From endothelial dysfunction to atherosclerosis

Improving cardiovascular outcomes in rheumatic diseases: therapeutic potential of circulating endothelial progenitor cells

Patients with Rheumatoid Arthritis (RA) and Systemic Lupus Erythematosus (SLE) have a significantly increased risk of cardiovascular disease (CVD). The reason for this is unclear but may be due, at least in part, to the failure of endothelial repair mechanisms. Over the last 15 years there has been much interest in the mechanisms of endothelial renewal and its potential as a therapy for CVD. In the circulation there are two distinct populations of cells; myeloid angiogenic cells (MACs) which augment repair by the paracrine secretion of angiogenic factors, and outgrowth endothelial cells (OECs) which are true endothelial progenitor cells (EPCs) and promote vasculogenesis by differentiating into mature endothelium. There are marked abnormalities in the number and function of these cells in patients with RA and SLE. Inflammatory cytokines including interferon-alpha (IFNα) and tumour-necrosis factor alpha (TNFα) both impair MAC and OEC function ex vivo and may therefore contribute to the CVD risk in these patients. Whilst administration of mononuclear cells, MACs and other progenitors has improved cardiovascular outcomes in the acute setting, this is not a viable option in chronic disease. The pharmacological manipulation of MAC/OEC function in vivo however has the potential to significantly improve endothelial repair and thus reduce CVD in this high risk population.

Toll-like receptor 2/6 agonist macrophage-activating lipopeptide-2 promotes reendothelialization and inhibits neointima formation after vascular injury

OBJECTIVE

Reendothelialization after vascular injury (ie, balloon angioplasty or stent implantation) is clinically extremely relevant to promote vascular healing. We here investigated the therapeutic potential of the toll-like receptor 2/6 agonist macrophage-activating lipopeptide (MALP)-2 on reendothelialization and neointima formation in a murine model of vascular injury.

APPROACH AND RESULTS

The left common carotid artery was electrically injured, and reendothelialization was quantified by Evans blue staining after 3 days. A single injection of MALP-2 (1 or 10 µg, IV) after vascular injury accelerated reendothelialization (P<0.001). Proliferation of endothelial cells at the wound margins determined by 5-ethynyl-2'-deoxyuridine incorporation was significantly higher in MALP-2-treated animals (P<0.05). Furthermore, wire injury-induced neointima formation of the left common carotid artery was completely prevented by a single injection of MALP-2 (10 µg, IV). In vitro, MALP-2 induced proliferation (BrdU incorporation) and closure of an artificial wound of endothelial cells (P<0.05) but not of smooth muscle cells. Protein array and ELISA analysis of isolated primary endothelial cells and ex vivo stimulated carotid segments revealed that MALP-2 stimulated the release of multiple growth factors and cytokines predominantly from endothelial cells. MALP-2 induced a strong activation of the mitogen-activated protein kinase cascade in endothelial cells, which was attenuated in smooth muscle cells. Furthermore, MALP-2 significantly enhanced circulating monocytes and hematopoietic progenitor cells.

CONCLUSIONS

The toll-like receptor 2/6 agonist MALP-2 promotes reendothelialization and inhibits neointima formation after experimental vascular injury via enhanced proliferation and migration of endothelial cells. Thus, MALP-2 represents a novel therapeutic option to accelerate reendothelialization after vascular injury.

The autoimmune side of heart and lung diseases

The elevated cardiovascular morbidity in rheumatoid arthritis, systemic lupus erythematosus, and the antiphospholipid syndrome is well known, as well as the pulmonary involvement observed in these conditions and to a major extent in systemic sclerosis. These manifestations constitute a major challenge for clinicians involved in patient management. Moreover, several issues regarding the link between autoimmune rheumatic diseases and cardio pulmonary morbidity remain largely enigmatic. The mechanistic role of certain autoantibodies frequently observed in association with heart and lung diseases or the pathogenetic link between chronic inflammation and the pathways leading to atherosclerosis or pulmonary vascular changes are yet to be elucidated. As such, these questions as well as treatment strategies are of common interest to rheumatologists, immunologist, pulmonologists, and cardiologists and thus call for an interdisciplinary approach. This paradigm has been well established for rare conditions such as the Churg-Strauss syndrome. Nowadays, it seems that this approach should be expanded to encompass more common conditions such as coronary heart disease, pulmonary arterial hypertension or dilated cardiomyopathy. The present issue of Clinical Reviews in Allergy and Immunology addresses the new knowledge and concepts of autoimmune-related cardiopulmonary diseases. The issue derives from the 2010 International Autoimmunity Meeting held in Ljubljana, Slovenia and is thus timely and dedicated to the latest developments in this new multidisciplinary field.

Auto-antibodies as emergent prognostic markers and possible mediators of ischemic cardiovascular diseases

During the last 15 years, a growing body of evidence supported the fact that auto-antibodies represent not only emergent markers but also active mediators of cardiovascular disease (CVD), clinically represented mostly by acute coronary syndrome (ACS) and stroke. There is a contrasted relationship between auto-antibodies and CVD, some being protective, while others acting as potential risk factors. Therefore, we performed a review of the literature on the respective cardiovascular prognostic value of the most relevant auto-antibodies in ACS and stroke, and their putative pathophysiological properties in atherogenesis. This review highlights auto-antibodies as active modulators of the innate immune system in atherogenesis (either toward a pro- or anti-inflammatory response), or by affecting basal heart rate regulation (anti-apoA-1 IgG). Given their apparent prognostic independency towards traditional cardiovascular risk factors, the data available in the literature indicates that some of those auto-antibodies could be of valuable help for cardiovascular risk stratification in the future, especially because their deleterious effects have been shown to be potentially abrogated in vivo and in vitro by existing therapeutic modalities. Although evidence in humans is currently lacking, these studies may open innovative therapeutic perspectives for CVD in the future.

Inhibition of the renin-angiotensin system for lowering coronary artery disease risk

The renin-angiotensin system when activated exerts proliferative and pro-inflammatory actions and thereby contributes to progression of atherosclerosis, including that occurring in the coronary arteries. It thus contributes as well to coronary artery disease (CAD). Several clinical trials have examined effects of renin-angiotensin system inhibition for primary and secondary prevention of coronary heart disease. These include important trials such as HOPE, EUROPA and PEACE using angiotensin converting enzyme inhibitors, VALIANT, OPTIMAAL and TRANSCEND using angiotensin receptor blockers, and the ongoing TOPCAT study in patients with preserved ejection fraction heart failure, many of who also have coronary artery disease. Data are unavailable as yet of effects of either direct renin inhibitors or the new angiotensin receptor/neprilysin inhibitor agents. Today, inhibition of the renin-angiotensin system is standard-of-care therapy for lowering cardiovascular risk in secondary prevention in high cardiovascular risk subjects.

