Caloric restriction reverses high-fat diet-induced endothelial dysfunction and vascular superoxide production in C57Bl/6 mice

Aldose Reductase (AR) Mediates and Perivascular Adipose Tissue (PVAT) Modulates Endothelial Dysfunction of Short-Term High-Fat Diet Feeding in Mice

Increased adiposity of both visceral and perivascular adipose tissue (PVAT) depots is associated with an increased risk of diabetes and cardiovascular disease (CVD). Under healthy conditions, PVAT modulates vascular tone via the release of PVAT-derived relaxing factors, including adiponectin and leptin. However, when PVAT expands with high-fat diet (HFD) feeding, it appears to contribute to the development of endothelial dysfunction (ED). Yet, the mechanisms by which PVAT alters vascular health are unclear. Aldose reductase (AR) catalyzes glucose reduction in the first step of the polyol pathway and has been long implicated in diabetic complications including neuropathy, retinopathy, nephropathy, and vascular diseases. To better understand the roles of both PVAT and AR in HFD-induced ED, we studied structural and functional changes in aortic PVAT induced by short-term HFD (60% kcal fat) feeding in wild type (WT) and aldose reductase-null (AR-null) mice. Although 4 weeks of HFD feeding significantly increased body fat and PVAT mass in both WT and AR-null mice, HFD feeding induced ED in the aortas of WT mice but not of AR-null mice. Moreover, HFD feeding augmented endothelial-dependent relaxation in aortas with intact PVAT only in WT and not in AR-null mice. These data indicate that AR mediates ED associated with short-term HFD feeding and that ED appears to provoke 'compensatory changes' in PVAT induced by HFD. As these data support that the ED of HFD feeding is AR-dependent, vascular-localized AR remains a potential target of temporally selective intervention.

Short-term dietary intervention improves endothelial dysfunction induced by high-fat feeding in mice through upregulation of the AMPK-CREB signaling pathway

AIM

In addition to functioning as an energy sensor switch, AMPK plays a key role in the maintenance of cardiovascular homeostasis. However, obesity disrupts AMPK signaling, contributing to endothelial dysfunction and cardiovascular disease. This study aimed to elucidate if a short-term dietary intervention consisting in replacing the high-fat diet with a standard diet for 2 weeks could reverse obesity-induced endothelial dysfunction via AMPK-CREB activation.

METHODS

For this, 5-week-old male C57BL6J mice were fed a standard (Chow) or a high-fat (HF) diet for 8 weeks. The HF diet was replaced by the chow diet for the last 2 weeks in half of HF mice, generating 3 groups: Chow, HF and HF-Chow. Vascular reactivity and western-blot assays were performed in the thoracic aorta.

RESULTS

Returning to a chow diet significantly reduced body weight and glucose intolerance. Relaxant responses to acetylcholine and the AMPK activator (AICAR) were significantly impaired in HF mice but improved in HF-Chow mice. The protein levels of AMPKα, p-CREB and antioxidant systems (heme oxygenase-1 (HO-1) and catalase) were significantly reduced in HF but normalized in HF-Chow mice.

CONCLUSION

Improving dietary intake by replacing a HF diet with a standard diet improves AMPK-mediated responses due to the upregulation of the AMPK/CREB/HO-1 signaling pathway.

Maternal High-Fat Diet and Offspring Hypertension

The incidence of hypertension has increased to epidemic levels in the past decades. Increasing evidence reveals that maternal dietary habits play a crucial role in the development of hypertension in adult offspring. In humans, increased fat consumption has been considered responsible for obesity and associated diseases. Maternal diets rich in saturated fats have been widely employed in animal models to study various adverse offspring outcomes. In this review, we discussed current evidence linking maternal high-fat diet to offspring hypertension. We also provided an in-depth overview of the potential mechanisms underlying hypertension of developmental origins that are programmed by maternal high-fat intake from animal studies. Furthermore, this review also presented an overview of how reprogramming interventions can prevent maternal high-fat-diet-induced hypertension in adult offspring. Overall, recent advances in understanding mechanisms behind programming and reprogramming of maternal high-fat diet on hypertension of developmental origins might provide the answers to curtail this epidemic. Still, more research is needed to translate research findings into practice.

Thromboxane-dependent coronary vasoconstriction in obese mice: Role of peroxynitrite

Obesity leads to chronic oxidative stress promoting the development of cardiovascular diseases including coronary artery disease and endothelial dysfunction. Increased reactive oxygen species production associated with obesity might lead to endothelial dysfunction through cyclooxygenase (COX) pathway. We evaluated arachidonic acid (AA)-dependent coronary vascular responses and explored COX metabolism in obese C57BL/6 mice. In response to arachidonic acid (AA), isolated hearts from obese mice showed increased vasoconstriction compared with control mice. Released thromboxane (TX) A2 during AA-induced vasoconstriction phase was increased in heart perfusates from obese mice. Indomethacin and 1-benzylimidazole, both reduced vasoconstriction response in control and obese mice. Vasoconstriction response to TXA2 mimetic analog U46619 was 2.7 higher in obese mice. Obesity increased COX-2, TXS and TX receptor protein expression as well as oxidative stress evaluated by nitrotyrosine and peroxynitrite levels, compared with control mice. Obese mice treated with FeTMPyP, a peroxynitrite scavenger, reversed all these parameters to control levels. These data suggest that alterations in COX pathway may be associated with increased generation of free radicals, including peroxynitrite, that result from the oxidative stress observed in obesity.

Caloric restriction overcomes pre-diabetes and hypertension induced by a high fat diet and renal artery stenosis

BACKGROUND

Calorie restriction (CR) is a type of dietary intervention that is essential in weight loss through modulation of critical metabolic control pathways, is well established and understood in cases of systemic arterial hypertension, however, its role in renovascular hypertension is still unclear.

METHODS

Rats were divided into three groups: SHAM, and two groups that underwent surgery to clip the left renal artery and induce renovascular hypertension (OH and OHR). The SHAM diet was as follows: 14 weeks normolipidic diet; OH: 2 weeks normolipidic diet + 12 weeks hyperlipidic diet, both ad libitum; OHR, 2 weeks normolipidic diet + 8 weeks ad libitum high-fat diet + 4 weeks 40% calorie-restricted high-fat diet.

RESULTS

Rats in the OHR group had decreased blood pressure, body weight, and glucose levels. Reductions in insulinemia and in lipid and islet fibrotic areas in the OHR group were observed, along with increased insulin sensitivity and normalization of insulin-degrading enzyme levels. The expression of nicotinamide phosphoribosyltransferase (NAMPT), insulin receptor (IR), sirtuin 1 (SIRT1), and complex II proteins were increased in the liver tissue of the OHR group. Strong correlations, whether positive or negative, were evaluated via Spearman's model between SIRT1, AMPK, NAMPT, PGC-1α, and NNMT expressions with the restoration of normal blood pressure, weight loss, glycemic and lipid panel, and mitochondrial adaptation.

CONCLUSION

CR provided short-term beneficial effects to recover the physiological parameters induced by a high-fat diet and renal artery stenosis in obese and hypertensive animals. These benefits, even in the short term, can provide physiological benefits in the long term.

Supportive treatment of vascular dysfunction in pediatric subjects with obesity: the OBELIX study

INTRODUCTION

Overweight or obese children develop abnormal endothelial cell dysfunction and arterial intima-media thickening with increased vasomotor tone and inflammation. Curcumin, resveratrol, zinc, magnesium, selenium, and vitamin D have shown beneficial effects on endothelial function. We test, among overweight and obese pediatric subjects, the effects on the endothelium of a combination of curcumin, resveratrol, zinc, magnesium, selenium, and vitamin D.

METHODS

Forty-eight subjects (6-17 years) were randomized into two groups (placebo vs treatment) attended three visits at 0, 3, and 6 months (±15 days). Endothelial function was assessed by means of a post-occlusive release hyperemic (PORH) test for estimation of delta flow (DF) and hyperemic AUC index, and a heat provocation test (HPT) to measure DF HPT (DF_HPT).

RESULTS

Significant DF difference was noted at 6 months in both groups (p < 0.001). Overall time trend was significantly different between baseline, 3 months, and 6 months both in placebo (p < 0.05) and treatment (p < 0.001) groups and their comparison (p < 0.001). No differences were noted in hyperemic AUC index (3 and 6 months), whilst there were significant differences in time trends of rreatment (p < 0.001) and placebo (p < 0.05) groups and their comparison (p < 0.001). DF_HPT difference between groups was significant at 3 and 6 months (p < 0.05). The overall time trend was significant exclusively in Treatment group between 3 and 6 months (p < 0.05). Correlation with anthropometrics was found for DF and body mass index (r = 0.677 6 months, p < 0.05), as well as for hyperemic AUC index and males (r = 0.348, p < 0.05), while DF_HPT showed no correlation.

