Rapid Effects of Rosiglitazone Treatment on Endothelial Function and Inflammatory Biomarkers

Vascular Aging: Assessment and Intervention

Vascular aging represents a collection of structural and functional changes in a blood vessel with advancing age, including increased stiffness, vascular wall remodeling, loss of angiogenic ability, and endothelium-dependent vasodilation dysfunction. These age-related alterations may occur earlier in those who are at risk for or have cardiovascular diseases, therefore, are defined as early or premature vascular aging. Vascular aging contributes independently to cardio-cerebral vascular diseases (CCVDs). Thus, early diagnosis and interventions targeting vascular aging are of paramount importance in the delay or prevention of CCVDs. Here, we review the direct assessment of vascular aging by examining parameters that reflect changes in structure, function, or their compliance with age including arterial wall thickness and lumen diameter, endothelium-dependent vasodilation, arterial stiffness as well as indirect assessment through pathological studies of biomarkers including endothelial progenitor cell, lymphocytic telomeres, advanced glycation end-products, and C-reactive protein. Further, we evaluate how different types of interventions including lifestyle mediation, such as caloric restriction and salt intake, and treatments for hypertension, diabetes, and hyperlipidemia affect age-related vascular changes. As a single parameter or intervention targets only a certain vascular physiological change, it is recommended to use multiple parameters to evaluate and design intervention approaches accordingly to prevent systemic vascular aging in clinical practices or population-based studies.

In Silico-Based Design and In Vivo Evaluation of an Anthranilic Acid Derivative as a Multitarget Drug in a Diet-Induced Metabolic Syndrome Model

Metabolic syndrome (MetS) is a complex disease that affects almost a quarter of the world's adult population. In MetS, diabetes, obesity, hyperglycemia, high cholesterol, and high blood pressure are the most common disorders. Polypharmacy is the most used strategy for managing conditions related to MetS, but it has drawbacks such as low medication adherence. Multitarget ligands have been proposed as an interesting approach to developing drugs to treat complex diseases. However, suitable preclinical models that allow their evaluation in a context closer to a clinical situation of a complex disease are needed. From molecular docking studies, compound 1b, a 5-aminoanthranilic acid derivative substituted with 4'-trifluoromethylbenzylamino and 3',4'-dimethoxybenzamide moieties, was identified as a potential multitarget drug, as it showed high in silico affinity against targets related to MetS, including PPAR-α, PPAR-γ, and HMG-CoA reductase. It was evaluated in a diet-induced MetS rat model and simultaneously lowered blood pressure, glucose, total cholesterol, and triglyceride levels after a 14-day treatment. No toxicity events were observed during an acute lethal dose evaluation test at 1500 mg/kg. Hence, the diet-induced MetS model is suitable for evaluating treatments for MetS, and compound 1b is an attractive starting point for developing multitarget drugs.

Platelet Effects of Anti-diabetic Therapies: New Perspectives in the Management of Patients with Diabetes and Cardiovascular Disease

In type 2 diabetes, anti-thrombotic management is challenging, and current anti-platelet agents have demonstrated reduced efficacy. Old and new anti-diabetic drugs exhibited—besides lowering blood glucose levels—direct and indirect effects on platelet function and on thrombotic milieu, eventually conditioning cardiovascular outcomes. The present review summarizes existing evidence on the effects of glucose-lowering agents on platelet properties, addressing pre-clinical and clinical research, as well as drug–drug interactions with anti-platelet agents. We aimed at expanding clinicians’ understanding by highlighting new opportunities for an optimal management of patients with diabetes and cardiovascular disease. We suggest how an improvement of the thrombotic risk in this large population of patients may be achieved by a careful and tailored combination of anti-diabetic and anti-platelet therapies.

GQ-11: A new PPAR agonist improves obesity-induced metabolic alterations in LDLr-/- mice

BACKGROUND

Obesity and insulin resistance/diabetes are important risk factors for cardiovascular diseases and demand safe and efficacious therapeutics.

OBJECTIVE

To assess the effects of a new thiazolidine compound-GQ-11-on obesity and insulin resistance induced by a diabetogenic diet in LDL receptor-deficient (LDLr^-/-) mice.

METHODS

Molecular docking simulations of GQ-11, PPARα and PPARγ structures were performed. Male C57BL/6J LDLr^-/- mice fed a diabetogenic diet for 24 weeks were treated with vehicle, GQ-11 or pioglitazone or (20 mg/kg/day) for 28 days by oral gavage. Glucose tolerance test, insulin, HOMA-IR, adipokines (leptin, adiponectin) and the lipid profile were assessed after treatment. Adipose tissue was analysed by X-ray analysis and morphometry; gene and protein expression were evaluated by real-time PCR and western blot, respectively.

RESULTS

GQ-11 showed partial agonism to PPARγ and PPARα. In vivo, treatment with GQ-11 ameliorated insulin sensitivity and did not modify subcutaneous adipose tissue and body weight gain. In addition, GQ-11 restored adipokine imbalance induced by a diabetogenic diet and enhanced Glut-4 expression in the adipose tissue. Improved insulin sensitivity was also associated with lower levels of MCP-1 and higher levels of IL-10. Furthermore, GQ-11 reduced triglycerides and VLDL cholesterol and increased HDL-cholesterol by upregulation of Apoa1 and Abca1 gene expression in the liver.

CONCLUSION

GQ-11 is a partial/dual PPARα/γ agonist that demonstrates anti-diabetic effects. Additionally, it improves the lipid profile and ameliorates chronic inflammation associated with obesity in atherosclerosis-prone mice.

Analysis of Drug Effects on Primary Human Coronary Artery Endothelial Cells Activated by Serum Amyloid A

Background

RA patients have a higher incidence of cardiovascular diseases compared to the general population. Serum amyloid A (SAA) is an acute-phase protein, upregulated in sera of RA patients.

Aim

To determine the effects of medications on SAA-stimulated human coronary artery endothelial cells (HCAEC).

Methods

HCAEC were preincubated for 2 h with medications from sterile ampules (dexamethasone, methotrexate, certolizumab pegol, and etanercept), dissolved in medium (captopril) or DMSO (etoricoxib, rosiglitazone, meloxicam, fluvastatin, and diclofenac). Human recombinant apo-SAA was used to stimulate HCAEC at a final 1000 nM concentration for 24 hours. IL-6, IL-8, sVCAM-1, and PAI-1 were measured by ELISA. The number of viable cells was determined colorimetrically.

Results

SAA-stimulated levels of released IL-6, IL-8, and sVCAM-1 from HCAEC were significantly attenuated by methotrexate, fluvastatin, and etoricoxib. Both certolizumab pegol and etanercept significantly decreased PAI-1 by an average of 43%. Rosiglitazone significantly inhibited sVCAM-1 by 58%.

