Characterization of an inhibitory effect of pioglitazone on balloon-injured vascular smooth muscle cell growth

Different Effects of Thiazolidinediones on In-Stent Restenosis and Target Lesion Revascularization after PCI: A Meta-Analysis of Randomized Controlled Trials

In-stent restenosis (ISR) remains the leading problem encountered after percutaneous coronary intervention (PCI). Thiazolidinediones (TZDs) has been shown to be associated with reduced ISR and target lesion revascularization (TLR); however, the results are inconsistent, especially between rosiglitazone and pioglitazone. In this study, fourteen RCTs with a total of 1350 patients were finally included through a systematical literature search of Embase, Pubmed, the Cochrane Library, and ClinicalTrials.gov from inception to January 31, 2017. The follow-up duration of the included trials ranged from 6 months to 18 months. The results demonstrated that TZDs treatment is associated with significantly reduced risk of TLR (RR:0.45, 95%CI 0.30 to 0.67 for pioglitazone, RR:0.68, 95%CI 0.46 to 1.00 for rosiglitazone). Pioglitazone is associated with significantly reduced risks of ISR (RR:0.47, 95%CI 0.27 to 0.81), major adverse cardiac events (MACE) (RR:0.44, 95%CI 0.30 to 0.64) and neointimal area (SMD: −0.585, 95%CI −0.910 to −0.261). No significant relationship was observed between rosiglitazone and ISR (RR:0.91, 95%CI 0.39 to 2.12), MACE (RR:0.73, 95%CI 0.53 to 1.00) and neointimal area (SMD: −0.164, 95%CI −1.146 to 0.818). This meta-analysis demonstrated that TZDs treatment is associated with significant reduction in ISR, TLR and MACE for patients after PCI. Pioglitazone treatment seems to have more beneficial effects than rosiglitazone and no significantly increased cardiovascular risk was detected for both agents.

Pioglitazone Attenuates Injury-Induced Neointima Formation in Mouse Femoral Artery Partially through the Activation of AMP-Activated Protein Kinase

BACKGROUND/AIMS

Pioglitazone (PIO), an antidiabetic drug, has been shown to attenuate vascular smooth muscle cell (VSMC) proliferation, which is a major event in atherosclerosis and restenosis after angioplasty. Till date, the likely contributory role of AMP-activated protein kinase (AMPK) toward PIO inhibition of VSMC proliferation has not been examined in vivo. This study is aimed at determining whether pharmacological inhibition of AMPK would prevent the inhibitory effect of PIO on neointima formation in a mouse model of arterial injury.

METHODS

Male CJ57BL/6J mice were subjected to femoral artery injury using guidewire. PIO (20 mg/kg/day) was administered orally 1 day before surgery and for 3 weeks until sacrifice in the absence or presence of compound C (an AMPK inhibitor). Injured femoral arteries were used for morphometric analysis of neointima formation. Aortic tissue lysates were used for immunoblot analysis of phosphorylated AMPK.

RESULTS

PIO treatment resulted in a significant decrease in intima-to-media ratio by ∼50.3% (p < 0.05, compared with vehicle control; n = 6), which was accompanied by enhanced phosphorylation of AMPK by ∼85% in the vessel wall. Compound C treatment led to a marked reduction in PIO-mediated inhibition of neointima formation.

CONCLUSION

PIO attenuates injury-induced neointima formation, in part, through the activation of AMPK.

Differential Effects of Peroxisome Proliferator Activator Receptor-α and γ Ligands on Intimal Hyperplasia After Balloon Catheter-Induced Vascular Injury in Zucker Rats

Background: Patients with type 2 diabetes mellitus have a higher rate of restenosis following angioplasty. Peroxisome proliferator activator receptor-x (PPAR) and y ligands such as fenofibrate and rosiglitazone, respectively, have been shown to have protective effects on the vessel wall. We studied the effect of fenofibrate and rosiglitazone on intimal hyperplasia in the Zucker rat, a model for insulin resistance and type 2 diabetes mellitus, following balloon catheter-induced injury.

