Changes in expression of antioxidant enzymes affect cell-mediated LDL oxidation and oxidized LDL-induced apoptosis in mouse aortic cells

The effects of mango consumption on vascular health and immune function

Objectives

Heart disease, caused by atherosclerosis, is the leading cause of death. Maintaining vascular integrity is crucial to reducing atherosclerosis risk. Mangos are rich in fiber, vitamins, minerals, and phytochemicals that may offer cardioprotective and immune-boosting benefits. However, their effects on the vasculature and immune system in adults with overweight and obesity remain unclear. The objective of this study was to investigate the effects of mango consumption on vascular health and immune function in adults with overweight and obesity.

Methods

In a 12-week, crossover study, 27 overweight and obese participants consumed either 100 kcals of mangos daily or isocaloric low-fat cookies daily. Fasting blood samples were collected at baseline, week 4, and week 12 and analyzed for vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), P-selectin, E-selectin, sCD4, sCD8, sCD3E, and sCD45, tumor necrosis factor-alpha (TNF-α), catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD).

Results

Mango consumption significantly decreased VCAM-1 between baseline and week 4 (P = 0.046) and week 12 (P = 0.004). CAT increased between baseline and week 12 (P = 0.035) with mango consumption. GPx increased at week 12 compared to baseline and week 4 (P < 0.05). At week 12, SOD was higher after mango consumption compared to low-fat cookie consumption (P = 0.046). There were no significant differences in ICAM-1, P-selectin, E-selectin, sCD4, sCD8, sCD3E, sCD45 or TNF-α concentrations (P > 0.05 for all non-significant results).

Conclusions

This study suggests that 100 kcals of mangos may benefit the integrity of the vasculature by reducing VCAM-1 and increasing SOD, CAT, and GPx levels. Mangos can be an alternative snack for improving atherosclerosis and oxidative stress risk factors.

Integrated Cascade Nanozymes with Antisenescence Activities for Atherosclerosis Therapy

Senescent cells are the critical drivers of atherosclerosis formation and maturation. Mitigating senescent cells holds promise for the treatment of atherosclerosis. In an atherosclerotic plaque microenvironment, senescent cells interact with reactive oxygen species (ROS), promoting the disease development. Here, we hypothesize that a cascade nanozyme with antisenescence and antioxidant activities can serve as an effective therapeutic for atherosclerosis. An integrated cascade nanozyme with superoxide dismutase- and glutathione peroxidase-like activities, named MSe1 , is developed in this work. The obtained cascade nanozyme can attenuate human umbilical vein endothelial cell (HUVEC) senescence by protecting DNA from damage. It significantly weakens inflammation in macrophages and HUVECs by eliminating overproduced intracellular ROS. Additionally, the MSe1 nanozyme effectively inhibits foam cell formation in macrophages and HUVECs by decreasing the internalization of oxidized low-density lipoprotein. After intravenous administration, the MSe1 nanozyme significantly inhibits the formation of atherosclerosis in apolipoprotein E-deficient (ApoE-/- ) mice by reducing oxidative stress and inflammation and then decreases the infiltration of inflammatory cells and senescent cells in atherosclerotic plaques. This study not only provides a cascade nanozyme but also suggests that the combination of antisenescence and antioxidative stress holds considerable promise for treating atherosclerosis.

Impairment of endothelial glycocalyx in atherosclerosis and obesity

Endothelial glycocalyx is a negatively charged gel-like layer located on the apical surface of endothelial cells. It serves as a selective two-way physical barrier between the flowing blood and the endothelium, which regulates the access of macromolecules and of blood cells to the endothelial surface. In addition, endothelial glycocalyx plays a major role in sensing mechanical signals generated by the blood flow and transducing these signals to maintain endothelial functions; Thus, dysfunction or disruption of endothelial glycocalyx in pathological condition leads to endothelial dysfunction and contributes to the development of vascular diseases. In this review, we discuss the impact of atherosclerosis with the following viewpoints: (i) hypercholesterolemic effects on endothelial glycocalyx degradation in animal models and human patients, (ii) disruption of endothelial glycocalyx by atherogenic lipoproteins, (iii) proatherogenic disturbed flow effects on endothelial glycocalyx degradation, (iv) pathological consequences of the loss of glycocalyx integrity in atherogenesis, and (v) therapeutic effect of glycocalyx supplementation on atherosclerosis development. Additionally, we also discuss recent studies in pathological effects of obesity on the disruption of endothelial glycocalyx.

Examining the expression levels of ferroptosis-related genes in angiographically determined coronary artery disease patients

BACKGROUND

Cardiovascular diseases are the leading cause of death worldwide, with several conditions being affected by oxidative stress. Ferroptosis, recently identified programmed cell death mechanism, is relies on oxidative stress. This study aimed to determine the expressions of the genes involved in the molecular pathways of oxidative stress and ferroptosis and the association of these genes with CAD risk factors in CAD and non-CAD individuals.

METHODS AND RESULTS

The blood samples of individuals who underwent coronary angiography were collected and divided according to CAD status. Total RNA isolation was performed using the PAXgene RNA isolation kit from the whole blood samples. The mRNA expression levels of RTN3, GPX4, CAT, HMOX1, ELOVL5, SLC25A1, SLC7A11, and ACSL4 genes were determined using Real-Time PCR. Biochemical analyses were done before coronary angiography, and the results were evaluated statistically. The expression levels of the CAT gene are significantly lower in the CAD group when compared to non-CAD. HMOX1 expression levels are positively correlated with stenosis percentage, Gensini, and SYNTAX scores in the CAD group. RTN3, SLC25A1, and GPX4 mRNA expressions are correlated with HDL-C levels. Moreover, HbA1c levels and BMI, correlate negatively with ACSL4 expression in non-CAD controls. Also, ELOVL5 expression is negatively correlated with total bilirubin and direct bilirubin levels in the CAD group.

CONCLUSIONS

In this study, the genes related to oxidative stress and ferroptosis were found associated with biochemical parameters associated with CAD risk. These preliminary results may provide a new perspective to further studies investigating the reasons behind the identified associations.

Antioxidant properties of anthocyanins and their mechanism of action in atherosclerosis

Atherosclerosis develops due to lipid accumulation in the arterial wall and sclerosis as result of increased hyperlipidemia, oxidative stress, lipid oxidation, and protein oxidation. However, improving antioxidant status through diet may prevent the progression of atherosclerotic cardiovascular disease. It is believed that polyphenol-rich plants contribute to the inverse relationship between fruit and vegetable intake and chronic disease. Anthocyanins are flavonoid polyphenols with antioxidant properties that have been associated with reduced risk of cardiovascular disease. The consumption of anthocyanins increases total antioxidant capacity, antioxidant defense enzymes, and HDL antioxidant properties by several measures in preclinical and clinical populations. Anthocyanins appear to impart antioxidant actions via direct antioxidant properties, as well as indirectly via inducing intracellular Nrf2 activation and antioxidant gene expression. These actions counter oxidative stress and inflammatory signaling in cells present in atherosclerotic plaques, including macrophages and endothelial cells. Overall, anthocyanins may protect against atherosclerosis and cardiovascular disease through their effects on cellular antioxidant status, oxidative stress, and inflammation; however, their underlying mechanisms of action appear to be complex and require further elucidation.

MnSOD protects against vascular calcification independent of changes in vascular function in hypercholesterolemic mice

BACKGROUND AND AIMS

The overall goal of this study was to determine the effects of MnSOD-deficiency on vascular structure and function in hypercholesterolemic mice. Previous work suggested that increases in mitochondrial-derived reactive oxygen species (ROS) can exacerbate vascular dysfunction and atherosclerosis. It remains unknown, however, how MnSOD-deficiency and local compensatory mechanisms impact atherosclerotic plaque composition.

METHODS AND RESULTS

We used a hypercholesterolemic mouse model (ldlr^-/-/ApoB^100/100; LA), either wild-type for MnSOD (LA-MnSOD^+/+) or MnSOD-haploinsufficient (LA-MnSOD^+/-), that was fed a western diet for either 3 or 6 months. Consistent with previous reports, reductions of MnSOD did not significantly worsen hypercholesterolemia-induced endothelial dysfunction in the aorta. Critically, dramatic impairment of vascular function with Nox2 inhibition or catalase pretreatment suggested the presence of a significant NO-independent vasodilatory mechanism in LA-MnSOD^+/- mice (e.g. H₂O₂). Despite remarkably well-preserved overall vascular relaxation, loss of mitochondrial antioxidant capacity in LA-MnSOD^+/- mice significantly increased osteogenic signalling and vascular calcification compared to the LA-MnSOD^+/+ littermates.

CONCLUSIONS

Collectively, these data are the first to suggest that loss of mitochondrial antioxidant capacity in hypercholesterolemic mice results in dramatic upregulation of NADPH oxidase-derived H₂O₂. While this appears to be adaptive in the context of preserving overall endothelium-dependent relaxation and vascular function, these increases in ROS appear to be remarkably maladaptive and deleterious in the context of vascular calcification.

