Triglyceride enrichment of HDL enhances in vivo metabolic clearance of HDL apo A-I in healthy men

Short-term HIIT impacts HDL function differently in lean, obese, and diabetic subjects

Introduction

High density lipoproteins (HDL) exert cardiovascular protection in part through their antioxidant capacity and cholesterol efflux function. Effects of exercise training on HDL function are yet to be well established, while impact on triacylglycerol (TG)-lowering has been often reported. We previously showed that a short-term high-intensity interval training (HIIT) program improves insulin sensitivity but does not inhibit inflammatory pathways in immune cells in insulin-resistant subjects. The purpose of this study is to evaluate HDL function along with changes of lipoproteins after the short-term HIIT program in lean, obese nondiabetic, and obese type 2 diabetic (T2DM) subjects.

Methods

All individuals underwent a supervised 15-day program of alternative HIIT for 40 minutes per day. VO2peak was determined before and after this training program. A pre-training fasting blood sample was collected, and the post-training fasting blood sample collection was performed 36 hours after the last exercise session.

Results

Blood lipid profile and HDL function were analyzed before and after the HIIT program. Along with improved blood lipid profiles in obese and T2DM subjects, the HIIT program affected circulating apolipoprotein amounts differently. The HIIT program increased HDL-cholesterol levels and improved the cholesterol efflux capacity only in lean subjects. Furthermore, the HIIT program improved the antioxidant capacity of HDL in all subjects. Data from multiple logistic regression analysis showed that changes in HDL antioxidant capacity were inversely associated with changes in atherogenic lipids and changes in HDL-TG content.

Discussion

We show that a short-term HIIT program improves aspects of HDL function depending on metabolic contexts, which correlates with improvements in blood lipid profile. Our results demonstrate that TG content in HDL particles may play a negative role in the anti-atherogenic function of HDL.

Association Between Triglycerides, High-Density Lipoprotein Cholesterol, and Their Ratio With the Pulse Wave Velocity in Adults From the ELSA-Brasil Study

Atherogenic dyslipidemia is a risk factor for cardiovascular diseases. The present study aimed to evaluate the association between triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), and the triglycerides to high-density lipoprotein (TG/HDL-C) ratio with carotid-femoral pulse wave velocity (cf-PWV), a marker of vascular stiffness. Anthropometric, biochemical, and clinical data from 13,732 adults were used to assess this association. Individuals within the third TG/HDL-C tertile presented worse anthropometric, biochemical, and clinical profiles as compared with the participants in the lower TG/HDL-C tertile. There was a linear association between TG, HDL-C, and TG/HDL-C ratio and cf-PWV in both men and women (stronger in women). After adjustment for confounders, lower levels of HDL-C were associated with increased cf-PWV in men (9.63 ± .02 m/s) and women (8.90 ± .03 m/s). However, TG was not significantly associated with cf-PWV after adjustment, regardless of sex. An increased TG/HDL-C ratio is associated with higher cf-PWV only in women (9.01 ± .03 m/s), but after adjustment for HDL-C levels, the association was non-significant (8.99 ± .03 m/s). These results highlight the stronger association of HDL-C with arterial stiffness, and that the association of TG/HDL-C with cf-PWV is dependent on HDL-C.

Deciphering structural aspects of reverse cholesterol transport: mapping the knowns and unknowns

Atherosclerosis is a major contributor to the onset and progression of cardiovascular disease (CVD). Cholesterol-loaded foam cells play a pivotal role in forming atherosclerotic plaques. Induction of cholesterol efflux from these cells may be a promising approach in treating CVD. The reverse cholesterol transport (RCT) pathway delivers cholesteryl ester (CE) packaged in high-density lipoproteins (HDL) from non-hepatic cells to the liver, thereby minimising cholesterol load of peripheral cells. RCT takes place via a well-organised interplay amongst apolipoprotein A1 (ApoA1), lecithin cholesterol acyltransferase (LCAT), ATP binding cassette transporter A1 (ABCA1), scavenger receptor-B1 (SR-B1), and the amount of free cholesterol. Unfortunately, modulation of RCT for treating atherosclerosis has failed in clinical trials owing to our lack of understanding of the relationship between HDL function and RCT. The fate of non-hepatic CEs in HDL is dependent on their access to proteins involved in remodelling and can be regulated at the structural level. An inadequate understanding of this inhibits the design of rational strategies for therapeutic interventions. Herein we extensively review the structure-function relationships that are essential for RCT. We also focus on genetic mutations that disturb the structural stability of proteins involved in RCT, rendering them partially or completely non-functional. Further studies are necessary for understanding the structural aspects of RCT pathway completely, and this review highlights alternative theories and unanswered questions.

High-Density Lipoprotein Alterations in Type 2 Diabetes and Obesity

Alterations affecting high-density lipoproteins (HDLs) are one of the various abnormalities observed in dyslipidemia in type 2 diabetes mellitus (T2DM) and obesity. Kinetic studies have demonstrated that the catabolism of HDL particles is accelerated. Both the size and the lipidome and proteome of HDL particles are significantly modified, which likely contributes to some of the functional defects of HDLs. Studies on cholesterol efflux capacity have yielded heterogeneous results, ranging from a defect to an improvement. Several studies indicate that HDLs are less able to inhibit the nuclear factor kappa-B (NF-κB) proinflammatory pathway, and subsequently, the adhesion of monocytes on endothelium and their recruitment into the subendothelial space. In addition, the antioxidative function of HDL particles is diminished, thus facilitating the deleterious effects of oxidized low-density lipoproteins on vasculature. Lastly, the HDL-induced activation of endothelial nitric oxide synthase is less effective in T2DM and metabolic syndrome, contributing to several HDL functional defects, such as an impaired capacity to promote vasodilatation and endothelium repair, and difficulty counteracting the production of reactive oxygen species and inflammation.

Effect of fixed-dose combination of insulin degludec and liraglutide on apoB-containing lipoprotein subclasses and HDL lipidome in type 2 diabetes

AIMS

Administration of insulin degludec and liraglutide (IDegLira) correlates to fasting lipid profile changes of diabetic patients, while data concerning apoB-containing lipoprotein subclasses and HDL lipidome are scarce. We evaluated its effect on fasting lipid parameters, apolipoproteins, apoB-containing lipoprotein subclasses and HDL lipidome in patients with type 2 diabetes.

METHODS

Sixty three patients with HbA1c > 7 % on oral glucose-lowering drugs received either IDegLira or insulin degludec for 3 months. Lipoprotein subfraction profile was determined through Lipoprint method, whereas HDL lipid composition via ¹H NMR.

RESULTS

Compared to insulin degludec, IDegLira administration resulted in significantly greater reduction of total and LDL-cholesterol. On the other hand, the effect of the two drugs on apolipoprotein-B-containing lipoprotein subfractions concentration was minimal and did not differ between the 2 interventions. IDegLira, but not insulin degludec, induced an atheroprotective shift in HDL's fatty acid composition and particle core depletion in triglycerides.

CONCLUSIONS

IDegLira administration is accompanied by total and LDL-cholesterol reduction, while sdLDL concentration only reduced in patients experiencing triglyceride reduction. IDegLira induced compositional changes of HDL particles. These changes may contribute to the cardioprotective properties of liraglutide.

Roles of maternal HDL during pregnancy

BACKGROUND

High density lipoproteins (HDL) were first linked to cardiovascular disease (CVD) over 30 years ago when an inverse relationship was shown between CVD and HDL-cholesterol levels. It is now apparent that HDL composition and function, not cholesterol levels, are the pertinent measurements describing HDL's role in various disease processes, especially those with subclinical or overt inflammation.

SCOPE OF REVIEW

Pregnancy is also an inflammatory state. When inflammation becomes excessive during pregnancy, there is an increased risk for adverse outcomes that affect the health of the mother and fetus, including preterm birth and preeclampsia. Though studies on HDL during pregnancy are limited, recent evidence demonstrates that HDL composition and function change during pregnancy and in women with adverse outcomes.

GENERAL SIGNIFICANCE

In this review, we will discuss how HDL may play a role in maintaining a healthy pregnancy and how impairments in function could lead to pregnancies with adverse outcomes.

