Antibodies to beta 2-glycoprotein I and clinical manifestations in patients with systemic lupus erythematosus

Deciphering the clinical significance of longitudinal antiphospholipid antibody titers

In antiphospholipid syndrome (APS), the risk of clinical manifestations increases with higher titers of antiphospholipid antibodies (aPL). Despite the adoption of aPL titers in the classification approach to aPL-positive subjects, the value of longitudinal monitoring of those titers in the follow-up is still debated, being well studied only in systemic lupus erythematosus (SLE). The literature suggests that the rate of aPL positivity decreases during follow-up in primary APS, estimating that seroconversion occurs in between 8.9 and 59% of patients over time. Negativisation of aPL occurs more frequently in asymptomatic aPL carriers than in patients with full-blown APS as well as in subjects with single aPL positivity or low aPL antibody titers. In patients with SLE, aPL typically behave fluctuating from positive to negative and back again in the course of follow-up. The few studies assessing the longitudinal course of aPL positivity with no associated systemic connective tissue disease reported a progressive decrement of aPL titers over time, in particular of antibodies against β2 glycoprotein I (antiβ2GPI) and cardiolipin (aCL) of IgG isotype. After a thrombotic event, aPL titers tend to decrease, as emerged from cohorts of both primary and secondary APS. Hydroxychloroquine has been identified as the most effective pharmacological agent to reduce aPL titers, with multiple studies demonstrating a parallel reduction in thrombosis rate. This review addresses available evidence on the significance of aPL titer fluctuation from clinical, therapeutic and pathogenic perspectives.

Laboratory Diagnosis of Antiphospholipid Syndrome: Insights and Hindrances

Diagnosis of antiphospholipid syndrome (APS) requires the presence of a clinical criterion (thrombosis and/or pregnancy morbidity), combined with persistently circulating antiphospholipid antibodies (aPL). Currently, laboratory criteria aPL consist of lupus anticoagulant (LAC), anticardiolipin antibodies (aCL) IgG/IgM, and anti-β2 glycoprotein I antibodies (aβ2GPI) IgG/IgM. Diagnosis and risk stratification of APS are complex and efforts to standardize and optimize laboratory tests have been ongoing since the initial description of the syndrome. LAC detection is based on functional coagulation assays, while aCL and aβ2GPI are measured with immunological solid-phase assays. LAC assays are especially prone to interference by anticoagulation therapy, but strategies to circumvent this interference are promising. Alternative techniques such as thrombin generation for LAC detection and to estimate LAC pathogenicity have been suggested, but are not applicable yet in routine setting. For aCL and aβ2GPI, a lot of different assays and detection techniques such as enzyme-linked immunosorbent and chemiluminescent assays are available. Furthermore, a lack of universal calibrators or standards results in high variability between the different solid-phase assays. Other non-criteria aPL such as anti-domain I β2 glycoprotein I and antiphosphatidylserine/prothrombin antibodies have been suggested for risk stratification purposes in APS, while their added value to diagnostic criteria seems limited. In this review, we will describe laboratory assays for diagnostic and risk evaluation in APS, integrating applicable guidelines and classification criteria. Current insights and hindrances are addressed with respect to both laboratory and clinical implications.

Modulating Autoimmunity against LDL: Development of a Vaccine against Atherosclerosis

Atherosclerosis is a chronic inflammatory disease of the arterial wall that leads to the build-up of occluding atherosclerotic plaques. Its clinical sequelae, myocardial infarction and stroke, represent the most frequent causes of death worldwide. Atherosclerosis is a multifactorial pathology that involves traditional risk factors and chronic low-grade inflammation in the atherosclerotic plaque and systemically. This process is accompanied by a strong autoimmune response that involves autoreactive T cells in lymph nodes and atherosclerotic plaques, as well as autoantibodies that recognize low-density lipoprotein (LDL) and its main protein component apolipoprotein B (ApoB). In the past 60 years, numerous preclinical observations have suggested that immunomodulatory vaccination with LDL, ApoB, or its peptides has the potential to specifically dampen autoimmunity, enhance tolerance to atherosclerosis-specific antigens, and protect from experimental atherosclerosis in mouse models. Here, we summarize and discuss mechanisms, challenges, and therapeutic opportunities of immunomodulatory vaccination and other strategies to enhance protective immunity in atherosclerosis.

Gut Microbiota Dysbiosis in Systemic Lupus Erythematosus: Novel Insights into Mechanisms and Promising Therapeutic Strategies

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that was traditionally thought to be closely related to genetic and environmental risk factors. Although treatment options for SLE with hormones, immunosuppressants, and biologic drugs are now available, the rates of clinical response and functional remission of these drugs are still not satisfactory. Currently, emerging evidence suggests that gut microbiota dysbiosis may play crucial roles in the occurrence and development of SLE, and manipulation of targeting the gut microbiota holds great promises for the successful treatment of SLE. The possible mechanisms of gut microbiota dysbiosis in SLE have not yet been well identified to date, although they may include molecular mimicry, impaired intestinal barrier function and leaky gut, bacterial biofilms, intestinal specific pathogen infection, gender bias, intestinal epithelial cells autophagy, and extracellular vesicles and microRNAs. Potential therapies for modulating gut microbiota in SLE include oral antibiotic therapy, fecal microbiota transplantation, glucocorticoid therapy, regulation of intestinal epithelial cells autophagy, extracellular vesicle-derived miRNA therapy, mesenchymal stem cell therapy, and vaccination. This review summarizes novel insights into the mechanisms of microbiota dysbiosis in SLE and promising therapeutic strategies, which may help improve our understanding of the pathogenesis of SLE and provide novel therapies for SLE.

ApoB-Specific CD4+ T Cells in Mouse and Human Atherosclerosis

Atherosclerosis is a chronic inflammatory condition of the arterial wall that leads to the formation of vessel-occluding plaques within the subintimal space of middle-sized and larger arteries. While traditionally understood as a myeloid-driven lipid-storage disease, growing evidence suggests that the accumulation of low-density lipoprotein cholesterol (LDL-C) ignites an autoimmune response with CD4+ T-helper (TH) cells that recognize self-peptides from Apolipoprotein B (ApoB), the core protein of LDL-C. These autoreactive CD4+ T cells home to the atherosclerotic plaque, clonally expand, instruct other cells in the plaque, and induce clinical plaque instability. Recent developments in detecting antigen-specific cells at the single cell level have demonstrated that ApoB-reactive CD4+ T cells exist in humans and mice. Their phenotypes and functions deviate from classical immunological concepts of distinct and terminally differentiated TH immunity. Instead, ApoB-specific CD4+ T cells have a highly plastic phenotype, can acquire several, partially opposing and mixed transcriptional programs simultaneously, and transit from one TH subset into another over time. In this review, we highlight adaptive immune mechanisms in atherosclerosis with a focus on CD4+ T cells, introduce novel technologies to detect ApoB-specific CD4+ T cells at the single cell level, and discuss the potential impact of ApoB-driven autoimmunity in atherosclerosis.