The homeostatic role of hydrogen peroxide, superoxide anion and nitric oxide in the vasculature

Reactive oxygen and nitrogen species are produced in a wide range of physiological reactions that, at low concentrations, play essential roles in living organisms. There is a delicate equilibrium between formation and degradation of these mediators in a healthy vascular system, which contributes to maintaining these species under non-pathological levels to preserve normal vascular functions. Antioxidants scavenge reactive oxygen and nitrogen species to prevent or reduce damage caused by excessive oxidation. However, an excessive reductive environment induced by exogenous antioxidants may disrupt redox balance and lead to vascular pathology. This review summarizes the main aspects of free radical biochemistry (formation, sources and elimination) and the crucial actions of some of the most biologically relevant and well-characterized reactive oxygen and nitrogen species (hydrogen peroxide, superoxide anion and nitric oxide) in the physiological regulation of vascular function, structure and angiogenesis. Furthermore, current preclinical and clinical evidence is discussed on how excessive removal of these crucial responses by exogenous antioxidants (vitamins and related compounds, polyphenols) may perturb vascular homeostasis. The aim of this review is to provide information of the crucial physiological roles of oxidation in the endothelium, vascular smooth muscle cells and perivascular adipose tissue for developing safer and more effective vascular interventions with antioxidants.

Simultaneous Cross-Linking and Cross-Polymerization of Enzyme Responsive Polyethylene Glycol Nanogels in Confined Aqueous Droplets for Reduction of Low-Density Lipoprotein Oxidation

A key initiating step in atherosclerosis is the accumulation and retention of apolipoprotein B complexing lipoproteins within the artery walls. In this work, we address this exact initiating mechanism of atherosclerosis, which results from the oxidation of low-density lipoproteins (oxLDL) using therapeutic nanogels. We present the development of biocompatible polyethylene glycol (PEG) cross-linked nanogels formed from a single simultaneous cross-linking and co-polymerization step in water without the requirement for an organic solvent, high temperature, or shear stress. The nanogel synthesis also incorporates in situ noncovalent electrostatically driven template polymerization around an innate anti-inflammatory and anti-oxidizing paraoxonase-1 (PON-1) enzyme payload-the release of which is triggered because of matrix metalloproteinase responsive elements instilled in the PEG cross-linker monomer. The results obtained demonstrate the potential of triggered release of the PON-1 enzyme and its efficacy against the production of ox-LDL, and therefore a reduction in macrophage foam cell and reactive oxygen species formation.

Paraoxonase-1 and other factors related to oxidative stress in psoriasis

Introduction

Psoriasis is considered as a risk factor for atherosclerosis and contributes to myocardial infarction, ischemic heart disease and brain stroke.

Aim

To estimate the atherogenic potential of psoriasis by analysing antioxidative and prooxidative factors (paraoxonase-1, α-tocopherol, uric acid, homocysteine), compare levels of these parameters between groups of psoriatic patients and healthy individuals as well as to analyse the impact of psoriasis severity and duration on the factors under the study and to define correlation between the marked factors and patients' lifestyles, body mass index (BMI) and abdominal circumference.

Material and methods

The investigated group consisted of 66 patients with psoriasis vulgaris, while the control group comprised 30 persons. Both groups were comparable as regards their age, sex and BMI as well as abdominal circumference.

Results

A significantly lower activity of paraoxonase-1 (p < 0.001), level of tocopherol (p < 0.05) and significantly higher concentration of homocysteine (p < 0.01), uric acid (p < 0.05) were found in patients with psoriasis as compared to the reference group. A higher homocysteine level occurs in patients with a negative family history of psoriasis (p < 0.05). In the group of patients with psoriasis and metabolic syndrome, the uric acid level was significantly higher (p < 0.05). Concentration of uric acid correlated negatively with the abdominal circumference value (p < 0.001).

Conclusions

Psoriasis promotes arteriosclerosis development by decreasing the levels of antiatherogenic and increasing the levels of proatherogenic agents. Adverse changes in psoriatic patients involve activity of paraoxonase-1, levels of α-tocopherol, uric acid, homocysteine as compared to healthy individuals selected by their age, BMI and abdominal circumference value.

Glutathione "Redox Homeostasis" and Its Relation to Cardiovascular Disease

More people die from cardiovascular diseases (CVD) than from any other cause. Cardiovascular complications are thought to arise from enhanced levels of free radicals causing impaired "redox homeostasis," which represents the interplay between oxidative stress (OS) and reductive stress (RS). In this review, we compile several experimental research findings that show sustained shifts towards OS will alter the homeostatic redox mechanism to cause cardiovascular complications, as well as findings that show a prolonged antioxidant state or RS can similarly lead to such cardiovascular complications. This experimental evidence is specifically focused on the role of glutathione, the most abundant antioxidant in the heart, in a redox homeostatic mechanism that has been shifted towards OS or RS. This may lead to impairment of cellular signaling mechanisms and elevated pools of proteotoxicity associated with cardiac dysfunction.

Oxidative Stress in Human Atherothrombosis: Sources, Markers and Therapeutic Targets

Atherothrombosis remains one of the main causes of morbidity and mortality worldwide. The underlying pathology is a chronic pathological vascular remodeling of the arterial wall involving several pathways, including oxidative stress. Cellular and animal studies have provided compelling evidence of the direct role of oxidative stress in atherothrombosis, but such a relationship is not clearly established in humans and, to date, clinical trials on the possible beneficial effects of antioxidant therapy have provided equivocal results. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase is one of the main sources of reactive oxygen species (ROS) in human atherothrombosis. Moreover, leukocyte-derived myeloperoxidase (MPO) and red blood cell-derived iron could be involved in the oxidative modification of lipids/lipoproteins (LDL/HDL) in the arterial wall. Interestingly, oxidized lipoproteins, and antioxidants, have been analyzed as potential markers of oxidative stress in the plasma of patients with atherothrombosis. In this review, we will revise sources of ROS, focusing on NADPH oxidase, but also on MPO and iron. We will also discuss the impact of these oxidative systems on LDL and HDL, as well as the value of these modified lipoproteins as circulating markers of oxidative stress in atherothrombosis. We will finish by reviewing some antioxidant systems and compounds as therapeutic strategies to prevent pathological vascular remodeling.

Glutathione peroxidase activity and expression levels are significantly increased in acute coronary syndromes

High levels of the antioxidant enzyme, glutathione peroxidase (GPx), have been associated with improved outcomes following acute coronary syndromes (ACS), suggesting a protective role. How GPx levels are altered with coronary disease is not clearly established. This study examined GPx activity, protein, and mRNA levels in healthy controls, patients with stable coronary artery disease (CAD), and patients with ACS. We studied 20 individuals from each of the healthy control, stable CAD, and ACS groups. GPx activity and protein levels, along with oxidized low-density lipoprotein (oxLDL) were assayed in plasma. GPx mRNA levels from whole blood were quantified using real-time PCR. Levels of GPx activity in the plasma were higher in ACS (109±7.7 U/mL) compared with patients with stable CAD (95.2±16.4 U/mL, p<0.01) and healthy controls (87.6±8.3 U/mL, p<0.001). Plasma GPx protein levels were also elevated in ACS (21.6±9.5 µg/mL) compared with patients with stable CAD (16.5±2.8 µg/mL, p<0.05) and healthy controls (16.3±5.3 µg/mL, p<0.05). Levels of GPX1, GPX3, and GPX4 mRNA were significantly higher in the patients with ACS. Levels of oxLDL were also significantly higher in patients with ACS (61.9±22.2 U/L) than in patients with stable CAD (47.8±10.4 U/L, p<0.05) and healthy controls (48.9±11.9 U/L, p<0.05). Levels of oxLDL, GPx activity, protein, and mRNA are all significantly higher in patients with ACS compared with patients with stable CAD and healthy controls. These findings suggest that GPx may be upregulated in response to a change in oxidative stress during an ACS.

Atheroprotective action of a modified organoselenium compound: in vitro evidence

ABSTRACT Oxidation of low-density lipoprotein (LDL) has been strongly suggested to play a significant role in the pathogenesis of atherosclerosis. Thus, reducing LDL oxidation is a potential approach to decrease the risk of the atherosclerosis. Organoselenium compounds have demonstrated promising atheroprotective properties in experimental models. Herein, we tested the in vitro atheroprotective capability of a modified organoselenium compound, Compound HBD, in protecting isolated LDL from oxidation as well as foam cells formation. Moreover, the glutathione peroxidase (GPx)-like activity of Compound HBD was analyzed in order to explore the mechanisms related to the above-mentioned protective effects. The Compound HBD in a concentration-dependent manner reduced the Cu2+-induced formation of conjugated dienes. The protein portion from LDL were also protected from Cu2+-induced oxidation. Furthermore, the Compound HBD efficiently decreased the foam cell formation in J774 macrophage cells exposed to oxidized LDL. We found that the atheroprotective effects of this compound can be, at least in part, related to its GPx-like activity. Our findings demonstrated an impressive effect of Compound HBD against LDL-induced toxicity, a further in vivo study to investigate in more detail the antioxidant and antiatherogenic effects of this compound could be considered.