Expressing the Human Cholesteryl Ester Transfer Protein Minigene Improves Diet-Induced Fatty Liver and Insulin Resistance in Female Mice

Mounting evidence has shown that CETP has important physiological roles in adapting to chronic nutrient excess, specifically, to protect against diet-induced insulin resistance. However, the underlying mechanisms for the protective roles of CETP in metabolism are not yet clear. Mice naturally lack CETP expression. We used transgenic mice with a human CETP minigene (huCETP) controlled by its natural flanking region to further understand CETP-related physiology in response to obesity. Female huCETP mice and their wild-type littermates were fed a high-fat diet for 6 months. Blood lipid profile and liver lipid metabolism were studied. Insulin sensitivity was analyzed with euglycemic-hyperinsulinemic clamp studies combined with ³H-glucose tracer techniques. While high-fat diet feeding induced obesity for huCETP mice and their wild-type littermates lacking CETP expression, insulin sensitivity was higher for female huCETP mice than for their wild-type littermates. There was no difference in insulin sensitivity for male huCETP mice vs. littermates. The increased insulin sensitivity in females was largely caused by the better insulin-mediated suppression of hepatic glucose production. In huCETP females, CETP in the circulation decreased HDL-cholesterol content and increased liver cholesterol uptake and liver cholesterol and oxysterol contents, which was associated with the upregulation of LXR target genes in long-chain polyunsaturated fatty acid biosynthesis and PPARα target genes in fatty acid β-oxidation in the liver. The upregulated fatty acid β-oxidation may account for the improved fatty liver and liver insulin action in female huCETP mice. This study provides further evidence that CETP has beneficial physiological roles in the metabolic adaptation to nutrient excess by promoting liver fatty acid oxidation and hepatic insulin sensitivity, particularly for females.

Postprandial plasma lipidome responses to a high-fat meal among healthy women

Postprandial lipemia consists of changes in concentrations and composition of plasma lipids after food intake, commonly presented as increased levels of triglyceride-rich lipoproteins. Postprandial hypertriglyceridemia may also affect high-density lipoprotein (HDL) structure and function, resulting in a net decrease in HDL concentrations. Elevated triglycerides (TG) and reduced HDL levels have been positively associated with risk of cardiovascular diseases development. Here, we investigated the plasma lipidome composition of 12 clinically healthy, nonobese and young women in response to an acute high-caloric (1135 kcal) and high-fat (64 g) breakfast meal. For this purpose, we employed a detailed untargeted mass spectrometry-based lipidomic approach and data was obtained at four sampling points: fasting and 1, 3 and 5 h postprandial. Analysis of variance revealed 73 significantly altered lipid species between all sampling points. Nonetheless, two divergent subgroups have emerged at 5 h postprandial as a function of differential plasma lipidome responses, and were thereby designated slow and fast TG metabolizers. Late responses by slow TG metabolizers were associated with increased concentrations of several species of TG and phosphatidylinositol (PI). Lipidomic analysis of lipoprotein fractions at 5 h postprandial revealed higher TG and PI concentrations in HDL from slow relative to fast TG metabolizers, but not in apoB-containing fraction. These data indicate that modulations in HDL lipidome during prolonged postprandial lipemia may potentially impact HDL functions. A comprehensive characterization of plasma lipidome responses to acute metabolic challenges may contribute to a better understanding of diet/lifestyle regulation in the metabolism of lipid and glucose.

HDL associates with insulin resistance and beta-cell dysfunction in South Asian families at risk of type 2 diabetes

OBJECTIVE

Dyslipidemia precedes type 2 diabetes (T2D) and worsens with increasing glucose intolerance. First degree relatives of T2D patients have an increased risk to develop dyslipidemia and glucose intolerance. The aim of the present study was to assess the relation between the development of dyslipidemia and glucose intolerance in first-degree relatives of T2D patients.

RESEARCH DESIGN AND METHODS

Fasting lipoprotein profiles were determined by density gradient ultracentrifugation in T2D patients and their first-degree relatives (42 Caucasians and 33 South Asians), and in 29 normoglycemic controls from non-T2D families. Glucose tolerance, insulin sensitivity index (ISI) and insulin disposition index (DI) were assessed by an extended, frequently sampled oral glucose tolerance test (OGTT), and fractional insulin synthesis rate (FSR) was measured by ¹³C-leucine enrichment in urinary C-peptide during the OGTT.

RESULTS

Of the first-degree relatives, 40, 16 and 19 had NGT, prediabetes and T2D, respectively. NGT family members had lower plasma HDL-cholesterol (HDLC) (1.34 ± 0.07 vs 1.58 ± 0.06 mmol/L; p = 0.015), HDL₂-C (0.41 ± 0.05 vs 0.57 ± 0.05 mmol/L; p = 0.021) and HDL₃-C (0.62 ± 0.03 vs 0.72 ± 0.02 mmol/L; p = 0.043) than controls. HDL₂-C levels tended to decrease with increasing glucose intolerance state. In South Asians, buoyant LDL-C levels decreased with increasing glucose intolerance state (p = 0.006). In South Asian families, HDL-C correlated with both ISI and DI (β 0.42; p = 0.04 and β 0.53; p = 0.01, respectively), whereas HDL₂-C and HDL₃-C levels correlated with DI (β 0.64; p = 0.002 and β 0.57; p = 0.005, respectively). HDL₂-C and plasma triglyceride correlated with FSR (β 0.48; p = 0.033 and β -0.50; p = 0.029, respectively).

CONCLUSIONS

Low HDL₂-C and HDL₃-C levels are present in NGT first-degree relatives of T2D patients, and HDL₂-C tend to decrease further with increasing glucose intolerance. In South Asian families HDL₂-C and HDL₃-C levels linked predominantly to deteriorating beta cell function.

New insights into the emerging effects of inflammatory response on HDL particles structure and function

According to the increasing results, it has been well-demonstrated that the chronic inflammatory response, including systemic lupus erythematosus, rheumatoid arthritis, and inflammatory bowel disease are associated with an increased risk of atherosclerotic cardiovascular disease. The mechanism whereby inflammatory response up-regulates the risk of cardio-metabolic disorder disease is multifactorial; furthermore, the alterations in high density lipoprotein (HDL) structure and function which occur under the inflammatory response could play an important modulatory function. On the other hand, the serum concentrations of HDL cholesterol (HDL-C) have been shown to be reduced significantly under inflammatory status with remarked alterations in HDL particles. Nevertheless, the potential mechanism whereby the inflammatory response reduces serum HDL-C levels is not simply defined but reduces apolipoprotein A1 production. The alterations in HDL structure mediated by the inflammatory response has been also confirmed to decrease the ability of HDL particle to play an important role in reverse cholesterol transport and protect the LDL particles from oxidation. Recently, it has been shown that under the inflammatory condition, diverse alterations in HDL structure could be observed which lead to changes in HDL function. In the current review, the emerging effects of inflammatory response on HDL particles structure and function are well-summarized to elucidate the potential mechanism whereby different inflammatory status modulates the pathogenic development of dyslipidemia.

High-density lipoprotein characteristics and coronary artery disease: a Mendelian randomization study

BACKGROUND

To assess whether genetically determined quantitative and qualitative HDL characteristics were independently associated with coronary artery disease (CAD).

METHODS

We designed a two-sample multivariate Mendelian randomization study with available genome-wide association summary data. We identified genetic variants associated with HDL cholesterol and apolipoprotein A-I levels, HDL size, particle levels, and lipid content to define our genetic instrumental variables in one sample (Kettunen et al. study, n = 24,925) and analyzed their association with CAD risk in a different study (CARDIoGRAMplusC4D, n = 184,305). We validated these results by defining our genetic variables in another database (METSIM, n = 8372) and studied their relationship with CAD in the CARDIoGRAMplusC4D dataset. To estimate the effect size of the associations of interest adjusted for other lipoprotein traits and minimize potential pleiotropy, we used the Multi-trait-based Conditional & Joint analysis.

RESULTS

Genetically determined HDL cholesterol and apolipoprotein A-I levels were not associated with CAD. HDL mean diameter (β = 0.27 [95%CI = 0.19; 0.35]), cholesterol levels in very large HDLs (β = 0.29 [95%CI = 0.17; 0.40]), and triglyceride content in very large HDLs (β = 0.14 [95%CI = 0.040; 0.25]) were directly associated with CAD risk, whereas the cholesterol content in medium-sized HDLs (β = -0.076 [95%CI = -0.10; -0.052]) was inversely related to this risk. These results were validated in the METSIM-CARDIoGRAMplusC4D data.

