Peroxisome Proliferator-Activated Receptor-γ Agonist Increases Both Low-Density Lipoprotein Cholesterol Particle Size and Small High-Density Lipoprotein Cholesterol in Patients with Type 2 Diabetes Independent of Diabetic Control

Small dense low-density lipoprotein-lowering agents

Metabolic disorders, including obesity, diabetes, and hyperlipidemia, as well as cardiovascular diseases (CVD), particularly atherosclerosis, are still leading causes of death worldwide. Plasma levels of low-density lipoprotein (LDL) are currently being considered as a critical risk factor for the diseases mentioned above, especially atherosclerosis. Because of the heterogeneous nature of LDL, many studies have already been conducted on its subclasses, especially small dense LDL (sdLDL). According to available evidence, sdLDL levels can be considered as an ideal alternative to LDL levels for monitoring CVD and early diagnosis of atherosclerosis. Recently, several researchers have focused on factors that are able to decrease sdLDL levels and improve health quality. Therefore, the purpose of this study is to describe the production process of sdLDL particles and review the effects of pharmaceutical and dietary agents as well as lifestyle on sdLDL plasma levels. In brief, their mechanisms of action are discussed. Apparently, cholesterol and LDL-lowering compounds are also effective in the reduction of sdLDL levels. In addition, improving lipid profile, especially the reduction of triglyceride levels, appropriate regimen, and lifestyle can decrease sdLDL levels. Therefore, all the aforementioned parameters should be taken into consideration simultaneously in sdLDL levels reducing strategies.

HDL inflammation and atherosclerosis: current and future perspectives

The role of high-density lipoprotein (HDL) in the genesis and evolution of cardiovascular disease is a topical and interesting issue. Reduced HDL concentrations appear to be unable to efficiently eliminate the cholesterol excess at the vascular wall level, contributing to the onset of the inflammatory response that typically occurs in the pathogenesis of atherosclerosis from its earliest stages. In the last decade, many studies have explored the possibility of reducing cardiovascular risk through modulation of HDL levels, glimpsing new fascinating therapeutic horizons. This review summarizes recent findings on HDL and cardiovascular disease, mainly with an educational objective, considering the biochemical, cellular and molecular aspects of these particles.

Clinical applications of advanced lipoprotein testing in diabetes mellitus

Traditional lipid profiles often fail to fully explain the elevated cardiovascular risk of individuals with diabetes mellitus. Advanced lipoprotein testing offers a novel means to evaluate dyslipidemia and refine risk estimation. Numerous observational studies have demonstrated a characteristic pattern of elevated levels of small, dense LDL particles, out of proportion to traditional lipid levels, in patients with both diabetes mellitus and the metabolic syndrome. Commonly used glucose and lipid-lowering agents have varied effects in patients with diabetes on both LDL and HDL subfractions. The exact role of advanced lipoprotein testing in patients with diabetes mellitus and the metabolic syndrome remains unclear but may offer improved assessment of cardiovascular risk compared with traditional lipid measurements.

Effects of peroxisome proliferator-activated receptors, dietary fat intakes and gene-diet interactions on peak particle diameters of low-density lipoproteins

The risk of cardiovascular diseases (CVDs) is modulated by gene-diet interactions. The objective of this study was to examine whether gene-diet interactions affect peak particle diameters (PPD) of low-density lipoprotein (LDL).

METHODS

The study included 674 participants. A food frequency questionnaire was administered to obtain dietary information. LDL-PPD was determined by non-denaturing 2-16% polyacrylamide gradient gel electrophoresis. Peroxisome proliferator-activated receptor (PPAR) gene polymorphisms PPARα L162V (rs1800206), PPARγ P12A (rs1801282) and PPARδ -87T→C (rs2016520) were determined by PCR-RFLP.

RESULTS

Among carriers of thePPARα L162V polymorphism, gene-diet interaction effects on LDL-PPD were observed with saturated fat (p=0.0005) and total dietary fat (p=0.006). Among PPARα V162 carriers, subjects with higher saturated fat intakes had smaller LDL-PPD than those with lower intakes (254.23±2.74 vs. 256.21±2.61 Å, respectively, p=0.007). Among subjects homozygous for the PPARα L162 allele, those with higher saturated fat intakes had larger LDL-PPD than those with lower saturated fat intakes (255.86±2.66 vs. 255.05±2.65 Å, respectively, p=0.01). Gene-diet interactions were also found for PPARγ P12A polymorphism with saturated fat intake (p=0.04) and for PPARδ -87T→C with the polyunsaturated/saturated fat ratio (p=0.0013).

CONCLUSIONS

These results stress that dietary factors should be included in studies determining the effect of different polymorphisms on CVD risk factors.

