Serena Del Turco

The omega-3 fatty acid docosahexaenoate attenuates endothelial cyclooxygenase-2 induction through both NADP(H) oxidase and PKCε inhibition

A high intake of the omega-3 fatty acid docosahexaenoate [docosahexaenoic acid (DHA)] has been associated with systemic antiinflammatory effects and cardiovascular protection. Cyclooxygenase (COX)-2 is responsible for the overproduction of prostaglandins (PG) at inflammatory sites, and its expression is increased in atheroma. We studied the effects of DHA on COX-2 expression and activity in human saphenous vein endothelial cells challenged with proinflammatory stimuli. A ≥24-h exposure to DHA reduced COX-2 expression and activity induced by IL-1, without affecting COX-1 expression. DHA effect depended on the NF-κB-binding site in the COX-2 promoter. EMSAs confirmed that DHA attenuated NF-κB activation. Because MAPK, PKC, and NAD(P)H oxidase all participate in IL-1-mediated COX-2 expression, we also tested whether these enzymes were involved in DHA effects. Western blots showed that DHA blocked nuclear p65 NF-κB subunit translocation by decreasing cytokine-stimulated reactive oxygen species and ERK1/2 activation by effects on both NAD(P)H oxidase and PKCε activities. Finally, to address the question whether DHA itself or DHA-derived products were responsible for these effects, we inhibited the most important enzymes involved in polyunsaturated fatty acid metabolism, showing that 15-lipoxygenase-1 products mediate part of DHA effects. These studies provide a mechanistic basis for antiinflammatory and possibly plaque-stabilizing effects of DHA

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.

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.

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.

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.

Transferrin-conjugated boron nitride nanotubes: protein grafting, characterization, and interaction with human endothelial cells.

In this paper we report on a covalent grafting of boron nitride nanotubes with human transferrin. After silanization of the nanotube wall, transferrin was linked to the nanotubes through carbamide binding. The obtained transferrin-conjugated boron nitride nanotubes (tf-BNNTs) resulted stable in aqueous environments and were characterized in terms of scanning electron microscopy, transmission electron microscopy, size distribution analysis and Z-potential measurement. Effective covalent grafting of transferrin was demonstrated by Fourier transform infrared spectroscopy and UV-Vis spectrophotometry. The obtained tf-BNNTs were thereafter tested on human umbilical vein endothelial cells (HUVECs); in particular cellular up-take was investigated by confocal, scanning and transmission electron microscopy, demonstrating the key role of transferrin during the internalization process. Here reported for the first time in the literature, the covalent BNNT functionalization with a targeting ligand represents a fundamental step towards BNNT exploitation as smart and selective nanocarriers in a number of nanomedicine applications.

Cytocompatibility evaluation of gum Arabic-coated ultra-pure boron nitride nanotubes on human cells

AIM Boron nitride nanotubes (BNNTs) are tubular nanoparticles with a structure analogous to that of carbon nanotubes, but with B and N atoms that completely replace the C atoms. Many favorable results indicate BNNTs as safe nanomaterials; however, important concerns have recently been raised about ultra-pure, long (~10 µm) BNNTs tested on several cell types. MATERIALS & METHODS Here, we propose additional experiments with the same BNNTs, but shortened (~1.5 µm) with a homogenization/sonication treatment that allows for their dispersion in gum Arabic aqueous solutions. Obtained BNNTs are tested on human endothelial and neuron-like cells with several independent biocompatibility assays. Moreover, for the first time, their strong sum-frequency generation signal is exploited to assess the cellular uptake. RESULTS & CONCLUSION Our data demonstrate no toxic effects up to concentrations of 20 µg/ml, once more confirming biosafety of BNNTs, and again highlighting that nanoparticle aspect ratio plays a key role in the biocompatibility evaluation.

Cytocompatibility evaluation of glycol-chitosan coated boron nitride nanotubes in human endothelial cells.

Boron nitride nanotubes (BNNTs) are intriguing nanomaterials with a wide range of potential biomedical applications. The assessment of BNNT interactions with biological systems, at both the cellular and subcellular levels, is an essential starting point for determining their bio-safety. We explore the effects of increasing concentrations of GC-BNNTs (0-100 μg/mL) on human vein endothelial cells (HUVECs), testing cell toxicity, proliferation, cytoskeleton integrity, cell activation and DNA damage. No significant changes were observed in cell viability, cytoskeleton integrity or DNA damage. Only a modest reduction in cell viability, tested by trypan blue assay, and the increased expression of vascular adhesion molecule-1, a marker of cell activation, were detected at the highest concentration used (100 μg/mL). Taken together, these findings indicate that GC-BNNTs do not affect endothelial cell biology, and are a promising first step in further investigation of their application potential in vascular targeting, imaging, and drug delivery.

The Mediterranean Lifestyle as a Non-Pharmacological and Natural Antioxidant for Healthy Aging

Oxidative stress has been suggested to affect age-associated physiological dysfunction. Therefore, it is speculated that antioxidant supplements could have a potential role in preventing age-related diseases and death. Among different dietary habits, the highly antioxidant Mediterranean dietary pattern, which includes high vegetable and fruit intake, consumption of legumes, cereals, and fish, low intake of meat and dairy derivatives, moderate red wine consumption, and use of extra-virgin olive oil, is characterized by other aspects than food, such as conviviality, sensory stimulation, socialization, biodiversity, and seasonality that can reinforce the Mediterranean diet’s (MeD) beneficial effects on wellbeing, quality of life, and healthy aging. The present review aims to discuss available data on the relationship between oxidative stress and aging, biomarkers of oxidative stress status, protective effects of the MeD, and the adoption of the Mediterranean lifestyle as a non-pharmacological and natural tool to cope with oxidative stress damage for a longer life span, and—even more important—healthy aging beyond the biological, psychological, and social challenges that old age entails.