CONCLUSIONS

Some qualitative HDL characteristics (related to size, particle distribution, and cholesterol and triglyceride content) are related to CAD risk while HDL cholesterol levels are not.

Associations of HDL Subspecies Defined by ApoC3 with Non-Alcoholic Fatty Liver Disease: The Multi-Ethnic Study of Atherosclerosis

Previously, we reported that inverse associations of high-density lipoprotein (HDL) with cardiovascular disease and diabetes were only observed for HDL that lacked the pro-inflammatory protein apolipoprotein C3 (apoC3). To provide further insight into the cardiometabolic properties of HDL subspecies defined by the presence or absence of apoC3, we aimed to examine these subspecies with liver fat content and non-alcoholic fatty liver disease (NAFLD). We investigated cross-sectional associations between ELISA-measured plasma levels of apoA1 in HDL that contained or lacked apoC3 and computed tomography-determined liver fat content and NAFLD (<51 HU) at baseline (2000–2002) among 5007 participants in the Multi-Ethnic Study of Atherosclerosis (MESA) without heavy alcohol consumption (>14 drinks/week in men and >7 drinks/week in women). In multivariable-adjusted regression models, apoA1 in HDL that contained or lacked apoC3 was differentially associated with liver fat content (P_{heterogeneity} = 0.048). While apoA1 in HDL that lacked apoC3 was inversely associated with liver fat content (P_trend < 0.0001), apoA1 in HDL that contained apoC3 was not statistically significantly associated with liver fat content (P_trend = 0.57). Higher apoA1 in HDL that lacked apoC3 was related to a lower prevalence of NAFLD (OR per SD: 0.80; 95% CI: 0.72, 0.89), whereas no association was found for apoA1 in HDL that contained apoC3 (OR per SD: 0.95; 95% CI: 0.85, 1.05; P_{heterogeneity} = 0.09). Higher apoA1 in HDL that lacked apoC3 was associated with less liver fat content and a lower prevalence of NAFLD. This finding extends the inverse association of HDL lacking apoC3 from cardiovascular disease to NAFLD. Lack of biopsy-proven hepatic steatosis and fibrosis data requires the replication of our study in further studies.

Pathophysiology of Type 2 Diabetes Mellitus

Type 2 Diabetes Mellitus (T2DM), one of the most common metabolic disorders, is caused by a combination of two primary factors: defective insulin secretion by pancreatic β-cells and the inability of insulin-sensitive tissues to respond appropriately to insulin. Because insulin release and activity are essential processes for glucose homeostasis, the molecular mechanisms involved in the synthesis and release of insulin, as well as in its detection are tightly regulated. Defects in any of the mechanisms involved in these processes can lead to a metabolic imbalance responsible for the development of the disease. This review analyzes the key aspects of T2DM, as well as the molecular mechanisms and pathways implicated in insulin metabolism leading to T2DM and insulin resistance. For that purpose, we summarize the data gathered up until now, focusing especially on insulin synthesis, insulin release, insulin sensing and on the downstream effects on individual insulin-sensitive organs. The review also covers the pathological conditions perpetuating T2DM such as nutritional factors, physical activity, gut dysbiosis and metabolic memory. Additionally, because T2DM is associated with accelerated atherosclerosis development, we review here some of the molecular mechanisms that link T2DM and insulin resistance (IR) as well as cardiovascular risk as one of the most important complications in T2DM.

Cholesteryl Ester Transfer Protein Impairs Triglyceride Clearance via Androgen Receptor in Male Mice

Elevated postprandial triacylglycerols (TAG) are an important risk factor for cardiovascular disease. Men have higher plasma TAG and impaired TAG clearance compared to women, which may contribute to sex differences in risk of cardiovascular disease. Understanding mechanisms of sex differences in TAG metabolism may yield novel therapeutic targets to prevent cardiovascular disease. Cholesteryl ester transfer protein (CETP) is a lipid shuttling protein known for its effects on high‐density lipoprotein (HDL) cholesterol levels. Although mice lack CETP, we previously demonstrated that transgenic CETP expression in female mice alters TAG metabolism. The impact of CETP on TAG metabolism in males, however, is not well understood. Here, we demonstrate that CETP expression increases plasma TAG in males, especially in very‐low density lipoprotein (VLDL), by impairing postprandial plasma TAG clearance compared to wild‐type (WT) males. Gonadal hormones were required for CETP to impair TAG clearance, suggesting a role for sex hormones for this effect. Testosterone replacement in the setting of gonadectomy was sufficient to restore the effect of CETP on TAG. Lastly, liver androgen receptor (AR) was required for CETP to increase plasma TAG. Thus, expression of CETP in males raises plasma TAG by impairing TAG clearance via testosterone signaling to AR. Further understanding of how CETP and androgen signaling impair TAG clearance may lead to novel approaches to reduce TAG and mitigate risk of cardiovascular disease.

Lipoproteins and lipids in cardiovascular disease: from mechanistic insights to therapeutic targeting

With cardiovascular disease being the leading cause of morbidity and mortality worldwide, effective and cost-efficient therapies to reduce cardiovascular risk are highly needed. Lipids and lipoprotein particles crucially contribute to atherosclerosis as underlying pathology of cardiovascular disease and influence inflammatory processes as well as function of leukocytes, vascular and cardiac cells, thereby impacting on vessels and heart. Statins form the first-line therapy with the aim to block cholesterol synthesis, but additional lipid-lowering drugs are sometimes needed to achieve low-density lipoprotein (LDL) cholesterol target values. Furthermore, beyond LDL cholesterol, also other lipid mediators contribute to cardiovascular risk. This review comprehensively discusses low- and high-density lipoprotein cholesterol, lipoprotein (a), triglycerides as well as fatty acids and derivatives in the context of cardiovascular disease, providing mechanistic insights into their role in pathological processes impacting on cardiovascular disease. Also, an overview of applied as well as emerging therapeutic strategies to reduce lipid-induced cardiovascular burden is provided.

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.

Intra-Abdominal Fat and High Density Lipoprotein Cholesterol Are Associated in a Non-Linear Pattern in Japanese-Americans

BACKGROUND

We describe the association between high density lipoprotein cholesterol (HDL-C) concentration and computed tomography (CT)-measured fat depots.

METHODS

We examined the cross-sectional associations between HDL-C concentration and intra-abdominal (IAF), abdominal subcutaneous (SCF), and thigh fat (TF) areas in 641 Japanese-American men and women. IAF, SCF, and TF were measured by CT at the level of the umbilicus and mid-thigh. The associations between fat area measurements and HDL-C were examined using multivariate linear regression analysis adjusting for age, sex, diabetes family history, homeostasis model assessment of insulin resistance (HOMA-IR), and body mass index (BMI). Non-linearity was assessed using fractional polynomials.

RESULTS

Mean±standard deviation of HDL-C concentration and IAF in men and women were 1.30±0.34 mg/dL, 105±55.3 cm², and 1.67±0.43 mg/dL, 74.4±46.6 cm² and differed significantly by gender for both comparisons (P<0.001). In univariate analysis, HDL-C concentration was significantly associated with CT-measured fat depots. In multivariate analysis, IAF was significantly and non-linearly associated with HDL-C concentration adjusted for age, sex, BMI, HOMA-IR, SCF, and TF (IAF: β=-0.1012, P<0.001; IAF²: β=0.0008, P<0.001). SCF was also negatively and linearly associated with HDL-C (β=-0.4919, P=0.001).

CONCLUSION

HDL-C does not linearly decline with increasing IAF in Japanese-Americans. A more complex pattern better fits this association.

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.

Sugar-containing beverage consumption and cardiometabolic risk in preschool children

Objective

Sugar-containing beverages (SCBs) including 100% fruit juice, fruit drinks and soda substantially contribute to total caloric intake in young children. The objective of this study was to examine whether consumption of SCB is associated with cardiometabolic risk (CMR) in preschool children, along with whether 100% fruit juice and sugar sweetened beverage (SSB) is associated with CMR.