Structure and activity study of egg protein ovotransferrin derived peptides (IRW and IQW) on endothelial inflammatory response and oxidative stress

Egg protein ovotransferrin derived peptides (IRW and IQW) can attenuate tumor necrosis factor (TNF) induced inflammatory responses and oxidative stress in endothelial cells. The present study investigates the structural requirements and molecular mechanisms underlying these events. Whereas IRW significantly inhibited TNF-induced up-regulation of intercellular cell adhesion molecule-I (ICAM-1) and vascular cell adhesion molecule-I (VCAM-1), IQW could inhibit only the up-regulation of ICAM-1. The anti-inflammatory effects of these peptides appeared to be mediated by the nuclear factor-κB (NF-κB) pathway, which was differentially regulated by IRW and IQW. Both IRW and IQW exhibited antioxidant effects as shown by reduction of TNF-induced superoxide generation. The structural integrity of these peptides was essential for their activities, because dipeptides or the combination of constituent amino acids did not exhibit the same effect. This study demonstrated the significance of the structural integrity of these two tripeptides in attenuating endothelial inflammation and oxidative stress, indicating their potential as nutraceuticals.

AFM investigation on Ox-LDL-induced changes in cell spreading and cell-surface adhesion property of endothelial cells

The integrity and adhesion properties of endothelium play vital roles during atherosclerosis. It is well known that oxidized low-density lipoprotein (Ox-LDL) influences many physiological activities or mechanical properties of endothelial cells. However, the effects of Ox-LDL on the integrity and nonspecific adhesion properties of endothelial cells are still unclear. In this study, using the topographical imaging and force measurement functions of atomic force microscopy (AFM), we found that Ox-LDL can transiently weaken the integrity of endothelium by impairing cell spreading of endothelial cells and decrease the attachment of irrelevant blood cells to endothelium by impairing the nonspecific adhesion property of endothelial cells. The AFM-based data provide important information for understanding the effects of Ox-LDL on endothelial cells or during atherogenesis.

Sitting and endothelial dysfunction: the role of shear stress

Sedentary activity is a modifiable life-style behavior and a key component in the etiology of atherosclerotic cardiovascular disease (ACVD). US adults and children spend more than half their waking time in sedentary pursuits. Sedentary activity has been shown to result in impaired insulin sensitivity, impaired metabolic function and attenuated endothelial function, which are classic markers of ACVD. Sedentary activity is defined as 'sitting without otherwise being active.' This behavior promotes reduced muscular activity of the lower extremities which decreases leg blood flow, increases blood pooling in the calf, augments mean arterial pressure, and deforms arterial segments resulting in low mean shear stress (SS). SS activates distinct physiological mechanisms which have been proposed to be protective against ACVD; specifically through a SS-induced endothelium-derived nitric oxide mechanism. Reduced bioavailability of nitric oxide creates a pro-oxidant milieu resulting in increased oxidative stress. There is sufficient evidence which demonstrates that endothelial function is attenuated in the presence of oxidative stress. Sedentary activity results in low SS in the lower extremities which may result in increased oxidative stress and impaired endothelial function. This review furthers the use of sitting as model to study the effects of inactivity, discusses possible physiological mechanisms and suggests future directions.

Stimulation of non-neuronal muscarinic receptors enhances chemerin/ChemR23 system in dysfunctional endothelial cells

AIMS

Endothelial cells play a pivotal role in vascular intimal inflammation during cardiovascular diseases. The chemerin/ChemR23 system in endothelial cells is one of physiological mechanisms that regulate inflammatory responses. Our previous studies indicated that stimulation of non-neuronal muscarinic receptor (NNMR) improved endothelial dysfunction. However, the relationship between the chemerin/ChemR23 signaling axis and NNMR in endothelial cell is poorly understood. Here, we first investigated whether the modulation of chemerin/ChemR23 signaling axis is involved in NNMR-mediated endothelial protection.

MAIN METHODS

Cultured rat aortic endothelial cells (RAECs) were used. The ChemR23 protein expression and chemerin secretion were measured using Western blot analysis. The gene expression level of ChemR23 was examined with reverse transcriptase PCR (RT-PCR). The production of nitric oxide (NO) was determined by a nitrate reductase assay kit.

KEY FINDINGS

A sharp decline of chemerin secretion and ChemR23 protein/gene expression was observed in RAECs after exposed to homocysteine at concentration of 0.5 mmol/L. Arecoline (10 μmol/L) pretreatment increased ChemR23 protein expression as well as mRNA expression, and enhanced the secretion of chemerin. Arecoline could also reverse the decreased ChemR23 mRNA expression induced by uric acid, high glucose, or oxidized low-density lipoprotein. Furthermore, the modulation of arecoline on chemerin/ChemR23 signaling axis was absolutely abolished in the presence of the nonselective muscarinic receptors antagonist atropine 1 μmol/L. Additionally, arecoline improved endothelial dysfunction by increasing the reduced NO production induced by uric acid, which was blocked by anti-ChemR23 antibody.

SIGNIFICANCE

The chemerin/ChemR23 signaling axis participates in NNMR-mediated protection against endothelial dysfunction in cardiovascular system.

Diabetes and cardiovascular disease: changing the focus from glycemic control to improving long-term survival

Diabetes mellitus (DM) is the fifth-leading cause of death worldwide and contributes to leading causes of death, cancer and cardiovascular disease, including CAD, stroke, peripheral vascular disease, and other vascular disease. While glycemic management remains a cornerstone of DM care, the co-management of hypertension, atherosclerosis, cardiovascular risk reduction, and prevention of long-term consequences associated with DM are now well recognized as essential to improve long-term survival. Clinical trial evidence substantiates the importance of glycemic control, low-density cholesterol-lowering therapy, blood pressure lowering, control of albuminuria, and comprehensive approaches targeting multiple risk factors to reduce cardiovascular risk. This article presents a review of the role of DM in the pathogenesis of atherosclerosis and cardiac dysfunction, recent evidence on the degree of glycemic control and mortality, and available evidence for a multifaceted approach to improve long-term outcomes for patients.