Anti-β2-glycoprotein I antibodies

The relationship between presence of anti-β2-glycoprotein I autoantibodies (aβ2-GPI) and history of thrombosis is now widely known. However, differences in the methodology of aβ2-GPI detection have made the comparison of data from different laboratories extremely difficult. We discuss the significance of aβ2-GPI of the IgG, IgM and IgA isotypes, and our approach to developing an easier and more reproducible method for the detection of this autoantibody. In addition, we present data that shows that commercially available enzyme immunoassay plates differ regarding detectability of aβ2-GPI. Since the clinical significance of this heterogeneity is presently unclear, the set-up of the detection systems and interpretation of data need great care.

Risk Factors for Recurrent Thrombosis: Prospective Study of a Cohort of Japanese Systemic Lupus Erythematosus

Not only antiphospholipid antibodies (aPLs) but also other factors should be considered in assessing the risk of thrombosis development in patients with systemic lupus erythematosus (SLE) and antiphospholipid antibodies (aPLs). The kinds of risk factors, including past history of thrombotic event (PHTE), hypertension, hypercholesterolemia, diabetes mellitus (DM), obesity, and smoking, in conjunction with aPLs, that contribute to the development of new thrombotic events in patients with SLE and aPLs were studied prospectively over a 5-year observation period. One-hundred and sixty-six Japanese patients with SLE (55 patients with aPLs and 111 patients without aPLs) were examined and followed up for 5 years. Five major risk factors for ischemic coronary disease and stroke according to the Framingham heart cohort study were evaluated objectively in these patients. A significant difference was seen for 4 factors: past history of thrombotic event (PHTE; odds ratio: 101.93; 95% confidence interval: 12.29-845.22; p<0.0001), hypertension (odds ratio: 8.87; 95% CI: 2.58-30.53; p<0.001), DM (odds ratio: 5.42; 95% CI: 1.44-20.46; p<0.05), and lupus anticoagulant (LAC; odds ratio: 47.41; 95% CI: 5.88-382.03, p<0.0001) as aPLs, when the incidence of these risk factors was compared between patients with and without new thrombotic events. Furthermore, PHTE (odds ratio: 30.19, 95% CI: 1.33-683.13), hypertension (odds ratio: 15.44; 95% CI: 1.77-134.80), and LAC (odds ratio: 14.11; 95% CI: 0.48-412.42) showed higher odds ratios than DM (odds ratio: 11.53; 95% CI: 0.83-159.94) on multivariate logistic analysis as well as analysis of the combination of risk factors, suggesting that these are important risk factors for the development of new thrombotic events in patients with SLE and aPLs.

Oxidized LDL/β2-glycoprotein I complexes: new aspects in atherosclerosis

β2-glycoprotein I (β2GPI) is a major antigenic target for antiphospholipid antibodies. Oxidized low-density lipoprotein (oxLDL) is the principal lipoprotein found in atherosclerotic lesions, and it colocalizes with β2GPI and immunoreactive lymphocytes. oxLDL/β2GPI complexes appeared in the blood circulation of patients with diseases, such as systemic lupus erythematosus (SLE), antiphospholipid syndrome (APS), systemic sclerosis, diabetes mellitus and chronic renal diseases. Thus, the complexes may be associated with systemic and chronic inflammation of the vasculature. IgG anti-oxLDL/β2GPI complexes autoantibodies and their immune complexes were detected only in SLE/APS patients and in its animal model and were strongly associated with arterial thrombosis. The oxLDL/β2GPI complexes were internalized by macrophages via IgG anti-β2GPI antibody-mediated phagocytosis. In contrast, IgM anti-oxLDL antibodies derived from hyperlipidemic mice reduced the incidence of atherosclerosis. The distribution patterns of IgG and IgM anti-oxLDL antibodies in patients suggest the different roles of these antibodies.

β2 Glycoprotein 1 in Indian Patients with SLE

Forty-five patients with systemic lupus erythematosus (SLE) were investigated to evaluate the role of antiphospholipid antibodies in causation of thrombosis in Indians. The antiphospholipid antibodies studied included lupus anticoagulant (LAC), anticardiolipin antibodies (aCL), and anti-β2-glycoprotein 1 (aβ2-GP1). Twenty-seven patients (60%) had clinical manifestations of antiphospholipid antibody syndrome. Nineteen patients (42.2%) had a history of thrombosis, and eight (17.7%) had a history of recurrent fetal loss. aβ2-GP1 was (IgG) was positive in 23 (51.1%), aCL in 13 (28.8%), and LAC in four (8.8%). Of 19 patients with thrombosis, 14 (73.6%) were positive for aβ2-GP1, eight (42.1%) for aCL, and none of them was positive for LAC. Of the eight patients with recurrent fetal loss, two (25%) patients were positive for β2-GP1, five (62.5%) for aCL, and one (12.5%) for LAC. Of 18 patients without any manifestations of antiphospholipid syndrome (APS), seven patients (38.8%) were positive for aβ2-GP1, and three (16.6%) for aCL and LAC each. It is concluded that presence of aβ2-GP1 increases the risk of thrombosis and therefore should be looked for in all cases of SLE to consider prophylactic antithrombotic therapy in these patients.

Vaccination to modulate atherosclerosis

Atherosclerosis is a chronic inflammatory disease of the artery wall. Adaptive immunity plays a key role in the pathogenesis of atherosclerosis. Recently, modulation of the immune response against atherosclerotic plaque antigen(s) has attracted attention as a potentially preventive and therapeutic approach. Here, we review a series of studies on immunization with various antigens targeting treatment and prevention of atherosclerosis. Atherosclerosis-related antigens include oxidized low-density lipoprotein (LDL), apolipoprotein B-100 (ApoB-100) and heat shock protein (HSP) 60/65. Accumulating evidence supports the idea that immunization with these antigenic proteins or peptides may reduce atherosclerosis. In this review, we discuss the current status of immunization studies and possible associated mechanisms of atheroprotection.

