New Drugs for the Treatment of Diabetes Mellitus

Celastrol Stabilizes Glycolipid Metabolism in Hepatic Steatosis by Binding and Regulating the Peroxisome Proliferator-Activated Receptor γ Signaling Pathway

The prevalence of nonalcoholic fatty liver disease (NAFLD) has been increasing. Obesity, insulin resistance, and lipid metabolic dysfunction are always accompanied by NAFLD. Celastrol modulates the Peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer binding protein α (C/EBPα) signaling pathways, thereby promoting lipolysis in 3T3-L1 adipocytes. In the present study, oleic-acid-induced NAFLD and differentiated 3T3-L1 preadipocytes were used as models of NAFLD and obesity to investigate the protective effect of celastrol. We investigated the impact of celastrol on hepatic steatosis caused by oleic acid (OA), as well as the associated underlying molecular pathways. To address the aforementioned questions, we used a cellular approach to analyze the signaling effects of celastrol on various aspects. These factors include the improvement in fatty liver in HepG2 cells, the differentiation of 3T3-L1 preadipocytes, glucose uptake, and the modulation of key transcriptional pathways associated with PPARγ. The administration of celastrol effectively mitigated lipid accumulation caused by OA in HepG2 cells, thereby ameliorating fatty liver conditions. Furthermore, celastrol suppressed the impacts on adipocyte differentiation in 3T3-L1 adipocytes. Additionally, celastrol exhibited the ability to bind to PPARγ and modulate its transcriptional activity. Notably, the ameliorative effects of celastrol on hepatic steatosis were reversed by rosiglitazone. According to our preliminary findings from in vitro celastrol signaling studies, PPARγ is likely to be the direct target of celastrol in regulating hepatic steatosis in HepG2 cells and adipocyte differentiation in 3T3-L1 cells.

In Vivo Inhibition of miR-34a Modestly Limits Cardiac Enlargement and Fibrosis in a Mouse Model with Established Type 1 Diabetes-Induced Cardiomyopathy, but Does Not Improve Diastolic Function

MicroRNA 34a (miR-34a) is elevated in the heart in a setting of cardiac stress or pathology, and we previously reported that inhibition of miR-34a in vivo provided protection in a setting of pressure overload-induced pathological cardiac hypertrophy and dilated cardiomyopathy. Prior work had also shown that circulating or cardiac miR-34a was elevated in a setting of diabetes. However, the therapeutic potential of inhibiting miR-34a in vivo in the diabetic heart had not been assessed. In the current study, type 1 diabetes was induced in adult male mice with 5 daily injections of streptozotocin (STZ). At 8 weeks post-STZ, when mice had established type 1 diabetes and diastolic dysfunction, mice were administered locked nucleic acid (LNA)-antimiR-34a or saline-control with an eight-week follow-up. Cardiac function, cardiac morphology, cardiac fibrosis, capillary density and gene expression were assessed. Diabetic mice presented with high blood glucose, elevated liver and kidney weights, diastolic dysfunction, mild cardiac enlargement, cardiac fibrosis and reduced myocardial capillary density. miR-34a was elevated in the heart of diabetic mice in comparison to non-diabetic mice. Inhibition of miR-34a had no significant effect on diastolic function or atrial enlargement, but had a mild effect on preventing an elevation in cardiac enlargement, fibrosis and ventricular gene expression of B-type natriuretic peptide (BNP) and the anti-angiogenic miRNA (miR-92a). A miR-34a target, vinculin, was inversely correlated with miR-34a expression, but other miR-34a targets were unchanged. In summary, inhibition of miR-34a provided limited protection in a mouse model with established type 1 diabetes-induced cardiomyopathy and failed to improve diastolic function. Given diabetes represents a systemic disorder with numerous miRNAs dysregulated in the diabetic heart, as well as other organs, strategies targeting multiple miRNAs and/or earlier intervention is likely to be required.

Adiponectin reduces apoptosis of diabetic cardiomyocytes by regulating miR-711/TLR4 axis

OBJECTIVE

To investigate the regulation of adiponectin/miR-711 on TLR4/NF-κB-mediated inflammatory response and diabetic cardiomyocyte apoptosis.

METHODS

Diabetes models were established using rats and H9c2 cardiomyocytes. qRT-PCR was used to detect adiponectin, miR-711, and TLR4. MTT, β-galactosidase staining, and flow cytometry were utilized to assess cell viability, senescence, and apoptosis, respectively. The colorimetric method was used to measure caspase-3 activity, DCFH-DA probes to detect ROS, and western blotting to determine the protein levels of Bax, Bcl-2, TLR4, and p-NF-κB p65. ELISA was performed to measure the levels of adiponectin, ICAM-1, MCP-1, and IL-1β. Dual-luciferase reporter system examined the targeting relationship between miR-711 and TLR4. H&E and TUNEL staining revealed myocardial structure and apoptosis, respectively.

RESULTS

Adiponectin and miR-711 were underexpressed and TLR4/NF-κB signaling pathway was activated in high glucose-treated H9c2 cells. High glucose treatment reduced viability, provoked inflammatory response, and accelerated senescence and apoptosis in H9c2 cells. miR-711 could bind TLR4 mRNA and inactivate TLR4/NF-κB signaling. Adiponectin treatment increased miR-711 expression and blocked TLR4/NF-κB signaling. Adiponectin/miR-711 reduced myocardial inflammation and apoptosis in diabetic rats.

CONCLUSION

Adiponectin inhibits inflammation and alleviates high glucose-induced cardiomyocyte apoptosis by blocking TLR4/NF-κB signaling pathway through miR-711.

Inflammatory Mechanisms of Diabetes and Its Vascular Complications

The main cause of death in patients with type 2 DM is cardiovascular complications resulting from the progression of atherosclerosis. The pathophysiology of the association between diabetes and its vascular complications is complex and multifactorial and closely related to the toxic effects of hyperglycemia that causes increased generation of reactive oxygen species and promotes the secretion of pro-inflammatory cytokines. Subsequent oxidative stress and inflammation are major factors of the progression of type 2 DM and its vascular complications. Data on the pathogenesis of the development of type 2 DM and associated cardiovascular diseases, in particular atherosclerosis, open up broad prospects for the further development of new diagnostic and therapeutic approaches.

Antihyperglycemic therapies and cardiovascular outcomes in patients with type 2 diabetes mellitus: State of the art and future directions

Type 2 diabetes mellitus is a progressive chronic disease and is an established risk factor for cardiovascular disease. Until recently, the cardiovascular safety and efficacy of antihyperglycemic drugs remained uncertain. However, after the changes in regulatory guidance in 2008, a wealth of data has been generated, expanding the focus of the treatment of diabetes from blood glucose control to the prevention of macro-and microvascular complications and improvement in mortality. This article will review cardiovascular outcome trials of antihyperglycemic agents and provide overview of ongoing trials.

