Giuseppina Basta

At Least 2 Distinct Pathways Generating Reactive Oxygen Species Mediate Vascular Cell Adhesion Molecule-1 Induction by Advanced Glycation End Products

Objective—The interaction of advanced glycation end products (AGEs) with their main receptor RAGE in endothelial cells induces intracellular generation of reactive oxygen species (ROS) and the expression of vascular cell adhesion molecule (VCAM)-1. We investigated the role of distinct sources of ROS, including the mitochondrial electron transport chain, NAD(P)H oxidase, xanthine oxidase, and arachidonic acid metabolism, in AGE-induced VCAM-1 expression. Methods and Results—The induction of ROS and VCAM-1 by AGEs in cultured human umbilical vein endothelial cells was specifically blocked by an anti-RAGE antibody. The inhibition of NAD(P)H oxidase by apocynin and diphenylene iodonium, and of the mitochondrial electron transport system at complex II by thenoyltrifluoroacetone (TTFA), significantly inhibited both AGE-induced ROS production and VCAM-1 expression, whereas these effects were potentiated by rotenone and antimycin A, specific inhibitors of mitochondrial complex I and III, respectively. The inhibition of Cu/Zn superoxide dismutase inhibited both ROS and VCAM-1 induction, indicating that H2O2 by this source is involved as a mediator of VCAM-1 expression by AGEs. Conclusions—Altogether, these results demonstrate that ROS generated by both NAD(P)H-oxidase and the mitochondrial electron transport system are involved in AGE signaling through RAGE, and indicate potential targets for the inhibition of the atherogenic signals triggered by AGE-RAGE interaction.

Ectopic fat and cardiovascular disease: what is the link?

AIM of this paper is to review the recent literature on the relationship between ectopic fat accumulation and cardiovascular disease. DATA SYNTHESIS Ectopic fat is an important predictor of metabolic (in particular insulin resistance) and cardiovascular disease, carrying more risk than general fat accumulation. Recent studies have shown a link between ectopic fat accumulation, as cardiac (epicardial or intra-myocardial fat) and/or visceral and/or hepatic fat, and development of atherosclerosis, coronary heart disease and hypertension. CONCLUSIONS Ectopic fat accumulation is not only a marker of cardiometabolic disease, since through the release of adipocitokines, lipotoxic and glucotoxic agents, participates in the crosstalk with insulin-sensitive organs leading to metabolic, cardiac and vascular dysfunctions.

Soluble receptor for advanced glycation end products in COPD: relationship with emphysema and chronic cor pulmonale: a case-control study.

BackgroundThe receptor for advanced glycation end products (RAGE) is a multiligand signal transduction receptor that can initiate and perpetuate inflammation. Its soluble isoform (sRAGE) acts as a decoy receptor for RAGE ligands, and is thought to afford protection against inflammation. With the present study, we aimed at determining whether circulating sRAGE is correlated with emphysema and chronic cor pulmonale in chronic obstructive pulmonary disease (COPD).MethodsIn 200 COPD patients and 201 age- and sex-matched controls, we measured lung function by spirometry, and sRAGE by ELISA method. We also measured the plasma levels of two RAGE ligands, N-epsilon-carboxymethyl lysine and S100A12, by ELISA method. In the COPD patients, we assessed the prevalence and severity of emphysema by computed tomography (CT), and the prevalence of chronic cor pulmonale by echocardiography. Multiple quantile regression was used to assess the effects of emphysema, chronic cor pulmonale, smoking history, and comorbid conditions on the three quartiles of sRAGE.ResultssRAGE was significantly lower (p = 0.007) in COPD patients (median 652 pg/mL, interquartile range 484 to 1076 pg/mL) than in controls (median 869 pg/mL, interquartile range 601 to 1240 pg/mL), and was correlated with the severity of emphysema (p < 0.001), the lower the level of sRAGE the greater the degree of emphysema on CT. The relationship remained statistically significant after adjusting for smoking history and comorbid conditions. In addition, sRAGE was significantly lower in COPD patients with chronic cor pulmonale than in those without (p = 0.002). Such difference remained statistically significant after adjusting for smoking history, comorbidities, and emphysema severity. There was no significant difference in the plasma levels of the two RAGE ligands between cases and controls.ConclusionssRAGE is significantly lower in patients with COPD than in age- and sex-matched individuals without airflow obstruction. Emphysema and chronic cor pulmonale are independent predictors of reduced sRAGE in COPD.

An update on advanced glycation endproducts and atherosclerosis.

