Nicked β2-glycoprotein I binds angiostatin 4.5 (plasminogen kringle 1-5) and attenuates its antiangiogenic property

Beyond antibodies: Beta-2 glycoprotein I as the unsung guardian of pregnancy

The physiological function of beta 2 glycoprotein I (β2GPI) itself is not well understood, other than that it is a primary antigen to anti-phospholipid antibodies in the autoimmune disease antiphospholipid syndrome. β2GPI is a soluble blood protein that is predominantly synthesized in hepatocytes. Why is the expression of β2GPI observed in the placenta despite its abundance in the circulating blood of healthy individuals? Does the placenta produce a specific-acting β2GPI?. β2GPI was recently shown to adopt two interconvertible biochemical confirmations based on the integrity of disulfide bonds: oxidized and reduced. The present study investigates the physiological function of β2GPI in trophoblast cells, with a focus on the reduced and oxidized forms of β2GPI under the hypothesis that placental β2GPI has a different activity from circulating β2GPI. Endogenous β2GPI secretion in trophoblast cells were predominantly in the reduced form, while those in HepG2 liver cells were mainly in the oxidized form. Progesterone increased reduced-β2GPI in both the trophoblast and liver cells. Oxidized-β2GPI significantly inhibited trophoblast cell migration and increased placental soluble fms-like tyrosine kinase-1 (sFlt-1). Furthermore, excess sFlt-1 significantly increased oxidized-β2GPI secretion in HepG2 cells. Circulating oxidized-β2GPI levels were significantly higher in women with pre-eclampsia than in those without pre-eclampsia. Therefore, oxidized-β2GPI may contribute to the pathogenesis of pre-eclampsia. Under oxidative stress, the excessive oxidation of β2GPI and/or excessive placental sFlt-1 may trigger a negative spiral between trophoblast and liver cells.

Mechanism of antiphospholipid antibody-mediated thrombosis in antiphospholipid syndrome

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by the occurrence of thrombotic or obstetrical events in patients with persistent antiphospholipid antibodies (aPL). Thrombotic events, the primary pathological hallmarks and clinical manifestations, are among the leading causes of mortality in APS. Our understanding of the mechanism underlying APS-related thrombosis has significantly advanced in recent years. The presence of aPL, particularly anti-β2-glycoprotein I (anti-β2GPI) antibodies, is a major driver of thrombosis. The proposed pathophysiological mechanisms of aPL-mediated pro-thrombotic events can be broadly categorized into three types: disruption of anticoagulant reactions and fibrinolysis, interference with coagulation cascade cells, and complement activation. A triggering 'second hit' is typically necessary to initiate thrombosis. The development of animal models of APS has further refined our understanding of the role of aPL in thrombosis. In this review, we focused on the role of β2GPI-dependent aPL in thrombosis of thrombotic APS.

Domain 5 of Beta 2 glycoprotein I: Friend or foe in health? Context matters

Beta 2 glycoprotein I (β2GPI) is the major autoantigen in the antiphospholipid syndrome, an autoimmune disorder characterized by thrombotic and obstetric complications. The autoantibodies that target beta 2 glycoprotein I are pathogenic and contribute to disease pathogenesis. The β2GPI molecule is composed of 5 domains that are numbered 1 through to 5. Autoantibodies bind mainly to domain 1 whereas the majority of the biological functions of the β2GPI molecule in diverse processes such as apoptotic cell clearance, complement regulation, lipopolysaccharide clearance and anticoagulation have been localised to domain 5 and its unique biochemistry, reviewed in this article. The role of purified domain 5 peptide as a potential therapeutic agent in APS and ischemia reperfusion injury is discussed.

