Pioglitazone: update on an oral antidiabetic drug with antiatherosclerotic effects

A Randomized Phase II Trial of Pioglitazone for Lung Cancer Chemoprevention in High-Risk Current and Former Smokers

Lung cancer chemoprevention, especially in high-risk former smokers, has great potential to reduce lung cancer incidence and mortality. Thiazolidinediones prevent lung cancer in preclinical studies, and diabetics receiving thiazolidinediones have lower lung cancer rates which led to our double-blind, randomized, phase II placebo-controlled trial of oral pioglitazone in high-risk current or former smokers with sputum cytologic atypia or known endobronchial dysplasia. Bronchoscopy was performed at study entry and after completing 6 months of treatment. Biopsies were histologically scored, and primary endpoint analysis tested worst biopsy scores (Max) between groups; Dysplasia index (DI) and average score (Avg) changes were secondary endpoints. Biopsies also received an inflammation score. The trial accrued 92 subjects (47 pioglitazone, 45 placebo), and 76 completed both bronchoscopies (39 pioglitazone, 37 placebo). Baseline dysplasia was significantly worse for current smokers, and 64% of subjects had mild or greater dysplasia at study entry. Subjects receiving pioglitazone did not exhibit improvement in bronchial dysplasia. Former smokers treated with pioglitazone exhibited a slight improvement in Max, while current smokers exhibited slight worsening. While statistically significant changes in Avg and DI were not observed in the treatment group, former smokers exhibited a slight decrease in both Avg and DI. Negligible Avg and DI changes occurred in current smokers. A trend toward decreased Ki-67 labeling index occurred in former smokers with baseline dysplasia receiving pioglitazone. While pioglitazone did not improve endobronchial histology in this high-risk cohort, specific lesions showed histologic improvement, and further study is needed to better characterize responsive dysplasia.

Oxidative stress, mitochondrial and proteostasis malfunction in adrenoleukodystrophy: A paradigm for axonal degeneration

Peroxisomal and mitochondrial malfunction, which are highly intertwined through redox regulation, in combination with defective proteostasis, are hallmarks of the most prevalent multifactorial neurodegenerative diseases-including Alzheimer's (AD) and Parkinson's disease (PD)-and of the aging process, and are also found in inherited conditions. Here we review the interplay between oxidative stress and axonal degeneration, taking as groundwork recent findings on pathomechanisms of the peroxisomal neurometabolic disease adrenoleukodystrophy (X-ALD). We explore the impact of chronic redox imbalance caused by the excess of very long-chain fatty acids (VLCFA) on mitochondrial respiration and biogenesis, and discuss how this impairs protein quality control mechanisms essential for neural cell survival, such as the proteasome and autophagy systems. As consequence, prime molecular targets in the pathogenetic cascade emerge, such as the SIRT1/PGC-1α axis of mitochondrial biogenesis, and the inhibitor of autophagy mTOR. Thus, we propose that mitochondria-targeted antioxidants; mitochondrial biogenesis boosters such as the antidiabetic pioglitazone and the SIRT1 ligand resveratrol; and the autophagy activator temsirolimus, a derivative of the mTOR inhibitor rapamycin, hold promise as disease-modifying therapies for X-ALD.

Methyl (2Z)-2-{(2Z)-3-[(cyclo-pentyl-idene)amino]-4-oxo-2-phenyl-imino-1,3-thia-zol-idin-5-yl-idene}acetate

In the title compound, C17H17N3O3S, the thia-zole ring is nearly planar [maximum deviation = 0.015 (1) Å for the ring N atom] and the cyclo-pentane ring has a twist conformation. The mol-ecular conformation is stabilized by a hypervalent inter-action between the S atom and the ester group carbonyl O atom, with an S⋯O distance of 2.7931 (10) Å. In the crystal, C-H⋯O inter-actions generate chains of mol-ecules propagating along [110] and π-π stacking inter-actions [centroid-centroid distance = 3.4677 (7) Å] between the thia-zole rings organize these chains into (001) layers.

Comparison of the Effects of Pioglitazone versus Placebo when Given in Addition to Standard Insulin Treatment in Patients with Type 2 Diabetes Mellitus Requiring Hemodialysis: Results from the PIOren Study

BACKGROUND

Patients with type 2 diabetes mellitus and advanced kidney disease are usually treated with insulin. However, the prolonged pharmacokinetic insulin profile in patients with delayed renal insulin elimination impairs a successful therapy. Due to its hepatic metabolism, pioglitazone is a potential candidate for additional administration. The aim of this study was to investigate the effect of pioglitazone versus placebo on total daily insulin requirements and several pleiotropic factors in type 2 diabetes patients requiring hemodialysis.