Conclusion

We observed marked influence of fluvastatin on lowering cytokine production in SAA-activated HCAEC. Methotrexate showed strong beneficial effects for lowering released Il-6, IL-8, and sVCAM-1. Interesting duality was observed for NSAIDs, with meloxicam exhibiting opposite-trend effects from diclofenac and etoricoxib. This represents unique insight into specific responsiveness of inflammatory-driven HCAEC relevant to atherosclerosis.

Rosiglitazone Improves Insulin Resistance Mediated by 10,12 Conjugated Linoleic Acid in a Male Mouse Model of Metabolic Syndrome

Trans-10, cis-12 conjugated linoleic acid (10,12 CLA) is a dietary fatty acid that promotes weight loss and disproportionate fat loss. Obese mice fed a high-fat, high-sucrose (HFHS) diet containing 10,12 CLA are resistant to weight gain and contain markedly reduced subcutaneous fat and adiponectin, with a concurrent lack of improvement in insulin sensitivity despite significant weight loss. Taken together, 10,12 CLA promotes a phenotype resembling peroxisome proliferator-activated receptor (PPAR)γ antagonism. Because thiazolidinediones such as rosiglitazone (Rosi) are used clinically to improve insulin sensitivity by activating PPARγ, with particular efficacy in subcutaneous white adipose tissue, we hypothesized that Rosi would improve glucose metabolism in mice losing weight with 10,12 CLA. Obese low-density lipoprotein receptor-deficient mice were fed a HFHS control diet, or supplemented with 1% 10,12 CLA with or without Rosi (10 mg/kg) for 8 weeks. Body composition, glucose and insulin tolerance tests, tissue gene expression, and plasma lipid analyses were performed. Mice consuming 10,12 CLA with Rosi lost weight and body fat compared with control groups, but with a healthier redistribution of body fat toward more subcutaneous adipose tissue than with 10,12 CLA alone. Further, Rosi improved 10,12 CLA-mediated insulin resistance parameters and increased plasma and subcutaneous adipose tissue adiponectin levels without adverse effects on plasma or hepatic lipids. We conclude that cotreatment of mice with 10,12 CLA and Rosi promotes fat loss with a healthier fat distribution that leads to improved insulin sensitivity, suggesting that the combination treatment strategy of 10,12 CLA with Rosi could have therapeutic potential for obesity treatment.

Thiazolidinedione drugs in the treatment of type 2 diabetes mellitus: past, present and future

Thiazolidinedione (TZD) drugs used in the treatment of type 2 diabetes mellitus (T2DM) have proven effective in improving insulin sensitivity, hyperglycemia, and lipid metabolism. Though well tolerated by some patients, their mechanism of action as ligands of peroxisome proliferator-activated receptors (PPARs) results in the activation of several pathways in addition to those responsible for glycemic control and lipid homeostasis. These pathways, which include those related to inflammation, bone formation, and cell proliferation, may lead to adverse health outcomes. As treatment with TZDs has been associated with adverse hepatic, cardiovascular, osteological, and carcinogenic events in some studies, the role of TZDs in the treatment of T2DM continues to be debated. At the same time, new therapeutic roles for TZDs are being investigated, with new forms and isoforms currently in the pre-clinical phase for use in the prevention and treatment of some cancers, inflammatory diseases, and other conditions. The aims of this review are to provide an overview of the mechanism(s) of action of TZDs, a review of their safety for use in the treatment of T2DM, and a perspective on their current and future therapeutic roles.

Mechanisms of Cardiovascular Injury in Type 2 Diabetes and Potential Effects of Dipeptidyl Peptidase-4 Inhibition

BACKGROUND

Cardiovascular (CV) disease is the major cause of mortality and morbidity in patients with type 2 diabetes mellitus (T2DM). The pathogenesis of CV disease in T2DM is complex and multifactorial and involves direct and indirect injury to the vasculature and heart. The impact of intensive glucose-lowering therapy with antihyperglycemic agents on CV outcomes is not clear, and questions remain as to which glucose-lowering agents may be beneficial to CV health in patients with T2DM.

PURPOSE

This review discusses findings regarding the known mechanisms of CV injury in T2DM and current knowledge regarding the potential cardioprotective effects of dipeptidyl peptidase-4 (DPP-4) inhibitors.

CONCLUSIONS

Dipeptidyl peptidase-4 inhibitors are relatively new antihyperglycemic agents. Their main mechanism of action is to inhibit the degradation of the incretin hormones glucagon-like peptide-1 and glucose-dependent insulinotropic peptide by DPP-4. By increasing levels of glucagon-like peptide-1, glucose-dependent insulin secretion is enhanced, glucagon secretion is suppressed, and the rate of gastric emptying is decreased. Dipeptidyl peptidase-4 also degrades other substances that are important in the regulation of CV function and inflammation. Animal studies, small observational studies in humans, and analyses of clinical trial data suggest that DPP-4 inhibitors may have beneficial CV effects. Recent prospectively designed CV outcomes trials with saxagliptin and alogliptin in patients with T2DM and high CV risk presented evidence that these DPP-4 inhibitors neither increased nor decreased adverse CV outcomes in this select patient population.

CLINICAL IMPLICATIONS

Dipeptidyl peptidase-4 inhibitors are promising therapies for the treatment of T2DM. Able to improve glycemic control without the risk of weight gain or hypoglycemia, they provide a safe alternative to sulfonylureas and are an effective adjunct to metformin. To date, this class of drugs seems to be at least neutral in terms of CV effects. Time will tell if these findings translate into a benefit for our patients.

Differential Role of Adipose Tissues in Obesity and Related Metabolic and Vascular Complications

This review focuses on the contribution of white, brown, and perivascular adipose tissues to the pathophysiology of obesity and its associated metabolic and vascular complications. Weight gain in obesity generates excess of fat, usually visceral fat, and activates the inflammatory response in the adipocytes and then in other tissues such as liver. Therefore, low systemic inflammation responsible for insulin resistance contributes to atherosclerotic process. Furthermore, an inverse relationship between body mass index and brown adipose tissue activity has been described. For these reasons, in recent years, in order to combat obesity and its related complications, as a complement to conventional treatments, a new insight is focusing on the role of the thermogenic function of brown and perivascular adipose tissues as a promising therapy in humans. These lines of knowledge are focused on the design of new drugs, or other approaches, in order to increase the mass and/or activity of brown adipose tissue or the browning process of beige cells from white adipose tissue. These new treatments may contribute not only to reduce obesity but also to prevent highly prevalent complications such as type 2 diabetes and other vascular alterations, such as hypertension or atherosclerosis.