Overexpression of Catalase Enhances Benzo(a)pyrene Detoxification in Endothelial Microsomes

We previously reported that overexpression of catalase upregulated xenobiotic- metabolizing enzyme (XME) expression and diminished benzo(a)pyrene (BaP) intermediate accumulation in mouse aortic endothelial cells (MAECs). Endoplasmic reticulum (ER) is the most active organelle involved in BaP metabolism. To examine the involvement of ER in catalase-induced BaP detoxification, we compared the level and distribution of XMEs, and the profile of BaP intermediates in the microsomes of wild-type and catalase transgenic endothelial cells. Our data showed that endothelial microsomes were enriched in cytochrome P450 (CYP) 1A1, CYP1B1 and epoxide hydrolase 1 (EH1), and contained considerable levels of NAD(P)H: quinone oxidoreductase-1 (NQO1) and glutathione S-transferase-pi (GSTP). Treatment of wild-type MAECs with 1μM BaP for 2 h increased the expression of microsomal CYP1A1, 1B1 and NQO1 by ~300, 64 and 116%, respectively. However, the same treatment did not significantly alter the expression of EH1 and GSTP. Overexpression of catalase did not significantly increase EH1, but upregulated BaP-induced expression of microsomal CYP1A1, 1B1, NQO1 and GSTP in the following order: 1A1>NQO1>GSTP>1B1. Overexpression of catalase did not alter the distribution of each of these enzymes in the microsomes. In contrast to our previous report showing lower level of BaP phenols versus BaP diols/diones in the whole-cell, this report demonstrated that the sum of microsomal BaP phenolic metabolites were ~60% greater than that of the BaP diols/diones after exposure of microsomes to BaP. Overexpression of catalase reduced the concentrations of microsomal BaP phenols and diols/diones by ~45 and 95%, respectively. This process enhanced the ratio of BaP phenol versus diol/dione metabolites in a potent manner. Taken together, upregulation of phase II XMEs and CYP1 proteins, but not EH1 in the ER might be the mechanism by which overexpression of catalase reduces the levels of all the BaP metabolites, and enhances the ratio of BaP phenolic metabolites versus diol/diones in endothelial microsomes.

Different Anti-Contractile Function and Nitric Oxide Production of Thoracic and Abdominal Perivascular Adipose Tissues

Divergent phenotypes between the perivascular adipose tissue (PVAT) surrounding the abdominal and the thoracic aorta might be implicated in regional aortic differences, such as susceptibility to atherosclerosis. Although PVAT of the thoracic aorta exhibits anti-contractile function, the role of PVAT in the regulation of the vascular tone of the abdominal aorta is not well defined. In the present study, we compared the anti-contractile function, nitric oxide (NO) availability, and reactive oxygen species (ROS) formation in PVAT and vessel walls of abdominal and thoracic aorta. Abdominal and thoracic aortic tissue from male Wistar rats were used to perform functional and molecular experiments. PVAT reduced the contraction evoked by phenylephrine in the absence and presence of endothelium in the thoracic aorta, whereas this anti-contractile effect was not observed in the abdominal aorta. Abdominal PVAT exhibited a reduction in endothelial NO synthase (eNOS) expression compared with thoracic PVAT, without differences in eNOS expression in the vessel walls. In agreement with this result, NO production evaluated in situ using 4,5-diaminofluorescein was less pronounced in abdominal compared with thoracic aortic PVAT, whereas no significant difference was observed for endothelial NO production. Moreover, NOS inhibition with L-NAME enhanced the phenylephrine-induced contraction in endothelial-denuded rings with PVAT from thoracic but not abdominal aorta. ROS formation and lipid peroxidation products evaluated through the quantification of hydroethidine fluorescence and 4-hydroxynonenal adducts, respectively, were similar between PVAT and vessel walls from the abdominal and thoracic aorta. Extracellular superoxide dismutase (SOD) expression was similar between the vessel walls and PVAT of the abdominal and thoracic aorta. However, Mn-SOD levels were reduced, while CuZn-SOD levels were increased in abdominal PVAT compared with thoracic aortic PVAT. In conclusion, our results demonstrate that the anti-contractile function of PVAT is lost in the abdominal portion of the aorta through a reduction in eNOS-derived NO production compared with the thoracic aorta. Although relative SOD isoforms are different along the aorta, ROS formation, and lipid peroxidation seem to be similar. These findings highlight the specific regional roles of PVAT depots in the control of vascular function that can drive differences in susceptibility to vascular injury.

High-selenium lentil diet protects against arsenic-induced atherosclerosis in a mouse model

BACKGROUND

Cardiovascular disease (CVD) is a major cause of death worldwide, and arsenic (As) intake, mainly through drinking water, is a well-known risk factor for CVD as well as other health problems. Selenium (Se) is a known antagonist to As toxicity.

OBJECTIVE

We tested the potential of high-Se lentils from the Canadian prairies as a therapeutic food to alter the outcome of As-enhanced atherosclerosis.

MATERIALS AND METHODS

Male ApoE(-/-) mice exposed to a moderate level of As (200ppb) in their drinking water, and control mice on tap water received one of three lentil diets: Se-deficient (0.009mg/kg), Se-adequate (0.16mg/kg) or Se-high (0.3mg/kg). After 13weeks, lesion formation in the aortic arch and sinus were assessed. Intralesional cellular composition, serum lipid levels and hepatic oxidative stress were assessed as well.

RESULTS

Arsenic-exacerbated plaque formation was reduced in the sinus and completely abolished in the aortic arch of mice on the Se-fortified lentil diet, whereas lesions were increased in As-exposed mice on both the Se-deficient and Se-adequate diets. Notably, Se deficiency contributed to proatherogenic composition of serum lipids in As-exposed mice as indicated by high-density lipoprotein:low-density lipoprotein. At least adequate Se status was crucial for counteracting As-induced oxidative stress.

CONCLUSION

This study is the first to show the potential of high-Se lentils to protect against As-triggered atherosclerosis, and this invites further investigations in human populations at risk from As contamination of their drinking water.

Impact of glutathione peroxidase-1 deficiency on macrophage foam cell formation and proliferation: implications for atherogenesis

Clinical and experimental evidence suggests a protective role for the antioxidant enzyme glutathione peroxidase-1 (GPx-1) in the atherogenic process. GPx-1 deficiency accelerates atherosclerosis and increases lesion cellularity in ApoE^−/− mice. However, the distribution of GPx-1 within the atherosclerotic lesion as well as the mechanisms leading to increased macrophage numbers in lesions is still unknown. Accordingly, the aims of the present study were (1) to analyze which cells express GPx-1 within atherosclerotic lesions and (2) to determine whether a lack of GPx-1 affects macrophage foam cell formation and cellular proliferation. Both in situ-hybridization and immunohistochemistry of lesions of the aortic sinus of ApoE^−/− mice after 12 weeks on a Western type diet revealed that both macrophages and – even though to a less extent – smooth muscle cells contribute to GPx-1 expression within atherosclerotic lesions. In isolated mouse peritoneal macrophages differentiated for 3 days with macrophage-colony-stimulating factor (MCSF), GPx-1 deficiency increased oxidized low density-lipoprotein (oxLDL) induced foam cell formation and led to increased proliferative activity of peritoneal macrophages. The MCSF- and oxLDL-induced proliferation of peritoneal macrophages from GPx-1^−/−ApoE^−/− mice was mediated by the p44/42 MAPK (p44/42 mitogen-activated protein kinase), namely ERK1/2 (extracellular-signal regulated kinase 1/2), signaling pathway as demonstrated by ERK1/2 signaling pathways inhibitors, Western blots on cell lysates with primary antibodies against total and phosphorylated ERK1/2, MEK1/2 (mitogen-activated protein kinase kinase 1/2), p90RSK (p90 ribosomal s6 kinase), p38 MAPK and SAPK/JNK (stress-activated protein kinase/c-Jun N-terminal kinase), and immunohistochemistry of mice atherosclerotic lesions with antibodies against phosphorylated ERK1/2, MEK1/2 and p90RSK. Representative effects of GPx-1 deficiency on both macrophage proliferation and MAPK phosphorylation could be abolished by the GPx mimic ebselen. The present study demonstrates that GPx-1 deficiency has a significant impact on macrophage foam cell formation and proliferation via the p44/42 MAPK (ERK1/2) pathway encouraging further studies on new therapeutic strategies against atherosclerosis.

