Remnant lipoproteins as therapeutic targets

Remnant Cholesterol is More Strongly Associated with Arterial Stiffness than Traditional Lipids and Lipid Ratios in the General Chinese Population

AIM

Studies on the relationship between remnant cholesterol (RC) and arterial stiffness (AS) are limited. This study aims to investigate the relationship between RC and AS and to explore RC, total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides (TG), non-HDL-C, LDL-C/HDL-C, TG/HDL-C, lipoprotein combine index (LCI), and TC/HDL-C, which are lipid parameters most strongly associated with AS.

METHODS

A total of 4653 participants from the REACTION (Risk Evaluation of Cancers in Chinese Diabetic Individuals) study were recruited. AS was defined as a brachial-ankle pulse wave velocity of ≥ 1400 cm/s. Multiple logistic regression analyses were performed to detect its association with lipid parameters (RC, TG, TC, HDL-C, LDL-C, non-HDL-C, LDL-C/HDL-C, TG/HDL-C, LCI, and TC/HDL-C).

RESULTS

Logistic regression analysis showed that compared with other traditional or non-traditional lipid parameters, the association between RC and AS was the strongest (odds ratio (OR) 1.59, 95% confidence interval (CI) 1.30-1.95, P＜0.001). In the stratified analysis, RC was significantly associated with AS in both sexes and at any age, as well as blood glucose, blood pressure, and body mass index levels. Besides, RC and AS were still significantly associated when TG＜1.7 mmol/L (OR:1.58, 95% CI: 1.02-2.45, P=0.04), LDL-C ＜3.4 mmol/L (OR:1.32, 95% CI: 1.01-1.73, P=0.041), HDL-C ≥ 1.0 mmol/L (OR:1.67, 95% CI: 1.34-2.08, P＜0.001), or non-HDL-C＜4.1 mmol/L (OR: 1.42, 95% CI: 1.10-1.82, P=0.007) are controlled within the appropriate range.

CONCLUSION

In conclusion, compared with traditional lipids and lipid ratios, RC is more strongly associated with AS. The association between RC and AS remains significant even when TG, LDL-C, HDL-C, or non-HDL-C levels are controlled within the appropriate range.

Postprandial Hyperlipidemia: Its Pathophysiology, Diagnosis, Atherogenesis, and Treatments

Postprandial hyperlipidemia showing postprandial increases in serum triglyceride (TG) is associated with the development of atherosclerotic cardiovascular disease (ASCVD). To diagnose postprandial hyperlipidemia, the oral fat loading test (OFLT) should be performed; however, this test is very time-consuming and is difficult to perform. Elevated serum TG levels reflect an increase in TG-rich lipoproteins (TRLs), such as chylomicrons (CM), very low-density lipoproteins (VLDL), and their remnants (CM remnants [CMRs] and VLDL remnants [VLDLRs]). Understanding of elevation in CMR and/or VLDLR can lead us to understand the existence of postprandial hyperlipidemia. The measurement of apo B48, which is a constituent of CM and CMR; non-fasting TG, which includes TG content in all lipoproteins including CM and CMR; non-high-density lipoprotein cholesterol (non-HDL-C), which includes TRLs and low-density lipoprotein; and remnant cholesterol are useful to reveal the existence of postprandial hyperlipidemia. Postprandial hyperlipidemia is observed in patients with familial type III hyperlipoproteinemia, familial combined hyperlipidemia, chronic kidney disease, metabolic syndrome and type 2 diabetes. Postprandial hyperlipidemia is closely related to postprandial hyperglycemia, and insulin resistance may be an inducing and enhancing factor for both postprandial hyperlipidemia and postprandial hyperglycemia. Remnant lipoproteins and metabolic disorders associated with postprandial hyperlipidemia have various atherogenic properties such as induction of inflammation and endothelial dysfunction. A healthy diet, calorie restriction, weight loss, and exercise positively impact postprandial hyperlipidemia. Anti-hyperlipidemic drugs such pemafibrate, fenofibrate, bezafibrate, ezetimibe, and eicosapentaenoic acid have been shown to improve postprandial hyperlipidemia. Anti-diabetic drugs including metformin, alpha-glucosidase inhibitors, pioglitazone, dipeptidyl-peptidase-4 inhibitors and glucagon-like peptide 1 analogues have been shown to ameliorate postprandial hyperlipidemia. Although sodium glucose cotransporter-2 inhibitors have not been proven to reduce postprandial hyperlipidemia, they reduced fasting apo B48 and remnant lipoprotein cholesterol. In conclusion, it is important to appropriately understand the existence of postprandial hyperlipidemia and to connect it to optimal treatments. However, there are some problems with the diagnosis for postprandial hyperlipidemia. Postprandial hyperlipidemia cannot be specifically defined by measures such as TG levels 2 h after a meal. To study interventions for postprandial hyperlipidemia with the outcome of preventing the onset of ASCVD, it is necessary to define postprandial hyperlipidemia using reference values such as IGT.

Measurement of Serum Low Density Lipoprotein Cholesterol and Triglyceride-Rich Remnant Cholesterol as Independent Predictors of Atherosclerotic Cardiovascular Disease: Possibilities and Limitations

The serum low density lipoprotein cholesterol (LDL-C) concentration is the dominant clinical parameter to judge a patient's risk of developing cardiovascular disease (CVD). Recent evidence supports the theory that cholesterol in serum triglyceride-rich lipoproteins (TRLs) contributes significantly to the atherogenic risk, independent of LDL-C. Therefore, combined analysis of both targets and adequate treatment may improve prevention of CVD. The validity of TRL-C calculation is solely dependent on the accuracy of the LDL-C measurement. Direct measurement of serum LDL- C is more accurate than established estimation procedures based upon Friedewald, Martin-Hopkins, or Sampson equations. TRL-C can be easily calculated as total C minus high density lipoprotein C (HDL-C) minus LDL-C. Enhanced serum LDL-C or TRL-C concentrations require different therapeutic approaches to lower the atherogenic lipoprotein C. This review describes the different atherogenic lipoproteins and their possible analytical properties and limitations.

Elevated Remnant Cholesterol is Associated with Adverse Cardiovascular Outcomes in Patients with Acute Coronary Syndrome

AIMS

This study aimed to investigate the association of elevated RC levels with adverse cardiovascular outcomes in acute coronary syndrome (ACS) patients with and without diabetes.

METHODS

We analyzed data from 1716 patients with ACS undergoing percutaneous coronary intervention. RC was calculated as total cholesterol minus high-density lipoprotein cholesterol minus low-density lipoprotein cholesterol. RC ＞75th percentile of the cohort (＞0.79 mmol/L) was defined as abnormally elevated RC. Cox-regression models and Kaplan-Meier analyses were used to assess the relationship between RC ＞0.79 mmol/L and major adverse cardiovascular events (MACE).

RESULTS

During a median follow-up of 927 days, a total of 354 patients had at least one event. In the overall population, compared with those with RC ≤ 0.79 mmol/L, patients with RC ＞0.79 mmol/L had a significantly higher risk of MACE after adjustment for potential confounders (hazard ratio: 1.572, 95% confidence interval: 1.251-1.975, P＜0.001). In addition, RC ＞0.79 mmol/L was associated with an increased risk of MACE of 66.7% (P=0.001) and 50.1% (P=0.022) in the diabetic and non-diabetic subgroups (P for interaction=0.073), respectively. The addition of RC significantly improved the predictive ability of baseline models for MACE in diabetic patients (all P＜0.05), but not in non-diabetic patients (all P＞0.05).

CONCLUSION

Abnormally elevated RC was significantly associated with worse prognosis in both diabetic and non-diabetic patients with ACS; however, the prognostic value of RC might be superior among diabetic patients.

