Immunology of the antiphospholipid antibody syndrome

Bullous Pemphigoid: Trigger and Predisposing Factors

Bullous pemphigoid (BP) is the most frequent autoimmune subepidermal blistering disease provoked by autoantibodies directed against two hemidesmosomal proteins: BP180 and BP230. Its pathogenesis depends on the interaction between predisposing factors, such as human leukocyte antigen (HLA) genes, comorbidities, aging, and trigger factors. Several trigger factors, such as drugs, thermal or electrical burns, surgical procedures, trauma, ultraviolet irradiation, radiotherapy, chemical preparations, transplants, and infections may induce or exacerbate BP disease. Identification of predisposing and trigger factors can increase the understanding of BP pathogenesis. Furthermore, an accurate anamnesis focused on the recognition of a possible trigger factor can improve prognosis by promptly removing it.

Epidemiological, clinical and immune factors that influence the persistence of antiphospholipid antibodies in leprosy

INTRODUCTION

Antiphospholipid antibodies (aPL) are described in individuals with leprosy without the clinical features of antiphospholipid antibody syndrome (APS), a condition involving thromboembolic phenomena. We have described the persistence of these antibodies for over 5 years in patients with leprosy after specific treatment.

OBJECTIVES

To determine whether epidemiological, clinical and immunological factors played a role in the long-term persistence of aPL antibodies in leprosy patients after multidrug therapy (MDT) had finished.

METHODS

The study sample consisted of 38 patients with a diagnosis of leprosy being followed up at the Dermatology and Venereology Outpatient Department at the Alfredo da Matta Foundation (FUAM) in Manaus, AM. ELISA was used to detect anticardiolipin (aCL) and anti-β₂ glycoprotein I (anti-β₂GPI) antibodies. Patients were reassessed on average of 5 years after specific treatment for the disease (MDT) had been completed.

RESULTS

Persistence of aPL antibodies among the 38 leprosy patients was 84% (32/38), and all had the IgM isotype. Mean age was 48.1 ± 15.9 years, and 23 (72.0%) were male. The lepromatous form (LL) of leprosy was the most common (n = 16, 50%). Reactional episodes were observed in three patients (9.4%). Eighteen (47.37%) were still taking medication (prednisone and/or thalidomide). Mean IgM levels were 64 U/mL for aCL and 62 U/mL for anti-β₂GPI. In the multivariate binary logistic regression the following variables showed a significant association: age (p = 0.045, OR = 0.91 and CI 95% 0.82-0.98), LL clinical presention (p = 0.034; OR = 0.02 and CI 95% = 0.0-0.76) and bacterial index (p = 0.044; OR = 2.74 and CI 95% = 1.03-7.33). We did not find association between prednisone or thalidomide doses and positivity for aPL (p = 0.504 and p = 0.670, respectively). No differences in the variables vascular thrombosis, pregnancy morbidity, diabetes, smoking and alcoholism were found between aPL-positive and aPL-negative patients.

CONCLUSION

Persistence of positivity for aPL antibodies was influenced by age, clinical presentation and bacterial index. However, further studies are needed to elucidate the reason for this persistence, the role played by aPL antibodies in the disease and the B cell lineages responsible for generation of these antibodies.

Timing of initiation of low-molecular-weight heparin administration in pregnant women with antiphospholipid syndrome: a randomized clinical trial of efficacy and safety

Objective

We aimed to evaluate the effect of different timing of initiation of low-molecular-weight heparin (LMWH) administration on the pregnancy outcomes in women with antiphospholipid syndrome (APS).

Materials and methods

A randomized controlled study was conducted on women with obstetrical APS. All participants were randomly divided at documentation of positive pregnancy test into two groups; early initiation group in which LMWH therapy was started once positive pregnancy test was established (in the fifth week of gestation), and later initiation group in which LMWH therapy was started after sonographic confirmation of fetal cardiac pulsation (in the seventh week of gestation). In both groups, LMWH (enoxaparin) was given at a dose of 40 mg/day subcutaneously and the therapy continued until end of pregnancy. The primary outcome measure was ongoing pregnancy rate and the secondary outcome measures were fetal loss, live birth rate, preterm labor before 34 weeks of gestation, intrauterine growth restriction (IUGR), and congenital fetal malformations.

Results

Ninety-four women (48 in the early initiation group and 46 in the later initiation group) were subjected to final analysis. The ongoing pregnancy rate was significantly higher in the early initiation group than in the later initiation group (81.2% vs 60.9%; P=0.040). However, both groups were similar in the incidences of fetal loss, preterm labor before 34 weeks of gestation, and IUGR, and live birth rate. No recorded congenital fetal malformations in both groups.

Conclusion

Early administration of LMWH for pregnant women with obstetrical APS reduces early pregnancy loss, but does not affect the incidence of late obstetrical complications.

Antiphospholipid (Hughes) syndrome and atheroma

The antiphospholipid syndrome (APS) is a prothrombotic disorder characterised by recurrent thrombotic events and pregnancy morbidity in the context of autoantibodies against phospholipid binding proteins. There is increasing evidence that these autoantibodies are associated with accelerated atherosclerosis. The presence of stenotic lesions radiologically and abnormalities of the ankle-brachial index, flow-mediated dilatation and carotid abnormalities supports this view and this clinical evidence is reviewed.

Is HLA class II susceptibility to primary antiphospholipid syndrome different from susceptibility to secondary antiphospholipid syndrome?