MBX-102/JNJ39659100, a novel non-TZD selective partial PPAR-γ agonist lowers triglyceride independently of PPAR-α activation

MBX-102/JNJ-39659100 (MBX-102) is a selective, partial PPAR-γ agonist that lowers glucose in the absence of some of the side effects, such as weight gain and edema, that are observed with the TZDs. Interestingly MBX-102 also displays pronounced triglyceride lowering in preclinical rodent models and in humans. Although in vitro reporter gene studies indicated that MBX-102 acid is a highly selective PPAR-γ agonist that lacks PPAR-α activity, we sought to determine if PPAR-α activation in vivo could possibly contribute to the triglyceride lowering abilities of MBX-102. In vivo studies using ZDF and ZF rats demonstrated that MBX-102 lowered plasma triglycerides. However in ZF rats, MBX-102 had no effect on liver weight or on hepatic expression levels of PPAR-α target genes. Further in vitro studies in primary human hepatocytes supported these findings. Finally, the ability of MBX-102 to lower triglycerides was maintained in PPAR-α knockout mice, unambiguously establishing that the triglyceride lowering effect of MBX-102 is PPAR-α independent. The in vivo lipid lowering abilities of MBX-102 are therefore mediated by an alternate mechanism which is yet to be determined.

Rosiglitazone increases small dense low-density lipoprotein concentration and decreases high-density lipoprotein particle size in HIV-infected patients

After 12 weeks of rosiglitazone treatment, significant increases in total and small dense low-density lipoprotein, and the total: high-density lipoprotein (HDL)-cholesterol ratio were found. The large HDL concentration and HDL particle size decreased significantly with rosiglitazone compared with placebo. These data indicate the production of a more atherogenic lipid profile with rosiglitazone, a consideration when selecting treatment for the growing population of HIV-infected patients with type 2 diabetes and dyslipidemia.

Effect of Divalproex on Metabolic Parameters Is Dose Related in Migraine Prophylaxis

OBJECTIVE

To examine the metabolic effects of three divalproex dosing regimens in patients with migraine.

BACKGROUND

Epidemiological and clinical studies have demonstrated a strong association between serum lipid levels and the development of coronary artery disease. Thus, it is important to understand the impact of chronically administered medications on serum lipids. Metabolic properties of divalproex, an approved and commonly used treatment for migraine prophylaxis, have not been systematically studied in patients with migraine.

METHODS

Adult patients with migraine were randomized to receive one of three daily doses of divalproex (500 mg [n = 45], 1000 mg [n = 43], or 1500 mg [n = 44]) or placebo (n = 44) for 12 weeks. Post hoc analyses were performed to determine the effects of divalproex on total cholesterol, glucose, weight, and body mass index (BMI).

RESULTS

The treatment groups were similar at baseline based on demographic and clinical characteristics and the use of concomitant medications. Divalproex resulted in a dose-related mean decrease from baseline in total cholesterol: -5.7 mg/dL or 3% reduction with 500 mg/day; -8.4 mg/dL or 4% reduction with 1000 mg/day; and -12.8 mg/dL or 7% reduction with 1500 mg/day (P < .05 for 1500 mg/day vs. placebo). There were no differences between any divalproex dose group and placebo for mean change from baseline in glucose, weight, or BMI.

CONCLUSIONS

Divalproex results in a dose-dependent reduction in serum cholesterol within the first 3 months of therapy, with no significant change in serum glucose or BMI.

HDL as a target in the treatment of atherosclerotic cardiovascular disease

Lipid abnormalities are among the key risk factors for cardiovascular disease. Indeed, lipid-modifying drugs - in particular, the statins, which primarily lower plasma levels of low-density lipoprotein (LDL) cholesterol - considerably reduce the risk of cardiovascular events, leading to their widespread use. Nevertheless, it seems that there might be limits to the degree of benefit that can be achieved by lowering LDL-cholesterol levels alone, which has led to increased interest in targeting other lipid-related risk factors for cardiovascular disease, such as low levels of high-density lipoprotein (HDL) cholesterol. In this article, we first consider the mechanisms that underlie the protective effect of HDL cholesterol, and then discuss several strategies that have recently emerged to increase levels of HDL cholesterol to treat cardiovascular disease, including nuclear receptor modulation, inhibition of cholesteryl ester transfer protein and infusion of apolipoprotein/phospholipid complexes.

Pioglitazone in a subgroup of patients with type 2 diabetes meeting the criteria for metabolic syndrome

Pioglitazone monotherapy and combinations were assessed in patients with type 2 diabetes and metabolic syndrome (Adult Treatment Panel III criteria) from four worldwide randomised, multicentre, double-blind studies. Patients were treated for 52 weeks with pioglitazone (PIO, n = 1040), sulphonylurea (SU, n = 535) or metformin (MET, n = 500) PIO + SU (n = 277) or MET + SU (n = 273); or PIO + MET (n = 286) or SU + MET (n = 275). Pooled week 52 glycaemic and lipid changes were compared using analysis of covariance. Haemoglobin A(1c) decreased significantly with pioglitazone compared with sulphonylurea (p < 0.05). Fasting, 2- and 3-h plasma glucose, insulin and homeostasis model assessment for insulin resistance decreased significantly with pioglitazone compared with other monotherapies (p < 0.05) and decreased significantly with PIO + MET compared with SU + MET (p < 0.05). Pioglitazone, alone and with metformin, improved lipid components of diabetic dyslipidaemia more than did their respective comparison groups. Pioglitazone was associated with weight increase. In conclusion, pioglitazone provided effective glycaemic control and lipid profile improvements in patients with type 2 diabetes and metabolic syndrome.