The protective effect of superoxide dismutase mimetic M40401 on balloon injury-related neointima formation: role of the lectin-like oxidized low-density lipoprotein receptor-1

Protective and curative effects of unconjugated bilirubin on gene expression of LOX-1 and iNOS in the heart of rats receiving high-fat diet and low dose streptozotocin: a histomorphometric approach

BACKGROUND

Atherosclerosis is a chronic inflammatory condition affecting the large arteries and is a major cause of cardiovascular diseases (CVDs) globally. Increased levels of adhesion molecules in cardiac tissue serve as prognostic markers for coronary artery occlusion risk. Given the antioxidant properties of bilirubin and its inverse correlation with atherosclerosis, this study aimed to assess the beneficial effects of bilirubin on atherosclerotic indices and heart structure in high-fat diet-fed diabetic rats with atherosclerosis.

METHODS

Atherosclerosis was induced in three out of five groups of adult male Sprague Dawley rats through a 14-week period of high-fat diet (HFD) consumption and a single low dose of streptozotocin (STZ) (35 mg/kg). The atherosclerotic rats were then treated with intraperitoneal administration of 10 mg/kg/day bilirubin for either 6 or 14 weeks (treated and protected groups, respectively), or the vehicle. Two additional groups served as the control and bilirubin-treated rats. Subsequently, the mRNA expression levels of vascular cell adhesion molecule 1 (VCAM-1), intercellular adhesion molecule 1 (ICAM-1), lectin-like LDL receptor 1 (LOX-1), and the inducible nitric oxide synthase (iNOS) were analyzed using quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). Histopathological and stereological analyses were performed to assess changes in the heart structure.

RESULTS

Bilirubin significantly decreased the expression of VCAM-1, ICAM-1, LOX-1, and iNOS genes in the treated group. Moreover, bilirubin mitigated pathological damage in the left ventricle of the heart. Stereological analysis revealed a decrease in the left ventricle and myocardium volume, accompanied by an increase in vessel volume in rats treated with bilirubin.

CONCLUSION

These findings demonstrate that mild hyperbilirubinemia can protect against the progression of atherosclerosis and heart failure by improving lipid profile, modulating adhesion molecules, LOX-1, and iNOS gene expression levels.

Therapeutic Potential of Small Molecules Targeting Oxidative Stress in the Treatment of Chronic Obstructive Pulmonary Disease (COPD): A Comprehensive Review

Chronic obstructive pulmonary disease (COPD) is an increasing and major global health problem. COPD is also the third leading cause of death worldwide. Oxidative stress (OS) takes place when various reactive species and free radicals swamp the availability of antioxidants. Reactive nitrogen species, reactive oxygen species (ROS), and their counterpart antioxidants are important for host defense and physiological signaling pathways, and the development and progression of inflammation. During the disturbance of their normal steady states, imbalances between antioxidants and oxidants might induce pathological mechanisms that can further result in many non-respiratory and respiratory diseases including COPD. ROS might be either endogenously produced in response to various infectious pathogens including fungi, viruses, or bacteria, or exogenously generated from several inhaled particulate or gaseous agents including some occupational dust, cigarette smoke (CS), and air pollutants. Therefore, targeting systemic and local OS with therapeutic agents such as small molecules that can increase endogenous antioxidants or regulate the redox/antioxidants system can be an effective approach in treating COPD. Various thiol-based antioxidants including fudosteine, erdosteine, carbocysteine, and N-acetyl-L-cysteine have the capacity to increase thiol content in the lungs. Many synthetic molecules including inhibitors/blockers of protein carbonylation and lipid peroxidation, catalytic antioxidants including superoxide dismutase mimetics, and spin trapping agents can effectively modulate CS-induced OS and its resulting cellular alterations. Several clinical and pre-clinical studies have demonstrated that these antioxidants have the capacity to decrease OS and affect the expressions of several pro-inflammatory genes and genes that are involved with redox and glutathione biosynthesis. In this article, we have summarized the role of OS in COPD pathogenesis. Furthermore, we have particularly focused on the therapeutic potential of numerous chemicals, particularly antioxidants in the treatment of COPD.

