Alterations in the high density lipoprotein phenotype and HDL-associated enzymes in subjects with metabolic syndrome. Lipids. 2009;44:9-16. [PMID: 18956219 DOI: 10.1007/s11745-008-3251-9]

HDL-C criterion of the metabolic syndrome and future diabetes and atherosclerosis in midlife women: The SWAN Study

Objective

High-density lipoprotein cholesterol (HDL-C) is one of 5 components [high blood pressure, glucose, triglycerides, waist circumference, low HDL-C], 3 of which, needed to diagnose metabolic syndrome (MetS). Evolving research shows that higher HDL-C is not necessarily cardioprotective in midlife women, supporting a need to re-evaluate HDL-C's contribution to risks related to MetS. We tested whether risk of future diabetes and higher carotid intima-media thickness (cIMT) differ by HDL-C status in midlife women diagnosed with MetS based on the other 4 components.

Methods Midlife women were classified into 3 groups

1) no MetS, 2) MetS with HDL-C ≥ 50 mg/dL (MetS hiHDL), and 3) MetS with HDL-C < 50 mg/dL (MetS loHDL). cIMT was measured 13.8 ± 0.6 years post baseline. Incident diabetes was assessed yearly.

Results

Among 2773 women (1350 (48 %) of them had cIMT), 2383 (86 %) had no MetS, 117 (4 %) had MetS hiHDL, 273 (10 %) had MetS loHDL. Compared with no MetS, both MetS- hiHDL and loHDL groups had higher cIMT and diabetes risk. Risk of having high cIMT did not differ between MetS loHDL vs. hiHDL groups. Adjusting for levels of MetS criteria other than HDL-C at baseline explained the associations of each of the two MetS groups with cIMT. Conversely, after adjustment, associations of MetS hiHDL and MetS loHDL with incident diabetes persisted.

Conclusions

In midlife women, HDL-C status matters for predicting risk of incident diabetes but not higher cIMT beyond other MetS components.

HDL abnormalities in type 2 diabetes: Clinical implications

Atherosclerotic cardiovascular disease (ASCVD) represents the primary cause of mortality among patients with Type 2 Diabetes Mellitus (T2DM). In this population, High-Density Lipoprotein (HDL) particles exhibit abnormalities in number, composition, and function, culminating in diminished anti-atherosclerotic capabilities despite normal HDL cholesterol (HDL-C) concentrations. Hyperglycemic conditions contribute to these alterations in HDL kinetics, composition, and function, causing T2DM patients' HDL particles to exhibit decreased concentrations of diverse lipid species and proteins. Treatment of hyperglycemia has the potential to correct abnormal HDL particle attributes in T2DM; however, pharmacological interventions, including metformin and thiazolidinediones, yield inconsistent outcomes with respect to HDL-C concentrations and functionality. Despite numerous attempts with diverse drugs, pharmacologically augmenting HDL-C levels has not resulted in clinical benefits in mitigating ASCVD risk. In contrast, reducing Low Density Lipoprotein cholesterol (LDL-C) via statins and ezetimibe has demonstrated significant efficacy in curtailing CVD risk among T2DM individuals. Promising results have been observed in animal models and early-phase trials utilizing recombinant HDL and Lecitin Cholesterol Acyl Transferase (LCAT) -enhancing agents, but the evaluation of their efficacy and safety in large-scale clinical trials is ongoing. While aberrant HDL metabolism constitutes a prevalent aspect of dyslipidemia in T2DM, HDL cholesterol concentrations and composition no longer offer valuable insights for informing therapeutic decisions. Nevertheless, HDL metabolism remains a critical research area in T2DM, necessitating further investigation to elucidate the role of HDL particles in the development of diabetes-associated complications.

The Association of HDL2b with Metabolic Syndrome Among Normal HDL-C Populations in Southern China

Background

The annual prevalence of metabolic syndrome (MetS) is increasing. Therefore, early screening and recognition of MetS are critical. This study aimed to evaluate the association between high-density lipoprotein (HDL) subclasses and MetS and to examine whether they could serve as early indicators in a Chinese community-based population with normal high-density lipoprotein cholesterol (HDL-C) levels.

Methods

We used microfluidic chip technology to measure HDL subclasses in 463 people with normal HDL levels in 2018. We assessed how HDL subclasses correlated with and predicted insulin resistance (IR) and metabolic syndrome (MetS), evaluated by homeostatic model insulin resistance index (HOMA-IR) and the 2009 International Diabetes Federation (IDF), the American Heart Association (AHA), and the National Heart, Lung, and Blood Institute (NHLBI) criteria, respectively. We used correlation tests and ROC curves for the analysis.

Results

The results indicate that there was a negative association between HDL2b% and the risk of IR and MetS in both sexes. Subjects in the highest quartile of HDL2b% had a significantly lower prevalence of IR and MetS than those in the lowest quartile (P<0.01). Correlation analysis between HDL2b% and metabolic risk factors showed that HDL2b% had a stronger association with these factors than HDL-C did in both sexes. ROC curve analysis also showed that HDL2b% had significant diagnostic value for IR and MetS compared to other lipid indicators.

Conclusion

This study showed that MetS alters the distribution of HDL subclasses even when HDL-C levels are within the normal range. HDL-2b% has better diagnostic value for IR and MetS than HDL-C alone and may be a useful marker for early screening.

Nonalcoholic Fatty Pancreas Disease: Role in Metabolic Syndrome, "Prediabetes," Diabetes and Atherosclerosis

Fat accumulation in the pancreas associated with obesity and the metabolic syndrome (MetS) has been defined as "non-alcoholic fatty pancreas disease" (NAFPD). The aim of this review is to describe the association of NAFPD with obesity, MetS, type 2 diabetes mellitus (T2DM) and atherosclerosis and also increase awareness regarding NAFPD. Various methods are used for the detection and quantification of pancreatic fat accumulation that may play a significant role in the differences that have been observed in the prevalence of NAFPD. Endoscopic ultrasound provides detailed images of the pancreas and its use is expected to increase in the future. Obesity and MetS have been recognized as NAFPD risk factors. NAFPD is strongly associated with non-alcoholic fatty liver disease (NAFLD) and it seems that the presence of both may be related with aggravation of NAFLD. A role of NAFPD in the development of "prediabetes" and T2DM has also been suggested by most human studies. Accumulation of fat in pancreatic tissue possibly initiates a vicious cycle of beta-cell deterioration and further pancreatic fat accumulation. Additionally, some evidence indicates a correlation between NAFPD and atherosclerotic markers (e.g., carotid intima-media thickness). Weight loss and bariatric surgery decreases pancreatic triglyceride content but pharmacologic treatments for NAFPD have not been evaluated in specifically designed studies. Hence, NAFPD is a marker of local fat accumulation possibly associated with beta-cell function impairment, carbohydrate metabolism disorders and atherosclerosis.