The role of S-methylisothiourea hemisulfate as inducible nitric oxide synthase inhibitor against kidney iron deposition in iron overload rats

Background:

Iron dextran is in common use to maintain iron stores. However, it is potentially toxic and may lead to iron deposition (ID) and impair functions of organs. Iron overload can regulate the expression of inducible nitric oxide synthase (iNOS) in some cells that has an important role in tissue destruction. S-methylisothiourea hemisulfate (SMT) is a direct inhibitor of iNOS, and this study was designed to investigate the effect of SMT against kidney ID in iron overload rats.

Materials and Methods:

24 Wistar rats (male and female) were randomly assigned to two groups. Iron overloading was performed by iron dextran 100 mg/kg/day every other day for 2 weeks. In addition, during the study, groups 1 and 2 received vehicle and SMT (10 mg/kg, ip), respectively. Finally, blood samples were obtained, and the kidneys were prepared for histopathological procedures.

Results:

SMT significantly reduced the serum levels of creatinine and blood urea nitrogen. However, SMT did not alter the serum levels of iron and nitrite, and the kidney tissue level of nitrite. Co-administration of SMT with iron dextran did not attenuate the ID in the kidney.

Conclusion:

SMT, as a specific iNOS inhibitor, could not protect the kidney from ID while it attenuated the serum levels of kidney function biomarkers.

Dual Peroxisome Proliferator-Activated Receptor-alpha/gamma Agonists : In the Treatment of Type 2 Diabetes Mellitus and the Metabolic Syndrome

The metabolic syndrome consists of a combination of cardiovascular risk factors that include hyperglycemia with or without type 2 diabetes mellitus, visceral obesity, elevated blood pressure, and atherogenic dyslipidemia. These interrelated disorders and their associated lipotoxicity, oxidative stress, and inflammatory state predispose to a constellation of cardiovascular conditions leading to high risk of heart attack, stroke, renal failure, blindness, and lower extremity amputation. Visceral obesity, a prime risk factor for type 2 diabetes and a major component of the metabolic syndrome, potentiates atherogenesis, atherosclerosis, organ lipotoxicity, and oxidative tissue damage.Peroxisome proliferator-activated receptors (PPARs) are relatively recently discovered nuclear transcription factors that are modulated by dietary fatty acids, including the essential polyunsaturated fatty acids, arachidonic acid and its metabolites, and are essential to the control of energy metabolism. Of the three PPAR isoforms (alpha, gamma, and delta), synthetic pharmaceutical ligands that activate PPARalpha (the antidyslipidemic fibric acid derivatives ['fibrates']) and PPARgamma (the antidiabetic thiazolidinediones) have been studied extensively. Recently developed dual PPARalpha/gamma agonists may combine the therapeutic effects of these drugs, creating the expectation of greater efficacy, and perhaps other advantages in the treatment of type 2 diabetes and the metabolic syndrome. However, thiazolidinediones are hampered by adverse effects related to increased weight gain and fluid overload. It remains to be seen whether the dual PPARalpha/gamma agonists currently under development have similar limitations. Nevertheless, existing clinical data imply that the combined effects of thiazolidinediones and fibrates are likely to be emulated by dual PPARalpha/gamma agonists, providing superior efficacy to these classes for the treatment of type 2 diabetes, the metabolic syndrome, and their cardiovascular and other end-organ complications.

New PPARγ partial agonist improves obesity-induced metabolic alterations and atherosclerosis in LDLr(-/-) mice

Peroxisome proliferator-activated receptor gamma (PPARγ) regulates multiple pathways involved in the pathogenesis of obesity and atherosclerosis. Here, we evaluated the therapeutic potential of GQ-177, a new thiazolidinedione, on diet-induced obesity and atherosclerosis. The intermolecular interaction between PPARγ and GQ-177 was examined by virtual docking and PPAR activation was determined by reporter gene assay identifying GQ-177 as a partial and selective PPARγ agonist. For the evaluation of biological activity of GQ-177, low-density lipoprotein receptor-deficient (LDLr(-/-)) C57/BL6 mice were fed either a high fat diabetogenic diet (diet-induced obesity), or a high fat atherogenic diet, and treated with vehicle, GQ-177 (20mg/kg/day), pioglitazone (20mg/kg/day, diet-induced obesity model) or rosiglitazone (15mg/kg/day, atherosclerosis model) for 28 days. In diet-induced obesity mice, GQ-177 improved insulin sensitivity and lipid profile, increased plasma adiponectin and GLUT4 mRNA in adipose tissue, without affecting body weight, food consumption, fat accumulation and bone density. Moreover, GQ-177 enhanced hepatic mRNA levels of proteins involved in lipid metabolism. In the atherosclerosis mice, GQ-177 inhibited atherosclerotic lesion progression, increased plasma HDL and mRNA levels of PPARγ and ATP-binding cassette A1 in atherosclerotic lesions. GQ-177 acts as a partial PPARγ agonist that improves obesity-associated insulin resistance and dyslipidemia with atheroprotective effects in LDLr(-/-) mice.

Rosiglitazone attenuates indoxyl sulphate-induced endothelial dysfunction

Indoxyl sulphate is a protein-bound uraemic toxin that has deleterious effects on the cardiovascular system. Rosiglitazone (RGZ) is an insulin sensitizer used for glycaemic control in type 2 diabetes. Rosiglitazone has been shown to be beneficial for cardiovascular disease because of its pleiotropic effects. Whether RGZ can improve indoxyl sulphate-induced endothelial damage has not been investigated. In the present in vitro study, we examined the effects of RGZ on indoxyl sulphate-induced endothelial injury. Endothelial cells were exposed to RGZ (5 and 10 μmol/L) and then treated with indoxyl sulphate (100 and 1000 μmol/L) for 48 h. Indoxyl sulphate upregulated intracellular cell adhesion molecule-1, vascular cell adhesion molecule-1 and monocyte chemotactic protein-1 expression. Indoxyl sulphate also increased the abundance of NADPH oxidase 4 (NOX4) and nuclear factor (NF)-κB. Both extracellular signal-regulated kinase (ERK) 1/2 and p38 mitogen-activated protein kinase (MAPK) signalling pathways were activated after 48 h treatment with indoxyl sulphate. Pretreatment of cells with both concentrations of RGZ improved indices of endothelial injury. In addition, RGZ attenuated the increase in NOX4 and NF-κB and prevented the activation of the ERK1/2 and p38 MAPK signalling pathways. We conclude that RGZ ameliorates indoxyl sulphate-induced endothelial injury.

Effects of oral hypoglycemic agents on platelet function

Platelet dysfunction plays a role in diabetic macrovascular complications. Several studies have assessed the effect of oral hypoglycemic agents (OHAs) on platelet function. Data from both in vivo and in vitro studies show a favorable effect for most of the traditional glucose-lowering therapies, while evidence is limited for the newer ones. Metformin, sulfonylureas, glitazones and acarbose exert a favorable effect on platelet function. Among incretin therapies, only sitagliptin has so far been demonstrated to have a beneficial effect on platelet aggregation. More in vivo and in vitro evidence is required to increase our knowledge on any potential beneficial effects of OHAs on platelet function. Any such effect may have implications for the reduction of cardiovascular risk in type 2 diabetes mellitus.