Mulberry leaf reduces oxidation and C-reactive protein level in patients with mild dyslipidemia

C-reactive protein (CRP) is the inflammatory marker that could represent the inflammation in blood vessels resulted from dyslipidemia. The objective of this study was to evaluate the antioxidative activity of mulberry leaf powder using DPPH assay and the effect of mulberry leaf powder on lipid profile, CRP level, and antioxidative parameters in mild dyslipidemia patients. A within-subjects design was conducted and patients received three tablets of 280 mg mulberry leaf powder three times a day before meals for 12 weeks. Total of 25 patients were enrolled but one subject was excluded. After three months of mulberry leaf consumption, serum triglyceride and low-density lipoprotein (LDL) level were significantly reduced and more than half of all patients' CRP levels decreased every month as well as the mean CRP level but no statistically significant difference was found. The average erythrocyte glutathione peroxidase activity of patients was increased but not at significant level; however, the mean serum 8-isoprostane level was significantly lower after mulberry treatment for 12 weeks. It can be concluded that mulberry leaf powder exhibited antioxidant activity and mulberry leaf powder has potential to decrease serum triglyceride, LDL, and CRP levels in mild dyslipidemia patients without causing severe adverse reactions.

Human atherosclerotic plaque lipid extract impairs the antioxidant defense capacity of monocytes

Oxidative stress, induced by reactive oxygen species (ROS), is implicated in the pathogenesis of plaque formation and instability. During this ongoing oxidative process, cells in the vasculature are exposed to the atherogenicity of the plaque; previous studies have suggested that the arterial plaque, apart from being a consequence of the development of atherosclerosis, is also a cause of its progression.

OBJECTIVE

In this study, we challenged this idea by investigating the effect of carotid plaque lipid extract on the human monocyte antioxidant system.

METHODS AND RESULTS

Exposure of monocytes to carotid plaque lipid extract (LE) for up to 72 h resulted in a significant increase in the ROS level (170%), with a simultaneous rise of 177% in glutathione oxidation. Experiments revealed a significant decrease, in the intracellular antioxidant enzyme activity of CAT, GPx and TRxR, (by 17, 33 and 43%, respectively). Although the activity of these enzymes subsequently returned to those of the controls, the levels of ROS did not decrease but rather continued increasing with extended LE exposure. Intriguingly, intracellular SOD activity rose significantly and remained high (176%), implying that endogenously produced H(2)O(2), and not O(2)·¯ < is the factor that promotes the oxidative stress resulting from the presence of LE.

CONCLUSION

Lipids from the atherosclerotic plaque may contribute to the progression of atherogenic conditions in adjacent regions by weakening the cellular antioxidant system and promoting oxidative stress, mainly through H(2)O(2) production.

Association between the rs1050450 glutathione peroxidase-1 (C > T) gene variant and peripheral neuropathy in two independent samples of subjects with diabetes mellitus

Glutathione peroxidase-1 (GPx-1) is an endogenous anti-oxidant enzyme. The T allele of the GPx-1 rs1050450 (C > T) gene variant is associated with reduced enzyme activity. Our aim was to examine the association between this gene variant and peripheral neuropathy in two cross-sectional samples of subjects with diabetes: (i) 773 Caucasian subjects were genotyped from the UCL Diabetes and Cardiovascular disease Study (UDACS) and (ii) 382 Caucasian subjects from the Ealing Diabetes Study (EDS). Peripheral neuropathy status (and oxidised-LDL [Ox-LDL:LDL] and plasma Total Ant-ioxidant Status [TAOS] in UDACS), were analysed in relation to genotype. We observed that: (i) In UDACS, the odds ratio (OR) for peripheral neuropathy in the T allele carriers compared to the CC genotype was 1.61 [1.10-2.28], p = 0.01. This remained significant after adjustment for other risk factors. Ox-LDL:LDL ratio was significantly elevated in T allele carriers (CC vs. CT/TT: 16.3 ± 2.4 v 18.0 ± 2.9 U/mmol LDL, p = 0.02). (ii) In EDS, the OR for peripheral neuropathy in the T allele carriers compared to the CC genotype was 1.95 [1.11-3.42], p = 0.02. This remained significant after adjustment for other risk factors. In conclusion, we observed a significant association between the T allele and peripheral neuropathy and LDL oxidation. This is the first paper to examine the rs1050450 variant in two samples of Caucasian subjects with diabetes. Prospective analysis of the gene variant is required in diabetic and healthy cohorts with measured plasma markers of oxidative stress to investigate the described association further.

Gain and loss of function for glutathione synthesis: impact on advanced atherosclerosis in apolipoprotein E-deficient mice

OBJECTIVE

Glutamate-cysteine ligase (GCL) is the rate-limiting step in glutathione synthesis. The enzyme is a heterodimer composed of a catalytic subunit, GCLC, and a modifier subunit, GCLM. We generated apolipoprotein E (apoE)-/- mice deficient in GCLM (apoE-/-/Gclm-/-) and transgenic mice that overexpress GCLC specifically in macrophages (apoE-/-/Gclc-Tg) to test the hypothesis that significantly altering the availability of glutathione has a measurable impact on both the initiation and progression of atherosclerosis.

METHODS AND RESULTS

Atherosclerotic plaque size and composition were measured in the innominate artery in chow-fed male and female mice at 20, 30, 40, and 50 weeks of age and in the aortic sinus at 40 and 50 weeks of age. The apoE-/-/Gclm-/- mice more rapidly developed complex lesions, whereas the apoE-/-/Gclc-Tg mice had reduced lesion development compared with the littermate apoE-/- control mice. Transplantation of bone marrow from the apoE-/-/Gclm-/- and apoE-/-/Gclc-Tg mice into apoE-/- mice with established lesions also stimulated or inhibited further lesion development at 30 weeks posttransplant.

CONCLUSION

Gain and loss of function in the capacity to synthesize glutathione especially in macrophages has reciprocal effects on the initiation and progression of atherosclerosis at multiple sites in apoE-/- mice.

Glutathione peroxidase-1 in health and disease: from molecular mechanisms to therapeutic opportunities

Reactive oxygen species, such as superoxide and hydrogen peroxide, are generated in all cells by mitochondrial and enzymatic sources. Left unchecked, these reactive species can cause oxidative damage to DNA, proteins, and membrane lipids. Glutathione peroxidase-1 (GPx-1) is an intracellular antioxidant enzyme that enzymatically reduces hydrogen peroxide to water to limit its harmful effects. Certain reactive oxygen species, such as hydrogen peroxide, are also essential for growth factor-mediated signal transduction, mitochondrial function, and maintenance of normal thiol redox-balance. Thus, by limiting hydrogen peroxide accumulation, GPx-1 also modulates these processes. This review explores the molecular mechanisms involved in regulating the expression and function of GPx-1, with an emphasis on the role of GPx-1 in modulating cellular oxidant stress and redox-mediated responses. As a selenocysteine-containing enzyme, GPx-1 expression is subject to unique forms of regulation involving the trace mineral selenium and selenocysteine incorporation during translation. In addition, GPx-1 has been implicated in the development and prevention of many common and complex diseases, including cancer and cardiovascular disease. This review discusses the role of GPx-1 in these diseases and speculates on potential future therapies to harness the beneficial effects of this ubiquitous antioxidant enzyme.

Nrf2-dependent induction of NQO1 in mouse aortic endothelial cells overexpressing catalase

Overexpression of catalase has been shown to accelerate benzo(a)pyrene (BaP) detoxification in mouse aortic endothelial cells (MAECs). NAD(P)H:quinone oxidoreductase-1 (NQO1) is an enzyme that catalyzes BaP-quinone detoxification. Aryl hydrocarbon receptor (AhR) and nuclear factor erythroid 2-related factor-2 (Nrf2) are transcription factors that control NQO1 expression. Here, we investigated the effects of catalase overexpression on NQO1, Nrf2, and AhR expression. The levels of NQO1 mRNA and protein were comparable in MAECs isolated from wild-type and transgenic mice that overexpress human catalase (hCatTg). BaP treatment increased NQO1 mRNA and protein levels in both groups, with a significantly greater induction in hCatTg MAECs than in wild-type cells. BaP-induced NQO1 promoter activity was dramatically higher in hCatTg MAECs than in wild-type cells. Our data also showed that the basal level of AhR and the BaP-induced level of Nrf2 were significantly higher in hCatTg MAECs than in wild-type cells. Inhibition of specificity protein-1 (Sp1) binding to the AhR promoter region by mithramycin A reversed the enhancing effect of catalase overexpression on AhR expression. Knockdown of AhR by RNA interference diminished BaP-induced expression of Nrf2 and NQO1. Knockdown of Nrf2 significantly decreased NQO1 mRNA and protein levels in cells with or without BaP treatment. NQO1 promoter activity was abrogated by mutation of the Nrf2-binding site in this promoter. In contrast, mutation of the AhR-binding site in the NQO1 promoter did not affect the promoter activity. These results suggest that catalase overexpression upregulates BaP-induced NQO1 expression by enhancing the Sp1-AhR-Nrf2 signaling cascade.

Enhanced pressor response to acute Ang II infusion in mice lacking membrane-associated prostaglandin E2 synthase-1

AIM

To examine the contribution of vascular membrane-associated prostaglandin E2 synthase-1 (mPGES-1) to acute blood pressure homeostasis.

