Impact of postprandial hypertriglyceridemia on vascular responses in patients with coronary artery disease: effects of ACE inhibitors and fibrates

A single, high-fat meal adversely affects postprandial endothelial function: a systematic review and meta-analysis

BACKGROUND

Endothelial dysfunction is a predictive risk factor for the development of atherosclerosis and is assessed by flow-mediated dilation (FMD). Although it is known that NO-dependent endothelial dysfunction occurs after consuming a high-fat meal, the magnitude of the effect and the factors that affect the response are unquantified.

OBJECTIVES

We conducted a systematic review and meta-analysis exploring the quantitative effects of a single high-fat meal on endothelial function and determined the factors that modify the FMD response.

METHODS

Six databases were systematically searched for original research published up to January 2022. Eligible studies measured fasting and postprandial FMD following consumption of a high-fat meal. Meta-regression was used to analyze the effect of moderator variables.

RESULTS

There were 131 studies included, of which 90 were suitable for quantitative meta-analysis. A high-fat meal challenge transiently caused endothelial dysfunction, decreasing postprandial FMD at 2 hours [-1.02 percentage points (pp); 95% CI: -1.34 to -0.70 pp; P < 0.01; I2 = 93.3%], 3 hours [-1.04 pp; 95% CI: -1.48 to -0.59 pp; P < 0.001; I2 = 84.5%], and 4 hours [-1.19 pp; 95% CI: -1.53 to -0.84 pp; P < 0.01; I2 = 94.6%]. Younger, healthy-weight participants exhibited a greater postprandial reduction in the FMD percentage change than older, heavier, at-risk groups after a high-fat meal ( P < 0.05). The percentage of fat in the meals was inversely associated with the magnitude of postprandial changes in FMD at 3 hours (P < 0.01).

CONCLUSIONS

A single, high-fat meal adversely impacts endothelial function, with the magnitude of the impact on postprandial FMD moderated by the fasting FMD, participant age, BMI, and fat content of the meal. Recommendations are made to standardize the design of future postprandial FMD studies and optimize interpretation of results, as high-fat meals are commonly used in clinical studies as a challenge to assess endothelial function and therapeutics. This trial was registered at PROSPERO as CRD42020187244.

Abrogation of postprandial triglyceridemia with dual PPAR α/γ agonist in type 2 diabetes mellitus: a randomized, placebo-controlled study

AIMS

Lowering postprandial lipemia may mitigate cardiovascular risk in patients with diabetic dyslipidemia. This study was aimed to investigate whether saroglitazar suppresses postprandial lipemia in patients with diabetes and dyslipidemia.

METHODS

This was a 12-week, prospective, multicenter, randomized, double-blinded, placebo-controlled study of saroglitazar in patients with diabetes and dyslipidemia. Thirty patients were randomized (1:1) to receive saroglitazar 4 mg or placebo orally once daily with metformin for 12 weeks. The primary endpoint was change in plasma triglyceride (TG) area under the curve (AUC) on a standardized 8-h fat tolerance test.

RESULTS

Thirty participants were randomized for interventions and eventually data of 19 participants qualified for per protocol analyses. Mean (SD) age in saroglitazar was 53.1 (8.8) years and 54.9 (7.7) years in placebo group. After 12 weeks, saroglitazar significantly lowered postprandial TG-AUC by - 458.3 (144.0) (- 25.7%, 95% CI - 765.1 to - 151.4) versus an increase of + 10.9 (157.9) (+ 0.5%, 95% CI - 325.6 to 347.3) mg/dL h in placebo group (P < 0.05). Saroglitazar lowered postprandial TG incremental AUC versus placebo: - 329.4 (89.9) (- 59%) versus + 80.4 (99.4) (+ 10%) mg/dL h (P < 0.05). HbA1c (%) decreased by - 0.36 (0.42) in the saroglitazar group as compared to an increase of + 1.26 (0.46) (P < 0.05) with placebo.

CONCLUSIONS

The saroglitazar treatment significantly improved postprandial TGs in people with diabetic dyslipidemia.

TRIAL REGISTRATION

Clinical Trial Registry of India; trial Registration No.: CTRI/2015/06/005845 and Date of registration: June 02, 2015.

Pravastatin improves postprandial endothelial dysfunction and hemorheological deterioration in patients with effort angina pectoris

Postprandial hypertriglyceridemia and hyperglycemia may promote endothelial and hemorheological dysfunction. The present study investigated the effects of pravastatin on endothelial function and hemorheology in patients with stable angina pectoris (AP) before and after eating a test meal. We recruited 26 patients with stable AP who had impaired glucose tolerance and mild dyslipidemia and six healthy men as controls to assess endothelial function and hemorheological behavior. In each group, we measured forearm blood flow (FBF) during post-ischemic reactive hyperemia and obtained blood samples before and 2 h after the test meal. Pravastatin 20 mg/day was then commenced in the 26 AP patients. The above tests were repeated after 2 days and 6 months. Maximum FBF during hyperemia in the baseline fasting phase was significantly lower in the AP patients than in the controls (p < 0.05). Fasting and postprandial FBF during reactive hyperemia time-dependently improved after pravastatin treatment (p < 0.05 vs. baseline data for each phase). Pravastatin treatment for 6 months, but not for 2 days, inhibited leukocyte activation and improved hemorheological parameters. In conclusion, pravastatin treatment for 6 months improved fasting and postprandial endothelial and hemorheological dysfunction in AP patients.