Methods and Results: Three groups of 13-week-old female fatty Zucker rats were administered an aqueous suspension of either 3 mg/kg/d rosiglitazone (n = 7) or 150 mg/kg/d fenofibrate (n = 6) by gavage, or served as controls (n = 9). In addition, two groups of 13-week-old female lean Zucker rats were either administered 3 mg/kg/d rosiglitazone (n = 6) or served as controls (n = 6). Carotid balloon injury was induced 1 week after the drugs were started. The drug administration was continued for 3 weeks. A 2-mm balloon catheter was introduced through the femoral artery to the left carotid. The balloon was inflated to 4 atmospheres for 20 seconds and then was deflated to 2 atmospheres and dragged down to the aorta. The rats were killed 3 weeks after the injury. The carotid intima/media ratio was calculated. Intimal hyperplasia after carotid balloon-induced injury in the fatty Zucker rats was significantly reduced in the group treated with rosiglitazone (0.18 ± 0.29) compared with the untreated group (0.97 ± 0.13; P < .01). Plasma glucose, triglyceride, and insulin levels were elevated, indicative of the presence of insulin resistance; rosiglitazone treatment significantly reduced insulin and triglyceride levels without decreasing glucose. Rosiglitazone treatment also reduced, but to a lesser extent, the intimal hyperplasia in the lean Zucker rats (0.57 ± 0.10 vs 1.06 ± 0.12 treated and untreated, respectively; P < .01); however, it had no effect on insulin, triglyceride, or glucose levels in this group. The intimal hyperplasia in the fatty Zucker rats treated with fenofibrate was not reduced compared with controls (0.84 ± 0.26 vs 0.97 ± 0.13, respectively); fenofibrate reduced insulin and triglyceride, but not glucose levels, in these animals.

Conclusions: The PPAR-y ligand rosiglitazone, but not the PPAR-x ligand fenofibrate, decreases intimal hyperplasia following balloon injury in both fatty and lean Zucker rats. This effect of the PPAR-y ligand was independent of glycemia, insulin, and lipid levels, and was more pronounced in insulin-resistant rats.

Pioglitazone, a PPARγ agonist, attenuates PDGF-induced vascular smooth muscle cell proliferation through AMPK-dependent and AMPK-independent inhibition of mTOR/p70S6K and ERK signaling

Pioglitazone (PIO), a PPARγ agonist that improves glycemic control in type 2 diabetes through its insulin-sensitizing action, has been shown to exhibit beneficial effects in the vessel wall. For instance, it inhibits vascular smooth muscle cell (VSMC) proliferation, a major event in atherosclerosis and restenosis after angioplasty. Although PPARγ-dependent and PPARγ-independent mechanisms have been attributed to its vasoprotective effects, the signaling events associated with PIO action in VSMCs are not fully understood. To date, the likely intermediary role of AMP-activated protein kinase (AMPK) toward PIO inhibition of VSMC proliferation has not been examined. Using human aortic VSMCs, the present study demonstrates that PIO activates AMPK in a sustained manner thereby contributing in part to inhibition of key proliferative signaling events. In particular, PIO at 30μM concentration activates AMPK to induce raptor phosphorylation, which diminishes PDGF-induced mTOR activity as evidenced by decreased phosphorylation of p70S6K, 4E-BP1, and S6 and increased accumulation of p27(kip1), a cell cycle inhibitor. In addition, PIO inhibits the basal phosphorylation of ERK in VSMCs. Downregulation of endogenous AMPK by target-specific siRNA reveals an AMPK-independent effect for PIO inhibition of ERK, which contributes in part to diminutions in cyclin D1 expression and Rb phosphorylation and the suppression of VSMC proliferation. Furthermore, AMPK-dependent inhibition of mTOR/p70S6K and AMPK-independent inhibition of ERK signaling occur regardless of PPARγ expression/activation in VSMCs as evidenced by gene silencing and pharmacological inhibition of PPARγ. Strategies that utilize nanoparticle-mediated PIO delivery at the lesion site may limit restenosis after angioplasty without inducing PPARγ-mediated systemic adverse effects.

Retrospective review of superficial femoral artery stenting in diabetic patients: thiazolidinedione use may decrease reinterventions

Background

Diabetics are known to have inferior outcomes following peripheral vascular interventions. Thiazolidinediones are oral diabetic agents which improve outcomes following coronary bare metal stenting. No studies have been performed evaluating thiazolidinedione use and outcomes following lower extremity endovascular interventions. We hypothesize that diabetic patients taking thiazolidinediones at the time of primary superficial femoral artery (SFA) stenting have fewer reinterventions.

Methods

A retrospective review was performed to identify diabetic patients undergoing primary SFA stenting. The unit of analysis was the extremity. The primary outcome was freedom from target lesion revascularization stratified by thiazolidinedione use, evaluated by Kaplan Meier curves and a log rank test. A Cox proportional hazards model was constructed to determine variables associated with freedom from target lesion revascularization.

Results

SFA stents were placed in 138 extremities in 128 diabetic patients between August 1, 2001 and July 15, 2012. Twenty-four patients were taking thiazolidinediones at the time of SFA stenting. All patients taking thiazolidinediones had TASC A or B lesions. Twenty-seven extremities in the non-thiazolidinedione group had TASC C or D lesions and were excluded to control for disease severity. Freedom from target lesion revascularization was significantly higher in diabetics taking thiazolidinediones at 2 years, 88.5% vs. 59.4%, P = 0.02, SE < 10%. Cox modeling identified a protective trend for thiazolidinedione use (thiazolidinedione use HR 0.33, 95% CI 0.09-1.13), whereas critical limb ischemia and insulin use were associated with trends for worse freedom from target lesion revascularization.

