Anti-oxidized Low-density Lipoprotein Research Articles

Increased Concentrations of Atherogenic Proteins in Aneurysm Sac Are Associated with Wall Enhancement of Unruptured Intracranial Aneurysm

Current MR-vessel wall imaging (VWI) of unruptured intracranial aneurysms (UIAs) permits the visualization of wall structures. Aneurysm wall enhancement (AWE) was associated with atherosclerotic remodeling of the aneurysm wall accompanied by infiltration of inflammatory cells, potentially contributing to rupture. This study sought to investigate whether the luminal concentrations of atherosclerotic proteins in the aneurysm sac were associated with increased wall enhancement of UIAs in VWI. Subjects undergoing endovascular treatment for UIAs were prospectively recruited. All subjects underwent evaluation using 3T-MRI including pre/post contrast VWI of the UIAs. Blood samples were collected from the aneurysm sac and the parent artery during endovascular procedures. The presence of AWE was correlated with the delta difference in concentration between the aneurysm sac and the parent artery for each atherosclerotic protein. A total of consecutive 45 patients with 50 UIAs were enrolled. The delta differences of anti-oxidized low-density lipoprotein (LDL) antibody, small dense LDL, and lipoprotein(a) [Lp(a)]were significantly higher in UIAs with AWE compared with those without AWE (767.6 ± 1957.1 versus - 442.4 ± 1676.3 mIU/mL, p = 0.02, 114.8 ± 397.7 versus - 518.5 ± 1344.4μg/mL, p = 0.04, and - 5.6 ± 11.3 versus - 28.7 ± 38.5μg/mL, p = 0.01, respectively). In multivariate logistic regression analysis, the delta Lp(a) was significantly associated with AWE (p = 0.04). Increased concentrations of atherogenic proteins in the aneurysm sac were significantly associated with wall enhancement of UIAs. Future studies examining the effect of medications for atherosclerosis on the atherogenic proteins within the aneurysm sac and hence the wall enhancement are warranted.

Safety and Efficacy of Simultaneous Inoculations of Pneumococcal and Influenza Vaccines in Patients with Coronary Artery Disease.

Aim: Pneumococcal and influenza infections can cause serious morbidity and mortality in patients with cardiovascular diseases. The purpose of this study was to investigate the safety and efficacy of simultaneous inoculations of 23-valent pneumococcal polysaccharide vaccine (PPSV23) and trivalent influenza vaccine (TIV) in patients with coronary artery disease (CAD). Methods: This was a prospective, randomized, single-blind, placebo-controlled study. A total of 40 patients with CAD were randomly assigned to the TIV＋PPSV23 (simultaneous inoculations of TIV and PPSV23) and TIV＋Placebo (inoculations of TIV and placebo) groups. Primary outcomes were the safety of simultaneous vaccinations and the changing of circulating cardiovascular biomarkers before, at 4-, and at 12-weeks after vaccinations. Results: The baseline characteristics between the two groups were identical. The prevalence of injection-site pain, swelling, and reddening were 47%, 37%, and 37% in the TIV＋PPSV23 group, and 10%, 5%, and 0% in the TIV＋Placebo group, respectively. All reactions were self-limited. Body temperature ＞37.0℃ or serious injection-related reaction was not observed. The levels of white blood cells, high-sensitivity C-reactive protein, N-terminal pro-B-type natriuretic peptide, pentraxin-3, and malondialdehide-modified low-density lipoprotein (LDL), were not significantly different between the two groups before and after vaccinations. The levels of anti-oxidized LDL were significantly and step-wisely decreased from baseline, to 4-, and 12-weeks vaccinations in the both groups. No significant changes of other markers were observed in both groups at each time point. Conclusion: Simultaneous inoculations of TIV and PPSV23 were safety in patients with CAD, suggesting that dual vaccinations can be considered even in patients with CAD.

Paraoxonases (PON) 1, 2, and 3 Polymorphisms and PON-1 Activities in Patients with Sickle Cell Disease.

