In vivo markers of oxidative stress and therapeutic interventions

Oxidized phospholipids and lipoprotein(a): An update

Over the past few years, there has been an undiminished interest in lipoprotein(a) [Lp(a)] and oxidized phospholipids (OxPLs), mainly carried on this lipoprotein. Elevated Lp(a) has been established as an independent causal risk factor for cardiovascular disease. OxPLs play an important role in atherosclerosis. The main questions that remain to be answered, however, is to what extent OxPLs contribute to the atherogenicity of Lp(a), what effect hypolipidaemic medications may have on their levels and the potential clinical benefit of their reduction. This narrative review aimed to summarize currently available data on OxPLs and cardiovascular risk, as well as the effect of established and emerging hypolipidaemic medications on Lp(a)-OxPLs.

Metabolomics to Diagnose Oxidative Stress in Perinatal Asphyxia: Towards a Non-Invasive Approach

There is a need for feasible and non-invasive diagnostics in perinatal asphyxia. Metabolomics is the study of small molecular weight products of cellular metabolism that may, directly and indirectly, reflect the level of oxidative stress. Saliva analysis is a novel approach that has a yet unexplored potential in metabolomics in perinatal asphyxia. The aim of this review was to give an overview of metabolomics studies of oxidative stress in perinatal asphyxia, particularly searching for studies analyzing non-invasively collected biofluids including saliva. We searched the databases PubMed/Medline and included 11 original human and 4 animal studies. In perinatal asphyxia, whole blood, plasma, and urine are the most frequently used biofluids used for metabolomics analyses. Although changes in oxidative stress-related salivary metabolites have been reported in adults, the utility of this approach in perinatal asphyxia has not yet been explored. Human and animal studies indicate that, in addition to antioxidant enzymes, succinate and hypoxanthine, as well acylcarnitines may have discriminatory diagnostic and prognostic properties in perinatal asphyxia. Researchers may utilize the accumulating evidence of discriminatory metabolic patterns in perinatal asphyxia to develop bedside methods to measure oxidative stress metabolites in perinatal asphyxia. Although only supported by indirect evidence, saliva might be a candidate biofluid for such point-of-care diagnostics.

Oxidized LDLs as Signaling Molecules

Levels of oxidized low-density lipoproteins (oxLDLs) are usually low in vivo but can increase whenever the balance between formation and scavenging of free radicals is impaired. Under normal conditions, uptake and degradation represent the physiological cellular response to oxLDL exposure. The uptake of oxLDLs is mediated by cell surface scavenger receptors that may also act as signaling molecules. Under conditions of atherosclerosis, monocytes/macrophages and vascular smooth muscle cells highly exposed to oxLDLs tend to convert to foam cells due to the intracellular accumulation of lipids. Moreover, the atherogenic process is accelerated by the increased expression of the scavenger receptors CD36, SR-BI, LOX-1, and SRA in response to high levels of oxLDL and oxidized lipids. In some respects, the effects of oxLDLs, involving cell proliferation, inflammation, apoptosis, adhesion, migration, senescence, and gene expression, can be seen as an adaptive response to the rise of free radicals in the vascular system. Unlike highly reactive radicals, circulating oxLDLs may signal to cells at more distant sites and possibly trigger a systemic antioxidant defense, thus elevating the role of oxLDLs to that of signaling molecules with physiological relevance.

Lipoprotein(a) the Insurgent: A New Insight into the Structure, Function, Metabolism, Pathogenicity, and Medications Affecting Lipoprotein(a) Molecule

Lipoprotein(a) [Lp(a)], aka "Lp little a", was discovered in the 1960s in the lab of the Norwegian physician Kåre Berg. Since then, we have greatly improved our knowledge of lipids and cardiovascular disease (CVD). Lp(a) is an enigmatic class of lipoprotein that is exclusively formed in the liver and comprises two main components, a single copy of apolipoprotein (apo) B-100 (apo-B100) tethered to a single copy of a protein denoted as apolipoprotein(a) apo(a). Plasma levels of Lp(a) increase soon after birth to a steady concentration within a few months of life. In adults, Lp(a) levels range widely from <2 to 2500 mg/L. Evidence that elevated Lp(a) levels >300 mg/L contribute to CVD is significant. The improvement of isoform-independent assays, together with the insight from epidemiologic studies, meta-analyses, genome-wide association studies, and Mendelian randomization studies, has established Lp(a) as the single most common independent genetically inherited causal risk factor for CVD. This breakthrough elevated Lp(a) from a biomarker of atherosclerotic risk to a target of therapy. With the emergence of promising second-generation antisense therapy, we hope that we can answer the question of whether Lp(a) is ready for prime-time clinic use. In this review, we present an update on the metabolism, pathophysiology, and current/future medical interventions for high levels of Lp(a).

Diabetes and dyslipidaemia are associated with oxidative stress independently of inflammation in long-term antiretroviral-treated HIV-infected patients

AIM

Ageing HIV-infected patients controlled by antiretroviral therapy (ART) frequently present age-related comorbidities, such as cardiovascular (CV) events, diabetes, dyslipidaemia, hypertension and chronic kidney disease (CKD). The prevalence of these comorbidities was evaluated in a cohort of long-term-monitored ART-controlled HIV-infected patients, then followed by a search into whether oxidative stress, like inflammation, might be associated with metabolic parameters and/or comorbidities.

METHODS

Included were 352 long-term ART patients who started with protease inhibitors (PIs) in 1997-1999. They were evaluated at their final visit, 11 years later, for previous CV events, prevalence of diabetes, LDL-related and atherogenic (high TG/HDL) dyslipidaemias, hypertension and CKD. Also measured were circulating biomarkers to explore oxidative stress (Lp-PLA2, oxLDL, oxLDL/LDL ratio, paraoxonase and arylesterase activities), inflammation/immune activation (hsCRP, hsIL-6, D dimer, soluble CD14, β2 microglobulin, cystatin C), adipokines and insulin resistance. Levels were compared in patients with and without each comorbidity or condition using non-parametric correlation tests and multivariate adjusted analyses.

RESULTS

At the final visit, 81.5% of patients were male and were aged (median, IQR) 49 years (45-56); BMI was 23.0 kg/m² (21.1-25.4), CD4+ lymphocytes were 620 cells/mm³ (453-790) and 91.5% had undetectable HIV-1 viral loads. The prevalence of diabetes was 11%, and LDL-related dyslipidaemia 28%, atherogenic dyslipidaemia 9%, hypertension 28%, CKD 9% and previous CV events 9%. Diabetes and atherogenic dyslipidaemia were associated with increased oxidative stress and independently with inflammation. LDL-related dyslipidaemia and impaired fasting glucose were associated with increased oxidative stress. No association of these biomarkers was detected with hypertension, CKD and previous CV events.

