Postprandial Lipemia and Remnant Lipoproteins

The effect of lipid-lowering therapies on the pro-inflammatory and anti-inflammatory properties of vascular endothelial cells

Atherosclerosis and cardiovascular events can be prevented, or treated, using statin therapy, either alone or in combination with ezetimibe. Chronic inflammation, vascular proliferation, and the development of atherosclerosis are also influenced by 25-hydroxycholesterol (25-OHC). The aim of the study was to compare the direct pleiotropic effects of two commonly-used statins (atorvastatin, rosuvastatin), ezetimibe, and their combinations, on the mRNA expression of pro-inflammatory IL1β, IL-18 and IL-23 and anti-inflammatory TGFβ, IL-35 (EBI3, IL-12 subunits), IL-10 and IL-37, in endothelial cells damaged by 25-OHC. It also analyzed IL-35 expression at the protein level. HUVECs were stimulated with atorvastatin (5 μM), rosuvastatin (10 μM), ezetimibe (1.22 μM), atorvastatin-ezetimibe (5 μM + 1.22 μM) or rosuvastatin-ezetimibe (10 μM + 1.22 μM), with or without pre-incubation with 10 μg/mL 25-OHC. mRNA expression was analyzed by real-time PCR. The protein level of IL-35 was analyzed by ELISA. In the pre-stimulated HUVECs, atorvastatin and rosuvastatin decreased mRNA expression of IL1β, IL-18, IL-23, TGFβ, IL35 and increased mRNA expression of IL-10 and IL-37 compared to 25-OHC. Furthermore, only incubation with rosuvastatin and rosuvastatin-ezetimibe decreased IL-35 mRNA and protein levels. Ezetimibe down-regulated only IL1β. Treatment with rosuvastatin-ezetimibe and atorvastatin-ezetimibe reversed the effect of 25-OHC in IL1β, IL-18 and IL-35 mRNA expression. In conclusion, rosuvastatin has the strongest anti-inflammatory effects and is the best at reducing the effect of oxysterols. Both statins exert a greater anti-inflammatory effect than ezetimibe. The anti-inflammatory effect of the combination therapies appears to be based on the effects of the statins alone and not their combination with ezetimibe.

Localized activity attenuates the combined impact of a high fat meal and prolonged sitting on arterial stiffness: A randomized, controlled cross-over trial

Exposure to acute prolonged sitting and consumption of a high fat (HF) meal have been shown to independently and additively impair central and peripheral cardiovascular function. This study sought to determine whether localized activity, namely leg fidgeting, offers a protective effect to these deleterious effects. Using a randomized crossover design with three trials, 18 healthy males sat uninterrupted for 180 min following the consumption of a low fat (LF, trial 1) or HF meal (trial 2). The third trial consisted of a HF meal but sitting was interrupted with 1 min of leg fidgeting (isolated bilateral plantar flexion) consisting of -250 taps per min every 5 min for the 180 min duration. Carotid-femoral pulse wave velocity (cfPWV), aortic-femoral stiffness gradient (af-SG), superficial femoral blood flow, shear-rate and PWVβ, triglyceride concentrations and lower-limb venous pooling (HHb) were assessed pre and post sitting in all trials. General linear mixed model found that following the uninterrupted HF trial, there was a significant worsening of cfPWV (mean difference (MD) = 0.57 mˑs-1; d = 1.04) and the af-SG (MD = 0.14, d = 0.50), and femoral artery blood flow (MD = 18 mlˑmin-1; d = 0.48) and shear rate (MD = 15 S1; d = 0.67) decreased. However, leg fidgeting was enough to prevent the combined deleterious effects of prolonged sitting following a HF meal. As there were no significant changes in the LF trial, the HF meal maybe the predominant driver when uninterrupted sitting is combined with a HF meal.

Saturated Fatty Acids Consumed in Smoothies Increase Glucose and Metabolic Load Index in Young Adults Compared to Polyunsaturated Omega-3-Fatty Acids

Introduction: Chronic diets high in saturated fat (SF) and omega-6-fatty acids (O6FAs) elevate fasting triglycerides (TRGs) and glucose (GLU). Postprandial TRGs, GLU, and Metabolic Load Index (MLI) are better predictors of disease risk compared to fasting levels alone. Conversely, diets high in omega-3 fatty acids (O3FAs) may be cardioprotective. Unfortunately, many existing postprandial studies are not standardized to body weight and given in an amount individuals would typically consume in their daily lives; the MLI is not calculated, and varying types of fat content are not examined. Therefore, we sought to determine whether SF, O3FAs, or O6FAs altered postprandial TRGs, GLU, and MLI from a standardized mixed meal. Methods: Fifteen individuals (6 M and 9 F) visited the laboratory three times, separated by at least 48 h, to consume HFM smoothies with varying FA composition (SF, high O6FAs, and high O3FAs). The smoothies were standardized to 12 kcal/kg body weight, 63% total fat, and 0.72 g/kg sugar. TRGs and GLU were collected at baseline and at 2 h and 4 h postprandially; the MLI was calculated by summing the TRG and GLU responses at each time point. Results: There was a significant increase in TRGs across time points (p < 0.001). For TRGs, there was a trend toward a significant interaction between smoothie type and time (p = 0.06) due to the increase in TRGs in the SF compared to the O3FA smoothie. There was an increase in postprandial GLU that varied across smoothie types (p = 0.036). Taken together, the MLI was elevated in the SF smoothie compared to the O3FAs at 2 h (p = 0.041). Conclusion: A SF smoothie in the morning elevated the metabolic load compared to an O3FA smoothie. Mechanisms of action in the competing clearance of TRGs and GLU warrant further investigation.

Acute-phase glycoprotein profile responses to different oral macronutrient challenges: Influence of sex, functional hyperandrogenism and obesity

Acute-phase glycoprotein ¹H-NMR spectroscopy profiles serve as surrogate markers of chronic inflammation in metabolic disorders such as obesity, diabetes and polycystic ovary syndrome (PCOS). The latter is associated with increased height-to-width (H/W) ratios of GlycA and GlycB after fasting, but not to glycoprotein areas, regardless of obesity. We studied the responses to separate glucose, lipid and protein oral challenges of five glycoprotein variables (GlycA, GlycB, and GlycF areas and the GlycA and GlycB H/W ratios) in 17 women with PCOS, 17 control women, and 19 healthy men. Glucose and protein ingestion resulted into decreases in all glycoprotein variables, whereas lipid ingestion increased GlycA, GlycF and induced minimal changes in GlycB and GlycB H/W. We found no effects of obesity or group of subjects on postprandial glycoprotein variables regardless of the macronutrient being ingested. However, a statistically significant interaction indicated that obesity blunted the decrease in some of these variables in control women and men, whereas obese women with PCOS showed larger changes when compared with their non-obese counterparts. In conclusion, acute-phase glycoprotein profiles indicate an anti-inflammatory response during postprandial phase that is less pronounced after lipid ingestion, and is counteracted by the chronic inflammatory background associated with obesity and PCOS.