Sodium-glucose Co-transporters-2 Inhibitors and Heart Failure: State of the Art Review and Future Potentials

Heart failure (HF) and type 2 diabetes mellitus (T2DM) are progressive chronic diseases that increase the risk of mortality and have worse outcomes when they coexist. There has been a paucity of data on effective therapeutic measures that reduce the risk of HF in patients with T2DM. However, the issuance of the Food and Drug Administration guidance in 2008 generated data on several antihyperglycemic agents that show cardiovascular (CV) benefits beyond glucose lowering. Among them, sodium-glucose co-transporter 2 (SGLT2) inhibitors have emerged as a class of drug with proven robust benefits in modulating HF and kidney diseases in patients with T2DM. In this article, we reviewed the epidemiology, pathophysiology, prognosis, lifestyle management, and therapeutic options, especially SGLT2 inhibitors, for HF and T2DM.

Rubia tinctorum root extracts: chemical profile and management of type II diabetes mellitus

The chemical and biological profiling of the root extracts of Rubia tinctorum was performed. The activities of different extracts were determined considering the antidiabetic effect against type II diabetes mellitus together with anti-obesity and hepatoprotective effects and lipid profile. The methanolic extract of Rubia tinctorum exhibited significant results in decreasing body weight, improving lipid profile, normalizing hyperglycaemia, insulin resistance, hyperinsulinemia. Additionally, it showed enhancement of liver tissue structure and function. The methanolic extract, being the most significant one, was subjected to LC-HRMS analysis to determine its chemical constituents. Finally, the chemical constituents were evaluated by molecular docking study that was carried out to identify the interaction of a panel of 45 compounds in silico and to correlate the structures to their anti-diabetic activity. Among the tested compounds, 1-hydroxy-2-hydroxymethyl anthra-quinone and naringenin-7-O-glucoside showed the most potent activity as α-amylase inhibitors.

The chemical and biological profiling of the root extracts of Rubia tinctorum was performed.

Tautomerase Activity-Lacking of the Macrophage Migration Inhibitory Factor Alleviates the Inflammation and Insulin Tolerance in High Fat Diet-Induced Obese Mice

Macrophage migration inhibitory factor (MIF) has multiple intrinsic enzymatic activities of the dopachrome/phenylpyruvate tautomerase and thiol protein oxidoreductase, and plays an important role in the development of obesity as a pro-inflammatory cytokine. However, which enzymatic activity of MIF is responsible for regulating in obesity are still unknown. In the present study, we investigated the roles of the tautomerase of MIF in high fat diet (HFD)-induced obesity using MIF tautomerase activity-lacking (MIF^P1G/P1G) mice. Our results showed that the serum MIF and the expression of MIF in adipose tissue were increased in HFD-treated mice compared with normal diet fed mice. The bodyweights were significantly reduced in MIF^P1G/P1G mice compared with WT mice fed with HFD. The sizes of adipocytes were smaller in MIF^P1G/P1G mice compared with WT mice fed with HFD using haematoxylin and eosin (H&E) staining. In addition, the MIF^P1G/P1G mice reduced the macrophage infiltration, seen as the decreases of the expression of inflammatory factors such as F4/80, IL-1β, TNFα, MCP1, and IL-6. The glucose tolerance tests (GTT) and insulin tolerance tests (ITT) assays showed that the glucose tolerance and insulin resistance were markedly improved, and the expressions of IRS and PPARγ were upregulated in adipose tissue from MIF^P1G/P1G mice fed with HFD. Furthermore, we observed that the expressions of Bax, a pro-apoptotic protein, and the cleaved caspase 3-positive cells in white tissues were decreased and the ratio of Bcl2/Bax was increased in MIF^P1G/P1G mice compared with WT mice. Taken together, our results demonstrated that the tautomerase activity-lacking of MIF significantly alleviated the HFD-induced obesity and adipose tissue inflammation, and improved insulin resistance in MIF^P1G/P1G mice.

MiR-27a promotes insulin resistance and mediates glucose metabolism by targeting PPAR-γ-mediated PI3K/AKT signaling

This study aimed to establish a high-fat diet (HFD)-fed obese mouse model and a cell culture model of insulin resistance (IR) in mature 3T3-L1 adipocytes. A dual-luciferase reporter assay (DLRA) was confirmed interaction between miR-27a and the 3'-untranslated region (UTR) of Peroxisome proliferator-activated receptor (PPAR)-γ. The inhibition of PPAR-γ expression by microRNA (miR)-27a in IR cells at both the protein and mRNA levels was confirmed by a mechanistic investigation. Moreover, the 3'-UTR of PPAR-γ was found to be a direct target of miR-27a, based on the DLRA. Furthermore, antagomiR-27a upregulated the activation of PI3K/Akt signaling and glucose transporter type 4 (GLUT4) expression at the protein and mRNA levels. Additionally, the PPAR inhibitor T0070907 repressed the insulin sensitivity upregulated by antagomiR-27a, which was accompanied by the inhibition of PPAR-γ expression and increased levels of AKT phosphorylation and GLUT4. The PI3K inhibitor wortmannin reduced miR-27a-induced increases in AKT phosphorylation, glucose uptake, and GLUT4. miR-27a is considered to be involved in the PPAR-γ-PI3K/AKT-GLUT4 signaling axis, thus leading to increased glucose uptake and decreased IR in HFD-fed mice and 3T3-L1 adipocytes. Therefore, miR-27a is a novel target for the treatment of IR in obesity and diabetes.

Emerging Actors in Diabetic Cardiomyopathy: Heartbreaker Biomarkers or Therapeutic Targets?

The diabetic heart is characterized by metabolic disturbances that are often accompanied by local inflammation, oxidative stress, myocardial fibrosis, and cardiomyocyte apoptosis. Overall changes result in contractile dysfunction, concentric left ventricular (LV) hypertrophy, and dilated cardiomyopathy, that together affect cardiac output and eventually lead to heart failure, the foremost cause of death in diabetic patients. There are currently several validated biomarkers for the diagnosis and risk assessment of cardiac diseases, but none is capable of discriminating patients with diabetic cardiomyopathy (DCM). In this review we point to several novel candidate biomarkers from new activated molecular pathways (including microRNAs) with the potential to detect or prevent DCM in its early stages, or even to treat it once established. The prospective use of selected biomarkers that integrate inflammation, oxidative stress, fibrosis, and metabolic dysregulation is widely discussed.

Cardiovascular Outcomes Trials of Glucose-Lowering Drugs or Strategies in Type 2 Diabetes

As recently as 20 years ago there were no randomized controlled trials of potentially cardiovascular protective therapies in people with type 2 diabetes. The ongoing cardiovascular trials bring needed evidence. Both primary and subsidiary analyses have transformed diabetes from a largely eminence based specialty to one that is firmly evidence based. These studies have provided evidence supporting glucose-lowering drugs for patients with cardiovascular risk factors. Randomized controlled trials such as those described here will continue to challenge assumptions and create new approaches and paradigms that can be pursued to reduce and hopefully eliminate serious cardiovascular and other consequences of diabetes.

