Reductions in biomarkers of cardiovascular risk in type 2 diabetes with rosiglitazone added to metformin compared with dose escalation of metformin: an EMPIRE trial sub-study

Metformin Directly Binds to MMP-9 to Improve Plaque Stability

Vulnerable atherosclerotic plaque rupture is the principal mechanism that accounts for myocardial infarction and stroke. High matrix metalloproteinase-9 (MMP-9) expression and activity have been proven to lead to plaque instability. Metformin, a first-line treatment for type 2 diabetes, is beneficial to plaque vulnerability. However, the mechanism underlying its anti-atherogenic effect remains unclear. Molecular docking and surface plasmon resonance experiments showed that metformin directly interacts with MMP-9, and incubated MMP-9 overexpressing HEK293A cells with metformin (1 μmol·L^-1) significantly attenuates MMP-9's activity using zymography and MMP activity assays. Moreover, metformin treatment drives MMP-9 degradation. Next, we constructed a carotid artery atherosclerotic plaque model and administered consecutive 14-day metformin (200 mg·kg^-1·d^-1) treatment by intragastric gavage. Immunofluorescence staining of the right carotid common artery and serum MMP activity assay results showed that metformin treatment decreased local plaque MMP-9 protein level and circulating MMP-9 activity, respectively. Histochemical staining revealed that after metformin treatment, the collagen content in plaque was significantly preserved, and the plaque vulnerability index decreased. These findings suggested that metformin improved atherosclerotic plaque stability by directly binding to MMP-9 and driving its degradation.

Association of dietary intake, medication and anthropometric indices with serum levels of advanced glycation end products, caspase-3, and matrix metalloproteinase-9 in diabetic patients

Background and objective

Increased serum levels of advanced glycation end products (AGEs), caspase-3 (Cas-3) and matrix metalloproteinase-9 (MMP-9) have been reported in diabetic patients. This study aimed to evaluate association of anthropometric, dietary, and therapeutic factors with serum levels of methylglyoxal (MGO), carboxymethyl lysine (CML), pentosidine (Pen), Cas-3, and MMP-9 in diabetic patients.

Methods

The current study included 36 diabetic subjects. Dietary intake of the participants was assessed using three-day 24-h recall survey and anthropometric indices were measured. Demographic factors and medication intake of every subject were obtained. Serum levels of CML, MGO, Pen, MMP-9, and Cas-3 were measured using ELISA method.

Results

Gliclazide consumption was positively correlated with MMP-9 and Cas-3, but not AGEs levels. Females had higher MGO level compared with males. Further, CML levels were negatively correlated with BMI and WHR. Dietary protein intake was positively correlated with MMP-9, Cas-3, and MGO levels. As well as dietary energy and fat intake had significant positive relationship with serum Cas-3 concentration.

Conclusion

It is concluded that anthropometric characteristics, dietary intake, and therapeutic medications are possible factors that may determine the circulating levels of AGEs, MMP-9, and Cas-3 in patients with diabetes.

The extra-pancreatic effects of GLP-1 receptor agonists: a focus on the cardiovascular, gastrointestinal and central nervous systems

The glucagon-like peptide-1 receptor agonists (GLP-1RAs) exenatide, liraglutide and lixisenatide have been shown to improve glycaemic control and beta-cell function with a low risk of hypoglycaemia in people with type 2 diabetes. GLP-1 receptors are also expressed in extra-pancreatic tissues and trial data suggest that GLP-1RAs also have effects beyond their glycaemic actions. Preclinical studies using native GLP-1 or GLP-1RAs provide substantial evidence for cardioprotective effects, while clinical trial data have shown beneficial actions on hypertension and dyslipidaemia in people with type 2 diabetes. Significant weight loss has been reported with GLP-1RAs in both people with type 2 diabetes and obese people without diabetes. GLP-1RAs also slow down gastric emptying, but preclinical data suggest that the main mechanism behind GLP-1RA-induced weight loss is more likely to involve their effects on appetite signalling in the brain. GLP-1RAs have also been shown to exert a neuroprotective role in rodent models of stroke, Alzheimer's disease and Parkinson's disease. These extra-pancreatic effects of GLP-1RAs could provide multi-factorial benefits to people with type 2 diabetes. Potential adverse effects of GLP-1RA treatment are usually manageable but may include gastrointestinal effects, increased heart rate and renal injury. While extensive further research is still required, early data suggest that GLP-1RAs may also have the potential to favourably impact cardiovascular disease, obesity or neurological disorders in people without diabetes in the future.