Postprandial dyslipidemia in insulin resistant states in adolescent populations

Obesity and the metabolic syndrome are becoming increasingly prevalent not only in adults, but also in adolescents. The metabolic syndrome, a complex cluster of metabolic abnormalities, increases one's risk of developing type 2 diabetes and cardiovascular disease (CVD). Dyslipidemia, a key component of the metabolic syndrome, is highly associated with insulin resistance and contributes to increased CVD risk. Dyslipidemia has traditionally been assessed using a fasting lipid profile [i.e. fasting triglycerides, total cholesterol, low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C)]. However, the postprandial state predominates over the course of a day and non-fasting triglycerides independently predict CVD risk. In insulin resistant states, the intestine overproduces triglyceride-rich lipoprotein (TRL) particles, termed chylomicrons (CMs), following ingestion of a fat-containing meal, as well as in the fasting state. Along with elevated hepatic TRLs (i.e. very-low density lipoproteins), CMs contribute to remnant lipoprotein accumulation, small dense LDL particles, and reduced HDL-C, which collectively increase CVD risk. Given the early genesis of atherosclerosis and physiological metabolic changes during adolescence, studying postprandial dyslipidemia in the adolescent population is an important area of study. Postprandial dyslipidemia in the pediatric population poses a significant public health concern, warranting a better understanding of its pathogenesis and association with insulin resistance and CVD. This review discusses the metabolic syndrome, focusing on the link between insulin resistance, postprandial dyslipidemia, and CVD risk. Furthermore, the clinical significance and functional assessment of postprandial dyslipidemia, specifically in the adolescent population, is discussed in more detail.

Sex differences in postprandial responses to different dairy products on lipoprotein subclasses: a randomised controlled cross-over trial

Men have earlier first-time event of CHD and higher postprandial TAG response compared with women. The aim of this exploratory sub-study was to investigate if intake of meals with the same amount of fat from different dairy products affects postprandial lipoprotein subclasses differently in healthy women and men. A total of thirty-three women and fourteen men were recruited to a randomised controlled cross-over study with four dairy meals consisting of butter, cheese, whipped cream or sour cream, corresponding to 45 g of fat (approximately 60 energy percent). Blood samples were taken at 0, 2, 4 and 6 h postprandially. Lipoprotein subclasses were measured using NMR and analysed using a linear mixed model. Sex had a significant impact on the response in M-VLDL (P=0·04), S-LDL (P=0·05), XL-HDL (P=0·009) and L-HDL (P=0·001) particle concentration (P), with women having an overall smaller increase in M-VLDL-P, a larger decrease in S-LDL-P and a larger increase in XL- and L-HDL-P compared with men, independent of meal. Men showed a decrease in XS-VLDL-P compared with women after intake of sour cream (P<0·01). In men only, XS-VLDL-P decreased after intake of sour cream compared with all other meals (v. butter: P=0·001; v. cheese: P=0·04; v. whipped cream: P=0·006). Meals with the same amount of fat from different dairy products induce different postprandial effects on lipoprotein subclass concentrations in men and women.

Single Triglyceride-Rich Meal Destabilizes Barrier Functions and Initiates Inflammatory Processes of Endothelial Cells

Postprandial hypertriglyceridemia is an independent risk factor for cardiovascular disease. The aim of this study was to assess the effects of a single fat-rich meal on barrier functions and inflammatory status on human umbilical vascular endothelial cells (HUVECs), furthermore we assess the effects of mixture of palmitic acid and 25-hydroxycholesterol (PA +25OHCH) on integrity of endothelial cells and their inflammatory properties. HUVECs were induced with serum of healthy volunteers taken before, and 3 h after, the consumption of a meal with a standardized daily required dose of fats. In addition, endothelial cells were induced with PA +25OHCH (800 μM/L+10 μg/mL). Total cholesterol, triglycerides (TGs), high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, high sensitivity c-reactive protein, and glucose were measured at fasting and postprandially. HUVEC integrity was measured in the RTCA-DP xCELLigence system. mRNA expression of interleukin (IL)-33, IL-32, intercellular adhesion molecule-1 (ICAM-1), monocyte chemoattractant protein-1 (MCP-1), CX3C-chemokine, vascular endothelial growth factor (VEGF) occludin, and VE-cadherin was analyzed by real-time polymerase chain reaction. Viability and apoptosis were assessed in flow cytometry. The level of VEGF and IL-33 in fasting and postprandial serum was assessed by enzyme-linked immunosorbent assay (ELISA). Three hours after consumption of a fatty meal, all patients displayed increased levels of TGs and Toll-like receptors (110 ± 37 mg/dL versus 182 ± 64 mg/dL P < 0.05) (24 ± 11 mg/dL versus 42 ± 14 mg/dL P < 0.05). Postprandial serum and PA +25OHCH caused >20% decrease of HUVEC integrity than fasting serum (P < 0.001). HUVEC disintegration was accompanied by a decrease of occludin mRNA expression as compared with fasting serum (P < 0.05). The fatty meal affected neither VE-cadherin mRNA expression nor its apoptosis (P > 0.05). Mixture of PA +25OHCH caused decrease of VE-cadherin mRNA expression as compared with fasting serum (P < 0.01). PA +25OHCH did not affect HUVEC apoptosis (P > 0.05). Postprandial serum and PA +25OHCH caused increase of IL-33, MCP-1, ICAM-1, IL-32, VEGF, and CX3C-chemokine mRNA expression as compared with fasting serum (P < 0.05). Moreover, level of VEGF in fatty serum was significantly higher (P < 0.001). Postprandial lipemia after a single fatty meal may destabilize the endothelial barrier and initiate inflammatory processes.