HLA class II is a factor in cardiovascular morbidity and mortality rates in patients with type 1 diabetes

AIMS/HYPOTHESIS

Patients with type 1 diabetes and kidney disease have a higher risk of cardiovascular events. HLA class II genes are expressed on infiltrated inflammatory cells and smooth-muscle cells in atherosclerotic plaques. We hypothesised that HLA class II haplotypes or genotypes might influence the risk of cardiovascular complications and death in Finnish type 1 diabetic patients.

METHODS

We included 3,082 patients with type 1 diabetes from the Finnish Diabetic Nephropathy Study. We analysed the 12 and ten most common HLA II haplo- and genotypes, respectively, using χ (2) tests. The positive findings were analysed with three differently adjusted regression models with cardiovascular morbidity and death as endpoints. Different kidney status groups were analysed separately.

RESULTS

At baseline, the common (DR1/10)-DQB1*05:01 haplotype (20.4%) and the (DR1/10)-DQB1*05:01/DRB1*04:01-DQB1*03:02 genotype (8.7%) were independently associated with cardiovascular disease in all kidney status groups, except in patients with normal AER. At follow-up (9.45 years; range 0.1-16.1 years), the (DR1/10)-DQB1*05:01/DRB1*04:01-DQB1*03:02 genotype was associated with cardiovascular mortality rates in patients with normal AER and microalbuminuria.

CONCLUSIONS/INTERPRETATION

The (DR1/10)-DQB1*05:01 haplotype and the (DR1/10)-DQB1*05:01/DRB1*04:01-DQB1*03:02 genotype are independently associated with cardiovascular events and death in Finnish type 1 diabetic patients.

Evaluation of the endothelial function in hypertensive patients with 13N-ammonia PET

BACKGROUND

Essential hypertension is one of the main risk factors for the development of coronary artery disease (CAD). Hypertension causes endothelial dysfunction which is considered an early sign for the development of CAD. Positron emission tomography is a non-invasive imaging technique that measures myocardial blood flow (MBF), allowing us to identify patients with endothelial dysfunction.

METHODS AND RESULTS

19 patients without comorbidities recently diagnosed hypertensive, as well as 21 healthy volunteers were studied. A three-phase (rest, cold pressor test, and adenosine-induced hyperemia) (13)N-ammonia PET was performed, and MBF was measured. Endothelial-Dependent Vasodilation Index, ΔMBF, and coronary flow reserve (CFR) were calculated for each patient. Hypertensive patients had a significantly higher systolic and diastolic blood pressures compared with the control group (134.6 ± 11.7/86.4 ± 10.6 mm Hg and 106.0 ± 11.8/71.4 ± 6.6 mm Hg, respectively, P < .001). The ENDEVI (1.28 ± 0.26 vs 1.79 ± 0.30, P < .001), the ΔMBF (0.81 ± 0.50 vs 0.25 ± 0.21, P < .001) and the CFR (2.18 ± 0.88 vs 3.17 ± 0.68, P = .001) were significantly lower in the hypertensive patients compared to the control group, 84% of the former group had endothelial dysfunction i.e., ENDEVI < 1.5 and 58% had vasomotor abnormalities, i.e., CFR < 2.5.

CONCLUSIONS

In this study, we showed that recently diagnosed hypertensive patients have coronary endothelial dysfunction and vasomotor disturbances which are early signs for the development of CAD.

Near-infrared fluorescence imaging of mouse myocardial microvascular endothelium using Cy5.5-lectin conjugate

Cy5.5-lectin, a non-toxic conjugate, combines the benefits of near-infrared (NIR) imaging, such as significant reduction of background fluorescence and increased tissue depth penetration, with its affinity for vascular endothelial cells. When compared to endothelial staining methods using FITC-lectin and ICAM2 antibodies, Cy5.5-lectin was confirmed to specifically bind endothelial cells and produce a fluorescence signal both in real-time and post-infusion. Ex-vivo experiments with isolated hearts demonstrated that binding was limited to perfused areas of the myocardium. With mouse in-vivo tail-vein injections, other organs such as the liver, spleen, and kidney were also stained and yielded similar quality images of the heart.

Effect of HSP65 on the expression of adhesion molecules in mice heart endothelial cells

This study aims to research the effect of HSP65 on the expression of adhesion molecules in activated mice heart endothelial cells (MHECs), which were from myocardial tissue of newborn animals. We used different concentrations of LPS as potent inducers to stimulate MHECs, adhesion molecule expression in vitro, including intercellular adhesion molecule-1 (ICAM-1), vascular adhesion molecule-1 (VCAM-1), E-, and P-selectins, then compared the mRNA and protein levels of adhesion molecules expression with or without HSP65 treatment at different levels. The optimal concentration of LPS to induce MHECs adhesion molecule expression is 100 ng/ml; HSP65 treatment significantly reduced the mRNA and protein levels of MHECs' ICAM-1, VCAM-1, E-, and P-selectins expression (p < 0.05), and the optimal concentration of HSP65 in inhibiting MHECs activation is 0.8 ng. HSP65 has the inhibitory effect on adhesion molecules expression in activated MHECs.

Nitric oxide-mediated coronary flow regulation in patients with coronary artery disease: recent advances

Nitric oxide (NO) formed via endothelial NO synthase (eNOS) plays crucial roles in the regulation of coronary blood flow through vasodilatation and decreased vascular resistance, and in inhibition of platelet aggregation and adhesion, leading to the prevention of coronary circulatory failure, thrombosis, and atherosclerosis. Endothelial function is impaired by several pathogenic factors including smoking, chronic alcohol intake, hypercholesterolemia, obesity, hyperglycemia, and hypertension. The mechanisms underlying endothelial dysfunction include reduced NO synthase (NOS) expression and activity, decreased NO bioavailability, and increased production of oxygen radicals and endogenous NOS inhibitors. Atrial fibrillation appears to be a risk factor for endothelial dysfunction. Endothelial dysfunction is an important predictor of coronary artery disease (CAD) in humans. Penile erectile dysfunction, associated with impaired bioavailability of NO produced by eNOS and neuronal NOS, is also considered to be highly predictive of ischemic heart disease. There is evidence suggesting an important role of nitrergic innervation in coronary blood flow regulation. Prophylactic and therapeutic measures to eliminate pathogenic factors inducing endothelial and nitrergic nerve dysfunction would be quite important in preventing the genesis and development of CAD.

