Inverse relationship between circulating oxidized low density lipoprotein (oxLDL) and anti-oxLDL antibody levels in healthy subjects

Positive Association between Autoantibodies Against Oxidized LDL and HDL-C: A Novel Mechanism for HDL Cardioprotection?

BACKGROUND

In the atherosclerotic plaque microenvironment, oxidized phospholipids expressed in the oxidized low-density lipoprotein (oxLDL) surface bind to scavenger receptors of macrophages eliciting foam cell formation and plaque progression. Auto-antibodies against oxLDL (oxLDL-Ab) interact with oxidative epitopes leading to the formation of immune complexes that are unable to interact with macrophage receptors, thus abrogating atherogenesis. Release of oxLDL-Ab by B cells involves interleukin 5 and Th2 response, which in turn are potentiated by HDL. Thereby, we hypothesized that individuals with higher levels of HDL-C may plausibly display elevated titers of oxLDL-Ab.

OBJECTIVE

To evaluate the relationship between HDL-C and oxLDL-Ab levels.

METHODS

Asymptomatic individuals (n = 193) were grouped according to their HDL-C concentration to one of three categories: low (< 68 mg/dL), intermediate (68 to 80 mg/dL) or high (> 80 mg/dL). P values < 0.05 were considered statistically significant.

RESULTS

Our analysis included 193 individuals (mean age: 47 years; male: 26.3%). Compared to individuals in the lowest HDL-C tertile, those in the highest tertile were older (36 versus 53 years; p = 0.001) and less frequently male (42.6% versus 20.9%; p = 0.001). Mean values of oxLDL-Ab increased as the HDL-C group escalated (0.31, 0.33 and 0.43 units, respectively; p = 0.001 for trend). Simple linear regression found a significant, positive relationship between the independent variable, HDL-C, and the dependent variable, oxLDL-Ab (R = 0.293; p = 0.009). This relation remained significant (R = 0.30; p = 0.044), after adjustment by covariates. Apolipoprotein AI levels were also related to oxLDL-Ab in both simple and adjusted linear regression models.

CONCLUSION

HDL-C and oxLDL-Ab are independently related.

Hepatitis C Virus Clearance by Direct-Acting Antivirals Agents Improves Endothelial Dysfunction and Subclinical Atherosclerosis: HEPCAR Study

INTRODUCTION

Hepatitis C virus (HCV) infection has been related to increased cardiovascular (CV) risk. The aim of this study was to analyze the impact of sustained virological response (SVR) on endothelial dysfunction and subclinical atherosclerosis in patients with hepatitis C virus treated with direct-acting antiviral agents.

METHODS

A total of 114 patients were prospectively recruited and underwent CV risk assessment including (i) endothelial dysfunction determined through laser Doppler flowmetry and (ii) subclinical atherosclerosis, elucidated by the ankle-brachial index (ABI). Atherogenic lipid profile (total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides); markers of oxidative stress (oxidized low-density lipoprotein antibodies [OLAbs]), soluble markers of adhesion (vascular cell adhesion molecule [VCAM], e-selectin, and soluble markers of angiogenesis; and vascular endothelial growth factor, endothelial [EMPs] and platelet [PMPs] apoptotic microparticles, and cell-free DNA [cfDNA]) were measured. All determinations were performed at baseline, 12 weeks (SVR time), and 1 year after treatment.

RESULTS

In patients with endothelial dysfunction, area of hyperemia improved after virus clearance (P = 0.013) and was related to significant decrease in VCAM, e-selectin (P < 0.001), and cfDNA (P = 0.017) and to increased OLAb levels (P = 0.001). In patients with subclinical atherosclerosis at baseline, a significantly improved ABI was seen after HCV clearance (P < 0.001). Levels of both EMPs and PMPs also decreased after SVR and at follow-up (P = 0.006 and P = 0.002, respectively).

DISCUSSION

HCV clearance improved not only liver function but also endothelial dysfunction and subclinical atherosclerosis promoted by decrease in levels of VCAM, e-selectin, cfDNA, and PMPs and EMPs.

Lipid Peroxidation in Atherosclerotic Cardiovascular Diseases

Significance: Atherosclerotic cardiovascular diseases (ACVDs) continue to be a primary cause of mortality worldwide in adults aged 35-70 years, occurring more often in countries with lower economic development, and they constitute an ever-growing global burden that has a considerable socioeconomic impact on society. The ACVDs encompass diverse pathologies such as coronary artery disease and heart failure (HF), among others. Recent Advances: It is known that oxidative stress plays a relevant role in ACVDs and some of its effects are mediated by lipid oxidation. In particular, lipid peroxidation (LPO) is a process under which oxidants such as reactive oxygen species attack unsaturated lipids, generating a wide array of oxidation products. These molecules can interact with circulating lipoproteins, to diffuse inside the cell and even to cross biological membranes, modifying target nucleophilic sites within biomolecules such as DNA, lipids, and proteins, and resulting in a plethora of biological effects. Critical Issues: This review summarizes the evidence of the effect of LPO in the development and progression of atherosclerosis-based diseases, HF, and other cardiovascular diseases, highlighting the role of protein adduct formation. Moreover, potential therapeutic strategies targeted at lipoxidation in ACVDs are also discussed. Future Directions: The identification of valid biomarkers for the detection of lipoxidation products and adducts may provide insights into the improvement of the cardiovascular risk stratification of patients and the development of therapeutic strategies against the oxidative effects that can then be applied within a clinical setting.

The Effect of a 13-Valent Conjugate Pneumococcal Vaccine on Circulating Antibodies Against Oxidized LDL and Phosphorylcholine in Man, A Randomized Placebo-Controlled Clinical Trial

Simple Summary

Atherosclerosis is the main underlying mechanism for cardiovascular disease. The main cause for atherosclerosis development is oxidized low density lipoprotein (oxLDL) accumulation in the vessel wall and a subsequent immune response. It has been established that immunoglobulin M antibodies against oxLDL help protect against atherosclerosis. It has been found in mice that vaccination with Streptococcus pneumoniae results in an increase of these protective antibodies and thereby decreases the development of atherosclerosis. In this study, we investigated if this increase of antibodies can be found in human as well. Twenty-four healthy male volunteers were vaccinated with Prevenar-13, a pneumococcal vaccine, using different dosing regimens. An increase in anti-Prevenar antibodies was found, showing that the vaccination worked. However, no increase in protective anti-phosphorylcholine or anti-oxLDL antibodies was observed. This work shows that vaccination against pneumococcal does not seem to be a suitable treatment option to help prevent atherosclerosis development, although further research would be required to test alternative pneumococcal-based vaccines, vaccination regimens or study populations.

Abstract

In mice vaccination with Streptococcus pneumoniae results in an increase in anti-oxLDL IgM antibodies due to mimicry of anti-phosphorylcholine (present in the cell wall of S. pneumoniae) and anti-oxLDL IgM. In this study we investigated the human translation of this molecular mimicry by vaccination against S. pneumoniae using the Prevenar-13 vaccine. Twenty-four healthy male volunteers were vaccinated with Prevenar-13, either three times, twice or once in a double-blind, placebo-controlled, randomized single center clinical study. Anti-pneumococcal wall, oxLDL and phosphorycholine antibody levels were measured at a fixed serum dilution, as well as circulating lipid levels over the course of 68 weeks. A significant increase in anti-oxLDL IgG and IgM was seen in the group receiving two doses six months apart compared to the placebo. However, these differences were not observed in the groups receiving a single dose, two doses one month apart, or three doses. This study shows that vaccination with Prevenar-13 does not result in robust anti-oxLDL IgM levels in humans. Further research would be required to test alternative pneumococcal-based vaccines, vaccination regimens or study populations, such as cardiovascular disease patients.