Determining Thrombogenicity: Using a Modified Thrombin Generation Assay to Detect the Level of Thrombotic Event Risk in Lupus Anticoagulant-Positive Patients

The aim of this study was to determine the thrombogenicity of lupus anticoagulant (LA) antibodies using a modified thrombin generation assay (TGA) with the addition of activated protein C (APC) in a group of 85 patients with LA-positive samples. Of these, 58 patients had clinical manifestations of antiphospholipid syndrome (APS) according to the Sydney criteria classification, i.e., each patient had thrombosis or foetal loss, and 27 patients did not show any clinical manifestations of APS. A comparison of the two groups' TGA results revealed statistically significant differences (Fisher's test p = 0.0016). The group of patients exhibiting clinical manifestations of APS showed higher thrombogenicity in 56.9% of patients, while the group of patients not yet exhibiting clinical manifestations of APS showed higher thrombogenicity in 25.9% of patients. There were no significant differences in the specificity of the TGA test between the groups of patients exhibiting similar clinical manifestations. Receiver operating characteristic curve analysis showed a more significant relationship (p = 0.0060) for TGA than for LA titre (p = 0.3387). These data suggest that the determination of LA thrombogenicity with the TGA assay leads to an increased prediction of the manifestation of a thromboembolic event. Our findings appear to be particularly relevant for the prediction of thrombotic events in patients with laboratory-expressed APS and no clinical manifestations.

The Pathophysiology of The Antiphospholipid Syndrome: A Perspective From The Blood Coagulation System

The antiphospholipid syndrome (APS), a systemic autoimmune disease characterized by a hypercoagulability associated to vascular thrombosis and/or obstetric morbidity, is caused by the presence of antiphospholipid antibodies such as lupus anticoagulant, anti-β-2-glycoprotein 1, and/or anticardiolipin antibodies. In the obstetrical APS, antiphospholipid antibodies induce the production of proinflammatory cytokines and tissue factor by placental tissues and recruited neutrophils. Moreover, antiphospholipid antibodies activate the complement system which, in turn, induces a positive feedback leading to recruitment of neutrophils as well as activation of the placenta. Activation of these cells triggers myometrial contractions and cervical ripening provoking the induction of labor. In thrombotic and obstetrical APS, antiphospholipid antibodies activate endothelial cells, platelets, and neutrophils and they may alter the multimeric pattern and concentration of von Willebrand factor, increase the concentration of thrombospondin 1, reduce the inactivation of factor XI by antithrombin, increase the activation of factor XII, and reduce the activity of tissue plasminogen activator with the subsequent production of plasmin. All these effects result in less permeable clots, denser, thinner, and with more branched fibrin fibers which are more difficult to lysate. As a consequence, thrombosis, the defining clinical criterion of APS, complicates the clinical course of the patient.

Βeta-2-glycoprotein I exerts antithrombotic function through its domain V in mice

Little is known about the physiological role of beta-2-glycoprotein I (β2GPI) despite it being the major auto-antigen in the antiphospholipid syndrome. A systematic study of the role of β2GPI in thrombus formation in vivo has not been performed to date. Herein, we report that β2GPI deficient (-/-) mice have enhanced thrombus formation compared to wild type (WT) mice in a laser-induced arteriole and venule model of thrombosis. Furthermore, neutrophil accumulation and elastase activity was enhanced in thrombi of β2GPI -/- compared with WT mice. The antithrombotic function of β2GPI is dependent on its fifth domain (domain V); intravenous administration of the β2GPI domain deletion mutant lacking domain V (human recombinant domain I-IV) had no effect on platelet and fibrin thrombus size in β2GPI -/- or WT mice. On the contrary, intravenous administration of human recombinant domain V significantly inhibited platelet and fibrin thrombus size in both β2GPI -/- mice and WT mice. These findings reveal a major role for β2GPI as a natural anticoagulant and implicate domain V of β2GPI as a potential antithrombotic therapy.

In vivo evidence of angiogenesis inhibition by β2-glycoprotein I subfractions in the chorioallantoic membrane of chicken embryos