Remnant lipoprotein particles and cardiovascular disease risk

Intravascular catabolism of chylomicrons and very low-density lipoproteins (VLDLs) gives rise to a spectrum of partially lipolyzed remnant particles. Their plasma levels and properties are influenced by lipases, lipid transfer proteins, and content of exchangeable lipoproteins. Particularly important among the latter are apoE, which mediates hepatic binding and uptake of remnants, and apoCIII, which can retard this process. In the course of their plasma transit, remnants can acquire pathologic properties that promote the development of atherosclerotic cardiovascular disease (ASCVD) including increased cholesterol content and transport of thrombogenic and inflammatory mediators. Levels of cholesterol-enriched remnant particles determined by various analytic techniques have been significantly linked to the incidence of ASCVD, most dramatically in dyslipidemic patients homozygous for the apoE2 genetic isoform. Further research is warranted for development of clinical assays that can better capture the pathologic impact of remnant lipoprotein subspecies, and for testing the impact on ASCVD of therapies that reduce their levels.

Postprandial dyslipidemia after a standardized high-fat meal in BMI-matched healthy individuals, and in subjects with prediabetes or type 2 diabetes

BACKGROUND & AIMS

A relationship between postprandial hyperlipidemia and glucose homeostasis/cardiovascular diseases has been suggested. We investigated postprandial plasma lipid patterns after a standardized high-fat meal and their association with glucose homeostasis and subclinical atherosclerosis.

METHODS

Using matching by BMI, 32 healthy individuals with normal glucose tolerance (NGT), 21 subjects with impaired glucose tolerance (IGT), and 20 subjects with drug-naïve type 2 diabetes (T2D) were enrolled. Plasma concentrations of triglycerides (TGs), apolipoprotein-B (ApoB), ApoB48, ApoB100, glucose, and insulin at baseline and 1, 2, 3, 4, 5, 6, and 8 h after a standardized meal (1041.03 kcal with 70.99 g of fat) were measured. Body composition, abdominal visceral fat area, and resting energy expenditure (REE) were measured using dual energy X-ray absorptiometry, computed tomography, and indirect calorimetry, respectively. The intima-media thickness (IMT) of the carotid artery and the ankle-brachial index (ABI) were used to detect subclinical atherosclerosis.

RESULTS

Baseline data and area under the curve (AUC) of plasma concentrations of TGs, ApoB, and ApoB48 in the IGT and T2D groups were higher than in the NGT group. The peak TG concentrations after the meal was observed at 5 h in subjects with IGT and T2D, while healthy subjects showed the highest concentrations at 4 h. In multivariable analysis, high abdominal visceral fat area and low HDL-cholesterol concentrations were independently associated with the AUC_TG and AUC_ApoB after adjusting for confounders including baseline TG and the REE. High LDL-cholesterol and high HbA1c concentrations were also associated with the AUC_ApoB. Furthermore, high AUC_TG and AUC_ApoB values were independent factors for an increased carotid IMT and a low ABI after adjusting for relevant variables.

CONCLUSIONS

Abdominal visceral obesity and low HDL-cholesterol concentrations were associated with increased post load excursions of TGs and ApoB in this series. These elevated concentrations of TGs and ApoB were linked with subclinical atherosclerosis.

Triglyceride-rich lipoproteins and their remnants: metabolic insights, role in atherosclerotic cardiovascular disease, and emerging therapeutic strategies-a consensus statement from the European Atherosclerosis Society

Recent advances in human genetics, together with a large body of epidemiologic, preclinical, and clinical trial results, provide strong support for a causal association between triglycerides (TG), TG-rich lipoproteins (TRL), and TRL remnants, and increased risk of myocardial infarction, ischaemic stroke, and aortic valve stenosis. These data also indicate that TRL and their remnants may contribute significantly to residual cardiovascular risk in patients on optimized low-density lipoprotein (LDL)-lowering therapy. This statement critically appraises current understanding of the structure, function, and metabolism of TRL, and their pathophysiological role in atherosclerotic cardiovascular disease (ASCVD). Key points are (i) a working definition of normo- and hypertriglyceridaemic states and their relation to risk of ASCVD, (ii) a conceptual framework for the generation of remnants due to dysregulation of TRL production, lipolysis, and remodelling, as well as clearance of remnant lipoproteins from the circulation, (iii) the pleiotropic proatherogenic actions of TRL and remnants at the arterial wall, (iv) challenges in defining, quantitating, and assessing the atherogenic properties of remnant particles, and (v) exploration of the relative atherogenicity of TRL and remnants compared to LDL. Assessment of these issues provides a foundation for evaluating approaches to effectively reduce levels of TRL and remnants by targeting either production, lipolysis, or hepatic clearance, or a combination of these mechanisms. This consensus statement updates current understanding in an integrated manner, thereby providing a platform for new therapeutic paradigms targeting TRL and their remnants, with the aim of reducing the risk of ASCVD.

Remnant lipoproteins: are they equal to or more atherogenic than LDL?

PURPOSE OF REVIEW

To critically appraise new insights into the biology of remnant lipoproteins and their putative role in the pathophysiology of atherosclerotic cardiovascular disease, and to compare the atherogenicity of remnant particles with that of low-density lipoproteins (LDL).

RECENT FINDINGS

New in-vivo stable isotope tracer studies of the kinetics of apoB48 and apoB100-containing lipoproteins in postprandial conditions have revealed that apoB48-containing very low-density lipoproteins (VLDL) accumulated markedly in hypertriglyceridemic patients. These intestinally-derived particles were cleared slowly, and represented up to 25% of circulating VLDL; as part of the remnant particle population, they may increase cardiovascular risk. Importantly, the PCSK9 inhibitor, evolocumab, was shown to reduce remnant levels (-29%) during the postprandial period in diabetic patients on statin therapy - an effect which may be additive to that of LDL-cholesterol reduction in conferring cardiovascular benefit. In recent Mendelian randomization studies, the effect of lowering triglyceride-rich lipoproteins or LDL-cholesterol translated to similar clinical benefit per unit of apoB. Finally, in randomized trials involving statin-treated patients with atherosclerotic cardiovascular disease, remnant cholesterol levels were associated with coronary atheroma progression independently of LDL-cholesterol.

SUMMARY

Overall, data from observational studies in large cohorts, Mendelian randomization studies, meta-regression analyses, and post-hoc analyses of randomized trials are consistent with the contention that remnants are highly atherogenic particles and contribute to the atherosclerotic burden in an equivalent manner to that of LDL.

Effects of Moderate Chronic Food Restriction on the Development of Postprandial Dyslipidemia with Ageing

Ageing is a major risk factor for the development of metabolic disorders linked to dyslipidemia, usually accompanied by increased adiposity. The goal of this work was to investigate whether avoiding an excessive increase in adiposity with ageing, via moderate chronic food restriction (FR), ameliorates postprandial dyslipidemia in a rat model of metabolic syndrome associated with ageing. Accordingly, we performed an oral lipid loading test (OLLT) in mature middle-aged (7 months) and middle-old-aged (24 months) Wistar rats fed ad libitum (AL) or under moderate FR for 3 months. Briefly, overnight fasted rats were orally administered a bolus of extra-virgin olive oil (1 mL/Kg of body weight) and blood samples were taken from the tail vein before fat load (t = 0) and 30, 60, 90, 120, 180, and 240 min after fat administration. Changes in serum lipids, glucose, insulin, and glucagon levels were measured at different time-points. Expression of liver and adipose tissue metabolic genes were also determined before (t = 0) and after the fat load (t = 240 min). Postprandial dyslipidemia progressively increased with ageing and this could be associated with hepatic ChREBP activity. Interestingly, moderate chronic FR reduced adiposity and avoided excessive postprandial hypertriglyceridemia in 7- and 24-month-old Wistar rats, strengthening the association between postprandial triglyceride levels and adiposity. The 24-month-old rats needed more insulin to maintain postprandial normoglycemia; nevertheless, hyperglycemia occurred at 240 min after fat administration. FR did not alter the fasted serum glucose levels but it markedly decreased glucagon excursion during the OLLT and the postprandial rise of glycemia in the 24-month-old rats, and FGF21 in the 7-month-old Wistar rats. Hence, our results pointed to an important role of FR in postprandial energy metabolism and insulin resistance in ageing. Lastly, our data support the idea that the vWAT might function as an ectopic site for fat deposition in 7-month-old and in 24-month-old Wistar rats that could increase their browning capacity in response to an acute fat load.

