Pathobiology and cell interactions of platelets in diabetes

Reconsidering the role of glycaemic control in cardiovascular disease risk in type 2 diabetes: A 21st century assessment

It is well known that the multiple factors contributing to the pathogenesis of type 2 diabetes (T2D) confer an increased risk of developing cardiovascular disease (CVD). Although the relationship between hyperglycaemia and increased microvascular risk is well established, the relative contribution of hyperglycaemia to macrovascular events has been strongly debated, particularly owing to the failure of attempts to reduce CVD risk through normalizing glycaemia with traditional therapies in high-risk populations. The debate has been further fuelled by the relatively recent discovery of the cardioprotective properties of glucagon-like peptide-1 receptor agonists and sodium-glucose cotransporter-2 inhibitors. Further, as guidelines now recommend individualizing glycaemic targets, highlighting the importance of achieving glycated haemoglobin (HbA1c) goals safely, the previously observed negative influences of intensive therapy on CVD risk might not present if trials were repeated using current-day treatments and individualized HbA1c goals. Emerging longitudinal data illuminate the overall effect of excess glucose, the impacts of magnitude and duration of hyperglycaemia on disease progression and risk of CVD complications, and the importance of glycaemic control at or early after diagnosis of T2D for prevention of complications. Herein, we review the role of glucose as a modifiable cardiovascular (CV) risk factor, the role of microvascular disease in predicting macrovascular risk, and the deleterious impact of therapeutic inertia on CVD risk. We reconcile new and old data to offer a current perspective, highlighting the importance of effective, early treatment in reducing latent CV risk, and the timely use of appropriate therapy individualized to each patient's needs.

ITGA2 Gene Polymorphism Is Associated with Type 2 Diabetes Mellitus in the Kazakhstan Population

Background and Objectives: Nowadays, every tenth adult in the world suffers from diabetes mellitus (DM). Diabetic retinopathy (DR) is the most common microvascular complication of type 2 DM (T2DM) and a leading cause of acquired blindness in middle-aged individuals in many countries. Previous studies have identified associations of several gene polymorphisms with susceptibility to microvascular complications of DM in various worldwide populations. In our study, we aimed to test the hypothesis of the associations of single nucleotide polymorphisms (SNP) of the VEGF (−2549I/D), RAGE (−429T/C and −374T/A), TCF7L2 (rs7903146), and ITGA2 (BglII) genes with a predisposition to DR among T2DM patients in the Kazakhstan population. Materials and Methods: We conducted a case–control study comparing the genotype distribution and allele frequencies between groups of DR patients (N = 94), diabetic patients without DR (N = 94), and healthy controls (N = 51). Genotypes were identified using the PCR-RFLP method. Results: In all cases, the genotype distribution corresponded to the Hardy–Weinberg equilibrium. The groups of diabetic patients with and without DR did not significantly differ in the genotype distribution of the SNPs studied. Differences between both groups of diabetic patients and healthy controls in four out of five SNPs were also not significant. At the same time, both groups of diabetic patients differed significantly from healthy controls in genotype distribution (p = 0.042 and 0.005, respectively) and allele frequencies (p = 0.021 and 0.002, respectively) of the BglII polymorphism in the ITGA2 gene. After adjusting for multiple comparisons, the differences between the group of diabetic patients without DR and the control group remained significant (pBonf = 0.027 for genotypes and pBonf = 0.009 for alleles). The BglII− allele was associated with diabetes: OR = 1.81 [1.09–2.99] for DR patients, and OR = 2.24 [1.34–3.75] for diabetic patients without DR. The association was also observed in the subset of Kazakhs. Conclusions: This study shows that the BglII polymorphism in the ITGA2 gene can be associated with T2DM but not with DR. According to our data, the risk allele for diabetes is the wild BglII− allele, and not the minor BglII+, which is considered as risky for DR.

Therapeutic Benefits of Alpha-Lipoic Acid Supplementation in Diabetes Mellitus: A Narrative Review

Elevated oxidative stress is a common denominator between pathways implicated in the pathogenesis of diabetes mellitus and diabetes complications, prompting the use of antioxidant compounds in diabetes therapy. Alpha-lipoic acid (ALA), has been investigated for its role as a potent antioxidant in diabetes treatment and the results from clinical trials indicate improved glucose metabolism, reduced oxidative stress, improved endothelial dysfunction, a decline in platelet reactivity and moderate improvements to weight loss yet conflicting data regarding insulin metabolism. ALA inhibits nuclear factor kappa B (NFkB), chelates divalent transient metal ions and induces the expression of adenosine monophosphate-activated protein kinase (AMPK). This narrative review explores the results from clinical trials investigating the role of ALA in the treatment of diabetes mellitus.

Vasculoprotective Effects of Vildagliptin. Focus on Atherogenesis

Vildagliptin is a representative of Dipeptidyl Peptidase-4 (DPP-4) inhibitors, antihyperglycemic drugs, approved for use as monotherapy and combination therapy in type 2 diabetes mellitus. By inhibiting enzymatic decomposition, DPP-4 inhibitors increase the half-life of incretins such as GLP-1 (Glucagon-like peptide-1) and GIP (Gastric inhibitors polypeptide) and prolong their action. Some studies present results suggesting the anti-sclerotic and vasculoprotective effects of vildagliptin reaching beyond glycemic control. Vildagliptin is able to limit inflammation by suppression of the NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) signaling pathway and proinflammatory agents such as TNF-α (tumor necrosis factor α), IL-1β (Interleukin-1β), and IL-8 (Interleukin 8). Moreover, vildagliptin regulates lipid metabolism; attenuates postprandial hypertriglyceridemia; and lowers serum triglycerides, apolipoprotein B, and blood total cholesterol levels. This DPP-4 inhibitor also reduces macrophage foam cell formation, which plays a key role in atheromatous plaque formation and stability. Vildagliptin reduces vascular stiffness via elevation of nitric oxide synthesis, improves vascular relaxation, and results in reduction in both systolic and diastolic blood pressure. Treatment with vildagliptin lowers the level of PAI-1 presenting possible antithrombotic effect. By affecting the endothelium, inflammation, and lipid metabolism, vildagliptin may affect the development of atherosclerosis at its various stages. The article presents a summary of the studies assessing vasculoprotective effects of vildagliptin with special emphasis on atherogenesis.