CONCLUSION

Curcumin, resveratrol, zinc, magnesium, selenium, and vitamin D appear to be promising in enhancing endothelial function by improvement of both DF in the PORH test and DF in the HPT, lowering the risk of developing cardiovascular diseases in overweight and obese pediatric subjects.

Impact of Dietary Restriction Regimens on Mitochondria, Heart, and Endothelial Function: A Brief Overview

Caloric restriction (CR) and intermittent fasting (IF) are strategies aimed to promote health beneficial effects by interfering with several mechanisms responsible for cardiovascular diseases. Both dietary approaches decrease body weight, insulin resistance, blood pressure, lipids, and inflammatory status. All these favorable effects are the result of several metabolic adjustments, which have been addressed in this review, i.e., the improvement of mitochondrial biogenesis, the reduction of reactive oxygen species (ROS) production, and the improvement of cardiac and vascular function. CR and IF are able to modulate mitochondrial function via interference with dynamics (i.e., fusion and fission), respiration, and related oxidative stress. In the cardiovascular system, both dietary interventions are able to improve endothelium-dependent relaxation, reduce cardiac hypertrophy, and activate antiapoptotic signaling cascades. Further clinical studies are required to assess the long-term safety in the clinical setting.

Mitochondrial contributions to vascular endothelial dysfunction, arterial stiffness, and cardiovascular diseases

Cardiovascular disease (CVD) affects one in three adults and remains the leading cause of death in America. Advancing age is a major risk factor for CVD. Recent plateaus in CVD-related mortality rates in high-income countries after decades of decline highlight a critical need to identify novel therapeutic targets and strategies to mitigate and manage the risk of CVD development and progression. Vascular dysfunction, characterized by endothelial dysfunction and large elastic artery stiffening, is independently associated with an increased CVD risk and incidence and is therefore an attractive target for CVD prevention and management. Vascular mitochondria have emerged as an important player in maintaining vascular homeostasis. As such, age- and disease-related impairments in mitochondrial function contribute to vascular dysfunction and consequent increases in CVD risk. This review outlines the role of mitochondria in vascular function and discusses the ramifications of mitochondrial dysfunction on vascular health in the setting of age and disease. The adverse vascular consequences of increased mitochondrial-derived reactive oxygen species, impaired mitochondrial quality control, and defective mitochondrial calcium cycling are emphasized, in particular. Current evidence for both lifestyle and pharmaceutical mitochondrial-targeted strategies to improve vascular function is also presented.

Adipocyte-Endothelium Crosstalk in Obesity

Obesity is characterized by pathological adipose tissue (AT) expansion. While healthy AT expansion enhances systemic insulin sensitivity, unhealthy AT expansion through increased adipocyte size is associated with insulin resistance, fibrosis, hypoxia, and reduced adipose-derived adiponectin secretion. The mechanisms causing the unhealthy AT expansion are not fully elucidated; yet, dysregulated crosstalk between cells within the AT is an important contributor. Evidence from animal and human studies suggests a crucial role of the crosstalk between vascular endothelium (the innermost cell type in blood vessels) and adipocytes for metabolic homeostasis. Arterial endothelial cells are directly involved in maintaining normal organ functions through local blood flow regulation. The endothelial-dependent regulation of blood flow in AT is hampered in obesity, which negatively affects the adipocyte. Moreover, endothelial cells secrete extracellular vesicles (EVs) that target adipocytes in vivo. The endothelial EVs secretion is hampered in obesity and may be affected by the adipocyte-derived adipokine adiponectin. Adiponectin targets the vascular endothelium, eliciting organ-protective functions through binding to T-cadherin. The reduced obesity-induced adiponectin binding of T-cadherin reduces endothelial EV secretion. This affects endothelial health and cell-cell communication between AT cells and distant organs, influencing systemic energy homeostasis. This review focuses on the current understanding of endothelial and adipocyte crosstalk. We will discuss how obesity changes the AT environment and how these changes contribute to obesity-associated metabolic disease in humans. Particularly, we will describe and discuss the EV-dependent communication and regulation between adipocytes, adiponectin, and the endothelial cells regulating systemic energy homeostasis in health and metabolic disease in humans.

Alterations of aorta intima and media transcriptome in swine fed high-fat diet over 1-year follow-up period and of the switch to normal diet

BACKGROUND AND AIM

We previously showed that 12-month high-fat diet (HFD) in pigs led to fattening and increased artery intima-media-thickness, which were partly reversed after 3-month return to control diet (CD). The aim of this study was to decipher underlying mechanism of action by using transcriptomic analyses of intima and media of aorta.

METHODS AND RESULTS

Thirty-two pigs were divided into three groups: CD for 12 months; HFD for 12 months; switch diet group (regression diet; RD): HFD for 9 months followed by CD for 3 months. After 12 months, RNA was isolated from aorta intima and media for nutrigenomic analyses. HFD significantly affected gene expression in intima, while RD gene expression profile was distinct from the CD group. This suggests that switch to CD is not sufficient to correct gene expression alterations induced by HFD but counteracted expression of a group of genes. HFD also affected gene expression in media and as for intima, the expression profile of media of pigs on RD differed from that of these on CD.

CONCLUSIONS

This study revealed nutrigenomic modifications induced by long-term HFD consumption on arterial intima and media. The return to CD was not sufficient to counteract the genomic effect of HFD.

Nox2 dependent redox-regulation of Akt and ERK1/2 to promote left ventricular hypertrophy in dietary obesity of mice

BACKGROUND

A Nox2 containing NADPH oxidase (Nox2) is involved in the global oxidative stress found in dietary obesity and metabolic disorders. However, the effects of high fat diet (HFD) on cardiac Nox2 activation and signaling in left ventricular hypertrophy (LVH) remain unknown.

METHODS

Left ventricular (LV) tissues isolated from C57BL/6J wild-type (WT) and Nox2 knockout (Nox2KO) mice (11 months old, n = 6 per group) after 4 months of HFD treatment were used. Cardiomyocyte sizes were measured digitally on LV cross-sections. The levels of cardiac reactive oxygen species (ROS) production was determined using lucigenin-chemiluminescence and in situ dihydroethidium (DHE) fluorescence. The levels of Nox subunit expression and redox signaling were examined by immunoblotting and immunofluorescence.

RESULTS

In comparison to WT normal chow diet control hearts, WT HFD hearts had 1.8-fold increases in cardiomyocyte size, a sign of cardiac hypertrophy, and this was accompanied with ≥2-fold increase in the levels of ROS production, Nox2 expression and the phosphorylation of Akt and ERK1/2. Increased ROS production measured in HFD heart homogenates was inhibited to control levels by Tiron (a cell membrane permeable O₂^•-scavenger), diphenyleneiodonium (DPI, a flavohaemoprotein inhibitor) and Nox2 ds-tat (a Nox2 assembly inhibitor). However, all of these abnormalities were significantly reduced or absent in Nox2KO hearts under the same HFD.

CONCLUSIONS

Nox2 activation in response to dietary obesity and metabolic disorders plays a key role in cardiac oxidative stress, aberrant redox signaling and cardiomyocyte hypertrophy. Knockout of Nox2 protects hearts from oxidative damage associated with obesity and metabolic disorders.

Calorie Restriction Improves Physical Performance and Modulates the Antioxidant and Inflammatory Responses to Acute Exercise

Our aim was to characterize the effects of calorie restriction on the anthropometric characteristics and physical performance of sportsmen and to evaluate the effects of calorie restriction and acute exercise on mitochondria energetics, oxidative stress, and inflammation. Twenty volunteer taekwondo practitioners undertook a calorie restriction of 30-40% on three alternate days a week for one month. Eleven volunteer sportsmen participated as controls. Both groups performed an energy efficiency test to evaluate physical performance, and samples were taken before and after exercise. The total weight of participants significantly decreased (5.9%) after calorie restriction, while the efficiency of work and the contributions of fat to obtain energy were enhanced by calorie restriction. No significant differences induced by acute exercise were observed in individual non-esterified fatty acid percentage or oxidative stress markers. Calorie restriction downregulated the basal gene expression of nitric oxide synthase, antioxidant enzymes, mitochondrial uncoupling proteins, and repairing stress proteins, but it enhanced the expression of sirtuins in peripheral blood mononuclear cells. In conclusion, one month of calorie restriction decreases body weight and increases physical performance, enhancing energy efficiency, moderating the antioxidant and inflammatory basal gene expression, and influencing its response to acute exercise.