Association between different lipid parameters and aortic stiffness: clinical and therapeutic implication perspectives

INTRODUCTION

Recommendations about lipid parameters varied from different guidelines. Aortic stiffness is a marker of vascular aging and may reflect occurrence of cardiovascular diseases. Aortic pulse wave velocity (PWV), a marker of aortic stiffness, can be measured by applanation tonometry. The purpose of our study was to test the associations between lipid parameters and aortic stiffness.

METHODS

A cross-sectional study was conducted from 2012 to 2017, 603 participants were included: 517 patients and 86 'healthy' individuals used to calculate the theoretical PWV. Lipid parameters, including total cholesterol, triglycerides, low-density lipoprotein (LDL), high-density lipoprotein (HDL), non-HDL, total cholesterol/HDL ratio, triglycerides/HDL ratio and LDL/HDL ratio were measured. Theoretical PWV can be calculated according to age, sex, mean blood pressure and heart rate, allowing to form an individual PWV index [(measured PWV - theoretical PWV)/theoretical PWV]. PWV index [(measured PWV -  theoretical PWV)/theoretical PWV] greater than 0 defined aortic stiffness.

RESULTS

In multiple linear regression analyses, total cholesterol (P = 0.03), LDL (P = 0.04), non-HDL (P = 0.03), total cholesterol/HDL (P = 0.01) and LDL/HDL (P = 0.03) were significantly correlated with PWV. In multiple logistic regression analyses, non-HDL [OR = 1.12 (1.04-1.20), P = 0.01, R value: 0.224], total cholesterol/HDL [OR = 1.12 (1.02-1.22), P = 0.03, R value: 0.219] and total cholesterol [OR = 1.11 (1.01-1.23), P = 0.03, R value: 0.209] were significantly associated with aortic stiffness.

CONCLUSION

Non-HDL, total cholesterol and total cholesterol/HDL were significantly associated with aortic stiffness than others and especially individually lipid parameters. This result should be considered in future clinical lipid-lowering trials.

A randomized, double blind, placebo controlled, multicenter clinical trial to assess the efficacy and safety of Emblica officinalis extract in patients with dyslipidemia

BACKGROUND

Dyslipidemia is one of the most frequently implicated risk factors for development of atherosclerosis. This study evaluated the efficacy of amla (Emblica officinalis) extract (composed of polyphenols, triterpenoids, oils etc. as found in the fresh wild amla fruit) in patients with dyslipidemia.

METHODS

A total of 98 dyslipidemic patients were enrolled and divided into amla and placebo groups. Amla extract (500 mg) or a matching placebo capsule was administered twice daily for 12 weeks to the respective group of patients. The patients were followed up for 12 weeks and efficacy of study medication was assessed by analyzing lipid profile. Other parameters evaluated were apolipoprotein B (Apo B), apolipoprotein A1 (Apo A1), Coenzyme Q10 (CoQ10), high-sensitive C-reactive protein (hsCRP), fasting blood sugar (FBS), homocysteine and thyroid stimulating hormone (TSH).

RESULTS

In 12 weeks, the major lipids such as total cholesterol (TC) (p = 0.0003), triglyceride (TG) (p = 0.0003), low density lipoprotein cholesterol (LDL-C) (p = 0.0064) and very low density lipoprotein cholesterol (VLDL-C) (p = 0.0001) were significantly lower in amla group as compared to placebo group. Additionally, a 39% reduction in atherogenic index of the plasma (AIP) (p = 0.0177) was also noted in amla group. The ratio of Apo B to Apo A1 was reduced more (p = 0.0866) in the amla group as compared to the placebo. There was no significant change in CoQ10 level of amla (p = 0.2942) or placebo groups (p = 0.6744). Although there was a general trend of FBS reduction, the numbers of participants who may be classified as pre-diabetes and diabetes groups (FBS > 100 mg/dl) in the amla group were only 8. These results show that the amla extract used in the study is potentially a hypoglycaemic as well. However, this needs reconfirmation in a larger study.

CONCLUSIONS

The Amla extract has shown significant potential in reducing TC and TG levels as well as lipid ratios, AIP and apoB/apo A-I in dyslipidemic persons and thus has scope to treat general as well as diabetic dyslipidemia. A single agent to reduce cholesterol as well as TG is rare. Cholesterol reduction is achieved without concomitant reduction of Co Q10, in contrast to what is observed with statins.

TRIAL REGISTRATION

Registered with Clinical Trials Registry- India at www.ctri.nic.in (Registration number: CTRI/2015/04/005682 ) on 8 April 2015 (retrospectively registered).

Comparison of various lipid parameters in association of target organ damage: a cohort study

BACKGROUND

Recommendations of non-HDL amplification varied from different guidelines. We aim to test the relationships between various lipid parameters and target organ damage (TOD) including aortic stiffness, peripheral arterial disease and chronic kidney disease in a community-based elderly cohort.

METHODS

1599 (aged 71.4 ± 6.1 years) participants were recruited. Eight lipid parameters, including total cholesterol (TC), triglycerides (TG), LDL-C, HDL-C, non-HDL-C, TC/HDL ratio, TG/HDL ratio and LDL/HDL ratio, together with other plasma biomarkers like creatinine were measured. Pulse wave velocity (PWV) was measured by the SphygmoCor device, and ankle-brachial index (ABI) was assessed by Omron VP-1000 device.

RESULTS

Four individual lipid parameters (TC, TG, LDL-C and HDL-C) significantly correlated with most, but not all, TOD indices. Meanwhile, 4 combined lipid parameters, namely non-HDL-C, TC/HDL, TG/HDL and LCL/HDL, significantly correlated with all TOD (P ≤ 0.033). In multiple linear regression analyses, 4 combined lipid parameters also significantly associated with TOD (P ≤ 0.027), while none of individual lipid parameters significantly associated with all TOD indices. In multiple logistic regression analyses, only non-HDLC and TC/HDL significantly associated with TOD (P ≤ 0.039), and other lipid parameters did not significantly associate with TOD.

CONCLUSION

In an elderly community sample, non-HDLC and TC/HDLC were better associated with TOD than other lipid parameters. This finding should be considered in future clinical lipid-lowing therapy.

TRIAL REGISTRATION

This trial was retrospectively registered in ClinicalTrials.gov (No. NCT02368938 , registered on 15 Feb 2015).

Hypothesis: Postprandial remnant lipoproteins are the causal factors that induce the insulin resistance associated with obesity

We have long thought that remnant lipoproteins (RLP) in plasma are significantly increased as the result of disturbed lipoprotein metabolism followed by obesity and insulin resistance. Therefore, it was believed that insulin resistance causes and enhances RLP formation. In contrast, this hypothesis states that RLP induces insulin resistance as the result of obesity associated with the excessive fat intake. The majority of plasma TG increased after fat intake is TG in RLP (RLP-TG) and the majority of postprandial RLP is VLDL remnants, not CM remnants. RLP is newly formed lipoproteins primarily for energy supply against starvation, like blood sugar after carbohydrate intake. Since RLP bearing apoE, LPL and Lp(a) function as ligands for the VLDL receptor, RLP interacts with the VLDL receptor in visceral fat adipocytes and stored as TG similar to excessive blood sugar. However, the excessive VLDL remnants induces obesity and its associated insulin resistance, which plays a major role as the initiator of metabolic domino effects, similar to blood sugar primarily serving as an energy supply to protect against starvation.