METHODS

Angiotensin II (AngII, 75 pmol·kg⁻¹·min⁻¹) was continuously infused via the jugular vein into wild-type and mPGES-1(-/-) mice for 30 min, and blood pressure was measured by carotid arterial catheterization. RT-PCR and immunohistochemistry were performed to detect the expression and localization of mPGES-1 in the mouse arterial vessels. Mesenteric arteries were dissected from mice of both genotypes to study vessel tension and measure vascular PGE2 levels.

RESULTS

Wild-type and mPGES-1(-/-) mice showed similar blood pressure levels at baseline, and the acute intravenous infusion of AngII caused a greater increase in mean arterial pressure in the mPGES-1(-/-) group, with a similar diuretic and natriuretic response in both groups. mPGES-1 was constitutively expressed in the aortic and mesenteric arteries and vascular smooth muscle cells of wild-type mice. Strong staining was detected in the smooth muscle layer of arterial vessels. Ex vivo treatment of mesenteric arteries with AngII produced more vasodilatory PGE2 in wild-type than in mPGES-1(-/-) mice. In vitro tension assays further revealed that the mesenteric arteries of mPGES-1(-/-) mice exhibited a greater vasopressor response to AngII than those arteries of wild-type mice.

CONCLUSION

Vascular mPGES-1 acts as an important tonic vasodilator, contributing to acute blood pressure regulation.

Overexpression of antioxidant enzymes upregulates aryl hydrocarbon receptor expression via increased Sp1 DNA-binding activity

We previously reported upregulation of aryl hydrocarbon receptor (AhR) expression as a mechanism by which overexpression of Cu/Zn-superoxide dismutase (SOD) and/or catalase accelerates benzo(a)pyrene (BaP) detoxification in mouse aorta endothelial cells (MAECs). The objective of this study was to investigate the regulatory role of specificity protein-1 (Sp1) in AhR expression in MAECs that overexpress Cu/Zn-SOD and/or catalase. Our data demonstrated comparable levels of nuclear Sp1 protein in the transgenic and wild-type MAECs; however, binding of Sp1 protein to the AhR promoter region was more than 2-fold higher in MAECs overexpressing Cu/Zn-SOD and/or catalase than in wild-type cells. Inhibition of Sp1 binding to the AhR promoter by mithramycin A reduced AhR expression and eliminated the differences between wild-type MAECs and three lines of transgenic cells. Functional promoter analysis indicated that AhR promoter activity was significantly higher in MAECs overexpressing catalase than in wild-type cells. Mutation of an AhR promoter Sp1-binding site or addition of hydrogen peroxide to the culture medium reduced AhR promoter activity, and decreased the differences between wild-type MAECs and transgenic cells overexpressing catalase. These results suggest that increased Sp1 binding to the AhR promoter region is an underlying mechanism for upregulation of AhR expression in MAECs that overexpress Cu/Zn-SOD and/or catalase.

MnSOD protects against COX1-mediated endothelial dysfunction in chronic heart failure

Endothelial function is impaired by oxidative stress in chronic heart failure (HF). Mechanisms that protect against increases in oxidative stress in HF are not clear. The goal of this study was to determine whether manganese superoxide dismutase (MnSOD) plays a key role in protecting against endothelial dysfunction in HF. Endothelial function and gene expression were examined in aorta from wild-type mice (MnSOD(+/+)) and mice deficient in MnSOD (MnSOD(+/-)) 12 wk after ligation of the left coronary artery (LCA). LCA ligation produced similar size myocardial infarctions in MnSOD(+/+) and MnSOD(+/-) mice and reduced ejection fraction to approximately 20% in both groups. Maximal relaxation in response to acetylcholine was 78 +/- 3% (mean +/- SE) and 66 +/- 8% in sham-operated MnSOD(+/+) and MnSOD(+/-) mice, respectively. Expression of antioxidant enzymes increased in MnSOD(+/+) mice with HF, and maximal relaxation to acetylcholine was slightly impaired (68 +/- 4%). Greater endothelial dysfunction was observed in MnSOD(+/-) mice with HF (46 +/- 5%, P < 0.05), which was significantly improved by polyethylene glycol-catalase but not Tempol. Incubation with the nonspecific cyclooxygenase (COX) inhibitor indomethacin or the COX1 inhibitor valeryl salicylate, but not the COX-2 inhibitor NS-398, significantly improved relaxation to acetylcholine in HF mice (maximum relaxation = 74 +/- 5, 91 +/- 1, and 58 +/- 5%). These data suggest that MnSOD plays a key role in protecting against endothelial dysfunction in HF. A novel mechanism was identified whereby chronic increases in oxidative stress, produced by mitochondrial SOD deficiency, impair vascular function via a hydrogen peroxide-dependent, COX1-dependent, endothelium-derived contracting factor.

Update on the oxidative stress theory of aging: does oxidative stress play a role in aging or healthy aging?

The oxidative stress theory of aging predicts that manipulations that alter oxidative stress/damage will alter aging. The gold standard for determining whether aging is altered is life span, i.e., does altering oxidative stress/damage change life span? Mice with genetic manipulations in their antioxidant defense system designed to directly address this prediction have, with few exceptions, shown no change in life span. However, when these transgenic/knockout mice are tested using models that develop various types of age-related pathology, they show alterations in progression and/or severity of pathology as predicted by the oxidative stress theory: increased oxidative stress accelerates pathology and reduced oxidative stress retards pathology. These contradictory observations might mean that (a) oxidative stress plays a very limited, if any, role in aging but a major role in health span and/or (b) the role that oxidative stress plays in aging depends on environment. In environments with minimal stress, as expected under optimal husbandry, oxidative damage plays little role in aging. However, under chronic stress, including pathological phenotypes that diminish optimal health, oxidative stress/damage plays a major role in aging. Under these conditions, enhanced antioxidant defenses exert an "antiaging" action, leading to changes in life span, age-related pathology, and physiological function as predicted by the oxidative stress theory of aging.

Overexpression of Cu/Zn-superoxide dismutase and/or catalase accelerates benzo(a)pyrene detoxification by upregulation of the aryl hydrocarbon receptor in mouse endothelial cells

A reduction in endogenously generated reactive oxygen species in vivo delays benzo(a)pyrene (BaP)-accelerated atherosclerosis, as revealed in hypercholesterolemic mice overexpressing Cu/Zn-superoxide dismutase (SOD) and/or catalase. To understand the molecular events involved in this protective action, we studied the effects of Cu/Zn-SOD and/or catalase overexpression on BaP detoxification and on aryl hydrocarbon receptor (AhR) expression and its target gene expression in mouse aortic endothelial cells (MAECs). Our data demonstrate that overexpression of Cu/Zn-SOD and/or catalase leads to an 18- to 20-fold increase in the expression of AhR protein in MAECs. After BaP exposure, the amount of AhR binding to the cytochrome P450 (CYP) 1A1 promoter was significantly greater, and the concentrations of BaP reactive intermediates were significantly less in MAECs overexpressing Cu/Zn-SOD and/or catalase than in wild-type cells. In addition, the BaP-induced CYP1A1 and 1B1 protein levels and BaP-elevated glutathione S-transferase (GST) activity were significantly higher in these transgenic cells, in parallel with elevated GSTp1, CYP1A1, and CYP1B1 mRNA levels, compared to wild-type MAECs. Moreover, knockdown of AhR with RNA interference diminished the Cu/Zn-SOD and catalase enhancement of CYP1A1 expression, GST activity, and BaP detoxification. These data demonstrate that overexpression of Cu/Zn-SOD and/or catalase is associated with upregulation of AhR and its target genes, such as xenobiotic-metabolizing enzymes.

Telmisartan-induced inhibition of vascular cell proliferation beyond angiotensin receptor blockade and peroxisome proliferator-activated receptor-gamma activation

We investigated the ability of angiotensin II type 1 (AT1) receptor blockers with peroxisome proliferator-activated receptor (PPAR)-gamma agonist activity (telmisartan and irbesartan) and AT1 receptor blockers devoid of PPARgamma agonist activity (eprosartan and valsartan) to inhibit vascular cell proliferation studied in the absence of angiotensin II stimulation. Telmisartan and, to a lesser extent, irbesartan inhibited proliferation of human aortic vascular smooth muscle cells in a dose-dependent fashion, whereas eprosartan and valsartan did not. To investigate the role of PPARgamma in the antiproliferative effects of telmisartan, we studied genetically engineered NIH3T3 cells that express PPARgamma. Pioglitazone inhibited proliferation of NIH3T3 cells expressing PPARgamma but had little effect on control NIH3T3 cells that lack PPARgamma. In contrast, telmisartan inhibited proliferation equally in NIH3T3 with and without PPARgamma. Valsartan failed to inhibit proliferation of either cell line. In addition, telmisartan inhibited proliferation equally in aortic smooth muscle cells derived from mice with targeted knockout of PPARgamma in the smooth muscle and from control mice, whereas valsartan had no effect on cell proliferation. Telmisartan, but not valsartan, reduced phosphorylation of AKT but not extracellular signal-regulated kinase otherwise induced by exposure to serum of quiescent human smooth muscle cells, quiescent mice smooth muscle cells lacking PPARgamma, or quiescent Chinese hamster ovary-K1 cells lacking the AT1 receptor. In summary, the antiproliferative effects of telmisartan in the absence of exogenously supplemented angiotensin II involve more than just AT1 receptor blockade and do not require activation of PPARgamma. It might be postulated that inhibition of AKT activation is a mechanism mediating the antiproliferative effects of telmisartan, including in cells lacking AT1 receptors or PPARgamma.

