Pharmacologic elevation of high-density lipoproteins: recent insights on mechanism of action and atherosclerosis protection

Biological Properties of Vitamins of the B-Complex, Part 1: Vitamins B1, B2, B3, and B5

This review summarizes the current knowledge on essential vitamins B₁, B₂, B₃, and B₅. These B-complex vitamins must be taken from diet, with the exception of vitamin B₃, that can also be synthetized from amino acid tryptophan. All of these vitamins are water soluble, which determines their main properties, namely: they are partly lost when food is washed or boiled since they migrate to the water; the requirement of membrane transporters for their permeation into the cells; and their safety since any excess is rapidly eliminated via the kidney. The therapeutic use of B-complex vitamins is mostly limited to hypovitaminoses or similar conditions, but, as they are generally very safe, they have also been examined in other pathological conditions. Nicotinic acid, a form of vitamin B₃, is the only exception because it is a known hypolipidemic agent in gram doses. The article also sums up: (i) the current methods for detection of the vitamins of the B-complex in biological fluids; (ii) the food and other sources of these vitamins including the effect of common processing and storage methods on their content; and (iii) their physiological function.

Clinical, Demographic, and Biochemical Characteristics of Patients with Acute ST-Segment Elevation Myocardial Infarction: An Analysis of Acute Coronary Syndrome Registry Data of a Single Medical Center from 2005 to 2016

Background

ST-segment elevation myocardial infarction (STEMI) is one of the leading causes of morbidity and mortality in developed countries. Therefore, understanding the prevalence and trends of major risk factors may facilitate primary and secondary prevention of STEMI.

Methods

In the present study, 2446 consecutive patients with STEMI admitted to Far Eastern Memorial Hospital from 2005 to 2016 were enrolled. A comprehensive analysis of the prevalence, distribution, and trends over time of major risk factors as well as Framingham risk scores of all patients was performed.

Results

The most prevalent risk factors were male sex, hypertension (HTN), smoking, age, dyslipidemia, and diabetes mellitus. Furthermore, 95%-97% of the patients had at least one modifiable risk factor, and < 1% of the patients did not have any identifiable risk factors. The prevalence trends of smoking, HTN, dyslipidemia, and metabolic syndrome increased significantly from 2005 to 2016. Seasonal variation analysis revealed a 15% increase in STEMI cases between January and March compared with those between April and December. Isolated low high- density lipoprotein-cholesterol syndrome was the second most common type of dyslipidemia, with a prevalence rate of 16.6%. Moreover, only 56.8% of the male and 32% of the female patients were in the Framingham high-risk group.

Conclusions

A high prevalence rate and an increasing trend of modifiable risk factors resulted in a high number of STEMI cases at our hospital. Controlling modifiable risk factors and improving nontraditional risk factor detection could facilitate primary and secondary preventions for STEMI.

Association of total cholesterol and HDL-C levels and outcome in coronary heart disease patients with heart failure

The aim of the study was to evaluate associations of total cholesterol (TC) and high density lipoprotein cholesterol (HDL-C) levels with prognosis in coronary heart disease (CHD) patients with heart failure (HF).Patients who were angiographical-diagnosis of CHD and echocardiographical-diagnosis of left ventricular ejection fraction (LVEF) < 45% were enrolled. Baseline characteristics were collected and association of TC and HDL-C levels with rehospitalization for HF and all-cause mortality was assessed.A total of 118 patients were recruited. Mean age was 58.6 ± 10.9 years and male accounted for 65%. Mean LVEF was 39.5 ± 4.0%. Twenty-eight patients were rehospitalized for HF and 6 patients were dead. In patients with poor prognosis, lower body mass index (BMI), TC, HDL-C and albumin while higher high sensitivity C-reactive protein (Hs-CRP) was observed. TC was positively correlated with BMI and albumin, and HDL-C was inversely correlated with Hs-CRP. The associations of TC level and rehospitalization for HF and all-cause mortality were attenuated but consistently significant through model 1 to 4, with odds ratio (OR) of 0.97 (95% confidence interval [CI]: 0.92-0.99). Associations of HDL-C level and rehospitalization for HF and all-cause mortality were also consistently significant through model 1 to 4, with OR of 0.95 (95% CI: 0.90-0.98). Strength of association was attenuated prominently in model 3 after adjusted for Hs-CRP, and no change was observed after further adjusted for BMI and albumin.Higher baseline TC and HDL-C levels are associated with better outcome in CHD patients with HF.

Associations of high HDL cholesterol level with all-cause mortality in patients with heart failure complicating coronary heart disease

The aim of the present study was to evaluate the association between HDL cholesterol level and all-cause mortality in patients with ejection fraction reduced heart failure (EFrHF) complicating coronary heart disease (CHD).A total of 323 patients were retrospectively recruited. Patients were divided into low and high HDL cholesterol groups. Between-group differences and associations between HDL cholesterol level and all-cause mortality were assessed.Patients in the high HDL cholesterol group had higher HDL cholesterol level and other lipid components (P <0.05 for all comparison). Lower levels of alanine aminotransferase (ALT), high-sensitivity C-reactive protein (Hs-CRP), and higher albumin (ALB) level were observed in the high HDL cholesterol group (P <0.05 for all comparison). Although left ventricular ejection fraction (LVEF) were comparable (28.8 ± 4.5% vs 28.4 ± 4.6%, P = 0.358), mean mortality rate in the high HDL cholesterol group was significantly lower (43.5% vs 59.1%, P = 0.007). HDL cholesterol level was positively correlated with ALB level, while inversely correlated with ALT, Hs-CRP, and NYHA classification. Logistic regression analysis revealed that after extensively adjusted for confounding variates, HDL cholesterol level remained significantly associated with all-cause mortality although the magnitude of association was gradually attenuated with odds ratio of 0.007 (95% confidence interval 0.001-0.327, P = 0.012).Higher HDL cholesterol level is associated with better survival in patients with EFrHF complicating CHD, and future studies are necessary to demonstrate whether increasing HDL cholesterol level will confer survival benefit in these populations of patients.

