < 0.001). Patients with high risk of Gensini score showed reduced VEGF levels (P < 0.001) accompanied by a negative correlation (r = -0.396, P < 0.001). Patients with a higher GRACE score indicated lower VEGF levels (P < 0.001). Low serum VEGF was one of the potential risk factors with adjusted HR of 0.531 (P=0.048).

Conclusion

Serum VEGF exhibits efficient diagnostic value for detection of ACS from SAP with a cutoff value of 648.75 pg/mL. Low serum VEGF indicates severe coronary artery lesions and a higher GRACE score, which suggests poor clinical outcomes.

Animal model of left atrial thrombus in congestive heart failure in rats

The aim of the present study was to develop and study a new model of left atrial thrombus (LAT) in rat with congestive heart failure (CHF). CHF was induced by aortic banding for 2 mo, followed by ischemia-reperfusion (I/R) and subsequent aortic debanding for 1 mo. Cardiac function and the presence of LAT were assessed by echocardiography. Masson's staining was performed for histological analysis. All CHF rats presented with significantly decreased cardiac function, fibrosis in remote myocardium, and pulmonary edema. The incidence rate of LAT was 18.8% in the rats. LAT was associated with severity of aortic constriction, aortic pressure gradient, aortic blood flow velocity, and pulmonary edema but not myocardial infarction or a degree of left ventricular depression. The progressive process of thrombogenesis was characterized by myocyte hypertrophy, fibrosis, and inflammation in the left atrial wall. Fibrin adhesion and clot formation were observed, whereas most LAT presented as a relatively hard "mass," likely attributable to significant fibrosis in the middle and outer layers. Some LAT mass showed focal necrosis as well as fibrin bulging. Most LAT occurred at the upper anterior wall of the left atrial appendage. Aortic debanding had no significant impact on large LATs (>5 mm2) that had formed, whereas small LATs (<5 mm2) regressed 1 mo after aortic release. LAT is found in a rat model of aortic banding plus I/R followed by aortic debanding. The model provides a platform to study molecular mechanisms and potential new pathways for LAT treatment. NEW & NOTEWORTHY It is critically important to have a rodent model to study the molecular mechanism of thrombogenesis in the left atrium. Left atrial thrombus (LAT) is not a simple fibrin clot like those seen in peripheral veins or arteries. Rather, LAT is a cellular mass that likely develops in conjunction with blood clotting. Studying this phenomenon will help us understand congestive heart failure and promote new therapies for LAT.

Placenta growth factor and sFlt-1 as biomarkers in ischemic heart disease and heart failure: a review

Coronary heart disease (CHD) and heart failure (HF) produce significant morbidity/mortality but identifying new biomarkers could help in the management of each. In this article, we summarize the molecular regulation and biomarker potential of PIGF and sFlt-1 in CHD and HF. PlGF is elevated during ischemia and some studies have shown PlGF, sFlt-1 or PlGF:sFlt-1 ratio, when used in combination with standard biomarkers, strengthens predictions of outcomes. sFlt-1 and PlGF are elevated in HF with sFlt-1 as a stronger predictor of outcomes. Although promising, we discuss additional study criteria needed to confirm the clinical usefulness of PlGF or sFlt-1 in the detection and management of CHD or HF.

Association of genetic polymorphisms in vascular endothelial growth factor with susceptibility to coronary artery disease: a meta-analysis

Background

Single nucleotide polymorphisms (SNPs) located in the vascular endothelial growth factor (VEGF) gene may be correlated with the susceptibility to coronary artery disease (CAD) – although results have been controversial. The aim of this meta–analysis is to clarify the effects of VEGF –2578A/C (rs699947), −1154G/A (rs1570360), +405C/G (rs2010963), and + 936C/T (rs3025039) polymorphisms on CAD risk.

Methods

Pooled odds ratio (OR) and corresponding 95% confidence intervals (CIs) were calculated to estimate the strength of the association between VEGF gene polymorphisms and CAD risk. Fixed- or random-effects model was used depending on the heterogeneity between studies.

Results

In total, 13 eligible articles containing 29 studies were analysed. The pooled analysis indicated that the VEGF gene polymorphisms of rs699947, rs2010963, and rs3025039 were associated with an increased risk of CAD, whereas no significant associations were observed with the rs1570360 polymorphism. A subgroup analysis stratified by ethnicity revealed that the rs699947 and rs3025039 polymorphisms were associated with CAD risk in Asian populations. In addition, stratification by control source indicated an increased risk of CAD susceptibility with the rs699947 polymorphism for population–based studies of reduced heterogeneity.

Conclusions

In summary, we concluded that the VEGF gene polymorphisms rs699947, rs2010963, and rs3025039 are correlated with an elevated CAD risk.

Electronic supplementary material

The online version of this article (10.1186/s12881-018-0628-3) contains supplementary material, which is available to authorized users.

The Role of Advanced Glycation End Products in Diabetic Vascular Complications

In cases of chronic hyperglycemia, advanced glycation end-products (AGEs) are actively produced and accumulated in the circulating blood and various tissues. AGEs also accelerate the expression of receptors for AGEs, and they play an important role in the development of diabetic vascular complications through various mechanisms. Active interventions for glucose and related risk factors may help improve the clinical course of patients by reducing AGEs. This review summarizes recent updates on AGEs that have a significant impact on diabetic vascular complications.