Breaking the mold: transcription factors in the anucleate platelet and platelet-derived microparticles

Platelets are small anucleate blood cells derived from megakaryocytes. In addition to their pivotal roles in hemostasis, platelets are the smallest, yet most abundant, immune cells and regulate inflammation, immunity, and disease progression. Although platelets lack DNA, and thus no functional transcriptional activities, they are nonetheless rich sources of RNAs, possess an intact spliceosome, and are thus capable of synthesizing proteins. Previously, it was thought that platelet RNAs and translational machinery were remnants from the megakaryocyte. We now know that the initial description of platelets as "cellular fragments" is an antiquated notion, as mounting evidence suggests otherwise. Therefore, it is reasonable to hypothesize that platelet transcription factors are not vestigial remnants from megakaryocytes, but have important, if only partly understood functions. Proteins play multiple cellular roles to minimize energy expenditure for maximum cellular function; thus, the same can be expected for transcription factors. In fact, numerous transcription factors have non-genomic roles, both in platelets and in nucleated cells. Our lab and others have discovered the presence and non-genomic roles of transcription factors in platelets, such as the nuclear factor kappa β (NFκB) family of proteins and peroxisome proliferator-activated receptor gamma (PPARγ). In addition to numerous roles in regulating platelet activation, functional transcription factors can be transferred to vascular and immune cells through platelet microparticles. This method of transcellular delivery of key immune molecules may be a vital mechanism by which platelet transcription factors regulate inflammation and immunity. At the very least, platelets are an ideal model cell to dissect out the non-genomic roles of transcription factors in nucleated cells. There is abundant evidence to suggest that transcription factors in platelets play key roles in regulating inflammatory and hemostatic functions.

Peroxisome proliferator-activated receptor γ agonist effect on rheumatoid arthritis: a randomized controlled trial

Introduction

Rheumatoid arthritis (RA), a chronic inflammatory disease, is associated with insulin resistance. Experimental evidence indicates that the relationship between insulin resistance and inflammation is bidirectional: Inflammation promotes insulin resistance, and insulin resistance promotes inflammation. Therefore, we examined the hypothesis that pioglitazone, a thiazolidinedione peroxisome proliferator-activated receptor γ agonist, would decrease inflammation and disease activity and improve insulin resistance in patients with RA.

Methods

In a single-center, randomized, double-blind, placebo-controlled crossover study patients with RA (N = 34) receiving stable therapy were randomized to also receive either pioglitazone 45 mg daily (n = 17) or matching placebo (n = 17) for eight weeks. This was followed by a four-week washout period and alternative treatment for eight weeks. Outcomes included change in Disease Activity Score in 28 joints (DAS28) score, individual components of the DAS28 score and homeostatic model assessment for insulin resistance (HOMA). Intention-to-treat analysis and linear mixed-effects models were used.

Results

Patients had a mean (±SD) age of 51 (±14.2) years, 82.4% were female and baseline DAS28 high-sensitivity C-reactive protein (DAS28-CRP) was 4.58 (±1.1) units. Addition of pioglitazone was associated with a 9.3% reduction (95% confidence interval (CI) = 0.17% to 17.6%) in DAS28-CRP (P = 0.046), but no significant change in DAS28 erythrocyte sedimentation rate (DAS28-ESR) (P = 0.92). There was a 10.7mm (95% CI = 0.4 to 20.9 mm) improvement in patient-reported global health (P = 0.042), a 48.6% decrease (95% CI = 27.6% to 63.5%) in CRP (P < 0.001) and a 26.4% decrease (95% CI = 3.7% to 43.8%) in insulin resistance as measured by HOMA (P = 0.025), but no significant reduction in swollen or tender joint count or in ESR (all P > 0.05). Lower-extremity edema was more common during pioglitazone treatment (16%) than placebo (0%).

Conclusion

Addition of pioglitazone to RA therapy improves insulin resistance and modestly reduces RA disease activity measured by DAS28-CRP and two of its components, including patient-reported global health and CRP, but not DAS28-ESR or ESR.

Trial registration

NCT00763139

Pioglitazone: an antidiabetic drug with cardiovascular therapeutic effects

The antidiabetic compound pioglitazone, an activator of the intracellular peroxisome proliferator-activated receptor-gamma, and decreases metabolic and vascular insulin resistance. The drug is well tolerated, and its metabolic effects include improvements in blood glucose and lipid control. Vascular effects consist of improvements in endothelial function and hypertension, and a reduction in surrogate markers of artherosclerosis. In a large, placebo-controlled, outcome study in secondary prevention, PROactive study, the use of pioglitazone in addition to an existing optimized macrovascular risk management resulted in a significant reduction of macrovascular endpoints within a short observation period that was comparable to the effect of statins and angiotensin converting enzyme inhibitors in other trials. These results underline the value of pioglitazone for managing the increased cardiovascular risk of patients with a metabolic syndrome or Type 2 diabetes mellitus.

PPAR-γ agonist pioglitazone prevents apoptosis of endothelial progenitor cells from rat bone marrow

Selective peroxisome proliferator-activated receptor-γ (PPAR-γ) agonist affects the functions of endothelial progenitor cells (EPCs). This study explores the effect of selective PPAR-γ agonist, pioglitazone, on EPC apoptosis. The cells were cultured and identified via the double staining method in a medium containing different concentrations of pioglitazone. EPC apoptosis was detected by flow cytometry. On Day 7, EPCs engulfed DiL-ac-LDL and FITC-UEA-1, and showed yellow fluorescence in a laser-scanning confocal microscope. EPC apoptosis inhibition was maximal at 50 µmol/L. The ability of pioglitazone to prevent EPC apoptosis may be mediated by the PI3K/Akt signal pathway. The use of thiazolidine two ketone (TZD) to reduce EPC apoptosis may have some potential in treating vascular diseases.

Endothelial dysfunction and cardiac allograft vasculopathy

Cardiac allograft vasculopathy remains a major challenge to long-term survival after heart transplantation. Endothelial injury and dysfunction, as a result of multifactorial immunologic and nonimmunologic insults in the donor and the recipient, are prevalent early after transplant and may be precursors to overt cardiac allograft vasculopathy. Current strategies for managing cardiac allograft vasculopathy, however, rely on the identification and treatment of established disease. Improved understanding of mechanisms leading to endothelial dysfunction in heart transplant recipients may provide the foundation for the development of sensitive screening techniques and preventive therapies.