Two-Hour Postprandial Lipoprotein Particle Concentration Differs Between Lean and Obese Individuals

The concentrations of lipoprotein particles [high-density lipoproteins (HDLs), low-density lipoproteins (LDLs), very-low-density lipoproteins (VLDLs), and chylomicrons] are associated with the risk of cardiovascular diseases. Most studies have examined these associations in the fasting state. Previous studies have shown lipoprotein particle concentration change following meal, and these changes are different in individuals with obesity. In this study, we aimed to assess whether various meal compositions lead to adverse short-term (2-h) postprandial lipoproteinemia in obese insulin resistant (obese-IR) subjects as compared to lean insulin sensitive (lean-IS) subjects. In a randomized crossover trial, nine lean-IS and nine obese-IR Chinese men aged 22–35 years were challenged with isoenergetic and isovolumic meals rich in protein (HP), fat (HF), or carbohydrate (HC). Plasma samples were collected after a 10-h fast, as well as 1-h and 2-h post-meal and analyzed using nuclear magnetic resonance. Plasma concentration of large VLDLs and chylomicron particles was higher and increased more after all meals in obese-IR compared to lean-IS subjects. The HP meal decreased small LDL particle concentration in obese-IR subjects, and increased small HDL particle concentration in all subjects. The HF meal led to a decrease in small HDL concentration in all subjects. In conclusion, obese-IR subjects revealed a detrimental response to meal challenges even as early as 2-h after meal intake.

AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS AND AMERICAN COLLEGE OF ENDOCRINOLOGY GUIDELINES FOR MANAGEMENT OF DYSLIPIDEMIA AND PREVENTION OF CARDIOVASCULAR DISEASE

OBJECTIVE

The development of these guidelines is mandated by the American Association of Clinical Endocrinologists (AACE) Board of Directors and American College of Endocrinology (ACE) Board of Trustees and adheres with published AACE protocols for the standardized production of clinical practice guidelines (CPGs).

METHODS

Recommendations are based on diligent reviews of the clinical evidence with transparent incorporation of subjective factors, according to established AACE/ACE guidelines for guidelines protocols.

RESULTS

The Executive Summary of this document contains 87 recommendations of which 45 are Grade A (51.7%), 18 are Grade B (20.7%), 15 are Grade C (17.2%), and 9 (10.3%) are Grade D. These detailed, evidence-based recommendations allow for nuance-based clinical decision-making that addresses multiple aspects of real-world medical care. The evidence base presented in the subsequent Appendix provides relevant supporting information for Executive Summary Recommendations. This update contains 695 citations of which 203 (29.2 %) are EL 1 (strong), 137 (19.7%) are EL 2 (intermediate), 119 (17.1%) are EL 3 (weak), and 236 (34.0%) are EL 4 (no clinical evidence).

CONCLUSION

This CPG is a practical tool that endocrinologists, other health care professionals, health-related organizations, and regulatory bodies can use to reduce the risks and consequences of dyslipidemia. It provides guidance on screening, risk assessment, and treatment recommendations for a range of individuals with various lipid disorders. The recommendations emphasize the importance of treating low-density lipoprotein cholesterol (LDL-C) in some individuals to lower goals than previously endorsed and support the measurement of coronary artery calcium scores and inflammatory markers to help stratify risk. Special consideration is given to individuals with diabetes, familial hypercholesterolemia, women, and youth with dyslipidemia. Both clinical and cost-effectiveness data are provided to support treatment decisions.

ABBREVIATIONS

4S = Scandinavian Simvastatin Survival Study A1C = glycated hemoglobin AACE = American Association of Clinical Endocrinologists AAP = American Academy of Pediatrics ACC = American College of Cardiology ACE = American College of Endocrinology ACS = acute coronary syndrome ADMIT = Arterial Disease Multiple Intervention Trial ADVENT = Assessment of Diabetes Control and Evaluation of the Efficacy of Niaspan Trial AFCAPS/TexCAPS = Air Force/Texas Coronary Atherosclerosis Prevention Study AHA = American Heart Association AHRQ = Agency for Healthcare Research and Quality AIM-HIGH = Atherothrombosis Intervention in Metabolic Syndrome With Low HDL/High Triglycerides trial ASCVD = atherosclerotic cardiovascular disease ATP = Adult Treatment Panel apo = apolipoprotein BEL = best evidence level BIP = Bezafibrate Infarction Prevention trial BMI = body mass index CABG = coronary artery bypass graft CAC = coronary artery calcification CARDS = Collaborative Atorvastatin Diabetes Study CDP = Coronary Drug Project trial CI = confidence interval CIMT = carotid intimal media thickness CKD = chronic kidney disease CPG(s) = clinical practice guideline(s) CRP = C-reactive protein CTT = Cholesterol Treatment Trialists CV = cerebrovascular CVA = cerebrovascular accident EL = evidence level FH = familial hypercholesterolemia FIELD = Secondary Endpoints from the Fenofibrate Intervention and Event Lowering in Diabetes trial FOURIER = Further Cardiovascular Outcomes Research with PCSK9 Inhibition in Subjects With Elevated Risk trial HATS = HDL-Atherosclerosis Treatment Study HDL-C = high-density lipoprotein cholesterol HeFH = heterozygous familial hypercholesterolemia HHS = Helsinki Heart Study HIV = human immunodeficiency virus HoFH = homozygous familial hypercholesterolemia HPS = Heart Protection Study HPS2-THRIVE = Treatment of HDL to Reduce the Incidence of Vascular Events trial HR = hazard ratio HRT = hormone replacement therapy hsCRP = high-sensitivity CRP IMPROVE-IT = Improved Reduction of Outcomes: Vytorin Efficacy International Trial IRAS = Insulin Resistance Atherosclerosis Study JUPITER = Justification for the Use of Statins in Primary Prevention: An Intervention Trial Evaluating Rosuvastatin LDL-C = low-density lipoprotein cholesterol Lp-PLA2 = lipoprotein-associated phospholipase A2 MACE = major cardiovascular events MESA = Multi-Ethnic Study of Atherosclerosis MetS = metabolic syndrome MI = myocardial infarction MRFIT = Multiple Risk Factor Intervention Trial NCEP = National Cholesterol Education Program NHLBI = National Heart, Lung, and Blood Institute PCOS = polycystic ovary syndrome PCSK9 = proprotein convertase subtilisin/kexin type 9 Post CABG = Post Coronary Artery Bypass Graft trial PROSPER = Prospective Study of Pravastatin in the Elderly at Risk trial QALY = quality-adjusted life-year ROC = receiver-operator characteristic SOC = standard of care SHARP = Study of Heart and Renal Protection T1DM = type 1 diabetes mellitus T2DM = type 2 diabetes mellitus TG = triglycerides TNT = Treating to New Targets trial VA-HIT = Veterans Affairs High-Density Lipoprotein Cholesterol Intervention Trial VLDL-C = very low-density lipoprotein cholesterol WHI = Women's Health Initiative.