Prevalence of pre-existing dysglycaemia among inpatients with acute coronary syndrome and associations with outcomes

AIMS

We aimed to confirm the hypothesis that dysglycaemia including in the pre-diabetes range affects a majority of patients admitted with acute coronary syndrome (ACS) and is associated with worse outcomes.

METHODS

In this prospective observational cohort study, consecutive inpatients aged ≥ 54 years with ACS were uniformly tested and categorised into diabetes (prior diagnosis/ HbA1c ≥ 6.5%, ≥48 mmol/mol), pre-diabetes (HbA1c 5.7-6.4%, 39-47 mmol/mol) and no diabetes (HbA1c ≤ 5.6%, ≤38 mmol/mol) groups.

RESULTS

Over two years, 847 consecutive inpatients presented with ACS. 313 (37%) inpatients had diabetes, 312 (37%) had pre-diabetes and 222 (25%) had no diabetes. Diabetes, compared with no diabetes, was associated with higher odds of acute pulmonary oedema (APO, odds ratio, OR 2.60, p < 0.01), longer length of stay (LOS, incidence rate ratio, IRR 1.18, p = 0.02) and, 12-month ACS recurrence (OR 1.86, p = 0.046) after adjustment, while no significant associations were identified for pre-diabetes. Analysed as a continuous variable, every 1% (11 mmol/mol) increase in HbA1c was associated with increased odds of APO (OR 1.28, P = 0.002) and a longer LOS (IRR 1.05, P = 0.03).

CONCLUSIONS

The high prevalence of dysglycaemia and association with poorer clinical outcomes justifies routine HbA1c testing to identify individuals who may benefit from cardioprotective anti-hyperglycaemic agents and, lifestyle modification to prevent progression of pre-diabetes.

Platelet Activation and Platelet-Leukocyte Aggregates in Type I Diabetes Mellitus

Hyperglycemia alone may not explain the increased risk of cardiovascular diseases (CVDs) in patients with type 1 diabetes (T1D) compared with type 2. This study emphases on the evaluation of some platelet activity markers in patients with T1D, with relevance to some metabolic disorders as hyperlipidemia and hyperglycemia. This study was performed on 35 patients with T1D and 20 healthy controls. All participants were subjected to full history taking, clinical examination and assay of glycated hemoglobin (HbA_1c), and lipid profile. The expression of CD62P and CD36 on platelets and the frequency of platelet–monocyte, and platelet–neutrophil aggregates were assessed by flow cytometry. Patients showed significantly higher expression of CD62P and CD36 than the control group. Platelets aggregates with monocytes were also higher among patients than the control group. Levels of CD36⁺ platelets, CD62P⁺ platelets, and platelet–monocyte aggregates revealed significant correlations with the levels of HbA_1c, total cholesterol, low-density lipoprotein, and triglycerides. Hyperlipidemia and hyperglycemia accompanying T1D have a stimulatory effect on platelet activation which probably makes those patients vulnerable to CVD than nondiabetics.

Endothelial dysfunction and platelet hyperactivity in type 2 diabetes mellitus: molecular insights and therapeutic strategies

The incidence and prevalence of diabetes mellitus is rapidly increasing worldwide at an alarming rate. Type 2 diabetes mellitus (T2DM) is the most prevalent form of diabetes, accounting for approximately 90-95% of the total diabetes cases worldwide. Besides affecting the ability of body to use glucose, it is associated with micro-vascular and macro-vascular complications. Augmented atherosclerosis is documented to be the key factor leading to vascular complications in T2DM patients. The metabolic milieu of T2DM, including insulin resistance, hyperglycemia and release of excess free fatty acids, along with other metabolic abnormalities affects vascular wall by a series of events including endothelial dysfunction, platelet hyperactivity, oxidative stress and low-grade inflammation. Activation of these events further enhances vasoconstriction and promotes thrombus formation, ultimately resulting in the development of atherosclerosis. All these evidences are supported by the clinical trials reporting the importance of endothelial dysfunction and platelet hyperactivity in the pathogenesis of atherosclerotic vascular complications. In this review, an attempt has been made to comprehensively compile updated information available in context of endothelial and platelet dysfunction in T2DM.

Diabetic macular oedema: under-represented in the genetic analysis of diabetic retinopathy

Diabetic retinopathy, a complication of both type 1 and type 2 diabetes, is a complex disease and is one of the leading causes of blindness in adults worldwide. It can be divided into distinct subclasses, one of which is diabetic macular oedema. Diabetic macular oedema can occur at any time in diabetic retinopathy and is the most common cause of vision loss in patients with type 2 diabetes. The purpose of this review is to summarize the large number of genetic association studies that have been performed in cohorts of patients with type 2 diabetes and published in English-language journals up to February 2017. Many of these studies have produced positive associations with gene polymorphisms and diabetic retinopathy. However, this review highlights that within this large body of work, studies specifically addressing a genetic association with diabetic macular oedema, although present, are vastly under-represented. We also highlight that many of the studies have small patient numbers and that meta-analyses often inappropriately combine patient data sets. We conclude that there will continue to be conflicting results and no meaningful findings will be achieved if the historical approach of combining all diabetic retinopathy disease states within patient cohorts continues in future studies. This review also identifies several genes that would be interesting to analyse in large, well-defined cohorts of patients with diabetic macular oedema in future candidate gene association studies.