Conventional and Nanotechnology Based Approaches to Combat Chronic Obstructive Pulmonary Disease: Implications for Chronic Airway Diseases

Chronic obstructive pulmonary disease (COPD) is the most prevalent obstructive lung disease worldwide characterized by decline in lung function. It is associated with airway obstruction, oxidative stress, chronic inflammation, mucus hypersecretion, and enhanced autophagy and cellular senescence. Cigarette smoke being the major risk factor, other secondary risk factors such as the exposure to air pollutants, occupational exposure to gases and fumes in developing countries, also contribute to the pathogenesis of COPD. Conventional therapeutic strategies of COPD are based on anti-oxidant and anti-inflammatory drugs. However, traditional anti-oxidant pharmacological therapies are commonly used to alleviate the impact of COPD as they have many associated repercussions such as low diffusion rate and inappropriate drug pharmacokinetics. Recent advances in nanotechnology and stem cell research have shed new light on the current treatment of chronic airway disease. This review is focused on some of the anti-oxidant therapies currently used in the treatment and management of COPD with more emphasis on the recent advances in nanotechnology-based therapeutics including stem cell and gene therapy approaches for the treatment of chronic airway disease such as COPD and asthma.

Modulation of Nitric Oxide Synthases by Oxidized LDLs: Role in Vascular Inflammation and Atherosclerosis Development

The maintenance of physiological levels of nitric oxide (NO) produced by eNOS represents a key element for vascular endothelial homeostasis. On the other hand, NO overproduction, due to the activation of iNOS under different stress conditions, leads to endothelial dysfunction and, in the late stages, to the development of atherosclerosis. Oxidized LDLs (oxLDLs) represent the major candidates to trigger biomolecular processes accompanying endothelial dysfunction and vascular inflammation leading to atherosclerosis, though the pathophysiological mechanism still remains to be elucidated. Here, we summarize recent evidence suggesting that oxLDLs produce significant impairment in the modulation of the eNOS/iNOS machinery, downregulating eNOS via the HMGB1-TLR4-Caveolin-1 pathway. On the other hand, increased oxLDLs lead to sustained activation of the scavenger receptor LOX-1 and, subsequently, to NFkB activation, which, in turn, increases iNOS, leading to EC oxidative stress. Finally, these events are associated with reduced protective autophagic response and accelerated apoptotic EC death, which activates atherosclerotic development. Taken together, this information sheds new light on the pathophysiological mechanisms of oxLDL-related impairment of EC functionality and opens new perspectives in atherothrombosis prevention.

Anagliptin inhibits neointimal hyperplasia after balloon injury via endothelial cell-specific modulation of SOD-1/RhoA/JNK signaling in the arterial wall

Intimal hyperplasia is one of the major complications after stenting, but the underlying mechanisms remain unclear. Our previous study found that the dipeptidyl peptidase IV (DPP-4) inhibitor, Anagliptin, suppresses intimal hyperplasia after balloon injury. Here, we further investigated the effects of Anagliptin on endothelial cell (EC) migration after balloon injury. The results showed that Anagliptin administration significantly reduced intimal hyperplasia by stimulating the migration of endothelial cells, but had no effect on the medial area after balloon injury. Anagliptin elevated the total plasma activity of SOD by up-regulating the level of SOD-1, but not SOD-2, after balloon injury. Meanwhile, pre-incubation with Anagliptin suppressed the hydrogen peroxide-mediated formation of oxidant species and apoptosis in HUVECs. In vitro pre-incubation with Anagliptin promoted the migration of HUVECs via the SOD-1/RhoA/JNK signaling pathway mediating the formation of F-actin. Collectively, the DPP-4 inhibitor, Anagliptin, regulates SOD-1/RhoA/ JNK-mediated HUVECs migration. The results suggest that Anagliptin could serve as a potential drug to prevent intimal hyperplasia formation after balloon injury.

Role of sLOX-1 in intracranial artery stenosis and in predicting long-term prognosis of acute ischemic stroke

OBJECTIVE

The role of sLOX-1 in acute ischemic stroke still remains unclear. This study aims to demonstrate the value of sLOX-1 in evaluating degrees of intracranial artery stenosis and to predict prognosis in stroke.

METHODS

Two hundred and seventy-two patients were included in this study and basic data were collected within 72 hr on admission. We assessed the association between sLOX-1 levels and stroke conditions in one-year duration. After adjusting for potential confounders, regression analyses were performed.

RESULTS

We found that sLOX-1 levels were increased significantly in severe patients compared to the mild stroke group (p = .011). After adjusting confounders, sLOX-1 was associated with a poor functional outcome in patients with an adjusted OR of 2. 946 (95% CI, 1.788-4.856, p < .001). There was also positive correlation between sLOX-1 levels and the degrees of intracranial artery stenosis in the different groups (p = .029).

CONCLUSIONS

Our study demonstrated that sLOX-1 levels could be used to evaluate the severity of stroke and the degrees of intracranial artery stenosis. Furthermore, sLOX-1 could be exploited to predict the long-term functional outcome of stroke.