HDL in Atherosclerotic Cardiovascular Disease: In Search of a Role

For a long time, high-density lipoprotein cholesterol (HDL-C) has been regarded as a cardiovascular disease (CVD) protective factor. Recently, several epidemiological studies, while confirming low plasma levels of HDL-C as an established predictive biomarker for atherosclerotic CVD, indicated that not only people at the lowest levels but also those with high HDL-C levels are at increased risk of cardiovascular (CV) mortality. This “U-shaped” association has further fueled the discussion on the pathophysiological role of HDL in CVD. In fact, genetic studies, Mendelian randomization approaches, and clinical trials have challenged the notion of HDL-C levels being causally linked to CVD protection, independent of the cholesterol content in low-density lipoproteins (LDL-C). These findings have prompted a reconsideration of the biological functions of HDL that can be summarized with the word “HDL functionality”, a term that embraces the many reported biological activities beyond the so-called reverse cholesterol transport, to explain this lack of correlation between HDL levels and CVD. All these aspects are summarized and critically discussed in this review, in an attempt to provide a background scenario for the “HDL story”, a lipoprotein still in search of a role.

Lipoprotein Lipase Inhibitor, Nordihydroguaiaretic Acid, Aggravates Metabolic Phenotypes and Alters HDL Particle Size in the Western Diet-Fed db/db Mice

Lipoprotein lipase (LPL) hydrolyzes triglycerides in lipoprotein to supply fatty acids, and its deficiency leads to hypertriglyceridemia, thereby inducing metabolic syndrome (MetSyn). Nordihydroguaiaretic acid (NDGA) has been recently reported to inhibit LPL secretion by endoplasmic reticulum (ER)-Golgi redistribution. However, the role of NDGA on dyslipidemia and MetSyn remains unclear. To address this question, leptin receptor knock out (KO)-db/db mice were randomly assigned to three different groups: A normal AIN76-A diet (CON), a Western diet (WD) and a Western diet with 0.1% NDGA and an LPL inhibitor, (WD+NDGA). All mice were fed for 12 weeks. The LPL inhibition by NDGA was confirmed by measuring the systemic LPL mass and adipose LPL gene expression. We investigated whether the LPL inhibition by NDGA alters the metabolic phenotypes. NDGA led to hyperglycemia, hypertriglyceridemia, and hypercholesterolemia. More strikingly, the supplementation of NDGA increased the percentage of high density lipoprotein (HDL)_small (HDL_3a+3b+3c) and decreased the percentage of HDL_large (HDL_2a+2b) compared to the WD group, which indicates that LPL inhibition modulates HDL subclasses. was NDGA increased adipose inflammation but had no impact on hepatic stress signals. Taken together, these findings demonstrated that LPL inhibition by NDGA aggravates metabolic parameters and alters HDL particle size.

Association between high-density lipoprotein subfractions and low-grade inflammation, insulin resistance, and metabolic syndrome components: The ELSA-Brasil study

BACKGROUND

High-density lipoprotein cholesterol (HDL-C) can be divided into subfractions, which may have variable effects in atherogenesis. The results about the association between HDL-C subfractions and risk factors for cardiovascular disease are mixed.

OBJECTIVE

The objective of this study was to analyze the association between HDL-C subfractions and each metabolic syndrome component, homeostasis model assessment-estimated insulin resistance (HOMA-IR) and C-reactive protein (CRP).

METHODS

Four thousand five hundred thirty-two individuals between 35 and 74 years old without previous manifest cardiovascular disease not using fibrates were enrolled. HDL-C subfractions were separated by vertical ultracentrifugation (vertical auto profile-in mg/dL) into HDL₂-C and HDL₃-C. HDL₂-C/HDL₃-C ratio, HOMA-IR, and high-sensitivity CRP were also included in the analysis.

RESULTS

Mean age of participants was 51 ± 9 years, and 54.8% were women. In univariate analysis, HDL-C, HDL₂-C, and HDL₃-C were all inversely associated with each of the metabolic syndrome defining factors, HOMA-IR values, and serum CRP. We also observed a negative association between HDL₂-C/HDL₃-C ratio with the variables aforementioned even after adjusting for smoking, alcohol use, physical activity, and HDL-C levels (P < .01).

CONCLUSION

HDL-C and its subfractions (HDL₂-C and HDL₃-C) are inversely associated with the defining features of metabolic syndrome, insulin resistance, and systemic inflammation. In addition, the HDL₂-C/HDL₃-C ratio measured by vertical auto profile is significantly associated with the former factors even after comprehensive adjustment for HDL-C and other confounding variables.

Maternal Gestational Diabetes Mellitus increases placental and foetal lipoprotein-associated Phospholipase A2 which might exert protective functions against oxidative stress

Increased Lipoprotein associated phospholipase A2 (LpPLA2) has been associated with inflammatory pathologies, including Type 2 Diabetes. Studies on LpPLA2 and Gestational Diabetes Mellitus (GDM) are rare, and have focused mostly on maternal outcome. In the present study, we investigated whether LpPLA2 activity on foetal lipoproteins is altered by maternal GDM and/or obesity (a major risk factor for GDM), thereby contributing to changes in lipoprotein functionality. We identified HDL as the major carrier of LpPLA2 activity in the foetus, which is in contrast to adults. We observed marked expression of LpPLA2 in placental macrophages (Hofbauer cells; HBCs) and found that LpPLA2 activity in these cells was increased by insulin, leptin, and pro-inflammatory cytokines. These regulators were also increased in plasma of children born from GDM pregnancies. Our results suggest that insulin, leptin, and pro-inflammatory cytokines are positive regulators of LpPLA2 activity in the foeto-placental unit. Of particular interest, functional assays using a specific LpPLA2 inhibitor suggest that high-density lipoprotein (HDL)-associated LpPLA2 exerts anti-oxidative, athero-protective functions on placental endothelium and foetus. Our results therefore raise the possibility that foetal HDL-associated LpPLA2 might act as an anti-inflammatory enzyme improving vascular barrier function.

Effects of PCSK9 Inhibitors on Other than Low-Density Lipoprotein Cholesterol Lipid Variables

Low-density lipoprotein cholesterol (LDL-C) is a major cardiovascular risk factor, but other lipid variables such as triglycerides (TRGs), high-density lipoprotein cholesterol (HDL-C) and lipoprotein a [Lp(a)] also affect cardiovascular risk. Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors significantly lower LDL-C concentration but also modestly improve the concentrations of TRGs and HDL-C and more robustly decrease Lp(a) levels. The review presents the associated mechanisms of the beneficial effects of PCSK9 inhibitors on the other than LDL-C lipid variables, including the effects on lipid/apolipoprotein secretion and clearance and the heteroexchange between lipoproteins, as well as the possible effects on other variables involved in lipid metabolism such as sortilin. Proprotein convertase subtilisin/kexin type 9 inhibitors improve the overall lipid profile, and these beneficial effects may play a role in the reduction of cardiovascular risk.

Impairment of the Ability of HDL From Patients With Metabolic Syndrome but Without Diabetes Mellitus to Activate eNOS

Objective—

High-density lipoprotein (HDL) from nondiabetic patients with metabolic syndrome (MetS) displays abnormalities in their lipidome, such as triglyceride enrichment and sphingosine-1-phosphate depletion. We hypothesized that these abnormalities could impair the ability of HDL to stimulate endothelial nitric oxide synthase (eNOS).