Eating and arterial endothelial function: a meta-analysis of the acute effects of meal consumption on flow-mediated dilation

Given that endothelial dysfunction precedes atherosclerotic cardiovascular disease, exploring the parameters that modify postprandial flow-mediated dilation (FMD) is important for public health. The objectives of the study are to estimate the population effect of meal ingestion on FMD and to determine how the effect varied based on patient characteristics and modifiable methodological features. Articles published before June 2015 were located using MEDLINE, PubMed and Web of Science. One hundred fifty-four effects were derived from 78 articles involving 2,548 subjects were selected. Included articles required measurement of FMD in adults before and after meal ingestion. Effects were analysed using an unstandardized mean gain random effects model, and significant moderators were analysed using meta-regression. Meal consumption significantly reduced FMD by a heterogeneous mean effect size delta (Δ) of -2.03 (95% CI: [-2.28, -1.77]), an ~2% reduction in FMD. FMD reductions were larger among normal weight individuals, males, those with a cardio-metabolic disorder, those with elevated baseline FMD, and individuals with impaired glucose tolerance at baseline. Macronutrient meal ingestion significantly reduced FMD, an effect that was moderated by body mass index, sex and two-way interactions between disease status and both baseline FMD and baseline blood glucose levels.

Acute Thermotherapy Prevents Impairments in Cutaneous Microvascular Function Induced by a High Fat Meal

We tested the hypothesis that a high fat meal (HFM) would impair cutaneous vasodilation, while thermotherapy (TT) would reverse the detrimental effects. Eight participants were instrumented with skin heaters and laser-Doppler (LD) probes and tested in three trials: control, HFM, and HFM + TT. Participants wore a water-perfused suit perfused with 33°C (control and HFM) or 50°C (HFM + TT) water. Participants consumed 1 g fat/kg body weight. Blood samples were taken at baseline and two hours post-HFM. Blood pressure was measured every 5-10 minutes. Microvascular function was assessed via skin local heating from 33°C to 39°C two hours after HFM. Cutaneous vascular conductance (CVC) was calculated and normalized to maximal vasodilation (%CVCmax). HFM had no effect on initial peak (48 ± 4 %CVCmax) compared to control (49 ± 4 %CVCmax) but attenuated the plateau (51 ± 4 %CVCmax) compared to control (63 ± 4 %CVCmax, P < 0.001). Initial peak was augmented in HFM + TT (66 ± 4 %CVCmax) compared to control and HFM (P < 0.05), while plateau (73 ± 3 % CVCmax) was augmented only compared to the HFM trial (P < 0.001). These data suggest that HFM negatively affects cutaneous vasodilation but can be minimized by TT.

Relationship between the Peroxidation of Leukocytes Index Ratio and the Improvement of Postprandial Metabolic Stress by a Functional Food

For the first time, we investigated the relationship between postprandial dysmetabolism and the Peroxidation of Leukocytes Index Ratio (PLIR), a test that measures the resistance of leukocytes to exogenous oxidative stress and their functional capacity of oxidative burst upon activation. Following a blind, placebo controlled, randomized, crossover design, ten healthy subjects ingested, in two different occasions, a high fat and high carbohydrates meal with Snello cookie (HFHCM-S) or with control cookies (HFHCM-C). Snello cookie, a functional food covered by dark chocolate and containing glucomannan, inulin, fructooligosaccharides, and Bacillus coagulans strain GanedenBC30, significantly improved postprandial metabolic stress (insulin, glucose, and triglycerides) and reduced the postprandial increase of uric acid. HFHCM-S improved PLIR of lymphocytes, but not of monocytes and granulocytes. Both meals increased granulocytes' count and reduced the lipoperoxidation induced by both exogenous free radicals and reactive oxygen species (ROS) produced by oxidative burst. Our results suggest that the healthy status of the subjects could be a limitation of this pilot study for PLIR evaluation on cells that produce ROS by oxidative burst. In conclusion, the relationship between PLIR and postprandial dysmetabolism requires further investigations.

Exenatide Protects Against Glucose- and Lipid-Induced Endothelial Dysfunction: Evidence for Direct Vasodilation Effect of GLP-1 Receptor Agonists in Humans

GLP-1 receptor (GLP-1R) agonists may improve endothelial function (EF) via metabolic improvement and direct vascular action. The current study determined the effect of GLP-1R agonist exenatide on postprandial EF in type 2 diabetes and the mechanisms underlying GLP-1R agonist-mediated vasodilation. Two crossover studies were conducted: 36 participants with type 2 diabetes received subcutaneous exenatide or placebo for 11 days and EF, and glucose and lipid responses to breakfast and lunch were determined; and 32 participants with impaired glucose tolerance (IGT) or diet-controlled type 2 diabetes had EF measured before and after intravenous exenatide, with or without the GLP-1R antagonist exendin-9. Mechanisms of GLP-1R agonist action were studied ex vivo on human subcutaneous adipose tissue arterioles and endothelial cells. Subcutaneous exenatide increased postprandial EF independent of reductions in plasma glucose and triglycerides. Intravenous exenatide increased fasting EF, and exendin-9 abolished this effect. Exenatide elicited eNOS activation and NO production in endothelial cells, and induced dose-dependent vasorelaxation and reduced high-glucose or lipid-induced endothelial dysfunction in arterioles ex vivo. These effects were reduced with AMPK inhibition. In conclusion, exenatide augmented postprandial EF in subjects with diabetes and prevented high-glucose and lipid-induced endothelial dysfunction in human arterioles. These effects were largely direct, via GLP-1R and AMPK activation.

Effects of culinary spices and psychological stress on postprandial lipemia and lipase activity: results of a randomized crossover study and in vitro experiments

BACKGROUND

Data suggest that culinary spices are a potent, low-calorie modality for improving physiological responses to high fat meals. In a pilot study (N = 6 healthy adults), we showed that a meal containing a high antioxidant spice blend attenuated postprandial lipemia by 30% compared to a low spice meal. Our goal was to confirm this effect in a larger sample and to consider the influence of acute psychological stress on fat metabolism. Further, we used in vitro methods to evaluate the inhibitory effect of spices on digestive enzymes.