Targeted anti-inflammatory therapy is a new insight for reducing cardiovascular events: A review from physiology to the clinic

Despite considerable progressions, cardiovascular disease (CVD) is still one of the major causes of mortality around the world, indicates an important and unmet clinical need. Recently, extensive studies have been performed on the role of inflammatory factors as either a major or surrogate factor in the pathophysiology of CVD. Epidemiological observations suggest the theory of the role of inflammatory mediators in the development of cardiovascular events. This may support the idea that targeted anti-inflammatory therapies, on the background of traditional validated medical therapies, can play a significant role in prevention and even reduction of cardiovascular disorders. Many randomized controlled trials have shown that drugs commonly useful for primary and secondary prevention of CVD have an anti-inflammatory mechanism. Further, many anti-inflammatory drugs are being examined because of their potential to reduce the risk of cardiovascular problems. In this study, we review the process of inflammation in the development of cardiovascular events, both in vivo and clinical evidence in immunotherapy for CVD.

Low-Density Lipoprotein-Reactive T Cells Regulate Plasma Cholesterol Levels and Development of Atherosclerosis in Humanized Hypercholesterolemic Mice

Supplemental Digital Content is available in the text.

Background:

Atherosclerotic cardiovascular disease is a chronic inflammatory process initiated when cholesterol-carrying low-density lipoprotein (LDL) is retained in the arterial wall. CD4⁺ T cells, some of which recognize peptide components of LDL as antigen, are recruited to the forming lesion, resulting in T-cell activation. Although these T cells are thought to be proatherogenic, LDL immunization reduces disease in experimental animals. These seemingly contradictory findings have hampered the development of immune-based cardiovascular therapy. The present study was designed to clarify how activation of LDL-reactive T cells impacts on metabolism and vascular pathobiology.

Methods:

We have developed a T-cell receptor–transgenic mouse model to characterize the effects of immune reactions against LDL. Through adoptive cell transfers and cross-breeding to hypercholesterolemic mice expressing the antigenic human LDL protein apolipoprotein B-100, we evaluate the effects on atherosclerosis.

Results:

A subpopulation of LDL-reactive T cells survived clonal selection in the thymus, developed into T follicular helper cells in lymphoid tissues on antigen recognition, and promoted B-cell activation. This led to production of anti-LDL immunoglobulin G antibodies that enhanced LDL clearance through immune complex formation. Furthermore, the cellular immune response to LDL was associated with increased cholesterol excretion in feces and with reduced vascular inflammation.

Conclusions:

These data show that anti-LDL immunoreactivity evokes 3 atheroprotective mechanisms: antibody-dependent LDL clearance, increased cholesterol excretion, and reduced vascular inflammation.

The Significance of Oxidized Low-Density Lipoprotein in Body Fluids as a Marker Related to Diseased Conditions

Oxidatively modified low-density lipoprotein (oxLDL) is known to be involved in various diseases, including cardiovascular diseases. The presence of oxLDL in the human circulatory system and in atherosclerotic lesions has been demonstrated using monoclonal antibodies. Studies have shown the significance of circulating oxLDL in various systemic diseases, including acute myocardial infarction and diabetic mellitus. Several different enzyme-linked immunosorbent assay (ELISA) procedures to measure oxLDL were utilized. Evidence has been accumulating that reveals changes in oxLDL levels under certain pathological conditions. Since oxLDL concentration tends to correlate with low-density lipoprotein (LDL)-cholesterol, the ratio of ox-LDL and LDL rather than oxLDL concentration alone has also been focused. In addition to circulating plasma, LDL and oxLDL are found in gingival crevicular fluid (GCF), where the ratio of oxLDL to LDL in GCF is much higher than in plasma. LDL and oxLDL levels in GCF show an increase in diabetic patients and periodontal patients, suggesting that GCF might be useful in examining systemic conditions. GCF oxLDL increased when the teeth were affected by periodontitis. It is likely that oxLDL levels in plasma and GCF could reflect oxidative stress and transfer efficacy in the circulatory system.

The effect of exenatide (a GLP-1 analog) and sitagliptin (a DPP-4 inhibitor) on plasma platelet-activating factor acetylhydrolase (PAF-AH) activity and concentration in normal and fructose-fed rats

Inflammation and oxidative stress are the two processes crucial in atherogenesis. Platelet-activating factor acetylhydrolase (PAF-AH), a plasma lipoprotein-associated enzyme, degrades pro-inflammatory lipids generated within oxidatively modified lipoproteins. Extensive evidence shows that incretin-based drugs, a new class of anti-diabetic agents, can provide cardiovascular protection that cannot be attributed to their glucose-lowering effects. The present study was undertaken to determine whether the antiatherogenic effects of the GLP-1(glucagon-like peptide-1) receptor agonist (exenatide) and DPP-4(dipeptidyl peptidase-4) inhibitors (sitagliptin) may occur via the regulation of platelet-activating factor acetylhydrolase (PAF-AH) activity/mass and inhibition of low-density lipoprotein (LDL) oxidation in the fructose-fed rats. Normal and fructose-fed rats (8 wk) were treated (4 wk) with sitagliptin (5 and 10 mg/kg p.o.) or with exenatide (5 and 10 µg/kg, s.c.). Plasma PAF-AH activity and phosphatidylcholine (PC) concentration were measured colorimetrically. Plasma PAF-AH concentration, oxidized LDL (oxLDL), hexanoyl-Lys adduct (HEL), lyso-PC, apolipoprotein A-I (apoA-I), apoB, platelet-activating factor (PAF), monocyte chemoattractant protein-1 (MCP-1) and endothelin-1 (ET-1) were measured by ELISA. The four-week exenatide (5 µg/kg, sc.) treatment of fructose fed-rats significantly increased plasma PAF-AH activity (+33%, P < 0.001) and decreased the level of circulating oxLDL (-42%, P < 0.05) and MCP-1 (-23%, P < 0.01). These changes were accompanied by the decrease in plasma PC/lyso-PC (-47%, P < 0.001) and apoB/apoA-I ratio (-75%, P < 0.001). The effect of exenatide on enzyme activity was associated with only a minor effect on metabolic parameters and was independent of weight reduction. Exenatide but not sitagliptin inhibits oxidative modification of LDL probably due to favorable effect on plasma PAF-AH activity.