Pharmacotherapy of type 2 diabetes: An update

Type 2 diabetes (T2DM) is a leading cause of morbidity and mortality worldwide and a major economic burden. The prevalence of T2DM is rising, suggesting more effective prevention and treatment strategies are necessary. The aim of this narrative review is to summarize the pharmacologic treatment options available for patients with T2DM. Each therapeutic class is presented in detail, outlining medication effects, side effects, glycemic control, effect on weight, indications and contraindications, and use in selected populations (heart failure, renal insufficiency, obesity and the elderly). We also present representative cost for each antidiabetic category. Then, we provide an individualized guide for initiation and intensification of treatment and discuss the considerations and rationale for an individualized glycemic goal.

Pioglitazone and the Risk of Bladder Cancer: A Meta-Analysis

People with type 2 diabetes are at increased risk of bladder cancer. Pioglitazone is said to increase it further, although published evidence is mixed. We conducted a meta-analysis to determine if any link between the use of pioglitazone and an increased risk of bladder cancer can be found. A comprehensive literature search was conducted through electronic databases as well as registries for data of clinical trials to identify studies that investigate the effect of pioglitazone on bladder cancer in diabetic patients. We used the risk ratio (RR) and the hazard ratio (HR) provided by the studies to illustrate the risk of occurrence of bladder cancer in the experimental group compared to that in the control group. Fourteen studies using RR and 12 studies using HR were included in the analysis. The overall RR was 1.13 with 95% CI (0.96-1.33) with low heterogeneity among the studies using RR, suggesting that no connection exists between use of pioglitazone and the risk of bladder malignancy. The summary HR was 1.07 (0.96-1.18) allowing us to affirm that there is no link between long-term use of pioglitazone and bladder cancer. Our results support the hypothesis of no difference in the incidence of bladder cancer among the pioglitazone group and the nonuser group. Our conclusion is that the explanation of hypothetically increased risk of bladder malignancy should be attributed to other factors.

FUNDING

Tchaikapharma High Quality Medicines Inc.

Integration of recent evidence into management of patients with atherosclerotic cardiovascular disease and type 2 diabetes

Cardiovascular outcome trials of antihyperglycaemic drugs and non-statin LDL-cholesterol-lowering drugs in patients with type 2 diabetes who have, or who are at high risk of, atherosclerotic cardiovascular disease have provided new evidence that has substantially affected the management of cardiovascular risk in these patients. On the basis of proven cardiovascular and renal benefit, the antihyperglycaemic drugs empagliflozin, liraglutide, and semaglutide-the latter being under review for approval by the US Food and Drug Administration and the European Medicines Agency-should be preferentially used as second-line treatments in these patient populations, typically in addition to metformin. Further treatment differentiation among the remainder of the antihyperglycaemic drugs should be made on the basis of evidence regarding cardiovascular safety, which is available for lixisenatide, alogliptin, saxagliptin, sitagliptin, and insulin glargine. The risk of heart failure, stroke, or retinopathy, or prevalent fasting versus postprandial hyperglycaemia, could also be considered in treatment decision making. Finally, emerging evidence of cardiovascular benefit for ezetimibe, alirocumab, and evolocumab positions these drugs as add-ons to maximally tolerated statin therapy or for those with statin intolerance.

Effects of pioglitazone therapy on blood parameters, weight and BMI: a meta-analysis

BACKGROUND

Type 2 diabetes mellitus (T2DM) is one of the most common diseases worldwide and insulin insufficiency and insulin resistance are two main metabolic issues connected with it. The dyslipidemia associated with insulin resistance and T2DM is characterized by higher triglycerides (TGs), higher very-low-density lipoprotein cholesterol and lower apo A1. Pioglitazone, a member of the thiazolidinedione class, with a proven antihyperglycemic effect, is known to positively influence insulin sensitivity and β-cell function and to have the potential to alter the lipid profile.

METHODS

The aim of our meta-analysis is to summarize and determine the influence of pioglitazone on the glycemic profile and lipoprotein metabolism as well as on weight and BMI in order to highlight the benefit of pioglitazone therapy in patients with T2DM. A comprehensive literature search was conducted through the electronic databases PubMed, MEDLINE, Scopus, PsyInfo, eLIBRARY.ru (from 2000 until February 2016) to identify studies that investigate the effect of pioglitazone on the glycemic and lipid profile and on the weight and BMI. We chose the random-effects method as the primary analysis. Forest plots depict estimated results from the studies included in the analysis and funnel plots are used to evaluate publication bias. Sensitivity analyses were performed in order to evaluate the degree of influence of the consequent elimination of each individual study on the final result.

RESULTS

Of the 1536 identified sources only 15 randomised trials were included in the meta-analysis. Pioglitazone treatment was associated with improvement in the glycemic profile. It reduced FPG levels by a mean of 1.1-2 mmol/l and HbA1c by a mean of 0.9-1.3%. Our results reaffirmed the hypothesis that pioglitazone has a positive influence on the lipid profile of T2DM patients with increase in TC and HDL, no significant changes in LDL and notable decrease in TGs. Results also showed that pioglitazone therapy led to increase in both weight and BMI (WMD 1.755, 95% CI 0.674 to 2.837 and 1.145, 95% CI 0.389 to 1.901 respectively).

CONCLUSION

Our results prove that the PPAR γ agonist pioglitazone has the potential to be beneficial to patients with T2DM.

PPARγ signaling and emerging opportunities for improved therapeutics

Peroxisome proliferator-activated receptor gamma (PPARγ) is a ligand-activated nuclear receptor that regulates glucose and lipid metabolism, endothelial function and inflammation. Rosiglitazone (RGZ) and other thiazolidinedione (TZD) synthetic ligands of PPARγ are insulin sensitizers that have been used for the treatment of type 2 diabetes. However, undesirable side effects including weight gain, fluid retention, bone loss, congestive heart failure, and a possible increased risk of myocardial infarction and bladder cancer, have limited the use of TZDs. Therefore, there is a need to better understand PPARγ signaling and to develop safer and more effective PPARγ-directed therapeutics. In addition to PPARγ itself, many PPARγ ligands including TZDs bind to and activate G protein-coupled receptor 40 (GPR40), also known as free fatty acid receptor 1. GPR40 signaling activates stress kinase pathways that ultimately regulate downstream PPARγ responses. Recent studies in human endothelial cells have demonstrated that RGZ activation of GPR40 is essential to the optimal propagation of PPARγ genomic signaling. RGZ/GPR40/p38 MAPK signaling induces and activates PPARγ co-activator-1α, and recruits E1A binding protein p300 to the promoters of target genes, markedly enhancing PPARγ-dependent transcription. Therefore in endothelium, GPR40 and PPARγ function as an integrated signaling pathway. However, GPR40 can also activate ERK1/2, a proinflammatory kinase that directly phosphorylates and inactivates PPARγ. Thus the role of GPR40 in PPARγ signaling may have important implications for drug development. Ligands that strongly activate PPARγ, but do not bind to or activate GPR40 may be safer than currently approved PPARγ agonists. Alternatively, biased GPR40 agonists might be sought that activate both p38 MAPK and PPARγ, but not ERK1/2, avoiding its harmful effects on PPARγ signaling, insulin resistance and inflammation. Such next generation drugs might be useful in treating not only type 2 diabetes, but also diverse chronic and acute forms of vascular inflammation such as atherosclerosis and septic shock.