Changes in regulation of human monocyte proteins in response to IgG from patients with antiphospholipid syndrome

The effects of immunoglobulin G (IgG) from patients with the antiphospholipid syndrome (APS) upon monocyte activation have not been fully characterized. We carried out a comprehensive proteomic analysis of human monocytes treated with IgG from patients with different manifestations of the APS. Using 2-dimensional differential gel electrophoresis (2D DiGE), 4 of the most significantly regulated proteins (vimentin [VIM], zinc finger CCH domain-containing protein 18, CAP Gly domain-containing linker protein 2, and myeloperoxidase) were differentially regulated in monocytes treated with thrombotic or obstetric APS IgG, compared with healthy control (HC) IgG. These findings were confirmed by comparing monocytes isolated from APS patients and HC. Anti-VIM antibodies (AVAs) were significantly increased in 11 of 27 patients (40.7%) with APS. VIM expression on HC monocytes was stimulated more strongly by APS IgG from patients with higher-avidity serum AVA. We further characterized the proteome of thrombotic APS IgG-treated monocytes using a label-free proteomics technique. Of 12 proteins identified with the most confidence, 2 overlapped with 2D DiGE and many possessed immune response, cytoskeletal, coagulation, and signal transduction functions which are all relevant to APS and may therefore provide potential new therapeutic targets of this disease.

14th International Congress on Antiphospholipid Antibodies Task Force. Report on antiphospholipid syndrome laboratory diagnostics and trends

Current classification criteria for definite Antiphospholipid Syndrome (APS) require the use of three laboratory assays to detect antiphospholipid antibodies (aCL, anti-β2GPI and LA) in the presence of at least one of the two major clinical manifestations (i.e. thrombosis or pregnancy morbidity) of the syndrome. However, several other autoantibodies shown to be directed to other proteins or their complex with phospholipids have been proposed to be relevant to APS but their clinical utility and their diagnostic value remains elusive. This report summarizes the findings, conclusions and recommendations of the "APS Task Force 3-Laboratory Diagnostics and Trends" meeting that took place during the 14th International Congress on Antiphospholipid Antibodies (APLA 2013, September 18-21, Rio de Janeiro, RJ, Brazil).

Clinical significance of IgA anti-cardiolipin and IgA anti-β2glycoprotein I antibodies

IgA antiphospholipid antibodies (aPL) are not currently recognized as formal laboratory criteria for the Antiphospholipid Syndrome (APS). This is mainly due to methodological issues (different study designs, use of various non-standardized IgA assays). However, there are experimental data showing the pathogenic role of IgA anti-cardiolipin antibodies (aCL) and IgA anti-β2glycoprotein I antibodies (anti-β2GPI). Isolated IgA aCL are not very common, therefore their testing could be useful in the case of strong suspicion of APS but negative results for other aPL tests. IgA anti-β2GPI seem to be the most prevalent isotype in patients with Systemic Lupus Erythematosus (SLE), with a significant association with thrombotic events. Such a clinical relevance has been recently recognized by the inclusion of these autoantibodies among the aPL tests in the novel SLICC classification criteria for SLE. Emerging interest has been raised by IgA anti-β2GPI against domain 4/5 as a novel subgroup of clinically relevant aPL.

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.

The NF-κB specific inhibitor DHMEQ prevents thrombus formation in a mouse model of antiphospholipid syndrome

BACKGROUND

β2-glycoprotein I (β2GPI)-dependent antiphospholipid antibodies (aPLs) are considered to play a pivotal pathogenic role in antiphospholipid syndrome (APS) by inducing the expression of tissue factor, inflammatory cytokines, and chemokines, most of which are dependent upon the NF-κB pathway. Therefore, the NF-κB is regarded as a promising target for the development of a novel therapeutic strategy. However, progress has been limited owing to the fact that there are no widely-used in vivo models, or highly specific inhibitors.

OBJECTIVE

This study aimed to test the effects of an NF-κB-specific inhibitor, DHMEQ, in preventing thrombus formation using an original mouse model of APS.

MATERIALS AND METHODS

Specificity of a monoclonal aPL WB-6 was examined by ELISA. WB-6 was injected into normal BALB/c mice with or without DHMEQ treatment. A pulse laser was radiated to a cutaneous vein in the window of a dorsal skinfold chamber attached to the mouse and thrombus formation was observed and recorded under a microscope.

RESULTS

WB-6 bound preferentially to the caldiolipin (CL)-β2GPI complex rather than to CL alone, or β2GPI alone. WB-6, but not isotype-matched control antibody, induced a prothrombotic state in the mice by inducing tissue factor expression upon circulating monocytes, resulting in thrombus formation at the site of laser-induced endothelial injury. This diathesis was almost completely ameliorated by DHMEQ treatment.

CONCLUSIONS

Inhibition of the NF-κB pathway is a promising strategy for the development of a novel treatment for APS.

Antiphospholipid syndrome: laboratory testing and diagnostic strategies

The antiphospholipid syndrome (APS) is diagnosed in patients with recurrent thromboembolic events and/or pregnancy loss in the presence of persistent laboratory evidence for antiphospholipid antibodies. Diagnostic tests for the detection of antiphospholipid antibodies include laboratory assays that detect anticardiolipin antibodies, lupus anticoagulants, and anti-β(2)-glycoprotein I antibodies. These assays have their origins beginning >60 years ago, with the identification of the biologic false positive test for syphilis, the observation of "circulating anticoagulants" in certain patients with systemic lupus erythematosus, the identification of cardiolipin as a key component in the serologic test for syphilis, and the recognition and characterization of a "cofactor" for antibody binding to phospholipids. Although these assays have been used clinically for many years, there are still problems with the accurate diagnosis of patients with this syndrome. For example, lupus anticoagulant testing can be difficult to interpret in patients receiving anticoagulant therapy, but most patients with a thromboembolic event will already be anticoagulated before the decision to perform the tests has been made. In addition to understanding limitations of the assays, clinicians also need to be aware of which patients should be tested and not obtain testing on patients unlikely to have APS. New tests and diagnostic strategies are in various stages of development and should help improve our ability to accurately diagnose this important clinical disorder.

