Autoantibodies against a complement component 1 q subcomponent contribute to complement activation and recurrent thrombosis/pregnancy morbidity in anti-phospholipid syndrome.

OBJECTIVE: To investigate the prevalence and significance of the autoantibodies against complement component 1 q subcomponent (C1q) in patients with APS. METHODS: In all, 40 consecutive primary APS patients, 42 patients with non-SLE CTDs and 20 SLE patients negative for aPL were enrolled in this retrospective analysis. Refractory APS was defined as a clinical status of recurring thrombosis or pregnancy morbidity during adequate secondary prophylaxis. An ELISA was used to measure serum levels of anti-C1q antibodies and anaphylatoxins (C3a, C4a). RESULTS: Anti-C1q antibodies were found in 36% (15/42) and 2.5% (1/40) of primary APS patients and controls, respectively. Among primary APS patients, anti-C1q antibody titres were significantly correlated with serum C4a levels (P = 0.013). Neither the prevalence nor the titre of anti-C1q antibodies was associated with any specific clinical manifestations of APS, nor titres of aPL. Refractory APS patients (n = 10) had a higher prevalence of anti-C1q antibodies (9/10 vs 6/32, P = 0.01) than APS patients without recurrence (n = 32). CONCLUSION: Anti-C1q antibodies are associated with complement activation in APS and may contribute to the pathogenesis, particularly in refractory cases.

Antiphospholipid antibodies and the risk of recurrence after a first episode of venous thromboembolism: a systematic review.

Laboratory evidence of antiphospholipid antibodies (APLA) in patients with a first episode of venous thromboembolism (VTE) is often considered an indication for indefinite anticoagulant therapy, but it is uncertain if this practice is justified. We performed a systematic review to determine whether the presence of APLA in patients with a first VTE is associated with an increased risk of recurrence. We searched PubMed, CINAHL, Cochrane, EMBASE, and Web of Knowledge through February 2012 and included prospective studies that met prespecified design criteria. There were 109 recurrent VTE in 588 patients with APLA and 374 recurrent VTE in 1914 patients without APLA (relative risk 1.41; 95% confidence interval [CI], 0.99 to 2.36). The unadjusted risk ratio for recurrent VTE after stopping anticoagulant therapy in patients with an anticardiolipin antibody was 1.53 (95% CI, 0.76-3.11), and with a lupus anticoagulant was 2.83 (95% CI, 0.83-9.64). All studies had important methodologic limitations and we judged the overall quality of the evidence as very low. Although a positive APLA test appears to predict an increased risk of recurrence in patients with a first VTE, the strength of this association is uncertain because the available evidence is of very low quality.

Antiphospholipid antibodies do not cause retargeting of placental extracellular vesicles in the maternal body.

Antiphospholipid antibodies (aPL) are autoantibodies that cause pregnancy disorders by a poorly defined mechanism that involves the placenta. The human placenta is covered by a single multinucleated cell, the syncytiotrophoblast, which extrudes vast numbers of extracellular vesicles (EVs) into the maternal blood. Extracellular vesicles are tiny packages of cellular material used by cells for remote signalling. In normal pregnancy, placental EVs assist maternal adaptations to pregnancy. We have previously shown that aPL alter the cargo of placental EVs, increasing the load of danger signals. These changes in EV cargo may explain how aPL contribute to the increased risk of recurrent miscarriage, preeclampsia and stillbirths observed in aPL-affected pregnancies. An additional possibility, that aPL alters the targeting of placental EVs to maternal organs to cause maternal maladaptation to pregnancy was investigated in this study.

Novel autoantibodies against the activated coagulation factor IX (FIXa) in the antiphospholipid syndrome that interpose the FIXa regulation by antithrombin.