(1) Background: Oxidative stress, chronic inflammation, vasoocclusion, and free iron are all features present in sickle cell disease. Paraoxonases (PON) are a family (PON-1, PON-2, PON-3) of antioxidant enzymes with anti-inflammatory action. Here, for the first time, we described PON-1 activities and PON-1, PON-2, PON-3 polymorphisms in patients with sickle cell disease, homozygous for HbSS, compared with healthy controls. (2) Methods: The groups were matched for age and gender. PON-1 activities (arylesterase and paraoxonase) were determined by enzymatic hydrolysis of phenylcetate and paraoxon, respectively. Polymorphisms were determined by Restriction Fragment Length Polymorphism- Polymerase Chain Reaction (RFLP-PCR). (3) Results: Plasma cholesterol and fractions, ApoA1 and ApoB levels were all decreased in sickle cell disease patients, while anti-oxidized low-density lipoprotein (LDL) antibodies and C-reactive protein were increased. Serum arylesterase activity was lower in sickle cell disease patients when compared with healthy controls. In patients, paraoxonase activity was higher in those with PON-1 RR Q192R polymorphism. In these patients, the increase of serum iron and ferritin levels and transferrin saturation were less pronounced than those observed in patients with QQ or QR polymorphism. No differences were observed with PON-1 L55M, and PON-2 and PON-3 polymorphisms. Multivariate regression analysis showed that transferrin and ferritin concentrations correlated with arylesterase and paraoxonase activities. (4) Conclusions: Both transferrin and ferritin were the main predictors of decreased arylesterase and paraoxonase activities in patients with sickle cell disease. LDL oxidation increased, and RR PON-1 Q192R polymorphism is likely to be a protective factor against oxidative damage in these patients.

A role for autoantibodies in atherogenesis.

An increased risk of cardiovascular disease (CVD) has long been recognized amongst people with autoimmune disease. It has been unclear whether this is due mainly to the ensuing treatment, particularly steroids, or whether some of this risk is due to the autoimmune process itself with subsequent inflammation. Indeed, a large body of evidence supports a role for chronic inflammation in atherogenesis, and autoantibodies have been identified as mediators in this complex inflammatory environment. Our aim is to carry out a systematic review of existing literature in order to formally establish the strength of the association between autoantibodies and atherosclerosis, amongst individuals without clinical autoimmune disease. An electronic search of five databases to June 2016 was performed by two independent reviewers. Inclusion criteria were analytical studies of adults, with at least two studies per autoantibody. Quality analysis was carried out using the Newcastle-Ottawa scale and the Cochrane Risk of Bias Quality Assessment Tool where appropriate. Where possible, studies were pooled using random effects models. Raised levels of anti-cardiolipin (odds ratio [OR] = 1.30; 95% CI: 1.15-1.49) and anti-oxidized low-density lipoprotein Immunoglobulin (Ig) G (OR = 1.25; 95% CI: 1.11-1.41), unspecified anti-cyclic citrullinated protein (OR = 3.09; 95% CI: 1.49-6.41) and anti-human heat shock protein 60 IgA (OR = 1.57; 95% CI: 1.15-2.16) were observed to increase the risk of cardiovascular outcomes. Alternatively, Anti-phosphorylcholine IgM (OR = 1.31; 95% CI: 1.14-1.50) conferred protection against CVD. Our results support an important role for autoantibodies in mediating cardiovascular events, independent of therapeutic treatments. Future research may focus on the presence of autoantibodies as markers of immune dysregulation and CVD risk.

Experimental study of the anti-atherosclerotic effect of demethylzeylasteral.