To assess whether the major histocompatibility complex (MHC) profile of patients presenting with primary antiphospholipid syndrome (PAPS) is different from that of patients with secondary antiphospholipid syndrome (SAPS), we studied 123 patients, 34 of whom presented PAPS and 35 SAPS due to systemic lupus erythematosus (SLE), 54 SLE patients without antiphospholipid syndrome (APS), and 166 controls. HLA-DRB1 and DQB1 alleles were typed using amplified DNA hybridized with sequence-specific primers. Compared to controls, PAPS patients exhibited a nonsignificantly increased frequency of DR53-associated alleles, and SAPS patients presented an increased frequency of HLA-DRB1* 03 alleles (corrected P 0.05). In addition, HLA-DRB1* 03 alleles were over-represented in SAPS patients presenting anticardiolipin antibody (aCL) (Pc 0.02), in SLE patients as a whole (Pc < 0.0001), and in SLE patients without APS (Pc 0.02). The frequency of aCL among SLE patients presenting or not HLA-DRB1* 03 alleles was closely similar. A trend to an increase in the frequency of the DQB1* 0604 allele (14.3 versus 4.2%, P 0.03) and of the DQB1*0302 allele (31.4 versus 12.7%, P 0.01) was observedin SAPS. Taken together, these results indicate that the association of SAPS with HLA-DRB1* 03 is due to the association with SLE and is not due to aCL, and suggest that the HLA class II profile of PAPS is different from that of SAPS.

Human monoclonal antibodies against the complex of phosphatidylserine and prothrombin from patients with the antiphospholipid antibodies

The presence of antibodies against the complex of prothrombin and phosphatidylserine (aPS/PT) more significantly correlates with manifestations of antiphospholipid syndrome (APS) and with the presence of lupus anticoagulants (LA) than antibodies against prothrombin bound to oxygenated polystyrene (aPT-A). To investigate immunological specificities and functional activities of aPS/PT, four monoclonal aPS/PT, designated as HG-4, KE-6, KF-5 and KF-6, from two patients with antiphospholipid antibodies (aPL) were established and characterized. Three of these antibodies (HG-4, KF-5 and KF-6) recognized the complex of phosphatidylserine and prothrombin, but did not react to prothrombin directly coated on oxygenated plates. KE-6 bound not only to the complex of phosphatidylserine and prothrombin but also to prothrombin on oxygenated plates. None of them showed the binding activity to prothrombin directly coated on non-oxygenated plates. HG-4, KE-6 and KF-5 had LA-like activity. The findings support the hypothesis that autoimmune aPS/PT recognize the cryptic epitopes or neoepitopes exposed upon interaction between prothrombin and phosphatidylserine, and that aPS/PT are, at least in part, responsible for LA activity. Lupus (2007) 16, 509—516.

Cerebral haemostasis and antiphospholipid antibodies

One of the major clinical concerns of the antiphospholipid syndrome (APS) is the propensity of antiphospholipid(aPL) antibodiesto cause thrombosis in both the large and small vessels of the brain. In this article, we review the current understandingof haemostasis in cerebral circulation and discuss this in the context of antiphospholipidantibodies. The systemic-defect-local-phenotypeparadox is of particular importance in this discussion. In this paradigm, a systemic defect in thrombosis and haemostasis leads to a localized pattern of thrombotic disease because the regional physiological variations in the several prothromboticand anticoagulantfactors and the defect interact so as to favour thrombosis at a particular site. One possible mechanism of initiation of thrombosis in APS is the activation of endothelialcells by aPL that could occur in the cerebral vessels and provoke thrombosis. We review the evidence from gene knockout mice, other animal models and human postmortem examination studies as to which pro- and antithrombotic mechanisms are effecting haemostasis in the cerebral circulation. We conclude that there are large deficits in the understanding of the regulation of haemostasis in the human brain. As a consequencethere is a lack of knowledgeabout the effect of aPL on cerebral endothelium and thrombosis. Recent developments in gene expression profiling may have an impact on our understandingof endothelialfunctionin the brain. More research is required.

Antiphospholipid-Mediated Thrombosis: Interplay Between Anticardiolipin Antibodies and Vascular Cells

The antiphospholipid syndrome (APS) is characterized by thrombosis or pregnancy morbidity in the presence of antiphospholipid autoantibodies (aPL). aPL are a heterogeneous family of autoantibodies with diverse cross-reactivities whose origin and role have not been fully elucidated. Many of the autoantibodies associated with APS are directed against phospholipid-binding plasma proteins, such as β2-GPI and prothrombin, or phospholipid-protein complexes. The mechanisms by which aPL cause thrombosis are not completely understood. There is no unique mechanism able to explain all symptoms associated with the presence of aPL. Different theories have been proposed, including the effect of aPL on endothelial cells, monocytes, and platelets. aPL are able to recognize, injure, or activate cultured vascular endothelial cells. Cultured endothelial cells incubated with aPL express increased levels of cell adhesion molecules and tissue factor (TF), an effect mediated by β2-GPI, and may promote inflammation and thrombosis. Overexpression of TF has been also shown in monocytes in vitro and ex vivo. TF is the major initiator of coagulation in vivo; thus, its dysregulation may be one of the most important contributors to thrombosis. Effects of aPL upon platelets are not completely elucidated. aPL bind anionic phospholipid but they are normally in the inner side of cell membranes. When platelets are activated by different agonists, anionic phospholipids are exposed. There is some evidence showing that activated platelets are present in aPL-positive patients. Increased levels of β-thrombomodulin, and microvesicle formation seem to support this hypothesis. Activated platelets may contribute to thrombosis by persistent exposure of a procoagulant surface.