Study Design

We used a repeated measures study design examining SCB consumption and CMR outcomes measured concurrently in children 3-6 years of age participating in TARGet Kids!, a primary-care, practice-based research network in Canada (2008-2017). To account for within-person variability, multivariable linear regression models using generalized estimating equation was used to examine the association between SCB consumption and CMR score and the individual CMR score components including systolic blood pressure, waist circumference, high-density lipoprotein cholesterol (HDL-c), triglycerides, and glucose.

Results

After adjusting for sociodemographic, familial and child-related covariates, higher SCB consumption was associated with elevated CMR score [0.05 (95% CI -0.0001 to 0.09), p = 0.05], including lower HDL-c [-0.02 mmol/L (95% CI -0.03 to -0.01), p = 0.01] and higher triglycerides [0.02 mmol/L (95% CI 0.004 to 0.04), p = 0.02]. When examined separately, higher 100% fruit juice [-0.02 mmol/L (95% CI -0.03 to -0.003), p = 0.02] and SSB[-0.03 mmol/L (95% CI -0.06 to -0.001), p = 0.04] consumption were each associated with lower HDL-c.

Conclusion

Higher SCB consumption was associated with small elevations of CMR in preschool children. Our findings support recommendations to limit overall intake of SCBs in early childhood, in effort to reduce the potential long-term burden of CMR.

Association of High-Density Lipoprotein Particles and High-Density Lipoprotein Apolipoprotein C-III Content With Cardiovascular Disease Risk According to Kidney Function: The Multi-Ethnic Study of Atherosclerosis

Background

Chronic kidney disease is associated with structural and compositional abnormalities in high‐density lipoprotein particles (HDLp). We examined associations of HDLp size, particle subfractions, and apolipoprotein C‐III content with incident cardiovascular disease (CVD) events across categories of estimated glomerular filtration rate (eGFR).

Methods and Results

Analyses included 6699 participants in MESA (Multi‐Ethnic Study of Atherosclerosis) with measurements of HDLp and 5723 participants with measurements of HDL apolipoprotein C‐III. Cox‐regression methods were used to evaluate associations between HDLp and apolipoproteins with CVD events. Larger HDLp size was associated with lower CVD risk in participants with lower eGFR: hazard ratio (95% CI) per SD higher mean HDL size was 1.00 (0.90–1.11) in eGFR ≥60 mL/min per 1.73 m², 0.65 (0.48–0.86) in eGFR 45 to 59 mL/min per 1.73 m², and 0.48 (0.25–0.93) in eGFR <45 mL/min per 1.73 m² (P for interaction=0.05). Associations of HDLp subfractions with CVD varied significantly by eGFR (P for interaction=0.04), with significant inverse associations between higher concentrations of large HDLp and CVD events across categories of kidney function, but nonsignificant results for small HDLp. Only HDLp without apolipoprotein C‐III was associated with lower risk of CVD events, with seemingly (albeit not statistically significant) stronger associations among participants with lower eGFR (P for interaction=0.19).

Conclusions

HDL particles of larger size and higher concentrations of large HDL and of HDL without apolipoprotein C‐III were associated with lower CVD risk, with risk estimates seemingly stronger among participants with lower eGFR. Future larger studies are needed to corroborate these findings.

HDL flux is higher in patients with nonalcoholic fatty liver disease

Altered lipid metabolism and inflammation are involved in the pathogenesis of both nonalcoholic fatty liver disease (NAFLD) and cardiovascular disease (CVD). Even though high-density lipoprotein (HDL), a CVD protective marker, is decreased, whether HDL metabolism and function are perturbed in NAFLD are currently unknown. We examined the effect of NAFLD and disease severity on HDL metabolism and function in patients with biopsy-proven simple steatosis (SS), nonalcoholic steatohepatitis (NASH), and healthy controls. HDL turnover and HDL protein dynamics in SS (n = 7), NASH (n = 8), and healthy controls (n = 9) were studied in vivo. HDL maturation and remodeling, antioxidant, cholesterol efflux properties, and activities of lecithin-cholesterol ester acyltransferase and cholesterol ester transfer protein (CETP) were quantified using in vitro assays. All patients with NAFLD had increased turnover of both HDL cholesterol (HDLc; 0.16 ± 0.09 vs. 0.34 ± 0.18 days, P < 0.05) and apolipoprotein A1 (ApoAI) (0.26 ± 0.04 vs. 0.34 ± 0.06 days, P < 0.005) compared with healthy controls. The fractional catabolic rates of other HDL proteins, including ApoAII (and ApoAIV) were higher (P < 0.05) in patients with NAFLD who also had higher CETP activity, ApoAI/HDLc ratio (P < 0.05). NAFLD-induced alterations were associated with lower antioxidant (114.2 ± 46.6 vs. 220.5 ± 48.2 nmol·mL-1·min-1) but higher total efflux properties of HDL (23.4 ± 1.3% vs. 25.5 ± 2.3%) (both P < 0.05), which was more pronounced in individuals with NASH. However, no differences were observed in either HDL turnover, antioxidant, and cholesterol efflux functions of HDL or HDL proteins' turnover between subjects with SS and subjects with NASH. Thus, HDL metabolism and function are altered in NAFLD without any significant differences between SS and NASH.

Circulating Apolipoprotein L1 is associated with insulin resistance-induced abnormal lipid metabolism

Circulating ApolipoproteinL1 (ApoL1) is a component of pre-β-high-density lipoprotein (HDL), however little is known about the relationship of ApoL1 with cardiometabolic factors. Considering previous studies reporting the correlation of ApoL1 to triglyceride, we have hypothesized that ApoL1 associates with insulin-related metabolism. The current study examined their associations in 126 non-diabetic subjects and 36 patients with type 2 diabetes (T2DM). Non-diabetic subjects demonstrated triglyceride (standardized coefficients [s.c.] = 0.204, p < 0.05), body mass index (s.c. =0.232, p < 0.05) and HDL cholesterol (s.c. = −0.203, p < 0.05) as independent determinant of ApoL1 levels, and the significant elevation of ApoL1 in metabolic syndrome. Lipoprotein fractionation analysis revealed the predominant distribution of ApoL1 in large HDL fraction, and the significant increase of ApoL1 in large LDL fraction in high ApoL1 samples with insulin resistance. In T2DM, ApoL1 was higher in T2DM with metabolic syndrome, however ApoL1 was lower with β cell dysfunction. Insulin significantly promotes ApoL1 synthesis and secretion in HepG2 cells. In conclusion, circulating ApoL1 may be associated with abnormal HDL metabolism in insulin resistant status. This may suggest a regulation of insulin signal on the ApoL1 level, leading to offer a novel insight to the ApoL1 biology.

Allergic rhinitis is associated with complex alterations in high-density lipoprotein composition and function

Despite strong evidence that high-density lipoproteins (HDLs) modulate the immune response, the role of HDL in allergies is still poorly understood. Many patients with allergic rhinitis (AR) develop a late-phase response, characterized by infiltration of monocytes and eosinophils into the nasal submucosa. Functional impairment of HDL in AR-patients may insufficiently suppress inflammation and cell infiltration, but the effect of AR on the composition and function of HDL is not understood. We used apolipoprotein (apo) B-depleted serum as well as isolated HDL from AR-patients (n = 43) and non-allergic healthy controls (n = 20) for detailed compositional and functional characterization of HDL. Both AR-HDL and apoB-depleted serum of AR-patients showed decreased anti-oxidative capacity and impaired ability to suppress monocyte nuclear factor-κB expression and pro-inflammatory cytokine secretion, such as interleukin (IL)-4, IL-6, IL-8, tumor necrosis factor alpha and IL-1 beta. Sera of AR-patients showed decreased paraoxonase and cholesteryl-ester transfer protein activities, increased lipoprotein-associated phospholipase A2 activity, while lecithin-cholesterol acyltransferase activity and cholesterol efflux capacity were not altered. Surprisingly, apoB-depleted serum and HDL from AR-patients showed an increased ability to suppress eosinophil effector responses upon eotaxin-2/CCL24 stimulation. Mass spectrometry and biochemical analyses showed reduced levels of apoA-I and phosphatidylcholine, but increased levels of apoA-II, triglycerides and lyso-phosphatidylcholine in AR-HDL. The changes in AR-HDL composition were associated with altered functional properties. In conclusion, AR alters HDL composition linked to decreased anti-oxidative and anti-inflammatory properties but improves the ability of HDL to suppress eosinophil effector responses.