Contrast-Enhanced Ultrasound Imaging Quantification of Adventitial Vasa Vasorum in a Rabbit Model of Varying Degrees of Atherosclerosis

This study used an atherosclerotic rabbit model to investigate the feasibility of quantifying adventitial vasa vasorum (VV) via contrast-enhanced ultrasound (CEUS) imaging to identify early atherosclerosis. Recent evidence has linked adventitial VV with atherosclerotic plaque progression and vulnerability. A growth in VV density has been detected preceding intimal thickening and even endothelial dysfunction. In our study, carotid atherosclerosis rabbit models were used, and animals underwent CEUS imaging at the end of the atherosclerotic induction period. Normalized maximal video-intensity enhancement (MVE) was calculated to quantify VV density. After CEUS imaging, animals were euthanized, and their carotids were processed for histopathological analysis following staining for CD31 and VEGF. Adventitial normalized MVE increased as atherosclerosis progressed (p < 0.001), and normalized MVE also progressed, demonstrating a linear correlation with histological findings (r = 0.634, p < 0.001 for VEGF-positive; r = 0.538, p < 0.001 for CD31-positive). Thus, we histologically validated that CEUS imaging can be used to quantify the development of adventitial VV associated with atherosclerosis progression. This method can be used for monitoring the VV to detect early atherosclerosis.

Prognostic use of soluble fms-like tyrosine kinase-1 and placental growth factor in patients with coronary artery disease

Background: Intention of the study is to assess the cardiovascular mortality of patients with coronary artery disease (CAD) with the biomarkers of angiogenesis PlGF and its endogenous inhibitor sFlt-1. Methods: The cohort included n = 1848 patients with CAD and 282 subjects without CAD. In 85 patients cardiovascular mortality, as combination of fatal myocardial infarction or any cardiac death, during a median follow-up duration of 3.9 years was reported. Results: In Kaplan–Meier curve analysis PlGF in rising thirds was not predictive regarding outcome (p = 0.54), the same was shown for sFlt-1 (p = 0.44). Cox regression for the fully adjusted model provided a hazard ratio (HR) of 0.8 (p = 0.18) for PlGF and for sFlt-1 a HR = 1.0 (p = 0.8). Conclusion: Our results point out that these biomarkers reflecting angiogenesis might not be suited to establish prognosis in CAD.

Stable phase post-MI patients have elevated VEGF levels correlated with inflammation markers, but not with atherosclerotic burden

BACKGROUND

The role of vascular endothelial growth factor (VEGF) in patients in the stable phase after myocardial infarction (MI) has not yet been explored. Therefore, we compared the values of VEGF in post-MI patients with those obtained in healthy controls. Furthermore, we investigated whether the values of VEGF correlate to either inflammation markers or the atherosclerotic burden.

METHODS

41 male patients (on average 44 years old) in the stable phase after MI (on average 20.5 months after MI) were recruited, while 25 healthy age-matched males served as controls. Plasma levels of VEGF and several markers of inflammation were measured by standard procedures. The atherosclerotic burden was determined by the angiographic severity of coronary atherosclerosis, endothelial dysfunction (measured by ultrasound measurement of the flow mediated dilation of the brachial artery), the intima-media thickness of the common carotid artery and the ankle-brachial pressure index.

RESULTS

VEGF values were significantly elevated in post-MI patients compared to the controls (53.8 ± 42.7 pg/ml vs. 36.3 ± 8.9 pg/ml, p = 0.014). The elevated VEGF values significantly correlated to the (increased) values of the inflammatory molecules interleukin 6 and 8 (r = 0.37, p = 0.017; and r = 0.45, p = 0.003; respectively). In contrast, no correlation was found between VEGF and the parameters of the atherosclerotic burden, although FMD and IMT were significantly impaired in patients.

CONCLUSIONS

We found that plasma levels of VEGF are increased in the stable phase after MI and correlate with inflammation cytokines, but not with the atherosclerotic burden. Thus, this suggests that increased levels of VEGF are a part of ongoing inflammatory activity. Since VEGF in these patients stimulates neovascularization of inflamed plaques and induces their destabilization, the VEGF level can have an important negative prognostic value. Clearly, further studies are needed to clarify the role of VEGF as a prognostic marker.

Atherosclerosis and thromboembolic risk in atrial fibrillation: focus on peripheral vascular disease

Atrial fibrillation (AF) is the most common cardiac arrhythmia in clinical practice. It results in a 5-fold increased risk for stroke and thromboembolism and is associated with a high morbidity and mortality. AF shares several risk factors and pathophysiological features with atherosclerosis. Hence AF is often complicated by a variety of other cardiovascular conditions. Indeed, peripheral vascular disease (PVD) is highly prevalent among AF patients and associates with increased mortality. Inclusion of PVD within stroke risk scoring systems such as the CHA2DS2-VASc score improves risk stratification of AF patients. Of note, PVD has not been previously well documented nor looked for in observational studies or clinical trials. The aim of this present review article is to provide an overview of the association between atherosclerosis (with particular focus on PVD) and AF as well as its complications.

Effects of pregnancy on endothelial function and cardiovascular disease risk in HIV-infected women

OBJECTIVE

This study assessed flow-mediated vasodilation (FMD) and brachial artery diameter (BAD) in HIV-infected pregnant women compared to healthy pregnant controls, and determined their relationships to variables of interest, including the HIV status.

METHODS

Subjects were enrolled prospectively for this longitudinal, observational study. Body mass index (BMI), blood pressure (BP), fasting lipoprotein profiles, homeostasis model assessment of insulin resistance (HOMA-IR), FMD, and BAD were assessed at 10-12, 20-22, and 32-35weeks gestation in HIV-infected women and healthy controls aged 18-45years with singleton pregnancies.

RESULTS

Fourteen HIV-infected women and 19 controls were enrolled. Groups were similar at baseline except there were more Caucasians in the control group (P<0.01). FMD and BAD did not change during pregnancy in either group, and there were no differences between groups. In multivariable regression analysis, FMD was associated with BAD (P=0.002), but not with age, BMI, BP, TC, TG, HOMA-IR, or HIV status. No variables were associated with BAD.