Nutrition, dietary interventions and prostate cancer: the latest evidence

Prostate cancer (PCa) remains a leading cause of mortality in US men and the prevalence continues to rise world-wide especially in countries where men consume a 'Western-style' diet. Epidemiologic, preclinical and clinical studies suggest a potential role for dietary intake on the incidence and progression of PCa. 'This minireview provides an overview of recent published literature with regard to nutrients, dietary factors, dietary patterns and PCa incidence and progression. Low carbohydrates intake, soy protein, omega-3 (w-3) fat, green teas, tomatoes and tomato products and zyflamend showed promise in reducing PCa risk or progression. A higher saturated fat intake and a higher β-carotene status may increase risk. A 'U' shape relationship may exist between folate, vitamin C, vitamin D and calcium with PCa risk. Despite the inconsistent and inconclusive findings, the potential for a role of dietary intake for the prevention and treatment of PCa is promising. The combination of all the beneficial factors for PCa risk reduction in a healthy dietary pattern may be the best dietary advice. This pattern includes rich fruits and vegetables, reduced refined carbohydrates, total and saturated fats, and reduced cooked meats. Further carefully designed prospective trials are warranted.

Associations of hydroxychloroquine use with lipid profiles in rheumatoid arthritis: pharmacologic implications

OBJECTIVE

To evaluate the association of hydroxychloroquine (HCQ) use with lipid profiles in a Veterans Affairs Rheumatoid Arthritis (VARA) cohort.

METHODS

Lipid profiles in HCQ users were compared with HCQ nonusers, adjusting for potential confounders (age, sex, race, disease activity, prednisone, disease-modifying antirheumatic drugs, diabetes mellitus, and statin use). Applying current National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III) guidelines for reduction of cardiovascular disease (CVD) events risk, the frequency of target lipid profiles with HCQ status was evaluated. Varied periods of HCQ exposure were compared to ascertain pharmacologic associations with lipid values. CVDs were compared between HCQ users and nonusers.

RESULTS

In an elderly, predominantly male VARA cohort, 1,011 patients had lipid profiles; 787 patients (77.8%) were white. Statin use was recorded in 11.6% of patients, diabetes mellitus in 33.5%, and CVD in 31.2%. HCQ users (n = 150) were older, had longer rheumatoid arthritis (RA) disease duration, and had lower disease activity. Optimum lipid profiles, including total cholesterol:high-density lipoprotein (HDL) and HDL:low-density lipoprotein ratios (P ≤ 0.001), were more frequent in HCQ users, with the exception of HDL (P = 0.165), and persisted in multivariate analyses. Similarly, more HCQ users had NCEP-ATP III target levels. Varied periods of HCQ exposure suggested lipid changes to occur early, but lost within a year of drug discontinuation. HCQ users had less prevalent CVD.

CONCLUSION

In RA patients, HCQ use of at least 3 months' duration was associated with better lipid profiles irrespective of disease activity or statin use. Given the increased CVD risks in RA and the relative low cost and toxicity of HCQ, continued use, regardless of treatment regimen, should be considered.

The relationship between nutrition and prostate cancer: is more always better?

CONTEXT

Prostate cancer (PCa) remains one of the most diagnosed malignancies in the world, correlating with regions where men consume more of a so-called Western-style diet. As such, there is much interest in understanding the role of lifestyle and diet on the incidence and progression of PCa.

OBJECTIVE

To provide a summary of published literature with regard to dietary macro- and micronutrients and PCa incidence and progression.

EVIDENCE ACQUISITION

A literature search was completed using the PubMed database for all studies published on diet and PCa in June 2012 or earlier. Primary literature and meta-analyses were given preference over other review articles when possible.

EVIDENCE SYNTHESIS

The literature was reviewed on seven dietary components: carbohydrates, protein, fat and cholesterol, vegetables, vitamins and minerals, and phytochemicals. Current literature linking these nutrients to PCa is limited at best, but trends in the published data suggest consumption of carbohydrates, saturated and ω-6 fats, and certain vitamin supplements may promote PCa risk and progression. Conversely, consumption of many plant phytochemicals and ω-3 fatty acids seem to slow the risk and progression of the disease. All other nutrients seem to have no effect or data are inconclusive. A brief summary about the clinical implications of dietary interventions with respect to PCa prevention, treatment, and survivorship is provided.

CONCLUSIONS

Due to the number and heterogeneity of published studies investigating diet and PCa, it is difficult to determine what nutrients make up the perfect diet for the primary and secondary prevention of PCa. Because diets are made of multiple macro- and micronutrients, further prospective studies are warranted, particularly those investigating the relationship between whole foods instead of a single nutritional component.

Reverse cholesterol transport in familial hypercholesterolemia

PURPOSE OF REVIEW

Familial hypercholesterolemia is characterized by a major elevation in circulating LDL-cholesterol levels, cholesterol deposition within the arterial wall and an increased risk of premature coronary artery disease. The reverse cholesterol transport (RCT) is now considered as a key process that protects against development of atherosclerosis. The major antiatherogenic action of HDL particles is intimately linked to their determinant role in RCT pathway. However, the steady-sate of HDL-cholesterol levels does not represent the optimal marker to evaluate the efficiency of the RCT in all circumstances.

RECENT FINDINGS

By using ex-vivo systems for the evaluation of the efficacy of RCT a strong inverse relationship between HDL efflux capacity from macrophages and atherosclerosis progression has been demonstrated. Low HDL-C phenotype observed in familial hypercholesterolemia patients is associated with defective capacities of HDL particles to mediate major steps of the centripetal movement of cholesterol from peripheral cells to feces. However, current available treatment used to reduce LDL-C to therapeutic goals does not correct altered functions of HDL particles in humans.

SUMMARY

In the context of familial hypercholesterolemia, a growing body of evidence suggests that impaired efficacy of the RCT pathway contributes significantly to the progression of atherosclerosis.

