Antiphospholipid and Antiprotein Syndromes in Non-thrombotic, Non-autoimmune Women with Unexplained Recurrent Primary Early Foetal Loss

Criteria and non-criteria antiphospholipid autoantibodies screening in patients with late pregnancy morbidity: A cross-sectional study

INTRODUCTION

Antiphospholipid syndrome (APS) is a cause of pregnancy morbidity. We aim to determine the frequency of criteria and non-criteria anti-phospholipid (aPL) autoantibodies in patients admitted for unexplained fetal death (UFD), pre-eclampsia (PE) and/or fetal growth restriction (FGR).

METHODS

All consecutive patients with UFD, PE and/or FGR followed in the department of Obstetrics, Bichat Hospital, University of Paris, Paris, between January 2019 and December 2021 were screened. Patients with available serum stored from the index pregnancy were included. Patients with previously known APS or twin pregnancy were excluded. Testing for aPL autoantibodies included anti-cardiolipin (aCL), anti-β2GPI (aβ2GPI), anti-phosphatidylethanolamine (aPE), anti-phosphatidylserine/prothrombin (aPS/PT) IgG/IgM and anti-annexin V IgG. When available, placenta specimens were analyzed by a pathologist blinded to the aPL status. All clinical characteristics, pregnancy features, and comorbidities were extracted from electronic medical records.

RESULTS

Overall 167 (32 (28.8-35.7) years) patients with UFD (n = 28; 16.8 %), PE (n = 60; 35.9 %) and/or FGR (n = 105; 62.9 %) were screened for aPL autoantibodies. Moderate titers of aPL autoantibodies were detected in 33 (n = 33/167, 19.8 %) patients. aPL autoantibodies were non-criteria aPE IgG/IgM in most cases (n = 28/33, 84.8 %). aPS/PT IgG/IgM were found in 11 (n = 11/33, 33.3 %) cases and aCL or aβ2GP1 IgG/IgM in 4 (n = 4/33, 12.1 %). Multivariable logistic regression showed that aPL autoantibodies were mostly associated with UFD (OR 4.37 [1.72-11.20], p = 0.002), PE ≤ 34th week of gestation (3.22 [0.86-11.90], p = 0.070) and chronic deciduitis (8.03 [0.89-67.2], p = 0.060) DISCUSSION: The frequency of aPL autoantibodies, mostly aPE, is high in patients with late pregnancy morbidity and may qualify obstetrical APS.

Biological markers of high risk of thrombotic recurrence in patients with antiphospholipid syndrome: A literature review

OBJECTIVES

This review aims to identify biological markers associated with the risk of recurrence of thrombotic and/or obstetric events in patients with antiphospholipid syndrome (APS).

METHODS

A comprehensive review of literature was conducted to evaluate established and potential novel biological markers associated with thrombosis in APS. To this end, a PubMed literature search was conducted for the last twenty years using the following keywords or their combinations: thrombotic risk, recurrence of thrombosis, risk stratification, severity, predictive value.

RESULTS

Previous studies showed that multiple aPL positivity correlates with an increased risk of thrombosis in APS. Moreover, the analysis of N-glycosylation of antiphospholipid antibodies (aPL) revealed that low levels of IgG sialylation, fucosylation or galactosylation increases the pro-inflammatory activity of aPL, predisposing to thrombosis. In addition, quantification of neutrophil extracellular traps (NETs) and antibodies directed against NETs (anti-NETs) in serum demonstrates promising prognostic utility in assessing APS severity. Oxidative stress plays a role in the pathogenicity of APS and paraoxonase 1 (PON1) activity emerges as a promising biomarker of thrombotic risk in APS. Furthermore, identification of novel antigenic targets involved in the pathophysiology of APS, such as lysobisphosphatidic acid (LBPA), had led to the discovery of unconventional aPL, antibodies directed against the LBPA (aLBPA), whose clinical value could make it possible to identify APS patients at high risk of thrombotic recurrence.

CONCLUSION

The immunological profile of aPL, N-glycosylation of aPL, quantification of NETs and anti-NETs, analysis of biomarkers of oxidative stress and the discovery of aLBPA offer potential prognostic tools for risk stratification in APS patients.

Profile and clinical relevance of non-criteria antiphospholipid antibodies in patients diagnosed with or highly suspected of APS

OBJECTIVE

This study investigates the positivity and relevance of non-criteria aPLs with clinical phenotypes in patients highly suspected of or diagnosed with APS.

METHODS

Outpatient cases were included from a prospectively maintained database, and patients were grouped into APS (n = 168), seronegative APS (SNAPS, n = 9), those meeting the diagnostic criteria for clinical events without laboratory results (only-event, n = 15), those that had aPL positivity without clinical manifestations (asymptomatic APA, n = 39), and healthy controls (n = 88). Criteria aPL results and APS-related clinical features were extracted. Sixteen non-criteria aPLs were tested and analysed.

