Overexpression of human superoxide dismutase inhibits oxidation of low-density lipoprotein by endothelial 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.

Association of blood manganese concentrations with 24-h based brachial and central blood pressure, and pulse-wave velocity

Potential environmental determinants of BP and hypertension in older adults are far less known than their lifestyle risk factors. Manganese (Mn) is an essential element for life that may induce changes in blood pressure (BP), but the direction of the association is unclear. We aimed to examine the association of blood manganese (bMn) with 24-h-based brachial, central BP (cBP), and pulse-wave velocity (PWV). With this purpose, we analyzed data from 1009 community-living adults aged >65 years without BP medication. bMn was measured using inductively-coupled plasma-mass spectrometry and 24-h BP with validated devices. The association of bMn (median: 6.77 μg/L; IQR: 5.59-8.27) with daytime brachial and central systolic (SBP) and with diastolic BP (DBP) was non-linear, with BP increases up to around the median of Mn and then stabilization or slight rightward decrease. Mean BP differences (95% confidence interval) comparing Mn Q2 to Q5 (vs Q1 quintile) for brachial daytime SBP were 2.56 (0.22; 4.90), 3.59 (1.22; 5.96), 3.14 (0.77; 5.51) and 1.72 (-0.68; 4.11) mmHg, respectively; and 2.22 (0.70, 3.73), 2.55 (1.01, 4.08), 2.45 (0.91; 3.98), and 1.68 (0.13; 3.24), respectively, for DBP. Daytime central-pressures showed a similar dose-response relationship with bMn as daytime brachial-pressures. The association with nighttime BP was linearly positive for brachial BPs, and only increasing for Q5 for cBP. Regarding PWV, a tendency to significant linear increase along bMn levels was observed (p-trend = 0.042). The present findings extend the scarce evidence on the association between Mn and brachial BP to 2 other vascular parameters, suggesting Mn levels as a candidate risk factor for increasing levels of both brachial and cBPs in older adults, yet further research is needed with larger cohort studies in adults at all age ranges.

A Study of Associations Between rs9349379 (PHACTR1), rs2891168 (CDKN2B-AS), rs11838776 (COL4A2) and rs4880 (SOD2) Polymorphic Variants and Coronary Artery Disease in Iranian Population

Recent genome-wide association studies reported the association of polymorphic alleles of PHACTR1 (rs9349379 (G)), CDDKN2B-AS1 (rs2891168 (G)), COL4A2 (rs11838776 (A)) and SOD2 (rs4880 (T)) with increased risk of coronary artery disease (CAD). The aim of our study was to assess the association of genetic variants with risk of CAD and its severity and in Southeast Iranian population. This study was examined in 250 CAD-suspected patients (mean age 53.49 ± 6.9 years) and 250 healthy individuals (mean age 52.96 ± 5.9 years). The Taqman SNP genotyping assay was used for genotyping of rs9349379 and rs2891168 variants. Tetra-primer Amplified refractory mutation system-PCR (Tetra-primer ARMS-PCR) was employed for rs11838776 and rs4880. Multivariate logistic regression analyses indicated that the G allele of rs9349379 and rs2891168 were associated with increased risk of CAD. The GG homozygous genotype of rs9349379 and rs2891168 had also been associated with risk of CAD. Additionally, the AG genotype of rs2891168 was associated with CAD. The significance of association of rs2891168 (G, GG, AG) increases with severity of CAD; but the rs9349379 (G, GG) have shown reverse association with severity of CAD. The genetic variants of COL4A2 (rs11838776) and SOD2 (rs4880) reflected no association with CAD in Southeast Iranian population. The findings of this study revealed that the PHACTR1 (rs9349379) and CDKN2B-AS1 (rs2891168) genetic variants might serve as genetic risk factor in CAD.

Role of reactive oxygen species in atherosclerosis: Lessons from murine genetic models

Atherosclerosis is a multifactorial chronic and inflammatory disease of medium and large arteries, and the major cause of cardiovascular morbidity and mortality worldwide. The pathogenesis of atherosclerosis involves a number of risk factors and complex events including hypercholesterolemia, endothelial dysfunction, increased permeability to low density lipoproteins (LDL) and their sequestration on extracellular matrix in the intima of lesion-prone areas. These events promote LDL modifications, particularly by oxidation, which generates acute and chronic inflammatory responses implicated in atherogenesis and lesion progression. Reactive oxygen species (ROS) (which include both free radical and non-free radical oxygen intermediates), play a key-role at each step of atherogenesis, in endothelial dysfunction, LDL oxidation, and inflammatory events involved in the initiation and development of atherosclerosis lesions. Most advanced knowledge supporting the "oxidative theory of atherosclerosis" i.e. the nature and the cellular sources of ROS and antioxidant defences, as well as the mechanisms involved in the redox balance, is based on the use of genetically engineered animals, i.e. transgenic, genetically modified, or altered for systems producing or neutralizing ROS in the vessels. This review summarizes the results obtained from animals genetically manipulated for various sources of ROS or antioxidant defences in the vascular wall, and their relevance (advance or limitation), for understanding the place and role of ROS in atherosclerosis.

The Essential Element Manganese, Oxidative Stress, and Metabolic Diseases: Links and Interactions

Manganese (Mn) is an essential element that is involved in the synthesis and activation of many enzymes and in the regulation of the metabolism of glucose and lipids in humans. In addition, Mn is one of the required components for Mn superoxide dismutase (MnSOD) that is mainly responsible for scavenging reactive oxygen species (ROS) in mitochondrial oxidative stress. Both Mn deficiency and intoxication are associated with adverse metabolic and neuropsychiatric effects. Over the past few decades, the prevalence of metabolic diseases, including type 2 diabetes mellitus (T2MD), obesity, insulin resistance, atherosclerosis, hyperlipidemia, nonalcoholic fatty liver disease (NAFLD), and hepatic steatosis, has increased dramatically. Previous studies have found that ROS generation, oxidative stress, and inflammation are critical for the pathogenesis of metabolic diseases. In addition, deficiency in dietary Mn as well as excessive Mn exposure could increase ROS generation and result in further oxidative stress. However, the relationship between Mn and metabolic diseases is not clear. In this review, we provide insights into the role Mn plays in the prevention and development of metabolic diseases.

Mitochondrial Electron Transport Chain-Derived Superoxide Exits Macrophages: Implications for Mononuclear Cell-Mediated Pathophysiological Processes

The involvement of mitochondrial electron transport chain (METC)-derived superoxide anion radical in cell protooncogene activation, mitogenic responses, and cancerous growth has recently received much attention. In order for METC-derived superoxide to participate in any of the above processes, its exit from mitochondria would be a critical step. Detection of intracellular superoxide showed that mitochondrial respiration is the major source of cellular superoxide in unstimulated or resting monocytes/macrophages. However, direct evidence for the exit of superoxide from mitochondria is presently lacking. Here we show that METC-derived superoxide does exit from mitochondria in unstimulated monocytes/macrophages. Release of superoxide was first found to occur with substrate-supported mitochondria isolated from these cells. We also observed the presence of extracellular superoxide with the intact unstimulated/resting cells. Extracellular superoxide was markedly diminished (>90%) by the mitochondrial inhibitor, rotenone, or the uncoupler, carbonylcyanide p-(trifluromethy) phenylhydrazone. Furthermore, cells with a deficient METC exhibited significant reduction (>90%) in extracellular superoxide, demonstrating that with intact cells METC-derived superoxide not only exits from mitochondria, but can be released extracellularly. Superoxide anion radical released from mitochondria could react with exogenous nitric oxide, forming peroxynitrite. Mitochondria-derived extracellular superoxide could also oxidize low-density lipoprotein (LDL). These results thus resolve any uncertainty on the ability of superoxide to exit from mitochondria. This study for the first time also identifies mitochondria as the major source of extracellular superoxide in unstimulated resting monocytes/macrophages, which has implications for the involvement of these mononuclear cells in various pathophysiological situations.