Determinants of evolving metabolic and cardiovascular benefit/risk profiles of rosiglitazone therapy during the natural history of diabetes: molecular mechanisms in the context of integrated pathophysiology

Rosiglitazone is a thiazolidinedione, a synthetic PPARγ receptor agonist with insulin-sensitizing properties that is used as an antidiabetic drug. In addition to improving glycemic control through actions in metabolic target tissues, rosiglitazone has numerous biological actions that impact on cardiovascular homeostasis. Some of these actions are helpful (e.g., improving endothelial function), whereas others are potentially harmful (e.g., promoting fluid retention). Since cardiovascular morbidity and mortality are major endpoints for diabetes, it is essential to understand how the natural history of diabetes alters the net benefits and risks of rosiglitazone therapy. This complex issue is an important determinant of optimal use of rosiglitazone and is critical for understanding cardiovascular safety issues. We give special attention to the effects of rosiglitazone in diabetic patients with stable coronary artery disease and the impact of rosiglitazone actions on atherosclerosis and plaque instability. This provides a rational conceptual framework for predicting evolving benefit/risk profiles that inform optimal use of rosiglitazone in the clinical setting and help explain the results of recent large clinical intervention trials where rosiglitazone had disappointing cardiovascular outcomes. Thus, in this perspective, we describe what is known about the molecular mechanisms of action of rosiglitazone on cardiovascular targets in the context of the evolving pathophysiology of diabetes over its natural history.

Pioglitazone improves the cardiovascular profile in patients with uncomplicated systemic lupus erythematosus: a double-blind randomized clinical trial

OBJECTIVE

We studied the effect of pioglitazone on insulin levels, inflammation markers, high-density lipoprotein (HDL) composition and subclasses distribution, in young women with uncomplicated systemic lupus erythematosus (SLE).

METHODS

This double-blind trial included 30 premenopausal women (30 ±8 years old) with SLE, who were randomized to pioglitazone (30 mg/day) or placebo treatment for 3 months. Plasma and HDL lipids were determined by colorimetric enzymatic assays, insulin by radioimmunometric assay, inflammation by immunonephelometry and HDL size and subclasses distribution by a native 4-30% polyacrylamide gradient gel electrophoresis.

RESULTS

Compared with placebo, pioglitazone significantly increased HDL-cholesterol plasma levels (14.2%), reduced fasting insulin plasma levels (23.6%) and the homeostasis model assessment-insulin resistance (31.7%). C-reactive protein (70.9%) and serum amyloid A (34.9%) were also significantly reduced with the pioglitazone use, whereas the HDL particle size was increased (8.80 nm vs. 8.95 nm; p = 0.044) by changes in the distribution of HDL(2b), HDL(3b), and HDL(3c) subclasses. The change in HDL size correlated with a rise in free and cholesterol-ester content in the HDL particles.

CONCLUSION

Pioglitazone significantly enhanced insulin sensitivity, reduced inflammation, and modified HDL characteristics, suggesting a potential beneficial effect of this drug in patients with SLE with a risk to develop cardiovascular disease.

TRIAL REGISTRATION

This trial is registered at ClinicalTrials.gov Protocol Registration System, with the number NCT01322308.

Downregulation of the proinflammatory state of circulating mononuclear cells by short-term treatment with pioglitazone in patients with type 2 diabetes mellitus and coronary artery disease

Background. This study was performed to investigate the influence of a short-term treatment with pioglitazone versus placebo on inflammatory activation of mononuclear cells (mRNA expression/protein secretion of inflammatory markers). Methods and Results. Sixty-three patients with well-controlled type 2 diabetes (52 males, 11 females, age (Mean ± SD): 66 ± 7 yrs, disease duration: 6.6 ± 9.6 yrs, HbA1c: 6.7 ± 0.6%) were randomized to additional 45 mg of pioglitazone or placebo to their existing metformin and sulfonylurea therpay for four weeks in a double-blind study design. Protein risk marker levels (hsCRP, MMP-9, MCP-1, etc.) and the expression of NFκB subunits and NFκB-modulated cytokines from isolated peripheral monocyte/macrophages were determined at baseline and endpoint. There were no changes in HbA1c, but significant biomarker improvements were seen with pioglitazone only. The mRNA marker expression was downregulated by pioglitazone and further up-regulated with placebo (e.g., P105 pioglitazone: −19%/placebo: +6%, RelA: −20%/+2%, MMP−9: −36%/+9%, TNFα: −10%/+14%, P < 0.05 between groups in all cases). Conclusions. Pioglitazone very rapidly down-regulated the activated state of peripheral monocytes/macrophages as assessed by mRNA expression of NFκB and NFκB-modulated cytokines and decreased plasma levels of cardiovascular risk marker proteins independent of glycemic control.

The role of peroxisome proliferator-activated receptors in pulmonary vascular disease

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors belonging to the nuclear hormone receptor superfamily that regulate diverse physiological processes ranging from lipogenesis to inflammation. Recent evidence has established potential roles of PPARs in both systemic and pulmonary vascular disease and function. Existing treatment strategies for pulmonary hypertension, the most common manifestation of pulmonary vascular disease, are limited by an incomplete understanding of the underlying disease pathogenesis and lack of efficacy indicating an urgent need for new approaches to treat this disorder. Derangements in pulmonary endothelial-derived mediators and endothelial dysfunction have been shown to play a pivotal role in pulmonary hypertension pathogenesis. Therefore, the following review will focus on selected mediators implicated in pulmonary vascular dysfunction and evidence that PPARs, in particular PPARγ, participate in their regulation and may provide a potential novel therapeutic target for the treatment of pulmonary hypertension.

Treatment of diabetic vasculopathy with rosiglitazone and ramipril: Hype or hope?

Cardiovascular diseases are responsible for increased morbidity and mortality in people with diabetes. Diabetic macrovasculopathy is associated with structural and functional changes in large arteries, which causes endothelial dysfunction, increased arterial stiffness, or decreased arterial distensability. Diabetic complications can be controlled and avoided by strict glycemic control, maintaining normal lipid profiles, regular physical exercise, adopting a healthy lifestyle and pharmacological interventions. Treatment goals for patients with type 2 diabetes specify targets for glycemia and other cardiometabolic risk factors, for example, hypertension and dyslipidemia. In recent years, special attention has been devoted to both thiazolidindiones (TZDs) and angiotensin converting enzyme (ACE) inhibitors as clinical trials revealed that these drugs may reduce the rate of progression to diabetes or delay the onset of diabetes, regression of impaired glucose tolerance (IGT) to normoglycemia and reduces the composite of all-cause mortality, nonfatal myocardial infarction and stroke in patients with diabetes. This review focuses on the potential roles of rosiglitazone, a member of TZD class of antidiabetic agents, and ramipril, an ACE inhibitor, in preventing the preclinical macrovasculopathy in diabetes and IGT population.