RESULTS

LA, aCL and anti-β2 glycoprotein-I were positive in 84.5%, 61.3% and 74.4% of APS patients, and 61.5%, 59.0% and 74.4% of asymptomatic APA patients, respectively. In patients negative for criteria serological tests, 23 out of 24 were positive for at least one non-criteria aPL. Triple-positive patients also had significantly higher tests of some aPLs in comparison with other groups. Stroke was associated with anti-phosphatidyl-inositol (aPI) IgG and anti-phosphatidyl-glycerol (aPG) IgG. Late embryonic loss correlated with aPI IgM, and premature birth/eclampsia was associated with aPI IgG and aPG IgG. There were also positive associations between heart valve lesions and anti-phosphatidylserine-prothrombin (aPS/PT) IgM, APS nephropathy and anti-phosphatidyl-choline IgG or aPS/PT IgG, and livedo reticularis and anti-phosphatidyl-ethanolamine IgM.

CONCLUSION

The prevalence of non-criteria aPLs differed from diagnostic biomarkers in patients diagnosed with or suspected of APS. Detection of aPLs provided additive value in the evaluation of APS-related clinical manifestations.

"In House" assays for the quantification of Annexin V and its autoantibodies in patients with recurrent pregnancy loss and in vitro fertilisation failures

Several studies have been shown that Annexin V (ANXV) autoantibodies concentrations are associated with both early recurrent pregnancy losses (RPLs) or in vitro fertilization failure (IVFf). We investigated the association between ANXV autoantibodies and ANVX levels in RPL, IVFf and normal group women. The study was conducted on 22 female patients with RPLs, 66 patients with IVFf, and 16 normal samples from women who had given birth. ANXV autoantibodies were measured using an ELISA test developed by fixing a homemade recombinant ANXV protein and examined with labeled human antibodies, while ANXV concentrations were measured by a competitive ELISA using a homemade anti ANXV polyclonal antibody. The results showed a clear relationship between the high levels of ANXV autoantibodies and the recurrent abortion. On the other hand, ANXV measurement in those patients showed decreased concentrations compared to normal samples. Negative correlation between ANXV and its autoantibodies levels was reported in almost all patients' samples. Our data supports the possibility that ANXV autoantibodies are a risk factor for reproductive failures associated with both RPLs and/or IVFf and the significant role for ANXV in the maintenance of pregnancy.

Non-criteria antiphospholipid antibodies in antiphospholipid syndrome: Diagnostic value added

Objective

Non-criteria antiphospholipid antibodies (aPLs) increase the diagnostic value for antiphospholipid syndrome (APS) and contribute to better recognition of seronegative APS (SNAPS). However, the clinical utility and the diagnostic value of non-criteria aPLs are inconsistent. This study aimed to investigate the prevalence and clinical significance of 7 non-criteria aPLs in a large APS cohort.

Methods

Seven non-criteria aPLs, including anti-phosphatidylserine/prothrombin (aPS/PT) antibodies IgG/IgA/IgM, anti-phosphatidylethanolamine antibodies (aPE) IgG/IgA/IgM, anti-Annexin V antibodies (aAnnexinV) IgG/IgA/IgM, anti-phosphatidylserine antibodies (aPS) IgM, aPS IgG, antibodies directed against a mixture of phospholipids (APhL) IgG, and APhL IgM were tested among 175 patients with APS, 122 patients with other autoimmune diseases (as disease controls), and 50 healthy controls.

Results

In the present study, the highest prevalence of non-criteria aPLs was seen in aAnnexinV (58.86%). APhL IgG and aPS IgM showed the highest specificity (95.35%) and aPS/PT showed the highest Youden index (0.3991) for the diagnostic value of APS. The aAnnexinV also showed the highest prevalence in SNAPS (43.3%), followed by APhL IgM (21.7%), aPE (16.7%) and aPS/PT (16.7%). APhL IgG, aPS/PT, and aPS IgG showed positive association with thrombotic events in APS patients [APhL IgG: odds ratio (OR) = 2.26, 95% confidence interval (CI) 1.18-4.34, p = 0.013; aPS/PT: OR = 2.48, 95% CI: 1.32-4.69, p = 0.004; aPS IgG: OR = 1.90, 95% CI 1.01-3.60, p = 0.046; respectively). The inclusion of the non-criteria aPLs increased the accuracy of APS diagnosis from 65.7% to 87.4%.

Conclusion

Our data provide evidence that adding the non-criteria aPLs can improve the diagnostic accuracy in APS. APhL IgG, aPS/PT, and aPS IgG may be potential biomarkers to predict the risk of thrombosis in APS.

Seronegative autoimmune diseases: A challenging diagnosis

Autoimmune diseases (AID) are increasingly prevalent conditions which comprise more than 100 distinct clinical entities that are responsible for a great disease burden worldwide. The early recognition of these diseases is key for preventing their complications and for tailoring proper management. In most cases, autoantibodies, regardless of their potential pathogenetic role, can be detected in the serum of patients with AID, helping clinicians in making a definitive diagnosis and allowing screening strategies for early -and sometimes pre-clinical- diagnosis. Despite their undoubted crucial role, in a minority of cases, patients with AID may not show any autoantibody, a condition that is referred to as seronegative AID. Suboptimal accuracy of the available laboratory tests, antibody absorption, immunosuppressive therapy, immunodeficiencies, antigen exhaustion, and immunosenescence are the main possible determinants of seronegative AID. Indeed, in seronegative AID, the diagnosis is more challenging and must rely on clinical features and on other available tests, often including histopathological evaluation and radiological diagnostic tests. In this review, we critically dissect, in a narrative fashion, the possible causes of seronegativity, as well as the diagnostic and management implications, in several AID including autoimmune gastritis, celiac disease, autoimmune liver disease, rheumatoid arthritis, autoimmune encephalitis, myasthenia gravis, Sjögren's syndrome, antiphospholipid syndrome, and autoimmune thyroid diseases.

