Alimentary lipemia, postprandial triglyceride-rich lipoproteins, and common carotid intima-media thickness in healthy, middle-aged men

The effect of two iso-caloric meals containing equal amounts of fats with a different fat composition on the inflammatory and metabolic markers in apparently healthy volunteers

Background

Little is known about the time-course of the postprandial appearance of macronutrient-induced inflammatory response. Our aim was to investigate the postprandial inflammatory and metabolic response following high fat, high caloric popular meals in apparently healthy participants.

Methods

Fifty four apparently healthy normal weight volunteers (BMI of 25.9±0.9) were given two iso-caloric meals with similar amounts but different composition of fats: a meal high in monounsaturated fats (MUFA), and a meal high in saturated fat (SFA). Three main effects and the interactions between them were analyzed: the time (before and 2 and 4 hours following the meals), the meal (MUFA or SFA) and the gender.

Results

The effect of time from the meal on hs-CRP level was highly significant (p=0.004). The highest responses were observed 2 hours after the meal (p=0.002). A statistically significant interaction was found between the time and the meal (p≤0.0001), which reflects the higher increase in hs-CRP values 2 hours after the SFA meal, with no effect by the MUFA meal. The white blood cell counts were affected significantly by the time (p≤0.0001) however, other inflammatory markers (fibrinogen, IL-6, TNFα, ICAM and VICAM) were not. All the metabolic markers (insulin, glucose, HOMA-R, QUICKI and triglycerides) were affected by the time (p≤0.0001), with no interactions observed.

Conclusions

Metabolic and modest inflammatory changes occur within a few hours after the ingestion of a high SFA meal in apparently healthy adults.

Postprandial lipemia in pre- and postmenopausal women

Background and Objective:

The increased risk for coronary artery disease observed in postmenopausal (PoW) women is partly explained by a more atherogenic lipoprotein profile. Moreover, natural menopause has been associated with an altered postprandial lipid profile. This study was designed to test the hypothesis that young premenopausal (PrW) and PoW may be independently associated with postprandial lipemia and indirectly associated with atherosclerosis.

Patients and Methods:

A total of 46 healthy PrW and 44 healthy PoW participated in a 5-h intervention study. Blood samples were taken at the baseline and at 1, 2, 3, and 4 h after eating. Total cholesterol, LDL-cholesterol, HDL-cholesterol, fasting, and postprandial triglycerides (PPTG) were determined sequentially in blood samples.

Results:

PPTG presented significant higher values in PoW compared to PrW (P < 0.05), but other lipids did not significantly differ between groups. PPTG concentrations in PoW were significantly higher than in PrW (P < 0.05). There was a significant time influence (P < 0.05) in TG in PrW and PoW, while time to peak and peak concentration were significantly higher in PoW than PrW. Other lipids were also decreased more in PrW than PoW, but not significantly so. Cholesterol concentrations showed a significant reduction after 2 h, to reach values similar to the baseline after 4 h in PrW but not in PoW. HDL-cholesterol concentration was decreased more in PoW compared to PrW but it was not significant.

Conclusions:

Lipid postprandial response indicates a higher cardiovascular risk pattern in PoW compared to PrW.

Extended-release niacin acutely suppresses postprandial triglyceridemia

OBJECTIVE

Postprandial triglyceridemia predicts cardiovascular events. Niacin might lower postprandial triglycerides by restricting free fatty acids. Immediate-release niacin reduced postprandial triglycerides, but extended-release niacin failed to do so when dosed the night before a fat challenge. The study aims were to determine whether extended-release niacin dosed before a fat challenge suppresses postprandial triglycerides and whether postprandial triglycerides are related to free fatty acid restriction.

METHODS

A double-blinded, placebo-controlled, random-order crossover experiment was performed, in which healthy volunteers took 2 g extended-release niacin or placebo 1 hour before heavy cream. We sampled blood over 12 hours and report triglycerides and free fatty acid as means ± standard deviation for incremental area under the curve (AUC) and nadir.

RESULTS

By combining 43 fat challenges from 22 subjects, postprandial triglycerides incremental AUC was +312 ± 200 mg/dL*h on placebo versus +199 ± 200 mg/dL*h on extended-release niacin (33% decrease, P=.02). The incremental nadir for free fatty acid was -0.07 ± 0.15 mmol/L on placebo versus -0.27 ± 0.13 mmol/L on extended-release niacin (P<.0001), and free fatty acid incremental AUC decreased from +2.9 ± 1.5 mmol/L*h to +1.5 ± 1.5 mmol/L*h on extended-release niacin (20% decrease, P=.0015). The incremental AUC for triglycerides was strongly related to the post-dose decrease in free fatty acid (r = +0.58, P=.0007).

CONCLUSIONS

Given right before a fat meal, even a single dose of extended-release niacin suppresses postprandial triglyceridemia. This establishes that postprandial triglycerides suppression is an acute pharmacodynamic effect of extended-release niacin, probably the result of marked free fatty acid restriction. Further study is warranted to determine whether mealtime dosing would augment the clinical efficacy of extended-release niacin therapy.

Postprandial Peaking and Plateauing of Triglycerides and VLDL in Patients with Underlying Cardiovascular Diseases Despite Treatment

BACKGROUND

Dyslipidemia is associated with cardiovascular morbidities and mortality. Currently, fasting lipid profile determination is used to monitor treatment response. Recently, postprandial lipemia is of increasing interest because of its atherogenic and thrombogenic potential and also was found to be more predictive for cardiovascular diseases.

OBJECTIVES

To demonstrate postprandial lipemia among patients with cardiovascular diseases despite low fat diet, normal fasting lipid profile and even statin regimen.

PATIENTS AND METHODS

Patients aged 40-80 years old with cardiovascular diseases (i.e. coronary artery disease and cerebrovascular disease) more than 6 months, on statin treatment for more than 6 months and normal fasting lipid profile (according to NCEP ATP III guidelines) were included. Study exclusion criteria were pregnancy, acute cardiovascular events < 6 months, hepatic or renal failure. Finally, twelve patients were included.

RESULTS

The triglyceride level showed a significant rise from fasting to 2 hours after breakfast with a mean difference of 23.86 mg/dL (P =0.012). The level peaked at 4 hours after breakfast with a mean difference (MD) of 72.02 mg/dL (P =0.002). Subsequent triglyceride levels plateaued and were significantly higher than the baseline (P <0.05) until the 12th hour of observation. VLDL levels showed a similar pattern. Levels increased significantly from fasting to 2h after breakfast (mean difference: 4.49 mg/dL, P = 0.007), then plateaued and further increased 4 hours after breakfast (MD: 14.01 mg/dL, P = 0.002). VLDL levels were significantly higher than fasting (P < 0.05) and did not return to baseline until the 12th hour of observation. In contrast, the levels of total cholesterol, HDL and LDL decreased postprandially.

CONCLUSIONS

Triglyceride and VLDL peaking and plateauing were observed in patients with cardiovascular diseases despite low fat diet, normal fasting lipid profile and statin regimen. These findings may raise more attentions in monitoring and management of dyslipidemia in patients with cardiovascular and cerebrovascular events.

