TL;DR: Clinical evidences obtained from bezafibrate-based studies strongly support the concept of pan-PPAR therapeutic approach to conditions which comprise the metabolic syndrome, as well as more powerful new compounds with pan- PPAR activity and proven long-term safety.
Abstract: There are three peroxisome proliferator-activated receptors (PPARs) subtypes which are commonly designated PPAR alpha, PPAR gamma and PPAR beta/delta. PPAR alpha activation increases high density lipoprotein (HDL) cholesterol synthesis, stimulates "reverse" cholesterol transport and reduces triglycerides. PPAR gamma activation results in insulin sensitization and antidiabetic action. Until recently, the biological role of PPAR beta/delta remained unclear. However, treatment of obese animals by specific PPAR delta agonists results in normalization of metabolic parameters and reduction of adiposity. Combined treatments with PPAR gamma and alpha agonists may potentially improve insulin resistance and alleviate atherogenic dyslipidemia, whereas PPAR delta properties may prevent the development of overweight which typically accompanies "pure" PPAR gamma ligands. The new generation of dual-action PPARs – the glitazars, which target PPAR-gamma and PPAR-alpha (like muraglitazar and tesaglitazar) are on deck in late-stage clinical trials and may be effective in reducing cardiovascular risk, but their long-term clinical effects are still unknown. A number of glitazars have presented problems at a late stage of clinical trials because of serious side-effects (including ragaglitazar and farglitazar). The old and well known lipid-lowering fibric acid derivative bezafibrate is the first clinically tested pan – (alpha, beta/delta, gamma) PPAR activator. It is the only pan-PPAR activator with more than a quarter of a century of therapeutic experience with a good safety profile. Therefore, bezafibrate could be considered (indeed, as a "post hoc" understanding) as an "archetype" of a clinically tested pan-PPAR ligand. Bezafibrate leads to considerable raising of HDL cholesterol and reduces triglycerides, improves insulin sensitivity and reduces blood glucose level, significantly lowering the incidence of cardiovascular events and new diabetes in patients with features of metabolic syndrome. Clinical evidences obtained from bezafibrate-based studies strongly support the concept of pan-PPAR therapeutic approach to conditions which comprise the metabolic syndrome. However, from a biochemical point of view, bezafibrate is a PPAR ligand with a relatively low potency. More powerful new compounds with pan-PPAR activity and proven long-term safety should be highly effective in a clinical setting of patients with coexisting relevant lipid and glucose metabolism disorders.
TL;DR: Tesaglitazar was well tolerated and produced significant, dose-dependent improvements in lipid and glucose metabolism and insulin sensitivity and may have the potential to prevent vascular complications and delay progression to diabetes in patients with evidence of insulin resistance.
Abstract: Insulin resistance is associated with abnormalities in lipid and glucose metabolism, which are major components of metabolic syndrome and risk factors for vascular disease. This study examined the effect of tesaglitazar (Galida), a novel, dual-acting peroxisome proliferator-activated receptor α/γ agonist, on lipid and glucose metabolism in patients with evidence of insulin resistance. A 12-week, multicentre, randomised, double-blind, placebo-controlled, dose-finding study compared the efficacy and safety of oral tesaglitazar (0.1, 0.25, 0.5 and 1.0 mg/day) and placebo in 390 non-diabetic patients with hypertriglyceridaemia (plasma triglyceride concentration >1.7 mmol/l) and abdominal obesity (waist-to-hip ratio >0.90 for men and >0.85 for women). A 1.0-mg dose of tesaglitazar reduced fasting triglycerides (the primary endpoint) by 37% (95% CI: −43% to −30%; p<0.0001), non-HDL-cholesterol by 15% (95% CI: −20% to −10%; p<0.0001) and NEFA by 40% (95% CI: −51% to −27%; p<0.0001), and increased HDL-cholesterol by 16% (95% CI: 8 to −24%; p<0.0001). At the end of treatment there was a dose-dependent increase in patients with pattern A LDL particle diameter (40% at baseline vs 87% at 12 weeks for tesaglitazar 1.0 mg). Tesaglitazar produced significant reductions in fasting insulin concentration (−35%; p<0.0001) and plasma glucose concentration (−0.47 mmol/l; p<0.0001). Respiratory infection and gastrointestinal symptoms were the most common adverse events and were similarly frequent in all groups. Tesaglitazar was well tolerated and produced significant, dose-dependent improvements in lipid and glucose metabolism and insulin sensitivity. Tesaglitazar may have the potential to prevent vascular complications and delay progression to diabetes in these patients.