Postprandial remnant lipoproteins as targets for the prevention of atherosclerosis

PURPOSE OF REVIEW

Oxidized low-density lipoprotein (Ox-LDL) and chylomicron remnants were previously proposed as the most atherogenic lipoproteins for the causal lipoproteins of atherosclerosis. However, there are still controversies on these hypothesizes. Therefore, we have proposed a new hypothesis based on our recent findings of remnant lipoproteins (RLPs) in postprandial plasma.

RECENT FINDINGS

Plasma RLP-C and RLP-TG increased significantly after fat load. More than 80% of the increased triglycerides after fat load consisted of the triglycerides in RLP, which contained greater amount of apoB100 than apoB48 particles as mostly very low density lipoproteins (VLDL) remnants. The majority of lipoprotein lipase (LPL) in plasma was found in RLP as RLP-LPL complex, which is released into circulation after hydrolysis. LPL activity and concentration in plasma did not increase after food intake associated with the insufficient hydrolysis of chylomicrons and VLDL and resulted in the significant increase of RLP-TG. Plasma LPL was inversely correlated with RLP particle size and number.

SUMMARY

VLDL remnants have been shown as the major atherogenic lipoproteins in postprandial plasma associated with LPL activity as the targets for prevention of atherosclerosis. We also proposed a new definition of RLPs, 'LPL bound TG-rich lipoproteins' based on the findings of RLP-LPL complex.

Atherogenic postprandial remnant lipoproteins; VLDL remnants as a causal factor in atherosclerosis

Oxidized LDL (Ox-LDL) and chylomicron (CM) remnants have been suggested to be the most atherogenic lipoproteins that initiate and exacerbate coronary atherosclerosis. In this review, we propose a hypothesis of the causal lipoproteins in atherosclerosis based on our recent findings on postprandial remnant lipoproteins (RLP). Plasma RLP-C and RLP-TG increased significantly after food intake, especially a fat load. More than 80% of the TG increase after the fat load consisted of the TG in RLP, which contained significantly greater apoB100 than apoB48 particles as VLDL remnants. The majority of the LPL in non-heparin plasma was found in RLP as an RLP-LPL complex and released into the circulation after hydrolysis. Plasma LPL did not increase after food intake, which may have caused the partial hydrolysis of CM and VLDL as well as the significant increase of RLP-TG in the postprandial plasma. LPL was inversely correlated with the RLP particle size after food intake. We showed that VLDL remnants are the major atherogenic lipoproteins in the postprandial plasma associated with insufficient LPL activity and a causal factor in the initiation and progression of atherosclerosis. We also propose "LPL bound TG-rich lipoproteins" as a new definition of remnant lipoproteins based on the findings of the RLP-LPL complex in the non-heparin plasma.

The Effect of Tofogliflozin Treatment on Postprandial Glucose and Lipid Metabolism in Japanese Men With Type 2 Diabetes: A Pilot Study

Background

Postprandial hyperglycemia and hyperlipidemia are highly related to the development of atherosclerosis. Sodium/glucose cotransporter-2 (SGLT2) inhibitors have attracted attention as a new class of anti-diabetic agents for the treatment of type 2 diabetes. We investigated the effect of tofogliflozin on postprandial glucose and lipid metabolism in Japanese male patients with type 2 diabetes.

Methods

Ten Japanese men with type 2 diabetes (average age 66.3 years) were orally administered tofogliflozin (20 mg per day) for 8 weeks followed by a subsequent 8 weeks of washout of the agent. At 0, 8 and 16 weeks, postprandial metabolic parameters were measured at 0, 60 and 120 min after cookie ingestion.

Results

There were significant reductions in body weight and body mass index at 8 weeks. There was a reduction in HbA1c at 8 weeks, which returned to pretreatment levels at 16 weeks. Serum insulin levels did not change during the entire study period under either fasting or postprandial state. The area under the curve of plasma glucagon significantly increased at 8 weeks. There were no changes in lipid and lipoprotein levels either in fasting or postprandial state except for tendency toward reduction in postprandial triglycerides at 8 weeks and increase in HDL-C at 16 weeks.

Conclusions

Tofogliflozin treatment causes an improvement of postprandial glucose metabolism but not considerable postprandial lipid metabolism.

Lipoprotein lipase does not increase significantly in the postprandial plasma

BACKGROUND

Previous reports have shown that lipoprotein lipase (LPL) activity significantly increases in the postprandial plasma associated with the increase of TG-rich lipoproteins. Therefore, we have reexamined those relationships using newly developed LPL assay with the different kinds of food intake.

METHODS

Standard meal (n=81), 50g of fat (n=54), 75g of glucose (n=25) and cookie (25g fat and 75g carbohydrate fat) (n=28) were administered in generally healthy volunteers. Plasma LPL, HTGL and TC, TG, LDL-C, HDL-C, RLP-C and RLP-TG were determined at subsequent withdrawal after the food intake.

RESULTS

Plasma TG, RLP-C and RLP-TG were significantly increased at 8PM (2h after dinner of standard meal) compared with 8AM before breakfast within the same day. Also those parameters were significantly increased in 2-6h after fat load. However, the concentrations and activities of LPL and HTGL did not significantly increase in association with an increase in the TG and remnant lipoproteins. Also LPL concentration did not significantly increase after glucose and "cookie test" within 4h.

CONCLUSION

No significant increase of LPL activity was found at CM and VLDL overload after different kinds of food intake when reexamined by newly developed assay for LPL activity and concentration.

Impaired response of VLDL lipid and apoB secretion to endotoxin in the fasted rat liver

Bacterial infection elicits hypertriglyceridemia attributed to increased hepatic production of very low-density lipoprotein (VLDL) particles and decreased peripheral metabolism. The mechanisms underlying VLDL overproduction in sepsis are as yet unclear, but seem to be fed/fasted state-dependent. To learn more about this, we investigated hepatocytes isolated from fasted rats, made endotoxic by 1 mg/kg lipopolysaccharide (LPS) injection, for their ability to secrete the VLDL protein and lipid components. The results were then related to lipogenesis markers and expression of genes critical to VLDL biogenesis. Endotoxic rats showed increased levels of serum VLDL-apoB (10-fold), -triglyceride (2-fold), and -cholesterol (2-fold), whereby circulating VLDL were lipid-poor particles. Similarly, VLDL-apoB secretion by isolated endotoxic hepatocytes was ~85% above control, whereas marginal changes in the output of VLDL-lipid classes occurred. This was accompanied by a substantial rise in apoB and a moderate rise in MTP mRNA levels, but with basal de novo formation and efficiency of secretion of triglycerides, cholesterol and cholesteryl esters. These results indicate that during periods of food restriction, endotoxin does not enhance lipid provision to accomplish normal lipidation of overproduced apoB molecules, though this does occur to a sufficient extent to pass the proteasome checkpoint and secretion of lipid-poor, type 2 VLDL takes place.

Antiatherogenic and Cardioprotective Effects of Black Chokeberry (Aronia melanocarpa) Juice in Aging Rats

Age-related diseases are a social problem of global significance and their prevention by natural products is a research area of particular interest. The present study is an approach to counteract the risk factors for atherosclerosis arising in the aging process by supplementation of chokeberry juice. It employed a model of healthy adult rats monitored for a number of somatometric, serum lipidogram, and histopathological parameters, related to risk factors and their response to supplementation with antioxidant-rich chokeberry juice. The results were used to calculate different atherogenic and cardioprotective indices, and all results were compared to those of young healthy rats. Chokeberry juice proved an extremely rich source of polyphenols resulting in very high antioxidant activity. Treatment with Aronia juice significantly lowered the proatherogenic low-density lipoprotein fraction of the animals studied and led to a 16.5% decrease in their total cholesterol. Atherogenic indices in Aronia-supplemented animals clearly showed lower atherogenic risk and cardioprotective indices indicated protection of the cardiovascular system. Besides that, chokeberry juice retarded the age-related changes in the aortic wall and can be recommended as a prophylactic tool for healthy aging.