Cell-based screening identifies the active ingredients from Traditional Chinese Medicine formula Shixiao San as the inhibitors of atherosclerotic endothelial dysfunction

In this study, we performed a phenotypic screening in human endothelial cells exposed to oxidized low density lipoprotein (an in vitro model of atherosclerotic endothelial dysfunction) to identify the effective compounds in Shixiao San. After investigating the suitability and reliability of the cell-based screening method using atorvastatin as the positive control drug, this method was applied in screening Shixiao San and its extracts. The treatment of n-butanol fraction on endothelial cells exhibited stronger healing effects against oxidized low density lipoprotein-induced insult when compared with other fractions. Cell viability, the level of nitric oxide, endothelial nitric oxide synthase and endothelin-1 were measured, respectively. The assays revealed n-butanol fraction significantly elevated the survival ratio of impaired cells in culture. In parallel, n-butanol fraction exhibited the highest inhibition of inflammation. The generation of prostaglandin-2 and adhesion molecule (soluble intercellular adhesion molecule-1) was obviously declined. Furthermore, n-butanol fraction suppressed the production of reactive oxygen species and malondialdehyde, and restored the activity of superoxide dismutase. Compounds identification of the n-butanol fraction was carried out by ultra high liquid chromatography coupled to quadrupole time-of-flight tandem mass spectrometry. The active ingredients including quercetin-3-O-(2G-α-l-rhamnosyl)-rutinoside, quercetin-3-O-neohesperidoside, isorhamnetin-3-O-neohesperidoside and isorhamnetin-3-O-rutinoside revealed the ability of anti-atherosclerosis after exposing on endothelial cells. The current work illustrated the pharmacology effect of Shixiao San and clearly indicated the major active components in Shixiao San. More importantly, the proposed cell-based screening method might be particularly suitable for fast evaluating the anti-atherosclerosis efficacy of Traditional Chinese Medicines and screening out the interesting ingredients of Traditional Chinese Medicines.

Evaluation of oxidant-antioxidant status in overweight and morbidly obese Saudi children

AIM: To evaluate the antioxidant enzymes and oxidative products in overweight and obese Saudi children before the onset of metabolic complications.

METHODS: The study was carried out on 231 Saudi children. They were classified into three groups: uncomplicated overweight, uncomplicated morbid obesity, and the matched age group as control. All subjects underwent anthropometric measurements and activities of superoxide dismutase, catalase, glutathione peroxidase (GSH-Px), glutathione reductase, the concentrations of reduced GSH, malondialdehyde (MDA) oxidized low-density lipoprotein (ox-LDL) and advanced oxidation protein products (AOPPs) were measured in the blood of these groups.

RESULTS: Overweight and obese children had a significantly higher body mass index, while obese children only had a significantly higher waist-to-hip ratio compared to that of the control group. The enzyme activities under study were significantly elevated in the overweight group, although they were significantly reduced among obese children. The concentration of GSH was reduced in both the overweight and obese groups. The mean values of ox-LDL, MDA and AOPP were non-significantly increased in overweight children, while they were significantly elevated in obese children compared to that of normal weight children. A significant disturbance of oxidant-antioxidant status was observed in severely morbid children.

CONCLUSION: The increase of oxidative stress in obese children is associated with the increase in AOPPs and MDA which reflects an imbalance between reactive oxygen species production and antioxidant defense.

Lactobacillus acidophilus ATCC 4356 attenuates the atherosclerotic progression through modulation of oxidative stress and inflammatory process

The aim of this study was to investigate the effect of Lactobacillus (L.) acidophilus ATCC 4356 on the progression of atherosclerosis in Apoliprotein-E knockout (ApoE(-/-)) mice and the underlying mechanisms. Eight week-old ApoE(-/-) mice were treated with L. acidophilus ATCC 4356 daily for 12 weeks. The wild type (WT) mice or ApoE(-/-) mice in the vehicle group were treated with saline only. Body weights, serum lipid levels, aortic atherosclerotic lesions, and tissue oxidative and inflammatory statuses were examined among the groups. As compared to ApoE(-/-) mice in the vehicle group, ApoE(-/-) mice treated with L. acidophilus ATCC 4356 had no changes in body weights and serum lipid profiles, but showed decreased atherosclerotic lesion size in en face aorta. In comparison with WT mice, ApoE(-/-) mice in the vehicle group showed higher levels of serum malondialdehyde (MDA), oxidized low density lipoprotein (oxLDL) and tumor necrosis factor-alpha (TNF-α), but lower levels of interleukin-10 (IL-10) and superoxide dismutase (SOD) activities in serum. Administration of L. acidophilus ATCC 4356 could reverse these trends in a dose-dependent manner in ApoE(-/-) mice. Furthermore, ApoE(-/-) mice treated with L. acidophilus ATCC 4356 showed an inhibition of translocation of NF-κB p65 from cytoplasm to nucleus, suppression of degradation of aortic IκB-α, and improvements of gut microbiota distribution, as compared to ApoE(-/-) mice in the vehicle group. Our findings suggest that administration of L. acidophilus ATCC 4356 can attenuate the development of atherosclerotic lesions in ApoE(-/-) mice through reducing oxidative stress and inflammatory response.

Oxidized low-density lipoproteins impair endothelial function by inhibiting non-genomic action of thyroid hormone-mediated nitric oxide production in human endothelial cells

BACKGROUND

Thyroid hormone (TH) plays an important role in the modulation of cardiac function, including contractility and systemic vascular resistance (SVR). 3,5,3'-triiodothyronine (T(3)), the active form of TH, induces the activation of endothelial nitric oxide synthase via PI3K/AKT non-genomic signaling. Hypothyroidism is associated with an increase in SVR and serum low-density lipoproteins (LDL) levels, and accumulation of oxidized LDL (oxLDL) may impair endothelial-dependent vascular relaxation. The aim of this study was to investigate the effects of both native LDL (nLDL) and oxLDL on T(3)-mediated AKT phosphorylation, nitric oxide (NO), and cyclic guanosine monophosphate (cGMP) production in human endothelial cells.

METHODS

Human umbilical vein endothelial cells were exposed to either nLDL or oxLDL for 3 hours and then stimulated with T(3) (10(-7) M) or pretreated with an antioxidant mixture of vitamins E and C for 12 hours before treatment with LDL. An analysis of AKT phosphorylation was performed by Western blot, and NO production was evaluated by using 4,5-diaminofluorescein diacetate. Intracellular production of cGMP was measured by enzymatic immunoassay. LDL oxidation was carried out by incubating LDL with CuSO(4), and α-tocopherol content of LDL was evaluated by high-performance liquid chromatography.

RESULTS

OxLDL impaired T(3)-mediated AKT phosphorylation at serine 473 and significantly decreased the production of both NO (oxLDL+T(3) vs. T(3), 9.79±0.5 AU vs. 80.75±2.8 AU, mean±standard deviation, p<0.0001) and cGMP. Furthermore, pretreatment with the antioxidant mixture obviated the inhibitory effect of LDL on T(3) action.

CONCLUSIONS

The results of this study demonstrate that oxLDL may contribute to a blunting of the non-genomic action of T(3) and impair the effect of T(3) on NO and cGMP production in endothelial cells. These data suggest that oxLDL, apart from inducing the atherosclerotic process, may also promote a mechanism of peripheral resistance to T(3,) further amplifying the impact of hypothyroidism on endothelial function by increasing SVR.