Association of postalimentary lipemia with atherosclerotic manifestations

We identified different lipemic and metabolic responses after the ingestion of a standardized meal by healthy adults and related them to atherosclerotic markers. Samples from 60 normolipidemic adults were collected before and after a liquid meal (40 g fat/m² body surface) at 0, 2, 4, 6, and 8 h for measurements of lipids, free fatty acids (FFA), insulin, cholesteryl ester transfer protein (CETP), autoantibodies to epitopes of oxidized LDL (oxLDL Ab), lipolytic activities, and apolipoprotein E polymorphism. Mean carotid intima-media thickness (cIMT) was determined by Doppler ultrasound. The volunteers were classified into early (N = 39) and late (N = 31) triacylglycerol (TAG) responders to the test meal. Late responders showed lower HDL cholesterol concentration at fasting and in the TAG peak, lower insulin and higher FFA concentrations compared to early responders. Multivariate regression analyses showed that mean cIMT was associated with gender (male) and age in early responders and by cholesterol levels at the 6th hour in late responders. oxLDL Ab were explained by lipoprotein lipase and negatively by hepatic lipase and oxLDL Ab (fasting period) by CETP (negative) and FFA (positive). This study is the first to identify a postalimentary insulin resistance state, combined with a reduced CETP response exclusively among late responders, and the identification of the regulators of postalimentary atherogenicity. Further research is required to determine the metabolic mechanisms described in the different postalimentary phenotypes observed in this study, as well as in different pathological states, as currently investigated in our laboratory.

The ddY mouse: a model of postprandial hypertriglyceridemia in response to dietary fat

Postprandial hyperlipidemia (lipemia) is a risk factor for atherosclerosis. However, mouse models of postprandial hyperlipidemia have not been reported. Here, we report that ddY mice display marked postprandial hypertriglyceridemia in response to dietary fat. In ddY mice, the fasting serum total triacylglyceride (TG) concentration was 134 mg/dl, which increased to 571 mg/dl after an intragastric safflower oil load (0.4 ml/mouse). In C57BL/6J mice, these concentrations were 57 and 106 mg/dl, respectively. By lipoprotein analysis, ddY mice showed increases in chylomicron- and VLDL-sized TG fractions (remnants and VLDL) after fat load. In C57BL/6J mice, post-heparin plasma LPL activity after fat load was increased 4.8-fold relative to fasting. However, in ddY mice, the increase of LPL activity after fat load was very small (1.2-fold) and not significant. High fat feeding for 10 weeks led to obesity in ddY mice. A difference in LPL amino acid composition between C57BL/6J and ddY mice was detected but was deemed unlikely to cause hypertriglyceridemia because hypertriglyceridemia was not evident in other strains harboring the ddY-type LPL sequence. These findings indicate that postprandial hypertriglyceridemia in ddY mice is induced by decreased LPL activity after fat load and is associated with obesity induced by a high-fat diet.

The transcription factor HNF-4α: a key factor of the intestinal uptake of fatty acids in mouse

With an excessive postprandial accumulation of intestine-derived, triglyceride-rich lipoproteins being a risk factor of cardiovascular diseases, it is essential to characterize the mechanisms controlling the intestinal absorption of dietary lipids. Our aim was to investigate the role of the transcription factor hepatocyte nuclear factor (HNF)-4α in this process. We used transgenic mice with a specific and inducible intestinal knockout of Hnf-4α gene. One hour after a lipid bolus, in the presence of the lipase inhibitor tyloxapol, lower amounts of triglycerides were found in both plasma and intestinal epithelium of the intestine-specific Hnf-4α knockout (Hnf-4α(intΔ)) mice compared with the Hnf-4α(loxP/loxP) control mice. These discrepancies were due to a net decrease of the intestinal uptake of fatty acid in Hnf-4α(intΔ) mice compared with Hnf-4α(loxP/loxP) mice, as assessed by the amount of radioactivity that was recovered in intestine and plasma after gavage with labeled triolein or oleic acid, or in intestinal epithelial cells isolated from jejunum after a supply of labeled oleic acid-containing micelles. This decreased fatty acid uptake was associated with significant lower levels of the fatty acid transport protein-4 mRNA and protein along the intestinal tract and with a lower acyl-CoA synthetase activity in Hnf-4α(intΔ) mice compared with the control mice. We conclude that the transcription factor HNF-4α is a key factor of the intestinal absorption of dietary lipids, which controls this process as early as in the initial step of fatty acid uptake by enterocytes.

High-intensity exercise attenuates postprandial lipaemia and markers of oxidative stress

Regular exercise can reduce the risk of CVD (cardiovascular disease). Although moderate-intensity exercise can attenuate postprandial TAG (triacylglycerol), high-intensity intermittent exercise might be a more effective method to improve health. We compared the effects of high-intensity intermittent exercise and 30 min of brisk walking on postprandial TAG, soluble adhesion molecules and markers of oxidative stress. Nine men each completed three 2-day trials. On day 1, subjects rested (control), walked briskly for 30 min (walking) or performed 5×30 s maximal sprints (high-intensity). On day 2, subjects consumed a high-fat meal for breakfast and 3 h later for lunch. Blood samples were taken at various times and analysed for TAG, glucose, insulin, ICAM-1 (intracellular adhesion molecule-1), VCAM-1 (vascular adhesion molecule-1), TBARS (thiobarbituric acid- reactive substances), protein carbonyls and β-hydroxybutyrate. On day 2 of the high-intensity trial, there was a lower (P<0.05) incremental TAG AUC (area under the curve; 6.42±2.24 mmol/l per 7 h) compared with the control trial (9.68±4.77 mmol/l per 7 h) with no differences during day 2 of the walking trial (8.98±2.84 mmol/l per 7 h). A trend (P=0.056) for a reduced total TAG AUC was also seen during the high-intensity trial (14.13±2.83 mmol/l per 7 h) compared with control (17.18±3.92 mmol/l per 7 h), walking showed no difference (16.33±3.51 mmol/l per 7 h). On day 2 of the high-intensity trial plasma TBARS and protein carbonyls were also reduced (P<0.05) when compared with the control and walking trials. In conclusion, high-intensity intermittent exercise attenuates postprandial TAG and markers of oxidative stress after the consumption of a high-fat meal.

Magnesium lithospermate B mediates anti-inflammation targeting activator protein-1 and nuclear factor-kappa B signaling pathways in human peripheral T lymphocytes

The activation of T lymphocytes contributes to the inflammatory processes of atherosclerotic diseases. Danshen is a traditional Chinese medicine and has shown therapeutic effects in patients with cardiovascular and cerebrovascular diseases. We investigated the effects of aqueous extract of Danshen (magnesium lithospermate B (MLB)) on phorbol 12-myristate acetate+ionomycin and anti-CD3+anti-CD28 monoclonal antibody-activated T cells. We showed that MLB inhibited interleukin (IL)-2, IL-4, tumor necrosis factor-alpha and interferon-gamma production from activated T cells. The expressions of T cell activation markers CD 25 and CD 69 were effectively reduced. EMSA analysis indicated that MLB down-regulated activator protein-1 (AP-1), nuclear factor kappa B (NF-κB) and octamer binding transcription factor (Oct-1) DNA-binding activity. In addition, MLB inhibited c-jun N-terminal kinase (JNK) but not extracellular signal regulated protein kinase activity. MLB also inhibited IκBα degradation, nuclear translocation of p65 and p50 as well as decreased IκBα kinase (IKK) activity. Through suppressing JNK-AP-1, IKK-IκBα-NF-κB and Oct-1 signaling pathways by MLB in activated T cells, our results provide support for efficacy of MLB in inflammatory diseases and raise its therapeutic potential in activated T cell-mediated pathologies.