Influenza vaccination can induce new-onset anticardiolipins but not β2-glycoprotein-I antibodies among patients with systemic lupus erythematosus

BACKGROUND

Antiphospholipid syndrome is characterized by autoantibodies against cardiolipins (aCL), lupus anticoagulant, and independent β2-glycoprotein (β2GPI). Controversy exists as to whether vaccination triggers the development of antiphospholipid antibodies (aPL) in patients with systemic lupus erythematosus (SLE).

METHODS

Patients with SLE (101) and matched controls (101) were enrolled from 2005-2009 and received seasonal influenza vaccinations. Sera were tested by ELISA for aCL at baseline, 2, 6, and 12 weeks after vaccination. Vaccine responses were ranked according to an overall anti-influenza antibody response index. Individuals with positive aCL were further tested for β2GPI antibodies.

RESULTS

Patients with SLE and healthy controls can develop new-onset aCL post vaccination, although at rates which do not differ between patients and controls (12/101 cases and 7/101 controls, OR 1.81, p = 0.34). New-onset moderate aCL are slightly enriched in African American SLE patients (5/36 cases; p = 0.094). The optical density measurements for aCL reactivity in patients were significantly higher than baseline at 2 weeks (p < 0.05), 6 weeks (p < 0.05), and 12 weeks (p < 0.05) post vaccination. No new β2GPI antibodies were detected among patients with new aCL reactivity. Vaccine response was not different between patients with and without new-onset aCL reactivity (p = 0.43).

CONCLUSIONS

This study shows transient increases in aCL, but not anti-β2GPI responses, after influenza vaccination.

Evaluating the conformation of recombinant domain I of β(2)-glycoprotein I and its interaction with human monoclonal antibodies

Pathogenic antiphospholipid antibodies (aPL) cause the antiphospholipid syndrome (APS) by interacting with domain I (DI) of beta-2-glycoprotein I (β₂GPI). The aPL/β₂GPI complex then exerts pathogenic effects on target cells. We previously described periplasmic bacterial expression of native and mutated variants of DI, and reported the presence of immunodominant epitopes at positions 8–9 (D8/D9) and position 39 (R39). Mutations at these positions strongly influenced the ability of recombinant DI to bind patient-derived IgG aPL and to inhibit pathogenic effects of these aPL in a mouse model of APS.

We now describe an improved cytoplasmic bacterial expression system allowing higher yield of DI. We demonstrate that the nuclear magnetic resonance (NMR) spectra of a ¹⁵N,¹³C-isotope-labelled sample of the recombinant DI protein exhibit properties consistent with the structure of DI in crystal structure of intact β₂GPI. Mutations at D8/D9 and R39 had limited impact on the NMR spectrum of DI indicating maintenance of the overall fold of the DI domain.

We investigated interactions between five variants of DI and ten monoclonal human IgG antibodies, all derived from the IgG aPL antibody IS4 by sequence manipulation and in vitro expression. Arginine residues at positions 100 and 100g in IS4V_H CDR3 play a particularly important role in binding to DI, but this is unlikely to be due to electrostatic interactions with negatively charged amino acids on DI. Both the strength of binding to DI and the ability to discriminate different DI variants varies between the different IgG antibodies tested. There was no simple relationship between these binding properties and antibody pathogenicity.

IgM anti-β2 glycoprotein I is protective against lupus nephritis and renal damage in systemic lupus erythematosus

OBJECTIVE

Antibodies to ß(2) glycoprotein I (IgG and IgM isotypes) have recently been added to the laboratory criteria of the revised antiphospholipid syndrome classification criteria. We investigated whether IgM anti-ß(2)-glycoprotein I (anti-ß(2)-GPI) is associated with clinical manifestations of systemic lupus erythematosus (SLE).

METHODS

Anti-ß(2)-GPI was measured in 796 patients with SLE (93% women, 53% white, 38% African American, mean age 45 yrs). IgM anti-ß(2)-GPI (> 20 phospholipid units) was found in 16%. Associations were determined with clinical manifestations of SLE and with components of the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index.

RESULTS

As expected, IgM anti-ß(2)-GPI was highly associated with both the lupus anticoagulant and with anticardiolipin. It was associated with transient ischemic attack (OR 2.64, p = 0.04), but not significantly with venous or arterial thrombosis. IgM anti-ß(2)-GPI was protective against lupus nephritis (OR 0.54, p = 0.049), renal damage (p = 0.019), and hypertension (OR 0.58, p = 0.008). This protective effect remained after adjustment for ethnicity.

CONCLUSION

In SLE, IgM anti-ß(2)-GPI is not associated with thrombosis but is protective against lupus nephritis and renal damage. "Natural" autoantibodies of the IgM isotype may have a protective effect.

Prevalence and clinical associations of lupus anticoagulant, anticardiolipin antibodies, and anti-beta2-glycoprotein I antibodies in patients with systemic lupus erythematosus

BACKGROUND

The presence of antiphospholipid antibodies (aPLs) is associated with the clinical features of antiphospholipid syndrome (APS), which comprises venous and arterial thrombosis and pregnancy loss, and systemic lupus erythematosus (SLE). The prevalence of aPLs has been reported to be different in patient populations affected by either of these conditions. We performed a retrospective study to evaluate the prevalence and clinical associations of aPLs, including lupus anticoagulant (LAC), anticardiolipin (aCL), and anti-beta2-glycoprotein I antibodies (anti-beta2-GPI) in a cohort of Korean patients with SLE.

METHODS

This study included samples from 88 SLE patients for whom aPL testing had been advised between June 2006 and July 2009 at the Dong-A University Hospital. Serum and plasma samples were tested for LAC, aCL (IgG, IgM), and anti-beta2-GPI (IgG, IgM) antibodies. Clinical data from patients were obtained from a review of medical records.

RESULTS

LAC was the most common (34.1% of total patients, 30/88) antibody, followed by IgM aCL (31.8%, 28/88), IgG aCL (18.2%, 16/88), and IgM and IgG anti-beta2-GPI (both 5.7%, 5/88 each). Positivity for LAC was strongly associated with venous/arterial thrombosis (P=0.002).

CONCLUSIONS

LAC was the most common antibody detected in Korean SLE patients and is shown to have a significant association with the presence of venous/arterial thrombosis. The measurement of LAC may be clinically useful in identifying patients with SLE who are at a high risk for venous/arterial thrombosis.

Autoimmunity, infectious immunity, and atherosclerosis

INTRODUCTION

Vascular inflammation is common in certain systemic autoimmune diseases and contributes to the oxidation of low-density lipoprotein (oxLDL) and oxLDL/beta2-glycoprotein I (beta2GPI) complex formation. These complexes have been implicated as proatherogenic autoantigens that participate in the development of atherosclerotic disease.