This study aimed to confirm that atherosclerosis (AS) is a systemic immune-mediated chronic inflammatory disease and to investigate the anti-atherosclerotic effect of demethylzeylasteral by testing the immunocompetent cells and inflammatory mediators in the blood and atherosclerotic plaques of the rabbit model of AS. For this purpose, 60 male New Zealand white rabbits were given 150 g high-fat diet (1% cholesterol, 5% lard, and 15% egg yolk powder) daily for a total of 90 days. On day 61, the rabbits were randomly divided into the saline group (n=15), the rosuvastatin group (n=15), the low-dose demethylzeylasteral group (n=15), and the high-dose demethylzeylasteral group (n=15). The CD3+ T lymphocytes and the subsets CD4+, CD8+, and CD4+/CD8+, as well as the soluble interleukin-2 receptor (sIL-2R) were measured before and after the treatment. The contents of immunoglobulins IgG, IgA and IgM and the levels of complements C3 and C4 were also monitored. In addition, the level of anti-oxidized low-density lipoprotein (ox-LDL) antibody, the inflammatory cytokines tumor necrosis factor-α (TNF-α), IL-6 and metalloproteinase-9 (MMP-9), the blood lipids triglyceride (TG), total cholesterol (TC), LDL cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) were measured, and the severity of plaque lesions was also evaluated. Our results showed that the saline group, the rosuvastatin group and the low-dose demethylzeylasteral group had significantly lower activated T lymphocyte parameters CD3+, CD4+, CD8+ and CD4+/CD8+ (P<0.05), and significantly higher levels of sIL-2R, immunoglobulins IgG, IgA and IgM, complements C3 and C4, anti-ox-LDL antibody, TNF-α, IL-6 and MMP-9 (P<0.01) when compared with the high-dose demethylzeylasteral group. Moreover, TG, TC, LDL-C contents were found significantly lower and their HDL-C contents were significantly higher in high-dose demethylzeylasteral group (P<0.01) as compared to the other three groups. Furthermore, Sudan staining and haematoxylin and eosin staining of the thoracic aorta showed that, after 30-day treatment, the high-dose demethylzeylasteral group had the smoothest intima and the lightest plaque lesions among the four groups. Based on these results, we concluded that AS is a systemic immune-mediated chronic inflammatory disease and the relatively high dose of demethylzeylasteral used in the treatment of atherosclerotic rabbits could significantly alleviate AS. This implies that demethylzeylasteral may be considered as a suitable drug for anti-immunization therapy.

Cutting Edge: BAFF Overexpression Reduces Atherosclerosis via TACI-Dependent B Cell Activation.

Patients with systemic lupus erythematosus exhibit accelerated atherosclerosis, a chronic inflammatory disease of the arterial wall. The impact of B cells in atherosclerosis is controversial, with both protective and pathogenic roles described. For example, natural IgM binding conserved oxidized lipid epitopes protect against atherosclerosis, whereas anti-oxidized low-density lipoprotein (oxLDL) IgG likely promotes disease. Because BAFF promotes B cell class-switch recombination and humoral autoimmunity, we hypothesized that excess BAFF would accelerate atherosclerosis. In contrast, BAFF overexpression markedly reduced hypercholesterolemia and atherosclerosis in hyperlipidemic mice. BAFF-mediated atheroprotection required B cells and was associated with increased protective anti-oxLDL IgM. Surprisingly, high-titer anti-oxLDL IgM production and reduced atherosclerosis was dependent on the BAFF family receptor transmembrane activator and CAML interactor. In summary, we identified a novel role for B cell-specific, BAFF-dependent transmembrane activator and CAML interactor signals in atherosclerosis pathogenesis, of particular relevance to the use of BAFF-targeted therapies in systemic lupus erythematosus.

An Unexpected Intriguing Effect of Toll-Like Receptor Regulator RP105 (CD180) on Atherosclerosis Formation With Alterations on B-Cell Activation