Changes in expression of the antioxidant enzyme SOD3 occur upon differentiation of human bone marrow-derived mesenchymal stem cells in vitro

The discovery that mesenchymal stem cells (MSCs) secrete SOD3 may help explain studies in which MSCs have direct antioxidant activities both in vivo and in vitro. SOD3 is an antioxidant enzyme that dismutes toxic free radicals produced during inflammatory processes. Therefore, MSC production and secretion of active and therapeutically significant levels of SOD3 would further support the use of MSCs as a cellular based antioxidant therapy. The aim of this study was therefore to investigate in vitro if MSC differentiation down the adipogenic, chondrogenic, and osteogenic lineages influences the expression of the antioxidant molecule SOD3. Human bone marrow MSCs and their differentiated progeny were cultured under standard conditions and both the SOD3 gene and protein expression examined. Following adipogenesis, cultures demonstrated that both SOD3 protein and gene expression are significantly increased, and conversely, following chondrogenesis SOD3 protein and gene expression is significantly decreased. Following osteogenesis there were no significant changes in SOD3 protein or gene expression. This in vitro study describes the initial characterization of SOD3 expression and secretion by differentiated MSCs. This should help guide further in vivo work establishing the therapeutic and antioxidative potential of MSC and their differentiated progeny.

Association of C47T polymorphism in SOD2 gene with coronary artery disease: a case-control study and a meta-analysis

Oxidative damage promotes atherosclerosis. SOD2 is an important antioxidant enzyme. A case-control study and a meta-analysis were performed to assess the association of C47T polymorphism in SOD2 gene with premature, late-onset and overall coronary artery disease (CAD) risk. A hospital-based case-control study was conducted with 269 premature CAD cases, 278 late-onset CAD cases and 299 healthy controls. Polymerase chain reaction (PCR) and Pyrosequencing were used to detect the polymorphism. Multinomial logistic regression model was performed to estimate odds ratio (OR) with 95% confidence intervals (CIs) and adjust potential confounders. A meta-analysis was performed using eight outcomes including our result. Fixed or random effect pooled measure was selected on the basis of homogeneity test among studies. Heterogeneity among studies was evaluated using I (2). Meta-regression was used to explore potential sources of between-study heterogeneity. Publication bias was estimated using Peters's linear regression test. In our case-control study, compared with the TT as the reference, the mutant genotype of CC + TC was significantly associated with a reduced premature CAD risk both in univariate (OR = 0.60, 95% CI = 0.41-0.87) and multivariate (OR = 0.59, 95% CI = 0.40-0.87) logistic regressions, but not with late-onset CAD risk. After excluding one article that deviated from Hardy-Weinberg equilibrium in controls, this meta-analysis showed a significant association of the C allele with reduced risk of CAD in dominant (FEM: OR = 0.69, 95% CI = 0.61-0.78), recessive (OR = 0.64, 95% CI = 0.50-0.82), and codominant (FEM: OR = 0.73, 95% CI = 0.65-0.80) models. Our study suggested that the mutant genotype of CC + TC was significantly associated with a reduced CAD risk.

Chromium and manganese levels in biological samples of Pakistani myocardial infarction patients at different stages as related to controls

It has been speculated that trace elements may play a role in the pathogenesis of heart diseases In the present study, we aimed to access the levels of chromium (Cr) and manganese (Mn) in biological samples (whole blood, urine, and scalp hair) of myocardial infarction (MI) patients of both gender age ranged (45-60 years) at first, second, and third heart attack (n = 130), hospitalized in cardiac ward of National Hospital of Hyderabad city (Pakistan). For comparison, healthy age-matched referent subjects (n = 61), of both gender were also selected. The Cr and Mn in biological samples were measured by electrothermal atomic absorption spectrometry, prior to microwave-assisted acid digestion. The validity of the methodology was checked by the biological certified reference materials. During this study, 78% of 32 registered patients of third MI attack (aged >50 years) were died. In these subjects the concentration of Cr and Mn were decreased by 24.7% and 19.8% in scalp hair, while in blood samples 17.9% and 12.4%, respectively, as compared to those who tolerated third MI attack (p = 0.063). Although these data do not prove a causal relationship, these results are consistent with the hypothesis that heart disease may cause deficiencies of certain essential trace elements. The excretion levels of Cr and Mn in urine samples of first MCI were higher than controls at p values (0.029 and 0.011), respectively, whereas the excretion rates of both elements were further enhance after second myocardial infarction attack. The Cr and Mn concentration was inversely associated with the risk of myocardial infarction attacks in both genders. These results add to an increasing body of evidence that, Cr and Mn are importance for cardiovascular health.

Dietary rice protein isolate attenuates atherosclerosis in apoE-deficient mice by upregulating antioxidant enzymes

Rice-based diets may have been reported to protect against the development of atherosclerosis; however, the underlying mechanism(s) for this protection remains unknown. In this report, the mechanism(s) contributing to the atheroprotective effects of rice-based diet was addressed using the apolipoprotein E knockout (apoE-/-) mice fed rice protein isolate (RPI) or casein (CAS). Reduced atherosclerotic lesions were observed in aortic sinus and enface analyses of the descending aorta in RPI-fed apoE-/- mice compared with CAS-fed mice. Plasma total- and HDL-cholesterol levels were not different amongst the two groups, suggesting alternative mechanism(s) could have contributed to the atheroprotective effect of rice-based diets. Plasma oxLDL and anti-oxLDL IgG levels were significantly decreased in RPI-fed compared to CAS-fed animals. Plasma and aortic tissue GSH levels and GSH:GSSG ratio were higher in RPI-fed mice compared to CAS-fed group. Interestingly, RPI feeding increased mRNA and protein expression of superoxide dismutase, and mRNA expression of catalase, glutathione peroxidase and glutathione reductase, key antioxidant enzymes implicated inhibiting oxidative stress leading to atherosclerosis. In conclusion, these findings suggest that the reduction in atherosclerotic lesions observed in mice fed the rice-based diet is mediated in part by inhibiting oxidative stress and subsequent oxLDL generation that could result in reduced foam cell formation, an early event during atherogenesis.

Oxidized low-density lipoprotein-activated c-Jun NH2-terminal kinase regulates manganese superoxide dismutase ubiquitination: implication for mitochondrial redox status and apoptosis

OBJECTIVE

Oxidized low-density lipoprotein (oxLDL) modulates intracellular redox status and induces apoptosis in endothelial cells. However, the signal pathways and molecular mechanism remain unknown. In this study, we investigated the role of manganese superoxide dismutase (Mn-SOD) on oxLDL-induced apoptosis via c-Jun NH2-terminal kinase (JNK)-mediated ubiquitin/proteasome pathway.

METHODS AND RESULTS

OxLDL induced JNK phosphorylation that peaked at 30 minutes in human aortic endothelial cells. Fluorescence-activated cell sorting analysis revealed that oxLDL increased mitochondrial superoxide production by 1.88+/-0.19-fold and mitochondrial membrane potential by 18%. JNK small interference RNA (siJNK) reduced oxLDL-induced mitochondrial superoxide production by 88.4% and mitochondrial membrane potential by 61.7%. OxLDL did not affect Mn-SOD mRNA expression, but it significantly reduced Mn-SOD protein level, which was restored by siJNK. Immunoprecipitation by ubiquitin antibody revealed that oxLDL increased ubiquitination of Mn-SOD, which was inhibited by siJNK. OxLDL-induced caspase-3 activities were also attenuated by siJNK but were enhanced by Mn-SOD small interfering RNA. Furthermore, overexpression of Mn-SOD abrogated oxLDL-induced caspase-3 activities.