Heart Failure Considerations of Antihyperglycemic Medications for Type 2 Diabetes

Prevalent and incident heart failure (HF) is increased in people with type 2 diabetes mellitus, with risk directly associated with the severity of hyperglycemia. Furthermore, in patients with type 2 diabetes mellitus, mortality is increased ≈10-fold in patients with versus without HF. Reducing HF with antihyperglycemic therapies, however, has been unsuccessful until recently. In fact, HF as an important outcome in patients with type 2 diabetes mellitus seems to be heterogeneously modulated by antihyperglycemic medications, as evidenced by results from cardiovascular outcome trials (CVOTs) and large observational cohort studies. Appropriately powered and executed CVOTs are necessary to truly evaluate cardiovascular safety and efficacy of new antihyperglycemic medications, as reflected by the guidance of the US Food and Drug Administration and other regulatory agencies since 2008. In light of the best available evidence at present, metformin and the sodium-glucose-co-transporter 2-inhibitor empagliflozin seem to be especially advantageous with regard to HF effects, with their use associated with reduced HF events and improved mortality. Acarbose, the dipeptidyl-peptidase 4-inhibitor sitagliptin, the glucagon-like peptide 1-receptor agonist lixisenatide based on presently available CVOT results comprise reasonable additional options, as significant harm in terms of HF has been excluded for those drugs. Additions to this list are anticipated pending results of ongoing CVOTs. Although no HF harm was seen in CVOTs for insulin or sulfonylureas, they should be used only with caution in patients with HF, given their established high risk for hypoglycemia and some uncertainties on their safety in patients with HF derived from epidemiological observations. Pioglitazone is contraindicated in patients with HF>New York Heart Association I, despite some benefits suggested by CVOT subanalyses.

Predicting cardiovascular risk in type 2 diabetes: the heterogeneity challenges

Type 2 diabetes mellitus has reached epidemic proportions around the world, and the increase in cardiovascular risk attributable to diabetes estimated to range from 2- to 4-fold poses grave public health concern. Though in some contexts type 2 diabetes has been equated with coronary heart disease equivalent risk, there is considerable evidence that incremental cardiovascular risk does not uniformly affect all people with type 2 diabetes. This heterogeneity in cardiovascular risk is multifactorial and only partially understood but is a key consideration for our understanding of the nexus of diabetes and cardiovascular disease and for the development of optimal and individualized cardiovascular risk reduction strategies. This review provides a brief synopsis of the concept of cardiovascular risk heterogeneity in diabetes, including epidemiologic evidence, discussion of established and potential determinants of heterogeneity, and clinical, research, and regulatory implications.

Rosiglitazone protects rat liver against acute liver injury associated with the NF-κB signaling pathway

Rosiglitazone, which is mainly used in the treatment of diabetes mellitus, is also involved in the regulation of inflammation. The peroxisome proliferator-activated receptor (PPAR)-γ receptor subtype appears to play a pivotal role in the regulation of inflammation. However, the exact mechanism for the protective effects of rosiglitazone against inflammation such as liver injury remains unclear. The aim of this study was to investigate the effects of rosiglitazone on inflammation in the liver of rats treated with D-GaIN/LPS. Male Sprague–Dawley rats were injected with D-GaIN/LPS with or without pre-administration of rosiglitazone (3, 10, or 30 mg/kg, intraperitoneal injection). Our data showed that rosiglitazone significantly inhibited D-GaIN/LPS-induced hepatotoxicity in a dose-dependent manner, as indicated by both diagnostic indicators of liver damage (serum aminotransferase activities) and histopathological analysis. Western blot analysis showed that rosiglitazone significantly decreased protein expression levels of COX-2 and production of pro-inflammatory markers, including TNF-α and IL-6, in D-GaIN/LPS-treated rat liver. The results indicated that the inhibition of D-GaIN/LPS-induced inflammation by rosiglitazone can be attributed, at least partially, to its capacity to regulate the the immunoregulatory transcription factor nuclear factor kappa B (NF-κB) signaling pathway.

Bedside-to-Bench Translational Research for Chronic Heart Failure: Creating an Agenda for Clients Who Do Not Meet Trial Enrollment Criteria

Congestive heart failure (CHF) is a chronic condition usually without cure. Significant developments, particularly those addressing pathophysiology, mainly started at the bench. This approach has seen many clinical observations initially explored at the bench, subsequently being trialed at the bedside, and eventually translated into clinical practice. This evidence, however, has several limitations, importantly the generalizability or external validity. We now acknowledge that clinical management of CHF is more complicated than merely translating bench-to-bedside evidence in a linear fashion. This review aims to help explore this evolving area from an Australian perspective. We describe the continuation of research once core evidence is established and describe how clinician-scientist collaboration with a bedside-to-bench view can help enhance evidence translation and generalizability. We describe why an extension of the available evidence or generating new evidence is occasionally needed to address the increasingly diverse cohort of patients. Finally, we explore some of the tools used by basic scientists and clinicians to develop evidence and describe the ones we feel may be most beneficial.

Cardiovascular Risk in Diabetes Mellitus: Complication of the Disease or of Antihyperglycemic Medications

Cardiovascular disease is the principal complication and the leading cause of death for patients with diabetes (DM). The efficacy of antihyperglycemic treatments on cardiovascular disease risk remains uncertain. Cardiovascular risk factors are affected by antihyperglycemic medications, as are many intermediate markers of cardiovascular disease. Here we summarize the evidence assessing the cardiovascular effects of antihyperglycemic medications with regard to risk factors, intermediate markers of disease, and clinical outcomes.

G Protein-coupled Receptor 40 (GPR40) and Peroxisome Proliferator-activated Receptor γ (PPARγ): AN INTEGRATED TWO-RECEPTOR SIGNALING PATHWAY

Peroxisome proliferator-activated receptor γ (PPARγ) ligands have been widely used to treat type 2 diabetes mellitus. However, knowledge of PPARγ signaling remains incomplete. In addition to PPARγ, these drugs also activate G protein-coupled receptor 40 (GPR40), a Gαq-coupled free fatty acid receptor linked to MAPK networks and glucose homeostasis. Notably, p38 MAPK activation has been implicated in PPARγ signaling. Here, rosiglitazone (RGZ) activation of GPR40 and p38 MAPK was found to boost PPARγ-induced gene transcription in human endothelium. Inhibition or knockdown of p38 MAPK or expression of a dominant negative (DN) p38 MAPK mutant blunted RGZ-induced PPARγ DNA binding and reporter activity in EA.hy926 human endothelial cells. GPR40 inhibition or knockdown, or expression of a DN-Gαq mutant likewise blocked activation of both p38 MAPK and PPARγ reporters. Importantly, RGZ induction of PPARγ target genes in primary human pulmonary artery endothelial cells (PAECs) was suppressed by knockdown of either p38 MAPK or GPR40. GPR40/PPARγ signal transduction was dependent on p38 MAPK activation and induction of PPARγ co-activator-1 (PGC1α). Silencing of p38 MAPK or GPR40 abolished the ability of RGZ to induce phosphorylation and expression of PGC1α in PAECs. Knockdown of PGC1α, its essential activator SIRT1, or its binding partner/co-activator EP300 inhibited RGZ induction of PPARγ-regulated genes in PAECs. RGZ/GPR40/p38 MAPK signaling also led to EP300 phosphorylation, an event that enhances PPARγ target gene transcription. Thus, GPR40 and PPARγ can function as an integrated two-receptor signal transduction pathway, a finding with implications for rational drug development.