The vascular network expansion and functioning are important factors affecting normal intra-uterine fetal development. This study addressed the previously reported antiangiogenic potential of beta-2-glycoprotein I (β₂GPI) in vivo in the chick embryo model of angiogenesis. The effects of two naturally occurring β₂GPI forms on the development of the chorioallantoic membrane (CAM) vessels and the chicken embryo were investigated. β₂GPI monomers and dimers were obtained by fractioned purification and characterized using SDS-PAGE, immunoblot, and ELISA. The egg exposure was performed by injection of small volumes of 2.5 µg/mL solutions of the β₂GPI subfractions. Angiogenesis was evaluated through quantitative measurements of vascular architecture parameters in the captured CAM images, using computational analysis of texture contrasts and computer vision techniques. Quantitative information was assigned to the CAM vasculature modifications. In vivo, the β₂GPI dimer completely halted the formation of CAM vessels and led to embryo death after 48 h of exposure. The β₂GPI monomer allowed the embryo to develop up to the 10th day, despite early changes of CAM vessels. The impaired normal vessel growth proceeded as a self-limited effect. The β₂GPI monomer-exposed eggs showed reduced vascularization on the 6th day of incubation, but embryos were viable on the 10th day of incubation, with ingurgitated CAM vessels implying sequelae of the angiogenesis inhibition. Both subfractions impaired CAM vasculature development. The β₂GPI dimer proved to be largely more harmful than the β₂GPI monomer. β₂GPI modification by cleavage or dimerization may play a role in angiogenesis control in vivo.

Beta2 glycoprotein I-derived therapeutic peptides induce sFlt-1 secretion to reduce melanoma vascularity and growth

Melanoma, a form of skin cancer, is one of the most common cancers in young men and women. Tumors require angiogenesis to provide oxygen and nutrients for growth. Pro-angiogenic molecules such as VEGF and anti-angiogenic molecules such as sFlt-1 control angiogenesis. In addition, the serum protein, Beta2 Glycoprotein I (β2-GPI) induces or inhibits angiogenesis depending on conformation and concentration. β2-GPI binds to proteins and negatively charged phospholipids on hypoxic endothelial cells present in the tumor microenvironment. We hypothesized that peptides derived from the binding domain of β2-GPI would regulate angiogenesis and melanoma growth. In vitro analyses determined the peptides reduced endothelial cell migration and sFlt-1 secretion. In a syngeneic, immunocompetent mouse melanoma model, β2-GPI-derived peptides also reduced melanoma growth in a dose-dependent response with increased sFlt-1 and attenuated vascular markers compared to negative controls. Importantly, administration of peptide with sFlt-1 antibody resulted in tumor growth. These data demonstrate the therapeutic potential of novel β2-GPI-derived peptides to attenuate tumor growth and endothelial migration is sFlt-1 dependent.

Primary antiphospholipid syndrome, Addison disease, and adrenal incidentaloma

Primary adrenal failure comprises an insufficient production of mineralocorticoids and glucocorticoids in the adrenal cortex. A rare manifestation of antiphospholipid syndrome (APS) is adrenal failure. The majority of patients with adrenal involvement in APS develop an irreversible cortisol deficiency and atrophy of the adrenal glands. Adrenal incidentalomas are adrenal masses larger than 1 cm that are discovered in the course of diagnostic evaluation or treatment for another medical condition. Its prevalence is calculated in 1.5-9% of individuals. We describe an exceptional case of a 23-year-old male patient with APS with persistent high levels of antiphospholipid antibodies (aPL) from the time of diagnosis, who developed Addison's disease as a manifestation of APS with atrophy of the adrenal glands, in whom an adrenal incidentaloma was developed later and was corroborated as an aldosterone-producing adenoma. Currently, the patient is asymptomatic and without manifestations of tumor recurrence. The protumoral effect of elevated and persistent aPL is discussed.

Structural and functional characterization of β2 -glycoprotein I domain 1 in anti-melanoma cell migration

We previously found that circulating β₂‐glycoprotein I inhibits human endothelial cell migration, proliferation, and angiogenesis by diverse mechanisms. In the present study, we investigated the antitumor activities of β₂‐glycoprotein I using structure‐function analysis and mapped the critical region within the β₂‐glycoprotein I peptide sequence that mediates anticancer effects. We constructed recombinant cDNA and purified different β₂‐glycoprotein I polypeptide domains using a baculovirus expression system. We found that purified β₂‐glycoprotein I, as well as recombinant β₂‐glycoprotein I full‐length (D12345), polypeptide domains I‐IV (D1234), and polypeptide domain I (D1) significantly inhibited melanoma cell migration, proliferation and invasion. Western blot analyses were used to determine the dysregulated expression of proteins essential for intracellular signaling pathways in B16‐F10 treated with β₂‐glycoprotein I and variant recombinant polypeptides. Using a melanoma mouse model, we found that D1 polypeptide showed stronger potency in suppressing tumor growth. Structural analysis showed that fragments A and B within domain I would be the critical regions responsible for antitumor activity. Annexin A2 was identified as the counterpart molecule for β₂‐glycoprotein I by immunofluorescence and coimmunoprecipitation assays. Interaction between specific amino acids of β₂‐glycoprotein I D1 and annexin A2 was later evaluated by the molecular docking approach. Moreover, five amino acid residues were selected from fragments A and B for functional evaluation using site‐directed mutagenesis, and P11A, M42A, and I55P mutations were shown to disrupt the anti‐melanoma cell migration ability of β₂‐glycoprotein I. This is the first study to show the therapeutic potential of β₂‐glycoprotein I D1 in the treatment of melanoma progression.