CONCLUSION

No differences were observed in FMD or BAD between HIV-infected and healthy pregnant women, and neither measure changed significantly during pregnancy. HIV status did not affect endothelial function or brachial artery diameter. Pregnancy does not appear to further increase the CVD risk associated with HIV infection.

Short communication: initiation of an abacavir-containing regimen in HIV-infected adults is associated with a smaller decrease in inflammation and endothelial activation markers compared to non-abacavir-containing regimens

Abacavir has been associated with myocardial infarction in several studies. This may be related to inflammation and endothelial cell activation. We compared changes in inflammation and endothelial activation markers between antiretroviral-naive adults initiating zidovudine, lamivudine, abacavir, and nonnucleoside reverse transcriptase inhibitor (NNRTI) or this regimen without abacavir. Changes in soluble tumor necrosis factor receptors-I, -II (sTNFR-I, -II), high sensitivity C-reactive protein, and soluble vascular cell adhesion molecule-1 (sVCAM-1) from baseline (pre-ART) to a second time point about 24 weeks after initiating antiretroviral therapy (ART) were compared between groups using multivariable linear regression. A total of 37 met eligibility criteria; 12 received abacavir. The median (interquartile range) age was 37 years (27-45). Most were men (32/37), African-American (15/37), or white (15/37). The median nadir CD4(+) and baseline HIV-1 RNA were 230 cells/mm(3) (180-301) and 82,642 copies/ml (34,400-204,703). In all, 15/30 smoked, 7/37 had hypertension, 1/37 had diabetes, and 1/37 had hyperlipidemia. None had coronary or renal disease. Changes in CD4(+) and HIV-1 RNA level and timing of stored samples with regard to ART initiation were not different between groups. In univariable analysis, log transformed percent change in sTNFR-I (p=0.05) and -II (p=0.04) showed significant between-group differences and trended toward significance for sVCAM-1 (p=0.08). These markers decreased less in the abacavir group. After adjustment for confounders, significantly less decrease for sTNFR-II and sVCAM-1 was seen for those receiving the abacavir-containing regimen. When taken with an NNRTI, abacavir induced a smaller decrease in inflammation biomarkers in this cohort, suggesting a possible proinflammatory effect of this nucleoside analogue.

Vascular endothelial growth factor and uPA/suPAR system in early and advanced chronic kidney disease patients: a new link between angiogenesis and hyperfibrinolysis?

Disturbances in hemostasis and abnormal angiogenesis are components in the plaque growth and destabilization. The role of the vascular endothelial growth factor (VEGF) in the perturbation of hemostasis in chronic kidney disease (CKD) is still unknown. In this preliminary study, we investigate the relation between VEGF and the parameters of coagulation: tissue factor (TF), its inhibitor (TFPI), and fibrinolytic system: urokinase-type plasminogen activator (uPA), its soluble receptor (suPAR), tissue-type plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1), plasmin/antiplasmin complexes (PAP) in the patients with mild-to-moderate, and severe CKD and healthy controls. All indices (except TFPI) were raised in CKD patients, particularly in those with severe CKD, compared with controls. The strong positive correlations were between VEGF and some parameters, both coagulation (TF, TFPI, TF/TFPI ratio) and fibrinolytic system (uPA, suPAR, PAP). The relationships were also between the individual hemostatic parameters. In multiple regression analysis, VEGF and kidney dysfunction markers (urea and creatinine levels) were independently associated with uPA, and VEGF was independently associated with suPAR levels. Moreover, PAP was independently associated with age and suPAR. This study represents the first to investigate the relation between VEGF and the activation both coagulation and fibrinolysis in CKD patients. VEGF and the parameters of hemostatic system activation were higher in the CKD group than in the controls with a significant correlation between them. VEGF was independently associated with uPA/suPAR system, whereas suPAR was independently related to PAP levels, suggesting a new link between abnormal angiogenesis and hyperfibrinolysis in this population.

T-cell phenotypes, apoptosis and inflammation in HIV+ patients on virologically effective cART with early atherosclerosis

Objective

We investigated the potential relationship between T-cell phenotype, inflammation, endotoxemia, and atherosclerosis evaluated by carotid intima-media thickness (IMT) in a cohort of HIV-positive patients undergoing long-term virologically suppressive combination antiretroviral therapy (cART).

Design

We studied 163 patients receiving virologically suppressive cART.

Methods

We measured IMT (carotid ultrasound); CD4+/CD8+ T-cell activation (CD38, CD45R0), differentiation (CD127), apoptosis (CD95), and senescence (CD28, CD57) (flow cytometry); plasma sCD14, IL-6, TNF- α, sVCAM-1, hs-CRP, anti-CMV IgG (ELISA); LPS (LAL). The results were compared by Mann-Whitney, Kruskal-Wallis or Chi-square tests, and factors associated with IMT were evaluated by multivariable logistic regression.

Results

Of 163 patients, 112 demonstrated normal IMT (nIMT), whereas 51 (31.3%) had pathological IMT (pIMT: ≥1 mm). Of the patients with pIMT, 22 demonstrated an increased IMT (iIMT), and 29 were shown to have plaques. These patient groups had comparable nadir and current CD4+, VLs and total length of time on cART. Despite similar proportions of CD38-expressing CD8+ cells (p = .95), pIMT patients exhibited higher activated memory CD8+CD38+CD45R0+ cells (p = .038) and apoptotic CD4+CD95+ (p = .01) and CD8+CD95+ cells (p = .003). In comparison to nIMT patients, iIMT patients tended to have lower numbers of early differentiated CD28+CD57− memory CD4+ (p = .048) and CD28–CD57−CD8+ cells (p = .006), both of which are associated with a higher proliferative potential. Despite no differences in plasma LPS levels, pIMT patients showed significantly higher circulating levels of sCD14 than did nIMT patients (p = .046). No differences in anti-CMV IgG was shown. Although circulating levels of sCD14 seemed to be associated with a risk of ATS in an unadjusted analysis, this effect was lost after adjusting for classical cardiovascular predictors.