Meals with Similar Fat Content from Different Dairy Products Induce Different Postprandial Triglyceride Responses in Healthy Adults: A Randomized Controlled Cross-Over Trial

BACKGROUND

Postprandial lipemia is a risk factor for cardiovascular disease. Dairy products differ in nutrient content and food matrix, and little is known about how different dairy products affect postprandial triglyceride (TG) concentrations.

OBJECTIVE

We investigated the effect of meals with similar amounts of fat from different dairy products on postprandial TG concentrations over 6 h in healthy adults.

METHODS

A randomized controlled cross-over study was performed on 47 subjects (30% men), with median (25th-75th percentile) age of 32 (25-46) y and body mass index of 23.6 (21.0-25.8) kg/m2. Meals included 1 of butter, cheese, whipped cream, or sour cream, corresponding to 45 g of fat (approximately 60 energy%). Serum concentrations of TGs (primary outcome), and total cholesterol (TC), low density lipoprotein cholesterol (LDL cholesterol), high density lipoprotein cholesterol (HDL cholesterol), insulin, glucose, non-esterified fatty acids, and plasma glucose-dependent insulinotropic polypeptide (secondary outcomes) were measured before the meal and 2, 4, and 6 h postprandially. Incremental AUC (iAUC) was calculated for the responses, and data were analyzed using a linear mixed model.

RESULTS

Sour cream induced a 61% larger TG-iAUC0-6 h compared to whipped cream (P < 0.001), a 53% larger TG-iAUC0-6 h compared to butter (P < 0.001), and a 23% larger TG-iAUC0-6 h compared to cheese (P = 0.05). No differences in TG-iAUC0-6 h between the other meals were observed. Intake of sour cream induced a larger HDL cholesterol-iAUC0-6 h compared to cheese (P = 0.01). Intake of cheese induced a 124% larger insulin iAUC0-6 h compared to butter (P = 0.006). No other meal effects were observed.

CONCLUSIONS

High-fat meals containing similar amount of fat from different dairy products induce different postprandial effects on serum TGs, HDL cholesterol, and insulin in healthy adults. The potential mechanisms and clinical impact of our findings remain to be further elucidated. The study was registered at www.clinicaltrials.gov as NCT02836106.

Olive oil and postprandial hyperlipidemia: implications for atherosclerosis and metabolic syndrome

Olive oil is the primary source of fat in the Mediterranean diet, which is associated with a significant improvement in health status, as measured by reduced mortality from several chronic diseases. The current pandemic of obesity, metabolic syndrome, and type 2 diabetes is intimately associated with an atherogenic dyslipidemic phenotype. The core components of the dyslipidemia of the metabolic syndrome, which most likely initiate atherosclerosis, are the "lipid triad" consisting of high plasma triglycerides, low levels of high-density lipoproteins, and a preponderance of small, dense low-density lipoproteins at fasting. However, postprandial (non-fasting) TGs (postprandial hyperlipidemia) are also recognized as an important component for atherosclerosis. Herein, the purpose of this review was to provide an update on the effects and mechanisms related to olive oil on postprandial hyperlipidemia and its implications for the onset and progression of atherosclerosis and metabolic syndrome.

Epigenome-wide association study of triglyceride postprandial responses to a high-fat dietary challenge

Postprandial lipemia (PPL), the increased plasma TG concentration after consuming a high-fat meal, is an independent risk factor for CVD. Individual responses to a meal high in fat vary greatly, depending on genetic and lifestyle factors. However, only a few loci have been associated with TG-PPL response. Heritable epigenomic changes may be significant contributors to the unexplained inter-individual PPL variability. We conducted an epigenome-wide association study on 979 subjects with DNA methylation measured from CD4⁺ T cells, who were challenged with a high-fat meal as a part of the Genetics of Lipid Lowering Drugs and Diet Network study. Eight methylation sites encompassing five genes, LPP, CPT1A, APOA5, SREBF1, and ABCG1, were significantly associated with PPL response at an epigenome-wide level (P < 1.1 × 10⁻⁷), but no methylation site reached epigenome-wide significance after adjusting for baseline TG levels. Higher methylation at LPP, APOA5, SREBF1, and ABCG1, and lower methylation at CPT1A methylation were correlated with an increased TG-PPL response. These PPL-associated methylation sites, also correlated with fasting TG, account for a substantially greater amount of phenotypic variance (14.9%) in PPL and fasting TG (16.3%) when compared with the genetic contribution of loci identified by our previous genome-wide association study (4.5%). In summary, the epigenome is a large contributor to the variation in PPL, and this has the potential to be used to modulate PPL and reduce CVD.

Effects of a Plant Sterol or Stanol Enriched Mixed Meal on Postprandial Lipid Metabolism in Healthy Subjects

Background

Evidence is increasing that plant sterols and stanols not only lower fasting serum low-density lipoprotein concentrations, but also those of triglycerides (TG). Insight into effects of these components on postprandial TG metabolism, an emerging risk factor for cardiovascular disease, is missing.

Objective

Our objective was to examine the 8-hour postprandial response after consuming plant sterol or stanol enriched margarine as part of a mixed meal.

Methods

This postprandial study was part of a randomized crossover study in which 42 subjects consumed plant sterol enriched (3 g/d plant sterols), plant stanol enriched (3 g/d plant stanols), and control margarines for 4 weeks. After each period, subjects consumed a shake enriched with 3g plant sterols (sterol period), 3g plant stanols (stanol period) or no addition (control period). Subjects received a second shake with no addition after 4 hours.

Results

TG and apoB48 incremental areas under the curves (iAUC) of the total (0-8h) and 1^st meal response (0-4h) were comparable between the meals and in all age categories (I:18-35y, II:36-52y, III:53-69y). In subjects aged 53-69y, TG iAUC after the 2^nd meal (4-8h) was higher in the stanol period as compared with the sterol (63.1±53.0 mmol/L/min; P < 0.01) and the control period (43.2±52.4 mmol/L/min; P < 0.05). ApoB48 iAUC after the 2^nd meal was higher after the stanol than after the sterol period (67.1±77.0 mg/L/min; P < 0.05) and tended to be higher than after the control period (43.1±64.5 mg/L/min; P = 0.08) in subjects aged 53-69y. These increased postprandial responses may be due to reduced lipoprotein lipase activity, since postprandial apoCIII/II ratios were increased after stanol consumption compared with the control meal.

Conclusion

Postprandial TG and apoB48 responses are age-dependently increased after plant stanol consumption, which might be related to a changed clearance of triglyceride-rich lipoproteins.