Understanding postprandial inflammation and its relationship to lifestyle behaviour and metabolic diseases

Postprandial hyperlipidemia with accumulation of remnant lipoproteins is a common metabolic disturbance associated with atherosclerosis and vascular dysfunction, particularly during chronic disease states such as obesity, the metabolic syndrome and, diabetes. Remnant lipoproteins become attached to the vascular wall, where they can penetrate intact endothelium causing foam cell formation. Postprandial remnant lipoproteins can activate circulating leukocytes, upregulate the expression of endothelial adhesion molecules, facilitate adhesion and migration of inflammatory cells into the subendothelial space, and activate the complement system. Since humans are postprandial most of the day, the continuous generation of remnants after each meal may be one of the triggers for the development of atherosclerosis. Modulation of postprandial lipemia by lifestyle changes and pharmacological interventions could result in a further decrease of cardiovascular mortality and morbidity. This paper will provide an update on current concepts concerning the relationship between postprandial lipemia, inflammation, vascular function, and therapeutic options.

The apolipoprotein C-I content of very-low-density lipoproteins is associated with fasting triglycerides, postprandial lipemia, and carotid atherosclerosis

Background. Experimental studies in animals suggest that apolipoprotein (apo) C-I is an important regulator of triglycerides in fasting and postprandial conditions and associated with carotid atherosclerosis. Methods. A cross-sectional study was conducted with 81 subjects, aged 56–80 years recruited from a population health survey. The participants underwent a fat tolerance test (1 g fat per Kg body weight) and carotid atherosclerosis was determined by ultrasound examination. VLDL particles, Sf 20–400, were isolated and their lipid composition and apoC-I content determined. Results. The carotid plaque area increased linearly with the number of apoC-I molecules per VLDL particles (P = 0.048) under fasting conditions. Fasting triglycerides increased across tertiles of apoC-I per VLDL particle in analyses adjusted for apoC-II and -C-III, apoE genotype and traditional cardiovascular risk factors (P = 0.011). The relation between apoC-I in VLDL and serum triglycerides was conveyed by triglyceride enrichment of VLDL particles (P for trend <0.001. The amount of apoC-I molecules per VLDL was correlated with the total (r = 0.41, P < 0.0001) and incremental (r = 0.35, P < 0.001) area under the postprandial triglyceride curve. Conclusions. Our findings support the concept that the content of apoC-I per VLDL particle is an important regulator of triglyceride metabolism in the fasting and postprandial state and associated with carotid athrosclerosis.

Identification of diacylglycerol acyltransferase inhibitors from Rosa centifolia petals

Diacylglycerol acyltransferase (DGAT) catalyzes the final step of triacylglycerol (TAG) synthesis, and is considered as a potential target to control hypertriglyceridemia or other metabolic disorders. In this study, we found that the extract of rose petals suppressed TAG synthesis in cultured cells, and that the extract showed DGAT inhibitory action in a dose-dependent manner. Fractionation of the rose extract revealed that the DGAT inhibitory substances in the extract were ellagitannins; among them rugosin B, and D, and eusupinin A inhibited DGAT activity by 96, 82, and 84% respectively, at 10 μM. These substances did not inhibit the activities of other hepatic microsomal enzymes, glucose-6-phosphatase and HMG-CoA reductase, or pancreatic lipase, suggesting that ellagitannins inhibit DGAT preferentially. In an oral fat load test using mice, postprandial plasma TAG increase was suppressed by rose extract; TAG levels 2 h after the fat load were significantly lower in mice administered a fat emulsion containing rose extract than in control mice (446.3 ± 33.1 vs 345.3 ± 25.0 mg/dL, control vs rose extract group; P < 0.05). These results suggest that rose ellagitannins or rose extract could be beneficial in controlling lipid metabolism and used to improve metabolic disorders.

Role of heparanase on hepatic uptake of intestinal derived lipoprotein and fatty streak formation in mice

Background

Heparanase modulates the level of heparan sulfate proteoglycans (HSPGs) which have an important role in multiple cellular processes. Recent studies indicate that HSPGs have an important function in hepatic lipoprotein handling and processes involving removal of lipoprotein particles.

Principal Findings

To determine the effects of decreased HSPGs chain length on lipoprotein metabolism and atherosclerosis, transgenic mice over-expressing the human heparanase gene were studied.

Hepatic lipid uptake in hpa-Tg mice were evaluated by giving transgenic mice oral fat loads and labeled retinol. Sections of aorta from mice over-expressing heparanase (hpa-Tg) and controls (C57/BL6) fed an atherogenic diet were examined for evidence of atherosclerosis. Heparanase over-expression results in reduced hepatic clearance of postprandial lipoproteins and higher levels of fasting and postprandial serum triglycerides. Heparanase over-expression also induces formation of fatty streaks in the aorta. The mean lesion cross-sectional area in heparanase over-expressing mice was almost 6 times higher when compared to control mice (23,984 µm²±5,922 vs. 4,189 µm²±1,130, p<0.001).

Conclusions

Over-expression of heparanase demonstrates the importance of HSPGs for the uptake of intestinal derived lipoproteins and its role in the formation of fatty streaks.

Effect of a fatty meal on inflammatory markers in healthy volunteers with a family history of type 2 diabetes

A family history of type 2 diabetes (T2D) confers a high risk of developing the disease, independent of that due to other common risk factors. Postprandial state is a pro-inflammatory condition associated with a transiently impaired endothelial function; an increased oxidative stress is considered as a mediator of such effects in T2D. We evaluated the short-term effect of a lipid meal on markers of early vascular damage in subjects at risk of developing T2D. A total of thirty-two healthy volunteers, divided according to the presence (FHD+) or absence (FHD - ) of a family history of T2D, underwent a fatty meal test. We measured the monocyte mRNA expressions of IL-6, IL-8 and IL-1β, and IL-6, soluble CD40 ligand (sCD40L), vascular cellular adhesion molecule-1 (VCAM-1), intracellular adhesion molecule-1 (ICAM-1) and nitrotyrosine plasma concentrations at baseline and in the post-meal phase, relating them to the lipid profile and other biochemical parameters. The basal expression of the cytokines did not differ in FHD -  and FHD+ subjects; neither was it modified by the meal ingestion. IL-6 and sCD40L plasma levels, similar in the two groups in the fasting state, did not vary after the meal. VCAM-1 and ICAM-1 increased in FHD+ subjects but not in FHD -  subjects. Nitrotyrosine, similar between the FHD -  and FHD+ subjects at baseline, increased more in FHD+ subjects than in FHD -  subjects after the meal. In conclusion, the presence of a familial history of T2D confers an abnormal endothelial activation after an oral lipid meal, coupled with an increased oxidative stress, supporting the hypothesis of an early endothelial dysfunction already present in healthy individuals prone to develop T2D.