Antiphospholipid Antibodies in Patients with Cancer

Antiphospholipid antibodies are generally associated with Antiphospholipid Syndrome, which can occur as a primary disorder or may be secondary to connective tissue disease or tumour. The presence of antiphospholipid antibodies in patients with tumour disease is responsible for thrombotic complications. In a population of 53 tumor patients with positive carcinoembryonic antigen CEA, carbohydrate antigen CA19.9, CA125 and CA15.3 markers, IgM and IgG anticardiolipin and antiphosphatidylinositol were detected by solid-phase immunoassays. Our results show that moderate or high levels of antiphospholipid antibodies are present in a great number of patients with CEA and CA19.9 markers, suggesting a specific association with gastroenteric tumors. By testing for antiphosphatidylinositol antibodies, many patients not evidenced by the standard anticardiolipin assay were found to be antiphospholipid-positive. The analysis of antiphosphatidylinositol antibodies as a diagnostic tool in gastroenteric cancer to highlight patients with the risk of thromboembolic complications is discussed.

Possible Effect of Extended Use of Hormonal Contraception on Increased Levels of Antiphospholipid Antibodies in Infertile Women

Purpose: Increased levels of antiphosholipid antibodies (aPLs) are associated with the autoimmune disorder antiphospholipid syndrome (APS) and are known to play a role in infertility. We investigated the possible effect of prolonged use of hormonal contraception (HC) on autoimmunity after discontinuing HC in women with infertility problems. Material and Methods: We analyzed hormonal status including ovulation and the humoral autoimmune response to eight phospholipids detected by ELISA in 1190 infertile women aged 21-46 (mean age: 29.3) years. Results: Long-term HC did not affect ovulation, but in the absence of ovulation HC masked the hormonal disorders. The majority of patients taking HC for more than 10 years with fertility failure had significantly higher levels of aPLs of the IgG isotype against phosphatidylinositol and phosphatidylserine (p > 0.001) than against β2-glycoprotein I and annexin V. Discussion: Thus, high levels of aPLs are significant for the anticoagulant treatment before and during pregnancy to prevent pregnancy loss.

Autoimmunity: from black water fever to regulatory function

Autoimmunity is a field that has only been around for a little over a century. Initially, it was thought that autoimmunity could not happen, that the body would never turn on itself (i.e. "horror autotoxicus"). It was only around the First World War that autoimmunity was recognized as the pathogenesis of various diseases, including rheumatoid arthritis. The discovery of Compound E led to successful treatment of patients with autoimmune diseases, but it was not till later that the adverse effects of this class of drugs were elucidated. The "modern" age of autoimmunity began around 1945 with the description of blackwater fever, and most of the subsequent research on hemolytic anemia and the role of an autoantibody in its pathogenesis led to a description of the anti-globulin reaction. The lupus erythematous (LE) cell was recognized in the mid-1940s by Hargreaves. His research carried on into the 1960s. Rheumatoid factor was also first described in the 1940s as yet another serum factor with activity against globulin-coated sheep red blood cells. The concept of autoimmunity really gained a foothold in the 1950s, when autoimmune thyroid disease and idiopathic thrombocytopenia were first described. Much has happened since then, and our understanding of autoimmunity has evolved now to include mechanisms of apoptosis, signaling pathway derangements, and the discovery of subsets of T cells with regulatory activity. The modern day study of autoimmunity is a fascinating area of research, and full understanding of the pathogenesis of autoimmune diseases is far from being completely elucidated.

Simultaneous antiphospholipid syndrome and heparin-induced thrombocytopenia in a single patient

Antiphospholipid syndrome and heparin-induced thrombocytopenia are immune-mediated thrombotic conditions initiated by 2 distinct antibodies each targeting a discrete protein-antigen complex. Although produced by 2 different types of antibodies, they are similar in their autoimmune and pathophysiologic mechanisms. We present a case with simultaneous antiphospholipid syndrome and heparin-induced thrombocytopenia syndromes that sheds light on the correlation between these 2 syndromes.

Clinical relevance of antibodies to cardiolipin in patients with chronic hepatitis C

The significance of antibodies to cardiolipin (anti-CL) remains uncertain in patients with chronic hepatitis C (CH-C). The main purpose of this study was to elucidate the clinical characteristics of patients with CH-C seropositive for anti-CL. The prevalence of anti-CL and clinical parameters associated with anti-CL in those patients were examined. Six of the 45 (13%) patients with CH-C had anti-CL. However, none of these six CH-C patients fulfilled the criteria for antiphospholipid syndrome. Serum triglyceride and apolipoprotein B (ApoB) levels in CH-C patients with anti-CL were significantly higher than those in CH-C patients without anti-CL. Serum triglyceride levels positively correlated with serum ApoB levels. CH-C patients with anti-CL had significantly more progressive hepatic fibrosis than those without anti-CL. The degree of 8-hydroxy 2'-deoxyguanosine (8-OHdG) expression in the liver tissue was more severe in CH-C patients with anti-CL than in those without it. However, the emergence of anti-CL in CH-C patients was independent of insulin resistance, hepatic steatosis, and iron overload. These findings suggest that the emergence of anti-CL is associated with oxidative stress and that CH-C patients seropositive for anti-CL have clinical characteristics of hypertriglyceridemia, which derives from the facilitation of ApoB synthesis, and progressive hepatic fibrosis.