CONCLUSIONS

OxLDL-induced JNK activation regulates mitochondrial redox status and Mn-SOD protein degradation via JNK-dependent ubiquitination, leading to endothelial cell apoptosis.

Association of the manganese superoxide dismutase polymorphism with vasospastic angina pectoris

BACKGROUND

Vasospastic angina (VSA) is closely related to endothelial dysfunction caused by oxidative damage. Manganese superoxide dismutase (MnSOD) is an antioxidant enzyme that functions in mitochondria. There are two genetic variants of MnSOD arising from a substitution of an alanine for a valine in the signal peptide. We previously reported that the valine allele of MnSOD decreases the mitochondrial MnSOD (mtMnSOD) activity. Here, we investigated the association of the MnSOD polymorphism (Ala16Val) with VSA.

METHODS AND RESULTS

Blood samples were collected from 618 healthy subjects who did not have any symptoms or other evidence suggesting angina pectoris, and 228 patients who underwent coronary angiography on suspicion of angina, and were diagnosed to have VSA by acetylcholine test. MnSOD genotype of each subject was determined by real-time polymerase chain reaction. The valine allele frequency was higher in the VSA patients (0.890) than in the healthy subjects (0.839) [odds ratio (OR)=1.55, p=0.0085]. In healthy subjects the MnSOD genotype distribution was as follows: alanine/alanine 1.9%, alanine/valine 28.3%, and valine/valine 69.8%, and in VSA patients the prevalence was: alanine/alanine 1.3%, alanine/valine 19.3%, and valine/valine 79.4%. Thus, the valine allele was closely associated with VSA (p=0.019). Multivariate logistic regression analysis showed valine/valine homozygosity to be an independent risk factor for VSA (OR=2.02, 95% CI 1.43, 2.85; p=0.0012).

CONCLUSION

The valine variant of MnSOD signal peptide increases the risk of VSA.

Alpha-tocopherol modulates human umbilical vein endothelial cell expression of Cu/Zn superoxide dismutase and catalase and lipid peroxidation

Recent studies suggest the potential of alpha-tocopherol as a gene regulator, possibly through peroxisome proliferator-activated receptor gamma (PPARgamma) activation due to the structural similarity of alpha-tocopherol to a PPARgamma ligand, troglitazone. Other investigators have suggested that a link exists between induction of the antioxidant enzymes Cu/Zn superoxide dismutase (SOD) and catalase and PPARgamma activation. This study was designed to examine whether alpha-tocopherol modulates expression of Cu/Zn SOD and catalase in human umbilical vein endothelial cells through redox-sensitive transcription factors, PPARgamma, and nuclear factor-kappaB (NF-kappaB). Alpha-tocopherol treatments showed significant increases in both PPARgamma (1.4- to 2.2-fold, P < .01) and NF-kappaB p50 (1.3- to 1.5-fold, P < .005) DNA binding activities compared with vehicle control. Significant increases in Cu/Zn SOD mRNA levels (6.0-fold, P < .005) and catalase mRNA (8.0-fold, P < .005) and its protein levels (2.3-fold, P < .005) and lipid peroxidation levels (5.3-fold, P < .005) were observed at the lowest concentration (10 mumol/L) of alpha-tocopherol treatments. Both mRNA and protein levels of these 2 antioxidant enzymes were positively associated with lipid peroxidation (P < .05). Alpha-tocopherol may play a role not only in preventing against oxidative damage as an exogenous antioxidant by scavenging free radicals and superoxide but also in modulating the expression of the endogenous antioxidant enzymes as a gene regulator through PPARgamma and NF-kappaB in the vascular cells. The alpha-tocopherol-mediated gene expression is either stimulatory or inhibitory, depending on its oxidative status or its concentrations.

Conjugated linoleic acid modulation of risk factors associated with atherosclerosis

Conjugated linoleic acid (CLA) has been the subject of extensive investigation regarding its possible benefits on a variety of human diseases. In some animal studies, CLA has been shown to have a beneficial effect on sclerotic lesions associated with atherosclerosis, be a possible anti-carcinogen, increase feed efficiency, and act as a lean body mass supplement. However, the results have been inconsistent, and the effects of CLA on atherogenesis appear to be dose-, isomer-, tissue-, and species-specific. Similarly, CLA trials in humans have resulted in conflicting findings. Both the human and animal study results may be attributed to contrasting doses of CLA, isomers, the coexistence of other dietary fatty acids, length of study, and inter-and/or intra-species diversities. Recent research advances have suggested the importance of CLA isomers in modulating gene expression involved in oxidative damage, fatty acid metabolism, immune/inflammatory responses, and ultimately atherosclerosis. Although the possible mechanisms of action of CLA have been suggested, they have yet to be determined.

Conjugated linoleic acid modulation of risk factors associated with atherosclerosis

Conjugated linoleic acid (CLA) has been the subject of extensive investigation regarding its possible benefits on a variety of human diseases. In some animal studies, CLA has been shown to have a beneficial effect on sclerotic lesions associated with atherosclerosis, be a possible anti-carcinogen, increase feed efficiency, and act as a lean body mass supplement. However, the results have been inconsistent, and the effects of CLA on atherogenesis appear to be dose-, isomer-, tissue-, and species-specific. Similarly, CLA trials in humans have resulted in conflicting findings. Both the human and animal study results may be attributed to contrasting doses of CLA, isomers, the coexistence of other dietary fatty acids, length of study, and inter-and/or intra-species diversities. Recent research advances have suggested the importance of CLA isomers in modulating gene expression involved in oxidative damage, fatty acid metabolism, immune/inflammatory responses, and ultimately atherosclerosis. Although the possible mechanisms of action of CLA have been suggested, they have yet to be determined.

Age-dependent dichotomous effect of superoxide dismutase Ala16Val polymorphism on oxidized LDL levels

We investigated the association between superoxide dismutase (SOD) Ala16Val polymorphism and the levels of oxidized LDL lipoprotein-C (ox-LDL-C) in two age-different Greek cohorts. Four hundred fifteen middle-aged (n=147 females: 43.2+/-13 years, n=268 males: 43.3+/-14 years) Caucasian Greek subjects consisted the middle aged cohort. One hundred seventy five elderly (n=88 females: 79.9+/-4 years; n=87 males: 80.6+/-4 years) were selected from the elderly cohort. Genotype data were obtained for all of them. Multiple linear regression analysis, stratified by gender and adjusted for age, smoking habits and body mass index as covariates, showed higher ox-LDL-C levels for the middle aged men with the Val/Val genotype, compared to the other allele (Ala/Ala and Ala/Val) carriers (65.9+/-25.7 vs. 55.7+/-20.5 mg/dl; standardized beta coefficient=0.192, P=0.012). On the contrary, elderly women with the Val/Val genotype occurred with lower ox-LDL-C levels compared to the Ala/Ala or Ala/Val genotype (74.2+/-22.1 vs. 86.5+/-26.6 mg/dl; standardized beta coefficient= -0.269, P=0.015). The same trend was also recorded in elderly men, however without reaching statistical significance (standardized beta coefficient= -0.187, P=0.077). Moreover, elderly men and women with the Ala/Ala or Ala/Val genotype presented higher triglycerides levels compared to Val/Val (women: 145.2+/-68.7 vs. 114.3+/- 34.3 mg/dl, P= 0.027; men: 147.8+/-72.4 vs. 103.7 +/-38.0 mg/dl, P=0.002). Additionally, middle aged men with the Val/Val genotype had higher HDL-C levels compared to the Ala allele carriers. The results suggest that SOD Ala16Val polymorphism is an age-dependent modulator of ox-LDL-C levels in middle-aged men and elderly women.

