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Keywords:

  • Heparin treatment;
  • immunoglobulin G;
  • implantation;
  • inflammation;
  • obstetrical complications;
  • trophoblast

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Antiphospholipid antibody manifestation in women with RPL
  5. Immunopathology of APS
  6. Placental pathology and micro-angiopathy induced by aPL
  7. Role of aspirin and heparin in aPL-mediated immunopathology
  8. Anticoagulation treatment in women with aPL and RPL
  9. Should treatment be different based on aPL titer, isotype, single, or multiple epitopes?
  10. Non-anticoagulant treatment for women with aPL and RPL
  11. Conclusion
  12. References

Antiphospholipid antibodies (aPL) have been associated with recurrent pregnancy losses (RPL) and other obstetrical complications. The diagnostic criteria for the classical antiphospholipid antibody syndrome (APS) have been utilized for the detection of obstetrical APS in women with RPL. However, laboratory findings and immunopathology of obstetrical APS are significantly different from those of classical APS. In addition, many women with RPL who have positive aPL do not have symptoms consistent with the current APS criteria. The induction of a proinflammatory immune response from trophoblasts and complement activation by aPL rather than thromboembolic changes has been reported as a major immunopathological feature of obstetrical APS. Heparin treatment has been reported to be effective in prevention of early pregnancy loss with APS but not for the late pregnancy loss or complications. The complex effects of heparin may explain the limited efficacy of heparin treatment in RPL. New diagnostic criteria for obstetrical APS are needed urgently, and new therapeutic approaches should be explored further.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Antiphospholipid antibody manifestation in women with RPL
  5. Immunopathology of APS
  6. Placental pathology and micro-angiopathy induced by aPL
  7. Role of aspirin and heparin in aPL-mediated immunopathology
  8. Anticoagulation treatment in women with aPL and RPL
  9. Should treatment be different based on aPL titer, isotype, single, or multiple epitopes?
  10. Non-anticoagulant treatment for women with aPL and RPL
  11. Conclusion
  12. References

The antiphospholipid antibody syndrome (APS) is a systemic autoimmune disorder that is characterized by the presence of serum antiphospholipid antibodies (aPL) and associated clinical manifestations, such as arterial thrombosis, venous thrombosis and/or obstetrical complications, especially recurrent pregnancy losses (RPL).[1, 2] Approximately, 20% of women with RPL have autoimmune abnormalities[3] and aPL is one of the most common autoimmune etiologic factor for RPL.[1, 4, 5] Fifteen percentage of women with three or more RPL were reported to have persistently positive aPL,[6] and the fetal loss rate of these women was reported to be 50–90% if no specific treatment was given.[7, 8]

APS is defined as IgG and/or IgM anti-cardiolipin antibody (aCL) at a medium or high titer level (over the 99th percentile of a normal population), anti-β2 glycoprotein-I (β2GPI) antibody (over the 99th percentile), and lupus anticoagulant (LA) by the revised Sapporo criteria in 2006.[2] In addition to laboratory assays, clinical criteria are utilized for the diagnosis of APS. Recently, the revised APS criteria have reflected the association of APS with more obstetrical complications; however, controversies and uncertainty regarding diagnosis and treatment still persist.[2, 9]

Our understanding regarding the possible etiology and pathogenesis of this syndrome is limited. APS has been generally considered as a thrombophilic disease. Hence, the treatment has been primarily focused on anticoagulation using heparin and aspirin. However, recent findings from APS research using animal models have demonstrated that APS-induced obstetrical complications are initiated by inflammation rather than thrombosis.[10-12] These studies suggest that anti-inflammatory treatment should be considered for APS management. This review will discuss the characteristics of aPL expression in women with RPL, the potential mechanisms of tissue injury by aPL, how heparin therapy might inhibit the pathogenic mediators of disease, and the management of obstetrical APS.