Elevated levels of oxidized low-density lipoprotein and of catalase activity in follicular fluid of obese women

The intrafollicular levels of oxidized low-density lipoprotein (oxLDL) and of enzyme antioxidants might contribute to reproductive disorders in obese and infertile women. Relevant data are missing. Eighty-four patients were grouped according to obese versus non-obese status and whether they had polycystic ovary syndrome (PCOS). The concentrations of oxLDL and the activities of superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx) and glutathione reductase (GR) in the serum and follicular fluid were measured. Obese women with and without PCOS had significantly greater amounts of oxLDL in the follicular fluid as compared with non-obese women. The level of oxLDL in the follicular fluid was 1000 times lower than in serum. Obese women with and without PCOS had significantly higher catalase activity in the follicular fluid as compared with non-obese women. No differences were found for the SOD activity in the follicular fluid. The GPx and GR activities were up-regulated in obese patients without and with PCOS, yet not in respect to each serum and follicular fluid sample. We conclude that elevated levels of oxLDL in the follicular fluid of obese women are associated with higher catalase activity; both parameters are independent of PCOS. The levels of oxLDL and catalase activity appear to indicate different degrees of oxidative stress.

Regulation and function of selenoproteins in human disease

Selenoproteins are proteins containing selenium in the form of the 21st amino acid, selenocysteine. Members of this protein family have many diverse functions, but their synthesis is dependent on a common set of cofactors and on dietary selenium. Although the functions of many selenoproteins are unknown, several disorders involving changes in selenoprotein structure, activity or expression have been reported. Selenium deficiency and mutations or polymorphisms in selenoprotein genes and synthesis cofactors are implicated in a variety of diseases, including muscle and cardiovascular disorders, immune dysfunction, cancer, neurological disorders and endocrine function. Members of this unusual family of proteins have roles in a variety of cell processes and diseases.

Overexpression of catalase delays G0/G1- to S-phase transition during cell cycle progression in mouse aortic endothelial cells

Although it is understood that hydrogen peroxide (H(2)O(2)) promotes cellular proliferation, little is known about its role in endothelial cell cycle progression. To assess the regulatory role of endogenously produced H(2)O(2) in cell cycle progression, we studied the cell cycle progression in mouse aortic endothelial cells (MAECs) obtained from mice overexpressing a human catalase transgene (hCatTg), which destroys H(2)O(2). The hCatTg MAECs displayed a prolonged doubling time compared to wild-type controls (44.0 +/- 4.7 h versus 28.6 +/- 0.8 h, p<0.05), consistent with a diminished growth rate and H(2)O(2) release. Incubation with aminotriazole, a catalase inhibitor, prevented the observed diminished growth rate in hCatTg MAECs. Inhibition of catalase activity with aminotriazole abrogated catalase overexpression-induced antiproliferative action. Flow cytometry analysis indicated that the prolonged doubling time was principally due to an extended G(0)/G(1) phase in hCatTg MAECs compared to the wild-type cells (25.0 +/- 0.9 h versus 15.9 +/- 1.4 h, p< 0.05). The hCatTg MAECs also exhibited decreased activities of the cyclin-dependent kinase (Cdk) complexes responsible for G(0)/G(1)- to S-phase transition in the cell cycle, including the cyclin D-Cdk4 and cyclin E-Cdk2 complexes. Moreover, the reduction in cyclin-Cdk activities in hCatTg MAECs was accompanied by increased protein levels of two Cdk inhibitors, p21 and p27, which inhibit the Cdk activity required for the G(0)/G(1)- to S-phase transition. Knockdown of p21 and/or p27 attenuated the antiproliferative effect of catalase overexpression in MAECs. These results, together with the fact that catalase is an H(2)O(2) scavenger, suggest that endogenously produced H(2)O(2) mediates MAEC proliferation by fostering the transition from G(0)/G(1) to S phase.

Overexpression of antioxidant enzymes in ApoE-deficient mice suppresses benzo(a)pyrene-accelerated atherosclerosis

The carcinogenic polycylic aromatic hydrocarbon, benzo(a)pyrene (BaP), has been shown to generate reactive oxygen species (ROS) and accelerate the development of atherosclerosis. To assess the causal role of BaP-generated ROS in this process, we evaluated atherosclerotic metrics in apolipoprotein E-deficient (ApoE(-/-)) mice with or without overexpression of Cu/Zn-superoxide dismutase (Cu/Zn-SOD) and/or catalase. Without BaP, aortic atherosclerotic lesions were smaller in ApoE(-/-) mice overexpressing catalase or both Cu/Zn-SOD and catalase than in those overexpressing neither or Cu/Zn-SOD only. After treating with BaP or vehicle for 24 weeks, mean lesion sizes in the aortic tree and aortic root of ApoE(-/-) mice were increased by approximately 60% and 40%, respectively. BaP also increased the levels of oxidized lipids in the aortic tree of ApoE(-/-) mice and increased the frequency of advanced lesions. In contrast, BaP did not significantly alter lipid peroxidation levels or atherosclerotic lesions in the aortas of ApoE(-/-) mice overexpressing Cu/Zn-SOD and/or catalase. Overexpression of Cu/Zn-SOD and/or catalase also inhibited BaP-induced expression of cell adhesion molecules in aortas and endothelial cells, and reduced BaP-induced monocyte adhesion to endothelial cells. These observations, together with the functions of catalase and Cu/Zn-SOD to scavenge hydrogen peroxide and superoxide anions, implicate a causal role of ROS in the pathogenesis of BaP-induced atherosclerosis.

Escherichia coli lipopolysaccharide administration alters antioxidant profile during hypercholesterolemia

Pathogens, especially Gram-negative bacteria or bacterial endotoxin, along with other classical factors, may be involved in inflammatory response within the aortic endothelium during the progression of cardiovascular disease. Studies have shown that bacterial endotoxin activates various inflammatory processes in the body. Our study aims to establish a correlation between endotoxemia and vascular expression of antioxidant enzymes. Swiss albino mice (4 weeks old) were fed a high fat diet for 24 weeks and then were administered Escherichia coli endotoxin intraperitonealy, for 4 weeks. Tissue antioxidant enzymes, serum levels of IL-6 and TNF alpha were measured from the mice. We report that i.p. administration of endotoxin to hyperlipidemic mice resulted in elevation of superoxide dismutase and catalase enzymes, which was paralleled by a systemic reduction of serum cholesterol and LDL expression. Myeloperoxidase levels were also found to be elevated in aortic tissue, while an increase was also observed in the serum cytokine levels.

Effect of acute myocardial infarction on erythrocytic glutathione peroxidase 1 activity and plasma vitamin e levels

Glutathione peroxidase 1 (GPX-1) has an important role in antioxidant defense and has been suggested to have a protective role against the pathogenesis of atherosclerosis. In the present study, erythrocytic GPX-1 activity from 42 patients with acute myocardial infarction and 285 healthy control subjects of Taiwanese origin were determined. Our data showed that mean GPX-1 activity decreased in patients with acute myocardial infarction (40.7 +/- 9.2 vs 47.3 +/- 16.6 U/g hemoglobin; p <0.001). There was a significant inverse correlation between GPX-1 activity and acute myocardial infarction incidence (p = 0.032). In addition, plasma vitamin E inversely correlated with acute myocardial infarction incidence (p = 0.017). The incidence of acute myocardial infarction increased only in patients with low plasma vitamin E and low erythrocytic GPX-1 activity, but not in those with high vitamin E and low GPX-1 activity, low vitamin E and high GPX-1 activity, or high vitamin E and high GPX-1 activity. In conclusion, acute myocardial infarction incidence significantly increased in patients with a concomitant decrease in plasma vitamin E and erythrocytic GPX-1 activity, suggesting that both GPX-1 and vitamin E may be valuable markers for monitoring cardiovascular events, particularly when used in combination.

Frequent inadequate supply of micronutrients in fast food induces oxidative stress and inflammation in testicular tissues of weanling rats

Fast food is high in energy density and low in essential micronutrient density, especially zinc (Zn), of which antioxidant processes are dependent. We have tested the hypothesis that frequent fast food consumption could induce oxidative damage associated with inflammation in weanling male rats in relevance to Zn deprivation, which could adversely affect testis function. Zn and iron (in plasma and testicular tissue), plasma antioxidant vitamins (A, E, and C), as well as testicular superoxide dismutase (SOD) and reduced glutathione (GSH), lipid peroxidation indexes (thiobarbituric acid reactive substances (TBARS) and lipoprotein oxidation susceptibility (LOS)), and inflammatory markers (plasma C-reactive protein (CRP) and testicular tumour necrosis factor-alpha (TNF-alpha)) were determined. Serum testosterone and histological examination of the testis were performed also. We found a severe decrease in antioxidant vitamins and Zn, with concomitant iron accumulation. Zinc deficiency correlated positively with SOD, GSH, antioxidant vitamins and testosterone, and negatively with TBARS, LOS, CRP and TNF-alpha, demonstrating a state of oxidative stress and inflammation. We concluded that micronutrient deficiency, especially Zn, enhanced oxidative stress and inflammation in testicular tissue leading to underdevelopment of testis and decreased testosterone levels.