Trial Registration

ClinicalTrials.gov NCT01559428

Assessment of postprandial triglycerides in clinical practice: Validation in a general population and coronary heart disease patients

BACKGROUND

Previous studies have suggested that for clinical purposes, subjects with fasting triglycerides (TGs) between 89-180 mg/dl (1-2 mmol/l) would benefit from postprandial TGs testing.

OBJECTIVE

To determine the postprandial TG response in 2 independent studies and validate who should benefit diagnostically from an oral-fat tolerance test (OFTT) in clinical practice.

METHODS

A population of 1002 patients with coronary heart disease (CHD) from the CORDIOPREV clinical trial and 1115 white US subjects from the GOLDN study underwent OFTTs. Subjects were classified into 3 groups according to fasting cut points of TGs to predict the usefulness of OFTT: (1) TG < 89 mg/dl (<1 mmol/l); (2) TG, 89-180 mg/dl (1-2 mmol/l); and (3) TG > 180 mg/dl (>2 mmol/l). Postprandial TG concentration at any point > 220 mg/dl (>2.5 mmol/l) has been pre-established as an undesirable postprandial response.

RESULTS

Of the total, 49% patients with CHD and 42% from the general population showed an undesirable response after the OFTT. The prevalence of undesirable postprandial TG in the CORDIOPREV clinical trial was 12.8, 50.3, and 89.7%, in group 1, 2, and 3, respectively (P < .001) and 11.2, 58.1, and 97.5% in group 1, 2, and 3, respectively (P < .001) in the GOLDN study.

CONCLUSIONS

These two studies validate the predictive values reported in a previous consensus. Moreover, the findings of the CORDIOPREV and GOLDN studies show that an OFTT is useful to identify postprandial hyperlipidemia in subjects with fasting TG between 1-2 mmol/l (89-180 mg/dL), because approximately half of them have hidden postprandial hyperlipidemia, which may influence treatment. An OFTT does not provide additional information regarding postprandial hyperlipidemia in subjects with low TG (<1 mmol/l, <89 mg/dL) or increased TG (>2 mmol/l, >180 mg/dl).

Effects of prandial challenge on triglyceridemia, glycemia, and pro-inflammatory activity in persons with chronic paraplegia

CONTEXT/OBJECTIVE

Exaggerated postprandial lipemia has been reported after spinal cord injury (SCI). We examined metabolite and accompanying pro-inflammatory biomarker responses to repeat feeding of typical high-fat meals in individuals with chronic paraplegia.

DESIGN

Descriptive trial.

METHODS

Metabolites (triglycerides, glucose, and insulin) and inflammatory biomarkers (interleukin-6 and high-sensitivity C-reactive protein (hsCRP)) were measured under fasting conditions in 11 recreationally active individuals with chronic (>1 year) paraplegia. Subjects received high-fat meals at time point 0 and again at minute 240. Antecubital venous blood was obtained at time points -30 (fasting), 0 (first meal), 30, 60, 90, 120, 240 (second meal), 360, and 480 minutes. Correlations were examined among the study variables. Exploratory subgroup analysis was performed for subjects with levels of postprandial glucose greater than >200 mg/dl.

RESULTS

Triglycerides showed a significant rise 4 hours after eating. Basal inflammatory markers were elevated, and did not undergo additional change during the testing. Additionally, subjects with excessive postprandial glucose responses showed higher hsCRP levels than those having typical glucose responses both for fasting (11.8 ± 6.5 vs. 2.9 ± 2.7 mg/l, P = 0.064) and postprandial (11.1 ± 4.9 vs. 3.7 ± 3.8 mg/l, P = 0.018) values.

CONCLUSIONS

Despite elevations in metabolic response markers, inflammatory markers did not change significantly after consumption of population-representative (i.e. hypercaloric) mixed-nutrient meals. Levels of fasting CRP in the high-risk range are consistent with other reports in persons with SCI and continue to pose concern for their cardiovascular disease risk. The possible association between postprandial metabolic responses and inflammatory states warrants further investigation to identify individual component risks for this secondary health hazard.

Postprandial lipemia as a cardiometabolic risk factor

High levels of fasting circulating triglycerides (TG) represent an independent risk factor for cardiovascular disease. In western countries, however, people spend most time in postprandial conditions, with continuous fluctuation of lipemia due to increased levels of TG-rich lipoproteins (TRLs), including chylomicrons (CM), very low density lipoproteins (VLDL), and their remnants. Several factors contribute to postprandial lipid metabolism, including dietary, physiological, pathological and genetic factors. The presence of coronary heart disease, type 2 diabetes, insulin resistance and obesity is associated with higher postprandial TG levels compared with healthy conditions; this association is present also in subjects with normal fasting TG levels. Increasing evidence indicates that impaired metabolism of postprandial lipoproteins contributes to the pathogenesis of coronary artery disease, suggesting that lifestyle modifications as well as pharmacological approaches aimed at reducing postprandial TG levels might help to decrease the cardiovascular risk.

Risk prediction with triglycerides in patients with stable coronary disease on statin treatment

BACKGROUND

The aim of the prospective Homburg Cream and Sugar study was to analyze the role of fasting and postprandial serum triglycerides (TG) as risk modifiers in patients with coronary artery disease (CAD).

METHODS AND RESULTS

A sequential oral triglyceride and glucose tolerance test was developed to obtain standardized measurements of postprandial TG kinetics and glucose in 514 consecutive patients with stable CAD confirmed by angiography (95% were treated with a statin). Fasting and postprandial TG predicted the primary outcome measure of cardiovascular death and hospitalizations after 48 months follow-up (fasting TG >150 vs. <106 mg/dl: Hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.31-2.45, p = 0.0001; area under the curve >1120 vs. <750 mg/dl/5 hr: HR 1.78, 95% CI 1.29-2.45, p = 0.0003). Parameters of the postprandial TG increase did not improve risk prediction compared to fasting TG. The number of cardiovascular deaths and myocardial infarctions was higher in the upper tertile of fasting TG (HR 1.79, 95%-CI 1.04-3.09, p = 0.03). Risk prediction by TG was independent of traditional risk factors, medication, glucose metabolism, LDL- and HDL-cholesterol. Total cholesterol, LDL- and HDL-cholesterol concentrations were not associated with the primary outcome.

CONCLUSIONS

Fasting serum triglycerides >150 mg/dl independently predict cardiovascular events in patients with coronary artery disease on guideline-recommended medication. Assessment of postprandial TG does not improve risk prediction compared to fasting TG in these patients.

Postprandial interleukin-6 response in elderly with abdominal obesity and metabolic syndrome

OBJECTIVE

The aim of this study is to evaluate the contribution of central obesity to inflammatory responses in the postprandial state in elderly patients with and without metabolic syndrome (MetS).