Is Oxidative Stress an Emerging Player in the Thrombosis of Patients with Anti-Phosphatidylethanolamine Autoantibodies?

The detection of anti-phosphatidylethanolamine autoantibodies (aPEs) has been proposed to improve the diagnosis and management of patients presenting clinical manifestations of antiphospholipid syndrome (APS), such as thrombosis, and who are persistently negative for conventional markers. After selecting the most specific ELISA for their detection, we evidenced the interest of aPEs in the exploration of thrombosis when APS conventional markers were negative through a 1-year retrospective study including 1131 consecutive patients routinely tested for aPEs. To validate this result, we assessed aPEs in a newly selected population of 77 patients with unexplained deep vein thrombosis (DVT). With a total prevalence of 19.5%, we confirmed the interest of aPE detection in patients with unexplained DVT who were devoid of other aPLs markers. Since endosomal compartment, a source of ROS production, has been recently identified as the cellular target of aPEs in vitro, we then investigated an association between aPE positivity and reactive oxygen species (ROS) production by measuring the production of thiobarbituric acid-reactive substances. We showed, for the first time, a significant association between aPE positivity and systemic ROS production in patients which led us to hypothesize a new mechanism of action of aPEs in thrombosis through a signaling related to oxidative stress.

Anti-phospholipid antibodies and reproductive failures

Anti-phospholipid syndrome (APS) recapitulates the link between autoimmunity and pregnancy failure: Acquired anti-phospholipid antibodies (aPL) play a pathogenic role in pregnancy complications. The diagnosis of obstetric APS can easily be pursued when women present with laboratory and clinical features fulfilling the international classification criteria. Standard therapeutic approach to obstetric APS consists in the association of anti-platelet agents and anticoagulants. Most patients achieve a live birth thanks to conventional treatment; however, approximately 20% fail to respond and are managed with additional therapeutic tools added on the top of conventional treatment. Surely, a refinement of risk stratification tools would allow early identification of high-risk pregnancies that warrant tailored treatment. In real life, obstetricians and rheumatologists face complex diagnostic scenarios including women with pregnancy morbidities other than those mentioned in classification criteria such as one or two early losses and premature birth after 34 weeks due to preeclampsia or placental insufficiency, women with low-titer aPL not fulfilling criteria laboratory requirements, women with positive non-criteria aPL, asymptomatic aPL carriers, and infertile women found to be aPL-positive. This review focuses on some of the several unanswered questions related to diagnostic, prognostic, and therapeutic aspects in obstetric APS.

[Seronegative antiphospholipid syndrome: Myth or reality?]

The antiphospholipid syndrome (APS) is a systemic autoimmune disease characterized by thrombosis and/or obstetrical manifestations and the persistent presence, at least 12 weeks apart, of antiphospholipid antibodies (aPL) such as lupus anticoagulant (LA) and/or anticardiolipin antibodies (ACL) and/or anti-β2 glycoprotein I antibodies (aβ2GPI). The finding of patients with clinical profile highly suggestive of APS but who are negative for conventional biological criteria has led to the concept of seronegative APS. In the last few years, new antigen targets and methodological approaches have been employed to more clearly identify this syndrome in patients with thrombosis or obstetrical complications without conventional aPL. Although seronegative APS is still controversial, there is increasing recognition of the existence of this subgroup. However, clinical relevance of non conventional aPL need to be confirmed by efforts toward standardizing new biological tools and longitudinal studies involving large cohort of patients.

Right ventricular thrombus in a case of neonatal lupus: case report

Neonatal thrombosis is considered a rare manifestation with unclear aetiology. We reported a neonatal lupus of a Sjogren’s syndrome mother with recurrent miscarriage secondary to antiphospholipid syndrome; seronegative to anticardiolipin antibodies, lupus anticoagulant and B2GP1. She was serologically positive to antiphosphatidylethanolamine and antiprothrombin antibodies, anti-SSA/Ro and anti-SSB/La. The neonate developed neonatal lupus complicated with right ventricular thrombus assumed to be induced by maternal transmission of antiphosphatidylethanolamine and antiprothrombin antibodies, treated successfully with tissue plasminogen activator and warfarin.

[Which place of antiphosphatidylethanolamine antibodies research in seronegative antiphospholipid syndrome suspicion?]

PURPOSE

Antiphospholipid syndrome (APS) is a clinico-biological syndrome, which associates vascular injury and persisting antiphospholipid antibodies (aPL). Patients with clinical symptoms of APS but without aPL are defined as "seronegative APS" (SNAPS). The aim of this study was to evaluate antiphosphatidylethanolamine antibody (aPE) investigation in patients with SNAPS suspicion.

METHODS

This retrospective study was conducted in patients with SNAPS suspicion. A homemade enzyme-linked immunosorbent assay (ELISA) was used to search for aPE. The results of this homemade method were compared with those from a global screening ELISA.

