[Show abstract][Hide abstract] ABSTRACT: Circulating microparticles (MPs) and endothelial progenitor cells (EPCs) correlate with endothelial dysfunction and contribute to the pathogenesis of atherosclerosis. In this context, we explored whether the angiotensin II type I receptor antagonist, irbesartan, exerts a pharmacological control in the atherosclerotic process by the improvement of EPC mobilization and inhibitory effects on MP release and VEGF and SDF-1α levels in the hypertensive-hypercholesterolemic (HH) hamster model. The HH hamsters were treated with irbesartan (50mg/kg b.w/day administered by gavage) for 4 month (HHI). We analyzed MP/EPC infiltration in vascular wall before and after irbesartan administration as well as the endothelial function and expression of VEGF/SDF-1α in plasma and tissue and of molecular pathways activated by them. The results showed that treatment with irbesartan significantly increased EPC infiltration and decreased MP infiltration. The mechanisms underlying this response include the reduction/increase of a number of specific membrane receptors exposed by MPs (TF, P-Selectin, E-Selectin, PSGL-1, Rantes), respectively by EPCs (β2-Integrins, α4β1-integrin), the augmentation of endothelium-mediated vasodilation and the reduction of protein expression of VEGF/SDF-1α followed by: 1) the diminishment of pro-inflammatory endothelial cytokines: VEGFR1, VEGFR2, CXCR4, Tie2, PIGF with role in EPC homing to sites of damaged endothelium; and 2) the increase of protein expression of COX-2, PGI2 synthase molecules with role in the improvement of arterial wall vasodilatation. In conclusion, the study underlines that irbesartan administration therapeutically improves/reduces EPC, respectively MP mobilization and this action may be of salutary relevance contributing to its beneficial cardiovascular effects.
European journal of pharmacology 04/2013; · 2.59 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: AIM: The purpose of this project was to evaluate the influence of circulating endothelial progenitor cells (EPCs) and platelet microparticles (PMPs) on blood platelet function in experimental hypertension associated with hypercholesterolemia. METHODS: GOLDEN SYRIAN HAMSTERS WERE DIVIDED IN SIX GROUPS: (i) control, C; (ii) hypertensive-hypercholesterolemic, HH; (iii) 'prevention', HHin-EPCs, HH animals fed a HH diet and treated with EPCs; (iv) 'regression', HHfin-EPCs, HH treated with EPCs after HH feeding; (v) HH treated with PMPs, HH-PMPs, and (vi) HH treated with EPCs and PMPs, HH-EPCs-PMPs. RESULTS: Compared to HH group, the platelets from HHin-EPCs and HHfin-EPCs groups showed a reduction of: (i) activation, reflected by decreased integrin 3β, FAK, PI3K, src protein expression; (ii) secreted molecules as: SDF-1, MCP-1, RANTES, VEGF, PF4, PDGF and (iii) expression of pro-inflammatory molecules as: SDF-1, MCP-1, RANTES, IL-6, IL-1β; TFPI secretion was increased. Compared to HH group, platelets of HH-PMPs group showed increased activation, molecules release and proteins expression. Compared to HH-PMPs group the combination EPCs with PMPs treatment induced a decrease of all investigated platelet molecules, however not comparable with that recorded when EPC individual treatment was applied. CONCLUSION: EPCs have the ability to reduce platelet activation and to modulate their pro-inflammatory and anti-thrombogenic properties in hypertension associated with hypercholesterolemia. Although, PMPs have several beneficial effects in combination with EPCs, these did not improve the EPC effects. These findings reveal a new biological role of circulating EPCs in platelet function regulation, and may contribute to understand their cross talk, and the mechanisms of atherosclerosis.
PLoS ONE 01/2013; 8(1):e52058. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Growing evidence links the stress at the endoplasmic reticulum (ER) to pathologies such as diabetes mellitus, obesity, liver, heart, renal and neurodegenerative diseases, endothelial dysfunction, atherosclerosis, and cancer. Therefore, identification of molecular pathways beyond ER stress and their appropriate modulation might alleviate the stress, and direct toward novel tools to fight this disturbance. An interesting resident of the ER membrane is protein tyrosine phosphatase 1B (PTP1B), an enzyme that negatively regulates insulin and leptin signaling, contributing to insulin and leptin resistance. Recently, new functions of PTP1B have been established linked to ER stress response. This review evaluates the novel data on ER stressors, discusses the mechanisms beyond PTP1B function in the ER stress response, and emphasizes the potential therapeutic exploitation of PTP1B to relieve ER stress.