MATERIAL/METHODS

We evaluated 80 elderly individuals who were distributed into three groups: MetS, abdominal obesity (AbObes) and Control, according to ATPIII criteria. Interleukin-6 (IL-6) serum concentration was measured at 0, 2, 4 and 6 hours after the ingestion of a physiological meal without an overload of fat.

RESULTS

Serum IL-6 increased 6 hours after the meal in all of the groups (P<0.001). Comparing the groups, there was no difference in the area under the curve (AUC) of IL-6 in the postprandial state. There was a correlation between the 6-hour changes in the concentrations of IL-6 and the homeostasis model assessment of insulin resistance (HOMA-IR) (r = 0.25, P<0.05).

CONCLUSION

In this study, differences in abdominal circumference (AC) have not determined a different behavior of IL-6 in the postprandial state, despite the correlation between AC and IL-6. However, we found that, in the elderly, there is a rise in serum IL-6 at 6 hours.

Why, when and how should hypertriglyceridemia be treated in the high-risk cardiovascular patient?

Recent epidemiology attests that hypertriglyceridemia may be a causal risk factor for cardiovascular disease (CVD). The specific atherogenicity of hypertriglyceridemia relates to the accumulation in plasma of triglyceride-rich lipoprotein remnants. Hypertriglyceridemia also drives a 'global' atherogenic dyslipidemic profile, which is frequent in high-risk cardiovascular patients, such as Type 2 diabetics. Elevated triglyceride in fasting or nonfasting blood samples should be a trigger for assessing atherogenic components of the lipid profile, particularly HDL-cholesterol, non-HDL-cholesterol and apoB. Residual risk of CVD remains high in statin-treated diabetic patients owing to persistent atherogenic dyslipidemia, which is not fully corrected by these agents nor by the addition of ezetimibe. Hypertriglyceridemia may then be targeted with niacin, fibrates or n-3 fatty acids, after correcting aggravating factors, especially obesity and hyperglycemia. Fibrates consistently decrease coronary events in dyslipidemic patients in outcome studies. New evidence supports adding fenofibrate to a statin in Type 2 diabetics with residual hypertriglyceridemia and low HDL-cholesterol; extrapolating from a recent meta-analysis, a 15% reduction in triglycerides could translate into a further 15% reduction in coronary events. Ongoing clinical trials may provide new evidence for adding niacin to a statin. The value of higher doses of n-3 fatty acids in reducing CVD risk remains to be demonstrated. The high triglyceride/low HDL nexus is an under-recognized risk factor for CVD that merits more detailed clinical assessment and treatment, particularly in patients with Type 2 diabetes already receiving a statin.

High-fat meal effect on LDL, HDL, and VLDL particle size and number in the Genetics of Lipid-Lowering Drugs and Diet Network (GOLDN): an interventional study

Background

Postprandial lipemia (PPL) is likely a risk factor for cardiovascular disease but these changes have not been well described and characterized in a large cohort. We assessed acute changes in the size and concentration of total and subclasses of LDL, HDL, and VLDL particles in response to a high-fat meal. Participants (n = 1048) from the Genetics of Lipid-Lowering Drugs and Diet Network (GOLDN) Study who ingested a high-fat meal were included in this analysis. Lipids were measured at 0 hr (fasting), 3.5 hr, and 6 hr after a standardized fat meal. Particle size distributions were determined using nuclear magnetic resonance spectroscopy. Analyses were stratified by baseline triglycerides (normal vs. elevated) and gender. The effect of PPL on changes in lipoprotein subclasses was assessed using repeated measures ANOVA.

Results

Postprandially, LDL-C, HDL-C, VLDL-C, and triglycerides increased regardless of baseline triglyceride status, with the largest increases in VLDL-C and TG; however, those with elevated triglycerides demonstrated larger magnitude of response. Total LDL particle number decreased over the 6-hour time interval, mostly from a decrease in the number of small LDL particles. Similarly, total VLDL particle number decreased due to reductions in medium and small VLDL particles. Large VLDL particles and chylomicrons demonstrated the largest increase in concentration. HDL particles demonstrated minimal overall changes in total particle number.

Conclusions

We have characterized the changes in LDL and VLDL particle number, and their subclass patterns following a high-fat meal.

Daytime triglyceride variability in men and women with different levels of triglyceridemia

BACKGROUND

Triglyceride (TG) levels measured in either the fasting or non-fasting state predict the risk of cardiovascular disease (CVD). Since CVD risk assessment is affected by variability in TG, the aim of the study was to investigate intra-individual variability of non-fasting TG.

METHODS

Capillary triglyceride (cTG) levels were measured in 246 free-living individuals at six time-points during the day on three separate occasions. Intra-individual variability in cTG was assessed by calculating the standard deviation of three measures at each time-point. Subjects were analyzed by gender and by fasting TG level.

RESULTS

In the fasting state, intra-individual variability was similar in males and females (0.28 and 0.35 mmol/l, respectively), but increased significantly in male but not in female subjects during the day, i.e., 0.28 to 0.69, and 0.35 to 0.36 mmol/l, resp. Subjects with higher fasting TG levels had greater absolute variability in both fasting and non-fasting TG.

CONCLUSIONS

The variability in non-fasting TG is greater in males and in individuals with higher levels of TG. Since greatest variability in non-fasting TG occurs very late in the day, it is unlikely to affect the assessment of CVD risk, which is based on a blood sample taken during daylight hours.

Influence of a fat overload on lipogenic regulators in metabolic syndrome patients

Several epidemiological studies have related an increase of lipids in the postprandial state to an individual risk for the development of CVD, possibly due to the increased plasma levels of TAG and fatty acids (FA) through enzymes of FA metabolism. The interaction between nutrition and the human genome determines gene expression and metabolic response. The aim of the present study was to evaluate the influence of a fat overload on the gene mRNA levels of lipogenic regulators in peripheral blood mononuclear cells (PBMC) from patients with the metabolic syndrome. The study included twenty-one patients with criteria for the metabolic syndrome who underwent a fat overload. Measurements were made before and after the fat overload of anthropometric and biochemical variables and also the gene mRNA levels of lipogenic factors. The main results were that the fat overload led to an increased mRNA levels of sterol regulatory element binding protein-1 (SREBP1), retinoid X receptor α (RXRα) and liver X receptor α (LXRα) in PBMC, and this increase was associated with the FA synthase (FASN) mRNA levels. We also found that TAG levels correlated with FASN mRNA levels. In addition, there was a positive correlation of SREBP1 with RXRα and of LXRα with the plasma lipoperoxide concentration. The fat overload led to an increase in regulators of lipogenesis in PBMC from patients with the metabolic syndrome.