Antiphospholipid antibody manifestation in women with RPL

  1. Top of page
  2. Abstract
  3. Introduction
  4. Antiphospholipid antibody manifestation in women with RPL
  5. Immunopathology of APS
  6. Placental pathology and micro-angiopathy induced by aPL
  7. Role of aspirin and heparin in aPL-mediated immunopathology
  8. Anticoagulation treatment in women with aPL and RPL
  9. Should treatment be different based on aPL titer, isotype, single, or multiple epitopes?
  10. Non-anticoagulant treatment for women with aPL and RPL
  11. Conclusion
  12. References

There are significant differences in the presence of the types of aPL in women with RPL and classical APS patients (Table 1). aPL are a heterogeneous group of autoantibodies, and their presence is associated with thrombosis and RPL.[1, 13] Regardless of the levels of positive aCL, antibodies directed against phospholipid-binding plasma proteins such as β2GPI, prothrombin (PT), and annexin V have also been reported to constitute a risk factor for thromboembolism in patients with systemic lupus erythematosus (SLE) and for miscarriage in women with RPL.[14] Patients with primary APS (pAPS) or SLE have significantly higher prevalence of these antibodies when compared to women with RPL. IgG and/or IgM aPL, anti-β2GPI, anti-PT, and IgG anti-annexin V antibodies were detected in 100, 80, 60, and 24% of the pAPS patients, respectively. In contrast, 66% of women with RPL were negative for all antibodies, and the prevalence of IgG and/or IgM aCL, anionic phospholipid antibody, anti-β2GPI, anti-PT, and IgG anti-annexin V antibodies was 6, 12, 6, 16, and 17%, respectively.[14] The titer and concentration of these antibodies were significantly higher in patients with pAPS and SLE as compared to women with RPL.[14] Thrombosis (54–67%) and thrombocytopenia (24–36%) are frequently present in women with SLE and APS; however, those are rarely found in women with RPL.[14-16]

Table 1. Comparison of Clinical and Laboratory Manifestations of Women with Systemic Lupus Erythematosus (SLE) or Recurrent Pregnancy Loss (RPL) among Antiphospholipid Antibody Syndrome (APS) Patients
 SLE with APSRPL
  1. aPL, antiphospholipid antibodies.

  2. a

    Reference[12].

  3. b

    Reference[14].

  4. c

    Reference[13].

aPL prevalenceHighaLowb
IgG CL53%13%
IgG PA37%9%
IgG PI32%11%
IgG PS38%15%
Anti-β2-GPI24%6%
aPL titerModerate to highLow to moderate
aPL concentration×3–10 higher than RPLLow
Thrombosis54–67% of aPL+ patientcPresent in placenta
Thrombocytopenia24–36% of aPL+ patientc

Women with RPL have a significantly higher prevalence of aPL directed against anionic phospholipids such as anti-phosphatidylserine or anti-phosphatidylethanolamine antibody as compared to normal controls,[16, 17] and pregnant women with RPL tend to have increased aPL prevalence as compared to normal pregnant women.[18] When we analyzed 320 women with RPL who visited Reproductive Medicine Clinic at Rosalind Franklin University of Medicine and Science, the majority of RPL women with positive aCL or anionic phospholipid antibodies had borderline to moderate positive titer antibodies and fewer patients had high titer aPL (Fig. 1). Although the presence of these other antibodies is not considered an indication of the classical APS, when these patients were treated with heparin and aspirin, 64% of women with antibodies to anionic phospholipids responded to the treatment and delivered a live-born infant.[17] Therefore, the current definition of aPL, which is limited to only aCL, LA and anti-β2GPI antibody, may not be broad enough to include women with RPL- and aPL-related pathology and should be re-evaluated.

image

Figure 1. Prevalence and titer distribution of antiphospholipid antibodies (aPL) in women with three or more recurrent pregnancy losses (n = 320). Green bar designates for high titer aPL, red for positive and blue for borderline titer. (IgG, immunoglobulin G; CL, cardiolipin; PE, phosphatidylethanolamine; PI, phosphatidyl inositol; PA, phosphatidic acid; PG, phosphatidyl glycerol; PS, phosphatidyl serine).

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Obstetrical APS is defined as appearing in women with obstetrical complications such as early RPL, fetal death, delivery <34 weeks due to severe pre-eclampsia or placental insufficiency, post-partum and long-term complications, and laboratory tests indicating the presence of APS.[19] In particular, the HELLP (hemolysis, elevated liver enzymes, low platelet count) syndrome was suggested to be included in microvascular and microangiopathic antiphospholipid-associated syndrome (MAPS).[20] Microvascular thrombotic and underestimated microangiopathic histopathological lesions in placenta of women with RPL and aPL have not been investigated well and need more study in the future.