Biochemical and Biophysical Research Communications 05/2012; 422(4):535-8. · 2.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This study aimed to (i) employ our newly designed model, the hypertensive-hypercholesterolemic hamster (HH), in order to find out whether a correlation exists between circulating microparticles (MPs), endothelial progenitor cells (EPCs) and their contribution to vascular dysfunction and (ii) to assess the effect of irbesartan treatment on HH animals (HHI).
The results showed that compared with the control (C) group, HH displayed: (i) a significant increase in plasma cholesterol and triglyceride concentration, and an augmentation of systolic and diastolic arterial blood pressure, and of heart rate; (ii) a marked elevation of MPs and a significant decrease in EPCs; (iii) structural modifications of the arterial wall correlated with altered protein expression of MMP2, MMP9, MMP12, TIMP1, TIMP2 and collagen type I and III; (iv) a considerably altered reactivity of the arterial wall closely correlated with MPs and EPC adherence; and (v) an inflammatory process characterized by augmented expression of P-Selectin, E-Selectin, von Willebrand factor, tissue factor, IL-6, MCP-1 and RANTES. Additionally, the experiments showed the potential of irbesartan to correct all altered parameters in HH and to mobilize EPCs by NO, chemokines and adhesion molecule-dependent mechanisms.
Hypertension associated with hypercholesterolemia is accompanied by structural modifications and expression of pro-inflammatory molecules by the vessel wall, the alteration of vascular tone, enhanced release of MPs and reduced EPCs; the ratio between the latter two may be considered as a marker of vascular dysfunction. Irbesartan, which exhibits a pharmacological control on the levels of MPs and EPCs, has the potential to restore homeostasis of the arterial wall.
Journal of Thrombosis and Haemostasis 02/2012; 10(4):680-91. · 6.08 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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.
Thrombosis Research 02/2012; 129(2):116-26. · 3.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Diabetes mellitus is one of the most common metabolic diseases in the world and the vascular dysfunction represents a challenging clinical problem. In diabetes, endothelial cells (ECs), lining the inner wall of blood vessels, do not function properly and contribute to impaired vascular function. Circulating endothelial progenitor cells (EPCs), the precursor of mature EC, actively participate in endothelial repair, by moving to the vascular injury site to form mature EC and new blood vessels. Knowing that the therapeutic interventions can improve only a part of EC dysfunction in diabetes, this review addresses recent findings on the use of EPCs for cell therapy. The strategies proposed in review are based on in vivo and in vitro studies and, thus, their physiological relevance is confirmed. EPC therapy shows great promise for the prevention and cure of diabetes-induced vascular dysfunction.
European journal of pharmacology 08/2011; 669(1-3):1-6. · 2.59 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Resistance to the hormones insulin and leptin are hallmarks in common for type 2 diabetes mellitus and obesity. Both conditions are associated with increased activity and expression of protein tyrosine phosphatase (PTP)1B. Therefore, inhibition of PTP1B activity or down-regulation of its expression should ameliorate insulin and leptin resistance, and may hold therapeutic utility in type 2 diabetes mellitus and obesity control. This background has motivated the fervent search for PTP1B inhibitors, carried out in the recent years. The purpose of this review is to provide the most recent advances in understanding the structural details of PTP1B molecule relevant to the interactions with inhibitors, and the progress towards compounds with enhanced membrane permeability, affinity, specificity, and potency on intracellular PTP1B; several inhibitors of benefit in type 2 diabetes mellitus and obesity control are presented and discussed.
Biochemical and Biophysical Research Communications 06/2011; 410(3):377-81. · 2.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The arterial endothelial dysfunction in aging and diabetes remains a clinical problem. We questioned the effect of the low-molecular-weight heparin, enoxaparin, on arterioles contractility in aging and in aging associated with diabetes, and investigated the involvement of the mitogen-activated protein (MAP) kinases pathway in the enoxaparin-mediated effect. The experiments were performed on the isolated resistance arteries of young (4 months old), aged (16 months old), and aged-diabetic hamsters (16 months old and 5 months since streptozotocin injection). The techniques used were myography, molecular biology, and immunoblotting. The results showed that 60 μg/ml enoxaparin has favorable effects on the arteriole reactivity in aged and aged-diabetic conditions, reducing the contractile response to 10-10 mol/l noradrenaline. The diminishment of contractility is exerted via MAP kinase pathway, and involves reduction of c-fos gene expression and of transcription factor AP-1 protein expression. These results suggest that enoxaparin preserves the arterial endothelial function in a mechanism independent of its anticoagulant activity. Understanding the signal transduction mechanisms involved in the altered contractility of vascular wall could provide useful information on the development of specific MAP kinase inhibitors with therapeutic benefits and reduced side effects.