We previously reported that some human antiphospholipid Abs (aPL) in patients with the antiphospholipid syndrome (APS) bind to the homologous enzymatic domains of thrombin and the activated coagulation factor X (FXa). Moreover, some of the reactive Abs are prothrombotic and interfere with inactivation of thrombin and FXa by antithrombin (AT). Considering the enzymatic domain of activated coagulation factor IX (FIXa) is homologous to those of thrombin and FXa, we hypothesized that some aPLs in APS bind to FIXa and hinder AT inactivation of FIXa. To test this hypothesis, we searched for IgG anti-FIXa Abs in APS patients. Once the concerned Abs were found, we studied the effects of the Ab on FIXa inactivation by AT. We found that 10 of 12 patient-derived monoclonal IgG aPLs bound to FIXa and that IgG anti-FIXa Abs in APS patients were significantly higher than those in normal controls (p < 0.0001). Using the mean + 3 SD of 30 normal controls as the cutoff, the IgG anti-FIXa Abs were present in 11 of 38 (28.9%) APS patients. Importantly, 4 of 10 FIXa-reactive monoclonal aPLs (including the B2 mAb generated against beta(2)-glycoprotein I significantly hindered AT inactivation of FIXa. More importantly, IgG from two positive plasma samples were found to interfere with AT inactivation of FIXa. In conclusion, IgG anti-FIXa Ab occurred in approximately 30% of APS patients and could interfere with AT inactivation of FIXa. Because FIXa is an upstream procoagulant factor, impaired AT regulation of FIXa might contribute more toward thrombosis than the dysregulation of the downstream FXa and thrombin.

Chorea in systemic lupus erythematosus.

BACKGROUND: Chorea is recognized as one of the neurologic manifestations of systemic lupus erythematosus (SLE). Most reports show an association between chorea and antiphospholipid (aPL) antibodies in SLE patients. OBJECTIVES: The objective of this study was to describe the association of aPL antibodies with lupus chorea and its possible role in the pathogenesis of chorea. METHODS: We made a retrospective review of all cases of lupus chorea between 1989 and 2007 in a tertiary care center in Mexico City. RESULTS: We found 7 episodes of chorea in 5 patients with SLE. In 2 patients (3 episodes), chorea was associated with cerebral ischemia; one of these cases had positive anticardiolipin (aCL) immunoglobulin G (IgG) antibodies, whereas the other was diagnosed as having vascular lipohyalinosis as the probable cause of cerebral ischemia. In 3 patients (4 episodes), an immune-mediated mechanism was suspected; these cases had negative aPL at the onset of chorea, but IgM aCL antibodies became positive later. CONCLUSIONS: In most episodes, chorea seems to be immunologically mediated and was associated with a later appearance of IgM aCL antibodies. Chorea in patients with lupus may also be caused by cerebral ischemia, and in some cases, it may be associated with IgG aCL antibodies.

The roll of Toll-like receptors in the antiphospholipid syndrome.

The antiphospholipid syndrome (APS) is an autoimmune disease characterized by thrombosis, recurrent fetal loss, and the presence of antiphospholipid antibodies (aPL). Recent data support the idea that the thrombotic activity in APS patients is attributed to enhanced cytokine release via activation of certain Toll-like receptors. To investigate these mechanisms more precisely, different experimental approaches were used to investigate this connection in detail. IgG fractions and/or monoclonal aPL, either generated from murine or human B cells were intensely used for stimulation experiments of monocytes, endothelial cells, or dendritic cells. All these stimuli induced an enhanced expression and secretion of cytokines, especially tumor necrosis factor (TNF)-alpha, caused by specific regulation or activation of Toll-like receptors. Using specific agonists or inhibitors could confirm the causal connection of these stimulatory effects. This review focuses on these recent developments, connecting the binding of aPL with the activity of Toll-like receptors, especially in monocytes, endothelial cells, and dendritic cells.

Antiphospholipid syndrome. Current insights into laboratory diagnosis and pathophysiology.