METHODS

The effect of pioglitazone (30 mg) versus placebo was explored in this prospective, randomized, double-blind parallel multicenter phase II study analyzing data from 36 patients with type 2 diabetes mellitus currently under hemodialysis (25 male, 11 female, aged 69.2 ± 7.9 years, baseline HbA1c 7.6 ± 0.9%). The most important efficacy parameters collected before dialysis and after an overnight fast at baseline and after 6 months were: total daily insulin dose, HbA1c, fasting blood glucose, adiponectin, HDL, LDL, triglycerides, NT-proBNP, and ultrafiltrate volume.

RESULTS

Application of pioglitazone resulted in a significant decrease of the daily insulin dose by 35% versus baseline (placebo: -10%, n.s.), improvement in HbA1c (-0.60 ± 0.87%, p = 0.015; placebo: 0.21 ± 1.1%, n.s.) and adiponectin (7.33 ± 4.80 mg/l, p < 0.001; placebo: -1.37 ± 2.56 mg/l, n.s.). Slight improvements or no changes were seen with fasting glucose, triglycerides, HDL, LDL and NT-proBNP. There was no indication of increased hypoglycemia risk and volume overload by the addition of pioglitazone.

CONCLUSIONS

Addition of pioglitazone to insulin in patients with late-stage kidney failure requiring hemodialysis is a well-tolerated treatment option that improves glycemic control with simultaneous insulin-sparing potential.

PPARgamma Agonists: Potential as Therapeutics for Neovascular Retinopathies

The angiogenic, neovascular proliferative retinopathies, proliferative diabetic retinopathy (PDR), and age-dependent macular degeneration (AMD) complicated by choroidal neovascularization (CNV), also termed exudative or “wet” AMD, are common causes of blindness. The antidiabetic thiazolidinediones (TZDs), rosiglitazone, and troglitazone are PPARγ agonists with demonstrable antiproliferative, and anti-inflammatory effects, in vivo, were shown to ameliorate PDR and CNV in rodent models, implying the potential efficacy of TZDs for treating proliferative retinopathies in humans. Activation of the angiotensin II type 1 receptor (AT1-R) propagates proinflammatory and proliferative pathogenic determinants underlying PDR and CNV. The antihypertensive dual AT1-R blocker (ARB), telmisartan, recently was shown to activate PPARγ and improve glucose and lipid metabolism and to clinically improve PDR and CNV in rodent models. Therefore, the TZDs and telmisartan, clinically approved antidiabetic and antihypertensive drugs, respectively, may be efficacious for treating and attenuating PDR and CNV humans. Clinical trials are needed to test these possibilities.

PIOfix-study: effects of pioglitazone/metformin fixed combination in comparison with a combination of metformin with glimepiride on diabetic dyslipidemia

OBJECTIVE

Dyslipidemia in patients with type 2 diabetes is characterized by elevated triglyceride levels, decreased high-density lipoprotein (HDL) cholesterol, and a predominance of small dense low-density lipoprotein (LDL) particles. Also, patients suffer from β-cell dysfunction, chronic systemic inflammation, increased hormonal visceral adipose tissue activity, and an increased risk of cardiovascular events. The aim of our study was to investigate the effect of a fixed pioglitazone + metformin (PM) combination (vs. glimepiride + metformin [GM]) on diabetic dyslipidemia.

RESEARCH DESIGN AND METHODS

A total of 288 type 2 diabetes patients completed this double-blind parallel study (187 men, 101 women; age [mean ± SD], 59 ± 10 years; body mass index, 32.6 ± 5.1 kg/m(2); hemoglobin A1c [HbA1c], 7.3 ± 0.8%). They were randomized to PM or GM for 6 months. Observation parameters at baseline and end point included HDL, LDL, triglycerides, fasting insulin, fasting glucose, total adiponectin, intact proinsulin, and high-sensitivity C-reactive peptide (hsCRP).