DISCUSSION

We have demonstrated that the in vitro macrophage uptake of oxLDL/beta2GPI complexes increases in the presence of IgG anti-beta2GPI antibodies and that IgG immune complexes containing oxLDL/beta2GPI upregulate the expression of both scavenger and Fcgamma receptors to activate beta2GPI specific T cells. Some persistent infections may cause immune responses that promote atherogenesis. Cellular immunity (Th1) against Helicobacter pylori (H. pylori) derived heat shock protein 60 (Hp-HSP60) cross-reacts with endogenous HSP60 to cause cardiovascular disease likely by molecular mimicry.

CONCLUSION

Infectious cellular response may be proatherogenic,while the humoral response (antibody production) maybe protective. We review the recent progress in our understanding of autoimmunity and infectious immunity that promote atherosclerosis.

Isolated elevation of IgA anti-beta2glycoprotein I antibodies with manifestations of antiphospholipid syndrome: a case series of five patients

Current diagnostic classification criteria recommend elevated titres of anti-cardiolipin (aCL) and/or anti-beta(2)GPI antibody by ELISA IgG or IgM and/or lupus anticoagulant (LA) to confirm antiphospholipid syndrome (APS). Although IgA aPL antibodies have been shown to be pathogenic in animal models of APS, their clinical significance has remained elusive. We report four cases of exclusive IgA anti-beta(2)GPI antibody sero-positivity with concomitant clinical manifestations associated with APS. Four of the five patients were LA negative. 1) Thirty-eight-year-old African-American female with SLE presented with resolving digital ulcers. Serum IgA anti-beta(2)GPI antibody titres were 118.5 SAU (normal range: 0-20 SAU). 2) Twenty-seven-year-old African-American woman with SLE was evaluated for recent onset of severe headaches, unresponsive to analgesics and anti-migraine medications. MRI of the brain revealed hyper-intensities in the white matter in the frontal lobes. Serum IgA anti-beta(2)GPI antibody titres were 29.1 Standard A Units (SAU). 3) Thirty-two-year-old Hispanic female with history of two unexplained miscarriages and negative serologies for SLE. Serum IgA anti-beta(2)GPI antibody titres were 102.0 SAU. 4) Twenty-five-year-old white female with history of recent unexplained miscarriage in the 11th week of gestation and associated complaints of numbness and tingling in her hands. Her IgA anti-beta(2)GPI antibody titre was 62.0 SAU. 5) Twenty-five-year-old African-American woman with SLE, positive for anti-Ro antibodies with a history of ischemic fingers, a pregnancy loss and recent pregnancy complicated due to pre-eclampsia. Her LA was positive and her IgA anti-beta(2)GPI antibody titer was 186.0 SAU. This case series supports that elevated IgA anti-beta(2)GPI antibody titres may identify additional patients who have clinical features of APS but who do not meet current diagnostic criteria.

Autoimmune-mediated atherothrombosis

Autoimmune vascular inflammation and oxidative stress (lipid peroxidation) are common in systemic autoimmune diseases and contribute to the oxidative modification of low-density lipoprotein (oxLDL) and oxLDL/beta2GPI complex formation. Circulating oxLDL/beta2GPI complexes have been detected in patients with systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS). The presence of antibodies to oxLDL/beta2GPI complexes indicates that these complexes are immunogenic, and the coexistence of complexes and antibodies has pointed to an active proatherogenic role in the development of autoimmune vascular complications. Immunohistochemical staining of atherosclerotic lesions suggest that these complexes are formed in the arterial wall and released into circulation. The in vitro macrophage uptake of oxLDL/beta2GPI complexes was significantly increased in the presence of antiphospholipid antibodies, either beta2GPI-dependent anticardiolipin or anti-beta2GPI antibodies, suggesting that macrophage Fcgamma receptors are involved in lipid intracellular influx and foam cell formation. These findings provide an explanation for the accelerated development of atherosclerosis seen in SLE and APS. The presence of circulating oxLDL/beta2GPI complexes and IgG antibodies to these complexes indicate significant vascular injury and oxidative stress as well as an active role in autoimmune-mediated atherothrombosis.

IgA antiphospholipid antibodies are an independent risk factor for thromboses

Antiphospholipid antibodies (lupus anticoagulant, anti-cardiolipin and anti-β2-glycoprotein I antibodies, mostly IgG isotype) are strong risk factors for thrombosis. Because a paucity of information on IgA isotype exists in the literature, we retrospectively evaluated the thrombotic significance of IgA antiphospholipid antibodies. We included 472 patients with clinical information on thrombotic events and complete laboratory work-up for antiphospholipid antibodies syndrome. Odds ratios (OR) of various antiphospholipid antibodies for thrombosis were calculated by univariate and multivariate analyses. Lupus anticoagulant alone was detected in 57 (12%) patients, ELISA-based antibodies (IgG, IgM, IgA) against cardiolipin, phosphatidylserine or β2-glycoprotein-I alone were detected in 131 (28%) patients, whereas 80 (17%) patients had both. Antibody isotype distribution was IgG 32%, IgM 60% and IgA 56%. Univariate analysis showed a statistically significant risk of thrombosis in patients with elevated titres of IgA of any ELISA-based antiphospholipid antibodies (OR 1.77). Stepwise logistic regression (multivariate) analysis identified elevated titres of any ELISA-based IgA antiphospholipid antibodies as an independent risk factor for thrombosis (OR 1.6) in the entire cohort, and in the subgroup of patients without concurrent presence of lupus anticoagulant (OR 1.8). IgA antiphospholipid antibodies appear to be a significant independent risk factor for thrombosis, thereby meriting evaluation in patients with unexpected thrombosis.