Circulating Oxidized Low-Density Lipoprotein is a Strong Risk Factor for the Early Stage of Coronary Heart Disease

This study aimed to detect the circulating oxidized low-density lipoprotein (ox-LDL) levels of controls and patients with stable angina pectoris (SAP), unstable angina pectoris (UAP), and acute myocardial infarction (AMI) and also to investigate the correlation with the severity of coronary heart disease (CHD). Plasma levels of circulating ox-LDL-4E6, malondialdehyde (MDA), high-sensitivity C-reactive protein (hs-CRP), total cholesterol, high-density lipoprotein cholesterol, LDL cholesterol, apoprotein A, apoprotein B, and lipoprotein (a) (Lp(a)) were measured in 99 participants who underwent coronary angiography. The plasma ox-LDL level was significantly higher in patients with CHD than in controls (P = 0.000). However, it was lower in the UAP and AMI groups than in the SAP group (P = 0.000). The lipid peroxide level (MDA) showed a significant difference among all groups (P = 0.000). It increased significantly in patients with CHD. The Lp(a) and hs-CRP levels were significantly higher in patients with CHD (P = 0.000 and 0.000, respectively). No difference in Lp(a) was found among the SAP, UAP, and AMI groups (P = 0.296). In patients with CHD, the plasma ox-LDL correlated negatively with hs-CRP (P = 0.011), and serum MDA correlated positively with hs-CRP (P = 0.004). The plasma ox-LDL could be used as a strong risk factor for the early stage but not the advanced stage of CHD. Hs-CRP may bound and transfer ox-LDL to macrophages. © 2018 IUBMB Life, 71(1):277-282, 2019.

Anionic 1,2-distearoyl-sn-glycero-3-phosphoglycerol (DSPG) liposomes induce antigen-specific regulatory T cells and prevent atherosclerosis in mice

Atherosclerosis is the predominant underlying pathology of many types of cardiovascular disease and is one of the leading causes of death worldwide. It is characterized by the retention of oxidized low-density lipoprotein (ox-LDL) in lipid-rich macrophages (foam cells) in the intima of arteries. Autoantigens derived from oxLDL can be used to vaccinate against atherosclerosis. However, a major challenge is the induction of antigen-specific Tregs in a safe and effective way. Here we report that liposomes containing the anionic phospholipid 1,2-distearoyl-sn-glycero-3-phosphoglycerol (DSPG) induce Tregs that are specific for the liposomes' cargo. Mechanistically, we show a crucial role for the protein corona that forms on the liposomes in the circulation, as uptake of DSPG-liposomes by antigen-presenting cells is mediated via complement component 1q (C1q) and scavenger receptors (SRs). Vaccination of atherosclerotic mice on a western-type diet with DSPG-liposomes encapsulating an LDL-derived peptide antigen significantly reduced plaque formation by 50% and stabilized the plaques, and reduced serum cholesterol concentrations. These results indicate that DSPG-liposomes have potential as a delivery system in vaccination against atherosclerosis.

Influence of hypercholesterolemia on serum antibodies against oxidized LDL in children and adolescents

BACKGROUND

The oxidation of low-density lipoprotein (LDL; oxLDL) appears to play a key role in the early development of atherosclerosis. Increased serum antibodies against the oxLDL (anti-oxLDL antibodies) have been found in adults with atherosclerotic disease, as well as in healthy adults. The clinical significance and its precise role (atherogenic or atheroprotective), however, have not yet been clarified. This aim of this study was therefore to evaluate anti-oxLDL antibodies in healthy children and adolescents with and without hypercholesterolemia.

METHODS

The study involved 312 subjects, aged 4-18 years, 141 with LDL cholesterol (LDL-C) ≥130 mg/dL and 171 with acceptable LDL-C (<110 mg/dL). Total anti-oxLDL antibodies, total cholesterol, LDL-C and high-density lipoprotein cholesterol, triglycerides, apolipoproteins A1 and B, lipoprotein (a) and high-sensitivity C-reactive protein were measured in fasting serum. The anti-oxLDL antibodies were measured on enzyme-linked immunosorbent assay.

RESULTS

Anti-oxLDL antibodies were similar in the hypercholesterolemia and non-hypercholesterolemia groups. Girls had significantly higher anti-oxLDL antibodies compared with boys. There was no significant correlation of antibodies with age or body mass index. Increased apolipoprotein B was an important factor for lower anti-oxLDL antibodies, while all other parameters had no significant association with anti-oxLDL antibodies.

CONCLUSION

In children and adolescents with hypercholesterolemia, total anti-oxLDL antibodies cannot serve as a marker for risk for atherosclerosis or for future cardiovascular disease.

Blood-derived macrophages prone to accumulate lysosomal lipids trigger oxLDL-dependent murine hepatic inflammation

Despite the consistent rise of non-alcoholic steatohepatitis (NASH) worldwide, the mechanisms that govern the inflammatory aspect of this disease remain unknown. Previous research showed an association between hepatic inflammation and lysosomal lipid accumulation in blood-derived hepatic macrophages. Additionally, in vitro findings indicated that lipids, specifically derived from the oxidized low-density lipoprotein (oxLDL) particle, are resistant to removal from lysosomes. On this basis, we investigated whether lysosomal lipid accumulation in blood-derived hepatic macrophages is causally linked to hepatic inflammation and assessed to what extent increasing anti-oxLDL IgM autoantibodies can affect this mechanism. By creating a proof-of-concept mouse model, we demonstrate a causal role for lysosomal lipids in blood-derived hepatic macrophages in mediating hepatic inflammation and initiation of fibrosis. Furthermore, our findings show that increasing anti-oxLDL IgM autoantibody levels reduces inflammation. Hence, therapies aimed at improving lipid-induced lysosomal dysfunction and blocking oxLDL-formation deserve further investigation in the context of NASH.

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.

High Levels of (Un)Switched Memory B Cells Are Associated With Better Outcome in Patients With Advanced Atherosclerotic Disease

BACKGROUND

Atherosclerosis is an inflammatory lipid disorder and the main underlying pathology of acute ischemic events. Despite a vast amount of data from murine atherosclerosis models, evidence of B-cell involvement in human atherosclerotic disease is limited. We therefore investigated the association of circulating B-cell subtypes with the occurrence of secondary cardiovascular events in advanced atherosclerotic disease.

METHODS AND RESULTS

This cohort study consists of 168 patients who were included in the Athero-Express biobank between 2009 and 2011. Before surgery, peripheral blood mononuclear cells were isolated and stored in liquid nitrogen. After gentle thawing of the peripheral blood mononuclear cells, different B-cell subtypes including naïve, (un)switched memory, and CD27+CD43+ B1-like B cells, were analyzed by flow cytometry. Univariable and multivariable Cox proportional hazard models were used to analyze associations between B-cell subtypes, circulating antibodies and secondary cardiovascular manifestations during the 3-year follow-up period. Mean age was 70.1±9.6 years, males represented 62.8% of the population, and 54 patients had secondary manifestations during follow-up. High numbers of unswitched memory cells were protective against secondary outcome (hazard ratio, 0.30 [95% CI, 0.13-0.69]; P<0.01). Similar results were obtained for the switched memory cells that also showed to be protective against secondary outcome (hazard ratio, 0.33 [95% CI, 0.14-0.77]; P=0.01).

CONCLUSIONS

A high number of (un)switched memory B cells is associated with better outcome following carotid artery endarterectomy. These findings suggest a potential role for B-cell subsets in prediction and prevention of secondary cardiovascular events in patients with atherosclerosis.

