Analytical Performance and Diagnostic Accuracy of Immunometric Assays for the Measurement of Circulating Oxidized LDL

The Effect of 75 Grams of Glucose during OGTT on Plasma Markers of Lipid and Lipoprotein Peroxidation, Oxidized LDL and Thiobarbituric Acid Reactive Substances, in People with Increased Body Mass

Obesity, currently defined as a disease, is associated with a number of metabolic disorders, and oxidative stress is discussed as the link between them. The aim of this study was to analyze the plasma markers reflecting oxidative modification of lipids and lipoproteins, oxidized LDL (oxLDL) and thiobarbituric acid reactive substances (TBARS), under the influence of the 75 g of oral glucose during oral glucose tolerance test (OGTT), in patients with increased body mass. One hundred twenty individuals of both genders (46 women and 74 men) aged 26 to 75 years with increased body mass (BMI > 25 kg/m2) were recruited for the study. OGTT was performed in each of the qualified persons, and glycemia, insulinemia, and concentrations of oxLDL and TBARS were measured fasting and at 120 min of OGTT. The homeostasis model assessment of insulin resistance (HOMA-IR) was used to assess the degree of insulin resistance (IR). In order to assess the changes of the investigated parameters under the influence of 75 g glucose, the index ROGTT = [120’]/[0’] was calculated to obtain oxLDL-ROGTT and TBARS-ROGTT. The statistical analysis was performed in the entire study population and subsequent groups from H1 to H4, defined by HOMA-IR quartiles. In the entire study population and the subgroups, oxidative stress markers changed during OGTT. From H1 to H4 group, increasing oxLDL and TBARS were observed both in the fasting state and at 120 min of OGTT, and the oxLDL-ROGTT index decreased from the H2 to the H4 group. The intensification of IR in people with increased body mass may predispose them to enhanced oxidative modification of lipoproteins. Individual reduction in the concentration of oxLDL during OGTT, in reference to fasting value (decreased oxLDL-ROGTT), suggests increased uptake of modified lipoproteins by scavenger receptor-presenting cells or increased migration to the vascular wall.

Investigation of Hyperlipidemia Associated with Increased Levels of Oxidized Low-Density Lipoproteins and 8-Hydroxy-2´-Deoxyguanosine

BACKGROUND

Hyperlipidemia is a common risk factor for atherosclerosis, heart diseases, and other pathological conditions. The factors leading to the oxidation of native low-density lipoproteins remain of valuable importance for a better understanding of the mechanisms leading to these pathologies. The aim of the present study was to evaluate the association between lipid status and the levels of oxidized low-density lipoproteins and 8-hydroxy-2´-deoxyguanosine.

METHODS

One hundred and fourteen participants were enrolled. Lipid profile parameters were measured and used individually to categorize subjects into two groups of normal and hyperlipidemic cases according to the international reference ranges. Oxidized low-density lipoproteins and 8-hydroxy-2´-deoxyguanosine were then compared in normal and high lipid profile groups. The obtained results were then statistically analyzed.

RESULTS

8-Hydroxy-2´-deoxyguanosine was found to be positively correlated with hypercholesterolemia, hypertriglyceridemia, and high levels of low-density lipoproteins (r = 0.53, 0.41, and 0.60), respectively (p<0.001). A positive correlation was observed also between the levels of oxidized low-density lipoproteins and the same lipid profile parameters (r = 0.42, 0.31, and 0.45), respectively (p<0.001).

CONCLUSION

The present study suggests that disturbance in lipid profile may result in increased levels of oxidized low-density lipoproteins and oxidative stress in the study group; however, a larger sample is needed to confirm the present findings.

Low Serum Vitamin D Status Is Associated with Incident Alzheimer's Dementia in the Oldest Old

Background. Vitamins A, D and E and beta-carotene may have a protective function for cognitive health, due to their antioxidant capacities. Methods. We analyzed data from 1334 non-demented participants (mean age 84 years) from the AgeCoDe study, a prospective multicenter-cohort of elderly general-practitioner patients in Germany, of whom n = 250 developed all-cause dementia and n = 209 developed Alzheimer’s dementia (AD) during 7 years of follow-up. We examined whether concentrations of vitamins A (retinol), D (25-hydroxycholecalciferol) and E (alpha-tocopherol) and beta-carotene, would be associated with incident (AD) dementia. Results. In our sample, 33.7% had optimum vitamin D concentrations (≥50 nmol/L). Higher concentrations of vitamin D were associated with lower incidence of all-cause dementia and AD (HR 0.99 (95%CI 0.98; 0.99); HR0.99 (95%CI 0.98; 0.99), respectively). In particular, subjects with vitamin D deficiency (25.3%, <25 nmol/L) were at increased risk for all-cause dementia and AD (HR1.91 (95%CI 1.30; 2.81); HR2.28 (95%CI 1.47; 3.53), respectively). Vitamins A and E and beta-carotene were unrelated to (AD) dementia. Conclusions. Vitamin D deficiency increased the risk to develop (AD) dementia. Our study supports the advice for monitoring vitamin D status in the elderly and vitamin D supplementation in those with vitamin D deficiency. We observed no relationships between the other vitamins with incident (AD) dementia, which is in line with previous observational studies.

Oxidized LDL is stable in human serum under extended thawed-state conditions ranging from -20 °C to room temperature

Introduction

Oxidized LDL (oxLDL) is formed by the spontaneous reaction between aldehyde byproducts of lipid peroxidation and lysine residues of apolipoprotein B within LDL. Clinically, oxLDL is used as a marker of coronary artery disease and predictor of metabolic syndrome risk. Despite its popularity as a clinical marker, no systematic studies of oxLDL stability, in which serum or plasma has been pre-analytically exposed to an array of different time and temperature conditions, have been carried out.

Objective

To systematically evaluate the stability of oxLDL in human serum samples exposed to thawed conditions (> -30 °C) for varying periods of time while monitoring a second protein/small molecule redox system as a positive control for non-enzymatic biomolecular activity.

Methods

OxLDL was measured in serum samples, from 24 different humans, that had been pre-exposed to three different time courses at 23 °C, 4 °C and -20 °C using ELISA kits from Mercodia that employ the 4E6 mouse monoclonal antibody. A liquid chromatography/mass spectrometry-based marker of serum exposure to thawed conditions known as ΔS-Cys-Albumin was employed as a positive control.

Results

OxLDL was stable in serum exposed to 23 °C for up to 48 h, 4 °C for 21 days, or -20 °C for 65 days. ΔS-Cys-Albumin changed dramatically during these time courses (p < 0.001).

Conclusions

OxLDL is remarkably stable ex vivo in human serum samples exposed to thawed conditions.

A Systematic Review of the Cardiometabolic Benefits of Plant Products Containing Mixed Phenolics and Polyphenols in Postmenopausal Women: Insufficient Evidence for Recommendations to This Specific Population

Menopause is characterized by endocrine and physiological changes and is often accompanied by increased body weight and cholesterol, glucose intolerance, and/or hypertension. These alterations are associated with increased risk for cardiovascular diseases (CVDs) and Type II diabetes mellitus (T2DM) that may be moderate by dietary plant phenolic compounds. In this review, we examine the current evidence of the impact of a variety of plant products (foods, extracts, beverages) rich in a mixture of phenolics and polyphenols on: (i) glucose and insulin levels; (ii) lipid profile; (iii) blood pressure; and (iv) biomarkers of inflammation and oxidative stress in postmenopausal women. We critically evaluate both the results of a range of intervention studies conducted in this specific subpopulation and the level of evidence supporting the benefits of consuming those products after the menopause. Overall, the current available evidence does not allow for specific dietary recommendations of these plant products rich in phenolics and polyphenols in this high-risk subpopulation. Our data show rather variable and small effects of the different products examined on the cardiometabolic biomarkers and further support the need to: (1) improve the quality of the study designs and data reporting; and (2) understand the variability in the response of the different biomarkers and establish clear differences between healthy and cardiometabolic disease levels.

The effect of dietary nitrate and vitamin C on endothelial function, oxidative stress and blood lipids in untreated hypercholesterolemic subjects: A randomized double-blind crossover study

BACKGROUND

Vitamin C may enhance nitric oxide (NO) production through stepwise reduction of dietary nitrate (NO₃) to nitrite (NO₂) to NO. The combined effect of vitamin C and NO₃ supplementation is relatively unexplored in untreated hypercholesterolemia.

AIMS

We aimed to examine whether co-administration of vitamin C and nitrate for 4-weeks would improve endothelial function (primary outcome), plasma NO metabolites, oxidative stress, and blood lipids (secondary outcomes).