CD11c/CD18 expression is upregulated on blood monocytes during hypertriglyceridemia and enhances adhesion to vascular cell adhesion molecule-1

OBJECTIVE

Atherosclerosis is associated with monocyte adhesion to the arterial wall that involves integrin activation and emigration across inflamed endothelium. Involvement of β(2)-integrin CD11c/CD18 in atherogenesis was recently shown in dyslipidemic mice, which motivates our study of its inflammatory function during hypertriglyceridemia in humans.

METHODS AND RESULTS

Flow cytometry of blood from healthy subjects fed a standardized high-fat meal revealed that at 3.5 hours postprandial, monocyte CD11c surface expression was elevated, and the extent of upregulation correlated with blood triglycerides. Monocytes from postprandial blood exhibited an increased light scatter profile, which correlated with elevated CD11c expression and uptake of lipid particles. Purified monocytes internalized triglyceride-rich lipoproteins isolated from postprandial blood through low-density lipoprotein-receptor-related protein-1, and this also elicited CD11c upregulation. Laboratory-on-a-chip analysis of whole blood showed that monocyte arrest on a vascular cell adhesion molecule-1 (VCAM-1) substrate under shear flow was elevated at 3.5 hours and correlated with blood triglyceride and CD11c expression. At 7 hours postprandial, blood triglycerides decreased and monocyte CD11c expression and arrest on VCAM-1 returned to fasting levels.

CONCLUSIONS

During hypertriglyceridemia, monocytes internalize lipids, upregulate CD11c, and increase adhesion to VCAM-1. These data suggest that analysis of monocyte inflammation may provide an additional framework for evaluating individual susceptibility to cardiovascular disease.

Up-regulation of hepatic lipolysis stimulated lipoprotein receptor by leptin: a potential lever for controlling lipid clearance during the postprandial phase

As a hepatic receptor for triglyceride-rich lipoproteins, the lipolysis-stimulated lipoprotein receptor (LSR) may be involved in the dynamics of lipid distribution between the liver and peripheral tissues. Here, we explore the potential role of leptin in regulating LSR. At physiological concentrations (1-10 ng/ml), leptin increased LSR protein and mRNA levels in Hepa1-6 cells through an ERK1/2-dependent and α-amanitin-sensitive pathway. In vivo, leptin treatment of C57BL6/Rj mice (1 μg 2×/d, 8 d) led to a significant increase in hepatic LSR mRNA and protein, decreased liver triglycerides and increased VLDL secretion as compared to controls. LSR(+/-) mice with elevated postprandial lipemia placed on a high-fat (60% kcal) diet exhibited accelerated weight gain and increased fat mass as compared to controls. While plasma leptin levels were increased 3-fold, hepatic leptin receptor protein levels and phosphorylation of ERK1/2 were significantly reduced. Therefore, leptin is an important regulator of LSR protein levels providing the means for the control of hepatic uptake of lipids during the postprandial phase. However, this may no longer be functional in LSR(+/-) mice placed under a chronic dietary fat load, suggesting that this animal model could be useful for the study of molecular mechanisms involved in peripheral leptin resistance.

Dyslipidaemia in the metabolic syndrome and type 2 diabetes: pathogenesis, priorities, pharmacotherapies

IMPORTANCE OF THE FIELD

Dyslipoproteinaemia is a cardinal feature of the metabolic syndrome that accelerates atherosclerosis. It is usually characterized by high plasma concentrations of triglyceride-rich and apolipoprotein B (apoB)-containing lipoproteins, with depressed concentrations of high-density lipoprotein (HDL). Drug interventions are essential for normalizing metabolic dyslipidaemia.

AREAS COVERED IN THIS REVIEW

This review discusses the mechanisms and treatment for dyslipidaemia in the metabolic syndrome and type 2 diabetes.

WHAT THE READER WILL GAIN

A comprehensive understanding of the pathophysiology and pharmacotherapy of dyslipidaemia in the metabolic syndrome and diabetes.

TAKE HOME MESSAGE

Dysregulation of lipoprotein metabolism may be due to a combination of overproduction of triglyceride-rich lipoproteins, decreased catabolism of apoB-containing particles, and increased catabolism of HDL particles. These abnormalities may be consequent on a global metabolic effect of insulin resistance and an excess of both visceral and hepatic fat. Lifestyle modifications may favourably alter lipoprotein transport in the metabolic syndrome. Patients with dyslipidaemia and established cardiovascular disease should receive a statin as first-line therapy. Combination with other lipid-regulating agents, such as ezetimibe, fibrates, niacins and fish oils may optimize the benefit of statin on atherogenic dyslipidaemia.

Genetic effects on postprandial variations of inflammatory markers in healthy individuals

Circulating levels of inflammatory markers predict the risk of cardiovascular disease (CVD), mediated perhaps in part by dietary fat intake, through mechanisms only partially understood. To evaluate post-fat load changes in inflammatory markers and genetic influences on these changes, we administered a standardized high-fat meal to 838 related Amish subjects as part of the Heredity and Phenotype Intervention (HAPI) Heart Study and measured a panel of inflammatory markers, including C-reactive protein (CRP), interleukin-1beta (IL-1beta), matrix metalloproteinase-1 and -9 (MMP-1 and MMP-9), and white blood cell (WBC) count, before and 4 h after fat challenge (CRP prechallenge only). Heritabilities (h(2) +/- s.d.) of basal inflammatory levels ranged from 16 +/- 8% for MMP-9 (P = 0.02) to 90 +/- 7% for MMP-1 (P < 0.0001). Post-fat load, circulating levels of WBC, MMP-1, and MMP-9 increased by 16, 32, and 43% (all P < 0.0001), with no significant changes in IL-1beta. Postprandial changes over the 4-h period were modestly heritable for WBC (age- and sex-adjusted h(2) = 14 +/- 9%, P = 0.04), but the larger MMP-1 and MMP-9 changes appeared to be independent of additive genetic effects. These results reveal that a high-fat meal induces a considerable inflammatory response. Genetic factors appear to play a significant role influencing basal inflammatory levels but to have minimal influence on post-fat intake inflammatory changes.

Comparative study of bezafibrate and pravastatin in patients with coronary artery disease and high levels of remnant lipoprotein

BACKGROUND

Remnant lipoproteinemia is a strong risk factor for cardiovascular (CV) diseases. This study examined which of 2 common lipid-lowering drugs (fibrates and statins) is more effective in patients with remnant lipoproteinemia and if lowering remnant lipoprotein levels can reduce CV risk.