RESULTS

Two hundred twenty-eight patients with SNAPS suspicion were included. Among them, 58.3% had a thrombotic event. The homemade ELISA found positive persisting aPE in 23 patients (10%): 15 with a thrombotic event, 6 with obstetrical morbidity and 2 with a combined event. The global screening ELISA was positive in only 11 of these 23 patients (47.8%).

CONCLUSION

These results suggest the implication of aPE in SNAPS.

Diagnosis and management of the antiphospholipid syndrome

Antiphospholipid syndrome (APS) is characterized by thrombosis and/or pregnancy complications in the presence of persistent antiphospholipid antibodies (APLA). Laboratory diagnosis of APLA depends upon the detection of a lupus anticoagulant, which prolongs phospholipid-dependent anticoagulation tests, and/or anticardiolipin (aCL) and anti-β2-glycoprotein-1 (β2GPI) antibodies. APLA are primarily directed toward phospholipid binding proteins. Pathophysiologic mechanisms underlying thrombosis and pregnancy loss in APS include APLA induced cellular activation, inhibition of natural anticoagulant and fibrinolytic systems, and complement activation, among others. There is a high rate of recurrent thrombosis in APS, especially in triple positive patients (patients with lupus anticoagulant, aCL and anti-β2GPI antibodies), and indefinite anticoagulation with a vitamin K antagonist is the standard of care for thrombotic APS. There is currently insufficient evidence to recommend the routine use of direct oral anticoagulants (DOAC) in thrombotic APS. Aspirin with low molecular weight or unfractionated heparin may reduce the incidence of pregnancy loss in obstetric APS. Recent insights into the pathogenesis of APS have led to the identification of new potential therapeutic interventions, including anti-inflammatory and immunomodulatory therapies. Additional research is needed to better understand the effects of APLA on activation of signaling pathways in vascular cells, to identify more predictive biomarkers that define patients at greatest risk for a first or recurrent APLA-related clinical event, and to determine the safety and efficacy of DOACs and novel anti-inflammatory and immune-modulatory therapies for refractory APS.

The outcome of ELISA for antiphosphatidylethanolamine antibodies is dependent on the composition of phosphatidylethanolamine

OBJECTIVE

The presence of circulating autoantibodies against phosphatidylethanolamine (PE) has been shown to be positively associated with symptoms of antiphospholipid syndromes (APS). However, the current ELISA-based tests for antiphosphatidylethanolamine (aPE) antibodies remain inconsistent and controversial. The term PE refers to a collection of phospholipids that have phosphorylethanolamine head group as a common structural feature, but can vary in fatty acids with diverse physicochemical properties. The present study was to investigate, using synthetic positionally symmetrical PE species as a model system, the impact of PE structural variations on aPE ELISA.

METHODS

Single and combinations of synthetic PE species, including 16:0 (fatty acid length:degree of unsaturation), 18:0, 18:1, 20:4 and 22:6, were screened with ELISA using serum samples from aPE patients and compared with chicken egg PE. There were a total of 37 aPE patient serum samples, including 11 cofactor-independent IgM, 14 ABP-independent IgG and 12 ABP-dependent aPE serum samples (3 IgM, 8 IgG and 1 IgA). The ELISA conditions were investigated for different isotypes and cofactor dependence. Based on the initial screening, adjustments in phospholipid compositions were made for achieving optimal OD readings. Finally, we isolated total IgG from aPE sera to validate different antigenic preferences.

RESULTS

The antigenic preference was different among immunoglobulin isotypes and between cofactor-dependent versus cofactor-independent aPE antibodies. More specifically, 18:1 PE was a preferred antigen for cofactor-dependent aPE, whereas 20:4 PE was the preferred antigen for cofactor-independent IgG aPE. In contrast, cofactor-independent IgM aPE appeared to have a general preference for a more complex PE combination with longer fatty acids and a higher degree of unsaturation.

CONCLUSION

The present data indicated that the outcome of aPE ELISA was dependent on the composition and physicochemical properties of PE antigens. The discovery that aPE antibodies may have different antigenic preferences could shed light on the nature of their binding interactions.

Thrombotic risk assessment in antiphospholipid syndrome: the role of new antibody specificities and thrombin generation assay

Antiphospholipid syndrome (APS) is an autoimmune condition characterized by the presence of antiphospholipid antibodies (aPL) in subjects presenting with thrombosis and/or pregnancy loss. The currently used classification criteria were updated in the international consensus held in Sidney in 2005. Vascular events seem to result of local procoagulative alterations upon triggers influence (the so called “second-hit theory”), while placental thrombosis and complement activation seem to lead to pregnancy morbidity. The laboratory tests suggested by the current classification criteria include lupus anticoagulant, a functional coagulation assay, and anticardiolipin and anti-β2-glycoprotein-I antibodies, generally detected by solid phase enzyme-linked immunosorbent assay. The real challenge for treating physicians is understanding what is the actual weight of aPL in provoking clinical manifestations in each case. As thrombosis has a multi-factorial cause, each patient needs a risk-stratified approach. In this review we discuss the role of thrombotic risk assessment in primary and secondary prevention of venous and arterial thromboembolic disease in patients with APS, focusing on new antibody specificities, available risk scoring models and new coagulation assays.