Immunopathology of APS

  1. Top of page
  2. Abstract
  3. Introduction
  4. Antiphospholipid antibody manifestation in women with RPL
  5. Immunopathology of APS
  6. Placental pathology and micro-angiopathy induced by aPL
  7. Role of aspirin and heparin in aPL-mediated immunopathology
  8. Anticoagulation treatment in women with aPL and RPL
  9. Should treatment be different based on aPL titer, isotype, single, or multiple epitopes?
  10. Non-anticoagulant treatment for women with aPL and RPL
  11. Conclusion
  12. References

Several mechanisms have been proposed to explain the clinical manifestations associated with aPL. First, aPL have been shown to cause activation in cells such as platelets, endothelial cells, and monocytes.[21-23] In the context of the thrombotic tendency of the disease and the observation that thrombocytopenia is a frequent manifestation in APS,[15] we can surmise that platelet activation may be an integral part of aPL-induced immunopathology. aPL have been shown to increase the expression of glycoproteins on the membrane of the platelet, particularly GPIIb/IIIa (a fibrinogen receptor important in platelet aggregation) and GPIIIa.[13] There is also convincing evidence that aPL can activate endothelial cells and monocytes in vivo and in vitro, and this activation can be demonstrated by the increased expression of different cellular adhesion molecules and tissue factor (TF).[24-30] The thrombotic tendency induced by aCL was reported to be related to the titer, but not the titers of anionic phospholipid antibodies.[15] This finding was also supported by an animal study which revealed a dose-dependent effect of white blood cell sticking to endothelial cells induced by aCL present in the sera of the mice.[31]

Second, aPL induces thrombosis in the placenta and the vascular bed by interfering with the annexin A5 anticoagulant shield on phospholipid expressing surfaces.[32, 33] Clustering of annexin A5 on phospholipid surface results in displacement of clotting factor Va, precluding formation of procoagulant complexes. In murine studies, it has been demonstrated that passive transfer of a human monoclonal aPL, CIC15, isolated from a patient with pAPS and RPL, induced fetal resorption.[34] Histological analysis revealed signs of decidual arterial thrombosis, but there was no evidence of inflammatory cell infiltration in the decidual or fetal tissue. Pregnancy loss in this setting was reported to be related to the procoagulant activity of CIC15 but not due to disrupting annexin A5, because CIC15 was not able to disrupt the two-dimensional ordered arrays of annexin A5.[34] Therefore, the induction of thrombosis by aPL in the placenta and the vascular bed may involve various pathways.

Third, aPL have been shown to alter the maturation, movement, and invasiveness of trophoblast cells. Histopathological examination of products of conception in women with pAPS and pregnancy losses between 7 and 10 weeks gestation attributed these losses to abnormal endovascular trophoblast invasion in decidual vessels rather than excessive villous thrombosis.[35] This finding suggests that aPL cause defective placentation,[36] and that thrombophilia is not the sole explanation for complications of pregnancy in patients with APS. Indeed, anti-β2GPI antibodies have been reported to trigger an inflammatory response in trophoblast cells by increasing secretion of IL-8, MCP-1, GRO-α, and IL-1β. At high concentrations, these antibodies also induce caspase-mediated cell death.[37] Therefore, by acting in an autocrine and paracrine manner, anti-β2GPI antibodies induce inflammatory mediators to compromise trophoblast survival. In addition, aPL limit trophoblast cell migration by down-regulating trophoblast IL-6 secretion and STAT3 activity.[38] Hence, women with aPL and RPL have increased risk of developing obstetrical complications, associated with impaired deep placentation, such as pre-eclampsia.[38] aPL significantly reduce both VEGF and MMPs production, and at the nuclear level, NFκB DNA binding activity.[36] aPL recognize anionic phospholipids and β2GPI, which have adhered onto trophoblast cell structures, and significantly reduce β–hCG release and Matrigel invasiveness.[39] Therefore, aPL can impair trophoblast cell maturation, mobility, and invasiveness as well.

Activation of the complement cascade has attracted much attention in recent years in the context of obstetrical APS. Inflammation is now believed to be at the core of the pathogenesis of this syndrome, and tissue injury is speculated to be the result of complement-mediated inflammatory reaction in addition to thrombosis. Findings from animal models of aPL-induced pregnancy loss and increased injury-induced thrombosis argue that complement factor C3 and C5 are essential proximal mediators of tissue injury.[10, 39, 40] The complement system is capable of producing the thrombotic manifestations of APS through the direct activation of the coagulation cascade via membrane attack complex or indirectly via C5a-C5a receptor interaction leading to upregulation of TF, and thus activating the coagulation cascade.[11] In addition, complement activation leads to recruitment and stimulation of inflammatory cells and injury to the developing fetal-placental unit.