Conclusions

This pilot, translation study demonstrates that diabetic patients taking thiazolidinediones at the time of primary SFA stenting have decreased reintervention rates at 2 years. These results may be explained by higher adiponectin levels or other anti-inflammatory effects in patients taking thiazolidinedione. National and regional quality improvement registries should consider collecting information regarding specific diabetic regimens and use of PPAR agonists such as cilostazol and fibrates.

Effects of low dose pioglitazone on restenosis and coronary atherosclerosis in diabetic patients undergoing drug eluting stent implantation

PURPOSE

Thiazolidinediones are insulin-sensitizing agents that reduce neointimal proliferation and the adverse clinical outcomes associated with percutaneous coronary intervention (PCI) in patients with diabetes mellitus (DM). There is little data on whether or not low dose pioglitazone reduces adverse clinical outcomes.

MATERIALS AND METHODS

The study population included 121 DM patients with coronary artery disease and they were randomly assigned to 60 patients taking 15 mg of pioglitazone daily in addition to their diabetic medications and 61 patients with placebo after the index procedure with drug-eluting stents (DESs). The primary end points were rate of in-stent restenosis (ISR) and change in atheroma volume and in-stent neointimal volume. The secondary end points were all-cause death, myocardial infarction (MI), stent thrombosis and re-PCI.

RESULTS

There were no statistical differences in the clinical outcomes and the rate of ISR between the two groups [all-cause death; n=0 (0%) in the pioglitazone group vs. n=1 (1.6%) in the control group, p=0.504, MI; n=2 (3.3%) vs. n=1 (1.6%), p=0.465, re-PCI; n=6 (10.0%) vs. n=6 (9.8%), p=0.652, ISR; n=4 (9.3%) vs. n=4 (7.5%), p=1.000, respectively]. There were no differences in changes in neointimal volume, percent neointimal volume, total plaque volume and percent plaque volume between the two groups on intravascular ultrasonography (IVUS) study.

CONCLUSION

Our study demonstrated that low dose pioglitazone does not reduce rate of ISR, neointimal volume nor atheroma volume in DM patients who have undergone PCI with DESs, despite the limitations of the study.

Three-year clinical outcome in type 2 diabetic patients with drug-eluting stents versus bare-metal stents with pioglitazone

AIMS

The aim of this study was to examine outcome subsequent to implantation of bare-metal stents (BMS) with pioglitazone, which are novel insulin-sensitizing agents, and drug-eluting stents (DES) in patients with diabetes.

METHODS AND RESULTS

A total of 139 consecutive Type 2 diabetic patients treated with stent were followed up for 3 years. Data on death, myocardial infarction (MI), target lesion revascularization (TLR), and stent thrombosis were ascertained from January 2003 to January 2006. Eighty-nine patients were treated with a BMS with pioglitazone, and 50 patients were treated with a DES. The incidence of MI was 1.1% in the BMS with pioglitazone group, 4.0% in the DES group [relative risk RR):0.52; 95% CI: 0.10-2.56]. The incidence of TLR was 22.5% in the BMS with pioglitazone group, 28.0% in the DES group (RR 0.89; 95% CI: 0.65-1.22). The incidence of stent thrombosis was 1.0% in the BMS with pioglitazone group, 4.0% in the DES group (RR 0.52; 95% CI: 0.10-2.56). Overall 3-year mortality was similar in the two groups (RR 0.77; 95% CI: 0.34-1.74).

CONCLUSIONS

During 3 years of follow-up, patients treated with BMS with pioglitazone had similar risks of death, TLR, MI, and stent thrombosis compared with patients treated with DES.

Pioglitazone and mechanisms of CV protection

BACKGROUND AND AIM

Pioglitazone has diverse multiple effects on metabolic and inflammatory processes that have the potential to influence cardiovascular disease pathophysiology at various points in the disease process, including atherogenesis, plaque inflammation, plaque rupture, haemostatic disturbances and microangiopathy.

RESULTS

Linking the many direct and indirect effects on the vasculature to the reduction in key macrovascular outcomes reported with pioglitazone in patients with type 2 diabetes presents a considerable challenge. However, recent large-scale clinical cardiovascular imaging studies are beginning to provide some mechanistic insights, including a potentially important role for improvements in high-density lipoprotein cholesterol with pioglitazone. In addition to a role in prevention, animal studies also suggest that pioglitazone may minimize damage and improve recovery during and after ischaemic cardio- and cerebrovascular events.

DESIGN AND METHODS

In this review, we consider potential cardiovascular protective mechanisms of pioglitazone by linking preclinical data and clinical cardiovascular outcomes guided by insights from recent imaging studies.

CONCLUSION

Pioglitazone may influence CVD pathophysiology at multiple points in the disease process, including atherogenesis, plaque inflammation, plaque rupture and haemostatic disturbances (i.e. thrombus/embolism formation), as well as microangiopathy.