Autoantibodies associated with reproductive failure

Autoimmune factors are involved in some of the cases of reproductive failure. These factors entail several autoantibodies, especially in patients having systemic lupus erythematosus (SLE) or the antiphospholipid syndrome (APS). These autoantibodies include mainly antibodies directed to phospholipid such as cardiolipin, phosphatidylserine, phosphatidylethanolamine or phospholipids binding glycoproteins such as b2glycoprotein-I, annexin V, prothrombin and protein-Z. There are also some other autoantibodies directed to laminin-I, thromboplastin, mitochondrial antibodies of the M5 type, corpus luteum, prolactin, poly (ADP-ribose), thyroglobulin and more, which were also found in SLE or APS patients with reproductive failure. Moreover, the presence of additional autoantibodies directed to actin, enolase, cubilin and others, needs further investigation to support a firm association to reproductive failure in women. Future studies are likely to help to determine and expand the number of autoantibodies screened in these patients, as well as by the use of proteomics technology, to determine peptides resembling the epitope specificities associated with the specific clinical manifestations.

The current standing of diagnosis of antiphospholipid syndrome associated with systemic lupus erythematosus

The antiphospholipid syndrome was first described in the early 1980s. The term was first coined to describe patients presenting with recurrent arterial and venous thrombosis or pregnancy complications. Antiphospholipid syndrome was first reported in systemic lupus erythematosus patients, but later on it became obvious that systemic lupus erythematosus is not a necessary condition for its occurrence. It has been shown that antibodies to phospholipids are the main causative agents of the disease, hence its name. The diagnosis of the disease has witnessed a remarkable evolution over the course of the past 25 years. With the observation that clinical parameters would not be enough to accurately diagnose the disease, antiphospholipid antibodies were recognized to play a central role in this regard. The main hindrance to an accurate diagnosis was the lack of standardization between different laboratory parameters that tested for the antiphospholipid antibodies. Lately, a combination of tests has been acknowledged to play a crucial role in diagnosis.

Laboratory diagnosis of antiphospholipid syndrome

Antiphospholipid syndrome is an intriguing clinical entity encountered by all physicians because of the wide range of clinical manifestations involving every organ system. Ordering a single test under the name "antiphospholipid antibody" does not rule out this entity. There are overlapping but distinct autoantibodies, and a positive result in one assay is conclusive despite a negative result in another. Laboratories continue to conduct several nonstandard tests as part of integrated kits and physicians should be familiar with them for proper interpretation of the results. Lupus anticoagulant testing is an integral part of every thrombophilia workup and should be performed regardless of the screening activated partial thromboplastin time or mixing study.

Loss of maternal annexin A5 increases the likelihood of placental platelet thrombosis and foetal loss

Antiphospholipid syndrome is associated with an increased risk of thrombosis and pregnancy loss. Annexin A5 (Anxa5) is a candidate autoantigen. It is not known, however, whether endogenous Anxa5 prevents foetal loss during normal pregnancy. We found significant reductions in litter size and foetal weight in Anxa5-null mice (Anxa5-KO). These changes occurred even when only the mother was Anxa5-KO. A small amount of placental fibrin deposition was observed in the decidual tissues, but did not noticeably differ between wild-type and Anxa5-KO mice. However, immunoreactivity for integrin beta 3/CD61, a platelet marker, was demonstrated within thrombi in the arterial canals only in Anxa5-KO mothers. Subcutaneous administration of the anticoagulant heparin to pregnant Anxa5-KO mice significantly reduced pregnancy loss, suggesting that maternal Anxa5 is crucial for maintaining intact placental circulation. Hence, the presence of maternal Anxa5 minimises the risk of thrombosis in the placental circulation and reduces the risk of foetal loss.

The contribution of antiphosphatidylethanolamine antibodies in the diagnosis of the antiphospholipid syndrome

The diagnosis of seronegative antiphospholipid syndrome (APS) has been proposed for patients with well-defined clinical APS but persistently negative for the routinely tested antiphospholipid antibodies (aPLs): antibodies to cardiolipin (aCL) and to β(2) glycoprotein I (aβ(2)GPI) and lupus anticoagulant (LA). Antibodies directed to phosphatidylethanolamine (aPE) have been described as the sole aPLs in some patients with clinical manifestations of APS. Here, we briefly summarize the available data on the clinical associations of aPEs and propose their investigation in patients with a clinical profile highly suggestive of seronegative APS.

'Non-criteria' aPL tests: report of a task force and preconference workshop at the 13th International Congress on Antiphospholipid Antibodies, Galveston, TX, USA, April 2010

Abstract: Current classification criteria for definite APS recommend the use of one or more of three positive standardized laboratory assays, including anticardiolipin antibodies (aCL), lupus anticoagulant (LA), and antibodies directed to β(2)glycoprotein I (anti-β(2)GPI) to detect antiphospholipid antibodies (aPL) in the presence of at least one of the two major clinical manifestations (i.e., thrombosis or pregnancy morbidity) of the syndrome. Several other autoantibodies shown to be directed to phospholipids and/or their complexes with phospholipids and/or to proteins of the coagulation cascade, as well as a mechanistic test for resistance to annexin A5 anticoagulant activity, have been proposed to be relevant to APS. A task force of worldwide scientists in the field discussed and analyzed critical questions related to 'non-criteria' aPL tests in an evidence-based manner during the 13th International Congress on Antiphospholipid Antibodies (APLA 2010, 13-16 April 2010, Galveston, Texas, USA). This report summarizes the findings, conclusions, and recommendations of this task force.