METHODS

Subjects 50-70 years of age with low density lipoprotein (LDL) > 130 mg/dL and RHI ≤2 were enrolled in this randomized double-blind crossover study. Subjects were assigned to two 4-week supplementation treatments starting with 70 ml of concentrated beetroot juice (CBJ) with 1000 mg of vitamin C (NC) or CBJ with matched placebo (N), then switched to alternate treatment following 2-week washout. The change in reactive hyperemia index (RHI), sum of plasma NO metabolites (NO₂ + NO₃ (NOx)), oxidized LDL (oxLDL), and serum lipids were assessed at baseline and at 4-weeks of each treatment period.

RESULTS

Eighteen subjects (11M:7F) completed all study visits. No significant treatment differences were observed in RHI change (N: 0.21 ± 0.12; NC: 0.20 ± 0.17; p = 0.99). Secondary analysis revealed that a subgroup of NC subjects who started with a baseline RHI of <1.67 (threshold value for ED) had greater improvements in RHI compared to subjects with RHI >1.67 (1.23 ± 0.15 to 1.96 ± 0.19; n = 8 vs. 1.75 ± 0.11 to 1.43 ± 0.10; n = 8; p = 0.02). Compared to N, NC experienced a significant increase in plasma NOx (N: 94.2 ± 15.5 μmol/L; NC: 128.7 ± 29.1 μmol/L; p = 0.01). Although there was no significant difference in oxLDL change between treatments (N: -1.08 ± 9.8 U/L; NC: -6.07 ± 9.14 U/L; p = 0.19), NC elicited significant reductions in LDL (N: 2.2 ± 2; NC: -10.7 ± 23; p = 0.049), triglycerides (N: 14.6 ± 43; NC: -43.7 ± 45; p = 0.03), and no change in serum high density lipoprotein. Within treatment group comparisons showed that only NC reduced oxLDL significantly from baseline to 4 weeks (p = 0.01).

CONCLUSIONS

No between intervention differences were observed in RHI. RHI only improved in NC subjects with ED at intervention baseline. Four weeks of NC enriched the NO pool and promoted reduction of blood lipids and oxidative stress in subjects with hypercholesterolemia. These preliminary findings highlight a supplementation strategy that may reduce the progression of atherosclerotic disease and deserves further attention in studies using flow mediated dilation methods.

CLINICAL TRIAL REGISTRATION

www.clinicaltrials.gov (NCT04283630).

Metabolism Regulation and Redox State: Insight into the Role of Superoxide Dismutase 1

Energy metabolism and redox state are strictly linked; energy metabolism is a source of reactive oxygen species (ROS) that, in turn, regulate the flux of metabolic pathways. Moreover, to assure redox homeostasis, metabolic pathways and antioxidant systems are often coordinately regulated. Several findings show that superoxide dismutase 1 (SOD1) enzyme has effects that go beyond its superoxide dismutase activity and that its functions are not limited to the intracellular compartment. Indeed, SOD1 is secreted through unconventional secretory pathways, carries out paracrine functions and circulates in the blood bound to lipoproteins. Striking experimental evidence links SOD1 to the redox regulation of metabolism. Important clues are provided by the systemic effects on energy metabolism observed in mutant SOD1-mediated amyotrophic lateral sclerosis (ALS). The purpose of this review is to analyze in detail the involvement of SOD1 in redox regulation of metabolism, nutrient sensing, cholesterol metabolism and regulation of mitochondrial respiration. The scientific literature on the relationship between ALS, mutated SOD1 and metabolism will also be explored, in order to highlight the metabolic functions of SOD1 whose biological role still presents numerous unexplored aspects that deserve further investigation.

Organochlorine pesticides and polychlorinated biphenyls (PCBs) in early adulthood and blood lipids over a 23-year follow-up

BACKGROUND

Some evidence in humans suggests that persistent organic pollutants (POPs), including organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs), may alter the blood lipid composition. This study analyzed associations between serum POPs concentrations in young adulthood with blood lipid levels up to 23 years later.

METHODS

Serum POPs were measured in year 2 of follow-up (n = 180 men and women, ages: 20-32y), and plasma lipids in follow-up years 2, 7, 10, 15, 20 and 25. 32 POPs were detectable in ≥75% of participants (23 PCBs, 8 OCPs and PBB-153). We created summary scores for PCBs and OCPs for both wet-weight, and lipid standardized (LP) concentrations. We used repeated measures regression adjusting for demographic factors, BMI, smoking, diabetes status, among others.

RESULTS

We observed positive associations of the 23 LP-PCB score with total cholesterol (β_{per SD increase} [95%CI]: 5.0 mg/dL [0.7, 9.2]), triglycerides (7.8 mg/dL [-0.9, 16.5]), LDL (4.2 mg/dL [0.2, 8.2]), oxidized LDL 3.4 U/L (-0.05, 6.8), and cholesterol/HDL ratio (0.2 [0.02, 0.3]). The associations for triglycerides (14.7 mg/dL [0.4, 20.1]), cholesterol/HDL (0.33 [0.09, 0.56]) and, to some extent, LDL (4.7 md/dL [-1.6, 10.9]) were only observed among participants in the upper 50th percentile of BMI. Non-dioxin-like PCBs had stronger associations that dioxin-like PCBs. OCPs and PBB-s had positive associations with most outcomes.

CONCLUSIONS

PCBs and PBB-153 measured in young adulthood were positively associated with prospective alterations in most blood lipid components, with evidence of effect modification by BMI. Further longitudinal studies with multiple measures of POPs overtime are needed.

Effects of a lifestyle intervention on markers of cardiometabolic risk and oxidized lipoproteins among obese adolescents with prediabetes

OBJECTIVE

Obesity and hyperglycaemia contribute to the atherosclerotic process in part through oxidative modifications to lipoprotein particles. The present study aimed to evaluate the effects of a lifestyle intervention on markers of oxidized lipoproteins in obese Latino adolescents with prediabetes.

DESIGN

Pre-post design.

SETTING

Participants were enrolled into a 12-week lifestyle intervention. Measurements pre- and post-intervention included anthropometrics and body composition, lipid panel, oxidized LDL (oxLDL), oxidized HDL (oxHDL), intake of fresh fruits and vegetables, and cardiorespiratory fitness.

PARTICIPANTS

Thirty-five obese Latino adolescents (seventeen females, eighteen males; mean age 15·5 (sd 1·0) years; mean BMI percentile 98·5 (sd 1·2)) with prediabetes.

RESULTS

Intervention participation resulted in significant reductions in weight (-1·2 %, P = 0·042), BMI and BMI percentile (-2·0 and -0·4 %, respectively, P < 0·001), body fat (-7·0 %, P = 0·025), TAG (-11·8 %, P = 0·032), total cholesterol (-5·0 %, P = 0·002), VLDL-cholesterol (-12·5 %, P = 0·029), and non-HDL-cholesterol (-6·7 %, P = 0·007). Additionally, fitness (6·4 %, P < 0·001) and intake of fruits and vegetables (42·4 %, P = 0·025) increased significantly. OxLDL decreased significantly after the intervention (51·0 (sd 14·0) v. 48·7 (sd 12·8) U/l, P = 0·022), while oxHDL trended towards a significant increase (395·2 (sd 94·6) v. 416·1 (sd 98·4) ng/ml, P = 0·056).

CONCLUSIONS

These data support the utility of lifestyle intervention to improve the atherogenic phenotype of Latino adolescents who are at high risk for developing premature CVD and type 2 diabetes.

Relation between circulating oxidized-LDL and metabolic syndrome in children with obesity: the role of hypertriglyceridemic waist phenotype

BACKGROUND

The association between oxidative stress (OS) and metabolic syndrome (MetS) has been reported in adults. We analyzed the relation between circulating oxidized low-density lipoproteins (Ox-LDL) and MetS in pediatric ages in order to define whether plasma Ox-LDL levels are correlated to obesity and whether oxidative damage, using serum Ox-LDL levels as a proxy, are associated with MetS.

METHODS

We enrolled 178 children (11.8±2.6 years). On the basis of a body mass index (BMI) threshold, the subjects were classified as: normal weight BMI <75th percentile; overweight BMI 75-97th percentile; obese BMI >97th percentile. Patients were classified as having MetS if they met three or more of the following criteria for age and sex: BMI >97th percentile, triglyceride levels >95th percentile, high-density lipoprotein (HDL) cholesterol level <5th percentile, systolic blood pressure (SBP) and/or diastolic blood pressure (DBP) >95th percentile and impaired glucose tolerance.

RESULTS

Obese children showed increased MetS prevalence (p=0.001) and higher Ox-LDL levels compared to normal- and overweight subjects (p<0.05), with a limited relation between Ox-LDL and MetS (p=0.06). Waist-to-height ratio (W/HtR) (p=0.02), triglycerides (TG) (p=0.001) and LDL-cholesterol (p<0.001) resulted independent predictors of increased plasma Ox-LDL levels.