In atherosclerosis, Toll-like receptors (TLRs) are traditionally linked to effects on tissue macrophages or foam cells. RP105, a structural TLR4 homolog, is an important regulator of TLR signaling. The effects of RP105 on TLR signaling vary for different leukocyte subsets known to be involved in atherosclerosis, making it unique in its role of either suppressing (in myeloid cells) or enhancing (in B cells) TLR-regulated inflammation in different cell types. We aimed to identify a role of TLR accessory molecule RP105 on circulating cells in atherosclerotic plaque formation. Irradiated low density lipoprotein receptor deficient mice received RP105(-/-) or wild-type bone marrow. RP105(-/-) chimeras displayed a 57% reduced plaque burden. Interestingly, total and activated B-cell numbers were significantly reduced in RP105(-/-) chimeras. Activation of B1 B cells was unaltered, suggesting that RP105 deficiency only affected inflammatory B2 B cells. IgM levels were unaltered, but anti-oxidized low-density lipoprotein and anti-malondialdehyde-modified low-density lipoprotein IgG2c antibody levels were significantly lower in RP105(-/-) chimeras, confirming effects on B2 B cells rather than B1 B cells. Moreover, B-cell activating factor expression was reduced in spleens of RP105(-/-) chimeras. RP105 deficiency on circulating cells results in an intriguing unexpected TLR-associated mechanisms that decrease atherosclerotic lesion formation with alterations on proinflammatory B2 B cells.

Gold Nanoparticle-Conjugated Anti-Oxidized Low-Density Lipoprotein Antibodies for Targeted Lipidomics of Oxidative Stress Biomarkers

Oxidized low-density lipoproteins (OxLDLs), in particular, oxidized phosphatidylcholines (OxPCs), are known to be involved in pathophysiological processes such as cardiovascular diseases and are described as potential biomarkers, for example, for atherosclerosis. In our study, we used the specific affinity of anti-OxLDL antibodies (Abs) conjugated to gold nanoparticles (GNPs) for extraction and enrichment of OxPCs via selective trapping of OxLDLs from plasma combined with the sensitive detection by liquid chromatography/tandem-mass spectrometry (LC-MS/MS). Successful bioconjugation chemistry of Abs via a bifunctional polyethylene glycol (PEG) spacer and protein G linkage, respectively, was controlled by measuring the surface plasmon resonance (SPR) spectra, size, and zeta potentials. Furthermore, the amount of Ab immobilized onto GNP via the PEG linker was determined. With the optimized immobilization chemistry, the ability and potential of the GNP-based extraction procedure was used for the determination of the dissociation constant, K(d), of the OxLDL binding to the GNP-Ab conjugate. Moreover, apparent K(d)'s were determined for individual PCs and their oxidation products using the compound-specific selected reaction monitoring mode, which allows the characterization of the Ab affinity and, thus, assessment of the potential antigenicity of (Ox)PCs bound to OxLDLs. In summary, the application of GNP-based bioanalysis for selective targeting of OxLDLs and the fast and sensitive detection by LC-MS/MS offers new possibilities for targeted lipidomics in lipoproteins as well as for oxidative stress lipid biomarker screening.

Adaptive immunity is related to coronary artery disease severity after acute coronary syndrome in subjects with metabolic syndrome

Metabolic syndrome (MetS) is an inflammatory state associated with high coronary disease risk. Inflammation and adaptive immunity modulate atherosclerosis and plaque instability. We examined early changes in anti-oxidized low-density lipoprotein (LDL) (anti-oxLDL) autoantibodies (Abs) in patients with MetS after an acute coronary syndrome (ACS). Patients of both genders (n=116) with MetS were prospectively included after an acute myocardial infarction (MI) or hospitalization due to unstable angina. Anti-oxLDL Abs (IgG class) were assayed at baseline, three and six weeks after ACS. The severity of coronary disease was evaluated by the Gensini score. We observed a decrease in anti-oxLDL Abs titers (p<0.002 vs. baseline), mainly in males (p=0.01), in those under 65 y (p=0.03), and in subjects with Gensini score above median (p=0.04). In conclusion, early decrease in circulating anti-oxLDL Abs is associated with coronary disease severity among subjects with MetS.