Anti-annexins autoantibodies: their role as biomarkers of autoimmune diseases

Annexins are a group of 12 highly conserved proteins which exert several regulatory functions on cell biology. There are involved in numerous cell processes including vesicle trafficking, calcium signaling, cell growth, division, and apoptosis. Autoantibodies directed toward annexin I, II, V and XI have been reported, but their role and their clinical correlates are controversial. Annexin I exerts an anti-inflammatory effect by suppressing the generation of inflammatory mediators and anti-annexin I antibodies were detected in patients affected with rheumatoid arthritis, systemic (SLE) and cutaneous lupus erythematosus. Annexin II and V have a high affinity for phospholipids playing a pivotal role in the regulation of coagulation cascade. Anti-annexin II and anti-annexin V antibodies were found in patients with arterial or venous thrombosis, especially in those with autoimmune rheumatic diseases (ARD) such as SLE, primary antiphospholipid syndrome (APS) or systemic sclerosis. Anti-annexin V antibodies were also found in patients with pregnancy loss with or without APS. Annexin XI is involved in several biological pathways, particularly apoptosis and cell proliferation. Anti-annexin XI antibodies have been found in patients with SLE, undifferentiated connective tissue disease, rheumatoid arthritis, Sjögren's syndrome and APS. The metanalysis of studies published up to now showed that the Odds Ratio for having an ARD in anti-annexin XI positive patients was 5.08 (95% CI 2.06-12.58).

Antiphospholipid antibody-mediated reproductive failure in antiphospholipid syndrome

The association of elevated titers of circulating antiphospholipid (anti-PL) Abs in antiphospholipid syndrome (APS) and reproductive failure is well established in the literature. The clinical features include recurrent abortions at various stages, including implantation, placentation in the first trimester, miscarriages in the second and third trimesters, intrauterine growth retardation, preeclampsia with placental insufficiency and growth restrictions, arterial and venous thrombosis, and possibly also infertility. APS-mediated recurrent pregnancy loss and other features of reproductive failure might result from diverse autoimmune factors, inflammation, involving different mechanisms, which encompass pathogenic anti-PL Abs. Herein, we discuss the association of anti-PL Abs with reproductive failure with special emphasis on antiphospholipid autoantibodies characterizing APS. This association is evident from either human studies or murine models.

Observational study of pregnant women with a previous spontaneous abortion before the 10th gestation week with and without antiphospholipid antibodies

BACKGROUND

A clinical subtype of purely obstetrical antiphospholipid antibody (aPL-Ab) syndrome (APS) requires three or more unexplained consecutive embryonic losses before the 10th week of gestation associated with persistently positive lupus anticoagulant (LAC), and/or anticardiolipin IgG or IgM, and/or anti-beta2-glycoprotein I (abeta2GpI) IgG or IgM. Although this diagnostic classification of APS appeared to be the most sensitive, the APS-associated serological criteria are still debated.

PATIENTS/METHODS

We prospectively observed the second pregnancy of 284 women with a previous embryonic loss, both with and without aPL-Ab.

RESULTS

aPL-Ab-positive women were more prone to pregnancy loss, embryonic loss, pre-eclampsia, placental abruption and intrauterine fetal growth restriction. Type IIa aPL-Ab positivity (LAC present alone) was associated with the highest risk of recurrent embryonic loss and intrauterine growth restriction. Type I aPL-Ab positivity (combinations of aPL-Ab type positivity) was associated with the strongest risks of late complications, pre-eclampsia and placental abruption. Finally, abeta2GpI-M positivities were not clinically relevant in these women.

CONCLUSION

Patients with a first unexplained pregnancy loss before the 10th week of gestation who are also positive for aPL-Abs have a higher risk of various complications in their second pregnancy. In this study, measurement of abeta2GpI-M had a questionable prognostic value.

Antiphosphatidylethanolamine antibodies and the antiphospholipid syndrome

The antiphospholipid antibodies included as laboratory criteria of the antiphospholipid syndrome (APS) are antibodies reacting with anionic phospholipids – anticardiolipin antibodies and lupus anticoagulant – and with β2-glycoprotein I. However, antibodies reacting with phosphatidylethanolamine (aPE), a zwitterionic phospholipid, have also been described to be associated with the main features of APS. The objectives of this review are to describe the characteristics of aPE and to bring attention to recent evidence that aPE are correlated with the main clinical features of APS, notably, in the absence of the laboratory criteria of this syndrome.

Autoantibodies and coagulation in reproductive medicine

Management of recurrent pregnancy loss (RPL) is considered to be difficult, in part because of cunfusion between autoantibodies and coagulation disorders. Autoantibodies and coagulation are related; two groups of multicenter studies concerning autoantibodies and coagulation reported that factor XII deficiency, hypofibrinolysis, anti-phosphatidylethanolamine (aPE), anti-beta2-glycoprotein I, anti-annexin A5, and lupus anticoagulant (LA) were found to be frequent risk factors in RPL women. Therefore, discrimination of autoantibodies and coagulation is important in understanding RPL well. We propose three types of pathways regarding reproduction, which are different and independent: (1) Negatively charged-phospholipid related antibodies (anti-phosphatidylserine; aPS, anti-cardiolipin; aCL, lupus anticoagulant; LA, anti-annexin A5; aANX), (2) factor XII-aPE-fibrinolysis: suppression of fibrinolysis, (3) protein C-protein S-factor V: loss of inactivation against activated factor V. Women with RPL and infertility showed similar findings in terms of the above clinical tests. Available data, however, is not enough to conclude whether these are pathogenic to infertile women.