Deficiency of T-type voltage-gated calcium channels results in attenuated weight gain and improved endothelium-dependent dilatation of resistance vessels induced by a high-fat diet in mice

The deletion of T-type Ca_v3.1 channels may reduce high-fat diet (HFD)-induced weight gain, which correlates positively with obesity and endothelial dysfunction. Therefore, experiments were designed to study the involvement of T-type Ca_v3.1 channels in HFD-induced endothelial dysfunction in mice. Wildtype (WT) and Ca_v3.1^-/- mice were fed either a normal diet (ND) or an HFD for 8 weeks. Body composition was assessed, and thoracic aortae and mesenteric arteries were harvested for myography to assess endothelium-dependent responses. Changes in intracellular calcium were measured by fluorescence imaging, and behavior was assessed with the open-field test. Ca_v3.1^-/- mice had attenuated HFD-induced weight gain and lower total fat mass compared with WT mice. Ca_v3.1^-/- mice on an HFD had reduced plasma cholesterol levels compared with WT mice on the same diet. Increased feeding efficiency, independent of food intake, was observed in WT mice on an HFD compared with an ND, but no difference in feeding efficiency between diets was observed for Ca_v3.1^-/- mice. Nitric oxide-dependent dilatation was increased in mesenteric arteries of Ca_v3.1^-/- mice compared with WT mice on an HFD, with no difference observed in aortae. No differences in mouse locomotor activity were observed between the experimental groups. Mice on an HFD lacking T-type channels have reduced weight gain, lower total cholesterol levels, and increased dilatation of resistance vessels compared with WT mice on an HFD, suggesting that Ca_v3.1 deletion protects against endothelial dysfunction in resistance vessels but not in large conduit vessels.

Caloric restriction induces H2O2 formation as a trigger of AMPK-eNOS-NO pathway in obese rats: Role for CAMKII

Caloric restriction (CR) improves endothelial function through the upregulation of adenosine monophosphate-activated protein kinase (AMPK) and endothelial nitric oxide synthase (eNOS). Moreover, hydrogen peroxide (H₂O₂) is upregulated in yeast subjected to CR. Our aim was to assess if mild short-term CR increases vascular H₂O₂ formation as a link with AMPK and eNOS activation. Twelve-week old Zucker obese (fa/fa) and control Zucker lean male rats were fed a standard chow either ad libitum (AL, n=10) or with a 20% CR (CR, n=10) for two weeks. CR significantly improved relaxation to ACh in fa/fa rats because of an enhanced endogenous production of H₂O₂ in aortic rings (H₂O₂ levels _fa/faAL=0.5 ± 0.05 nmol/mg vs. H₂O₂ levels _fa/faCR=0.76 ± 0.07 nmol/mg protein; p<0.05). Expression of mitochondrial superoxide dismutase (Mn-SOD) and total SOD activity were increased in aorta from fa/fa animals after CR. In cultured aortic endothelial cells, serum deprivation or 2-deoxy-d-glucose induced a significant increase in: i) superoxide anion and H₂O₂ levels, ii) p-AMPK/AMPK and p-eNOS/eNOS expression and iii) nitric oxide levels. This effect was reduced by catalase and strongly inhibited by Ca²⁺/calmodulin-dependent kinase II (CamkII) silencing. In conclusion, we propose that mild short-term CR might be a trigger of mechanisms aimed at protecting the vascular wall by the increase of H₂O₂, which then activates AMPK and nitric oxide release, thus improving endothelium-dependent relaxation. In addition, we demonstrate that CAMKII plays a key role in mediating CR-induced AMPK activation through H₂O₂ increase.

Short-Term Low-Carbohydrate High-Fat Diet in Healthy Young Males Renders the Endothelium Susceptible to Hyperglycemia-Induced Damage, An Exploratory Analysis

Postprandial hyperglycemia has been linked to elevated risk of cardiovascular disease. Endothelial dysfunction and/or damage may be one of the mechanisms through which this occurs. In this exploratory study, we determined whether acute glucose ingestion would increase markers of endothelial damage/activation and impair endothelial function before and after a short-term low-carbohydrate high-fat diet (HFD) designed to induce relative glucose intolerance. Nine healthy young males (body mass index 23.2 ± 2 kg/m²) consumed a 75 g glucose drink before and <24 hours after consuming seven days of an iso-energetic HFD consisting of ~70% energy from fat, ~10% energy from carbohydrates, and ~20% energy from protein. CD31+/CD42b- and CD62E+ endothelial microparticles (EMPs) were enumerated at fasting, 1 hour (1 h), and 2 hours (2 h) post-consumption of the glucose drink. Flow-mediated dilation (FMD), arterial stiffness, and diameter, velocity, and flow of the common and internal carotid, and vertebral arteries were assessed in the fasting state and 1 h post glucose consumption. After the HFD, CD31+/CD42b- EMPs were elevated at 1 h compared to 2 h (p = 0.037), with a tendency for an increase above fasting (p = 0.06) only post-HFD. CD62E EMPs followed the same pattern with increased concentration at 1 h compared to 2 h (p = 0.005) post-HFD, with a tendency to be increased above fasting levels (p = 0.078). FMD was reduced at 1 h post glucose consumption both pre- (p = 0.01) and post-HFD (p = 0.005). There was also a reduction in FMD in the fasting state following the HFD (p = 0.02). In conclusion, one week of low-carbohydrate high-fat feeding that leads to a relative impairment in glucose homeostasis in healthy young adults may predispose the endothelium to hyperglycemia-induced damage.

Luteolin Prevents Cardiometabolic Alterations and Vascular Dysfunction in Mice With HFD-Induced Obesity

Purpose: Luteolin exerts beneficial effects against obesity-associated comorbidities, although its influence on vascular dysfunction remains undetermined. We examined the effects of luteolin on endothelial dysfunction in a mouse model of diet-induced obesity. Methods: Standard diet (SD) or high-fat diet (HFD)-fed mice were treated daily with luteolin intragastrically. After 8 weeks, body and epididymal fat weight, as well as blood cholesterol, glucose, and triglycerides were evaluated. Endothelium-dependent relaxations of resistance mesenteric vessels was assessed by a concentration-response curve to acetylcholine, repeated upon N^w-nitro-L-arginine methylester (L-NAME) or ascorbic acid infusion to investigate the influence of nitric oxide (NO) availability and reactive oxygen species (ROS) on endothelial function, respectively. Intravascular ROS production and TNF levels were measured by dihydroethidium dye and ELISA, respectively. Endothelial NO synthase (eNOS) and superoxide dismutase 1 (SOD1), as well as microRNA-214-3p expression were examined by Western blot and RT-PCR assays, respectively. Results: HFD animals displayed elevated body weight, epididymal fat weight and metabolic indexes. Endothelium-dependent relaxation was resistant to L-NAME and enhanced by ascorbic acid, which restored also the inhibitory effect of L-NAME, suggesting a ROS-dependent reduction of NO availability in HFD vessels. Moreover, media-lumen ratio, intravascular superoxide anion and TNF levels were increased, while vascular eNOS, SOD1, and microRNA-214-3p expression were decreased. In HFD mice, luteolin counteracted the increase in body and epididymal fat weight, and metabolic alterations. Luteolin restored vascular endothelial NO availability, normalized the media-lumen ratio, decreased ROS and TNF levels, and normalized eNOS, SOD1 and microRNA-214-3p expression. Conclusion: Luteolin prevents systemic metabolic alterations and vascular dysfunction associated with obesity, likely through antioxidant and anti-inflammatory mechanisms.