A nutrient-dense, high-fiber, fruit-based supplement bar increases HDL cholesterol, particularly large HDL, lowers homocysteine, and raises glutathione in a 2-wk trial

Dietary intake modulates disease risk, but little is known how components within food mixtures affect pathophysiology. A low-calorie, high-fiber, fruit-based nutrient-dense bar of defined composition (e.g., vitamins and minerals, fruit polyphenolics, β-glucan, docosahexaenoic acid) appropriate for deconstruction and mechanistic studies is described and evaluated in a pilot trial. The bar was developed in collaboration with the U.S. Department of Agriculture. Changes in cardiovascular disease and diabetes risk biomarkers were measured after 2 wk twice-daily consumption of the bar, and compared against baseline controls in 25 healthy adults. Plasma HDL-cholesterol (HDL-c) increased 6.2% (P=0.001), due primarily to a 28% increase in large HDL (HDL-L; P<0.0001). Total plasma homocysteine (Hcy) decreased 19% (P=0.017), and glutathione (GSH) increased 20% (P=0.011). The changes in HDL and Hcy are in the direction associated with decreased risk of cardiovascular disease and cognitive decline; increased GSH reflects improved antioxidant defense. Changes in biomarkers linked to insulin resistance and inflammation were not observed. A defined food-based supplement can, within 2 wk, positively impact metabolic biomarkers linked to disease risk. These results lay the groundwork for mechanistic/deconstruction experiments to identify critical bar components and putative synergistic combinations responsible for observed effects.

Lipid transfer to HDL is higher in marathon runners than in sedentary subjects, but is acutely inhibited during the run

Although exercise increases HDL-cholesterol, exercise-induced changes in HDL metabolism have been little explored. Lipid transfer to HDL is essential for HDL's role in reverse cholesterol transport. We investigated the effects of acute exhaustive exercise on lipid transfer to HDL. We compared plasma lipid, apolipoprotein and cytokine levels and in vitro transfer of four lipids from a radioactively labeled lipid donor nanoemulsion to HDL in sedentary individuals (n = 28) and in marathon runners (n = 14) at baseline, immediately after and 72 h after a marathon. While HDL-cholesterol concentrations and apo A1 levels were higher in marathon runners, LDL-cholesterol, apo B and triacylglycerol levels were similar in both groups. Transfers of non-esterified cholesterol [6.8 (5.7-7.2) vs. 5.2 (4.5-6), p = 0.001], phospholipids [21.7 (20.4-22.2) vs. 8.2 (7.7-8.9), p = 0.0001] and triacylglycerol [3.7 (3.1-4) vs. 1.3 (0.8-1.7), p = 0.0001] were higher in marathon runners, but esterified-cholesterol transfer was similar. Immediately after the marathon, LDL- and HDL-cholesterol concentrations and apo A1 levels were unchanged, but apo B and triacylglycerol levels increased. Lipid transfer of non-esterified cholesterol [6.8 (5.7-7.2) vs. 5.8 (4.9-6.6), p = 0.0001], phospholipids [21.7 (20.4-22.2) vs. 19.1 (18.6-19.3), p = 0.0001], esterified-cholesterol [3.2 (2.2-3.8) vs. 2.3 (2-2.9), p = 0.02] and triacylglycerol [3.7 (3.1-4) vs. 2.6 (2.1-2.8), p = 0.0001] to HDL were all reduced immediately after the marathon but returned to baseline 72 h later. Running a marathon increased IL-6 and TNF-α levels, but after 72 h these values returned to baseline. Lipid transfer, except esterified-cholesterol transfer, was higher in marathon runners than in sedentary individuals, but the marathon itself acutely inhibited lipid transfer. In light of these novel observations, further study is required to clarify how these metabolic changes can influence HDL composition and anti-atherogenic function.

Reverse D4F, an apolipoprotein-AI mimetic peptide, inhibits atherosclerosis in ApoE-null mice

OBJECTIVE

Synthetic class A amphipathic helical peptide analogs of apolipoprotein-AI (apoAI; with varied phenylalanine residues) are emerging therapeutic approaches under investigation for atherosclerosis. Utilizing retroinverso sequencing, we designed reverse-D4F (Rev-D4F) peptide with 18 d-amino acids containing 4 phenylalanine residues and reverse order that allows the side chain residues to be of exact alignment and superimposable to those of the parent l-amino acid peptide. This study examined the effect of Rev-D4F on atherosclerosis in apolipoprotein E (apoE)-null mice and the underlying mechanisms.

MATERIALS/METHODS

ApoE-null mice were fed a chow diet and administered water (control), Rev-D4F, or L4F mimetic peptides (0.4 mg/mL, equivalent to 1.6 mg/d) orally in drinking water for 6 weeks. Aortic root atherosclerotic lesion area, lesion macrophage content, and the ability of plasma high-density lipoprotein (HDL) to influence monocyte chemotaxis were measured.

RESULTS

Rev-D4F significantly decreased aortic sinus atherosclerotic lesion area and lesion macrophage content without affecting plasma total and HDL-cholesterol levels in apoE-null mice. The HDL from Rev-D4F-treated mice showed enhanced anti-inflammatory monocyte chemotactic activity, while low-density lipoprotein (LDL) exhibited reduced proinflammatory activity. In in vitro studies, Rev-D4F inhibited LDL oxidation, endothelial cell vascular cell adhesion molecule 1 (VCAM-1), and monocyte chemotactic factor 1 (MCP-1) expression, and monocyte adhesion to aortic endothelial cells.

CONCLUSIONS

The Rev-D4F inhibits atherosclerosis by inhibiting endothelial inflammatory/oxidative events and improving HDL function. The data suggest that Rev-D4F may be an effective apoAI mimetic peptide for further development in preventing atherosclerosis.

Association between Perchlorate and Indirect Indicators of Thyroid Dysfunction in NHANES 2001-2002, a Cross-Sectional, Hypothesis-Generating Study

BACKGROUND

A previous study based on NHANES 2001-2002 observed that increased levels of urinary perchlorate were associated with increased levels of thyroid stimulating hormone among all women, and with decreased levels of thyroxine among women with low urinary iodine. No associations were observed for men.

