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.

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.

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 placenta: a systematic review of their in vitro effects and modulation by treatment.

BACKGROUND: Antiphospholipid antibodies (aPL) are a family of auto-antibodies that are associated with an increased risk of recurrent miscarriage, intrauterine growth restriction and preterm birth. The placenta is a major target of aPL and it is likely that these antibodies promote pregnancy morbidity by affecting trophoblast function. Numerous studies have investigated the effect of aPL on trophoblast function in vitro. However, different trophoblast models and a variety of culture conditions have been employed, resulting in a myriad of different reported findings. This review systematically summarized those published studies that have investigated the effect of aPL on trophoblast function in vitro. In addition, the reported effects of pharmacological treatment on trophoblast function in the presence of aPL were also systematically reviewed. METHODS: PubMed, Scopus, Embase and Web of Science databases were searched using the keywords 'placenta OR trophoblast' AND 'antiphospholipid antibody OR antiphospholipid syndrome' up to 25 April 2014. Studies were excluded based on the absence of appropriate controls. The effects of aPL on trophoblast proliferation, death, syncytialization, invasion, hormone production, cytokine production, coagulation and complement activation were recorded. The effects of different treatments on the function of trophoblasts in the presence of aPL were also recorded. RESULTS: A total of 1071 records were retrieved from the four databases. After removing duplicates, the titles and abstracts of 529 articles were reviewed. Of those, 48 articles were read and relevant experimental results were extracted from 47 articles. CONCLUSIONS: This systematic review provides an overview of all the studies performed to date on the effects of aPL on trophoblast function in vitro. There is considerable support for aPL decreasing trophoblast viability, syncytialization and invasion in vitro. Some work has also suggested that aPL may affect the production of hormones and signalling molecules by trophoblasts, and may stimulate coagulation and complement activation in vitro. Current reports of the in vitro effects of therapeutic treatments on trophoblast function in the presence of aPL are inconclusive. This systematic review has highlighted many gaps in our knowledge of how aPL work and may direct future research in this area.

Role of Toll-like receptors 2 and 4 in mediating endothelial dysfunction and arterial remodeling in primary arterial antiphospholipid syndrome.

OBJECTIVE: To assess the role of Toll-like receptors (TLRs) in antiphospholipid antibody (aPL)-mediated vascular abnormalities in patients with primary arterial antiphospholipid syndrome (APS). METHODS: Forty-eight subjects participated in the study. Arterial function and structure and TLR pathway activation were determined in patients with primary arterial APS and matched controls. The pathogenic effects of aPL isolated from patients were assessed in wild-type (WT) and TLR-knockout mice. RESULTS: APS patients had endothelial dysfunction, arterial stiffening, and hypertrophy, as evidenced by decreased brachial artery endothelium-dependent flow-mediated dilation (FMD) and increased aortic pulse wave velocity and carotid intima-media thickness (IMT), as compared with controls. Plasma samples from APS patients revealed decreased nitric oxide (NO) availability and a pro-oxidative, proinflammatory, and prothrombotic state illustrated by a decrease in nitrite and an increase in lipid peroxidation, tumor necrosis factor α levels, and tissue factor (TF) levels. Furthermore, TLR pathway activation was found in APS patients with increased TLR-2 and TLR-4 messenger RNA expression and increased protein levels of the activated TLR transduction protein interleukin-1 receptor-associated kinase 1 in peripheral blood mononuclear cells. Moreover, agonist-stimulated cell-surface expression of TLR-2 and TLR-4 in circulating monocytes was higher in APS patients than in controls. These changes were positively associated with IMT and negatively associated with FMD. Finally, aPL injection decreased mesenteric endothelium-dependent relaxation and increased TF expression in WT mice but not in TLR-2- or TLR-4-knockout mice. CONCLUSION: This translational study supports the notion that TLR-2 and TLR-4 play a role in mediating vascular abnormalities in patients with primary arterial APS. TLRs thus constitute a promising pharmacologic target for preventing cardiovascular complications in APS.