Pneumococcal vaccination may induce anti-oxidized low-density lipoprotein antibodies that have potentially protective effects against cardiovascular disease

Many animal and human studies have found an inverse association between anti-oxidized low-density lipoprotein (oxLDL) antibodies (anti-oxLDL) and atherosclerotic burden. Furthermore, anti-oxLDL antibodies have been shown to cause regression of atherosclerotic plaque in mice. Animal studies indicate that the 23-valent pneumococcal vaccine may induce the production of these potentially protective anti-oxLDL antibodies, and human epidemiological studies support their potentially beneficial effect in reducing cardiovascular events. Here we describe the association between self-reported pneumococcal vaccination, vaccination verified by linkage to health records, and anti-pneumococcal antibody titers, and anti-ox-LDL titers in a group of 116 older people. We found a bimodal distribution of anti-oxLDL antibodies, and a significant association between pneumococcal IgG and anti-oxLDL antibody titers that remained after multivariate adjustment for potential confounders (p=0.04). There was no significant association between self-reported vaccination or vaccination verified by health record linkage and ox-LDL titers, which may be due to reporting error or variability in response to the vaccine. These results support a mechanistic link between pneumococcal vaccination and a potential protective effect on cardiovascular disease, and indicate that self-reported or verified vaccine status may not be sufficient to detect this association.

Anti-oxidized low-density lipoprotein antibodies in chronic heart failure

Oxidative stress may play a significant role in the pathogenesis of heart failure (HF). Antibodies to oxidized low-density lipoprotein (oxLDL Abs) reflect an immune response to LDL over a prolonged period and may represent long-term oxidative stress in HF. The oxLDL plasma level is a useful predictor of mortality in HF patients, and measurement of the oxLDL Abs level may allow better management of those patients. Antibodies to oxLDL also significantly correlate with the New York Heart Association score. Hypercholesterolemia, smoking, hypertension, and obesity are risk factors for atherosclerotic coronary heart disease (CHD) leading to HF, but these factors account for only one-half of all cases, and understanding of the pathologic process underlying HF remains incomplete. Nutrients with antioxidant properties can reduce the susceptibility of LDL to oxidation. Antioxidant therapy may be an adjunct to lipid-lowering, angiotensin converting enzyme inhibition and metformin (in diabetes) therapy for the greatest impact on CHD and HF. Observational data suggest a protective effect of antioxidant supplementation on the incidence of HD. This review summarizes the data on oxLDL Abs as a predictor of morbidity and mortality in HF patients.

Post-menopausal hormone therapy reduces autoantibodies to oxidized apolipoprotein B100

The aim of the study was to verify whether post-menopausal hormone replacement therapy (HRT) modifies autoantibody titers against oxidized low-density lipoprotein (LDL) (anti-LDLoxi), against epitopes of oxidized apolipoprotein B100 and common carotid intima-media thickness (IMT) in these women. Sixty-eight women in pre-menopause (PMW) and 216 in post-menopause (POMW) were recruited; eighty-three had undergone HRT for at least 12 months, where 48 received conjugated estrogens alone (EHRT) and 35 received conjugated estrogen and medroxyprogesterone acetate (CHRT). ELISA was used to determine autoantibodies. Lipoprotein lipase (LPL), hepatic lipase (HL), cholesterol ester transfer protein (CETP) and phospholipid transfer protein (PLTP) activities were assayed by radiometric methods. IMT was measured using Doppler ultrasound. Anti-oxidized LDL and anti-D antibodies increased by 40% (p ≤ 0.003) and 42% (p ≤ 0.006), respectively, with menopause. There was a surprising and significant 7% reduction in anti-D2 antibody titers with HRT (p ≤ 0.050), indicating a positive effect of treatment on the immune response to oxidized LDL. Combined HRT decreased activities of HL and LPL. HRT did not change common carotid IMT, which was increased by 32% as expected after menopause (p ≤ 0.030). This study describes, for the first time, the protective effect of HRT on decreasing autoantibody titers against oxidized apolipoprotein B in LDL.

Efeitos de autoanticorpos antilipoproteína lipase, antilipoproteína de baixa densidade e antilipoproteína de baixa densidade oxidada sobre o metabolismo lipídico e aterosclerose no lúpus eritematoso sistêmico

