Overweight and obese humans demonstrate increased vascular endothelial NAD(P)H oxidase-p47(phox) expression and evidence of endothelial oxidative stress

Sprint interval and endurance training are equally effective in increasing muscle microvascular density and eNOS content in sedentary males

Sprint interval training (SIT) has been proposed as a time efficient alternative to endurance training (ET) for increasing skeletal muscle oxidative capacity and improving certain cardiovascular functions. In this study we sought to make the first comparisons of the structural and endothelial enzymatic changes in skeletal muscle microvessels in response to ET and SIT. Sixteen young sedentary males (age 21 ± SEM 0.7 years, BMI 23.8 ± SEM 0.7 kg m(-2)) were randomly assigned to 6 weeks of ET (40-60 min cycling at ∼65% , 5 times per week) or SIT (4-6 Wingate tests, 3 times per week). Muscle biopsies were taken from the m. vastus lateralis before and following 60 min cycling at 65% to measure muscle microvascular endothelial eNOS content, eNOS serine(1177) phosphorylation, NOX2 content and capillarisation using quantitative immunofluorescence microscopy. Whole body insulin sensitivity, arterial stiffness and blood pressure were also assessed. ET and SIT increased skeletal muscle microvascular eNOS content (ET 14%; P < 0.05, SIT 36%; P < 0.05), with a significantly greater increase observed following SIT (P < 0.05). Sixty minutes of moderate intensity exercise increased eNOS ser(1177) phosphorylation in all instances (P < 0.05), but basal and post-exercise eNOS ser(1177) phosphorylation was lower following both training modes. All microscopy measures of skeletal muscle capillarisation (P < 0.05) were increased with SIT or ET, while neither endothelial nor sarcolemmal NOX2 was changed. Both training modes reduced aortic stiffness and increased whole body insulin sensitivity (P < 0.05). In conclusion, in sedentary males SIT and ET are effective in improving muscle microvascular density and eNOS protein content.

Effect of sulfasalazine on inflammation and endothelial function in patients with established coronary artery disease

Inflammation is critical for atherosclerosis development and may be a target for risk-reduction therapy. In experimental studies, activation of the inflammatory regulator, nuclear factor kappa B (NFlB), contributes to endothelial activation and reduced nitric oxide production. We treated patients with coronary artery disease with sulfasalazine, an inhibitor of NFκB, and placebo in a randomized, double-blind, crossover study design. Brachial artery flow-mediated dilation (FMD) and digital vascular function were measured at baseline and after each 6-week treatment period. Of the 53 patients enrolled in the crossover study, 32 (age 60 ± 10, 22% female) completed all the visits, with a high rate of study withdrawal due to gastrointestinal side effects. In a subset of 10 participants, we compared the effects of 4 days of sulfasalazine treatment (n = 5) to no treatment (n = 5) on NFκB-regulated gene expression in peripheral blood mononuclear cells. Tumor necrosis factor α-stimulated expression of CD69 and NFlB subunit p50 was significantly blunted after 4 days of sulfasalazine treatment but not after no treatment. However, FMD and digital vasodilator response did not significantly change from baseline with long-term sulfasalazine treatment. Short-term sulfasalazine inhibited NFlB activity; however, long-term treatment was poorly tolerated and did not improve endothelial function. Our findings suggest that sulfasalazine therapy is not the optimal anti-inflammatory treatment for reversing endothelial dysfunction in cardiovascular disease. Further studies are warranted to investigate the potential for NFlB inhibition to reduce cardiovascular risk.

Obesity and oxidative stress predict AKI after cardiac surgery

Obesity increases oxidative stress, endothelial dysfunction, and inflammation, but the effect of obesity on postoperative AKI is not known. We examined the relationship between body mass index (BMI) and AKI in 445 patients undergoing cardiac surgery and whether oxidative stress (F(2)-isoprostanes), inflammation (IL-6), or antifibrinolysis (plasminogen activator inhibitor-1 [PAI-1]) contribute to any identified relationship. Overall, 112 (25%) of the 445 patients developed AKI. Higher BMI was independently associated with increased odds of AKI (26.5% increase per 5 kg/m(2) [95% confidence interval, 4.3%-53.4%]; P=0.02). Baseline F(2)-isoprostane (P=0.04), intraoperative F(2)-isoprostane (P=0.003), and intraoperative PAI-1 (P=0.04) concentrations also independently predicted AKI. BMI no longer predicted AKI after adjustment for the effect of F(2)-isoprostanes, suggesting that obesity may affect AKI via effects on oxidative stress. In contrast, adjustment for IL-6 or PAI-1 did not substantially alter the association between BMI and AKI. Further, deconstruction of the obesity-AKI relationship into direct (i.e., independent of candidate pathways) and indirect (i.e., effect of BMI on AKI via each candidate pathway) effects indicated that F(2)-isoprostanes, but not IL-6 or PAI-1, partially mediate the relationship between obesity and AKI (P=0.001). In conclusion, obesity independently predicts AKI after cardiac surgery, and oxidative stress may partially mediate this association.

Phytochemical activation of Nrf2 protects human coronary artery endothelial cells against an oxidative challenge

Activation of NF-E2-related factor 2 (Nrf2) is a potential therapeutic intervention against endothelial cell oxidative stress and associated vascular disease. We hypothesized that treatment with the phytochemicals in the patented dietary supplement Protandim would induce Nrf2 nuclear localization and phase II antioxidant enzyme protein in human coronary artery endothelial cells (HCAECs), protecting against an oxidant challenge in an Nrf2- dependent manner. Protandim treatment induced Nrf2 nuclear localization, and HO-1 (778% of control ± 82.25 P < 0.01), SOD1 (125.9% of control ± 6.05 P < 0.01), NQO1 (126% of control ± 6.5 P < 0.01), and GR (119.5% of control ± 7.00 P < 0.05) protein expression in HCAEC. Treatment of HCAEC with H(2)O(2) induced apoptosis in 34% of cells while pretreatment with Protandim resulted in only 6% apoptotic cells (P < 0.01). Nrf2 silencing significantly decreased the Protandim-induced increase in HO-1 protein (P < 0.01). Nrf2 silencing also significantly decreased the protection afforded by Protandim against H(2)O(2)- induced apoptosis (P < 0.01 compared to no RNA, and P < 0.05 compared to control RNA). These results show that Protandim induces Nrf2 nuclear localization and antioxidant enzyme expression, and protection of HCAEC from an oxidative challenge is Nrf2 dependent.

Obesity and airway responsiveness: role of TNFR2

Obese mice exhibit innate airway hyperresponsiveness (AHR), a feature of asthma. Tumor necrosis factor alpha (TNFα) is implicated in the disease progression and chronic inflammatory status of both obesity and asthma. TNF acts via two TNF receptors, TNFR1 and TNFR2. To examine the role of TNFR2 in the AHR observed in obese mice, we generated obese Cpe(fat) mice that were either sufficient or deficient in TNFR2 (Cpe(fat) and Cpe(fat)/TNFR2(-/-) mice, respectively) and compared them with their lean controls (WT and TNFR2(-/-) mice). Compared to WT mice, Cpe(fat) mice exhibited AHR to aerosolized methacholine (measured using the forced oscillation technique) which was ablated in Cpe(fat)/TNFR2(-/-) mice. Bioplex or ELISA assay indicated significant increases in serum leptin, G-CSF, IL-7, IL-17A, TNFα, and KC in obese versus lean mice, as well as significant obesity-related increases in bronchoalveolar lavage fluid (BALF) G-CSF and IP-10, regardless of TNFR2 status. Importantly, BALF IL-17A was significantly increased over lean controls in Cpe(fat) but not Cpe(fat)/TNFR2(-/-) mice. Functional annotation clustering of significantly affected genes identified from microarray analysis comparing gene expression in lungs of Cpe(fat) and WT mice, identified blood vessel morphogenesis as the gene ontology category most affected by obesity. This category included several genes associated with AHR, including endothelin and trkB. Obesity increased pulmonary mRNA expression of endothelin and trkB in TNFR2 sufficient but not deficient mice. Our results indicate that TNFR2 signaling is required for the innate AHR that develops in obese mice, and suggest that TNFR2 may act by promoting IL-17A, endothelin, and/or trkB expression.