Residual cardiovascular risk among people with diabetes

Type 2 diabetes (T2D) is a growing health concern across both developed and developing countries. Cardiovascular disease (CVD) remains the major cause of increased mortality in this patient population. In recent years, effective low density lipoprotein lowering treatments and other risk reduction strategies have substantially reduced the risk of atherosclerotic CVD, yet patients with T2D continue to remain at increased risk for atherosclerotic CVD. Here, we will briefly review various proposed underlying mechanisms for this residual risk with a more in-depth focus on the potential role of triglyceride-rich lipoproteins in residual risk and potential avenues to target this pharmacologically.

The importance of dyslipidaemia in the pathogenesis of cardiovascular disease in people with diabetes

Atherosclerotic cardiovascular events are the leading cause of mortality and morbidity in those with diabetes. A key contributor to the development of atherosclerosis in this population is the presence of a particularly atherogenic lipid profile often referred to as 'Diabetic Dyslipidemia'. This profile is characterized by elevated triglycerides, triglyceride-rich lipoproteins, small dense LDL particles, and reduced HDL levels. This article reviews the underlying aetiology and pathophysiology of this dyslipidaemia and atherosclerosis in those with diabetes, provides insights from epidemiological and genetic studies, and current cardiovascular risk reducing interventions including novel therapies such as PCSK-9 inhibitors.

CETP Inhibition Improves HDL Function but Leads to Fatty Liver and Insulin Resistance in CETP-Expressing Transgenic Mice on a High-Fat Diet

In clinical trials, inhibition of cholesteryl ester transfer protein (CETP) raises HDL cholesterol levels but does not robustly improve cardiovascular outcomes. Approximately two-thirds of trial participants are obese. Lower plasma CETP activity is associated with increased cardiovascular risk in human studies, and protective aspects of CETP have been observed in mice fed a high-fat diet (HFD) with regard to metabolic outcomes. To define whether CETP inhibition has different effects depending on the presence of obesity, we performed short-term anacetrapib treatment in chow- and HFD-fed CETP transgenic mice. Anacetrapib raised HDL cholesterol and improved aspects of HDL functionality, including reverse cholesterol transport, and HDL's antioxidative capacity in HFD-fed mice was better than in chow-fed mice. Anacetrapib worsened the anti-inflammatory capacity of HDL in HFD-fed mice. The HDL proteome was markedly different with anacetrapib treatment in HFD- versus chow-fed mice. Despite benefits on HDL, anacetrapib led to liver triglyceride accumulation and insulin resistance in HFD-fed mice. Overall, our results support a physiologic importance of CETP in protecting from fatty liver and demonstrate context selectivity of CETP inhibition that might be important in obese subjects.

Different inverse association of large high-density lipoprotein subclasses with exacerbation of insulin resistance and incidence of type 2 diabetes: The Nagahama study

AIMS

In addition to its antiatherogenic action, high-density lipoprotein (HDL) may also have an antidiabetes function. Although the biological actions of small HDL (HDL3) and large HDL (HDL2) subclasses may be different, evidence in support of that hypothesis is lacking. The aim of this study was to clarify the difference in prognostic significance of HDL subclasses for exacerbation of insulin resistance and incidence of type 2 diabetes in the general population.

METHODS

Study participants included 8365 community residents 52±13years of age not taking lipid lowering drugs. Serum HDL cholesterol subclasses and low-density lipoprotein subclasses, were measured by a homogeneous assay. Insulin resistance was assessed by homeostasis model assessment of insulin resistance (HOMA-IR).

RESULTS

Cross-sectional analysis adjusted for possible covariates found that HDL2 cholesterol (HDL2-C) levels were inversely associated with HOMA-IR (β=-0.169, p<0.001), whereas HDL3-C had the opposite association (β=0.054, p<0.001). Similar results were found in an analysis for type 2 diabetes (HDL2-C, odds ratio=0.96, p=0.001; HDL3-C, odds ratio=1.04, p=0.181). In a longitudinal analysis with 5.0years of follow-up, HDL2-C was inversely associated with exacerbation of insulin resistance (β=-0.163, p<0.001); HDL3-C had the opposite association (β=0.026, p=0.037). During follow-up, 205 individuals were newly diagnosed with diabetes, and HDL2-C level was associated with an inverse risk of type 2 diabetes incidence (odds ratio=0.98, p=0.006).

CONCLUSIONS

HDL may have an antidiabetic function; the prognostic value of HDL2-C for diabetes and insulin resistance might be better than that of HDL3-C.

Postprandial lipemic and inflammatory responses to high-fat meals: a review of the roles of acute and chronic exercise

Postprandial lipemia is an independent risk factor for development of cardiovascular disease. Postprandial inflammation following the prolonged elevation of triglycerides occurring subsequent to ingestion of high-fat meals, provides a likely explanation for increased disease risk. Substantial evidence has shown that acute exercise is an effective modality for attenuation of postprandial lipemia following a high-fat meal. However, much of the evidence pertaining to exercise intensity, duration, and overall energy expenditure for reducing postprandial lipemia is inconsistent. The effects of these different exercise variables on postprandial inflammation is largely unknown. Long-term, frequent exercise, however, appears to effectively reduce systemic inflammation, especially in at-risk or diseased individuals. With regard to an acute postprandial response, without a recent bout of exercise, high levels of chronic exercise do not appear to reduce postprandial lipemia. This review summarizes the current literature on postprandial and inflammatory responses to high-fat meals, and the roles that both acute and chronic exercise play. This review may be valuable for health professionals who wish to provide evidence-based, pragmatic advice for reducing postprandial lipemia and cardiovascular disease risk for their patients. A brief review of proposed mechanisms explaining how high-fat meals may result in pro-inflammatory and pro-atherosclerotic environments is also included.

Effect of inflammation on HDL structure and function

PURPOSE OF REVIEW

Studies have shown that chronic inflammatory disorders, such as rheumatoid arthritis, systemic lupus erythematosus, and psoriasis are associated with an increased risk of atherosclerotic cardiovascular disease. The mechanism by which inflammation increases cardiovascular disease is likely multifactorial but changes in HDL structure and function that occur during inflammation could play a role.

RECENT FINDINGS

HDL levels decrease with inflammation and there are marked changes in HDL-associated proteins. Serum amyloid A markedly increases whereas apolipoprotein A-I, lecithin:cholesterol acyltransferase, cholesterol ester transfer protein, paraoxonase 1, and apolipoprotein M decrease. The exact mechanism by which inflammation decreases HDL levels is not defined but decreases in apolipoprotein A-I production, increases in serum amyloid A, increases in endothelial lipase and secretory phospholipase A2 activity, and decreases in lecithin:cholesterol acyltransferase activity could all contribute. The changes in HDL induced by inflammation reduce the ability of HDL to participate in reverse cholesterol transport and protect LDL from oxidation.

SUMMARY

During inflammation multiple changes in HDL structure occur leading to alterations in HDL function. In the short term, these changes may be beneficial resulting in an increase in cholesterol in peripheral cells to improve host defense and repair but over the long term these changes may increase the risk of atherosclerosis.

Clinical Scenario of the Metabolic Syndrome

The term metabolic syndrome (MeS) refers to a cluster of associated symptoms composed of impaired fasting glucose, abdominal obesity, hypertension, and dyslipidemia. MeS is associated with an increased risk of cardiovascular and diabetes-associated morbidity and mortality. The increased amount of visceral fat together with a chronic inflammatory state predisposes to the development of arteriosclerosis. Furthermore, insulin resistance (IR) and dyslipidemia are associated with fatty liver disease. In addition, MeS is linked to non-cardiovascular diseases such as cancer as well as psychiatric or endocrine disorders. Here, we discuss the clinical impact of MeS in cardiovascular and non-cardiovascular diseases to highlight the importance of prevention, early diagnosis, and multifactorial treatment of high-risk individuals.

