High density lipoprotein is positively correlated with the changes in circulating total adiponectin and high molecular weight adiponectin during dietary and fenofibrate treatment

Understanding HDL Metabolism and Biology Through In Vivo Tracer Kinetics

HDL (high-density lipoprotein), owing to its high protein content and small size, is the densest circulating lipoprotein. In contrast to lipid-laden VLDL (very-low-density lipoprotein) and LDL (low-density lipoprotein) that promote atherosclerosis, HDL is hypothesized to mitigate atherosclerosis via reverse cholesterol transport, a process that entails the uptake and clearance of excess cholesterol from peripheral tissues. This process is mediated by APOA1 (apolipoprotein A-I), the primary structural protein of HDL, as well as by the activities of additional HDL proteins. Tracer-dependent kinetic studies are an invaluable tool to study HDL-mediated reverse cholesterol transport and overall HDL metabolism in humans when a cardiovascular disease therapy is investigated. Unfortunately, HDL cholesterol-raising therapies have not been successful at reducing cardiovascular events suggesting an incomplete picture of HDL biology. However, as HDL tracer studies have evolved from radioactive isotope- to stable isotope-based strategies that in turn are reliant on mass spectrometry technologies, the complexity of the HDL proteome and its metabolism can be more readily addressed. In this review, we outline the motivations, timelines, advantages, and disadvantages of the various tracer kinetics strategies. We also feature the metabolic properties of select HDL proteins known to regulate reverse cholesterol transport, which in turn underscore that HDL lipoproteins comprise a heterogeneous particle population whose distinct protein constituents and kinetics likely determine its function and potential contribution to cholesterol clearance.

Associations between Insulin-Like Growth Factor Binding Protein-2 and lipoprotein kinetics in men

Low circulating concentrations of insulin-like growth factor binding protein-2 (IGFBP-2) have been associated with dyslipidemia, notably with high triglyceride (TG) levels. However, the determinants by which IGFBP-2 influences lipoprotein metabolism, especially that of TG-rich lipoproteins (TRLs), are poorly understood. Here, we aimed to assess the relationships between IGFBP-2 levels and lipoprotein production and catabolism in human subjects. Fasting IGFBP-2 concentrations were measured in the plasma of 219 men pooled from previous lipoprotein kinetics studies. We analyzed production rate and fractional catabolic rates of TRLapoB-48, and LDL-, IDL-, and VLDLapoB-100 by multicompartmental modeling of l-[5,5,5-D3] leucine enrichment data after a 12 h primed constant infusion in individuals kept in a constant nutritional steady state. Subjects had an average BMI of 30 kg/m², plasma IGFBP-2 levels of 157 ng/ml, and TG of 2.2 mmol/l. After adjustments for age and BMI, IGFBP-2 levels were negatively associated with plasma TG (r = −0.29; P < 0.0001) and positively associated with HDL-cholesterol (r = 0.26; P < 0.0001). In addition, IGFBP-2 levels were positively associated with the fractional catabolic rate of VLDLapoB-100 (r = 0.20; P < 0.01) and IDLapoB-100 (r = 0.19; P < 0.05) and inversely with the production rate of TRLapoB-48 (r = −0.28; P < 0.001). These correlations remained statistically significant after adjustments for age, BMI, and the amount of fat given during the tracer infusion. These findings show that the association between low plasma IGFBP-2 and high TG concentrations could be due to both an impaired clearance of apoB-100-containing VLDL and IDL particles and an increased production of apoB-48-containing chylomicrons. Additional studies are necessary to investigate whether and how IGFBP-2 directly impacts the kinetics of TRL.

Altered HDL metabolism in metabolic disorders: insights into the therapeutic potential of HDL

Metabolic disorders are associated with an increased risk of cardiovascular disease (CVD), and are commonly characterized by a low plasma level of high-density lipoprotein cholesterol (HDL-C). Although cholesterol lowering medications reduce CVD risk in these patients, they often remain at increased risk of CVD. Therapeutic strategies that raise HDL-C levels and improve HDL function are a potential treatment option for reducing residual CVD risk in these individuals. Over the past decade, understanding of the metabolism and cardioprotective functions of HDLs has improved, with preclinical and clinical studies both indicating that the ability of HDLs to mediate reverse cholesterol transport, inhibit inflammation and reduce oxidation is impaired in metabolic disorders. These cardioprotective effects of HDLs are supported by the outcomes of epidemiological, cell and animal studies, but have not been confirmed in several recent clinical outcome trials of HDL-raising agents. Recent studies suggest that HDL function may be clinically more important than plasma levels of HDL-C. However, at least some of the cardioprotective functions of HDLs are lost in acute coronary syndrome and stable coronary artery disease patients. HDL dysfunction is also associated with metabolic abnormalities. This review is concerned with the impact of metabolic abnormalities, including dyslipidemia, obesity and Type 2 diabetes, on the metabolism and cardioprotective functions of HDLs.