Spirulina improves non-alcoholic steatohepatitis, visceral fat macrophage aggregation, and serum leptin in a mouse model of metabolic syndrome

BACKGROUND

Nutritional approaches are sought to overcome the limits of pioglitazone in metabolic syndrome and non-alcoholic fatty liver disease. Spirulina, a filamentous unicellular alga, reduces serum lipids and blood pressure while exerting antioxidant effects.

AIM

To determine whether Spirulina may impact macrophages infiltrating the visceral fat in obesity characterizing our metabolic syndrome mouse model induced by the subcutaneous injection treatment of monosodium glutamate.

METHODS

Mice were randomized to receive standard food added with 5% Spirulina, 0.02% pioglitazone, or neither. We tested multiple biochemistry and histology (both liver and visceral fat) readouts at 24 weeks of age.

RESULTS

Data demonstrate that both the Spirulina and the pioglitazone groups had significantly lower serum cholesterol and triglyceride levels and liver non-esterified fatty acid compared to untreated mice. Spirulina and pioglitazone were associated with significantly lower leptin and higher levels, respectively, compared to the control group. At liver histology, non-alcoholic fatty liver disease activity score and lipid peroxide were significantly lower in mice treated with Spirulina.

CONCLUSIONS

Spirulina reduces dyslipidaemia in our metabolic syndrome model while ameliorating visceral adipose tissue macrophages. Human studies are needed to determine whether this safe supplement could prove beneficial in patients with metabolic syndrome.

Improved Metabolic Control in Diabetes, HSP60, and Proinflammatory Mediators

The diabetes-atherosclerosis relationship remains to be fully defined. Repeated prolonged hyperglycemia, increased ROS production and endothelial dysfunction are important factors. One theory is that increased blood levels of heat shock protein (HSP)60 are proinflammatory, through activation of innate immunity, and contribute to the progression of vascular disease. It was hypothesized that improvement of diabetes control in patients presenting with metabolic syndrome would lower HSP60, and anti-HSP60 antibody levels and decrease inflammatory markers. Paired sera of 17 Italian patients, before and after intensive treatment, were assayed for cytokines, HSP60 and anti-HSP60 antibodies. As expected, intensive treatment was associated with a decrease in HgbA1C (P < 0.001) and BMI (P < 0.001). After treatment, there was a significant decrease in IL-6 (P < 0.05). HSP60 levels were before treatment −6.9 + 1.9, after treatment −7.1 + 2.0 ng/mL (P = ns). Overall HSP60 concentrations were lower than published reports. Anti-HSP60 antibody titers were high and did not decrease with treatment. In conclusion, improvement of diabetic control did not alter HSP60 concentrations or antiHSP60 antibody titers, but led to a reduction of IL-6 levels.

Beneficial effects of aged garlic extract and coenzyme Q10 on vascular elasticity and endothelial function: the FAITH randomized clinical trial

OBJECTIVE

Aged garlic extract (AGE) is associated with a significant decrease in atherosclerotic plaque progression and endothelial function improvement. Similarly, coenzyme Q10 (CoQ10) has significant beneficial effects on endothelial function. A stressful lifestyle is a well-known risk factor for the presence and progression of atherosclerosis. This study investigated the effect of AGE plus CoQ10 on vascular elasticity measured by pulse-wave velocity (PWV) and endothelial function measured by digital thermal monitoring (DTM) in firefighters.

METHODS

Sixty-five Los-Angeles County firefighters who met the eligibility criteria were enrolled in this placebo-controlled, double-blinded randomized trial. The firefighters were randomized to four tablets of AGE (300 mg/tablet) plus CoQ10 (30 mg/tablet) or placebo. The participants underwent quarterly visits and 1-year follow-up. PWV and DTM were measured at baseline and at the 1-year follow-up.

RESULTS

There were no significant differences in age, cardiovascular risk factors, PWV, and DTM between the AGE/CoQ10 and placebo groups at baseline (P > 0.5). At 1-y, PWV and DTM significantly improved in the AGE/CoQ10 compared with the placebo group (P < 0.05). After an adjustment for cardiovascular risk factors and statin therapy, the mean decrease in vascular stiffness (PWV) was 1.21 m/s in the AGE/CoQ10 compared with the placebo group (P = 0.005). Similarly, the mean increase in the area under the temperature curve, the DTM index of endothelial function, was 31.3 in the AGE/CoQ10 compared with the placebo group (P = 0.01).

CONCLUSION

The combination of AGE and CoQ10 was independently associated with significant beneficial effects on vascular elasticity and endothelial function in firefighters with high occupational stress, highlighting the important role of AGE and CoQ10 in atherosclerotic prevention of such individuals.

Effects of soya oligosaccharides and soya oligopeptides on lipid metabolism in hyperlipidaemic rats

In the present study, we aimed to examine the effects of soya oligosaccharides (SOS) and soya oligopeptides (SOP) on blood lipid levels, release of vasoactive substances, antioxidant activity and faecal bile acid (FBA) excretion in rats fed a high-fat diet (HFD). Male Sprague-Dawley rats were evenly divided into five groups according to diets as follows: regular diet (control), HFD, HFD enriched with 2 % of SOS (SOS), HFD enriched with 3 % of SOP (SOP) and HFD enriched with 2 % SOS and 3 % SOP (SOSP). The results showed that SOS and SOP significantly reduced plasma total cholesterol, LDL-cholesterol and TAG, whereas HDL-cholesterol concentration was significantly increased. Furthermore, SOS and SOP reduced plasma apoB, apoE and the apoB:apoAI ratio, whereas apoAI was significantly increased. Moreover, SOS and SOP also reduced plasma thromboxane A₂ (TXA₂) and the TXA₂:prostacyclin (PGI₂) ratio, whereas plasma PGI₂ and nitric oxide were significantly increased. In addition, SOS and SOP significantly reduced serum and liver malondialdehyde concentrations and increased FBA excretion. However, we did not observe obvious influences of SOS and SOP on superoxide dismutase activities in the liver of HFD-fed rats. The combination of 2 % SOS and 3 % SOP showed a more marked effect than SOS or SOP alone in improving the lipid profile, release of vasoactive substances and increasing FBA excretion (P < 0.05). In summary, SOS and SOP might help prevent atherosclerosis through improving abnormal blood lipid levels, regulating vasoactive substances and protecting against oxidative stress.