METHODS AND RESULTS

Remnant lipoprotein levels were measured by an immunoseparation method (remnant-like lipoprotein particles cholesterol: RLP-C) in 274 patients with coronary artery disease and high RLP-C levels (>or=5.0 mg/dl). They were randomly assigned to receive bezafibrate (200-400 mg/day) or pravastatin (10-20 mg/day), and were prospectively followed-up for 1 year or until the occurrence of CV events. Complete follow-up data were obtained in 180 patients. RLP-C levels at 1 year of treatment were reduced more by bezafibrate than pravastatin (37% and 25% from baseline, respectively). During follow-up, bezafibrate-treated patients had 3 CV events, compared with 12 events in pravastatin-treated patients (P<0.01). In multivariate logistic regression analysis, a decrease in RLP-C level was significantly associated with a reduction in CV events after adjustment for treatment group and changes in levels of other lipids.

CONCLUSIONS

Bezafibrate therapy decreased RLP-C levels to a greater extent than pravastatin and a decrease in RLP-C level may be associated with a reduction in CV events in patients with high RLP-C levels.

Postprandial metabolic responses to dietary glycemic index in hypercholesterolemic postmenopausal women

Cardiovascular disease is the leading cause of death in postmenopausal women. While diet and lifestyle remain the cornerstones of prevention, a low-fat/high-carbohydrate diet is associated with hyperglycemia and hyperlipemia-atherosclerotic risk factors affected by postprandial conditions. The objective of this study was to examine the acute response of lipids and insulin to a low-fat/high-carbohydrate meal with either a high-glycemic or a low-glycemic index in healthy postmenopausal women. Fifteen healthy postmenopausal women were enrolled in a randomized crossover dietary intervention study. Levels of glucose, triglyceride, free fatty acids (FFAs), and insulin were measured preprandially and for 240 minutes after consumption of the test meals. In response to the high-glycemic compared with the low-glycemic index meal, postprandial insulin levels had a higher peak (65.4 vs 48.1 microU/mL, respectively), the homeostasis model assessment-insulin resistance (HOMA-IR) was significantly higher (P=.014), serum triglyceride levels declined significantly (P<.001), and there was a small reduction in FFA levels, although the difference did not reach statistical significance. The results suggest a postprandial impact of glycemic index on cardiovascular metabolic biomarkers in postmenopausal women and may have implications for dietary glycemic modification of cardiovascular risk in women.

Difference between fasting and nonfasting triglyceridemia; the influence of waist circumference

AIM

Postprandial hypertriglyceridemia is recognized as an independent risk factor for cardiovascular disease. The aim of this study was to identify differences between fasting and postprandial TG levels, focusing on the influence of waist circumference.

METHODS

Subjects included 1,505 men and 798 women aged 3865 years who were not taking medications for diabetes or dyslipidemia. Fasting TG levels were measured after an overnight fast, and postprandial TG levels were measured 2 hours after a standardized rice-based lunch (total 740 kcal, 20 g fat, 30 g protein, and 110 g carbohydrates) in the afternoon on the same day.

RESULTS

Fasting and postprandial TG levels were highly correlated in both men (r=0.86, p<0.001) and women (r=0.84, p<0.001). Waist circumference was positively correlated with fasting TG (r=0.38 in men and r=0.36 in women) and postprandial TG (r=0.42 in men and r=0.45 in women), respectively. On multiple regression analyses, the association of waist circumference with postprandial TG was still significant (standardized beta=0.10 in men and standardized beta=0.15 in women, p<0.001) after the inclusion of HbA1c, age, high-density-lipoprotein (HDL)-cholesterol, alcohol consumption, and fasting TG in the regression model.

CONCLUSION

Postprandial TG has a better relation with waist circumference than fasting TG.

Glucagon-like peptide-2 increases intestinal lipid absorption and chylomicron production via CD36

BACKGROUND & AIMS

Excessive postprandial lipemia is a prevalent condition that results from intestinal oversecretion of apolipoprotein B48 (apoB48)-containing lipoproteins. Glucagon-like peptide-2 (GLP-2) is a gastrointestinal-derived intestinotropic hormone that links nutrient absorption to intestinal structure and function. We investigated the effects of GLP-2 on intestinal lipid absorption and lipoprotein production.

METHODS

Intestinal lipid absorption and chylomicron production were quantified in hamsters, wild-type mice, and Cd36(-/-) mice infused with exogenous GLP-2. Newly synthesized apoB48 was metabolically labelled in primary hamster jejunal fragments. Fatty acid absorption was measured, and putative fatty acid transporters were assessed by immunoblotting.

RESULTS

Human GLP-2 increased secretion of the triglyceride (TG)-rich lipoprotein (TRL)-apoB48 following oral administration of olive oil to hamsters; TRL and cholesterol mass each increased 3-fold. Fast protein liquid chromatography profiling indicated that GLP-2 stimulated secretion of chylomicron/very low-density lipoprotein-sized particles. Moreover, GLP-2 directly stimulated apoB48 secretion in jejunal fragments cultured ex vivo, increased expression of fully glycosylated cluster of differentiation 36/fatty acid translocase (CD36), and induced intestinal absorption of [(3)H]triolein. The ability of GLP-2 to increase intestinal lipoprotein production was lost in Cd36(-/-) mice.

CONCLUSIONS

GLP-2 stimulates intestinal apoB48-containing lipoprotein secretion, possibly through increased lipid uptake, via a pathway that requires CD36. These findings suggest that GLP-2 represents a nutrient-dependent signal that regulates intestinal lipid absorption and the assembly and secretion of TRLs from intestinal enterocytes.

Red-wine Beneficial Long-term Effect on Lipids but not on Antioxidant Characteristics in Plasma in a Study Comparing Three Types of Wine--Description of twoO-methylated Derivatives of Gallic Acid in Humans

The purpose of this double clinical study was (1) to evaluate the effect of one single intake (300 ml) of red wine (RW) on the plasma antioxidant capacity (pAOC) and plasma phenolics over the 24-h time period following the intake, and (2) to compare the long-term effects of daily intakes (250 ml/d) of RW, white wine (WW) and Champagne (CH) on the plasma and LDL characteristics of healthy subjects. In the first part, blood samples were collected just before and after wine consumption. In the second part, subjects received the 3 types of wine successively, only at the mealtime, over 3-week periods separated by a 3-week wash out. Blood samples were drawn in fasting condition before and after each 3-week wine consumption period. The peak of pAOC was at 3-4 h following the single intake of RW, that of catechin was at 4 h (0.13 micromol/l) and that of gallic acid and caffeic acid was earlier (< or = 1.5 and 0.3 micromol/l, respectively). In plasma, the major form of gallic acid was 4-O-methylated, but a minor form (the 3-O-methyl derivative) appeared. In the long term study, no wine was able to change LDL oxidizability, but some other parameters were modified specifically: RW decreased pAOC (without changing TBARS and uric acid plasma levels), LDL lipids and total cholesterol (TC), and increased plasma apoA1, whereas CH increased plasma vitamin A. The beneficial effect of RW seems to mainly be explained by its action on lipid and lipoprotein constants, and not by its antioxidant one.

