Autoantibodies to oxidized LDL and cardiovascular risk: the Framingham Offspring Study

Role of Antibodies and Their Specificities in Atherosclerotic Cardiovascular Disease

Atherosclerosis is a lipid-driven chronic inflammatory disease that is modulated by innate and adaptive immunity including humoral immunity. Importantly, antibody alterations achieved by genetic means or active and passive immunization strategies in preclinical studies can improve or aggravate atherosclerosis. Additionally, a wide range of epidemiological data demonstrate not only an association between the total levels of different antibody isotypes but also levels of antibodies targeting specific antigens with atherosclerotic cardiovascular disease. Here, we discuss the potential role of atherogenic dyslipidemia on the antibody repertoire and review potential antibody-mediated effector mechanisms involved in atherosclerosis development highlighting the major atherosclerosis-associated antigens that trigger antibody responses.

Humoral immunity in atherosclerosis and myocardial infarction: from B cells to antibodies

Immune mechanisms are critically involved in the pathogenesis of atherosclerosis and its clinical manifestations. Associations of specific antibody levels and defined B cell subsets with cardiovascular disease activity in humans as well as mounting evidence from preclinical models demonstrate a role of B cells and humoral immunity in atherosclerotic cardiovascular disease. These include all aspects of B cell immunity, the generation of antigen-specific antibodies, antigen presentation and co-stimulation of T cells, as well as production of cytokines. Through their impact on adaptive and innate immune responses and the regulation of many other immune cells, B cells mediate both protective and detrimental effects in cardiovascular disease. Several antigens derived from (oxidised) lipoproteins, the vascular wall and classical autoantigens have been identified. The unique antibody responses they trigger and their relationship with atherosclerotic cardiovascular disease are reviewed. In particular, we focus on the different effector functions of specific IgM, IgG, and IgE antibodies and the cellular responses they trigger and highlight potential strategies to target B cell functions for therapy.

Circulating Biomarkers Reflecting Destabilization Mechanisms of Coronary Artery Plaques: Are We Looking for the Impossible?

Despite significant strides to mitigate the complications of acute coronary syndrome (ACS), this clinical entity still represents a major global health burden. It has so far been well-established that most of the plaques leading to ACS are not a result of gradual narrowing of the vessel lumen, but rather a result of sudden disruption of vulnerable atherosclerotic plaques. As most of the developed imaging modalities for vulnerable plaque detection are invasive, multiple biomarkers were proposed to identify their presence. Owing to the pivotal role of lipids and inflammation in the pathophysiology of atherosclerosis, most of the biomarkers originated from one of those processes, whereas recent advancements in molecular sciences shed light on the use of microRNAs. Yet, at present there are no clinically implemented biomarkers or any other method for that matter that could non-invasively, yet reliably, diagnose the vulnerable plaque. Hence, in this review we summarized the available knowledge regarding the pathophysiology of plaque instability, the current evidence on potential biomarkers associated with plaque destabilization and finally, we discussed if search for biomarkers could one day bring us to non-invasive, cost-effective, yet valid way of diagnosing the vulnerable, rupture-prone coronary artery plaques.

Simultaneous detection and quantification of DNA and protein biomarkers in spectrum of cardiovascular diseases in a microfluidic microbead chip

The rapid and simultaneous detection of DNA and protein biomarkers is necessary to detect the outbreak of a disease or to monitor a disease. For example, cardiovascular diseases are a major cause of adult mortality worldwide. We have developed a rapidly adaptable platform to assess biomarkers using a microfluidic technology. Our model mimics autoantibodies against three proteins, C-reactive protein (CRP), brain natriuretic peptide (BNP), and low-density lipoprotein (LDL). Cell-free mitochondrial DNA (cfmDNA) and DNA controls are detected via fluorescence probes. The biomarkers are covalently bound on the surface of size- (11–15 μm) and dual-color encoded microbeads and immobilized as planar layer in a microfluidic chip flow cell. Binding events of target molecules were analyzed by fluorescence measurements with a fully automatized fluorescence microscope (end-point and real-time) developed in house. The model system was optimized for buffers and immobilization strategies of the microbeads to enable the simultaneous detection of protein and DNA biomarkers. All prime target molecules (anti-CRP, anti-BNP, anti-LDL, cfmDNA) and the controls were successfully detected both in independent reactions and simultaneously. In addition, the biomarkers could also be detected in spiked human serum in a similar way as in the optimized buffer system. The detection limit specified by the manufacturer is reduced by at least a factor of five for each biomarker as a result of the antibody detection and kinetic experiments indicate that nearly 50 % of the fluorescence intensity is achieved within 7 min. For rapid data inspection, we have developed the open source software digilogger, which can be applied for data evaluation and visualization.