Advanced glycation endproducts (AGEs) are a group of modified molecular species formed by nonenzymatic reactions between the aldehydic group of reducing sugars with proteins, lipids, or nucleic acids. Formation and accumulation of AGEs are related to the aging process and are accelerated in diabetes. AGEs are generated in hyperglycemia, but their production also occurs in settings characterized by oxidative stress and inflammation. These species promote vascular damage and acceleration of atherosclerotic plaque progression mainly through two mechanisms: directly, altering the functional properties of vessel wall extracellular matrix molecules, or indirectly, through activation of cell receptor‐dependent signaling. Interaction between AGEs and the key receptor for AGEs (RAGE), a transmembrane signaling receptor which is present in all cells relevant to atherosclerosis, alters cellular function, promotes gene expression, and enhances the release of proinflammatory molecules. The importance of the AGE‐RAGE interaction and downstream pathways, leading to vessel wall injury and plaque development, has been amply established in animal studies. Moreover, the deleterious link of AGEs with diabetic vascular complications has been suggested in many human studies. Blocking the vicious cycle of AGE‐RAGE axis signaling may be essential in controlling and preventing cardiovascular complications. In this article, we review the pathogenetic role of AGEs in the development, progression and instability of atherosclerosis, and the potential targets of this biological system for the prevention and treatment of cardiovascular disease.

Circulating soluble receptor of advanced glycation end product inversely correlates with atherosclerosis in patients with chronic kidney disease

The soluble receptor of advanced glycation end product (sRAGE) prevents vascular damage in experimental animal models, and observational studies in the general population support the hypothesis that sRAGE may exert a protective role on the vasculature. To test this in patients with chronic kidney disease, we determined the relationship between plasma sRAGE and carotid atherosclerosis in 142 patients with an average estimated glomerular filtration rate (eGFR) of 32 ml/min per 1.73 m(2) and 49 healthy control individuals matched for age and gender. Plasma sRAGE was significantly higher in patients with chronic kidney disease than in the control cohort. In an aggregate analysis of the patients and controls, there was a significant inverse relationship between eGFR and sRAGE, with a breakpoint in the regression line at 64 ml/min per 1.73 m(2). Significant inverse relationships were found for sRAGE to intima-media thickness and plaque number in the patients with chronic kidney disease, but no such associations were found in the controls. On covariance analysis, the slopes of intima-media thickness and plaque number to sRAGE were significantly steeper in patients with chronic kidney disease than in the controls. Furthermore, a significant interaction was found between sRAGE and smoking for predicting atherosclerotic plaques in patients with chronic kidney disease. The pathophysiological significance of this correlation will have to await more mechanistic studies.

What is the role of the receptor for advanced glycation end products–ligand axis in liver injury?†

Multiligand receptor for advanced glycation end products (RAGE) is expressed in a wide variety of tissues, including the liver. Interactions with its ligands lead to cellular activation and thus prolonged inflammation and apoptosis. RAGE also exists in a soluble, truncated isoform called soluble RAGE, which has the same ligand‐binding specificity as membrane‐RAGE; acting as decoy, it can contribute to the removal/neutralization of circulating ligands and the resultant reduction of signaling pathway activation. Experimental and clinical studies have highlighted the idea that the RAGE‐ligand axis is involved in the development of liver fibrosis, inflammation, and regeneration after a massive injury and in the setting of liver transplantation. The involvement of the RAGE‐ligand axis in vascular disease, diabetes, cancer, and neurodegeneration is well established, but it still needs to be clarified in the setting of liver diseases. We present a review of the recent literature on this receptor in surgical and clinical settings involving the liver, and we highlight the open issues and possible directions of future research. Liver Transpl 17:633‐640, 2011.

Therapeutic effect of diagnostic ultrasound on enzymatic thrombolysis An in vitro study on blood of normal subjects and patients with coronary artery disease

If delivered at elevated intensity, ultrasound potentiates enzymatic clot dissolution; however, an elevated acoustic intensity damages vascular wall and favors reocclusion. This studys aim was to investigate whether exposure to high-frequency, low-intensity ultrasound - generated by a diagnostic scanner -enhances enzymatic thrombolysis, and if this effect differs in clots from blood of normal subjects and of patients with coronary artery disease (CAD). Venous blood samples were drawn from 10 healthy volunteers and from 10 CAD patients on chronic medical treatment, which also included aspirin. Each sample generated 2 radiolabelled clots, which were positioned in 2 in vitro models filled with human plasma recirculating at 37 degrees. One clot was exposed to acetyl salicylic acid (60 microg/ml), tissue plasminogen activator (3 microg/ml) and heparin (1 IU/ml), while the other was exposed to the same medications plus ultra-sound (2.5 MHz, mechanical index = 1.0) for 3 hours. Enzymatic thrombolysis was measured as solubilization of radiolabel. Normal subjects and patients did not significantly differ as to coagulation parameters, weight, volume and density of the clots, and fibrinolytic activity (p = 0.794). Ultrasound exposure did not influence thrombolysis in clots of normal subjects (p = 0.367), while it enhanced the dissolution of clots of CAD patients (p = 0.013). The enhancement was equal to 51% at 5 minutes, 32% at 15 minutes, 27% at 30 minutes, 20% at 1 hour and 19% at 3 hours (p < 0.05). Diagnostic ultrasound enhances enzymatic dissolution of clots generated from the blood of CAD patients, likely due to chronic treatment and in particular to aspirin.