Systemic upregulation of NADPH oxidase in diet-induced obesity in rats

Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase is upregulated in a variety of tissues in obesity. It is still unclear as to whether NADPH oxidase upregulation in a specific tissue is part of a systemic response. Here we analyzed the expression pattern of NADPH oxidase in vascular, adipose, and kidney tissues in a rat model of diet-induced obesity. After weaning, rats were fed either a normal or high-fat diet for 12 weeks. The high-fat diet resulted in 20% increased body weight. In the aorta, Nox4 expression was increased by three-fold in obese rats. Upregulations of p22phox and p47phox in adipose, and Nox4, p22phox, and p47phox in kidney were observed in obesity. Marked increases in plasma leptin and insulin were observed, with more modest changes in adiponectin in obese rats. The average systolic blood pressure in the obese group was 11 mmHg higher than that of lean rats (P < 0.005). There was a significant correlation between blood pressure and aortic Nox4 expression (P < 0.01). In cultured vascular smooth muscle cells, adiponectin reduced the expression of Nox4 in a protein kinase A-dependent manner. Our results suggest that upregulation of NADPH oxidase in multiple tissues during obesity appears to be a systemic response. At least in vitro, adiponectin may have a protective antioxidant role by suppressing vascular NADPH oxidase expression. The association between NADPH oxidase Nox4 expression in the vasculature and the elevated blood pressure in obesity requires further investigation.

Oxidative stress and inflammation interactions in human obesity

Obesity is often characterized by increased oxidative stress and exacerbated inflammatory outcomes accompanying infiltration of immune cells in adipocytes. The oxidative stress machinery and inflammatory signaling are not only interrelated, but their impairment can lead to an inhibition of insulin responses as well as a higher risk of cardiovascular diseases and associated features. Mitochondria, in addition to energy transformation, play a role in apoptosis, cellular proliferation, as well as in the cellular redox state control. Under certain circumstances, protons are able to re-enter the mitochondrial matrix via different uncoupling proteins, disturbing free radical production by mitochondria. Disorders of the mitochondrial electron transport chain, over-generation of reactive oxygen species, and lipoperoxides or alterations in antioxidant defenses have been reported in situations of obesity and type-2 diabetes. On the other hand, obesity has been linked to a low grade pro-inflammatory state, in which impairments in the oxidative stress and antioxidant mechanism could be involved. The current scientific evidence highlights the need of investigating the interplay between oxidative stress and inflammation with obesity/diabetes onset as well as the interactions of such factors either as a cause or consequence of obesity. The signaling mediated by the activation of inflammatory markers or nuclear factor kappa β and other transcription factors as central regulators of inflammation are key issues to understanding oxidative stress responses in obesity. This review aims at summarizing the main mechanisms and interplay factors between oxidative stress and inflammation in human obesity according to the last 10 years of research in the field.

Is oxidative stress, a link between nephrolithiasis and obesity, hypertension, diabetes, chronic kidney disease, metabolic syndrome?

Epidemiological studies have provided the evidence for association between nephrolithiasis and a number of cardiovascular diseases including hypertension, diabetes, chronic kidney disease, metabolic syndrome. Many of the co-morbidities may not only lead to stone disease but also be triggered by it. Nephrolithiasis is a risk factor for development of hypertension and have higher prevalence of diabetes mellitus and some hypertensive and diabetic patients are at greater risk for stone formation. An analysis of the association between stone disease and other simultaneously appearing disorders, as well as factors involved in their pathogenesis, may provide an insight into stone formation and improved therapies for stone recurrence and prevention. It is our hypothesis that association between stone formation and development of co-morbidities is a result of certain common pathological features. Review of the recent literature indicates that production of reactive oxygen species (ROS) and development of oxidative stress (OS) may be such a common pathway. OS is a common feature of all cardiovascular diseases (CVD) including hypertension, diabetes mellitus, atherosclerosis and myocardial infarct. There is increasing evidence that ROS are also produced during idiopathic calcium oxalate (CaOx) nephrolithiasis. Both tissue culture and animal model studies demonstrate that ROS are produced during interaction between CaOx/calcium phosphate (CaP) crystals and renal epithelial cells. Clinical studies have also provided evidence for the development of oxidative stress in the kidneys of stone forming patients. Renal disorders which lead to OS appear to be a continuum. Stress produced by one disorder may trigger the other under the right circumstances.

Carvedilol-lisinopril combination therapy and endothelial function in obese individuals with hypertension

The authors hypothesized that carvedilol controlled-release plus lisinopril combination therapy (C+L) would increase endothelial function and decrease oxidative stress to a greater extent than hydrochlorothiazide plus lisinopril combination therapy (H+L) in obese patients with hypertension. Twenty-five abdominally obese patients (aged 54.4±7.3 years; 14 women) with hypertension/prehypertension were enrolled in a 7-month (two 3-month treatment periods separated by a 1-month washout), randomized, double-blind, controlled, crossover clinical trial comparing C+L vs H+L. Endothelial function, measured by digital reactive hyperemic index (RHI), circulating oxidized low-density lipoprotein (oxLDL), 8-isoprostane, and asymmetric dimethylarginine (ADMA) were obtained at baseline, post-period 1, post-washout, and post-period 2. Analyses were adjusted for baseline measurements by analysis of covariance, with robust variance estimation for confidence intervals and P values. C+L treatment compared to H+L treatment significantly improved RHI (0.74, 95% confidence interval, 0.31-1.19, P =.001). This difference persisted after adjustment for the change in systolic blood pressure. No significant treatment differences were observed for oxLDL, 8-isoprostane, or ADMA. These data provide evidence that independent of blood pressure-lowering, C+L therapy improves endothelial function to a greater extent than H+L therapy. Levels of oxidative stress were not significantly different between treatments, suggesting that other mechanisms may be responsible for the improvement in endothelial function.

Habitually exercising older men do not demonstrate age-associated vascular endothelial oxidative stress

We tested the hypothesis that older men who perform habitual aerobic exercise do not demonstrate age-associated vascular endothelial oxidative stress compared with their sedentary peers. Older exercising men (n=13, 62±2 years) had higher (P<0.05) physical activity (79±7 vs. 30±6 MET hours per week) and maximal exercise oxygen consumption (42±1 vs. 29±1 mL kg(-1) per minute) vs. sedentary men (n=28, 63±1 years). Brachial artery flow-mediated dilation (FMD), a measure of vascular endothelial function, was greater (P<0.05) in the exercising vs. sedentary older men (6.3±0.5 vs. 4.9±0.4%Δ) and not different than young controls (n=20, 25±1 years, 7.1±0.5%Δ). In vascular endothelial cells sampled from the brachial artery, nitrotyrosine, a marker of oxidative stress, was 51% lower in the exercising vs. sedentary older men (0.38±0.06 vs. 0.77±0.10 AU). This was associated with lower endothelial expression of the oxidant enzyme nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (p47(phox) subunit, 0.33±0.05 vs. 0.61±0.09 AU) and the redox-sensitive transcription factor nuclear factor kappa B (NFκB) (p65 subunit, 0.36±0.05 vs. 0.72±0.09 AU). Expression of the antioxidant enzyme manganese superoxide dismutase (SOD) (0.57±0.13 vs. 0.30±0.04 AU) and activity of endothelium-bound extracellular SOD were greater (6.4±0.5 vs. 5.0±0.6 U mL(-1) per minute) in the exercising men (both P<0.05), but differences no longer were significant after correcting for adiposity and circulating metabolic factors. Overall, values for the young controls differed with those for the sedentary, but not the exercising older men. Older men who exercise regularly do not demonstrate vascular endothelial oxidative stress, and this may be a key molecular mechanism underlying their reduced risk of cardiovascular diseases.