Examining the non-linear relationship between monoclonal antiphospholipid antibody sequence, structure and function

In the antiphospholipid syndrome (APS), pathogenic antiphospholipid antibodies (aPL) that cause thrombosis or pregnancy morbidity are characterized by binding to anionic phospholipids (PL) and β2-glycoprotein I (β2GPI). Sequence analysis of human monoclonal aPL has shown that high affinity for these antigens is associated with the presence of three particular amino acids: arginine (Arg), asparagine and lysine in the complementarity determining regions (CDRs) of their heavy and light chains. In vitro expression systems have been used to create variants of the antibodies in which these amino acids have been altered. In general, removal of Arg residues reduces affinity for anionic PL and β2GPI. Arg at different positions in the sequence, however, have different effects on binding affinity and effects on binding are not always mirrored by effects on pathogenicity. This review will focus upon the sequence motifs that have been found to distinguish pathogenic from non-pathogenic aPL, and whether these or other properties may help to identify distinct pathogenic subsets of aPL. In particular, we will focus on our recent work in which we are trying to develop a better understanding of the molecular mechanisms involved in activation of target cells by pathogenic aPL. These studies, together with molecular models of antigen/antibody complexes, help us to understand exactly how pathogenic antibodies interact with antigens. Ultimately, this understanding may aid the design of more powerful diagnostic/prognostic assays and targeted therapeutic agents to block the pathogenic effects of these antibodies.

A protocol for determination of anticardiolipin antibodies by ELISA

The anticardiolipin (aCL) test has been widely used by physicians since the mid-1980s for diagnosing patients with antiphospholipid syndrome (APS). Establishment of this diagnosis has enabled effective management of patients with recurrent thrombosis or recurrent pregnancy losses. The test was first established in 1983 as a radioimmunoassay and soon thereafter converted into ELISA. There have been numerous efforts to standardize the aCL test, but precise reproducible measurement of aCL levels is difficult and the use of semiquantitative measurements (high, medium and low) is recommended as this is probably sufficient for clinical diagnosis. Using validated ELISAs for measuring aCL Abs offers greater reproducibility, would reduce interlaboratory variations and limit discrepancies in results between different laboratories. This article details a procedure that takes approximately 2 h and summarizes the information available on the aCL ELISA test.

[Clinical features and treatments of antiphospholipid syndrome]

Antiphospholipid antibodies are serological markers of antiphospholipid syndrome (APS). Diversity of so-called antiphospholipid antibodies is well-known. These antibodies are directed against phospholipid binding proteins such as beta(2)-glycoprotein I and prothrombin as well as against phospholipids such as cardiolipin. Thrombosis and pregnancy morbidity are clinical features of APS. In addition, cardiovascular manifestations, neurological disorders, skin manifestations, renal involvements and thrombocytopenia are reported to be significant in clinical aspects of APS. Anticoagulation therapy and antiplatelet therapy are effective for the secondary prevention of thrombosis in APS.

Autoantibody explosion in antiphospholipid syndrome

Antiphospholipid syndrome (APS) is characterized by thrombosis and pregnancy loss in the presence of antiphospholipid antibodies (aPL), mainly anticardiolipin, anti-beta2-glycoprotein I and lupus anticoagulant. However, similar to systemic lupus erythematosus, APS is also characterized by multiple other autoantibodies including 'non-classical' aPL, as well as other antibodies. Herein we describe the autoantigen properties, prevalence and clinical importance of 30 different antibodies in APS. Among the other antibodies characterizing APS are autoantibodies directed to platelets, glycoproteins, various coagulation factors, lamins, mitochondrial antigens and cell surface markers. Few of these autoantibodies are correlated with the presence of other antibodies, and some may have an additive role in the pro-thrombotic tendency of the syndrome. This autoantibody explosion might be important in early identification of the syndrome and its manifestations.

The role of antibody polyspecificity and lipid reactivity in binding of broadly neutralizing anti-HIV-1 envelope human monoclonal antibodies 2F5 and 4E10 to glycoprotein 41 membrane proximal envelope epitopes

Two neutralizing human mAbs, 2F5 and 4E10, that react with the HIV-1 envelope gp41 membrane proximal region are also polyspecific autoantibodies that bind to anionic phospholipids. To determine the autoantibody nature of these Abs, we have compared their reactivities with human anti-cardiolipin mAbs derived from a primary antiphospholipid syndrome patient. To define the role of lipid polyreactivity in binding of 2F5 and 4E10 mAbs to HIV-1 envelope membrane proximal epitopes, we determined the kinetics of binding of mAbs 2F5 and 4E10 to their nominal gp41 epitopes vs liposome-gp41 peptide conjugates. Both anti-HIV-1 mAbs 2F5 and 4E10 bound to cardiolipin with K(d) values similar to those of autoimmune anti-cardiolipin Abs, IS4 and IS6. Binding kinetics studies revealed that mAb 2F5 and 4E10 binding to their respective gp41 peptide-lipid conjugates could best be defined by a two-step (encounter-docking) conformational change model. In contrast, binding of 2F5 and 4E10 mAbs to linear peptide epitopes followed a simple Langmuir model. A mouse mAb, 13H11, that cross-blocks mAb 2F5 binding to the gp41 epitope did not cross-react with lipids nor did it neutralize HIV-1 viruses. Taken together, these data demonstrate the similarity of 2F5 and 4E10 mAbs to known anti-cardiolipin Abs and support the model that mAb 2F5 and 4E10 binding to HIV-1 involves both viral lipid membrane and gp41 membrane proximal epitopes.

Anti-β2-glycoprotein I antibodies of IgM class are linked to thrombotic disorders in young women without autoimmune disease

Antiphospholipid autoantibodies particularly antibodies against beta2-glycoprotein I (anti-beta2GPI) are casually associated with thromboses in patients with autoimmune diseases. However, their exact prevalence and role in the pathogenesis of thromboses in the absence of autoimmune disease is still inconclusive. They might be particularly important when other risk factors of thrombosis are absent. We investigated antiphospholipid antibodies in 68 young women (aged <45yr at onset of the event, without autoimmune disease and with an otherwise low risk of thrombosis) in the stable period following myocardial infarction (MI), lacunar cerebral infarction (LACI) or deep vein thrombosis (DVT) and in 37 healthy age-matched controls. Patients had increased IgM anti-beta2GPI compared to controls (36.0, 11.5-49.5 vs. 17.50, 3.50-30.0 arbitrary units (AU), p<0.001), whereas no difference was obtained in other measured antibodies (anticardiolipin and antiphosphatidylserine (aPS) antibodies of IgG and IgM). IgM anti-beta2GPI positively correlated with some markers of increased coagulation potential and negatively with BMI (r=-039, p<0.005) and other parameters of the metabolic syndrome. In conclusion, we found that levels of IgM anti-beta2GPI are increased in young women suffering arterial or venous thromboses in the absence of other known autoimmune diseases and also in the absence of pronounced classical risk factors. We found that IgM anti-beta2GPI positively correlated with some markers of increased coagulation potential and negatively with parameters of the metabolic syndrome. Thus, it appears that elevated levels of IgM anti-beta2GPI are linked to thrombotic disorders in young women (without autoimmune disease) particularly when classical risk factors or the metabolic syndrome are absent.