Cross-reactive saliva IgA antibodies to oxidized LDL and periodontal pathogens in humans

AIM

Oxidized low-density lipoproteins (oxLDL) are formed as a result of lipid peroxidation and are highly immunogenic and proatherogenic. In this study, saliva antibodies binding to oxLDL, Porphyromonas gingivalis (Pg) and Aggregatibacter actinomycetemcomitans (Aa) were characterized and their cross-reactivity was evaluated.

MATERIALS AND METHODS

Resting and stimulated saliva samples were collected from 36 healthy adults (mean age 26 years). Saliva IgA, IgG and IgM autoantibody levels to copper oxidized LDL (CuOx-LDL) and malondialdehyde acetaldehyde-modified LDL (MAA-LDL) were determined with chemiluminescence immunoassay.

RESULTS

Saliva IgA and IgG antibodies binding to MAA-LDL and CuOx-LDL were detected in all samples and they were associated with the saliva levels of IgA and IgG to P. gingivalis and A. actinomycetemcomitans. Competitive immunoassay showed that saliva antibodies to MAA-LDL cross-reacted specifically with P. gingivalis. The autoantibody levels to oxLDL in saliva were not associated with the autoantibody levels to oxLDL in plasma or with saliva apolipoprotein B 100 levels.

CONCLUSIONS

Saliva contains IgA and IgG binding to oxLDL, which showed cross-reactive properties with the periodontal pathogens Porphyromonas gingivalis (P.g). The data suggest that secretory IgA to P.g may participate in immune reactions involved in LDL oxidation through molecular mimicry.

Long-term follow-up of circulating oxidative stress markers in patients undergoing lipoprotein apheresis by Direct Adsorption of Lipids (DALI)

OBJECTIVE

Beyond its well-established efficacy in lowering atherogenic lipids and lipoproteins, DALI (Direct Adsorption of Lipids) apheresis has been shown to have acute anti-inflammatory and endothelium-protective effects. In the present study, we investigated long-term effects of DALI procedures on circulating oxidative stress markers.

METHODS

Thirteen patients involved in the study underwent regular DALI apheresis for nearly two years. At sessions 1, 40 and 80 conventional lipid status and changes of systemic oxidative stress markers (oxidized LDL, anti-oxidized LDL antibodies, advanced oxidation protein products (AOPP), and myeloperoxidase (MPO)) were examined.

RESULTS

DALI procedure efficiently reduced atherogenic lipids/lipoproteins. On day three after apheresis lipid parameters returned to pre-apheresis values. They showed no tendency to increase or to decrease over time. No significant differences were found between 1st, 40th and 80th sessions. In a similar way, levels of oxidative stress biomarkers acutely decreased after apheresis sessions and rebounded on day three after apheresis. No significant differences were observed between sessions 1, 40, and 80.

CONCLUSION

DALI apheresis repeatedly decreases atherogenic lipid/lipoprotein profile and oxidative stress biomarker levels during each session. Among all investigated parameters no longitudinal effects over two years could be observed.

The immunology of atherosclerosis

Cardiovascular disease is the leading cause of death worldwide, both in the general population and among patients with chronic kidney disease (CKD). In most cases, the underlying cause of the cardiovascular event is atherosclerosis - a chronic inflammatory disease. CKD accelerates atherosclerosis via augmentation of inflammation, perturbation of lipid metabolism, and other mechanisms. In the artery wall, subendothelial retention of plasma lipoproteins triggers monocyte-derived macrophages and T helper type 1 (T_H1) cells to form atherosclerotic plaques. Inflammation is initiated by innate immune reactions to modified lipoproteins and is perpetuated by T_H1 cells that react to autoantigens from the apolipoprotein B100 protein of LDL. Other T cells are also active in atherosclerotic lesions; regulatory T cells inhibit pathological inflammation, whereas T_H17 cells can promote plaque fibrosis. The slow build-up of atherosclerotic plaques is asymptomatic, but plaque rupture or endothelial erosion can induce thrombus formation, leading to myocardial infarction or ischaemic stroke. Targeting risk factors for atherosclerosis has reduced mortality, but a need exists for novel therapies to stabilize plaques and to treat arterial inflammation. Patients with CKD would likely benefit from such preventive measures.

Study of oxidative and inflammatory parameters in LDLr-KO mice treated with a hypercholesterolemic diet: Comparison between the use of Campomanesia xanthocarpa and acetylsalicylic acid

BACKGROUND

Atherosclerosis is an inflammatory disease that affects the arterial wall leading to myocardial, cerebral, and peripheral ischemic syndromes. The use of low doses of aspirin inhibits platelet aggregation and inflammation and prevents cardiovascular mortality. However, ASA may produce hemorrhagic events. Thus, several studies have sought new natural compounds to suppress platelet aggregation without causing serious adverse effects.

PURPOSE

In this sense, this study aims to compare the effects of Campomanesia xanthocarpa plant extract with those of acetylsalicylic acid (ASA) on inflammatory parameters observed in homozygous mice knockout for the low-density lipoprotein receptor (LDLr-KO) treated with a hypercholesterolemic diet.

MATERIAL AND METHODS

In this study, 28 male LDLr-KO mice were divided into three groups and fed a hypercholesterolemic diet for 4 weeks. Thereafter, the animals that received the hypercholesterolemic diet were treated for 5 days with (1) distilled water, (2) C. xanthocarpa extract, or (3) acetylsalicylic acid. The levels of inflammatory markers were assessed in the blood samples. The gastric tolerability of the animals after oral administration of the treatments was assessed through quantification of the lesions in the gastric mucosa.

RESULTS

The levels of proinflammatory cytokines IL-1, IL-6, TNF-α, and INF-γ were reduced to 19.2 ± 3%, 20.4 + 1.3%, 24.7 ± 1.2%, and 20.8 ± 1.7%, respectively, in the group treated with C. xanthocarpa, when compared to control group. Furthermore, treatment with plant extract significantly increased the levels of the anti-inflammatory cytokine IL-10 by 27.3 ± 5.9%, but ASA showed no significant effect on the same cytokines when compared to the control group, with the exception of IL-10, which presented an increase of 8.6 ± 3.5%. Treatments with C. xanthocarpa and ASA also caused significant reductions of 26.4 ± 3% and 38.4± 6% in the serum levels of oxLDL, respectively. However, only treatment with C. xanthocarpa reduced the levels of anti-oxLDL antibodies when compared with the control (25.8 ± 6%). In addition, the analyzed extract did not induce ulcerogenic activity, while ASA induced the formation of lesions.

CONCLUSION

In conclusion, treatment with C. xanthocarpa causes anti-inflammatory activity in hypercholesterolemic animals, with results superior to those obtained with the use of ASA.