The fixed combination of pioglitazone and metformin improves biomarkers of platelet function and chronic inflammation in type 2 diabetes patients: results from the PIOfix study

BACKGROUND

Type 2 diabetes mellitus (T2DM) is characterized by a proinflammatory and procoagulant condition. This study investigates the impact of a pioglitazone plus metformin therapy on biomarkers of inflammation and platelet activation in comparison to a treatment with glimepiride plus metformin.

METHODS

The study was designed as a multicenter, randomized, double-blinded two-arm trial. Patients with T2DM and dyslipidemia under metformin monotherapy with hemoglobin A1c value between 6.5% and 9.0% were eligible for trial participation. Blood was drawn at baseline and after 24 weeks of treatment from patients of five centers. Markers of inflammation and thrombocyte function (soluble CD40 ligand, thromboxane, vWillebrand factor, adhesion molecules, clotting reaction) were evaluated subsequently in a central laboratory.

RESULTS

A total of 46 patients were included in the final analyses. Mean (± standard deviation) age was 58.5 ± 9.0 years (13 women, 33 men; disease duration 6.3 ± 5.0 years; body mass index 32.0 ± 4.8 kg/m(2)). A total of 25 patients were treated with pioglitazone plus metformin, and 21 patients were in the glimepiride arm. There was a significant decline of E-selectin (-3.7 ± 4.8 ng/ml, p < .001 versus baseline), vWillebrand factor (-19.5 ± 32.0%, p < .05), and high-sensitivity C-reactive protein concentrations (-1.08 ± 0.91 mg/liter, p < .05) in the metformin + pioglitazone arm only (metformin + glimepiride, -0.5 ± 3.4 ng/ml, +1.4 ± 33.2%, + 0.08 ± 0.72 mg/liter, respectively, all not significant). Also, all other surrogate markers for platelet function and inflammation showed slight improvements in the metformin + pioglitazone arm but not in the metformin + glimepiride arm.

CONCLUSIONS

The fixed metformin + pioglitazone combination treatment showed an overall improvement of laboratory surrogate markers, indicating improvement of platelet function and of chronic systemic inflammation, which was not seen with metformin + glimepiride.

Fat redistribution preferentially reflects the anti-inflammatory benefits of pioglitazone treatment

Thiazoledinedione is known to have an anti-inflammatory effect besides a hypoglycemic effect. We investigated changes in high-sensitivity C-reactive protein (hsCRP), a proinflammatory marker, after pioglitazone treatment in association with the resulting changes in various metabolic and anthropometric parameters. A total of 93 type 2 diabetes mellitus patients (47 men and 46 women; mean age, 50.0 ± 10.8 years) who were being treated with a stable dose of sulfonylurea or metformin were enrolled in the study. Pioglitazone (15 mg/d) was added to their treatment regimen for 12 weeks, and metabolic and anthropometric measurements were taken before and after pioglitazone treatment. Pioglitazone treatment for 12 weeks decreased serum hsCRP levels (0.83 [1.14] to 0.52 [0.82] mg/L, P < .001) and improved glycemic control (fasting glucose, P < .001; glycosylated hemoglobin, P < .001) and lipid profiles (triglyceride, P = .016; high-density lipoprotein cholesterol, P < .001). Between responders and nonresponders to the hsCRP-lowering effect of pioglitazone, there were significant differences in baseline hsCRP levels and changes in the postprandial glucose and the ratio of visceral fat thickness (VFT) to subcutaneous fat thickness (SFT) (P = .004, .011, and .001, respectively). The percentage change in hsCRP levels after treatment was inversely correlated with baseline hsCRP levels (r = -0.497, P < .001) and directly correlated with the change in postprandial glucose (r = 0.251, P = .021), VFT (r = 0.246, P = .030), and VFT/SFT ratio (r = 0.276, P = .015). Logistic regression analysis revealed that the hsCRP-lowering effect of pioglitazone was affected by baseline hsCRP levels (odds ratio [OR] = 7.929, P = .007) as well as changes in postprandial 2-hour glucose (OR = 0.716, P = .025) and VFT/SFT ratio (OR = 0.055, P = .009). In conclusion, treatment with pioglitazone produced an anti-inflammatory effect, decreasing serum hsCRP levels; and a decrease in the VFT/SFT ratio was independently and most strongly associated with the hsCRP-decreasing effect. These results suggest that abdominal fat redistribution preferentially reflects the anti-inflammatory benefits of pioglitazone treatment.

Rosiglitazone induces the unfolded protein response, but has no significant effect on cell viability, in monocytic and vascular smooth muscle cells

Given the safety concerns expressed over negative cardiovascular outcomes resulting from the clinical use of rosiglitazone, and the view that rosiglitazone exerts PPARγ-independent effects alongside its insulin-sensitising PPARγ-dependent effects, we hypothesised that rosiglitazone may trigger Unfolded Protein Responses (UPRs) due to disruptions in [Ca(2+)](i) homeostasis within two cardiovascular cell types: monocytic (MM6) and vascular smooth muscle (A7r5) cells. In microsomal samples derived from both cell types, pre-incubation with rosiglitazone rapidly (30min) brought about concentration-dependent PPARγ-independent inhibition of Ca(2+)ATPase activity (IC(50) ∼2μM). Fluo-3 fluorimetric data demonstrated in intact cells that 1h treatment with 1 or 10μM rosiglitazone caused Ca(2+) ions to leak into the cytoplasm. Gene expression analysis showed that within 4h of rosiglitazone exposure, the UPR transcription factor XBP-1 was activated (likely due to corresponding ER Ca(2+) depletion), and the UPR target genes BiP and SERCA2b were subsequently upregulated within 24-72h. After 72h 1 or 10μM rosiglitazone treatment, microsomal Ca(2+)ATPase activity increased to >2-fold of that seen in control microsomes, while [Ca(2+)](i) returned to basal, indicating that UPR-triggered SERCA2b upregulation was responsible for enhanced enzymatic Ca(2+) sequestration within the ER. This appeared to be sufficient to replenish ER Ca(2+) stores and restore normal cell physiology, as cell viability levels were not decreased due to rosiglitazone treatment throughout a 2-week study. Thus, incubation with 1-10μM rosiglitazone triggers the UPR, but does not prove cytotoxic, in cells of the cardiovascular system. This observation provides an important contribution to the current debate over the use of rosiglitazone in the clinical treatment of Type-2 Diabetes.

Effects of physical exercise versus rosiglitazone on endothelial function in coronary artery disease patients with prediabetes

We conducted a three-arm, parallel-group, randomized, controlled trial to compare the effects of rosiglitazone and physical exercise on endothelial function in patients with coronary artery disease and impaired fasting glucose or impaired glucose tolerance over a 6-month period. Group A received rosiglitazone tablets 8 mg daily (n = 16), group B underwent a structured physical exercise programme (n = 15) and group C served as a control group (n = 12). At baseline and after 6 months, brachial artery ultrasound imaging was performed to assess reactive flow-mediated dilation (FMD). Rosiglitazone treatment and exercise both led to significant improvements in insulin resistance at 6 months, whereas no change was observed in control patients. FMD improved significantly in physical exercise patients, whereas no change could be observed in patients receiving rosiglitazone or in the control group. Between-group comparisons also showed a significant relative improvement in FMD in exercise patients compared with rosiglitazone.