METHODS

Using the same NHANES 2001-2002 data, associations of urinary perchlorate with indirect biomarkers of thyroid hormone disruption were investigated. Decreased levels of hemoglobin (HGB), hematocrit (HCT), and high density lipoprotein (HDL) have been observed among subjects with subclinical hypothyroidism. To investigate the suitability of these indicators for use in observational studies, subjects were divided into six groups: boys, age 6-19; men, age 20-85; girls, age 6-14; non-pregnant women, age 15-49; women, age 50-85; and pregnant women. Use of perchlorate quintiles (Q1-Q5) and continuous log-transformed perchlorate in the regression models allowed investigation of both non-linear and linear associations. Adjustments were made for age, urinary creatinine, race/ethnicity, body mass index, cotinine, poverty index, hours of fasting, thiocyanate, nitrate, daily kcal intake, C-reactive protein. Adjustment for alcohol consumption depended on availability. Adjustment for prescription drugs (beta-blockers, sex hormones, antihyperlipidemic and antidiabetic drugs) was made if it changed the perchlorate estimate by ≥10%.

RESULTS

Statistically significant decreases were observed for HGB and HCT among boys, men, women age 15-49, and pregnant women, and for HDL among men.

CONCLUSIONS

Although the mean response biomarkers were within normal range, their association with urinary perchlorate is of interest. HGB and HCT among pregnant women showed a stronger association with urinary perchlorate than non-pregnant women age 15-49. Statistically significant associations were observed for individual perchlorate quintiles. Assumption of linearity of log-transformed perchlorate may result in underestimation of some associations.

Sphingomyelin synthase overexpression increases cholesterol accumulation and decreases cholesterol secretion in liver cells

BACKGROUND

Studies have shown that plasma high density lipoprotein cholesterol levels are negatively correlated with the development of atherosclerosis, whereas epidemiological studies have also shown that plasma sphingomyelin level is an independent risk factor for atherosclerosis.

METHODS

To evaluate the relationship between cellular sphingomyelin level and cholesterol metabolism, we created two cell lines that overexpressed sphingomyelin synthase 1 or 2 (SMS1 or SMS2), using the Tet-off expression system.

RESULTS

We found that SMS1 or SMS2 overexpression in Huh7 cells, a human hepatoma cell line, significantly increased the levels of intracellular sphingomyelin, cholesterol, and apolipoprotein A-I and decreased levels of apolipoprotein A-I and cholesterol in the cell culture medium, implying a defect in both processes.

CONCLUSIONS

Our findings indicate that the manipulation of sphingomyelin synthase activity could influence the metabolism of sphingomyelin, cholesterol and apolipoprotein A-I.

Sphingosylphosphorylcholine stimulates CCL2 production from human umbilical vein endothelial cells

Sphingosylphosphorylcholine (SPC) is a component of high-density lipoprotein particles. We investigated the functional role of SPC in HUVECs. SPC stimulation induced production of the CCL2 chemokine in a PTX-sensitive G-protein-dependent manner. SPC treatment caused the activation of NF-κB and AP-1, which are essential for SPC-induced CCL2 production, and induced the activation of three MAPKs, ERK, p38 MAPK, and JNK. Inhibition of p38 MAPK or JNK by specific inhibitors caused a dramatic decrease in SPC-induced CCL2 production. The Jak/STAT3 pathway was also activated upon SPC stimulation of HUVECs. Pretreatment with a Jak inhibitor blocked not only SPC-induced p38 MAPK and JNK activation, but also NF-κB and AP-1 activation. Our results suggest that SPC stimulates HUVECs, resulting in Jak/STAT3-, NF-κB-, and AP-1-mediated CCL2 production. We also observed that SPC stimulated expression of the adhesion molecule ICAM-1 in HUVECs. Our results suggest that SPC may contribute to atherosclerosis; therefore, SPC and its unidentified target receptor offer a starting point for the development of a treatment for atherosclerosis.

Transcriptional regulation of T helper 17 cell differentiation

The third lineage of T helper subsets, Th17, has recently been identified as an IL- 17-producing CD4+ Th cell, and its functions and regulatory mechanisms have been extensively characterized in immune responses. Functional studies have provided evidence that Th17 cells are important for the modulation of autoimmune responses, such as chronic asthma, rheumatoid arthritis, inflammatory bowel diseases, and multiple sclerosis. Murine Th17 cell differentiation is enhanced by the coordinated functions of distinct cytokines including TGFbeta, IL-6, IL-21, and IL-23, whereas IL-2, IL-4, IFNgamma, and IL-27 inhibit its differentiation. In addition, Th17 cells are controlled by several transcription factors such as RORgammat, IRF4, BATF, FoxP3, T-bet, PPARgamma, E-FABP, and SOCSs. This review focuses on the functions and regulatory mechanisms of several transcription factors in the control of Th17 cell differentiation.

Pioglitazone increases apolipoprotein A-I production by directly enhancing PPRE-dependent transcription in HepG2 cells

Pioglitazone, a hypoglycemic agent, has been shown to increase plasma HDL cholesterol, but the mechanism is incompletely understood. We further investigated effects of pioglitazone on transcriptional regulation of apolipoprotein (apo)A-I gene and functional properties of pioglitazone-induced apoA-I-containing particles. Pioglitazone dose-dependently stimulated apoA-I promoter activities in HepG2 cells. A peroxisome proliferator-activated receptor (PPAR)-response element located in site A (-214 to -192 bp, upstream of the transcription start site) of the promoter is required for pioglitazone-induced apoA-I gene transcription. Deletion of site A (-214 to -192 bp), B (-169 to -146 bp), or C (-134 to -119 bp), which clusters a number of cis-acting elements for binding of different transcription factors, reduced the basal apoA-I promoter activities, and no additional pioglitazone-sensitive elements were found within this region. Overexpression or knock-down of liver receptor homolog-1, a newly identified nuclear factor with strong stimulatory effect on apoA-I transcription, did not alter pioglitazone-induced apoA-I transcription. Pioglitazone-induced apoA-I transcription is mainly mediated through PPARalpha but not PPARgamma in hepatocytes. Pioglitazone induced production of HDL enriched in its subfraction containing apoA-I without apoA-II, which inhibited monocyte adhesion to endothelial cells in vitro. In conclusion, pioglitazone increases apoA-I production by directly enhancing PPAR-response element-dependent transcription, resulting in generation of apoA-I-containing HDL particles with increased anti-inflammatory property.