CONCLUSION

In long-term-treated HIV-infected patients with frequent comorbid conditions, oxidative stress could be contributing to diabetes and LDL-related and atherogenic dyslipidaemias independently of inflammation.

The Role of Traditional Chinese Medicine in the Regulation of Oxidative Stress in Treating Coronary Heart Disease

Oxidative stress has been closely related with coronary artery disease. In coronary heart disease (CHD), an excess of reactive oxygen species (ROS) production generates endothelial cell and smooth muscle functional disorders, leading to a disequilibrium between the antioxidant capacity and prooxidants. ROS also leads to inflammatory signal activation and mitochondria-mediated apoptosis, which can promote and increase the occurrence and development of CHD. There are several kinds of antioxidative and small molecular systems of antioxidants, such as β-carotene, ascorbic acid, α-tocopherol, and reduced glutathione (GSH). Studies have shown that antioxidant treatment was effective and decreased the risk of CHD, but the effect of the treatment varies greatly. Traditional Chinese medicine (TCM) has been utilized for thousands of years in China and is becoming increasingly popular all over the world, especially for the treatments of cardiovascular diseases. This review will concentrate on the evidence of the action mechanism of TCM in preventing CHD by modulating oxidative stress-related signaling pathways.

Dapsone protects brain microvascular integrity from high-fat diet induced LDL oxidation

Atherosclerosis was considered to induce many vascular-related complications, such as acute myocardial infarction and stroke. Abnormal lipid metabolism and its peroxidation inducing blood–brain barrier (BBB) leakage were associated with the pre-clinical stage of stroke. Dapsone (DDS), an anti-inflammation and anti-oxidation drug, has been found to have protective effects on vascular. However, whether DDS has a protective role on brain microvessels during lipid oxidation had yet to be elucidated. We investigated brain microvascular integrity in a high-fat diet (HFD) mouse model. We designed this study to explore whether DDS had protective effects on brain microvessels under lipid oxidation and tried to explain the underlying mechanism. In our live optical study, we found that DDS significantly attenuated brain microvascular leakage through reducing serum oxidized low-density lipoprotein (oxLDL) in HFD mice (p < 0.001), and DDS significantly inhibited LDL oxidation in vitro (p < 0.001). Our study showed that DDS protected tight junction proteins: ZO-1 (p < 0.001), occludin (p < 0.01), claudin-5 (p < 0.05) of microvascular endothelial cells in vivo and in vitro. DDS reversed LAMP1 aggregation in cytoplasm, and decreased the destruction of tight junction protein: ZO-1 in vitro. We first revealed that DDS had a protective role on cerebral microvessels through preventing tight junction ZO-1 from abnormal degradation by autophagy and reducing lysosome accumulation. Our findings suggested the significance of DDS in protecting brain microvessels under lipid metabolic disorders, which revealed a novel potential therapeutic strategy in brain microvascular-related diseases.

Mass spectrometry-based methods for identifying oxidized proteins in disease: advances and challenges

Many inflammatory diseases have an oxidative aetiology, which leads to oxidative damage to biomolecules, including proteins. It is now increasingly recognized that oxidative post-translational modifications (oxPTMs) of proteins affect cell signalling and behaviour, and can contribute to pathology. Moreover, oxidized proteins have potential as biomarkers for inflammatory diseases. Although many assays for generic protein oxidation and breakdown products of protein oxidation are available, only advanced tandem mass spectrometry approaches have the power to localize specific oxPTMs in identified proteins. While much work has been carried out using untargeted or discovery mass spectrometry approaches, identification of oxPTMs in disease has benefitted from the development of sophisticated targeted or semi-targeted scanning routines, combined with chemical labeling and enrichment approaches. Nevertheless, many potential pitfalls exist which can result in incorrect identifications. This review explains the limitations, advantages and challenges of all of these approaches to detecting oxidatively modified proteins, and provides an update on recent literature in which they have been used to detect and quantify protein oxidation in disease.

Antioxidants and coronary artery disease: from pathophysiology to preventive therapy

Oxidant stress in the cardiovascular system may occur when antioxidant capacity is insufficient to reduce reactive oxygen species and other free radicals. Oxidant stress has been linked to the pathogenesis of atherosclerosis and incident coronary artery disease. As a result of this connection, early observational studies focused on dietary antioxidants, such as β-carotene, α-tocopherol, and ascorbic acid, and demonstrated an inverse relationship between intake of these antioxidants and major adverse cardiovascular events. These findings supported a number of randomized trials on the use of selected antioxidants as primary or secondary prevention strategies to decrease cardiac risk; however, many of these studies reported disappointing results with little or no observed risk reduction in antioxidant-treated patients. Several plausible explanations for these findings have been suggested, including incorrect antioxidant choice or dose, synthetic versus dietary antioxidants as the intervention, and patient selection, all of which will be important to consider when designing future clinical trials. This review will focus on the contemporary evidence that is the basis for our current understanding of the role of antioxidants in cardiovascular disease prevention.

Acrolein modification impairs key functional features of rat apolipoprotein E: identification of modified sites by mass spectrometry

Apolipoprotein E (apoE), an antiatherogenic apolipoprotein, plays a significant role in the metabolism of lipoproteins. It lowers plasma lipid levels by acting as a ligand for the low-density lipoprotein receptor (LDLr) family of proteins, in addition to playing a role in promoting macrophage cholesterol efflux in atherosclerotic lesions. The objective of this study is to examine the effect of acrolein modification on the structure and function of rat apoE and to determine the sites and nature of modification by mass spectrometry. Acrolein is a highly reactive aldehyde, which is generated endogenously as one of the products of lipid peroxidation and is present in the environment in pollutants such as tobacco smoke and heated oils. In initial studies, acrolein-modified apoE was identified by immunoprecipitation using an acrolein-lysine specific antibody in the plasma of 10-week old male rats that were exposed to filtered air (FA) or low doses of environmental tobacco smoke (ETS). While both groups displayed acrolein-modified apoE in the lipoprotein fraction, the ETS group had higher levels in the lipid-free fraction compared with the FA group. This observation provided the rationale to further investigate the effect of acrolein modification on rat apoE at a molecular level. Treatment of recombinant rat apoE with a 10-fold molar excess of acrolein resulted in (i) a significant decrease in lipid-binding and cholesterol efflux abilities, (ii) impairment in the LDLr- and heparin-binding capabilities, and (iii) significant alterations in the overall stability of the protein. The disruption in the functional abilities is attributed directly or indirectly to acrolein modification yielding an aldimine adduct at K149 and K155 (+38); a propanal adduct at K135 and K138 (+56); an N(ε)-(3-methylpyridinium)lysine (MP-lysine) at K64, K67, and K254 (+76), and an N(ε)-(3-formyl-3,4-dehydropiperidino)lysine (FDP-lysine) derivative at position K68 (+94), as determined by matrix-assisted laser desorption/ionization-time of flight/time of flight mass spectrometry (MALDI-TOF/TOF MS). The loss of function may also be attributed to alterations in the overall fold of the protein as noted by changes in the guanidine HCl-induced unfolding pattern and to protein cross-linking. Overall, disruption of the structural and functional integrity of apoE by oxidative modification of essential lysine residues by acrolein is expected to affect its role in maintaining plasma cholesterol homeostasis and lead to dysregulation in lipid metabolism.