Long-term pioglitazone therapy improves arterial stiffness in patients with type 2 diabetes mellitus

Pioglitazone, a peroxisome proliferator-activated receptor gamma agonist, not only improves insulin resistance and glycemic control, but may also have additional beneficial vascular effects in patients with type 2 diabetes mellitus. We investigated whether pioglitazone had an influence on arterial stiffness, which is an independent predictor of cardiovascular events, in 204 patients with type 2 diabetes mellitus. A prospective, nonrandomized, open-label trial was performed that involved 41 patients treated with pioglitazone, 46 patients receiving sulfonylureas, 67 patients on insulin, and 50 patients on diet/exercise only. The follow-up period was 56 +/- 3 months. Arterial stiffness was evaluated by using the arterial stiffness index (ASI), which was based on analysis of the pulse wave amplitude pattern obtained during automated blood pressure measurement in the upper limb. The 4 groups had a similar baseline ASI, which was greater than the reference range in each group. Although antidiabetic therapies improved hemoglobin A(1c) and low-density lipoprotein cholesterol, ASI only decreased significantly in the pioglitazone group. Thus, pioglitazone improved abnormal arterial stiffness in patients with type 2 diabetes mellitus via a mechanism beyond the metabolic improvement. These findings may have important clinical implications in the use of pioglitazone in patients with type 2 diabetes mellitus.

Effect of long-term treatment with rosiglitazone on arterial elasticity and metabolic parameters in patients with Type 2 diabetes mellitus: a 2-year follow-up study

AIMS

Thiazolidinediones may influence the atherogenic process by improving cardiovascular risk factors. The present study was designed to determine the long-term effect of rosiglitazone on arterial compliance and metabolic parameters in patients with Type 2 diabetes.

METHODS

In an open-label, prospective study, 65 diabetic patients received rosiglitazone orally (4-8 mg/day) for 6 months. After 6 months, the patients continued an open follow-up study and were divided into two groups: group 1 included patients continuing rosiglitazone for 2 years, group 2 included patients discontinuing rosiglitazone and receiving other oral glucose-lowering agents. Lipid profile, glycated haemoglobin (HbA1c), insulin, C-peptide, fibrinogen, high-sensitivity-CRP and homeostasis model assessment-insulin resistance were measured. Arterial elasticity was assessed using pulse wave contour analysis.

RESULTS

In patients treated with rosiglitazone for 2 years: the large artery elasticity index (LAEI) increased from 10.0 +/- 4.6 to 13.9 +/- 4.7 ml/mmHg x 100 after 2 years (P = 0.003). The small artery elasticity (SAEI) index increased significantly from 3.2 +/- 1.2 to 5.1 +/- 1.9 (P < 0.0001). In patients who discontinued rosiglitazone: LAEI did not change after 6 months, but decreased from 12.1 +/- 5.4 to 8.9 +/- 3.9 ml/mmHg x 10 (P < 0.0001) at the end of 2 years. SAEI increased during the first 6 months of treatment, from 3.9 +/- 1.8 to 5.1 +/- 1.5 ml/mmHg x 100 (P < 0.0001) and decreased after discontinuation of rosiglitazone (P = 0.042).

CONCLUSIONS

Prolonged treatment with rosiglitazone improved arterial elasticity. However, significant deterioration in LAEI and SAEI was observed in patients who discontinued rosiglitazone. The beneficial vascular effect of rosiglitazone on arterial elasticity was independent of glycaemic control.

Efficacy and safety of low-dose pioglitazone after primary coronary angioplasty with the use of bare metal stent in patients with acute myocardial infarction and with type 2 diabetes mellitus or impaired glucose tolerance

Thiazolidinediones (TZDs) have beneficial effects on markers of cardiovascular risk in patients with type 2 diabetes mellitus (DM). This study aimed to investigate the efficacy and safety of low-dose pioglitazone (15 mg per day) in patients with acute myocardial infarction (AMI) and type 2 DM or impaired glucose tolerance (IGT) treated with coronary angioplasty using bare metal stent (BMS). In 56 patients, pioglitazone was orally administered for 6 months after stenting (pioglitazone group). The incidence of in-stent restenosis (ISR) and left ventricular end-diastolic volume index (LVEDVI) at acute phase and 6 months after stenting in these patients were retrospectively compared with those in the other 37 patients (control group) treated without pioglitazone. No adverse events including death, emergency bypass surgery, and reinfarction, occurred in any patients in the hospital. There was no congestive heart failure (CHF) during a follow-up period in the pioglitazone group. At 6 months after stenting, the overall angiographic ISR rate was significantly lower in the pioglitazone group than in the control group (28.6% vs 48.6%, P = 0.049). In patients with hemoglobin A1c (HbA1c) <7.0% at follow-up, the ISR rate was also significantly lower in the pioglitazone group than in controls (21.3% vs 44.8%, P = 0.03). Delta-LVEDVI (defined as follow-up LVEDVI minus acute LVEDVI) was similar between the pioglitazone group and control group (0.13 vs 5.16 ml/m(2), P = 0.482). Low-dose pioglitazone seems to have a potential to reduce ISR and does not adversely affect LV remodeling after AMI treated with coronary angioplasty using BMS in patients with type 2 DM or IGT.