Approach and Results—

Compared with HDL from control subjects, HDL from normoglycemic patients with MetS was 39% richer in triglycerides ( P <0.01) and 15% poorer in sphingosine-1-phosphate ( P <0.05; n=23 in each group). eNOS activity, assessed by the conversion of L-[ 3 H]arginine to L-[ 3 H]citrulline, was 69% lower in human umbilical vein endothelial cells incubated with HDL from MetS patients than in cells incubated with HDL from controls ( P <0.0001). In addition, the activating phosphorylation of eNOS at serine (Ser) 1177 and of Akt (protein kinase B) at Ser473 was 37% ( P <0.001) and 39% ( P <0.05) lower, respectively, with HDL from MetS patients. Sphingosine-1-phosphate enrichment of HDL from MetS patients restored their ability to stimulate eNOS activity ( P <0.05), in relation with a significant increase in eNOS phosphorylation at Ser1177 ( P <0.05) and in Akt phosphorylation at Ser473 ( P =0.05). By contrast, triglyceride enrichment of HDL from control subjects did not modify eNOS activity ( P =0.90) and phosphorylation at Ser1177 ( P =0.87).

Conclusions—

We provide evidence that the activation of eNOS by HDL is decreased in MetS patients before the appearance of diabetes mellitus and that sphingosine-1-phosphate depletion of HDL is the main factor responsible for this defect. This has important consequences on the impairment of HDL functionality and antiatherogenic properties in these patients.

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.

Effect of soy on metabolic syndrome and cardiovascular risk factors: a randomized controlled trial

BACKGROUND

Cardiovascular diseases are currently the commonest cause of death worldwide. Different strategies for their primary prevention have been planned, taking into account the main known risk factors, which include an atherogenic lipid profile and visceral fat excess.

METHODS

The study was designed as a randomized, parallel, single-center study with a nutritional intervention duration of 12 weeks. Whole soy foods corresponding to 30 g/day soy protein were given in substitution of animal foods containing the same protein amount.

RESULTS

Soy nutritional intervention resulted in a reduction in the number of MetS features in 13/26 subjects. Moreover, in the soy group we observed a significant improvement of median percentage changes for body weight (-1.5 %) and BMI (-1.5 %), as well as for atherogenic lipid markers, namely TC (-4.85 %), LDL-C (-5.25 %), non-HDL-C (-7.14 %) and apoB (-14.8 %). Since the majority of the studied variables were strongly correlated, three factors were identified which explained the majority (52 %) of the total variance in the whole data set. Among them, factor 1, which loaded lipid and adipose variables, explained the 22 % of total variance, showing a statistically significant difference between treatment arms (p = 0.002).

CONCLUSIONS

The inclusion of whole soy foods (corresponding to 30 g/day protein) in a lipid-lowering diet significantly improved a relevant set of biomarkers associated with cardiovascular risk.

Subfractions of high-density lipoprotein (HDL) and dysfunctional HDL in chronic kidney disease patients

A number of studies have shown that chronic kidney disease (CKD) is associated with increased risk for cardiovascular disease (CVD). Chronic kidney disease is characterized by significant disturbances in lipoprotein metabolism, including differences in quantitative and qualitative content of high-density lipoprotein (HDL) particles. Recent studies have revealed that serum HDL cholesterol levels do not predict CVD in CKD patients; thus CKD-induced modifications in high-density lipoprotein (HDL) may be responsible for the increase in CV risk in CKD patients. Various methods are available to separate several subclasses of HDL and confirm their atheroprotective properties. However, under pathological conditions associated with inflammation and oxidation, HDL can progressively lose normal biological activities and be converted into dysfunctional HDL. In this review, we highlight the current state of knowledge on subfractions of HDL and HDL dysfunction in CKD.

HDL2/HDL3 Ratio Changes, Metabolic Syndrome Markers, and Other Factors in a Japanese Population

AIM AND METHODS

The high-density lipoprotein 2 cholesterol (HDL2-C) to HDL3-C ratio is associated with insulin resistance, high-molecular-weight adiponectin (HMW-Ad), and metabolic syndrome (MetS) components and is useful for evaluating MetS in Japanese individuals. We investigated potential associations between changes in HDL2-C/HDL3-C and changes in MetS components, insulin resistance, adipocytokine, lipids, and lifestyle habits in 892 Japanese subjects who underwent annual health examinations twice at a mean interval of 1.1 years. Study subjects were divided into three groups on the basis of HDL2-C/HDL3-C changes.

RESULTS

Average changes in waist circumference (WC) and HDL-C were significantly lower and higher, respectively, in the 0 to ＜0.5 and ≥0.5 HDL2-C/HDL3-C change groups compared with those in the reference group (＜0 HDL2-C/HDL3-C change). Among MetS components, average changes in HDL2-C/HDL3-C were associated with changes in WC and HDL-C. Average changes in HMW-Ad and the homeostasis model assessment of insulin resistance were significantly higher and lower, respectively, in the ≥0.5 HDL2-C/HDL3-C change group compared with those in the reference group. In addition, the average low-density lipoprotein cholesterol (LDL-C) gradually decreased as HDL2-C/HDL3-C increased. The average change in LDL-C was significantly lower in the 0 to ＜0.5 and ≥0.5 HDL2-C/HDL3-C change groups than in the reference group. Moreover, a ≥0.5 HDL2-C/HDL3-C change positively correlated with good lifestyle statuses in terms of smoking, physical activity, and alcohol consumption.

CONCLUSION

Changes in HDL2-C/HDL3-C inversely correlated with changes in WC, insulin resistance, and LDL-C and positively correlated with HMW-Ad and good lifestyle habits. Therefore, HDL2-C/HDL3-C changes comprise a useful marker for both MetS and atherogenic conditions in Japanese population.

Going into labor and beyond: phospholipase A2 in pregnancy

The phospholipase A2(PLA2) family is a very diverse group of enzymes, all serving in the cleavage of phospholipids, thereby releasing high amounts of arachidonic acid (AA) and lysophospholipids. AA serves as a substrate for prostaglandin production, which is of special importance in pregnancy for the onset of parturition. Novel research demonstrates that PLA2action affects the immune response of the mother toward the child and is therefore probably implied in the tolerance of the fetus and prevention of miscarriage. This review presents data on the biochemical and enzymatic properties of PLA2during gestation with a special emphasis on its role for the placental function and development of the fetus. We also critically discuss the possible pathophysiological significance of PLA2alterations and its possible functional consequences. These alterations are often associated with pregnancy pathologies such as preeclampsia and villitis or pregnancy complications such as obesity and diabetes in the mother as well as preterm onset of labor.

High density lipoprotein and metabolic disease: Potential benefits of restoring its functional properties

Background

High density lipoproteins (HDLs) are thought to be atheroprotective and to reduce the risk of cardiovascular disease (CVD). Besides their antioxidant, antithrombotic, anti-inflammatory, anti-apoptotic properties in the vasculature, HDLs also improve glucose metabolism in skeletal muscle.

Scope of the review

Herein, we review the functional role of HDLs to improve metabolic disorders, especially those involving insulin resistance and to induce regression of CVD with a particular focus on current pharmacological treatment options as well as lifestyle interventions, particularly exercise.

Major conclusions

Functional properties of HDLs continue to be considered important mediators to reverse metabolic dysfunction and to regress atherosclerotic cardiovascular disease. Lifestyle changes are often recommended to reduce the risk of CVD, with exercise being one of the most important of these. Understanding how exercise improves HDL function will likely lead to new approaches to battle the expanding burden of obesity and the metabolic syndrome.

Lipoprotein-associated phospholipase A2 distribution among lipoproteins differs in type 1 diabetes

BACKGROUND

LpPLA2 mass and activity have been variably related to cardiovascular disease risk, and the distribution of LpPLA2 in patients with type 1 diabetes (T1D), wherein cardiovascular disease risk is high despite normal or higher levels of high-density lipoprotein (HDL) cholesterol, is unknown.