C-reactive protein/oxidised low-density lipoprotein/β2-glycoprotein I complex promotes atherosclerosis in diabetic BALB/c mice via p38mitogen-activated protein kinase signal pathway

Background

The aim of this study was to investigate the effect of C-reactive protein/oxidised low-density lipoprotein/β2-glycoprotein I (CRP/oxLDL/β2GPI) complex on atherosclerosis (AS) in diabetic BALB/c mice.

Methods

BALB/c mice were fed high-fat and normal diet. Eight weeks later, the mice fed with high-fat diet were injected with streptozotocin (STZ) to induce diabetes. The diabetic mice were respectively injected twice monthly with 20 μg oxLDL, 20 μg β2GPI, 40 μg oxLDL/β2GPI complex, 44 μg CRP/oxLDL/β2GPI complex, and PBS. Aortas were stained with Sudan IV to investigate lipid plaque formation. The infiltration condition of smooth muscle cells (SMCs), macrophages, and T cells in the aortas were determined by immunohistochemistry (IH). The mRNA expressions of receptors associated with lipid metabolism were quantified by real-time PCR. The phosphorylation of p38 mitogen-activated protein kinase (p38MAPK) and MKK3/6 in aorta tissues were assessed by Western blot. The expression of inflammation cytokines was evaluated by protein chip.

Results

The lipid plaques were more extensive, the lumen area was obviously narrower, the ratio of intima and media thickness were increased, and the normal internal elastic lamia structure and endothelial cell disappeared (P < 0.05) in the oxLDL and CRP/oxLDL/β2GPI groups (P < 0.05). CRP/oxLDL/β2GPI complex dramatically promoted infiltration of SMCs, macrophages, and T cells, improved the mRNA expression of ABCA1 and ABCG1, but reduced the mRNA expression of SR-BI and CD36 and increased the phosphorylation of p38MAPK and MKK3/6 (all P < 0.05). The highest expression levels of IL-1, IL-9, PF-4, bFGF, and IGF-II were detected in the CRP/oxLDL/β2GPI group (P < 0.05).

Conclusions

CRP/oxLDL/β2GPI complex aggravated AS in diabetic BALB/c mice by increasing lipid uptake, the mechanism of which may be mediated by the p38MAPK signal pathway.

Laboratory testing for the antiphospholipid syndrome: making sense of antiphospholipid antibody assays

The antiphospholipid syndrome (APS) is an autoimmune condition characterised by a wide range of clinical features (primarily thrombosis and/or obstetric related), associated with the presence of antiphospholipid antibodies (aPL) as detected by a diverse range of laboratory tests. APS remains a significant diagnostic challenge for clinicians across a wide range of specialities, largely due to issues related to laboratory testing as well as the expanding range of reported clinical manifestations of APS. The laboratory issues include limitations in detailed knowledge by both clinical and laboratory personnel regarding the 'complete' range of available aPL tests, as well as ongoing problems with assay reproducibility and standardisation. aPL are identified using diverse laboratory procedures based on one of two distinct test processes, namely solid phase and liquid phase assays. The former includes anticardiolipin antibodies (aCL) and anti-β(2)-glycoprotein I antibodies (aβ(2)GPI). The latter are centred on clot-based tests that are used to identify the so-called lupus anticoagulant (LA). This article will discuss: (i) issues related to laboratory testing for APS in terms of the currently available solid-phase and liquid-phase assays, and identifiable biases resulting from these tests usually being performed in different laboratories; (ii) current problems with calibration, standardisation and reproducibility of these assays; (iii) pre-analytical, analytical and post-analytical considerations and ongoing initiatives for improvement; (iv) issues related to potential combinations/panels of available aPL tests; and (v) the entities of seropositive APS, seronegative APS and non-APS aPL-positivity. In doing so, this review will hopefully help bridge the two disciplines of haematology and immunology ('representing' liquid-phase and solid-phase aPL testing, respectively), by improving the understanding of those working in each of these disciplines of the merits and limitations of the assays performed in the other discipline, and encouraging inter-discipline cooperation in the reporting of aPL test results.

Increased risk of stroke in patients with bullous pemphigoid: a population-based follow-up study

BACKGROUND AND PURPOSE

Although previous research reveals that cardiovascular events and thromboembolic diseases are important causes of death in patients with bullous pemphigoid (BP), the risk of stroke after the diagnosis of BP relative to the general population remains unknown. Using a randomly selected nationwide population-based sample, this study investigates the risk of stroke in patients with BP compared with unaffected individuals of a similar age.

METHODS

This study analyzes data from Taiwan's National Health Insurance Research Database. This sample included 390 patients with BP and 1950 matched subjects as a comparison group. Stratified Cox proportional hazard regressions were used to calculate the 3-year stroke risk for these 2 groups after adjusting for patient's age, sex, and comorbid medical disorders at baseline.

RESULTS

Of the 2340 patients in the sample, 312 patients (13.3%) had strokes during the 3-year follow-up period, 89 (22.8% of the patients with BP) in the study group and 223 (11.4% of patients without BP) in the comparison group (P<0.001). The hazard ratio for stroke for patients with BP was 2.37 (95% CI, 1.78 to 3.15; P<0.001) times as high that for patients without BP within the 3-year follow-up period after adjusting for hypertension, diabetes, hyperlipidemia, heart failure, atrial fibrillation, and coronary heart disease.