The forgotten face of regular physical exercise: a 'natural' anti-atherogenic activity

Humans are not programmed to be inactive. The combination of both accelerated sedentary lifestyle and constant food availability disturbs ancient metabolic processes leading to excessive storage of energy in tissue, dyslipidaemia and insulin resistance. As a consequence, the prevalence of Type 2 diabetes, obesity and the metabolic syndrome has increased significantly over the last 30 years. A low level of physical activity and decreased daily energy expenditure contribute to the increased risk of cardiovascular morbidity and mortality following atherosclerotic vascular damage. Physical inactivity leads to the accumulation of visceral fat and consequently the activation of the oxidative stress/inflammation cascade, which promotes the development of atherosclerosis. Considering physical activity as a 'natural' programmed state, it is assumed that it possesses atheroprotective properties. Exercise prevents plaque development and induces the regression of coronary stenosis. Furthermore, experimental studies have revealed that exercise prevents the conversion of plaques into a vulnerable phenotype, thus preventing the appearance of fatal lesions. Exercise promotes atheroprotection possibly by reducing or preventing oxidative stress and inflammation through at least two distinct pathways. Exercise, through laminar shear stress activation, down-regulates endothelial AT1R (angiotensin II type 1 receptor) expression, leading to decreases in NADPH oxidase activity and superoxide anion production, which in turn decreases ROS (reactive oxygen species) generation, and preserves endothelial NO bioavailability and its protective anti-atherogenic effects. Contracting skeletal muscle now emerges as a new organ that releases anti-inflammatory cytokines, such as IL-6 (interleukin-6). IL-6 inhibits TNF-α (tumour necrosis factor-α) production in adipose tissue and macrophages. The down-regulation of TNF-α induced by skeletal-muscle-derived IL-6 may also participate in mediating the atheroprotective effect of physical activity.

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".

Enhancement of antioxidant defense mechanism by pitavastatin and rosuvastatin on obesity-induced oxidative stress in Wistar rats

CONTEXT

There has been a steady increase in the epidemiology of obesity over the last 30 years with developed countries leading the way. Oxidative stress was believed to be the principle contributor to the development of cardiovascular disorders that linked with obesity.

OBJECTIVE

To evaluate the enhancement of antioxidant defense mechanism by Pitavastatin (PTV) and Rosuvastatin (RSV) on obesity-induced oxidative stress in Wistar rats.

METHODS

Fifty Wistar albino rats were divided into five groups. High fat diet (HFD, 20 g/day/rat) pellets were given for 28 days to produce obesity-induced oxidative stress in Wistar rats. Oral administration of HFD along with PTV, RSV and Orlistat [(HFD for 28 days + from 8th day PTV (1 mg/kg), RSV (5 mg/kg) and Orlistat (10 mg/kg) to 28th day] were given respectively.

RESULTS

Both PTV and RSV produced significant (p < 0.01) reduction in serum apolipoprotein-B (Apo-B), total cholesterol (TC), triglycerides (TGs), cardiac-lipid peroxides (TBARS) levels and elevation in serum high density lipoprotein (HDL-C), cardiac antioxidant enzymes [glutathione (GSH), glutathione peroxidase (GPx), glutathione reductase (GR), glutathione-S-transferase (GST), superoxide dismutase (SOD) and catase (CAT)] levels.

DISCUSSION AND CONCLUSION

Results were comparable with Orlistat, a standard antiobesity drug and present initial evidence that Pitavastatin and Rosuvastatin are useful for the treatment of obesity by enhancing the antioxidant defense mechanism. However, the effects of PTV were more prominent than RSV. The present findings of Pitavastatin and Rosuvastatin raise the possibility of a new application as an antiobesity therapeutic modality.

SIRT-1 and vascular endothelial dysfunction with ageing in mice and humans

We tested the hypothesis that reductions in the cellular deacetylase, sirtuin-1 (SIRT-1), contribute to vascular endothelial dysfunction with ageing via modulation of endothelial nitric oxide synthase (eNOS) acetylation/activation-associated nitric oxide (NO) production. In older (30 months, n = 14) vs. young (5-7 months, n = 16) B6D2F1 mice, aortic protein expression of SIRT-1 and eNOS phosphorylated at serine 1177 were lower (both P < 0.05), and acetylated eNOS was 6-fold higher (P < 0.05), whereas total eNOS did not differ (P = 0.65). Acetylcholine (ACh)-induced peak endothelium-dependent dilatation (EDD) was lower in isolated femoral arteries with ageing (P < 0.001). Incubation with sirtinol, a SIRT-1 inhibitor, reduced EDD in both young and older mice, abolishing age-related differences, whereas co-administration with l-NAME, an eNOS inhibitor, further reduced EDD similarly in both groups. Endothelium-independent dilatation to sodium nitroprusside (EID), was not altered by age or sirtinol treatment. In older (64 ± 1 years, n = 22) vs. young (25 ± 1 years, n = 16) healthy humans, ACh-induced forearm EDD was impaired (P = 0.01) and SIRT-1 protein expression was 37% lower in endothelial cells obtained from the brachial artery (P < 0.05), whereas EID did not differ. In the overall group, EDD was positively related to endothelial cell SIRT-1 protein expression (r = 0.44, P < 0.01). Reductions in SIRT-1 may play an important role in vascular endothelial dysfunction with ageing. SIRT-1 may be a key therapeutic target to treat arterial ageing.

Vitamin C status is related to proinflammatory responses and impaired vascular endothelial function in healthy, college-aged lean and obese men

Vitamin C supplementation has been suggested to reduce cardiovascular disease risk. However, no studies have examined the relationship between vitamin C status and vascular dysfunction in lean and obese individuals in the absence of supplementation. We examined whether vascular function is interrelated with vitamin C status and inflammation in healthy, college-aged lean and obese men with no history of dietary supplementation. A cross-sectional study was conducted during winter 2008 in lean and obese men aged 21±3 years (n=8/group). Brachial artery flow-mediated dilation (FMD) was measured to determine vascular endothelial function. Plasma antioxidants (vitamin C, vitamin E, and thiols), inflammatory proteins (C-reactive protein [CRP], myeloperoxidase [MPO], and cytokines), and cellular adhesion molecules were measured. Participants also completed 3-day food records on the days preceding their vascular testing. Group differences were evaluated by t tests, and correlation coefficients were determined by linear regression. FMD was 21% lower (P<0.05) in obese men. They also had 51% lower vitamin C intakes and 38% lower plasma vitamin C concentrations. Obese men had greater plasma concentrations of CRP, MPO, inflammatory cytokines, and cellular adhesion molecules. Participants' CRP and MPO were each inversely related (P<0.05) to FMD (r=-0.528 and -0.625) and plasma vitamin C (r=-0.646 and -0.701). These data suggest that low vitamin C status is associated with proinflammatory responses and impaired vascular function in lean and obese men. Additional study is warranted to determine whether improving dietary vitamin C intakes from food attenuate vascular dysfunction.