Rapid effect of single-dose rosiglitazone treatment on endothelial function in healthy men with normal glucose tolerance: data from a randomised, placebo-controlled, double-blind study

Antidiabetic thiazolidinediones (TZDs) improve endothelial function in patients with or without type 2 diabetes. The present randomised, placebo-controlled, double-blind study examined the time course of a single dose of rosiglitazone on flow-mediated endothelium-dependent vasodilation (FMD), metabolic parameters, and its effect on inflammatory markers in non-diabetic men. Forty non-obese, healthy men with normal glucose tolerance were randomised to a single dose of rosiglitazone (8 mg) or placebo, and FMD was assessed at baseline as well as after 6 h and 24 h. Rosiglitazone did not significantly affect blood glucose and insulin levels or lipid parameters after 6 and 24 h compared with placebo. Treatment with rosiglitazone significantly increased FMD after 6 h from 4.3% (3.3; 4.9) to 7.6% (5.6; 9.2) (p<0.0001 vs. baseline) resulting in a highly significant effect compared with placebo (p<0.0001 for difference between groups). After 24 h FMD was still significantly higher in the rosiglitazone group compared with baseline (p=0.001), but the effect was no longer statistically significant versus placebo (p=0.171). Our study shows a very rapid effect of single dose rosiglitazone treatment on endothelial function in non-diabetic healthy men, underscoring the hypothesis that TZDs may exhibit direct effect in the vasculature independent of their metabolic action.

Osteoprotegerin as a predictor of coronary artery disease and cardiovascular mortality and morbidity

Osteoprotegerin (OPG) is a glycoprotein that acts as a decoy receptor for receptor activator of nuclear factor kappaB ligand (RANKL) and tumor necrosis factor-related apoptosis-inducing ligand. The OPG/RANKL/receptor activator of nuclear factor kappaB axis plays an important regulatory role in the skeletal, immune, and vascular systems. The protective role of OPG, in animal models, against vascular calcification has not been replicated in human trials; moreover, increased OPG levels have been consistently associated with the incidence and prevalence of coronary artery disease. There seems to be some dichotomy in the role of OPG, RANKL, and tumor necrosis factor-related apoptosis-inducing ligand in atherosclerosis and plaque stability. In this review, we integrate the findings from some of the important studies and try to draw conclusions with a view to gaining some insight into the complex interactions of the OPG/RANKL/receptor activator of nuclear factor kappaB axis and tumor necrosis factor-related apoptosis-inducing ligand in the pathophysiology of atherosclerosis.

Endothelial dysfunction in diabetes mellitus: molecular mechanisms and clinical implications

Cardiovascular disease is a major complication of diabetes mellitus, and improved strategies for prevention and treatment are needed. Endothelial dysfunction contributes to the pathogenesis and clinical expression of atherosclerosis in diabetes mellitus. This article reviews the evidence linking endothelial dysfunction to human diabetes mellitus and experimental studies that investigated the responsible mechanisms. We then discuss the implications of these studies for current management and for new approaches for the prevention and treatment of cardiovascular disease in patients with diabetes mellitus.

Alteration of vascular reactivity in diabetic human mammary artery and the effects of thiazolidinediones

Vascular reactivity was investigated in endothelium-denuded human internal mammary artery (IMA) rings from type 2 diabetic patients. It was also investigated whether insulin sensitizer thiazolidinedione drugs, pioglitazone and rosiglitazone, can directly affect the reactivity of IMA. Using organ bath techniques, cumulative concentration-response curves to phenylephrine (PE), KCl, cromakalim (CRO) and sodium nitroprusside (SNP) were constructed in diabetic and non-diabetic IMA rings. Means of maximal responses (% Emax) and pEC50 values (sensitivity) were compared. Emax values and the sensitivity to PE and KCl were increased while KATP-channel-mediated relaxations were reduced significantly in diabetic rings compared with non-diabetic rings (n = 5–12, P &lt; 0.05). No changes were observed for SNP responses (n = 5, P &gt; 0.05). Incubations with pioglitazone (1 and 10 μM) and rosiglitazone (1 and 20 μM), for 30 min, did not affect KATP-channel-mediated relaxations (n = 5 each, P &gt; 0.05). Pioglitazone partly inhibited pre-contractions of PE and KCl at 10 μM, rosiglitazone did not. Vascular dysfunction observed in diabetic IMA may be of specific importance since they are widely used as coronary bypass material. Thiazolidinedione drugs may not worsen arterial dilatation through KATP channels in ischaemic or hypoxic insults in diabetic patients who are prone to such conditions. Pioglitazone has vasorelaxant property in the grafts.

Association between serum amyloid A and obesity: a meta-analysis and systematic review

BACKGROUND

Emerging evidence indicates an association of the acute-phase protein serum amyloid A (SAA) with obesity. Here we review and summarize quantitatively the available data related to this association.

METHODS

PubMed was systematically searched using the terms "serum amyloid A" and "obesity." Eighty-one relevant studies between January 1966 and July 2009 were identified. Of these, only 11 cross-sectional studies and 10 prospective studies with successful interventions met our inclusion criteria for the meta-analysis. All analyses were conducted using the Comprehensive Meta-Analysis software. Literature pertaining to the relationship between SAA and other inflammatory markers, and the association between SAA and obesity-related disorders, such as cardiovascular diseases, atherosclerosis, diabetes, and insulin resistance was also reviewed.

RESULTS

A strong association between body mass index and SAA levels was found in the 11 cross-sectional studies. The overall correlation coefficient is 0.230 (95% CI 0.160-0.297, P < 0.0005). The ten prospective studies were subsequently analyzed, and the difference in SAA levels before and after weight loss, expressed as standardized mean difference was -0.480 (95% CI -0.678 to -0.283, P < 0.0005). We discuss some potential underlying mechanisms and clinical applications for reducing SAA levels in obesity.