Protein Restriction, Epigenetic Diet, Intermittent Fasting as New Approaches for Preventing Age-associated Diseases

Data from epidemiological and experimental studies have shown that diet and eating patterns have a major role in the pathogenesis of many age-associated diseases. Since 1935, calorie restriction (CR) has been identified as one of the most effective nongenetic dietary interventions that can increase lifespan. It involves reducing calorie intake by about 20%–40% below ad libitum, without malnutrition. Restricting food intake has been observed to increase lifespan and prevent many age-associated diseases in rats, mice, and many other species. Understanding the metabolic, molecular, and cellular mechanisms involved in the anti-aging effects of CR can help us to find dietary interventions that can mimic its effects. Recently, different studies have shown that intermittent fasting, protein restriction, and an epigenetic diet can have similar effects to those of CR. These approaches were selected because it has been indicated that they act through a similar molecular pathway and also, are safe and effective in delaying or preventing diseases. In this review, we focus on the mechanistic pathway involved in CR. Then, we review the mimicking interventions through the mechanistic approach. For this purpose, we reviewed both animal and human articles, mainly available through the PubMed online database. We then selected the most relevant full texts which are summarized in this article.

Hypercholesterolemia-Induced Loss of Flow-Induced Vasodilation and Lesion Formation in Apolipoprotein E-Deficient Mice Critically Depend on Inwardly Rectifying K+ Channels

BACKGROUND

Hypercholesterolemia-induced decreased availability of nitric oxide (NO) is a major factor in cardiovascular disease. We previously established that cholesterol suppresses endothelial inwardly rectifying K+ (Kir) channels and that Kir2.1 is an upstream mediator of flow-induced NO production. Therefore, we tested the hypothesis that suppression of Kir2.1 is responsible for hypercholesterolemia-induced inhibition of flow-induced NO production and flow-induced vasodilation (FIV). We also tested the role of Kir2.1 in the development of atherosclerotic lesions.

METHODS AND RESULTS

Kir2.1 currents are significantly suppressed in microvascular endothelial cells exposed to acetylated-low-density lipoprotein or isolated from apolipoprotein E-deficient (Apoe-/- ) mice and rescued by cholesterol depletion. Genetic deficiency of Kir2.1 on the background of hypercholesterolemic Apoe-/- mice, Kir2.1+/-/Apoe-/- exhibit the same blunted FIV and flow-induced NO response as Apoe-/- or Kir2.1+/- alone, but while FIV in Apoe-/- mice can be rescued by cholesterol depletion, in Kir2.1+/-/Apoe-/- mice cholesterol depletion has no effect on FIV. Endothelial-specific overexpression of Kir2.1 in arteries from Apoe-/- and Kir2.1+/-/Apoe-/- mice results in full rescue of FIV and NO production in Apoe-/- mice with and without the addition of a high-fat diet. Conversely, endothelial-specific expression of dominant-negative Kir2.1 results in the opposite effect. Kir2.1+/-/Apoe-/- mice also show increased lesion formation, particularly in the atheroresistant area of descending aorta.

CONCLUSIONS

We conclude that hypercholesterolemia-induced reduction in FIV is largely attributable to cholesterol suppression of Kir2.1 function via the loss of flow-induced NO production, whereas the stages downstream of flow-induced Kir2.1 activation appear to be mostly intact. Kir2.1 channels also have an atheroprotective role.

Detection and analysis of apoptosis- and autophagy-related miRNAs of mouse vascular endothelial cells in chronic intermittent hypoxia model

Endothelial dysfunction is the main pathogenic mechanism of cardiovascular complications induced by obstructive sleep apnea/hyponea syndrome (OSAHS). Chronic intermittent hypoxia (CIH) is the primary factor of OSAHS-associated endothelial dysfunction. The hypoxia inducible factor (HIF) pathway regulates the expression of downstream target genes and mediates cell apoptosis caused by CIH-induced endothelial injury. miRNAs play extensive and important negative regulatory roles in this process at the post-transcriptional level. However, the regulatory mechanism of miRNAs in CIH tissue models remains unclear. The present study established a mouse aortic endothelial cell model of CIH in an attempt to screen out specific miRNAs by using miRNA chip analysis. It was found that 14 miRNAs were differentially expressed. Of them, 6 were significantly different and verified by quantitative real-time PCR (Q-PCR), of which four were up-regulated and two were down-regulated markedly. To gain an unbiased global perspective on subsequent regulation by altered miRNAs, we established signaling networks by GO to predict the target genes of the 6 miRNAs. It was found that the 6 identified miRNAs were apoptosis- or autophagy-related target genes. Down-regulation of miR-193 inhibits CIH induced endothelial injury and apoptosis- or autophagy-related protein expression. In conclusion, our results showed that CIH could induce differential expression of miRNAs, and alteration in the miRNA expression pattern was associated with the expression of apoptosis- or autophagy-related genes.

Healthy human aging: intrinsic and environmental factors

Abstract This review is an attempt to compile current knowledge on concepts and transformations that occur naturally in the human body and that characterize what is defined today as biological aging with quality of life and longevity. Many authors define natural aging as a continuous and uninterrupted process, which occurs in the human body causing structural and functional changes, classified as: cumulative, progressive, intrinsic and deleterious (CUPID). Usually these changes begin early in life and culminate in physical death. Genetic, chemical and biochemical changes lead to progressive degeneration of cells, tissues and organs, body systems and the organism as a whole, leading to loss of structures and functions due to aging. All these changes were discussed in some detail in the review here presented. We concluded that aging is not genetically determined, resulting in the accumulation of cellular and tissue damage, particularly in chromatin and DNA within cells, in addition to structural and bioactive proteins that command the general metabolism. Environmental factors such as feeding (nutrition) and lifestyle were also discussed.

MRI assessment of coronary microvascular endothelial nitric oxide synthase function using myocardial T1 mapping

PURPOSE

Endothelial nitric oxide synthase (eNOS) plays a central role in regulating vascular tone, blood flow, and microvascular permeability. Endothelial dysfunction, including eNOS dysfunction, is an early biomarker of vascular disease. This study aimed to show that myocardial T₁ mapping during nitric oxide synthase (NOS) inhibition could assess coronary microvascular eNOS function.

METHODS

Wild-type mice, eNOS^-/- mice, and wild-type mice fed a high-fat diet underwent T₁ mapping at baseline and for 20 min after injection of N^G -nitro-L-arginine methyl ester (LNAME), a NOS inhibitor. First-pass perfusion MRI was performed in wild-type mice at baseline and 5 min after LNAME injection.

RESULTS

T₁ mapping detected an increase in myocardial T₁ 5 min after an injection of 4 mg/kg LNAME compared with baseline in control mice (T₁  = 1515 ± 30 ms with LNAME versus T₁  = 1402 ± 30 ms at baseline, P < 0.05). No change in myocardial T₁ after LNAME injection was observed in eNOS^-/- mice. The change in T₁ after LNAME injection was less in high-fat-diet mice (ΔT₁  = 31 ± 14 ms at 12 weeks of diet and ΔT₁  = 16 ± 17 ms at 18 weeks of diet) compared with mice fed a standard diet (ΔT₁  = 113 ± 15 ms), with P < 0.05. First-pass MRI measured similar perfusion at baseline and 5 min after LNAME injection.

CONCLUSIONS

NOS inhibition causes an increase in myocardial T₁ in healthy mice, and this effect is mediated through eNOS. T₁ mapping during NOS inhibition detects coronary microvascular eNOS dysfunction in high-fat-diet mice. T₁ mapping during NOS inhibition may be useful in preclinical studies aiming to investigate mechanisms underlying and therapies for coronary microvascular eNOS dysfunction. Magn Reson Med 79:2246-2253, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

WITHDRAWN: Detection and analysis of apoptosis- and autophagy-related miRNAs of vascular endothelial cells in a mouse chronic intermittent hypoxia model

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Caloric Restriction as a Strategy to Improve Vascular Dysfunction in Metabolic Disorders

Caloric restriction (CR) has proved to be the most effective and reproducible dietary intervention to increase healthy lifespan and aging. A reduction in cardiovascular disease (CVD) risk in obese subjects can be already achieved by a moderate and sustainable weight loss. Since pharmacological approaches for body weight reduction have, at present, a poor long-term efficacy, CR is of great interest in the prevention and/or reduction of CVD associated with obesity. Other dietary strategies changing specific macronutrients, such as altering carbohydrates, protein content or diet glycemic index have been also shown to decrease the progression of CVD in obese patients. In this review, we will focus on the positive effects and possible mechanisms of action of these strategies on vascular dysfunction.