Fish oil and vascular endothelial protection: bench to bedside

Fish oil is recommended for the management of hypertriglyceridemia and to prevent secondary cardiovascular disorders. Fish oil is a major source of ω-3-polyunsaturated fatty acids (PUFAs) such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Clinical studies suggest that fish oil not only prevents the incidence of detrimental cardiovascular events, but also lowers the cardiovascular mortality rate. In addition to a classic lipid-lowering action, ω-3-PUFAs in fish oil could regulate blood pressure and enhance vascular integrity and compliance. Additionally, ω-3-PUFAs have the ability to protect vascular endothelial cells by decreasing oxidative stress, halting atherosclerotic events, and preventing vascular inflammatory and adhesion cascades. Intriguingly, recent studies have demonstrated that ω-3-PUFAs improve the function of vascular endothelium by enhancing the generation and bioavailability of endothelium-derived relaxing factor (nitric oxide) through upregulation and activation of endothelial nitric oxide synthase (eNOS). This certainly opens up a new area of research identifying potential mechanisms influencing fish oil-mediated functional regulatory action on vascular endothelium. We address in this review the potential of fish oil to prevent vascular endothelial dysfunction and associated cardiovascular disorders. Moreover, the mechanisms pertaining to fish oil-mediated eNOS activation and nitric oxide generation in improving endothelial function are delineated. We finally suggest the importance of further studies to determine the dose adjustment of fish oil with an optimal ratio of EPA and DHA for achieving consistent cardiovascular protection.

Prevalence of low ankle brachial index and its association with pulse pressure in an elderly Chinese population: a cross-sectional study

Background

We investigated the prevalence of low ankle brachial index (ABI) and the association of low ABI with pulse pressure among elderly community residents in China.

Methods

This population-based cross-sectional study was conducted in Beijing and recruited 2982 participants who were aged 60 years or older in 2007. Low ABI was defined as an ABI value less than 0.9 in either leg. Participants with or without stroke or coronary heart disease (CHD) were analyzed separately. The association between pulse pressure and low ABI was examined by using multiple logistic regression models.

Results

The prevalence of low ABI was 5.65% (4.24% among men and 6.52% among women; P = 0.0221) among participants without stroke or CHD and 10.91% (13.07% among men and 9.49% among women; P = 0.1328) among those with stroke or CHD. After adjusting for confounders, the odds ratio (95% CI) for each 5-mm Hg increase in pulse pressure was 1.19 (1.07, 1.33) and 1.10 (1.02, 1.20) for men and women, respectively, among participants without stroke or CHD and 1.17 (1.03, 1.34) and 1.15 (1.02, 1.30) for men and women with stroke or CHD. When pulse pressure was classified into quartiles and the lowest quartile was used as reference, the association between pulse pressure and low ABI remained positive in men and women.

Conclusions

Low ABI was prevalent among elderly Chinese, and pulse pressure was positively associated with low ABI.

Endothelium-specific SIRT1 overexpression inhibits hyperglycemia-induced upregulation of vascular cell senescence

The rapidly increasing prevalence of diabetes mellitus worldwide is one of the most serious and challenging health problems in the 21st century. Mammalian sirtuin 1 (SIRT1) has been shown to decrease high-glucose-induced endothelial cell senescence in vitro and prevent hyperglycemia-induced vascular dysfunction. However, a role for SIRT1 in prevention of hyperglycemia-induced vascular cell senescence in vivo remains unclear. We used endothelium-specific SIRT1 transgenic (SIRT1-Tg) mice and wild-type (WT) mice to construct a 40-week streptozotocin (STZ)-induced diabetic mouse model. In this mode, 42.9% of wild-type (WT) mice and 38.5% of SIRT1-Tg mice were successfully established as diabetic. Forty weeks of hyperglycemia induced significant vascular cell senescence in aortas of mice, as indicated by upregulation of expression of senescence-associated markers including p53, p21 and plasminogen activator inhibitor-1 (PAI-1). However, SIRT1-Tg diabetic mice displayed dramatically decreased expression of p53, p21 and PAI-1 compared with diabetic WT mice. Moreover, manganese superoxide dismutase expression (MnSOD) was significantly downregulated in the aortas of diabetic WT mice, but was preserved in diabetic SIRT1-Tg mice. Furthermore, expression of the oxidative stress adaptor p66Shc was significantly decreased in aortas of SIRT1-Tg diabetic mice compared with WT diabetic mice. Overall, these findings suggest that SIRT1-mediated inhibition of hyperglycemia-induced vascular cell senescence is mediated at least partly through the reduction of oxidative stress.

Effect of visfatin on the function of endothelial progenitor cells in high-fat-fed obese rats and investigation of its mechanism of action

The aim of this study was to study the quantity change of endothelial progenitor cells (EPCs) in obese rats fed a high-fat-diet and to investigate the correlation of EPC numbers with visfatin. The impact of visfatin on the quantity and function of EPCs were further investigated by cell culture methods. Male Wistar rats were fed on either a standard diet (NC group) or a high-fat diet (HF group) for 16 weeks. Serum visfatin, Lee's index and the protein expression of visfatin in viseral adipose tissue (VAT) were determined. Bone marrow EPCs in 2 groups of rats were isolated, cultured and counted. EPCs primarily cultured from control male Wistar rats were treated with different concentrations of visfatin. The quantity, migration and adhesion capacity of EPCs were evaluated after visfatin treatment. Protein expression of nuclear factor-κB (NF-κB) in the nuclei of EPCs was detected. After 16-week feeding, body weight, serum visfatin, Lee's index and visfatin contents in viseral fat were significantly increased in the HF group compared with NC group (P<0.01 or P<0.05). The quantity of EPCs primarily cultured from rats in HF group was lower than that in NC group. The quantity of EPCs was negatively correlated with serum visfatin levels, visceral fat, fasting blood glucose, HOMA-IR, total cholesterol, triglyceride and body weight (P<0.01). In cultured EPCs, visfatin significantly increased the protein expression of NF-κB in EPC nuclei (P<0.01) in a dose-dependent manner. The migration and adhesion capacity were impaired by visfatin treatment (P<0.01). In conclusion, bone marrow-derived EPCs decrease in number and have impaired migration and adhesion function in high-fat-fed obese rats, along with increased serum visfatin and protein contents in VAT. Visfatin may have an impact on the quantity and function of EPCs through the NF-κB pathway.