Effect of pioglitazone versus metformin on cardiovascular risk markers in type 2 diabetes

INTRODUCTION

Besides its critical role in metabolic homeostasis, peroxisome proliferator-activated receptor (PPAR)-γ modulates several cellular responses involved in atherothrombosis. This multicenter, double-blind, randomized study investigated the effects of two oral hypoglycemic agents on markers of inflammation, platelet activation, thrombogenesis, and oxidative stress in patients with type 2 diabetes.

METHODS AND RESULTS

The primary objective of this study was to evaluate the effect on C-reactive protein (CRP) after a 16-week treatment period with either pioglitazone or metformin. Additionally, markers of vascular inflammatory response, platelet activation, thrombogenesis, oxidative stress, glucose, and lipid metabolism, as well as liver function, were measured. In total, 50 patients completed the study. Pioglitazone-treated patients were found to have statistically significantly larger decreases in mean CRP levels (-0.4 mg/dL) compared to those treated with metformin (-0.2 mg/dL) (P=0.04), as well as greater reductions in levels of mean fasting plasma glucose (-27 vs. -9 mg/dL; P=0.01), serum insulin (-2 vs. -1.9 mU/L; P=0.014), homeostatic model assessment (HOMA) (-1.2 vs. -0.9; P=0.015), and E-selectin (-12.4 vs. +3.4 μg/mL; P=0.01). Mean glycated hemoglobin (HbA1c) levels decreased in both treatment groups from baseline to week 16 (-0.4% in the pioglitazone group, -0.2% in the metformin group; P=0.36). Pioglitazone treatment was also found to be associated with a statistically significant increase in total cholesterol levels (+10 mg/dL in the pioglitazone arm, -3 mg/dL in the metformin arm; P=0.05) and a decrease in liver enzyme levels.

CONCLUSIONS

The favorable changes in markers of systemic and vascular inflammatory response with pioglitazone suggest that it may positively influence the atherothrombotic process in type 2 diabetes.

Matrix metalloproteinases and peripheral arterial disease

Matrix metalloproteinases (MMPs), a family of enzymes that degrade extracellular matrix, are emerging as important modulators of atherothrombosis. MMPs are produced by inflammatory cells; some of them are also released by activated platelets and play a crucial role in the remodeling processes, leading to atherosclerotic plaque formation, plaque rupture, arterial aneurysm development, and critical limb ischemia. Independent from their matrix degrading activity, MMPs also regulate some cell functions relevant to atherothrombosis, such as platelet activation, neutrophil activation, and vascular reactivity. Plasma levels of some MMPs are increasingly being recognized as a biomarker of atherosclerosis and cardiovascular risk. In peripheral arterial disease, MMPs have been shown to be involved in angiogenesis, arteriogenesis, and the development of arterial calcifications. Increased plasma levels of some MMPs (MMP-2, MMP-9) have been correlated with PAD development and severity. Single nucleotide polymorphisms of the genes encoding for some MMPs have also been associated with the risk of developing peripheral arterial disease and critical limb ischemia. Large prospective observational studies are needed to further demonstrate the role of MMPs in PAD. In perspective, pharmacologic targeting of the expression or activity of MMPs may represent a novel, attractive approach for the treatment of peripheral arterial disease.