A Study of Platelet Indices in Type 2 Diabetes Mellitus Patients

Altered platelets have been reported in patients with diabetes mellitus and has been considered as a 'prothrombotic state' with enhanced platelet reactivity. They have been associated with increased risk of vascular complications in these patients. Platelet indices correlate with functional status of platelets and is an emerging risk factor of vascular complications in diabetes. The study was undertaken to know the efficacy of platelet analysis in assessing the prognosis of diabetes mellitus. A prospective hospital based study of platelet parameters MPV, PDW and P-LCR was carried out on 280 cases diagnosed with Type 2 diabetes Mellitus and 280 controls with normal blood glucose levels. The blood glucose levels and HbA1c level were also measured. Statistical evaluation was performed by using Student's unpaired t test and Pearson correlation test. The average age of presentation with type 2 diabetes mellitus was 53 ± 5.7 years. The mean duration of diabetes was 4.7 ± 2.5 years. MPV, PDW and P-LCR were significantly higher in diabetics compared to non diabetics (11.3 ± 1.0 vs. 9.0 ± 0.6, 14.2 ± 2.5 vs. 10.7 ± 0.7 fl, 35.0 ± 8.1 vs. 23.0 ± 2.4%). Among the diabetics, MPV, PDW and P-LCR were higher in those with complications as compared to those without complications, which was not statistically significant. The higher values of MPV, PDW and P-LCR indicates that they serve as better risk indicator of initial vascular complications in diabetes mellitus patients and can be used as a simple and cost effective tool to assess vascular events.

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.

Type 2 diabetes and cardiovascular disease: Have all risk factors the same strength?

Diabetes mellitus is a chronic condition that occurs when the body cannot produce enough or effectively use of insulin. Compared with individuals without diabetes, patients with type 2 diabetes mellitus have a considerably higher risk of cardiovascular morbidity and mortality, and are disproportionately affected by cardiovascular disease. Most of this excess risk is it associated with an augmented prevalence of well-known risk factors such as hypertension, dyslipidaemia and obesity in these patients. However the improved cardiovascular disease in type 2 diabetes mellitus patients can not be attributed solely to the higher prevalence of traditional risk factors. Therefore other non-traditional risk factors may be important in people with type 2 diabetes mellitus. Cardiovascular disease is increased in type 2 diabetes mellitus subjects due to a complex combination of various traditional and non-traditional risk factors that have an important role to play in the beginning and the evolution of atherosclerosis over its long natural history from endothelial function to clinical events. Many of these risk factors could be common history for both diabetes mellitus and cardiovascular disease, reinforcing the postulate that both disorders come independently from “common soil”. The objective of this review is to highlight the weight of traditional and non-traditional risk factors for cardiovascular disease in the setting of type 2 diabetes mellitus and discuss their position in the pathogenesis of the excess cardiovascular disease mortality and morbidity in these patients.

Association of platelet glycoprotein receptor alpha2beta1 integrin and glycoprotein IIIa gene polymorphisms with diabetic retinopathy: evidence from 3007 subjects

PURPOSE

Many epidemiological studies have evaluated associations of platelet glycoprotein receptor alpha2beta1 integrin (ITGA2) and glycoprotein IIIa (ITGB3) gene polymorphisms with diabetic retinopathy (DR), but the published data are inconclusive. The aim of the present study was to assess the associations by using meta-analysis.

METHODS

A comprehensive electronic search (PubMed, EMBASE, Elsevier Science Direct, CNKI and Wanfang) was carried out until 31 August 2013. Odds ratios (ORs) and its 95% confidence intervals (CIs) were used to assess the strength of the associations.

RESULTS

Nine studies including 1678 cases and 1329 controls were included in the meta-analysis. Meta-analysis was performed for ITGA2 gene BgI II polymorphism (7 studies including 758 cases and 570 controls) and ITGB3 gene PlA1/A2 polymorphism (4 studies including 1047 cases and 861 controls). Significant associations were found for BgI II (+ versus -: OR = 1.42, 95% CI = 1.06-1.90, p = 0.02; +/- + +/+ versus -/-: OR = 1.46, 95% CI = 0.99-2.15, p = 0.06; +/+ versus -/- + +/-: OR = 1.90, 95% CI = 1.35-2.67, p = 0.0003) and PlA1/A2 (A2 versus A1: OR = 0.74, 95% CI = 0.52-1.07, p = 0.11; A1A2 + A2A2 versus A1A1: OR = 0.80, 95% CI = 0.64-0.99, p = 0.04; A2A2 versus A1A1 + A1A2: OR = 0.45, 95% CI = 0.27-0.75, p = 0.002) polymorphisms.

CONCLUSION

This meta-analysis demonstrates that DR is associated with ITGA2 BgI II and ITGB3 PlA1/A2 polymorphisms.

Clinical marker of platelet hyperreactivity in diabetes mellitus

Atherothrombotic complications are important causes of morbidity and mortality in diabetic patients. Diabetes has been considered to be a prothrombotic status. Several factors contribute to the prothrombotic condition, such as increasing coagulation, impaired fibrinolysis, endothelial dysfunction, and platelet hyperreactivity. Among the factors that contribute to the prothrombotic status in diabetes, altered platelet function plays a crucial role. Although understanding platelet function abnormalities in diabetes still remains as a challenge, more attention should be focused on platelet function for effective management and the prediction of atherothrombotic events in diabetic patients. This review will provide an overview on the current status of knowledge of platelet function abnormalities and clinical marker of platelet hyperreactivity in patients with diabetes.