OBJECTIVE

To determine whether there are differences in the distribution of LpPLA2 mass and activity across lipoproteins and their association with coronary artery calcium (CAC) in patients with T1D.

METHODS

Men with T1D (n = 19) not on statins, with and without CAC progression, and men without diabetes matched for HDL cholesterol (n = 25) had lipoproteins separated by fast protein liquid chromatography.

RESULTS

Both LpPLA2 mass and activity were found within low-density lipoprotein (LDL) and HDL pools with more LpPLA2 mass being associated with HDL (54% vs 44%; P-value <.001) and more LpPLA2 activity being associated with LDL (56% vs 40%; P value = .02). In T1D, more LpPLA2 activity was associated with large- or less-dense LDL compared to those without diabetes. However, no difference in LpPLA2 activity or mass between lipoprotein subfractions was observed between all groups, and there was no relationship between LpPLA2 activity or mass and its distribution and CAC score progression in healthy or T1D men.

CONCLUSION

LpPLA2 is found in both LDL and HDL and is distributed differently in men with T1D without any relationship to CAC score progression.

Increased cholesterol efflux capacity in metabolic syndrome: Relation with qualitative alterations in HDL and LCAT

BACKGROUND

Metabolic syndrome (MetS) is associated with changes in HDL levels, composition and sub-fraction profile. Whether these alterations affect HDL anti-atherogenic function, specifically measured as its capacity to perform cholesterol efflux, is not yet clearly known.

OBJECTIVE

To evaluate the relation between serum cholesterol efflux capacity and the changes in HDL composition and sub-fraction profile in MetS.

METHODS

In 35 non-treated MetS patients and 15 healthy controls, HDL mediated cholesterol efflux was measured as the ability of apoB-depleted serum to accept cholesterol from cholesterol-loaded BHK cells expressing either ABCA1 or ABCG1. Additionally we determined: lipid profile, HDL sub-fractions (NMR) and LCAT mass (ELISA). Isolated HDL (δ:1.063-1.210 g/mL) was chemically characterized. Pre-β1-HDL was determined by 2D-electrophoresis in a sub-group of MetS and controls (n = 6 each).

RESULTS

Surprisingly, MetS patients presented higher ABCA1 mediated cholesterol efflux (10.4 ± 1.8 vs. 8.7 ± 0.3%; p = 0.0001), without differences in ABCG1 efflux. In MetS, HDL showed reduction in particle size and number (p < 0.02) and lower large/small HDL ratio (p = 0.05), as well as triglyceride enrichment (p = 0.0001). Pre-β1-HDL was increased in MetS (p = 0.048) and correlated with ABCA1-cholesterol efflux (r = 0.64; p = 0.042). LCAT mass showed a tendency to reduction in MetS (p = 0.08), and inversely correlated with ABCA1-cholesterol efflux (r = -0.51; p = 0.001), independently of obesity and insulin-resistance (β = -0.40, p = 0.034).

CONCLUSION

This is the first description of ABCA1 mediated cholesterol efflux in MetS. Regardless the reduced HDL-cholesterol, in vitro cholesterol efflux capacity by ABCA1 was enhanced, linked to increased pre-β1-HDL and slightly reduced in LCAT mass that would probably reflect a delay in reverse cholesterol transport occurring in MetS.

Correlation Between High-Density Lipoprotein and Monocyte Subsets in Patients with Stable Coronary Heart Disease

Background

High-density lipoprotein (HDL) consists of heterogeneous particles with a variety of structures and functions. Its role in atherosclerosis has been gradually recognized. Studies have shown dysfunction of small HDL in patients with coronary artery disease (CAD). Monocytes play an important role in atherosclerosis, which can be divided into 3 subgroups based on the expression of surface markers CD14 and CD16. This study aimed to investigate the association between HDL and monocyte subsets in CAD patients.

Material/Methods

A total of 90 patients with stable CAD were selected in this study. Monocytes were divided into classical monocytes (CM, CD14++CD16−), intermediate monocytes (IM, CD14++CD16+), and non-classical monocytes (NCM, CD14+CD16++). HDL components in serum were determined by high-resolution polyacrylamide gel electrophoresis (detected by Quantimetrix HDL Lipoprint system, referring to HDL subfractions analysis: A new laboratory diagnostic assay for patients with cardiovascular diseases and dyslipoproteinemia).

Results

Serum level of small HDL was positively correlated with circulating proinflammatory NCM (r=0.30; p=0.004), negatively correlated with CM, and not correlated with IM. We also found that disease severity was not associated with diabetes mellitus, glycosylated hemoglobin, hypertension, smoking history, or statin dosage.

Conclusions

Our study confirmed that small HDL level is associated with an increase in NCM and a decrease in CM, suggesting the proinflammatory relationship between small HDL and intrinsic immune function during the progression of stable CAD.

Amount of hepatic fat predicts cardiovascular risk independent of insulin resistance among Hispanic-American adolescents

Background

Nonalcoholic fatty liver disease (NAFLD) has emerged as the major pediatric chronic liver disease, and it is estimated to affect more than one third of obese children in the U.S. Cardiovascular complications are a leading cause of increased mortality in adults with NAFLD and many adolescents with NAFLD already manifest signs of subclinical atherosclerosis including increased carotid intima-media thickness.

Methods

Volume of intrahepatic fat was assessed in 50 Hispanic-American, overweight adolescents, using Magnetic Resonance Spectroscopy. Lipoprotein compositions were measured using Nuclear Magnetic Resonance.

Results

Plasma triglycerides (TG) (p = 0.003), TG/HDL ratio (p = 0.006), TG/apoB ratio (p = 0.011), large VLDL concentration (p = 0.019), VLDL particle size (p = 0.012), as well as small dense LDL concentration (p = 0.026) progressively increased across higher levels of hepatic fat severity, while large HDL concentration progressively declined (p = 0.043). This pattern of associations remained even after controlling for gender, BMI, visceral fat, and insulin resistance.

Conclusions

Our findings suggest that increased hepatic fat is strongly associated with peripheral dyslipidemia and the amount of fat in the liver may influence cardiovascular risk. Further studies are needed to longitudinally monitor dyslipidemia in children with NAFLD and to examine whether the reduction of hepatic fat would attenuate their long-term CVD risk.

HDL2-cholesterol/HDL3-cholesterol ratio was associated with insulin resistance, high-molecular-weight adiponectin, and components for metabolic syndrome in Japanese

AIMS

Recent data have suggested a relationship between the high-density lipoprotein (HDL) subclass ratio and metabolic syndrome (MetS). However, limited information is available regarding the relationships between the HDL subclass ratio and insulin resistance, associated adipocytokine levels, and MetS components. The associations of the high-density lipoprotein 2 cholesterol (HDL2-C) to high-density lipoprotein 3 cholesterol (HDL3-C) ratio with the homeostasis model assessment of insulin resistance (HOMA-IR) index, high-molecular-weight adiponectin (HMW-Ad) levels, and MetS components were examined.

METHODS

The study included 1155 Japanese subjects who met our inclusion criteria and underwent an annual health examination that included an HDL subclass analysis.