Triple verses glimepiride plus metformin therapy on cardiovascular risk biomarkers and diabetic cardiomyopathy in insulin resistance type 2 diabetes mellitus rats

IRtype2DM patients are often treated with a combination of antidiabetic agents. Drugs with different complementary mechanisms of action frequently used in daily clinical practice but glycemic control with monotherapeutic attempts fail in the long run. To date, biomarkers for cardiovascular risk and insulin sensitivity with combination of triple oral hypoglycemic therapies are not fully revelled in view of additional cardiovascular risk reduction. In the present study, IRtype2DM induced by administering streptozotocin (90 mg/kg, i.p.) in neonatal rat model. IRtype2DM rats were selected by determining FPI [>60 pmol/l]; HOMA-IR & Hyperinsulinemic euglycemic clamp technique at 6 weeks and then treated for 8 weeks with (i) Metformin (120 mg/kg, o.d.)+Glimepiride (1mg/kg, o.d.), (ii) Metformin (265 mg/kg, o.d.)+Rosiglitazone (1mg/kg, o.d.)+Glimepiride (0.7 mg/kg, o.d.). At the end cardiovascular risk parameters evaluated by ELISA kits and insulin sensitivity were determined by HOMA-IR. In conclusion, triple oral hypoglycemic therapy improves glycemic control, insulin sensitivity, retards diabetic cardiomyopathy and does not increased body weight; decrease more detrimental inflammatory markers, increase interleukin-10 and adiponectin in neonatal streptozotocin-induced IRtype2DM Wistar Albino Rats. Triple therapy showed a synergistic effect and was promising in insulin resistance, better in additional cardiovascular risk reduction and those nonresponders to metformin add on glimepiride therapy.

The CD40/CD40 ligand system: linking inflammation with atherothrombosis

The role of CD40/CD40 ligand (CD40L) in atherothrombosis is now widely accepted. However, the exact mechanisms linking the CD40/CD40L system and the soluble form of CD40 ligand (sCD40L) with atherothrombosis are currently a topic of intensive research. CD40L and sCD40L belong to the tumor necrosis factor superfamily, and they are molecules with a dual prothrombotic and proinflammatory role. They are expressed in a variety of tissues such as the immune system (in both B and T cells), the vascular wall, and activated platelets. Soluble CD40L has multiple autocrine, paracrine, and endocrine actions, and it may trigger key mechanisms participating in atherothrombosis. CD40/CD40L may participate in the development of coronary atherosclerosis and the triggering of acute coronary syndromes, while sCD40L seems to have a prognostic role not only in subjects with advanced atherosclerosis but also in the general population. Although conventional cardiovascular medication such as antiplatelet therapy, statins, angiotensin-converting enzyme inhibitors, and many others have been shown to reduce both sCD40L and cardiovascular risk, it is still unclear whether specific treatments targeting the CD40/CD40L system will prove to be beneficial against atherothrombosis in the near future.

Pioglitazone enhances collateral blood flow in ischemic hindlimb of diabetic mice through an Akt-dependent VEGF-mediated mechanism, regardless of PPARgamma stimulation

Background

Type 2 diabetes mellitus (T2DM) is commonly associated with both microvascular and macrovascular complications and a strong correlation exists between glycaemic control and the incidence and progression of vascular complications. Pioglitazone, a Peroxisome proliferator-activated receptor-γ (PPARγ) ligand indicated for therapy of type T2DM, induces vascular effects that seem to occur independently of glucose lowering.

Methods

By using a hindlimb ischemia murine model, in this study we have found that pioglitazone restores the blood flow recovery and capillary density in ischemic muscle of diabetic mice and that this process is associated with increased expression of Vascular Endothelial Growth Factor (VEGF). Importantly, these beneficial effects are abrogated when endogenous Akt is inhibited; furthermore, the direct activation of PPARγ, with its selective agonist GW1929, does not restore blood flow recovery and capillary density. Finally, an important collateral vessel growth is obtained with combined treatment with pioglitazone and selective PPARγ inhibitor GW9662.

Conclusion

These data demonstrate that Akt-VEGF pathway is essential for ischemia-induced angiogenic effect of pioglitazone and that pioglitazone exerts this effect via a PPARγ independent manner.

Anti-inflammatory effect of rosiglitazone is not reflected in expression of NFkappaB-related genes in peripheral blood mononuclear cells of patients with type 2 diabetes mellitus

BACKGROUND

Rosiglitazone not only improves insulin-sensitivity, but also exerts anti-inflammatory effects. We have now examined in type 2 diabetic patients if these effects are reflected by changes in mRNA expression in peripheral blood mononuclear cells (PBMCs) to see if these cells can be used to study these anti-inflammatory effects at the molecular level in vivo.

METHOD

Eleven obese type 2 diabetic patients received rosiglitazone (2 x 4 mg/d) for 8 weeks. Fasting blood samples were obtained before and after treatment. Ten obese control subjects served as reference group. The expression of NFkappaB-related genes and PPARgamma target genes in PBMCs, plasma TNFalpha, IL6, MCP1 and hsCRP concentrations were measured. In addition, blood samples were obtained after a hyperinsulinemic-euglycemic clamp.

RESULTS

Rosiglitazone reduced plasma MCP1 and hsCRP concentrations in diabetic patients (-9.5 +/- 5.3 pg/mL, p = 0.043 and -1.1 +/- 0.3 mg/L p = 0.003), respectively). For hsCRP, the concentration became comparable with the non-diabetic reference group. However, of the 84 NFkappaB-related genes that were measured in PBMCs from type 2 diabetic subjects, only RELA, SLC20A1, INFgamma and IL1R1 changed significantly (p < 0.05). In addition, PPARgamma and its target genes (CD36 and LPL) did not change. During the clamp, insulin reduced plasma MCP1 concentration in the diabetic and reference groups (-9.1 +/- 1.8%, p = 0.001 and -11.1 +/- 4.1%, p = 0.023, respectively) and increased IL6 concentration in the reference group only (23.5 +/- 9.0%, p = 0.028).

CONCLUSION

In type 2 diabetic patients, the anti-inflammatory effect of rosiglitazone is not reflected by changes in NFkappaB and PPARgamma target genes in PBMCs in vivo. Furthermore, our results do not support that high insulin concentrations contribute to the pro-inflammatory profile in type 2 diabetic patients.

Fat poetry: a kingdom for PPAR gamma

Adipose tissue is not an inert cell mass contributing only to the storage of fat, but a sophisticated ensemble of cellular components with highly specialized and complex functions. In addition to managing the most important energy reserve of the body, it secretes a multitude of soluble proteins called adipokines, which have beneficial or, alternatively, deleterious effects on the homeostasis of the whole body. The expression of these adipokines is an integrated response to various signals received from many organs, which depends heavily on the integrity and physiological status of the adipose tissue. One of the main regulators of gene expression in fat is the transcription factor peroxisome proliferator-activated receptor gamma (PPARgamma), which is a fatty acid- and eicosanoid-dependent nuclear receptor that plays key roles in the development and maintenance of the adipose tissue. Furthermore, synthetic PPARgamma agonists are therapeutic agents used in the treatment of type 2 diabetes.This review discusses recent knowledge on the link between fat physiology and metabolic diseases, and the roles of PPARgamma in this interplay via the regulation of lipid and glucose metabolism. Finally, we assess the putative benefits of targeting this nuclear receptor with still-to-be-identified highly selective PPARgamma modulators.