Platelet function profiles in patients with diabetes mellitus

Patients with diabetes mellitus (DM) are at high risk for several cardiovascular disorders such as coronary heart disease, stroke, peripheral arterial disease, and congestive heart failure. DM has reached epidemic proportions and its strong association with coronary artery disease is responsible for increased cardiovascular morbidity and mortality. DM patients are characterized by platelet hyperreactivity, which contribute to the enhanced atherothrombotic risk of these subjects. Several mechanisms are involved in the hyperreactive platelet phenotype characterizing DM patients. Furthermore, a large proportion of DM patients show inadequate response to standard antiplatelet treatments and high rate of adverse recurrent cardiovascular events despite compliance with standard antiplatelet treatment regimens. Therefore, new antiplatelet treatment regimens are warranted in DM patients to reduce their atherothrombotic risk. The present manuscript provides an overview on the current status of knowledge on platelet function profiles in patients with DM and therapeutic considerations.

Association analysis of genetic variations of eNOS and α2β1 integrin genes with type 2 diabetic retinopathy

Background

Diabetic retinopathy (DR) is classically defined as a microvasculopathy that primarily affects the small blood vessels of the inner retina as a complication of diabetes mellitus. It has been suggested that nitric oxide (NO) and α₂β₁ integrin (a platelet receptor for collagen) play an important role in the pathogenesis of microvascular complications in DR.

Aim

The aim of this study was to investigate the association of two candidate genes involved in the regulation of retinal vasculature, endothelial nitric oxide synthase (eNOS) and α₂β₁ integrin (ITGA2) genes, with the development of DR in Egyptian patients with type 2 diabetes mellitus and to investigate whether genetic variants will affect the type of retinopathy (proliferative or nonproliferative).

Methods

In this study, 70 patients were enrolled and categorized into two groups: (1) a DR group consisting of 50 patients with DR, which was further subclassified into 25 patients with nonproliferative DR (NPDR group) and 25 patients with proliferative DR (PDR group) and (2) a diabetes without retinopathy (DWR) group, comprising 20 patients with type 2 diabetes of more than 10 years’ duration who showed no signs of DR. Associations of the genetic polymorphisms of eNOS (G894T) and ITGA2 (BgI II) were studied. Polymerase chain reaction-restriction fragment length polymorphism analysis was performed for all samples to evaluate the genotypes and correlate with the phenotype of the disease.

Results

The allele frequencies of both polymorphisms showed considerable differences between patients with and without DR. The GG genotype of G894T polymorphism of eNOS was associated with a 9.75-fold increased risk of DR (95% confidence interval 1.7–55.4) and the genotype ITGA2 BgI II (+/+) was associated with a 10.1-fold increased risk of DR (95% confidence interval 1.8–57.9), while the α₂β₁ integrin gene polymorphism of genotype distribution of both eNOS and ITGA2 polymorphisms did not differ significantly between the proliferative and nonproliferative DR groups.

Conclusion

A significant association between the G894T polymorphism of eNOS and BgI II polymorphism of ITGA2 genes and DR was observed, while there was no association between the genetic variants of those two polymorphisms and the type of retinopathy.

[Characteristics of therapy of acute myocardial infarction in diabetes]

Therapy of acute myocardial infarction (STEMI and NSTEMI) in diabetics does not principally differ from that of non-diabetic patients. Due to the higher mortality in diabetics reperfusion measures, such as direct percutaneous coronary intervention (PCI), should be rapidly performed. An intensive drug treatment with thrombocyte aggregation inhibitors, angiotensin-converting enzyme (ACE) inhibitors and beta-receptor blocking agents must be carried out according to the current guidelines. An important factor is the high risk of renal failure due to the contrast dye administered during PCI in the presence of pre-existing diabetic kidney damage which should be limited to 100 ml if possible. Direct PCI should be limited to the infarcted vessel. After stabilization a comprehensive strategy to cure coronary artery disease, whether with PCI or coronary artery bypass graft (CABG) should be finalized. If severe coronary 3-vessel disease is present, CABG should be favored in diabetic patients. After surviving an acute myocardial infarction differentiated metabolic monitoring is mandatory.

Platelet dysfunction in vascular pathologies and how can it be treated

Cardiovascular diseases are one of the leading causes of morbidity and mortality in industrialized countries, and although many processes play a role in the development of vascular disease, thrombosis is the primary event that precipitates stroke and acute coronary syndromes. The blood platelets are of significant importance in medicine. These cells are involved in many physiological processes, particularly haemostasis through their ability to aggregate and form clots in response to activation. In addition, these dynamic cells display activities that extend beyond thrombosis, including an important role in initiating and sustaining vascular inflammation. The expansion of knowledge from basic and clinical research has highlighted the critical position of platelets in several inflammatory diseases such as arthritis and atherosclerosis. Platelets are emerging as important mediators of inflammation and provide important signals to mediate phenotype of other blood and vascular cells. The important role of platelets in arterial thrombosis and the onset of acute myocardial infarction after atherosclerotic plaque rupture make inhibition of platelet aggregation a critical step in preventing thrombotic events associated with stroke, heart attack, and peripheral arterial thrombosis. However, the use of platelet inhibitors for thrombosis prevention must seek a delicate balance between inhibiting platelet activation and an associated increased bleeding risk. The aim of this review is to up-date the knowledge on platelets physiology and dysfunction in pathologies, such as diabetes mellitus, hypercholesterolemia, and hypertension, emphasizing the link between platelets and the inflammation-related atherosclerosis. The review evaluates the opportunities offered by the novel platelet inhibitors to efficiently alleviate the thrombotic events.