Hypolipidaemic and antiplatelet activity of phenoxyacetic acid derivatives related to α-asarone

The phenoxyacetic acid derivatives 1–6 [2-methoxy-4-(2-propenyl)phenoxyacetic acid (1); 2-methoxy-5-nitro-4-(2-propenyl)phenoxyacetic acid (2); methyl 2-methoxy-4-(2-propenyl)phenoxyacetate (3); ethyl 2-methoxy-4-(2-propenyl)phenoxyacetate (4); methyl 2-methoxy-5-nitro-4-(2-propenyl)phenoxyacetate (5); ethyl 2-methoxy-5-nitro-4-(2-propenyl)phenoxyacetate (6)] related to α-asarone have been reported previously as hypolipidaemic agents in diet-induced hyperlipidaemic mice. We have aimed to expand the pharmacological profile of these derivatives by investigating their hypolipidaemic activity in rats and mice under different experimental conditions. The antiplatelet activity was tested also in-vitro from blood derived from consenting healthy volunteers. In normolipidaemic rats, compounds 2, 3 and 5 at oral doses of 40 and 80 mg kg−1 significantly decreased total cholesterol and LDL-cholesterol levels. Moreover, analogues 3 and 5 administered to hypercholesterolaemic rats at the same doses for seven days also produced a reduction in the content of these same lipoproteins. In neither case were the high-density lipoprotein cholesterol and triglyceride concentrations affected. However, practically all tested compounds were found to be hypocholesterolaemic agents, and were shown to effectively lower low-density lipoprotein cholesterol and triglyceride levels in Triton-induced hyperlipidaemic mice at oral doses of 50 and 100 mg kg−1. In all tests, all animals appeared to be healthy throughout the experimental period in their therapeutic ranges. Triton-induced hypercholesterolaemic mice appeared to be a desirable model for this class of hypolipidaemic drugs. On the other hand, compounds 1, 2, 4 and 5 significantly inhibited ADP-induced aggregation in-vitro. These findings indicated that all of these compounds appeared to be promising for the treatment of human hyperlipidaemia and thrombotic diseases.

Higher HDL cholesterol levels are associated with a lower incidence of chronic kidney disease in patients with type 2 diabetes

BACKGROUND AND AIMS

Type 2 diabetes is one of the most important risk factor for the development of chronic kidney disease (CKD). Recently, it has been shown that lower high-density lipoprotein cholesterol (HDL-C) levels predicted the development of microalbuminuria in type 2 diabetic individuals. We have prospectively assessed the effects of plasma HDL-C levels on the incidence of CKD in a large cohort of type 2 diabetic patients.

METHODS AND RESULTS

We followed 1987 type 2 diabetic outpatients with normal or near-normal kidney function at baseline for 5 years for the occurrence of incident CKD defined as glomerular filtration rate < or = 60 mL/min/1.73 m(2) (as estimated by the abbreviated Modified Diet and Renal Disease Study equation). Cox proportional hazards models were used to examine the independent relationship between plasma HDL-C levels and incident CKD. During a median follow-up of 5 years, 11.8% (n=234) of participants developed incident CKD. In multivariate regression analysis, higher HDL-C levels were associated with a lower risk of incident CKD (multiple-adjusted hazard ratio 0.76; 95% coefficient intervals 0.61-0.96; p=0.025) independently of age, gender, body mass index, hypertension, smoking history, diabetes duration, hemoglobin A1c, plasma triglycerides, LDL-cholesterol, presence of diabetic retinopathy, baseline albuminuria, and current use of medications (anti-hypertensive, anti-platelet, lipid-lowering and hypoglycemic drugs).

CONCLUSIONS

Higher plasma levels of HDL-C are associated with a lower risk of incident CKD in a large cohort of type 2 diabetic adults independently of numerous confounding factors.

Association between change in high density lipoprotein cholesterol and cardiovascular disease morbidity and mortality: systematic review and meta-regression analysis

OBJECTIVE

To investigate the association between treatment induced change in high density lipoprotein cholesterol and total death, coronary heart disease death, and coronary heart disease events (coronary heart disease death and non-fatal myocardial infarction) adjusted for changes in low density lipoprotein cholesterol and drug class in randomised trials of lipid modifying interventions.

DESIGN

Systematic review and meta-regression analysis of randomised controlled trials.

DATA SOURCES

Medline, Embase, Central, CINAHL, and AMED to October 2006 supplemented by contact with experts in the field.

STUDY SELECTION

In teams of two, reviewers independently determined eligibility of randomised trials that tested lipid modifying interventions to reduce cardiovascular risk, reported high density lipoprotein cholesterol and mortality or myocardial infarctions separately for treatment groups, and treated and followed participants for at least six months.

DATA EXTRACTION AND SYNTHESIS

Using standardised, pre-piloted forms, reviewers independently extracted relevant information from each article. The change in lipid concentrations for each trial and the weighted risk ratios for clinical outcomes were calculated.

RESULTS

The meta-regression analysis included 108 randomised trials involving 299 310 participants at risk of cardiovascular events. All analyses that adjusted for changes in low density lipoprotein cholesterol showed no association between treatment induced change in high density lipoprotein cholesterol and risk ratios for coronary heart disease deaths, coronary heart disease events, or total deaths. With all trials included, change in high density lipoprotein cholesterol explained almost no variability (<1%) in any of the outcomes. The change in the quotient of low density lipoprotein cholesterol and high density lipoprotein cholesterol did not explain more of the variability in any of the outcomes than did the change in low density lipoprotein cholesterol alone. For a 10 mg/dl (0.26 mmol/l) reduction in low density lipoprotein cholesterol, the relative risk reduction was 7.2% (95% confidence interval 3.1% to 11%; P=0.001) for coronary heart disease deaths, 7.1% (4.5% to 9.8%; P<0.001) for coronary heart disease events, and 4.4% (1.6% to 7.2%; P=0.002) for total deaths, when adjusted for change in high density lipoprotein cholesterol and drug class.