METHODS

In a 2 x 2, randomized, 4-period crossover design, we compared the effects of 14.5 g spices (black pepper, cinnamon, cloves, garlic, ginger, oregano, paprika, rosemary, and turmeric) vs. placebo incorporated into a high fat meal (1000 kcal, 45 g fat), followed by psychological stress (Trier Social Stress Test) vs. rest on postprandial metabolism in 20 healthy but overweight adults. Blood was sampled at baseline and at 105, 140, 180, and 210 minutes for analysis of triglycerides, glucose, and insulin. Additional in vitro analyses examined the effect of the spice blend and constituent spices on the activity of pancreatic lipase (PL) and secreted phospholipase A₂ (PLA₂). Mixed models were used to model the effects of spices and stress (SAS v9.3).

RESULTS

Serum triglycerides, glucose and insulin were elevated following the meal (p < 0.01). Spices reduced post-meal triglycerides by 31% when the meal was followed by the rest condition (p = 0.048), but this effect was not present during stress. There was no effect of the spice blend on glucose or insulin; however, acute stress significantly increased both of these measures (p < 0.01; mean increase of 47% and 19%, respectively). The spice blend and several of the individual spices dose-dependently inhibited PL and PLA2 activity in vitro.

CONCLUSIONS

Inclusion of spices may attenuate postprandial lipemia via inhibition of PL and PLA₂. However, the impact of psychological stress negates any influence of the spice blend on triglycerides, and further, increases blood glucose and insulin.

TRIAL REGISTRATION

ClinicalTrials.gov as NCT00954902 .

Risks of misinterpretation in the evaluation of the effect of fruit-based drinks in postprandial studies

It has been suggested that some fruit-based drinks (FBD) may delay the onset of postprandial stress, which is involved in the pathogenesis of many diseases. The majority of the studies, which have investigated the effects of FBD on postprandial stress, involved a placebo that was a drink with the same content in sugars or carbohydrates of the FBD, but without the bioactive antioxidant compounds. These studies were aimed more at evaluating the effect of the antioxidants rather than the effect of the FBD as a whole. Only 4 studies compared the effect of FBD with water as control and did not support the hypothesis that FBD could inhibit postprandial dysmetabolism, as well as the studies that compared the effect of orange juice and cola. Overall, the results suggest a complex relationship between postprandial dysmetabolism, inflammation, and oxidative stress. Furthermore, the inflammatory and oxidative stress markers need further analytical validation and normal ranges should be established in order to reach a firm conclusion. Finally, caution should be taken in the interpretation of the effect of FBD in postprandial studies and the reviewed results suggest that dietary recommendations should aim to limit rather than increase sugar-sweetened beverages consumption.

Impact of vitamin D supplementation on arterial vasomotion, stiffness and endothelial biomarkers in chronic kidney disease patients

Background

Cardiovascular events are frequent and vascular endothelial function is abnormal in patients with chronic kidney disease (CKD). We demonstrated endothelial dysfunction with vitamin D deficiency in CKD patients; however the impact of cholecalciferol supplementation on vascular stiffness and vasomotor function, endothelial and bone biomarkers in CKD patients with low 25-hydroxy vitamin D [25(OH)D] is unknown, which this study investigated.

Methods

We assessed non-diabetic patients with CKD stage 3/4, age 17–80 years and serum 25(OH)D <75 nmol/L. Brachial artery Flow Mediated Dilation (FMD), Pulse Wave Velocity (PWV), Augmentation Index (AI) and circulating blood biomarkers were evaluated at baseline and at 16 weeks. Oral 300,000 units cholecalciferol was administered at baseline and 8-weeks.

Results

Clinical characteristics of 26 patients were: age 50±14 (mean±1SD) years, eGFR 41±11 ml/min/1.73 m², males 73%, dyslipidaemia 36%, smokers 23% and hypertensives 87%.

At 16-week serum 25(OH)D and calcium increased (43±16 to 84±29 nmol/L, p<0.001 and 2.37±0.09 to 2.42±0.09 mmol/L; p = 0.004, respectively) and parathyroid hormone decreased (10.8±8.6 to 7.4±4.4; p = 0.001). FMD improved from 3.1±3.3% to 6.1±3.7%, p = 0.001.

Endothelial biomarker concentrations decreased: E-Selectin from 5666±2123 to 5256±2058 pg/mL; p = 0.032, ICAM-1, 3.45±0.01 to 3.10±1.04 ng/mL; p = 0.038 and VCAM-1, 54±33 to 42±33 ng/mL; p = 0.006. eGFR, BP, PWV, AI, hsCRP, von Willebrand factor and Fibroblast Growth Factor-23, remained unchanged.

Conclusion

This study demonstrates for the first time improvement of endothelial vasomotor and secretory functions with vitamin D in CKD patients without significant adverse effects on arterial stiffness, serum calcium or FGF-23.

Trial Registration

ClinicalTrials.gov NCT02005718

Postprandial lipaemia suppresses endothelium-dependent arterial dilation in patients with hypothyroidism

Endothelial dysfunction represents an early step in the development of atherosclerosis. The purpose of this study was to investigate the relationship between postprandial lipaemia and endothelial dysfunction in patients with overt hypothyroidism (oHT) and subclinical hypothyroidism (sHT). Female subjects with oHT and sHT, as well as female healthy subjects with euthyroid state were enrolled (10 cases in each group). The examination of flow-mediated dilation (FMD) was performed before and after an oral fat-loading by high resolution ultrasound. Endothelial dysfunction after an oral fat challenge was related to the extent of hypertriglyceridemia and free radicals. FMD decreased significantly at 4-h point in 3 groups, (p < 0.05) and then FMD in control and sHT restored to baseline at 8-h point, it was lower than baseline in sHT group at 6-h point (p = 0.042). However, FMD continued to decrease at 6-h point (p < 0.001), and then increased toward to baseline at 8-h point, which was still lower than baseline (p = 0.039) in oHT. Spearman's analysis showed a negative correlation between FMD and triglyceride, a negative correlation between FMD and thiobarbituric acid reactive substances (TBARS), and a positive correlation between triglyceride and TBARS levels during oral lipid-loading test in hypothyroid patients (p < 0.001) and controls (p < 0.05). In hypothyroid subjects including oHT and sHT, even in healthy individuals, FMD was impaired after an oral fat challenge. The endothelial dysfunction observed after an oral fat challenge was related to the extent of hypertriglyceridemia and oxygen-derived free radicals.