The role of lipoprotein-associated phospholipase A2 in a murine model of experimental autoimmune uveoretinitis

Macrophage activation is, in part, regulated via hydrolysis of oxidised low density lipoproteins by Lipoprotein-Associated phospholipase A₂ (Lp-PLA₂), resulting in increased macrophage migration, pro-inflammatory cytokine release and chemokine expression. In uveitis, tissue damage is mediated as a result of macrophage activation; hence inhibition of Lp-PLA₂ may limit macrophage activation and protect the tissue. Utilising Lp-PLA₂ gene-deficient (KO) mice and a pharmacological inhibitor of Lp-PLA₂ (SB-435495) we aimed to determine the effect of Lp-PLA₂ suppression in mediating retinal protection in a model of autoimmune retinal inflammation, experimental autoimmune uveoretinitis (EAU). Following immunisation with RBP-3 (IRBP) 1–20 or 161–180 peptides, clinical disease was monitored and severity assessed, infiltrating leukocytes were enumerated by flow cytometry and tissue destruction quantified by histology. Despite ablation of Lp-PLA₂ enzyme activity in Lp-PLA₂ KO mice or wild-type mice treated with SB-435495, the number of infiltrating CD45⁺ cells in the retina was equivalent to control EAU animals, and there was no reduction in disease severity. Thus, despite the reported beneficial effects of therapeutic Lp-PLA₂ depletion in a variety of vascular inflammatory conditions, we were unable to attenuate disease, show delayed disease onset or prevent progression of EAU in Lp-PLA₂ KO mice. Although EAU exhibits inflammatory vasculopathy there is no overt defect in lipid metabolism and given the lack of effect following Lp-PLA₂ suppression, these data support the hypothesis that sub-acute autoimmune inflammatory disease progresses independently of Lp-PLA₂ activity.

Oxidized low-density lipoprotein antibodies in myocardial infarction patients without classical risk factors

AIM

To determine whether circulating antibodies against oxidized low-density lipoprotein (LDL; OLAB) levels are associated with acute myocardial infarction (AMI) in individuals without classical cardiovascular risk factors.

METHODS

A case-control study including 34 first AMI patients without classical risk factors (smoking, dyslipidemia, hypertension or diabetes) and 45 population-based healthy controls.

RESULTS

There were no differences in anthropometric variables between cases and controls. Oxidized LDL levels were similar in both groups. Total cholesterol, LDL cholesterol, apolipoprotein B and physical activity were lower in cases than in controls. OLAB levels were also lower in cases than controls (128 versus 447 U/l, P < 0.001). After adjusting for age, oxidized LDL and physical activity, participants with OLAB levels of 165 U/l or less had a higher risk of AMI (odds ratio, OR = 7.48, 95% confidence interval: 1.57-35.66). When the model was fitted with OLAB as a continuous variable, the natural logarithm (LnOLAB) levels were independently associated with AMI with an OR of 0.40 (95% confidence interval: 0.19-0.86). After adjusting the model by Framingham-risk-adapted score and oxidized LDL, the LnOLAB levels maintained their independent association (OR of 0.43, 95% confidence interval: 0.23-0.79).

CONCLUSION

First AMI patients without classical risk factors had lower levels of OLAB compared with healthy controls. It is likely that the immunological reaction due to oxidized LDL participates as a preventive factor in the physiopathology of atherosclerosis.

Paraoxonase 1 activity and level of antibodies directed against oxidized low density lipoproteins in a group of an elderly population in Poland - PolSenior study

The aim of this study was to assess two factors influencing the amount of oxidized LDL-paraoxonase 1 (PON1) activity and the level of anti-oxidized LDL antibodies (anti-ox LDL) in a large group of elderly individuals in Poland. The effects of cognitive status, hypertension and metabolic syndrome and of selected serum lipids and inflammation indicators on PON1 activity and anti-ox LDL level were also examined. The investigated population consisted of 3154 individuals aged 65 and more - participants of the population-based PolSenior project. PON1 arylesterase activity was determined spectrophotometrically, anti-ox-LDL antibodies using ELISA method. PON1 activity significantly decreased with advancing age, was lower in males than in females and decreased in persons with impaired cognition. Individuals with hypertension and high lipid levels showed higher PON1 activity. Lower PON1 activity was related to higher level of inflammation indicators - hsCRP and IL-6. The significant association of PON1 activity with age, HDL-C, LDL-C, sex and IL-6 was confirmed in multivariate analysis. Anti-ox LDL antibodies level was significantly higher in the two oldest subgroups of males. It was significantly lower in males than in females. It was decreased in persons with higher serum triglycerides. No relationship of anti-ox LDL level with cognition, hypertension, metabolic syndrome, inflammation indicators and serum lipid levels was observed. In some persons very high levels of anti-ox LDL were stated, most frequently in the oldest persons, particularly in men.

CONCLUSION

Both investigated antioxidant factors - PON1 activity and anti-ox LDL level, could play an important role in aging.

Plasma oxidized low density lipoprotein cholesterol correlates inversely with testosterone in young adult male smokers

INTRODUCTION

There are indications that oxidized low density lipoprotein cholesterol (Ox-LDLC) may play an important role in cardiovascular disease (CVD) events. In most developing countries, the interplay between the different lipid fractions and cigarette smoking has not been studied. This study assessed the effect of cigarette smoking on the alterations in plasma lipid fractions and their associations with the gonadal hormone, testosterone (T).

METHODS

One hundred and sixty male participants, consisting of eighty smokers and eighty apparently healthy non-smokers were recruited. Anthropometric indices and biochemical parameters were determined using standard procedures.

RESULTS

Significant increases were obtained in plasma total cholesterol (TC), triglyceride (TG), oxidized low density lipoprotein (Ox-LDLC) and Ox-LDLC/TT ratio (p<0.001) in smokers compared with the non-smokers. Plasma high density cholesterol (HDLC) (p<0.001) was significantly reduced in smokers compared with the non-smokers. The plasma mean T result was not significantly different from the non-smokers, but inversely correlated with Ox-LDLC and significantly correlated with the lipids and lipoproteins. Significantly high plasma TC, TG and LDLC (p<0.001) and low HDLC (p<0.001) were also obtained in smokers when co-founding factors such as duration and number of cigarette smoked per day were applied.

CONCLUSION

This study showed an inverse correlation between Ox-LDLC and testosterone as well as strong association between the number of tobacco and cigarettes usage per day. These changes in part, could be major causes of premature CVD and decreased fertility in young adults.

Lysosomal cholesterol accumulation: driver on the road to inflammation during atherosclerosis and non-alcoholic steatohepatitis

Many studies show an association between the accumulation of cholesterol inside lysosomes and the progression towards inflammatory disease states that are closely related to obesity. While in the past, the knowledge regarding lysosomal cholesterol accumulation was limited to its association with plaque severity during atherosclerosis, recently, a growing body of evidence indicates a causal link between lysosomal cholesterol accumulation and inflammation. These findings make lysosomal cholesterol accumulation an important target for intervention in metabolic diseases that are characterized by the presence of an inflammatory response. In this review, we aim to show the importance of cholesterol trapping inside lysosomes to the development of inflammation by focusing upon cardiovascular disease and non-alcoholic steatohepatitis (NASH) in particular. We summarize current data supporting the hypothesis that lysosomal cholesterol accumulation plays a key role in the development of inflammation during atherosclerosis and NASH. In addition, potential mechanisms by which disturbed lysosomal function can trigger the inflammatory response, the challenges in improving cholesterol trafficking in macrophages and recent successful research directions will be discussed.