CONCLUSIONS

Patients with BP have an increased risk of stroke and particularly ischemic stroke.

The antiphospholipid syndrome: a large elephant with many parts or an elusive chameleon disguised by many colours?

The antiphospholipid syndrome (APS) is characterized by a range of clinical features (primarily thrombosis and/or obstetric-related), together with the presence of antiphospholipid antibody (aPL) as detected by a diverse range of laboratory tests. APS remains a significant diagnostic and management challenge for clinicians across a wide range of specialties, some 30 years after APS was first described as a discrete clinical entity. This is due to ongoing issues regarding nomenclature, the diagnosis of APS in individual patients, the expanding range of recognized clinical manifestations and of APS-related laboratory tests, and management issues in particular APS patient subgroups (including obstetric and catastrophic APS). In addition to the presence of appropriate clinical features, the diagnosis of APS fundamentally requires the finding of positive aPL test result(s), which is hampered by ongoing problems with assay reproducibility and standardization. This review focuses on ongoing dilemmas and issues related to clinical and laboratory aspects of APS including: (1) diagnostic challenges posed by the protean clinical manifestations of APS; (2) current nomenclature and recent proposals for revision of the 2006 international classification criteria; (3) an overview of some key issues related to aPL testing; (4) potential pitfalls of applying the APS classification criteria as diagnostic criteria; and (5) the controversial subgroups of seronegative APS and non-APS aPL positivity.

Identification of rare anti-phospholipid/protein co-factor autoantibodies in patients with systemic lupus erythematosus

Lupus anticoagulant (LA) and beta2-glikoprotein I (b2GPI) dependent anti-cardiolipin (aCL) are part of the diagnostic criteria both of systemic lupus erythematosus (SLE) and anti-phospholipid syndrome (APS). Anti-phospholipid antibodies (aPL) may also bind to other phospholipids and/or protein co-factors. In the present study, besides aCL and anti-b2GPI, antibodies directed against phosphatidylserine, prothrombin (PT) and annexin V (aANX) were measured in 85 randomly selected SLE patients, 14 suffering from secondary APS. LA was detected by hemostasis tests. Correlations were determined between rare aPLs and clinical manifestations, including thrombotic events. Anti-cardiolipin IgG was positive in 14 patients, aCL IgM in 8, anti-b2GPI IgG in 4 and IgM in 5 patients. LA was detected in nine cases. Seven patients were positive for anti-phosphatidylserine (aPS) IgG, nine for aPS IgM, while anti-PT (aPT) IgG was positive in nine cases. aPT IgM and anti-aANX were negative in all patients. Correlation was found between aPS and aCL antibodies. The frequency and concentration of rare anti-phospholipid/co-factor antibodies was higher in patients with secondary APS. The presence of such rare aPLs cumulated in APS patients, their presence increased the frequency of thrombotic events in the entire study population, furthermore in patients positive for LA or aCL. Rare anti-phospholipid/co-factor antibodies were found in 12% of an un-selected lupus patient population. Their presence was more frequent in patients with secondary APS, and further increased the risk of thrombotic complications.

Pathogenic role of anti-endothelial cell antibodies in autoimmune rheumatic diseases

Anti-endothelial cells antibodies have been detected in numerous autoimmune and inflammatory diseases, including systemic lupus erythematous, rheumatoid arthritis, vasculitis and sarcoidosis. Anti-endothelial cells antibodies bind to endothelial cell antigens and induce endothelial damage. Their effects on the endothelial cell have been considered responsible, at least in part, by the vascular injury which occurs in these pathological conditions.

Anticardiolipin and anti-beta-2-glycoprotein I antibodies

The anticardiolipin (aCL) antibody test was first established in 1983, using cardiolipin (negatively charged phospholipid) as an antigen in a solid-phase immunoassAy. It was first applied to the study of systemic lupus erythematosus patients, and was found associated with thromboses and recurrent pregnancy losses. The wide use of this test was determinant in the definition of the "aCL or antiphospholipid syndrome" (APS).Later, it was demonstrated that aCL antibodies do not recognize anionic phospholipids but are directed against plasma proteins bound to anionic phospholipids, mainly beta-2-glycoprotein I, which is now considered as the autoantigen in APS. Anti-beta-2-glycoprotein I (anti-beta2GPI) is not yet accepted as a serological criterion for APS, but most investigators would consider a patient with anti-beta2GPI antibodies and clinical features of APS to have the syndrome. aCL and anti-beta2GPI are a heterogeneous group of antibodies with different clinical significances and can be present in different autoimmune diseases as well as in infectious diseases.

Multiple steno-obstructive vascular lesions and femoral superficial artery dissection in a young Caucasian male with antiphospholipid syndrome

A young Caucasian male was admitted for claudication intermittens, hyposphygmia on the right lower limb, high blood pressure and deterioration of renal function. Instrumental investigations documented right renal artery stenosis, multiple steno-obstructive manifestations of the splanchnic artery system, occlusion of the right external iliac artery and dissection of the left superficial femoral artery. The patient had not been previously diagnosed with antiphospholipid syndrome. Subsequently, the vascular lesions, because of his thrombophilic state, needed endovascular treatment and anticoagulant therapy.