Circulating soluble receptor for advanced glycation end-product levels are decreased in patients with calcific aortic valve stenosis

OBJECTIVE It has been suggested that atherosclerotic mechanisms are involved in the pathogenesis of aortic valve stenosis (AVS). We hypothesised that low levels of the soluble receptor for advanced glycation end-products (sRAGE) might be associated with AVS due to its clinical and pathological associations with atherosclerosis. METHODS We enrolled 75 consecutive patients with severe AVS scheduled for surgical aortic valve replacement and 39 controls without AVS matched for age and gender. Besides the traditional risk factors, we evaluated plasma levels of sRAGE, C-reactive protein (CRP) and IL-6. All patients underwent transthoracic echocardiography, carotid arteries ultrasound scan and coronary angiography. The aortic and coronary calcium by multislice computed tomography was assessed in AVS patients. RESULTS The values of sRAGE were significantly lower (p<0.01) in AVS patients than in controls, while the CRP levels were significantly higher (p<0.05) in AVS patients than in controls. In AVS patients the sRAGE levels correlated inversely with age, cholesterol levels and coronary calcification. In all study subjects, we found an inverse correlation between circulating sRAGE and the number of echographically assessed sites of calcification (ANOVA, p<0.0001). In multivariable logistic regression analysis after adjustment for potential confounders, the sRAGE levels were significantly and independently associated with the risk of AVS (OR=0.997, 95% CI=0.994-1.000, p=0.048). CONCLUSION Since sRAGE could exert antiatherogenic effects by preventing inflammatory responses mediated by cell surface RAGE activation, low levels in AVS patients indicate that ligand-RAGE axis could contribute to pathogenesis of AVS.

Effect of the administration of n-3 polyunsaturated fatty acids on circulating levels of microparticles in patients with a previous myocardial infarction

Background Increased levels of microparticles exposing tissue factor circulate in the blood of patients with coronary heart disease, possibly disseminating their pro-thrombotic and pro-inflammatory potential. Because diets rich in n-3 (polyunsaturated) fatty acids have been associated with reduced incidence of coronary heart disease-related events, we investigated the in vivo effects of treatments with n-3 fatty acids on levels of circulating microparticles and their tissue factor- dependent procoagulant activity in patients with a previous myocardial infarction. Design and Methods Forty-six post-myocardial infarction patients were assigned to receive either 5.2 g of n-3 fatty acids daily (n=23) or an olive oil placebo (n=23) for 12 weeks. Circulating microparticles were isolated from peripheral blood. The number of microparticles, their cellular source and tissue factor antigen were determined by flow cytometry, and their procoagulant potential assayed by a fibrin generation test. Results The total number of microparticles, endothelium-derived microparticles and microparticle tissue factor antigen were not significantly different between the two groups. However, the number of platelet-derived microparticles [from a median of 431 (126–1796, range) ×106/L to a median of 226 (87–677, range)] ×106/L and monocyte-derived microparticles [from a median of 388 (9–1681, range) ×106/L to a median of 265 (7–984, range) ×106/L] in plasma were significantly (p<0.05) decreased by n-3 fatty acids, while they were unchanged in the placebo group. Total microparticle tissue factor-procoagulant activity was also reduced in the n-3 fatty acid group compared to that in the placebo group. Conclusions Treatment with n-3 fatty acids after myocardial infarction exerts favorable effects on levels of platelet- and monocyte-derived microparticles, thus possibly explaining some of the anti-inflammatory and anti-thrombotic properties of these natural compounds.

The effect of Ginkgo biloba in isolated ischemic/reperfused rat heart: a link between vitamin E preservation and prostaglandin biosynthesis.

The effect of Ginkgo biloba extract (EGb 761) was studied in rat hearts submitted to ischemia/reperfusion. Isolated hearts perfused in Langendorff mode were subjected to 60 minutes of global ischemia and 15 minutes of reperfusion. EGb 761 was administered by chronic or acute treatment: intra-peritoneal injections of 5 mg/Kg extract for 5 days, or 100 mg /L extract addition to the perfusion buffer, respectively. In hearts not treated with EGb 761, ischemia induced a 20% decrease in the concentration of membrane α-tocopherol. This effect was not worsened by reperfusion. α-tocopherol consumption was accompanied by about 650% increase in 6-ketoPGF1α release within 3 minutes of reperfusion. Moreover, ischemia induced activation of transcription factor NF-κB, as compared with the untreated group. In both chronic and acute treatment with EGb 761, heart concentration of α-tocopherol was completely spared during ischemia as much as after reperfusion, and a significant decrease of 6-ketoPGF1α release was observed at 3 minutes of reperfusion. Nuclear translocation of NF-κB was lowered during ischemia. EGb 761 might act as direct free radical scavenger or as tocopheryl radical recycler; in both cases sparing membrane vitamin E should affect phospholipase A2 activity. Finally, EGb 761, by lowering ROS produced during ischemia, challenges nuclear translocation of NF-κB.