Premature development of atherosclerosis in systemic lupus erythematosus has been widely reported. Anti-lipoprotein lipase antibody may be one cause contributing to this disorder. To assess the extent of coronary risk due to autoimmune antibodies in terms of carotid plaque in lupus patients. We compared 114 documented lupus patients with 111 normal controls matched for sex and age. Anti-lipoprotein lipase (A-LPL), anti-oxidized low density lipoprotein (A-OXLDL), and anti-low density lipoprotein (A-LDL) were measured by enzme-linked immunoabsorbent assay. Low density lipoprotein-triglyceride (LDL-Trig) and high density lipoprotein-triglyceride (HDL-Trig) were also measured. Plaque was measured by bilateral carotid ultrasound. 45.6% of patients tested positive for A-LPL, and 34.4% for A-OXLDL. 44% of normal controls tested positive for A-LPL, and 20% for A-OXLDL. Risk increased sharply in subgroups with increased antibody levels. Patients with A-LPL and A-OXLDL > 0.40 (n = 12) showed coronary risk correlations of: A-LPL x LDL-Trig = 0.7008, P = 0.0111; bilateral ultrasound vs total cholesterol = 0.62205, P = 0.0308; LDL-Trig vs myocardial infarction (MI) = 0.76562, P = 0.0037; total triglycerides vs MI = 0.78191, P = 0.0027); LDL-Trig/LDL-cholesterol vs MI = 0.80493, P = 0.0016; A-OXLDL vs USBL = 0.71930, P = 0.0084. Correlations of SLEDAI with risk variables were highly significant only in subgroups of elevated antibody levels (SLEDAI x A-OXLDL = 0.70366, P = 0.0107). A-LPL initiates the development of LDL mutations, followed by antibody production, plaque formation and coronary risk in some SLE patients.

Anti‐oxidized LDL antibody levels are reduced in women with hypertension

Previous studies have suggested that hypertension may be associated with increased oxidized low-density lipoprotein (LDL). Increased in vitro oxidizability of LDL or elevated titers of anti-oxidized LDL antibodies have been shown in subjects with essential hypertension. However, the relationship between oxidized LDL and hypertension is equivocal. We examined the association between hypertension and levels of IgG anti-oxidized LDL antibodies in a group of women from the general population. The study included 619 women classified according to their blood pressure values. IgG anti-oxidized LDL antibodies were measured by enzyme-linked immunosorbent assay and the women were classified as being above or below the 50th percentile. Hypertension was present in 54.3% of the women. These women had significantly lower levels of IgG anti-oxidized LDL antibodies than the normotensive women (0.280 +/- 0.117 vs. 0.336 +/- 0.125, P < 0.001). Both systolic and the diastolic blood pressures showed a significant negative correlation with the levels of IgG anti-oxidized LDL antibodies (r = -0.204, P < 0.001; r = -0.225, P < 0.001, respectively). Women with IgG anti-oxidized LDL antibody levels above the 50th percentile had a lower prevalence of hypertension than those with IgG anti-oxidized LDL antibody levels below the 50th percentile (40.2% vs. 59.8%) (P < 0.001). Women with hypertension had lower levels of IgG anti-oxidized LDL antibodies than normotensive women.

Anti‐oxidized low‐density lipoprotein antibody levels are associated with the development of type 2 diabetes mellitus

Anti-oxidized low-density lipoprotein (LDL) antibodies are associated with the oxidative capacity of plasma, but whether they protect or promote diabetes is unknown. We undertook a prospective study to determine the predictive capacity of anti-oxidized LDL antibodies for the onset of type 2 diabetes mellitus (T2DM). We selected 391 non-diabetic women aged 18-65 years. The subjects were classified as being normal (oral glucose test tolerance normal, OGTT-N), or having impaired glucose tolerance (IGT), impaired fasting glucose (IFG) or T2DM according to their baseline glucose levels and after an OGTT. The same subjects were studied six years later. The levels of anti-oxidized LDL antibodies were classified as above or below the 50th percentile. Of the women who were OGTT-N at the start of the study and who had anti-oxidized LDL antibody levels below the 50th percentile, only 65.1% were still OGTT-N after 6 years versus 79.5% of those who had anti-oxidized LDL antibody levels above the 50th percentile (P = 0.015). Women who had IGT or IFG at the start of the study whose anti-oxidized LDL antibody levels were below the 50th percentile had a relative risk of 9.79 (95% confidence interval, 1.40-68.45) of developing diabetes (P < 0.001). Logistic regression analysis showed that the variables predicting the development of a carbohydrate metabolism disorder in the women after 6 years were body mass index (P < 0.001) and the levels of anti-oxidized LDL antibodies (P = 0.042). Levels of anti-oxidized LDL antibodies are independent predictors for the development of T2DM in women.