β2-Glycoprotein I Inhibits Vascular Endothelial Growth Factor-Induced Angiogenesis by Suppressing the Phosphorylation of Extracellular Signal-Regulated Kinase 1/2, Akt, and Endothelial Nitric Oxide Synthase

Angiogenesis is the process of new blood vessel formation, and it plays a key role in various physiological and pathological conditions. The β₂-glycoprotein I (β₂-GPI) is a plasma glycoprotein with multiple biological functions, some of which remain to be elucidated. This study aimed to identify the contribution of ₂-GPI on the angiogenesis induced by vascular endothelial growth factor (VEGF), a pro-angiogenic factor that may regulate endothelial remodeling, and its underlying mechanism. Our results revealed that β₂-GPI dose-dependently decreased the VEGF-induced increase in endothelial cell proliferation, using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and the bromodeoxyuridine (BrdU) incorporation assays. Furthermore, incubation with both β₂-GPI and deglycosylated β₂-GPI inhibited the VEGF-induced tube formation. Our results suggest that the carbohydrate residues of β₂-GPI do not participate in the function of anti-angiogenesis. Using in vivo Matrigel plug and angioreactor assays, we show that β₂-GPI remarkably inhibited the VEGF-induced angiogenesis at a physiological concentration. Moreover, β₂-GPI inhibited the VEGF-induced phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), Akt, and endothelial nitric oxide synthase (eNOS). In summary, our in vitro and in vivo data reveal for the first time that β₂-GPI inhibits the VEGF-induced angiogenesis and highlights the potential for β₂-GPI in anti-angiogenic therapy.

Antiphospholipid syndrome: 30 years and our contribution

In 1983, Graham Hughes first described the concept of antiphospholipid syndrome (APS). In 1984, we described the enzyme-linked immunosorbent assay (ELISA) system which directly detected circulating aCL in patients with systemic lupus erythematosus (SLE) who revealed biological false positive serological test for syphilis. In 1990, three groups, including our group, independently reported the necessity of a cofactor for the binding of autoimmune anticardiolipin antibodies (aCL) to the solid phase phospholipids. β2-glycoprotein I (β2GPI) was identified as this cofactor. In 1994,the epitope for aCL was shown to develop when β2GPI is adsorbed on polyoxygenated polystyrene plates. In 2000, we described antiprothrombin antibodies bind to prothrombin exposed to immobilized phosphatidylserine and established a phosphatidylserine dependent monoclonal antiprothrombin antibody. In 2004, a novel role of nicked β2GPI was identified in the negative feedback pathway of extrinsic fibrinolysis. Nicked β2GPI was found to bind angiostatin 4.5 and to attenuate its antiangiogenic property. In 2004, we demonstrated that the p38 MAPK pathway mediates induction of the TF gene in stimulated with human monoclonal anti- β2GPI antibodies. Very recently, β2GPI was identified as a complement regulator. The cross-link between complement activation and prothrombotic status in patients with APS has been drawn much attention. Genetic factors are hypothesized to play a role in the susceptibility to APS based on several family studies in patients with antiphospholipid antibodies (aPL) and/or clinical manifestations of APS. The genetics of β2GPI has been extensively studied. 247 Val/Leu polymorphism can affect the conformational change of β2-GPI and the exposure of the epitopes for aCL. We found that 247 Val was correlated with anti-β2-GPI production in patients with primary APS, and 247 Val may be important for β2-GPI antigenicity. STAT4 SNP in Japanese patients with SLE and/or APS. T allele frequencies in SLE and APS were significantly elevated compared with that in healthy controls. When analyzed only in primary APS patients, T allele frequency was further higher. BANK1, BLK and SNP in 1q25.1 region were associated with not only SLE but also APS in Japanese population. These results suggest that APS and SLE, in part, share a common genetic background.