Specificity and sensitivity of anti-beta2-glycoprotein I as compared with anticardiolipin antibody and lupus anticoagulant in Thai systemic lupus erythematosus patients with clinical features of antiphospholipid syndrome

Antibodies to beta(2)-glycoprotein I (anti-beta(2)-GPI) have been reported to have stronger association with clinical antiphospholipid syndrome (APS) than anticardiolipin antibodies (aCL) and lupus anticoagulant (LAC). We investigated the sensitivity and specificity of ELISA for anti-beta(2)-GPI in Thai systemic lupus erythematosus (SLE) patients with clinical features of APS and compared the results with IgG/IgM aCL and LAC to find the test with the best association. The hospital records of 151 Thai SLE patients whose sera had been sent for either IgG/IgM anticardiolipin antibodies or lupus anticoagulant testing were reviewed. Sera of patients either without complete clinical records or those with APS-related manifestations other than vascular thrombosis and pregnancy morbidity (according to the international consensus statement on preliminary classification criteria for definite APS) were excluded. For the remaining subjects (112 patients), their sera were tested for anti-beta(2)-GPI antibody, IgG and IgM anticardiolipin, and lupus anticoagulant. The sensitivity and specificity of each method were compared by using the chi-square test. Among the 112 (74.2%) SLE patients in the study, 35 (31.3%) presented with preliminary clinical criteria for APS (i.e., vascular thrombosis and pregnancy morbidity) whereas 77 (68.7%) did not. The sensitivity and specificity of anti-beta(2)-GPI determination were 57.1 and 79.2%, respectively, whereas those of IgG aCL were 25.7 and 94.8%, of IgM aCL were 5.7 and 98.7%, and of LAC were 44.8 and 77.3%, respectively. The accuracy of the four tests showed similar association with clinical APS (accuracy of test = 72.3, 73.2, 69.6, and 68.3%, respectively). Concerning the sensitivity, specificity, and difficulty of the methods, the combination of anti-beta(2)-GPI and IgG aCL tests was the best for the diagnosis of APS in Thai SLE patients.

Association of nodular regenerative hyperplasia of the liver with porto-pulmonary hypertension in a patient with systemic lupus erythematosus

A 37-year old woman with systemic lupus erythematosus (SLE) complicated by pulmonary hypertension (PHT) was admitted to evaluate abnormal liver function. Radiological imaging study, including ultrasonography, computed tomography and magnetic resonance imaging and upper gastrointestinal endoscopy, revealed multiple hepatic nodules, hepatosplenomegaly and esophageal varices. Percutaneous needle liver biopsy showed non-cirrhotic hepatic nodules with hyperplastic hepatocytes surrounded by atrophic hepatocytes, confirming the diagnosis of nodular regenerative hyperplasia (NRH) associated with non-cirrhotic portal hypertension (PT). NRH of the liver is known to be a very rare hepatic manifestation in rheumatic diseases. This case shows the association of NRH with porto-pulmonary hypertension in SLE.

Significance of antiprothrombin antibodies in patients with systemic lupus erythematosus: clinical evaluation of the antiprothrombin assay and the antiphosphatidylserine/prothrombin assay, and comparison with other antiphospholipid antibody assays

Antibodies against prothrombin are detected by enzyme immunoassays (EIA) in sera of patients with antiphospholipid syndrome (APS). However, there are two methods for antiprothrombin EIA; one that uses high binding plates (aPT-A), and another that utilizes phosphatidylserine bound plates (aPS/PT). We aimed to evaluate and compare aPT-A and aPS/PT in a clinical setting. We performed EIA for anti-PT, anti-PS/PT, IgG, and IgM anticardiolipin antibodies (aCL), and IgG β2-glycoprotein I-dependent aCL (aβ2GPI/CL) with serum samples from 139 systemic lupus erythematosus (SLE) patients (16 with history of at least one thrombotic episode) and 148 controls. We observed that: (1) although titers of anti-PT and anti-PS/PT were significantly related with each other (P < 0.0001, ρ = 0.548), titer of anti-PT and anti-PS/PT differed greatly in some samples; (2) odds ratio and 95% confidence interval for each assay was 3.556 (1.221–10.355) for aPT-A, 4.591 (1.555–15.560) for aPS/PT, 4.204 (1.250–14.148) for IgG aCL, 1.809 (0.354–9.232) for IgM aCL, and 7.246 (2.391–21.966) for aβ2GPI/CL. We conclude that, while all EIA performed in this study except IgM aCL are of potential value in assessing the risk of thrombosis, aPS/PT and aβ2GPI/CL seemed to be highly valuable in clinical practice, and that autoantibodies detected by anti-PT and anti-PS/PT are not completely identical.

Accelerated atheroma in the antiphospholipid syndrome

Increased cardiovascular morbidity and mortality due to the pre-mature or accelerated development of atherosclerosis has been reported in patients with systemic autoimmune diseases such as systemic lupus erythematosus. These findings motivated a great deal of research into the role of autoimmunity in atherogenesis. The relationship between atherosclerosis and cholesterol metabolism to atherosclerosis has been well established. However, the participation of newer inflammatory and immunologic mechanisms are emerging as relevant factors for the initiation and progression of atherosclerotic lesions.

The antiphospholipid syndrome: what are we really measuring? How do we measure it? And how do we treat it?

The antiphospholipid syndrome is described with a review of its historical development as a recognized syndrome, what constitutes an antiphospholipid antibody, how it is measured, and how the syndrome is treated. Antiphospholipid antibodies are actually antibodies to a protein, most often beta-2-glycoprotein 1, that is usually bound to a phospholipid. Some antibodies are directed towards lipid-bound prothrombin. The antibodies are measured by immunologic assays or by antibody-dependent abnormalities detected in coagulation assays. Although they prolong coagulation assays, they are associated with a thrombotic tendency rather than a bleeding disorder. There are numerous postulated mechanisms to account for the thrombotic tendency. Patients with the antiphospholipid syndrome are treated with long-term oral anticoagulation to prolong the INR to 2.0 to 3.0. For most patients, a more intense level of treatment with a higher INR is not needed.