Conclusions

Despite the provision of full viral suppression by cART, a hyperactivated, pro-apoptotic T-cell profile characterizes HIV-infected patients with early vascular damage, for whom the potential contribution of subclinical endotoxemia and anti-CMV immunity should be investigated further.

Vitamin D is linked to carotid intima-media thickness and immune reconstitution in HIV-positive individuals

BACKGROUND

Patients with HIV infection are at increased risk of cardiovascular disease (CVD). Vitamin D insufficiency has been associated with increased CVD risk in non-HIV populations. This study sought to determine the relationship between vitamin D status and markers of CVD and HIV-related factors in HIV-positive patients.

METHODS

Patients with HIV infection on antiretroviral therapy and healthy controls were prospectively enrolled. Fasting lipids, glucose, insulin, inflammatory markers (soluble tumour necrosis factor-α receptor I, interleukin-6 and high-sensitivity C-reactive protein) and endothelial markers (soluble intercellular adhesion molecule-1 and soluble vascular cell adhesion molecule-1) were measured. Fasting 25-hydroxyvitamin D (25(OH)D) was measured from stored serum samples. The internal carotid artery and common carotid artery (CCA) intima-media thickness (IMT) were measured in a subset of HIV-positive patients. Baseline cross-sectional data were analysed.

RESULTS

A total of 149 HIV-positive patients (56 with carotid IMT) and 34 controls were included. Controls had higher adjusted mean 25(OH)D levels than HIV-positive patients (P=0.02). In multivariable linear regression among the HIV-positive patients, 25(OH)D was positively associated with CD4(+) T-cell restoration after antiretroviral therapy (ΔCD4 = current - nadir CD4(+) T-cell; P<0.01), but was not associated with inflammatory or endothelial markers. In multivariable logistic regression, odds of having CCA IMT above the median were more than 10× higher in those with lower 25(OH)D levels (OR=10.62, 95% CI 1.37-82.34; P<0.01).

CONCLUSIONS

Vitamin D status in HIV-positive patients was positively associated with improved immune restoration after antiretroviral therapy and negatively associated with CCA IMT. These findings suggest that vitamin D may play a role in HIV-related CVD and in immune reconstitution after antiretroviral therapy.

Plasma chemokine levels are associated with the presence and extent of angiographic coronary collaterals in chronic ischemic heart disease

BACKGROUND

In patients with chronic ischemic heart disease (IHD), the presence and extent of spontaneously visible coronary collaterals are powerful determinants of clinical outcome. There is marked heterogeneity in the recruitment of coronary collaterals amongst patients with similar degrees of coronary artery stenoses, but the biological basis of this heterogeneity is not known. Chemokines are potent mediators of vascular remodeling in diverse biological settings. Their role in coronary collateralization has not been investigated. We sought to determine whether plasma levels of angiogenic and angiostatic chemokines are associated with of the presence and extent of coronary collaterals in patients with chronic IHD.

METHODOLOGY/PRINCIPAL FINDINGS

We measured plasma concentrations of angiogenic and angiostatic chemokine ligands in 156 consecutive subjects undergoing coronary angiography with at least one ≥90% coronary stenosis and determined the presence and extent of spontaneously visible coronary collaterals using the Rentrop scoring system. Eighty-eight subjects (56%) had evidence of coronary collaterals. In a multivariable regression model, the concentration of the angiogenic ligands CXCL5, CXCL8 and CXCL12, hyperlipidemia, and an occluded artery were associated with the presence of collaterals; conversely, the concentration of the angiostatic ligand CXCL11, interferon-γ, hypertension and diabetes were associated with the absence of collaterals (ROC area 0.91). When analyzed according to extent of collateralization, higher Rentrop scores were significantly associated with increased concentration of the angiogenic ligand CXCL1 (p<0.0001), and decreased concentrations of angiostatic ligands CXCL9 (p<0.0001), CXCL10 (p = 0.002), and CXCL11 (p = 0.0002), and interferon-γ (p = 0.0004).

CONCLUSIONS/SIGNIFICANCE

Plasma chemokine concentrations are associated with the presence and extent of spontaneously visible coronary artery collaterals and may be mechanistically involved in their recruitment.

Androgen stimulates endothelial cell proliferation via an androgen receptor/VEGF/cyclin A-mediated mechanism

Growing evidences support that androgen displays beneficial effects on cardiovascular functions although the mechanism of androgen actions remains to be elucidated. Modulation of endothelial cell growth and function is a potential mechanism of androgen actions. We demonstrated in the present study that androgens [dihydrotestosterone (DHT) and testosterone], but not 17β-estradiol, produced a time- and dose-dependent induction of cell proliferation in primary human aortic endothelial cells (HAECs) as evident by increases in viable cell number and DNA biosynthesis. Real-time qRT-PCR analysis showed that DHT induced androgen receptor (AR), cyclin A, cyclin D1, and vascular endothelial growth factor (VEGF) gene expression in a dose- and time-dependent manner. The addition of casodex, a specific AR antagonist, or transfection of a specific AR siRNA blocked DHT-induced cell proliferation and target gene expression, indicating that the DHT effects are mediated via AR. Moreover, coadministration of SU5416 to block VEGF receptors, or transfection of a specific VEGF-A siRNA to knockdown VEGF expression, produced a dose-dependent blockade of DHT induction of cell proliferation and cyclin A gene expression. Interestingly, roscovitine, a selective cyclin-dependent kinase inhibitor, also blocked the DHT stimulation of cell proliferation with a selective inhibition of DHT-induced VEGF-A expression. These results indicate that androgens acting on AR stimulate cell proliferation through upregulation of VEGF-A, cyclin A, and cyclin D1 in HAECs, which may be beneficial to cardiovascular functions since endothelial cell proliferation could assist the repair of endothelial injury/damage in cardiovascular system.