Antiphospholipid antibodies: paradigm in transition

OBJECTIVES

This is a critical review of anti-phospholipid antibodies (aPL). Most prior reviews focus on the aPL syndrome (APS), a thrombotic condition often marked by neurological disturbance. We bring to attention recent evidence that aPL may be equally relevant to non-thrombotic autoimmune conditions, notably, multiple sclerosis and ITP.

ORGANIZATION

After a brief history, the recent proliferation of aPL target antigens is reviewed. The implication is that many more exist. Theories of aPL in thrombosis are then reviewed, concluding that all have merit but that aPL may have more diverse pathological consequences than now recognized. Next, conflicting results are explained by methodological differences. The lupus anticoagulant (LA) is then discussed. LA is the best predictor of thrombosis, but why this is true is not settled. Finally, aPL in non-thrombotic disorders is reviewed.

CONCLUSION

The current paradigm of aPL holds that they are important in thrombosis, but they may have much wider clinical significance, possibly of special interest in neurology.

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.

The clinical spectrum of antiphospholipid syndrome

Antiphospholipid syndrome (APS) is a disorder characterized by a wide variety of clinical manifestations. Virtually any organ system or tissue may be affected by the consequences of large- or small-vessel thrombosis. There is a broad spectrum of disease among individuals with antiphospholipid antibodies (aPL). Patients may exhibit clinical features suggesting APS but not fulfill the International Criteria for a "definite" diagnosis. Seronegative APS patients demonstrate typical idiopathic thromboses but aPL are not initially detected. Patients defined with definite APS demonstrate nearly identical sites of venous and arterial thrombosis, regardless of the presence or absence of systemic lupus erythematosus. Microangiopathic APS may present with isolated tissue and organ injury or as the overwhelming "thrombotic storm" observed in catastrophic APS.

The Role of Anti-Phospholipid Auto Antibodies Syndrome in Cerebrovascular Diseases

Objectives: The aims of the study are to determine the role of anti-phospholipid autoantibodies (APLAs) among patients with stroke and/or transient ischaemic attacks (TIAs), to identify the types and effective isotype of some important APLAs which are lupus anticoagulant (LA), anticardiolipin (aCL), anti∼fi2 glycoprotein I dependent (afi2-GPI), and anti-phosphatidyl serine (aPS). Also, to find out any concomitant effect of non-APLAparameters not specific to antiphospholipid syndrome (APS).

Subjects and Methods: This study was carried out on 50 patients attending mainly the Teaching and General Hospitals in Mosul, Duhok, and Erbil Cities, Iraq during the period between 1st March 2004 and 1st March 2005. The studied cases were under 50 years of age, and had no recognizable risk factors. The activated partial thromboplastin time (APTT) was used for LA estimation and ELISA assay was used to test for IgG& IgM isotypes ofaCL, aJ32-GPI, and aPS. The ANA, RF, VDRL, CRP, and C4 complement were tested by different immuoserological methods. The thrombocytopenic (TP) status was diagnosed by estimation of platelets counts.

Results: The strokes and!or TIAs related to APS were diagnosed in 22/50 (44%) of patients and a significant correlation was reported among patients with IgG plus IgM aCL (p <  0.05), IgG afi2-GPI (p <  0.05), and IgG aPS (p <  0.05). In APLAs positive patients, raised CRP concentrations were reported in 36.4%, TP status in 22.7%, ANA in 22.7%, RF positive in 13.6%, and low C4 levels in l3.6%. Finally,the FP-VDRL test was found in 50 % of APLAs positive cases.

Conclusions: The aCL, afi2- GPI, and aPS antibodies were shown to play a significant role in the development of stroke and!or TIAs among the studied cases.

Intravenous immunoglobulin to prevent recurrent thrombosis in the antiphospholipid syndrome

The antiphospholipid syndrome (APS) occurs as a primary entity or in association with autoimmune diseases, malignancies, or medications. Conventional treatment for APS-associated thrombosis involves the use of anticoagulants such as aspirin, heparin, and warfarin. Alternative treatment options are limited. We report on a patient with APS who failed conventional therapy but had clinical improvement and a decline in anticardiolipin (aCL) antibody titers during treatment with monthly intravenous immunoglobulin (IVIg). Anticardiolipin antibodies IgG, IgA, and IgM were measured before initiating IVIg and before each subsequent infusion of IVIg. The patient was also evaluated for the presence of thromboses during the treatment period. IgG and IgA aCL levels were elevated initially, and there was a significant decrease in anticardiolipin IgG and IgA levels during treatment without further episodes of thrombosis. IVIg may be an alternative therapy for recurrent thrombosis in the antiphospholipid antibody syndrome.

Coalescence of phospholipid membranes as a possible origin of anticoagulant effect of serum proteins

Interactions between phospholipid membranes (made of palmitoyloleoylphosphatidylcholine, cardiolipin and cholesterol) after addition of beta2 glycoprotein I (beta2GPI) or anti-beta2GPI antibodies or a mixture of both were studied by observing giant phospholipid vesicles under the phase contrast microscope. Both, negatively charged and neutral vesicles coalesced into complexes and adhered to the bottom of the observation chamber in the presence of beta2GPI in solution. Anti-beta2GPIs alone or previously mixed with beta2GPI caused coalescence of charged but not neutral vesicles, i.e. for neutral membranes the effect of beta2GPI was abolished by the presence of anti-beta2GPIs. Since the presence of the above adhesion mediators can prevent fragmentation of the membrane we propose a (new) possible anticoagulant mechanism for some serum proteins by preventing the release of prothrombogenic microexovesicles into circulation.