Reduction of neointimal hyperplasia after coronary stenting by pioglitazone in nondiabetic patients with metabolic syndrome

BACKGROUND

This study investigates whether pioglitazone reduces neointimal hyperplasia after coronary stenting in nondiabetic patients with metabolic syndrome (MS) using intravascular ultrasound (IVUS). Pioglitazone, a novel insulin-sensitizing thiazolidinedione, has been shown to reduce neointimal hyperplasia after coronary stenting in patients with type 2 diabetes. However, the effect of pioglitazone on in-stent restenosis in nondiabetic patients with MS remains unknown.

METHODS AND RESULTS

Twenty-eight nondiabetic patients with MS after bare-metal stent implantation were randomized to 6-month treatment with or without 30 mg/d of pioglitazone (pioglitazone group [PIO] of 14 patients with 16 lesions and control group [CONT] of 14 patients with 16 lesions). At baseline and at 6-month follow-up, assessment of insulin resistance and visceral fat accumulation, quantitative coronary angiographic analysis, and IVUS measurements were performed. Pioglitazone treatment improved insulin resistance and decreased visceral fat accumulation without significant changes in plasma glucose levels, glycosylated hemoglobin A1c levels, and lipid profiles. Intimal index (intimal area/stent area) and intimal area were reduced in PIO compared with CONT (13% +/- 7% vs 21% +/- 13%, P = .033; 1.28 +/- 0.76 mm2 vs 1.90 +/- 1.16 mm2, P = .084; respectively). Binary restenosis rate was 0% in PIO versus 31% in CONT (P = .043).

CONCLUSIONS

This is the first randomized, prospective IVUS study demonstrating that pioglitazone reduces neointimal hyperplasia after coronary stenting in nondiabetic patients with MS. Our data suggest that pioglitazone treatment may represent a novel therapeutic tool to target in-stent restenosis in nondiabetic patients with MS.

Long-term effects of a PPAR-gamma agonist, pioglitazone, on neointimal hyperplasia and endothelial regrowth in insulin resistant rats

OBJECTIVE

Insulin resistance is an independent risk factor for cardiovascular disease. PPAR-gamma agonists like pioglitazone decrease insulin resistance and have been shown to reduce neointimal hyperplasia in the short-term. However long-term studies on endothelial regrowth and neointimal hyperplasia have not been done.

METHODS AND RESULTS

We used hyperinsulinemic, normoglycemic Zucker fatty rats. Rats were treated with either 10 mg/kg body wt. pioglitazone or placebo till the end of the experiment. Rats underwent carotid angioplasty at age 12-14 weeks, 1 week after treatment was begun. In one set of experiments rats were sacrificed at 6 months and neointimal hyperplasia and VEGF expression was assessed. In another set of experiments rats were sacrificed at 3 and 6 months. Endothelial regrowth was determined. The rats were all normoglycemic and hyperinsulinemic. Pioglitazone treated rats had a significantly lesser degree of neointimal hyperplasia than control rats. Treated rats also had decreased VEGF expression. Endothelial regrowth was decreased in the treated rats at 6 months.

CONCLUSION

We conclude that although pioglitazone decreases neointimal hyperplasia even at 6 months, it retards endothelial regrowth, which could predispose the denuded vessel to thrombotic events. This may be modulated by a suppression of VEGF expression.

Are thiazolidinediones good or bad for the heart?

Type 2 diabetes is a global epidemic contributing to significant cardiovascular morbidity and mortality. The high prevalence of cardiovascular disease can largely be attributed to the metabolic syndrome with its multiple cardiovascular risk factors, including central obesity, hypertension, glucose intolerance, chronic inflammation, and dyslipidemia. The peroxisome proliferator-activated receptor-gamma agonists, the thiazolidinediones, may potentially correct the inflammatory disarray, endothelial dysfunction, dyslipidemia, and plaque vulnerability associated with diabetic cardiovascular disease through their effects on insulin resistance and fat metabolism, yet they can also exacerbate congestive heart failure. This review summarizes basic science, animal, and human data on the effects of thiazolidinediones on cardiovascular disease.