Provision of antioxidant therapy in hemodialysis (PATH): a randomized clinical trial

Increased markers of oxidative stress and acute-phase inflammation are prevalent in patients undergoing maintenance hemodialysis therapy (MHD), and are associated with increased mortality and hospitalization rates and decreased erythropoietin responsiveness. No adequately powered studies have examined the efficacy of antioxidant therapies on markers of inflammation and oxidative stress. We tested the hypothesis that oral antioxidant therapy over 6 months would decrease selected biomarkers of acute-phase inflammation and oxidative stress and improve erythropoietic response in prevalent MHD patients. In total, 353 patients were enrolled in a prospective, placebo-controlled, double-blind clinical trial and randomly assigned to receive a combination of mixed tocopherols (666 IU/d) plus α-lipoic acid (ALA; 600 mg/d) or matching placebos for 6 months (NCT00237718); 238 patients completed the study. High-sensitivity C-reactive protein (hsCRP) and IL-6 concentration were measured as biomarkers of systemic inflammation, and F2 isoprostanes and isofurans were measured as biomarkers of oxidative stress. The groups did not significantly differ at baseline. At 3 and 6 months, the treatment had no significant effect on plasma hsCRP, IL-6, F2 isoprostane, or isofuran concentrations and did not improve the erythropoietic response. No major adverse events were related to the study drug, and both groups had similar mortality and hospitalization rates during the study. In conclusion, the administration of mixed tocopherols and ALA was generally safe and well tolerated, but did not influence biomarkers of inflammation and oxidative stress or the erythropoietic response.

Aged garlic extract with supplement is associated with increase in brown adipose, decrease in white adipose tissue and predict lack of progression in coronary atherosclerosis

BACKGROUND

Aged garlic extract with supplement (AGE-S) significantly reduces coronary artery calcium (CAC). We evaluated the effects of AGE-S on change in white (wEAT) and brown (bEAT) epicardial adipose tissue, homocysteine and CAC.

METHODS

Sixty subjects, randomized to a daily capsule of placebo vs. AGE-S inclusive of aged garlic-extract (250 mg) plus vitamin-B12 (100 μg), folic-acid (300 μg), vitamin-B6 (12.5mg) and L-arginine (100mg) underwent CAC, wEAT and bEAT measurements at baseline and 12 months. The postcuff deflation temperature-rebound index of vascular function was assessed using a reactive-hyperemia procedure. Vascular dysfunction was defined according to the tertiles of temperature-rebound at 1 year of follow-up. CAC progression was defined as an annual-increase in CAC>15%.

RESULTS

From baseline to 12 months, there was a strong correlation between increase in wEAT and CAC (r(2)=0.54, p=0.0001). At 1 year, the risks of CAC progression and increased wEAT and homocysteine were significantly lower in AGE-S to placebo (p<0.05). Similarly, bEAT and temperature-rebound were significantly higher in AGE-S as compared to placebo (p<0.05). Strong association between increase in temperature-rebound and bEAT/wEAT ratio (r(2)=0.80, p=0.001) was noted, which was more robust in AGE-S. Maximum beneficial effect of AGE-S was noted with increase in bEAT/wEAT ratio, temperature-rebound, and lack of progression of homocysteine and CAC.

CONCLUSIONS

AGE-S is associated with increase in bEAT/wEAT ratio, reduction of homocysteine and lack of progression of CAC. Increases in bEAT/wEAT ratio correlated strongly with increases in vascular function measured by temperature-rebound and predicted a lack of CAC progression and plaque stabilization in response to AGE-S.

Development of a fast and simple LC-MS/MS method for measuring the F2-isoprostanes in newborns

BACKGROUND

Quantification of F(2)-IsoPs isomer has been regarded as the "gold standard" to assess oxidative stress status in various adult and neonatal human diseases. These methods require high amounts of plasma.

OBJECTIVE

To develop a fast and simple LC-MS/MS method for measuring F(2)-isoprostanes in newborns.

METHODS

A sample of heel blood (0.4 mL) was collected in a tube containing EDTA was collected from 20 term healthy newborns. For measurements, the tandem mass spectrometer has been run in multiple reaction monitoring (MRM) with the electrospray source operating in negative ion mode, and by exploiting the transitions m/z 353.3 > 193.2 for F2-IsoPs and 357.3 > 197.2 for the internal standard d4-8-iso PGF2α.

RESULTS

The concentration of F(2)-IsoPs (in pg/mL) in the collected cord bloods was 60.50 ± 25.04 (mean ± S.D.). No statistical difference was found between male (57.09 ± 19.69) and female (64.67 ± 31.13) concentrations. The overall efficiency of the extraction has been over 80%, while the recovery on spiked samples has been around 94% for spikes of 100 pg/mL with a C.V. of 7.7%.

CONCLUSIONS

We developed a suitable method for large-scale studies with a reduced sample requirement as it is mandatory in neonatal age. Small samples and quick answers are very useful in Neonatology allowing early diagnosis and preventive treatments' strategies of free radical related diseases of the newborn.

Consequences of oxidative stress in age-related macular degeneration

The retina resides in an environment that is primed for the generation of reactive oxygen species (ROS) and resultant oxidative damage. The retina is one of the highest oxygen-consuming tissues in the human body. The highest oxygen levels are found in the choroid, but this falls dramatically across the outermost retina, creating a large gradient of oxygen towards the retina and inner segments of the photoreceptors which contain high levels of polyunsaturated fatty acids. This micro-environment together with abundant photosensitizers, visible light exposure and a high energy demand supports a highly oxidative milieu. However, oxidative damage is normally minimized by the presence of a range of antioxidant and efficient repair systems. Unfortunately, as we age oxidative damage increases, antioxidant capacity decreases and the efficiency of reparative systems become impaired. The result is retinal dysfunction and cell loss leading to visual impairment. It appears that these age-related oxidative changes are a hallmark of early age-related macular degeneration (AMD) which, in combination with hereditary susceptibility and other retinal modifiers, can progress to the pathology and visual morbidity associated with advanced AMD. This review reassesses the consequences of oxidative stress in AMD and strategies for preventing or reversing oxidative damage in retinal tissues.