Platelet activation rather than endothelial injury identifies risk of thrombosis in subjects positive for antiphospholipid antibodies

BACKGROUND

Anti-phospholipid antibodies (APLA) are often associated with thrombosis, defining the antiphospholipid syndrome (APS) but it remains unclear why many subjects who are positive for APLA chiefly anti-cardiolipin (aCL) or anti-beta2GPI (abeta2GPI) do not develop thrombosis. A related question addressed in this study is whether the target of cellular injury in APS is predominately platelets or endothelial cells (EC).

METHODS

aCL and abeta2GPI were determined by ELISA in 88 patients, 60 of whom were thrombotic and 28 non-thrombotic. Platelet activation was measured by CD62P and by concentration of platelet microparticles (PMP) and EC activation was assessed by endothelial microparticles (EMP), both by flow cytometry. Lupus anticoagulant (LAC) was measured in the hospital laboratory.

RESULTS

There was no difference in frequency of aCL or abeta2GPI, neither IgG or IgM, between the thrombotic and non-thrombotic groups. Both groups showed elevated EMP compared to controls but this did not differ between thrombotic and non-thrombotic groups. In contrast, PMP were not significantly elevated in non-thrombotic but were elevated in thrombotic compared to non-thrombotic (p=0.03) and controls. CD62P, an independent marker of platelet activation, was also elevated in thrombotic vs. non-thrombotic. There was a trend for increased LAC in the thrombotic group but not significant.

CONCLUSION

Although all subjects had evidence of endothelial activation, only platelet activation differed between thrombotic and non-thrombotic. This supports the hypothesis that platelet activation predisposes to thrombosis in the presence of chronic EC activation. These data also raise the possibility of distinguishing risk-prone APLA-positive individuals.

Pregnancies Complicated with Antiphospholipid Syndrome: The Pathogenic Mechanism of Antiphospholipid Antibodies: A Review of the Literature

There are several possible mechanisms by which antiphospholipid antibodies (aPL) may have adverse effects on placental functions. Examination of placentas and first-trimester decidua from antiphospholipid syndrome-complicated pregnancies has found little evidence of specific thrombotic placental pathology. It is now generally accepted that the clinically relevant aPL bind to proteins with affinity for phospholipids. The most important epitope for antiphospholipid syndrome-related aPL resides on beta2-glycoprotein-I (beta2GPI). aPL detected by anti-beta2GPI assays are associated with fetal loss. During differentiation to syncytium, trophoblasts express cell membrane anionic phospholipids that can bind beta2GPI. Adhered beta2GPI can be recognized by the antibodies that, once bound, interfere with trophoblast cell maturation, resulting in defective placentation. The improved outcome of pregnancies treated with heparin stimulated interest on the drug's mechanism of action. Several mechanisms could explain its beneficial effects in addition to a direct effect of heparin on the coagulation cascade. It might reduce the binding of aPL, inflammation by inhibiting complement activation, and might facilitate implantation. Further investigations are needed to better understand how aPL induce obstetric complications and to better clarify the functional role of heparin in the human placenta, leading to more successful therapeutic options.

Antiphospholipid antibodies: lessons from the bench

Antiphospholipid antibodies (aPL) are an heterogeneous group of circulating immunoglobulins arising in a wide range of infectious and autoimmune diseases. Since the early 80s, the interest on anticardiolipin antibodies (aCL) has exponentially increased due to their association with thrombosis. The antiphospholipid syndrome (APS) was defined as a clinical disorder characterized by thrombosis and pregnancy morbidity associated to the persistent presence of aCL and/or lupus anticoagulant (LA). Thrombosis is the major manifestation in patients with aPL, but the spectrum of symptoms and signs associated with aPL has considerably broadened, and other manifestations such as thrombocytopenia, non-thrombotic neurological syndromes, psychiatric manifestations, livedo reticularis, skin ulcers, haemolytic anemia, pulmonary hypertension, cardiac valve abnormality and atherosclerosis have also been related to the presence of those antibodies. Numerous mechanisms have been proposed to explain the thrombotic tendency of patients with aPL, but the pathogenesis seems to be multifactorial.

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.

Anti-beta2GPI-antibody-induced endothelial cell gene expression profiling reveals induction of novel pro-inflammatory genes potentially involved in primary antiphospholipid syndrome

OBJECTIVE

To determine the effects of primary antiphospholipid syndrome (PAPS)-derived anti-beta(2)GPI antibodies on gene expression in human umbilical vein endothelial cells (HUVEC) by gene profiling using microarrays.

METHODS

Anti-beta(2)GPI antibodies purified from sera of patients with PAPS or control IgG isolated from normal subjects were incubated with HUVEC for 4 h before isolation of RNA and processing for hybridisation to Affymetrix Human Genome U133A-2.0 arrays. Data were analysed using a combination of the MAS 5.0 (Affymetrix) and GeneSpring (Agilent) software programmes. For selected genes microarray data were confirmed by real-time PCR analysis or at the protein level by ELISA.