RESULTS

The HDL2-C/HDL3-C ratio and the HMW-Ad level gradually decreased as the number of MetS components increased. In contrast, HOMA-IR gradually increased as the number of MetS components increased. The HDL2-C/HDL3-C ratio correlated inversely with HOMA-IR and positively with the HMW-Ad level. A strong positive correlation was observed between the HDL2-C/HDL3-C ratio and the HDL-C level. The HDL2-C/HDL3-C ratio exhibited moderate negative correlations with the body mass index, waist circumference, and triglyceride level. Weak negative correlations were observed for the HDL2-C/HDL3-C ratio with the systolic and diastolic blood pressure and fasting plasma glucose levels.

CONCLUSIONS

Our data indicated that the HDL2-C/HDL3-C ratio was associated with insulin resistance, the HMW-Ad level, and MetS components, and it was useful for evaluating MetS in Japanese individuals.

Small high-density lipoprotein is associated with monocyte subsets in stable coronary artery disease

Objective: High-density lipoprotein (HDL) particles are heterogeneous in structure and function and the role of HDL subfractions in atherogenesis is not well understood. It has been suggested that small HDL may be dysfunctional in patients with coronary artery disease (CAD). Monocytes are considered to play a key role in atherosclerotic diseases. Circulating monocytes can be divided into three subtypes according to their surface expression of CD14 and CD16. Our aim was to examine whether monocyte subsets are associated with HDL subfractions in patients with atherosclerosis. Methods: We included 90 patients with angiographically stable CAD. Monocyte subsets were defined as classical monocytes (CD14++CD16-; CM), intermediate monocytes (CD14++CD16+; IM) and non-classical monocytes (CD14+CD16++; NCM). HDL subfractions were measured by electrophoresis on polyacrylamide gel. Results: Serum levels of small HDL correlated with circulating pro-inflammatory NCM and showed an inverse relationship to circulating CM independently from other lipid parameters, risk factors, inflammatory parameters or statin treatment regime, respectively. IM were not associated with small HDL. In particular, patients with small HDL levels in the highest tertile showed dramatically increased levels of NCM (14.7 ± 7% vs. 10.7 ± 5% and 10.8 ± 5%; p = 0.006) and a decreased proportion of CM (79.3 ± 7% vs. 83.7 ± 6% and 83.9 ± 6%; p = 0.004) compared to patients in the two lower tertiles. In contrast, intermediate HDL, large HDL and total HDL were not associated with monocyte subset distribution. Conclusion: Small HDL levels are associated with pro-inflammatory NCM and inversely correlated with CM. This may suggest that small HDL could have dysfunctional anti-inflammatory properties in patients with established CAD.

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Small HDL levels are associated with non-classical monocytes in stable CAD.

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Classical monocytes are inversely associated with small HDL levels.

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Associations are independent of other lipid parameters, risk factors, inflammatory parameters or statin treatment regime.

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Inflammatory markers do not vary according to small HDL levels.

High density lipoproteins and type 2 diabetes: Emerging concepts in their relationship

Patients with type 2 diabetes mellitus (T2DM) frequently exhibit macrovascular complications of atherosclerotic cardiovascular (CV) disease. High density lipoproteins (HDL) are protective against atherosclerosis. Low levels of HDL cholesterol (HDL-C) independently contribute to CV risk. Patients with T2DM not only exhibit low HDL-C, but also dysfunctional HDL. Furthermore, low concentration of HDL may increase the risk for the development of T2DM through a decreased β cell survival and secretory function. In this paper, we discuss emerging concepts in the relationship of T2DM with HDL.

Cholesterol forms and traditional lipid profile for projection of atherogenic dyslipidemia: lipoprotein subfractions and erythrocyte membrane cholesterol

Atherogenic dyslipidemia characterized by abnormal changes in plasma lipid profile such as low high-density lipoprotein (HDL) and increased triglyceride (TG) levels is strongly associated with atherosclerotic diseases. We aimed to evaluate the levels of pro- and antiatherogenic lipids and erythrocyte membrane cholesterol (EMC) content in normo- and dyslipidemic subjects to investigate whether EMC content could be a useful marker for clinical presentation of atherogenic dyslipidemia. Low-density lipoprotein (LDL), HDL and their subfraction levels and erythrocyte lipid content were determined in 64 normolipidemic (NLs), 42 hypercholesterolemic (HCs) and 42 mixed-type dyslipidemic subjects (MTDs). Plasma atherogenic lipid indices [small–dense LDL (sdLDL)/less-dense HDL (LHDL), TC/HDL-C, TG/HDL-C and Apo B/AI] were higher in MTDs compared to NLs (p < 0.001). The highest sdLDL level was observed in HCs (p < 0.01). Despite a slight increase in EMC level in dyslipidemic subgroups, the difference was not statistically significant. A significant negative correlation, however, was observed between EMC and sdLDL/LHDL in HCs (p < 0.035, r = −0.386). Receiver operating characteristic curves to predict sdLDL level showed that TG and EMC levels had higher area under curve values compared to other parameters in HCs. We showed that diameters of larger LDL and HDL particles tend to shift toward smaller values in MTDs. Our results suggest that EMC content and TG levels may be a useful predictor for sdLDL level in hypercholesterolemic patients.

Lipoprotein subfraction profile and HDL-associated enzymes in sickle cell disease patients

Although hypocholesterolemia is a reported finding in sickle cell disease (SCD), low-density lipoprotein (LDL)/high-density lipoprotein (HDL) subfractions and HDL-associated enzymes have not been determined in SCD patients. Blood was collected from 38 hemoglobin (Hb)A volunteers and 45 homozygous HbSS patients who had not received blood transfusions in the last 3 months. Serum lipids were measured by automated analyzer while LDL and HDL subfraction analysis was done by continuous disc polyacrylamide gel electrophoresis. Serum levels of cholesteryl ester transfer protein (CETP), lecithin-cholesterol acyltransferase (LCAT), apolipoprotein B (apoB) and apolipoprotein A-1 (apoA-I) were determined by enzyme-linked immunosorbent assay (ELISA). Total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) levels were significantly decreased, while TG levels were significantly increased in SCD patients compared to controls. A significant decrease in intermediate-density lipoprotein (IDL)-C, IDL-B, IDL-A and LDL-1 fractions were seen in SCD patients, while no significant difference was observed in small dense LDL particles. A significant decrease was seen in HDL-large, HDL-intermediate and HDL-small fractions in SCD patients versus controls. Levels of LCAT and ApoA-1 protein measured in SCD patients were significantly lower while no significant difference was observed in CETP and ApoB protein levels compared to controls. The reduction observed in LDL- and HDL-C in SCD patients was reflected as significantly decreased IDL, LDL-1 and HDL-subfractions. Decreased HDL subfractions may possibly lead to the reduced ApoA-1 and LCAT protein levels observed in SCD patients.