Effect of rosiglitazone, metformin and medical nutrition treatment on arterial stiffness, serum MMP-9 and MCP-1 levels in drug naive type 2 diabetic patients

The aim of the study was to evaluate the long-term effect of rosiglitazone and metformin monotherapy with medical nutrition treatment (MNT) and of MNT alone on arterial stiffness, serum monocyte chemoattractant protein (MCP)-1 and matrix metalloproteinase (MMP)-9 in drug naive patients with type 2 diabetes mellitus. Fifty type 2 diabetic patients were randomized to receive rosiglitazone 4 mg/day (n=19) or metformin 850 mg/day (n=16) with MNT or MNT alone (n=15), for 52 weeks. Arterial stiffness was assessed by using large and small artery elasticity index (SAEI and LAEI, respectively). SAEI, LAEI, serum MCP-1 and MMP-9 levels were measured at baseline and following 52 weeks of treatment. SAEI was improved only in the rosiglitazone group, and the difference was still statistically significant when the three groups were compared (p=0.024). There were no differences in LAEI in inter- and intragroup comparisons at the end of the study. Serum MMP-9 levels were decreased in the metformin (-13.5+/-34.8%, p=0.02) and rosiglitazone (-27.2+/-51.0%, p=0.023) groups compared with baseline values, whereas no significant change was seen in serum MCP-1 levels. These results suggest that rosiglitazone monotherapy has favorable effects on arterial stiffness compared with metformin monotherapy independent of glycemic control.

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

BACKGROUND

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

AIMS

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

MATERIALS AND METHODS

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

RESULTS

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

DISCUSSION

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

CONCLUSION

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

The backbone of oral glucose-lowering therapy: time for a paradigm shift?

The complex array of metabolic abnormalities associated with type 2 diabetes provides a number of new targets for therapeutic intervention. Although the established oral glucose-lowering therapies, metformin and the sulfonylureas, continue to provide the backbone of therapeutic approaches, the thiazolidinediones (TZDs) also play an important role. Further, a new class of oral agents, the dipeptidyl peptidase-IV (DPP-IV) inhibitors, has recently become available with apparent utility in decreasing postprandial glucose excursions. This review examines how the TZDs and the DPP-IV inhibitors might integrate into current treatment strategies, considering not only glycemic goals, but also longer-term benefits such as durability of glycemic control, effect on metabolic parameters and cardiovascular outcomes. A practical approach is taken, reflecting potential clinical situations in which therapeutic intervention is required.

Redefining the role of thiazolidinediones in the management of type 2 diabetes

There is a need to evaluate oral glucose-lowering agents not only for their value in achieving glycemic control but also for their impact on cardiac risk factor modification. This article reviews the evidence base for the two thiazolinediones currently available, pioglitazone and rosiglitazone. These drugs exert their effects through actions affecting metabolic control, lipid profiles, and the vascular wall. They have been shown to be as efficacious in establishing glycemic control, in both monotherapy and combination therapy regimens, as more traditional oral agents, and may be able to sustain that control in the long term. Both thiazolidinediones have demonstrated favorable effects on markers of cardiovascular disease. Evidence from the large PROactive outcomes study suggests that pioglitazone may exert protective effects in patients with type 2 diabetes and macrovascular disease. Thiazolidinediones are generally well tolerated but they can cause weight gain, induce fluid retention, and may contribute to bone loss in postmenopausal women. The place of thiazolidinediones in the management of type 2 diabetes is well established. The potential for additional benefits in reducing macrovascular risk encourages further long-term study of these agents.