Unique vascular protective properties of natural products: supplements or future main-line drugs with significant anti-atherosclerotic potential?

Natural health products (NHP) which include minerals, vitamins and herbal remedies are not generally considered by medical practitioners as conventional medicines and as such are not frequently prescribed by health centre's as either main-line or supplemental treatments. In the field of cardiovascular medicine, studies have shown that typically, less than half of patients suffering from coronary syndromes chose to take any form of NHP supplement and these products are rarely recommended by their medical practitioner. Vascular/endothelial cell damage is a key instigator of coronary arterial plaque development which often culminates in thrombosis and myocardial infarction (MI). Current treatment for patients known to be at risk of primary or secondary (MI) includes lipid lowering statins, anti-clotting agents (e.g. tissue plasminogen activator; tPA) and drugs for stabilization of blood pressure such as beta-blockers. However, evidence has been building which suggests that components of at least several NHP (e.g. aged garlic extract (AGExt), resveratrol and green tea extracts (GTE)) may have significant vascular protective effects through reduction of oxidative stress, lowering of blood pressure, reduction in platelet aggregation, vasodilation and inhibition of abnormal angiogenesis. Therefore, in this review we will discuss in detail the potential of these substances (chosen on the basis of their potency and complimentarity) as anti-atherosclerotic agents and the justification for their consideration as main-line additional supplements or prescriptions.

Effect of cocoa/chocolate ingestion on brachial artery flow-mediated dilation and its relevance to cardiovascular health and disease in humans

Prospective studies indicate that high intake of dietary flavanols, such as those contained in cocoa/chocolate, are associated with reduced rates of cardiovascular-related morbidity and mortality in humans. Numerous mechanisms may underlie these associations such as favorable effects of flavanols on blood pressure, platelet aggregation, thrombosis, inflammation, and the vascular endothelium. The brachial artery flow-mediated dilation (FMD) technique has emerged as a robust method to quantify endothelial function in humans. Collectively, the preponderance of evidence indicates that FMD is a powerful surrogate measure for firm cardiovascular endpoints, such as cardiovascular-related mortality, in humans. Thus, literally thousands of studies have utilized this technique to document group differences in FMD, as well as to assess the effects of various interventions on FMD. In regards to the latter, numerous studies indicate that both acute and chronic ingestion of cocoa/chocolate increases FMD in humans. Increases in FMD after cocoa/chocolate ingestion appear to be dose-dependent such that greater increases in FMD are observed after ingestion of larger quantities. The mechanisms underlying these responses are likely diverse, however most data suggest an effect of increased nitric oxide bioavailability. Thus, positive vascular effects of cocoa/chocolate on the endothelium may underlie (i.e., be linked mechanistically to) reductions in cardiovascular risk in humans.

Potential health benefits of moderate alcohol consumption: current perspectives in research

The benefits of moderate amounts of alcohol for a better health and longer life expectancy compared with abstinence have been suggested by the findings of numerous studies. However, controversies have emerged regarding the influence of confounding factors and the systematic errors that might have been inadvertently disregarded in the early studies. This review includes a description of the findings of those research studies published in the last 5 years on the effects of moderate alcohol consumption on all-cause mortality, CVD and inflammation, the immune system, insulin sensitivity, non-alcoholic fatty liver disease (NAFLD) and cancer. Promising evidences exist from both animal studies and human clinical trials regarding intermediate end-points of CHD and insulin sensitivity, such as HDL, adiponectin or fibrinogen. However, controversies and inconsistent findings exist regarding many of these diseases and related functions and biomarkers. Further research and human randomised-controlled trials with adequate standardisation of the study conditions are necessary in order to draw a comparison between studies, establish the causal effect of moderate alcohol intake on disease protection and reach consensus on the circumstances that allow the recommendation of moderate alcohol habitual intakes as a strategy for health maintenance.

Peroxisome proliferator-activated receptor-γ and the endothelium: implications in cardiovascular disease

Peroxisome proliferator-activated receptors-γ (PPARγs) are ligand-activated transcription factors that play a crucial regulatory role in the transcription of a large number of genes involved in lipid metabolism and inflammation. In addition to physiological ligands, synthetic ligands (the thiazoledinediones) have been developed. In spite of the much publicized adverse cardiovascular effects of one such thiazoledinedione (rosiglitazone), PPARγ activation may have beneficial cardiovascular effects. In this article we review the effects of PPARγ activation on the endothelium with special emphasis on the possible implications in cardiovascular disease. We discuss its possible role in inflammation, vasomotor function, thrombosis, angiogenesis, vascular aging and vascular rhythm. We also briefly review the clinical implications of these lines of research.

Endothelial expression of human ABCA1 in mice increases plasma HDL cholesterol and reduces diet-induced atherosclerosis

The role of endothelial ABCA1 expression in reverse cholesterol transport (RCT) was examined in transgenic mice, using the endothelial-specific Tie2 promoter. Human ABCA1 (hABCA1) was significantly expressed in endothelial cells (EC) of most tissues except the liver. Increased expression of ABCA1 was not observed in resident peritoneal macrophages. ApoA-I-mediated cholesterol efflux from aortic EC was 2.6-fold higher (P < 0.0001) for cells from transgenic versus control mice. On normal chow diet, Tie2 hABCA1 transgenic mice had a 25% (P < 0.0001) increase in HDL-cholesterol (HDL-C) and more than a 2-fold increase of eNOS mRNA in the aorta (P < 0.04). After 6 months on a high-fat, high-cholesterol (HFHC) diet, transgenic mice compared with controls had a 40% increase in plasma HDL-C (P < 0.003) and close to 40% decrease in aortic lesions (P < 0.02). Aortas from HFHC-fed transgenic mice also showed gene expression changes consistent with decreased inflammation and apoptosis. Beneficial effects of the ABCA1 transgene on HDL-C levels or on atherosclerosis were absent when the transgene was transferred onto ApoE or Abca1 knockout mice. In summary, expression of hABCA1 in EC appears to play a role in decreasing diet-induced atherosclerosis in mice and is associated with increased plasma HDL-C levels and beneficial gene expression changes in EC.