Methods for evaluating endothelial function: a position statement from the European Society of Cardiology Working Group on Peripheral Circulation

The endothelium holds a pivotal role in cardiovascular health and disease. Assessment of its function was until recently limited to experimental designs due to its location. The advent of novel techniques has facilitated testing on a more detailed basis, with focus on distinct pathways. This review presents available in-vivo and ex-vivo methods for evaluating endothelial function with special focus on more recent ones. The diagnostic modalities covered include assessment of epicardial and microvascular coronary endothelial function, local vasodilation by venous occlusion plethysmography and flow-mediated dilatation, arterial pulse wave analysis and pulse amplitude tonometry, microvascular blood flow by laser Doppler flowmetry, biochemical markers and bioassays, measurement of endothelial-derived microparticles and progenitor cells, and glycocalyx measurements. Insights and practical information on the theoretical basis, methodological aspects, and clinical application in various disease states are discussed. The ability of these methods to detect endothelial dysfunction before overt cardiovascular disease manifests make them attractive clinical tools for prevention and rehabilitation.

N-acetylcysteine prevents pulmonary edema and acute kidney injury in rats with sepsis submitted to mechanical ventilation

Sepsis is a common cause of acute kidney injury (AKI) and acute lung injury. Oxidative stress plays as important role in such injury. The aim of this study was to evaluate the effects that the potent antioxidant N-acetylcysteine (NAC) has on renal and pulmonary function in rats with sepsis. Rats, treated or not with NAC (4.8 g/l in drinking water), underwent cecal ligation and puncture (CLP) 2 days after the initiation of NAC treatment, which was maintained throughout the study. At 24 h post-CLP, renal and pulmonary function were studied in four groups: control, control + NAC, CLP, and CLP + NAC. All animals were submitted to low-tidal-volume mechanical ventilation. We evaluated respiratory mechanics, the sodium cotransporters Na-K-2Cl (NKCC1) and the α-subunit of the epithelial sodium channel (α-ENaC), polymorphonuclear neutrophils, the edema index, oxidative stress (plasma thiobarbituric acid reactive substances and lung tissue 8-isoprostane), and glomerular filtration rate. The CLP rats developed AKI, which was ameliorated in the CLP + NAC rats. Sepsis-induced alterations in respiratory mechanics were also ameliorated by NAC. Edema indexes were lower in the CLP + NAC group, as was the wet-to-dry lung weight ratio. In CLP + NAC rats, α-ENaC expression was upregulated, whereas that of NKCC1 was downregulated, although the difference was not significant. In the CLP + NAC group, oxidative stress was significantly lower and survival rates were significantly higher than in the CLP group. The protective effects of NAC (against kidney and lung injury) are likely attributable to the decrease in oxidative stress, suggesting that NAC can be useful in the treatment of sepsis.

Temporal dissociation between myeloperoxidase (MPO)-modified LDL and MPO elevations during chronic sleep restriction and recovery in healthy young men

OBJECTIVES

Many studies have evaluated the ways in which sleep disturbances may influence inflammation and the possible links of this effect to cardiovascular risk. Our objective was to investigate the effects of chronic sleep restriction and recovery on several blood cardiovascular biomarkers.

METHODS AND RESULTS

Nine healthy male non-smokers, aged 22-29 years, were admitted to the Sleep Laboratory for 11 days and nights under continuous electroencephalogram polysomnography. The study consisted of three baseline nights of 8 hours sleep (from 11 pm to 7 am), five sleep-restricted nights, during which sleep was allowed only between 1 am and 6 am, and three recovery nights of 8 hours sleep (11 pm to 7 am). Myeloperoxidase-modified low-density lipoprotein levels increased during the sleep-restricted period indicating an oxidative stress. A significant increase in the quantity of slow-wave sleep was measured during the first recovery night. After this first recovery night, insulin-like growth factor-1 levels increased and myeloperoxidase concentration peaked.

CONCLUSIONS

We observed for the first time that sleep restriction and the recovery process are associated with differential changes in blood biomarkers of cardiovascular disease.

Mechanistic insights into the therapeutic use of high-dose allopurinol in angina pectoris

OBJECTIVES

The aim of this study was to evaluate the effect of high-dose allopurinol on vascular oxidative stress (OS) and endothelial function in subjects with stable coronary artery disease (CAD).

BACKGROUND

Allopurinol, a xanthine oxidase inhibitor, prolongs the time to chest pain during exercise in angina. We sought to ascertain whether allopurinol also improves endothelial dysfunction in optimally treated CAD patients, because such an effect might be of value to reduce future cardiovascular mortality. The mechanism of the anti-ischemic effect of allopurinol could be related to its reducing xanthine oxidase-induced OS, and our second aim was to see whether allopurinol really does reduce vascular tissue OS in CAD patients.

METHODS

A randomized, double-blind, placebo-controlled, crossover study was conducted in 80 patients with CAD, comparing allopurinol (600 mg/day) with placebo. Endothelial function was assessed by forearm venous occlusion plethysmography, flow-mediated dilation, and pulse wave analysis. Vascular OS was assessed by intra-arterial co-infusion of vitamin C and acetylcholine.

RESULTS

Compared with placebo, allopurinol significantly improved endothelium-dependent vasodilation, by both forearm venous occlusion plethysmography (93 ± 67% vs. 145 ± 106%, p = 0.006) and flow-mediated dilation (4.2 ± 1.8% vs. 5.4 ± 1.7%, p < 0.001). Vascular oxidative stress was completely abolished by allopurinol. Central augmentation index improved significantly with allopurinol (2.6 ± 7.0%, p < 0.001) but not with placebo.

CONCLUSIONS

Our study demonstrates that, in optimally treated CAD patients, high-dose allopurinol profoundly reduces vascular tissue OS and improves 3 different measures of vascular/endothelial dysfunction. The former effect on OS might underpin the anti-ischemic effect of allopurinol in CAD. Both effects (on OS and endothelial dysfunction) increase the likelihood that high-dose allopurinol might reduce future cardiovascular mortality in CAD, over and above existing optimum therapy. (Exploring the therapeutic potential of xanthine oxidase inhibitor allopurinol in angina; ISRCTN15253766).