Lectin-like oxidized low-density lipoprotein receptor-1 modulates endothelial apoptosis in obstructive sleep apnea

BACKGROUND

Lectin-like oxidized low-density lipoprotein receptor 1 (LOX-1) is the major receptor for oxidized low-density lipoprotein in endothelial cells, and its expression is enhanced in proatherogenic settings. The objective of this study was to investigate the association between LOX-1 in freshly harvested human venous endothelial cells and apoptotic circulating endothelial cells in patients with obstructive sleep apnea (OSA).

METHODS

We conducted a prospective, interventional study of 38 patients with newly diagnosed OSA free of disease and 12 healthy control subjects. Plasma LOX-1 (pLOX-1) levels were measured using a commercially available enzyme-linked immunosorbent assay. Protein expression of LOX-1 was quantified by immunofluorescence in freshly harvested venous endothelial cells before and after 8 weeks of continuous positive airway pressure (CPAP) therapy. Circulating apoptotic endothelial cells (CD146(+), CD45(-), and CD31(1)) were assessed concomitantly by flow cytometry.

RESULTS

pLOX-1 levels were higher in subjects with OSA than in control subjects (326.9 ± 267.1 pg/mL and 141.1 ± 138.6 g/mL, respectively; P = .004). Patients with OSA showed a threefold increase in baseline endothelial expression of LOX-1 relative to control subjects. CPAP therapy resulted in a significant decrease in endothelial LOX-1 expression only in CPAP-adherent patients. Circulating apoptotic endothelial cells correlated directly with baseline expression of LOX-1 (R(2) = 0.32, P = .01) after adjustment for age, BMI, and waist to hip ratio.

CONCLUSIONS

Increased expression of LOX-1 in vivo is associated with endothelial apoptosis. Adherence to CPAP therapy may reverse these derangements.

Insulin resistance and oxidative stress influence colony-forming unit-endothelial cells capacity in obese patients

The aim of this study was to investigate the relationship between a sub-population of endothelial progenitor cells (EPC), namely colony-forming unit-endothelial cells (CFU-EC), their colony-forming capacity and variable clinical parameters, including insulin resistance and oxidative stress, in obese individuals. Thirty-eight obese adults (aged 42.5 ± 12.7), with BMI 32.3 ± 4.0 and 13 normal-weight controls (aged 48.2 ± 12.9; BMI 23.2 ± 2.3) were studied. CFU-EC colony-forming capacity was impaired in the group of obese individuals compared to the normal-weight controls (P = 0.001). The inverse correlation between homeostasis model assessment-insulin resistance (HOMA(IR)) index and CFU-EC number (r = -0.558, P < 0.0001) as well as positive total antioxidant status of plasma (TAS)/CFU-EC relation were noticed during the study. Additionally, correlations between the concentration of triglycerides (TG), high-density lipoproteins (HDLs), and body composition parameters in the obese participants were established. Our results demonstrate that insulin resistance and oxidative stress have a significant impact on the CFU-EC colony formation in obesity. Moreover, in multivariate regression analysis, in both studied groups, the HOMA(IR) index and HDL concentration were independent predictors of the number of CFU-EC. Endothelium dysfunction, which can be present in obesity, may in part be caused by EPC function impairment in this condition.

Augmented NADPH oxidase activity and p22phox expression in monocytes underlie oxidative stress of patients with type 2 diabetes mellitus

BACKGROUND

This study was to test the hypothesis that enhanced oxidative stress is induced in monocytes with over-activated NADPH oxidase during the development of type 2 diabetes mellitus.

METHODS

Levels of glucose and lipids were analyzed in 73 diabetic patients and 36 controls. Superoxide dismutase (SOD), malondialdehyde (MDA), reactive oxygen species (ROS) and protein carbonylation were tested. Expression of NADPH oxidase was examined and p47phox translocation was assessed.

RESULTS

With the abnormality of glucose and lipid metabolism, diabetic patients showed a higher oxidative stress state indicated by decreased SOD activity but elevated MDA and protein carbonylation level. Monocytes in diabetes also showed elevated ROS generation and protein carbonylation level. Furthermore, NADPH oxidase was highly activated in monocytes represented by p22phox up-regulation and p47phox translocation. Significant positive bivariate correlation was found between glucose and MDA level as well as p22phox expression. In vitro experiments also indicated that glucose could stimulate ROS generation in a NADPH oxidase dependent manner. Moreover, we carried out same measurement in 40 diabetic patients with anti-diabetic intervention and obtained the reinforced results.

CONCLUSIONS

Hyperglycemia is the main factor which induces oxidative stress mainly by activation of NADPH oxidase in monocytes of diabetic patients.

Effect of early particulate air pollution exposure on obesity in mice: role of p47phox

OBJECTIVE

To evaluate the role of early-life exposure to airborne fine particulate matter (diameter, <2.5 μm [PM(2.5)]) pollution on metabolic parameters, inflammation, and adiposity; and to investigate the involvement of oxidative stress pathways in the development of metabolic abnormalities.

METHODS AND RESULTS

PM(2.5) inhalation exposure (6 h/d, 5 d/wk) was performed in C57BL/6 mice (wild type) and mice deficient in the cytosolic subunit of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase p47(phox) (p47(phox-/-)) beginning at the age of 3 weeks for a duration of 10 weeks. Both groups were simultaneously fed a normal diet or a high-fat diet for 10 weeks. PM(2.5)-exposed C57BL/6 mice fed a normal diet exhibited metabolic abnormalities after exposure to PM(2.5) or FA for 10 weeks. Consistent with insulin resistance, these abnormalities included enlarged subcutaneous and visceral fat contents, increased macrophage infiltration in visceral adipose tissue, and vascular dysfunction. Ex vivo-labeled and infused monocytes demonstrated increased adherence in the microcirculation of normal diet- or high-fat diet-fed PM(2.5)-exposed mice. p47(phox-/-) mice exhibited an improvement in parameters of insulin resistance, vascular function, and visceral inflammation in response to PM(2.5).

CONCLUSIONS

Early-life exposure to high levels of PM(2.5) is a risk factor for subsequent development of insulin resistance, adiposity, and inflammation. Reactive oxygen species generation by NADPH oxidase appears to mediate this risk.

The effect of paternal diet-induced obesity on sperm function and fertilization in a mouse model

Although obvious effects of obesity on female reproduction and oocytes are emerging, the effects on male fertility and sperm quality are less clear with studies reporting conflicting results. We hypothesize that male obesity affects sperm function and physiology probably as a result of elevated oxidative stress in spermatozoa and therefore elevated levels of sperm DNA damage and loss of function. Six-week-old C57/Bl6 male mice (n = 36) were randomly allocated to two groups: group 1 (n = 18) received a control diet, whereas group 2 (n = 18) received a high-fat diet (HFD). At the completion of a 9-week period, mice were sacrificed and spermatozoa were obtained. Sperm motility, concentration, intracellular reactive oxygen species (ROS) production and sperm DNA damage were measured. The ability of the sperm to undergo capacitation, acrosome reaction, sperm binding and ability to fertilize an oocyte were also assessed. The percentage of motile spermatozoa was decreased in the HFD group compared with controls (36 ± 2% vs. 44 ± 4%; p < 0.05). Intracellular ROS was elevated (692 ± 83 vs. 409 ± 22 units; p < 0.01) in the HFD group compared with controls. Sperm DNA damage was also increased (1.64 ± 0.6% vs. 0.17 ± 0.06%; p < 0.05) in the HFD group compared with the control group. Furthermore, the percentage of non-capacitated sperm was significantly lower compared with controls (12.34% vs. 21.06%; p < 0.01). The number of sperm bound to each oocyte was significantly lower (41.14 ± 2.5 vs. 58.39 ± 2.4; p < 0.01) in the HFD group compared with that in controls and resulted in significantly lower fertilization rates (25.9% vs. 43.9%; p < 0.01). This report provides evidence that obesity may induce oxidative stress and sperm DNA damage as well as decreased fertilizing ability. This is important as DNA damage in the sperm as a result of oxidative stress has been linked to poor reproductive outcomes.