Fibroblasts isolated from human pterygia exhibit altered lipid metabolism characteristics

To determine whether the fibrovascular proliferation observed in pterygium, may be, at least in part, mediated by an increased activity of cholesterol metabolism. The correlation between lipid metabolism and rate of growth was studied in human normal conjunctival (NCF) and primary pterygium fibroblasts (PFs) in primary culture. The expression of two proliferation markers (Ki-67 and p53) was evaluated by immunohistochemical staining techniques. Proliferation was evaluated by [(3)H]thymidine incorporation and by immunohistochemical assays. Lipid metabolism was evaluated by (14)C-oleate incorporated into cholesterol esters as well as by oil red O staining. Moreover, the cultures of pterygium fibroblasts were supplemented with two antiproliferative drugs in order to confirm the effective alterations in cholesterol metabolism related to proliferation. Immunohistochemistry of frozen sections from primary pterygium demonstrated an increased staining in Ki-67 and p53 compared with staining observed in normal conjunctiva. A dramatically increased activity of intracellular cholesterol metabolism was demonstrated in pterygium fibroblasts obtained from four different patients. This finding was confirmed by the reduction of cholesterol metabolism in pterygium fibroblasts treated with antiproliferative drugs. Collectively, these data support the hypothesis that alterations of cholesterol metabolism are involved in the development of pterygia. This finding may represent a target of new therapeutic approaches for treatment and prevention of pterygium.

A randomized comparison of pioglitazone to inhibit restenosis after coronary stenting in patients with type 2 diabetes

OBJECTIVE

Recent studies have demonstrated that the treatment with thiazolidinediones reduces in-stent restenosis. The aim of this study was to elucidate the mechanism of the efficacy of pioglitazone for preventing in-stent restenosis in type 2 diabetic patients.

RESEARCH DESIGN AND METHODS

We conducted a prospective, randomized trial involving 54 type 2 diabetic patients referred for coronary stenting who were randomly assigned to either the control or the pioglitazone group. Quantitative coronary angiography was performed at study entry and at 6 months follow-up. Endothelial nitric oxide synthase (eNOS), tumor necrosis factor alpha, interleukin-6, leptin, and adiponectin were measured at study entry and at 6 months follow-up.

RESULTS

A total of 28 patients were randomly assigned to the control group, and 26 patients were assigned to the pioglitazone group. There were no significant differences in glycemic control levels or in lipid levels in the two groups at baseline or at follow-up. Insulin, homeostasis model assessment of insulin resistance, eNOS, and leptin at follow-up were significantly reduced in the pioglitazone group compared with the control group. The late luminal loss and in-stent restenosis were significantly less in the pioglitazone group than in the control group. Leptin independently correlated with late luminal loss at multiple regression analysis.

CONCLUSIONS

The treatment with pioglitazone in type 2 diabetic patients significantly reduced leptin. This decreased leptin improved insulin resistance and endothelial function with the reduction of insulin. The improved endothelial function affected the reduction of in-stent restenosis.

Pioglitazone Decreases Carotid Intima-Media Thickness Independently of Glycemic Control in Patients With Type 2 Diabetes Mellitus

Background— Patients with type 2 diabetes mellitus are at high risk of cardiovascular disease. Carotid intima-media thickness (IMT) is a strong predictor of myocardial infarction and stroke.

Methods and Results— We compared the effects of pioglitazone-based therapy (45 mg/d) and glimepiride-based treatment (2.7±1.6 mg/d) for 12 and 24 weeks on metabolic control (HbA 1c ), insulin resistance (homeostasis model assessment), and carotid IMT (B-mode ultrasonography) in a randomized controlled study in 173 orally treated patients with type 2 diabetes (66 women, 107 men; mean±SD age, 62.6±7.9 years; body mass index, 31.8±4.6 kg/m 2 ; HbA 1c , 7.5±0.9%). Treatment was generally well tolerated in both groups. Despite similar improvements in metabolic control (HbA 1c ) after 24 weeks (−0.8±0.9% [pioglitazone] versus −0.6±0.8% [glimepiride]; P =NS), carotid IMT was reduced only in the pioglitazone group after 12 weeks (−0.033±0.052 versus −0.002±0.047 mm [glimepiride]; P <0.01 between groups) and 24 weeks (−0.054±0.059 versus −0.011±0.058 mm [glimepiride]; P <0.005 between groups). Insulin resistance was also improved only in the pioglitazone group (homeostasis model assessment, −2.2±3.4 versus −0.3±3.3; P <0.0001 between groups). Reduction of IMT correlated with improvement in insulin resistance ( r =0.29, P <0.0005) and was independent of improvement in glycemic control ( r =0.03, P =0.68).

Conclusions— We found a substantial regression of carotid IMT, independent of improved glycemic control, after 12 and 24 weeks of pioglitazone treatment. This finding may have important prognostic implications for patients with type 2 diabetes mellitus.