Anti-Oxidized LDL Antibodies and Coronary Artery Disease: A Systematic Review

Antibodies to oxidized LDL (oxLDL) may be associated with improved outcomes in cardiovascular disease. However, analysis is restricted by heterogenous study design and endpoints. Our objective was to conduct a comprehensive systematic review assessing anti-oxLDL antibodies in relation to coronary artery disease (CAD). Through a systematic literature search, we identified all studies assessing the relationship of either, IgG or IgM ox-LDL/ copper-oxLDL/ malondialdehyde-LDL, with coronary atherosclerosis or cardiovascular events in populations with, and without, established CAD. Systematic review best practices were adhered to and study quality was assessed. An initial electronic database search identified 2059 records, which was subsequently followed by abstract and full-text review. Finally, we included 18 studies with over 1811 patients with CAD. The studies varied according to populations studied, conventional cardiovascular risk factors and interventional modalities used to assess CAD. IgM anti-oxLDL antibodies were found to indicate protection from more severe CAD and possibly cardiovascular events, whilst the relationship with IgG is more complex and difficult to elucidate, with studies reporting divergent results. In this systematic review, there is evidence that suggests a relationship between anti-oxLDL antibodies and CAD, especially for the IgM subclass. However, further studies, with well-characterized prospective cohorts, will be important to clarify these associations.

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.

Atherothrombosis and Oxidative Stress: Mechanisms and Management in Elderly

SIGNIFICANCE

The incidence of cardiovascular events (CVEs) increases with age, representing the main cause of death in an elderly population. Aging is associated with overproduction of reactive oxygen species (ROS), which may affect clotting and platelet activation, and impair endothelial function, thus predisposing elderly patients to thrombotic complications. Recent Advances: There is increasing evidence to suggest that aging is associated with an imbalance between oxidative stress and antioxidant status. Thus, upregulation of ROS-producing enzymes such as nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and myeloperoxidase, along with downregulation of antioxidant enzymes, such as superoxide dismutase and glutathione peroxidase, occurs during aging. This imbalance may predispose to thrombosis by enhancing platelet and clotting activation and eliciting endothelial dysfunction. Recently, gut-derived products, such as trimethylamine N-oxide (TMAO) and lipopolysaccharide, are emerging as novel atherosclerotic risk factors, and gut microbiota composition has been shown to change by aging, and may concur with the increased cardiovascular risk in the elderly.

CRITICAL ISSUES

Antioxidant treatment is ineffective in patients at risk or with cardiovascular disease. Further, anti-thrombotic treatment seems to work less in the elderly population.

FUTURE DIRECTIONS

Interventional trials with antioxidants targeting enzymes implicated in aging-related atherothrombosis are warranted to explore whether modulation of redox status is effective in lowering CVEs in the elderly. Antioxid. Redox Signal. 27, 1083-1124.

Clinical Application of NOX Activity and Other Oxidative Biomarkers in Cardiovascular Disease: A Critical Review

SIGNIFICANCE

The oxidative stress theory of atherosclerosis is based on the assumption that the production of reactive oxidant species (ROS) by blood, as well as resident cells of the artery wall, elicits the formation of oxidized low-density lipoproteins (ox-LDL), which, in turn, promotes a series of inflammatory responses, ultimately leading to atherosclerotic plaque. This theory prompted the development of new laboratory methodologies that aimed at assessing the relationship between oxidative stress and clinical progression of human atherosclerosis.

CRITICAL ISSUES

Markers assessing the oxidation of phospholipid and protein components of LDL were among the first to be developed. Clinical trials included cross-sectional as well as retrospective and prospective studies that, however, provided equivocal results. Thus, clear evidence that oxidative biomarkers add more to the risk stratification by common atherosclerotic risk factors is still lacking.