The Peripheral Network between Oxidative Stress and Inflammation in Multiple Sclerosis

Reactive oxygen species (ROS) are mainly produced by microglia and macrophages during inflammation-driven oxidative burst. However, they can in turn affect the reactivity and function of immune cells. For the first time, the relationship between these two key players involved in Multiple Sclerosis (MS) was evaluated at peripheral level. We performed an in-depth immune-phenotypic and functional analysis of MBP (Myelin Basic Protein)-stimulated Peripheral Blood Mononuclear Cells (PBMCs) by flow-cytometry. In addition, blood Coenzyme-Q10 (CoQ10), total, oxidized and reduced forms of glutathione (GSTot, GSSG, GSH), malondialdehyde (MDA), ROS, anti-oxidized-low-density-lipoproteins antibodies (anti-oxLDL), and anti-oxidant-power (PAO) were studied in 31 untreated MS patients (MSnoTP), 23 MS patients (MSTP) treated with Disease Modifying Drugs (DMDs) and 39 matched controls (HC). The focus of our study was the correlation between oxidative stress biomarkers and distribution of immune-phenotypes across the 3 studied groups. In MSnoTP an inverse correlation between MDA and apoptotic cells (CD4+ AnnexinV+TIM3+) was detected (rs= − 0.50, p= 0.01). Ml functional phenotype (CD14+IL6+) and TH17 cells (CD4+IL22+) inversely (rs= − 0.48) and directly (rs= 0.46) correlated (p = 0.01) with Anti-oxLDL antibodies and GSSG, respectively. The latter direct correlation was shown also in MSTP. Notably, in this group, we also detected a direct correlation between CD4+ IL4+ and CD4+ IL25+ (TH2 phenotype) with CoQ10 (rs= 0.54) and GSH (rs= 0.46) (p< 0.03), two crucial anti-oxidants. Again, a direct correlation was found between CD8+ BDNF+ cells (suppressor phenotype) and anti-oxLDL (rs= 0.48, p= 0.03). Surprisingly, we measured an inverse correlation between CD14+ IL10+ cells (M2 immune-regulatory cells) with GSH (rs= − 0.59, p< 0.001). Our findings endorse the idea of a relationship between pro-inflammatory cells and pro-oxidative environment, even at peripheral level. Interestingly, the correlation between CD4+ IL10+cells and a defective anti-oxidant equipment might be regarded as evidence of the involvement of these cells during an inflammatory/oxidative phase that they try to control. The finding of this link only in MSTP patients might suggest that DMDs can provide an alternative way to counteract inflammation, regardless of an absolute increase of these immune-regulatory cells.

Oxidative stress is differentially present in multiple sclerosis courses, early evident, and unrelated to treatment

BACKGROUND

Oxidative stress is well documented in multiple sclerosis (MS) lesions, but its correspondence at peripheral level is still controversial. Objective. To evaluate peripheral oxidative stress markers in MS patients.

METHODS

We studied total blood levels of Coenzyme Q10 (CoQ10), oxidized and reduced forms of glutathione, malondialdehyde, reactive oxygen species (ROS), anti-oxidized-low-density lipoproteins (anti-oxLDL) antibodies, and antioxidant power (PAO) in 87 patients with different MS clinical phenotypes and in 77 controls.

RESULTS

CoQ10 was lower whereas anti-oxLDL antibodies titer was higher in MS patients than in controls. The benign variant of MS displayed both higher CoQ10 and higher anti-oxLDL than other MS clinical variants. Female patients had lower CoQ10 and PAO and higher ROS than male patients. Differences were greater in younger patients with shorter disease duration. Surprisingly, there was no difference for these markers between treated and untreated patients.

CONCLUSION

We found lower antioxidant agents and higher anti-oxLDL antibodies in MS, and the highest antibody titers occurred in the benign form. We suggest that natural anti-oxLDL antibodies can be protective against MS, saving blood brain barrier integrity. Our findings also suggest that milder MS is associated with a distinct oxidative stress pattern, which may provide a useful biomarker of disease prognosis.

Using oxidized low-density lipoprotein autoantibodies to predict restenosis after balloon angioplasty in patients with acute myocardial infarction

Objectives

Oxidized low-density lipoproteins (oxLDL) and oxidized low-density lipoprotein autoantibodies (OLAB) have been detected in human plasma and atherosclerotic lesions. OLAB appear to play a role in the clearance of oxLDL from circulation. Higher levels of OLAB appear to be associated with a reduced risk of a wide range of cardiovascular diseases. We investigated the prognostic value of plasma oxLDL and OLAB in patients undergoing primary coronary balloon angioplasty for acute ST-elevation myocardial infarction (STEMI).

Methods

Plasma oxLDL and OLAB concentrations were measured in 56 patients with acute STEMI before primary angioplasty, and then 3 days, 7 days and 1 month after the acute event. Follow-up angiography was repeated 6 months later to detect the presence of restensosis (defined as >50% luminal diameter stenosis). The thrombolysis in myocardial infarction (TIMI) risk score was calculated to determine the relationship between OLAB/oxLDL ratio and TIMI risk scores.

Results

Of the 56 patients, 18 (31%) had angiographic evidence of restenosis. Plasma OLAB concentrations were significantly lower in the restenosis group before angioplasty (181±114 vs. 335±257 U/L, p = 0.003), and at day 3 (155±92 vs. 277±185 U/L, p<0.001) and day 7 (177±110 vs. 352±279 U/L, p<0.001) after the acute event. There was no difference in oxLDL concentration between the two groups. The ratio of OLAB/oxLDL positively correlated with TIMI risk scores before angioplasty (p for trend analysis, p = 0.004), at day 3 (p = 0.008) and day 7 (p<0.001) after STEMI.

Significance

A relative deficit of OLAB, and hence likely impaired clearance of oxLDL, is associated with the risk of arterial restenosis after primary angioplasty for acute STEMI.

Dyslipidemia in patients with chronic and end-stage kidney disease

In this review, we discuss the physiology, diagnosis and treatment of dyslipidemia in patients with chronic and end-stage renal disease. The recent important clinical trials in patients with chronic kidney disease and dyslipidemia are reviewed. Because of the lack of evidence in treating lipid abnormalities in this specific patient population, we propose that future studies should focus on the pathophysiological mechanisms and treatment of dyslipidemia in this special patient population.

LDL Oxidation and Its Association With Carotid Artery Intima-Media Thickness and Other Cardiovascular Risk Factors in a Sample of Spanish General Population

We studied the association between oxidized low-density lipoproteins (OxLDLs) and early atherosclerosis, assessed by carotid artery intima-media thickness (cIMT), as well as with other known atherosclerosis risk factors in a sample of the general middle- and old-age population of Burgos (Spain). Circulating OxLDL showed a significant and independent association with the average cIMT of both carotid arteries but not with the absence or presence of ≥1 carotid atheroma plaques. Plasma OxLDL concentrations were associated with age, smoking, low-density lipoprotein-cholesterol, and triglycerides, independently of other variables. Our findings in an asymptomatic sample representative of the Spanish middle- and old-age population underscore the role of OxLDL in early atherosclerosis represented by the cIMT especially in older asymptomatic individuals, but this cannot be extended to more advanced atherosclerosis, represented by carotid plaques.