Manganese superoxide dismutase polymorphism affects the oxidized low-density lipoprotein-induced apoptosis of macrophages and coronary artery disease

AIMS

Oxidative damage promotes atherosclerosis. Manganese superoxide dismutase (MnSOD) is an antioxidant enzyme localized in mitochondria. We investigated the associations of the MnSOD polymorphism (valine-to-alanine in the mitochondrial-targeting domain) with its activity in leukocytes, with macrophage apoptosis by oxidized low-density lipoprotein (oxLDL), and with coronary artery disease (CAD).

METHODS AND RESULTS

Blood samples were taken from 50 healthy subjects. The mitochondrial MnSOD activities in leukocytes were 542.4 +/- 71.6 U/mg protein (alanine/alanine, n = 2), 302.0 +/- 94.9 U/mg protein (alanine/valine, n = 12), and 134.0 +/- 67.1 U/mg protein (valine/valine, n = 36; P < 0.0001 for non-valine/valine vs. valine/valine). Macrophages were treated with oxLDL. After incubation, the percentages of apoptotic macrophages were 48.6 +/- 3.6% (alanine/alanine), 78.6 +/- 9.8% (alanine/valine), and 87.5 +/- 7.0% (valine/valine) (P < 0.0001, non-valine/valine vs. valine/valine). The association of the MnSOD polymorphism with CAD was investigated using blood samples collected from 498 CAD patients and 627 healthy subjects; the alanine allele was found to reduce the risk of CAD and acute myocardial infarction (AMI).

CONCLUSION

Our data indicate that the alanine variant of signal peptide increases the mitochondrial MnSOD activity, protects macrophages against the oxLDL-induced apoptosis, and reduces the risk of CAD and AMI.

Defective cholesterol traffic and neuronal differentiation in neural stem cells of Niemann-Pick type C disease improved by valproic acid, a histone deacetylase inhibitor

Niemann-Pick type C disease (NPC) is a neurodegenerative and lipid storage disorder for which no effective treatment is known. We previously reported that neural stem cells derived from NPC1 mice showed impaired self-renewal and differentiation. We examined whether valproic acid (VPA), a histone deacetylase inhibitor, could enhance neuronal differentiation and recover defective cholesterol metabolism in neural stem cells (NSCs) from NPC1-deficient mice (NPC1(-/-)). VPA could induce neuronal differentiation and restore impaired astrocytes in NSCs from NPC1(-/-) mice. Importantly, an increasing level of cholesterol within NSCs from NPC1(-/-) mice could be reduced by VPA. Moreover, essential neurotrophic genes (TrkB, BDNF, MnSoD, and NeuroD) were up-regulated through the repression of the REST/NRSF and HDAC complex by the VPA treatment. Up-regulated neurotrophic genes were able to enhance neural differentiation and cholesterol homeostasis in neural stem cells from NPC1(-/-) mice. In this study, we suggested that, along with cholesterol homeostasis, impaired neuronal differentiation and abnormal morphology of astrocytes could be rescued by the inhibition of HDAC and REST/NRSF activity induced by VPA treatment.

Paradoxical increase in LDL oxidation by endothelial cells from an atherosclerosis-resistant mouse strain

Oxidative modification of LDL accumulated in the subendothelial space is a critical step in atherogenesis. Mouse strains C57BL/6 (B6) and BALB/c differ markedly in atherosclerosis susceptibility. We sought to determine whether variation of endothelial cells in the capacity to oxidize LDL or in response to minimally modified LDL (MM-LDL) constitutes a genetic component in atherosclerosis. LDL oxidation was assessed by measuring thiobarbituric acid-reactive substance (TBARS) production. Responses to MM-LDL were evaluated by examining induction of monocyte chemotactic protein-1, macrophage-colony stimulating factor, and vascular cell adhesion molecule-1. Both strains exhibited comparable endothelial responses to MM-LDL, whereas BALB/c mice had an increased rate of oxidizing LDL compared with B6 mice. To examine whether endothelial nitric oxide synthase (eNOS) contributed to the difference in LDL oxidation, cells were incubated with native LDL in the presence or absence of N(Omega)-nitro-l-arginine methyl ester (l-NAME), a specific NOS inhibitor. Although l-NAME significantly inhibited endothelial cell-mediated LDL oxidation, it failed to abolish the difference between the strains. In contrast, Baicalein, a specific 12/15 lipoxygenase inhibitor, abolished the difference in LDL oxidation. Thus, the paradoxical increase in LDL oxidation by endothelial cells is attributable to higher oxidant activity of 12/15-lipoxygenase in BALB/c mice and endothelial cells appear unlikely to be a source of the resistance to atherosclerosis.

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.

Rosuvastatin restores superoxide dismutase expression and inhibits accumulation of oxidized LDL in the aortic arch of obese dyslipidemic mice

BACKGROUND AND PURPOSE

Our goal was to elucidate mechanisms of the inhibitory effect of rosuvastatin on the accumulation of plaque oxidized low density lipoproteins (oxLDL) and on plaque volume, without lowering cholesterol, in mice with combined leptin and LDL-receptor deficiency (DKO).

EXPERIMENTAL APPROACH

Twelve-week old DKO mice were treated with rosuvastatin (10 mg kg(-1) day(-1), s.c.) or placebo or no treatment for 12 weeks. The effect on blood variables, aortic plaque volume and composition and gene expression in the aorta and in THP-1 cells was assessed.

KEY RESULTS

Rosuvastatin lowered free fatty acids (FFA), triglycerides, and increased insulin sensitivity, without affecting cholesterol. Rosuvastatin lowered the plaque volume, inhibited macrophage, lipid and oxLDL accumulation, and decreased the oxLDL-to-LDL ratio of plaques in the aortic arch. It increased superoxide dismutase 1 (SOD1), CD36, LXR-alpha, ABCA-1 and PPAR-gamma RNA expression in aortic extracts. SOD1 was the strongest inverse correlate of oxLDL. In THP-1 macrophages and foam cells, expression of SOD1 was lower than in THP-1 monocytes. Rosuvastatin restored expression of SOD1 in THP-1 macrophages and foam cells.

CONCLUSIONS AND IMPLICATIONS

Rosuvastatin restored SOD1 expression in THP-1 macrophages and foam cells in vitro and in the aorta of DKO mice. The latter was associated with less oxLDL accumulation within atherosclerotic plaques and inhibition of plaque progression. This effect was obtained at a dose not affecting cholesterol levels but improving insulin sensitivity. SOD1 is a potentially important mediator of the prevention of oxLDL accumulation within atherosclerotic plaques.

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.

Mechanisms of H2O2-Induced Oxidative Stress in Endothelial Cells Exposed to Physiologic Shear Stress

Hydrogen peroxide (H2O2) is produced by inflammatory and vascular cells and induces oxidative stress, which may contribute to vascular disease and endothelial cell dysfunction. In smooth muscle cells, H2O2 induces production of O2 by activating NADPH oxidase. However, the mechanisms whereby H2O2 induces oxidative stress in endothelial cells are not well understood, although O2 may play a role. Recent studies have documented increased O2 in endothelial cells exposed to H2O2 via uncoupled nitric oxide synthase (NOS) and NADPH oxidase under static conditions. To assess responses to H2O2 in porcine aortic endothelial cells (PAEC) under shearing conditions, a constant flow rate of 24. 4 ml/min was applied to produce physiologically relevant shear stress (8. 2 dynes/cm). Here we demonstrate that treatment with 100 muM H2O2 increases intracellular O2 levels in PAEC. In addition, we demonstrate that l-NAME, an inhibitor of NOS, and apocynin, an inhibitor of NADPH oxidase, reduced O2 levels in PAEC treated with H2O2 under physiologic shear suggesting that both NOS and NADPH oxidase contribute to H2O2-induced O2 in PAEC. Co-inhibition of NOS and NADPH oxidase also reduced intracellular O2 levels under shear. We conclude that H2O2-induced oxidative stress in endothelial cells exhibits increased intracellular O2 levels through NOS and NADPH oxidase under shear. The inhibition of NOS and NADPH with H2O2 exposure is nonlinear, suggesting some interdependent or compensating system within endothelial cells. These findings suggest a complex interaction between H2O2 and oxidant-generating enzymes that may contribute to endothelial dysfunction in cardiovascular diseases.