Cholesteryl ester transfer protein alters liver and plasma triglyceride metabolism through two liver networks in female mice

Elevated plasma TGs increase risk of cardiovascular disease in women. Estrogen treatment raises plasma TGs in women, but molecular mechanisms remain poorly understood. Here we explore the role of cholesteryl ester transfer protein (CETP) in the regulation of TG metabolism in female mice, which naturally lack CETP. In transgenic CETP females, acute estrogen treatment raised plasma TGs 50%, increased TG production, and increased expression of genes involved in VLDL synthesis, but not in nontransgenic littermate females. In CETP females, estrogen enhanced expression of small heterodimer partner (SHP), a nuclear receptor regulating VLDL production. Deletion of liver SHP prevented increases in TG production and expression of genes involved in VLDL synthesis in CETP mice with estrogen treatment. We also examined whether CETP expression had effects on TG metabolism independent of estrogen treatment. CETP increased liver β-oxidation and reduced liver TG content by 60%. Liver estrogen receptor α (ERα) was required for CETP expression to enhance β-oxidation and reduce liver TG content. Thus, CETP alters at least two networks governing TG metabolism, one involving SHP to increase VLDL-TG production in response to estrogen, and another involving ERα to enhance β-oxidation and lower liver TG content. These findings demonstrate a novel role for CETP in estrogen-mediated increases in TG production and a broader role for CETP in TG metabolism.

Clinical Significance of Determining Plasma MicroRNA33b in Type 2 Diabetic Patients with Dyslipidemia

Aim: Sterol regulatory element-binding protein (SREBP)-1c is the dominant liver insulin-stimulated isoform and strongly correlates with diabetic dyslipidemia characterized by hyperinsulinemia [i.e., high-density lipoprotein cholesterol (HDL-C) levels and hypertriglyceridemia]. MicroRNA (miRNA) 33b is harbored in the intron of SREBP-1c and represses ATP-binding cassette, sub-family A, and member 1 (ABCA1) expression, essential for HDL formation. We measured plasma miRNA33b levels as possible biomarkers for diabetic dyslipidemia in patients with type 2 diabetes mellitus (T2DM) showing insulin resistance.

Methods: The participants included 50 patients with T2DM (M/F 31/19) enrolled in an educational program for controlling blood glucose levels at Hirosaki University Hospital. HbA1c, fasting plasma glucose, insulin, and lipid levels were determined. Plasma miRNA33b, miRNA33a and miRNA148a were quantified using a TaqMan^® MicroRNA Assay, and values were corrected with reference to miRNA16.

Results: Mean BMI of participants were 28.2 ± 6.6 (kg/m²) and the Homeostasis Model Assessment of Insulin Resistance was 4.3 ± 2.7. Patients' laboratory findings indicated diabetic dyslipidemia with insulin resistance. Plasma miRNA33b/16 levels revealed a positive correlation with plasma insulin level (r = 0.326, P = 0.021), serum C-peptide (r = 0.280, P = 0.049), and triglyceride (r = 0.351, P = 0.012), but no association with HDL-C (r = −0.210, P = 0.143). The blood level of miRNA33a was approximately 1/150th of that of miRNA33b and was not correlated with the above parameters.

Conclusion: We postulated that plasma miRNA33b may be useful as a new metabolic biomarker of dyslipidemia in patients with T2DM as well as metabolic syndrome via an insulin/SREBP-1c/miRNA33b/ABCA1 pathway.

In vivo triglyceride synthesis in subcutaneous adipose tissue of humans correlates with plasma HDL parameters

BACKGROUNDS AND AIMS

Low concentrations of plasma HDL-C are associated with the development of atherosclerotic cardiovascular diseases and type 2 diabetes. Here we aimed to explore the relationship between the in vivo fractional synthesis of triglycerides (fTG) in subcutaneous (s.q.) abdominal adipose tissue (AT), HDL-C concentrations and HDL particle size composition in non-diabetic humans.

METHODS

The fTG in s.q. abdominal AT was measured in 16 non-diabetic volunteers (7 women, 9 men; Age: 49 ± 20 years; BMI: 31 ± 5 kg/m; Fasting Plasma Glucose: 90 ± 10 mg/dl) after (2)H2O labeling. HDL-C concentration and subclasses, large (L-HDL), intermediate (I-HDL) and small (S-HDL) were measured.

RESULTS

Linear regression analyses demonstrated significant associations of fTG with plasma concentration of HDL-C (r = 0.625,p = 0.009) and percent contribution of L-HDL (r = 0.798,p < 0.001), I-HDL (r = -0.765,p < 0.001) and S-HDL (r = -0.629, p = 0.009). When analyses were performed by gender, the associations remained significant in women (HDL-C: r = 0.822,p = 0.023; L-HDL: r = 0.892,p = 0.007; I-HDL: r = -0.927,p = 0.003) but not men.

CONCLUSIONS

Our study demonstrated an in vivo association between subcutaneous abdominal adipose tissue lipid dynamics and HDL parameters in humans, but this was true for women not men. Positive association with L-HDL and negative with I-HDL suggest that subcutaneous abdominal adipose tissue lipid dynamics may play an important role in production of mature functional HDL particles. Further studies evaluating the mechanism responsible for these associations and the observed gender differences are important and warranted to identify potential novel targets of intervention to increase the production of atheroprotective subclasses of HDL-Cs and thus decreasing the risks of development of atherosclerotic conditions.

Cholesteryl Ester Transfer Protein Inhibition With Anacetrapib Decreases Fractional Clearance Rates of High-Density Lipoprotein Apolipoprotein A-I and Plasma Cholesteryl Ester Transfer Protein

OBJECTIVE

Anacetrapib (ANA), an inhibitor of cholesteryl ester transfer protein (CETP) activity, increases plasma concentrations of high-density lipoprotein cholesterol (HDL-C), apolipoprotein A-I (apoA)-I, apoA-II, and CETP. The mechanisms responsible for these treatment-related increases in apolipoproteins and plasma CETP are unknown. We performed a randomized, placebo (PBO)-controlled, double-blind, fixed-sequence study to examine the effects of ANA on the metabolism of HDL apoA-I and apoA-II and plasma CETP.

APPROACH AND RESULTS

Twenty-nine participants received atorvastatin (ATV) 20 mg/d plus PBO for 4 weeks, followed by ATV plus ANA 100 mg/d for 8 weeks (ATV-ANA). Ten participants received double PBO for 4 weeks followed by PBO plus ANA for 8 weeks (PBO-ANA). At the end of each treatment, we examined the kinetics of HDL apoA-I, HDL apoA-II, and plasma CETP after D3-leucine administration as well as 2D gel analysis of HDL subspecies. In the combined ATV-ANA and PBO-ANA groups, ANA treatment increased plasma HDL-C (63.0%; P<0.001) and apoA-I levels (29.5%; P<0.001). These increases were associated with reductions in HDL apoA-I fractional clearance rate (18.2%; P=0.002) without changes in production rate. Although the apoA-II levels increased by 12.6% (P<0.001), we could not discern significant changes in either apoA-II fractional clearance rate or production rate. CETP levels increased 102% (P<0.001) on ANA because of a significant reduction in the fractional clearance rate of CETP (57.6%, P<0.001) with no change in CETP production rate.

CONCLUSIONS

ANA treatment increases HDL apoA-I and CETP levels by decreasing the fractional clearance rate of each protein.

The effect of moderate intensity exercise in the postprandial period on the inflammatory response to a high-fat meal: an experimental study

Background

Consuming a high-fat meal (HFM) may lead to postprandial lipemia (PPL) and inflammation. Postprandial exercise has been shown to effectively attenuate PPL. However, little is known about the impact of postprandial exercise on systemic inflammation and whether PPL and inflammation are associated. The purpose of this study was to determine whether moderate intensity exercise performed 60 min following a true-to-life HFM would attenuate PPL and inflammation.

Methods

Thirty-nine young adults (18–40 year) with no known metabolic disease were randomized to either a control group (CON) who remained sedentary during the postprandial period or an exercise (EX) group who walked at 60 % VO_2peak to expend ≈ 5 kcal/kgbw one-hour following the HFM. Participants consumed a HFM of 10 kcal/kgbw and blood draws were performed immediately before, 2 h and 4 h post-HFM.