CONCLUSIONS

Oxidative damage was correlated with a hypertriglyceridemic waist phenotype and can be a precocious marker of MetS and cardiometabolic risk in obese children.

Low-density lipoprotein oxidation biomarkers in human health and disease and effects of bioactive compounds

Based on the significance of oxidized low-density lipoprotein (LDL) in health and disease, this review focuses on human studies addressing oxidation of LDL, including three lines of biomarkers, (i) ex vivo LDL resistance to oxidation, a "challenge test" model, (ii) circulating oxidized LDL, indicating the "current in vivo status", and (iii) autoantibodies against oxidized LDL as fingerprints of an immune response to oxidized LDL, along with circulating oxysterols and 4-hydroxynonenal as biomarkers of lipid peroxidation. Lipid peroxidation and oxidized LDL are hallmarks in the development of various metabolic, cardiovascular and other diseases. Changes further occur across life stages from infancy to older age as well as in athletes and smokers. Given their responsiveness to targeted nutritional interventions, markers of LDL oxidation have been employed in a rapidly growing number of human studies for more than 2 decades. There is growing interest in foods, which, besides providing energy and nutrients, exert beneficial effects on human health, such as protection of DNA, proteins and lipids from oxidative damage. Any health claim, however, needs to be substantiated by supportive evidence derived from human studies, using reliable biomarkers to demonstrate such beneficial effects. A large body of evidence has accumulated, demonstrating protection of LDL from oxidation by bioactive food compounds, including vitamins, other micronutrients and secondary plant ingredients, which will facilitate the selection of oxidation biomarkers for future human intervention studies and health claim support.

Markers of Oxidative Stress in Dogs with Myxomatous Mitral Valve Disease are Influenced by Sex, Neuter Status, and Serum Cholesterol Concentration

Background

Cardiovascular disease has been associated with oxidative stress, which has been suggested to contribute to myocardial remodeling in human patients. Little is known about the relationship between myxomatous mitral valve disease (MMVD) and oxidative stress in dogs.

Objective

To determine whether clinical stage of MMVD is associated with changes in the plasma concentrations of certain markers of oxidative stress in clinically healthy dogs and dogs with MMVD.

Animals

Seventy five privately owned dogs: 59 cavalier King Charles Spaniels (CKCS) with different severities of MMVD and 16 dogs of different breeds with clinical signs of congestive heart failure (CHF) caused by MMVD.

Methods

Markers of oxidative stress including malondialdehyde (MDA), oxidized low‐density lipoprotein (oxLDL), and vitamin E (α‐tocopherol and γ‐tocopherol) were measured in plasma and their association with clinical stage of MMVD was assessed by regression analyses.

Results

Plasma oxLDL concentration was significantly lower in female dogs compared with males (P = .01). Significantly higher plasma γ‐tocopherol concentrations were found in neutered (P = .003) dogs. Vitamin E (α‐tocopherol [P = .0004] and γ‐tocopherol [P = .003]) was associated with body condition score (BCS), but the association disappeared when cholesterol was included in the analyses. All markers of oxidative stress (MDA, oxLDL, and vitamin E) were positively associated with serum cholesterol concentration (P ≤ .04), but none were associated with clinical stage of MMVD.

Conclusions

In conclusion, markers of oxidative stress are associated with sex, BCS, neuter status, and cholesterol. The results cannot confirm a relationship between oxidative stress and clinical stage of the disease in dogs with MMVD.

Inverse associations between cardiometabolic risk factors and 25-hydroxyvitamin D in obese American children and adolescents

OBJECTIVES

To examine the association between 25-hydroxyvitamin D [25(OH)D] concentrations and cardiometabolic risk factors in obese American children.

METHODS

A cross-sectional study was conducted on 209 obese children (55% females, 25.8% black) aged between 6 and 19 years old. Study measurements included plasma 25(OH)D concentrations, blood pressure, lipids and oxidized LDL levels, insulin resistance (IR) indices from glucose, insulin and 5 hour oral glucose tolerance test.

RESULTS

Fifty-one percent of the children had vitamin D deficiency. Older age [OR (95% CI) = 1.16 (1.00, 1.35)], black race/ethnicity [15.39 (5.79, 40.92)], winter/spring season [3.46 (1.69, 7.02)] and higher body mass index (BMI) [1.05 (0.99, 1.11)] were associated with increased odds of having vitamin D deficiency. None of cardiometabolic risk factors examined were significantly associated with vitamin D deficiency in age, race/ethnicity, season, and BMI adjusted models. In age, race/ethnicity, season and BMI adjusted models, total cholesterol (β = -0.001, P = 0.013), non-HDL-C (β = -0.001, P = 0.014), and oxidized LDL (β = -0.087, P = 0.045) were inversely associated with log-transformed 25(OH)D. An approximate 10 mg/dl increase in total cholesterol or in non-HDL-C was associated with an approximate 1.3% decrease in the geometric mean of 25(OH)D concentration. Further a 10% increase in ox-LDL levels was associated with an approximate 0.8% decrease in the geometric mean of 25(OH)D.

CONCLUSION

Vitamin D deficiency is prevalent in obese American children. There was evidence that some cardiometabolic risk factors including lipid levels and oxidized LDL levels were significantly inversely associated with 25(OH)D concentration in our sample. Am. J. Hum. Biol. 28:736-742, 2016. © 2016 Wiley Periodicals, Inc.

Longitudinal study of circulating oxidized LDL and HDL and fatty liver: the Cardiovascular Risk in Young Finns Study

Oxidative reactions are thought to play a role in the inflammatory condition called fatty liver. It is unclear whether oxidized lipoprotein lipids or proteins are associated with future fatty liver. In the Cardiovascular Risk in Young Finns Study, we determined the circulating levels of LDL and HDL oxidized lipids and studied their associations with fatty liver assessed by ultrasonography. There were 1286 middle-aged subjects with normal liver and 288 subjects with fatty liver. Analysis of oxidized lipids consisted of conjugated dienes in isolated HDL (oxHDLlipids) and LDL (oxLDLlipids). Oxidized LDL was also measured with a method based on antibodies against oxidized apolipoprotein B (oxLDLprot). After adjustment for age, sex, leisure-time physical activity, body mass index, alcohol intake, smoking, serum LDL and HDL cholesterol as well as particle concentrations, participants with elevated oxLDLlipids (odds ratio for 1-SD change in oxLDLlipids = 1.27, p =0.011) had an increased risk for fatty liver. Similarly, a high oxidation score (oxLDLlipids + oxLDLprot) was directly associated with fatty liver (odds ratio=1.34, p = 0.012). The strongest direct association was seen with a high oxLDLlipids/oxHDLlipids ratio (odds ratio=1.49, p = 0.001). These data suggest that oxidized lipoprotein lipids are linked with the risk of fatty liver in middle-aged adults.

Vitamin A Decreases Cytotoxicity of Oxidized Low-Density Lipoprotein in Patients with Atherosclerosis

BACKGROUND

Oxidized low-density lipoprotein (ox-LDL) is implicated in initiation and progression of atherosclerosis. Previously, we found that ox-LDL increases vulnerability of peripheral blood mononuclear cells (PBMCs) in atherosclerotic patients compared to controls. Vitamin A induces proliferation of PBMCs. The aim of this study was to determine the effect of vitamin A supplementation on PBMC survival against LDL and different doses of ox-LDL.

METHOD

In this double-blind placebo-controlled trial, we recruited 35 atherosclerotic patients and 38 healthy controls and randomly allocated them into placebo and vitamin A groups, which received either placebo or 25,000 IU/day of vitamin A for 3 months. PBMCs were isolated, cultured, and stimulated by 1 µg/mL LDL as well as 1 µg/mL and 50 µg/mL ox-LDL. The stimulation indexes (SIs) of PBMCs were calculated to identify cell viability. Additionally, the circulating ox-LDL levels were measured by ELISA.

RESULTS

Viability of PBMCs stimulated by 50 µg/mL ox-LDL significantly increased following vitamin A supplementation in patients (p < 0.01). The levels of circulating ox-LDL were not changed by vitamin A treatment. Ox-LDL levels were strongly and positively correlated to SI of PBMCs stimulated by 1 µg/mL LDL and1 µg/mL ox-LDL in all groups.

CONCLUSION

Vitamin A decreases cytotoxicity of high-dose ox-LDL and improves PBMC viability. The protective effect of vitamin A is not mediated by an antioxidative mechanism, but may instead have been due to intracellular protection of the apoptotic machinery or induction of proliferation of the cells. Higher levels of ox-LDL increase PBMC irritability in all participants.