My contribution, my dream - a look at the future of APS

We found, in 1994, that the epitope for anticardiolipin antibodies (aCL) developed when β2-glycoprotein I (β2GPI) was adsorbed on polyoxygenated polystyrene plates. We also found, in 2009, that the cleaved form of β2GPI (nicked β2GPI) was bound to angiostatin 4.5 and attenuated its antiangiogenic property. We described in 2000 that antiprothrombin antibodies were bound to prothrombin exposed to immobilized phosphatidylserine (aPS/PT) and more than 95% of antiphospholipid syndrome patients who were positive for aPS/PT had lupus anticoagulant. We demonstrated that in the cells stimulated by human monoclonal anti-β2GPI antibodies, p38 mitogen-activated protein kinase phosphorylation was observed in the presence of β2GPI. Furthermore, we found that complement activation was essential for thrombus formation in patients with the antiphospholipid syndrome in vivo.

Obstetric antiphospholipid syndrome: a recent classification for an old defined disorder

Obstetric antiphospholipid syndrome (APS) is now being recognized as a distinct entity from vascular APS. Pregnancy morbidity includes >3 consecutive and spontaneous early miscarriages before 10weeks of gestation; at least one unexplained fetal death after the 10th week of gestation of a morphologically normal fetus; a premature birth before the 34th week of gestation of a normal neonate due to eclampsia or severe pre-eclampsia or placental insufficiency. It is not well understood how antiphospholipid antibodies (aPLs), beyond their diagnostic and prognostic role, contribute to pregnancy manifestations. Indeed aPL-mediated thrombotic events cannot explain the obstetric manifestations and additional pathogenic mechanisms, such as a placental aPL mediated complement activation and a direct effect of aPLs on placental development, have been reported. Still debated is the possible association between aPLs and infertility and the effect of maternal autoantibodies on non-vascular manifestations in the babies. Combination of low dose aspirin and unfractionated or low molecular weight heparin is the effective treatment in most of the cases. However, pregnancy complications, in spite of this therapy, can occur in up to 20% of the patients. Novel alternative therapies able to abrogate the aPL pathogenic action either by interfering with aPL binding at the placental level or by inhibiting the aPL-mediated detrimental effect are under active investigation.

Proteolytic processing of the extracellular scaffolding protein LEV-9 is required for clustering acetylcholine receptors

Correct positioning of neurotransmitter-gated receptors at postsynapses is essential for synaptic transmission. At Caenorhabditis elegans neuromuscular junctions, clustering of levamisole-sensitive acetylcholine receptors (L-AChRs) requires the muscle-secreted scaffolding protein LEV-9, a multidomain factor containing complement control protein (CCP) modules. Here we show that LEV-9 needs to be cleaved at its C terminus to exert its function. LEV-9 cleavage is not required for trafficking nor secretion but directly controls scaffolding activity. The cleavage site is evolutionarily conserved, and post-translational cleavage ensures the structural and functional decoupling between different isoforms encoded by the lev-9 gene. Data mining indicates that most human CCP-containing factors are likely cleaved C-terminally from CCP tandems, suggesting that not only domain architectures but also cleavage location can be conserved in distant architecturally related proteins.

β2-Glycoprotein I inhibits endothelial cell migration through the nuclear factor κB signalling pathway and endothelial nitric oxide synthase activation