NOX activity in brain aging: exacerbation by high fat diet

This study describes how age and high fat diet affect the profile of NADPH oxidase (NOX). Specifically, NOX activity and subunit expression were evaluated in the frontal cerebral cortex of 7-, 16-, and 24-month old mice following a 4-month exposure to either Western diet (WD, 41% calories from fat) or very high fat lard diet (VHFD, 60% calories from fat). Data reveal a significant effect of age in on NOX activity, and show that NOX activity was only increased by VHFD, and only in 24-month old mice. NOX subunit expression was also increased by diet only in older mice. Quantification of protein carbonyls revealed significant age-related increases in protein oxidation, and indicate that only aged mice respond to high fat diet with enhanced protein oxidation. Histological analyses indicate prominent neuronal localization of both NOX subunits and protein carbonylation. Finally, data indicate that changes in reactive microgliosis, but not astrocytosis, mirror the pattern of diet-induced NOX activation and protein oxidation. Collectively, these data show that both age and dietary fat drive NOX activation, and further indicate that aged mice are preferentially sensitive to the effects of high fat diet. These data also suggest that high fat diets might exacerbate age-related oxidative stress in the brain via increased NOX.

Lipotoxicity in obese pregnancy and its potential role in adverse pregnancy outcome and obesity in the offspring

Increasing maternal obesity is a challenge that has an impact on all aspects of female reproduction. Lean and obese pregnant women gain similar fat mass, but lean women store fat in the lower-body compartment and obese women in central compartments. In the non-pregnant, central storage of fat is associated with adipocyte hypertrophy and represents a failure to adequately store excess fatty acids, resulting in metabolic dysregulation and ectopic fat accumulation (lipotoxicity). Obese pregnancy is associated with exaggerated metabolic adaptation, endothelial dysfunction and increased risk of adverse pregnancy outcome. We hypothesize that the preferential storage of fat in central rather than ‘safer’ lower-body depots in obese pregnancy leads to lipotoxicity. The combination of excess fatty acids and oxidative stress leads to the production of oxidized lipids, which can be cytotoxic and influence gene expression by acting as ligands for nuclear receptors. Lipid excess and oxidative stress provoke endothelial dysfunction. Oxidized lipids can inhibit trophoblast invasion and influence placental development, lipid metabolism and transport and can also affect fetal developmental pathways. As lipotoxicity has the capability of influencing both maternal endothelial function and placental function, it may link maternal obesity and placentally related adverse pregnancy outcomes such as miscarriage and pre-eclampsia. The combination of excess/altered lipid nutrient supply, suboptimal in utero metabolic environment and alterations in placental gene expression, inflammation and metabolism may also induce obesity in the offspring.

Association of carotid atherosclerosis with genetic polymorphisms of the klotho gene in patients with hypertension

AIM

Previous studies suggest that klotho gene polymorphisms may be associated with atherosclerosis, but did not assess the relationship between klotho gene polymorphisms and atherosclerosis parameters such as carotid artery intima-media thickness (IMT). Here, we studied whether klotho single nucleotide polymorphisms (SNP) were associated with carotid atherosclerosis.

METHODS

All subjects were Japanese. Eight-hundred and fifty-three patients with hypertension (465 men and 388 women) in the outpatient clinic and 1783 subjects from the general population (821 men and 962 women) attending health check-ups were analyzed in the present study. We measured mean IMT of the common carotid artery to evaluate carotid atherosclerosis. Four single nucleotide polymorphisms (SNP) (rs7323281; intron1, rs5644481; exon4, rs3752472; exon3, rs650439; intron4) of klotho were selected as representative SNP in haplotype blocks.

RESULTS

Multivariate logistic regression analysis adjusted by confounding factors showed a significant association of rs650439 with carotid atherosclerosis in hypertensive patients (TT vs TA vs AA, P < 0.01; TT + TA vs AA, P < 0.01). By ancova considering confounding factors, rs650439 was also significantly associated with mean IMT (TT + TA vs AA, P = 0.04) in the hypertensive population. However, there was no significant association between klotho SNP and carotid IMT in the general population. Compared to the general population, the subject group with hypertensive patients clearly had more atherosclerosis risk factors.

CONCLUSION

Only in hypertensive patients was klotho rs650439 strongly associated with mean IMT thickening of the common carotid artery. Therefore, klotho SNP (rs650439) may influence on the progression of carotid atherosclerosis in patients with hypertension.

Vascular inflammation in obesity and sleep apnea

BACKGROUND

Unrecognized obstructive sleep apnea (OSA) is highly prevalent in obesity. Both obesity and OSA are associated with vascular endothelial inflammation and increased risk for cardiovascular diseases. We investigated directly whether the endothelial alterations that are attributed commonly to obesity are in fact related to OSA.

METHODS AND RESULTS

Seventy-one subjects with a body mass index ranging from normal to obese underwent attended polysomnography. To assess vascular inflammation and oxidative stress directly, we quantified the expression of nuclear factor-kappaB and nitrotyrosine by immunofluorescence in freshly harvested venous endothelial cells. To evaluate basal endothelial nitric oxide (NO) production and activity, we quantified the expression of endothelial NO synthase (eNOS) and phosphorylated eNOS. Vascular reactivity was measured by brachial artery flow-mediated dilation. Expression of eNOS and phosphorylated eNOS and flow-mediated dilation were significantly lower, whereas expression of nitrotyrosine was significantly greater in OSA patients (n=38) than in OSA-free subjects (n=33) regardless of central adiposity. Expression of nuclear factor-kappaB was greater in obese OSA patients than in obese OSA-free subjects (P=0.004). Protein expression and flow-mediated dilation were not significantly affected by increasing body mass index or central obesity in OSA patients and in OSA-free subjects. After 4 weeks of continuous positive airway pressure therapy, flow-mediated dilation and expression of eNOS and phosphorylated eNOS significantly increased whereas expression of nitrotyrosine and nuclear factor-kappaB significantly decreased in OSA patients who adhered to continuous positive airway pressure >/=4 hours daily.

CONCLUSIONS

Untreated OSA rather than obesity is a major determinant of vascular endothelial dysfunction, inflammation, and elevated oxidative stress in obese patients.

Does endothelial dysfunction contribute to the clinical status of patients with peripheral arterial disease?

Peripheral arterial disease leads to lower extremity ischemia and limb loss, and is linked to cardiovascular events. The anatomical extent of lower extremity atherosclerosis fails to fully explain ischemic symptoms or predict the development of critical limb ischemia. Endothelial dysfunction is known to contributed to the pathogenesis and clinical expression of coronary artery disease, but the importance of endothelial dysfunction in peripheral arterial disease remains incompletely understood. Endothelial dysfunction could contribute to lower extremity ischemia by impairing blood flow responses to ischemia, collateral formation and arterial remodelling, and by promoting vasospasm, thrombosis, plaque rupture and lesion progression. There is a need for additional studies examining the contribution of endothelial dysfunction to the pathogenesis of peripheral arterial disease, and the potential role of endothelial dysfunction as a surrogate marker with utility in the management of patients.