RECENT ADVANCES

More recently, the analysis of oxidative stress focused on enzymatic pathways generating ROS, such as NADPH oxidase and myeloperoxidase (MPO). Experimental and clinical studies suggest that both enzymes may be implicated in promoting atherosclerotic disease. Novel laboratory methodologies have been, therefore, developed to study NADPH oxidase and MPO in patients with stable atherosclerosis as well as in patients with acute coronary and cerebro-vascular syndromes.

FUTURE DIRECTIONS

This review will analyze the strengths and weaknesses of the current methodology to study these enzymes in human atherosclerosis with particular regard to their clinical application in several settings of cardiovascular disease. Clinical methodology and results of previous studies with regard to markers of LDL oxidation have also been reviewed as a useful background for the future development of clinical trials.

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.

The role of oxidized low-density lipoproteins in atherosclerosis: the myths and the facts

The oxidative modification hypothesis of atherosclerosis, which assigns to oxidized low-density lipoproteins (LDLs) a crucial role in atherosclerosis initiation and progression, is still debated. This review examines the role played by oxidized LDLs in atherogenesis taking into account data derived by studies based on molecular and clinical approaches. Experimental data carried out in cellular lines and animal models of atherosclerosis support the proatherogenic role of oxidized LDLs: (a) through chemotactic and proliferating actions on monocytes/macrophages, inciting their transformation into foam cells; (b) through stimulation of smooth muscle cells (SMCs) recruitment and proliferation in the tunica intima; (c) through eliciting endothelial cells, SMCs, and macrophages apoptosis with ensuing necrotic core development. Moreover, most of the experimental data on atherosclerosis-prone animals benefiting from antioxidant treatment points towards a link between oxidative stress and atherosclerosis. The evidence coming from cohort studies demonstrating an association between oxidized LDLs and cardiovascular events, notwithstanding some discrepancies, seems to point towards a role of oxidized LDLs in atherosclerotic plaque development and destabilization. Finally, the results of randomized clinical trials employing antioxidants completed up to date, despite demonstrating no benefits in healthy populations, suggest a benefit in high-risk patients. In conclusion, available data seem to validate the oxidative modification hypothesis of atherosclerosis, although additional proofs are still needed.

Auto-antibodies as emergent prognostic markers and possible mediators of ischemic cardiovascular diseases

During the last 15 years, a growing body of evidence supported the fact that auto-antibodies represent not only emergent markers but also active mediators of cardiovascular disease (CVD), clinically represented mostly by acute coronary syndrome (ACS) and stroke. There is a contrasted relationship between auto-antibodies and CVD, some being protective, while others acting as potential risk factors. Therefore, we performed a review of the literature on the respective cardiovascular prognostic value of the most relevant auto-antibodies in ACS and stroke, and their putative pathophysiological properties in atherogenesis. This review highlights auto-antibodies as active modulators of the innate immune system in atherogenesis (either toward a pro- or anti-inflammatory response), or by affecting basal heart rate regulation (anti-apoA-1 IgG). Given their apparent prognostic independency towards traditional cardiovascular risk factors, the data available in the literature indicates that some of those auto-antibodies could be of valuable help for cardiovascular risk stratification in the future, especially because their deleterious effects have been shown to be potentially abrogated in vivo and in vitro by existing therapeutic modalities. Although evidence in humans is currently lacking, these studies may open innovative therapeutic perspectives for CVD in the future.