Soluble lectin-like oxidized low-density lipoprotein receptor-1 as a novel biomarker for large-artery atherosclerotic stroke

BACKGROUND

Serum soluble lectin-like oxidized low-density lipoprotein receptor-1 (sLOX-1) has been shown associated with the progression of atherosclerosis in endothelial cells. We sought to assess whether the baseline serum sLOX-1 levels are correlated with the presence and short-term functional outcome of large-artery atherosclerotic (LAA) stroke.

METHODS

The study recruited 241 subjects, including 148 consecutive patients with acute ischemic stroke with the subtype of LAA and 93 non-stroke controls. Clinical and laboratory data, including serum concentration of sLOX-1, were collected within 24 h of admission, and the severity of LAA stroke patients was evaluated by National Institutes of Health Stroke Scale score. And functional outcome was assessed by modified Rankin Scale three months after stroke. The association between sLOX-1 level and the functional outcome at three months was analyzed by multiple logistic regression models.

RESULTS

Serum levels of sLOX-1 in the LAA stroke patients were significantly higher as compared to normal controls (2.48 ± 0.93 ng/ml vs. 2.22 ± 0.79 ng/ml in the controls, t = 2.301, p = 0.022). The levels of serum sLOX-1 in patients with good outcome were significantly lower than those with poor outcome (2.39 ± 0.94 ng/ml vs. 2.77 ± 0.84 ng/ml, p = 0.032). After adjusting for potential confounders, sLOX-1 was still an independent predictor for the function outcome with an adjusted OR of 3.39 (95% CI, 1.61-7.11, p = 0.001).

CONCLUSIONS

The serum sLOX-1 level was higher in patients with LAA stroke, and it was an independent predictor of functional outcome in patients with LAA ischemic stroke.

Oxidized LDL attenuates protective autophagy and induces apoptotic cell death of endothelial cells: Role of oxidative stress and LOX-1 receptor expression

BACKGROUND

Overproduction of oxidized-low density lipoproteins (oxyLDLs) has been found to contribute in endothelial cell (EC) dysfunction thereby leading to atherosclerosis development and progression. In particular, oxyLDLs lead to apoptotic cell death of EC via oxidative stress production, mostly subsequent to the overexpression of the scavenger receptor LOX-1. Here, we hypothesize that LOX-1 expression in EC represents a crucial event which attenuates protective autophagic response, thereby enhancing programmed endothelial cell death.

METHODS AND RESULTS

Bovine aortic endothelial cells (BAECs) in culture were exposed to oxyLDL (1-100 μM). After 48 h incubation, oxyLDL produced pronounced malondialdehyde (MDA) elevation and apoptotic cell death of BAEC as detected by FACS analysis, an effect counteracted by antioxidant N-acetyl-cysteine (NAC) as well as by the NO-donor SNAP. OxyLDL-induced apoptotic cell death was also accompanied by reduced VEGF-dependent phosphorylation of constitutive NO synthase (cNOS) in BAEC and consistent attenuation of autophagic response as detected by the expression of Beclin-1 and LC3, two reliable biomarkers of autophagy. Moreover, silencing LOX-1 receptor significantly restored LC3 expression in oxyLDL-treated BAEC, thus suggesting a key role of LOX-1 overproduction in oxyLDL-induced endothelial dysfunction.

CONCLUSIONS

OxyLDL leads to impaired NO generation and apoptotic cell death in BAECs. This effect occurs via the overexpression of LOX-1 and subsequent attenuation of protective autophagic response thereby contributing to the pathophysiology of oxyLDL-induced endothelial dysfunction which characterizes early stages of atherosclerotic process.

Sex-based differential regulation of oxidative stress in the vasculature by nitric oxide

Background

Nitric oxide (^•NO) is more effective at inhibiting neointimal hyperplasia following arterial injury in male versus female rodents, though the etiology is unclear. Given that superoxide (O₂^•−) regulates cellular proliferation, and ^•NO regulates superoxide dismutase-1 (SOD-1) in the vasculature, we hypothesized that ^•NO differentially regulates SOD-1 based on sex.

Materials and methods

Male and female vascular smooth muscle cells (VSMC) were harvested from the aortae of Sprague-Dawley rats. O₂^•− levels were quantified by electron paramagnetic resonance (EPR) and HPLC. sod-1 gene expression was assayed by qPCR. SOD-1, SOD-2, and catalase protein levels were detected by Western blot. SOD-1 activity was measured via colorimetric assay. The rat carotid artery injury model was performed on Sprague-Dawley rats ±^•NO treatment and SOD-1 protein levels were examined by Western blot.