Postprandial hyperlipidemia, endothelial dysfunction and cardiovascular risk: focus on incretins

Cardiovascular disease (CVD) risk in type 2 diabetes (T2DM) is only partially reduced by intensive glycemic control. Diabetic dyslipidemia is suggested to be an additional important contributor to CVD risk in T2DM. Multiple lipid lowering medications effectively reduce fasting LDL cholesterol and triglycerides concentrations and several of them routinely reduce CVD risk. However, in contemporary Western societies the vasculature is commonly exposed to prolonged postprandial hyperlipidemia. Metabolism of these postprandial carbohydrates and lipids yields multiple proatherogenic products. Even a transient increase in these factors may worsen vascular function and induces impaired endothelial dependent vasodilatation, a predictor of atherosclerosis and future cardiovascular events. There is a recent increased appreciation for the role of gut-derived incretin hormones in controlling the postprandial metabolic milieu. Incretin-based medications have been developed and are now used to control postprandial hyperglycemia in T2DM. Recent data indicate that these medications may also have profound effects on postprandial lipid metabolism and may favorably influence several cardiovascular functions. This review discusses (1) the postprandial state with special emphasis on postprandial lipid metabolism and its role in endothelial dysfunction and cardiovascular risk, (2) the ability of incretins to modulate postprandial hyperlipidemia and (3) the potential of incretin-based therapeutic strategies to improve vascular function and reduce CVD risk.

Hypolipidemic effect of Pleurotus eryngii extract in fat-loaded mice

Pleurotus eryngii water extract (PEE), which showed the most significant inhibitory activity against pancreatic lipase in vitro among eight edible mushrooms, was investigated to determine the mechanism of its anti-lipase activity in vitro and its hypolipidemic effect in fat-loaded mice. The inhibitory effects of mushroom extracts on pancreatic lipase activity were examined using 4-methylumbelliferyl oleate (4-MUO) or trioleoylglycerol emulsified with lecithin, gum arabic or Triton X-100 as a substrate. For in vivo experiments, blood samples were taken after oral administration of corn oil and [(3)H]trioleoylglycerol with or without PEE to food-deprived mice. PEE inhibited hydrolysis of 4-MUO and trioleoylglycerol emulsified with lecithin or Triton X-100, but not that of trioleoylglycerol emulsified with gum arabic. PEE suppressed the elevations of plasma and chylomicron triacylglycerol levels after oral administration of corn oil, but had no effect on lipoprotein lipase activity. [(3)H]Trioleoylglycerol absorption was also decreased by administration of PEE. The results of in vitro studies suggest that PEE may prevent interactions between lipid emulsions and pancreatic lipase. The hypolipidemic effect of PEE in fat-loaded mice may be due to low absorption of fat caused by the inhibition of pancreatic lipase.

Postprandial vascular reactivity in obese and normal weight young adults

As humans spend a significant amount of time in the postprandial state, we examined whether vascular reactivity (a key indicator of cardiovascular health) was different after a high-fat meal in 11 obese (median BMI 46.4, age 32.1 +/- 6.3 years, 7 men) and 11 normal weight (median BMI 22.6) age- and sex-matched controls. At baseline and 1 and 3 h postmeal, blood pressure (BP), heart rate (HR), reactive hyperemia peripheral artery tonometry (RH-PAT) index, radial augmentation index adjusted for HR (AIx75), brachial pulse wave velocity (PWV(b)), glucose, insulin, total and high-density lipoprotein (HDL) cholesterol, and triglycerides were measured. Brachial flow-mediated dilatation (FMD) and, by venous plethysmography, resting and hyperemic forearm blood flows (FBFs) were measured at baseline and 3 h. At baseline, obese subjects had higher systolic BP, HR, resting FBF, insulin and equivalent FMD, RH-PAT, hyperemic FBF, AIx75, PWV(b), glucose, total cholesterol, triglycerides, and lower HDL cholesterol. In obese and lean subjects, FMD at baseline and 3 h was not significantly different (6.2 +/- 1.7 to 5.8 +/- 4.3% for obese and 4.7 +/- 4.1 to 4.3 +/- 3.9% for normal weight, P = 0.975 for group x time). The meal did not produce significant changes in RH-PAT, hyperemic FBF, and PWV(b) in either group (P > 0.1 for the effect of time and for group x time interactions). In conclusion, the vascular responses to a high-fat meal are similar in obese and normal weight young adults. An exaggerated alteration in postprandial vascular reactivity is thus unlikely to contribute importantly to the increased cardiovascular risk of obesity.

Triglyceride-rich lipoprotein lipolysis releases neutral and oxidized FFAs that induce endothelial cell inflammation

Triglyceride-rich lipoprotein (TGRL) lipolysis products provide a pro-inflammatory stimulus that can alter endothelial barrier function. To probe the mechanism of this lipolysis-induced event, we evaluated the pro-inflammatory potential of lipid classes derived from human postprandial TGRL by lipoprotein lipase (LpL). Incubation of TGRL with LpL for 30 min increased the saturated and unsaturated FFA content of the incubation solutions significantly. Furthermore, concentrations of the hydroxylated linoleates 9-hydroxy ocatadecadienoic acid (9-HODE) and 13-HODE were elevated by LpL lipolysis, more than other measured oxylipids. The FFA fractions elicited pro-inflammatory responses inducing TNFalpha and intracellular adhesion molecule expression and reactive oxygen species (ROS) production in human aortic endothelial cells (HAECs). The FFA-mediated increase in ROS was blocked by both the cytochrome P450 2C9 inhibitor sulfaphenazole and NADPH oxidase inhibitors. Compared with linoleate, 13-HODE was found to be a more potent inducer of ROS production in HAECs, an activity that was insensitive to both NADPH oxidase and cytochrome P450 inhibitors. Therefore, although the oxidative metabolism of FFA in endothelial cells can produce inflammatory responses, TGRL lipolysis can also release preformed mediators of oxidative stress (e.g., HODEs) that may influence endothelial cell function in vivo by stimulating intracellular ROS production.