Results

At baseline, there were no differences between EX and CON groups for any metabolic or inflammatory markers (p > 0.05). Postprandial triglycerides (TRG) increased from baseline to 4 h in the EX and CON groups (p < 0.001), with no differences between groups (p = 0.871). High density lipoprotein cholesterol (HDL-C) decreased in both groups across time (p < 0.001) with no differences between groups (p = 0.137). Interleukin-6 (IL-6) was significant as a quadratic function over time (p = 0.005), decreasing from baseline to 2 h then increasing and returning to baseline at 4 h in all participants with no difference between groups (p = 0.276). Tumor necrosis factor-alpha (TNF-α) was not different from baseline to 4 h between groups (p > 0.05). There was an increase in soluble vascular adhesion molecule (sVCAM-1) from baseline to 4 h (p = 0.027) for all participants along with a group x time interaction (p = 0.020). Changes in TRG were associated with changes in interleukin-10 (IL-10) from 0 to 2 h (p = 0.007), but were not associated with changes in any other inflammatory marker in the postprandial period (p > 0.05).

Conclusions

Despite significant increases in PPL following a HFM, moderate intensity exercise in the postprandial period did not mitigate the PPL nor the inflammatory response to the HFM. These results indicate that in populations with low metabolic risk, PPL and inflammation following a HFM may not be directly related.

A patient with a novel homozygous missense mutation in FTO and concomitant nonsense mutation in CETP

The fat mass and obesity associated gene (FTO) has previously been associated with a variety of diseases and conditions, notably obesity, acute coronary syndrome and metabolic syndrome. Reports describing mutations in FTO as well as FTO animal models have further demonstrated a role for FTO in the development of the brain and other organs. Here, we describe a patient born of consanguineous union who presented with microcephaly, developmental delay, behavioral abnormalities, dysmorphic facial features, hypotonia, and other various phenotypic abnormalities. Whole exome sequencing revealed a novel homozygous missense mutation in FTO and a nonsense mutation in the cholesteryl ester transfer protein (CETP). Exome CNV analysis revealed no disease causing large duplications or deletions within coding regions. Patient’s, her parents’ and non-related control’ fibroblasts were analyzed for morphologic defects, abnormal proliferation, apoptosis and transcriptome profile. We have shown that FTO is located in nucleus of cells from each tested samples. Western blot analysis demonstrated no changes in patient FTO. Q-PCR analysis revealed slightly decreased levels of FTO expression in patient cells compared to controls. No morphological or proliferation differences between the patient and control fibroblasts were observed. There is still much to be learned about the molecular mechanisms by which mutations in FTO contribute to such severe phenotypes.

Targeting inflammation in metabolic syndrome

The metabolic syndrome (MetS) is comprised of a cluster of closely related risk factors, including visceral adiposity, insulin resistance, hypertension, high triglyceride, and low high-density lipoprotein cholesterol; all of which increase the risk for the development of type 2 diabetes and cardiovascular disease. A chronic state of inflammation appears to be a central mechanism underlying the pathophysiology of insulin resistance and MetS. In this review, we summarize recent research which has provided insight into the mechanisms by which inflammation underlies the pathophysiology of the individual components of MetS including visceral adiposity, hyperglycemia and insulin resistance, dyslipidemia, and hypertension. On the basis of these mechanisms, we summarize therapeutic modalities to target inflammation in the MetS and its individual components. Current therapeutic modalities can modulate the individual components of MetS and have a direct anti-inflammatory effect. Lifestyle modifications including exercise, weight loss, and diets high in fruits, vegetables, fiber, whole grains, and low-fat dairy and low in saturated fat and glucose are recommended as a first line therapy. The Mediterranean and dietary approaches to stop hypertension diets are especially beneficial and have been shown to prevent development of MetS. Moreover, the Mediterranean diet has been associated with reductions in total and cardiovascular mortality. Omega-3 fatty acids and peroxisome proliferator-activated receptor α agonists lower high levels of triglyceride; their role in targeting inflammation is reviewed. Angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and aldosterone blockers comprise pharmacologic therapies for hypertension but also target other aspects of MetS including inflammation. Statin drugs target many of the underlying inflammatory pathways involved in MetS.

Oral L-Arginine Administration Improves Anthropometric and Biochemical Indices Associated With Cardiovascular Diseases in Obese Patients: A Randomized, Single Blind Placebo Controlled Clinical Trial

BACKGROUND

Recently, the potential of L-arginine supplementation as a novel and effective strategy for weight loss and improving biochemical parameters in obese patients has been under consideration.

OBJECTIVES

To evaluate the influence of 8-week oral L-arginine supplementation on body mass index (BMI), waist circumference (WC), triceps skinfold (TS), subscapular skinfold (SS), systolic blood pressure (SBP), diastolic blood pressure (DBP), plasma fasting blood sugar (FBS), glycated hemoglobin (HbA1c), triglyceride (TG), total cholesterol (TC), low-density lipoprotein (LDL), high-density lipoprotein (HDL), and malondialdehyde (MDA) in patients with BMI values > 29.9 or visceral obesity (WC > 102 cm in men or > 88 cm in women).

PATIENTS AND METHODS

Ninety obese patients were included in a single-blind randomized controlled trial. Patients were randomized to receive either L-arginine (3 or 6 g thrice daily) or placebo for 8 weeks. Anthropometric and biochemical indices, dietary intake, and blood pressure values were measured at the baseline and after the 8-week intervention.

RESULTS

Significant decreases in anthropometric parameters, blood pressure (SBP, DBP), FBS, HbA1c, LDL, MDA (P < 0.001), TG (P = 0.02), and TC (P = 0.002) and a significant increase in HDL (P < 0.001) were observed in the intervention group, compared to the control group. In the control group, no significant differences were found between the baseline and end-of-intervention measurements.

CONCLUSIONS

In conclusion, oral L-Arginine supplementation appears to improve anthropometric parameters, blood pressure values, and some blood biochemical indices associated with cardiovascular disease prevention.

Study to assess whether waist circumference and changes in serum glucose and lipid profile are independent variables for the CETP gene

AIMS

To observe the relationship among genes, obesity and the changes in serum glucose and lipid profile to assess whether obesity-related disease results from genes and/or obesity.

METHODS

Correlations among serum glucose, lipids, waist circumference (WC), and Taq1B, I405V, and D442G polymorphisms of the cholesteryl ester transfer protein (CETP) gene were assessed. Logistic regression analysis was used to screen independent variables among obesity-related anthropometric indexes and serum biochemical indicators for genes.

RESULTS

The waist circumference density index (WCDI) may be attributed to changes in serum biochemical indicators and among WCDI, BMI and serum biochemical indicators, however, only WCDI was an independent variable for the G allele. Differences were observed in anthropometric indexes and serum biochemical indicators between subjects with the G allele and those without (p<0.05).

CONCLUSION

Abdominal obesity and changes in serum glucose and lipid profile are affected by a group of genes, including CETP. Correlation of the CETP gene with waist circumference may be independent compared with serum glucose and lipid profile.

Prior exercise and postprandial incretin responses in lean and obese individuals

PURPOSE

The incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) help regulate postprandial triacylglycerol (TAG) and insulin concentrations, but the effects of acute aerobic exercise on GLP-1 or GIP responses are unclear. The purpose of this study was to determine whether reductions in postprandial TAG and insulin with exercise are associated with GLP-1 and GIP responses.

METHODS

Thirteen normal-weight (NW) and 13 obese (Ob) individuals participated in two, 4-d trials in random order including an exercise (EX) and a no exercise (NoEX) trial. Diet was controlled during both trials. The EX trial consisted of 1 h of treadmill walking (55%-60% of V˙O2peak) during the evening of day 3 of the trial, 12 h before a 4-h mixed meal test on day 4, during which frequent blood samples were collected to assess postprandial lipemia, glycemia, insulin, C-peptide, GIP, and GLP-1 responses. Insulin secretion was estimated using the insulinogenic index, and insulin clearance was estimated using the ratio of insulin to C-peptide.

RESULTS

Postprandial TAG were 29% lower after EX in Ob individuals (P < 0.05) but were not significantly altered in NW individuals (P > 0.05). The drop in postprandial HDL cholesterol was attenuated with EX in Ob individuals (P < 0.05). Insulin responses were 14% lower after EX in Ob individuals (P < 0.05), and this was associated with reduced insulin secretion (P < 0.05), with no change in insulin clearance (P > 0.05). Glucose, C-peptide, GIP, and GLP-1 were not different between trials.