Lipid-modulating treatments for mixed dyslipidemia increase HDL-associated phospholipase A2 activity with differential effects on HDL subfractions

The effect of lipid-modulating treatments on modification of high density lipoprotein (HDL) subfractions remains unknown. In this study, mixed dyslipidemia patients (n = 100) inadequately controlled with a standard statin dose were randomized to switch to 40 mg of rosuvastatin or add-on extended release nicotinic acid/laropiprant (ER-NA/LRPT) or add-on fenofibrate. The cholesterol concentrations of HDL (HDL-C) subfractions and HDL-associated lipoprotein-associated phospholipase A2 (HDL-Lp-PLA2) activity were assessed at baseline and 3 months later. We observed that large HDL-C increased by 50 and 6 % in the add-on-ER-NA/LRPT and rosuvastatin groups, respectively, while it decreased by 20 % in the add-on-fenofibrate group (p < 0.01 vs baseline for all groups and p < 0.01 for all comparisons among groups). On the other hand, small HDL-C decreased by 17 % in the add-on-ER-NA/LRPT group (p < 0.01 vs baseline), while it increased by 25 % in the add-on-fenofibrate group (p < 0.01 vs baseline) without any change in the rosuvastatin group (p < 0.01 for all comparisons among groups). HDL-Lp-PLA2 activity increased by 55, 33 and 18 % in add-on-ER-NA/LRPT, add-on-fenofibrate and rosuvastatin groups, respectively (p < 0.01 for all comparisons vs baseline and for all comparisons among groups). In conclusion, add-on-ER-NA/LRPT was associated with an increase in large HDL-C and a decrease in small HDL-C, while opposite effects were noticed in the add-on-fenofibrate group. Add-on-ER-NA/LRPT was associated with the most pronounced increase in HDL-Lp-PLA2 activity.

Does combination therapy with statins and fibrates prevent cardiovascular disease in diabetic patients with atherogenic mixed dyslipidemia?

Type 2 diabetes mellitus (T2DM) is associated with the development and progression of cardiovascular disease (CVD). Statins have an established efficacy in the management of dyslipidemia primarily by decreasing the levels of low-density lipoprotein cholesterol and thus decreasing CVD risk. They also have a favorable safety profile. Despite the statin-mediated benefit of CVD risk reduction a residual CVD risk remains, especially in T2DM patients with high triglyceride (TG) and low high-density lipoprotein cholesterol (HDL-C) values. Fibrates decrease TG levels, increase HDL-C concentrations, and improve many other atherosclerosis-related variables. Fibrate/statin co-administration improves the overall lipoprotein profile in patients with mixed dyslipidemia and may reduce the residual CVD risk during statin therapy. However, limited data exists regarding the effects of statin/fibrate combination on CVD outcomes in patients with T2DM. In the Action to Control Cardiovascular Risk in Diabetes (ACCORD) study the statin/fibrate combination did not significantly reduce the rate of CVD events compared with simvastatin/placebo in patients with T2DM. However, it did show a possible benefit in a pre-specified analysis in the subgroup of patients with high TG and low HDL-C levels. Furthermore, in the ACCORD study the simvastatin/fenofibrate combination significantly reduced the rate of progression of retinopathy compared with statin/placebo administration in patients with T2DM. The present review presents the available data regarding the effects of statin/fibrate combination in patients with T2DM and atherogenic mixed dyslipidemia.

High density lipoprotein and cardiovascular diseases

Several epidemiological studies have clearly shown that low plasma levels of high density lipoprotein cholesterol (HDL-C) represent a cardiovascular disease (CVD) risk factor. However, it is unclear if there is a causal association between HDL-C concentration and CVD. A recent study published in the Lancet, which performed two Mendelian randomization analyses, showed that increased HDL-C levels were not associated with a decreased risk of myocardial infarction. These findings, together with the termination of the niacin-based AIM-HIGH trial and the discontinuation of cholesteryl ester transfer protein inhibitor dalcetrapib, challenge the concept that raising of plasma HDL-C will uniformly translate into reductions in CVD risk. HDL particles exhibit several anti-atherosclerotic properties, such as anti-inflammatory and anti-oxidative activities and cellular cholesterol efflux activity. Furthermore, HDL particles are very heterogeneous in terms of size, structure, composition and metabolism. HDL functionality may be associated more strongly with CVD risk than the traditional HDL-C levels. More research is needed to assess the association of the structure of HDL particle with its functionality and metabolism.

Small high-density lipoprotein (HDL) subclasses are increased with decreased activity of HDL-associated phospholipase A₂ in subjects with prediabetes

Alterations in high-density lipoprotein (HDL) subclass distribution, as well as in the activities of HDL-associated enzymes, have been associated with increased cardiovascular disease (CVD) risk. HDL subclass distribution and the activities of HDL-associated enzymes remain unknown in prediabetic patients, a condition also associated with increased CVD risk. The aim of the present study was to assess any differences in HDL subclass distribution (using polyacrylamide gel electrophoresis) and in activities of HDL-associated enzymes between prediabetic (impaired fasting glucose, IFG, n = 80) and non-prediabetic subjects (n = 105). Subjects with prediabetes had significantly increased waist circumference, blood pressure and triacylglycerol (TAG) levels compared with subjects with fasting glucose levels <100 mg/dL (all p < 0.05). The proportion of small HDL3 over HDL cholesterol (HDL-C) was significantly increased in prediabetic subjects compared with their controls (p < 0.05). The activity of the anti-atherogenic HDL-associated lipoprotein-associated phospholipase A₂ (HDL-LpPLA₂) was significantly lower in subjects with prediabetes (p < 0.05), whereas the activity of paraoxonase 1 (using both paraoxon and phenyl acetate as substrates) did not significantly differ between subjects with or without prediabetes. In a stepwise linear regression analysis, the proportion of small HDL3 over HDL-C concentration was independently associated with the presence of prediabetes and with total cholesterol and TAG concentration (positively), as well as with HDL-C levels (negatively). We also observed a trend of increased small dense low-density lipoprotein cholesterol levels in prediabetic subjects compared with their controls. Subjects with IFG exhibit increased proportion of small HDL3 particles combined with decreased activity of the anti-atherogenic HDL-LpPLA₂.

Lipoprotein subfractions in metabolic syndrome and obesity: clinical significance and therapeutic approaches

Small, dense low density lipoprotein (sdLDL) represents an emerging cardiovascular risk factor, since these particles can be associated with cardiovascular disease (CVD) independently of established risk factors, including plasma lipids. Obese subjects frequently have atherogenic dyslipidaemia, including elevated sdLDL levels, in addition to elevated triglycerides (TG), very low density lipoprotein (VLDL) and apolipoprotein-B, as well as decreased high density lipoprotein cholesterol (HDL-C) levels. Obesity-related co-morbidities, such as metabolic syndrome (MetS) are also characterized by dyslipidaemia. Therefore, agents that favourably modulate LDL subclasses may be of clinical value in these subjects. Statins are the lipid-lowering drug of choice. Also, anti-obesity and lipid lowering drugs other than statins could be useful in these patients. However, the effects of anti-obesity drugs on CVD risk factors remain unclear. We review the clinical significance of sdLDL in being overweight and obesity, as well as the efficacy of anti-obesity drugs on LDL subfractions in these individuals; a short comment on HDL subclasses is also included. Our literature search was based on PubMed and Scopus listings. Further research is required to fully explore both the significance of sdLDL and the efficacy of anti-obesity drugs on LDL subfractions in being overweight, obesity and MetS. Improving the lipoprotein profile in these patients may represent an efficient approach for reducing cardiovascular risk.

