Reciprocal relationships between abnormal metabolic parameters and endothelial dysfunction

Exploring the underlying pharmacological, immunomodulatory, and anti-inflammatory mechanisms of phytochemicals against wounds: a molecular insight

BACKGROUND

Numerous cellular, humoral, and molecular processes are involved in the intricate process of wound healing.

PHARMACOLOGICAL RELEVANCE

Numerous bioactive substances, such as ß-sitosterol, tannic acid, gallic acid, protocatechuic acid, quercetin, ellagic acid, and pyrogallol, along with their pharmacokinetics and bioavailability, have been reviewed. These phytochemicals work together to promote angiogenesis, granulation, collagen synthesis, oxidative balance, extracellular matrix (ECM) formation, cell migration, proliferation, differentiation, and re-epithelialization during wound healing.

FINDINGS AND NOVELTY

To improve wound contraction, this review delves into how the application of each bioactive molecule mediates with the inflammatory, proliferative, and remodeling phases of wound healing to speed up the process. This review also reveals the underlying mechanisms of the phytochemicals against different stages of wound healing along with the differentiation of the in vitro evidence from the in vivo evidence There is growing interest in phytochemicals, or plant-derived compounds, due their potential health benefits. This calls for more scientific analysis and mechanistic research. The various pathways that these phytochemicals control/modulate to improve skin regeneration and wound healing are also briefly reviewed. The current review also elaborates the immunomodulatory modes of action of different phytochemicals during wound repair.

Circulating metabolic biomarkers and risk of new-onset hypertension: findings from the UK Biobank

OBJECTIVE

The evidence regarding the associations of circulating metabolic biomarkers with hypertension risk is scarce. We aimed to examine the associations between circulating metabolites and risk of hypertension.

METHODS

We included 49 422 individuals free of hypertension at baseline with a mean (SD) age of 53.5 (8.0) years from the UK Biobank. Nuclear magnetic resonance spectroscopy was used to quantify 143 individual metabolites. Multivariable-adjusted Cox regression models were used to estimate hazard ratios and 95% confidence intervals (CIs).

RESULTS

During a mean (SD) follow-up of 11.2 (1.8) years, 2686 incident hypertension cases occurred. Out of 143 metabolites, 76 were associated with incident hypertension, among which phenylalanine (hazard ratio: 1.40; 95% CI: 1.24-1.58) and apolipoprotein A1 (hazard ratio: 0.76; 95% CI: 0.66-0.87) had the strongest association when comparing the highest to the lowest quintile. In general, very-low-density lipoprotein (VLDL) particles were positively, whereas high-density lipoprotein (HDL) particles were inversely associated with risk of hypertension. Similar patterns of cholesterol, phospholipids, and total lipids within VLDL and HDL particles were observed. Triglycerides within all lipoproteins were positively associated with hypertension risk. Other metabolites showed significant associations with risk of hypertension included amino acids, fatty acids, ketone bodies, fluid balance and inflammation markers. Adding 10 selected metabolic biomarkers to the traditional hypertension risk model modestly improved discrimination (C-statistic from 0.745 to 0.752, P < 0.001) for prediction of 10-year hypertension incidence.

CONCLUSION

Among UK adults, disturbances in metabolic biomarkers are associated with incident hypertension. Comprehensive metabolomic profiling may provide potential novel biomarkers to identify high-risk individuals.

Association between seaweed intake and risk of type 2 diabetes mellitus: a prospective cohort study

This study aimed to identify the longitudinal association between seaweed and type 2 diabetes mellitus (T2DM) in the Korean population. Data from 148 404 Korean adults aged 40 years and older without a history of T2DM, cardiovascular disease or cancer at baseline were obtained from the Korean Genome and Epidemiology Study data. The participants' seaweed intake was obtained using a validated semi-quantitative food frequency questionnaire, and the diagnosis of T2DM was surveyed through a self-reported questionnaire during follow-up. The hazard ratio (HR) and 95 % confidence interval (CI) for T2DM were calculated using the Cox proportional hazard regression, and the dose-response relationship was analysed using a restricted cubic spline regression. Participants had a mean follow-up period of 5 years. Participants with the highest seaweed intake had a 7 % lower risk of T2DM compared with the group with the lowest intake (95 % CI (0·87, 0·99)). Interestingly, this association was stronger in those with normal weight (HR: 0·88, 95 % CI (0·81, 0·95)), while no association was observed in participants with obesity. Spline regression revealed an inverse linear relationship between seaweed intake and T2DM risk in participants with normal weight, showing a trend where increased seaweed intake is related to lower instances of T2DM (Pfor nonlinearity = 0·48). Seaweed intake is inversely associated with the onset of T2DM in Korean adults with normal weight.

Hemodynamics and Arterial Stiffness in Response to Oral Glucose Loading in Individuals with Type II Diabetes and Controlled Hypertension

INTRODUCTION

Type 2 diabetes (T2D), the fastest growing pandemic, is typically accompanied by vascular complications. A central hallmark of both T2D and vascular disease is insulin resistance which causes impaired glucose transport and vasoconstriction concomitantly. Those with cardiometabolic disease display greater variation in central hemodynamics and arterial elasticity, both potent predictors of cardiovascular morbidity and mortality, which may be exacerbated by concomitant hyperglycemia and hyperinsulinemia during glucose testing. Thus, elucidating central and arterial responses to glucose testing in those with T2D may identify acute vascular pathophysiologies triggered by oral glucose loading.

AIM

This study compared hemodynamics and arterial stiffness to an oral glucose challenge (OGC: 50g glucose) between individuals with and without T2D. 21 healthy (48 ± 10 years) and 20 participants with clinically diagnosed T2D and controlled hypertension (52 ± 8 years) were tested.

METHODS

Hemodynamics and arterial compliance were assessed at baseline, and 10, 20, 30, 40, 50, and 60 min post-OGC.

RESULTS

Heart rate increased between 20 and 60 post-OGC in both groups (p < 0.05). Central systolic blood pressure (SBP) decreased in the T2D group between 10 and 50 min post-OGC while central diastolic blood pressure (DBP) decreased in both groups from 20 to 60 post-OGC. Central SBP decreased in T2D between 10 and 50 min post-OGC and central DBP decreased in both groups between 20 and 60 min post-OGC. Brachial SBP decreased between 10 and 50 min in healthy participants, whereas both groups displayed decreases in brachial DBP between 20 and 60 min post-OGC. Arterial stiffness was unaffected.

CONCLUSIONS

An OGC alters central and peripheral blood pressure in healthy and T2D participants similarly with no changes in arterial stiffness.

Intestinal flora variation reflects the short-term damage of microplastic to the intestinal tract in mice

The potential toxicity of microplastic (MPs) to organisms has attracted extensive attention. However, due to the subacute toxicity of MPs, the biological effect is hard to verify in short-term exposure experiment. Here, by tracking the dynamics of gut microbes, mice model was utilized to evaluate the toxicity of compositional MPs (PE, PET, PP, PS and PVC). After 7 days digestive exposure, the physiological indicators were normal as the control group that the body weight and serum cholesterol levels were insignificant change. Whereas, through histopathological examination, all the treatment groups suffered colon tissue damage, among which PS had the most inflammatory cells. Moreover, the high-throughput sequencing results revealed great variation of intestinal flora in treated mice. The ratio of Bacteroidetes and Firmicutes in PE, PET and PP treatment groups heighten, and the relative abundance of Ruminococcaceae and Lachnospiraceae increased significantly at family levels. At the genus level, Alistipes bacteria in PS treatment group significantly decreased that is associated with obesity risk. It indicated that MPs induced inflammatory response would further interfere the dynamics of intestinal flora causing health effect in living organisms. This work shed light on MPs toxicity in short-term exposure and supplied research paradigm of MPs health risk assessment.