Soluble fms-like tyrosine kinase-1 and the progression of carotid intima-media thickness – 24-month follow-up study –

BACKGROUND

The relationship between fms-like tyrosine kinase-1 (sFlt-1), a soluble receptor for vascular endothelial growth factor (VEGF), and vascular disease has not been established, so this study aimed to elucidate the association between sFlt-1 and the progression of carotid intima - media thickness (IMT) in hypertensive patients.

METHODS AND RESULTS

The 120 hypertensive patients under medical control were enrolled and 112 completed the study (age 59 ± 9 years, 57 females). Plasma VEGF and sFlt-1 levels were measured at enrollment. At baseline and 24-month visit, carotid IMT was measured and the association between sFlt-1 and IMT progression was assessed by linear regression. At baseline, age (r=0.186) and low level of high-density lipoprotein-cholesterol (HDL-C <40 mg/dl, r=0.214) were significantly related to carotid IMT. Over the 24 months, carotid IMT increased from 0.670 ± 0.089 mm to 0.696 ± 0.095 mm. There was a positive correlation between sFlt-1 tertiles and IMT change (P=0.05 by ANOVA). Upon multivariate analysis, log-transformed sFlt-1 level (β=0.137, P=0.003) and low HDL-C (β=0.048, P=0.04) were identified as predictors of IMT progression, independent of other confounding variables.

CONCLUSIONS

High sFlt-1 level is predictive of carotid IMT progression in hypertensive patients. Low HDL-C level was also associated with IMT change. These observations support a high sFlt-1 level being indicative of progression of atherosclerosis. 

Vascular Endothelial Growth Factor, Soluble Fms-Like Tyrosine Kinase 1, and the Severity of Coronary Artery Disease

Background: The association between vascular endothelial growth factor (VEGF), soluble fms-like tyrosine kinase 1 (sFlt-1), and coronary artery disease (CAD) was investigated. Methods: We enrolled 112 hypertensive patients with proven CAD and 112 hypertensive controls matched for age and gender. The severity of CAD was assessed by the most severe clinical presentation of CAD in patients’ history and by the number of diseased vessels. Results: Vascular endothelial growth factor level was lower, whereas sFlt-1 level was higher in the CAD group compared to the controls. Diabetes mellitus (P = .001), smoking (P = .004), and higher sFlt-1 level (P = .01) were independently associated with CAD. Younger age (P = .02), smoking (P = .049), and higher VEGF levels (P = .02) were independently associated with a history of myocardial infarction (MI), whereas higher sFlt-1 level (P = .01) was independently associated with multivessel disease. Conclusion: Plasma sFlt-1 levels are positively associated with the presence of CAD and are associated with angiographical severity of CAD.

Relationship between inflammatory markers, endothelial activation markers, and carotid intima-media thickness in HIV-infected patients receiving antiretroviral therapy

BACKGROUND

Human immunodeficiency virus (HIV)-infected patients are at increased risk of cardiovascular disease, which may be related to chronic inflammation and endothelial dysfunction despite virological control with antiretroviral therapy. The relationship between carotid intima-media thickness (IMT), a surrogate marker for cardiovascular disease, proinflammatory cytokines, and endothelial activation markers has not been fully explored in HIV-infected patients who are receiving antiretroviral therapy.

METHODS

We conducted a prospective, cross-sectional, observational study of treated HIV-infected patients and healthy control subjects to evaluate the relationship between carotid IMT, proinflammatory cytokines, endothelial activation biomarkers, and metabolic parameters in treated HIV-infected patients, compared with healthy control subjects.

RESULTS

We enrolled 73 HIV-infected patients and 21 control subjects. Common carotid artery and internal carotid artery IMT measurements, as well as tumor necrosis factor-alpha, high-sensitivity C-reactive protein, interleukin-6, myeloperoxidase, and soluble vascular cell adhesion molecule-1 levels were higher in the HIV-infected group. High-sensitivity C-reactive protein was the only biomarker that was positively correlated with carotid IMT in both groups. In the HIV-infected group, soluble vascular cell adhesion molecule-1 was positively correlated with all inflammatory cytokine levels. In multiple regression analysis, soluble vascular cell adhesion molecule-1, myeloperoxidase, and tumor necrosis factor-alpha levels were all associated with internal carotid artery IMT in the HIV-infected group, whereas age was associated with both common carotid artery and internal carotid artery IMT.

CONCLUSIONS

Enhanced endothelial activation, inflammation, and increased carotid IMT occur in HIV-infected patients despite antiretroviral therapy. Inflammatory markers are associated with endothelial activation, and both are associated with internal carotid artery IMT, supporting a potential role of inflammation in endothelial activation and cardiovascular disease in HIV infection.

A systems biology perspective on sVEGFR1: its biological function, pathogenic role and therapeutic use

Angiogenesis is the growth of new capillaries from pre-existent microvasculature. A wide range of pathological conditions, from atherosclerosis to cancer, can be attributed to either excessive or deficient angiogenesis. Central to the physiological regulation of angiogenesis is the vascular endothelial growth factor (VEGF) system – its ligands and receptors (VEGFRs) are thus prime molecular targets of pro-angiogenic and anti-angiogenic therapies. Of growing interest as a prognostic marker and therapeutic target in angiogenesis-dependent diseases is soluble VEGF receptor-1 (sVEGFR1, also known as sFlt-1) – a truncated version of the cell membrane-spanning VEGFR1. For instance, it is known that sVEGFR1 is involved in the endothelial dysfunction characterizing the pregnancy disorder of pre-eclampsia, and sVEGFR1’s therapeutic potential as an anti-angiogenic agent is being evaluated in pre-clinical models of cancer. This mini review begins with an examination of the protein domain structure and biomolecular interactions of sVEGFR1 in relation to the full-length VEGFR1. A synopsis of known and inferred physiological and pathological roles of sVEGFR1 is then given, with emphasis on the utility of computational systems biology models in deciphering the molecular mechanisms by which sVEGFR1’s purported biological functions occur. Finally, we present the need for a systems biology perspective in interpreting circulating VEGF and sVEGFR1 concentrations as surrogate markers of angiogenic status in angiogenesis-dependent diseases.