Göttingen minipig model of diet-induced atherosclerosis: influence of mild streptozotocin-induced diabetes on lesion severity and markers of inflammation evaluated in obese, obese and diabetic, and lean control animals

Background

From a pharmacological perspective, readily-available, well-characterized animal models of cardiovascular disease, including relevant in vivo markers of atherosclerosis are important for evaluation of novel drug candidates. Furthermore, considering the impact of diabetes mellitus on atherosclerosis in human patients, inclusion of this disease aspect in the characterization of a such model, is highly relevant. The objective of this study was to evaluate the effect of mild streptozotocin-induced diabetes on ex- and in vivo end-points in a diet-induced atherosclerotic minipig model.

Methods

Castrated male Göttingen minipigs were fed standard chow (CD), atherogenic diet alone (HFD) or with superimposed mild streptozotocin-induced diabetes (HFD-D). Circulating markers of inflammation (C-reactive protein (CRP), oxidized low-density lipoprotein (oxLDL), plasminogen activator inhibitor-1, lipid and glucose metabolism were evaluated together with coronary and aortic atherosclerosis after 22 or 43 diet-weeks. Group differences were evaluated by analysis of variance for parametric data and Kruskal–Wallis test for non-parametric data. For qualitative assessments, Fisher’s exact test was applied. For all analyses, p < 0.05 was considered statistically significant.

Results

Overall, HFD and HFD-D displayed increased CRP, oxLDL and lipid parameters compared to CD at both time points. HFD-D displayed impaired glucose metabolism as compared to HFD and CD. Advanced atherosclerotic lesions were observed in both coronary arteries and aorta of HFD and HFD-D, with more advanced plaque findings in the aorta but without differences in lesion severity or distribution between HFD and HFD-D. Statistically, triglyceride was positively (p = 0.0039), and high-density lipoprotein negatively (p = 0.0461) associated with aortic plaque area.

Conclusions

In this model, advanced coronary and aortic atherosclerosis was observed, with increased levels of inflammatory markers, clinically relevant to atherosclerosis. No effect of mild streptozotocin-induced diabetes was observed on plaque area, lesion severity or inflammatory markers.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0670-2) contains supplementary material, which is available to authorized users.

Correlation between salivary and serum oxidized LDL levels: a pilot study on overweight/obese subjects

BACKGROUND

Saliva contains a variety of substances and could be functionally equivalent to serum in reflecting the physiological state of the body, including metabolic variations. Salivary samples are non-invasive, safe, and easier to handle than serum. Oxidized LDL cholesterol (oxLDL) is an additional cardiovascular risk factor playing an important role in atheromatous plaque formation; overweight/obese subjects present an increase in oxLDL concentrations. The aims of the study were to assess oxLDL salivary levels, if detectable, and to verify their possible correlation with serum in overweight/obese subjects.

METHODS

Thirty-five consecutive overweight/obese subjects and 10 normal weight controls were enrolled. Serum and salivary oxLDL levels were measured by a commercial enzyme-linked-immunosorbent assay (ELISA method).

RESULTS

oxLDL levels were detectable in salivary samples and correlated (P = 0.001) with serum levels. Overweight/obese subjects showed serum and salivary oxLDL levels higher than controls (P = 0.000 and P = 0.022, respectively).

CONCLUSIONS

Our study showed the presence of oxLDL in salivary samples and highlighted a correlation between salivary oxLDL levels and their counterpart in serum. Moreover, salivary oxLDL levels were higher in overweight/obese subjects than in controls. Therefore, a salivary sample could be functionally equivalent to serum in monitoring cardiovascular risk in overweight/obese subjects.

Mitochondrial DNA sequence associations with dementia and amyloid-β in elderly African Americans

Mitochondrial dysfunction occurs early in the course of several neurodegenerative diseases, and is potentially related to increased oxidative damage and amyloid-β (Aβ) formation in Alzheimer's disease. The goals of this study were to assess mtDNA sequence associations with dementia risk, 10-year cognitive change, and markers of oxidative stress and Aβ among 1089 African-Americans in the population-based Health, Aging, and Body Composition Study. Participants were free of dementia at baseline, and incidence was determined in 187 (18%) cases over 10 to 12 follow-up years. Haplogroup L1 participants were at increased risk for developing dementia (odds ratio = 1.88, 95% confidence interval = 1.23-2.88, p = 0.004), lower plasma Aβ42 levels (p = 0.03), and greater 10-year decline on the Digit Symbol Substitution Test (p = 0.04) when compared with common haplogroup L3. The p.V193I, ND2 substitution was associated with significantly higher Aβ42 levels (p = 0.0012), and this association was present in haplogroup L3 (p = 0.018) but not L1 (p = 0.90) participants. All associations were independent of potential confounders, including APOEε4 status and nuclear genetic ancestry. Identification of mtDNA sequence variation associated with dementia risk and cognitive decline may contribute to the development of new treatment targets and diagnostic tests that identify responders to interventions targeting mitochondria.

Oxidized low density lipoprotein and total antioxidant capacity in type-2 diabetic and impaired glucose tolerance Saudi men

BACKGROUND

Oxidative modification of low density lipoproteins (LDL) convert these native particles into pathogenic, immunogenic and atherogenic particles. Factors enhance LDL oxidation are poorly understood, especially in conditions of hyperglycemia. The present study was conducted to investigate which metabolic conditions are associated with the promotion of LDL oxidation in different glycemic situations.

METHODS

Adult male participants (274) were selected from patients admitted to the outpatient department of Diabetes Center in Al-Noor Specialized Hospital in Makkah and other citizens and residents in the city. The studied group was classified into three sub-groups: Group-I: control group of non-diabetic normal subjects, Group-II: subjects with impaired glucose tolerance (IGT) and Group-III: cases of type-2 diabetes mellitus (DM). Measurement of fasting blood glucose, 2 hour post-prandial blood glucose, glycosylated hemoglobin (HbA1c), triglycerides, serum cholesterol, HDL-cholesterol, LDL-cholesterol, ox-LDL, Total Antoxidant capacity (TAC) and Malondialdehyde (MDA) were performed. The obtained results were statistically analyzed.

RESULTS

Oxidation of native LDL increase nearly two folds in Type-2 DM group compared to controls. There is also significant increase in Ox-LDL of IGT group compared to controls. The correlation between Ox-LDL concentration and HbA1c in the whole population of the study confirms the increased Ox-LDL in subjects with hyperglycemia. A negative correlation exists between the concentration of Ox-LDL and total antioxidant capacity (TAC) in each studied group and in the whole population of the study as well. A positive correlation also exists between Ox-LDL concentrations and LDL values, more clear in controls and Type-2 DM, while this correlation was not significant in IGT group. The ratio of LDL oxidation as expressed by ox-LDL/LDL was increased in IGT group compared to control. More significant increase was observed in type-2 DM group.

CONCLUSION

We concluded that the concentration of Ox-LDL increased in subjects with type-2 DM and IGT compared to controls. Moreover, oxidation of native LDL was associated with low levels of TAC and positively correlated with LDL levels, total cholesterol, HbA1c, body mass index (BMI) and increased age.

Relationship between oxidized low-density lipoprotein antibodies and obesity in different glycemic situations

BACKGROUND

Autoantibodies to oxidized low-density lipoprotein (oxLDL) are a heterogeneous group of antibodies that are controversially discussed to be either pathogenic or protective. Biochemical and anthropometric measurements correlated with increased levels of these antibodies are also controversial, especially in conditions of impaired glucose tolerance and type 2 diabetes mellitus. The present study was conducted to evaluate levels of oxLDL antibodies and their correlation with obesity in different glycemic situations.

METHODS

Two hundred and seventy-four adult males were classified into three subgroups: group 1 (n=125), comprising a control group of nondiabetic subjects; group 2 (n=77), comprising subjects with impaired glucose tolerance; and group 3 (n=72), comprising patients with type 2 diabetes mellitus. Body mass index was calculated, and measurement of oxLDL and oxLDL antibodies was performed.

RESULTS

Higher mean concentrations of oxLDL were found in the type 2 diabetes mellitus and impaired glucose tolerance groups (143.5±21.9 U/L and 108.7±23.7 U/L, respectively). The mean value for the control group was 73.5±27.5 U/L (P<0.001). Higher mean concentrations of anti-oxLDL antibodies were observed in the type 2 diabetes mellitus and impaired glucose tolerance groups (55.7±17.8 U/L and 40.4±17.6 U/L, respectively). The mean value for the control group was 20.4±10 U/L (P<0.001). Levels of anti-oxLDL antibodies were found to be positively and significantly correlated with body mass index in the control group (r=0.46), impaired glucose tolerance (r=0.51), type 2 diabetes mellitus group (r=0.46), and in the whole study population (r=0.44; P<0.001).

CONCLUSION

Anti-oxLDL antibody levels were increased in subjects with type 2 diabetes mellitus and impaired glucose tolerance and were positively correlated with obesity and body mass index.