Evidence on the pathogenic role of auto-antibodies in acute cardiovascular diseases

Atherothrombosis is the major determinant of acute ischaemic cardiovascular events, such as myocardial infarction and stroke. Inflammatory processes have been linked to all phases of atherogenesis In particular, the identification of autoimmunity mediators in the complex microenvironment of chronic inflammation has become the focus of attention in both early and advanced atherogenic processes. Auto-antibodies against self-molecules or new epitopes generated by oxidative processes infiltrate atherosclerotic plaques and were shown to modulate the activity of immune cells by binding various types of receptors. However, despite mounting evidence for a pathophysiological role of autoantibodies in atherothrombosis, the clinical relevance for circulating autoantibodies in cardiovascular outcomes is still debated. This review aims at illustrating the mechanisms by which different types of autoantibodies might either promote or repress atherothrombosis and to discuss the clinical studies assessing the role of auto-antibodies as prognostic biomarkers of plaque vulnerability.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Oxidative stress biomarkers as predictors of cardiovascular disease

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

Clinical significance of the humoral immune response to modified LDL

Human low density lipoprotein (LDL) undergoes oxidation and glycation in vivo. By themselves, oxidized LDL (oxLDL) and AGE-LDL have proinflammatory properties and are considered atherogenic. But the atherogenicity of these lipoproteins are significantly increased as a consequence of the formation of immune complexes (IC) involving specific autoantibodies. OxLDL and AGE antibodies have been shown to be predominantly of the IgG1 and IgG3 isotypes. OxLDL antibodies are able to activate the complement system by the classical pathway and to induce FcR-mediated phagocytosis. In vitro and ex vivo studies performed with modified LDL-IC have proven their pro-inflammatory and atherogenic properties. Clinical studies have demonstrated that the levels of circulating modified LDL-IC correlate with parameters indicative of cardiovascular and renal disease in diabetic patients and other patient populations. The possibility that spontaneously formed or induced modified LDL antibodies (particularly IgM oxLDL antibodies) may have a protective effect has been suggested, but the data is unclear and needs to be further investigated.

From hyperglycemia to AGE-RAGE interaction on the cell surface: a dangerous metabolic route for diabetic patients

BACKGROUND

Diabetes mellitus constitutes a serious public health problem. Recent advances in therapies are unable to control its vascular complications. New medications have been suggested but without comprehensive knowledge of the signaling pathways induced by hyperglycemia.

OBJECTIVE

To review the mechanisms of the inducer and effector phases of the metabolic cascade in diabetes, with emphasis on the steps that have been targeted to date The route from hyperglycemia to advanced glycation end products (AGE)-receptor of advanced glycation end products (RAGE) complex formation is suggested as a target for new therapies.

METHODS

A review of literature, including historical papers and recent manuscripts.

RESULTS

All the components of the suggested route are initially activated or indirectly formed due to hyperglycemia via a two-phase cascade that represents a dangerous metabolic route, especially for diabetics. Recent experiments with new drugs and clinical trials targeting this pathway are examined.

CONCLUSIONS

In order to control vascular injury in diabetes, several steps in the cascade need to be inhibited simultaneously together with aggressive glycemic control.

Ethnic variation in levels of circulating IgG autoantibodies to oxidised low-density lipoprotein

BACKGROUND

Oxidised low-density lipoprotein (Ox-LDL) plays a key role in atherosclerosis. Our aim was to determine whether serum autoantibodies against Ox-LDL (Ab Ox-LDL) differ by ethnic group.

DESIGN AND METHODS

Soluble serum Ab Ox-LDL levels were measured in 250 white (113 females), 169 African origin (91 females) and 196 South Asian (92 females) individuals from the Wandsworth Heart and Stroke Study (WHSS) population. All were free from coronary heart disease (CHD), stroke, other cardiovascular disease, diabetes, drug therapy for hypertension or high lipids, hormone replacement therapy or oral contraceptive pill.

RESULTS

There were no sex differences in levels of Ab Ox-LDL, but levels were higher in non-smokers (430U/L [95% CI 471-596]) than in smokers (384U/L [316-468]) (p<0.009). Age- and sex-adjusted levels of Ab Ox-LDL were higher in people of African origin and South Asians compared to whites. This difference was maintained in South Asian women following adjustment for multiple risk factors (82% [21-175]; p=0.004). Ab Ox-LDL levels were negatively associated with serum triglycerides and positively associated with sVCAM-1.

CONCLUSIONS

Higher IgG Ab to Ox-LDL are associated with higher levels of sVCAM-1 and, are elevated in female South Asian individuals who have an increased risk of atherosclerosis compared to whites.