Vascular endothelial growth factor in serum indicates cardiovascular risk in urology patients

OBJECTIVE

We hypothesized that a high serum concentration of vascular endothelial growth factor (VEGF), a cytokine involved in prostate growth which is also upregulated in chronic ischemia, indicates an increased risk of cardiovascular disease and death in urology patients.

MATERIAL AND METHODS

The serum VEGF concentration was measured in 219 males (mean age 72 years) who sought medical attention because of lower urinary tract symptoms. Data on cardiovascular events and survival were obtained from the hospital registry of Stockholm County and the Death Registry over a period of up to 10 years (mean 6.2 years).

RESULTS

After adjusting for the effects of age and smoking, patients with a serum VEGF level in the upper 20% of the cohort (>500 pg/ml) had an increased risk of developing cardiovascular disease (hazard ratio 2.18; 95% CI 1.04-4.60), including acute myocardial infarction (3.36; 1.35-8.41) and stroke (3.98; 1.61-9.86). They also had an increased risk of death (1.74; 1.01-3.00). These differences from patients with a lower serum VEGF concentration (<300 pg/ml) were manifested 2-5 years after the blood sample was taken.

CONCLUSION

An elevated VEGF level in peripheral blood was a risk factor for subsequent development of cardiovascular disease.

A compartment model of VEGF distribution in humans in the presence of soluble VEGF receptor-1 acting as a ligand trap

Vascular endothelial growth factor (VEGF), through its activation of cell surface receptor tyrosine kinases including VEGFR1 and VEGFR2, is a vital regulator of stimulatory and inhibitory processes that keep angiogenesis--new capillary growth from existing microvasculature--at a dynamic balance in normal physiology. Soluble VEGF receptor-1 (sVEGFR1)--a naturally-occurring truncated version of VEGFR1 lacking the transmembrane and intracellular signaling domains--has been postulated to exert inhibitory effects on angiogenic signaling via two mechanisms: direct sequestration of angiogenic ligands such as VEGF; or dominant-negative heterodimerization with surface VEGFRs. In pre-clinical studies, sVEGFR1 gene and protein therapy have demonstrated efficacy in inhibiting tumor angiogenesis; while in clinical studies, sVEGFR1 has shown utility as a diagnostic or prognostic marker in a widening array of angiogenesis-dependent diseases. Here we developed a novel computational multi-tissue model for recapitulating the dynamic systemic distributions of VEGF and sVEGFR1. Model features included: physiologically-based multi-scale compartmentalization of the human body; inter-compartmental macromolecular biotransport processes (vascular permeability, lymphatic drainage); and molecularly-detailed binding interactions between the ligand isoforms VEGF(121) and VEGF(165), signaling receptors VEGFR1 and VEGFR2, non-signaling co-receptor neuropilin-1 (NRP1), as well as sVEGFR1. The model was parameterized to represent a healthy human subject, whereupon we investigated the effects of sVEGFR1 on the distribution and activation of VEGF ligands and receptors. We assessed the healthy baseline stability of circulating VEGF and sVEGFR1 levels in plasma, as well as their reliability in indicating tissue-level angiogenic signaling potential. Unexpectedly, simulated results showed that sVEGFR1 - acting as a diffusible VEGF sink alone, i.e., without sVEGFR1-VEGFR heterodimerization--did not significantly lower interstitial VEGF, nor inhibit signaling potential in tissues. Additionally, the sensitivity of plasma VEGF and sVEGFR1 to physiological fluctuations in transport rates may partially account for the heterogeneity in clinical measurements of these circulating angiogenic markers, potentially hindering their diagnostic reliability for diseases.

Endothelial activation markers are linked to HIV status and are independent of antiretroviral therapy and lipoatrophy

OBJECTIVES

To assess the association of inflammatory and endothelial activation biomarkers with the presence of lipoatrophy in HIV-infected subjects and to examine the role of HIV, antiretroviral therapy (ART), and metabolic parameters in endothelial activation and inflammation.

DESIGN

Prospective, cross-sectional study including 4 groups: HIV+ on ART with HIV-1 RNA<1000 copies/mL with and without clinical lipoatrophy, HIV+ ART naive, and healthy controls.

METHODS

We measured plasma levels of inflammatory cytokines (tumor necrosis factor-alpha, soluble tumor necrosis factor receptors I and II, interleukin-6, C-reactive protein, and myeloperoxidase) and endothelial activation markers (soluble intercellular and vascular cell adhesion molecules and von Willebrand factor).

RESULTS

We enrolled 182 subjects. Limb fat and lipoatrophy status were not correlated with endothelial markers. Endothelial markers were higher in HIV+ ART naive when compared with healthy controls and with HIV+ on ART but were similar between HIV+ on ART and healthy controls. Neither endothelial nor inflammatory markers were correlated with HIV duration, CD4 count, lipids, glucose, or specific ART. Strong correlations were found between some inflammatory cytokines and endothelial markers.

CONCLUSIONS

There is enhanced endothelial activation in ART naive, whereas HIV+ on ART has similar values to healthy controls. Lipoatrophy did not seem to affect endothelial activation. Results highlight a potential association between heightened inflammation and endothelial activation.