The differential effect of statins on oxidative stress and endothelial function: atorvastatin versus pravastatin

BACKGROUND

Atherogenic risk in subjects with metabolic syndrome is partly mediated by increased oxidative stress and subsequent endothelial dysfunction. Clinical trials have demonstrated differences in outcomes between subjects receiving lipophilic statins (atorvastatin) compared with hydrophilic statins (pravastatin). However, whether these findings are attributable to differences in the doses administered or to nonlipid-lowering pleiotropic effects of statins on oxidative stress and vascular function remains unknown. We hypothesized that equipotent doses of these two statins will have divergent effects on markers of oxidative stress and endothelial function.

METHODS

Thirty-six subjects with hyperlipidemia and metabolic syndrome and/or diabetes were randomized in a double-blind manner to either pravastatin 80 mg or atorvastatin 10 mg daily. Oxidative stress (dROMs assay that measures lipid hydroperoxides, plasma thiobarbituric acid reactive substances [TBARS], and aminothiol levels) and brachial artery flow-mediated dilation (FMD) were measured at baseline and after 12 weeks of statin therapy.

RESULTS

Statin therapy reduced serum low-density lipoprotein cholesterol levels equally in both groups. Atorvastatin therapy was associated with a significant reduction in TBARS (P = .006) and dROMs levels (P = .02), which was not observed in subjects treated with pravastatin. Endothelial function improved with statin therapy (P = .02), but there was no difference between the statin groups.

CONCLUSION

In hyperlipidemic subjects with metabolic syndrome, atorvastatin is associated with a greater reduction in lipid markers of oxidation compared with pravastatin. Whether these effects are responsible for the outcome differences in trials comparing these agents needs further investigation.

Oxidative stress biomarkers as predictors of cardiovascular disease

Evidence for the role of oxidative stress in the pathogenesis of cardiovascular disease (CVD) is primarily based on experimental and observational human studies. The aim of this review is to examine the observational longitudinal studies that have investigated the relationship between oxidative stress biomarkers and CVD. Fifty-one studies were identified with twenty-six of these measuring oxidized (Ox)-LDL, fifteen assessing myeloperoxidase, seven using lipid peroxidation measures and three quantifying protein oxidation. Results of studies using Ox-LDL have been equivocal with sixteen of the twenty-six studies reporting that this measure is predictive of cardiovascular events. These inconsistent results are not explained by differences in the study populations (primary or secondary CVD) or the type of assay used (auto or monoclonal antibodies). Six of the seven lipid peroxidation, and two of three protein oxidation studies found associations. Twelve of fifteen studies assessing the role of myeloperoxidase reported it to be predictive of CVD. However, issues surrounding the specificity of myeloperoxidase as a marker of oxidative stress and the small number of research groups reporting these results, limit this finding. In summary, the ability of oxidative stress biomarkers to predict CVD has yet to be established. Furthermore, it is important to note that the methods used to assess oxidative stress in these studies are indirect, and the evidence that the various methods actually reflect oxidative stress in vivo is limited.

Intimomedial thickness of the vertebral arteries complex: A new useful parameter for the assessment of atheroclerotic process?

Bacground/Aim. An integral part of Doppler ultrasound examination of cervical blood vessels is determination of intimomedial thicknes (IMT) of the common carotid. The aim of the study was to estimate the relations between IMT of the common carotid and vertebral arteries in order to determine if the value of IMT obtained on the vertebral artery could be applied in clinical practice. Methods. We measured IMT in a randomized, prospective and crosssectional study, performed on 50 persons both sexes (29 men and 21 women), at the age from 18 to 79 years (mean age 52.4 ? 17.63 years). All the persons were healthy, what was confirmed with clinical examination and laboratory analyses. Measurements were perfomed from January 2006 until September 2008. Intimomedial thickness was recorded by twodimensional ultrasonography in B-mode on both common carotid arteries: one value was obtained as average of three successeful measurements (measurements were perform on different places). We measured IMT on the first segment of both vertebral arteries, 1.5 cm proximal from the connection of the first and second segments (we got results of the measurement of IMT on the vertebral arteries in the same way: mean value from the three records). Results. (IMT = 0.782 ? 0.248 mm), obtained from 50 healthy persons, was higher than that measured on the vertabral artery on the first segment (IMT = 0.585 ? 0.134 mm). The values of IMT after measurement on two different places were statistically highly different (t = 7.03, SD = 0.028, p < 0.01). Coefficient of variability of IMT values in carotid circulation (CV = 34.4%) was higher than that in vertebral circulation (22.9%). Values of IMT on vertebral arteries were in statistically significant correlation with those in carotid circulation (r = 0.24 and t- = 2.48; p < 0.02). There were no statistically significant difference between IMT measurement on the right and the left side so they were analysed as the same set Conclusion. Values of IMT on the vertebral arteries are one more undependent parameter of doplersonographic examination of cervical vessels, which significantly correlates with IMT values on common carotid artery. Variability of this parameter is lower, and absolute values lower than the same in the common carotid artery. Therefore, this parameter is probably not so sensitive. On the other hand, lower variability of IMT values on the vertebral artery might be of higher specificity for prediction of atherosclerotic progress by the increased values of this parameter than based on IMT values obtained on the common carotid arteries.

Assessment of antioxidants in foods and biological samples: a short critique

Antioxidants can be defined on a biological basis by their ability to inhibit the oxidation of susceptible biomolecules such as proteins, lipids and DNA. There is observational evidence on an inverse association between dietary antioxidant intake and the development of chronic conditions, although randomized trials have not confirmed these results. The antioxidant potential of a biological material can be evaluated by methods categorized into three groups. The first group includes the determination of the individual antioxidants present in the investigated sample. The second focuses on 'total antioxidant capacity', which is considered a convenient tool for obtaining an overall estimate of the antioxidant potential of the sample. The third group involves the quantification of in vivo markers of oxidative stress, such as the products of protein, lipid and DNA oxidation. Due to differences between the assays, however, current research suggests the application of a combination of such methods for a more informative assessment of the oxidation status of the organism.

Isoprostanes as markers of oxidative stress-induced cell damage in porcine islet cell isolation

INTRODUCTION

Mechanical stress and reagents used during the isolation and purification process as well as digestion time and temperature can alter the success of porcine islet cell (PIC) isolation. This study aimed to characterize the occurrence of isoprostanes during PIC isolation using a modified automated Ricordi method and to evaluate their influence on PIC isolation outcome.