ACE inhibition and endothelial function: main findings of PERFECT, a sub-study of the EUROPA trial

Background

ACE inhibition results in secondary prevention of coronary artery disease (CAD) through different mechanisms including improvement of endothelial dysfunction. The Perindopril-Function of the Endothelium in Coronary artery disease Trial (PERFECT) evaluated whether long-term administration of perindopril improves endothelial dysfunction.

Methods

PERFECT is a 3-year double blind randomised placebo controlled trial to determine the effect of perindopril 8 mg once daily on brachial artery endothelial function in patients with stable CAD without clinical heart failure. Endothelial function in response to ischaemia was assessed using ultrasound. Primary endpoint was difference in flow-mediated vasodilatation (FMD) assessed at 36 months.

Results

In 20 centers, 333 patients randomly received perindopril or matching placebo. Ischemia-induced FMD was 2.7% (SD 2.6). In the perindopril group FMD went from 2.6% at baseline to 3.3% at 36 months and in the placebo group from 2.8 to 3.0%. Change in FMD after 36 month treatment was 0.55% (95% confidence interval −0.36, 1.47; p = 0.23) higher in perindopril than in placebo group. The rate of change in FMD per 6 months was 0.14% (SE 0.05, p = 0.02) in perindopril and 0.02% (SE 0.05, p = 0.74) in placebo group (0.12% difference in rate of change p = 0.07).

Conclusion

Perindopril resulted in a modest, albeit not statistically significant, improvement in FMD.

Endothelial function, arterial stiffness and lipid lowering drugs

The endothelium is a dynamic organ that plays a pivotal role in cardiovascular homeostasis. Alteration in endothelial function precedes the development of atherosclerosis and contributes to its initiation, perpetuation and clinical manifestations. It has been suggested that the assessment of endothelial function could represent a barometer of vascular health that could be used to gauge cardiovascular risk. This review summarises the various methods used to assess endothelium-dependent vasodilatation and their potential prognostic implications. In addition, the techniques used to evaluate arterial stiffness are discussed. The latter is to some extent controlled by the endothelium and has been the subject of considerable research in recent years. This paper also discusses the effects of lipid lowering treatment on both endothelial function and arterial stiffness.

Fenofibrate therapy ameliorates fasting and postprandial lipoproteinemia, oxidative stress, and the inflammatory response in subjects with hypertriglyceridemia and the metabolic syndrome

OBJECTIVE

The aim of this study was to determine the effects of fenofibrate (160 mg/day) on fasting and postprandial lipoproteins, oxidized fatty acids, and inflammatory mediators in subjects with hypertriglyceridemia and the metabolic syndrome.

RESEARCH DESIGN AND METHODS

Fifty-nine subjects with fasting hypertriglyceridemia (> or = 1.7 and < 6.9 mmol/l) and two or more of the Adult Treatment Panel III criteria for the metabolic syndrome were randomly assigned to fenofibrate (160 mg/day) or placebo in a double-blind, controlled clinical trial.

RESULTS

Fenofibrate treatment lowered fasting triglycerides (-46.1%, P < 0.0001) and postprandial (area under the curve) triglycerides (-45.4%, P < 0.0001) due to significant reductions in postprandial levels of large (-40.8%, P < 0.0001) and medium (-49.5%, P < 0.0001) VLDL particles. The number of fasting total LDL particles was reduced in fenofibrate-treated subjects (-19.0%, P = 0.0033) primarily due to reductions in small LDL particles (-40.3%, P < 0.0001); these treatment differences persisted postprandially. Fasting and postprandial oxidized fatty acids were reduced in fenofibrate-treated subjects compared with placebo-administered subjects (-15.3%, P = 0.0013, and 31.0%, P < 0.0001, respectively), and fenofibrate therapy lowered fasting and postprandial soluble vascular cell adhesion molecule-1 (VCAM-1) (-10.9%, P = 0.0005, and -12.0%, P = 0.0001, respectively) as well as fasting and postprandial soluble intercellular adhesion molecule-1 (ICAM-1) (-14.8%, P < 0.0001, and -15.3%, P < 0.0001, respectively). Reductions in VCAM-1 and ICAM-1 were correlated with reductions in fasting and postprandial large VLDL particles (P < 0.0001) as well as postprandial oxidized fatty acids (P < 0.0005).

CONCLUSIONS

Triglyceride-lowering therapy with fenofibrate reduced fasting and postprandial free fatty acid oxidation and inflammatory responses, and these antiatherosclerotic effects were most highly correlated with reductions in large VLDL particles.

Microvascular endothelial function in subjects with Type 2 diabetes and the effect of lipid-lowering therapy

AIMS

Abnormalities of microvascular and endothelial function are present in subjects with Type 2 diabetes. Although statin therapy improves cardiovascular risk in diabetes, dyslipidaemia in diabetes may be more responsive to combined statin and fibrate therapy. We examined the effect of cerivastatin and fenofibrate on microvascular function in subjects with Type 2 diabetes with no clinical evidence of cardiovascular disease and near normal lipid levels.