Effectiveness of the early addition of rosiglitazone to control hyperglycemia after unsuccessful submaximal sulphonylurea monotherapy: the Rosiglitazone Early Versus SULphonylurea Titration (RESULT) Study

Practice Pearl: This study demonstrates the effectiveness of the early addition of rosiglitazone to control hyperglycemia after unsuccessful submaximal sulphonylurea monotherapy. Original Article: Rosenstock J, Goldstein BJ, Vinik AI, et al. RESULT Study Group. Effect of early addition of rosiglitazone to sulphonylurea therapy in older type 2 diabetes patients (> 60 years): the Rosiglitazone Early vs. SULphonylurea Titration (RESULT) study.

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.

Hepatic dysfunction and insulin insensitivity in type 2 diabetes mellitus: a critical target for insulin-sensitizing agents

The liver plays an essential role in maintaining glucose homeostasis, which includes insulin-mediated processes such as hepatic glucose output (HGO) and uptake, as well as in clearance of insulin itself. In type 2 diabetes, the onset of hyperglycaemia [itself a potent inhibitor of hepatic glucose output (HGO)], alongside hyperinsulinaemia, indicates the presence of hepatic insulin insensitivity. Increased HGO is central to the onset of hyperglycaemia and highlights the need to target hepatic insulin insensitivity as a central component of glucose-lowering therapy. The mechanisms underlying the development of hepatic insulin insensitivity are not well understood, but may be influenced by factors such as fatty acid oversupply and altered adipocytokine release from dysfunctional adipose tissue and increased liver fat content. Furthermore, although the impact of insulin insensitivity as a marker of cardiovascular disease is well known, the specific role of hepatic insulin insensitivity is less clear. The pharmacological tools available to improve insulin sensitivity include the biguanides (metformin) and thiazolidinediones (rosiglitazone and pioglitazone). Data from a number of sources indicate that thiazolidinediones, in particular, can improve multiple aspects of hepatic dysfunction, including reducing HGO, insulin insensitivity and liver fat content, as well as improving other markers of liver function and the levels of mediators with potential involvement in hepatic function, including fatty acids and adipocytokines. The current review addresses this topic from the perspective of the role of the liver in maintaining glucose homeostasis, its key involvement in the pathogenesis of type 2 diabetes and the tools currently available to reduce hepatic insulin insensitivity.

C-reactive protein (CRP): more than just an innocent bystander?

This editorial discusses whether measuring C-reactive protein (CRP) levels can be used as a predictor of vascular risk. The agents that reduce CRP levels and the evidence for a possible causative role of CRP in the pathogenesis of coronary events and atherosclerosis are also considered. There is a need to further elucidate the role of CRP, as well as the clinical relevance, if any, of CRP-lowering agents.

Peroxisome proliferator-activated receptors and the metabolic syndrome

The prevalence of the metabolic syndrome is rapidly increasing. This syndrome is characterized by metabolic disturbances, such as abnormal lipid and carbohydrate metabolism and a low-grade inflammatory state. PPARs play an important role in these metabolic processes, which makes them effective targets for treatment and prevention of the metabolic syndrome. Synthetic PPAR agonists, such as fibrates and thiazolidinediones are already used to treat hyperlipidemia and diabetes mellitus, respectively. Besides synthetic ligands, dietary fatty acids and fatty acid derivatives can also bind to an activate PPARs. As demonstrated with ligand-binding assays, PPARs have a clear preference of binding polyunsaturated fatty acids. Monounsaturated fatty acids are also very effective in binding PPARs, whereas saturated fatty acids are poor PPAR binders. However, ligand binding does not necessarily mean transcriptional activation. Therefore, it is important to investigate transactivation properties of dietary fatty acids as PPAR agonists and their role in metabolic reactions. Furthermore, human intervention studies comparing the effects of natural versus synthetic ligands side-by-side may reveal specific fatty acids that exert beneficial PPAR-mediated metabolic effects. The ability of PPARs to sense fatty acids and to mediate lipid metabolism, glucose metabolism and the inflammatory state makes them excellent targets for dietary modulation in order to prevent and treat the metabolic syndrome and associated diseases. This review discusses the role and function of PPARs and their ligands in light of the metabolic syndrome.