Lipoprotein subfractions in metabolic syndrome and obesity: clinical significance and therapeutic approaches

Small, dense low density lipoprotein (sdLDL) represents an emerging cardiovascular risk factor, since these particles can be associated with cardiovascular disease (CVD) independently of established risk factors, including plasma lipids. Obese subjects frequently have atherogenic dyslipidaemia, including elevated sdLDL levels, in addition to elevated triglycerides (TG), very low density lipoprotein (VLDL) and apolipoprotein-B, as well as decreased high density lipoprotein cholesterol (HDL-C) levels. Obesity-related co-morbidities, such as metabolic syndrome (MetS) are also characterized by dyslipidaemia. Therefore, agents that favourably modulate LDL subclasses may be of clinical value in these subjects. Statins are the lipid-lowering drug of choice. Also, anti-obesity and lipid lowering drugs other than statins could be useful in these patients. However, the effects of anti-obesity drugs on CVD risk factors remain unclear. We review the clinical significance of sdLDL in being overweight and obesity, as well as the efficacy of anti-obesity drugs on LDL subfractions in these individuals; a short comment on HDL subclasses is also included. Our literature search was based on PubMed and Scopus listings. Further research is required to fully explore both the significance of sdLDL and the efficacy of anti-obesity drugs on LDL subfractions in being overweight, obesity and MetS. Improving the lipoprotein profile in these patients may represent an efficient approach for reducing cardiovascular risk.

High-density lipoprotein subfractions--what the clinicians need to know

Although the inverse relationship between plasma levels of high-density lipoprotein (HDL) and cardiovascular disease has been largely demonstrated, many observations have suggested that the assessment of HDL functionality might be more informative than a simple measurement of HDL-cholesterol plasma levels. HDLs are a class of structurally and functionally heterogeneous particles; in atherosclerosis-related diseases, changes in HDL subfraction levels and functions are frequently observed. Circulating levels of large HDL particles are decreased in dyslipidaemic conditions, while levels of small dense HDL particles are increased in patients with coronary heart disease. Furthermore, specific genetic defects in proteins involved in HDL metabolism significantly impact the distribution of HDL subpopulations. Finally, many drugs used for dyslipidaemia induce changes in HDL subfractions strictly related to cardiovascular disease. Although several methods exist to evaluate HDL subclass levels, most of them are not easily applicable in clinical practice, due to the costs and high variability. However, the possibility to measure the levels of specific HDL subfractions in patients with atherosclerosis-related diseases might help to better define their cardiovascular risk.

Influence of obesity and cardiometabolic makers on lipoprotein-associated phospholipase A2 (Lp-PLA2) activity in adolescents: the healthy young cross-sectional study

BACKGROUND

Lipoprotein-associated phospholipase A2 activity (Lp-PLA2) is a good marker of cardiovascular risk in adults. It is strongly associated with stroke and many others cardiovascular events. Despite this, the impact of obesity on this enzyme activity and its relation to biomarkers of cardiovascular disease in adolescents is not very well investigated. The purpose of this article is to evaluate the influence of obesity and cardiometabolic markers on Lp-PLA2 activity in adolescents.

RESULTS

This cross-sectional study included 242 adolescents (10-19 years) of both gender. These subjects were classified in Healthy Weight (n = 77), Overweight (n = 82) and Obese (n = 83) groups. Lipid profile, glucose, insulin, HDL size, LDL(-) and anti-LDL(-) antibodies were analyzed. The Lp-PLA2 activity was determined by a colorimetric commercial kit. Body mass index (BMI), waist circumference and body composition were monitored. Food intake was evaluated using three 24-hour diet recalls. The Lp-PLA2 activity changed in function to high BMI, waist circumference and fat mass percentage. It was also positively associated with HOMA-IR, glucose, insulin and almost all variables of lipid profile. Furthermore, it was negatively related to Apo AI (β = -0.137; P = 0.038) and strongly positively associated with Apo B (β = 0.293; P < 0.001) and with Apo B/Apo AI ratio (β = 0.343; P < 0.001). The better predictor model for enzyme activity, on multivariate analysis, included Apo B/Apo AI (β = 0.327; P < 0.001), HDL size (β = -0.326; P < 0.001), WC (β = 0.171; P = 0.006) and glucose (β = 0.119; P = 0.038). Logistic regression analysis demonstrated that changes in Apo B/Apo AI ratio were associated with a 73.5 times higher risk to elevated Lp-PLA2 activity.

CONCLUSIONS

Lp-PLA2 changes in function of obesity, and that it shows important associations with markers of cardiovascular risk, in particular with waist circumference, glucose, HDL size and Apo B/Apo AI ratio. These results suggest that Lp-PLA2 activity can be a cardiovascular biomarker in adolescence.

Effects of 12 months of treatment with disease-modifying anti-rheumatic drugs on low and high density lipoprotein subclass distribution in patients with early rheumatoid arthritis: a pilot study

OBJECTIVES

Patients with rheumatoid arthritis (RA) have increased cardiovascular risk. The aim of the present study was the assessment of low density lipoprotein (LDL) and high density lipoprotein (HDL) subclass distribution in patients with early RA (ERA, n = 30) compared with age- and sex-matched healthy subjects (n = 30), as well the effect of treatment for 12 months with the disease-modifying anti-rheumatic drugs (DMARDs) methotrexate and prednisone in this distribution.

METHOD

LDL and HDL subclass distribution was determined using a polyacrylamide gel-tube electrophoresis method.

RESULTS

ERA patients exhibited increased levels of inflammatory markers and high disease activity score. ERA patients had higher serum levels of total cholesterol (TC), LDL cholesterol (LDL-C), and triglycerides (TG) whereas their serum HDL cholesterol (HDL-C) levels were significantly lower compared with controls. ERA patients exhibited significantly higher plasma levels of small dense LDL-C (sdLDL-C), leading to a significantly decreased mean LDL diameter. ERA patients had significantly decreased small HDL particles (HDL-3) concentration whereas serum levels of large HDL particles (HDL-2) did not differ compared with controls. Treatment with DMARDs resulted in a significant decrease in inflammatory markers and disease activity, along with a significant increase in HDL-C serum levels. The concentration of sdLDL-C did not change significantly during treatment. We observed a significant increase in the levels of large HDL-2 whereas the concentration of small HDL-3 did not significantly change.

CONCLUSIONS

Patients with ERA have increased sdLDL-C levels and decreased HDL-C levels because of decreased concentration of the small HDL-3 subclass. The administration of DMARDs induced a significant increase in HDL-C levels, which was attributed to the increase in large HDL-2 serum concentration.

Lipoprotein-associated phospholipase A(2) bound on high-density lipoprotein is associated with lower risk for cardiac death in stable coronary artery disease patients: a 3-year follow-up

OBJECTIVES

The aim of this study was to examine the prognostic value of lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) associated with high-density lipoprotein (HDL) (HDL-Lp-PLA(2)) in patients with stable coronary artery disease (CAD).

BACKGROUND

Lp-PLA(2) is a novel risk factor for cardiovascular disease. It has been postulated that the role of Lp-PLA(2) in atherosclerosis may depend on the type of lipoprotein with which it is associated.

METHODS

Total plasma Lp-PLA(2) and HDL-Lp-PLA(2) mass and activity, lipids, and C-reactive protein were measured in 524 consecutive patients with stable CAD who were followed for a median of 34 months. The primary endpoint was cardiac death, and the secondary endpoint was hospitalization for acute coronary syndromes, myocardial revascularization, arrhythmic event, or stroke.