Hyperlipidemia: a new therapeutic target for diabetic neuropathy

Emerging data establish dyslipidemia as a significant contributor to the development of diabetic neuropathy. In this review, we discuss how separate metabolic imbalances, including hyperglycemia and hyperlipidemia, converge on mechanisms leading to oxidative stress in dorsal root ganglia (DRG) sensory neurons. We conclude with suggestions for novel therapeutic strategies to prevent or reverse diabetes-induced nerve degeneration.

Proteomic profiling reveals comprehensive insights into adrenergic receptor-mediated hypertrophy in neonatal rat cardiomyocytes

Myocardial adrenergic receptors (ARs) play important roles in cardiac hypertrophy. However, the detailed molecular mechanism of AR-mediated cardiac hypertrophy remains elusive to date. To gain full insight into how ARs are involved in the regulation of cardiac hypertrophy, protein expression profiling was performed with comparative proteomics approach on neonatal rat cardiomyocytes. Forty-six proteins were identified as differentially expressed in hypertrophic cardiomyocytes induced by AR stimulation. To better understand the biological significance of the obtained proteomic data, we utilized the ingenuity pathway analysis tool to construct biological networks and analyze function and pathways that might associate with AR-mediated cardiac hypertrophy. Pathway analysis strongly suggested that ROS may be involved in the development of AR-mediated cardiac hypertrophy, which was then confirmed by further experimentation. The results showed that a marked increase in ROS production was detected in AR-mediated cardiac hypertrophy and blocking of ROS production significantly inhibited AR-mediated cardiac hypertrophy. We further proved that the ROS production was through NADPH oxidase or the mitochondrial electron transport chain and this ROS accumulation resulted in activation of extracellular signal-regulated kinase 1/2 leading to AR-mediated cardiac hypertrophy. These experimental results support the hypothesis, from the ingenuity pathway analysis, that AR-mediated cardiac hypertrophy is associated with the dysregulation of a complicated oxidative stress-regulatory network. In conclusion, our results provide a basis for understanding the detailed molecular mechanisms of AR-mediated cardiac hypertrophy.

Insulin resistance, lipotoxicity and endothelial dysfunction

The number of people with the insulin-resistant conditions of type 2 diabetes mellitus (T2DM) and obesity has reached epidemic proportions worldwide. Eighty percent of people with T2DM will die from the complications of cardiovascular atherosclerosis. Insulin resistance is characterised by endothelial dysfunction, which is a pivotal step in the initiation/progression of atherosclerosis. A hallmark of endothelial dysfunction is an unfavourable imbalance between the bioavailability of the antiatherosclerotic signalling molecule nitric oxide (NO) and proatherosclerotic reactive oxygen species. In this review we discuss the mechanisms linking insulin resistance to endothelial dysfunction, with a particular emphasis on a potential role for a toxic effect of free fatty acids on endothelial cell homeostasis.

Inflammatory stress in primary venous and aortic endothelial cells of type 1 diabetic mice

OBJECTIVE

The progression of diabetes is associated with profound endothelial dysfunction. We tested the hypothesis that cellular stress would be detectable in ECs retrieved from arterial and venous vessels of diabetic mice.

METHOD

We describe a method for direct isolation of well-characterised aortic and venous ECs from mice in which cells are not subjected to propagation in culture.

RESULTS

Gene expression profiling, confirmed by real-time PCR, revealed a progressive increase in markers of injury within two main gene families, EC activation and EC apoptosis, in aortic and venous ECs recovered from diabetic versus non-diabetic mice. In short-term diabetes, Il1b mRNA transcripts were higher in aortic and venous ECs of diabetic mice versus controls. In long-term diabetes, casp-1 mRNA transcripts were higher in aortic and venous ECs of diabetic mice versus controls.

CONCLUSION

These data suggest that diabetes imparts diffuse endothelial perturbation in the arterial and venous endothelium.

Vascular endothelial estrogen receptor alpha is modulated by estrogen status and related to endothelial function and endothelial nitric oxide synthase in healthy women

CONTEXT AND OBJECTIVE

Estrogen receptor alpha (ER alpha), a potent transcription factor expressed in vascular endothelial cells, plays a key role in regulating vascular function and health. We determined whether vascular endothelial cell expression of ER alpha is influenced by estrogen status and is related to vascular endothelial function in healthy women.

METHODS

ER alpha protein expression was measured (quantitative immunofluorescence) in endothelial cells from peripheral veins of 16 healthy, premenopausal women during the early follicular (EF) and late follicular (LF) phases of the menstrual cycle and 17 estrogen-deficient postmenopausal women. Endothelial-dependent dilation (EDD; brachial artery flow-mediated dilation) and endothelial nitric oxide synthase (eNOS) expression and activation were also measured in a subgroup of women.

RESULTS

In premenopausal women (n = 10), ER alpha expression was 30% lower (P < 0.001) during the EF (low estrogen) compared with the LF (high estrogen) phase of the menstrual cycle. In postmenopausal women, ER alpha expression was 33% lower (P < 0.001) compared with the LF phase of the menstrual cycle in premenopausal women. ER alpha expression was strongly related (r = 0.67; P < 0.001) to EDD, which was reduced in postmenopausal women. ER alpha abundance was positively related to expression of eNOS (r = 0.54; P = 0.009; n = 21) and ser1177 phosphorylated eNOS (r = 0.59; P = 0.006; n = 20).

CONCLUSIONS

These results provide the first evidence that expression of ER alpha in vascular endothelial cells is modulated by estrogen status and may be a key determinant of vascular endothelial function in healthy pre- and postmenopausal women. ER alpha expression may influence vascular endothelial function in women by affecting protein levels and activation of eNOS.

Vascular actions of insulin with implications for endothelial dysfunction

Hemodynamic actions of insulin depend largely on the hormone's ability to stimulate synthesis and release of endothelial mediators, whose balanced activity ensures dynamic control of vascular function. Nitric oxide (NO), endothelin-1 (ET-1), and reactive oxygen species (ROS) are important examples of endothelial mediators with opposing properties on vascular tone, hemostatic processes, and vascular permeability. Reduced NO bioavailability, resulting from either insufficient production or increased degradation of NO, characterizes endothelial dysfunction. In turn, endothelial dysfunction predicts vascular complications of metabolic and hemodynamic disorders. In the cardiovascular system, insulin stimulates the production and release of NO, ET-1, and ROS via activation of distinct intracellular signaling pathways. Under insulin-resistant conditions, increased insulin concentrations and/or impaired insulin-signaling pathways in the vasculature may contribute to imbalance in secretion of endothelial mediators that promote pathogenesis of vascular abnormalities. This short review describes signaling pathways involved in insulin-stimulated release of NO, ROS, and ET-1 and suggests possible molecular mechanisms by which abnormal insulin signaling may contribute to endothelial dysfunction.

Protein expression in vascular endothelial cells obtained from human peripheral arteries and veins

Studying molecular mechanisms of vascular endothelial function in humans is difficult in part because of limited access to arteries. Access to peripheral veins is more practical. We determined if differences in protein expression of endothelial cells (EC) collected from a peripheral artery are reflected in measurements made on EC obtained from peripheral veins. EC were collected from the brachial artery and an antecubital vein of 106 healthy adults (60 men and 46 women, age 18-77 years). Quantitative immunofluorescence was used to measure protein expression of endothelial nitric oxide synthase (eNOS), Ser-1177 phosphorylated eNOS, manganese superoxide dismutase, nitrotyrosine, xanthine oxidase and nuclear factor-kappaB p65. Protein expression in EC obtained from brachial artery and antecubital vein sampling was moderately to strongly related (r = 0.59-0.81, all p < 0.0001, mean r = 0.70). Moreover, differences between subgroups in the lowest and highest tertiles of protein expression in EC obtained from arterial samples were consistently reflected in EC obtained from venous collections. These findings indicate that interindividual and group differences in expression of several proteins involved in nitric oxide production, oxidant production, antioxidant defense and inflammatory signaling in EC obtained from brachial artery sampling are consistently reflected in EC obtained from venous samples. Thus, EC collected from peripheral veins may provide a useful surrogate for EC obtained from arteries for measurements of EC protein expression in humans.