RESULTS

HDL increased in the PM group by 0.08 ± 0.25 mmol/L (GM, -0.01 ± 0.2.8 mmol/L; P < 0.001 vs. PM), whereas LDL increased in both groups (GM, 0.25 ± 0.90 mmol/L; PM, 0.29 ± 0.66 mmol/L; difference not significant between groups). Improvements were seen for triglycerides (PM, -0.47 ± 1.30; GM, -0.19 ± 1.39 mmol/L), HbA1c (PM, -0.8 ± 0.9%; GM, -1.0 ± 0.9%), and glucose (PM, -1.2 ± 2.1; GM, -1.2 ± 2.2 mmol/L). Decreases in fasting insulin (PM, -5.2 ± 11.9; GM, -0.1 ± 9.8 μU/mL; P < 0.001 between groups), hsCRP (PM, -0.9 ± 1.9; GM, 0.0 ± 1.8 mg/L; P < 0.001), and fasting intact proinsulin (PM, -5.5 ± 11.1; GM, -0.1 ± 10.0 pmol/L; P < 0.001) and an increase in adiponectin (PM, +6.8 ± 6.4 mg/L; GM, +0.7 ± 2.7 mg/L; P < 0.001) were seen in the PM arm, only.

CONCLUSIONS

With comparable glycemic control, the fixed PM combination was more efficacious on HDL cholesterol improvement than the GM combination. Additional positive effects were observed for biomarkers of lipid metabolism, β-cell function, activity of the visceral adipose tissue, and chronic systemic inflammation.

Improving cardiovascular risk--applying evidence-based medicine to glucose-lowering therapy with thiazolidinediones in patients with type 2 diabetes

BACKGROUND

The management of patients with type 2 diabetes aims to reduce the elevated risk of cardiovascular disease (CVD) by addressing established risk factors including hyperglycaemia, dyslipidaemia and hypertension. The thiazolidinediones are equally effective in improving glycaemic control when used in combination regimens in patients with type 2 diabetes, but have differing effects on the diabetic dyslipidaemia.

AIMS

To compare the effects of rosiglitazone and pioglitazone on inflammatory mediators associated with atherosclerosis and CVD, surrogate cardiovascular endpoints, and hard cardiovascular outcomes in patients with type 2 diabetes.

MATERIALS AND METHODS

A search of the PubMed database plus manual search of referenced papers for other relevant citations.

RESULTS

Both glitazones reduce inflammatory markers and other circulating markers of CV disease. Available data suggest that pioglitazone can delay progression of atherosclerosis in patients with type 2 diabetes, as shown by the PERISCOPE and CHICAGO studies, and that it can reduce the rate of clinical CV events as shown by PROactive. Clinical end-point data for rosiglitazone are inconclusive, providing no evidence of benefit and a possible increase in myocardial infarction.

DISCUSSION

There is a consistency of benefit with pioglitazone on markers, surrogate cardiovascular outcomes and clinical end-point trials.

CONCLUSION

Pioglitazone is the preferred thiazolidinedione to reduce cardiovascular risk in people with type 2 diabetes.

Chronic administration of voglibose, an alpha-glucosidase inhibitor, increases active glucagon-like peptide-1 levels by increasing its secretion and decreasing dipeptidyl peptidase-4 activity in ob/ob mice

Administration of an alpha-glucosidase inhibitor, voglibose, increases the secretion of glucagon-like peptide (GLP)-1, a key modulator of pancreatic islet hormone secretion and glucose homeostasis. In the present study, novel mechanisms by which voglibose increases active GLP-1 circulation were evaluated. Voglibose (0.001 and 0.005%) was administered in the diet to ob/ob mice for 1 day or 3 to 4 weeks to determine effects on incretin profiles and plasma activity of dipeptidyl peptidase-4 (DPP-4), an enzyme responsible for GLP-1 degradation. Voglibose showed no direct inhibitory effect against DPP-4 in vitro (DPP-4 inhibitor alogliptin, IC(50) < 10 nM). Likewise, 1-day treatment with voglibose did not change plasma DPP-4 activity; however, it increased plasma active GLP-1 by 1.6- to 3.4-fold. After chronic treatment, voglibose stimulated GLP-1 secretion, as evidenced by the 1.3- to 1.5-fold increase in plasma active plus inactive amidated GLP-1 levels. Plasma DPP-4 activity was decreased unexpectedly by 40 to 51%, resulting from reduced plasma DPP-4 concentrations in voglibose-treated mice. Voglibose increased GLP-1 content by 1.5- to 1.6-fold and 1.4- to 1.6-fold in the lower intestine and colon, respectively. The increased GLP-1 content in the colon was associated with elevated expression of gut glucagon gene. Chronic treatment with voglibose resulted in 1.9- to 4.1-fold increase in active GLP-1 circulation, which was higher than 1-day treatment. A similar treatment with pioglitazone (0.03%), an insulin sensitizer, did not affect plasma DPP-4 activity or GLP-1 levels. These results suggest that increased GLP-1 secretion, decreased DPP-4 activity, and increased gut GLP-1 content may have contributed to increased active GLP-1 circulation after chronic treatment with voglibose in a glucose control-independent manner in ob/ob mice.