[Cardial target-organ damage in diabetes]

Coronary heart disease and type 2 diabetes mellitus can be considered as a syntropy. Accordingly, cardiologists and diabetologists should organize an interdisciplinary car of the patient with both cardiac disease and diabetes mellitus. Arterial hypertension is frequently present in the diabetic condition and increases further morbidity and mortality rates due to the involvement of the coronary microcirculation. Coronary artery disease is characterized by a rapid progression and a diffuse distribution particularly in the periphery. Consequently in severe diabetic coronary artery disease coronary bypass surgery should be preferred rather than percutaneous coronary stenting, which should be favored in less severe cases. In the antihyperglycemic treatment a reduction in cardiovascular endpoints has only be documented after metformin. Therapy with thiazolidinediones has been terminated due to an increase in coronary morbidity and mortality under rosiglitazone. In as much glucagon-like peptide-I analogues and dipeptidylpeptidase 4 inhibitors will reduce cardiovascular endpoints has to be waited for. Thus an endpoint orientated antihyperglycemic treatment is limited to insulin, metformin and sulfonylureas.

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.

Duration and type of therapy for diabetes: impact on cardiac risk stratification with stress electrocardiographic-gated SPECT myocardial perfusion imaging

BACKGROUND

Stress electrocardiogram(ECG)-gated single photon emission computed tomography (SPECT) imaging is highly effective in risk stratification of diabetic patients for adverse cardiac events. While patients with diabetes are predisposed to a more aggressive progression of vascular disease, the impact of its duration and type of therapy on risk stratification are unknown.

METHODS

From the Hartford Hospital Nuclear Cardiology clinical database, 886 diabetic patients who underwent exercise or pharmacologic stress ECG-gated SPECT were identified, with complete follow-up regarding the occurrence of adverse cardiac events and information regarding the duration of diabetes and the type of therapy (insulin vs oral medication only) at the time of testing. Images were interpreted using the American College of Cardiology/ASNC standard 17-segment scoring model.

RESULTS

Of the 886 diabetic patients, 98 (11%) suffered cardiac death or non-fatal myocardial infarction during follow-up (2.5 ± 1.6 years). A receiver operator characteristics curve demonstrated that diabetes ≥10 years in duration provided the maximal sum of sensitivity and specificity for the prediction of adverse cardiac outcomes. Multivariate analysis identified the following as independent predictors of adverse outcome: Post-stress ejection fraction (EF) <40% (P = .001), age (P = .004), insulin therapy (P = .031), diabetes duration >10 years (P = .038), summed stress score (SSS) >8 (P = .046). For patients with an SSS >8, diabetes duration and type of therapy significantly enhanced risk stratification. Similar findings emerged for patients with a post-stress EF <40%.

CONCLUSION

For diabetic patients undergoing stress ECG-gated SPECT myocardial perfusion imaging, disease duration and type of therapy provide independent and incremental prognostic information. Integration of these variables with this cardiovascular imaging technology significantly enhances cardiac risk stratification.

Platelet abnormalities in diabetes mellitus

Patients with diabetes mellitus (DM) have accelerated atherosclerosis, which is the main underlying factor contributing to the high risk of atherothrombotic events in these patients. Atherothrombotic complications are the leading cause of morbidity and mortality in patients with DM. Among factors contributing to the prothrombotic condition which characterise patients with DM, platelet hyperreactivity plays a pivotal role. Platelets of DM patients are characterised by dysregulation of several signalling pathways leading to intensified adhesion, activation and aggregation. Multiple mechanisms are involved in platelet dysfunction of patients with DM, which can be categorised as follows: a) hyperglycaemia, b) insulin deficiency and resistance, c) associated metabolic conditions, and d) other cellular abnormalities.The present manuscript aims to provide an overview on the current status of knowledge on platelet abnormalities that characterise patients with DM.

Antithrombotic therapy in patients with diabetes mellitus and coronary artery disease

Currently approved antiplatelet treatment strategies have proved successful for reducing cardiovascular adverse events in patients with CAD. However, despite the use of recommended antiplatelet treatment strategies, the presence of DM has been consistently associated with a negative impact on outcomes and a high rate of adverse cardiovascular events continue to occur in patients with DM. The elevated prevalence of low response to standard oral antiplatelet agents contribute to these impaired outcomes. Thus, the search for more potent antiplatelet treatment strategies is warranted in high-risk patients, such as those with DM. The present manuscript provides an overview on the current status of knowledge on currently available antiplatelet agents, focusing on the benefits and limitations of these therapies in DM patients, and evaluating the potential role of new antithrombotic agents and treatment strategies currently under development to overcome these limitations.

[The role of platelets in atherosclerosis, diabetes mellitus, and chronic kidney disease. An attempt at explaining the TREAT study results]

Erythropoiesis-stimulating agents (ESA) are used to treat renal anemia. The TREAT study (Trial to Reduce Cardiovascular Events with Aranesp Ther- apy) of diabetic patients with chronic kidney disease (CKD) found that the risk of stroke was significantly higher than in the control arm. This raises the question as to what causes this phenomenon. Platelets may play a crucial role in this context. Atherogenesis involves complex interactions between platelets and monocytes (platelet-monocyte crosstalk) and with endothelial cells. Platelets are activated in cases of diabetes mellitus, especially. During atherogenesis, partial functions of platelets other than those inhibited by aspirin, as a cyclooxygenase inhibitor, or by adenosine diphosphate receptor P2Y(12)antagonists, such as thienopyridines, are of relevance. During platelet-monocyte crosstalk, specifically, an important role is played by adhesion receptors such as selectins and integrins. In addition, ESA cause platelet activation by direct and indirect mechanisms. Antagonistic thereto is a renal bleeding tendency in cases of severe CKD, due to platelet dysfunction, which can be remedied with appropriate renal replacement therapy and administration of ESA in order to reach a hemoglobin (Hb) level of 10 g/dl. However, if the Hb level exceeds 10 g/dl, the even stronger platelet activation caused by ESA, combined with the activation caused by diabetes, leads to a prothrombotic state, which in patients with severe atherosclerosis can result in acute atherothrombotic complications, in the genesis of which platelets play a key role. This would be one hypothesis for explaining the increased incidence of strokes in the TREAT study.