Nitric oxide, NAD(P)H oxidase, and atherosclerosis

The endothelial cell layer plays a major role in the development and progression of atherosclerosis. Endothelial NO synthase (eNOS) produces nitric oxide (NO) from L-arginine. NO can rapidly react with reactive oxygen species to form peroxynitrite. This reduces NO availability, impairs vasodilatation, and mediates proinflammatory and prothrombotic processes such as leukocyte adhesion and platelet aggregation. In the vessel wall, specific NAD(P)H oxidase complexes are major sources of reactive oxygen species. These NAD(P)H oxidases can transfer electrons across membranes to oxygen and generate superoxide anions. The short-lived superoxide anion rapidly dismutates to hydrogen peroxide, which can further increase the production of reactive oxygen species. This can lead to uncoupling of eNOS switching enzymatic activity from NO to superoxide production. This review describes the structure and regulation of different NAD(P)H oxidase complexes. We will also focus on NO/superoxide anion balance as modulated by hemodynamic forces, vasoconstrictors, and oxidized low-density lipoprotein. We will then summarize the recent advances defining the role of nitric oxide and NAD(P)H oxidase-derived reactive oxygen species in the development and progression of atherosclerosis. In conclusion, novel mechanisms affecting the vascular NO/superoxide anion balance will allow the development of therapeutic strategies in the treatment of cardiovascular diseases.

Vascular endothelial dysfunction with aging: endothelin-1 and endothelial nitric oxide synthase

To determine whether impaired endothelium-dependent dilation (EDD) in older adults is associated with changes in the expression of major vasoconstrictor or vasodilator proteins in the vascular endothelium, endothelial cells (EC) were obtained from the brachial artery and peripheral veins of 56 healthy men, aged 18-78 yr. Brachial artery EC endothelin-1 (ET-1) [0.99 +/- 0.10 vs. 0.57 +/- 0.10 ET-1/human umbilical vein EC (HUVEC) intensity, P = 0.01] and serine 1177 phosphorylated endothelial nitric oxide synthase (PeNOS) (0.77 +/- 0.09 vs. 0.44 +/- 0.07 PeNOS/HUVEC intensity, P < 0.05) (quantitative immunofluorescence) were greater, and EDD (peak forearm blood flow to intrabrachial acetylcholine) was lower (10.2 +/- 0.9 vs. 14.7 +/- 1.7 ml.100 ml(-1).min(-1), P < 0.05) in older (n = 18, 62 +/- 1 yr) vs. young (n = 15, 21 +/- 1 yr) healthy men. EDD was inversely related to expression of ET-1 (r = -0.39, P < 0.05). Brachial artery EC eNOS expression did not differ significantly with age, but tended to be greater in the older men (young: 0.23 +/- 0.03 vs. older: 0.33 +/- 0.07 eNOS/HUVEC intensity, P = 0.08). In the sample with venous EC collections, EDD (brachial artery flow-mediated dilation) was lower (3.50 +/- 0.44 vs. 7.68 +/- 0.43%, P < 0.001), EC ET-1 and PeNOS were greater (P < 0.05), and EC eNOS was not different in older (n = 23, 62 +/- 1 yr) vs. young (n = 27, 22 +/- 1 yr) men. EDD was inversely related to venous EC ET-1 (r = -0.37, P < 0.05). ET-1 receptor A inhibition with BQ-123 restored 60% of the age-related impairment in carotid artery dilation to acetylcholine in B6D2F1 mice (5-7 mo, n = 8; 30 mo, n = 11; P < 0.05). ET-1 expression is increased in vascular EC of healthy older men and is related to reduced EDD, whereas ET-1 receptor A signaling tonically suppresses EDD in old mice. Neither eNOS nor PeNOS is reduced with aging. Changes in ET-1 expression and bioactivity, but not eNOS, contribute to vascular endothelial dysfunction with aging.

Effects of red grape juice polyphenols in NADPH oxidase subunit expression in human neutrophils and mononuclear blood cells

The NADPH oxidase enzyme system is the main source of superoxide anions in phagocytic and vascular cells. NADPH oxidase-dependent superoxide generation has been found to be abnormally enhanced in several chronic diseases. Evidence is accumulating that polyphenols may have the potential to improve cardiovascular health, although the mechanism is not fully established. Consumption of concentrated red grape juice, rich in polyphenols, has been recently shown to reduce NADPH oxidase activity in circulating neutrophils from human subjects. In the present work we studied whether red grape juice polyphenols affected NADPH oxidase subunit expression at the transcription level. For this, we used human neutrophils and mononuclear cells from peripheral blood, HL-60-derived neutrophils and the endothelial cell line EA.hy926.Superoxide production was measured with 2'7'-dichlorofluorescein diacetate or lucigenin, mRNA expression by real-time RT-PCR and protein expression by Western blot. Each experiment was performed at least three times. In all cell types tested, red grape juice, dealcoholised red wine and pure polyphenols decreased superoxide anion production. Red grape juice and dealcoholised red wine selectively reduced p47phox, p22phox and gp91phox expression at both mRNA and protein levels, without affecting the expression of p67phox. Pure polyphenols, particularly quercetin, also reduced NADPH oxidase subunit expression, especially p47phox, in all cell types tested. The present results showing that red grape juice polyphenols reduce superoxide anion production provide an alternative mechanism by which consumption of grape derivatives may account for a reduction of oxidative stress associated with cardiovascular and/or inflammatory diseases related to NADPH oxidase superoxide overproduction.

Obesity and vulnerability of the CNS

The incidence of obesity is increasing worldwide, and is especially pronounced in developed western countries. While the consequences of obesity on metabolic and cardiovascular physiology are well established, epidemiological and experimental data are beginning to establish that the central nervous system (CNS) may also be detrimentally affected by obesity and obesity-induced metabolic dysfunction. In particular, data show that obesity in human populations is associated with cognitive decline and enhanced vulnerability to brain injury, while experimental studies in animal models confirm a profile of heightened vulnerability and decreased cognitive function. This review will describe findings from human and animal studies to summarize current understanding of how obesity affects the brain. Furthermore, studies aimed at identifying key elements of body-brain dialog will be discussed to assess how various metabolic and adipose-related signals could adversely affect the CNS. Overall, data suggest that obesity-induced alterations in metabolism may significantly synergize with age to impair brain function and accelerate age-related diseases of the nervous system. Thus, enhanced understanding of the effects of obesity and obesity-related metabolic dysfunction on the brain are especially critical as increasing numbers of obese individuals approach advanced age.

Nuclear factor-{kappa}B activation contributes to vascular endothelial dysfunction via oxidative stress in overweight/obese middle-aged and older humans

BACKGROUND

We tested the hypothesis that nuclear factor-kappaB (NF-kappaB) activity contributes to vascular endothelial dysfunction with aging and obesity in humans.