Results

In vitro, male VSMC have higher O₂^•− levels and lower SOD − 1 activity at baseline compared to female VSMC (P < 0.05). ^•NO decreased O₂^•− levels and increased SOD − 1 activity in male (P<0.05) but not female VSMC. ^•NO also increased sod− 1 gene expression and SOD − 1 protein levels in male (P<0.05) but not female VSMC. In vivo, SOD-1 levels were 3.7-fold higher in female versus male carotid arteries at baseline. After injury, SOD-1 levels decreased in both sexes, but ^•NO increased SOD-1 levels 3-fold above controls in males, but returned to baseline in females.

Conclusions

Our results provide evidence that regulation of the redox environment at baseline and following exposure to ^•NO is sex-dependent in the vasculature. These data suggest that sex-based differential redox regulation may be one mechanism by which ^•NO is more effective at inhibiting neointimal hyperplasia in male versus female rodents.

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The baseline redox environment in the vascular is sex-dependent.

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Nitric oxide differentially affects the vascular redox environment between the sexes.

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Nitric oxide decreases superoxide (O₂^.) levels, by increasing SOD-1 activity, sod1 gene expression and SOD-1 protein levels in male vascular smooth muscle cells, but not in females.

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Sex-based differential redox regulation may be one mechanism by which is more effective at inhibiting neointimal hyperplasia in male versus female rodents.

Nitric oxide inhibits neointimal hyperplasia following vascular injury via differential, cell-specific modulation of SOD-1 in the arterial wall

Superoxide (O2(•-)) promotes neointimal hyperplasia following arterial injury. Conversely, nitric oxide ((•)NO) inhibits neointimal hyperplasia through various cell-specific mechanisms, including redox regulation. What remains unclear is whether (•)NO exerts cell-specific regulation of the vascular redox environment following arterial injury to inhibit neointimal hyperplasia. Therefore, the aim of the present study was to assess whether (•)NO exerts cell-specific, differential modulation of O2(•-) levels throughout the arterial wall, establish the mechanism of such modulation, and determine if it regulates (•)NO-dependent inhibition of neointimal hyperplasia. In vivo, (•)NO increased superoxide dismutase-1 (SOD-1) levels following carotid artery balloon injury in a rat model. In vitro, (•)NO increased SOD-1 levels in vascular smooth muscle cells (VSMC), but had no effect on SOD-1 in endothelial cells or adventitial fibroblasts. This SOD-1 increase was associated with an increase in sod1 gene expression, increase in SOD-1 activity, and decrease in O2(•-) levels. Lastly, to determine the role of SOD-1 in (•)NO-mediated inhibition of neointimal hyperplasia, we performed the femoral artery wire injury model in wild type and SOD-1 knockout (KO) mice, with and without (•)NO. Interestingly, (•)NO inhibited neointimal hyperplasia only in wild type mice, with no effect in SOD-1 KO mice. In conclusion, these data show the cell-specific modulation of O2(•-) by (•)NO through regulation of SOD-1 in the vasculature, highlighting its importance on the inhibition of neointimal hyperplasia. These results also shed light into the mechanism of (•)NO-dependent redox balance, and suggest a novel VSMC redox target to prevent neointimal hyperplasia.

Bergamot polyphenolic fraction enhances rosuvastatin-induced effect on LDL-cholesterol, LOX-1 expression and protein kinase B phosphorylation in patients with hyperlipidemia

BACKGROUND

Statins are the most commonly prescribed drugs to reduce cardiometabolic risk. Besides the well-known efficacy of such compounds in both preventing and treating cardiometabolic disorders, some patients experience statin-induced side effects. We hypothesize that the use of natural bergamot-derived polyphenols may allow patients undergoing statin treatment to reduce effective doses while achieving target lipid values. The aim of the present study is to investigate the occurrence of an enhanced effect of bergamot-derived polyphenolic fraction (BPF) on rosuvastatin-induced hypolipidemic and vasoprotective response in patients with mixed hyperlipidemia.

METHODS

A prospective, open-label, parallel group, placebo-controlled study on 77 patients with elevated serum LDL-C and triglycerides was designed. Patients were randomly assigned to a control group receiving placebo (n=15), two groups receiving orally administered rosuvastatin (10 and 20mg/daily for 30 days; n=16 for each group), a group receiving BPF alone orally (1000 mg/daily for 30 days; n=15) and a group receiving BPF (1000 mg/daily given orally) plus rosuvastatin (10mg/daily for 30 days; n=15).