Proteomics meets blood banking: identification of protein targets for the improvement of platelet quality

Proteomics has brought new perspectives to the fields of hematology and transfusion medicine in the last decade. The steady improvement of proteomic technology is propelling novel discoveries of molecular mechanisms by studying protein expression, post-translational modifications and protein interactions. This review article focuses on the application of proteomics to the identification of molecular mechanisms leading to the deterioration of blood platelets during storage - a critical aspect in the provision of platelet transfusion products. Several proteomic approaches have been employed to analyse changes in the platelet protein profile during storage and the obtained data now need to be translated into platelet biochemistry in order to connect the results to platelet function. Targeted biochemical applications then allow the identification of points for intervention in signal transduction pathways. Once validated and placed in a transfusion context, these data will provide further understanding of the underlying molecular mechanisms leading to platelet storage lesion. Future aspects of proteomics in blood banking will aim to make use of protein markers identified for platelet storage lesion development to monitor proteome changes when alterations such as the use of additive solutions or pathogen reduction strategies are put in place in order to improve platelet quality for patients.

Erythrocytosis in offspring of mothers with Type 1 diabetes--are factors other than insulin critical determinants?

AIM

Maternal diabetes is associated with polycythaemia and thrombocytopaenia in the offspring; however, the relationship with fetal hormones is unknown. We assessed the association of maternal glycaemic control, birthweight and fetal hormones with haematological indices in pregnancies complicated by maternal diabetes.

METHODS

Prospective study using cord blood samples from 89 offspring of mothers with Type 1 diabetes (OT1DM) and 34 control offspring. Full blood count, insulin, leptin, adiponectin, cortisol, insulin-like growth factor 1 (IGF-1), insulin-like growth factor binding protein 3, intercellular adhesion molecule 1 and C-reactive protein were measured in the umbilical vein at birth.

RESULTS

Haematocrit was higher in OT1DM (OT1DM 0.55 +/- 0.17%, control offspring 0.51 +/- 0.06%; P = 0.02). The difference in platelets count was not statistically significant [OT1DM 214 x 10(9)/l (173-259); control offspring 253 x 10(9)/l (180-310), P = 0.06]. Maternal glycated haemoglobin (HbA(1c)) showed a moderate positive correlation with fetal haematocrit (r = 0.30, P = 0.02). Cord platelet counts were negatively associated with birthweight in OT1DM (r = -0.27, P = 0.01). In multivariate models, cord insulin was not associated with haematocrit, but cord leptin was negatively associated with platelets in control offspring (P < 0.001) and OT1DM (P = 0.046), with additional contributions from male sex (P = 0.08) in OT1DM, and IGF-1 (P = 0.04) and insulin (P = 0.04) in control offspring.

CONCLUSIONS

Fetal haematocrit is increased in response to diabetes in pregnancy and is related to maternal glycaemic control. Fetal hyperinsulinism, hyperleptinaemia or macrosomia, although readily demonstrable in this cohort, do not emerge as determinants of raised fetal haematocrit in OT1DM. Both increased birthweight and fetal leptin are negatively associated with platelet count.

Platelet proteome changes associated with diabetes and during platelet storage for transfusion

Human platelets play a key role in hemostasis and thrombosis and have recently emerged as key regulators of inflammation. Platelets stored for transfusion produce pro-thrombotic and pro-inflammatory mediators implicated in adverse transfusion reactions. Correspondingly, these mediators are central players in pathological conditions including cardiovascular disease, the major cause of death in diabetics. In view of this, a mass spectrometry based proteomics study was performed on platelets collected from healthy and type-2 diabetics stored for transfusion. Strikingly, our innovative and sensitive proteomic approach identified 122 proteins that were either up- or down-regulated in type-2 diabetics relative to nondiabetic controls and 117 proteins whose abundances changed during a 5-day storage period. Notably, our studies are the first to characterize the proteome of platelets from diabetics before and after storage for transfusion. These identified differences allow us to formulate new hypotheses and experimentation to improve clinical outcomes by targeting "high risk platelets" that render platelet transfusion less effective or even unsafe.

Atherogenesis and atherothrombosis--focus on diabetes mellitus

Diabetes mellitus represents a major cause of cardiovascular morbidity and mortality in developed countries, and atherothrombosis accounts for most deaths among patients with diabetes mellitus. Atherothrombosis is defined as atherosclerotic lesion disruption with superimposed thrombus formation. As a long-term, progressive disease process, atherosclerosis often results in an acute atherothrombotic event through plaque rupture and formation of a platelet-rich thrombus. The principal clinical manifestations of atherothrombosis are sudden cardiac death, myocardial infarction, ischaemic stroke, and peripheral arterial ischaemia comprising both intermittent claudication and critical limb ischaemia. Atherosclerosis is the leading cause of morbidity and mortality in the industrialized world, and diabetes mellitus magnifies the risk of cardiovascular events. In addition to the well-known microvascular complications of diabetes mellitus - such as nephropathy, retinopathy and neuropathy - the risk of macrovascular complications affecting the large conduit arteries markedly increases in patients with diabetes mellitus.