Caloric restriction improves diabetes-induced cognitive deficits by attenuating neurogranin-associated calcium signaling in high-fat diet-fed mice

Diabetes-induced cognitive decline has been recognized in human patients of type 2 diabetes mellitus and mouse model of obesity, but the underlying mechanisms or therapeutic targets are not clearly identified. We investigated the effect of caloric restriction on diabetes-induced memory deficits and searched a molecular mechanism of caloric restriction-mediated neuroprotection. C57BL/6 mice were fed a high-fat diet for 40 weeks and RNA-seq analysis was performed in the hippocampus of high-fat diet-fed mice. To investigate caloric restriction effect on differential expression of genes, mice were fed high-fat diet for 20 weeks and continued on high-fat diet or subjected to caloric restriction (2 g/day) for 12 weeks. High-fat diet-fed mice exhibited insulin resistance, glial activation, blood-brain barrier leakage, and memory deficits, in that we identified neurogranin, a down-regulated gene in high-fat diet-fed mice using RNA-seq analysis; neurogranin regulates Ca(2+)/calmodulin-dependent synaptic function. Caloric restriction increased insulin sensitivity, reduced high-fat diet-induced blood-brain barrier leakage and glial activation, and improved memory deficit. Furthermore, caloric restriction reversed high-fat diet-induced expression of neurogranin and the activation of Ca(2+)/calmodulin-dependent protein kinase II and calpain as well as the downstream effectors. Our results suggest that neurogranin is an important factor of high-fat diet-induced memory deficits on which caloric restriction has a therapeutic effect by regulating neurogranin-associated calcium signaling.

Vascular smooth muscle-specific deletion of the leptin receptor attenuates leptin-induced alterations in vascular relaxation

Obesity is a risk factor for cardiovascular disease and is associated with increased plasma levels of the adipose-derived hormone leptin. Vascular smooth muscle cells (VSMC) express leptin receptors (LepR); however, their physiological role is unclear. We hypothesized that leptin, at levels to mimic morbid obesity, impairs vascular relaxation. To test this, we used control and VSM-LepR knockout mice (VSM-LepR KO) created with a tamoxifen-inducible specific Cre recombinase to delete the LepR gene in VSMC. Control (10-12 wk old) and VSM-LepR KO (10-12 wk old) mice were fed a diet containing tamoxifen (50 mg/kg) for 6 wk, after which vascular reactivity was studied in isolated carotid arteries using an organ chamber bath. Vessels were incubated with leptin (100 ng/ml) or vehicle (0.1 mM Tris·HCl) for 30 min. Leptin treatment resulted in significant impairment of vessel relaxation to the endothelial-specific agonist acetylcholine (ACh). When these experiments were repeated in the presence of the superoxide scavenger tempol, relaxation responses to ACh were restored. VSM-LepR deletion resulted in a significant attenuation of leptin-mediated impaired ACh-induced relaxation. These data show that leptin directly impairs vascular relaxation via a VSM-LepR-mediated mechanism, suggesting a potential pathogenic role for leptin to increase cardiovascular risk during obesity.

Oxidative Stress-Dependent Coronary Endothelial Dysfunction in Obese Mice

Obesity is involved in several cardiovascular diseases including coronary artery disease and endothelial dysfunction. Endothelial Endothelium vasodilator and vasoconstrictor agonists play a key role in regulation of vascular tone. In this study, we evaluated coronary vascular response in an 8 weeks diet-induced obese C57BL/6 mice model. Coronary perfusion pressure in response to acetylcholine in isolated hearts from obese mice showed increased vasoconstriction and reduced vasodilation responses compared with control mice. Vascular nitric oxide assessed in situ with DAF-2 DA showed diminished levels in coronary arteries from obese mice in both basal and acetylcholine-stimulated conditions. Also, released prostacyclin was decreased in heart perfusates from obese mice, along with plasma tetrahydrobiopterin level and endothelium nitric oxide synthase dimer/monomer ratio. Obesity increased thromboxane A2 synthesis and oxidative stress evaluated by superoxide and peroxynitrite levels, compared with control mice. Obese mice treated with apocynin, a NADPH oxidase inhibitor, reversed all parameters to normal levels. These results suggest that after 8 weeks on a high-fat diet, the increase in oxidative stress lead to imbalance in vasoactive substances and consequently to endothelial dysfunction in coronary arteries.

Vascular and hepatic impact of short-term intermittent hypoxia in a mouse model of metabolic syndrome

Background

Experimental models of intermittent hypoxia (IH) have been developed during the last decade to investigate the consequences of obstructive sleep apnea. IH is usually associated with detrimental metabolic and vascular outcomes. However, paradoxical protective effects have also been described depending of IH patterns and durations applied in studies. We evaluated the impact of short-term IH on vascular and metabolic function in a diet-induced model of metabolic syndrome (MS).

Methods

Mice were fed either a standard diet or a high fat diet (HFD) for 8 weeks. During the final 14 days of each diet, animals were exposed to either IH (1 min cycle, FiO₂ 5% for 30s, FiO₂ 21% for 30s; 8 h/day) or intermittent air (FiO₂ 21%). Ex-vivo vascular reactivity in response to acetylcholine was assessed in aorta rings by myography. Glucose, insulin and leptin levels were assessed, as well as serum lipid profile, hepatic mitochondrial activity and tissue nitric oxide (NO) release.

Results

Mice fed with HFD developed moderate markers of dysmetabolism mimicking MS, including increased epididymal fat, dyslipidemia, hepatic steatosis and endothelial dysfunction. HFD decreased mitochondrial complex I, II and IV activities and increased lactate dehydrogenase (LDH) activity in liver. IH applied to HFD mice induced a major increase in insulin and leptin levels and prevented endothelial dysfunction by restoring NO production. IH also restored mitochondrial complex I and IV activities, moderated the increase in LDH activity and liver triglyceride accumulation in HFD mice.

Conclusion

In a mouse model of MS, short-term IH increases insulin and leptin levels, restores endothelial function and mitochondrial activity and limits liver lipid accumulation.

Impact of caloric restriction on myocardial ischaemia/reperfusion injury and new therapeutic options to mimic its effects

Caloric restriction (CR) is the most reliable intervention to extend lifespan and prevent age-related disorders in various species from yeast to rodents. Short- and long-term CR confers cardio protection against ischaemia/reperfusion injury in young and even in aged rodents. A few human trials suggest that CR has the potential to mediate improvement of cardiac or vascular function and induce retardation of cardiac senescence also in humans. The underlying mechanisms are diverse and have not yet been clearly defined. Among the known mediators for the benefits of CR are NO, the AMP-activated PK, sirtuins and adiponectin. Mitochondria, which play a central role in such complex processes within the cell as apoptosis, ATP-production or oxidative stress, are centrally involved in many aspects of CR-induced protection against ischaemic injury. Here, we discuss the relevant literature regarding the protection against myocardial ischaemia/reperfusion injury conferred by CR. Furthermore, we will discuss drug targets to mimic CR and the possible role of calorie restriction in preserving cardiovascular function in humans.

Mild caloric restriction reduces blood pressure and activates endothelial AMPK-PI3K-Akt-eNOS pathway in obese Zucker rats

Genetic obesity models exhibit endothelial dysfunction associated to adenosine monophosphate-activated protein kinase (AMPK) dysregulation. This study aims to assess if mild short-term caloric restriction (CR) restores endothelial AMPK activity leading to an improvement in endothelial function. Twelve-week old Zucker lean and obese (fa/fa) male rats had access to standard chow either ad libitum (AL, n=8) or 80% of AL (CR, n=8) for two weeks. Systolic blood pressure was significantly higher in fa/fa AL rats versus lean AL animals, but was normalized by CR. Endothelium-dependent relaxation to acetylcholine (ACh, 10(-9) to 10(-4) M) was reduced in fa/fa AL compared to control lean AL rats (p<0.001), and restored by CR. The AMPK activator AICAR (10(-5) to 8·10(-3) M) elicited a lower relaxation in fa/fa AL rings that was normalized by CR (p<0.001). Inhibition of PI3K (wortmannin, 10(-7) M), Akt (triciribine, 10(-5) M), or eNOS (L-NAME, 10(-4) M) markedly reduced AICAR-induced relaxation in lean AL, but not in fa/fa AL rats. These inhibitions were restored by CR in Zucker fa/fa rings. These data show that mild short-term CR improves endothelial function and lowers blood pressure in obesity due to the activation of the AMPK-PI3K-Akt-eNOS pathway.

p38 mitogen-activated protein kinase is involved in arginase-II-mediated eNOS-uncoupling in obesity

Background

Endothelial nitric oxide synthase (eNOS)-uncoupling links obesity-associated insulin resistance and type-II diabetes to the increased incidence of cardiovascular disease. Studies have indicated that increased arginase is involved in eNOS-uncoupling through competing with the substrate L-arginine. Given that arginase-II (Arg-II) exerts some of its biological functions through crosstalk with signal transduction pathways, and that p38 mitogen-activated protein kinase (p38mapk) is involved in eNOS-uncoupling, we investigated here whether p38mapk is involved in Arg-II-mediated eNOS-uncoupling in a high fat diet (HFD)-induced obesity mouse model.