Glutathione peroxidase-1 plays a major role in protecting against angiotensin II-induced vascular dysfunction

Levels of reactive oxygen species, including hydrogen peroxide(,) increase in blood vessels during hypertension and in response to angiotensin II (Ang II). Although glutathione peroxidases are known to metabolize hydrogen peroxide, the role of glutathione peroxidase during hypertension is poorly defined. We tested the hypothesis that glutathione peroxidase-1 protects against Ang II-induced endothelial dysfunction. Responses of carotid arteries from Gpx1-deficient (Gpx1(+/-) and Gpx1(-/-)) and Gpx1 transgenic mice, and their respective littermate controls, were examined in vitro after overnight incubation with either vehicle or Ang II. Under control conditions, relaxation to acetylcholine (ACh; an endothelium-dependent agonist) was similar in control, Gpx1(+/-), and Gpx1 transgenic mice, whereas in Gpx1(-/-) mice, responses to ACh were impaired. In control mice, ACh-induced vasorelaxation was not affected by 1 nmol/L of Ang II. In contrast, relaxation to ACh in arteries from Gpx1(+/-) mice was inhibited by approximately 60% after treatment with 1 nmol/L of Ang II, indicating that Gpx1 haploinsufficiency markedly enhances Ang II-induced endothelial dysfunction. A higher concentration of Ang II (10 nmol/L) selectively impaired relaxation to ACh in arteries from control mice, and this effect was prevented in arteries from Gpx1 transgenic mice or in arteries from control mice treated with polyethylene glycol-catalase (which degrades hydrogen peroxide). Thus, genetic and pharmacological evidence suggests a major role for glutathione peroxidase-1 and hydrogen peroxide in Ang II-induced effects on vascular function.

Suppression of atherogenesis by overexpression of glutathione peroxidase-4 in apolipoprotein E-deficient mice

Accumulation of oxidized lipids in the arterial wall contributes to atherosclerosis. Glutathione peroxidase-4 (GPx4) is a hydroperoxide scavenger that removes oxidative modifications from lipids such as free fatty acids, cholesterols, and phospholipids. Here, we set out to assess the effects of GPx4 overexpression on atherosclerosis in apolipoprotein E-deficient (ApoE(-/-)) mice. The results revealed that atherosclerotic lesions in the aortic tree and aortic sinus of ApoE(-/-) mice overexpressing GPx4 (hGPx4Tg/ApoE(-/-)) were significantly smaller than those of ApoE(-/-) control mice. GPx4 overexpression also diminished signs of advanced lesions in the aortic sinus, as seen by a decreased occurrence of fibrous caps and acellular areas among hGPx4Tg/ApoE(-/-) animals. This delay of atherosclerosis in hGPx4Tg/ApoE(-/-) mice correlated with reduced aortic F(2)-isoprostane levels (R(2)=0.75, p<0.01). In addition, overexpression of GPx4 lessened atherogenic events induced by the oxidized lipids lysophosphatidylcholine and 7-ketocholesterol, including upregulated expression of adhesion molecules in endothelial cells and adhesion of monocytes to endothelial cells, as well as endothelial necrosis and apoptosis. These results suggest that overexpression of GPx4 inhibits the development of atherosclerosis by decreasing lipid peroxidation and inhibiting the sensitivity of vascular cells to oxidized lipids.

Superoxide dismutase activity in gingiva in type-2 diabetes mellitus patients with chronic periodontitis

OBJECTIVE

Antioxidant defence reduces in diabetes mellitus (DM) and periodontitis. This study investigates antioxidant enzyme; superoxide dismutase (SOD) activity in gingiva and blood glucose and lipid levels in type-2 DM patients and systemically healthy individuals with chronic periodontitis (CP).

MATERIALS AND METHODS

Periodontal parameters, blood glycated-haemoglobin (HbA1c), glucose and lipid levels, and gingival-SOD activities (spectrophotometric assay) were measured in 17 DM patients with CP (DMCP), 17 systemically healthy CP patients, 18 periodontally healthy DM patients (DMPH), and 17 healthy controls (PH).

RESULTS

Periodontal parameters were higher in periodontitis groups than the controls (p<0.05), while there was no difference between the periodontitis groups and between the control groups. HbA1c, glucose, and triglyceride levels were higher in diabetic groups than the non-diabetic groups (p<0.05). Low-density lipoprotein (LDL), very-LDL and cholesterol values of the DMCP group did not significantly differ from the CP group. No differences existed between diabetic patients with and without periodontitis in HbA1c, glucose, and lipid levels and the same was true for non-diabetic patients with and without periodontitis. Gingival-SOD activity was lower in periodontitis groups than the matched control groups (p<0.05). DMPH group had the highest and CP group had the lowest SOD levels. There were correlations between periodontal parameters, gingival-SOD activity, HbA1c, glucose and high-density lipoprotein (HDL) levels.

CONCLUSION

The results suggest that gingival-SOD activity increases in diabetes and decreases in periodontitis and relations may exist between gingival-SOD activity, periodontal status, HbA1c, glucose and HDL levels. The higher gingival-SOD activity in diabetes may be attributed to an adaptive mechanism in the tissue.

Oxidative damage markers and antioxidants in patients with acute myocardial infarction and their clinical significance

Oxidative stress has been associated with degenerative diseases such as cardiovascular and neurodegenerative diseases. Acute myocardial infarction (AMI) is the major cause of death among cardiovascular diseases. Inflammation, a major risk factor of AMI, is associated with leukocytic activation, secretion of myeloperoxidase (MPO) and subsequent oxidant generation. It has been hypothesized that oxidative stress is a risk factor for AMI. To test this hypothesis, we studied profiles of oxidative damage and antioxidants in patients with AMI. The levels of MPO, 8-OHdG, and 3-Cl-Tyr were higher in blood specimens from AMI patients than in those of controls. Antioxidant levels, such as vitamin E and glutathione peroxidase, were significantly lower in these patients. The GSH/GSSG ratio, indicative of redox status, was also lower in AMI patients. Such findings suggest that these AMI patients experience increased oxidative stress. Moreover, markers in combination are better for evaluating antioxidant status and monitoring cardiac events than the same markers used separately.

Atherosclerosis and oxidant stress: the end of the road for antioxidant vitamin treatment?

Extensive experimental data have revealed a central role for oxidative stress in atherogenesis and suggested a potential role for 'antioxidant' treatment in cardiovascular disease (CVD) [1-11]. Experimental data, however, have not translated into clinical benefit: most antioxidant vitamin trials have failed to reduce cardiovascular morbidity and mortality [12]. Moreover, recent clinical trials have suggested that mono-therapy with certain antioxidant vitamins like vitamin E may, in fact, be detrimental [13]. As a result of the disappointing outcome of 'antioxidant' vitamin trials, some authors have questioned both the utility of 'antioxidant' treatment in CVD and the supposedly central role of oxidative stress in atherogenesis [14-19]. Other investigators, however, sustain that the beneficial effects of lipid lowering and anti-hypertensive treatment are at least, in part, due to their 'antioxidant' properties, in addition to their specific pharmacological properties [20, 21]. Oxidant stress plays a pivotal role in atherogenesis, however, the clinical promise of antioxidant vitamins has failed to translate into clinical benefit. Increasing evidence suggests that more rigorous clinical trial designs are necessary to effectively divulge antioxidant utility and that a multifaceted antioxidant approach to atherosclerosis may yield the most clinical reward. This article reviews currently available evidence on the role of oxidant stress in atherosclerosis, analyzes the results of large anti-oxidant trials, and suggests ways to investigate the true role of antioxidant treatment in the clinical setting.