RESULTS

A total of 101 genes were found to be upregulated and 14 genes were downregulated twofold or more in response to anti-beta(2)GPI antibodies. A number of novel genes not previously associated with APS were induced, including chemokines CCL20, CXCL3, CX3CL1, CXCL5, CXCL2 and CXCL1, the receptors Tenascin C, OLR1, IL-18 receptor 1, and growth factors CSF2, CSF3 IL-6, IL1beta and FGF18. The majority of downregulated genes were transcription factors/signalling molecules including ID2. Quantitative real-time RT-PCR analysis confirmed the microarray results for selected genes (CSF3, CX3CL1, FGF18, ID2, SOD2, Tenascin C).

CONCLUSIONS

This study reveals a complex gene expression response in HUVEC to anti-beta(2)GPI antibodies with multiple chemokines, pro-inflammatory cytokines, pro-thrombotic and pro-adhesive genes regulated by these antibodies in vitro. Some of these newly identified anti-beta(2)GPI antibody-regulated genes could contribute to the vasculopathy associated with this disease.

The prevalence and clinical significance of antiphospholipid antibodies in rheumatoid arthritis

Published data were reviewed to evaluate the occurrence of antiphospholipid antibodies (aPL) in rheumatoid arthritis (RA) patients and to investigate their clinical relevance in this population. The mean prevalence was calculated at 28% and the median was 22%. Few studies have found a relationship between aPL antibodies and thrombosis, particularly in combination with other risk factors. Conflicting results have been reported on the association of anticardiolipin (aCL) antibody positivity and neurologic symptoms, Reynaud's phenomenon, disease activity, radiographic erosions, extra-articular RA manifestations, rheumatoid factor, and atherosclerosis. Some studies, however, suggest that there is a correlation present between those antibodies and C-reactive protein levels, rheumatoid nodules, and antinuclear antibodies. TNF-alpha blocking agents may cause an induction of aCL antibodies, but it seems like they do not cause any clinical features related to the antiphospholipid syndrome. Higher 17beta-estradiol levels were observed in aCL antibody-positive RA patients than in aCL antibody-negative patients and especially in premenopausal women, which may predispose to a more efficient immune response.

Primary antiphospholipid syndrome: A distinct entity?

Although antiphospholipid syndrome (APS) was first fully described in the context of connective tissue diseases such as systemic lupus erythematosus (SLE), it was soon recognised that the condition can exist on its own. APS appears to represent a clinical spectrum, both in terms of APS features and the presence of other autoimmune conditions. The clinical and serological characteristics of "primary" APS (PAPS) are similar to those of secondary APS, although the clinical features are more commonly recognised in the presence of another autoimmune or inflammatory condition. Furthermore, patients with PAPS may subsequently develop SLE. It is important to identify PAPS, since it is likely to be a contributing factor for a significant proportion of patients with a variety of vascular, neurological and other conditions. It may emerge as more common than secondary APS.

A prospective study of anticardiolipin antibodies as a risk factor for venous thrombosis in a general population (the HUNT study)

We prospectively examined whether there is an association between elevated anticardiolipin antibody levels and the risk for a future first venous thrombosis (VT) in a general population. We studied this in a large population-based nested case-cohort study of 508 VT cases and 1464 matched control subjects from a cohort of 66,140 participants in the Health Study of Nord-Trøndelag in Norway. Venous thrombosis was validated using standardized criteria for venous thrombosis and pulmonary embolism. Prethrombotic serum anticardiolipin antibodies were measured by an enzyme-linked immunoassay. There was no association between elevated anticardiolipin antibody levels and subsequent venous thrombosis, overall or after stratification by sex, different age groups or idiopathic vs. secondary thrombosis. The overall odds ratio was 1.11 (95% CI: 0.71-1.74) for greater than vs. less than the 95th percentile of anticardiolipin antibody levels. In conclusion, in this general population sample elevated anticardiolipin antibody levels was not a risk factor for subsequent venous thrombosis.

Antiphospholipid antibodies bind ATP: a putative mechanism for the pathogenesis of neuronal dysfunction

Antiphospholipid antibodies (aPL) generated in experimental animals cross-react with ATP. We therefore examined the possibility that aPL IgG from human subjects bind to ATP by affinity column and an enzyme linked immunosorbent assay (ELISA). Sera with high levels of aPL IgG were collected from 12 patients with the antiphospholipid syndrome (APS). IgG fractions from 10 of 12 APS patients contained aPL that could be affinity-bound to an ATP column and completely eluted with NaCl 0.5 M. A significant (>50%) inhibition of aPL IgG binding by ATP 5 mM was found in the majority. Similar inhibition was obtained with ADP but not with AMP or cAMP. All the affinity purified anti-ATP antibodies also bound β₂-glycoprotein-I (β₂-GPI, also known as apolipoprotein H) suggesting that, similar to most pathogenic aPL, their binding depends on this serum cofactor. We further investigated this possibility and found that the binding of β₂-GPI to the ATP column was similar to that of aPL IgG in that most was reversed by NaCl 0.5 M. Furthermore, addition of β₂-GPI to aPL IgG significantly increased the amount of aPL binding to an ATP column. We conclude that aPL IgG bind ATP, probably through β₂-GPI. This binding could interfere with the normal extracellular function of ATP and similar neurotransmitters.

Anticardiolipin antibodies and ocular disease

This paper reviews anticardiolipin antibodies and ocular disease. Its aim is to present the latest knowledge regarding the relationship between the two. It focuses mainly on ocular features and treatment, but also describes the epidemiology, main systemic features, immunology, and immunopathology of the antiphospholipid syndrome.