The associations of oxidized high-density lipoprotein lipids with risk factors for atherosclerosis: the Cardiovascular Risk in Young Finns Study

Scavenging and reverse transport of atherogenic oxidized lipids by high-density lipoprotein (HDL) was recently suggested to contribute to atheroprotection. We investigated the associations of oxidized HDL lipids (oxHDLlipids) with known risk factors for atherosclerosis in a population-based cross-sectional study of 1395 Finnish adults ages 24-39 years (54.9% women). Analysis of oxidized lipids in isolated HDL and LDL (oxLDLlipids) was based on the determination of conjugated dienes. Oxidized LDL was measured also with a method based on antibodies against oxidized Apo-B (oxLDLprot). Serum lipids and risk factors were measured. In multivariable models, oxHDLlipids were associated inversely with age (partial R(2)=2.9% in men, 0.8% in women) and directly with oxLDLlipids (partial R(2)=3.4% in men, 4.2% in women) after adjustment for Apo-A1 (partial R(2)=9.6% in men, 25.2% in women). In men, oxHDLlipids were also associated inversely with insulin (partial R(2)=1.1%). In women, oxHDLlipids were additionally inversely associated with waist circumference (partial R(2)=1.8%) and daily smoking (partial R(2)=0.7%) and directly with C-reactive protein (CRP; partial R(2)=0.5%) and alcohol use (partial R(2)=0.5%). We conclude that an elevated risk profile characterized primarily by advanced age is associated with lower oxHDLlipid levels in a population of young Finnish men and women. Higher levels of oxHDLlipids are additionally associated with higher oxLDLlipid levels. In men, higher insulin levels are also associated with lower oxHDLlipid levels. In women, increased waist circumference and daily smoking are also associated with lower oxHDLlipid levels, and higher CRP levels and alcohol use are associated with higher oxHDLlipid levels.

Deregulation from CD4+ memory T cells to regulatory cells in patients with chronic renal failure: a pilot study

BACKGROUND

The aim of this study was to elucidate whether the CD4+ memory T (Tm) cells differentiation to regulatory T cells (Tregs) play a role in the immunological defects in patients with chronic kidney disease (CKD), and if the oxidized low-density lipoprotein (oxLDL) had affect on on CD4+ Tm cells and Tregs apoptosis in these subjects.

METHODS

CD4+ Tm cells and Tregs were detected by flow cytometry in each group of ten subjects. Apoptosis was measured by flow cytometry and confirmed by Western blotting.

RESULTS

The oxLDL concentration was significantly higher in CKD stage 4 (CKD4) patients than in controls, particularly in hemodialysis (HD) subjects (P < 0.001, respectively). In total, 100 μg/ml oxLDL significantly inhibited the CD4+ Tm cell proliferation. oxLDL-induced Tm generated Tregs apoptosis in controls and CKD4 patients, especially in HD patients (P < 0.001, respectively).

CONCLUSION

Dysregulation of CD4+ Tm cells converting into Tregs played a role in the immune defects of CKD patients, and oxLDL induced the apoptosis of Tm generating Tregs in these subjects. Larger size of sample should be investigated to confirm the findings in further studies.

Relationship of lipid oxidation with subclinical atherosclerosis and 10-year coronary events in general population

OBJECTIVES

To assess 1) the association of lipid oxidation biomarkers with 10-year coronary artery disease (CAD) events and subclinical atherosclerosis, and 2) the reclassification capacity of these biomarkers over Framingham-derived CAD risk functions, in a general population.

METHODS

Within the framework of the REGICOR study, 4782 individuals aged between 25 and 74 years were recruited in a population-based cohort study. Follow-up of the 4042 who met the eligibility criteria was carried out. Plasma, circulating oxidized low-density lipoprotein (oxLDL) and oxLDL antibodies (OLAB) were measured in a random sample of 2793 participants. End-points included fatal and non-fatal acute myocardial infarction (AMI) and angina. Carotid intima-media thickness (IMT) in the highest quintile and ankle-brachial index <0.9 were considered indicators of subclinical atherosclerosis.

RESULTS

Mean age was 50.0 (13.4) years, and 52.4% were women. There were 103 CAD events (34 myocardial infarction, 43 angina, 26 coronary deaths), and 306 subclinical atherosclerosis cases. Oxidized LDL was independently associated with higher incidence of CAD events (HR = 1.70; 95% Confidence Interval: 1.02-2.84), but not with subclinical atherosclerosis. The net classification index of the Framingham-derived CAD risk function was significantly improved when ox-LDL was included (NRI = 14.67% [4.90; 24.45], P = 0.003). No associations were found between OLAB and clinical or subclinical events. The reference values for oxLDL and OLAB are also provided (percentiles).

CONCLUSIONS

OxLDL was independently associated with 10-year CAD events but not subclinical atherosclerosis in a general population, and improved the reclassification capacity of Framingham-derived CAD risk functions.

Serum sphingolipids level as a novel potential marker for early detection of human myocardial ischaemic injury

Background: Ventricular tachyarrhythmias are the most common and often the first manifestation of coronary heart disease and lead to sudden cardiac death (SCD). Early detection/identification of acute myocardial ischaemic injury at risk for malignant ventricular arrhythmias in patients remains an unmet medical need. In the present study, we examined the sphingolipids level after transient cardiac ischaemia following temporary coronary artery occlusion during percutaneous coronary intervention (PCI) in patients and determined the role of sphingolipids level as a novel marker for early detection of human myocardial ischaemic injury.

Methods and Results: Venous samples were collected from either the coronary sinus (n = 7) or femoral vein (n = 24) from 31 patients aged 40–73 years-old at 1, 5 min, and 12 h, following elective PCI. Plasma sphingolipids levels were assessed by HPLC. At 1 min coronary sinus levels of sphingosine 1-phosphate (S1P), sphingosine (SPH), and sphinganine (SA) were increased by 314, 115, and 614%, respectively (n = 7), while peripheral blood levels increased by 79, 68, and 272% (n = 24). By 5 min, coronary sinus S1P and SPH levels increased further (720%, 117%), as did peripheral levels of S1P alone (792%). Where troponin T was detectable at 12 h (10 of 31), a strong correlation was found with peak S1P (R² = 0.818; P < 0.0001).

Conclusion: For the first time, we demonstrate the behavior of plasma sphingolipids following transient cardiac ischaemia in humans. The observation supports the important role of sphingolipids level as a potential novel marker of transient or prolonged myocardial ischaemia.

Bison meat has a lower atherogenic risk than beef in healthy men

The rearing method of bison and the nutrient content of the meat may make bison a healthier alternative to beef. We hypothesized that the acute and chronic effects of bison consumption, in comparison to beef, will result in a less perturbed blood lipid panel and a reduced inflammatory and oxidative stress response which will minimize the detrimental effect on vascular function. A double-blind, cross-over randomized trial was employed to examine the consequence of a single 12 oz serving (n = 14) and 7 weeks of chronic consumption (n = 10) (12 oz/d, 6 d/wk) of each meat. Measurements included blood lipids, interleukin-6, plasminogen activator inhibitor 1, C-reactive protein, oxidized low-density lipoprotein, protein carbonyl, hydroperoxides, flow-mediated dilation (FMD) and FMD/shear rate. Following a single beef meal, triglycerides and oxidized low-density lipoprotein were elevated (67% ± 45% and 18% ± 17% respectively); there was a tendency for hydroperoxides to be elevated (24% ± 37%); and FMD/shear rate was reduced significantly (30% ± 38%). Following a single meal of bison: there was a smaller increase in triglycerides (30% ± 27%), and markers of inflammation and oxidative stress and FMD/shear rate were unchanged. Chronic consumption of either meat did not influence body weight, % body fat, or blood lipids. Protein carbonyl (24% ± 45%), plasminogen activator inhibitor 1 (78% ± 126%), interleukin-6 (59% ± 76%) and C-reactive protein (72% ± 57%) were significantly elevated and FMD/shear rate was significantly reduced (19% ± 28%) following 7 weeks of beef consumption, but not bison consumption. Based on our findings, the data suggest that bison consumption results in a reduced atherogenic risk compared to beef.