A potent activator of PPARα and γ reduces the vascular cell recruitment and inhibits the intimal thickning in hypercholesterolemic rabbits

Peroxisome proliferator-activated receptors (PPARs) regulate the vascular cell functions as well as systemic lipid and glucose metabolism. Here, we studied the effect of TAK-559, a newly developed potent activator both for PPARalpha and gamma, on the vascular cell recruitment. TNF-alpha- or interleukin-1beta (IL-1beta)-induced THP-1 cell attachment to cultured endothelial cells was significantly reduced in the presence of 10 microM TAK-559 (P < 0.05). The secretion of monocyte chemoattractant protein-1 (MCP-1) from endothelial cells is reduced by 36% in the presence of 10 microM TAK-559, accompanied with the decreased mRNA expression in the cells. The proliferation and migration of cultured smooth muscle cells (SMCs) were significantly decreased in the presence of TAK-559 (P < 0.05). TAK-559-treated hypercholesterolemic rabbits showed the significant reduction of intimal thickning after balloon catheterization by 51% compared with control (P < 0.05), although the plasma lipid and glucose level was not changed between them. The numbers of macrophage and SMCs were decreased to 34% and 49% in the hyperplastic intima of arteries from TAK-559-treated rabbits compared to those from control, respectively. These results suggest that the PPARalpha and gamma activator inhibits the recruitment of macrophages and SMCs in intima, possibly leading to the reduction of intimal hyperplasia in hypercholesterolemia.

PPAR gamma ligands, 15-deoxy-delta12,14-prostaglandin J2 and rosiglitazone regulate human cultured airway smooth muscle proliferation through different mechanisms

The influence of two peroxisome proliferator-activated receptor gamma (PPARgamma) ligands, a thiazolidinedione, rosiglitazone (RG) and the prostaglandin D2 metabolite 15-deoxy-Delta(12,14)-prostaglandin J2 (15d-PGJ2) on the proliferation of human cultured airway smooth muscle (HASM) was examined. The increases in HASM cell number in response to basic fibroblast growth factor (bFGF, 300 pm) or thrombin (0.3 U ml-1) were significantly inhibited by either RG (1-10 microM) or 15d-PGJ2 (1-10 microM). The effects of RG, but not 15d-PGJ2, were reversed by the selective PPARgamma antagonist GW9662 (1 microM). Neither RG nor 15d-PGJ2 (10 microM) decreased cell viability, or induced apoptosis, suggesting that the regulation of cell number was due to inhibition of proliferation, rather than increased cell death. Flow-cytometric analysis of HASM cell cycle distribution 24 h after bFGF addition showed that RG prevented the progression of cells from G1 to S phase. In contrast, 15d-PGJ2 caused an increase in the proportion of cells in S phase, and a decrease in G2/M, compared to bFGF alone. Neither RG nor 15d-PGJ2 inhibited ERK phosphorylation measured 6 h post mitogen addition. The bFGF-mediated increase in cyclin D1 protein levels after 8 h was reduced in the presence of 15d-PGJ2, but not RG. Although both RG and 15d-PGJ2 can inhibit proliferation of HASM irrespective of the mitogen used, only the antiproliferative effects of RG appear to be PPARgamma-dependent. The different antimitogenic mechanisms of 15d-PGJ2 and synthetic ligands for PPARgamma may be exploited to optimise the potential for these compounds to inhibit airway remodelling in asthma. British Journal of Pharmacology (2004) 141, 517-525. doi:10.1038/sj.bjp.0705630

Impact of adjunctive thiazolidinedione therapy on blood lipid levels and glycemic control in patients with type 2 diabetes

OBJECTIVE

This study was undertaken to assess the effect of pioglitazone hydrochloride and rosiglitazone maleate on blood lipid levels and glycemic control when these drugs are used as adjunctive therapy in type 2 diabetes.

RESEARCH DESIGN AND METHODS

Patients with type 2 diabetes receiving metformin and/or sulfonylurea (n = 829) were evaluated in this national, multicenter, retrospective study. Medical records from 318 endocrinology practices in the USA were randomly selected and screened for study inclusion. Data related to patient demographics and laboratory data were extracted from medical records and analyzed for primary and secondary outcomes.

MAIN OUTCOME MEASURES

The primary study outcome was the mean change in plasma rosiglitazone was associated with no significant triglyceride (TG) levels. Secondary outcome measures included mean changes in total cholesterol (TChol), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) concentrations and hemoglobin A1C levels.

RESULTS

With pioglitazone, TG levels declined by a mean of 51.5 mg/dl (P < 0.001), HDL-C levels rose by 3.3mg/dl (P < 0.001), and no change was seen in LDL-C or TChol. Treatment with change in TG levels and a 1.5mg/dl mean increase in HDL-C (P < 0.001). Furthermore, rosiglitazone therapy was associated with an 8 mg/dl mean increase in TChol (P < 0.001), and a 5.8 mg/dl mean increase in LDL-C (P < 0.001). Hemoglobin A1C levels were significantly reduced by approximately 1% within thiazolidinedione (TZD) cohorts (P < 0.001), but were not significantly different between study groups (P = 0.257).