The Current Drug Treatment Landscape for Diabetes and Perspectives for the Future

The escalating global epidemic of type 2 diabetes mellitus has focused attention on the devastating consequences of protracted hyperglycemia. Early and effective intervention to control blood glucose is a fundamental principle of treatment guidelines, requiring assiduous use of current therapies. However, many patients do not achieve or maintain glycemic targets, emphasizing the need for further therapies. This narrative review assesses the available medicinal options to address hyperglycemia and the opportunities to develop novel agents.

Comparative analysis of therapeutic efficiency and costs (experience in Bulgaria) of oral antidiabetic therapies based on glitazones and gliptins

Type 2 diabetes mellitus is a serious, chronic, progressive and widespread disease. Metformin is the most commonly prescribed initial therapy, but combination with other antidiabetic agents usually becomes necessary due to the progression of the disease. Pioglitazone is recommended as a second-line therapy because of its strong antihyperglycemic effect and its ability to reduce insulin resistance. Treatment with pioglitazone is associated with a significantly lower risk of cardiovascular complications and hypoglycemia, while simultaneously improving the lipid profile and the symptomatic and histological changes in the liver. Gliptins (sitagliptin and vildagliptin) are a new class of oral antidiabetic drugs which reduce glycated hemoglobin by a different mechanism. Although the efficacy of sitagliptin and vildagliptin is close to that of pioglitazone, the lack of long-term safety data and the higher price question their predominant use. The objective of this review is to highlight the advantages of mono- and combination therapy with pioglitazone in comparison with gliptins and to underline the inconsistencies in the medicinal and reimbursement policy in Bulgaria.

Metabolic dysfunction in diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is defined as cardiac disease independent of vascular complications during diabetes. The number of new cases of DCM is rising at epidemic rates in proportion to newly diagnosed cases of diabetes mellitus (DM) throughout the world. DCM is a heart failure syndrome found in diabetic patients that is characterized by left ventricular hypertrophy and reduced diastolic function, with or without concurrent systolic dysfunction, occurring in the absence of hypertension and coronary artery disease. DCM and other diabetic complications are caused in part by elevations in blood glucose and lipids, characteristic of DM. Although there are pathological consequences to hyperglycemia and hyperlipidemia, the combination of the two metabolic abnormalities potentiates the severity of diabetic complications. A natural competition exists between glucose and fatty acid metabolism in the heart that is regulated by allosteric and feedback control and transcriptional modulation of key limiting enzymes. Inhibition of these glycolytic enzymes not only controls flux of substrate through the glycolytic pathway, but also leads to the diversion of glycolytic intermediate substrate through pathological pathways, which mediate the onset of diabetic complications. The present review describes the limiting steps involved in the development of these pathological pathways and the factors involved in the regulation of these limiting steps. Additionally, therapeutic options with demonstrated or postulated effects on DCM are described.

Update on Safety Issues Related to Antihyperglycemic Therapy

The American Diabetes Association emphasizes the importance of individualized patient care in the management of diabetes. One of the important considerations in choosing an antihyperglycemic agent is its side-effect and safety profile. This article reviews the common and clinically significant side effects of each class of agents, including ways to prevent and overcome their occurrence.

Diabetic cardiomyopathy: mechanisms and new treatment strategies targeting antioxidant signaling pathways

Cardiovascular disease is the primary cause of morbidity and mortality among the diabetic population. Both experimental and clinical evidence suggest that diabetic subjects are predisposed to a distinct cardiomyopathy, independent of concomitant macro- and microvascular disorders. 'Diabetic cardiomyopathy' is characterized by early impairments in diastolic function, accompanied by the development of cardiomyocyte hypertrophy, myocardial fibrosis and cardiomyocyte apoptosis. The pathophysiology underlying diabetes-induced cardiac damage is complex and multifactorial, with elevated oxidative stress as a key contributor. We now review the current evidence of molecular disturbances present in the diabetic heart, and their role in the development of diabetes-induced impairments in myocardial function and structure. Our focus incorporates both the contribution of increased reactive oxygen species production and reduced antioxidant defenses to diabetic cardiomyopathy, together with modulation of protein signaling pathways and the emerging role of protein O-GlcNAcylation and miRNA dysregulation in the progression of diabetic heart disease. Lastly, we discuss both conventional and novel therapeutic approaches for the treatment of left ventricular dysfunction in diabetic patients, from inhibition of the renin-angiotensin-aldosterone-system, through recent evidence favoring supplementation of endogenous antioxidants for the treatment of diabetic cardiomyopathy. Novel therapeutic strategies, such as gene therapy targeting the phosphoinositide 3-kinase PI3K(p110α) signaling pathway, and miRNA dysregulation, are also reviewed. Targeting redox stress and protective protein signaling pathways may represent a future strategy for combating the ever-increasing incidence of heart failure in the diabetic population.

The role of nateglinide and repaglinide, derivatives of meglitinide, in the treatment of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is one of the most common chronic diseases worldwide, presenting a great challenge to the public health systems due to high morbidity and mortality, because of frequent micro-/macro-vascular complications. Many treatment options are now available, with different efficacy as well as mechanisms of action to improve deranged glucose metabolism. We review some of the available data on derivatives of meglitinide, namely nateglinide and repaglinide. These two compounds increase insulin secretion by a mechanism similar to the one of sulfonylureas, but with a shorter half-life. Nateglinide and repaglinide, derivatives of meglitinides, have characteristic pharmacodynamic and pharmacokinetic properties that, together with their proposed mechanism of action, make them useful for type 2 diabetes mellitus, especially when used in combination therapy.