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 mediate autoimmunity against dying cells.

The Antiphospholipid Syndrome (APS) is characterized by thrombosis and pregnancy loss, clinical events mediated by pathogenic anti-phospholipid autoantibodies (aPL). ß2-glycoprotein I (ß2GPI) is the major autoantigens recognized by aPL. ß2GPI is a cationic protein that binds to negatively charged surfaces such as those of apoptotic cells. This feature may lead to two major events: i) immunization with ß2GPI fosters the Fc-receptor-mediated uptake by antigen presenting cells of apoptotic material decorated with ß2GPI and the activation of ß2GPI-specific T cells which in turn provide help to ß2GPI-specific B cells for the production of anti-ß2GPI; ii) apoptotic bodies decorated with ß2GPI can be opsonized by anti-ß2GPI and shifted towards a pro-inflammatory clearance by macrophages; epitope spread can occur with the generation of autoimmunity against nuclear autoantigens. In the presence of a predisposing genetic background and of a particular cytokine environment (type I interferons), the sequential emergence of autoantibodies can evolve into overt clinical disease. The spectrum of clinical phenotypes of the patients can be modulated by several factors affecting the pathogenicity of anti-ß2GPI (e.g. domain specificity). We conclude that dying cells may play a dual role in APS: (I) as immunogen for the induction of aPL (etiology) and (II) as targets of aPL for the chronification of inflammation and the development of autoimmune diseases (pathology).

Antiphospholipid antibodies prolong the activation of endothelial cells induced by necrotic trophoblastic debris: implications for the pathogenesis of preeclampsia.

The symptoms of preeclampsia are preceded by endothelial cell activation/dysfunction which is induced by a placental trigger(s) but maternal risk factor(s) also contribute to the pathogenesis of preeclampsia. In this work we have investigated the interactions of a maternal risk factor, antiphospholipid antibodies, and a placental trigger, necrotic trophoblastic debris, on the activation of endothelial cells. Trophoblastic debris, from placental explants, was induced to become necrotic by freeze-thawing then exposed to endothelial cells for 24 h. After washing away residual trophoblastic debris antiphospholipid antibodies or a control antibody were added to the cultures then replaced with fresh medium in the presence or absence of antibodies. Endothelial cell activation was quantified by examining cell-surface ICAM-1 expression and monocyte adhesion. Endothelial cells exposed to necrotic trophoblastic debris for 24 h became activated but the activation was lost 24 h after removal of the debris. Antiphospholipid antibodies alone did not active untreated endothelial cells, but did prolong the activation of endothelial cells which had been activated by pre-treatment with necrotic trophoblastic debris. When exposed to antiphospholipid antibodies the endothelial cells remained activated despite removal of the trophoblastic debris. In contrast, a control antibody did not prolong endothelial cell activation. Our data suggest that in women with antiphospholipid antibodies, activation of endothelial cells induced by necrotic trophoblastic debris could be maintained even if the endothelial cells were only intermittently exposed to necrotic debris. This might in part explain why antiphospholipid antibodies are such a strong maternal risk factor for preeclampsia.

Examining how antiphospholipid antibodies activate intracellular signaling pathways: a systematic review.