CONCLUSIONS

Results from this study suggest that pioglitazone has a more favorable effect on lipid profiles of patients with type 2 diabetes compared with rosiglitazone. In particular, differences were observed in TG and LDL-C levels. Both TZDs were equivalent at reducing hemoglobin A1C levels. These differences in lipid effects may have an impact on cardiovascular outcomes. The full clinical importance of these lipid alterations must be further assessed in prospective trials.

Pioglitazone reduces neointimal tissue proliferation after coronary stent implantation in patients with type 2 diabetes mellitus: an intravascular ultrasound scanning study

BACKGROUND

It has been reported that pioglitazone reduces neointimal hyperplasia after balloon-induced vascular injury in an experimental model.

METHODS

To determine whether pioglitazone reduces neointimal tissue proliferation after coronary stent implantation in patients with type 2 diabetes mellitus, we studied 44 stented lesions in 44 patients with diabetes mellitus who underwent successful coronary stent implantation. Study patients were randomized into 2 groups: the pioglitazone group (23 patients with 23 lesions) and the control group (21 patients with 21 lesions). All patients underwent serial quantitative coronary angiography and serial intravascular ultrasound scanning studies. With a motorized pullback system, multiple image slices within the stent were obtained at every 1 mm. The stent area and lumen area were measured, and the neointimal area was calculated. Measurements were averaged over the number of selected image slices. The neointimal index was calculated as the averaged neointimal area divided by the averaged stent area multiplied by 100 (%).

RESULTS

After 6 months of treatment, angiographic in-stent restenosis (17% vs 43%, respectively, P =.0994) and target lesion revascularization (13% vs 38%, respectively, P =.0835) were less frequent in the pioglitazone group than the control group; however, these differences did not reach significance. The intravascular ultrasound scanning study demonstrated that the neointimal index in the pioglitazone group was significantly smaller than that in the control group (28% +/- 9% vs 48% +/- 15%, respectively, P <.0001).

CONCLUSION

A serial intravascular ultrasound scanning assessment demonstrated that pioglitazone reduces neointimal tissue proliferation after coronary stent implantation in patients with type 2 diabetes mellitus.

Cardioprotection with pioglitazone is abolished by nitric oxide synthase inhibitor in ischemic rabbit hearts--comparison of the effects of pioglitazone and metformin

BACKGROUND

The effects of two drugs representing different classes of antidiabetic pharmacology (pioglitazone, a thiazolidinedione; and metformin, a biguanide) on the myocardial metabolism in the ischemia are poorly understood.

METHODS

To test the hypothesis that cardioprotection of pioglitazone and metformin is associated with nitric oxide (NO), we studied the high energy phosphate metabolism by 31P-nuclear magnetic resonance (NMR) in isolated rabbit hearts. Forty-five minutes of continuous normothermic global ischemia was carried out. Pioglitazone or metformin was administered at the beginning, 60 min prior to the global ischemia, with or without the nitric oxide synthase inhibitor, L-NAME, administered 5 min or 60 min prior to the ischemia. In the first experiment, whether NO was produced or not by administration of pioglitazone, for the prevention of myocardial ischemic injury, was investigated. Hearts of male Japanese white rabbits were divided into 4 experimental groups: the control (C) group, the P group consisting of pioglitazone treatment, the P + L5 group consisting of pioglitazone treatment with L-NAME (5 min before ischemia), and the P + L60 group consisting of pioglitazone treatment with L-NAME (60 min before ischemia). In the next experiment, a comparison between the effects of pioglitazone and metformin in preventing ischemic injury were studied. The hearts were divided into 4 experimental groups: the control (C) group, the P group consisting of pioglitazone treatment, the P + L5 group consisting of pioglitazone treatment with L-NAME (5 min before ischemia), the M group consisting of metformin treatment, and the M + L5 group consisting of metformin treatment with L-NAME (5 min before ischemia).

RESULTS

In the first experiment, the decrease in adenosine triphosphate (ATP) during ischemia was significantly inhibited in the P group in comparison with the C group (P < 0.01). However, the decrease in ATP was not inhibited in the P + L5 group during ischemia. In contrast, in the P + L60 group, the decrease in ATP was not inhibited during a part of ischemia. In the next experiment, a comparison between the effects of pioglitazone and metformin in preventing ischemic injury was studied. As a result of administration of either pioglitazone or metformin, there was no difference between groups with and without L-NAME.

CONCLUSION

These results suggest that pioglitazone has a significant beneficial effect on improving the myocardial energy metabolism during ischemia. This cardioprotection may be dependent on nitric oxide (NO) synthase during ischemia more than preischemia. Furthermore, the present findings suggest that both pioglitazone and metformin have equal cardioprotective effects mediated by NO on myocardial ischemic injury in rabbits.