Effects of pioglitazone on cardiac ion currents and action potential morphology in canine ventricular myocytes

Despite its widespread therapeutical use there is little information on the cellular cardiac effects of the antidiabetic drug pioglitazone in larger mammals. In the present study, therefore, the concentration-dependent effects of pioglitazone on ion currents and action potential configuration were studied in isolated canine ventricular myocytes using standard microelectrode, conventional whole cell patch clamp, and action potential voltage clamp techniques. Pioglitazone decreased the maximum velocity of depolarization and the amplitude of phase-1 repolarization at concentrations ≥3 μM. Action potentials were shortened by pioglitazone at concentrations ≥10 μM, which effect was accompanied with significant reduction of beat-to-beat variability of action potential duration. Several transmembrane ion currents, including the transient outward K(+) current (Ito), the L-type Ca(2+) current (ICa), the rapid and slow components of the delayed rectifier K(+) current (IKr and IKs, respectively), and the inward rectifier K(+) current (IK1) were inhibited by pioglitazone under conventional voltage clamp conditions. Ito was blocked significantly at concentrations ≥3 μM, ICa, IKr, IKs at concentrations ≥10 μM, while IK1 at concentrations ≥30 μM. Suppression of Ito, ICa, IKr, and IK1 has been confirmed also under action potential voltage clamp conditions. ATP-sensitive K(+) current, when activated by lemakalim, was effectively blocked by pioglitazone. Accordingly, action potentials were prolonged by 10 μM pioglitazone when the drug was applied in the presence of lemakalim. All these effects developed rapidly and were readily reversible upon washout. In conclusion, pioglitazone seems to be a harmless agent at usual therapeutic concentrations.

Discordant effects of rosiglitazone on novel inflammatory biomarkers

BACKGROUND

Although rosiglitazone favorably affects myriad intermediate markers of atherosclerosis, it appears to increase myocardial infarction (MI) risk. We analyzed the effects of rosiglitazone on a panel of 8 novel circulating biomarkers, 4 of which are independently associated with atherosclerosis: lymphotoxin β receptor, peptidoglycan recognition protein 1, chemokine ligand 23, and soluble receptor for advanced glycation end products (sRAGE) as well as on high-sensitivity C-reactive protein (hs-CRP).

METHODS

Blood samples were analyzed at baseline and after 6 months of study treatment from subjects with type 2 diabetes with or at high risk for coronary artery disease in a randomized trial comparing rosiglitazone versus placebo.

RESULTS

Data from 111 subjects (rosiglitazone 55, placebo 56) were analyzed. Mean age was 56 years, 41% were women, and 66% were nonwhite. Compared with baseline values, rosiglitazone adversely affected levels of lymphotoxin β receptor (1.7 vs 2.4 ng/mL, P = .002), peptidoglycan recognition protein 1 (29.0 vs 30.1 ng/mL, P = .01), and chemokine ligand 23 (0.76 vs 0.84 ng/mL, P = .02) and favorably affected levels of sRAGE (inversely associated with atherosclerosis, 1.1 vs 1.4 ng/mL, P = .003) and hs-CRP (0.42 vs 0.31 ng/mL, P = .02); no changes were observed with rosiglitazone in the other biomarkers. In the placebo group, change was observed only for sRAGE (1.0 vs 1.1 ng/mL, P = .046).

CONCLUSION

Rosiglitazone adversely affected 3 novel biomarkers and favorably affected a fourth previously associated with atherosclerosis while improving hs-CRP, as has previously been shown. Whether these complex effects on circulating inflammatory biomarkers contribute to the signal of increased MI risk with rosiglitazone and whether pioglitazone has similar effects warrant further investigation.

PPAR agonists for the treatment of cardiovascular disease in patients with diabetes

Diabetes is a complex disease defined by hyperglycaemia; however, strong associations with abdominal obesity, hypertension and dyslipidaemia contribute to the high risk of cardiovascular disease. Although aggressive glycaemic control reduces microvascular complications, the evidence for macrovascular complications is less certain. The theoretical benefits of the mode of action of peroxisome proliferator-activated receptor (PPAR) agonists are clear. In clinical practice, PPAR-α agonists such as fibrates improve dyslipidaemia, while PPAR-γ agonists such as thiazolidinediones improve insulin resistance and diabetes control. However, although these agents are traditionally classed according to their target, they have different and sometimes conflicting clinical benefit and adverse event profiles. It is speculated that this is because of differing properties and specificities for the PPAR receptors (each of which targets specific genes). This is most obvious in the impact on cardiovascular outcomes--in clinical trials pioglitazone appeared to reduce cardiovascular events, whereas rosiglitazone potentially increased the risk of myocardial infarction. The development of a dual PPAR-α/γ agonist may prove beneficial in effectively managing glycaemic control and improving dyslipidaemia in patients with type 2 diabetes. Yet, development of agents such as muraglitazar and tesaglitazar has been hindered by various serious adverse events. Aleglitazar, a balanced dual PPAR-α/γ agonist, is currently the most advanced in clinical development and has shown promising results in phase II clinical trials with beneficial effects on glucose and lipid variables. A phase III study, ALECARDIO, is ongoing and will establish whether improvements in laboratory test profiles translate into an improvement in cardiovascular outcomes.

Diabetes Mellitus and Trends in Hospital Survival After Myocardial Infarction, 1994 to 2006

Background—

Patients with diabetes mellitus (DM) are at high risk for mortality after myocardial infarction (MI). Despite an overall trend of reduced mortality after MI, the mortality gap between MI patients with and without DM did not decrease over time in previous analyses. We assessed recent trends in hospital mortality for patients with MI according to DM status.

Methods and Results—

We analyzed data from the National Registry of Myocardial Infarction, a contemporary registry of MI patients treated in 1964 hospitals, representing approximately one fourth of all US acute care hospitals. The study comprised 1734431 MI patients enrolled from 1994 to 2006, including 502315 (29%) with DM. Crude hospital mortality decreased in all patients between 1994 and 2006 but remained higher in patients with DM compared with those without DM throughout the study. The absolute difference in mortality between patients with and without DM significantly narrowed over time, from 15.6% versus 11.5% in 1994 to 8.0% versus 6.8% in 2006 ( P <0.001 for DM × time interaction). The adjusted odds ratio for mortality associated with DM declined from 1.24 (95% confidence interval, 1.16–1.32) in 1994 to 1.08 (95% confidence interval, 0.99–1.19) in 2006 ( P <0.001 for trend). The largest improvement in hospital mortality was observed in diabetic women (17.9% in 1994 versus 8.4% in 2006; P <0.001).

Conclusions—

The hospital mortality gap between MI patients with and without DM narrowed significantly from 1994 to 2006, with the greatest improvement observed in women with DM.

5-Arylidenethioxothiazolidinones as inhibitors of tyrosyl-DNA phosphodiesterase I

Tyrosyl-DNA phosphodiesterase I (Tdp1) is a cellular enzyme that repairs the irreversible topoisomerase I (Top1)-DNA complexes and confers chemotherapeutic resistance to Top1 inhibitors. Inhibiting Tdp1 provides an attractive approach to potentiating clinically used Top1 inhibitors. However, despite recent efforts in studying Tdp1 as a therapeutic target, its inhibition remains poorly understood and largely underexplored. We describe herein the discovery of arylidene thioxothiazolidinone as a scaffold for potent Tdp1 inhibitors based on an initial tyrphostin lead compound 8. Through structure-activity relationship (SAR) studies we demonstrated that arylidene thioxothiazolidinones inhibit Tdp1 and identified compound 50 as a submicromolar inhibitor of Tdp1 (IC₅₀ = 0.87 μM). Molecular modeling provided insight into key interactions essential for observed activities. Some derivatives were also active against endogenous Tdp1 in whole cell extracts. These findings contribute to advancing the understanding on Tdp1 inhibition.