Ellagic Acid: A Review on Its Natural Sources, Chemical Stability, and Therapeutic Potential

Ellagic acid (EA) is a bioactive polyphenolic compound naturally occurring as secondary metabolite in many plant taxa. EA content is considerable in pomegranate (Punica granatum L.) and in wood and bark of some tree species. Structurally, EA is a dilactone of hexahydroxydiphenic acid (HHDP), a dimeric gallic acid derivative, produced mainly by hydrolysis of ellagitannins, a widely distributed group of secondary metabolites. EA is attracting attention due to its antioxidant, anti-inflammatory, antimutagenic, and antiproliferative properties. EA displayed pharmacological effects in various in vitro and in vivo model systems. Furthermore, EA has also been well documented for its antiallergic, antiatherosclerotic, cardioprotective, hepatoprotective, nephroprotective, and neuroprotective properties. This review reports on the health-promoting effects of EA, along with possible mechanisms of its action in maintaining the health status, by summarizing the literature related to the therapeutic potential of this polyphenolic in the treatment of several human diseases.

Associations between the lipid profile and the development of hypertension in young individuals - the preliminary study

INTRODUCTION

Hypertension is the leading direct cause of death in the world and one of the most important risk factors for cardiovascular disease (CVD). Elevated blood pressure (BP) often coexists with lipid disorders and is an additional factor that increases CV risk. Nowadays, we are able to distinguish low density lipoproteins (LDL) and high density lipoproteins (HDL) subfractions. Except LDL also HDL small subfractions can increase the risk of CV events. Therefore, we aimed to investigate the associations between changes of lipoprotein subfractions and the risk of hypertension development.

MATERIAL AND METHODS

In 2-year long study 200 volunteers with normal blood pressure at the age of 19-32 years were included. Each volunteer underwent detailed medical examination, 12-lead electrocardiogram was taken at rest, echocardiogram, lipid subfraction assessment (using Lipoprint®) and two 24-hour BP measurements.

RESULTS

Mean total cholesterol concentration was 189 mg/dl (4.89 mmol/l), with mean LDL concentration of 107 mg/dl (2.77 mmol/l), HDL of 63 mg/dl (1.63 mmo/l), very low-density lipoprotein (VLDL) of 40 mg/dl (1.04 mmol/l) and triglycerides (TG) of 89 mg/dl (1.00 mmol/l). Subfractions LDL 1-3 were most abundant, LDL 4-5 making up a marginal portion and LDL 6-7 were not observed. Whereas, subfractions HDL 4-6 were most abundant, in lower concentration was present HDL 1-3 and HDL 8-10. We showed that increased systolic blood pressure coreclated significantly with HDL cholesterol concentrations (p = 0.0078), HDL intermediate subgractions (p = 0.0451), with HDL-3 subfraction (p = 0.0229), and intermediate density lipoprotein-A (IDL-A) (p = 0.038). A significant correlation between increased diastolic blood pressure and HDL lipoprotein levels (p = 0.0454) was only observed.

CONCLUSIONS

Obtained results indicating correlation between total HDL levels and HDL-3 subfraction concentration (for systolic BP) and the tendency to develop hypertension.

Health benefits of walnut polyphenols: An exploration beyond their lipid profile

Walnuts are commonly found in our diet and have been recognized for their nutritious properties for a long time. Traditionally, walnuts have been known for their lipid profile, which has been linked to a wide array of biological properties and health-promoting effects. In addition to essential fatty acids, walnuts contain a variety of other bioactive compounds, such as vitamin E and polyphenols. Among common foods and beverages, walnuts represent one of the most important sources of polyphenols, hence their effect over human health warrants attention. The main polyphenol in walnuts is pedunculagin, an ellagitannin. After consumption, ellagitannins are hydrolyzed to release ellagic acid, which is converted by gut microflora to urolithin A and other derivatives such as urolithins B, C, and D. Ellagitannins possess well known antioxidant and anti-inflammatory bioactivity, and several studies have assessed the potential role of ellagitannins against disease initiation and progression, including cancer, cardiovascular, and neurodegenerative diseases. The purpose of this review is to summarize current available information relating to the potential effect of walnut polyphenols in health maintenance and disease prevention.

Deletion of interleukin 1 receptor-associated kinase 1 (Irak1) improves glucose tolerance primarily by increasing insulin sensitivity in skeletal muscle

Chronic inflammation may contribute to insulin resistance via molecular cross-talk between pathways for pro-inflammatory and insulin signaling. Interleukin 1 receptor-associated kinase 1 (IRAK-1) mediates pro-inflammatory signaling via IL-1 receptor/Toll-like receptors, which may contribute to insulin resistance, but this hypothesis is untested. Here, we used male Irak1 null (k/o) mice to investigate the metabolic role of IRAK-1. C57BL/6 wild-type (WT) and k/o mice had comparable body weights on low-fat and high-fat diets (LFD and HFD, respectively). After 12 weeks on LFD (but not HFD), k/o mice (versus WT) had substantially improved glucose tolerance (assessed by the intraperitoneal glucose tolerance test (IPGTT)). As assessed with the hyperinsulinemic euglycemic glucose clamp technique, insulin sensitivity was 30% higher in the Irak1 k/o mice on chow diet, but the Irak1 deletion did not affect IPGTT outcomes in mice on HFD, suggesting that the deletion did not overcome the impact of obesity on glucose tolerance. Moreover, insulin-stimulated glucose-disposal rates were higher in the k/o mice, but we detected no significant difference in hepatic glucose production rates (± insulin infusion). Positron emission/computed tomography scans indicated higher insulin-stimulated glucose uptake in muscle, but not liver, in Irak1 k/o mice in vivo Moreover, insulin-stimulated phosphorylation of Akt was higher in muscle, but not in liver, from Irak1 k/o mice ex vivo In conclusion, Irak1 deletion improved muscle insulin sensitivity, with the effect being most apparent in LFD mice.

Vascular and metabolic effects of omega-3 fatty acids combined with fenofibrate in patients with hypertriglyceridemia

BACKGROUND

Effects of omega-3 fatty acids (n-3 FA) combined with fenofibrate are not yet investigated, compared with fenofibrate.

METHODS

This was a randomized, single-blind, placebo-controlled, parallel study. Age, sex, and body mass index were matched among groups. All patients were recommended to maintain a low fat diet. Fifty patients with hypertriglyceridemia in each group were given placebo, n-3 FA 2g+fenofibrate 160mg (combination), or fenofibrate 160mg, respectively daily for 2months.

RESULTS

Placebo, combination, and fenofibrate significantly decreased triglycerides by 7%, 41% and 30%, respectively and triglycerides/HDL cholesterol ratio by 11%, 45% and 32%, respectively relative to baseline measurements (all P<0.05 by paired t-test). When compared with placebo and fenofibrate, these with combination were significant (P<0.001 by ANOVA). When compared with placebo, both combination and fenofibrate significantly decreased apolipoprotein B and non-HDL cholesterol and improved flow-mediated dilation and reduced CRP and fibrinogen (all P<0.05 by ANOVA), however, there were no significant differences between combination and fenofibrate. When compared with placebo, both combination and fenofibrate significantly reduced insulin and glucose (both P<0.05 by ANOVA), and improved insulin sensitivity (P=0.005 by ANOVA). However, there were no significant differences between combination and fenofibrate.

CONCLUSIONS

When compared with fenofibrate, combination significantly decreased triglycerides and triglycerides/HDL cholesterol ratio. Otherwise, combination and fenofibrate significantly reduced apolipoprotein B and non-HDL cholesterol and improved flow-mediated dilation and reduced CRP and fibrinogen to a similar extent. Also, combination and fenofibrate significantly improved insulin sensitivity to a similar extent by reducing insulin and glucose in patients with hypertriglyceridemia.