Changes in autoimmune markers of the anti-cardiolipin syndrome on days of extreme geomamagnetic activity

The possible relation between various biological or medical phenomena and changes in environmental physical activity, such as Solar, Geomagnetic Activity (GMA); Cosmic Ray; Proton, and other particle flux, have been reported. These phenomena seem to be reflected, among others, in the immune system, resulting in changes in immunoglobulin (Ig) levels or outbursts of epidemics.

AIM

to examine a possible association of GMA with another aspect of the immune system--autoimmunity. Fluctuations of levels of anticardiolipin (IgG; IgM, IgA subtypes) and lupus anticoagulant (Kaulin clotting time and Dilute Russell's viper venom time) autoantibodies, serving as anticardiolipin syndrome (ACLS) markers, were monitored during days of severe GMA storms and compared with those of lowest/quiet GMA days. Cosmophysical data were obtained from the NOAA National Space Service Center and the National Geophysical Data Center, USA.

RESULTS

A significant rise in the levels of anti beta2Gp1-IgA (p = 0.0001); and KCT (p = 0.019) was observed on days of the GMA storms.

CONCLUSION

On days of major GMA storms, significant changes in the autoimmune marker levels of ACLS were observed compared with quiet days. An involvement of those changes in clinical events related to GMA storms is possible.

Predictive value of persistent versus transient antiphospholipid antibody subtypes for the risk of thrombotic events in pediatric patients with systemic lupus erythematosus

Study objectives were to determine, in children with systemic lupus erythematosus (SLE), (1) the association of antiphosholipid antibody (APLA) subtypes with thrombotic events (TEs) and (2) the predictive value of persistent versus transient antibodies for TEs. This is a cohort study of 58 SLE children in whom lupus anticoagulants (LAs), anticardiolipin antibodies (ACLAs), anti–β2-glycoprotein-I (anti–β2-GPI), and antiprothrombin (anti-PT) were assessed on at least 2 occasions (more than 3 months apart). Antibodies were classified as persistent (positive on at least 2 occasions) or transient (positive once). Outcomes were symptomatic TEs confirmed by objective radiographic tests identified retrospectively and prospectively. Seven of the 58 patients (12%) had 10 TEs; 5 patients had TEs during prospective follow-up. Persistent LAs showed the strongest association with TEs (P < .001). Persistent ACLAs (P = .003) and anti–β2-GPI (P = .002) were significantly associated with TEs; anti-PT (P = .063) showed a trend. Persistent or transient LAs and anti–β2-GPI showed similar strength of association, while ACLAs and anti-PT were no longer associated with TEs. Positivity for multiple APLA subtypes showed stronger associations with TEs than for individual APLA subtypes because of improved specificity. Lupus anticoagulant is the strongest predictor of the risk of TEs; other APLA subtypes provide no additional diagnostic value. Anticardiolipin antibodies and anti-PT require serial testing because only persistent antibodies are associated with TEs.

Pathogenesis of antiphospholipid antibodies: impairment of fibrinolysis and monocyte activation via the p38 mitogen-activated protein kinase pathway

Antiphospholipid syndrome (APS) is characterized by recurrent thrombosis or pregnancy morbidity associated with antiphospholipid antibodies (aPL). Impaired fibrinolysis is a contributing factor for the development of thrombosis, and the effect of aPL in the fibrinolytic system has been investigated. Impaired release of tPA and enhanced release of PAI-1 after endothelial activation is reported in patients with APS. Elevated Lipoprotein (a) levels have been found in APS, which results in inhibition of fibrinolytic activity. Phospholipid-bound beta(2)-glycoprotein I (beta(2)GPI) is a major autoantigen for aPLs. beta(2)GPI exerts both anti-coagulant and pro-coagulant properties mainly by interacting with other phospholipid-binding proteins such as coagulation factors and protein C. Dramatic increase in the affinity of beta(2)GPI to the cell surface is induced by binding of pathogenic anti-beta(2)GPI antibodies, which may modify the physiological function of beta(2)GPI and may affect the coagulation/fibrinolysis balance on the cell surface. Using chromogenic assays for measuring fibrinolytic activity, we demonstrated that addition of monoclonal anticardiolipin antibody (aCL) decreases the activity of extrinsic/intrinsic fibrinolysis. Significantly lower activity of intrinsic fibrinolysis was also demonstrated in the euglobulin fractions from APS patients. Endothelial cells and monocytes are activated by aPLs in vitro, resulting in production of tissue factor (TF), a major initiator of the coagulation system. Recently, aPLs are reported to induce thrombocytes to produce thromboxane. The importance of apoE receptor 2 on platelets for the binding of artificially dimerized beta(2)GPI was suggested. By investigating aPL-inducible genes in peripheral blood mononuclear cells, we found that the mitogen-activated protein kinase (MAPK) pathway was up-regulated. Using a monocyte cell line, phosphorylation of p38 MAPK, NF-kappaB translocation to the nuclear fraction, and up-regulated TF mRNA expression were demonstrated after treatment with monoclonal aCL. These phenomena were observed only in the presence of beta(2)GPI. Moreover, a specific p38 MAPK inihibitor SB203580 decreased aCL/beta(2)GPI-induced TF mRNA expression. Thus, aCL/beta(2)GPI plays dual roles in the pathogenesis of APS, firstly by deranging the fibrinolytic system and secondly by activating monocytes, endothelial cells and thrombocytes to produce TF or thromboxane.

Infarction of the right hemisphere in a patient with antiphospholipid antibody syndrome

Hemicraniectomy as a surgical treatment for intracranial pressure following large ischemic lesions is widely practiced in selected patients. The antiphospholipid antibody syndrome (APS), a disorder characterized by recurrent arterial and venous thrombosis, is a very rare cause of space occupying ischemic lesions. We present a case of a 35 year old female diagnosed with APS who initially presented with small ischemic lesions and within days developed a massive near-total infarction of the right hemisphere. Because of central nervous system, skin and systemic manifestations Sneddon's syndrome and catastrophic antiphospholipid antibody syndrome (CAPS) remained a possible diagnoses. Sneddon's syndrome is a non-inflammatory occlusive arteriopathy of small and medium size arteries predominantly of the skin and brain, whereas the catastrophic antiphospholipid antibody syndrome is characterized by acute multi-organ system thrombosis of small and large vessels. In addition to the diagnostic criteria for APS a heterozygous factor V Leiden mutation was found in this patient, which may be a contributing risk factor for cerebral ischemia. When considering invasive decompressive procedures the neurosurgeon has to be aware of the poor prognosis of some forms of APS with systemic manifestations.