Anti-beta(2)-glycoprotein-I and anti-phosphatidylserine antibodies in women with spontaneous pregnancy loss

OBJECTIVE

To evaluate the role of anti-beta(2)-glycoprotein-I (anti-beta(2)GPI-ab) and anti-phosphatidylserine (aPS-ab) antibodies as a risk factor in both recurrent miscarriage (RM) and unexplained fetal losses (UFL).

DESIGN

Retrospective, cohort study.

SETTING

Vall d'Hebron University Hospital, Barcelona, Spain.

PATIENT(S)

122 pregnant women divided in two groups: study group of 54 women with RM and/or UFL and control group of 68 pregnant without RM history.

INTERVENTION(S)

Analysis of lupus anticoagulant, anticardiolipin antibodies, and anti-beta(2)GP1 and aPS antibodies.

MAIN OUTCOME MEASURE(S)

Comparison of aPL antibody between groups.

RESULT(S)

The prevalence of aPL positive results was 8 out of 54 (14.8%) in the study group and 3 out of 68 (4.41%) in the controls. In the RM subgroup, the prevalence was 3 out of 25 (12%) versus 3 out of 68 (4.4%), and 7 out of 34 (20.6%) versus 3 out of 68 (4.4%) in UFL subgroup. As a whole, the prevalence of anti-beta(2)GP1-ab in the RM/UFL group showed a difference compared with controls but not aPS-ab. In the RM women, anti-beta(2)GP1-ab was positive in 3 out of 25 (12%) versus 1 out of 68 (1.5%) in controls and in 4 out of 34 versus 0 out of 68 cases in women with UFL. In the RM subgroup, aPS-ab was positive in 1 out of 25 (4%) versus 2 out of 68 (2.9%) in control group and in 3 out of 34 versus 2 out of 68 cases in women with UFL.

CONCLUSION(S)

Our results suggest that anti-beta(2)GP1-ab but not aPS-ab is related to RM/UFL and should be considered as a pregnancy-loss risk factor.

Antiphospholipid antibodies increase the risk of pregnancy-induced hypertension and adverse pregnancy outcomes

Antiphospholipid antibody (aPL) is associated with thromboembolism. There is scant evidence of a relationship between the aPL profile and serious adverse pregnancy outcome. The aim of this study was to assess whether aPL measurements during early pregnancy were useful in predicting a serious adverse pregnancy outcome. In this prospective study, we measured aPLs, including lupus anticoagulant (LA), IgG, IgM, IgA anticardiolipin antibody (aCL), IgG, IgM phosphatidylserine-dependent antiprothrombin antibody, and IgG kininogen-dependent antiphosphatidylethanolamine antibody (aPE) during the first trimester in a consecutive series of 1155 women. The 99 th percentile cut-off values in each aPL were determined using samples from 105 women who did not exhibit any pregnancy morbidity. We assessed the predictive risk of a serious adverse pregnancy outcome adjusted for confounding factors. We found that IgG aCL was associated with developing pregnancy-induced hypertension (PIH) (odds ratio 11.4, 95% CI 2.7-48); IgG aPE with PIH (8.3, 2.4-29), severe PIH (20.4, 4.5-91), and premature delivery (PD) (12.7, 3.1-50); and LA with PD (11.0, 2.8-44) and low birth weight (8.0, 2.1-31). The combinations of IgG aPE plus IgG aCL (17.5, 4.7-66.7) or IgG aPE plus LA (22.2, 5.4-909) measurements predicted severe PIH with 30.8% sensitivity and 99.2% specificity. We conclude that aPL measurements during early pregnancy may be useful in predicting adverse pregnancy outcome.

How we diagnose the antiphospholipid syndrome

The antiphospholipid syndrome (APS) is an acquired thrombophilia, characterized by the occurrence of venous and arterial events. This article examines the laboratory and key clinical aspects of APS. Particular focus is given to anti–beta 2-glycoprotein I (β2GPI) antibodies in view of their recent inclusion in the APS classification criteria. The clinical utility of using the β2GPI enzyme-linked immunosorbent assay, in conjunction with the established lupus anticoagulant assays and cardiolipin enzyme-linked immunosorbent assay, for diagnosing and risk stratifying patients suspected of having APS is discussed. The relative importance of the various assays in diagnosing obstetric APS (early and late gestation miscarriages) is explored. The implications of recent epidemiologic findings for possibly understanding the underlying pathophysiologic mechanisms of obstetric APS are highlighted. Insights into which patients with obstetric APS may be at most risk of thrombotic complications are presented.