Effect of the Probiotic Saccharomyces boulardii on Cholesterol and Lipoprotein Particles in Hypercholesterolemic Adults: A Single-Arm, Open-Label Pilot Study

OBJECTIVES

Elevated blood cholesterol levels are a major risk factor for coronary artery disease, the leading cause of death worldwide. Probiotics have been investigated as potential cholesterol-lowering therapies, but no previous studies have assessed the effect of the probiotic yeast Saccharomyces boulardii on cholesterol levels in human volunteers. The objective of this study was to examine the effect of S. boulardii on serum cholesterol and lipoprotein particles in hypercholesterolemic adults.

DESIGN

This study was a single-arm, open-label pilot study.

SUBJECTS

Twelve hypercholesterolemic participants were recruited into the study; one dropped out.

INTERVENTION

Participants took 5.6×10(10) colony forming unit (CFU) encapsulated S. boulardii (Saccharomyces cerevisiae var. boulardii CNCM I-1079) twice daily for an 8-week period.

OUTCOME MEASURES

Fasting concentrations of cholesterol (total cholesterol, low-density lipoprotein-cholesterol [LDL-C], high-density lipoprotein-cholesterol [HDL-C], and triglycerides), lipoprotein particles (very-low-density lipoprotein-particle [VLDL-P], remnant lipoprotein particle [RLP-P], total LDL-P, LDL III-P, LDL IV-P, total HDL-P, and HDL 2b-P), and additional cardiovascular biomarkers (apo B-100, lipoprotein [a], high-sensitivity C-reactive protein, homocysteine, fibrinogen, and insulin) were measured at baseline, after 4 weeks, and after 8 weeks.

RESULTS

Remnant lipoprotein particles decreased by 15.5% (p=0.03) over the 8-week period. The remaining outcome measures were not significantly altered.

CONCLUSIONS

In this pilot study, 8 weeks of daily supplementation with S. boulardii lowered remnant lipoprotein, a predictive biomarker and potential therapeutic target in the treatment and prevention of coronary artery disease.

National lipid association recommendations for patient-centered management of dyslipidemia: part 1--full report

The leadership of the National Lipid Association convened an Expert Panel to develop a consensus set of recommendations for patient-centered management of dyslipidemia in clinical medicine. An Executive Summary of those recommendations was previously published. This document provides support for the recommendations outlined in the Executive Summary. The major conclusions include (1) an elevated level of cholesterol carried by circulating apolipoprotein B-containing lipoproteins (non-high-density lipoprotein cholesterol and low-density lipoprotein cholesterol [LDL-C], termed atherogenic cholesterol) is a root cause of atherosclerosis, the key underlying process contributing to most clinical atherosclerotic cardiovascular disease (ASCVD) events; (2) reducing elevated levels of atherogenic cholesterol will lower ASCVD risk in proportion to the extent that atherogenic cholesterol is reduced. This benefit is presumed to result from atherogenic cholesterol lowering through multiple modalities, including lifestyle and drug therapies; (3) the intensity of risk-reduction therapy should generally be adjusted to the patient's absolute risk for an ASCVD event; (4) atherosclerosis is a process that often begins early in life and progresses for decades before resulting a clinical ASCVD event. Therefore, both intermediate-term and long-term or lifetime risk should be considered when assessing the potential benefits and hazards of risk-reduction therapies; (5) for patients in whom lipid-lowering drug therapy is indicated, statin treatment is the primary modality for reducing ASCVD risk; (6) nonlipid ASCVD risk factors should also be managed appropriately, particularly high blood pressure, cigarette smoking, and diabetes mellitus; and (7) the measurement and monitoring of atherogenic cholesterol levels remain an important part of a comprehensive ASCVD prevention strategy.

High remnant lipoprotein predicts recurrent cardiovascular events on statin treatment after acute coronary syndrome

BACKGROUND

After acute coronary syndrome (ACS), there is a high risk of recurrent cardiovascular events. Triglyceride-rich lipoproteins influence residual cardiovascular risk in patients taking statin. This study examined the predictive value of remnant lipoprotein level for secondary cardiovascular events in patients treated with statins after ACS.

METHODS AND RESULTS

A total of 190 patients treated with statins after ACS were enrolled in the study. The serum level of remnant lipoproteins (remnant-like lipoprotein particle cholesterol; RLP-C) was measured using an immunoseparation method. All the patients were followed prospectively for a maximum period of 70 months or until the occurrence of one of the following events: cardiac death, non-fatal myocardial infarction, unstable angina requiring unplanned coronary revascularization, or ischemic stroke. During the follow-up period, 42 patients had a secondary event. Multivariate Cox analysis showed that a high level of RLP-C (≥5.4 mg/dl; determined on receiver operating characteristic curve analysis) was a significant risk factor for secondary events, independent of conventional risk factors (hazard ratio, 2.94; 95% confidence interval: 1.40-6.18; P<0.01). The addition of high RLP-C to traditional risk factors enhanced net reclassification improvement (NRI) and integrated discrimination improvement (IDI) (NRI, 0.66, P=0.0003; and IDI, 0.08, P=0.0002).

CONCLUSIONS

RLP-C is useful for risk assessment of secondary cardiovascular events in patients treated with statins after ACS.

An International Atherosclerosis Society Position Paper: global recommendations for the management of dyslipidemia--full report

An international panel of the International Atherosclerosis Society has developed a new set of recommendations for the management of dyslipidemia. The panel identifies non--high-density lipoprotein cholesterol as the major atherogenic lipoprotein. Primary and secondary prevention are considered separately. Optimal levels for atherogenic lipoproteins are derived for the two forms of prevention. For primary prevention, the recommendations emphasize lifestyle therapies to reduce atherogenic lipoproteins; drug therapy is reserved for subjects at greater risk. Risk assessment is based on estimation of lifetime risk according to differences in baseline population risk in different nations or regions. Secondary prevention emphasizes use of cholesterol-lowering drugs to attain optimal levels of atherogenic lipoproteins.

Short-term effect of pitavastatin treatment on glucose and lipid metabolism and oxidative stress in fasting and postprandial state using a test meal in Japanese men

Introduction. The objective of this study was to clarify how pitavastatin affects glucose and lipid metabolism, renal function, and oxidative stress. Methods. Ten Japanese men (average age of 33.9 years) were orally administered 2 mg of pitavastatin for 4 weeks. Postprandial glucose, lipoprotein metabolism, and oxidative stress markers were evaluated at 0 and 4 weeks of pitavastatin treatment (2 mg once daily) with a test meal consisting of total calories: 460 kcal, carbohydrates: 56.5 g (226 kcal), protein: 18 g (72 kcal), lipids: 18 g (162 kcal), and NaCl: 1.6 g. Metabolic parameters were measured at 0, 60, and 120 minutes after test meal ingestion. Results. After administration of pitavastatin, serum total cholesterol, low-density lipoprotein cholesterol, apolipoprotein B, arachidonic acid, insulin, and adjusted urinary excretion of uric acid decreased, whereas creatinine clearance (C_Cr) and uric acid clearance (C_UA) increased. And postprandial versus fasting urine 8-hydroxydeoxyguanosine remained unchanged, while postprandial versus fasting isoprostane decreased after pitavastatin treatment. Next, we compared postprandial glucose and lipid metabolism after test meal ingestion before and after pitavastatin administration. Incremental areas under the curve significantly decreased for triglycerides (P < 0.05) and remnant-like particle cholesterol (P < 0.01), while those for apolipoprotein E (apoE), glucose, insulin, and high-sensitivity C-reactive protein remained unchanged. Conclusion. Pitavastatin improves postprandial oxidative stress along with hyperlipidemia.