Hypercholesterolemia accelerates vascular calcification induced by excessive vitamin D via oxidative stress

Hypercholesterolemia plays an important role in the initiation and progression of atherosclerosis and has a positive correlation with cardiovascular disease. Calcification is a common feature of atherosclerotic lesions and contributes to cardiovascular dysfunctions. The present study investigated the role of hypercholesterolemia in vascular calcification and its potential mechanism. Models of vascular calcification were established by administering vitamin D2 (VD) to rats alone or combined with a high-cholesterol diet (HCD) and by treating rat aorta smooth muscle cells (RASMCs) with beta-glycerophosphate (GP) alone or combined with oxidized low-density lipoprotein (oxLDL) in vitro. In rats, the combination of VD with HCD significantly enhanced vessel calcium deposition and the activity and mRNA expression of vessel alkaline phosphatase (ALP) compared to treatment with VD alone. This combination also enhanced serum levels of total cholesterol, oxLDL, and malondialdehyde as well as vascular production of superoxide anion, while it reduced the vascular activity of superoxide dismutase. Both simvastatin, a cholesterol-lowering agent, and antioxidant vitamin E antagonized the effects of the above combination. In RASMCs, oxLDL accumulation dependently accelerated calcium deposition in cell layers initiated by GP alone. Also, oxLDL stimulated ALP activity and mRNA expression in RASMCs in a concentration-dependent manner. Taken together, these results suggest that acceleration of vascular calcification by hypercholesterolemia might be attributed to oxidative stress and such calcification may be another target of statin or antioxidant action in antiatherosclerosis.

Overexpression of lysosomal acid lipase and other proteins in atherosclerosis

Atherosclerosis is one of the major causes of morbidity and mortality in the western world. The existing data of elevated expression levels of proteins like DNA damage and DNA repair enzymes in human atherosclerotic plaques are reviewed. From the literature, the effect of overexpression of different proteins using adenoviral vectors or the model of transgenic mice on the development of atherosclerosis will be discussed. Special focus is placed on the lysosomal acid lipase (LAL), because LAL connects extra-cellular with intra-cellular lipid metabolism and is the only hydrolase for cleavage of cholesteryl esters delivered to the lysosomes. Patients with a deficiency of LAL show an accumulation of lipids in the cells and develop pre-mature atherosclerosis. To answer the question of the influence of LAL in atherosclerosis if overexpressed, we show for the first time data of transgenic mice overexpressing LAL and the effect on the lipid level.

Mechanisms of H2O2-induced oxidative stress in endothelial cells

Hydrogen peroxide, produced by inflammatory and vascular cells, induces oxidative stress that may contribute to endothelial dysfunction. In smooth muscle cells, H(2)O(2) induces production of O(2)*(-) by activating NADPH oxidase. However, the mechanisms whereby H(2)O(2) induces oxidative stress in endothelial cells are poorly understood. We examined the effects of H(2)O(2) on O(2)*(-) levels on porcine aortic endothelial cells (PAEC). Treatment with 60 micromol/L H(2)O(2) markedly increased intracellular O(2)*(-) levels (determined by conversion of dihydroethidium to hydroxyethidium) and produced cytotoxicity (determined by propidium iodide staining) in PAEC. Overexpression of human manganese superoxide dismutase in PAEC reduced O(2)*(-) levels and attenuated cytotoxicity resulting from treatment with H(2)O(2). L-NAME, an inhibitor of nitric oxide synthase (NOS), and apocynin, an inhibitor of NADPH oxidase, reduced O(2)*(-) levels in PAEC treated with H(2)O(2), suggesting that both NOS and NADPH oxidase contribute to H(2)O(2)-induced O(2)*(-) in PAEC. Inhibition of NADPH oxidase using apocynin and NOS rescue with L-sepiapterin together reduced O(2)*(-) levels in PAEC treated with H(2)O(2) to control levels. This suggests interaction-distinct NOS and NADPH oxidase pathways to superoxide. We conclude that H(2)O(2) produces oxidative stress in endothelial cells by increasing intracellular O(2)*(-) levels through NOS and NADPH oxidase. These findings suggest a complex interaction between H(2)O(2) and oxidant-generating enzymes that may contribute to endothelial dysfunction.

Crocetin Attenuates Atherosclerosis in Hyperlipidemic Rabbits Through Inhibition of LDL Oxidation

Oxidation of low-density lipoprotein plays a crucial role in the pathogenesis of atherosclerosis, raising the possibility of using antioxidants as an inhibitor of atherosclerosis. However, studies with antioxidants have led to contradictory results. In the present study, we investigated the effect of crocetin, a carotenoid with potent antioxidant activity, on experimental atherosclerosis in rabbits. After 8 weeks of feeding on high lipid diet, rabbits developed severe atherosclerotic lesions in thoracic aortas (P < 0.01), together with a significant elevation of plasma lipids level, thiobarbituric acid reactive substances (TBARS), and oxidized low-density lipoprotein (P < 0.01). In contrast, supplementation with crocetin markedly reduced the progression of atherosclerotic lesions (P < 0.01) and plasma levels of Ox-LDL and TBARS, whereas plasma lipids level remained unchanged. Plasma total antioxidant capacity and superoxide dismutase activity were obviously increased in crocetin-treated rabbits. In vitro studies demonstrated that supplementation with crocetin significantly increased the resistance of LDL to cupric ion-induced oxidation. Regression analysis indicated that atherosclerotic areas correlated positively with plasma level of Ox-LDL and the susceptibility of LDL to in vitro oxidation. These findings suggest that suppression of LDL oxidation by crocetin contributes, at least partly, to the attenuation of atherosclerosis.

Contribution of an imbalance between oxidant—antioxidant systems to plaque vulnerability in patients with carotid artery stenosis

OBJECT

Reactive species of oxygen and nitrogen mediate the oxidative modification of low-density lipoprotein (LDL). Oxidation of LDL is inhibited by endogenous radical scavenging enzymes such as manganese superoxide dismutase (SOD) and Cu-ZnSOD that catalyze dismutation of oxygen to H2O2. Low-molecular antioxidants such as uric acid regulate the inactivation that appears to be linked to an increase in peroxynitrite resulting in oxidized LDL (OxLDL) elevation. The authors evaluated whether a focal imbalance between pro- and antioxidant systems induces plaque vulnerability in patients with carotid artery (CA) stenosis.

METHODS

Carotid artery plaques obtained in 35 patients who had undergone carotid endarterectomy were classified as vulnerable or stable based on histopathological findings. In vulnerable plaques, OxLDL, measured using enzyme-linked immunosorbent assay, was significantly higher (p < 0.01) and SOD activity significantly lower than in stable plaques (p < 0.05). The plaque and plasma OxLDL levels were inversely correlated with plaque SOD activity (p < 0.01). The physiological uric acid level in all plaques was one fourth to one eighth of that in plasma and appeared to be unable to protect Cu-ZnSOD from degradation by H2O2. Immunohistochemical analysis showed increased peroxynitrite and OxLDL in vulnerable plaques. There was a significant correlation between plaque and plasma OxLDL levels (p < 0.01).