Antibodies against annexin A5: detection pitfalls and clinical associations

Antiphospholipid syndrome (APS) has been defined as a clinical and laboratory entity. Laboratory criteria include the presence of anticardiolipin antibodies (aCL) and/or lupus anticoagulant (LA), collectively termed as antiphospholipid antibodies (aPL). However, there has been a rising interest in antibodies against so-called protein cofactors, particularly in beta(2)-glycoprotein I. In the early 90s, annexins were considered as target antigens for aPL, but at present the exact role of antibodies against annexins (aANX) remains puzzling. This review is concerned with annexin V or annexin A5 (ANXA5), a widespread member of the annexin family, and antibodies directed towards it. We have endeavoured to summarise essential information about the detection of anti-annexin V antibodies (aANXA5) and their clinical relevance. This review has also brought together some relevant published data concerning the structure, physiological role and therapeutic potential of ANXA5.

Protein C supports platelet binding and activation under flow: role of glycoprotein Ib and apolipoprotein E receptor 2

BACKGROUND

Activated protein C (APC) regulates thrombin generation and inhibits apoptosis. Endothelial protein C receptor (EPCR)-bound protein C is activated by thrombomodulin-bound thrombin. APC inactivates coagulation factors (F)Va/VIIIa and generates cytoprotective signaling downstream of protease-activated receptor-1 (PAR-1). Binding of APC to EPCR both modifies and induces PAR-1 signaling, but it is unknown if protein C interacts with cells in an alternative manner.

AIM

To determine whether platelets possess receptors for protein C that can generate intracellular signals.

RESULTS

Immobilized protein C or APC supported platelet adhesion, lamellipodia formation and elevation of intracellular Ca(2+). Adhesion of platelets to protein C or APC was inhibited by soluble recombinant apolipoprotein E receptor 2' (ApoER2') and by receptor-associated protein (RAP), an inhibitor of the low-density lipoprotein receptor family. Under shear, surface-bound protein C supported platelet adhesion and aggregation in a glycoprotein (GP)Ibalpha-dependent manner, and adhesion of platelets to immobilized protein C was abrogated by the addition of soluble forms of ApoER2' or RAP. APC bound to purified recombinant ApoER2' or GPIbalpha.

CONCLUSIONS

Our data demonstrate that activation of platelets with rapid intracellular signaling caused by binding to immobilized protein C or APC occurs via mechanisms that require ApoER2 and GPIbalpha and that APC directly binds to purified ectodomains of the receptors ApoER2 and GPIbalpha. These findings imply that protein C and APC may directly promote cell signaling in other cells by binding to ApoER2 and/or GPIbalpha.

Association of the protein Z intron F G79A gene polymorphism with recurrent pregnancy loss

OBJECTIVE

To investigate the association of the common protein Z (PZ) intron F G79A gene polymorphism with recurrent early pregnancy loss (RPL) and its gene-gene interaction with known thrombophilic risk factors for RPL.

DESIGN

Case control study.

SETTING

University clinic.

PATIENT(S)

We enrolled 49 women with a history of two consecutive or three to six nonconsecutive pregnancy losses between the 8th and 12th weeks of gestation and 48 age-matched parous controls without a history of pregnancy complications.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Allele frequencies of the PZ intron F G79A polymorphism and its gene-gene interaction with known risk factors for RPL.

RESULT(S)

Fourteen case subjects (28.6%) and 24 control subjects (50.0%) carried at least one A allele. This was associated with a significant reduction of the relative risk for recurrent pregnancy loss (odds ratio [OR] 0.4, 95% confidence interval [CI] 0.2-0.9; adjusted OR 0.3, 95% CI 0.1-0.8). Coexistence of any thrombophilic risk factor studied with the 79A allele resulted in a clear reduction of the primal relative risk for recurrent pregnancy loss.

CONCLUSION(S)

The isolated presence of the PZ intron F 79A allele as well as the combination with known thrombophilic risk factors was protective against RPL between the 8th and 12th weeks of gestation.

Antigenic profile, prevalence, and clinical significance of antiphospholipid antibodies in women referred for in vitro fertilization

The aim of this prospective study was to assess the prevalence of antiphospholipid antibodies (aPL) in women who had undergone in vitro fertilization (IVF) and the relationship between aPL and IVF outcome. A total of 101 infertile women with at least three unsuccessful IVF attempts were consecutively included in this study. Samples were collected in the follicular phase of a spontaneous ovarian cycle 2 months after the last ovulation induction treatment. Age-matched healthy fertile women (n = 160) were included as controls. All were evaluated for the presence of lupus anticoagulant (LA), antibodies (IgG, IgA, IgM) to cardiolipin (aCL), beta2-glycoprotein I (abeta2GPI), and phosphatidylethanolamine (aPE). Out of the 101 infertile women, 40 were persistently positive for aPL, showing a prevalence significantly higher than in controls (39.6% versus 5%, P < 0.0001). Among aPL, aPE were found with a significantly higher prevalence compared with LA, aCL, and aP2GPI (67.5% versus 0%, 15%, and 40%, respectively). Interestingly, aPE were found in 70% of the cases in the absence of the other aPL. The predominant isotype of aPL was IgA, in particular for abeta2GPI. Finally, no significant association was found between the presence of aPL and IVF outcome. This prospective study shows aPE as the most prevalent aPL in infertile women and IgA as more common than IgG and IgM. However, our results do not support an association between aPL and IVF outcome.