New therapeutic alternatives for the management of dyslipidemia

Hypercholesterolemia affects over 34 million adults in the United States and is a major cause of coronary heart disease (CHD). Conventional therapies, such as statins, have demonstrated their ability to improve clinical end points and decrease morbidity and mortality in patients with CHD. Lomitapide (Juxtapid(®)), mipomersen (Kynamro(®)), and icosapent (Vascepa(®)) are 3 novel agents approved by the US Food and Drug Administration in the past 2 years, which offer new lipid-lowering treatment options with unique pharmacology.

Dyslipidemia, kidney disease, and cardiovascular disease in diabetic patients

This article reviews the relationship between dyslipidemia, chronic kidney disease, and cardiovascular diseases in patients with diabetes. Diabetes mellitus is associated with complications in the cardiovascular and renal system, and is increasing in prevalence worldwide. Modification of the multifactorial risk factors, in particular dyslipidemia, has been suggested to reduce the rates of diabetes-related complications. Dyslipidemia in diabetes is a condition that includes hypertriglyceridemia, low high-density lipoprotein levels, and increased small and dense low-density lipoprotein particles. This condition is associated with higher cardiovascular risk and mortality in diabetic patients. Current treatment guidelines focus on lowering the low-density lipoprotein cholesterol level; multiple trials have confirmed the cardiovascular benefits of treatment with statins. Chronic kidney disease also contributes to dyslipidemia, and dyslipidemia in turn is related to the occurrence and progression of diabetic nephropathy. Different patterns of dyslipidemia are associated with different stages of diabetic nephropathy. Some trials have shown that treatment with statins not only decreased the risk of cardiovascular events, but also delayed the progression of diabetic nephropathy. However, studies using statins as the sole treatment of hyperlipidemia in patients on dialysis have not shown benefits with respect to cardiovascular risk. Diabetic patients with nephropathy have a higher risk of cardiovascular events than those without nephropathy. The degree of albuminuria and the reduction in estimated glomerular filtration rate are also correlated with the risk of cardiovascular events. Treatment with angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers to reduce albuminuria in diabetic patients has been shown to decrease the risk of cardiovascular morbidity and mortality.

Exploitation of lipid components by viral and host proteins for hepatitis C virus infection

Hepatitis C virus (HCV), which is a major causative agent of blood-borne hepatitis, has chronically infected about 170 million individuals worldwide and leads to chronic infection, resulting in development of steatosis, cirrhosis, and eventually hepatocellular carcinoma. Hepatocellular carcinoma associated with HCV infection is not only caused by chronic inflammation, but also by the biological activity of HCV proteins. HCV core protein is known as a main component of the viral nucleocapsid. It cooperates with host factors and possesses biological activity causing lipid alteration, oxidative stress, and progression of cell growth, while other viral proteins also interact with host proteins including molecular chaperones, membrane-anchoring proteins, and enzymes associated with lipid metabolism to maintain the efficiency of viral replication and production. HCV core protein is localized on the surface of lipid droplets in infected cells. However, the role of lipid droplets in HCV infection has not yet been elucidated. Several groups recently reported that other viral proteins also support viral infection by regulation of lipid droplets and core localization in infected cells. Furthermore, lipid components are required for modification of host factors and the intracellular membrane to maintain or up-regulate viral replication. In this review, we summarize the current status of knowledge regarding the exploitation of lipid components by viral and host proteins in HCV infection.

Ezetimibe: its novel effects on the prevention and the treatment of cholesterol gallstones and nonalcoholic Fatty liver disease

The cholesterol absorption inhibitor ezetimibe can significantly reduce plasma cholesterol concentrations by inhibiting the Niemann-Pick C1-like 1 protein (NPC1L1), an intestinal sterol influx transporter that can actively facilitate the uptake of cholesterol for intestinal absorption. Unexpectedly, ezetimibe treatment also induces a complete resistance to cholesterol gallstone formation and nonalcoholic fatty liver disease (NAFLD) in addition to preventing hypercholesterolemia in mice on a Western diet. Because chylomicrons are the vehicles with which the enterocytes transport cholesterol and fatty acids into the body, ezetimibe could prevent these two most prevalent hepatobiliary diseases possibly through the regulation of chylomicron-derived cholesterol and fatty acid metabolism in the liver. It is highly likely that there is an intestinal and hepatic cross-talk through the chylomicron pathway. Therefore, understanding the molecular mechanisms whereby cholesterol and fatty acids are absorbed from the intestine could offer an efficacious novel approach to the prevention and the treatment of cholesterol gallstones and NAFLD.

Apolipoproteins: metabolic role and clinical biochemistry applications

Lipoprotein metabolism is dependent on apolipoproteins, multifunctional proteins that serve as templates for the assembly of lipoprotein particles, maintain their structure and direct their metabolism through binding to membrane receptors and regulation of enzyme activity. The three principal functions of lipoproteins are contribution to interorgan fuel (triglyceride) distribution (by means of the fuel transport pathway), to the maintenance of the extracellular cholesterol pool (by means of the overflow pathway) and reverse cholesterol transport. The most important clinical application of apolipoprotein measurements in the plasma is in the assessment of cardiovascular risk. Concentrations of apolipoprotein B and apolipoprotein AI (and their ratio) seem to be better markers of cardiovascular risk than conventional markers such as total cholesterol and LDL-cholesterol. Apolipoprotein measurements are also better standardized than the conventional tests. We suggest that measurements of apolipoprotein AI and apolipoprotein B are included as a part of the specialist lipid profile. We also suggest that lipoprotein (a) should be measured as part of the initial assessment of dyslipidaemias because of its consistent association with cardiovascular risk. Genotyping of apolipoprotein E isoforms remains useful in the investigation of mixed dyslipidaemias. Lastly, the role of postprandial metabolism is increasingly recognized in the context of atherogenesis, obesity and diabetes. This requires better markers of chylomicrons, very-low-density lipoproteins and remnant particles. Measurements of apolipoprotein B48 and remnant lipoprotein cholesterol are currently the key tests in this emerging field.

Postprandial lipoprotein metabolism: VLDL vs chylomicrons

Since Zilversmit first proposed postprandial lipemia as the most common risk of cardiovascular disease, chylomicrons (CM) and CM remnants have been thought to be the major lipoproteins which are increased in the postprandial hyperlipidemia. However, it has been shown over the last two decades that the major increase in the postprandial lipoproteins after food intake occurs in the very low density lipoprotein (VLDL) remnants (apoB-100 particles), not CM or CM remnants (apoB-48 particles). This finding was obtained using the following three analytical methods; isolation of remnant-like lipoprotein particles (RLP) with specific antibodies, separation and detection of lipoprotein subclasses by gel permeation HPLC and determination of apoB-48 in fractionated lipoproteins by a specific ELISA. The amount of the apoB-48 particles in the postprandial RLP is significantly less than the apoB-100 particles, and the particle sizes of apoB-48 and apoB-100 in RLP are very similar when analyzed by HPLC. Moreover, CM or CM remnants having a large amount of TG were not found in the postprandial RLP. Therefore, the major portion of the TG which is increased in the postprandial state is composed of VLDL remnants, which have been recognized as a significant risk for cardiovascular disease.

Predictive value of remnant lipoprotein for cardiovascular events in patients with coronary artery disease after achievement of LDL-cholesterol goals

OBJECTIVES

Triglycerides-rich lipoproteins are related to residual cardiovascular risk in patients on lipid-lowering treatment who achieve low-density lipoprotein cholesterol (LDL-C) goals. This study examined the predictive value of remnant lipoprotein levels for cardiovascular events in patients with coronary artery disease (CAD) with LDL-C levels <100mg/dL on lipid-lowering therapy.

METHODS

Serum levels of remnant lipoproteins (remnant-like lipoprotein particles cholesterol; RLP-C) were measured by an immunoseparation method in 560 patients with CAD who had LDL-C levels <100mg/dL on lipid-lowering therapy, including statin (58%), fibrate (13%) or diet only (29%). All the patients were followed prospectively for a period of ≤ 36 months or until occurrence of one of the following events: cardiac death, non fatal myocardial infarction, unstable angina requiring coronary revascularization, or ischemic stroke.