METHODS

Porcine pancreatic tissue was harvested at the local slaughter house, and 10 PIC isolations were performed using a modified automated Ricordi method. As positive controls for tissue damage-associated oxidative stress, six consecutive PIC isolations were performed in the presence of 1 mug lipopolysaccharide (LPS). PIC were purified by density gradient centrifugation using the Lymphoprep density gradient. Isoprostane measurement was performed using enzyme-linked immunosorbent assay.

RESULTS

The final yield of viable and pure PICs in the experimental group was 3479 +/- 542 IEQ/g pancreas, and the LPS group yielded lower cell numbers compared to the experimental group. Isoprostane levels were significantly elevated in the LPS group as compared to the experimental group at all time points during the isolation from the beginning of the digestion process.

DISCUSSION

PIC isolation and purification results significantly differed in the two experimental groups, underlining the negative effects of oxidative stress on PIC viability and purity, which impact negatively on PIC transplantation success.

Mechanisms of LDL oxidation

BACKGROUNDS

Many lines of evidence suggest that oxidized low-density lipoprotein (LDL) is implicated in the pathogenesis of atherosclerotic vascular diseases. This review summarizes a diversity of mechanisms proposed for LDL oxidation serving for the so-called "LDL oxidation hypothesis of atherogenesis".

METHODS AND RESULTS

We investigated the literature and our research results related to mechanisms of LDL oxidation and its atherogenesis. LDL oxidation is catalyzed by transition metal ions and several free radicals, and LDL is also oxidized by some oxidizing enzymes. In this way, LDL can be converted to a form that is recognized specifically by and with high affinity to macrophage scavenger receptors, leading to foam cell formation, the defining characteristic of fatty streak lesions.

CONCLUSIONS

Several pathways are involved in the promotion of LDL oxidation in vitro and in vivo, but it would appear that the physiologically relevant mechanisms of LDL oxidation are still imperfectly understood. The underlying mechanisms of LDL oxidation must be further explored to reveal appropriate ways for the diagnosis and treatment of atherosclerosis and its relevant diseases.

Little change in markers of protein breakdown and oxidative stress in humans in immobilization-induced skeletal muscle atrophy

A number of studies in rodents suggest that disuse atrophy results from a large increase in proteolysis affected by, or accompanying, increased oxidative stress. Little information is available, however, about the effects of immobilization on markers of muscle protein breakdown and oxidative stress in humans. Therefore, the purpose of this investigation was to measure markers of breakdown or oxidative stress in subjects who underwent 14 days of knee-brace-mediated immobilization. Vastus lateralis samples taken from 21 young subjects before, and 2 days and 14 days after, single leg immobilization were measured for ubiquitin-protein conjugates, caspase 3/7 activity, the 14-kDa caspase-3 cleaved actin fragment, 4-hydroxy-2-nonenal (4-HNE) adducts, and protein carbonyls. Quadriceps cross-sectional area decreased by 5.7% +/- 1.1% (p < 0.0001) following immobilization. Ubiquitin-protein conjugates were elevated at 2 days of immobilization (12%, p < 0.05) but were not different from baseline at 14 days. Levels of the 14-kDa actin fragment and caspase 3/7 activity did not change over the immobilization period. The oxidative stress markers, 4-HNE adducts and protein carbonyls, did not change at any time point. These static measures of breakdown and oxidative modification suggest that a small increase in protein ubiquitination occurs early (2 days), but elevations in ubiquitinated or oxidatively modified proteins are not sustained during the later phase (14 days) of uncomplicated disuse atrophy in humans, suggesting that these pathways are not playing a major role in simple disuse-induced atrophic loss of protein mass.

Generation and biological activities of oxidized phospholipids

Glycerophospholipids represent a common class of lipids critically important for integrity of cellular membranes. Oxidation of esterified unsaturated fatty acids dramatically changes biological activities of phospholipids. Apart from impairment of their structural function, oxidation makes oxidized phospholipids (OxPLs) markers of "modified-self" type that are recognized by soluble and cell-associated receptors of innate immunity, including scavenger receptors, natural (germ line-encoded) antibodies, and C-reactive protein, thus directing removal of senescent and apoptotic cells or oxidized lipoproteins. In addition, OxPLs acquire novel biological activities not characteristic of their unoxidized precursors, including the ability to regulate innate and adaptive immune responses. Effects of OxPLs described in vitro and in vivo suggest their potential relevance in different pathologies, including atherosclerosis, acute inflammation, lung injury, and many other conditions. This review summarizes current knowledge on the mechanisms of formation, structures, and biological activities of OxPLs. Furthermore, potential applications of OxPLs as disease biomarkers, as well as experimental therapies targeting OxPLs, are described, providing a broad overview of an emerging class of lipid mediators.

Oxidative stress in renal dysfunction: mechanisms, clinical sequelae and therapeutic options

Oxidative stress has been increasingly linked to the high incidence of cardiovascular events in patients with chronic kidney disease (CKD), especially as traditional cardiovascular risk factors seem to not be able to account for the huge cardiovascular morbidity and mortality in this population group. Oxidative stress is increased in patients with renal impairment as a result of increased oxidant activity and reduced antioxidant capacity, and this is increased in a graded manner with increasing renal dysfunction. Inflammation, which is also present in CKD, further amplifies the oxidant generation process. The two clinical sequelae of oxidative stress are endothelial dysfunction and left ventricular hypertrophy, which have adverse cardiovascular consequences. With our new understanding of oxidative stress, it is now important to assess treatment options that reduce it in the hope that they reverse endothelial dysfunction and left ventricular hypertrophy and the clinical sequelae of these abnormalities.

Relation of oxidative biomarkers, vascular dysfunction, and progression of coronary artery calcium

The relation between oxidative stress and coronary artery calcium (CAC) progression is currently not well described. The present study evaluated the relation among the biomarkers of oxidative stress, vascular dysfunction, and CAC. Sixty asymptomatic subjects participated in a randomized trial evaluating the effect of aged garlic extract plus supplement versus placebo and underwent measurement of CAC. The postcuff deflation temperature-rebound index of vascular function was assessed using a reactive hyperemia procedure. The content of oxidized phospholipids (OxPL) on apolipoprotein B-100 (apoB) particles detected by antibody E06 (OxPL/apoB), lipoprotein(a), IgG and IgM autoantibodies to malondialdehyde-low-density lipoprotein and apoB-immune complexes were measured at baseline and after 12 months of treatment. CAC progression was defined as an annual increase in CAC >15%. Vascular dysfunction was defined according to the tertiles of temperature-rebound at 1 year of follow-up. From baseline to 12 months, a strong inverse correlation was noted between an increase in CAC scores and increases in temperature-rebound (r(2) = -0.90), OxPL/apoB (r(2) = -0.85), and lipoprotein(a) (r(2) = -0.81) levels (p <0.0001 for all). The improvement in temperature-rebound correlated positively with the increases in OxPL/apoB (r(2) = 0.81, p = 0.0008) and lipoprotein(a) (r(2) = 0.79, p = 0.0001) but inversely with autoantibodies to malondialdehyde-low-density lipoprotein and apoB-immune complexes. The greatest CAC progression was noted with the lowest tertiles of increases in temperature-rebound, OxPL/apoB and lipoprotein(a) and the highest tertiles of increases in IgG and IgM malondialdehyde-low-density lipoprotein. In conclusion, the present results have documented a strong relation among markers of oxidative stress, vascular dysfunction, and progression of coronary atherosclerosis. Increases in OxPL/apoB and lipoprotein(a) correlated strongly with increases in vascular function and predicted a lack of progression of CAC.