Hypotensive effect of atorvastatin in hypertensive patients: the association among flow-mediated dilation, oxidative stress and endothelial dysfunction

INTRODUCTION

To investigate the hypothesis that atorvastatin decreases blood pressure (BP) values and improves endothelial function assessed by flow-mediated dilation (FMD) in normolipidaemic hypertensive patients.

MATERIAL AND METHODS

Fifty-six hypertensive patients were randomized in a 2 : 1 proportion to atorvastatin (80 mg/day/3 months; group A; n = 39) or previous standard anti-hypertensive therapy (group B), which means the patients were treated with angiotensin-converting enzyme inhibitors, diuretics, β-blockers, calcium antagonists and angiotensin receptor blockers. The study had a crossover design: after 3 months, both groups were changed (group A* stopped and group B* started atorvastatin treatment). Nitric oxide (NO), total antioxidant status (TAS), endothelin-1 (ET-1), and peroxide concentrations as well as FMD were measured before, after 3 and after 6 months of treatment. Atorvastatin added to existing treatment decreased BP in both groups.

RESULTS

Flow-mediated dilation improved in both statin-treated groups, but only significantly in group B* (from 11.9 ±8.3% to 22.1 ±9.0%; p < 0.05). In patients with FMD improvement, there was a greater BP reduction. After treatment discontinuation, FMD significantly decreased (from 19.6 ±12.6% to 13.0 ±10.5%; p < 0.05), which was consistent with BP increase. Changes in FMD were not significantly related to the increase in NO and TAS concentrations and decrease in ET-1 and peroxides measurements.

CONCLUSIONS

The hypotensive effect of atorvastatin is associated with FMD improvement in normolipidaemic, hypertensive patients. Although this could be related to changes in oxidative stress and endothelial function, this was not demonstrated in this study and warrants further investigation.

Human endothelial progenitor cells isolated from COPD patients are dysfunctional

Cardiovascular disease is the leading cause of morbidity and mortality in patients with moderate-to-severe chronic obstructive pulmonary disease (COPD). More than 44% of these patients present with generalized atherosclerosis at autopsy. It is accepted that endothelial progenitor cells (EPCs) participate in the repair of dysfunctional endothelium and thus protects against atherosclerosis. However, whether COPD affects the repairing capacity of EPCs is unknown. Therefore, the objective of this study was to determine whether and how EPCs are involved in the vascular repair process in patients with COPD. In our study, EPCs from 25 COPD and 16 control patients were isolated by Ficoll density-gradient centrifugation and identified using fluorescence activated cell sorting. Transwell Migratory Assay was performed to determine the number of EPC colony-forming units and the adherent capacity late-EPCs to human umbilical vein endothelial cells. Following arterial damage in NOD/SCID mice, the number of EPCs incorporated at the injured vascular site was determined using a fluorescence microscope. We found that the number of EPC clusters and cell migration, as well as the expression of CXCR4, was significantly decreased in patients with COPD. Additionally, the number of late-EPCs adherent to HUVEC tubules was significantly reduced, and fewer VEGFR2(+)-staining cells were incorporated into the injured site in COPD patients. Our study demonstrates that EPC capacity of repair was affected in COPD patients, which may contribute to altered vascular endothelium in this patient population.

Contrast stress echocardiography in hypertensive heart disease

Hypertension is associated with atherosclerosis and cardiac and vascular structural and functional changes. Myocardial ischemia may arise in hypertension independent of coronary artery disease through an interaction between several pathophysiological mechanisms, including left ventricular hypertrophy, increased arterial stiffness and reduced coronary flow reserve associated with microvascular disease and endothelial dysfunction. The present case report demonstrates how contrast stress echocardiography can be used to diagnose myocardial ischemia in a hypertensive patient with angina pectoris but without significant obstructive coronary artery disease. The myocardial ischemia was due to severe resistant hypertension complicated with concentric left ventricular hypertrophy and increased arterial stiffness.

Subcellular signaling in the endothelium: cyclic nucleotides take their place

When lecturing on the topic of cellular signaling I have had occasion to ask the class for examples of cellular processes NOT impacted by cyclic AMP (cAMP) and am struck by how few examples exist. Indeed, studies spanning the past 60 years have detailed how this ubiquitous second messenger impacts virtually all cellular processes, including intermediary metabolism, contractility, motility, proliferation, and gene expression in most mammalian cells. Since the hydrophobic cAMP could in principle diffuse rapidly throughout the cell once formed, the remarkable spatial and temporal specificity of its numerous actions in cells is truly impressive. Herein I introduce the main players involved in coordinating actions of cAMP in vascular endothelial cells (VECs), and focus on the increasing awareness of the dominant role that cyclic nucleotide phosphodiesterases (PDEs), the sole cellular enzymes capable of hydrolytically inactivating cAMP, play in fostering this specificity.

Serum lipid profiles are associated with disability and MRI outcomes in multiple sclerosis

Background

The breakdown of the blood-brain-barrier vascular endothelium is critical for entry of immune cells into the MS brain. Vascular co-morbidities are associated with increased risk of progression. Dyslipidemia, elevated LDL and reduced HDL may increase progression by activating inflammatory processes at the vascular endothelium.

Objective

To assess the associations of serum lipid profile variables (triglycerides, high and low density lipoproteins (HDL, LDL) and total cholesterol) with disability and MRI measures in multiple sclerosis (MS).

Methods

This study included 492 MS patients (age: 47.1 ± 10.8 years; disease duration: 12.8 ± 10.1 years) with baseline and follow-up Expanded Disability Status Score (EDSS) assessments after a mean period of 2.2 ± 1.0 years. The associations of baseline lipid profile variables with disability changes were assessed. Quantitative MRI findings at baseline were available for 210 patients.

Results

EDSS worsening was associated with higher baseline LDL (p = 0.006) and total cholesterol (p = 0.001, 0.008) levels, with trends for higher triglyceride (p = 0.025); HDL was not associated. A similar pattern was found for MSSS worsening. Higher HDL levels (p < 0.001) were associated with lower contrast-enhancing lesion volume. Higher total cholesterol was associated with a trend for lower brain parenchymal fraction (p = 0.033).

Conclusions

Serum lipid profile has modest effects on disease progression in MS. Worsening disability is associated with higher levels of LDL, total cholesterol and triglycerides. Higher HDL is associated with lower levels of acute inflammatory activity.