A 'High Risk' Lifestyle Pattern Is Associated with Metabolic Syndrome among Qatari Women of Reproductive Age: A Cross-Sectional National Study

This study investigated the effect of lifestyle patterns, as a combination of diet, physical activity and smoking, on Metabolic Syndrome (MetS) among Qatari women of childbearing age (n = 418), a population group particularly vulnerable to the health sequela of this syndrome. Using data from the National WHO STEPwise survey conducted in Qatar in 2012, Principal Component Factor Analysis was performed to derive lifestyle patterns with survey variables related to the frequency of consumption of 13 foods/food groups, physical activity levels, and smoking status. MetS was diagnosed using ATPIII criteria. Three lifestyle patterns were identified: 'High Risk' pattern, characterized by intakes of fast foods, sweets and sugar sweetened beverages, in addition to lower levels of physical activity and higher smoking prevalence; 'Prudent' pattern, driven mainly by higher intakes of fruits, vegetables, fish, and whole grains; and 'Traditional' pattern which included beans, meat, dairy products, and a low prevalence of smoking. Among these three lifestyle patterns, only the 'High Risk' was associated with MetS, whereby subjects belonging to the third tertile of this pattern's score had 2.5 times the odds of MetS compared to those belonging to the first tertile. The findings of this study demonstrated the synergy among high risk behaviors among Qatari women in increasing the odds of MetS; the latter being a major risk factor for cardiovascular diseases.

A randomized trial on the effects of 2010 Dietary Guidelines for Americans and Korean diet patterns on cardiovascular risk factors in overweight and obese adults

BACKGROUND

Dietary patterns that are considered healthy (eg, the Dietary Approaches to Stop Hypertension diet and Mediterranean diet) may be more successful in reducing typical cardiovascular disease risks compared to dietary patterns considered unhealthy (eg, energy-dense diets such as the typical American diet).

OBJECTIVE

This study assessed the effects of a Korean diet, the 2010 Dietary Guidelines for Americans (DGA), and a typical American diet on cardiometabolic risk factors, including lipid levels and blood pressure, in overweight, non-Asian individuals in the United States with elevated low-density lipoprotein cholesterol.

DESIGN/INTERVENTION

The study was a three-period crossover, controlled-feeding study from January 2012 to May 2012. Thirty-one subjects were randomly allocated to one of six possible sequential orders for consuming the three diets for 4 weeks, each separated by a 10-day break. Data analysis included 27 subjects on the Korean diet periods and 29 in the DGA and typical American diet periods. Subjects remained weight stable.

MAIN OUTCOME MEASURES

Lipid profile, blood pressure, insulin, glucose, and 24-hour urinary sodium were determined at baseline and at the end of each diet period.

STATISTICAL ANALYSES PERFORMED

The additive main effects multiplicative interactions model was used to test for a subject by diet interaction. Differences among diets were determined using a mixed-models procedure (PROC MIXED) with random intercept for each subject.

RESULTS

Total cholesterol and low-density lipoprotein cholesterol significantly decreased on Korean (P<0.0001 and P<0.01, respectively) and DGA (P<0.01 and P<0.05, respectively) diets, but not on the typical American diet. Although an unfavorable outcome, high-density lipoprotein cholesterol significantly decreased on all three diets (Korean: P<0.0001; DGA: P<0.0001; typical American: P<0.05). No diet had a significant effect on serum triglycerides, but a slight increase in triglycerides in the Korean and decrease in the DGA resulted in a significant difference between these two diets (P<0.01). All three diets caused modest decreases in systolic and diastolic blood pressure, which reached statistical significance for DGA only (P<0.05 and P<0.01, respectively). No diet had significant effect on fasting insulin, whereas fasting glucose decreased significantly on the Korean (P<0.01) and typical American (P<0.05) diets only. Urinary sodium output decreased significantly on DGA (P<0.0001).

CONCLUSIONS

After a 4-week feeding period, Korean and DGA diet patterns resulted in positive changes in cardiovascular disease risk factors.

Impact of milk consumption on cardiometabolic risk in postmenopausal women with abdominal obesity

Background

The impact of dairy intake on cardiometabolic risk factors associated with metabolic syndrome (MetS) needs further research.

Objective

To investigate the impact of milk consumption on a wide array of cardiometabolic risk factors associated with MetS (blood lipids, cholesterol homeostasis, glucose homeostasis, systemic inflammation, blood pressure, endothelial function) in postmenopausal women with abdominal obesity.