Sibutramine effect on metabolic control of obese patients with type 2 diabetes mellitus treated with pioglitazone

Thiazolidinediones are supposed to be the pharmacologic agents that more physiologically fight the insulin resistance, but a possible adverse effect may be a weight increase. The aim of the study was to test the efficacy and tolerability of sibutramine on the metabolic effect of pioglitazone in obese patients with type 2 diabetes mellitus. All enrolled patients were required to have been diagnosed as being diabetic for at least 6 months and did not have glycemic control with diet and oral hypoglycemic agents such as sulfonylureas or metformin, both to the maximum tolerated dose. After a run-in period in which the eligible patients took a fixed dose of pioglitazone (30 mg/d), the patients were randomized to receive also sibutramine (10 mg/d) or placebo for 6 months. We assessed body mass index, hemoglobin A(1c) (HbA(1c)), fasting plasma glucose (FPG), postprandial plasma glucose (PPG), fasting plasma insulin (FPI), postprandial plasma insulin (PPI), lipid profile, lipoprotein parameters, and lipoprotein (a) at baseline and after 3 and 6 months. No body mass index change was observed after 3 and 6 months in the pioglitazone + placebo (pp) group. Significant decrease was present in the pioglitazone + sibutramine (ps) group after 3 (P < .05) and 6 months (P < .01) compared with the baseline values, and this variation was significant (P < .05) between groups. A significant HbA(1c) decrease was observed after 3 (P < .05) and 6 months (P < .01) in both groups with respect to the baseline values. There was no difference in HbA(1c) value between the 2 groups. No FPG, PPG, FPI, PPI, and homeostasis model assessment index change was observed at 3 months, whereas a significant decrease was present after 6 months (P < .05), in both groups with respect to the baseline values. There was no difference in FPG, PPG, FPI, PPI, and homeostasis model assessment index value between the pp and ps groups. No significant low-density lipoprotein cholesterol change was observed at 3 months, whereas a significant decrease was present after 6 months (P < .05), in both groups with respect to the baseline values. There was no difference in low-density lipoprotein cholesterol value between the pp and ps groups. No triglyceride variation was present at 3 and 6 months in the pp group and at 3 months in the ps group, whereas a significant decrease was observed at 6 months (P < .05) in the ps group with respect to the baseline values. There was no difference in triglyceride value between both groups. No high-density lipoprotein cholesterol, apolipoprotein A-I, apolipoprotein B, and lipoprotein (a) changes were present in both groups with respect to the baseline values. Sibutramine appears to be a tolerable and efficacious drug when added to pioglitazone for the global management of obese diabetic patients.

PPAR gamma agonist normalizes glomerular filtration rate, tissue levels of homocysteine, and attenuates endothelial-myocyte uncoupling in alloxan induced diabetic mice

Background: Homocysteine (Hcy) is an independent cardiovascular risk factor; however, in diabetes, the role of tissue Hcy leading to cardiac dysfunction is unclear.

Aims: To determine whether tissue Hcy caused endothelial-myocyte uncoupling and ventricular dysfunction in diabetes.

Methods: Diabetes was created in C57BL/6J male mice by injecting 65 mg/kg alloxan. To reverse diabetic complications, ciglitazone (CZ) was administered in the drinking water. Plasma glucose, Hcy, left ventricular (LV) tissue levels of Hcy and nitric oxide (NO) were measured. Glomerular filtration rate (GFR) was measured by inulin-FITC. Endothelial-myocyte coupling was measured in cardiac rings. In vivo diastolic relaxation and LV diameters were measured by a Millar catheter in LV and by M-mode echocardiography, respectively.