CONCLUSIONS

Analysis of the results suggests that a focal imbalance between pro- and antioxidant defense systems in patients with CA plaques induces an increase in plaque OxLDL levels and consequent plaque instability, contributing to high levels of plasma OxLDL.

Local resistance to oxidative stress by overexpression of copper-zinc superoxide dismutase limits neointimal formation after angioplasty

PURPOSE

To examine the effects of oxidative stress on neointimal hyperplasia through local overexpression of human copper-zinc superoxide dismutase (Cu-Zn SOD).

METHODS

The left common femoral arteries (CFA) of 18 New Zealand white rabbits were subjected to balloon overdilation injury. Each dilated CFA was then incubated with either a nonviral (buffer) or viral (adenovirus overexpressing beta-galactosidase) control or an adenovirus overexpressing Cu-Zn SOD. Animals were then sacrificed at 3, 7, or 28 days (3 arteries per group per time point) and the treated CFA segments were harvested for analysis of esterase-positive inflammatory cells and extracellular matrix elements. The intima-to-media ratio (I/M) was measured to assess the degree of neointimal formation.

RESULTS

At 3 days, local SOD levels in the Cu-Zn SOD-treated group were significantly elevated relative to both controls (p<0.01). Significant reductions in lipid peroxidation byproducts were also seen in the SOD group relative to viral and nonviral controls (p<0.05). Mean I/M at 28 days was 0.582+/-0.088 for the nonviral control group versus 0.565+/-0.133 for the viral control group. The SOD-treated group had a significant reduction relative to both controls: 0.259+/-0.045 (p<0.05). Statistically significant reductions in I/M were also demonstrated in the SOD group relative to control groups at 7 days (p<0.05). The SOD-treated group demonstrated significant preservation of elastin relative to controls, as well as a significant reduction in esterase-positive granulocytes relative to controls (p<0.05).

CONCLUSIONS

Direct buffering of oxidative stress in balloon-injured vessels can significantly alter postinjury response and limit neointimal hyperplasia.

Adiponectin suppresses proliferation and superoxide generation and enhances eNOS activity in endothelial cells treated with oxidized LDL

Adiponectin (also known as 30-kDa adipocyte complement-related protein or Acrp30) is an abundant adipocyte-derived plasma protein with anti-atherosclerotic and insulin-sensitizing properties. In order to investigate the potential mechanism(s) of the vascular protective effect of adiponectin, we used cultured bovine endothelial cells (BAECs) to study the effect of recombinant globular adiponectin (gAd) on cellular proliferation and the generation of reactive oxygen species (ROS) induced by oxidized LDL (oxLDL). By RT-PCR, we found that BAECs preferentially express AdipoR1, the high-affinity receptor for gAd. Treatment of BAECs with oxLDL (10 microg/ml) for 16h stimulated cell proliferation by approximately 60%, which was inhibited by co-incubation with gAd. Cell treatment with gAd also inhibited basal and oxLDL-induced superoxide release, and suppressed the activation of p42/p44 MAP kinase by oxLDL. The effects of gAd were blocked by a specific polyclonal anti-adiponectin antibody (TJ414). OxLDL-induced BAEC proliferation and superoxide release were inhibited by the NAD(P)H oxidase inhibitor diphenyleneiodonium (DPI), but not the eNOS inhibitor l-nitroarginine methyl ester (l-NAME). Finally, gAd ameliorated the suppression of eNOS activity by oxLDL. These data indicate that gAd inhibits oxLDL-induced cell proliferation and suppresses cellular superoxide generation, possibly through an NAD(P)H oxidase-linked mechanism.

Antioxidant Gene Therapy Can Protect Hearing and Hair Cells from Ototoxicity

Aminoglycosides are commonly used antibiotics that often induce ototoxicity leading to permanent hair cell loss and hearing impairment. The ototoxic effects of aminoglycosides have been linked to oxidative stress. To determine the feasibility of antioxidant gene therapy for protecting the inner ear against aminoglycoside-induced oxidative stress, we used adenoviral vectors for overexpression of catalase, Cu/Zn superoxide dismutase (SOD1), and Mn superoxide dismutase (SOD2). We inoculated adenoviruses designated Ad.cat, Ad.SOD1, and Ad.SOD2 into the left guinea pig cochlea. Five days later, an ototoxic combination of kanamycin and ethacrynic acid was systemically administered. Artificial perilymph and adenovirus without a gene cassette (Ad.null) were used as controls. Biochemical analysis showed significant increase in catalase and a moderate elevation in SOD2 levels in tissues of the cochlea inoculated with the respective vectors. Auditory brain-stem responses were measured to monitor hearing thresholds. Animals were sacrificed 7 days after the ototoxic insult and their hair cells counted. Hair cells and hearing thresholds were significantly protected by Ad.cat and Ad.SOD2, while results with Ad.SOD1 were inconsistent. Control ears showed no significant protective effects. The results demonstrate that the expression of functional enzymes in the inner ear is feasible using adenoviral-mediated gene delivery. Furthermore, they confirm that reactive oxygen species contribute to aminoglycoside ototoxicity and suggest antioxidant gene therapy as a potential therapeutic strategy to reduce inner ear oxidative stress.

The signal sequence polymorphism of the MnSOD gene is associated with the degree of carotid atherosclerosis

Redox-state of the cells of vascular walls is an important determinant of atherosclerosis. Manganese superoxide dismutase (MnSOD) is an essential anti-oxidant enzyme working in mitochondria of mammalian cells. A potentially functional amino acid polymorphism (Ala16Val) has been described in the signal sequence of the enzyme. The aim of the current study was to test whether the signal sequence polymorphism of the MnSOD would be associated with the degree of carotid atherosclerosis. The polymorphism was genotyped in a sample of 989 middle-aged hypertensive and control subjects. Carotid atherosclerosis was quantified as intima-media thickness (IMT) by ultrasound. The signal sequence polymorphism was found to be a minor determinant of carotid IMT explaining 1.3% of the overall variation, the Val allele associated with the higher IMT. In women, a significant interaction with plasma levels of low-density lipoprotein (LDL) cholesterol was detected, since LDL cholesterol levels were positively correlated with carotid IMT only in the carriers of the Val allele and the Val allele was associated with higher IMT only in the subjects with highest plasma levels of LDL cholesterol. In conclusion, the signal sequence polymorphism of the MnSOD gene is a minor determinant of carotid IMT pointing out the importance of redox-balance in the atherogenesis.

Zinc and copper status in children with high family risk of premature cardiovascular disease

BACKGROUND

Zinc and copper are beneficial to health, growth and development, and also for the prevention of cardiovascular disease (CVD) with regards to improved dietary habits as a preliminary step in CVD prevention. This study was conducted among 2-18-year-old children with high family risk of premature CVD in comparison to controls.

SUBJECTS AND METHODS

One hundred randomly selected children whose parents had premature myocardial infarction were included in the study. The controls were 100 individuals randomly selected from the case group's neighbors and matched for age, sex, and socioeconomic status. A four-day food record questionnaire was used to assess zinc and copper intakes, and their serum levels were determined using Flame-Atomic Absorption Spectrophotometry. The data were analyzed by SPSS/Windows V6 software, using the Student's t and Mantel-Hanzel tests. Significance of differences was considered at P<0.05.