Small dense LDL is more susceptible to glycation than more buoyant LDL in Type 2 diabetes

Glycation of apoB (apolipoprotein B) of LDL (low-density lipoprotein) increases its atherogenicity. Concentrations of both serum glyc-apoB (glycated apoB) and SD-LDL (small dense LDL) (syn LDL3; D=1.044-1.063 g/ml) are increased in diabetes and are closely correlated. We studied whether SD-LDL is more susceptible to glycation in vitro than more buoyant LDL in statin- and non-statin-treated Type 2 diabetes mellitus. Serum SD-LDL apoB and glyc-apoB on statins was 20±2 (means±S.D.) and 3.6±0.41 compared with 47±3 and 5.89±0.68 mg/dl in those not receiving statins (P<0.001 and <0.01, respectively). There was a dose-dependent increase in glycation on incubation of LDL subfractions with glucose, which was accompanied by an increase in LPO (lipid peroxide) and electrophoretic mobility and a decrease in free amino groups. SD-LDL was more susceptible to these changes than more buoyant LDL. Both SD-LDL and more buoyant LDL from statin-treated patients were less susceptible to glycation. There were fewer free amino groups on LDL subfractions from statin-treated patients, which may contribute to this resistance. In conclusion, greater susceptibility of SD-LDL to glycation is likely to contribute to the raised levels of circulating glyc-apoB in diabetes. Statins are associated with lower levels of both SD-LDL and glyc-apoB.

Grape consumption increases anti-inflammatory markers and upregulates peripheral nitric oxide synthase in the absence of dyslipidemias in men with metabolic syndrome

We evaluated the effects of grape consumption on inflammation and oxidation in the presence or absence of dyslipidemias in metabolic syndrome (MetS). Men with MetS (n = 24), 11 with high triglycerides and low HDL and 13 with no dyslipidemia were recruited and randomly allocated to consume daily either 46 g of lyophilized grape powder (GRAPE), equivalent to 252 g fresh grapes, or placebo with an identical macronutrient composition and caloric value as GRAPE for four weeks. After a three-week washout, participants followed the alternate treatment. We measured changes between placebo and GRAPE periods in inflammatory and oxidative stress markers both in circulation and in gene expression. Changes in plasma adiponectin (p < 0.05), interleukin (IL)-10 (p < 0.005) and in mRNA expression of the inducible isoform of nitric oxide synthase (iNOS) (p < 0.25) were increased in the GRAPE compared to the placebo period only in those individuals without dyslipidemia. Additionally, plasma IL-10 was negatively correlated with NOX2 expression, a marker of oxidative stress (r = −0.55, p < 0.01), while iNOS expression was positively correlated with the expression of superoxide dismutase 2 (r = 0.642, p < 0.01), a key anti-oxidative enzyme. Grape consumption displayed anti-oxidative and increased anti-inflammatory markers in the absence of the inflammatory milieu associated with dyslipidemias.

Flaxseed lignan complex administration in older human type 2 diabetics manages central obesity and prothrombosis-an invitation to further investigation into polypharmacy reduction

Aim. Animal and human study evidence supports the hypothesis that flaxseed lignan complex (FLC) at a dose of 600 mg secoisolariciresinol diglucoside (SDG)/day for three months would combat hyperglycaemia, dyslipidemia, blood pressure, central obesity, prothrombotic state, inflammation, and low density lipoprotein (LDL) oxidation. Methods. Sixteen type 2 diabetic patients completed this double-blind, randomised crossover placebo-controlled study. A univariate repeated measures analysis of covariance (significance P < 0.05) was followed by a mixed linear model effects analysis corrected for multiple comparisons (MCC). Results. Prior to MCC, FLC caused decreased fasting plasma glucose, A1c, inflammation (c-reactive protein (CRP) and interleukin-6 (IL-6)), and increased bleeding time. After correction for multiple comparisons, FLC induced a statistically significant increase in bleeding time and smaller waist circumference gain. No treatment effect occurred in the other variables before or after adjustment. Conclusions. It is concluded that FLC significantly increased bleeding time thus reducing the prothrombotic state, reduced central obesity gain as measured by waist circumference, and did not affect significantly the other dependent variables measured after adjustment for multiple comparisons. These findings, not yet published in human type 2 diabetes, suggest that this FLC dose over at least three months, may, subject to further investigation, reduce polypharmacy.

Impaired thymic export and increased apoptosis account for regulatory T cell defects in patients with non-ST segment elevation acute coronary syndrome

Regulatory T (Treg) cells play a protective role against the development of atherosclerosis. Previous studies have revealed Treg cell defects in patients with non-ST elevation acute coronary syndrome (NSTACS), but the mechanisms underlying these defects remain unclear. In this study, we found that the numbers of peripheral blood CD4(+)CD25(+)CD127(low) Treg cells and CD4(+)CD25(+)CD127(low)CD45RA(+)CD45RO(-) naive Treg cells were lower in the NSTACS patients than in the chronic stable angina (CSA) and the chest pain syndrome (CPS) patients. However, the number of CD4(+)CD25(+)CD127(low)CD45RA(-)CD45RO(+) memory Treg cells was comparable in all of the groups. The frequency of CD4(+)CD25(+)CD127(low)CD45RO(-)CD45RA(+)CD31(+) recent thymic emigrant Treg cells and the T cell receptor excision circle content of purified Treg cells were lower in the NSTACS patients than in the CSA patients and the CPS controls. The spontaneous apoptosis of Treg cells (defined as CD4(+)CD25(+)CD127(low)annexin V(+)7-AAD(-)) was increased in the NSTACS patients compared with the CSA and CPS groups. Furthermore, oxidized LDL could induce Treg cell apoptosis, and the oxidized LDL levels were significantly higher in the NSTACS patients than in the CSA and CPS groups. In accordance with the altered Treg cell levels, the concentration of TNF-α was increased in the NSTACS patients, resulting in a decreased IL-10/TNF-α ratio. These findings indicate that the impaired thymic output of Treg cells and their enhanced susceptibility to apoptosis in the periphery were responsible for Treg cell defects observed in the NSTACS patients.

Serum oxidized low-density lipoprotein level and risk of cognitive impairment in older women

We investigated the association between serum level of oxidized low-density lipoprotein (oxLDL) and risk of cognitive impairment (dementia or mild cognitive impairment) among 572 nondemented community-dwelling women from a prospective cohort study of aging. After 5 years of follow-up, 228 (39.9%) developed cognitive impairment; and this did not differ by tertile of baseline oxLDL level (highest compared with lowest tertile 38.2% vs. 39.5%; odds ratio, 0.90; 95% confidence interval, 0.63-1.43). Multivariate adjustment produced similar results (odds ratio, 0.91; 95% confidence interval, 0.60-1.39). These findings suggest that increased levels of serum oxLDL are not associated with a greater risk of incident cognitive impairment in older women.

Decrease of miR-146b-5p in monocytes during obesity is associated with loss of the anti-inflammatory but not insulin signaling action of adiponectin

Background

Low adiponectin, a well-recognized antidiabetic adipokine, has been associated with obesity-related inflammation, oxidative stress and insulin resistance. Globular adiponectin is an important regulator of the interleukin-1 receptor-associated kinase (IRAK)/NFκB pathway in monocytes of obese subjects. It protects against inflammation and oxidative stress by inducing IRAK3. microRNA (miR)-146b-5p inhibits NFκB-mediated inflammation by targeted repression of IRAK1 and TNF receptor-associated factor-6 (TRAF6). Therefore, we measured the expression of miR-146b-5p in monocytes of obese subjects. Because it was low we determined the involvement of this miR in the anti-inflammatory, antioxidative and insulin signaling action of globular adiponectin.

Methods

miR-146b-5p expression in monocytes of obese subjects was determined by qRT-PCR. The effect of miR-146b-5p silencing on molecular markers of inflammation, oxidative stress and insulin signaling and the association with globular adiponectin was assessed in human THP-1 monocytes.

Results

miR-146b-5p was downregulated in monocytes of obese persons. Low globular adiponectin decreased miR-146b-5p and IRAK3 in THP-1 monocytes, associated with increased mitochondrial reactive oxygen species (ROS). Intracellular ROS and insulin receptor substrate-1 (IRS1) protein were unchanged. Silencing of miR-146b-5p with an antisense inhibitor resulted in increased expression of IRAK1 and TRAF6 leading to more NFκB p65 DNA binding activity and TNFα. As a response IRAK3 and IRS1 protein increased. Mitochondrial and intracellular ROS production did not increase despite more inflammation. In addition, exposure of miR-146b-5p-depleted THP-1 monocytes to high levels of globular adiponectin resulted in an increased production of TNFα and intracellular ROS. Still, they did not lose their potential to increase IRAK3 and IRS1 protein and to decrease mitochondrial ROS.

Conclusion

miR-146b-5p, decreased in monocytes during obesity, is a major mediator of the anti-inflammatory action of globular adiponectin. It appears not to be involved in insulin signaling possibly by protective response of IRAK3 and lack of mitochondrial ROS production.

Interleukin-1 receptor-associated kinase-3 is a key inhibitor of inflammation in obesity and metabolic syndrome

Background

Visceral obesity is associated with the rising incidence of type 2 diabetes and metabolic syndrome. Low-grade chronic inflammation and oxidative stress synergize in obesity and obesity-induced disorders.