Oxidized low density lipoproteins induce a pathologic response by retinal pigmented epithelial cells

The accumulation of apolipoprotein B100 lipoproteins in Bruch membrane is an early event thought to promote age-related macular degeneration (AMD). Immunohistochemistry using an anti-oxidized low density lipoprotein antibody on 10 AMD specimens showed staining in Bruch membrane including basal deposits, a marker of AMD. To determine whether retinal pigmented epithelial cells develop a pathologic phenotype after interaction with lipoproteins, ARPE-19 cells were exposed to low density lipoproteins (LDL) or oxidized LDLs (oxLDL). Analysis using the Affymetrix U133 Plus 2.0 (Affymetrix, Inc., Santa Clara, CA, USA) gene chip showed physiological and pathological transcriptional responses after LDL and oxLDL treatment, respectively. LDL induced a down-regulation of cholesterol biosynthesis genes while oxLDL induced transcriptional alterations in genes related to lipid metabolism, oxidative stress, inflammation and apoptosis. Electrospray mass spectrometry showed that oxLDL, but not LDL induced large cellular increases of sphingomyelin, ceramides, and cholesteryl esters. With TUNEL labeling, oxLDL caused 14.6% apoptosis compared to <1% after LDL. Addition of an inhibitor of sphingomyelin synthase inhibited this apoptosis by 41%. These data support the hypothesis that oxidized lipoproteins are one trigger for initiating early events in the pathogenesis of AMD.

Anti-oxidized low-density lipoprotein antibodies in myeloperoxidase–positive vasculitis patients preferentially recognize hypochlorite-modified low density lipoproteins

Many patients surviving vasculitis are prone to accelerated atherosclerosis and often have enhanced levels of antibodies to oxidized low-density lipoprotein (oxLDL). To measure anti-oxLDL antibodies, oxidation of LDL is achieved with copper (Cu) or malondialdehyde (MDA). Because, in vivo, LDL may be oxidized with myeloperoxidase (MPO) or its product hypochlorite, we measured anti-hypochlorite LDL antibodies in patients with vasculitis, haemodialysis patients and healthy controls. A newly developed enzyme-linked immunosorbent assay (ELISA) was used to detect antibodies to oxLDL as modified by hypochlorite. Results are compared with data obtained by standard LDL oxidation using MDA-LDL or Cu-LDL as substrate. Results were compared between anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) patients (n = 93), haemodialysis (HD) patients (n = 59) and healthy controls (HC; n = 43). Furthermore, patients with MPO-ANCA-associated vasculitis (n = 47) were compared with patients with proteinase 3 (PR3)-ANCA associated vasculitis (n = 46). Optimal cut-off points were determined by receiver operator characteristic (ROC) curve analysis. Anti-oxLDL antibodies are enhanced in AAV patients (MDA-LDL and hypochlorite-LDL) and in HD patients (hypochlorite-LDL), when compared to HC. Furthermore, patients with MPO-ANCA-associated vasculitis had higher levels of antibodies to hypochlorite-LDL than patients with PR3-ANCA-associated vasculitis. Our newly developed assay, in which hypochlorite-LDL is used as substrate, seems a more sensitive assay than traditional assays to measure oxLDL antibodies. Furthermore, our results suggest that enhanced MPO-mediated LDL oxidation occurs in patients with MPO-ANCA.