Sex-associated effect of CETP and LPL polymorphisms on postprandial lipids in familial hypercholesterolaemia

Background

This study assessed the gender-specific influence of the cholesteryl ester transfer protein (TaqIB, I405V) and lipoprotein lipase (S447X) polymorphisms on the response to an oral fat tolerance test in heterozygotes for familial hypercholesterolaemia.

Methods

We selected and genotyped 80 men and postmenopausal women heterozygous for familial hypercholesterolaemia (main group) as well as 11 healthy control subjects. Patients were subgrouped based on their response to oral fat tolerance test. The oral fat tolerance test was defined as pathological when postprandial triglyceride concentration was higher than the highest triglyceride concentration observed in healthy subjects (220 mg/dl) at any time (2, 4, 6 or 8 h).

Results

In the pathological subgroup, men had significantly higher incremental area under the curve after oral fat tolerance test than postmenopausal women. Furthermore, multivariate analysis revealed a gender association of TaqIB and I405V influence on postprandial lipaemia in this subgroup.

Conclusion

In conclusion, it seems that gender and TaqIB polymorphism of the cholesteryl ester transfer protein gene were both associated with the distribution of triglyceride values after oral fat tolerance test, only in subjects with a pathological response to oral fat tolerance test. Specifically, men carrying the B2 allele of the TaqIB polymorphism showed a higher postprandial triglyceride peak and a delayed return to basal values compared with women carrying B2. However, further investigations in larger populations are required to replicate and confirm these findings.

GLP-1 agonist-based therapies: an emerging new class of antidiabetic drug with potential cardioprotective effects

Cardiovascular disease is a leading cause of death in the United States and across the world, and better therapies are constantly being sought to improve patient outcomes. Recent studies have brought our attention to the mechanisms of glucagon-like peptide 1 (GLP-1). Not only does it demonstrate beneficial effects in regard to cardiovascular risk factors (i.e., diabetes, lipid management, and weight control), but it also has been shown in animal studies to have positive cardiac effects irrespective of its effects on glucose control and weight loss. This review discusses the biology of GLP-1 and its effects on cardiovascular risk factors, and it also elaborates on the positive direct cardiovascular outcomes of GLP-1 in animal studies.

Postprandial lipemia 16 and 40 hours after low-volume eccentric resistance exercise

PURPOSE

There is evidence to suggest that muscle damage caused by resistance exercise (RE) may increase postprandial lipemia (PPL). This study examined PPL for two consecutive days after a protocol of low-volume eccentric RE that caused muscle damage.

METHODS

Nine healthy, untrained male volunteers aged 27.2 +/- 1.1 yr performed a session of eccentric RE consisting of eight sets of inclined leg presses at six repetition maximum with 3-min rest intervals. A high-fat meal (1.2 g fat, 1.2 g carbohydrate, 0.22 g protein, and 68.6 kJ kg(-1) body mass) was administered 16 h (day 1) and 40 h (day 2) after exercise as well as after an overnight fast with no prior exercise (control condition [C]). Venous blood samples were obtained before and hourly for 6 h after each meal.

RESULTS

The duration of the exercise session (including rest intervals) was 25.6 +/- 0.2 min, whereas net exercise time was 4.6 +/- 0.2 min. Total energy expenditure was 0.64 +/- 0.04 MJ. Serum creatine kinase and ratings of perceived muscle soreness were significantly elevated on day 1 and peaked on day 2. Triacylglycerol total area under the curve was 12.1% lower on day 1 compared with C (7.51 +/- 0.99 vs. 8.54 +/- 1.07 mmol L(-1) 6h(-1), P < 0.02), whereas no difference existed between C and day 2. Serum insulin incremental area under the curve was significantly elevated on day 2 compared with C, indicating transient insulin resistance.

CONCLUSION

These results show that low-volume eccentric RE is effective in reducing postprandial triacylglycerol concentration despite the low energy expenditure. Muscle damage does not have a detrimental effect on PPL.

Genetic variation in the ADIPOR2 gene is associated with liver fat content and its surrogate markers in three independent cohorts

AIMS

We investigated whether polymorphisms in candidate genes involved in lipid metabolism and type 2 diabetes are related to liver fat content.

METHODS

Liver fat content was measured using proton magnetic resonance spectroscopy ((1)H-MRS) in 302 Finns, in whom single nucleotide polymorphisms (SNPs) in acyl-CoA synthetase long-chain family member 4 (ACSL4), adiponectin receptors 1 and 2 (ADIPOR1 and ADIPOR2), and the three peroxisome proliferator-activated receptors (PPARA, PPARD, and PPARG) were analyzed. To validate our findings, SNPs significantly associated with liver fat content were studied in two independent cohorts and related to surrogate markers of liver fat content.

RESULTS

In the Finnish subjects, polymorphisms in ACSL4 (rs7887981), ADIPOR2 (rs767870), and PPARG (rs3856806) were significantly associated with liver fat content measured with (1)H-MRS after adjusting for age, gender, and BMI. Anthropometric and circulating parameters were comparable between genotypes. In the first validation cohort of approximately 600 Swedish men, ACSL4 rs7887981 was related to fasting insulin and triglyceride concentrations, and ADIPOR2 rs767870 to serum gamma glutamyltransferase concentrations after adjusting for BMI. The SNP in PPARG (rs3856806) was not significantly associated with any relevant metabolic parameter in this cohort. In the second validation cohort of approximately 3000 subjects from Western Finland, ADIPOR2 rs767870, but not ACSL4 rs7887981 was related to fasting triglyceride concentrations.

CONCLUSIONS

Genetic variation, particularly in the ADIPOR2 gene, contributes to variation in hepatic fat accumulation in humans.

Beneficial effects of designed dietary fatty acid compositions on lipids in triacylglycerol-rich lipoproteins among Chinese patients with type 2 diabetes mellitus

Elevated levels of postprandial triacylglycerol-rich lipoproteins (ppTRLs) are atherogenic. Patients with type 2 diabetes mellitus (T2DM) have exaggerated postprandial lipemia associated with elevation or prolonged residence of ppTRL remnants. We examined whether dietary fatty acid compositions (DFACs) decrease atherogenic lipid profiles in ppTRL subfractions in T2DM Chinese patients. A single-blind randomized controlled trial was conducted among 28 T2DM patients. Patients consumed 1 of 3 standardized DFAC-specific fat meals: equidominant (1:1:1), polyunsaturated fatty acid (PUFA)-dominant (PUFA-D, 1:1.7:2.3), or monounsaturated fatty acid (MUFA)-dominant (MUFA-D, 1:1.7:1.2) meals. Numbers in parenthesis, respectively, represent the ratio of saturated fatty acids, MUFA, and PUFA to saturated fatty acids. The MUFA-D meal was the control. Triacylglycerol and cholesterol levels were measured in Svedberg flotation rate (S(f)) greater than 400, S(f) 60 to 400, S(f) 20 to 60, and S(f) 12 to 20 ppTRL subfractions at fasting (0 hour) and 2, 4, and 6 hours after the consumption of the fat meals. Effects of DFACs on mean concentrations of triacylglycerols and cholesterol averaged over 0, 2, 4, and 6 hours in ppTRL subfractions were assessed using linear mixed models. Stability and robustness were validated with 1000 bootstrap replicates. Contrasted to the control, equidominant meal reduced 6-hour average triacylglycerol levels in S(f) greater than 400 (P = .002, bootstrap P < .05) and S(f) 20 to 60 (P = .02, bootstrap P < .05) subfractions, and decreased average S(f) 20 to 60 cholesterol (P = .04, bootstrap P < .05); PUFA-D decreased S(f) greater than 400 average triacylglycerol levels (P = .09, bootstrap P < .05). Bootstrap samples suggested that PUFA-D decreased average S(f) 20 to 60 cholesterol levels (bootstrap P < .05). Therefore, modifying DFACs attenuates the atherogenic lipid profile of ppTRLs in T2DM patients; but increasing PUFA ratio may be more feasible.