Methods

Obesity was induced in wild type (WT) and Arg-II-deficient (Arg-II^-/-) mice on C57BL/6 J background by high-fat diet (HFD, 55% fat) for 14 weeks starting from age of 7 weeks. The entire aortas were isolated and subjected to 1) immunoblotting analysis of the protein level of eNOS, Arg-II and p38mapk activation; 2) arginase activity assay; 3) endothelium-dependent and independent vasomotor responses; 4) en face staining of superoxide anion and NO production with Dihydroethidium and 4,5-Diaminofluorescein Diacetate, respectively, to assess eNOS-uncoupling. To evaluate the role of p38mapk, isolated aortas were treated with p38mapk inhibitor SB203580 (10 μmol/L, 1 h) prior to the analysis. In addition, the role of p38mapk in Arg-II-induced eNOS-uncoupling was investigated in cultured human endothelial cells overexpressing Arg-II in the absence or presence of shRNA against p38mapk.

Results

HFD enhanced Arg-II expression/activity and p38mapk activity, which was associated with eNOS-uncoupling as revealed by decreased NO and enhanced L-NAME-inhibitable superoxide in aortas of WT obese mice. In accordance, WT obese mice revealed decreased endothelium-dependent relaxations to acetylcholine despite of higher eNOS protein level, whereas Arg-II^-/- obese mice were protected from HFD-induced eNOS-uncoupling and endothelial dysfunction, which was associated with reduced p38mapk activation in aortas of the Arg-II^-/- obese mice. Moreover, overexpression of Arg-II in human endothelial cells caused eNOS-uncoupling and augmented p38mapk activation. The Arg-II-induced eNOS-uncoupling was prevented by silencing p38mapk. Furthermore, pharmacological inhibition of p38mapk recouples eNOS in isolated aortas from WT obese mice.

Conclusions

Taking together, we demonstrate here for the first time that Arg-II causes eNOS-uncoupling through activation of p38 mapk in HFD-induced obesity.

Endothelial dysfunction in adipose triglyceride lipase deficiency

Systemic knockout of adipose triglyceride lipase (ATGL), the pivotal enzyme of triglyceride lipolysis, results in a murine phenotype that is characterized by progredient cardiac steatosis and severe heart failure. Since cardiac and vascular dysfunction have been closely related in numerous studies we investigated endothelium-dependent and -independent vessel function of ATGL knockout mice. Aortic relaxation studies and Langendorff perfusion experiments of isolated hearts showed that ATGL knockout mice suffer from pronounced micro- and macrovascular endothelial dysfunction. Experiments with agonists directly targeting vascular smooth muscle cells revealed the functional integrity of the smooth muscle cell layer. Loss of vascular reactivity was restored ~50% upon treatment of ATGL knockout mice with the PPARα agonist Wy14,643, indicating that this phenomenon is partly a consequence of impaired cardiac contractility. Biochemical analysis revealed that aortic endothelial NO synthase expression and activity were significantly reduced in ATGL deficiency. Enzyme activity was fully restored in ATGL mice treated with the PPARα agonist. Biochemical analysis of perivascular adipose tissue demonstrated that ATGL knockout mice suffer from perivascular inflammatory oxidative stress which occurs independent of cardiac dysfunction and might contribute to vascular defects. Our results reveal a hitherto unrecognized link between disturbed lipid metabolism, obesity and cardiovascular disease.

Early impairment of skeletal muscle endothelial glycocalyx barrier properties in diet-induced obesity in mice

While previous studies have indicated an important role for the endothelial glycocalyx in regulation of microvascular function, it was recently shown that acute enzymatic glycocalyx degradation in rats was associated with an impaired insulin‐mediated glucose disposal. The aim of this study was to determine whether glycocalyx damage in skeletal muscle occurs at an early stage of diet‐induced obesity (DIO). The microcirculation of the hindlimb muscle of anesthetized C57Bl/6 mice, fed chow (CON) or a high‐fat diet (HFD) for 6 and 18 weeks (w), respectively, was visualized with a Sidestream Dark‐Field camera, and glycocalyx barrier properties were derived from the calculated perfused boundary region (PBR). Subsequently, an intraperitoneal glucose tolerance test was performed and the area under the curve (AUC) of blood glucose was calculated. Impairment of glycocalyx barrier properties was already apparent after 6 weeks of HFD and remained after 18 weeks of HFD (PBR [in μm]: 0.81 ± 0.03 in CON_6w vs. 0.97 ± 0.04 in HFD_6w and 1.02 ± 0.07 in HFD_18w [both P < 0.05]). Glucose intolerance appeared to develop more slowly (AUC [in mmol/L × 120 min]: 989 ± 61 in CON_6w vs. 1204 ± 89 in HFD_6w [P = 0.11] and 1468 ± 84 in HFD_18w [P < 0.05]) than the impairment of glycocalyx barrier properties. The data indicate that damage to the endothelial glycocalyx is an early event in DIO. It is suggested that glycocalyx damage may contribute to the development of insulin resistance in obesity.

In this study we assessed glycocalyx barrier properties in skeletal muscle using Sidestream Dark‐Field imaging at an early and later stage of diet‐induced obesity in mice, by feeding them a high‐fat diet for 6 and 18 weeks, respectively. Glycocalyx barrier properties in hindlimb muscle microcirculation were found to be impaired after 6 weeks already. Our results suggest that in obesity glycocalyx damage represents an early aspect of microvascular dysfunction which may as well contribute to the development of glucose intolerance.

Polymorphism of rs1836882 in NOX4 gene modifies associations between dietary caloric intake and ROS levels in peripheral blood mononuclear cells

Excessive caloric intake is a contributing risk factor for human metabolic disorders. Caloric restriction may prolong a person's life by lowering the incidence of deadly diseases. Reactive oxygen species (ROS) in peripheral blood mononuclear cells (PBMC) have been associated with the biochemical basis of the relationship between caloric intake and pathophysiologic processes. Polymorphisms associated with ROS generation genes are being increasingly implicated in inter-individual responses to daily caloric intake alterations. In the current study, a single nucleotide polymorphism, rs1836882, in the nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4) gene's promoter region was found to modulate associations between dietary caloric intake and ROS levels in PBMC. Based on rs1836882, 656 Chinese Han participants were classified into CC, CT and TT genotypes. ROS levels in PBMC were significantly higher in the CC or CT genotypes compared with the TT genotype with the same increases in daily caloric intake. Using an electrophoretic mobility shift assay, NOX4 promoter region with rs1836882 (T) was observed to have a higher affinity for hepatocyte nuclear factor gamma (HNF3γ) protein than rs1836882 (C). HNF3γ protein over-expression decreased NOX4 gene transcriptional activity in the TT genotype more than in the CC genotype (5.68% vs. 2.12%, P<0.05) in a dual luciferase reporter assay. By silencing the NOX4 gene using small interfering RNA or over-expressing HNF3γ using an expression plasmid, serum from high dietary caloric intake participants decreased ROS levels in PBMC of the TT genotype more than in the CC or CT genotype via HNF3γ down-regulating the NOX4 gene expression signaling pathway. This is the first study to report on the functions of phenotypes of rs1836882 in the NOX4 gene, and it suggests rs1836882 as a candidate gene for interpreting inter-individual ROS levels differences in PBMC induced by alterations in daily caloric intake.