Methods

In this randomized, crossover study, 27 women with abdominal obesity consumed two 6-week diets based on the National Cholesterol Education Program (NCEP), one with 3.2 servings/d of 2% fat milk per 2000 kcal (MILK) and one without milk or other dairy (NCEP). The macronutrient composition of both diets was comparable (55% carbohydrates, 15% proteins, 30% fat and 10% saturated fat).

Results

The MILK diet had no significant effect on LDL-C, triglycerides, LDL size, CRP and cell adhesion molecule concentrations and on indicators of insulin sensitivity. The MILK diet reduced HDL-C, adiponectin, endothelin and fasting glucose levels as well blood pressure (all P ≤ 0.01), but those changes were comparable to those seen with the NCEP milk-free diet (all between-diet P ≥ 0.07). Finally, the MILK diet was associated with lower VLDL apolipoprotein B fractional catabolic rate (−13.4%; P = 0.04) and plasma sterol concentrations (−12.0%; P = 0.04) compared with the control NCEP milk-free diet.

Conclusions

These data suggest that short-term consumption of low fat milk in the context of a prudent NCEP diet has no favorable nor deleterious effect on cardiometabolic risk factors associated with MetS in postmenopausal women with abdominal obesity.

Electronic supplementary material

The online version of this article (doi:10.1186/1475-2891-14-12) contains supplementary material, which is available to authorized users.

Effect of Mediterranean Diet With and Without Weight Loss on Apolipoprotein B 100 Metabolism in Men With Metabolic Syndrome

Objective—

To assess the effect of a Mediterranean diet (MedDiet) with and without weight loss (WL) on apolipoprotein B 100 (apoB 100 ) metabolism in men with metabolic syndrome.

Approach and Results—

The diet of 19 men with metabolic syndrome (age, 24–62 years) was first standardized to a North American isoenergetic control diet for 5 weeks, followed by an isoenergetic MedDiet for an additional 5 weeks under full-feeding conditions (MedDiet−WL). Participants next underwent a 20-week supervised WL program under free-living conditions (−10.2±2.9% body weight; P <0.01) and finally consumed the MedDiet (5 weeks) under weight-stabilizing feeding conditions (MedDiet+WL). In vivo kinetic of apoB 100 was assessed in the fasted state at the end of the 3 controlled diets using a bolus of D 3 -leucine. Compared with the control diet, MedDiet−WL reduced low-density lipoprotein (LDL)-apoB 100 pool size (−14.2%, P <0.01) primarily through an increase in LDL-apoB 100 fractional catabolic rate (+30.4%, P =0.02) and increased LDL particle size ( P <0.01) but had no effect on very-LDL (VLDL)-apoB 100 pool size or triglyceride concentrations, despite a significant increase in VLDL-apoB 100 fractional catabolic rate (+25.6%; P =0.03). MedDiet+WL had no further effect on LDL-apoB 100 pool size and fractional catabolic rate but further increased LDL particle size and reduced VLDL-apoB 100 pool size versus the control diet primarily through an increase in VLDL-apoB 100 fractional catabolic rate (+30.7%; P <0.01).

Conclusions—

Consumption of MedDiet increases LDL size and reduces LDL-apoB 100 concentrations primarily by increasing the catabolism of LDL even in the absence of WL in men with metabolic syndrome. MedDiet seems to have a trivial effect on VLDL concentrations and kinetics unless accompanied by significant WL.

Clinical Trial Registration

—URL: http://www.clinicaltrials.gov . Unique identifier: NCT00988650.

Effect of polyene phosphatidylcholine combined with fenofibrate capsules in treatment of nonalcoholic steatohepatitis

AIM: To investigate the efficacy and safety of polyene phosphatidylcholine combined with fenofibrate capsules in the treatment of nonalcoholic steatohepatitis (NASH).

METHODS: A total of 124 patients with NASH were selected and divided randomly into two groups: a treatment group and two control groups. The treatment group received polyene phosphatidylcholine combined with fenofibrate capsules (n = 45) for 12 wk, while the two control groups received fenofibrate capsules and inosine (n = 43) and polyene phosphatidylcholine alone (n = 36) for the same duration, respectively. The levels of serum transaminase, clinical symptoms, blood lipids and B-mode ultrasonic imaging findings before and after treatment were compared between groups.

RESULTS: The levels of serum transaminase, clinical symptoms, blood lipids and B-mode ultrasonic imaging findings improved obviously after treatment. The response rates were 86.7%, 53.5% and 88.9% in the treatment group and the two control groups, respectively. There were significant differences between the three groups in the improvement of clinical symptoms, liver function and blood lipids (P < 0.05 for all).