β2-GPI (β2-glycoprotein I) is a plasma glycoprotein ascribed with an anti-angiogenic function; however, the biological role and molecular basis of its action in cell migration remain unknown. The aim of the present study was to assess the contribution of β2-GPI to HAEC (human aortic endothelial cell) migration and the details of its underlying mechanism. Using wound healing and Boyden chamber assays, we found that β2-GPI inhibited endothelial cell migration, which was restored by its neutralizing antibody. NF-κB (nuclear factor κB) inhibitors and lentiviral siRNA (small interfering RNA) silencing of NF-κB significantly attenuated the inhibitory effect of β2-GPI on cell migration. Moreover, β2-GPI was found to induce IκBα (inhibitor of NF-κB) phosphorylation and translocation of p65 and p50. We further demonstrated that mRNA and protein levels of eNOS [endothelial NO (nitric oxide) synthase] and NO production were all increased by β2-GPI and these effects were remarkably inhibited by NF-κB inhibitors and siRNAs of p65 and p50. Furthermore, β2-GPI-mediated inhibition of cell migration was reversed by eNOS inhibitors and eNOS siRNAs. The findings of the present study provide novel insight into the ability of β2-GPI to inhibit endothelial cell migration predominantly through the NF-κB/eNOS/NO signalling pathway, which indicates a potential direction for clinical therapy in vascular diseases.

Antiphospholipid syndrome: laboratory detection, mechanisms of action and treatment

The antiphospholipid syndrome (APS) identifies a condition at increased risk of vascular occlusion and/or pregnancy complications. Patients are defined as having APS if they have at least one clinical (vascular occlusion and/or pregnancy complications) and one laboratory criterion at the same time. The laboratory criteria that define APS are repeated positivity (confirmed 12 weeks apart) for lupus anticoagulants and/or antibodies targeted against cardiolipin or β(2) -glycoprotein I immobilized on solid surfaces. Over the years, APS has attracted the interest of many medical specialties. The aim of this review is to provide an update on (i) the laboratory criteria that determine the presence of APS, (ii) how the antibodies increase the risk of vascular occlusion and foetal loss and (iii) the treatment of the related clinical events.

β₂-glycoprotein I, the major target in antiphospholipid syndrome, is a special human complement regulator

The human plasma protein β(2)-glycoprotein I (β(2)-GPI) is the major target of autoantibodies associated with antiphospholipid syndrome. However, the biologic function of this abundant protein is still unclear. Here we identify β(2)-GPI as a complement regulator. β(2)-GPI circulates in the plasma in an inactive circular form. On surface binding, such as to apoptotic cells, β(2)-GPI changes conformation to an elongated form that acquires C3/C3b binding activities. β(2)-GPI apparently changes conformation of C3, so that the regulator factor H attaches and induces subsequent degradation by the protease factor I. β(2)-GPI also mediates further cleavage of C3/C3b compared with factor H alone. Our data provide important insights into innate immune regulation by plasma protein β(2)-GPI, which may be exploited in the prevention and therapy of autoimmune disease antiphospholipid syndrome.

In vivo modulation of angiogenesis by beta 2 glycoprotein I

Beta 2 glycoprotein I (β2GPI) is the major auto antigen in the antiphospholipid syndrome but also interacts with fibrinolytic and angiogenic proteins. The aim of this study was to examine the angiogenic potential of β2GPI in vivo in β2GPI deficient mice utilizing angiogenic assays. β2GPI deficient mice show increased microvessel formation in comparison to β2GPI replete controls when injected with growth factor free-matrigel implants. However, microvessel formation in matrigel plugs of β2GPI deficient mice was less than in β2GPI replete mice when basic fibroblast growth factor (bFGF) was included in the matrigel. Hemoglobin content was higher in vascular endothelial growth factor (VEGF) containing-matrigel plugs in the β2GPI deficient mouse demonstrating that the lack of β2GPI led to increased extravasation by VEGF. Melanoma B16F10 tumour growth was enhanced in β2GPI deficient mice. Melanoma microvessel density was increased in β2GPI deficient mice but the proliferation rate of tumour cells (determined by Ki67 immunohistochemistry) was unaffected by the presence or absence of β2GPI. Subcutaneous delivery of native human β2GPI by the ALZET osmotic pump did not affect melanoma tumour growth in β2GPI deficient mice. We conclude that the in vivo unopposed action of β2GPI is anti-angiogenic however this function is modified in the presence of a strong angiogenic stimulus into stabilization of vessel formation. Although the presence of β2GPI attenuates vessel sprouting in certain tumours, no survival benefit is conferred to tumour bearing animals. This does not preclude the potential benefit of modified or fragments of β2GPI in anti-angiogenesis research.

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.