Oxidative stress increases continuously with BMI and age with unfavourable profiles in males

Oxidative stress is a risk factor for chronic diseases and was previously shown to be independently associated with obesity. The authors investigated the relationship between body mass index (BMI), age and oxidative stress on 2190 subjects undergoing a health care examination. Total antioxidant status (TAS), total peroxides (TOC) and autoantibodies against oxidized LDL (oLAb) were used as oxidative stress biomarkers in addition to serum lipoproteins, bilirubin and uric acid. Gender-specific differences were observed for age, BMI, serum concentrations of bilirubin, low-density lipoprotein (LDL), uric acid and TAS, all of which were higher in males (p < 0.001), while high-density lipoprotein (HDL), HDL/LDL ratio and TOC were higher in females (p < 0.001). Total cholesterol (p < 0.05) and LDL were increased (p < 0.05), while HDL was decreased (p < 0.05) in overweight and obese subjects. This was accompanied by increased uric acid and TAS concentrations. Lowest oLAb titers were detected in obese subjects. In extremely obese subjects, increased TOC and decreased TAS were observed in spite of high uric acid levels. These results demonstrate that oxidative stress increases with increasing BMI and age, as a sequel to an impaired antioxidant status, the consumption of oLAbs, an increase of peroxides and uric acid and a disadvantaged lipid profile.

Immune response to lipoproteins in atherosclerosis

Atherosclerosis, the underlying cause of cardiovascular disease, is characterized by chronic inflammation and altered immune response. Cholesterol is a well-known risk factor associated with the development of cardiovascular diseases. Elevated serum cholesterol is unique because it can lead to development of atherosclerosis in animals and humans even in the absence of other risk factors. Modifications of low-density lipoproteins mediated by oxidation, enzymatic degradation, and aggregation result in changes in their function and activate both innate and adaptive immune system. Oxidized low-density lipoprotein (LDL) has been identified as one of the most important autoantigens in atherosclerosis. This escape from self-tolerance is dependent on the formation of oxidized phospholipids. The emerging understanding of the importance of immune responses against oxidized LDL in atherosclerosis has focused attention on the possibility of development of novel therapy for atherosclerosis. This review provides an overview of immune response to lipoproteins and the fascinating possibility of developing an immunomodulatory therapy for atherosclerosis.

Oxidized LDL to autoantibodies against oxLDL ratio - the new biomarker associated with carotid atherosclerosis and cardiovascular complications in dialyzed patients

OBJECTIVE

To investigate the role of autoantibodies against oxidized LDL (oxLDL-Ab) in clearing of oxLDL from circulation in dialyzed uremic patients, as well as the significance of this process in the carotid atherosclerosis and cardiovascular complications.

METHODS

oxLDL, oxLDL-Ab and intima-media thickness (IMT) were measured in 132 uremic patients on hemodialysis (HD), peritoneal dialysis (PD) or conservative treatment both with and without cardiovascular disease (CVD) and in 29 healthy controls. The ratio of oxLDL to oxLDL-Ab (oxLDL/oxLDL-Ab), reflecting the balance between in vivo oxidative LDL modification and the clearance of oxLDL from circulation was also calculated.

RESULTS

oxLDL were lower, whereas oxLDL-Ab were higher in patients without CVD compared to those with CVD. oxLDL/oxLDL-Ab ratio was also significantly lower in dialyzed subjects without CVD compared to their counterparts with CVD and healthy controls. IMT values were significantly higher in uremic patients compared with controls, and patients with CVD had particularly elevated IMT compared with those without CVD. The inverse correlation was between IMT and oxLDL-Ab, whereas the IMT was strongly and positively associated with oxLDL/oxLDL-Ab ratio. There was the weak inverse relationship between oxLDL and oxLDL-Ab levels in dialyzed patients. Multiple stepwise regression analysis identified oxLDL/oxLDL-Ab ratio as one of the predictors of IMT in the whole dialyzed group.

CONCLUSIONS

oxLDL/oxLDL-Ab ratio could be a new biomarker significantly and independently associated with carotid atherosclerosis in dialyzed patients. A titer of oxLDL-Ab and oxLDL/oxLDL-Ab ratio seem to play an important role for distinguishing patients with and without cardiovascular complications.

Imbalance in superoxide dismutase/thioredoxin reductase activities in hypercholesterolemic subjects: relationship with low density lipoprotein oxidation

BACKGROUND

There is a relationship among hypercholesterolemia, oxidative stress and inflammation in the atherogenesis. Thus, the objective of the present study was to assess paraoxonase (PON1), superoxide dismutase (SOD) and thioredoxin reductase (TrxR-1) activities and their relationship with lipids, oxidative stress and inflammation in subjects with different low density lipoprotein-cholesterol (LDL) levels.

METHODS

Serum lipids, highly sensitive C-reactive protein (hs-CRP), lipid and protein oxidation, oxidized LDL (LDLox) and LDLox autoantibodies (LDLoxAB) levels and enzymes activities were measured in a total of 116 subjects that were divided into the following groups according to their LDL levels: low-LDL group (LDL < 100 mg/dL, n = 23), intermediate-LDL group (LDL 100-160 mg/dL, n = 50) and high-LDL group (LDL > 160 mg/dL, n = 43).

RESULTS

The LDLox and hs-CRP levels increased in the high-LDL group (2.7- and 3.7- fold, respectively), whereas the intermediate and high-LDL groups had higher LDLoxAB (2.2- and 3.1-fold) when compared to low-LDL group (p < 0.05). Similarly, SOD activity, the atherogenic index (AI) and protein oxidation were also higher in the intermediate (1.3-, 1.3- and 1.2-fold) and high-LDL (1.6-, 2.3- and 1.6-fold) groups when compared to the low-LDL group (p < 0.05). Lipid oxidation and SOD/TrxR-1 ratio increased only in the high-LDL group (1.3- and 1.6-fold) when compared to the low-LDL group (p < 0.05). The SOD/TrxR-1 ratio was positively correlated to TBARS (r = 0.23, p < 0.05), LDLox (r = 0.18, p < 0.05), LDLoxAB (r = 0.21, p < 0.05), LDL (r = 0.19, p < 0.05) and AI (r = 0.22, p < 0.05). PON1 and TrxR-1 activities were similar among groups.

CONCLUSIONS

Some oxidative events initiate when LDL levels are clinically acceptable. Moreover, hypercholesterolemic patients have an imbalance in SOD and TrxR-1 activities that is positively associated to LDL oxidation.

Anti-oxidized low-density lipoprotein (oxLDL) antibody levels are not related to increasing circulating oxLDL concentrations during the course of pregnancy

PROBLEM

To address the question of whether the high levels of oxidative modified low-density lipoproteins (oxLDL) in pregnancy are opposed by an appropriate humoral autoimmune response providing anti-oxLDL autoantibodies in maternal serum of healthy women throughout gestation.

METHOD OF STUDY

Blood was taken from 33 patients at four different time points from early to late gestation and post-partum. OxLDL and anti-oxLDL concentrations were measured by enzyme-linked immunosorbent assays. ANOVA was used for statistical evaluations followed by post hoc test with Bonferoni adjustment.

RESULTS

Oxidized Low Density Lipoprotein concentrations increased while anti-oxLDL levels decreased significantly from early to late gestation. OxLDL was strongly positively correlated with LDL concentration and mildly negatively associated with anti-oxLDL levels. Estimating the status of oxidation by calculating oxLDL/LDL ratio revealed decreasing values with ongoing pregnancy. Multivariate analysis showed that anti-oxLDL levels were dependent on gestational age but neither on oxLDL levels nor on the oxLDL/LDL ratio.