RESULTS

Both doses of rosuvastatin and BPF reduced total cholesterol, LDL-C, the LDL-C/HDL-C ratio and urinary mevalonate in hyperlipidemic patients, compared to control group. The cholesterol lowering effect was accompanied by reductions of malondialdehyde, oxyLDL receptor LOX-1 and phosphoPKB, which are all biomarkers of oxidative vascular damage, in peripheral polymorphonuclear cells.

CONCLUSIONS

Addition of BPF to rosuvastatin significantly enhanced rosuvastatin-induced effect on serum lipemic profile compared to rosuvastatin alone. This lipid-lowering effect was associated with significant reductions of biomarkers used for detecting oxidative vascular damage, suggesting a multi-action enhanced potential for BPF in patients on statin therapy.

LOX-1 is a novel marker for peripheral artery disease in patients with type 2 diabetes

OBJECTIVE

The aim of this study was to investigate whether serum soluble lectin-like oxidized low-density lipoprotein receptor-1 (sLOX-1), which mediates initiation and progression of atherosclerosis in endothelial cells, could be a novel marker for peripheral artery disease (PAD) in patients with type 2 diabetes.

METHODS

We evaluated relationships of serum sLOX-1 to ankle-brachial index (ABI) and examined the association of serum sLOX-1 with PAD in 410 patients with type 2 diabetes.

RESULTS

Serum sLOX-1 was inversely correlated with ABI (r=-0.197, P<0.0001). Stepwise regression analysis demonstrated that serum sLOX-1 (β=-0.168, F=5.571, P<0.05) was independently associated with ABI, and multiple logistic regression analysis demonstrated that serum sLOX-1 (16.254 (1.237-213.651), P=0.0339) was independently associated with PAD.

CONCLUSIONS

Serum sLOX-1 is associated with ABI and it could be a novel marker for PAD in patients with type 2 diabetes.

Strategies to decrease ongoing oxidant burden in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a leading cause of mortality and morbidity globally, and its development is mainly associated with tobacco/biomass smoke-induced oxidative stress. Hence, targeting systemic and local oxidative stress with agents that can balance the antioxidant/redox system can be expected to be useful in the treatment of COPD. Preclinical and clinical trials have revealed that antioxidants/redox modulators can detoxify free radicals and oxidants, control expression of redox and glutathione biosynthesis genes, chromatin remodeling and inflammatory gene expression; and are especially useful in preventing COPD exacerbations. In this review, various novel approaches and problems associated with these approaches in COPD are reviewed.

LOX-1: a new target for therapy for cardiovascular diseases

There is much interest in the role of oxidant stress in an ever-increasing list of disease states. However, the precise mediator of oxidant stress and the stressor molecule/s have not been identified. Accordingly, trials of inhibitors of oxidant stress in animal models of disease states have met only limited success. The trials of traditional anti-oxidant vitamins have been largely unsuccessful in the treatment of a wide array of disease states in humans. Recent identification of LOX-1 in vascular endothelial cells and its activation by oxidant species have led to a marked improvement in our understanding of the pathology of several cardiovascular disease states. Here, we review the disease states where therapy targeted at LOX-1 inhibition might be helpful.

Antioxidant pharmacological therapies for COPD

Increased oxidative stress occurs in the lungs and systemically in COPD, which plays a role in many of the pathogenic mechanisms in COPD. Hence, targeting local lung and systemic oxidative stress with agents that modulate the antioxidants/redox system or boost endogenous antioxidants would be a useful therapeutic approach in COPD. Thiol antioxidants (N-acetyl-l-cysteine [NAC] and N-acystelyn, carbocysteine, erdosteine, and fudosteine) have been used to increase lung thiol content. Modulation of cigarette smoke (CS) induced oxidative stress and its consequent cellular changes have also been reported to be effected by synthetic molecules, such as spin traps (α-phenyl-N-tert-butyl nitrone), catalytic antioxidants (superoxide dismutase [ECSOD] mimetics), porphyrins, and lipid peroxidation and protein carbonylation blockers/inhibitors (edaravone and lazaroids/tirilazad). Preclinical and clinical trials have shown that these antioxidants can reduce oxidative stress, affect redox and glutathione biosynthesis genes, and proinflammatory gene expression. In this review the approaches to enhance lung antioxidants in COPD and the potential beneficial effects of antioxidant therapy on the course of the disease are discussed.