CONCLUSION

A 1-h bout of moderate-intensity aerobic exercise the night before a mixed meal attenuates TAG and insulin responses in Ob but not NW individuals, an effect not associated with altered GLP-1 or GIP responses.

Gene-gene interaction between CETP and APOE polymorphisms confers higher risk for hypertriglyceridemia in oldest-old Chinese women

The knowledge of dyslipidemia and its genetic contributors in oldest-old subjects is limited; in addition, the majority of oldest-old subjects are females. Evidence has accumulated that multiple genetic factors play important roles in determining susceptibility to dyslipidemia and extended life span. Cholesterol ester transfer protein (CETP) and apolipoprotein E (APOE) are two plausible candidate genes for human longevity owing to their functionally related modulation of circulating lipid homeostasis; however, few studies have considered their interplay. In this study, we analyzed the distribution of CETP*V (rs5882) and APOE*4 (rs429358 and rs7412) in 372 oldest-old Chinese women (aged 80-109) and 340 controls (aged 20-58). In addition to replicating the association of longevity, our main goal was to evaluate the contribution of CETP*V, APOE*4 and CETP*APOE interaction to the risk of dyslipidemia. Only APOE*4 conferred a risk against longevity and was associated with high-cholesterol (hTC) and mixed dyslipidemia for oldest-old females. Moreover, CETP*V was found to be associated with hypertriglyceridemia (hTG) independently from APOE*4, age, BMI, alcohol drinking, TC, TG, HDL-c, and LDL-c. The stratification test, multivariable-adjusted logistic regression, and nonparametric MDR analysis all suggested a significant CETP*APOE interaction associated with hTG. The unadjusted odds for hTG were more than 4-fold in subjects with CETP*V and APOE*4 than those without either (OR=4.36, P<0.001). These results provide evidence of strong independent associations between hTG and CETP*V in oldest-old Chinese females, and APOE*4, as an independently non-significant variant, might interact with CETP*V resulting in an increased risk for hTG.

Elevated cholesteryl ester transfer protein (CETP) activity, a major determinant of the atherogenic dyslipidemia, and atherosclerotic cardiovascular disease in South Asians

AIMS

Why South Asians are at increased risk of premature atherosclerotic cardiovascular diseases compared with other ethnic groups is not fully understood. Atherogenic dyslipoproteinemia - hypertriglyceridemia, elevated numbers of low-density lipoprotein (LDL) particles and low high-density lipoprotein cholesterol (HDL-C) - is more common in South Asians but the mechanisms responsible have not been explicated. Here we examined whether the circulating lipid transfer protein, cholesteryl ester transfer protein (CETP), plays a role in the pathogenesis of the atherogenic dyslipoproteinemia among South Asians.

METHODS AND RESULTS

CETP activity was determined by exogenous substrate assay in the serum of healthy, metabolically well-characterized individuals of South Asian and European descent (N = 244 and 238, respectively). Serum and lipoprotein lipids and apolipoproteins were measured and lipoprotein particle number and size were quantified via nuclear magnetic resonance spectroscopy. All the elements of the atherogenic dyslipoproteinemia were more severe in South Asians and CETP activity was significantly greater by 30% in South Asians compared with Europeans, adjusted for age, sex, body mass index and waist circumference (p < 0.0001). CETP activity was directly associated with serum triglycerides and inversely with HDL-C in the whole population. CETP activity was also directly related to apoB and LDL particle number. Finally, increased CETP activity was associated with pro-atherogenic reductions in HDL and LDL particle size.

CONCLUSIONS

We identified novel associations between elevated CETP activity and the triad of quantitative and qualitative lipoprotein abnormalities in the atherogenic dyslipidemia in South Asians, a major contributor of increased atherosclerotic cardiovascular diseases in South Asians.

How do elevated triglycerides and low HDL-cholesterol affect inflammation and atherothrombosis?

This review article summarizes recent research into the mechanisms as to how elevated levels of triglyceride (TG) and low levels of high- density- lipoprotein cholesterol (HDL-C) contribute to inflammation and atherosclerosis. Evidence supports the role of TG-rich lipoproteins in signaling mechanisms via apolipoproteins C-III and free fatty acids leading to activation of NFKβ, VCAM-1 and other inflammatory mediators which lead to fatty streak formation and advanced atherosclerosis. Moreover, the cholesterol content in TG-rich lipoproteins has been shown to predict CAD risk better than LDL-C. In addition to reverse cholesterol transport, HDL has many other cardioprotective effects which include regulating immune function. The "functionality" of HDL appears more important than the level of HDL-C. Insulin resistance and central obesity underlie the pathophysiology of elevated TG and low HDL-C in metabolic syndrome and type 2 diabetes. Lifestyle recommendations including exercise and weight loss remain first line therapy in ameliorating insulin resistance and the adverse signaling processes from elevated levels of TG-rich lipoproteins and low HDL-C.

Comparison of the serum lipidome in patients with abdominal aortic aneurysm and peripheral artery disease

BACKGROUND

Currently, the relationship between circulating lipids and abdominal aortic aneurysm (AAA) is unclear. We conducted a lipidomic analysis to identify serum lipids associated with AAA presence. Secondary analyses assessed the ability of models incorporating lipidomic features to improve stratification of patient groups with and without AAA beyond traditional risk factors.

METHODS AND RESULTS

Serum lipids were profiled via liquid chromatography tandem mass spectrometry analysis of serum from 161 patients with AAA and 168 controls with peripheral artery disease. Binary logistic regression was used to identify AAA-associated lipids. Classification models were created based on a combination of (1) traditional risk factors only or (2) lipidomic features and traditional risk factors. Model performance was assessed using receiver operator characteristic curves. Three diacylglycerols and 7 triacylglycerols were associated with AAA. Combining lipidomic features with traditional risk factors significantly improved stratification of AAA and peripheral artery disease groups when compared with traditional risk factors alone (mean area under the receiver operator characteristic curve [95% confidence interval], 0.760 [0.756-0.763] and 0.719 [0.716-0.723], respectively; P<0.05).

CONCLUSIONS

A group of linoleic acid containing triacylglycerols and diacylglycerols were significantly associated with AAA presence. Inclusion of lipidomic features in multivariate analyses significantly improved prediction of AAA presence when compared with traditional risk factors alone.

Chronic Hyperinsulinemia Does Not Increase the Production Rate of High-Density Lipoprotein Apolipoprotein AI

Objective—

In vitro studies showed that insulin stimulates the production of apolipoprotein AI (apoAI). Thus, we hypothesized that chronic hyperinsulinemia could contribute to the increase in the production of high-density lipoprotein apoAI that is observed in metabolic syndrome.

Approach and Results—

We performed an in vivo kinetic study with stable isotope in 7 patients with insulinoma who showed hyperinsulinemia but no insulin resistance, 8 patients with insulin resistance, and 16 controls. Insulinemia was 3.1× ( P <0.01) higher in patients with insulinoma or insulin resistance than in controls in the fasting state and, respectively, 3.5× and 2.6× ( P <0.05) higher in the fed state. The high-density lipoprotein apoAI pool size was smaller in patients with insulin resistance than in controls (49.3±5.4 versus 59.6±7.7 mg·kg −1 ; P <0.01), whereas both the high-density lipoprotein apoAI fractional catabolic rate and the high-density lipoprotein apoAI production rate were higher (0.30±0.07 versus 0.20±0.04 pool·d −1 ; P <0.0001 and 14.6±1.5 versus 11.5±1.9 mg·kg −1 ·d −1 ; P <0.01, respectively). In contrast, no significant difference was observed for these parameters between patients with insulinoma and controls. In patients with insulinoma, the apoAI pool size tended to be greater than in patients with insulin resistance (56.3±8.6 versus 49.3±5.4 mg·kg −1 ; P =0.078), whereas both the apoAI fractional catabolic rate and the production rate were lower (0.20±0.06 versus 0.30±0.07 pool·d −1 ; P <0.01 and 11.1±1.6 versus 14.6±1.5 mg·kg −1 ·d −1 ; P <0.01, respectively). The apoAI fractional catabolic rate was the only variable associated with the apoAI production rate in multivariate analysis and explained 80% of its variance.

Conclusions—

Chronic endogenous hyperinsulinemia does not induce any increase in the apoAI production rate, which seems to be more dependent on the apoAI fractional catabolic rate.