Effects of dapagliflozin, an SGLT2 inhibitor, on HbA(1c), body weight, and hypoglycemia risk in patients with type 2 diabetes inadequately controlled on pioglitazone monotherapy

OBJECTIVE

To examine the safety and efficacy of dapagliflozin, a sodium-glucose cotransporter-2 inhibitor, added on to pioglitazone in type 2 diabetes inadequately controlled on pioglitazone.

RESEARCH DESIGN AND METHODS

Treatment-naive patients or those receiving metformin, sulfonylurea, or thiazolidinedione entered a 10-week pioglitazone dose-optimization period with only pioglitazone. They were then randomized, along with patients previously receiving pioglitazone ≥30 mg, to 48 weeks of double-blind dapagliflozin 5 (n = 141) or 10 mg (n = 140) or placebo (n = 139) every day plus open-label pioglitazone. The primary objective compared HbA(1c) change from baseline with dapagliflozin plus pioglitazone versus placebo plus pioglitazone at week 24. Primary analysis was based on ANCOVA model using last observation carried forward; all remaining analyses used repeated-measures analysis.

RESULTS

At week 24, the mean reduction from baseline in HbA(1c) was -0.42% for placebo versus -0.82 and -0.97% for dapagliflozin 5 and 10 mg groups, respectively (P = 0.0007 and P < 0.0001 versus placebo). Patients receiving pioglitazone alone had greater weight gain (3 kg) than those receiving dapagliflozin plus pioglitazone (0.7-1.4 kg) at week 48. Through 48 weeks: hypoglycemia was rare; more events suggestive of genital infection were reported with dapagliflozin (8.6-9.2%) than placebo (2.9%); events suggestive of urinary tract infection showed no clear drug effect (5.0-8.5% for dapagliflozin and 7.9% for placebo); dapagliflozin plus pioglitazone groups had less edema (2.1-4.3%) compared with placebo plus pioglitazone (6.5%); and congestive heart failure and fractures were rare.

CONCLUSIONS

In patients with type 2 diabetes inadequately controlled on pioglitazone, the addition of dapagliflozin further reduced HbA(1c) levels and mitigated the pioglitazone-related weight gain without increasing hypoglycemia risk.

The effects of rosiglitazone on myocardial triglyceride content in patients with type 2 diabetes: a randomised, placebo-controlled trial

This was a nested sub-study of a randomised placebo-controlled trial of the effect of 6 months of treatment with rosiglitazone added to existing therapy on myocardial triglyceride (mTG) content in patients with type 2 diabetes (T2D) and prevalent cardiovascular disease (CVD) or at least one additional risk factor. The primary endpoint, mTG content, was measured with cardiac (1)H-magnetic resonance spectroscopy. Of the 99 randomised participants selected for the imaging sub-study, 49 (48%) had complete and interpretable spectroscopy data (age = 58 years, duration of T2D = 9.5 years; 57% women and 69% non-white). There was no significant change in mTG in either group (-0.1 ± 0.6% and -0.05 ± 0.8% respectively) and the changes in mTG were not associated with changes in left ventricular structure or function. Compared with placebo, treatment with rosiglitazone for 6 months had no discernible effect on mTG or left ventricular function in this population with long-standing diabetes and CVD.

Can the electrophysiological action of rosiglitazone explain its cardiac side effects?

Recent large clinical trials found an association between the antidiabetic drug rosiglitazone therapy and increased risk of cardiovascular adverse events. The aim of this report is to elucidate the cardiac electrophysiological properties of rosiglitazone (R) on isolated rat and murine ventricular papillary muscle cells and canine ventricular myocytes using conventional microelectrode, whole cell voltage clamp, and action potential (AP) voltage clamp techniques. In histidine-decarboxylase knockout mice as well as in their wild types R (1-30 µM) shortened AP duration at 90% level of repolarization (APD(90)) and increased the AP amplitude (APA) in a concentration-dependent manner. In rat ventricular papillary muscle cells R (1-30 µM) caused a significant reduction of APA and maximum velocity of depolarization (V(max)) which was accompanied by lengthening of APD(90). In single canine ventricular myocytes at concentrations ≥10 µM R decreased the amplitude of phase-1 repolarization, the plateau potential and reduced V(max). R suppressed several ion currents in a concentration-dependent manner under voltage clamp conditions. The EC(50) value for this inhibition was 25.2±2.7 µM for the transient outward K(+ ) current (I(to)), 72.3±9.3 µM for the rapid delayed rectifier K(+ ) current (I(Kr)), and 82.5±9.4 µM for the L-type Ca(2+ ) current (I(Ca)) with Hill coefficients close to unity. The inward rectifier K(+ ) current (I(K1)) was not affected by R up to concentrations of 100 µM. Suppression of I(to), I(Kr), and I(Ca) has been confirmed under action potential voltage clamp conditions as well. The observed alterations in the AP morphology and densities of ion currents may predict serious proarrhythmic risk in case of intoxication with R as a consequence of overdose or decreased elimination of the drug, particularly in patients having multiple cardiovascular risk factors, such as elderly diabetic patients.

Cardiac ion channel modulation by the hypoglycaemic agent rosiglitazone

The hypoglycaemic thiazolidinedione rosiglitazone is used clinically in the treatment of type 2 diabetes. However, in 2010, information relating to rosiglitazone-associated increased cardiovascular risk led the European Medicines Agency to recommend suspension of marketing authorizations for rosiglitazone-containing anti-diabetes drugs, while the US Food and Drug Administration recommended significant restriction on the agent's use. Two timely studies in this issue of the British Journal of Phrarmacology provide new information regarding modification of cardiac cellular electrophysiology by rosiglitazone. Szentandrássy et al. demonstrate canine ventricular action potential modification and concentration-dependent suppression of L-type Ca current and of transient outward and rapid delayed rectifier K currents. Jeong et al. demonstrate concentration-dependent inhibition of recombinant K(v) 4.3 channels, providing mechanistic insight into the likely molecular basis of transient outward K current inhibition by the compound. Further studies using diabetic models would be of value to determine whether, in a diabetic setting, rosiglitazone modification of these channels could affect the risk of arrhythmia at clinically relevant drug concentrations.

Diabetic cardiomyopathy

Individuals with diabetes are at a significantly greater risk of developing cardioymyopathy and heart failure despite adjusting for concomitant risks such as coronary artery disease or hypertension. This has led to the increased recognition of a distinct disease process termed as "diabetic cardiomyopathy." In this article, we perform an extensive review of the pathogenesis and treatment of this disease. From a clinical perspective, physicians should be aware of this entity, and early screening should be considered because physical evidence of early diabetic cardiomyopathy could be difficult to detect. Early detection of the disease should prompt intensification of glycemic control, concomitant risk factors, use of pharmacologic agents such as β-blockers and renin-angiotensin-aldosterone system antagosists. From a research perspective, more studies on myocardial tissue from diabetic patients are needed. Clinical trials to evaluate the development of diabetic cardiomyopathy and fibrosis in early stages of the disease, as well as clinical trials of pharmacologic intervention in patients specifically with diabetic cardiomyopathy, need to be conducted.