Dietary quercetin attenuates oxidant-induced endothelial dysfunction and atherosclerosis in apolipoprotein E knockout mice fed a high-fat diet: a critical role for heme oxygenase-1

Several lines of evidence indicate that quercetin, a polyphenol derived in the diet from fruit and vegetables, contributes to cardiovascular health. We aimed to investigate the effects of dietary quercetin on endothelial function and atherosclerosis in mice fed a high-fat diet. Wild-type C57BL/6 (WT) and apolipoprotein E gene knockout (ApoE(-/-)) mice were fed: (i) a high-fat diet (HFD) or (ii) a HFD supplemented with 0.05% w/w quercetin (HFD+Q), for 14 weeks. Compared with animals fed HFD, HFD+Q attenuated atherosclerosis in ApoE(-/-) mice. Treatment with the HFD+Q significantly improved endothelium-dependent relaxation of aortic rings isolated from WT but not ApoE(-/-) mice and attenuated hypochlorous acid-induced endothelial dysfunction in aortic rings of both WT and ApoE(-/-) mice. Mechanistic studies revealed that HFD+Q significantly improved plasma F2-isoprostanes, 24h urinary nitrite, and endothelial nitric oxide synthase activity, and increased heme oxygenase-1 (HO-1) protein expression in the aortas of both WT and ApoE(-/-) mice (P<0.05). HFD+Q also resulted in small changes in plasma cholesterol (P<0.05 in WT) and plasma triacylglycerols (P<0.05 in ApoE (-/-)mice). In a separate experiment, quercetin did not protect against hypochlorite-induced endothelial dysfunction in arteries obtained from heterozygous HO-1 gene knockout mice with low expression of HO-1 protein. Quercetin protects mice fed a HFD against oxidant-induced endothelial dysfunction and ApoE(-/-) mice against atherosclerosis. These effects are associated with improvements in nitric oxide bioavailability and are critically related to arterial induction of HO-1.

Preserved endothelial function in human obesity in the absence of insulin resistance

Background

Insulin resistance (IR) is frequently associated with endothelial dysfunction and has been proposed to play a major role in cardiovascular disease (CVD). On the other hand, obesity has long been related to IR and increased CVD. However it is not known if IR is a necessary condition for endothelial dysfunction in human obesity, allowing for preserved endothelial function in obese people when absent. Therefore, the purpose of the study was to assess the relationship between IR and endothelial dysfunction in human obesity and the mechanisms involved.

Methods

Twenty non-insulin resistant morbid obese (NIR-MO), 32 insulin resistant morbid obese (IR-MO), and 12 healthy subjects were included. Serum concentrations of glucose, insulin, interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), resistin and adiponectin were determined. IR was evaluated by HOMA-index. Endothelium-dependent relaxation to bradykinin (BK) in mesenteric microvessels was assessed in wire myograph.

Results

Serum IL-6, and TNF-α levels were elevated only in IR-MO patients while resistin was elevated and adiponectin reduced in all MO individuals. Mesenteric arteries from IR-MO, but not from NIR-MO subjects displayed blunted relaxation to BK. Vasodilatation was improved in IR-MO arteries by the superoxide scavenger, superoxide dismutase (SOD) or the mitochondrial-targeted SOD mimetic, mito-TEMPO. NADPH oxidase inhibitors (apocynin and VAS2870) and the nitric oxide synthase (NOS) cofactor, tetrahydrobiopterin failed to modify BK-induced vasodilatations. Superoxide generation was higher in vessels from IR-MO subjects and reduced by mito-TEMPO. Blockade of TNF-α with infliximab, but not inhibition of inducible NOS or cyclooxygenase, improved endothelial relaxation and decreased superoxide formation.

Conclusions

Endothelial dysfunction is observed in human morbid obesity only when insulin resistance is present. Mechanisms involved include augmented mitochondrial superoxide generation, and increased systemic inflammation mediated by TNF-α. These findings may explain the different vascular risk of healthy vs unhealthy obesity.

Obesity impairs vasodilatation and blood flow increase mediated by endothelial nitric oxide: an overview

Obesity dramatically increases the risk of development of cardiovascular and metabolic diseases. Endothelial dysfunction induced by obesity is an important risk factor that impairs blood flow controls in various organs. Impaired endothelial function occurs early in life in obese children. Obesity-induced endothelial dysfunction is associated with decreased nitric oxide (NO) production due to impaired endothelial NO synthase activity and expression and increased production of superoxide anion and the endogenous NOS inhibitor ADMA, together with increased vasoconstrictor factors, such as endothelin-1 and sympathetic nerve activation. Decreased endothelial progenitor cells are also involved in endothelial cell senescence in obese individuals. Insulin resistance and diabetes mellitus augment obesity-induced endothelial dysfunction. Adipokines liberated from adipose tissues play roles in modulating endothelial function; adiponectin and ghrelin have beneficial effects on endothelial cells. Effects of leptin on endothelial function are controversial. Decreased body weight by physical exercise, dietary interventions, and bariatric surgery are effective measures that reverse endothelial dysfunction; however, the weight control is not only the reason for improving of endothelia function. Pharmacological therapies with β-adrenoceptor antagonists, resveratolol, anti-obesity agents, nifedipine, and NADPH oxidase inhibitors may also be effective; however, these treatments have to be utilized under the basis of exercise and dietary controls.

[Energy restriction reduces oxidative stress in the aorta and heart and corrects the atherogenic risk in obese rat]

AIM OF THE STUDY

The aim was to see if 40% of caloric restriction can improve in rats, the oxidative stress induced by a high fat diet on liver, heart and aorta, and have a positive impact on the lipoproteins-cholesterol contents.

METHODS

Male Wistar rats (n=12) consumed at weaning obesegenic diet. The obese rats were divided into two groups (n=6) each consumed for 4 weeks a normocaloric diet (1,60 MJ) or a calorie restricted diet (40% of energy of the standard diet [0.96 MJ]). A control group (n=6) was fed a standard diet during the experiment.

RESULTS

Caloric restriction decreased cholesterol and low-density lipoproteins-cholesterol, whereas the high-density lipoproteins-cholesterol was elevated. Levels of cholesterol in the aorta and heart were lowered in the group that consumed caloric restriction compared to normocaloric diet. The values of thiobarbituric acid reactive substances and hydroperoxides were lowered in the aorta and the heart. The caloric restriction compared to normocaloric diet increased positively the superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase activities in the heart and those of catalase and superoxide dismutase in aorta.

CONCLUSION

In obese rats, caloric restriction may play a role in the antioxidant defense of cardiovascular system by reducing proatherogenic cholesterol and lipid peroxidation and increasing the antioxidant activity of some enzymes, which was in favor of reduction of cardiometabolic risk associated with obesity.

Caloric restriction reverses obesity-induced mammary gland inflammation in mice

Obesity is a risk factor for the development of hormone receptor-positive breast cancer in postmenopausal women. Estrogen synthesis is catalyzed by aromatase. Recently, we identified an obesity→inflammation→aromatase axis in mouse models and women. In mouse models of obesity, inflammatory foci characterized by crown-like structures (CLS) consisting of dead adipocytes encircled by macrophages were found in the mammary gland. CLS of the breast were found in most overweight and obese women. CLS were associated with adipocyte hypertrophy, activation of NF-κB, elevated levels of proinflammatory mediators and aromatase, and increased expression of the progesterone receptor (PR). Collectively, these findings provide a plausible explanation for the link between obesity, chronic inflammation, and postmenopausal breast cancer. Here, we investigated whether caloric restriction (CR) reversed the inflammatory state and related molecular changes in the mammary gland of obese mice. Obese ovariectomized C57BL/6J mice were subjected to 30% CR for 7 or 14 weeks. Findings in CR mice were compared with the results in mice fed a high-fat diet ad libitum or with control mice fed a low-fat diet. CR was associated with more than a 75% decrease in mammary CLS/cm(2). Reduced histologic inflammation following CR was associated with decreased adipocyte diameter and monocyte chemoattractant protein-1 (MCP-1) levels, reduced NF-κB binding activity, and normalization of levels of proinflammatory mediators, aromatase, and PR. In summary, obesity-related inflammation of the mammary gland and elevated aromatase and PR levels were reversed with CR. Our results provide a rationale for determining whether weight loss can reverse breast inflammation associated with obesity in women.

Preventive and therapeutic effects of quercetin on lipopolysaccharide-induced oxidative stress and vascular dysfunction in mice

Quercetin, a dietary antioxidant flavonoid, possesses strong anti-inflammatory and cytoprotective activities. The effects were investigated in an animal model of lipopolysaccharide (LPS)-induced endotoxaemia and vascular dysfunction in vivo. Male ICR mice were injected with LPS (10 mg/kg; i.p.). Quercetin (50 or 100 mg/kg) was intragastrically administered either before or after LPS administration. Fifteen hours after LPS injection, mice were found in endotoxaemic condition, as manifested by hypotension, tachycardia, and blunted vascular responses to vasodilators and vasoconstrictor. The symptoms were accompanied by increased aortic iNOS protein expression, decreased aortic eNOS protein expression, marked suppression of cellular glutathione (GSH) redox status, enhanced aortic superoxide production, increased plasma malodialdehyde and protein carbonyl, and elevated urinary nitrate/nitrite. Treatment with quercetin either before or after LPS preserved the vascular function, as blood pressure, heart rate, vascular responsiveness were restored to near normal values, particularly when quercetin was given as a preventive regimen. The vascular protective effects were associated with upregulation of eNOS expression, reduction of oxidative stress, and maintained blood GSH redox ratio. Overall findings suggest the beneficial effect of quercetin on the prevention and restoration of a failing eNOS system and alleviation of oxidative stress and vascular dysfunction against endotoxin-induced shock in mice.

