PPAR dual agonists: are they opening Pandora's Box?
ABSTRACT Cardiovascular disorders are the major cause of mortality in patients of diabetes mellitus. Peroxisome proliferator activated receptors (PPARs) are ligand-activated transcription factors of nuclear hormone receptor superfamily comprising of three subtypes such as PPARalpha, PPARgamma and PPARdelta/beta. Activation of PPARalpha reduces triglycerides and involves in regulation of energy homeostasis. Activation of PPARgamma causes insulin sensitization and enhances glucose metabolism, whereas activation of PPARdelta enhances fatty acid metabolism. Current therapeutic strategies available for the treatment of diabetes do not inhibit the associated secondary cardiovascular complications. Hence, the development of multimodal drugs which can reduce hyperglycemia and concomitantly inhibit the progression of secondary cardiovascular complications may offer valuable therapeutic option. Several basic and clinical studies have exemplified the beneficial effects of PPARalpha and PPARgamma ligands in preventing the cardiovascular risks. The PPARalpha/gamma dual agonists are developed to increase insulin sensitivity and simultaneously prevent diabetic cardiovascular complications. Such compounds are under clinical trials and proposed for treatment of Type II diabetes with secondary cardiovascular complications. However, PPARalpha/gamma dual agonists such as muraglitazar, tesaglitazar and ragaglitazar have been noted to produce several cardiovascular risks and carcinogenicity, which raised number of questions about the clinical applications of dual agonists in diabetes and its associated complications. The ongoing basic studies have elucidated the cardio protective role of PPARdelta. Therefore, further studies are on the track to develop PPARalpha/delta and PPAR gamma/delta dual agonists and PPARalpha/gamma/delta pan agonists for the treatment of diabetic cardiovascular complications. The present review critically analyzes the protective and detrimental effect of PPAR agonists in diabetic cardiovascular complications. Moreover, the newly developed PPARalpha/delta and PPAR gamma/delta dual agonists and PPARalpha/gamma/delta pan agonists have also been discussed which may open a new vista in the management of diabetic cardiovascular complications in near future.
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ABSTRACT: The formation of an atherosclerotic lesion is mediated by lipid-laden macrophages (foam cells), which also establish chronic inflammation associated with lesion progression. The peroxisome proliferator-activated receptor (PPAR) gamma promotes lipid uptake and efflux in these atherogenic cells. In contrast, we found that the closely related receptor PPARdelta controls the inflammatory status of the macrophage. Deletion of PPARdelta from foam cells increased the availability of inflammatory suppressors, which in turn reduced atherosclerotic lesion area by more than 50%. We propose an unconventional ligand-dependent transcriptional pathway in which PPARdelta controls an inflammatory switch through its association and disassociation with transcriptional repressors. PPARdelta and its ligands may thus serve as therapeutic targets to attenuate inflammation and slow the progression of atherosclerosis.Science 11/2003; 302(5644):453-7. · 31.20 Impact Factor
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ABSTRACT: More than 70% of patients with Type 2 diabetes mellitus (T2DM) die because of cardiovascular diseases. Current therapeutic strategies are based on separate treatment of insulin resistance and dyslipidaemia. Development of drugs with multimodal activities should improve management of the global cardiovascular risk of T2DM patients and result in better patient compliance. New therapeutic strategies are aimed at targeting the entire spectrum of dysfunctioning organs, cells and regulatory pathways implicated in the pathogenesis of T2DM, dyslipidaemia and atherosclerosis. PPAR family members play major roles in the regulation of lipid metabolism, glucose homeostasis and inflammatory processes, making these transcription factors ideal targets for therapeutic strategies against these diseases. This review discusses why PPARs and development of novel selective PPAR modulators, dual and pan PPAR agonists constitute promising approaches for the treatment of diabetes, dyslipidaemia and atherosclerosis.Expert Opinion on Emerging Drugs 10/2006; 11(3):379-401. · 2.48 Impact Factor
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ABSTRACT: Patients with type 2 diabetes are at high risk of fatal and non-fatal myocardial infarction and stroke. There is indirect evidence that agonists of peroxisome proliferator-activated receptor gamma (PPAR gamma) could reduce macrovascular complications. Our aim, therefore, was to ascertain whether pioglitazone reduces macrovascular morbidity and mortality in high-risk patients with type 2 diabetes. We did a prospective, randomised controlled trial in 5238 patients with type 2 diabetes who had evidence of macrovascular disease. We recruited patients from primary-care practices and hospitals. We assigned patients to oral pioglitazone titrated from 15 mg to 45 mg (n=2605) or matching placebo (n=2633), to be taken in addition to their glucose-lowering drugs and other medications. Our primary endpoint was the composite of all-cause mortality, non fatal myocardial infarction (including silent myocardial infarction), stroke, acute coronary syndrome, endovascular or surgical intervention in the coronary or leg arteries, and amputation above the ankle. Analysis was by intention to treat. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN NCT00174993. Two patients were lost to follow-up, but were included in analyses. The average time of observation was 34.5 months. 514 of 2605 patients in the pioglitazone group and 572 of 2633 patients in the placebo group had at least one event in the primary composite endpoint (HR 0.90, 95% CI 0.80-1.02, p=0.095). The main secondary endpoint was the composite of all-cause mortality, non-fatal myocardial infarction, and stroke. 301 patients in the pioglitazone group and 358 in the placebo group reached this endpoint (0.84, 0.72-0.98, p=0.027). Overall safety and tolerability was good with no change in the safety profile of pioglitazone identified. 6% (149 of 2065) and 4% (108 of 2633) of those in the pioglitazone and placebo groups, respectively, were admitted to hospital with heart failure; mortality rates from heart failure did not differ between groups. Pioglitazone reduces the composite of all-cause mortality, non-fatal myocardial infarction, and stroke in patients with type 2 diabetes who have a high risk of macrovascular events.The Lancet 11/2005; 366(9493):1279-89. · 39.06 Impact Factor