The role of abnormal metabolic conditions on arterial stiffness in healthy subjects with no drug treatment

BACKGROUND

Subjects with abnormal metabolic conditions had increased risk for cardiovascular disease. We investigated the role of abnormal metabolic conditions on arterial stiffness in healthy subjects with no drug treatment.

METHODS

A total 601 subjects (age 48.7 ± 11.8 years, male 46.2 %, hypertension 19.1 %) were enrolled. Major cardiovascular risk factors, metabolic conditions and parameters (pre-diabetes, diabetes mellitus, metabolic syndrome, fasting blood sugar (FBS), glycated hemoglobin), lipid profiles, hsCRP, and brachial ankle pulse wave velocity (baPWV) were measured.

RESULTS

Subjects with metabolic syndrome (n = 200) had higher baPWV than in subjects without metabolic syndrome (n = 401) even after adjustments for age, sex and presence of hypertension (1435.9 ± 212.2 vs. 1336.5 ± 225.0 cm/sec, p < 0.001). The differences of baPWV among normal FBS, prediabetes and diabetes mellitus groups are significant (P for trend = 0.036) by multivariate analysis (adjustments for age, sex, office systolic blood pressure). Subjects with diabetes mellitus (n = 30) had higher baPWV than in subjects with normal FBS (n = 384, 1525 ± 267.1 vs. 1341.5 ± 224.1 cm/sec, P = 0.016 adjustments for age, sex, office systolic blood pressure). BaPWV in subjects with prediabetes (n = 187) was slightly higher, but not statistically significant than in subjects with normal FBS (P = 0.377). Of interest, FBS was one of the independent predictors for increased baPWV (β = 0.809, 95 % CI 0.222-1.397, p = 0.007) by multivariate analysis.

CONCLUSIONS

Subjects with abnormal metabolic conditions have increased arterial stiffness independent of age and BP which may contribute to the development of cardiovascular disease.

Vascular reactivity and biomarkers of endothelial function in healthy subjects exposed to acute hypobaric hypoxia

AIMS

The aim of this study was to evaluate the effects of acute hypobaric hypoxia (HH) on vascular reactivity and biochemical markers associated with endothelial function (EF).

MAIN METHODS

Ten healthy subjects were exposed to a simulated altitude of 4,000 meters above sea level for 4 hours in a hypobaric chamber. Vascular reactivity was measured by the flow-mediated vasodilatation (FMVD) test. Endothelin-1, high sensitive-C reactive protein (hsCRP), vascular cell adhesion molecule 1, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), paraoxonase and adiponectin levels, and FMVD were evaluated before and after the exposure.

KEY FINDINGS

Subjects were young (age: 32±6 years), lean [body mass index: 23.9±2.0kg/m(2), waist circumference: 77(IQR: 72-80) cm], and presented normal clinical and biochemical parameters. No significant changes were evidenced in FMVD in response to HH (pre: 0.45 (0.20-0.70) vs. during: 0.50 (0.20-1.22) mm; p=0.594). On the other hand, endothelin-1 (+54%, p<0.05), hsCRP (+37%, p<0.001), IL-6 (+75%, p<0.05), TNF-α (+75%, p<0.05), and adiponectin (-39%, p<0.01) levels were significantly altered post-HH. FMVD was increased in 7 subjects, and it was decreased in 3 individuals during HH exposure. Interestingly, when EF biomarkers were compared between these two subgroups of subjects, only post exposure-adiponectin levels were significantly different (49±5 vs. 38±6μg/ml, respectively, p<0.05).

SIGNIFICANCE

HH exposure had an effect on endothelin-1, adiponectin, hsCRP, IL-6, and TNF-α concentration. However, adiponectin was the only biomarker associated with an altered vascular reactivity.

Relationships between adipokines, biomarkers of endothelial function and inflammation and risk of type 2 diabetes

AIMS

Identification of novel biomarkers of diabetes risk help to understand mechanisms of pathogenesis and improve risk prediction. Our objectives were to examine the relationships between adipokines, biomarkers of inflammation and endothelial function and development of type 2 diabetes; and to assess the relevance of including these biomarkers in type 2 diabetes prediction risk models.

METHODS

1345 subjects from the SU.VI.MAX study, who were free of diabetes at baseline and who completed 13 years of follow-up were included in the present analyses. Odds ratios (OR) with 95% confidence intervals (95% CI) of incident type 2 diabetes associated with a 1-SD increase in adiponectin, leptin, C-reactive protein (CRP), soluble intracellular adhesion modecule-1 (sICAM-1), soluble vascular cell adhesion molecule 1 (sVCAM-1), E-selectin and monocyte chemoattractant protein-1 (MCP-1) were estimated. Predicitive performances of models including biomarkers were assessed with area under the receiver operating curves (AUC) and integrated discrimination improvement (IDI) statistics.

RESULTS

82 subjects developed type 2 diabetes during follow-up. The risk of developing type 2 diabetes increased with increasing concentrations of leptin (2.04 (1.28;3.26)), sICAM-1 (1.39 (1.08;1.78)) and sVCAM-1 (1.29 (1.01;1.64)). Type 2 diabetes associations with leptin remained significant after adjusting for a combination of biomarkers. Models adjusted for novel biomarkers had improved performance compared to models adjusted for classical risk factors as assessed by IDI, but not by AUC.

CONCLUSIONS

Adipokines, biomarkers of inflammation and endothelial function were significantly associated to onset of type 2 diabetes. However their inclusion in predictive scores is not supported by the present study.

Differential metabolic actions of specific statins: clinical and therapeutic considerations

SIGNIFICANCE

Statins, the most widely prescribed drugs in clinical practice, mainly act by reducing the plasma level of low-density lipoprotein (LDL)-cholesterol. A shift in redox homeostasis to an imbalance between reactive oxygen species generation and endogenous antioxidant mechanisms results in oxidative stress that has been implicated in the pathogenesis of various diseases, including those of the cardiovascular system. Beyond their efficacy in lowering LDL cholesterol, statins modulate redox systems that are implicated in the development of atherosclerosis, cardiovascular morbidity, and mortality.

RECENT ADVANCES

Differences in specific statins or their dosages result in differential metabolic actions arising from off-target or unknown mechanisms of action that can have important implications for overall patient morbidity and mortality.

CRITICAL ISSUES

A recent meta-analysis and a combined analysis have suggested that high doses of statins increase the risk of developing type 2 diabetes mellitus, but reduce the risk of cardiovascular events. Thus, it is important to consider the cardiovascular and metabolic context and natural history of diseases when choosing a specific statin therapy for optimal individual patient health over the long term.

FUTURE DIRECTIONS

More information is needed regarding the metabolism of statins, and the off-target or unknown actions of statins in affecting insulin resistance and metabolic homeostasis. The differential metabolic effects of specific statins should be considered in formulating optimal therapeutic strategies to reduce not just cardiovascular-related but also overall patient morbidity and mortality.

Statins and renin-angiotensin system inhibitor combination treatment to prevent cardiovascular disease

Hypercholesterolemia and hypertension are common risk factors for cardiovascular disease (CVD). Updated guidelines emphasize target reductions of overall cardiovascular risks. Experimental studies have shown reciprocal relationships between insulin resistance (IR) and endothelial dysfunction. Hypercholesterolemia and hypertension have a synergistic deleterious effect on IR and endothelial dysfunction. Unregulated renin-angiotensin system (RAS) is important in the pathogenesis of atherosclerosis and hypertension. Various strategies with different classes of antihypertensive medications to reach target goals have failed to reduce residual CVD risk further. Of interest, treating moderate cholesterol elevations with low-dose statins in hypertensive patients reduced CVD risk by 35-40% further. Therefore, statins are important in reducing CVD risk. Unfortunately, statin therapy causes IR and increases the risk of type 2 diabetes mellitus. RAS inhibitors improve both endothelial dysfunction and IR. Further, cross-talk between hypercholesterolemia and RAS exists at multiple steps of IR and endothelial dysfunction. In this regard, combined therapy with statins and RAS inhibitors demonstrates additive/synergistic effects on endothelial dysfunction and IR in addition to lowering cholesterol levels and blood pressure when compared with either monotherapy in patients. This is mediated by both distinct and interrelated mechanisms. Therefore, combined therapy with statins and RAS inhibitors may be important in developing optimal management strategies in patients with hypertension, hypercholesterolemia, diabetes, metabolic syndrome, or obesity to prevent CVD.  