The antiphospholipid syndrome (APS) is a non-inflammatory autoimmune disease characterized by the presence of antiphospholipid antibodies (aPL) in the plasma of patients with vascular thrombosis, recurrent complications of pregnancy, or both (1, 2). The presence of aPL in plasma of patients can be detected with either a prolongation of phospholipid dependent coagulation tests (lupus anticoagulant, LAC), or with solid phase immune assays against the protein beta2-glycoprotein I (beta2-GPI) or the phospholipid cardiolipin (anti-beta2-GPI antibody ELISA and anti-cardiolipin antibody ELISA, respectively) (3). For a long time there was a lot of confusion on who had the syndrome and who not. To solve this dispute, an international consensus meeting was organized in Sapporo in 1999 to formulate classification criteria for patients with the antiphospholipid syndrome (4). These criteria have been updated in 2004 at another international consensus meeting in Sydney (5). The classification criteria were defined for scientific purposes and were aimed to be used as inclusion criteria in patient related studies. They were specifically not defined for diagnostic purposes. However, current practice is that these criteria are used as a diagnostic tool. This is very unfortunate because the specificity of the different aPL assays to detect the clinical manifestations that characterize APS are disputable. One of the aims of defining the criteria was to initiate studies to determine the value of the different anti-phospholipid antibody assays to serve as biomarker for the risk of thrombosis and pregnancy morbidity. The recent progress made on this important topic will be discussed.

Autoantibodies associated with neuropsychiatric systemic lupus erythematosus: the quest for symptom-specific biomarkers.

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that affects multiple organs, including the central nervous system. Neuropsychiatric SLE (NPSLE) is a severe and potentially fatal condition. Several factors including autoantibodies have been implicated in the pathogenesis of NPSLE. However, definitive biomarkers of NPSLE are yet to be identified owing to the complexity of this disease. This is a major barrier to accurate and timely diagnosis of NPSLE. Studies have identified several autoantibodies associated with NPSLE;some of these autoantibodies are well investigated and regarded as symptom-specific. In this review, we discuss recent advances in our understanding of the manifestations and pathogenesis of NPSLE. In addition, we describe representative symptom-specific autoantibodies that are considered to be closely associated with the pathogenesis of NPSLE.

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.

The role of antiphospholipid antibodies toward the protein C/protein S system in venous thromboembolic disease.

The association between venous thromboembolism (VTE) and antibodies anti-Protein C (PC)/Protein S (PS) is still uncertain. We performed a case-control study to determine the risk of VTE related to the presence of these auto-antibodies considered independently of the presence of lupus anticoagulant (LAC) or anti-cardiolipin antibodies (ACA). One hundred thirty-five patients with idiopathic VTE and 164 healthy subjects were enrolled. Anti-PC and anti-PS antibodies (both IgG and IgM) were assessed using commercially available ELISA kits. Among cases there was a higher prevalence of elevated anti-PC IgM antibodies than in controls (OR 2.44, 95%CI 1.00-5.94). The presence of anti-PC IgG and anti-PS IgG and IgM antibodies was also higher in cases than in controls, but the difference was not statistically significant. Only five patients had both anti-PC or anti-PS antibodies and LAC or ACA. We performed a stepwise multivariate logistic regression analysis showing that anti-PC IgM>958 percentile was a significant predictor of VTE after adjustment for LAC or ACA (OR 2.52, 95%CI 1.01-6.24)). Larger prospective studies are needed to confirm this finding.

Impact of antiphospholipid biology in maternal Down syndrome screening.

OBJECTIVE: Women with antiphospholipid (aPL) biology present obstetric complications. The alpha-fetoprotein (AFP) serum levels of these patients are higher than in general population. Because AFP is involved in the calculation of the risk of trisomy 21 (T21), we studied the effect of AFP variations in the presence of aPL during T21 screening. METHODS: The study group (aPL group) was comprised of 64 pregnancies in women with aPL antibodies. The control group was comprised of 21 655 pregnancies included in the national program for routine Down syndrome (DS) screening by maternal serum markers [human chorionic gonadotrophin (hCG) and AFP] between 14 + 0 and 18 + 6 weeks of gestation. RESULTS: AFP values, converted in logarithm of multiples of the median (MoM), were significantly higher in the aPL group (0.03 vs 0.10; p = 0.018). After a matricial transformation of AFP MoM and hCG MoM in the aPL group, new T21 risks presented a median of one in 1665 versus one in 2574 (p < 0.0001 with a rank-sign test). CONCLUSION: Our results highlight the fact that in the presence of aPL antibodies, the calculated risk of T21 is underestimated. Therefore, clinicians should interpret the screening borderline results in aPL patients with caution.