Quantification of F2-isoprostanes as a reliable index of oxidative stress in vivo using gas chromatography-mass spectrometry (GC-MS) method

Free radical-induced lipid peroxidation has been implicated in a number of human diseases including atherosclerosis, cancer, and neurodegenerative diseases. F(2)-Isoprostanes (IsoPs) are isomers of prostaglandin PGF(2alpha) that are generated in vivo from the free radical-initiated peroxidation of arachidonic acid independent of cyclooxygenase enzymes. Since the discovery of the IsoPs in the early 1990s, a large body of evidence has been accumulated to indicate that quantification of these F(2)-IsoPs represents the most reliable biomarker to assess oxidative stress in vivo. A variety of analytical approaches have been developed for the quantification of these novel compounds; these methods include mass spectrometry (MS) detection coupled to gas chromatography (GC) or liquid chromatography (LC) separation, and detection using immunological approaches. This article summarizes our current methodology to quantify F(2)-IsoPs in biological fluids and tissues using GC-MS. This method includes solid-phase extraction (SPE), thin-layer chromatography (TLC) purification, chemical derivatization, and MS detection using negative ion chemical ionization (NICI) coupled with GC. The protocol described herein has been optimized and validated to provide the best sensitivity and selectivity for quantification of F(2)-IsoPs from a variety of biological sources.

NOX2 inhibition with apocynin worsens stroke outcome in aged rats

This study utilized middle cerebral artery occlusion (MCAO) with tissue plasminogen activator (tPA) to assess inhibition of the NOX2 isoform of NADPH oxidase on brain injury and functional recovery in aged rats. Effects of NOX2 on the degree of brain injury and functional recovery following MCAO and tPA reperfusion was assessed in young adult and aged rats. Rats received apocynin (NOX2 inhibitor; 5 mg/kg) or saline 30 min prior to MCAO. At 24 h following MCAO, blood-brain barrier permeability (BBB), stroke infarct volume, edema formation, and oxidative damage were measured. Apocynin treatment in aged rats increased mortality rate and failed to improve functional outcome, total infarct volume, edema formation, and BBB permeability. Aged rats displayed increased BBB permeability to sucrose in the contralateral hemisphere following MCAO and diminished antioxidant capacity in the brain as compared to young adult rats. We conclude that inhibition of NOX2 in the aged rat exacerbates stroke injury and diminishes functional outcome. These results suggest age is an important factor in stroke damage and more rigorous examination of apocynin as a therapeutic agent for treatment of stroke must be done.

Environmental tobacco smoke and cardiometabolic risk in young children: results from a survey in south-west Germany

AIMS

We explored the association between exposure to environmental tobacco smoke (ETS) and various cardiometabolic biomarkers in 10-year-old children.

METHODS AND RESULTS

A population-based cross-sectional study was carried out. Data on ETS exposure and potential confounders were collected by parental questionnaire. Adiponectin, leptin, markers of inflammation, apolipoproteins (apo) AI and B, and lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) were measured. Linear and logistic regression models were applied using the 90th percentile as a cut-off point except for adiponectin and apoAI (10th percentile). In linear models, ETS exposure was significantly associated with increasing plasma concentrations of leptin, C-reactive protein, fibrinogen, interleukin (IL)-6, and Lp-PLA(2). When compared with none, ETS exposure of more than 10 cigarettes per day was associated with elevated concentrations of leptin (OR 6.40; 95% CI, 2.67-15.39), C-reactive protein (OR 3.17; 95% CI, 1.31-7.68), Lp-PLA(2) (OR 2.97 95% CI, 1.32-6.68), low adiponectin (OR 2.69; 95% CI, 1.10-6.57), and low apoAI (OR 4.48; 95% CI, 2.16-10.85). Increasing dose of ETS exposure was related to an increasing number of abnormal cardiometabolic markers.

CONCLUSION

Among children, ETS exposure was associated with a low-grade inflammatory response and altered markers of lipid metabolism, which may initiate atherosclerosis in early life. However, longitudinal studies are necessary to determine the potential causal relevance of these associations.

A cross-sectional study of intima-media thickness, ethnicity, metabolic syndrome, and cardiovascular risk in 2268 study participants

OBJECTIVE

To describe the association between intima-media thickness (IMT) and metabolic syndrome (MetS) and to examine if the addition of IMT to a traditional MetS definition adds value to the assessment of predicted cardiovascular disease (CVD) risk in a large multiethnic population.

PARTICIPANTS AND METHODS

In this cross-sectional study, carotid IMT was measured in 2268 men and women as part of a wellness physical examination between August 1, 2000, and October 1, 2001. The wellness examination included a fasting lipid panel, physical examination, and medical history. Mean IMT was described by sex, ethnicity, and the MetS. Predicted risk for CVD was determined with IMT as a component of the diagnostic criteria for MetS.

RESULTS

Intima-media thickness increased with each additional component of the MetS, increasing from 0.516 mm for 0 components to 0.688 mm for 4 or more components (P<.001). In each ethnic group (non-Hispanic whites, blacks, Hispanics, and Asians), those with the MetS had higher mean IMT (increased by 0.084 mm to 0.134 mm) than those without MetS. The addition of IMT as a "new" component in the diagnosis of MetS allowed us to identify 78 (3.4%) participants who were not previously diagnosed as having MetS but who had a high 10-year estimated risk of MetS as measured by the Framingham risk score (11.67%).

CONCLUSION

The addition of IMT to the traditional criteria for the diagnosis of the MetS may help identify individuals who otherwise would not have been identified to be at high risk of CVD.

A cross-sectional study of intima-media thickness, ethnicity, metabolic syndrome, and cardiovascular risk in 2268 study participants

OBJECTIVE

To describe the association between intima-media thickness (IMT) and metabolic syndrome (MetS) and to examine if the addition of IMT to a traditional MetS definition adds value to the assessment of predicted cardiovascular disease (CVD) risk in a large multiethnic population.