RESULTS

During a mean follow-up period of 33 months, 40 events occurred. Stepwise multivariate Cox proportional hazard analysis showed that RLP-C was a significant predictor of cardiovascular events after adjustment for known risk factors and lipid variables including triglycerides, non-high-density lipoprotein (HDL)-C, and total apolipoprotein B (HR 1.53, 95% CI 1.35-1.97, p<0.01). The c-statistics showed that addition of RLP-C had a greater incremental effect on the predictive value of conventional risk factors than addition of non-HDL-C or total apolipoprotein B.

CONCLUSIONS

RLP-C was superior to non-HDL-C for predicting cardiovascular events in CAD patients with LDL-C levels <100mg/dL on lipid-lowering treatment. Remnant lipoprotein may therefore be an important target for residual risk reduction after LDL-C goals on lipid lowering therapy.

Apolipoprotein E polymorphisms and postprandial triglyceridemia before and after fenofibrate treatment in the Genetics of Lipid Lowering and Diet Network (GOLDN) Study

BACKGROUND

Although much is known about the effect of Apolipoprotein E (APOE) alleles on fasting lipid concentrations, less is known about the effect of APOE alleles on postprandial triglyceridemia or the triglyceride response to fenofibrate.

METHODS AND RESULTS

We evaluated the effects of the APOE locus on fasting and postprandial triglyceride concentrations as part of the Genetics of Lipid Lowering and Diet Network (GOLDN) study. Participants were evaluated after a high-fat meal challenge before (n=1072) and after 3 weeks of daily treatment with 160 mg of fenofibrate (n=738). Mixed models adjusted for sex, age, waist circumference, and family relationship were used to examine the association of the ε4 carrier and ε2 carrier status versus ε3 homozygotes with fasting triglycerides and the area under the curve (AUC) for triglycerides during the high-fat meal challenge. Compared with the ε3/ε3 genotype, ε2 carriers had on average higher fasting triglyceride concentrations (130.5 mg/dL versus 109.3 mg/dL, P<0.001). After fenofibrate treatment, the APOE genotype differences persisted in the fasting state (ε2 carriers: 85.1 mg/dL versus ε3/ε3: 75.9 mg/dL, P<0.05). Carriers of the ε4 allele had significantly higher fasting triglyceride concentrations only prefenofibrate (120.9 mg/dL versus 109.3 mg/dL, P=0.008). APOE alleles did not have an effect on response to fenofibrate. Postprandial triglycerides were significantly higher for ε2 carriers versus ε3 homozygotes (but not ε4 carriers) both before and after fenofibrate treatment (P=0.01 and P=0.005, respectively).

CONCLUSIONS

APOE polymorphisms are important determinants of triglyceride concentrations, especially in the fasting state.

Association of angiopoietin-like protein 3 with hepatic triglyceride lipase and lipoprotein lipase activities in human plasma

Background

The relationship between plasma angiopoietin-like protein 3 (ANGPTL3), and lipoprotein lipase (LPL) activity and hepatic triglyceride lipase (HTGL) activity has not been investigated in the metabolism of remnant lipoproteins (RLPs) and high-density lipoprotein (HDL) in human plasma.

Methods

ANGPTL3, LPL activity, HTGL activity, RLP-C and RLP-TG and small, dense LDL-cholesterol (sd LDL-C) were measured in 20 overweight and obese subjects in the fasting and postprandial states.

Results

Plasma TG, RLP-C, RLP-TG and sd LDL-C were inversely correlated with LPL activity both in the fasting and postprandial states, but not correlated with HTGL activity and ANGPTL3. However, plasma HDL-C was positively correlated with LPL activity both in the fasting and postprandial states, while inversely correlated with HTGL activity. ANGPTL3 was inversely correlated with HTGL activity both in the fasting and postprandial states, but not correlated with LPL activity.

Conclusion

HTGL plays a major role in HDL metabolism, but not RLP metabolism. These findings suggest that ANGPTL3 is strongly associated with the inhibition of HTGL activity and regulates HDL metabolism, but not associated with the inhibition of LPL activity for the metabolism of RLPs in human plasma.

The diameter of liver sinusoidal fenestrae is not a major determinant of lipoprotein levels and atherosclerosis in cholesterol-fed rabbits

BACKGROUND

The liver is a key organ in lipid and lipoprotein metabolism. It has been postulated that a small diameter of sinusoidal fenestrae retards clearance of chylomicron remnants, resulting in hypercholesterolemia and atherosclerosis. However, this hypothesis has not been rigorously tested hitherto.

METHODS

In the current study, we compared plasma levels of proatherogenic lipoproteins and assessed the development of atherosclerosis at distinct locations throughout the arterial tree in heterozygous New Zealand White and Dutch Belt rabbits that are deficient in low-density lipoprotein receptor and with an average fenestrae size of 103 and 124 nm, respectively.

RESULTS

Feeding of a 0.15% cholesterol diet for 4 months resulted in similar total plasma cholesterol levels in New Zealand White (420±20 mg/dl) and Dutch Belt (380±30 mg/dl) rabbits. Following isolation of lipoproteins by ultracentrifugation, no biologically significant differences in very-low-density lipoprotein, intermediate-density lipoprotein, and low-density lipoprotein cholesterol levels were observed between cholesterol-fed New Zealand White and Dutch Belt rabbits. Furthermore, the relative amount of intestinally derived apolipoprotein-B48-containing lipoproteins did not differ significantly between both strains (7.3±0.42% vs. 8.0±0.54%). Atherosclerosis was more pronounced in the thoracic aorta in New Zealand White rabbits than in Dutch Belt rabbits, but the reverse was observed with the abdominal aorta. These topographic differences cannot be explained by circulating lipoprotein levels.

CONCLUSIONS

The data presented in this study do not support the hypothesis that the diameter of fenestrae is an important determinant of chylomicron remnant levels, diet-induced hypercholesterolemia, and atherosclerosis in cholesterol-fed rabbits.

Plant stanol supplementation decreases serum triacylglycerols in subjects with overt hypertriglyceridemia

Evidence is accumulating that high serum concentrations of triacylglycerols (TAG) are, like LDL cholesterol, causally related to cardiovascular disease. A recent meta-analysis has indicated that plant stanol ester (PSE) intake not only lowered LDL cholesterol, but also serum TAG concentrations, especially in subjects with high baseline TAG concentrations. We therefore evaluated the effects of PSE supplementation on lipid metabolism in a population with elevated fasting TAG concentrations. In a randomized, placebo-controlled, parallel study, 28 subjects with elevated TAG concentrations (>1.7 mmol/L) were studied. After a 1-week run-in period during which a control margarine was used, subjects consumed for 3 weeks either control or PSE-enriched margarine (2.5 g/day of plant stanols). Serum plant stanol concentrations increased in all subjects receiving the PSE-enriched margarines, demonstrating good compliance. PSE supplementation significantly decreased serum total (6.7%, P = 0.015) and LDL cholesterol (9.5%, P = 0.041). A significant interaction between baseline TAG concentrations and PSE intake was found; PSE intake lowered TAG concentrations, particularly in subjects with high baseline TAG concentrations (>2.3 mmol/L; P = 0.009). Additionally, a significant interaction between baseline total number of LDL particles (LDL-P) and PSE intake was found (P = 0.020). PSE consumption lowered LDL-P, primarily in subjects with elevated baseline values; this was mainly due to a non-significant decrease in the number of atherogenic small LDL-P. Circulating levels of hs-CRP, glucose, and insulin were not changed after PSE intake. Taken together, PSE supplementation not only lowered LDL cholesterol, but also serum TAG concentrations, especially in subjects with overt hypertriglyceridemia.

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.