METHODS

Age-, sex-, lipid- and blood pressure-matched subjects with Type 2 diabetes were randomized in double-blind fashion to one of four treatment groups: group 1 placebo/placebo (n=12), group 2 fenofibrate/placebo (n=10), group 3 cerivastatin/placebo (n=20) and group 4 cerivastatin/fenofibrate (n=11). The subjects were recruited from the Lipid in Diabetes Study. Microvascular function was assessed by skin blood flow response to iontophoresis of acetylcholine and sodium nitroprusside and by skin maximum hyperaemia to local heating. Measurements were carried out at baseline and 3 months later.

RESULTS

Although all lipid parameters improved in groups 2-4 after 3 months' therapy, no difference was detected in skin blood flow to iontophoresis or maximum hyperaemia in any of the groups. Highly sensitive c-reactive protein (Hs-CRP) did not change with therapy.

CONCLUSIONS

In conclusion, we were unable to demonstrate any improvement in microvascular endothelial function in non-hyperlipidaemic Type 2 diabetic subjects treated with single or combination lipid-lowering therapy.

Clinical impact of vasomotor function assessment and the role of ACE-inhibitors and statins

Impaired endothelial function is recognised as one of the earliest events of atherogenesis. Endothelium-dependent vasomotion has been the principal method to assess endothelial function. In this article, we will discuss the clinical value of the different techniques to evaluate endothelium-dependent vasomotion. To date, there seems not to be a simple and reliably endothelial function test to identify asymptomatic subjects at increased risk for cardiovascular disease in clinical practice. Recent studies indicate that pharmacological interventions, in particular with ACE-inhibitors and statins, might improve endothelial function. However, there is no solid evidence that improvement of endothelial function is a necessity for the observed reduction in cardiovascular events by these compounds. Overall, at this moment, there is no place in clinical practice for the use of endothelial function as a method for risk assessment or target of pharmacological interventions.

Postprandial dysmetabolism and cardiovascular disease in type 2 diabetes

The worldwide prevalence of type 2 diabetes mellitus has reached epidemic proportions. The so-called traditional risk factors cannot fully explain the excessive cardiovascular disease risk of type 2 diabetic patients. Numerous studies indicate that postprandial metabolic derangements, most notably hyperglycaemia and hypertriglyceridaemia, which are exaggerated and prolonged in type 2 diabetes, are important cardiovascular disease risk factors since they induce oxidative stress and endothelial dysfunctions. This review discusses the current evidence showing that postprandial dysmetabolism may indeed constitute an important cardiovascular disease risk factor as well as the mechanisms underlying this association. Finally, some possible therapeutic options and recommendations for future research are discussed.

Endothelial function and dysfunction. Part II: Association with cardiovascular risk factors and diseases. A statement by the Working Group on Endothelins and Endothelial Factors of the European Society of Hypertension*

Dysfunction of the vascular endothelium is a hallmark of most conditions that are associated with atherosclerosis and is therefore held to be an early feature in atherogenesis. However, the mechanisms by which endothelial dysfunction occurs in smoking, dyslipidaemia, hyperhomocysteinaemia, diabetes mellitus, arterial hypertension, cerebrovascular diseases, coronary artery disease and heart failure are complex and heterogeneous. Recent data indicate that endothelial dysfunction is often associated with erectile dysfunction, which can precede and predict cardiovascular disease in men. This paper will provide a concise overview of the mechanisms causing endothelial dysfunction in the different cardiovascular risk factors and disease conditions, and of the impact of the intervention measures and treatments.

Fenofibrate lowers adiposity and corrects metabolic abnormalities, but only partially restores endothelial function in dietary obese rats

In humans, dietary-induced obesity markedly increases plasma lipid profile and impairs vascular function leading to increased incidence of cardiovascular events. We have recently reported that chronic withdrawal of obesity-inducing diet attenuates obesity and completely corrects endothelial function. The aim of this study was to investigate whether fenofibrate-induced decrease in adiposity would also correct vascular function in the presence of obesity-inducing diet. Wistar rats were fed with either standard laboratory chow (lean, n = 9) or given a highly palatable diet (diet-fed, n = 18) for 15 weeks. After 7 weeks, half of the diet-fed group was treated with fenofibrate (fenofibrate-treated, n = 9) for 8 weeks before being sacrificed. Untreated diet-fed (n = 9) rats had significantly higher body weight, total fat mass (by up to two-fold, p < 0.001 for both), and raised fasting plasma levels of insulin, leptin and triglycerides (up to 110%; p < 0.001), but not glucose or nonesterified fatty acids (NEFA) than both lean control and fenofibrate-treated groups. Resistance mesenteric arteries responses to KCl- and noradrenaline-induced vasoconstriction were similar in all three groups. However, compared with lean controls, endothelium-dependent vasorelaxation responses were shifted to the right in both untreated and fenofibrate-treated diet-fed groups. Fenofibrate treatment improved endothelium-dependent vasorelaxation at only high carbamycholine concentrations (10 microM). There were no differences in endothelium-independent vasorelaxation between the three groups. These results indicate that, in the presence of obesity-inducing diet, fenofibrate markedly reverses obesity and corrects insulin resistance and lipid profile, but it only has a limited beneficial effect on vascular function. Therefore, it seems that diet component rather than obesity per se plays a key role in the genesis of vascular abnormalities.

Assessment of flow-mediated vasodilatation (FMD) of the brachial artery: effects of technical aspects of the FMD measurement on the FMD response

AIMS

The ability to assess endothelial function non-invasively with B-mode ultrasound has lead to its widespread application in a variety of studies. However, the absolute values obtained using this approach vary considerably across studies. We studied whether technical aspects of the methodology can explain the wide variety in absolute values across studies.

