A new perspective in the treatment of dyslipidemia : can fenofibrate offer unique benefits in the treatment of type 2 diabetes mellitus?

Gender dependent differences in lipid metabolism in individuals with type 2 diabetes mellitus

Aim

The present study investigates gender dependent effects of insulin resistance on lipid profile and adipocytokines in individuals with diabetes receiving oral antidiabetic drugs (OADs). The aim was also to reveal the changes in the expression of genes involved in lipid metabolism and inflammation.

Methods

Lipid profile, adipocytokine levels and homeostatic model assessment of insulin resistance (HOMA-IR) was assessed in 100 patients with diabetes (M = 43, F = 57) matched for age and gender with healthy individuals (M = 45, F = 55). The expression pattern of genes was analyzed by quantitative real time PCR.

Results

Males consuming metformin with other drugs exhibited a positive association between HOMA-IR and cholesterol, triglyceride and very low density lipoprotein (VLDL). Females consuming only metformin and metformin with other drugs, showed a positive association of HOMA-IR with cholesterol and a negative association with adiponectin. In males and females with diabetes, a comparable expression of peroxisome proliferator activated receptor γ (PPARγ) while higher expression of sterol regulatory element binding protein 1 (SREBP1) was observed. Expression of fatty acid synthase (FAS), long chain acyl CoA Synthetases (ACSL), malonyl-CoA-acyl carrier protein transacylase (MCAT) and nuclear factor kappa β (NFkβ) was higher in men with diabetes than healthy males. Expression of tumor necrosis factor α (TNF-α) was higher in males and females with diabetes than respective healthy genders.

Conclusion

Insulin resistance adversely affects lipid profile, adipocytokines in males with type 2 diabetes. Expression of genes involved in lipid metabolism and inflammation is found to be undesirably and differentially altered in both the genders.

Therapies for type 2 diabetes: lowering HbA1c and associated cardiovascular risk factors

OBJECTIVES

To summarize data supporting the effects of antidiabetes agents on glucose control and cardiovascular risk factors in patients with type 2 diabetes.

METHODS

Studies reporting on the effects of antidiabetes agents on glycemic control, body weight, lipid levels, and blood pressure parameters are reviewed and summarized for the purpose of selecting optimal therapeutic regimens for patients with type 2 diabetes.

RESULTS

National guidelines recommend the aggressive management of cardiovascular risk factors in patients with type 2 diabetes, including weight loss and achieving lipid and blood pressure treatment goals. All antidiabetes pharmacotherapies lower glucose; however, effects on cardiovascular risk factors vary greatly among agents. While thiazolidinediones, sulfonylureas, and insulin are associated with weight gain, dipeptidyl peptidase-4 inhibitors are considered weight neutral and metformin can be weight neutral or associated with a small weight loss. Glucagon-like peptide-1 receptor agonists and amylinomimetics (e.g. pramlintide) result in weight loss. Additionally, metformin, thiazolidinediones, insulin, and glucagon-like peptide-1 receptor agonists have demonstrated beneficial effects on lipid and blood pressure parameters.

CONCLUSION

Management of the cardiovascular risk factors experienced by patients with type 2 diabetes requires a multidisciplinary approach with implementation of treatment strategies to achieve not only glycemic goals but to improve and/or correct the underlying cardiovascular risk factors.

PPAR transcriptional activator complex polymorphisms and the promise of individualized therapy for heart failure

The PPAR gene pathway consists of interrelated genes that encode transcription factors, enzymes, and downstream targets which coordinately act to regulate cellular processes central to glucose and lipid metabolism. The pathway includes the PPAR genes themselves, other class II nuclear hormone receptor transcription factors within the PPAR family, PPAR co-activators, PPAR co-repressors, and downstream metabolic gene targets. This review focuses on the transcription factors that comprise the PPAR transcriptional activator complex--the PPARs (PPARalpha, PPARbeta, or PPARgamma), PPAR heterodimeric partners, such as RXRalpha, and PPAR co-activators, such as PPARgamma coactivator 1alpha (PGC-1alpha) and the estrogen-related receptors (ERRalpha, ERRbeta, and ERRgamma). These transcription factors have been implicated in the development of myocardial hypertrophy and dilated cardiomyopathy as well as response to myocardial ischemia/infarction and, by association, ischemic cardiomyopathy. Human expression studies and animal data are presented as the background for a discussion of the emerging field of pharmacogenetics as it applies to these genes and the consequent implications for the individualization of therapy for patients with heart failure.

Pharmacogenetics of the PPAR genes and cardiovascular disease

The goal of pharmacogenetics is to define the genetic determinants of individual drug responsiveness, and thereby provide personalized treatment to each individual. The peroxisome proliferator-activated receptors (PPARs) are polypeptide products of a set of related genes functioning to regulate several cellular processes that are central to cardiovascular health and disease. Given their pleiotropic roles in lipid and glucose homeostasis, cardiac energy balance and regulation of adipocyte release of circulating inflammatory factors, it is not surprising that PPARs represent an attractive target for clinical investigation and intervention in disease states, such as diabetes, obesity, atherosclerosis, cardiomyopathy, cardiac hypertrophy and heart failure. Research into the manipulation of PPAR function by pharmacologic agents has already resulted in important advances in the treatment of diabetes mellitus and cardiovascular disease. It follows that PPAR pharmacogenetics promises important advances in the personalized treatment of cardiovascular disease.

Evolution of Peroxisome Proliferator-Activated Receptor Agonists

OBJECTIVE:

To discuss the evolution of peroxisome proliferator-activated receptor (PPAR) agonists from single site to multiple subtype or partial agonists for the treatment of type 2 diabetes, dyslipidemia, obesity, and the metabolic syndrome.

DATA SOURCES:

Information was obtained from MEDLINE (1966-March 2007) using search terms peroxisome proliferator-activated receptor agonist, PPAR dual agonist, PPAR α/γ agonist, PPAR pan agonist, partial PPAR, and the specific compound names. Other sources included pharmaceutical companies, the Internet, and the American Diabetes Association 64th-66th Scientific Sessions abstract books.

STUDY SELECTION AND DATA EXTRACTION:

Animal data, abstracts, clinical trials, and review articles were reviewed and summarized.

DATA SYNTHESIS:

PPAR α, γ, and δ receptors play an important role in lipid metabolism, regulation of adipocyte proliferation and differentiation, and insulin sensitivity. The PPAR dual agonists were developed to combine the triglyceride lowering and high-density lipoprotein cholesterol elevation from the PPAR-α agonists (fibrates) with the insulin sensitivity improvement from the PPAR-γ agonists (thiazolidinediones). Although the dual agonists reduced hemoglobin A1C(A1C) and improved the lipid profile, adverse effects led to discontinued development. Currently, PPAR-γ agonists (GW501516 in Phase I trials), partial PPAR-γ agonists (metaglidasen in Phase II and III trials), and pan agonists (α, γ, δ netoglitazone in Phase II and III trials) with improved cell and tissue selectivity are undergoing investigation to address multiple aspects of the metabolic syndrome with a single medication. By decreasing both A1C and triglycerides, metaglidasen did improve multiple aspects of the metabolic syndrome with fewer adverse effects than compared with placebo. Metaglidasen is now being compared with pioglitazone.

CONCLUSIONS:

Influencing the various PPARs results in improved glucose, lipid, and weight management, with effects dependent on full or partial agonist activity at single or multiple receptors. Although the dual PPAR compounds have been associated with unacceptable toxicities, new PPAR agonist medications continue to be developed and investigated to discover a safe drug with benefits in multiple disease states.