RESULTS

Follow-up data were obtained from 477 patients. One hundred twenty-three patients (25.8%) presented with cardiovascular events (24 cardiac deaths, 47 acute coronary syndromes, 28 revascularizations, 22 arrhythmic events, and 2 strokes). Total plasma Lp-PLA(2) mass and activity were predictors of cardiac death (hazard ratio [HR]: 1.013; 95% confidence interval [CI]: 1.005 to 1.021; p = 0.002; and HR: 1.040; 95% CI: 1.005 to 1.076; p = 0.025, respectively) after adjustment for traditional risk factors for CAD. In contrast, HDL-Lp-PLA(2) mass and activity were associated with lower risk for cardiac death (HR: 0.972; 95% CI: 0.952 to 0.993; p = 0.010; and HR: 0.689; 95% CI: 0.496 to 0.957; p = 0.026, respectively) after adjustment for traditional risk factors for CAD.

CONCLUSIONS

Total plasma Lp-PLA(2) is a predictor of cardiac death, while HDL-Lp-PLA(2) is associated with lower risk for cardiac death in patients with stable CAD, independently of other traditional cardiovascular risk factors.

Effect of rosuvastatin monotherapy or in combination with fenofibrate or ω-3 fatty acids on lipoprotein subfraction profile in patients with mixed dyslipidaemia and metabolic syndrome

BACKGROUND

Raised triglycerides (TG), decreased high-density lipoprotein cholesterol (HDL-C) levels and a predominance of small dense low density lipoproteins (sdLDL) are characteristics of the metabolic syndrome (MetS).

OBJECTIVE

To compare the effect of high-dose rosuvastatin monotherapy with moderate dosing combined with fenofibrate or ω-3 fatty acids on the lipoprotein subfraction profile in patients with mixed dyslipidaemia and MetS.

METHODS

We previously randomised patients with low-density lipoprotein cholesterol (LDL-C) > 160 and TG > 200 mg/dl to rosuvastatin monotherapy 40 mg/day (R group, n = 30) or rosuvastatin 10 mg/day combined with fenofibrate 200 mg/day (RF group, n = 30) or ω-3 fatty acids 2 g/day (Rω group, n = 30). In the present study, only patients with MetS were included (24, 23 and 24 in the R, RF and Rω groups respectively). At baseline and after 12 weeks of treatment, the lipoprotein subfraction profile was determined by polyacrylamide 3% gel electrophoresis.

RESULTS

The mean LDL size was significantly increased in all groups. This change was more prominent with RF than with other treatments in parallel with its greater hypotriglyceridemic capacity (p < 0.05 compared with R and Rω). A decrease in insulin resistance by RF was also noted. Only RF significantly raised HDL-C levels (by 7.7%, p < 0.05) by increasing the cholesterol of small HDL particles. The cholesterol of larger HDL subclasses was significantly increased by R and Rω.

CONCLUSIONS

All regimens increased mean LDL size; RF was the most effective. A differential effect of treatments was noted on the HDL subfraction profile.

A review of the role of apolipoprotein C-II in lipoprotein metabolism and cardiovascular disease

The focus of this review is on the role of apolipoprotein C-II (apoC-II) in lipoprotein metabolism and the potential effects on the risk of cardiovascular disease (CVD). We searched PubMed/Scopus for articles regarding apoC-II and its role in lipoprotein metabolism and the risk of CVD. Apolipoprotein C-II is a constituent of chylomicrons, very low-density lipoprotein, low-density lipoprotein, and high-density lipoprotein (HDL). Apolipoprotein C-II contains 3 amphipathic α-helices. The lipid-binding domain of apoC-II is located in the N-terminal, whereas the C-terminal helix of apoC-II is responsible for the interaction with lipoprotein lipase (LPL). At intermediate concentrations (approximately 4 mg/dL) and in normolipidemic subjects, apoC-II activates LPL. In contrast, both an excess and a deficiency of apoC-II are associated with reduced LPL activity and hypertriglyceridemia. Furthermore, excess apoC-II has been associated with increased triglyceride-rich particles and alterations in HDL particle distribution, factors that may increase the risk of CVD. However, there is not enough current evidence to clarify whether increased apoC-II causes hypertriglyceridemia or is an epiphenomenon reflecting hypertriglyceridemia. A number of pharmaceutical interventions, including statins, fibrates, ezetimibe, nicotinic acid, and orlistat, have been shown to reduce the increased apoC-II concentrations. An excess of apoC-II is associated with increased triglyceride-rich particles and alterations in HDL particle distribution. However, prospective trials are needed to assess if apoC-II is a CVD marker or a risk factor in high-risk patients.

Variation of lipoprotein associated phospholipase A2 across demographic characteristics and cardiovascular risk factors: a systematic review of the literature

BACKGROUND

Lipoprotein association phospholipase A2 (Lp-PLA(2)), an enzyme which has been found in atherosclerotic plaque is currently under investigation in large Phase III clinical trials of vascular disease prevention. We assessed in a variety of different population settings variation of Lp-PLA(2) mass and activity across gender, ethnicity, diabetes, kidney disease and metabolic syndrome. We also assessed correlations with measures of circulating lipids, systemic inflammation and adiposity.

METHODS

Systematic review of studies measuring Lp-PLA(2) and at least one of the relevant characteristics in >50 participants.

RESULTS

We identified a total of 77 studies involving 102,499 participants meeting the inclusion criteria. Lp-PLA(2) mass and activity were consistently approximately 10% higher in males than females and 15% higher in Caucasians than African Americans or Hispanics. There were no clear associations of Lp-PLA(2) mass or activity with type II diabetes, markers of systemic inflammation (C-reactive protein, fibrinogen) or with body mass index. Correlations of Lp-PLA(2) mass or activity with low density lipoprotein cholesterol and apolipoprotein B were moderate and positive, whilst correlations with high density lipoprotein cholesterol were negative and moderate to weak. There was no clear differences in associations with any of the above characteristics in groups defined based upon prevalent cardiovascular disease or its risk factors.

CONCLUSIONS

Despite considerable variability in absolute levels of Lp-PLA(2) across studies, the variability of Lp-PLA(2) across gender, ethnicity, and levels of circulating lipids and markers of systemic inflammation are more consistent and appear not to vary importantly across categories defined by CVD or its risk factors.

Paraoxonase 1 polymorphisms L55M and Q192R were not risk factors for Parkinson's disease: a HuGE review and meta-analysis

PURPOSE

The Paraoxonase 1 (PON1) has been studied as a potential candidate gene for Parkinson's disease risk, but direct evidence from genetic association studies remains inconclusive. We performed a meta-analysis pooling data from all relevant studies in order to determine the effects of two PON 1 polymorphisms (L55M and Q192R) on Parkinson's disease.

METHODS

We applied a random effects to combine odds ratio (OR) and 95% confidence intervals. Q statistic was used to evaluate the homogeneity, and Egger's test and Funnel plot were used to assess publication bias. In secondary analyses, we examined dominant and recessive models as well.

RESULTS

Concerning the PON1 L55M polymorphism, we identified 9 eligible studies (a total of 2582 cases and 3997 controls). The random effects pooled OR was OR=1.29, (0.90, 1.84). Concerning the Q192R polymorphism, we identified 7 eligible studies (a total of 2582 cases and 3997 controls). The random effects pooled OR was OR=1.08(0.81, 1.43). Analysis with dominant and recessive genetic models yielded the same inferences as genotype-based comparisons for both of the two polymorphisms.

CONCLUSION

The results of this meta-analysis suggested that both PON1 L55M and Q192R were not responsible for PD.