RESULTS

The daily zinc intake was significantly lower in the case than control group (6.89+/-2.97 vs. 8.30+/-2.45 mg, P=0.047). The mean serum zinc level was not significantly different between both groups (82.12+/-14.1 vs. 92.26+/-23.7 microg/dL, P>0.05). Zinc deficiency was more prevalent among the case in boys than their controls (58% vs. 18%, P=0.04). This difference was not significantly in girls (44% vs. 40%). The daily intake and serum level of copper were not significantly different between the case and control groups. No case of copper deficiency was found. The mean systolic blood pressure was not significantly different between the zinc-deficient and zinc-sufficient subjects. Although the mean diastolic blood pressure of the former was higher than the latter, there was no statistically significant difference. About 23.7% of all studied sample had mild-to-moderate degrees of failure to thrive, with significantly lower daily intake and serum zinc level than other subjects (5.14+/-1.06 mg, 82.09+/-12.74 microg/dL vs. 6.89+/-2.14 mg, 99.25+/-27.15 microg/dL, respectively, P<0.05).

CONCLUSION

It is recommended that emphasis be placed on the consumption of food rich in zinc by children, especially those with high family risk of premature CVD.

Relationship between physical activity and oxidative stress biomarkers in women

PURPOSE

To examine the relationship between physical activity and levels of plasma lipid peroxides, superoxide dismutase in erythrocytes (SOD), and glutathione peroxidase (GSH-Px) in whole blood activities.

METHODS

Cross-sectional study in 488 Spanish women. Two categories of leisure time physical activity were defined according to their intensity: low (<or=6 METs) and high (>6 METs). Energy expenditure in household activities was also recorded. Multivariate linear regression analyses were used to adjust for the effect of physical activity on lipid peroxides and SOD and GSH-Px for confounding variables.

RESULTS

The amount of leisure time physical activity was associated with high activity levels of SOD (P = 0.022) and GSH-Px (P = 0.002). Similar results were obtained when physical activity in household activities was added to total leisure physical activity. Physical activity of low intensity was associated with high SOD activity levels (P = 0.002) and that of high intensity with high GSH-Px activity levels (P = 0.001).

CONCLUSION

The amount and intensity of leisure physical activity were directly related to both antioxidant enzyme activity levels. The findings of this study suggest a modulatory effect of leisure physical activity intensity on antioxidative balance in the studied female population.

Adenovirus-mediated overexpression of extracellular superoxide dismutase improves endothelial dysfunction in a rat model of hypertension

Gene transfer may be appropriate for therapeutic protocols targeted at the vascular endothelium. Endothelial dysfunction is the principal phenotype associated with atherosclerosis and hypertension. Oxidative stress has been implicated in the development of endothelial dysfunction. We have explored the ability of overexpressing anti-oxidant genes (superoxide dismutases; SODs) in vitro and in vivo to assess their potential for reversing endothelial dysfunction in a rat model, the stroke-prone spontaneously hypertensive rat (SHRSP). Western blotting and immunofluorescence assays in vitro showed efficient overexpression of MnSOD and ECSOD with respect to localisation to the mitochondria and extracellular surface, respectively. Transgene functional activity was quantified with SOD activity assays. MnSOD and ECSOD overexpression in intact SHRSP vessels in vivo led to endothelial and adventitial overexpression. Pharmacological assessment of transduced vessels following in vivo delivery by basal NO availability quantification demonstrated that the "null" adenovirus and MnSOD adenovirus did not significantly increase NO availability. However, AdECSOD-treated carotid arteries showed a significant increase in NO availability (1.91 +/- 0.04 versus 0.75 +/- 0.08 g/g, n = 6, P = 0.029). In summary, efficient overexpression of ECSOD, but not MnSOD in vivo, results in improved endothelial function in a rat model of hypertension and has important implications for the development of endothelial-based vascular gene therapy.

Inhibitory effects of rosa roxburghii tratt juice on in vitro oxidative modification of low density lipoprotein and on the macrophage growth and cellular cholesteryl ester accumulation induced by oxidized low density lipoprotein

BACKGROUND

Rosa roxburghii tratt juice (RRTJ) administration has been shown to significantly ameliorate atherosclerotic diseases in cholesterol-fed animals. However, the mechanism for the antiatherogenic effect of RRTJ is not clear.

METHODS

We investigated the effects of RRTJ on in vitro oxidative modification of LDL and on LDL-induced macrophage growth and cellular cholesteryl ester (CE) accumulation. The effects of RRTJ on LDL oxidative modification were assessed by relative electrophoretic migration, thiobarbituric acid-reactive substance (TBARS) content, and the formation of conjugated dienes. The inhibition of RRTJ on oxidized LDL (Ox-LDL)-induced murine peritoneal macrophage growth was evaluated by a cell-counting assay and an MTT assay. The effect of RRTJ on Ox-LDL-induced cellular CE accumulation was examined after macrophages were incubated with Ox-LDL in the presence of RRTJ. To clarify the mechanism of the inhibitory effect of RRTJ on Ox-LDL-induced CE accumulation in macrophages, its capacity for cholesterol efflux from macrophage-derived foam cells were examined.

RESULTS

We showed that RRTJ significantly reduced LDL oxidative susceptibility. In addition, RRTJ effectively suppressed Ox-LDL-induced macrophage growth and especially Ox-LDL-induced CE accumulation in murine peritoneal macrophages by promoting cellular cholesterol efflux.

CONCLUSION

These results indicated that RRTJ exerted its antiatherogenic effects largely due to its ability to inhibit the oxidative modification of LDL and to suppress the formation of foam cells.

The role of vitamin E in atherogenesis: linking the chemical, biological and clinical aspects of the disease

Atherosclerosis is a disease involving both oxidative modifications and disbalance of the immune system. Vitamin E, an endogenous redox-active component of circulating lipoproteins and (sub)cellular membranes whose levels can be manipulated by supplementation, has been shown to play a role in the initiation and progression of the disease. Recent data reveal that the activities of vitamin E go beyond its redox function. Moreover, it has been shown that vitamin E can exacerbate certain processes associated with atherogenesis. In this essay we review the role of biology of atherosclerosis, and suggest that these two facets decide the clinical manifestation and outcome of the disease.

Gene transfer of manganese superoxide dismutase reverses vascular dysfunction in the absence but not in the presence of atherosclerotic plaque

Impaired endothelium-dependent vasorelaxation (EDVR) is observed in hypercholesterolemia both in the presence and absence of morphological abnormalities and may be due to superoxide anions. Our aim was to assess the effect of gene transfer of manganese superoxide dismutase (MnSOD) to blood vessels from hypercholesterolemic animals with and without atherosclerotic plaque and to compare the effects of endothelial nitric oxide synthase (eNOS) and MnSOD over-expression on vascular dysfunction in the setting of atherosclerosis. Rabbits received a high-cholesterol diet for 10 weeks, resulting in abnormal EDVR in the absence of plaque in the carotids and the presence of plaque in the aorta. In Group 1, adenoviral vectors encoding MnSOD (AdMnSOD) or beta-galactosidase (Ad(beta)gal) were delivered to the carotid arteries in vivo. Four days later, transgene expression and vascular reactivity were assessed. In Group 2, segments of the aorta were transduced ex vivo with AdMnSOD, AdeNOS or both. Transgene expression and vascular reactivity were assessed 24 hr later. In Group 1, MnSOD expression was detected in AdMnSOD-ransduced vessels and impaired EDVR was reversed in the absence of atherosclerotic plaque. In Group 2 (with atherosclerotic plaque present), MnSOD and eNOS expression were detected by western analysis, and eNOS, but not MnSOD over-expression, improved EDVR whereas simultaneous over-expression of eNOS and MnSOD was no better than eNOS alone. Adenovirus-mediated gene transfer of MnSOD to nonatherosclerotic carotid arteries, but not atherosclerotic aorta, normalizes EDVR. eNOS gene transfer improves EDVR, even in the presence of plaque.