Blood coagulation & fibrinolysis: an international journal in haemostasis and thrombosis 03/2011; 22(4):310-6. · 1.25 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Chronic venous insufficiency (CVI) is a common medical problem that may result in significant morbidity and mortality. Platelets are key players in haemostasis and thrombosis, but their role in the development of venous thrombosis is more controversial.
The purpose of this study was to investigate platelet properties in CVI and their interaction with the venular endothelium.
Human peripheral venules were explanted during leg surgery of patients with CVI and of healthy subjects (C); concurrently, the platelets were isolated from blood samples collected. The techniques used were: fluorescence and electron microscopy and Western-blotting.
Compared with the C group, the platelets of patients with CVI are activated, as demonstrated by: (i) cellular modifications, such as alteration of the discoidal shape by the development of extended cytoplasmic filopodia and changes of the cells normal ultrastructure, (ii) biochemical modifications, such as the enhanced protein levels of FAK, p85 PI3K, Akt and src, accounting for activation of alphaIIbbeta3 outside-in signaling, and (iii) apparent higher adhesion to the venular endothelium. We demonstrate in addition, that CVI is accompanied by severe modifications of the ultrastructure of the cells within the venular wall.
In CVI, platelets circulate in an activated state and may contribute to the altered dysfunctional response of the venous wall and to the development of this pathology.
[Show abstract][Hide abstract] ABSTRACT: The aim of the present study was to examine the effects of obesity alone and obesity associated with Type 2 diabetes on the structure, vascular reactivity and response to insulin of isolated human subcutaneous fat arterioles; these effects were correlated with the expression of insulin signalling proteins. Periumbilical subcutaneous adipose tissue was explanted during surgery, small arterioles (internal diameter 220 ± 40 μm) were dissected out and investigated by electron microscopy, myography and immunoblotting. Compared with the subcutaneous arterioles of lean subjects, obesity activated the endothelium, enhanced the accumulation of collagen within vascular wall and increased the sensitivity of adrenergic response; obesity also diminished eNOS (endothelial NO synthase) protein expression, NO production, and endothelium-dependent and insulin-induced vasodilatation, as well as the protein expression of both IRS (insulin receptor substrates)-1 and IRS-2 and of the downstream molecules in the insulin signalling pathway, such as PI3K (phosphoinositide 3-kinase), phospho-Akt and Akt. When obesity was associated with Type 2 diabetes, these changes were significantly augmented. In conclusion, obesity alone or obesity associated with Type 2 diabetes alters human periumbilical adipose tissue arterioles in terms of structure, function and biochemsitry, including diminished eNOS expression and reduced levels of IRS-1, IRS-2, PI3K and Akt in the insulin signalling pathway.
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to determine the effect of simultaneous hypertension and hypercholesterolemia on platelet activation, nitric oxide (NO) production and oxidative stress, and to evaluate the role of irbesartan, an angiotensin II type 1 receptor antagonist.
Golden Syrian hamsters were divided into three groups: controls, C (fed a standard diet); hypertensive-hypercholesterolemic, HH (fed a diet enriched in 3% cholesterol, 15% butter and 8% NaCl, for 4 months); and hypertensive-hypercholesterolemic treated with irbesartan, HHI (fed as HH group, plus irbesartan 10 mg kg(-1) per day, for 4 months).
Compared with the C group, platelets isolated from the HH group showed: morphological modifications; increased integrin β3 exposure and protein expression of P-selectin, FAK, PI3K, Akt and Src; reduced eNOS protein expression and NO production; higher generation of ROS, mostly produced by NADPH-oxidase, cyclooxygenase-1 (COX-1) and 12-lipoxygenase; and enhanced NAD(P)H oxidase activity and protein expression of gp91phox and p22phox subunits, 12-lipoxygenase, COX-1, cPLA(2) and PKC. Compared with the HH group, the treatment with irbesartan (HHI group) significantly attenuates the changes in all the molecules tested, reduces platelet aggregation, and improves intraplatelet redox balance.
Experimental hypertension associated with hypercholesterolemia produces major changes in morphology, signaling mechanisms and oxidative stress in blood platelets. These changes were significantly diminished by irbesartan administration, which functions as an antioxidant on platelets.