Effects of rosiglitazone on the configuration of action potentials and ion currents in canine ventricular cells

BACKGROUND AND PURPOSE

In spite of its widespread clinical application, there is little information on the cellular cardiac effects of the antidiabetic drug rosiglitazone in larger experimental animals. In the present study therefore concentration-dependent effects of rosiglitazone on action potential morphology and the underlying ion currents were studied in dog hearts.

EXPERIMENTAL APPROACH

Standard microelectrode techniques, conventional whole cell patch clamp and action potential voltage clamp techniques were applied in enzymatically dispersed ventricular cells from dog hearts.

KEY RESULTS

At concentrations ≥10 µM rosiglitazone decreased the amplitude of phase-1 repolarization, reduced the maximum velocity of depolarization and caused depression of the plateau potential. These effects developed rapidly and were readily reversible upon washout. Rosiglitazone suppressed several transmembrane ion currents, concentration-dependently, under conventional voltage clamp conditions and altered their kinetic properties. The EC(50) value for this inhibition was 25.2 ± 2.7 µM for the transient outward K(+) current (I(to)), 72.3 ± 9.3 µM for the rapid delayed rectifier K(+) current (I(Kr)) and 82.5 ± 9.4 µM for the L-type Ca(2+) current (I(Ca) ) with Hill coefficients close to unity. The inward rectifier K(+) current (I(K1)) was not affected by rosiglitazone up to concentrations of 100 µM. Suppression of I(to), I(Kr), and I(Ca) was confirmed also under action potential voltage clamp conditions.

CONCLUSIONS AND IMPLICATIONS

Alterations in the densities and kinetic properties of ion currents may carry serious pro-arrhythmic risk in case of overdose with rosiglitazone, especially in patients having multiple cardiovascular risk factors, like elderly diabetic patients.

Diabetes mellitus: new drugs for a new epidemic

The prevalence of diabetes mellitus (DM) is increasing rapidly in the 21st century as a result of obesity, an ageing population, lack of exercise, and increased migration of susceptible patients. This costly and chronic disease has been likened recently to the 'Black Death' of the 14th century. Type 2 DM is the more common form and the primary aim of management is to delay the micro- and macrovascular complications by achieving good glycaemic control. This involves changes in lifestyle, such as weight loss and exercise, and drug therapy. Increased knowledge of the pathophysiology of diabetes has contributed to the development of novel treatments: glucagon-like peptide-1 (GLP-1) mimetics, dipeptidyl peptidase-4 (DPP-4) inhibitors, thiazolidinediones (TZDs), and insulin analogues. GLP-1 agonists mimic the effect of this incretin, whereas DPP-4 inhibitors prevent the inactivation of the endogenously released hormone. Both agents offer an effective alternative to the currently available hypoglycaemic drugs but further evaluation is needed to confirm their safety and clinical role. The past decade has seen the rise and fall in the use of the TZDs (glitazones), such that the only glitazone recommended is pioglitazone as a third-line treatment. The association between the use of rosiglitazone and adverse cardiac outcomes is still disputed by some authorities. The advent of new insulin analogues, fast-acting, and basal release formulations, has enabled the adoption of a basal-bolus regimen for the management of blood glucose. This regimen aims to provide a continuous, low basal insulin release between meals with bolus fast-acting insulin to limit hyperglycaemia after meals. Insulin therapy is increasingly used in type 2 DM to enhance glycaemic control. Recently, it has been suggested that the use of the basal-release insulins, particularly insulin glargine may be associated with an increased risk of cancer. Although attention is focused increasingly on newer agents in the treatment of diabetes, metformin and the sulphonylureas are still used in many patients. Metformin, in particular, remains of great value and may have novel anti-cancer properties.

Assessment of cardiac structure and function in patients without and with peripheral oedema during rosiglitazone treatment

BACKGROUND

Thiazolidinediones cause peripheral oedema, the aetiology of which remains poorly understood.

METHODS

In a sub-study of a 6-month trial comparing rosiglitazone (Rsg) versus placebo, we compared those with versus without oedema among the 74 subjects treated with Rsg with respect to peak oxygen consumption indexed to fat-free mass (VO(2peak-FFM) ), cardiac MRI and markers of plasma volume expansion.

RESULTS

Almost half (49%) of the Rsg-treated patients developed oedema. Baseline VO(2peak-FFM) was not different between those with versus without oedema (25.8 versus 28.2 ml/kg/min; p = 0.22) and declined 5% in the oedema group (Δ -1.3 ml/min/kg; p = 0.005) with no change in those without oedema. Stroke volume increased in both groups (Δ 8.7 and 8.8 ml; p < 0.001 for each); end-diastolic volume increased only in those with oedema (+13.1 ml; p = 0.001). No other cardiac function changes were observed. In both groups, weight increased (3.6 and 2.2 kg) and haematocrit decreased (-3.2% and -2.1%; p < 0.001 for each). In those with oedema, albumin decreased (-0.2 g/dl) and brain natriuretic peptide increased (11.9 pg/ml; p < 0.03 for each).

CONCLUSIONS

Oedema was associated with a small decline in VO(2peak FFM), no adverse effects on cardiac function, and changes in selected measures suggesting that volume expansion underpins Rsg oedema.

Pleiotropic effects of glitazones: a double edge sword?

Glitazones (thiazolidinediones) are drugs used for diabetes mellitus type 2. By binding to peroxisome proliferator-activated receptor γ (PPARγ) they modulate transcription of genes of carbohydrate and lipid metabolism. Through PPARγ stimulation, however, glitazones also affect other genes, encompassing inflammation, cell growth and differentiation, angiogenesis, which broads their therapeutic potential. The gene expression profile induced by each glitazone shows peculiarities, which may affect its benefit/risk balance; indeed, troglitazone and rosiglitazone have been associated with liver failure and coronary disease, respectively; whether or not these severe adverse effects are solely related to PPARγ remains yet unclear, since glitazones exert also PPARγ-independent effects. Glitazone chemistry serves as scaffold for synthesizing new compounds with PPARγ-independent pharmacological properties and we report here a preliminary observation of inhibition of vasoconstriction by troglitazone in isolated vessels, an effect that appears fast, reversible, and PPARγ-independent. Pleiotropic effects of glitazones need specific attention in terms of drug safety, but also provide basis for drug development and novel experimental therapeutics.

Targeting type 2 diabetes

The evolving concept of how nutrient excess and inflammation modulate metabolism provides new opportunities for strategies to correct the detrimental health consequences of obesity. In this review, we focus on the complex interplay among lipid overload, immune response, proinflammatory pathways and organelle dysfunction through which excess adiposity might lead to type 2 diabetes. We then consider evidence linking dysregulated CNS circuits to insulin resistance and results on nutrient-sensing pathways emerging from studies with calorie restriction. Subsequently, recent recommendations for the management of type 2 diabetes are discussed with emphasis on prevailing current therapeutic classes of biguanides, thiazolidinediones and incretin-based approaches.