Association between glucokinase regulatory protein (GCKR) and apolipoprotein A5 (APOA5) gene polymorphisms and triacylglycerol concentrations in fasting, postprandial, and fenofibrate-treated states

BACKGROUND

Hypertriglyceridemia is a risk factor for cardiovascular disease. Variation in the apolipoprotein A5 (APOA5) and glucokinase regulatory protein (GCKR) genes has been associated with fasting plasma triacylglycerol.

OBJECTIVE

We investigated the combined effects of the GCKR rs780094C-->T, APOA5 -1131T-->C, and APOA5 56C-->G single nucleotide polymorphisms (SNPs) on fasting triacylglycerol in several independent populations and the response to a high-fat meal and fenofibrate interventions.

DESIGN

We used a cross-sectional design to investigate the association with fasting triacylglycerol in 8 populations from America, Asia, and Europe (n = 7,730 men and women) and 2 intervention studies in US whites (n = 1,061) to examine postprandial triacylglycerol after a high-fat meal and the response to fenofibrate. We defined 3 combined genotype groups: 1) protective (homozygous for the wild-type allele for all 3 SNPs); 2) intermediate (any mixed genotype not included in groups 1 and 3); and 3) risk (carriers of the variant alleles at both genes).

RESULTS

Subjects within the risk group had significantly higher fasting triacylglycerol and a higher prevalence of hypertriglyceridemia than did subjects in the protective group across all populations. Moreover, subjects in the risk group had a greater postprandial triacylglycerol response to a high-fat meal and greater fenofibrate-induced reduction of fasting triacylglycerol than did the other groups, especially among persons with hypertriglyceridemia. Subjects with the intermediate genotype had intermediate values (P for trend <0.001).

CONCLUSIONS

SNPs in GCKR and APOA5 have an additive effect on both fasting and postprandial triacylglycerol and contribute to the interindividual variability in response to fenofibrate treatment.

Elevated levels of platelet microparticles in carotid atherosclerosis and during the postprandial state

BACKGROUND

Platelet microparticles (PMPs) possess proatherogenic and procoagulant properties which may play a role in atherogenesis and subsequent thromboembolic complications. The present study was conducted to investigate the possible relationship between carotid atherosclerosis and plasma concentrations of PMPs, and elucidate if plasma levels of PMPs were affected by postprandial hypertriglyceridemia.

METHODS AND RESULTS

Subjects with ultrasound-assessed carotid atherosclerotic plaques (echogenic; n=20 and echolucent; n=20), assessed by ultrasonography, and subjects without carotid plaques (n=20) were recruited from a population-based study and underwent a standard fat tolerance test. Subjects with carotid plaques had significantly higher levels of large PMPs than subjects without carotid atherosclerotic plaques (96.7+/-50.4 microg/l versus 56.1+/-34.9 microg/l), after adjustments for traditional cardiovascular risk factors and use cardiovascular drugs (p=0.021). Plasma PMPs were not associated with plaque echogenicity. Postprandial hypertriglyceridemia induced a similar increase in plasma PMPs within all groups. Significant correlations were found between an increase in plasma triglycerides and percent elevation in total PMPs (r=0.29, p<0.05) and large PMPs (r=0.34, p<0.01) in the postprandial phase.

CONCLUSIONS

Individuals with echogenic and echolucent carotid atherosclerotic plaques have statistically significant elevation of large plasma PMPs compared to age/sex-matched normal controls. Postprandial hypertriglyceridemia induces a significant, similar increase in plasma PMPs in individuals with and without carotid atherosclerotic plaques which could be of pathophysiological importance in atherogenesis.

ApoB100-LDL acts as a metabolic signal from liver to peripheral fat causing inhibition of lipolysis in adipocytes

Background

Free fatty acids released from adipose tissue affect the synthesis of apolipoprotein B-containing lipoproteins and glucose metabolism in the liver. Whether there also exists a reciprocal metabolic arm affecting energy metabolism in white adipose tissue is unknown.

Methods and Findings

We investigated the effects of apoB-containing lipoproteins on catecholamine-induced lipolysis in adipocytes from subcutaneous fat cells of obese but otherwise healthy men, fat pads from mice with plasma lipoproteins containing high or intermediate levels of apoB100 or no apoB100, primary cultured adipocytes, and 3T3-L1 cells. In subcutaneous fat cells, the rate of lipolysis was inversely related to plasma apoB levels. In human primary adipocytes, LDL inhibited lipolysis in a concentration-dependent fashion. In contrast, VLDL had no effect. Lipolysis was increased in fat pads from mice lacking plasma apoB100, reduced in apoB100-only mice, and intermediate in wild-type mice. Mice lacking apoB100 also had higher oxygen consumption and lipid oxidation. In 3T3-L1 cells, apoB100-containing lipoproteins inhibited lipolysis in a dose-dependent fashion, but lipoproteins containing apoB48 had no effect. ApoB100-LDL mediated inhibition of lipolysis was abolished in fat pads of mice deficient in the LDL receptor (Ldlr^−/−Apob^100/100).

Conclusions

Our results show that the binding of apoB100-LDL to adipocytes via the LDL receptor inhibits intracellular noradrenaline-induced lipolysis in adipocytes. Thus, apoB100-LDL is a novel signaling molecule from the liver to peripheral fat deposits that may be an important link between atherogenic dyslipidemias and facets of the metabolic syndrome.

Association of serum apolipoprotein B48 level with the presence of carotid plaque in type 2 diabetes mellitus

AIMS

The atherogenicity of chylomicron remnants has been discussed. We examined whether serum apoB48 level is associated with the presence of carotid plaque in type 2 diabetic patients.

METHOD

Forty type 2 diabetic patients (21 males and 19 females, 52.8+/-11.8 years old; mean+/-S.D.) were divided into two groups by the presence or absence of carotid plaque. The diurnal change of serum apoB48 level was measured by enzyme-linked immunosorbent assay.