Journal of Thrombosis and Haemostasis 10/2010; 9(1):173-84. · 6.08 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This article provides an overview of the current knowledge on intraplatelet oxidative/nitrative stress, an abnormality associated with platelet activation and hyper-reactivity. The first issue discussed is related to induction of platelet endogenous stress by the molecules present within the circulating (extracellular) milieu that bathes these cells. The second issue concerns the intraplatelet oxidative/nitrative stress associated with specific pathologies or clinical procedures and action of particular molecules and platelet agonists as well as of the specialized intraplatelet milieu and its redox system; the biomarkers of endogenous oxidative/nitrative stress are also briefly outlined. Next, the association between intraplatelet oxidative/nitrative stress and the risk factors of the metabolic syndrome is presented. Then, the most recent strategies aimed at the control/regulation of platelet endogenous oxidative/nitrative stress, such as exploitation of circulating extracellular reactive oxygen species scavengers, manipulation of platelet molecules, and the use of antioxidants, are discussed. Finally, the results of studies on platelet-dependent redox mechanisms, which deserve immediate attention for potential clinical exploitation, are illustrated.
Trends in cardiovascular medicine 10/2010; 20(7):232-8. · 4.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Protein activation by phosphorylation reactions (exerted by various kinases) is a universal mechanism of signal transduction that controls the amplitude of signaling response. In physiological conditions, this mechanism is fine tuned by dephosphorylation reactions (exerted by phosphatases), that control the rate and the duration of signaling response. In this study we questioned on the in vivo effect of circulating high glucose concentration on the balance between phosphorylating kinases and dephosphorylating protein tyrosine phosphatase 1B operating in the aorta, an issue still uncovered. Experiments were conducted on Type 1 diabetic golden Syrian hamsters, at 4 weeks after streptozotocin injection (control: normal hamsters); animals were severely diabetic (plasma glucose concentration: 44020 mg/dl), the pancreatic β cells showed progressive destruction and apoptosis, and the thoracic aorta displayed dysfunctional endothelium and smooth muscle cells. In comparison with normal animals, hyperglycaemia produced the following effects on aortic signaling proteins expression: (i) did not significantly alter the protein level of insulin receptor substrate 2 (IRS2, that mediates effects of insulin, insulin-like growth factor 1, and other cytokines by acting as a molecular adaptor between diverse receptor tyrosine kinases and downstream effectors), (ii) up-regulates expression of Protein Tyrosine Phosphatase-1B (PTP-1B, that interacts with and dephosphorylates the activated insulin receptor), and (iii) down-regulates the levels of Phosphoinositide 3-kinase (PI3K, that interacts with the insulin receptor substrate and regulates intracellular glucose uptake through a series of phosphorylation events), and AKT (a member of the serine/threonine-specific protein kinase family). The imbalance in hyperglycaemia -induced phosphorylation /dephosphorylation events are likely to intervene in diabetes-associated aortic wall dysfunction.
[Show abstract][Hide abstract] ABSTRACT: We aimed to investigate whether polymorphisms LEP G-2548A and LEPR Q223R in the human leptin (LEP), and leptin receptor (LEPR) genes are associated with obesity and metabolic traits in a sample of Romanian population. Two hundred and two subjects divided in obese (body mass index, BMI30 kg/m(2)), and non-obese were included in this study. The polymorphisms were genotyped using polymerase chain reaction (PCR) followed by restriction fragment length polymorphism (RFLP) analysis. The results showed no significant differences in LEP and LEPR genotype and allele frequencies between obese and non-obese subjects. Logistic regression analysis showed that LEP -2548GG genotype presented an increased risk of obesity (p=0.013, OR=1.003, 95% CI=1.000-1.007), after adjusting for age and gender. The association analysis with metabolic syndrome quantitative traits showed that homozygous for LEP -2548G allele had significantly higher leptin levels (17.2+/-6.6 ng/ml vs. 13.2+/-4.9 ng/ml, p=0.011), and carriers of R allele had higher levels of triglycerides (p=0.017) and glucose (p=0.040), and enhanced systolic (p=0.015) and diastolic blood pressure (p=0.026), after adjustment for age, gender, and BMI. These results indicate that LEP G-2548A and LEPR Q223R SNPs may not be considered as genetic risk factors for obesity in a sample of Romanian population. However, LEP -2548GG genotype appear to be important in regulating leptin levels, whereas the LEPR 223R allele might predispose healthy subjects to develop metabolic disturbances.