Results: Plasma glucose, GFR and LV tissue Hcy were increased in diabetic mice and were normalized after CZ treatment; whereas, elevated plasma Hcy level remained unchanged with or without CZ treatment. NO levels in the LV were found inversely related to tissue Hcy levels. Attenuated endothelial-myocyte function in diabetic mice was ameliorated by CZ treatment. Cardiac relaxation, the ratio of LV wall thickness to LV diameter was decreased in diabetes, and normalized after CZ treatment.

Conclusion: CZ normalized LV tissue levels of Hcy and ameliorated endothelial-myocyte coupling; therefore, specifically suggest the association of LV tissue Hcy levels with impair endothelial-myocyte function in diabetes.

Intensification of oxidative stress and inflammation in type 2 diabetes despite antihyperglycemic treatment

INTRODUCTION

The metabolic deregulation associated with diabetes mellitus (DM) causes secondary pathophysiologic changes in multiple organ systems. Endothelial injury is induced by oxidative stress (OS) and inflammation. We have previously shown that DM type 2 patients are exposed to increased OS and inflammation contributed in part by primed peripheral polymorphonuclear leukocytes (PMNLs).

AIMS

To characterize the effect of oral medication on PMNL priming, on PMNL-related and on systemic inflammation, in correlation to changed diabetes parameters in patient with newly diagnosed type 2 DM.

METHODS

PMNLs were separated from DM patient's prior and following treatment with either metformin (Glucophage), or Thiazolidinedione (rosiglitazone) and from healthy control subjects (HC). Rate of superoxide release from phorbol ester-stimulated PMNLs and CD11b on PMNLs assessed PMNL priming. White blood cells (WBC) and PMNL counts and apoptosis reflected PMNL-related inflammation. CRP, fibrinogen, transferrin and albumin blood levels reflected systemic inflammation.

RESULTS

Both metformin and rosiglitazone treatments reduced significantly the high levels of glucose and HbA1c, and slightly improved lipid profile during 2 months. PMNL priming parameters, higher compared to HC, increased after 2 months of metformin treatment. Rosiglitazone treatment decreased PMNL priming. ALP, higher in DM, significantly decreased following 2 months of both treatments. Systemic inflammation markers (fibrinogen, CRP), higher in DM, decreased following both treatments. Transferrin and albumin were similar to HC. PMNL-related inflammation markers were higher in DM; however, only PMNL apoptosis decreased after both treatments. Monocyte counts, higher in DM compared to HC, decreased following both treatments. Serum insulin levels, higher in DM compared to HC, decreased following both treatments. PMNL-related priming and inflammation parameters positively correlated with HbA1c.

CONCLUSION

The present research adds new facet in evaluating anti-hyperglycemic treatment in type 2 DM patients. Despite sufficient glycemic control using both treatments, some PMNL-related parameters deteriorated. Thus, anti hyperglycemic treatment should be favored due to its combined anti-PMNL priming and anti-inflammatory effect, in addition to its anti-hyperglycemic characteristics, according to the correlation among these parameters. Such combined treatment may reduce morbidity and mortality common in DM patients.

The role of peroxisome proliferator-activated receptor-gamma (PPARgamma) in Alzheimer's disease: therapeutic implications

Alzheimer's disease is a complex neurodegenerative disorder, with aging, genetic and environmental factors contributing to its development and progression. The complexity of Alzheimer's disease presents substantial challenges for the development of new therapeutic agents. Alzheimer's disease is typified by pathological depositions of beta-amyloid peptides and neurofibrillary tangles within the diseased brain. It has also been demonstrated to be associated with a significant microglia-mediated inflammatory component, dysregulated lipid homeostasis and regional deficits in glucose metabolism within the brain. The peroxisome proliferator-activated receptor-gamma (PPARgamma) is a prototypical ligand-activated nuclear receptor that coordinates lipid, glucose and energy metabolism, and is found in elevated levels in the brains of individuals with Alzheimer's disease. A recently appreciated physiological function of this type of receptor is its ability to modulate inflammatory responses. In animal models of Alzheimer's disease, PPARgamma agonist treatment results in the reduction of amyloid plaque burden, reduced inflammation and reversal of disease-related behavioural impairment. In a recent phase II clinical trial, the use of the PPARgamma agonist rosiglitazone was associated with improved cognition and memory in patients with mild to moderate Alzheimer's disease. Thus, PPARgamma may act to modulate multiple pathophysiological mechanisms that contribute to Alzheimer's disease, and represents an attractive therapeutic target for the treatment of the disease.