Predictive, protective, orphan autoantibodies: the example of anti-phospholipid antibodies.

Anti-phospholipid antibodies (aPL) are one of the most recent examples of autoantibodies that can appear even long time before any clinical manifestation can be associated with them. There is a general agreement that they may represent a strong risk factor for recurrent thrombosis and/or fetal losses. Anti-phospholipid antibodies represent a necessary but not sufficient factor (first hit) for thrombosis, and require additional triggering factors (second hit) to disclose the thrombogenic activity. Several factors may affect the predictive value of aPL, including titre, immunoglobulin isotype, fine antigenic specificity and affinity binding activity. Their careful evaluation is suggested in order to characterize the true predictive value of aPL.

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.

Antiphospholipid syndrome in pregnancy.

During the past 5 years the author and his colleagues have assessed carefully 351 women referred for evaluation of thrombosis and hemostasis after they had suffered recurrent miscarriages. This article describes the flow protocol the author and associates follow to maximize success and keep the costs of evaluation of recurrent miscarriage syndrome/infertility at a minimum while providing the best chances for defining a cause and thus providing optimal therapy for successful term pregnancy outcome. It presents the outcomes of the author's protocol and those of others in treating women who have antiphospholipid syndrome and who have suffered recurrent miscarriages.

Modulation of fibrinolysis by the combined action of phospholipids and immunoglobulins.

Because both immunoglobulin G (IgG) and phospholipids interfere with fibrinolysis, their combined modulating effects were investigated in experimental models of three consecutive steps of the fibrinolytic process [diffusion of tissue-type plasminogen activator (tPA) into the clot, plasminogen activation on fibrin surface and fibrin dissolution by plasmin] using IgGs isolated from healthy subjects and from patients with antiphospholipid syndrome in combination with mixtures of synthetic dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylserine. In fibrin clots containing phospholipids the normal IgG enhanced the barrier function of the phospholipids with respect to the diffusion of tPA and plasminogen activation, but did not modify the lysis by plasmin. One of the examined antiphospholipid syndrome-IgGs also restricted the diffusion of tPA, but it accelerated the plasminogen activation on the fibrin surface and slowed down the lysis of fibrin by plasmin. Another antiphospholipid syndrome IgG, which did not affect significantly the tPA penetration into the fibrin gel, did not modify the plasminogen activation on its own, but it partially opposed the inhibiting effect of phospholipids on plasmin formation and accelerated the end-stage lysis of fibrin containing phospholipids. The IgGs from the two examined antiphospholipid syndrome patients did not show consistent deviation from the pattern of normal IgG effects on fibrinolysis in phospholipid environment. Thus, a high degree of heterogeneity with respect to the profibrinolytic or antifibrinolytic effects of the pathological IgGs can be expected in the antiphospholipid syndrome patient population, which may contribute to the variable thrombotic symptoms in this clinical syndrome.

Neurological dysfunction and hyperactive behavior associated with antiphospholipid antibodies. A mouse model.

Antiphospholipid antibodies (aPL) have been associated with various neurological manifestations, but the underlying mechanism has not been elucidated. We assessed mice with induced experimental antiphospholipid syndrome (APS) for neurological and behavioral changes. After immunization with monoclonal human anticardiolipin antibody (H-3), female BALB/c mice developed elevated levels of circulating anti-negatively charged phospholipids (aPL), anti-beta2-glycoprotein I (abeta2GPI), and anti-endothelial cell antibodies (AECA), along with clinical manifestations of APS like thrombocytopenia and fetus resorption. APS mice were impaired neurologically and performed several reflexes less accurately compared to the controls, including placing reflex (P < 0.05), postural reflex (P < 0.05), and grip test (P = 0.05). The APS mice also exhibited hyperactive behavior in an open field, which tests spatial behavior (P < 0.03), and displayed impaired motor coordination on a rotating bar. aPL in combination with abeta2GPI and AECA is probably involved in the neurological and behavioral defects shown in mice with experimental APS.

Anti-endothelial cell antibodies and antiphospholipid antibodies in Takayasu's arteritis: correlations of their titers and isotype distributions with disease activity.