Biochemical and Biophysical Research Communications 11/2009; 391(1):282-6. · 2.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Hyperglycemia stimulates a plethora of intracellular signaling pathways within the cells of the vascular wall resulting in dysfunction-associated pathologies. Most of the studies reported so far explored the effect of rather short-time exposure of smooth muscle cells to high glucose concentrations. To mimic situation in Type 2 diabetes in which vascular wall is constantly exposed to circulating hyperglycemia, we report here the long-term (7days) effect of high glucose concentration on human media artery smooth muscle cells. This consists in up-regulation of PTP1B protein expression, down-regulation of basal Akt phosphorylation, and elevation of basal ERK1/2 activation. Acute stimulation of cells in high glucose with insulin down-regulated PTP1B expression, slightly decreased ERK1/2 activity, and activated Akt, whereas oxidative stress up-regulated Akt and ERK1/2 phosphorylation. In conclusion, long-term high glucose and acute oxidative stress and insulin stimulation imbalance the expression of activated kinases Akt and ERK1/2 and of dephosphorylating PTP1B in the insulin signaling pathway.
Biochemical and Biophysical Research Communications 09/2009; 388(1):51-5. · 2.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Protein Tyrosine Phosphatases (PTPs) are important contributors to vascular cells normal function, by balancing signaling proteins activation exerted by phosphorylating kinases. Type 2 diabetes related insults, such as hyperglycemia, oxidative stress, and insulin resistance disturb the phosphorylation/dephosphorylation equilibrium towards an abnormal augmented phosphorylation of signaling proteins associated with changes in PTPs expression, enzymatic activity and interaction with cellular substrates. We briefly review here: (i) the new findings on receptor and non-receptor PTPs and their role in vascular cells, (ii) several data on oxidation and phosphorylation of these molecules in endothelial and smooth muscle cells, (iii) vascular PTPs intrinsic activity and dysregulation under the insults of diabetic milieu, and (iv) the potential use of PTPs and their inhibitors as therapeutic targets in Type 2 diabetes-associated vascular dysfunction.
Biochemical and Biophysical Research Communications 09/2009; 389(1):1-4. · 2.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Chronic venous insufficiency (CVI) results when the veins in the legs no longer pump blood back to the heart effectively. Microparticles (MPs) are small membrane vesicles released by several circulating and vascular cells upon activation or apoptosis.
The purpose of this study was to assess the subpopulations of circulating endothelial (EMPs) and platelet microparticles (PMPs) in CVI, and to disclose their contribution in mediating dysfunction of human peripheral venules.
Human peripheral venules were explanted during leg surgery on patients with CVI and on control subjects (C); concurrently, blood samples were collected and circulating MPs isolated. The techniques used were: flow cytometry, fluorescence and electron microscopy, myograph technique and western-blotting technique.
The results showed that compared with controls, patients with CVI had: (i) a marked elevation of circulating EMPs and PMPs; (ii) a structural modification of the venous wall consisting of activation of endothelial and smooth muscle cells, an abundance of intermediary filaments and synthesis of hyperplasic-multilayered basal lamina; (iii) a significantly altered reactivity of the venous wall, closely associated with EMPs and PMPs adherence; (iv) altered contractile response to noradrenaline, acetylcholine, 5-hydroxytryptamine and KCl, and an impeded relaxation in response to sodium nitroprusside; and (iv) a substantially increased protein expression of tissue factor (TF) and of P-Selectin both in the venular vascular wall and on the surface of EMPs and PMPs.
The findings indicate that CVI is accompanied by an enhanced release of EMPs and PMPs that contribute to altered dysfunctional response of the venous wall.
Journal of Thrombosis and Haemostasis 07/2009; 7(9):1566-75. · 6.08 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Type 2 diabetes mellitus induces a characteristic platelet hyperactivity that might be due to several factors including oxidative stress and abnormal intracellular Ca2+ homeostasis. Hyperhomocysteinaemia is considered a risk factor in the development of thrombosis although its effect on platelet function and the mechanisms involved are still poorly understood. Here we show that homocysteine (Hcy) induce a concentration-dependent increase in endogenous production of reactive oxygen species (ROS), which was significantly greater in platelets from diabetic patients than in controls. Platelet treatment with Hcy resulted in Ca2+ release from the dense tubular system and the acidic stores. Ca2+ mobilisation-induced by Hcy consisted in two components, an initial slow increase in intracellular free Ca2+ concentration ([Ca2+]i) and a rapid and marked increase in [Ca2+]i, the second leading to the activation of platelet aggregation. As well as ROS generation, Ca2+ mobilization and platelet aggregation were significantly greater in platelets from diabetic donors than in controls, which indicate that platelets from diabetic donors are more sensitive to Hcy. These findings, together with the hyperhomocysteinaemia reported in diabetic patients, strongly suggest that Hcy might be considered a risk factor in the development of cardiovascular complications associated to type 2 diabetes mellitus.
Journal of Cellular and Molecular Medicine 12/2008; 12(6B):2586-97. · 4.75 Impact Factor