Pathway analysis of seven common diseases assessed by genome-wide association

Recent genome-wide association studies (GWAS) have identified DNA sequence variations that exhibit unequivocal statistical associations with many common chronic diseases. However, the vast majority of these studies identified variations that explain only a very small fraction of disease burden in the population at large, suggesting that other factors, such as multiple rare or low-penetrance variations and interacting environmental factors, are major contributors to disease susceptibility. Identifying multiple low-penetrance variations (or "polygenes") contributing to disease susceptibility will be difficult. We present a pathway analysis approach to characterizing the likely polygenic basis of seven common diseases using the Wellcome Trust Case Control Consortium (WTCCC) GWAS results. We identify numerous pathways implicated in disease predisposition that would have not been revealed using standard single-locus GWAS statistical analysis criteria. Many of these pathways have long been assumed to contain polymorphic genes that lead to disease predisposition. Additionally, we analyze the genetic relationships between the seven diseases, and based upon similarities with respect to the associated genes and pathways affected in each, propose a new way of categorizing the diseases.

Alterations in plasma soluble vascular endothelial growth factor receptor-1 (sFlt-1) concentrations during coronary artery bypass graft surgery: relationships with post-operative complications

Background

Plasma concentrations of sFlt-1, the soluble form of the vascular endothelial growth factor receptor (VEGF), markedly increase during coronary artery bypass graft (CABG) surgery with extracorporeal circulation (ECC). We investigated if plasma sFlt-1 values might be related to the occurrence of surgical complications after CABG.

Methods

Plasma samples were collected from the radial artery catheter before vascular cannulation and after opening the chest, at the end of ECC just before clamp release, after cross release, after weaning from ECC, at the 6^th and 24^th post-operative hour. Thirty one patients were investigated. The presence of cardiovascular, haematological and respiratory dysfunctions was prospectively assessed. Plasma sFlt-1 levels were measured with commercially ELISA kits.

Results

Among the 31 investigated patients, 15 had uneventful surgery. Patients with and without complications had similar pre-operative plasma sFlt-1 levels. Lowered plasma sFlt-1 levels were observed at the end of ECC in patients with haematological (p = 0.001, ANOVA) or cardiovascular (p = 0.006) impairments, but not with respiratory ones (p = 0.053), as compared to patients with uneventful surgery.

Conclusion

These results identify an association between specific post-CABG complication and the lower release of sFlt-1 during ECC. sFlt-1-induced VEGF neutralisation might, thus, be beneficial to reduce the development of post-operative adverse effects after CABG.

[Von Willebrand factor, endothelial lesion, and ischemic heart disease]

OBJECTIVE

To analyze if the levels of von Willebrand factor (FvW) are higher in patients with ischemic heart disease than in healthy subjects and evaluate the relationship of these levels with clinical recurrence and coronary interventionism.

DESIGN

Observational prospective study.

PATIENTS

We analyzed the levels of FvW in 75 patients with ischemic heart disease who underwent coronary interventionism (Group I) and compared them with those of 30 healthy subjects with no cardiovascular risk factors and who, theoretically, had no coronary injuries (Group II).

MAIN VARIABLES

Levels of FvW before coronary interventionism (sample 0), 24 hours after (sample 1), and at three months of out-patient follow-up (sample 2). A single measurement was made of the FvW levels in Group II.

RESULTS

Subjects with ischemic heart disease had higher levels of FvW than healthy subjects (162+/-74% versus 95+/-33%; p=0.0001). FvW levels were significantly increased after coronary interventionism (162.4+/-74.9% in sample 0 versus 213+/-90% in sample 1; p=0.0001). Patients with clinical symptoms at three months have no significant difference regarding those with no symptoms in the FvW levels (125+/-63% versus 133+/-60%; p=0.57).

CONCLUSIONS

FvW levels reflect an endothelial alteration in patients with ischemic heart disease. The increase of the levels after coronary interventionism could be due to the endothelial aggression itself of the intervention. It was not possible to demonstrate higher levels of FvW in patients with symptoms in the three month follow-up.

Non-traditional biomarkers of atherosclerosis in stable and unstable coronary artery disease, do they differ?

BACKGROUND

Biomarkers of atherosclerosis are emerging as a potential tool for assessment of coronary artery disease (CAD) patients. As acute coronary syndrome (ACS), and stable CAD are distinguished in their pathophysiology it is conceivable that they are also characterized by different biomarkers of atherosclerosis.

METHODS

We systematically reviewed the literature for clinical studies of several non-traditional biomarkers of atherosclerosis reflecting various pathophysiological processes, namely macrophage-activity, oxidative-stress, tissue remodeling, and thrombosis in ACS and stable CAD to determine whether circulating biomarkers are differently expressed/predict outcome in these two clinical conditions.

RESULTS

Macrophage-activity (monocyte chemoattractant protein-1, neopterin), tissue-remodeling (matrix metalloproteinase-9) and thrombosis (tissue-factor) related biomarkers were consistently elevated in ACS compared to stable CAD, in accordance with the pathophysiological role of these mediators in plaque rupture, characterizing ACS. Thus, these biomarkers may be applicable for diagnosis of ACS. Additionally, neopterin was consistently shown to predict outcome in both stable and ACS patients and myeloperoxidase was strongly shown to predict outcome in ACS, implying for their potential role in risk stratification of these patients.

CONCLUSIONS

As ACS and stable CAD are characterized by different pathophysiological processes, it appears that the biomarkers that are associated with them are differently expressed in these two clinical conditions

Release of soluble vascular endothelial growth factor receptor-1 (sFlt-1) during coronary artery bypass surgery

Background

This study was conducted to follow plasma concentrations of sFlt-1 and sKDR, two soluble forms of the vascular endothelial growth factor (VEGF) receptor in patients undergoing coronary artery bypass graft (CABG) surgery with extracorporeal circulation (ECC).