Assessment of the Accutrend GCT and PTS CardioChek meters to measure blood triglyceride concentrations in cats

Point-of-care (POC) meters that determine whole blood triglyceride (TG) concentrations are used in human medicine to monitor both fasting and post-prandial TG concentrations. The aim of this study was to evaluate their performance for determining feline TG concentrations. A total of 116 venous blood samples were collected from 55 cats. TG concentrations were measured in whole blood using two meters: the Accutrend glucose cholesterol triglyceride (GCT) (GCT: Roche Diagnostics) and PTS CardioChek (PTS - Polymer Technology Systems), and results compared to those determined by a National Association of Testing Authorities (NATA) accredited veterinary laboratory. The GCT was not suitable for use in cats with normal TG concentrations (<0.9 mmol/l), as it overestimated almost 80% of the values; however, this device performed better with TG concentrations between 0.9 and 2.0 mmol/l. The PTS meter performed well in cats with normal TG concentrations, correctly classifying 90% of values as 'normal', and fairly well with TG concentrations <2.0 mmol/l. The PTS meter could be used to determine whether cats have normal fasting TG concentrations or predict mild elevations in serum TG, whereas the GCT meter can only be used to predict cats with elevated TG concentrations. Although both meters have limitations in determining some TG concentrations, the PTS in particular, could be used as a screening tool to distinguish normal cats to those with hypertriglyceridaemia.

Cell-mediated lipoprotein transport: a novel anti-atherogenic concept

Lipoprotein transport is thought to occur in the plasma compartment of the blood, where lipoproteins are modulated by various enzymatic reactions. Subsequently, lipoproteins can migrate through the endothelial barrier to the subendothelial space or are taken up by the liver. The interaction between pro-atherogenic (apoB-containing) lipoproteins and blood cells (especially monocytes and macrophages) in the subendothelial space is well known. This lipoprotein-inflammatory cell interplay is central in the development of the atherosclerotic plaque. In this review, a novel interaction is described between lipoproteins and both leukocytes and erythrocytes in the blood compartment. This lipoprotein-blood cell interaction may also be related to the process of atherosclerosis by inducing inflammatory changes in the case of leukocytes (pro-atherogenic) and as an anti-atherogenic transport-system by adherence to erythrocytes. Triglyceride rich lipoprotein (TRL)-mediated leukocyte activation can lead to an inflammatory situation with generation of oxidative stress and the production of cytokines, ultimately resulting in acute endothelial dysfunction. Binding of apoB containing lipoproteins to erythrocytes may be a potential anti-atherogenic mechanism protecting the vessel wall from the pro-inflammatory effects of these lipoproteins and also playing a role in the removal of these particles from the circulation. One of the proposed mechanisms of this interaction implies complement activation on the lipoprotein surface and binding to the Complement Receptor 1 (CR1) on erythrocytes and leukocytes, followed by clearance by the liver.

Methods to assess impaired post-prandial metabolism and the impact for early detection of cardiovascular disease risk

Post-prandial lipaemia has emerged as a key contributor to cardiovascular disease (CVD) risk and progression. Specifically, delayed clearance of chylomicrons (CM) and their remnants increase the delivery of triglyceride and cholesteryl ester to the vessel wall and can accelerate the progression of atherosclerosis, which may be particularly pertinent to individuals with insulin resistance and/or obesity. As the number of studies linking post-prandial metabolism and chronic disease increases, interest has grown in the use of parameters reflecting CM metabolism as a possible indicator of early CVD risk. This, in turn has raised the question of what method might be most appropriate to detect CM and their remnants in plasma accurately. However, the handful of techniques able to measure CM metabolism (triglyceride-rich lipoprotein fractions; remnant-lipoprotein cholesterol; retinyl esters, CM-like emulsion; sodium dodecyl sulphate-polyacrylamide gel electrophoresis; immunoblotting, enzyme-linked immunoabsorbent assays; C(13) breath test; capillary finger prick) differ in their specificity, cost and applicability in research and in the clinical setting. In this review, we explore the scientific and clinical implications of CM methodology to better understand early risk assessment of CVD. We raise ongoing issues of the need to appreciate differential separation of very low-density lipoprotein and CM fractions, as well as to identify the technical basis for imprecision between assays for apolipoprotein B48. We also highlight emerging issues with respect to the practicality of measuring post-prandial metabolism in large clinical studies and offer opinions on the appropriateness of existing techniques in this field.

Triglycerides and coronary heart disease: have recent insights yielded conclusive answers?

PURPOSE OF REVIEW

Despite over 50 years of research, the relevance of triglycerides to coronary heart disease risk remains uncertain.

RECENT FINDINGS

Contrary to prevailing views, recent studies demonstrate that the long-term within-individual variability of triglyceride measurements is similar to that of other lipid fractions. Several prospective studies have reported on associations of circulating triglyceride levels with coronary heart disease risk, but it remains unclear whether observed associations are dependent on levels of conventional risk factors (especially other lipids) or are importantly modified under different circumstances (especially by fasting status). Ongoing large-scale studies should help clarify such outstanding uncertainties and assess whether measurement of triglyceride levels can better identify individuals at increased risk of coronary heart disease than measurement of conventional risk factors alone. Available interventions that lower levels of triglycerides are unable to judge causality as such interventions typically influence levels of several lipid fractions. Study of genetic variants that regulate triglyceride levels may provide an alternative approach to assess causality.

SUMMARY

Although recent studies have progressed our understanding of triglycerides and coronary heart disease, several outstanding uncertainties remain unresolved. Ongoing studies should help clarify these, including whether measurement of triglyceride levels can help improve coronary heart disease risk assessment, and study of genetic variants may help better understand any causal role.