Combination pravastatin and valsartan treatment has additive beneficial effects to simultaneously improve both metabolic and cardiovascular phenotypes beyond that of monotherapy with either drug in patients with primary hypercholesterolemia

Statin and angiotensin II type 1 receptor blocker therapy improves endothelial dysfunction using distinct mechanisms. We evaluated simultaneous vascular and metabolic responses to pravastatin and valsartan therapy, alone or in combination, in hypercholesterolemic patients. Forty-eight hypercholesterolemic patients (23 had metabolic syndrome) were given pravastatin 40 mg and placebo, pravastatin 40 mg and valsartan 160 mg, or valsartan 160 mg and placebo daily during each 2-month treatment period in a randomized, single-blind, placebo-controlled, crossover trial with three treatment arms and two washout periods (each 2 months). Brachial artery flow-mediated dilation and C-reactive protein improved to a greater extent with combined therapy compared with either monotherapy. Importantly, we also observed simultaneous improvement in metabolic phenotypes, with all three treatments causing increased plasma adiponectin levels, reduced fasting insulin levels, and increased insulin sensitivity relative to baseline measurements. For the first time in a statin combination trial, pravastatin combined with valsartan therapy increased plasma adiponectin, lowered fasting insulin levels, and improved insulin sensitivity in an additive manner when compared with monotherapy alone. In contrast to other statins, hydrophilic pavastatin may be combined with other drugs to safely reach lipid target levels while simultaneously improving the metabolic and cardiovascular phenotype of patients at high risk.

The influence of fenofibrate on lipid profile, endothelial dysfunction, and inflammatory markers in type 2 diabetes mellitus patients with typical and mixed dyslipidemia

BACKGROUND

Type 2 diabetes is associated with early development of endothelial dysfunction. Patients present with typical dyslipidemia (predominantly high levels of triglycerides [TG] and low levels of high-density lipoprotein cholesterol [HDL-C]) or mixed hypercholesterolemia (high levels of low-density lipoprotein cholesterol [LDL-C] and TG with low HDL-C). Normal levels include LDL-C < 100 mg/dL, TG < 135 mg/dL, and HDL-C > 40 mg/dL for men and >50 mg/dL for women.

OBJECTIVE

To determine the effects of 8 weeks' administration of fenofibrate on inflammatory markers, metabolic parameters, and endothelial dysfunction.

METHODS

We administered micronized fenofibrate (Laboratories Fourneir S.A Dijon, France) daily for 8 weeks to 40 dyslipidemic, type 2 diabetes patients with equal numbers in each arm of the typical or mixed dyslipidemia groups. Noninvasive endothelial function assessments were performed and serum inflammatory markers obtained before and after treatment.

RESULTS

The typical group demonstrated significantly greater TG reduction and HDL-C increment, ie, 56% vs, 21.3% (P < .005) and 21% vs. 7.6% (P = .001), respectively, compared with the mixed group. There was greater LDL-C reduction within the mixed group compared with the typical group 21.0% vs. 2.2% (P < .05). Endothelial dysfunction was present in both groups at baseline. After treatment, the typical group demonstrated significant improvement in resting brachial diameter (3.9 mm [interquartile range {IQR} 3.3-4.7] to 4.2 mm [IQR 3.4-4.8], P = .001) compared with no change within the mixed group (3.6 mm [IQR 3.1-5.4] to 3.7 mm [IQR 3.1-5.3], P = .26). Flow-mediated diameter improved significantly in both groups. The mixed group had significantly greater levels of hs-CRP at baseline but no changes throughout the study. The mixed group demonstrated an increase in vascular adhesion molecule-1 from 706 ng/mL (IQR 566-1195) to 845 ng/mL (637-1653; P = .01), a reduction of tumor necrosis factor-α from 7.0 pg/mL (IQR 1.0-43.5) to 2.5 pg/mL (IQR 1.5-13.5; P = .04) throughout the study.

CONCLUSIONS

We effectively compared 8 weeks of fenofibrate therapy in type 2 diabetics with contrasting lipid abnormalities. The typical dyslipidemia group showed significantly greater lipid improvements compared with the mixed dyslipidemia group. Both groups had improvements in endothelial functions that were independent of the lipid levels. We concluded that fibrate therapy in type 2 diabetics is beneficial, especially those with typical dyslipidemia and extends beyond its lipid lowering properties.

Rosuvastatin does not affect fasting glucose, insulin resistance, or adiponectin in patients with mild to moderate hypertension

The effects of statins on insulin resistance and new-onset diabetes are unclear. The purpose of this study was to evaluate the effects of rosuvastatin on insulin resistance and adiponectin in patients with mild to moderate hypertension. In a randomized, prospective, single-blind study, 53 hypertensive patients were randomly assigned to the control group (n=26) or the rosuvastatin (20 mg once daily) group (n=27) during an 8-week treatment period. Both groups showed significant improvements in systolic blood pressure and flow-mediated dilation (FMD) after 8 weeks of treatment. Rosuvastatin treatment improved total cholesterol, low-density lipoprotein (LDL)-cholesterol, and triglyceride levels. The control and rosuvastatin treatment groups did not differ significantly in the change in HbA1c (3.0±10.1% vs. -1.3±12.7%; p=0.33), fasting glucose (-1.3±18.0% vs. 2.5±24.1%; p=0.69), or fasting insulin levels (5.2±70.5% vs. 22.6±133.2%; p=0.27) from baseline. Furthermore, the control and rosuvastatin treatment groups did not differ significantly in the change in the QUICKI insulin sensitivity index (mean change, 2.2±11.6% vs. 3.6±11.9%; p=0.64) or the HOMA index (11.6±94.9% vs. 32.4±176.7%; p=0.44). The plasma adiponectin level increased significantly in the rosuvastatin treatment group (p=0.046), but did not differ significantly from that in the control group (mean change, 23.2±28.4% vs. 23.1±27.6%; p=0.36). Eight weeks of rosuvastatin (20 mg) therapy resulted in no significant improvement or deterioration in fasting glucose levels, insulin resistance, or adiponectin levels in patients with mild to moderate hypertension.

Overexpression of steroidogenic acute regulatory protein in rat aortic endothelial cells attenuates palmitic acid-induced inflammation and reduction in nitric oxide bioavailability

BACKGROUND

Endothelial dysfunction is a well documented evidence for the onset of atherosclerosis and other cardiovascular diseases. Lipids disorder is among the main risk factors for endothelial dysfunction in these diseases. Steroidogenic acute regulatory protein (StAR), one of the cholesterol transporters, plays an important role in the maintenance of intracellular lipid homeostasis. However, the effect of StAR on endothelial dysfunction is not well understood. Palmitic acid (PA) has been shown to decrease eNOS activity and induce inflammation, both are the causes of endothelial dysfunction, in an endothelial cell culture model.

METHODS

StAR gene was introduced into primary rat aortic endothelial cells by adenovirus infection. Real-time PCR and Western blotting were performed to determine the relative genes and proteins expression level to elucidate the underlying mechanism. The free fatty acid and cholesterol quantification kits were used to detect total cellular free fatty acid and cholesterol. The levels of inflammatory factors and nitric oxide were determined by ELISA and classic Griess reagent methods respectively.