OBJECTIVES: Diverse experimental evidence exists implicating the activation of various different cell surface receptors and intracellular pathways by antiphospholipid antibodies (aPL). This evidence has been generated using a number of different cell types with varying numbers of aPL from different sources and disease subtypes. This experimental variability complicates the comparison of results from different studies. We therefore undertook a systematic review of the literature to provide a critical analysis of the strength of the evidence that specific receptors and signaling pathways are important in the pathogenesis of antiphospholipid syndrome. METHODS: We searched PubMed and EMBASE for studies in which the effects of aPL on cell surface receptors or intracellular signaling pathways were measured in vitro or in vivo. Each publication was systematically examined to note the following points: antibody type and source, outcome measures, use of receptor/signaling pathway inhibitors, and cell type and origin. RESULTS: We identified 10 original studies on toll-like receptors (TLR), 14 on protein kinases, and 13 on nuclear factor kappa B (NFκB). There was considerable heterogeneity between studies. Nevertheless, convincing evidence from multiple approaches implicates TLR4, p38 mitogen-activated protein kinase (MAPK), and NFκB in mediating pathogenic effects of antiphospholipid antibodies. CONCLUSIONS: TLR4, p38 MAPK and NFκB are involved in mediating pathogenic effects of aPL on different cell types and may be potential therapeutic targets in antiphospholipid syndrome.

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.

Antiphospholipid syndrome; its implication in cardiovascular diseases: a review.

Antiphospholipid syndrome (APLS) is a rare syndrome mainly characterized by several hyper-coagulable complications and therefore, implicated in the operated cardiac surgery patient. APLS comprises clinical features such as arterial or venous thromboses, valve disease, coronary artery disease, intracardiac thrombus formation, pulmonary hypertension and dilated cardiomyopathy. The most commonly affected valve is the mitral, followed by the aortic and tricuspid valve. For APLS diagnosis essential is the detection of so-called antiphospholipid antibodies (aPL) as anticardiolipin antibodies (aCL) or lupus anticoagulant (LA). Minor alterations in the anticoagulation, infection, and surgical stress may trigger widespread thrombosis. The incidence of thrombosis is highest during the following perioperative periods: preoperatively during the withdrawal of warfarin, postoperatively during the period of hypercoagulability despite warfarin or heparin therapy, or postoperatively before adequate anticoagulation achievement. Cardiac valvular pathology includes irregular thickening of the valve leaflets due to deposition of immune complexes that may lead to vegetations and valve dysfunction; a significant risk factor for stroke. Patients with APLS are at increased risk for thrombosis and adequate anticoagulation is of vital importance during cardiopulmonary bypass (CPB). A successful outcome requires multidisciplinary management in order to prevent thrombotic or bleeding complications and to manage perioperative anticoagulation. More work and reporting on anticoagulation management and adjuvant therapy in patients with APLS during extracorporeal circulation are necessary.

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.

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.

Anetodermic primary cutaneous B-cell lymphoma: a unique clinicopathological presentation of lymphoma possibly associated with antiphospholipid antibodies.

BACKGROUND: Primary cutaneous B-cell lymphoma manifested by anetoderma has been reported in 7 cases. In all, the secondary anetoderma developed in lesions of marginal-zone lymphoma or posttransplant lymphoproliferative disorder resembling marginal-zone lymphoma. The mechanisms underlying the destruction of elastic tissue in anetoderma are unclear. However, there is growing evidence linking primary anetoderma with a wide range of immunologic abnormalities, the most common being the presence of antiphospholipid antibodies. OBSERVATIONS: We analyzed data from 5 patients (3 male, 2 female) with clinical and histopathological features of anetodermic primary cutaneous B-cell lymphoma. Three had marginal-zone lymphoma and 2 had follicle-center cell lymphoma. In all, secondary anetoderma developed in self-regressing nodules/plaques of the lymphoma. Two patients also had lesions clinically and histopathologically compatible with primary anetoderma. Associated immunologic diseases were systemic lupus erythematosus-like disease and rheumatoid arthritis (1 patient each; not in patients with primary anetoderma). Antiphospholipid antibodies were found in 4 patients. CONCLUSIONS: Anetodermic primary cutaneous B-cell lymphoma is a rare and unique clinicopathological manifestation not only of marginal-zone lymphoma, as previously described, but also of follicle-center cell lymphoma. This type of secondary anetoderma, like primary anetoderma, might be associated with immunologic disorders, particularly antiphospholipid antibodies.