Pharmacological antioxidant strategies as therapeutic interventions for COPD

Cigarette/tobacco smoke/biomass fuel-induced oxidative and aldehyde/carbonyl stress are intimately associated with the progression and exacerbation of chronic obstructive pulmonary disease (COPD). Therefore, targeting systemic and local oxidative stress with antioxidants/redox modulating agents, or boosting the endogenous levels of antioxidants are likely to have beneficial effects in the treatment/management of COPD. Various antioxidant agents, such as thiol molecules (glutathione and mucolytic drugs, such as N-acetyl-L-cysteine and N-acystelyn, erdosteine, fudosteine, ergothioneine, and carbocysteine), have been reported to modulate various cellular and biochemical aspects of COPD. These antioxidants have been found to scavenge and detoxify free radicals and oxidants, regulate of glutathione biosynthesis, control nuclear factor-kappaB (NF-kappaB) activation, and hence inhibiting inflammatory gene expression. Synthetic molecules, such as specific spin traps like α-phenyl-N-tert-butyl nitrone, a catalytic antioxidant (ECSOD mimetic), porphyrins (AEOL 10150 and AEOL 10113), and a superoxide dismutase mimetic M40419, iNOS and myeloperoxidase inhibitors, lipid peroxidation inhibitors/blockers edaravone, and lazaroids/tirilazad have also been shown to have beneficial effects by inhibiting cigarette smoke-induced inflammatory responses and other carbonyl/oxidative stress-induced cellular alterations. A variety of oxidants, free radicals, and carbonyls/aldehydes are implicated in the pathogenesis of COPD, it is therefore, possible that therapeutic administration or supplementation of multiple antioxidants and/or boosting the endogenous levels of antioxidants will be beneficial in the treatment of COPD. This review discusses various novel pharmacological approaches adopted to enhance lung antioxidant levels, and various emerging beneficial and/or prophylactic effects of antioxidant therapeutics in halting or intervening the progression of COPD. This article is part of a Special Issue entitled: Antioxidants and Antioxidant Treatment in Disease.

Oxidative stress and lectin-like ox-LDL-receptor LOX-1 in atherogenesis and tumorigenesis

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) has been identified as a major receptor for oxidized low-density lipoprotein (ox-LDL) in endothelial cells, monocytes, platelets, cardiomyocytes, and vascular smooth muscle cells. Its expression is minimal under physiological conditions but can be induced under pathological conditions. The upregulation of LOX-1 by ox-LDL appears to be important for physiologic processes, such as endothelial cell proliferation, apoptosis, and endothelium remodeling. Pathophysiologic effects of ox-LDL in atherogenesis have also been firmly established, including endothelial cell dysfunction, smooth muscle cell growth and migration, monocyte transformation into macrophages, and finally platelet aggregation-seen in atherogenesis. Recent studies show a positive correlation between increased serum ox-LDL levels and an increased risk of colon, breast, and ovarian cancer. As in atherosclerosis, ox-LDL and its receptor LOX-1 activate the inflammatory pathway through nuclear factor-kappa B, leading to cell transformation. LOX-1 is important for maintaining the transformed state in developmentally diverse cancer cell lines and for tumor growth, suggesting a molecular connection between atherogenesis and tumorigenesis.

Antioxidant therapeutic advances in COPD

Chronic obstructive pulmonary disease (COPD) is associated with a high incidence of morbidity and mortality. Cigarette smoke-induced oxidative stress is intimately associated with the progression and exacerbation of COPD and therefore targeting oxidative stress with antioxidants or boosting the endogenous levels of antioxidants is likely to have beneficial outcome in the treatment of COPD. Among the various antioxidants tried so far, thiol antioxidants and mucolytic agents, such as glutathione, N-acetyl-L-cysteine, N-acystelyn, erdosteine, fudosteine and carbocysteine; Nrf2 activators; and dietary polyphenols (curcumin, resveratrol, and green tea catechins/quercetin) have been reported to increase intracellular thiol status along with induction of GSH biosynthesis. Such an elevation in the thiol status in turn leads to detoxification of free radicals and oxidants as well as inhibition of ongoing inflammatory responses. In addition, specific spin traps, such as alpha-phenyl-N-tert-butyl nitrone, a catalytic antioxidant (ECSOD mimetic), porphyrins (AEOL 10150 and AEOL 10113), and a SOD mimetic M40419 have also been reported to inhibit cigarette smoke-induced inflammatory responses in vivo in the lung. Since a variety of oxidants, free radicals and aldehydes are implicated in the pathogenesis of COPD, it is possible that therapeutic administration of multiple antioxidants and mucolytics will be effective in management of COPD. However, a successful outcome will critically depend upon the choice of antioxidant therapy for a particular clinical phenotype of COPD, whose pathophysiology should be first properly understood. This article will review the various approaches adopted to enhance lung antioxidant levels, antioxidant therapeutic advances and recent past clinical trials of antioxidant compounds in COPD.