RESULTS

Fasting serum apoB48 level was higher in the subjects with carotid plaque than those without (6.5+/-3.8vs. 4.1+/-1.9 microg/ml, p=0.01). Age- and gender-adjusted analysis showed that the presence of carotid plaque was associated with fasting apoB48 (OR 1.43; 95% CI, 1.07-2.09, p=0.04) and triglyceride (OR 1.14; 95% CI, 1.02-1.32, p=0.04) levels. In normal LDL-cholesterol (<140 mg/dl) subjects, the presence of carotid plaque was associated with fasting apoB48 level (OR 2.16; 95% CI, 1.22-5.32, p=0.04), but not associated with fasting triglyceride level (OR 1.11; 95% CI, 0.99-1.30, p=0.13).

CONCLUSIONS

Serum apoB48 level was strongly associated with the presence of carotid plaque in type 2 diabetic patients.

Dyslipidemia and glucose dysregulation in overweight and obese patients

Inactivity and a sedentary lifestyle contribute to overweight, obesity, and cardiometabolic risk. Overweight and obesity can lead to metabolic abnormalities, insulin resistance, type 2 diabetes mellitus (DM), lipid disorders, and cardiovascular disease. Diet and exercise can effectively reverse overweight and obesity and their related comorbidities. Modest weight loss (5%-10%) and modest physical activity (30 minutes a day) are first-line recommendations for the prevention of type 2 DM. Clinical trials have demonstrated that insulin sensitivity can be improved and type 2 DM can be prevented through lifestyle modification and pharmacologic therapy, including antiobesity drugs, antidiabetic drugs, statins, and antihypertensive drugs. The endocannabinoid system plays an important role in regulating metabolism through its effects on food intake at the level of the hypothalamus and on body composition through peripheral effects on adipose tissue.

Association of fasting and nonfasting serum triglycerides with cardiovascular disease and the role of remnant-like lipoproteins and small dense LDL

PURPOSE OF REVIEW

The magnitude of the contribution of serum triglycerides to cardiovascular disease risk and the mechanisms by which triglyceride-rich lipoproteins exert their effect on the vascular wall are largely unknown. Postprandial lipemia likewise has been linked to atherosclerosis, but large prospective studies assessing the magnitude of this association are also lacking. Hypertriglyceridemia is characterized by the presence of cholesterol-rich remnant-like lipoproteins and small dense LDL particles, both of which are believed to contribute to cardiovascular disease risk.

RECENT FINDINGS

Several large prospective cohort studies and a meta-analysis have been published recently, investigating the association of fasting and nonfasting serum triglycerides with cardiovascular disease. Fasting triglycerides increase the adjusted hazard ratios for cardiovascular disease risk 1.7 x (comparing upper with lower tertile), and nonfasting levels around 2.0 x. Measurement of nonfasting triglycerides may be more feasible and more informative, but standardization of a test meal is necessary. For clinical practice, the concentration of the atherogenic lipoprotein subfractions in hypertriglyceridemia may be reflected best by measuring apolipoprotein B.

SUMMARY

Nonfasting triglyceride levels may replace fasting levels in assessing cardiovascular disease risk once standard reference values have been developed. Several atherogenic lipoprotein subfractions can be measured by including apolipoprotein B in addition to HDL, (nonfasting) triglycerides and LDL cholesterol.

[The role of post-prandial lipids in atherogenesis: particularities of diabetes mellitus]

Atherosclerosis is a complex and multifactorial disease, which determines clinical events that cause significant morbidity-mortality, represented by acute myocardial infarction, angina and sudden death. It is associated with lipid disturbances, platelet activation, thrombosis, endothelial dysfunction, inflammation, oxidative stress, altered matrix metabolism, among other disturbances. All these abnormalities are usual and more pronounced in diabetic patients, as well as in the post-prandial state. Among the coronary artery disease risk factors that are not usually employed in clinical practice in the whole population, postprandial hyperlipemia plays a major role, being a possible early marker of metabolic abnormalities and vascular dysfunction not yet seen in the fasting state. Recent results showed that post-oral lipid overload changes are negatively associated with endothelial dysfunction, and vascular reactivity abnormalities are strongly related to atherosclerosis progression and cardiovascular events. These abnormalities could disclose a lipid intolerance state that can be detected in apparently healthy subjects even before fasting abnormalities are seen. This review will deal with the pathophysiology changes involved in post-prandial hyperlipemia and its relationship with atherogenesis, with particular emphasis to diabetes mellitus.

Postprandial lipaemia in patients with impaired fasting glucose, impaired glucose tolerance and diabetes mellitus

AIMS

To compare the postprandial lipid responses in subjects with prediabetes (IFG and IGT), newly detected diabetes mellitus (NDDM) and normal glucose tolerance (NGT).

METHODS

Postprandial lipid responses to a standard oral fat challenge was studied in forty-four subjects who were divided after an OGTT into NGT, pure impaired fasting glucose (PIFG), pure impaired glucose tolerance (PIGT) and NDDM.

RESULTS

There was a significantly higher postprandial triglyceride (PPTg) response with a higher PPTg area under curve (p=0.004) and peak PPTg levels (p=0.003) in patients with NDDM but not with either PIFG (p>0.05) or PIGT (p>0.05) when compared with NGT. Overall, PPTg responses correlated significantly with fasting plasma glucose (p=0.001) and 2h plasma glucose (p=0.001) but not with age, sex, body mass index, waist, or insulin resistance.

CONCLUSION

Subjects with newly detected diabetes mellitus displayed postprandial hypertriglyceridemia after a standard oral fat meal challenge while no such abnormality could be demonstrated in subjects with IFG or IGT. This defect is probably related to glycemic status and insulin resistance.

Fasting triglyceride is a major determinant of postprandial triglyceride response in postmenopausal women

OBJECTIVE

The purpose of the study was to examine the relative influences of fasting lipids, insulin resistance, and waist circumference (WC) on postprandial lipemia in postmenopausal women.

DESIGN

Forty-nine naturally postmenopausal women were recruited for the study. Each woman underwent a 75-g oral glucose tolerance test to measure insulin resistance and a 1,000-kcal high-fat mixed meal test for postprandial triglyceride (TG) response.

RESULTS

The participants were divided into three groups by tertiles of incremental TG response in the mixed meal test. The three groups were comparable in weight, WC, and fasting high-density lipoprotein cholesterol (HDL-C) levels. There were significant differences in fasting TG and non-HDL-C concentrations among the three groups. The women in the high-tertile group were more insulin resistant than those in the low-tertile group, indicated by higher homeostasis model assessment for insulin resistance (HOMA-IR) values. The postprandial TG response was significantly correlated with Log(fasting TG), fasting non-HDL-C and Log(HOMA-IR), but not with WC, in univariate regression analyses. Log(fasting TG) was the only variable that remained significantly related to incremental TG response when all the above were entered into multiple regression models. Subsequently, we found that Log(HOMA-IR) and fasting non-HDL-C independently predicted the variance of Log(fasting TG) in stepwise multiple regression.

CONCLUSIONS

Our data demonstrated that the fasting TG level is a major determinant of postprandial TG response in postmenopausal women. Insulin resistance and non-HDL-C may contribute independently to the fasting TG level. The influences of WC on postprandial lipemia seemed to be insignificant.