CONCLUSIONS

Available data suggest that simply increasing the amount of circulating high density lipoprotein cholesterol does not reduce the risk of coronary heart disease events, coronary heart disease deaths, or total deaths. The results support reduction in low density lipoprotein cholesterol as the primary goal for lipid modifying interventions.

Nicotinic acid: pharmacological effects and mechanisms of action

Pharmacological doses of nicotinic acid induce a profound change in the plasma levels of various lipids and lipoproteins. The ability of nicotinic acid to strongly increase the plasma concentration of high-density lipoprotein (HDL) cholesterol has in recent years led to an increased interest in the pharmacological potential of nicotinic acid. There is increasing evidence that nicotinic acid alone or in addition to LDL cholesterol-lowering drugs can reduce the progression of atherosclerosis and reduce the risk of cardiovascular events. The clinical use of nicotinic acid is, however, hindered by harmless but unpleasant side effects, especially by a strong cutaneous vasodilation called flushing. The recent discovery of the G protein-coupled receptor GPR109A (HM74A or PUMA-G) as a receptor for nicotinic acid has allowed for better understanding of the mechanisms underlying the metabolic and vascular effects of nicotinic acid. On the basis of recent progress in understanding the pharmacological effects of nicotinic acid, new strategies are in development to better exploit the pharmacological potential of nicotinic acid. New drugs acting via the nicotinic acid receptor or related receptors, as well as new co-medications that suppress unwanted effects of nicotinic acid, will most likely be introduced as new therapeutic options in the treatment of dyslipidemia and the prevention of cardiovascular diseases.

Effects of D-003, a mixture of high-molecular-weight sugar cane wax acids, on lipid peroxidation markers in older individuals: A randomized, double-blind, placebo-controlled study

BACKGROUND

Aging is associated with increased lipid peroxidation (LP). D-003, a mixture of long-chain aliphatic primary acids purified from sugar cane wax, has been found to inhibit LP in experimental models and in healthy subjects.

OBJECTIVES

The aim of this study was to assess the effects of D-003 on LP markers and the lipid profile of older individuals.

METHODS

This randomized, double-blind, placebo-controlled study was conducted at the Plaza Veterans' House, Havana City, Cuba. Male and female patients aged ≥60 years with total cholesterol values of <6.1 mmol/L were eligible for inclusion in the study. After a 3-week lead-in and baseline assessment period, patients were randomized to receive PO D-003 5 mg/d, D-003 10 mg/d, or placebo for 8 weeks. The effect on copper-induced LP of low-density lipoprotein (LDL) particles was the primary variable, and the effects on plasma total antioxidant status (TAS), plasma malondialdehyde (MDA) concentration, plasma antioxidant enzyme (superoxide dismutase and glutathione peroxidase) activities, and the lipid profile were secondary variables. A clinical examination was performed at each visit (baseline, weeks 4 and 8). A clinical examination, LP, and blood tests (lipid profile, hematologic, and blood biochemistry safety indicators) were performed at baseline and after 8 weeks of treatment. Compliance and adverse events (AEs) were assessed at weeks 4 and 8. A 2-tailed P < 0.05 was considered statistically significant for comparisons of both continuous and categoric variables.

RESULTS

Fifty-four patients aged ≥60 years were assessed for inclusion in the study, and 51 patients (40 women, 11 men; mean [SD] age, 67 [6] years) were included in the study. The lag phase of conjugated diene formation increased significantly and in a dose-dependent manner in the group treated with D-003 5 mg (24.7%; P < 0.01) and in the group treated with D-003 10 mg (29.3%; P < 0.01) compared with placebo. The maximal rate of conjugated diene propagation decreased significantly in the D-003 5- and 10-mg groups -22.7% and -25.8%, respectively; both, P < 0.05) compared with placebo. TAS increased significantly (17.7% and 23.0%, respectively; both, P < 0.01) in both active treatment groups compared with placebo. Plasma MDA concentration decreased significantly in the D-003 10-mg group (-28.6%; P < 0.05) but not in the D-003 5-mg group, compared with placebo. These changes were also significant compared with baseline. Antioxidant enzyme activities did not change in the active treatment groups compared with placebo or baseline. In the D-003 5- and 10-mg groups, significant decreases were found in LDL cholesterol concentration (-15.8% and -23.8%, respectively; both, P < 0.001) and total cholesterol concentration (-13.0% and -16.8%, both, P < 0.05) compared with placebo. High-density lipoprotein cholesterol concentration increased significantly in the D-003 5-mg group (5.7%; P < 0.05) and the D-003 10-mg group (18.2%; P < 0.001) compared with placebo. Changes in the lipid profile were also significant compared with baseline. In the placebo group, no variable changed significantly compared with baseline. D-003 was well tolerated at both dose levels, and no patient withdrew from the study. There were a total of 3 AEs reported: insomnia and acidity in 2 patients receiving placebo; and heartburn in 1 patient receiving D-003 5 mg.

CONCLUSIONS

D-003 5 and 10 mg/d administered to these older individuals (aged ≥60 years) for 8 weeks inhibited LP of LDL and increased TAS in a dose-dependent manner, while plasma MDA concentration decreased in the patients receiving D-003 10 mg/d only. D-003 was well tolerated at both doses.

Pioglitazone stimulates apolipoprotein A-I production without affecting HDL removal in HepG2 cells: involvement of PPAR-alpha

OBJECTIVE

Pioglitazone, an antihyperglycemic drug, increases plasma high-density lipoprotein (HDL)-cholesterol in patients with type 2 diabetes. The mechanisms by which pioglitazone regulate HDL levels are not clear. This study examined the effect of pioglitazone on hepatocyte apolipoprotein AI (apoA-I) and apoA-II production and HDL-protein/cholesterol ester uptake.