Triglyceride response following an oral fat tolerance test in Burmese cats, other pedigree cats and domestic crossbred cats

Primary lipid disorders causing fasting triglyceridaemia have been documented infrequently in Burmese cats. Due to the known increased risk of diabetes mellitus and sporadic reports of lipid aqueous in this breed, the aim of this study was to determine whether healthy Burmese cats displayed a more pronounced pre- or post-prandial triglyceridaemia compared to other cats. Serum triglyceride (TG) concentrations were determined at baseline and variably at 2, 4 and 6h after ingestion of a high-fat meal (ie, an oral fat tolerance test) in a representative sample of Burmese and non-Burmese cats. The median 4 and 6h serum TG concentrations were significantly higher in Burmese cats (4h - 2.8mmol/l; 6h - 8.2mmol/l) than in other pedigree and domestic crossbred cats (4h - 1.5mmol/l; 6h - 1.0mmol/l). The non-Burmese group had post-prandial TG concentrations ranging from 0.6 to 3.9mmol/l. Seven Burmese cats had post-prandial TG concentrations between 6.6 and 19.0mmol/l, five had concentrations between 4.2 and 4.7mmol/l, while the remaining 15 had post-prandial concentrations between 0.5 and 2.8mmol/l. None of these Burmese cats had fasting triglyceridaemia. Most Burmese cats with a 4 h TG > 6.0 mmol/l had elevated fasting very low density lipoprotein (VLDL) concentrations. This study demonstrates that a proportion of Burmese cats in Australia have delayed TG clearance compared to other cats. The potential repercussions of this observation with reference to lipid aqueous, pancreatitis and diabetes mellitus in Burmese cats are discussed.

The differential effects of thiazolidindiones on atherogenic dyslipidemia in type 2 diabetes: what is the clinical significance?

BACKGROUND

Diabetic dyslipidemia is typically characterized by an increase in plasma triglycerides, a decrease in high-density lipoprotein cholesterol and a concomitant increase in atherogenic small dense low-density lipoproteins. Thiazolidindiones are able to lower the levels of fasting glucose and glycated hemoglobin significantly by improving insulin sensitivity, as well as improving some aspects of diabetic dyslipidemia: total cholesterol, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol tend to increase while triglycerides are generally decreased.

OBJECTIVE

This paper reviewed the effects of pioglitazone and rosiglitazone on atherogenic diabetic dyslipidemia, in particular on small dense low-density lipoprotein particles.

METHODS

A literature search (by Medline and Scopus) was performed up to 15 March 2008. The authors also manually reviewed the references of selected articles for any pertinent material.

RESULTS

Pioglitazone showed an additional beneficial effect on triglycerides, high-density lipoprotein cholesterol and the levels of small dense low-density lipoprotein compared to rosiglitazone.

CONCLUSIONS

Since recent studies have suggested that these agents may also have a differential effect on long-term cardiovascular end-points despite similar improvements in glycated hemoglobin and insulin sensitivity, the different impact on atherogenic diabetic dyslipidemia may help to explain these findings.

Novel aspects of postprandial lipemia in relation to atherosclerosis

Postprandial hyperlipidemia is considered to be a substantial risk factor for atherosclerosis. Interestingly, this concept has never been supported by randomized clinical trials. The difficulty lies in the fact that most interventions aimed to reduce postprandial lipemia, will also affect LDL-C levels. The atherogenic mechanisms of postprandial lipids and lipoproteins can be divided into direct lipoprotein-mediated and indirect effects; the latter, in part, by inducing an inflammatory state. Elevations in postprandial triglycerides (TG) have been related to the increased expression of postprandial leukocyte activation markers, up-regulation of pro-inflammatory genes in endothelial cells and involvement of the complement system. This set of events is part of the postprandial inflammatory response, which is one of the recently identified potential pro-atherogenic mechanisms of postprandial lipemia. Especially, complement component 3 levels show a close correlation with postprandial lipemia and are also important determinants of the metabolic syndrome. In clinical practice, fasting TG are frequently used as reflections of postprandial lipemia due to the close correlation between the two. The use of serial capillary measurements in an out-of-hospital situation is an alternative for oral fat loading tests. Daylong TG profiles reflect postprandial lipemia and are increased in conditions like the metabolic syndrome, type 2 diabetes and atherosclerosis. Studies are needed to elucidate the role of postprandial inflammation in atherogenesis and to find new methods in order to reduce selectively the postprandial inflammatory response. Future studies are needed to find new methods in order to reduce selectively the postprandial inflammatory response.

Intestinal lipoprotein overproduction in insulin-resistant states

PURPOSE OF REVIEW

Excessive postprandial lipemia is highly prevalent in obese and insulin-resistant/type 2 diabetic individuals and substantially increases the risk of atherosclerosis and cardiovascular disease. This article will review our current understanding of the link between insulin resistance and intestinal lipoprotein overproduction and highlight some of the key recent findings in the field.

RECENT FINDINGS

Emerging evidence from several animal models of insulin resistance as well as insulin-resistant humans clearly supports the link between insulin resistance and aberrant intestinal lipoprotein metabolism. In insulin-resistant states, elevated free fatty acid flux into the intestine, downregulation of intestinal insulin signaling and upregulation of microsomal triglyceride transfer protein all appear to stimulate intestinal lipoprotein production. Gut peptides, GLP-1 and GLP-2, may be important regulators of intestinal lipid absorption and lipoprotein production.

SUMMARY

Available evidence in humans and animal models strongly favors the concept that the small intestine is not merely an absorptive organ but rather plays an active role in regulating the rate of production of triglyceride-rich lipoproteins. Metabolic signals in insulin resistance and type 2 diabetes and in some cases an aberrant intestinal response to these factors all contribute to the enhanced formation and secretion of triglyceride-rich lipoproteins.

Influence of postprandial triglyceride-rich lipoproteins on lipid-mediated gene expression in smooth muscle cells of the human coronary artery

AIMS

Postprandial triglyceride-rich lipoproteins (TRL) have a direct effect on vascular smooth muscle cells (SMC) and they increase the risk of atherogenesis. Here, we have tested the hypothesis that the different fatty acid composition of TRL is capable of differentially modifying gene expression in human coronary artery SMC (CASMC). In addition, the effect of TRL on cell proliferation and transcription factor activation was also evaluated.

METHODS AND RESULTS

TRL were prepared from plasma of healthy volunteers after the ingestion of meals enriched in refined olive oil (ROO), butter or a mixture of vegetable and fish oils (VEFO). We use cDNA microarrays to determine the genes differentially expressed in TRL-treated CASMC. Correspondence cluster analysis demonstrated that TRL-butter, -ROO and -VEFO provoked different transcriptional profiles in CASMC. Sixty-six genes were regulated by TRL-butter, 55 by -ROO, and 47 by -VEFO. The data revealed that TRL-butter predominantly activated genes involved in the regulation of cell proliferation and inflammation. Likewise, TRL-VEFO induced the expression of genes implicated in inflammation, while TRL-ROO promoted a less atherogenic gene profile.

CONCLUSION

The pathophysiological contribution of TRL to the development of atherosclerosis and the stability of atherosclerotic plaques may depend on the fatty acid composition of TRL. Our findings suggest a role for macrophage-inhibiting cytokine-1 (MIC-1) in coronary artery cardiovascular events.