RESULTS

We successfully overexpressed StAR in primary rat aortic endothelial cells. Following StAR overexpression, mRNA levels of IL-1β, TNFα, IL6 and VCAM-1 and protein levels of IL-1β, , TNFα and IL-6 in culture supernatant were significantly decreased, which duing to blocke NFκB nuclear translocation and activation. Moreover, StAR overexpression attenuated the PA-induced reduction of nitric oxide bioavailability by protecting the bioactivity of pAkt/peNOS/NO pathway. Furthermore, the key genes involved in lipid metabolism were greatly reduced following StAR overexpression. In order to investigate the underlying mechanism, cerulenin and lovastatin, the inhibitor of fatty acid and cholesterol synthase, were added prior to PA treatment. The results showed that both cerulenin and lovastatin had a similar effect as StAR overexpression. On the other hand, the role of StAR was inhibited when siRNA was introduced to reduce StAR expression.

CONCLUSIONS

Our results showed that StAR attenuated lipid synthesis and uptake as well as PA-induced inflammation and reduction in NO bioavailability in aortic endothelial cells. StAR can ameliorate endothelial dysfunction induced by PA via reducing the intracellular lipid levels.

Association of the DDAH2 gene polymorphism with type 2 diabetes and hypertension

AIMS

The aim of this study was to investigate whether the polymorphism of DDAH2 is associated with type 2 diabetes and hypertension in Korean population.

METHODS

Total 605 subjects were included in this study: 403 patients with type 2 diabetes and 202 non-diabetic control subjects. The SNP rs805304 and rs2272592 in DDAH2 were analyzed. We examined the association of SNP rs805304 and rs2272592 in DDAH2 with type 2 diabetes and hypertension.

RESULTS

SNP rs2272592 was significantly associated with type 2 diabetes (P<0.001) while SNP rs805304 was not (P=0.716). We observed that the prevalence of the AG+GG genotypes were significantly greater than AA homozygotes in type 2 diabetes (AA vs AG+GG; OR 20.74, 95% CI 6.48-66.35, P<0.001). Significance was maintained after adjusting for age, sex, BMI, DBP and BUN (OR 21.03, 95% CI 2.83-151.14, P=0.003). Both SNP rs805304 and rs2272592 in DDAH2 were not significantly associated with hypertension.

CONCLUSIONS

In the present study, we found that SNP rs2272592 in DDAH2 is associated with type 2 diabetes but SNP rs805304 in DDAH2 is not. DDAH2 SNP rs2272592 AG+GG genotypes are associated with genetic susceptibility to type 2 diabetes in Korean population.

Significant differential effects of omega-3 fatty acids and fenofibrate in patients with hypertriglyceridemia

BACKGROUND

Omega-3 fatty acids and fenofibrate are both used to treat patients with hypertriglyceridemia. However, a head-to-head comparison of the lipoprotein and metabolic effects of these two medicines has not been published.

METHODS

This was a randomized, single-blind, placebo-controlled, parallel study. Age, sex, and body mass index were matched among groups. All patients were recommended to maintain a low fat diet. Fifty patients in each group were given placebo, omega-3 fatty acids 2 g (most commonly used dosage in Korean patients), or fenofibrate 160 mg, respectively daily for 2 months.

RESULTS

Omega-3 fatty acids therapy decreased triglycerides by 21% and triglycerides/HDL cholesterol and improved flow-mediated dilation (P<0.01), however, did not significantly change insulin, plasma adiponectin levels, and insulin sensitivity (determined by QUICKI) relative to baseline measurements. Fenofibrate therapy decreased total cholesterol, triglycerides by 29%, and triglycerides/HDL-cholesterol (all P<0.01) and improved flow-mediated dilation when compared with baseline. When compared with placebo and omega-3 fatty acids, fenofibrate therapy decreased non-HDL cholesterol (P<0.001) and triglycerides/HDL cholesterol (P=0.016) while increasing HDL cholesterol (P<0.001) and apolipoprotein AI (P=0.001). Of note, when compared with omega-3 fatty acids, fenofibrate therapy decreased fasting insulin (P=0.023) and increased plasma adiponectin (P=0.002) and insulin sensitivity (P=0.015).

CONCLUSIONS

Omega-3 fatty acids and fenofibrate therapy promoted similar changes in triglycerides and endothelium-dependent dilation. However, fenofibrate therapy had substantially better effects on lipoprotein and metabolic profiles in patients with hypertriglyceridemia.

Lipoprotein subclass abnormalities and incident hypertension in initially healthy women

BACKGROUND

Abnormalities in traditional lipids, particularly decreased HDL cholesterol and increased triglycerides, can precede the onset of hypertension. Whether lipoprotein particle size or subclass concentrations play a role in the development of hypertension is unknown.

METHODS

We followed 17 527 initially healthy women without baseline hypertension prospectively for 8 years. At baseline, information regarding traditional lipids and hypertension risk factors was obtained, and lipoprotein size and subclass concentrations were measured by nuclear magnetic resonance spectroscopy.

RESULTS

Baseline lipoprotein size and subclass concentrations were significantly associated with incident hypertension. Although LDL cholesterol was not associated with hypertension [odds ratio (OR) for quintile 5 vs 1: 1.08 (95% CI 0.96-1.20)], increased concentrations of LDL particles were associated with greater risk [OR 1.73 (1.54-1.95)], especially small LDL particles [OR 1.62 (1.45-1.83)]. Increased HDL cholesterol was associated with lower risk of hypertension [OR for quintile 5 vs 1: 0.79 (0.70-0.89)]. By contrast, increased concentrations of HDL particles had greater risk [OR 1.48 (1.32-1.67)], especially small HDL particles [OR 1.36 (1.22-1.53)], whereas large HDL particles had lower risk [OR 0.80 (0.71-0.90)]. Triglycerides and triglyceride-rich VLDL particles were positively associated with hypertension, with large VLDL particles associated with greater risk [OR 1.68 (1.50-1.89)]. Adding particle subclasses improved discrimination over a model with traditional lipids and risk factors (c-statistic 0.671 compared to 0.676; P < 0.001).

CONCLUSIONS

In this study of initially healthy women, lipoprotein particle size and subclass concentrations were associated with incident hypertension and provided additive information to traditional lipids and risk factors.

Contributions of dysglycaemia, obesity, and insulin resistance to impaired endothelium-dependent vasodilation in humans

BACKGROUND

Individual effects of hyperglycaemia and obesity to impair vascular health are recognized. However, the relative contributions of dysglycaemia versus other obesity-related traits to vascular dysfunction have not been systematically evaluated.

METHODS

We undertook a cross-sectional evaluation of factors contributing to vascular function in 271 consecutive subjects, categorized as non-obese normal glucose tolerant (n = 115), non-obese dysglycaemic (n = 32), obese normal glucose tolerant (n = 57), obese dysglycaemic (n = 38), or type 2 diabetic (n = 29). Vascular function was measured invasively as leg blood flow responses to methacholine chloride, an endothelium-dependent vasodilator. Categorical and continuous analyses were carried out to assess the contributions of hyperglycaemia to vascular dysfunction.

RESULTS

Even among normoglycaemic subjects, obese subjects had impaired vascular function compared to non-obese subjects (p = 0.004). Vascular function was also impaired in non-obese dysglycaemic subjects (p = 0.04 versus non-obese normoglycaemic subjects), to a level comparable to normoglycaemic obese subjects. Within obese subject groups, gradations of dysglycaemia including the presence of diabetes were not associated with further worsening of these vascular responses beyond the effect of obesity alone (p = not significant comparing all obese groups, p < 0.001 versus lean normoglycaemic subjects). After univariate and multivariable modelling analyses we found that effects of glycaemia were less powerful than effects of insulin resistance and obesity on vascular dysfunction.

CONCLUSIONS

Dysglycaemia contributes to impaired vascular function in non-obese subjects, but obesity and insulin resistance are more important determinants of vascular function in obese and diabetic subjects.