Hyperglycemia, diabetes and stroke: focus on the cerebrovasculature

Acute ischemic stroke (AIS) results from the occlusion of an artery and causes vascular and neuronal damage, both of which affect the extent of ischemic injury and stroke outcome. Despite extensive efforts, there is only one effective treatment for AIS. Given that up to 40% of the AIS patients present with admission hyperglycemia either as a result of diabetes or acute stress response, targets for neuronal and vascular protection under hyperglycemic conditions need to be better defined. Here, we review the impact of diabetes and acute hyperglycemia on experimental stroke with an emphasis on cerebrovasculature structure and function. The relevance to clinical evidence is also discussed.

The application of proteomics technology to thrombosis research: the identification of potential therapeutic targets in cardiovascular disease

Thrombus formation underpins the development of cardiovascular diseases, including acute coronary syndromes and ischaemic stroke. A number of well-characterised cardiovascular risk factors which contribute to the development of the majority of cardiovascular events have been identified, including dyslipidaemia, hypertension and diabetes. Individuals with type 2 diabetes mellitus (T2DM) have a 3- to 5-fold increased risk for development of cardiovascular disease (CVD). They may have a cluster of haemostatic abnormalities, including elevated levels of plasminogen activator inhibitor-1 (PAI-1) and fibrinogen, which contribute to acute thrombotic events. It is clear that additional unidentified risk factors contribute to the pathogenesis of cardiovascular events, and so the search for novel biomarkers and effectors, particularly in individuals with T2DM, remains a major challenge of cardiovascular medicine. Plasma and cellular proteins which contribute to thrombus formation have the potential to confer a pro-thrombotic state and represent a link between genotype, environment and disease phenotype. The comprehensive analysis of these proteins is now increasingly facilitated through the continued development of proteomic technologies which provide multifaceted approaches to the identification of novel biomarkers and/or effectors of thrombus formation and on which future anticoagulant and thrombolytic therapies may be based. This review provides an overview of current proteomic technologies. It focuses on the recent studies in which these technologies have been applied in the search for novel proteins that may confer increased risk of acute cardiovascular diseases and therefore that may influence disease progression and therapy.

Coated-platelet levels in patients with Type 1 and with Type 2 diabetes mellitus

Coated-platelet levels were quantified in 58 people with Type 1 diabetes, 90 with Type 2 diabetes, and 54 non-diabetic controls. In diabetes high coated-platelet levels were related to smoking and glucose control drugs, but not to glycaemia or other drugs. Prospective studies should evaluate coated-platelets and complications and drug effects.

Strategies for antiplatelet targets and agents

Platelets play a key role in thrombosis and haemostasis, which can be either beneficial or deleterious depending on the circumstance. Antiplatelet therapy is the 'cornerstone' in the prevention and treatment of thrombotic diseases. Platelet activation is a complex process known as transmembrane signaling which then serves to activate the platelet via a cascade of biochemical interactions. Currently available strategies of antiplatelet therapy are generally based on the signaling pathway of platelet activation, which possess the characters that mono-agent, mono-target, and mainly irreversible inhibition. Therefore, both established and novel antiplatelet agents have their own pros and cons and such problems as resistance, drug-drug interaction, discontinuation and monitoring, etc. have been appeared. Due to the problems existing in current antiplatelet agents, future new strategies for antiplatelet targets, agent-developing and treatment might probably include three aspects: targeting the factors associated with platelet hyperactivity, developing novel antiplatelet agents with multiple targets, mild and reversible properties from natural products, and keeping healthy lifestyle and emphasizing prevention.

Aspirin and mortality in patients with diabetes sustaining acute coronary syndrome

OBJECTIVE

We sought to compare mortality reduction associated with secondary prevention in patients with and without diabetes after acute coronary syndrome (ACS).

RESEARCH DESIGN AND METHODS

We conducted a cohort study involving 2,499 patients with ACS recruited from 11 U.K. hospitals. Multivariable analysis comparing all-cause mortality risk reduction associated with pharmacologic agents in patients with and without diabetes.

RESULTS

Aspirin was not associated with significant mortality benefit in diabetes sufferers (95% CI 0.50-1.08); nondiabetic patients derived a 48% mortality reduction (P < 0.001). The interaction between diabetes and aspirin use was statistically significant (P = 0.037), indicating that patients with diabetes experience less effective mortality reduction from aspirin use.

CONCLUSIONS

Aspirin, but not other secondary prevention agents, is associated with less effective mortality reduction in patients with diabetes and unstable coronary artery disease.

Cardiovascular complications in diabetes: targets and interventions

Cardiovascular complications are mainly responsible for the high morbidity and mortality in people with diabetes. The awareness of physicians for the importance of primary prevention increased lately and numerous strategies have been developed. The spectrum ranges from pharmacologic treatment to vitamins and dietetic interventions. Some interesting concepts such as focusing on exogenous advanced glycation end products have emerged, but definitive results on their clinical relevance are still lacking. A major problem of the primary prevention is the choice of the method applied for screening, the criteria used to classify risk patients, as well as the choice of therapy. Guidelines provide goals to be achieved and offer alternatives for treatment, but the medical decision has to be made on an individualized basis. In this overview, we will comprehensively focus on the most important pathomechanisms and clinically relevant approaches, aiming at the early diagnosis and treatment of diabetes along with coronary heart disease. When primary prevention fails, we advocate a more aggressive treatment of critically ill patients, followed by optimal secondary prevention meeting on-target goals precisely.