CONCLUSION: Treatment of NASH with fenofibrate capsules combined with polyene phosphatidylcholine is safe and effective.

Effect of the Mediterranean diet on plasma adipokine concentrations in men with metabolic syndrome

OBJECTIVE

While a Mediterranean dietary pattern (MedDiet) has been associated with favorable changes in several features of metabolic syndrome (MetS), its impact on plasma adipokine concentrations remains largely unknown. The objective of this study was to determine the impact of the MedDiet consumed under controlled feeding conditions, without (-WL) and with weight loss (+WL), on plasma adipokine concentrations in adult men with MetS (NCEP-ATP III).

MATERIALS/METHODS

The diet of 26 men with MetS (age 24 to 62 yrs) was first standardized to a North American control diet for 5 weeks. Participants then consumed a pre-determined MedDiet for 5 weeks. Both diets were consumed under weight-maintaining isoenergetic feeding conditions. Participants then underwent a 20-week free-living caloric restriction period, after which they consumed the MedDiet again in weight stabilizing, isoenergetic feeding conditions.

RESULTS

Body weight was reduced by 10.2%±2.9% and waist circumference by 8.6±3.3 cm after the weight loss period and stabilization on MedDiet (P<0.001). MedDiet-WL had no impact on plasma concentrations of leptin, plasminogen activator inhibitor-1, resistin, visfatin, acylation stimulating protein and adiponectin. MedDiet+WL reduced plasma leptin concentrations (P<0.01) and increased plasma adiponectin concentrations (P<0.05) compared with the control diet and MedDiet-WL.

CONCLUSION

Data from this nutritionally controlled study suggest that short-term consumption of MedDiet has little effect on the concentrations of many adipokines in the absence of weight loss.

Current role of fenofibrate in the prevention and management of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is a common health problem with a high mortality burden due to its liver- and vascular-specific complications. It is associated with obesity, high-fat diet as well as with type 2 diabetes mellitus (T2DM) and metabolic syndrome (MetS). Impaired hepatic fatty acid (FA) turnover together with insulin resistance are key players in NAFLD pathogenesis. Peroxisome proliferator-activated receptors (PPARs) are involved in lipid and glucose metabolic pathways. The novel concept is that the activation of the PPARα subunit may protect from liver steatosis. Fenofibrate, by activating PPARα, effectively improves the atherogenic lipid profile associated with T2DM and MetS. Experimental evidence suggested various protective effects of the drug against liver steatosis. Namely, fenofibrate-related PPARα activation may enhance the expression of genes promoting hepatic FA β-oxidation. Furthermore, fenofibrate reduces hepatic insulin resistance. It also inhibits the expression of inflammatory mediators involved in non-alcoholic steatohepatitis pathogenesis. These include tumor necrosis factor-α, intercellular cell adhesion molecule-1, vascular cell adhesion molecule-1 and monocyte chemoattractant protein-1. Consequently, fenofibrate can limit hepatic macrophage infiltration. Other liver-protective effects include decreased oxidative stress and improved liver microvasculature function. Experimental studies showed that fenofibrate can limit liver steatosis associated with high-fat diet, T2DM and obesity-related insulin resistance. Few studies showed that these benefits are also relevant even in the clinical setting. However, these have certain limitations. Namely, these were uncontrolled, their sample size was small, fenofibrate was used as a part of multifactorial approach, while histological data were absent. In this context, there is a need for large prospective studies, including proper control groups and full assessment of liver histology.

Dietary strategies to reduce metabolic syndrome

Metabolic syndrome (MetS) is a cluster of metabolic abnormalities characterized by central obesity, dyslipidemias, hypertension, high fasting glucose, chronic low-grade inflammation and oxidative stress. This condition has become an increasing problem in our society where about 34 % of adults are diagnosed with MetS. In parallel with the adult situation, a significant number of children present lipid abnormalities and insulin resistance, which can be used as markers of MetS in the pediatric population. Changes in lifestyle including healthy dietary regimens and increased physical activity should be the first lines of therapy to decrease MetS. In this article, we present the most recent information on successful dietary modifications that can reduce the parameters associated with MetS. Successful dietary strategies include energy restriction and weight loss, manipulation of dietary macronutrients--either through restriction of carbohydrates, fat, or enrichment in beneficial fatty acids, incorporation of functional foods and bioactive nutrients, and adherence to dietary and lifestyle patterns such the Mediterranean diet and diet/exercise regimens. Together, the recent findings presented in this review serve as evidence to support the therapeutic treatment of MetS through diet.