METHODS AND RESULTS

A literature search was performed to identify published reports on flow-mediated vasodilatation (FMD) of the brachial artery published between 1992 and 2001. Information on type of equipment (wall track/B-mode), location of the measurement (antecubital fossa/upper arm), occlusion site (lower/upper arm), occlusion duration (min), and occlusion pressure was extracted. Patient characteristics were also extracted. For the healthy populations, mean FMD varied from 0.20 to 19.2%; for the coronary heart disease (CHD) patients FMD varied from -1.3 to 14%; for subjects with diabetes mellitus FMD varied from 0.75 to 12%. Compared with occlusion at the upper arm, lower arm occlusion was related to decreased FMD (mean difference in FMD -2.47%; 95% CI 0.55-4.39). An occlusion duration of > or =4.5 min was related to an increased FMD compared with an occlusion time of < or =4 min (mean difference 1.30%; 95% CI 0.35-2.46). These findings were adjusted for other technical aspects of the methodology and for differences in risk factors between populations.

CONCLUSION

Mean FMD differs widely between studies. There is a great overlap between populations (healthy, CHD, diabetics). Our findings suggest that the technical aspects of the measurements, the location, and the duration of the occlusion may explain some of these differences, whereas type of equipment, location of the measurement, and occlusion pressure do not.

Impact of left ventricular ejection fraction on endothelial function in patients with coronary artery disease

BACKGROUND

Endothelial dysfunction is present in patients with coronary artery disease (CAD) or with congestive heart failure.

HYPOTHESIS

This study was performed to evaluate the impact of systolic heart function on endothelial function in patients with CAD.

METHODS

The study population consisted of 283 consecutive patients (mean age 59 years, 176 men) undergoing coronary angiography. Endothelial function was assessed by measuring flow-mediated vasodilation (FMD) of the brachial artery.

RESULTS

Patients (n = 236) with an ejection fraction (EF) > or = 55% on routine echocardiogram were younger (mean age 58 vs. 62 years), showed a lower prevalence of diabetes (15 vs. 38%) and myocardial infarction (13 vs. 66%), and showed a higher FMD (4.8 +/- 2.4 vs. 4.0 +/- 2.0%, p < 0.05) than patients (n = 47) with an EF < 55%. The correlation coefficient between FMD/endothelial function and EF/systolic heart function was 0.149 (p < 0.02) in the overall study population. Multivariate analysis showed that of age, gender, frequency of diabetes mellitus, myocardial infarction, and CAD extent, EF was the only significant independent parameter correlating with FMD in patients with CAD.

CONCLUSIONS

Compared with the other tested risk factors, EF surprisingly was the only significant independent parameter correlating with endothelial function in patients with CAD. Our results support the view that endothelial function is an independent prognostic factor in patients with CAD.

Food and red wine do not exert acute effects on vascular reactivity

Experimental hyperglycemia and hyperinsulinemia have been shown to affect vascular reactivity. Chronic red wine consumption is associated with less cardiovascular mortality. Whether ingestion of a natural meal and red wine causes acute changes in vascular homeostasis is poorly understood. The aim of the current study was to clarify whether meal ingestion, with and without red wine, exert acute effects on vascular reactivity in healthy humans. We studied vascular reactivity and forearm nitrite balance in 10 healthy subjects under 3 different circumstances: (1) fasting; (2) after ingestion of a standard natural meal (1,050 kcal); and (3) after the same meal enriched with a glass of red wine. We measured forearm blood flow (FBF) by strain-gauge plethismography during intrabrachial, graded infusion of acetylcholine (ACh), sodium nitroprusside (NP), and norepinephrine (NE). We also measured the forearm balance of nitrite before and during ACh infusion. Despite significant increases in plasma glucose and insulin concentrations, the vasodilatory response to Ach and NP after meal ingestion was not different from the fasting response. Similarly, the vasoconstrictory response to NE was similar postprandially and during fasting. Addition of red wine did not modify the response to any of the vasoactive agents. Finally, the forearm nitrite production during Ach infusion was not different in the 3 experimental settings. Food intake, whether associated or not with red wine, does not affect vascular reactivity in normal human subjects.

Effect of simvastatin and fenofibrate on endothelium in Type 2 diabetes

Statins and fibrates influence endothelial activity and consequently atherogenesis but the mechanisms are not well understood. Twenty Type 2 diabetic patients with dyslipidemia were treated 3 months with simvastatin (20 mg daily) and then 3 months with fenofibrate (200 mg daily) with 2 months of wash-out between the two treatments. Laboratory parameters of oxidative stress, fibrinolysis and endothelial function were evaluated before and at the end of each treatment period. The significant decrease in serum total and LDL-cholesterol concentrations (P<0.0001) caused by simvastatin was associated with an increase in serum N-acetyl-beta-glucosaminidase activity (P<0.001), ascorbic acid (P<0.001), plasminogen activator inhibitor (PAI-1) (P<0.01), vonWillebrand factor (P<0.05), E-selectin (P<0.01) and vascular endothelial growth factor (P<0.05) concentrations and with a decrease in plasma glutathione (P<0.01) levels. Fenofibrate caused a significant decrease in serum triglyceride concentration (P<0.0001) associated with a decrease in plasma malondialdehyde (P<0.001) and an increase in plasma PAI-1 (P<0.05) and P-selectin (P<0.05) concentrations. We conclude that simvastatin and fenofibrate interact, by different mechanisms, with oxidative stress, a key factor in the modification of fibrinolysis and endothelial function in Type 2 diabetes.

Effects of fenofibrate on endothelial function and cell adhesion molecules during post-prandial lipemia in hypertriglyceridemia

BACKGROUND

Fasting and post-prandial hypertriglyceridemia have been associated with endothelial dysfunction.

OBJECTIVE

To investigate the effects of a 3-month treatment with fenofibrate (200 mg daily) on endothelial reactivity and inflammatory state in hypertriglyceridemic patients at fast and after an oral fat load.

METHODS

Brachial flow-mediated vasodilation (FMV) and the circulating levels of intercellular adhesion molecule (ICAM) and vascular cellular adhesion molecule (VCAM) were determined in 10 hypertriglyceridemic patients.