[Caloric restriction suppresses endothelial cells senescence via down-regulation of NOX4 induced by HNF3γ]

The aim of current study is to investigate the molecular mechanism that caloric restriction (CR) suppresses endothelial cells senescence. Human aortic endothelial cells (HAECs) were divided into 5 groups: control group, high caloric group (about 1.5 times caloric intake of control group), low caloric group (about 0.5 times caloric intake of control group), siRNA plus low caloric group (low caloric treatment pretreated with special siRNA targeting hepatocyte nuclear factor 3γ (HNF3γ)), and siRNA plus high caloric group (high caloric treatment pretreated with special siRNA targeting HNF3γ). The gene and protein expressions of HNF3γ and NADPH oxidase 4 (NOX4) were quantified by real-time quantitative PCR (RT-qPCR) and Western blotting, respectively. Intracellular reactive oxygen species (ROS) production was measured by flow cytometry. Endothelial cells senescence was assayed by senescence associated β-galactosidase staining. After verifying the binding of HNF3γ to NOX4 promoter region by chromatin immunoprecipitation assay (ChIP), NOX4 promoter activity was assayed by dual-luciferase reporter system. Compared with the control group, the mRNA and protein expression levels of HNF3γ,and the ratio of phosphorylated HNF3γ protein increased significantly (P<0.05) in low caloric group, and decreased significantly (P<0.05) in high caloric group and siRNA plus low or high caloric group; whereas the mRNA and protein levels of NOX4 intracellular ROS and endothelial cells senescence decreased significantly (P<0.05) in low caloric group and increased significantly (P<0.05) in high caloric group and siRNA plus low or high caloric group. ChIP result showed there were four HNF3γ binding sites in NOX4 gene promoter region (-6, -76, -249 and -954 bp) and HNF3γ could bind to all 4 predicted sites. According to the results of dual-luciferase reporter system, HNF3γ binding to 1 site (-6 bp), 2 sites (-6 and -76 bp), 3 sites (-6, -76 and -249 bp) and 4 sites(-6, -76, -249 and -954 bp) could suppress NOX4 promoter activity to 80.15±4.64%, 40.02.±2.15%, 16.46±2.24% and 12.13±1.46% compared with that of baseline, respectively ( P<0.05). In a word, low caloric intake decreases the production of intracellular ROS and suppresses endothelial cells senescence through promoting HNF3γ binging to NOX4 promoter region and inhibiting NOX4 gene expression induced by up-regulated HNF3γ.

Caloric restriction and redox state: does this diet increase or decrease oxidant production?

Calorie restriction (CR) is well established to enhance the lifespan of a wide variety of organisms, although the mechanisms are still being uncovered. Recently, some authors have suggested that CR acts through hormesis, enhancing the production of reactive oxygen species (ROS), activating stress response pathways, and increasing lifespan. Here, we review the literature on the effects of CR and redox state. We find that there is no evidence in rodent models of CR that an increase in ROS production occurs. Furthermore, results in Caenorhabditis elegans and Saccharomyces cerevisiae suggesting that CR increases intracellular ROS are questionable, and probably cannot be resolved until adequate, artifact free, tools for real-time, quantitative, and selective measurements of intracellular ROS are developed. Overall, the largest body of work indicates that CR improves redox state, although it seems improbable that a global improvement in redox state is the mechanism through which CR enhances lifespan.

Association of ALOX15 gene polymorphisms with obesity-related phenotypes in Chinese nuclear families with male offspring

AIM

Genetic variation in ALOX12, which encoded human 12-lipoxygenase, was found to be associated with fat mass in young Chinese men. The objective of this study was to investigate the relationship between single nucleotide polymorphisms (SNPs) and haplotypes in the ALOX15 gene and obesity-related phenotypes in Chinese nuclear families with male offspring.

METHODS

We recruited 1,296 subjects from 427 nuclear families with male offspring and genotyped five SNPs (rs9894225, rs748694, rs2619112, rs2619118, and rs916055) in the ALOX15 gene locus. The total fat mass (TFM), trunk fat mass (tFM), leg fat mass (LFM) and arm fat mass (AFM) were measured using dual-energy X-ray absorptiometry (DXA). The percentage of fat mass (PFM) was the ratio of TFM and body weight. The association between SNPs and haplotypes of ALOX15 and obesity-related phenotypic variation was measured using quantitative transmission disequilibrium test (QTDT).

RESULTS

Using QTDT to measure family-based genetic association, we found that rs916055 had a statistically significant association with PFM (P=0.038), whereas rs916055 had a marginal but statistically insignificant association with tFM (P=0.093). The multiple-parameter 1000 permutations test agreed with the family-based association results: both showed that rs916055 had a statistically significant association with PFM (P=0.033).

CONCLUSION

rs916055 in ALOX15 gene was significantly associated with the percentage of fat mass in Chinese nuclear families with male offspring in the family-based association study using QTDT approach.

Fetoplacental vascular endothelial dysfunction as an early phenomenon in the programming of human adult diseases in subjects born from gestational diabetes mellitus or obesity in pregnancy

Gestational diabetes mellitus (GDM) and obesity in pregnancy (OP) are pathological conditions associated with placenta vascular dysfunction coursing with metabolic changes at the fetoplacental microvascular and macrovascular endothelium. These alterations are seen as abnormal expression and activity of the cationic amino acid transporters and endothelial nitric oxide synthase isoform, that is, the "endothelial L-arginine/nitric oxide signalling pathway." Several studies suggest that the endogenous nucleoside adenosine along with insulin, and potentially arginases, are factors involved in GDM-, but much less information regards their role in OP-associated placental vascular alterations. There is convincing evidence that GDM and OP prone placental endothelium to an "altered metabolic state" leading to fetal programming evidenced at birth, a phenomenon associated with future development of chronic diseases. In this paper it is suggested that this pathological state could be considered as a metabolic marker that could predict occurrence of diseases in adulthood, such as cardiovascular disease, obesity, diabetes mellitus (including gestational diabetes), and metabolic syndrome.

Moderate dietary restriction reduces p53-mediated neurovascular damage and microglia activation after hypoxic ischemia in neonatal brain

BACKGROUND AND PURPOSE

Neurovascular damage, including neuronal apoptosis and blood-brain barrier (BBB) damage, and microglia activation account for the hypoxic-ischemia (HI) susceptibility in neonatal brain. The p53 upregulation is involved in apoptosis, endothelial cell damage, and microglia activation. We hypothesized that underweight induced by dietary restriction (DR) protects against HI in rat pups by attenuating p53-mediated neurovascular damage.

METHODS

Male rat pups were grouped as normal litter (NL) size (12 pups/dam), DR (18 pups/dam), and extreme DR (24 pups/dam) from postnatal day 1 and subjected to HI on postnatal day 7. Immunohistochemistry and immunoblotting were used to determine p53, phospho-murine double minute-2, caspases, BBB damage and microglia activation, and immunofluorescence to determine the cellular distribution of p53. Pharmacological approaches were used to regulate p53.

RESULTS

The NL, DR, and extreme DR pups had similar TUNEL-positive cells and caspases on postnatal day 7 and comparable learning performance at adulthood. After HI, the DR-HI, but not extreme DR-HI, pups had significantly lower p53, higher phospho-murine double minute-2, lower cleaved caspases, less BBB damage and microglia activation, and less brain volume loss than NL-HI pups. In NL-HI pups, p53 expression was located mainly in the neurons, endothelial cells, and microglia. The p53 blockage by pifithrin-α in NL-HI pups decreased apoptosis, BBB damage, and microglia activation, and was neuroprotective. In contrast, upregulating p53 by nutlin-3 in DR-HI pups increased apoptosis, BBB damage, and microglia activation, and worsened brain damage.

CONCLUSIONS

Moderate DR, but not extreme DR, reduces p53-mediated neurovascular damage after HI and confers long-term protection in neonatal brain.