Objective

We searched a cluster of molecules that support interactions between these stress conditions in monocytes.

Methods

RNA expressions in blood monocytes of two independent cohorts comprising 21 and 102 obese persons and 46 age-matched controls were determined by microarray and independently validated by quantitative RT-PCR analysis. The effect of three-month weight loss after bariatric surgery was determined. The effect of RNA silencing on inflammation and oxidative stress was studied in human monocytic THP-1 cells.

Results

Interleukin-1 receptor-associated kinase-3 (IRAK3), key inhibitor of IRAK/NFκB-mediated chronic inflammation, is downregulated in monocytes of obese persons. Low IRAK3 was associated with high superoxide dismutase-2 (SOD2), a marker of mitochondrial oxidative stress. A comparable expression profile was also detected in visceral adipose tissue of the same obese subjects. Low IRAK3 and high SOD2 was associated with a high prevalence of metabolic syndrome (odds ratio: 9.3; sensitivity: 91%; specificity: 77%). By comparison, the odds ratio of high-sensitivity C-reactive protein, a widely used marker of systemic inflammation, was 4.3 (sensitivity: 69%; specificity: 66%). Weight loss was associated with an increase in IRAK3 and a decrease in SOD2, in association with a lowering of systemic inflammation and a decreasing number of metabolic syndrome components. We identified the increase in reactive oxygen species in combination with obesity-associated low adiponectin and high glucose and interleukin-6 as cause of the decrease in IRAK3 in THP-1 cells in vitro.

Conclusion

IRAK3 is a key inhibitor of inflammation in association with obesity and metabolic syndrome. Our data warrant further evaluation of IRAK3 as a diagnostic and prognostic marker, and as a target for intervention.

Myeloperoxidase is associated with incident coronary heart disease independently of traditional risk factors: results from the MONICA/KORA Augsburg study

AIMS

Oxidative stress plays a critical role in the initiation and progression of atherosclerosis. Myeloperoxidase (MPO) is a marker of oxidative stress. We prospectively investigated whether an increased serum concentration of MPO is associated with an increased risk of incident coronary heart disease (CHD).

METHODS

We conducted a population-based case-cohort study in middle-aged, healthy men and women within the MONICA/KORA Augsburg studies. Serum levels of MPO were measured in 333 subjects with (cases) and 1727 without (noncases) incident CHD. Mean follow-up time was 10.8 ± 4.6 years.

RESULTS

Baseline concentrations of MPO were higher in cases compared with noncases (P ≤ 0.001 in men; P=0.131 in women). After adjustment for major cardiovascular risk factors, the hazard ratio (HR) with 95% confidence interval (CI) comparing the top with the two lower tertiles was 1.70 (95% CI, 1.25-2.30). After additional adjustment for markers of inflammation and endothelial dysfunction, the association was attenuated (HR 1.50; 95% CI, 1.08-2.09). There were no significant interactions of MPO with sex or increased weight on CHD risk.

CONCLUSIONS

Elevated concentrations of the oxidative stress marker MPO were independently associated with increased risk of incident CHD. This finding deserves detailed evaluation in further studies.

Vitamin C and fibre consumption from fruits and vegetables improves oxidative stress markers in healthy young adults

The aim of the present cross-sectional study was to assess the potential relationships between fruit and vegetable (FV) consumption and some oxidative stress markers in young adults, with particular emphasis on fibre and vitamin C intake. The study enrolled 246 healthy subjects (eighty-eight men and 158 women), with a mean age of 22 (sd 3) years and a mean BMI of 21·9 (sd 2·8) kg/m2. Dietary intake, anthropometry, blood pressure, lifestyle features and blood biochemical data were assessed with validated procedures. Those subjects in the highest tertile (T) of FV consumption ( ≥ 705 g/d) had statistically lower oxidised LDL (ox-LDL) concentrations as well as higher plasma total antioxidant capacity (TAC) and glutathione peroxidase (GPx) activity (P for trend <0·05), after adjusting for sex, age, energy intake, physical activity, smoking, BMI, vitamin supplement use and other confounding factors. Moreover, plasma ox-LDL concentrations showed a decreasing trend and TAC an increasing trend across tertiles of fibre (T3: ≥14 g/d) and vitamin C (T3: ≥150 mg/d) from FV intake, while GPx activity was positively associated with vitamin C intake (P for trend < 0·05). In conclusion, greater FV consumption was independently associated with reduced ox-LDL as well as increased TAC and GPx activity in healthy young adults, with dietary fibre and vitamin C from FV clearly being implicated in this beneficial relationship.

Dietary total antioxidant capacity is inversely related to central adiposity as well as to metabolic and oxidative stress markers in healthy young adults

Background

Dietary total antioxidant capacity (TAC) has been assumed as a useful tool to assess the relationship between the cumulative antioxidant food capacity and several chronic disorders. The aim of this cross-sectional study was to investigate the potential relationships of dietary TAC with adiposity, metabolic and oxidative stress markers in healthy young adults.

Methods

This study enrolled 266 healthy subjects (105 men/ 161 women; 22 ± 3 years-old; 22.0 ± 2.7 kg/m²). Dietary intake, anthropometry, blood pressure, lifestyle features, and biochemical data were assessed with validated procedures.

Results

In linear regression analyses, dietary TAC values were inversely associated with glycemia, total cholesterol:HDL-c ratio, triglycerides and oxidized-LDL concentrations, and positively associated with HDL-c concentrations, independently of gender, age, smoking status, physical activity, vitamin use supplement, waist circumference, energy intake, fatty acid intake. In addition, plasma TAC was negatively correlated with ox-LDL concentrations (r= -0.20, P = 0.003), independently of the assessed confounding variables. Finally, dietary TAC values were inversely related to waist circumference values (r= -0.17, P = 0.005) as well as to lower mild central obesity occurrence (waist circumference ≥ 80/ 94 cm for women/ men, respectively).

Conclusion

Dietary TAC values are inversely associated with glucose and lipid biomarkers as well as with central adiposity measurements in healthy young adults, indicating dietary TAC as a useful tool to assess the health benefits of cumulative antioxidant capacity from food intake. In addition, the independent and inverse relationships of ox-LDL concentrations with dietary and plasma TAC respectively suggest a putative role of antioxidant rich-diet in the link between redox state and atherogenesis at early stage.

Oxidized LDL and the Risk of Coronary Heart Disease: Results from the MONICA/KORA Augsburg Study

BACKGROUND

Oxidative stress plays a critical role in the initiation and progression of atherosclerosis. Oxidized LDL (oxLDL) is a marker of oxidative stress. We prospectively investigated whether increased serum oxLDL concentrations are associated with incident coronary heart disease (CHD).

METHODS

We conducted a prospective population-based case–cohort study within the MONICA/KORA Augsburg studies. Serum oxLDL concentrations were measured in 333 case individuals with incident CHD and in 1727 noncase individuals selected from a source population of 9300 middle-aged, healthy men and women. The mean (SD) follow-up time was 10.8 (4.6) years.

RESULTS

Baseline oxLDL concentrations were higher in case individuals than in noncase individuals (P &lt; 0.001). After adjustment for age, sex, survey, smoking status, systolic blood pressure, physical activity, diabetes, body mass index, parental history of myocardial infarction, and alcohol consumption, the hazard ratio (HR) for comparing the first and third tertiles was 1.87 (95% CI, 1.33–2.64; P &lt; 0.001). Additional adjustment for lipid parameters, inflammatory markers, and markers of endothelial dysfunction attenuated the association (HR, 1.29; 95% CI, 0.88–1.89; P = 0.087). We observed no significant interactions between oxLDL and sex or being overweight.

CONCLUSIONS

Increased oxLDL concentrations were associated with an increased risk for incident CHD. Nevertheless, because this effect became nonsignificant after adjustment for covariates, particularly the ratio of total cholesterol to HDL cholesterol, it may be mediated primarily by lipid parameters. Further studies are warranted to clarify this issue.

Laboratory reproducibility of biochemical markers of bone turnover in clinical practice

SUMMARY

To determine the laboratory reproducibility of urine N-telopeptide and serum bone-specific alkaline phosphatase measurements, we sent identical specimens to six US commercial labs over an 8-month period. Longitudinal and within-run laboratory reproducibility varied substantially. Efforts to improve the reproducibility of these tests are needed.

INTRODUCTION

We assessed the laboratory reproducibility of urine N-telopeptide (NTX) and serum bone-specific alkaline phosphatase (BAP).

METHODS

Serum and urine were collected from five postmenopausal women, pooled, divided into identical aliquots, and frozen. To evaluate longitudinal reproducibility, identical specimens were sent to six US commercial labs on five dates over an 8-month period. To evaluate within-run reproducibility, on the fifth date, each lab was sent five identical specimens. Labs were unaware of the investigation.