CONCLUSIONS

The results indicate that normal pregnancy is a well-balanced state of oxidative and anti-oxidative processes. However, we could not confirm a dependence of anti-oxLDL autoantibodies on oxLDL concentration. Whether or not the humoral immune system is involved in oxidative defence remains to be elucidated.

Neither oxidized nor anti-oxidized low-density lipoprotein level is associated with atherosclerosis or mortality in hemodialysis patients

It is anticipated that oxidized low-density lipoprotein (oxLDL) and anti-oxLDL are associated with atherosclerosis and mortality. However, data on this issue are controversial and limited. We aimed to investigate the effect of these two markers on the extent and progression of atherosclerosis and mortality in a group of hemodialysis patients. In this prospective observational study with a follow-up of 36 months, 124 hemodialysis patients were studied. Ninety-five patients underwent carotid intima media thickness (CA-IMT) measurement by B-Mode ultrasonography both at baseline and at the end of the study. oxLDL and anti-oxLDL were measured by enzyme-linked immunosorbent assay. The extent and progression of CA-IMT, along with overall and cardiovascular mortality, were assessed. The mean age at baseline was 54.0 ± 14.8 years, 57.3% male and 20% diabetic. The mean oxLDL and anti-oxLDL levels were 8.11 ± 3.16 mU/L and 1.30 ± 0.31, respectively. Baseline mean CA-IMT was 0.82 ± 0.20 mm. Fifteen patients died during a follow-up period of 28.5 ± 6.6 months, 11 from cardiovascular causes. Only oxLDL, not anti-oxLDL, was correlated with the extent of atherosclerosis at baseline. However, both had no role in the progression of atherosclerosis. Also, in unadjusted and adjusted models, both parameters were not associated with overall or cardiovascular mortality. Neither oxLDL nor anti-oxLDL level is associated with the progression of atherosclerosis or mortality in hemodialysis patients.

Association between OLR1 K167N SNP and intima media thickness of the common carotid artery in the general population

BACKGROUND AND PURPOSE

The lectin-like oxidised LDL receptor-1 (OLR1) gene encodes a scavenger receptor implicated in the pathogenesis of atherosclerosis. Although functional roles have been suggested for two variants, epidemiological studies on OLR1 have been inconsistent.

METHODS

We tested the association between the non-synonymous substitution K167N (rs11053646) and intima media thickness of the common carotid artery (CCA-IMT) in 2,141 samples from the Progression of Lesions in the Intima of the Carotid (PLIC) study (a prospective population-based study).

RESULTS

Significantly increased IMT was observed in male carriers of the minor C (N) allele compared to GC and GG (KN and KK) genotype. Functional analysis on macrophages suggested a decreased association to Ox-LDL in NN carriers compared to KN and KK carriers which is also associated with a reduced OLR1 mRNA expression. Macrophages from NN carriers present also a specific inflammatory gene expression pattern compared to cells from KN and KK carriers.

CONCLUSIONS

These data suggest that the 167N variant of LOX-1 receptor affects the atherogenic process in the carotid artery prior to evidence of disease through an inflammatory process.

Susceptibility of LDL and its subfractions to glycation

PURPOSE OF REVIEW

To highlight the potential importance of glycation as an atherogenic modification of LDL, factors determining glycated apolipoprotein B in vivo and susceptibility of LDL to glycation in vitro. We also discuss the distribution of glycated apolipoprotein B across different LDL subfractions in healthy controls, patients with type 2 diabetes and metabolic syndrome.

RECENT FINDINGS

Small, dense LDL, which is known to be most closely associated with atherogenesis, is more preferentially glycated in vivo and more susceptible to glycation in vitro than more buoyant LDL. Glycation and oxidation of LDL appear to be intimately linked. In patients with type 2 diabetes, plasma glycated apolipoprotein B correlated with small, dense LDL apolipoprotein B, but not with HbA1c. Glycated apolipoprotein B is significantly lower in statin-treated type 2 diabetes compared with those not on statins.

SUMMARY

Glycation of LDL occurs chiefly because of the nonenzymatic reaction of glucose and its metabolites with the free amino groups of lysine of which apolipoprotein B is rich. Higher concentrations of glycated LDL are present in diabetes than in nondiabetic individuals and metabolic syndrome. Even in nondiabetic individuals, however, there is generally more circulating glycated LDL than oxidatively modified LDL. Probably, oxidation and glycation of LDL are partially interdependent and indisputably coexist, and both prevent LDL receptor-mediated uptake and promote macrophage scavenger receptor-mediated LDL uptake. The recognition that LDL glycation is at least as important as oxidation in atherogenesis may lead to improvements in our understanding of its mechanism and how to prevent it.

High density lipoprotein cholesterol level is a robust predictor of lipid peroxidation irrespective of gender, age, obesity, and inflammatory or metabolic biomarkers

BACKGROUND

Obesity related dyslipidemia, chronic inflammation and oxidative stress were associated with atherosclerotic sequels. We analysed oxidized low-density lipoprotein (oxLDL) plasma levels of 797 participants of the STyrian Juvenile OBesity (STYJOBS) / Early DEteCTion of Atherosclerosis (EDECTA) Study cohort aged from 5 to 50 years. The rationale of STYJOBS/EDECTA is to investigate the preclinical phase of obesity by a well defined cohort of young and middle aged overweight/obese and normal weight subjects.

METHODS AND RESULTS

Plasma oxLDL was analysed by ELISA (Mercodia, Sweden). In the overweight/obese (OW/OB) study group, oxLDL levels were significantly increased compared to normal weighted controls (p<0.001). Probands with metabolic syndrome (MS) had significantly higher oxLDL levels than probands without MS; between overweight and obese participants, and between females and males, no significant difference was seen. In a multiple stepwise regression analysis including all study subjects, age, gender, anthropometric data, presence of metabolic syndrome, systolic, diastolic blood pressure, carotis communis intima media thickness, lipids, adipokines, metabolic, and inflammatory biomarkers, decreased high-density lipoprotein (HDL-cholesterol) and increased total cholesterol were the best predictors for increased oxLDL levels.

CONCLUSION

Decreased HDL-cholesterol is an important determinant of lipid peroxidation irrespective of obesity, age, gender, SAT distribution, and inflammatory/metabolic biomarkers.

Vaccination, atherosclerosis and systemic lupus erythematosus

Atherosclerosis is an inflammatory disease, leading to the formation of pro-inflammatory and pro-oxidative lipids that generate an immune response. Several antigens have been shown to activate the immune response and affect the development of atherogenesis. Systemic lupus erythematosus is an autoimmune and inflammatory disease strongly associated with premature development of atherosclerotic plaques. Modulation of the immune system could represent a useful approach to prevent and/or treat atherosclerosis. A vaccination-based approach might be a useful, effective tool in the modern arsenal of cardiovascular therapies and could be used on a large scale at a low cost. In non-systemic lupus erythematosus populations, vaccines against oxidized low-density lipoprotein, beta-2-glycoprotein I, heat shock proteins, lipoproteins, cholesterol, molecules involved in cholesterol metabolism, and other molecules (CD99, vascular endothelial growth factor-receptor, and interleukin-2) have been tested, with promising results. However, there are no studies of vaccination against atherosclerosis in systemic lupus erythematosus.