METHODS AND RESULTS

In human hepatoblastoma (HepG2) cells, pioglitazone, dose-dependently (0.5 to 10 micromol/L), increased the de novo synthesis (up to 45%), secretion (up to 44%), and mRNA expression (up to 59%) of apoA-I. Pioglitazone also increased apoA-II de novo synthesis (up to 73%) and mRNA expression (up to 129%). Pioglitazone did not affect the uptake of HDL3-protein or HDL3-cholesterol ester in HepG2 cells. The pioglitazone-induced apoA-I lipoprotein particles increased cholesterol efflux from THP-1 macrophages. The pioglitazone-induced apoA-I secretion or mRNA expression by the HepG2 cells was abrogated with the suppression of PPAR-alpha by small interfering RNA or a specific inhibitor of PPAR-alpha, MK886.

CONCLUSIONS

The data indicate that pioglitazone increases HDL by stimulating the de novo hepatic synthesis of apoA-I without affecting hepatic HDL-protein or HDL-cholesterol removal. We suggest that pioglitazone-mediated hepatic activation of PPAR-alpha may be one of the mechanisms of action of pioglitazone to raise hepatic apoA-I and HDL.

The effect of NeOpuntia on blood lipid parameters--risk factors for the metabolic syndrome (syndrome X)

Metabolic syndrome (syndrome X) causes millions of cardiovascular complications and premature deaths every year. The aim of this study was to evaluate the effects of NeOpuntia, patented, dehydrated, Opuntia ficus-indica leaves, on blood lipid parameters and metabolic syndrome. Opuntia ficus-indica leaves are traditionally consumed as a vegetable. Participants in this monocentric, randomized, placebocontrolled, double-blind, 6-wk study were 68 women, ages 20 to 55 y, with metabolic syndrome and a body mass index between 25 and 40. Fifty-nine subjects completed the study according to the study plan. All volunteers followed wellbalanced diets with controlled lipid input. NeOpuntia or placebo capsules were taken at a dosage of 1.6 g per meal. All 5 syndrome X criteria were measured on days 0, 14, and 42, including low-density lipoprotein cholesterol (LDL-C), highdensity lipoprotein cholesterol (HDL-C), and triglyceride levels. For the 42 females above 45 y of age, we show a significant increase in HDL-C levels with NeOpuntia and a tendency toward decreased triglyceride levels. At the same time, there was a decrease in HDL-C levels with placebo. Overall, for the entire study population, similar but less pronounced tendencies were demonstrated. Forty-two females taking NeOpuntia with no additional hypolipemic treatment, had a pronounced reduction in LDL cholesterol, especially after day 14. At the study end, 39% of the NeOpuntia group, but only 8% of the placebo group, were no longer diagnosed with metabolic syndrome. Our results indicate an advantage of using NeOpuntia in dietary supplements and functional foods because of improvement of blood lipid parameters associated with cardiovascular risks.

[Lipid profile of patients with increased risk for cardiovascular events in daily clinical practice]

Although there are specific guidelines regarding the treatment of dyslipidemia in highly risk patients, these recommendations are usually inadequately followed. The aim of this study is to investigate risk factors in patients with increased cardiovascular risk currently treated in Brazil and Venezuela. Medical charts of 412 patients were selected in 4 institutions. Patients were divided into groups according to the use of lipid-lowering drugs (LLD), particularly statins. Patients who did not use LLD showed higher levels of total cholesterol (p< 0.001), LDL cholesterol (p< 0,001) and HDL cholesterol (p< 0.001), besides lower levels of triglycerides (p< 0.001). The use of statins was associated with a decrease in levels of total cholesterol (from 251.0 +/- 40.0 to 196.0 +/- 46.0), LDL cholesterol (from 168.0 +/- 36.0 to 116.0 +/- 39.0), HDL cholesterol (from 51.0 +/- 46.0 to 46.0 +/- 12.0) and triglycerides (from 181.0 +/- 120.0 to 160.0 +/-79.0). Finally, only a small percentage of patients, even those under treatment with LLD, showed cholesterol levels according to currently available guidelines. Therefore, although the guidelines for the treatment of dyslipidemia are widely known, only a small percentage of patients achieve adequate levels of cholesterol. It is necessary to decrease lipid levels of these patients by increasing the dose of the statins or using a second drug.

Myeloperoxidase Predicts Progression of Carotid Stenosis in States of Low High-Density Lipoprotein Cholesterol

OBJECTIVES

We investigated the effect of myeloperoxidase (MPO) on progression of carotid stenosis in states of high and low high-density lipoprotein-cholesterol (HDL-C) and low-density lipoprotein-cholesterol (LDL-C) levels.

BACKGROUND

Myeloperoxidase is pivotally involved in the pathogenesis of atherosclerosis. In vitro data suggest that MPO exerts deleterious effects via oxidative modulation of lipoproteins.

METHODS

We prospectively studied 1,019 of 1,268 consecutive patients who were asymptomatic with respect to carotid artery disease. Patients underwent serial carotid ultrasound investigations at baseline and after a follow-up interval of median 7.5 months (range 6 to 9 months), categorizing carotid arteries as 0% to 29%, 30% to 49%, 50% to 69%, 70% to 89%, or 90% to 99% stenosed or occluded. The MPO, HDL-C, and LDL-C levels were measured at baseline, grouped by medians, and correlated with progression of carotid atherosclerosis.

RESULTS

Progression of carotid atherosclerosis was found in 100 of 1,019 patients (9.8%). Myeloperoxidase (p = 0.014) but not HDL-C (p = 0.95) or LDL-C (p = 0.30) were associated with progressive disease. However, MPO > or =310 ng/ml was significantly associated with progressive disease (adjusted odds ratio [OR] 2.57, 95% confidence interval [CI] 1.39 to 4.75) only in patients with HDL-C levels <49 mg/dl. Otherwise, in patients with higher HDL-C levels (> or =49 mg/dl), MPO > or =310 ng/ml did not predict disease progression (adjusted OR 1.42, 95% CI 0.72 to 2.78). No interaction of MPO with LDL-C was observed.

CONCLUSIONS

Myeloperoxidase was associated with progression of carotid atherosclerosis in patients with HDL cholesterol levels below 49 mg/dl.