PARTICIPANTS AND METHODS

In this cross-sectional study, carotid IMT was measured in 2268 men and women as part of a wellness physical examination between August 1, 2000, and October 1, 2001. The wellness examination included a fasting lipid panel, physical examination, and medical history. Mean IMT was described by sex, ethnicity, and the MetS. Predicted risk for CVD was determined with IMT as a component of the diagnostic criteria for MetS.

RESULTS

Intima-media thickness increased with each additional component of the MetS, increasing from 0.516 mm for 0 components to 0.688 mm for 4 or more components (P<.001). In each ethnic group (non-Hispanic whites, blacks, Hispanics, and Asians), those with the MetS had higher mean IMT (increased by 0.084 mm to 0.134 mm) than those without MetS. The addition of IMT as a "new" component in the diagnosis of MetS allowed us to identify 78 (3.4%) participants who were not previously diagnosed as having MetS but who had a high 10-year estimated risk of MetS as measured by the Framingham risk score (11.67%).

CONCLUSION

The addition of IMT to the traditional criteria for the diagnosis of the MetS may help identify individuals who otherwise would not have been identified to be at high risk of CVD.

More knocks to the oxidation hypothesis for vascular disease?

The oxidation hypothesis for CHD (coronary heart disease) is attractive; however, the almost universal failure of antioxidant vitamin supplementation as a CVD (cardiovascular disease) risk modifier challenges the oxidation hypothesis, at least as a concept that easily 'translates' into clinical benefit for the population. At the same time, quality prospective data on lipid or protein oxidation markers as predictors of vascular events are sparse. In the present issue of Clinical Science, Woodward and co-workers provide much needed prospective data examining the relationship between markers of oxidative damage and CHD outcome in a general population. Despite noting the expected associations between several established CHD risk factors and CHD events, no significant link was observed between measured oxidation markers and CHD risk, a finding which further challenges the oxidation hypothesis for CHD.

Oxidized LDL and C-reactive protein level in relation to carotid intima-media thickness in population with risk factors for atherosclerosis

Introduction. Elevated levels of oxidized LDL cholesterol (OxLDL) are considered to be a key factor of initiating and accelerating atherosclerosis. It promotes atherosclerosis through inflammatory and immunologic mechanisms that lead to the formation of macrophage foam cells. Objective. To determine the relationship among OxLDL, C-reactive protein (CRP) level and carotid intima-media thickness (IMT) in population with risk factors for atherosclerosis. Methods. The study group consisted of 125 clinically healthy, hypercholesterolaemic subjects (49.3?5.7 years; 75 females and 50 males) compared with 100 age-matched population-based control subjects. The study group was divided into two subgroups: subgroup A (the levels of LDL cholesterol > 5 mmol/L) and subgroup B (the levels of LDL cholesterol <5 mmol/L). None of the subjects had history of cerebrovascular, ischaemic heart disease, hypertension or diabetes mellitus. Lipid profiles were measured by enzymatic methods. OxLDL was measured by using a specific monoclonal antibody, mAb4E6. CRP was measured using hemiluminescent methods (Immulite - DPC). The common carotid IMT was measured by the B-mode ultrasound. Results Compared to controls, the study group had higher levels of OxLDL (119.97?43.15 vs. 82.03?25.99 IU/L; p<0.01) and CRP (6.20?3.55 vs. 2.68?3.04 mg/ml; p<0.05). IMT was significantly higher in study subjects (1.14?0.38 vs. 0.72?0.24 mm; p<0.05). We also found that, in the whole study group, IMT significantly positively correlated with OxLDL (r=0.442; p<0.05). We found that in the study subgroup A, IMT positively correlated with CRP (r=0.792; p<0.01). In controls, we found a significantly positive association between IMT and OxLDL (r=0.781; p<0.01) and CRP (r=0.748; p<0.01). Conclusion. The elevated levels of OxLDL and CRP are associated with higher common carotid intima-media thickness in population with risk factors for atherosclerosis.

Paraoxonases role in the prevention of cardiovascular diseases

Increased oxidative stress is a characteristic of patients with high risk for atherosclerosis development (hypercholesterolemic, hypertensive, diabetic), and the above phenomenon was shown to be associated with attenuated antioxidative status. The increased oxidative stress in atherosclerotic patients is present in their blood, as well as in their arterial wall cells, including macrophages, the hallmark of foam cells formation during early atherogenesis. Serum high density lipoprotein (HDL)-associated paraoxonase 1 (PON1) reduces oxidative stress in lipoproteins, in macrophages, and in the atherosclerotic lesion, whereas paraoxonase 2 (PON2, which is present in tissues, but not in serum) acts as an antioxidant at the cellular and not humoral level. Both PON1 and PON2 protect against atherosclerosis development, and this phenomenon could be related to their antioxidative properties. The use of nutritional antioxidants such as vitamin E, carotenoids (lycopene and beta-carotene), and mainly polyphenols (such as those present in red wine, licorice root ethanolic extract, or in pomegranate) by atherosclerotic animals and also by cardiovascular patients, leads to a reduction in oxidative stress and to the attenuation of atherosclerosis development. These latter phenomena could be related to the nutritional antioxidants-induced increase in HDL PON1 activity (effects on gene expression, on preventing enzyme inactivation, and on increasing PON1 stability through its binding to HDL), as well as an increase in macrophage PON2 activation (at the gene expression level).

Evaluation of whole antioxidant defenses of human mononuclear cells by a new in vitro biological test: lack of correlation between erythrocyte and mononuclear cell resistance to oxidative stress

OBJECTIVES

This work aims to evaluate the resistance of mononuclear cells to oxidative stress using a "KRL" test, formerly utilized to evaluate the resistance of erythrocyte to free radicals.

METHODS

The "KRL" test evaluates the resistance to lysis of cells treated by free radicals generated under standardized conditions.

RESULTS

We defined new analytical parameters (level of radical production, time course, number of cells) to obtain an accurate assay determining the resistance to oxidative stress of mononuclear cells, in comparison to that of erythrocytes. This test allows the evaluation of change in the redox state of mononuclear cells (improved by an antioxidant mix or deteriorated by antimycin A-induced mitochondrial radical overproduction). Interestingly, our data show that the sensitivity of mononuclear cells to oxidative stress is not correlated with the susceptibility of erythrocytes to oxidative stress.

CONCLUSIONS

The quantification of the susceptibility of mononuclear cells to oxidative stress gives additional information (in addition to erythrocyte resistance) and could be helpful for patients with chronic inflammation.