A new look at the renin-angiotensin system--focusing on the vascular system

The renin-angiotensin system (RAS), critically involved in the control of blood pressure and volume homeostasis, is a dual system comprising a circulating component and a local tissue component. The rate limiting enzyme is renin, which in the circulating RAS derives from the kidney to generate Ang II, which in turn regulates cardiovascular function by binding to AT(1) and AT(2) receptors on cardiac, renal and vascular cells. The tissue RAS can operate independently of the circulating RAS and may be activated even when the circulating RAS is suppressed or normal. A functional tissue RAS has been identified in brain, kidney, heart, adipose tissue, hematopoietic tissue, gastrointestinal tract, liver, endocrine system and blood vessels. Whereas angiotensinsinogen, angiotensin converting enzyme (ACE), Ang I and Ang II are synthesized within these tissues, there is still controversy as to whether renin is produced locally or whether it is taken up from the circulation, possibly by the (pro)renin receptor. This is particularly true in the vascular wall, where expression of renin is very low. The exact function of the vascular RAS remains elusive, but may contribute to fine-tuning of vascular tone and arterial structure and may amplify vascular effects of the circulating RAS, particularly in pathological conditions, such as in hypertension, atherosclerosis and diabetes. New concepts relating to the vascular RAS have recently been elucidated including: (1) the presence of functionally active Ang-(1-7)-Mas axis in the vascular system, (2) the importance of the RAS in perivascular adipose tissue and cross talk with vessels, and (3) the contribution to vascular RAS of Ang II derived from immune and inflammatory cells within the vascular wall. The present review highlights recent progress in the RAS field, focusing on the tissue system and particularly on the vascular RAS.

Purified anthocyanin supplementation improves endothelial function via NO-cGMP activation in hypercholesterolemic individuals

BACKGROUND

Anthocyanins have been shown to improve endothelial function in animal models. However, whether these compounds have similar beneficial effects in humans is largely unknown.

METHODS

In a short-term crossover study, 12 hypercholesterolemic individuals were given oral anthocyanins (320 mg) isolated from berries or placebo. Brachial artery flow-mediated dilation (FMD) was assessed before and after the intervention. In a long-term intervention trial (12 weeks), 150 hypercholesterolemic individuals were given anthocyanins (320 mg/day, n = 75) or placebo (n = 75), after which we measured FMD, plasma cGMP, and other serum biomarkers. Another short-term intervention was conducted in the presence of NO-cGMP inhibitors in 6 people and in a rat aortic ring model (n = 8).

RESULTS

Significant increases of FMD from 8.3% (0.6%) at baseline to 11.0% (0.8%) at 1 h and 10.1% (0.9%) at 2 h were observed after short-term anthocyanin consumption, concomitantly with increases of plasma anthocyanin concentrations (P < 0.05). In the study participants who received long-term anthocyanin intervention, compared with the control group, we observed significant increases in the FMD (28.4% vs 2.2%), cGMP (12.6% vs -1.2%), and HDL-cholesterol concentrations, but decreases in the serum soluble vascular adhesion molecule-1 and LDL cholesterol concentrations (P < 0.05). The changes in the cGMP and HDL cholesterol concentrations positively correlated with FMD in the anthocyanin group (P < 0.05). In the presence of NO-cGMP inhibitors, the effects of anthocyanin on endothelial function were abolished in human participants and in a rat aortic ring model.

CONCLUSIONS

Anthocyanin supplementation improves endothelium-dependent vasodilation in hypercholesterolemic individuals. This effect involves activation of the NO-cGMP signaling pathway, improvements in the serum lipid profile, and decreased inflammation.

Plasma klotho and cardiovascular disease in adults

OBJECTIVES

To determine whether plasma klotho, a recently discovered hormone that has been implicated in atherosclerosis, is related to prevalent cardiovascular disease (CVD) in adults.

DESIGN

Cross-sectional.

SETTING

Population-based sample of adults residing in Tuscany, Italy.

PARTICIPANTS

One thousand twenty-three men and women aged 24 to 102 participating in the Invecchiare in Chianti (InCHIANTI) study.

MEASUREMENTS

Anthropometric measures, plasma klotho, fasting plasma total, high-density lipoprotein cholesterol (HDL-C), triglycerides, glucose, creatinine, C-reactive protein (CRP). Clinical measures: medical assessment, diabetes mellitus, hypertension, coronary heart disease, heart failure, stroke, peripheral artery disease, cancer, chronic kidney disease. Logistic regression models were used to examine the relationship between plasma klotho and prevalent CVD.

RESULTS

Of 1,023 participants, 259 (25.3%) had CVD. Median (25th, 75th percentile) plasma klotho concentrations were 676 pg/mL (530, 819 pg/mL). Plasma klotho was correlated with age (correlation coefficient (r) = -0.14, P < .001), HDL-C (r = 0.11, P<.001), and CRP (r = -0.10, P < .001) but not systolic blood pressure, fasting plasma glucose, or renal function. Plasma klotho age-adjusted geometric means were 626 pg/mL (95% confidence interval (CI) = 601-658 pg/mL) in participants with CVD and 671 pg/mL (95% CI = 652-692 pg/mL) in those without CVD (P = .001). Adjusting for traditional cardiovascular risk factors (age, sex, smoking, total cholesterol, HDL-C, systolic blood pressure, and diabetes mellitus), log plasma klotho was associated with prevalent CVD (odds ratio per 1 standard deviation increase = 0.85, 95% CI = 0.72-0.99).

CONCLUSION

In community-dwelling adults, higher plasma klotho concentrations are independently associated with a lower likelihood of having CVD.

Influence of obesity and metabolic dysfunction on the endothelial control in the coronary circulation

Diseases of the coronary circulation remain the leading cause of death in Western society despite impressive advances in diagnosis, pharmacotherapy and post-event management. Part of this statistic likely stems from a parallel increase in the prevalence of obesity and metabolic dysfunction, both significant risk factors for coronary disease. Obesity and diabetes pose unique challenges for the heart and their impact on the coronary vasculature remains incompletely understood. The vascular endothelium is a major interface between arterial function and the physical and chemical components of blood flow. Proper function of the endothelium is necessary to preserve hemostasis, maintain vascular tone and limit the extent of vascular diseases such as atherosclerosis. Given its central role in vascular health, endothelial dysfunction has been the source of considerable research interest in diabetes and obesity. In the current review, we will examine the pathologic impact of obesity and diabetes on coronary function and the extent to which these two factors impact endothelial function. This article is part of a Special Issue entitled "Coronary Blood Flow".