The contribution of ApoB and ApoA1 measurements to cardiovascular risk assessment

LDL has been widely recognized as the major atherogenic lipoprotein and designated as the primary target for prevention of coronary heart disease (CHD); however, there is growing evidence that other triglyceride-rich lipoproteins, such as very low-density lipoprotein (VLDL) and intermediate density lipoprotein (IDL) carry atherogenic potential as well. This led to the designation of non-HDL cholesterol (HDL-C) (LDL + IDL + VLDL) as a secondary target of treatment for hyperlipidaemia. As each one of LDL, IDL and VLDL particles carries only one apolipoprotein B-100 (ApoB-100) molecule, the total ApoB value represents the total number of potentially atherogenic lipoproteins, whereas non-HDL-C provides the cholesterol content of these same lipoproteins. Recent data from epidemiological, observational and interventional studies suggest that non-HDL-C, apolipoproteins ApoA1 and ApoB may improve CHD risk assessment by identifying more high-risk individuals than the usual lipid profile alone. However, the targets for the optimal treatment of dyslipidaemia remain a subject of considerable debate. Further studies are needed to determine whether ApoB and ApoA1 are superior to conventional lipid parameters as predictors of cardiovascular disease or therapeutic targets of hyperlipidaemias. In this review, we summarize the current opinions on the use of ApoA1 and ApoB values as estimates of cardiovascular risk or as treatment goals in patients undergoing treatment for hyperlipidaemia.

Biochemical Aspects, Laboratory Diagnosis and Follow-Up of High Blood Cholesterol: NCEP ATP III Guidelines

Treći izveštaj ekspertske grupe o detekciji, evaluaciji i tretmanu povišene koncentracije holesterola u odraslih (Adult Treatment Panel III, ATP III) predstavlja ažuriran klinički vodič Nacionalnog programa edukacije o holesterolu (National Cholesterol Education Program, NCEP), o određivanju holesterola i zbrinjavanju osoba s povišenom koncentracijom holesterola u serumu. Pored toga što preporučuje intenzivan tretman pacijenata sa koronarnom srčanom bolešću (coronary heart disease/CHD), važna karakteristika ATP III je težište na primarnoj prevenciji kod osoba sa više prisutnih faktora rizika. ATP III nastavlja da identifikuje povišene koncentracije LDL holesterola kao primarni cilj terapije za snižavanje holesterola. Osnovni princip prevencije je da se intenzitet terapije prilagođava apsolutnom riziku za CHD svake osobe pojedinačno. Procena rizika podrazumeva određivanje LDL holesterola u sklopu analize lipoproteina i identifikaciju pratećih determinanti rizika (prisustvo ili odsustvo CHD, drugih kliničkih oblika aterosklerotske bolesti i dijabetesa, pušenje, hipertenzija, niska koncentracija HDL holesterola, porodična anamneza prevremene pojave CHD, starost). U kategoriji najvišeg rizika nalaze se osobe sa CHD i CHD ekvivalentima rizika, čiji je apsolutni rizik od pojave srčane smrti ili nefatalnog infarkta miokarda u narednih 10 godina ≥20%. Drugu kategoriju čine osobe sa dva ili više faktora rizika kod kojih je 10-godišnji rizik <20%. Apsolutni rizik se procenjuje na osnovuFraminghamrizik skora. U trećoj kategoriji su osobe sa jednim ili nijednim faktorom rizika. Definisane su preporučene koncentracije LDL holesterola za svaku kategoriju i postižu se korekcijom ishrane i/ili farmakoterapijom. Evropske preporuke za prevenciju kardiovaskularne bolesti (cardiovascular disease, CVD) u kliničkoj praksi preporučuju upotrebu SCO-RE (Systematic COronary Risk Evaluation) tablica za procenu rizika za pojavu CVD, koje podrazumevaju apsolutnu verovatnoću za fatalan ishod CVD u toku 10 godina. Cilj ovog rada je predstavljanje delova NCEP ATP III i evropskih preporuka značajnih za njihovu implementaciju u laboratorijsku praksu.

Effect of dietary cholesterol and fat on cell cholesterol transfer to postprandial plasma in hyperlipidemic men

Postprandial chylomicrons are potent ultimate acceptors of cell membrane cholesterol and are believed to accelerate reverse cholesterol transport (RCT). We compared the effects of meals rich in polyunsaturated fat (PUFA) and either high (605 mg) or low (151 mg) in cholesterol and a meal rich in dairy fat (DF) in the form of cream on net in vitro transport of red blood cell (RBC) membrane cholesterol to 4 and 6 h postprandial plasma in eight normotriglyceridemic (NTG-H) and eight hypertriglyceridemic (HTG-H) men with mild to moderate hypercholesterolemia. In HTG-H men, cell cholesterol accumulation in 6-h postprandial plasma was significantly (P = 0.02) less after the PUFA-HC meal compared with the other meals. The significant (P < 0.001) increase in cell plus endogenous cholesterol accumulation in the triglyceride-rich lipoprotein (TRL) fraction of 4 h postprandial plasma incubated with RBC was significantly (P = 0.007) higher after the PUFA-HC meal compared with DF meal in HTG-H men. In NTG-H men, cholesterol accumulation in plasma and plasma lipoproteins in the presence and absence of RBC was not significantly affected by the type of meal ingested. These data suggest that addition of large amounts of cholesterol to a PUFA meal may impair diffusion-mediated transport of cell membrane cholesterol to postprandial plasma and that replacing DF with PUFA in a meal increases postprandial lipemia and may potentially increase cholesterol accumulation in atherogenic postprandial TRL in HTG-H men.

Removal of triacylglycerols from chylomicrons and VLDL by capillary beds: the basis of lipoprotein remnant formation

The triacylglycerol content of chylomicrons and VLDL (very-low-density lipoprotein) compete for the same lipolytic pathway in the capillary beds. Although chylomicron triacylglycerols appear to be the favoured substrate for lipoprotein lipase, VLDL particles compete in numbers. Methods to quantify the specific triacylglycerol removal from VLDL and chylomicrons may involve endogenous labelling of the triacylglycerol substrate with stable isotopes in combination with arteriovenous blood sampling in humans. Arteriovenous quantification of remnant lipoproteins suggests that adipose tissue with its high lipoprotein lipase activity is a principal site for generation of remnant lipoproteins. Under circumstances of reduced efficiency in the removal of triacylglycerols from lipoproteins, there is accumulation of remnant lipoproteins, which are potentially atherogenic.

Fenofibrate effect on triglyceride and postprandial response of apolipoprotein A5 variants: the GOLDN study

OBJECTIVE

Apolipoprotein A5 (APOA5) is a key determinant of plasma triglyceride (TG) concentrations. Genetic variation at the APOA5 locus could be responsible for some of the observed differences in response to fenofibrate therapy.

METHODS AND RESULTS

We examined the association between tag SNPs (-1131T>C and 56C>G) at APOA5 and TG and HDL-C response to fenofibrate and a postprandial lipid challenge in 791 men and women participating in the GOLDN study. After 3-week drug treatment, APOA5 56G carriers displayed significant decrease in TG (P=0.006), and increase in HDL-C (P=0.002) levels relative to their basal values in the fasting state when compared with noncarriers (a TG reduction of -35.8+/-2.8% versus -27.9+/-0.9% and a HDL-C increase of 11.8+/-1.3% versus 6.9+/-0.5%, respectively). In the postprandial lipemia after a fat load, the 56G carriers showed a significant decrease in the area under curve for TG and increase for HDL-C than the noncarriers. These diverse beneficial responses of 56G carriers to fenofibrate were further characterized by a higher increase in large LDL-C concentrations and LDL size. On the other hand, subjects with different APOA5-1131T>C genotypes showed no significant response to fenofibrate intervention.

CONCLUSION

This study suggests that the APOA5 56G carriers benefited more from the fenofibrate treatment than noncarriers in lowering plasma TG and increasing HDL-C levels.