GPR109A (PUMA-G/HM74A) mediates nicotinic acid-induced flushing

Nicotinic acid (niacin) has long been used as an antidyslipidemic drug. Its special profile of actions, especially the rise in HDL-cholesterol levels induced by nicotinic acid, is unique among the currently available pharmacological tools to treat lipid disorders. Recently, a G-protein-coupled receptor, termed GPR109A (HM74A in humans, PUMA-G in mice), was described and shown to mediate the nicotinic acid-induced antilipolytic effects in adipocytes. One of the major problems of the pharmacotherapeutical use of nicotinic acid is a strong flushing response. This side effect, although harmless, strongly affects patient compliance. In the present study, we show that mice lacking PUMA-G did not show nicotinic acid-induced flushing. In addition, flushing in response to nicotinic acid was also abrogated in the absence of cyclooxygenase type 1, and mice lacking prostaglandin D(2) (PGD(2)) and prostaglandin E(2) (PGE(2)) receptors had reduced flushing responses. The mouse orthologue of GPR109A, PUMA-G, is highly expressed in macrophages and other immune cells, and transplantation of wild-type bone marrow into irradiated PUMA-G-deficient mice restored the nicotinic acid-induced flushing response. Our data clearly indicate that GPR109A mediates nicotinic acid-induced flushing and that this effect involves release of PGE(2) and PGD(2), most likely from immune cells of the skin.

Pharmacologic augmentation of high-density lipoproteins: mechanisms of currently available and emerging therapies

PURPOSE OF REVIEW

With the limited effects of low-density lipoprotein-based lipid intervention, more attention is being paid to drugs that augment or mimic high-density lipoprotein's beneficial effects. A thorough understanding of the anti-atherogenic effects of high-density lipoprotein, and the mechanisms of existing or emerging high-density lipoprotein-based therapies, is essential for rational strategy for the prevention of cardiovascular disease.

RECENT FINDINGS

High-density lipoprotein mediates its beneficial effects through reverse cholesterol transport and direct anti-inflammatory effects of apolipoprotein AI and other component parts. Currently available drugs increase high-density lipoprotein-C through increasing apoAI synthesis (statins, fibrates) and decreasing apolipoprotein AI catabolism (niacin). Cholesteryl ester transfer protein inhibitors dramatically raise high-density lipoprotein-C, but clinical data are still required to verify their cardioprotective effects. Novel therapies such as apolipoprotein AImilano, apolipoprotein AI mimetic peptide, and exogenous phospholipids show tremendous promise as treatments for atherosclerosis.

SUMMARY

High-density lipoprotein and its defining functional protein apoAI prevent atherosclerosis through reverse cholesterol transport and other direct effects. Research has led to the development of novel therapies that increase high-density lipoprotein-C or that mimic direct anti-atherogenic effects of apolipoprotein AI. As these emerging therapies find a place in clinical medicine, we can anticipate preventing a much higher degree of cardiovascular events.

Transcriptional regulatory networks in lipid metabolism control ABCA1 expression

The ATP-binding cassette transporters, ABCA1 and ABCG1, are major players in mediating cellular efflux of phospholipids and cholesterol to apoA-I containing lipoproteins including prebeta-HDL and alphaHDL and thereby exert important antiatherogenic properties. Although the exact mechanisms how ABC transporters mediate lipid transport are not completely resolved, recent evidence from several laboratories including ours suggests that vesicular transport processes involving different interactive proteins like beta2-syntrophin, alpha1-syntrophin, Lin7, and cdc42 are critically involved in cellular lipid homeostasis controlled by ABCA1 and ABCG1. Besides sterols and fatty acids as known physiological modulators of the LXR/RXR and SREBP pathways, a growing list of natural and synthetic substances and metabolic regulators such as retinoids, PPAR-ligands, hormones, cytokines, and drugs are particularly effective in modulating ABCA1 and ABCG1 gene expression. Although ABCA1 protein amounts are regulated at the level of stability, the majority of potent activating and repressing mechanisms on ABCA1 function directly act on the ABCA1 gene promoter. Among the inducing factors, liver-X-receptors (LXR), retinoic acid receptors (RAR) and peroxisome proliferator-activated receptors (PPARs) along with their coactivators provide an amplification loop for ABCA1 and ABCG1 expression. The ABCA1 promoter is further stimulated by the ubiquitous factor Sp1 and the hypoxia-induced factor 1 (HIF1), which bind to GC-boxes and the E-box, respectively. Shutdown of ABCA1 expression in the absence of sterols or in certain tissues is mediated by corepressor complexes involving unliganded LXR, sterol-regulatory element binding protein 2 (SREBP2), Sp3, and the SCAN-domain protein ZNF202, which also impacts nuclear receptor signaling. Thus, a highly sophisticated transcriptional network controls the balanced expression of ABCA1.

Mechanisms mediating insulin resistance in transgenic mice overexpressing mouse apolipoprotein A-II

We previously demonstrated that transgenic mice overexpressing mouse apolipoprotein A-II (apoA-II) exhibit several traits associated with the insulin resistance (IR) syndrome, including increased atherosclerosis, hypertriglyceridemia, obesity, and IR. The skeletal muscle appeared to be the insulin-resistant tissue in the apoA-II transgenic mice. We now demonstrate a decrease in FA oxidation in skeletal muscle of apoA-II transgenic mice, consistent with reports that decreased skeletal muscle FA oxidation is associated with increased skeletal muscle triglyceride accumulation, skeletal muscle IR, and obesity. The decrease in FA oxidation is not due to decreased carnitine palmitoyltransferase 1 activity, because oxidation of palmitate and octanoate were similarly decreased. Quantitative RT-PCR analysis of gene expression demonstrated that the decrease in FA oxidation may be explained by a decrease in medium chain acyl-CoA dehydrogenase. We previously demonstrated that HDLs from apoA-II transgenic mice exhibit reduced binding to CD36, a scavenger receptor involved in FA metabolism. However, studies of combined apoA-II transgenic and CD36 knockout mice suggest that the major effects of apoA-II are independent of CD36. Rosiglitazone treatment significantly ameliorated IR in the apoA-II transgenic mice, suggesting that the underlying mechanisms of IR in this animal model may share common features with certain types of human IR.