TL;DR: Results indicate that the dual PPARα/γ agonism of AZ 242 reduces insulin resistance and has beneficial effects on FA and glucose metabolism, which could provide a suitable therapeutic approach to the treatment of type 2 diabetes, metabolic syndrome, and associated vascular risk factors.
TL;DR: Increase in adiponectin levels resulted in amelioration of albuminuria, glomerular hypertrophy, and reduction of inflammatory response in kidney tissue, and Renin-angiotensin-aldosterone system blockers, adip onectin receptor agonists, and PPAR agonists may be potential therapeutic drugs for the treatment of DKD.
Abstract: Diabetic kidney disease (DKD) is a major complication for diabetic patients. Adiponectin is an insulin sensitizer and anti-inflammatory adipokine and is mainly secreted by adipocytes. Two types of adiponectin receptors, AdipoR1 and AdipoR2, have been identified. In both type 1 and type 2 diabetes (T2D) patients with DKD, elevated adiponectin serum levels have been observed, and adiponectin serum level is a prognostic factor of end-stage renal disease. Renal insufficiency and tubular injury possibly play a contributory role in increases in serum and urinary adiponectin levels in diabetic nephropathy by either increasing biodegradation or elimination of adiponectin in the kidneys, or enhancing production of adiponectin in adipose tissue. Increases in adiponectin levels resulted in amelioration of albuminuria, glomerular hypertrophy, and reduction of inflammatory response in kidney tissue. The renoprotection of adiponectin is associated with improvement of the endothelial dysfunction, reduction of oxidative stress, and upregulation of endothelial nitric oxide synthase expression through activation of adenosine 5'-monophosphate-activated protein kinase by AdipoR1 and activation of peroxisome proliferator-activated receptor (PPAR)-α signaling pathway by AdipoR2. Several single nucleotide polymorphisms in the AdipoQ gene, including the promoter, are associated with increased risk of the development of T2D and DKD. Renin-angiotensin-aldosterone system blockers, adiponectin receptor agonists, and PPAR agonists (e.g., tesaglitazar, thiazolidinediones, fenofibrate), which increase plasma adiponectin levels and adiponectin receptors expression, may be potential therapeutic drugs for the treatment of DKD.
TL;DR: Reduced EtOH intake in mice and the genetic association between AD or withdrawal in humans highlight the potential for repurposing FDA-approved PPARα or PPARγ agonists for the treatment of AD.
Abstract: Background
Peroxisome proliferator-activated receptor (PPAR) agonists reduce voluntary ethanol (EtOH) consumption in rat models and are promising therapeutics in the treatment for drug addictions. We studied the effects of different classes of PPAR agonists on chronic EtOH intake and preference in mice with a genetic predisposition for high alcohol consumption and then examined human genomewide association data for polymorphisms in PPAR genes in alcohol-dependent subjects.
Methods
Two different behavioral tests were used to measure intake of 15% EtOH in C57BL/6J male mice: 24-hour 2-bottle choice and limited access (3-hour) 2-bottle choice, drinking in the dark. We measured the effects of pioglitazone (10 and 30 mg/kg), fenofibrate (50 and 150 mg/kg), GW0742 (10 mg/kg), tesaglitazar (1.5 mg/kg), and bezafibrate (25 and 75 mg/kg) on EtOH intake and preference. Fenofibric acid, the active metabolite of fenofibrate, was quantified in mouse plasma, liver, and brain by liquid chromatography tandem mass spectrometry. Data from a human genome-wide association study (GWAS) completed in the Collaborative Study on the Genetics of Alcoholism (COGA) were then used to analyze the association of single nucleotide polymorphisms (SNPs) in different PPAR genes (PPARA, PPARD, PPARG, and PPARGC1A) with 2 phenotypes: DSM-IV alcohol dependence (AD) and the DSM-IV criterion of withdrawal.
Results
Activation of 2 isoforms of PPARs, α and γ, reduced EtOH intake and preference in the 2 different consumption tests in mice. However, a selective PPARδ agonist or a pan agonist for all 3 PPAR isoforms did not decrease EtOH consumption. Fenofibric acid, the active metabolite of the PPARα agonist fenofibrate, was detected in liver, plasma, and brain after 1 or 8 days of oral treatment. The GWAS from COGA supported an association of SNPs in PPARA and PPARG with alcohol withdrawal and PPARGC1A with AD but found no association for PPARD with either phenotype.
Conclusions
We provide convergent evidence using both mouse and human data for specific PPARs in alcohol action. Reduced EtOH intake in mice and the genetic association between AD or withdrawal in humans highlight the potential for repurposing FDA-approved PPARα or PPARγ agonists for the treatment of AD.