Methods

Plasma samples were obtained before, during and after surgery in 15 patients scheduled to undergo CABG. Levels of sFlt-1 and KDR levels were investigated using specific ELISA.

Results

A 75-fold increase of sFlt-1 was found during cardiac surgery, sFlt-1 levels returning to pre-operative values at the 6^th post-operative hour. In contrast sKDR levels did not change during surgery. The ECC-derived sFlt-1 was functional as judge by its inhibitory effect on the VEGF mitogenic response in human umbilical vein endothelial cells (HUVECs). Kinetic experiments revealed sFlt-1 release immediately after the beginning of ECC suggesting a proteolysis of its membrane form (mFlt-1) rather than an elevated transcription/translation process. Flow cytometry analysis highlighted no effect of ECC on the shedding of mFlt-1 on platelets and leukocytes suggesting vascular endothelial cell as a putative cell source for the ECC-derived sFlt-1.

Conclusion

sFlt-1 is released during CABG with ECC. It might be suggested that sFlt-1 production, by neutralizing VEGF and/or by inactivating membrane-bound Flt-1 and KDR receptors, might play a role in the occurrence of post-CABG complication.

Erythropoietin promotes survival of primary human endothelial cells through PI3K-dependent, NF-kappaB-independent upregulation of Bcl-xL

Erythropoietin (EPO) regulates the production of red blood cells primarily by preventing apoptosis of erythroid progenitors. More recently, however, EPO has emerged as a major cytoprotective cytokine in several nonhemopoietic tissues in the setting of stress or injury. The underlying mechanisms of the protective responses of EPO have not been fully defined. Here we show that EPO triggers a phosphatidylinositol 3-kinase-(PI3K)-dependent survival pathway that counteracts endothelial cell death. The protection conferred by PI3K relies on the subsequent induction of Bcl-x(L), a prosurvival member of the Bcl-2 protein family. In addition, EPO counteracts the upregulation of the pro-apoptotic BH3-only protein BIM, which is induced by serum withdrawal. EPO also activates extracellular signal-regulated kinase 1 and 2 (ERK1/2), which are involved in a Bcl-x(L)-independent cytoprotective pathway. EPO caused a prolonged activation of nuclear factor (NF)-kappaB, which was blocked by inhibition of PI3K, but not by inhibition of mitogen-activated protein (MAP)/ERK kinase (MEK), suggesting that EPO-activated NF-kappaB requires PI3K activity. However, the activation of the NF-kappaB pathway was not required for the ability of EPO to counteract endothelial apoptosis. Thus EPO promotes survival of endothelial cells through PI3K-dependent Bcl-x(L)-induction and BIM regulation, as well as through a separate mechanism involving the ERK pathway.

Association of plasma eotaxin levels with the presence and extent of angiographic coronary artery disease

Eotaxin (CCL11) is an eosinophil-specific chemoattractant which has been found to be highly expressed at sites of vascular pathology. In the present study, we aimed to evaluate the association of plasma eotaxin levels with the presence and extent of angiographic coronary artery disease (CAD). Three hundred and fifty six consecutive patients attending for elective coronary angiography were investigated. Compared with 111 patients without CAD, 245 with CAD showed higher eotaxin concentrations [median (interquartile range): 76.0 (56.3-103.0)pg/ml versus 116.0 (80.5-162.0)pg/ml, respectively; P<0.001]. Importantly, a significant Spearman correlation was found between eotaxin levels and the extent score of coronary artery stenosis (r=0.449, P<0.001). A stepwise increase in plasma levels of eotaxin was also found depending on the number of >50% coronary stenosis: median value 76.0 pg/ml in CAD(-) subjects, 96.0 pg/ml in 1-vessel disease, 128.0 pg/ml in 2-vessel disease, and 129.0 pg/ml in 3-vessel disease (P<0.001 for trend). After confounding variables were controlled for, multiple stepwise regression analysis demonstrated that plasma eotaxin was an independent predictor of angiographic extent of CAD (beta=0.426, P<0.001). Our data suggest that increased eotaxin levels are associated with the presence of CAD and that circulating levels of this chemokine may reflect the extent of coronary atherosclerosis.

Time courses of vascular endothelial growth factor and intercellular adhesion molecule-1 expressions in aortas of atherosclerotic rats

An increasing number of studies have focused on the expressions of growth factors and adhesion molecules in atherosclerotic lesions, which are confirmed to play central roles in angiogenesis and endothelial dysfunction, including vascular endothelial growth factor (VEGF) and intercellular adhesion molecule-1 (ICAM-1). However, the difference of growth factor and adhesion molecule expression time courses has not been determined in vivo. This study aimed to determine the expression patterns and expression curves of ICAM-1 and VEGF in atherosclerotic rats during the time course. An experiment atherosclerotic model in rats was established by combining the high fat/cholesterol diets with injection of vitamin D3. In situ hybridization was used to determine the expression patterns of VEGF and ICAM-1 in aortas of normal or atherosclerotic rats in 8 weeks. There was a massive increase in reactivity for both ICAM-1 and VEGF in atherosclerotic plaques. Northern blot, Western blot and ELISA analysis were used to quantify VEGF and ICAM-1 expressions in time course. In rat aorta, the expression curves in time course showed that ICAM-1, not VEGF, was up-regulated in mRNA levels significantly in 2 weeks; while VEGF expression was hysteresis than ICAM-1, which showed maximum expression level in 8 weeks. Our results provide the evidence of VEGF and ICAM-1 expression curves in time course in atherosclerotic rats, which indicated different regulatory mechanisms of VEGF and ICAM-1 expression in atherogenesis.