OBJECTIVE: To investigate the prevalence of anti-endothelial cell antibodies (AECA) and antiphospholipid antibodies, and the correlations of their isotype distributions and titers with disease activity in patients with Takayasu's arteritis (TA). METHODS: Forty-seven patients with TA and 30 age- and sex-matched controls were studied. Blood samples were obtained from all patients and they were divided into either active or stable disease groups. Paired samples were available in 18 patients at both active and stable stage, respectively. AECA against human umbilical vein endothelial cells and antiphospholipid antibodies were measured. RESULTS: Forty-two (89.4%) TA patients had AECA, and positivity rates of IgM and IgG AECA were 83.0% and 68.1%, respectively, while those for controls were both 3.3%. The titers of IgM and IgG AECA in patients were significantly higher than those in controls. IgM AECA titers of the active group were significantly higher than those of the stable group, but IgG AECA titers were not. In 18 patients with paired samples, IgM AECA titers at active stage were significantly higher than those at stable stage, but IgG AECA titers were not different between stages. The changes of IgM AECA titers correlated well with those of ESR levels between stages. Antiphospholipid antibodies were detected in only 4 patients with TA, but not in controls. CONCLUSION: IgM AECA and IgG AECA were more prevalent and their titers were higher in patients with TA than in controls, and IgM AECA titers correlated well with the disease activity of TA. Antiphospholipid antibodies were not found significant.

Antiphospholipid antibodies in medical practice: a review.

BACKGROUND: Antiphospholipid antibodies are autoantibodies that have been associated with . thrombosis and recurrent foetal loss. The purpose of this review is to highlight the history of these antibodies, their epidemiology, to document what is known of their pathogenesis, clinical features, diagnosis and available treatment modalities. METHODS: Literature on the subject was reviewed using manual library search, articles in journals, internet search and conference abstracts. RESULT: Antiphospholipid antibodies have been detected in all age groups; incidence increases with age. They are antibodies to protein-phospholipid complexes and not to phospholipid alone. The most commonly detected antiphospholipid antibodies are lupusanticoagulant (LA), anticardiolipin antibodies and anti--2 glycoprotein-1 antibodies. Apart from thrombosis and recurrent foetal loss, they are also associated with neurologic disorders, cutaneous manifestations and thrombocytopaenia. CONCLUSION: Early detection requires a strong index of suspicion especially when thrombosis is seen at unusual sites. Several modalities of treatment such as anticoagulants and antiplatelet agents have been developed, though it is difficult to monitor level of anticoagulation as the antibodies may interfere with coagulation studies. Grey areas remain in the management of antiphospholipid antibodies; for instance it is not certain if patients with a positive laboratory test without any clinical feature should be treated.

[New insights into the pathogenicity of antiphospholipid antibodies].

Antiphospholipid antibodies (aPL) recognize phospholipid-binding proteins such as beta(2)-glycoprotein I (beta(2)-GPI) and prothrombin, inducing thrombosis and pregnancy morbidities. Pathogenicity of aPL has been established by many in vivo experiments in which administration of aPL resulted in pregnancy losses and/or thrombotic phenomena. The mechanisms how aPL cause such symptoms have been extensively investigated. aPL alters fibrinolysis/coagulation system by suppression of protein C/Z systems in the presence of beta(2)-GPI. B cell epitopes were also studied for specific therapies, resulting in diverse candidates such as domain I, IV or other domains. For T cells, importance of cryptic epitope on domain V was suggested. Recently, activation of endothelial cells, monocytes and thrombocytes by aPL with beta(2)-GPI has been reported. This activation is mainly mediated by p38MAP kinase activation and results in expression of tissue factor and adhesion molecules in endothelial cells and monocytes, thromboxane B2 in thrombocytes. Annexin II, toll-like receptor 4, LDL-receptor family members, and glycoprotein Ib are the candidates for cell surface ligands, suggesting the possibility of their blockades by monoclonal antibodies. Although treatment of APS is now limited to nonspecific anticoagulants or anti-platelet agents, based on these new insights, specific therapies targeting signal molecules and/or cell surface ligands for beta(2)-GPI should be introduced in near future.