Oxidative stress in prehypertension: rationale for antioxidant clinical trials

Prehypertension has been recently described as an independent category of blood pressure. Mounting evidence suggests that blood pressure in the prehypertensive range is associated with an increased risk of developing hypertension and cardiovascular disease. Several reports have assigned a critical role for oxidative stress in these disease processes. This review focuses on the clinical and experimental studies done in prehypertension and hypertension within the context of oxidative stress. This article also provides insights into why diverse therapeutic interventions, which have in common the ability to reduce oxidative stress, can impede or delay the onset of hypertension in prehypertension subjects.

The protective effect of bergamot oil extract on lecitine-like oxyLDL receptor-1 expression in balloon injury-related neointima formation

Lectin-like oxyLDL receptor-1 (LOX-1) has recently been suggested to be involved in smooth muscle cell (SMC) proliferation and neointima formation in injured blood vessels. This study evaluates the effect of the nonvolatile fraction (NVF), the antioxidant component of bergamot essential oil (BEO), on LOX-1 expression and free radical generation in a model of rat angioplasty. Common carotid arteries injured by balloon angioplasty were removed after 14 days for histopathological, biochemical, and immunohistochemical studies. Balloon injury led to a significant restenosis with SMC proliferation and neointima formation, accompanied by increased expression of LOX-1 receptor, malondialdehyde and superoxide formation, and nitrotyrosine staining. Pretreatment of rats with BEO-NVF reduced the neointima proliferation together with free radical formation and LOX-1 expression in a dose-dependent manner. These results suggest that natural antioxidants may be relevant in the treatment of vascular disorders in which proliferation of SMCs and oxyLDL-related endothelial cell dysfunction are involved.

Basic mechanisms of oxidative stress and reactive oxygen species in cardiovascular injury

The development of vascular disease has its origins in an initial insult to the vessel wall by biological or mechanical factors. The disruption of homeostatic mechanisms leads to alteration of the original architecture of the vessel and its biological responsiveness, contributing to acute or chronic diseases such as stroke, hypertension, and atherosclerosis. Endothelial dysfunction, macrophage infiltration of the vessel wall, and proliferation and migration of smooth muscle cells all involve different types of reactive oxygen species produced by various vessel wall components. Although basic science and animal research have clearly established the role of reactive oxygen species in the progression of vascular disease, the failure of clinical trials with antioxidant compounds has underscored the need for better antioxidant therapies and a more thorough understanding of the role of reactive oxygen species in cardiovascular physiology and pathology.

Role of poly(ADP-ribose) polymerase 1 (PARP-1) in cardiovascular diseases: the therapeutic potential of PARP inhibitors

Accumulating evidence suggests that the reactive oxygen and nitrogen species are generated in cardiomyocytes and endothelial cells during myocardial ischemia/reperfusion injury, various forms of heart failure or cardiomyopathies, circulatory shock, cardiovascular aging, diabetic complications, myocardial hypertrophy, atherosclerosis, and vascular remodeling following injury. These reactive species induce oxidative DNA damage and consequent activation of the nuclear enzyme poly(ADP-ribose) polymerase 1 (PARP-1), the most abundant isoform of the PARP enzyme family. PARP overactivation, on the one hand, depletes its substrate, NAD+, slowing the rate of glycolysis, electron transport, and ATP formation, eventually leading to the functional impairment or death of the endothelial cells and cardiomyocytes. On the other hand, PARP activation modulates important inflammatory pathways, and PARP-1 activity can also be modulated by several endogenous factors such as various kinases, purines, vitamin D, thyroid hormones, polyamines, and estrogens, just to mention a few. Recent studies have demonstrated that pharmacological inhibition of PARP provides significant benefits in animal models of cardiovascular disorders, and novel PARP inhibitors have entered clinical development for various cardiovascular indications. Because PARP inhibitors can enhance the effect of anticancer drugs and decrease angiogenesis, their therapeutic potential is also being explored for cancer treatment. This review discusses the therapeutic effects of PARP inhibitors in myocardial ischemia/reperfusion injury, various forms of heart failure, cardiomyopathies, circulatory shock, cardiovascular aging, diabetic cardiovascular complications, myocardial hypertrophy, atherosclerosis, vascular remodeling following injury, angiogenesis, and also summarizes our knowledge obtained from the use of PARP-1 knockout mice in the various preclinical models of cardiovascular diseases.