Relationship of IgG and IgM autoantibodies to oxidized low density lipoprotein with coronary artery disease and cardiovascular events

The relationship between autoantibodies to oxidized low density lipoprotein (OxLDL) and coronary artery disease (CAD) remains controversial. IgM and IgG OxLDL autoantibodies to malondialdehyde (MDA)-modified LDL, copper oxidized low density lipoprotein (CuOxLDL), and oxidized cholesterol linoleate (OxCL), as well as apolipoprotein B-100 immune complexes (apoB-ICs), were measured in 504 patients undergoing clinically indicated coronary angiography. Patients were followed for cardiovascular events for a median of 4 years. In univariate analysis, IgM OxLDL autoantibodies and IgM apoB-ICs were inversely associated with the presence of angiographically determined CAD, whereas IgG OxLDL autoantibodies and IgG apoB-ICs were positively associated. In logistic regression analysis, compared with the first quartile, patients in the fourth quartile of IgM OxLDL autoantibodies and apoB-ICs showed a lower probability of angiographically determined CAD (>50% diameter stenosis). Odds ratios and (95% confidence intervals) were as follows: MDA-LDL, 0.51 (0.32-0.82; P = 0.005); CuOxLDL, 0.63 (0.39-1.01; P = 0.05); OxCL, 0.63 (0.39-1.01; P = 0.05); and apoB-IC, 0.55 (0.34-0.88; P = 0.013). These relationships were accentuated in the setting of hypercholesterolemia, with the highest IgM levels showing the lowest risk of CAD for the same level of hypercholesterolemia. Multivariable analysis revealed that neither IgM or IgG OxLDL autoantibodies nor apoB-ICs were independently associated with angiographically determined CAD or cardiovascular events. In conclusion, IgG and IgM OxLDL biomarkers have divergent associations with CAD in univariate analysis but are not independent predictors of CAD or clinical events.

The fine-tuning of anti-oxidized low-density lipoprotein antibodies in cardiovascular disease and thrombosis

Anti-oxidised low-density lipoprotein (anti-oxLDL) antibodies are a heterogeneous group of autoantibodies including both pathogenic and protective subsets. Whereas in most studies the levels of anti-oxLDL antibodies were associated with enhanced atherosclerosis as evaluated by different methods, immunization with oxLDL leads to elevated levels of anti-oxLDL and protection against atherosclerosis. Anti-oxLDL can also be used for immunomodulation of atherosclerosis (i.e. possible therapeutic use of intravenous immunoglobulin, oral tolerance). More specific autoantibodies out of total anti-oxLDL should be selected, for instance, anti-oxLDL/beta-2-glycoprotein I complex, hence defining the fine-tuning of anti-oxLDL antibodies might detect which autoantibodies are pathogenic and which can be used therapeutically.

Serotonin Derivatives, Major Safflower (Carthamus tinctorius L.) Seed Antioxidants, Inhibit Low-Density Lipoprotein (LDL) Oxidation and Atherosclerosis in Apolipoprotein E-Deficient Mice

The effects of defatted safflower seed extract and its phenolic constituents, serotonin derivatives, on atherosclerosis were studied. Ethanol-ethyl acetate extract of safflower seeds (SSE) inhibited low-density lipoprotein (LDL) oxidation induced in vitro by an azo-containing free-radical initiator V70 or copper ions. Two serotonin derivatives [N-(p-coumaroyl)serotonin, CS; N-feruloylserotonin, FS] and their glucosides were identified as the major phenolic constituents of the extract. The study with chemically synthesized materials revealed that a majority of the antioxidative activity of SSE was attributable to the aglycones of these two serotonin derivatives. Orally administered CS and FS suppressed CuSO(4)-induced plasma oxidation ex vivo. Long-term (15 week) dietary supplementation of SSE (1.0 wt %/wt) and synthetic serotonin derivatives (0.2-0.4%) significantly reduced the atherosclerotic lesion area in the aortic sinus of apolipoprotein E-deficient mice (29.2-79.7% reduction). The plasma level of both lipid peroxides and anti-oxidized LDL autoantibody titers decreased concomitantly with the reduction of lesion formation. Serotonin derivatives were detected as both intact and conjugated metabolites in the plasma of C57BL/6J mice fed on 1.0% SSE diet. These findings demonstrate that serotonin derivatives of SSE are absorbed into circulation and attenuate atherosclerotic lesion development possibly because of the inhibition of oxidized LDL formation through their strong antioxidative activity.