RESULTS

Longitudinal coefficients of variation (CVs) ranged from 5.4% to 37.6% for NTX and from 3.1% to 23.6% for BAP. Within-run CVs ranged from 1.5% to 17.2% for NTX. Compared to the Osteomark NTX assay, the Vitros ECi NTX assay had significantly higher longitudinal reproducibility (mean CV 7.2% vs. 30.3%, p < 0.0005) and within-run reproducibility (mean CV 3.5% vs. 12.7%, p < 0.0005).

CONCLUSIONS

Reproducibility of urine NTX and serum BAP varies substantially across US labs.

Increased PAFAH and Oxidized Lipids Are Associated With Inflammation and Atherosclerosis in Hypercholesterolemic Pigs

Objective— To study the association of PAF-acetyl hydrolase (PAFAH) activity with inflammation, oxidative stress, and atherosclerosis in hypercholesterolemic swine.

Methods and Results— Cholesterol-rich diet feeding of miniature pigs was associated with an increase in PAFAH activity and an increase of the PAFAH to PON1 ratio. PLA2G7 RNA (coding for PAFAH) expression was increased in blood monocytes and plaque macrophages. Increased PAFAH activity was associated with higher plasma lysophosphatidylcholine and correlated with oxidized LDL. In THP1 monocytes and macrophages and in human blood-derived macrophages, oxidized LDL induced PLA2G7 RNA expression. Atherogenic diet feeding induced the accumulation of macrophages and oxidized LDL in the arterial wall leading to atherosclerosis. PAFAH activity correlated positively with plaque size and TNFalpha expression in plaque macrophages.

Conclusions— We demonstrated that an increase in PAFAH activity was associated with increased levels of lysophosphatidylcholine, oxidized LDL, and inflammation, resulting in accelerated atherosclerosis in hypercholesterolemic minipigs. The significant correlation between PLA2G7 RNA expression in plaque macrophages and plasma PAFAH activity suggests that the latter is a consequence, rather than a cause of macrophage accumulation. Our cell experiments suggest that oxidized LDL can induce PAFAH, resulting in accumulation of lysophosphatidylcholine that increases the inflammatory action of oxidized LDL.

Association between oxidized LDL, obesity and type 2 diabetes in a population-based cohort, the Health, Aging and Body Composition Study

BACKGROUND

Accumulating evidence suggests a cross-sectional association between oxidative stress and type 2 diabetes (T2D). Systemic oxidative stress, as measured by oxidized LDL (oxLDL), has been correlated with visceral fat. We examined the relationship between oxLDL, and T2D- and obesity-related traits in a bi-racial sample of 2985 subjects at baseline and after 7 years of follow-up.

METHODS

We examined six T2D-related traits (T2D status, HbA(1c), fasting glucose, insulin, adiponectin and HOMA-IR) as well as six obesity-related traits (obesity status, BMI, leptin, % body fat, visceral and subcutaneous fat mass) using logistic and linear regression models.

RESULTS

In all subjects at baseline, oxLDL was positively associated with T2D (OR = 1.3, 95% CI:1.1-1.5), fasting glucose (ss = 0.03 +/- 0.006), HbA(1c) (ss = 0.02 +/- 0.004), fasting insulin (ss = 0.12 +/- 0.02), HOMA-IR (ss = 0.13 +/- 0.02) and negatively with adiponectin (ss = -0.16 +/- 0.03), (all p < 0.001). The strength and magnitude of these associations did not differ much between blacks and whites. In both blacks and whites, oxLDL was also associated with obesity (OR = 1.3, 95% CI:1.1-1.4) and three of its related traits (ss = 0.60 +/- 0.14 for BMI, ss = 0.74 +/- 0.17 for % body fat, ss = 0.29 +/- 0.06 for visceral fat; all p < 0.001). Furthermore, of four traits measured after 7 years of follow-up (fasting glucose, HbA1c, BMI and % fat), their relationship with oxLDL was similar to baseline observations. No significant association was found between oxLDL and incident T2D. Interestingly, oxLDL was significantly associated with % change in T2D- and obesity-related traits in whites but not in blacks.

CONCLUSION/INTERPRETATION

Our data suggest that systemic oxidative stress may be a novel risk factor for T2D and obesity.

Oxidative stress and insulin resistance: the coronary artery risk development in young adults study

OBJECTIVE

Although cumulative evidence suggests that increased oxidative stress may lead to insulin resistance in vivo or in vitro, community-based studies are scarce. This study examined the longitudinal relationships of oxidative stress biomarkers with the development of insulin resistance and whether these relationships were independent of obesity in nondiabetic young adults.

RESEARCH DESIGN AND METHODS

Biomarkers of oxidative stress (F(2)-isoprostanes [F(2)Isop] and oxidized LDL [oxLDL]), insulin resistance (the homeostasis model assessment of insulin resistance [HOMA-IR]), and various fatness measures (BMI, waist circumference, and estimated percent fat) were obtained in a population-based observational study (Coronary Artery Risk Development in Young Adults) and its ancillary study (Young Adult Longitudinal Trends in Antioxidants) during 2000-2006.

RESULTS

There were substantial increases in estimated mean HOMA-IR over time. OxLDL and F(2)Isop showed little association with each other. Mean evolving HOMA-IR increased with increasing levels of oxidative stress markers (P < 0.001 for oxLDL and P = 0.06 for F(2)Isop), measured in 2000-2001. After additional adjustment for adiposity, a positive association between oxLDL and HOMA-IR was strongly evident, whereas the association between F(2)Isop and HOMA-IR was not.

CONCLUSIONS

We observed positive associations between each of two oxidative stress markers and insulin resistance. The association with oxidized LDL was independent of obesity, but that with F(2)Isop was not.

Oxidized LDL modulates apoptosis of regulatory T cells in patients with ESRD

Increased levels of oxidized low-density lipoproteins (oxLDL) contribute to the increased risk for atherosclerosis, which persists even after adjusting for traditional risk factors, among patients with ESRD. Regulatory T cells (CD4+/CD25+ Tregs), which down-regulate T cell responses to foreign and self-antigens, are protective in murine atherogenesis, but whether similar immunoregulation occurs in humans with ESRD is unknown. Because cellular defense systems against oxLDL involve proteolytic degradation, the authors investigated the role of oxLDL on proteasome activity of CD4+/CD25+ Tregs in patients with ESRD. CD4+/CD25+ Tregs isolated from uremic patients' peripheral blood, especially that of chronically hemodialyzed patients, failed to suppress cell proliferation, exhibited cell-cycle arrest, and entered apoptosis by altering proteasome activity. Treating CD4+/CD25+ Tregs with oxLDL or uremic serum ex vivo decreased the number and suppressive capacity of CD4+/CD25+ Tregs. In vitro, oxLDL promoted the accumulation of p27Kip1, the cyclin-dependent kinase inhibitor responsible for G1 cell cycle arrest, and increased apoptosis in a time- and concentration-dependent manner. In summary, proteasome inhibition by oxLDL leads to cell cycle arrest and apoptosis, dramatically affecting the number and suppressive capacity of CD4+/CD25+ Tregs in chronically hemodialyzed patients. This response may contribute to the immune dysfunction, microinflammation, and atherogenesis observed in patients with ESRD.

Relationship of lipoprotein-associated phospholipase A2 and oxidized low density lipoprotein in carotid atherosclerosis

Plasma levels of lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) and oxidized low density lipoprotein (oxLDL) have been identified as risk factors for cardiovascular disease. Lp-PLA(2) is the sole enzyme responsible for the hydrolysis of oxidized phospholipids on LDL particles in atherosclerotic plaques. We have studied the relationship between Lp-PLA(2) and oxLDL in carotid endarterectomy (CEA) tissues and in matched plasmas. In extracts from CEA anatomical segments, the levels of oxLDL were significantly associated with the levels of Lp-PLA(2) protein (r = 0.497) and activity (r = 0.615). OxLDL and Lp-PLA(2) mass/activity were most abundant in the carotid bifurcation and internal segments where plaque was most abundant. In extracts from CEA atheroma, the levels of oxLDL and Lp-PLA(2) were significantly correlated (r = 0.634). In matched plasma and atheroma extracts, the levels of Lp-PLA(2) were negatively correlated (r = - 0.578). The ratio of Lp-PLA(2) to oxLDL was higher in atheromatous tissue (277:1) than in normal tissue (135:1) and plasma (13:1). Immunohistochemical experiments indicated that in plaques, oxLDL and Lp-PLA(2) existed in overlapping but distinctly different distribution. Fluorescence microscopy showed both oxLDL and Lp-PLA(2) epitopes on the same LDL particle in plasma but not in plaque. These results suggest that the relationship between Lp-PLA(2) and oxLDL in the atherosclerotic plaque is different from that in the plasma compartment.