RESULTS

Before treatment, post-prandial phase was characterized by an increase in triglycerides (3.7 +/- 1 mmol/L at baseline vs. 4.2 +/- 1, 6.5 +/- 1, 6.6 +/- 2, and 5.3 +/- 2 mmol/L after 2, 4, 6, and 8 h), a decrease in FMV (4.3 +/- 2% at baseline vs. 2.8 +/- 1, 2.2 +/- 1, and 1.3 +/- 1% after 2, 4, and 6 h), and an increase in ICAM and VCAM. After fenofibrate there was a significant reduction in fasting triglycerides (3.7 +/- 1.3 vs. 2.1 +/- 0.8 mmol/L), ICAM (480 +/- 113 vs. 269 +/- 65 ng/mL) and VCAM (1821 +/- 570 vs. 1104 +/- 376 ng/mL), and an increase in FMV (4.3 +/- 2 vs. 7.1 +/- 2%). Post-prandially triglycerides increased (2.1 +/- 1 at baseline vs. 2.4 +/- 2 and 3.6 +/- 1 mmol/L after 4 and 6 h), FMV decreased (7.1 +/- 2 at baseline vs. 5.8 +/- 2, 5.5 +/- 2, 5.9 +/- 2, 6.4 +/- 2% after 2, 4, 6, and 8 h), and there was an increase of ICAM and VCAM. Before therapy post-prandial changes in FMV had an inverse correlation with the changes in triglycerides (r = -0.34; P < 0.05) and ICAM (r = -0.66; P < 0.001).

CONCLUSIONS

The transient endothelial dysfunction observed in hypertriglyceridemic subjects during post-prandial lipemia is mediated by post-prandial triglyceride increase and by the activation of inflammatory response. The anti-inflammatory activity of fenofibrate may represent an additional mechanism of its favorable action on the endothelial function during fasting and the post-prandial phase.

Postprandial hypertriglyceridaemia in patients with Tangier disease

BACKGROUND

Tangier disease (TD) is the phenotypic expression of rare familial syndromes with mutations in the ABCA1 transporter. TD results in extremely low high density lipoprotein (HDL) cholesterol and reduced low density lipoprotein cholesterol, with normal or mildly increased fasting triglyceride (TG) concentrations. Although there is a close relation between HDL cholesterol values and atherogenesis, the risk of coronary artery disease is variable in TD. Raised fasting or postprandial TG values frequently accompany low HDL cholesterol and can add to the risk of a vascular event.

AIMS

To investigate the postprandial TG response in TD.

PATIENTS AND METHODS

Five patients (three homozygotes (HTD) and two heterozygotes (hTD)) from one family were studied. One was defined by DNA analysis as homozygous for a new mutation (C2033A) resulting in truncation of the ABCA1 protein. Their TG concentrations were measured before and four, six, and eight hours after a standardised fat load and compared with a control group.

RESULTS

Two patients with HTD had high fasting TG concentrations. The third patient with HTD, the two with hTD, and the control group had TG concentrations within the reference range. The patients with HTD had increased postprandial peak TG values when compared with those with hTD and controls.

CONCLUSION

Patients with HTD, with or without fasting hypertriglyceridaemia, may have an increased TG response to a fatty meal. The small number of patients does not allow definitive conclusions to be made. However, postprandial hypertriglyceridaemia could be a reason why some patients with TD develop premature atherosclerosis.

Effect of supplemental phytonutrients on impairment of the flow-mediated brachial artery vasoactivity after a single high-fat meal

OBJECTIVES

Our objective was to determine if long-term daily administration of phytonutrient supplements can prevent the immediate adverse impact of a high-fat meal and increase the production of nitric oxide.

BACKGROUND

Ingestion of a high-fat meal impairs flow-mediated vasodilation of the brachial artery for at least 4 h; however, co-ingestion of vitamin antioxidants or a green salad has been shown to prevent this effect.

METHODS

Flow-mediated brachial artery reactivity test (BART) both before and 3 h after a 900 calorie 50 g fat meal was evaluated in 38 healthy volunteers (age 36.4 +/- 10.1 years). Subjects were randomized to four weeks of daily supplementation with a powdered fruit vegetable juice concentrate (Juice Plus [JP]) along with a complex supplement providing nutritional antioxidants and various herbal extracts (Vineyard [V]), JP alone, or a matching placebo. At three and four weeks, BART was repeated both before and after the high-fat meal. Serum nitrate/nitrite concentrations were measured at baseline and at four weeks.

RESULTS

Four weeks of the JP-V combination blunted the detrimental effect of the high-fat meal (-47.5 +/- 23.4% at baseline vs. -1.7 +/- 9.7% at four weeks [p < 0.05]). Four weeks of JP alone had a similar beneficial effect (-45.1 +/- 19.7% at baseline vs. -16.6 +/- 10.3% at four weeks [p < 0.05]), whereas there was no substantial effect of the placebo. In the subjects treated with supplements, concentrations of serum nitrate/nitrite increased from 78 +/- 39 to 114 +/- 62 microm/l (p < 0.02).

CONCLUSIONS

Daily ingestion of modest amounts of a fruit/vegetable juice concentrate with or without adjunctive phytonutrient supplementation can reduce the immediate adverse impact of high-fat meals on flow-mediated vasoactivity and increase nitrate/nitrite blood concentration.

Oxidized fat in the diet, postprandial lipaemia and cardiovascular disease

Accumulating evidence suggests that oxidized fats and lipid oxidation products in the diet can contribute to the pathogenesis of atherosclerosis. The present review summarizes studies that show that oxidized fat and lipid oxidation products are present in human foods; that these compounds are absorbed by the intestine and appear in the blood circulation; and that these ingested substances can have deleterious cardiovascular effects in both humans and experimental animals. However, considerable additional research is required to establish the extent to which dietary fat oxidation poses a threat to human health and/or longevity.