Apolipoprotein E-deficient lipoproteins induce foam cell formation by downregulation of lysosomal hydrolases in macrophages

Apolipoprotein E (apoE) deficiency has been suggested to induce foam cell formation. Using lipoproteins obtained from wild-type mice and apoE-deficient mice expressing apoB-48 but not apoB-100, we studied apoE-deficient lipoprotein-induced changes in lipoprotein catabolism and protein expression in mouse peritoneal macrophages (MPMs). Our data demonstrate that incubation of MPMs with apoE-deficient lipoproteins induced intracellular lipoprotein, cholesteryl ester, and triglyceride accumulation, which was associated with a time-related decline in apoE-deficient lipoprotein degradation in MPMs. Confocal microscopy analysis indicated that the accumulated lipids were localized in lysosomes. ApoE-deficient lipoproteins reduced the protein levels of lysosomal acid lipase, cathepsin B, and cation-dependent mannose 6 phosphate receptor (MPR46). Exogenous apoE reduced apoE-deficient lipoprotein-induced lipid accumulation and attenuated the suppressive effect of apoE-deficient lipoproteins on lysosomal hydrolase and MPR46 expression. Although oxidized lipoproteins also increased lipid contents in MPMs, exogenous apoE could not attenuate oxidized lipoprotein-induced lipid accumulation. Our in vivo studies also showed that feeding apoE-deficient mice a high-fat diet resulted in cholesteryl ester and triglyceride accumulation and reduced lysosomal hydrolase expression in MPMs. These data suggest that apoE-deficient lipoproteins increase cellular lipid contents through pathways different from those activated by oxidized lipoproteins and that reducing lysosomal hydrolases in macrophages might be a mechanism by which apoE-deficient lipoproteins result in intralysosomal lipoprotein accumulation, thereby inducing foam cell formation.

Tanshinone II A attenuates atherosclerotic calcification in rat model by inhibition of oxidative stress

AIM

We have previously proved that oxidized low-density lipoprotein (oxLDL), a proatherogenic lipoprotein, plays a pivotal role in the development of atherosclerotic calcification (AC). The present study was performed to investigate whether tanshinone II A (TS II A), an anti-oxidant which has been shown to inhibit in vitro oxidation of LDL, has the effects to inhibit AC in rat model and by which, if any, mechanisms.

METHODS

Rat AC model was induced by excessive vitamin D(2) (VD) and high cholesterol diet (HCD), which was proven to be successful histopathologically and biochemically.

RESULTS

Administration of AC rats with TS II A (35, 70 mg/kg) dose-dependently attenuated the AC pathological changes, meanwhile reduced the vessel contents of lipid and calcium. However, TS II A had no effects on serum levels of lipids, calcium and 25-OH VD. Further studies revealed that TS II A decreased serum concentration of oxLDL, reduced the superoxide anion production and malondialdehyde (MDA) in vessel. In addition, TS II A increased vessel Cu/Zn SOD activity, upregulated vessel mRNA and protein expression of Cu/Zn SOD.

CONCLUSION

The results suggested that TS II A significantly attenuated the AC in rat model, which might be attributed to its inhibition of oxLDL production independent of the serum levels of lipids, calcium and 25-OH VD, and that increasing of Cu/Zn SOD activity as well as mRNA and protein expression by TS II A might protect LDL against oxidation induced by superoxide anion in vessel.

Biomarkers of obesity and subsequent cardiovascular events

Obesity is a major risk factor for cardiovascular diseases, but the mechanisms for increased cardiovascular risk in obesity are still unclear. Inflammation and increased oxidative stress are two potential mechanisms proposed to play a major role in the morbidity associated with obesity. Studies that investigate these mechanisms rely on biomarkers, but validated biomarkers for obesity-related cardiovascular outcomes are lacking. By finding optimal biomarkers, diagnostic criteria for cardiovascular diseases can be refined in the obese beyond "traditional" risk factors to identify early pathologic processes. The objective of this review is to identify potential early biomarkers resulting from obesity and associated with cardiovascular disease. Studies were initially identified through the search engine PubMed by using the keywords "obesity" and "biomarker." Subsequently, combinations of the keywords "obesity," "biomarker," "cardiovascular risk," "adipose tissue," "adipokine," "adipocytokine," and "oxidative stress" were used. The SOURCE database and Online Mendelian Inheritance in Man (OMIM) were used to obtain more information on the biomarkers. Results of the searches yielded a large number of potential biomarkers that occur in obesity and which either correlate with traditional cardiovascular risk factors or predict subsequent cardiovascular events. Several biomarkers are promising regarding their biologic properties, but they require further validation in humans.

Role of mitochondrial reactive oxygen species in hypoxia-dependent increase in intracellular calcium in pulmonary artery myocytes

Previous studies examining the role of mitochondria-derived reactive oxygen species (ROS) in hypoxic responses have been mainly conducted in isolated lungs and cultured pulmonary artery smooth muscle cells (PASMCs) using mitochondrial inhibitors, and yielded largely conflicting results. Here we report that in freshly isolated mouse PASMCs, which are devoid of the mixed responses from multi-types of cells in lungs and significant changes in gene expression in cultured cells, the mitochondrial electron transport chain (ETC) complex I, II, or III inhibitors blocked hypoxia-induced increases in intracellular ROS and Ca2+ concentration ([ROS]i and [Ca2+]i) without effects on their resting levels. Inhibition of the complex I plus II and/or III did not produce an additive effect. Glutathione peroxidase-1 (Gpx1) or catalase gene overexpression to enhance H2O2 removal remarkably reduced hypoxic increases in [ROS]i and [Ca2+]i, whereas Gpx1 gene deletion had the opposite effect. None of these genetic modifications changed the resting [ROS]i and [Ca2+]i. H2O2 at 51 microM caused a similar increase in DCF fluorescence ([ROS]i) as that by hypoxia, but only induced 33% of hypoxic increase in [Ca2+]i. Moreover, H2O2 (5.1 microM) reversed the inhibition of the hypoxia-induced increase in [Ca2+]i by rotenone. Collectively, our study using various mitochondrial inhibitors and genetic approaches demonstrates that in response to acute hypoxia, the mitochondrial ETC molecules prior to the complex III ubisemiquinone site act as a functional unit to increase the generation of ROS, particularly H2O2, which is important for, but may not fully cause, the hypoxic increase in [Ca2+]i in freshly isolated PASMCs.

Superoxide dismutase and catalase inhibit oxidized low-density lipoprotein-induced human aortic smooth muscle cell proliferation: Role of cell-cycle regulation, mitogen-activated protein kinases, and transcription factors

Several antioxidant enzymes, including copper, zinc-superoxide dismutase (Cu, Zn-SOD) and catalase, have been suggested to be protective against the proliferation of vascular smooth muscle cells exposed to oxidative stress. In the present study, we investigated effects of Cu, Zn-SOD and/or catalase on oxLDL-induced proliferation of, and intracellular signaling in, human aortic smooth muscle cells (HASMCs). HASMCs were transfected with adenovirus carrying the human Cu, Zn-SOD gene and/or the human catalase gene. This resulted in a high level of Cu, Zn-SOD and/or catalase overexpression and decreased oxLDL-induced proliferation. Cu, Zn-SOD and/or catalase also arrested cell cycle progression, which was associated with decreased expression of cyclin D1, cyclin E, CDK2, and CDK4 and upregulation of p21(Cip1) and p27(Kip1). Phosphorylation studies on ERK1/2, JNK, and p38, three major subgroups of mitogen activator protein kinases, demonstrated that Cu, Zn-SOD and/or catalase overexpression suppressed ERK1/2 and JNK phosphorylation. Gel-mobility shift analysis showed that oxLDL caused an increase in the DNA binding activity of activator protein-1 (AP-1) and nuclear factor kappaB (NF-kappaB), which was inhibited by Cu, Zn-SOD and/or catalase overexpression. These results provide the first evidence that overexpression of Cu, Zn-SOD and/or catalase in HASMCs attenuates the cell proliferation caused by oxLDL stimulation and that this inhibitory effect is mediated via downregulation of ERK1/2 and JNK phosphorylation and AP-1 and NF-kappaB inactivation. These observations support the feasibility of the increase of Cu, Zn-SOD and/or catalase expression in human smooth muscle cells as a means of protection against oxidant injury.

Reduction in extracellular superoxide dismutase activity in African-American patients with hypertension

Superoxide anions react with nitric oxide to form peroxynitrite and hence reduce the bioavailability of nitric oxide in the arteries. Extracellular superoxide dismutase (EC-SOD) is a major superoxide scavenger in human plasma and vascular tissues. The objective of this study is to assess whether essential hypertension is associated with an alteration in EC-SOD activity. In this report, blood samples were obtained from hypertensive (n=39) and normotensive (n=37) African-Americans. Plasma EC-SOD activity was measured using in-gel activity staining and spectrophotometric assays, EC-SOD protein level was measured using Western blotting, nitrotyrosine was measured using slot blotting, 8-isoprostane was measured with an enzyme immunoassay, and plasma copper and zinc concentrations were measured using an atomic absorption assay. Our data demonstrate that the copper, zinc, and plasma EC-SOD protein concentrations in the hypertensive and normotensive subjects are indistinguishable. Compared to normotensive controls, hypertensive patients have significantly reduced plasma EC-SOD activity. Plasma nitrotyrosine and 8-isoprostane levels are significantly higher in the hypertensive patients than in normotensive controls. Results from this study suggest that a reduction in EC-SOD activity in hypertensive patients is not due to a down-regulation of the SOD3 gene (encoding EC-SOD) or deficiency in mineral cofactors. Furthermore, the reduced EC-SOD activity might be at least partially responsible for the increased oxidative stress, as reflected by increased plasma nitrotyrosine and 8-isoprostane, in hypertensive subjects.