Sulfation of 25-hydroxycholesterol by SULT2B1b decreases cellular lipids via the LXR/SREBP-1c signaling pathway in human aortic endothelial cells

OBJECTIVE

25-Hydroxycholesterol (25HC) and its sulfated metabolite, 25-hydroxycholesterol-3-sulfate (25HC3S), regulate certain aspects of lipid metabolism in opposite ways. Hence, the enzyme for the biosynthesis of 25HC3S, oxysterol sulfotransferase (SULT2B1b), may play a crucial role in regulating lipid metabolism. We evaluate the effect of 25HC sulfation on lipid metabolism by overexpressing the gene encoding SULT2B1b in human aortic endothelial cells (HAECs) in culture.

METHODS AND RESULTS

The human SULT2B1b gene was successfully overexpressed in HAECs following infection using a recombinant adenovirus. HPLC analysis demonstrated that more than 50% of (3)H-25HC was sulfated in 24h following overexpression of the SULT2B1b gene. In the presence of 25HC, SULT2B1b overexpression significantly decreased mRNA and protein levels of LXR, ABCA1, SREBP-1c, ACC-1, and FAS, which are key regulators of lipid biosynthesis and transport; and subsequently reduced cellular lipid levels. Overexpression of the gene encoding SULT2B1b gave similar results as adding exogenous 25HC3S. However, in the absence of 25HC or in the presence of T0901317, synthetic liver oxysterol receptor (LXR) agonist, SULT2B1b overexpression had no effect on the regulation of key genes involved in lipid metabolism.

CONCLUSIONS

Our data indicate that sulfation of 25HC by SULT2B1b plays an important role in the maintenance of intracellular lipid homeostasis via the LXR/SREBP-1c signaling pathway in HAECs.

Differential metabolic effects of distinct statins

Reciprocal relationships between endothelial dysfunction and insulin resistance suggest that therapies improving endothelial dysfunction will simultaneously improve insulin sensitivity and other metabolic parameters. However, previous studies with some statins either did not alter insulin sensitivity or promoted insulin resistance despite significant improvements in endothelial dysfunction and decreases in circulating pro-inflammatory markers. This may be due to pleiotropic or off-target effects of some statins to cause insulin resistance by diverse mechanisms unrelated to endothelial dysfunction. Indeed, there is evidence of other differential metabolic actions of distinct statins including effects on hydroxymethylglutaryl-CoA reductase inhibition, isoprotenoid synthesis, calcium release, glucose transport, insulin secretion, and/or insulin resistance. Pravastatin increases expression of adiponectin mRNA, enhances adiponectin secretion, increases plasma levels of adiponectin, and enhances insulin sensitivity in mice and humans. Clinical studies including large scale randomized controlled trials demonstrate potential differences between individual statins, with pravastatin promoting risk reduction for new onset of diabetes. Conversely, other statins including atorvastatin, rosuvastatin, and simvastatin all promote significant increase in this risk. Given the frequent concordance of metabolic diseases including diabetes, obesity, and metabolic syndrome with cardiovascular diseases associated with hyperlipidemia, it is important to understand the potential metabolic risks and benefits of therapies with distinct statins. In this review, we discuss these differential effects of statins on metabolic homeostasis and insulin sensitivity.

Beta-sitosterol exhibits anti-inflammatory activity in human aortic endothelial cells

beta-Sitosterol, normally present in vegetable-containing diets, comprises an important component of cholesterol controlling functional foods. It has been associated with cardiovascular protection, exerting its effect mainly through increasing the antioxidant defense system and effectively lowering the serum cholesterol levels in humans. However, its anti-inflammatory effect on endothelium is unknown. Attachment of leukocytes to the vascular endothelium and the subsequent migration of cells into the vessel wall are early events in atherogenesis, this process requiring the expression of endothelial adhesion molecules. We examined the effect of beta-sitosterol (0.1-200 microM) on (i) the expression of vascular adhesion molecule 1 and intracellular adhesion molecule 1 by cell ELISA and (ii) the attachment of monocytes (U937 cells) in tumor necrosis factor-alpha (TNF-alpha)-stimulated human aortic endothelial cells (HAECs) by adhesion assay. The effect on nuclear factor-kB phosphorylation was also examined via a cell-based ELISA kit. Results showed that beta-sitosterol inhibits significantly vascular adhesion molecule 1 and intracellular adhesion molecule 1 expression in TNF-alpha-stimulated HAEC as well as the binding of U937 cells to TNF-alpha-stimulated HAEC and attenuates the phosphorylation of nuclear factor-kB p65. This study extends existing data regarding the cardioprotective effect of beta-sitosterol and provides new insights into understanding the molecular mechanism underlying the beneficial effect of beta-sitosterol on endothelial function.

Improved endothelial function with simvastatin but unchanged insulin sensitivity with simvastatin or ezetimibe

In addition to their expected effects on lipid profile, lipid-lowering agents may reduce cardiovascular events because of effects on nonclassic risk factors such as insulin resistance and inflammation. Ezetimibe specifically blocks the absorption of dietary and biliary cholesterol as well as plant sterols. Although it is known that an additional reduction of low-density lipoprotein cholesterol (LDL-C) levels can be induced by the combination of ezetimibe with statins, it is not known if this can enhance some pleiotropic effects, which may be useful in slowing the atherosclerotic process. This study assessed the effects of simvastatin and ezetimibe, in monotherapy or in combination, on markers of endothelial function and insulin sensitivity. Fifty prediabetic subjects with normo- or mild-to-moderate hypercholesterolemia were randomly allocated to 2 groups receiving either ezetimibe (10 mg/d) or simvastatin (20 mg/d) for 12 weeks, after which the drugs were combined for both groups for an additional 12-week period. Clinical and laboratory parameters were measured at baseline and after 12 and 24 weeks of therapy. Homeostasis model assessment of insulin resistance index and the area under the curve of insulin were calculated. As expected, both groups receiving drugs in isolation significantly reduced total cholesterol, LDL-C, apolipoprotein B, and triglyceride levels; and additional reductions were found after the combination period (P < .05). After 12 weeks of monotherapy, plasminogen activator inhibitor-1 levels and urinary albumin excretion were lower in the simvastatin than in the ezetimibe group. No change in homeostasis model assessment of insulin resistance index, area under the curve of insulin, and adiponectin levels was observed after either the monotherapies or the combined therapy. However, simvastatin combined with ezetimibe provoked significant reductions in E-selectin and intravascular cellular adhesion molecule-1 levels that were independent of LDL-C changes. Our findings support claims that simvastatin may be beneficial in preserving endothelial function in prediabetic subjects with normo- or mild-to-moderate hypercholesterolemia. Alternatively, a deleterious effect of ezetimibe on the endothelial function is suggested, considering the increase in intravascular cellular adhesion molecule-1 and E-selectin levels. Simvastatin and ezetimibe, in isolation or in combination, do not interfere with insulin sensitivity.

Silent Partner in Blood Vessel Homeostasis? Pervasive Role of Nitric Oxide in Vascular Disease

The endothelium generates powerful mediators that regulate blood flow, temper inflammation and maintain a homeostatic environment to prevent both the initiation and progression of vascular disease. Nitric oxide (NO) is arguably the single most influential molecule in terms of dictating blood vessel homeostasis. In addition to direct effects associated with altered NO production (e.g. vasoconstriction, excessive inflammation, endothelial dysfunction), NO is a critical modulator of vaso-relevant pathways including cyclooxygenase (COX)-derived prostaglandin production and angiotensin II generation by the renin-angiotensin system. Furthermore, NO may influence the selectivity of COX-2 inhibitors and ultimately contribute to controversies associated with the use of these drugs. Consistent with a central role for NO in vascular disease, disruptions in the production and bioavailability of NO have been linked to hypertension, diabetes, hypercholesterolemia, obesity, aging, and smoking. The ability of the vessel wall to control disease-associated oxidative stress may be the most critical determinant in maintaining homeostatic levels of NO and subsequently the prospect of stroke, myocardial infarction and other CV abnormalities. To this end, investigation of mechanisms that alter the balance of protective mediators, including pathways that are indirectly modified by NO, is critical to the development of effective therapy in the treatment of CV disease.