Oxidized to non-oxidized lipoprotein ratios are associated with arteriosclerosis and the metabolic syndrome in diabetic patients

BACKGROUND AND AIM

Type 2 diabetic patients have a greater prevalence of the metabolic syndrome, oxidative stress and accelerated atherosclerosis, compared to non-diabetics. We examined the association between biomarkers of lipid peroxidation and the presence of atherosclerosis and the metabolic syndrome in diabetic patients.

METHODS AND RESULTS

We studied oxidized LDL (OxLDL), OxLDL/LDL, OxLDL/HDL, lipoperoxides, autoantibodies against OxLDL (OxLDL-Ab), diene formation of LDL (lag phase), vitamin E, vitamin E/cholesterol and PON1 polymorphisms (-108C>T, 55T>A, and 192A>G) in 166 non-smoking type 2 diabetic patients, 119 fulfilling the criteria for the metabolic syndrome, 73 with atherosclerosis and 93 without atherosclerosis. Patients with macrovascular disease had higher values of OxLDL/LDL (11%; P=0.016), OxLDL/HDL (18%; P=0.024) and OxLDL-Ab (12%; P=0.046). OxLDL/LDL and OxLDL/HDL were correlated with the number of components of the metabolic syndrome (P<0.001). PON1 polymorphisms were not associated to LDL oxidation markers, only PON1 (-108TT) was weakly associated with higher OxLDL-Ab concentrations (22%; P=0.040) in patients with atherosclerosis.

CONCLUSION

OxLDL/LDL, OxLDL/HDL and OxLDL-Ab are the most useful clinical parameters of lipoprotein oxidation for discriminating the presence of macrovascular disease in diabetic patients. The presence of the metabolic syndrome in these patients is also associated with an increase in the oxidized lipoprotein ratios.

Targets for intervention in dyslipidemia in diabetes

Treatment for dyslipidemia in diabetes reduces cardiovascular events. Diabetes is associated with major abnormalities in fatty acid metabolism. The resulting disturbance results in an abnormal lipoprotein cascade from the large chylomicron through to the small HDL particle. This suggests that drugs that alter formation of the chylomicron particle might have a very important role in diabetic dyslipidemia. Achieving normal glycemia will reverse the abnormalities in fatty acid metabolism, but this is difficult, particularly as the disease progresses. Genes that regulate cholesterol absorption and excretion have been described (Niemann Pick C1-like 1 [NPC1-L1] and ATP binding cassette proteins [ABC] G5 and G8). An effective NPC1-L1 inhibitor (ezetimibe) improves the reduction in cholesterol caused by statins. Agonists of ABCG5 and G8 may become important in the treatment of dyslipidemia. Microsomal triglyceride transfer protein (MTP) is responsible for the assembly of the chylomicron and VLDL particles. New MTP inhibitors, acting only on the intestine, are exciting possible treatments. The advisability of sitosterol-enriched foods to lower cholesterol may have to be reassessed for patients with diabetes, since these products may lead to an increase in chylomicron sitosterol in diabetic patients. More successful treatment of diabetic dyslipidemia is essential if we are to reduce the burden of cardiovascular disease so commonly found in diabetes.

Atherogenic Antiphospholipid Antibodies in Antiphospholipid Syndrome

Macrophage uptake of oxidized LDL (oxLDL) plays a critical role in early stages of atherosclerosis. We previously reported that oxLDL forms stable complexes with beta2-glycoprotein I (beta2GPI), and that these complexes were frequently present in the sera of patients with systemic lupus erythematosus (SLE) and/or antiphospholipid syndrome (APS). oxLDL/beta2GPI complexes were shown to be antigenic targets for autoantibodies present in APS. To understand the role of autoantibodies in accelerated atherosclerosis of SLE and APS, we investigated the binding characteristics of beta2GPI and oxLDL to mouse macrophages, and the effect of anti-beta2GPI and anti-oxLDL autoantibodies on this macrophage binding. IgM anti-oxLDL antibody (derived from Apoe -/- mouse) showed inhibitory effect on oxLDL binding to macrophages. Although beta2GPI partly inhibited oxLDL binding to macrophages, IgG anti-beta2GPI autoantibody (derived from APS model mouse) showed pro-atherogenic property by promoting the binding of oxLDL/beta2GPI to macrophages.