Nitric oxide and peroxynitrite in health and disease

The discovery that mammalian cells have the ability to synthesize the free radical nitric oxide (NO) has stimulated an extraordinary impetus for scientific research in all the fields of biology and medicine. Since its early description as an endothelial-derived relaxing factor, NO has emerged as a fundamental signaling device regulating virtually every critical cellular function, as well as a potent mediator of cellular damage in a wide range of conditions. Recent evidence indicates that most of the cytotoxicity attributed to NO is rather due to peroxynitrite, produced from the diffusion-controlled reaction between NO and another free radical, the superoxide anion. Peroxynitrite interacts with lipids, DNA, and proteins via direct oxidative reactions or via indirect, radical-mediated mechanisms. These reactions trigger cellular responses ranging from subtle modulations of cell signaling to overwhelming oxidative injury, committing cells to necrosis or apoptosis. In vivo, peroxynitrite generation represents a crucial pathogenic mechanism in conditions such as stroke, myocardial infarction, chronic heart failure, diabetes, circulatory shock, chronic inflammatory diseases, cancer, and neurodegenerative disorders. Hence, novel pharmacological strategies aimed at removing peroxynitrite might represent powerful therapeutic tools in the future. Evidence supporting these novel roles of NO and peroxynitrite is presented in detail in this review.

Endothelial dysfunction: a multifaceted disorder (The Wiggers Award Lecture)

Endothelial cells synthesize and release various factors that regulate angiogenesis, inflammatory responses, hemostasis, as well as vascular tone and permeability. Endothelial dysfunction has been associated with a number of pathophysiological processes. Oxidative stress appears to be a common denominator underlying endothelial dysfunction in cardiovascular diseases. However, depending on the pathology, the vascular bed studied, the stimulant, and additional factors such as age, sex, salt intake, cholesterolemia, glycemia, and hyperhomocysteinemia, the mechanisms underlying the endothelial dysfunction can be markedly different. A reduced bioavailability of nitric oxide (NO), an alteration in the production of prostanoids, including prostacyclin, thromboxane A2, and/or isoprostanes, an impairment of endothelium-dependent hyperpolarization, as well as an increased release of endothelin-1, can individually or in association contribute to endothelial dysfunction. Therapeutic interventions do not necessarily restore a proper endothelial function and, when they do, may improve only part of these variables.

Oxidative stress in asthma and COPD: antioxidants as a therapeutic strategy

Asthma and chronic obstructive pulmonary disease (COPD) are inflammatory lung diseases that are characterized by systemic and chronic localized inflammation and oxidative stress. Sources of oxidative stress arise from the increased burden of inhaled oxidants, as well as elevated amounts of reactive oxygen species (ROS) released from inflammatory cells. Increased levels of ROS, either directly or via the formation of lipid peroxidation products, may play a role in enhancing the inflammatory response in both asthma and COPD. Moreover, in COPD it is now recognized as the main pathogenic factor for driving disease progression and increasing severity. ROS and lipid peroxidation products can influence the inflammatory response at many levels through its impact on signal transduction mechanisms, activation of redox-sensitive transcriptions factors, and chromatin regulation resulting in pro-inflammatory gene expression. It is this impact of ROS on chromatin regulation by reducing the activity of the transcriptional co-repressor, histone deacetylase-2 (HDAC-2), that leads to the poor efficacy of corticosteroids in COPD, severe asthma, and smoking asthmatics. Thus, the presence of oxidative stress has important consequences for the pathogenesis, severity, and treatment of asthma and COPD. However, for ROS to have such an impact, it must first overcome a variety of antioxidant defenses. It is likely, therefore, that a combination of antioxidants may be effective in the treatment of asthma and COPD. Various approaches to enhance the lung antioxidant screen and clinical trials of antioxidant compounds are discussed.

Expression of lectin-like oxidized LDL receptor-1 in smooth muscle cells after vascular injury

Lectin-like oxidized LDL receptor-1 (LOX-1) is an oxidized LDL receptor, and its role in restenosis after angioplasty remains unknown. We used a balloon-injury model of rabbit aorta, and reverse transcription-polymerase chain reaction revealed that LOX-1 mRNA expression was modest in the non-injured aorta, reached a peak level 2 days after injury, and remained elevated until 24 weeks after injury. Immunohistochemistry and in situ hybridization showed that LOX-1 was not detected in the media of non-injured aorta but expressed in both medial and neointimal smooth muscle cells (SMC) at 2 and 24 weeks after injury. Low concentrations of ox-LDL (10 microg/mL) stimulated the cultured SMC proliferation, which was inhibited by antisense oligonucleotides of LOX-1 mRNA. Double immunofluorescence staining showed the colocalization of LOX-1 and proliferating cell nuclear antigen in human restenotic lesion. These results suggest that LOX-1 mediates ox-LDL-induced SMC proliferation and plays a role in neointimal formation after vascular injury.