Muscle contraction, but not insulin, increases microvascular blood volume in the presence of free fatty acid-induced insulin resistance

OBJECTIVE

Insulin and contraction each increase muscle microvascular blood volume (MBV) and glucose uptake. Inhibiting nitric oxide synthase blocks insulin's but not contraction's effects. We examined whether contraction could augment the MBV increase seen with physiologic hyperinsulinemia and whether free fatty acid (FFA)-induced insulin resistance differentially affects contraction- versus insulin-mediated increases in MBV.

RESEARCH DESIGN AND METHODS

Rats were fasted overnight. Plasma FFAs were increased by intralipid/heparin infusion (3 h), insulin was increased with a euglycemic clamp (3 mU x min(-1) x kg(-1)), and hindlimb muscle contraction was electrically stimulated. Muscle MBV was measured using contrast-enhanced ultrasound. Insulin transport into muscle was measured using (125)I-insulin. BQ-123 (0.4 mg/h) was used to block the endothelin-1 (ET-1) receptor A.

RESULTS

Superimposing contraction on physiologic hyperinsulinemia increased MBV within 10 min by 37 and 67% for 0.1 or 1 Hz, respectively (P < 0.01). FFA elevation alone did not affect MBV, whereas 0.1 Hz stimulation doubled MBV (P < 0.05) and increased muscle insulin uptake (P < 0.05) despite high FFA. Physiologic hyperinsulinemia during FFA elevation paradoxically decreased MBV (P < 0.05). This MBV decrease was reversed by either 0.1 Hz contraction or ET-1 receptor A antagonism, and the combination raised MBV above basal.

CONCLUSIONS

Contraction recruits microvasculature beyond that seen with physiologic hyperinsulinemia by a distinct mechanism that is not blocked by FFA-induced vascular insulin resistance. The paradoxical MBV decline seen with insulin plus FFA may result from differential inhibition of insulin-stimulated nitric oxide-dependent vasodilation relative to ET-1 vasoconstriction. Our results implicate ET-1 as a potential mediator of FFA-induced vascular insulin resistance.

Antiatherosclerotic and anti-insulin resistance effects of adiponectin: basic and clinical studies

Adiponectin is a protein secreted by adipose cells that may couple regulation of insulin sensitivity with energy metabolism and serve to link obesity with insulin resistance. Obesity-related disorders characterized by insulin resistance including the metabolic syndrome, diabetes, atherosclerosis, hypertension, and coronary artery disease are associated with both decreased adiponectin levels and endothelial dysfunction. Recent studies demonstrate that adiponectin has insulin-sensitizing effects as well as antiatherogenic properties. Lifestyle modifications and some drug therapies to treat atherosclerosis, hypertension, diabetes, and coronary heart disease have important effects in increasing adiponectin levels, decreasing insulin resistance, and improving endothelial dysfunction. In this review, we discuss insights into the relationships between adiponectin levels, insulin resistance, and endothelial dysfunction that are derived from various therapeutic interventions. The effects of lifestyle modifications and cardiovascular drugs on adiponectin levels and insulin resistance suggest plausible mechanisms that may be important for understanding and treating atherosclerosis and coronary heart disease.

Combination therapy for treatment or prevention of atherosclerosis: focus on the lipid-RAAS interaction

Large clinical trials demonstrate that control of blood pressure or hyperlipidemia reduces risk for cardiovascular events by approximately 30%. Factors that may further reduce remaining risk are not definitively established. One potential target is atherosclerosis, a crucial feature in the pathogenesis of cardiovascular diseases whose development is determined by multiple mechanism including complex interactions between endothelial dysfunction and insulin resistance. Reciprocal relationships between endothelial dysfunction and insulin resistance as well as cross-talk between hyperlipidemia and the rennin-angiotensin-aldosterone system may contribute to development of atherosclerosis. Therefore, one appealing strategy for prevention or treatment of atherosclerosis may be to simultaneously address several risk factors with combination therapies that target multiple pathogenic mechanisms. Combination therapy with statins, peroxisome proliferators-activated receptor agonists, and rennin-angiotensin-aldosterone system blockers demonstrate additive beneficial effects on endothelial dysfunction and insulin resistance when compared with monotherapies in patients with cardiovascular risk factors. Additive beneficial effects of combined therapy are mediated by both distinct and interrelated mechanisms, consistent with both pre-clinical and clinical investigations. Thus, combination therapy may be an important concept in developing more effective strategies to treat and prevent atherosclerosis, coronary heart disease, and co-morbid metabolic disorders characterized by endothelial dysfunction and insulin resistance.

Cytochrome P450 metabolites of arachidonic acid play a role in the enhanced cardiac dysfunction in diabetic rats following ischaemic reperfusion injury

1 This study examined the contribution of cytochrome P450 metabolites of arachidonic acid in mediating ischaemia/reperfusion (I/R)-induced cardiac dysfunction in normal and diabetic rats. 2 We first compared the metabolism of arachidonic acid in microsomes prepared from the hearts of control rats and rats treated with streptozotocin (55 mg kg(-1)) to induce diabetes. The production of dihydroxyeicosatrienoic acids and epoxyeicosatrienoic acids (EETs) were similar in microsomes prepared from the hearts of control and diabetic rats, but the production of 20-hydroxyeicosatetraenoic acid (20-HETE) was two-fold higher in diabetic hearts than in control animals. 3 We then compared the change in left ventricular pressure (P(max)), left ventricular end-diastolic pressure, coronary flow and coronary vascular resistance in isolated perfused hearts obtained from control and diabetic animals after 40 min of global ischaemia (I) followed by 30 min of reperfusion (R). The decline in cardiac function was three- to five-fold greater in the hearts obtained from diabetic vs. control animals. 4 Pretreatment of the hearts with N-hydroxy-N'-(4-butyl-2-methyl-phenyl)-formamidine (HET0016, 1 microm), a selective inhibitor of the synthesis of 20-HETE, for 30 min before I/R resulted in significant improvement in the recovery of cardiac function in the hearts obtained from diabetic but not in control rats. Perfusion with an inhibitor of soluble epoxide hydrolase, 1-cyclohexyl-3-dodecyl urea (CDU), before I/R improved the recovery of cardiac function in hearts obtained from both control and diabetic animals. Perfusion with both HET0016 and CDU resulted in significantly better recovery of cardiac function of diabetic hearts following I/R than that seen using either drug alone. Pretreatment of the hearts with glibenclamide (1 microm), an inhibitor of ATP-sensitive potassium channels, attenuated the cardioprotective effects of both CDU and HET0016. 5 This is the first study to suggest that acute blockade of the formation of 20-HETE and/or reduced inactivation of EETs could be an important strategy to reduce cardiac dysfunction following I/R events in diabetes.

Differential metabolic effects of pravastatin and simvastatin in hypercholesterolemic patients

BACKGROUND

Lipophilic and hydrophilic statins have different effects on adiponectin and insulin resistance in experimental studies and different effects on the rate of onset of new diabetes in large scale clinical studies. Therefore, we hypothesized that simvastatin and pravastatin may have differential metabolic effects in hypercholesterolemic patients.

METHODS

This was a randomized, single-blind, placebo-controlled, parallel study. Age, gender, and body mass index were matched. Forty-three patients were given placebo, simvastatin 20mg, or pravastatin 40 mg, respectively once daily for 2 months.