METHODS AND RESULTS

We conducted a randomized, double-blind, placebo-controlled crossover study in 14 nondiabetic overweight or obese (body mass index > or =25 kg/m(2)) middle-aged and older (age 52 to 68 years) adults. Salsalate (nonacetylated salicylate, 4500 mg/d), a compound that inhibits NF-kappaB activity, or placebo was administered for 4-day periods. Plasma salicylate concentrations reached the midtherapeutic range (21.8+/-1.1 mg/100 mL, P< or =0.0001 versus placebo) by day 4 of salsalate treatment. Salsalate increased expression of the inhibitor of NF-kappaB and reduced total and nuclear expression of NF-kappaB in endothelial cells obtained from the subjects (all P<0.05). Salsalate increased brachial artery flow-mediated dilation by 74% (from 4.0+/-0.4% to 6.6+/-0.5%, P<0.001) but did not affect endothelium-independent dilation (P=0.83). The change in brachial artery flow-mediated dilation with salsalate was inversely related to baseline flow-mediated dilation (r=-0.77, P<0.01). Infusion of vitamin C increased brachial artery flow-mediated dilation during placebo (P<0.001) but not after salsalate (P=0.23). Salsalate reduced nitrotyrosine (P=0.06) and expression of NADPH oxidase p47(phox) (P<0.05) in endothelial cells obtained from the subjects but did not influence circulating or endothelial cell inflammatory proteins.

CONCLUSIONS

Our findings provide the first direct evidence that NF-kappaB, in part via stimulation of oxidative stress, plays an important role in mediating vascular endothelial dysfunction in overweight and obese middle-aged and older humans.

Positive and negative regulation of insulin signaling by reactive oxygen and nitrogen species

Regulated production of reactive oxygen species (ROS)/reactive nitrogen species (RNS) adequately balanced by antioxidant systems is a prerequisite for the participation of these active substances in physiological processes, including insulin action. Yet, increasing evidence implicates ROS and RNS as negative regulators of insulin signaling, rendering them putative mediators in the development of insulin resistance, a common endocrine abnormality that accompanies obesity and is a risk factor of type 2 diabetes. This review deals with this dual, seemingly contradictory, function of ROS and RNS in regulating insulin action: the major processes for ROS and RNS generation and detoxification are presented, and a critical review of the evidence that they participate in the positive and negative regulation of insulin action is provided. The cellular and molecular mechanisms by which ROS and RNS are thought to participate in normal insulin action and in the induction of insulin resistance are then described. Finally, we explore the potential usefulness and the challenges in modulating the oxidant-antioxidant balance as a potentially promising, but currently disappointing, means of improving insulin action in insulin resistance-associated conditions, leading causes of human morbidity and mortality of our era.

Internet-delivered lifestyle physical activity intervention: limited inflammation and antioxidant capacity efficacy in overweight adults

Overweight and physical inactivity are associated with elevated reactive oxygen species and chronic low-grade inflammation. Exercise training studies have measured changes in systemic inflammatory and oxidative/antioxidative biomarkers but predominantly at moderate-high intensities. Few low-intensity, lifestyle-based physical activity (PA) studies have been conducted. The purpose of this study was to determine whether improvements in lifestyle-oriented PA resulting from a 16-wk Internet-delivered PA program [Active Living Every Day-Internet (ALED-I)] elicit cardioprotective improvements in measures of inflammation, oxidation, or antioxidant enzyme capacity. Forty-one men and women (age 23-62 yr) were randomized to either the ALED-I intervention [n = 19; age = 40.4 +/- 1.9 yr; body mass index (BMI) = 31.4 +/- 1.1 kg/m(2)] or a delayed intent-to-treat control condition (n = 22; age = 46.6 +/- 1.3 yr; BMI = 31.0 +/- 0.7 kg/m(2)). TNF-alpha, C-reactive protein, myeloperoxidase, superoxide dismutase, catalase, total antioxidative capacity, change in PA, and other cardiometabolic disease risk factors were measured at baseline and postintervention. The ALED-I group increased PA and decreased central adiposity without changes in the control group. There was no change in the control group for any inflammation, oxidation, or antioxidant biomarkers. TNF-alpha decreased (P = 0.01) in the intervention group but was not statistically different from the control group. In conclusion, modest improvements in daily low-intensity ambulatory PA as a result of an Internet-delivered lifestyle PA intervention may be cardioprotective in sedentary and overweight adults through reductions in central adiposity and inflammation. However, the absence of favorable changes in other inflammation, oxidation, and antioxidant biomarkers highlights the need for further attention to the dose response of lifestyle-structured PA promotion strategies for health maintenance/improvement.

G allele of the -930A>G polymorphism of the CYBA gene is associated with insulin resistance in obese subjects

It has been shown that NADPH oxidase plays a role in oxidative stress which has been involved in the development of metabolic syndrome. The -930A/G polymorphism of the CYBA gene (that codes p22phox, a major component of the NADPH oxidase) has been associated with human hypertension and with a reduction in NADPH oxidase activity. In this work, we have examined the influence of the -930A/G polymorphism on obesity risk and insulin resistance in a case-control study of Spanish subjects (n=313). In the obese group (n=159), there was a statistically significant association between the GG genotype of the -930A/G polymorphism of the CYBA gene and fasting insulin levels and HOMA index. This outcome agrees with previous findings concerning functional analyses of this polymorphism and reinforces the hypothesis that insulin resistance is associated with oxidative stress. In conclusion, a protective effect in carriers of the -930A/G polymorphism of the p22phox gene against insulin resistance in a population of Spanish obese adults has been found.

Aging is associated with greater nuclear NF kappa B, reduced I kappa B alpha, and increased expression of proinflammatory cytokines in vascular endothelial cells of healthy humans

The vascular endothelium may develop a proinflammatory profile with aging, but evidence is limited in humans. Expression of inflammatory proteins was determined in vascular endothelial cells (EC) obtained from peripheral veins of 24 young (23 +/- 1 years, mean +/- SE) and 36 older (63 +/- 1) healthy men and women using quantitative immunofluorescence. The older subjects had lower vascular endothelium-dependent dilation (forearm blood flow responses to acetylcholine, p < 0.05), and higher plasma concentrations of C-reactive protein, interleukin-6 (IL-6), and oxidized low-density lipoprotein (all p < 0.05), but not tumor necrosis factor-alpha (TNF-alpha). Total (O: 0.52 +/- 0.04 vs. Y: 0.33 +/- 0.05 NFkappaB/HUVEC intensity, p < 0.05) and nuclear (O: 0.59 +/- 0.04 vs. Y: 0.41 +/- 0.04) expression of nuclear factor kappa B p65 (NFkappaB), a proinflammatory gene transcription factor, was greater in EC from the older subjects (p < 0.05). EC expression of the inhibitor (of nuclear translocation) of NFkappaB (IkappaBalpha) was lower in the older subjects (O: 0.16 +/- 0.02 vs. Y: 0.24 +/- 0.03, p < 0.05), whereas IkappaB kinase (IkappaK) was not different. EC expression of the proinflammatory proteins IL-6 (O: 0.42 +/- 0.06 vs. Y: 0.29 +/- 0.03, p < 0.05), TNF-alpha (O: 0.52 +/- 0.06 vs. Y: 0.33 +/- 0.05, p < 0.05) and monocyte chemoattractant protein 1 (MCP-1) (O: 0.59 +/- 0.06 vs. Y: 0.38 +/- 0.02, p < 0.05) was greater in the older subjects, whereas cyclooxygenase 2 and the receptor for advanced glycation end-products did not differ. These findings indicate that impaired function with aging in healthy adults is associated with the development of a proinflammatory phenotype in the vascular endothelium that could be caused in part by reduced IkappaB-mediated inhibition of NFkappaB.