Review of the pleiotropic effects of peroxisome proliferator-activated receptor gamma agonists on platelet function

The primary target receptor for thiazolidinediones (TZDs) or peroxisome proliferator-activated receptor gamma (PPARgamma) agonists is a transcription factor in the nucleus of adipocytes and other metabolically active cells, where they improve insulin sensitivity and glucose utilization. TZDs are also able to modify gene expression in macrophages, smooth muscle cells, and endothelial cells. Although PPARgamma is considered to be a nuclear receptor, enucleate platelets also highly express this receptor. The aim of this review is to present the current understanding of a direct or indirect effect of TZDs on platelet function. By means of a comprehensive literature search (January 1990-June 2006), publications were obtained that contained specific information about in vitro and in vivo effects of TZDs on platelet function. The effects were studied for different risk biochemical markers, i.e., proteins found to be elevated in the state of procoagulant inflammation and endothelial dysfunction. Improvement of platelet function was reported for all TZDs-troglitazone, pioglitazone, and rosiglitazone. The described effects included reduction of platelet aggregation, suppression of thrombin-induced protein kinase C-alpha and -beta activation, decrease in plasma P-selectin and platelet P-selectin expression, increase in nitric oxide production, inhibition of the Rho/Rho kinase pathway, and inhibition of tissue factor- and platelet-activating factor-induced morphological changes in macrophages. These findings appeared in parallel with reduction of the plasma concentrations of pro-inflammatory risk markers. TZDs seem to have a direct pleiotropic positive influence on platelet function and coagulation and may be helpful in treating the prothrombotic state observed in patients with type 2 diabetes and metabolic syndrome.

Relaxin expression correlates significantly with serum fibrinogen variation in response to antidiabetic treatment in women with type 2 diabetes mellitus

AIM

Diabetes is associated with aberrant coagulation. Relaxin, an insulin-like peptide hormone, is a candidate to be involved in the underlying molecular mechanisms. Therefore, the present study investigated the correlation of relaxin expression with fibrinogen levels in diabetes patients undergoing oral antidiabetic treatment.

METHOD

In total, 192 type 2 diabetes patients were enrolled into the study. The patients were randomized to receive either pioglitazone or glimepiride for 26 weeks. Blood was drawn at baseline and at the end of the study to measure the concentrations of relaxin and fibrinogen with an enzyme-linked immunosorbent assay and a turbimetric method, respectively. In addition, platelets were counted at both time points.

RESULTS

Total datasets were available from 161 patients (age 62.5 +/- 8.1 years, mean +/- standard deviation; 58 women, 103 men). The median initial parameter concentrations were: relaxin, 27.4 pg/ml (range 0.4 - 380 pg/ml); fibrinogen, 3.0 g/l (range 1.1 - 7.9 g/l); platelets, 217,000/microl (range 51,000 - 547 000/microl). The data were analyzed according to the increase or decrease of each parameter after therapy compared with baseline. There was a significant correlation of relaxin variation with fibrinogen variation, seen particularly in the female subgroup (p < 0.05). The correlation was independent of the antidiabetic medication.

CONCLUSION

The data suggest that there is a correlation between fibrinogen levels and relaxin expression. Relaxin may exert its cardioprotective properties after pathologic fibrinogen increase. This regulation may be affected by diabetes. As a consequence, cardiovascular risk may increase in women with aberrant relaxin functionality.

AGEs and methylglyoxal induce apoptosis and expression of Mac-1 on neutrophils resulting in platelet—neutrophil aggregation

INTRODUCTION

Diabetes mellitus is characterised by hyperglycaemia that plays an important role in the pathogenesis of diabetic complications including accumulation of methylglyoxal (MG), a highly reactive alpha-dicarbonyl metabolite of glucose degradation pathways and increased generation of advanced glycation end products (AGEs). The aim of this study was to investigate the impact of AGE-BSA, the model substance for AGEs, and MG on cellular haemostasis.

MATERIALS AND METHODS

Isolated peripheral blood mononuclear cells (PBMCs) or whole blood was incubated with AGE-BSA and MG. Markers of cellular haemostasis were monitored by flow cytometry.

RESULTS

Exposure of PBMCs to AGE-BSA and MG resulted in a dose- and time-dependent increase of TF-expression by monocytes. AGE-BSA and MG induced enhanced platelet-neutrophil aggregation. Examination of platelet activation showed that AGE-BSA induces no direct effect on the expression of P-selectin. However, stimulation with MG resulted in a dose-dependent expression of P-selectin by platelets. Stimulation with AGE-BSA or MG markedly increased dose-dependent expression of Apo2.7 on the neutrophil mitochondria. In addition the analysis demonstrated for the first time that both AGE-BSA and MG induce a dose-dependent expression of the adhesion molecule Mac-1 on the surface of neutrophils.

CONCLUSIONS

AGE-BSA as well as MG induced apoptosis of neutrophils and enhanced expression of the adhesion molecule Mac-1 resulting in increased formation of platelet-neutrophil aggregates. These findings may contribute to better understand the mechanism of diabetic thrombosis and the associated high cardiovascular risk of diabetic patients.

Proteomic approaches to dissect platelet function: Half the story

Platelets play critical roles in diverse hemostatic and pathologic disorders and are broadly implicated in various biological processes that include inflammation, wound healing, and thrombosis. Recent progress in high-throughput mRNA and protein profiling techniques has advanced our understanding of the biological functions of platelets. Platelet proteomics has been adopted to decode the complex processes that underlie platelet function by identifying novel platelet-expressed proteins, dissecting mechanisms of signal or metabolic pathways, and analyzing functional changes of the platelet proteome in normal and pathologic states. The integration of transcriptomics and proteomics, coupled with progress in bioinformatics, provides novel tools for dissecting platelet biology. In this review, we focus on current advances in platelet proteomic studies, with emphasis on the importance of parallel transcriptomic studies to optimally dissect platelet function. Applications of these global profiling approaches to investigate platelet genetic diseases and platelet-related disorders are also addressed.