RESULTS

Simvastatin and pravastatin therapy significantly changed lipoprotein levels and improved flow-mediated dilation after 2 months when compared with baseline (P<0.001) or placebo treatment (P<0.001 by ANOVA). Simvastatin therapy significantly increased insulin levels (mean % changes; 127%, P=0.014) and decreased plasma adiponectin levels (10%, P=0.012) and insulin sensitivity as assessed by QUICKI (6%, P=0.007) when compared with baseline. By contrast, pravastatin therapy did not significantly change insulin levels (-3%, P=0.437) but significantly increased plasma adiponectin levels (9%, P=0.011) and insulin sensitivity (6%, P=0.008) when compared with baseline. In addition, these effects of simvastatin were significant when compared with pravastatin (P<0.001 for insulin levels by ANOVA on Ranks, P<0.001 for adiponectin and P=0.001 for QUICKI by ANOVA). When compared with baseline, simvastatin significantly increased plasma leptin levels (35%, P=0.028), but pravastatin did not (1%, P=0.822).

CONCLUSIONS

Despite causing comparable changes in lipoprotein and endothelium-dependent dilation, simvastatin and pravastatin therapy had differential metabolic effects in hypercholesterolemic patients that may be clinically relevant.

The effect of telmisartan on endothelial function and arterial stiffness in patients with essential hypertension

BACKGROUND AND OBJECTIVES

Several studies have shown that angiotensin II receptor blockers (ARBs) improve endothelial function and arterial stiffness. Telmisartan is a highly selective ARB that activates peroxisome proliferator-activated receptor gamma (PPARgamma). The purpose of this study was to evaluate the effects of telmisartan, such as endothelial function, arterial stiffness, and insulin sensitivity, in patients with essential hypertension.

SUBJECTS AND METHODS

Thirty-nine patients with essential hypertension were administered telmisartan (80 mg once daily) using an open-labeled and prospective protocol. The patients were examined before and 8 weeks after treatment to assess changes in flow mediated-vasodilation (FMD), pulse wave velocity (PWV), quantitative insulin-sensitivity check index (QUICKI), homeostasis model assessment (HOMA), and adiponection.

RESULTS

The systolic and diastolic blood pressure (BP) decreased from 153+/-15 mmHg and 90+/-13 mmHg to 137+/-16 mmHg and 84+/-10 mmHg after telmisartan treatment, respectively (p<0.01). Telmisartan therapy increased the FMD from 7.6+/-3.5 to 9.0+/-2.8% (p<0.01). The following parameters of arterial stiffness were significantly improved after telmisartan therapy: brachial-ankle pulse wave velocity (baPWV), from 17.2+/-3.1 to 15.9+/-2.6 m/sec; heart-carotid PWV (hcPWV), from 9.7+/-1.8 to 9.0+/-1.9 m/sec; and heart-femoral PWV (hfPWV), from 11.3+/-1.9 to 10.7+/-1.9 m/sec (p<0.01). There were no changes in QUICKI, the HOMA level, and plasma adiponectin (p=NS).

CONCLUSION

These results suggest that telmisartan is effective in improving endothelial function and arterial stiffness in patients with essential hypertension.

Chios Mastic Gum Extract and Isolated Phytosterol Tirucallol Exhibit Anti-Inflammatory Activity in Human Aortic Endothelial Cells

Chios mastic gum (CMG) is a white, semitransparent, natural resin that is obtained as a trunk exudate from mastic trees. Triterpenic compounds and phytosterols like tirucallol are among its major components. CMG has been associated with cardiovascular protection, exerting its effect mainly through increasing the antioxidant defense system, and effectively lowering the levels of serum cholesterol in human subjects. However, data on its anti-inflammatory effect on endothelium are scarce. Attachment of leukocytes to the vascular endothelium and the subsequent migration of cells into the vessel wall are early events in atherogenesis, and this process requires the expression of endothelial adhesion molecules. In this study, we examined the effect of CMG neutral extract (25–200 μ g/ml) and tirucallol (0.1–100 μ M) on the following: 1) the expression of adhesion molecules (VCAM-1 and ICAM-1) by Cell ELISA and 2) the attachment of monocytes (U937 cells) in TNF-α stimulated Human Aortic Endothelial Cells (HAEC) by Adhesion assay. The impact of treatment with CMG neutral extract and tirucallol in NFkB phosphorylation was also examined by a cell-based ELISA kit. Both CMG extract and tirucallol inhibit significantly VCAM-1 and ICAM-1 expression in TNF-α-stimulated HAEC. They also inhibit significantly the binding of U937 cells to TNF-α-stimulated HAEC and attenuate the phosphorylation of NFkB p65. This study extends existing data regarding the cardioprotective effect of CMG, expands the spectrum of known phytosterols with potent antiatheromatic activity, provides new insight into the mechanisms underlying the beneficial effect of CMG on endothelial function, and may aid in design of new therapy for intervention in atherosclerosis.

Does reversal of oxidative stress and inflammation provide vascular protection?

Chronic inflammation is a pathogenic feature of atherosclerosis and cardiovascular disease mediated by substances including angiotensin II, proinflammatory cytokines, and free fatty acids. This promotes generation of reactive oxygen species in vascular endothelial cells and smooth muscle cells, which mediate injury through several mechanisms. Reciprocal relationships between endothelial dysfunction and insulin resistance as well as cross-talk between hyperlipidaemia and the renin-angiotensin-aldosterone system (RAAS) at multiple levels contribute importantly to a variety of risk factors. Therefore, combination therapy that simultaneously addresses multiple mechanisms for the pathogenesis of atherosclerosis is an attractive emerging concept for slowing progression of atherosclerosis. Combined therapy with statins, peroxisome proliferator-activated receptors, and RAAS blockade demonstrates additive beneficial effects on endothelial dysfunction and insulin resistance when compared with monotherapies in patients with cardiovascular risk factors due to both distinct and interrelated mechanisms. These additive beneficial effects of combined therapies are consistent with laboratory and recent clinical studies. Thus, combination therapy may be an important paradigm for treating and slowing progression of atherosclerosis, coronary heart disease, and co-morbid metabolic disorders characterized by endothelial dysfunction and insulin resistance.

Distinct vascular and metabolic effects of different classes of anti-hypertensive drugs

BACKGROUND

ASCOT-BPLA study demonstrates that in hypertensive subjects, atenolol+bendroflumethiazide therapy is associated with higher incidence of adverse cardiovascular outcomes and developing diabetes than an amlodipine+perindopril regimen. This is not explained by changes in blood pressure alone. We hypothesized that distinct vascular and metabolic effects of anti-hypertensive drugs may explain these differential effects.

METHODS

Either placebo or one class of anti-hypertensive drug (atenolol 100 mg, amlodipine 10 mg, hydrochlorothiazide 50 mg, ramipril 10 mg, or candesartan 16 mg) was given daily during 8 weeks to 31 patients in each of 6 arms of a randomized, single-blind, placebo-controlled, parallel study.

RESULTS

Atenolol, amlodipine, and candesartan therapies significantly reduced systolic blood pressure when compared with ramipril (P<0.05 by ANOVA). Atenolol and thiazide therapies increased triglycerides levels greater than ramipril or candesartan (P=0.005 by ANOVA). Amlodipine significantly increased HDL cholesterol levels greater than atenolol (P=0.011 by ANOVA). Ramipril and candesartan therapies improved FMD and increased adiponectin levels and insulin sensitivity to a greater extent than atenolol or thiazide therapies (P<0.001 and P<0.015 by ANOVA). Amlodipine therapy increased adiponectin levels greater than atenolol therapy (P<0.05 by ANOVA). Ramipril, candesartan, and amlodipine therapies significantly decreased leptin levels to a greater extent when compared with atenolol or thiazide therapies (P<0.001 by ANOVA). Amlodipine therapies significantly decreased resistin levels greater than ramipril or candesartan therapies (P=0.001 by ANOVA).

CONCLUSIONS

We observed differential effects of anti-hypertensive drugs on endothelial dysfunction and plasma adipocytokines.