Placental pathology and micro-angiopathy induced by aPL

  1. Top of page
  2. Abstract
  3. Introduction
  4. Antiphospholipid antibody manifestation in women with RPL
  5. Immunopathology of APS
  6. Placental pathology and micro-angiopathy induced by aPL
  7. Role of aspirin and heparin in aPL-mediated immunopathology
  8. Anticoagulation treatment in women with aPL and RPL
  9. Should treatment be different based on aPL titer, isotype, single, or multiple epitopes?
  10. Non-anticoagulant treatment for women with aPL and RPL
  11. Conclusion
  12. References

When placenta from women with RPL are reviewed for histological properties, inadequate cytotrophoblast invasion depth (54%), disrupted syncytium formation (44%), thromboembolism in decidual vessels (33.9%), and elevated CD57+ NK cells infiltration (29.6%) are often present.[41] In women with aPL without any history of RPL, 36% of non-treated women who miscarry prior to 18 weeks gestation demonstrated chronic intervillositis and none had typical aPL-related pathology.[42] Sebire et al.,[35] reported that defective decidual endovascular trophoblast invasion, rather than excessive intervillous thrombosis, is the most frequent histological abnormality in aPL-associated early pregnancy loss as compared to aPL-negative pregnancy loss and normal controls. Therefore, thrombotic placental pathology is not specific for aPL-related pregnancy losses.

Lack of thrombotic changes at maternal fetal junction has been also demonstrated in an animal model treated with aPL. Mice that received IgG containing aPL showed strong TF staining throughout the decidua and on embryonic debris. TF staining was not associated with either fibrin staining or thrombi in decidua. The absence of fibrin deposition and thrombi suggests that TF-dependent activation of coagulation does not directly mediate aPL-induced pregnancy loss.[43] Inflammation, especially complement activation with generation of the anaphylotoxin C5a, has been reported to be an essential mediator of aPL-induced fetal injury. aPL induces TF expression, which leads to cell signaling activity.[43, 44] Recently, in a study of women with SLE and APS, it has been reported that classical complement activation plays a major role in aPL-mediated fetal injury and that placental C4d deposition is a reflection of classical complement activation in women with APS.[12]

Similar pathological findings have been reported in endometrium of women with aPL. Although aPL have been reported to activate endothelial cells in vivo, and create a prothrombotic state on endothelial cells,[31] thrombotic occlusion or intimal thickening affecting endometrial blood vessels is not often detected by hematoxylin–eosin staining of specimens from women with aPL. Instead, endometrial and subendometrial vascularity measured by Doppler ultrasound was significantly impaired in women with RPL and aPL during midluteal phase compared with normal fertile women.[45] Impaired endometrial vascularity may be the common effect induced by heterogeneous etiologic factors in women with RPL and aPL and unexplained RPL. Inflammation induced by aPL may lead to defective decidual endovascular trophoblast invasion during early implantation.

Role of aspirin and heparin in aPL-mediated immunopathology

  1. Top of page
  2. Abstract
  3. Introduction
  4. Antiphospholipid antibody manifestation in women with RPL
  5. Immunopathology of APS
  6. Placental pathology and micro-angiopathy induced by aPL
  7. Role of aspirin and heparin in aPL-mediated immunopathology
  8. Anticoagulation treatment in women with aPL and RPL
  9. Should treatment be different based on aPL titer, isotype, single, or multiple epitopes?
  10. Non-anticoagulant treatment for women with aPL and RPL
  11. Conclusion
  12. References

Recently, the use of combined unfractionated heparin (UFH) and low-dose aspirin regimen was reported to reduce the risk of spontaneous pregnancy loss by 54%, resulting in a live birth rate of 70–80%.[46, 47] However, histological studies of the APS patients or animal models often demonstrated the absence of thrombosis from miscarriage samples.[11, 35] Thus, it was postulated that inflammation may be the culprit in the aPL-induced pregnancy loss.

Aspirin is commonly prescribed to women at high risk of obstetric complications. The antithrombotic properties of aspirin may act to improve blood flow in the uterine vessels via inhibition of thromboxane A2, which is required for platelet aggregation.[48] Aspirin can also stimulate IL-3, an essential factor for implantation and placental growth; hence, more favorable embryonic implantation may be induced.[49] Aspirin and heparin combined therapy was reported to have a better success rate than aspirin monotherapy alone.[50] In a pilot double blinded randomized controlled trial, it was found that there was no significant difference in the aspirin and placebo treatment groups, reporting a live birth rate of 80 and 85%, respectively.[51] Therefore, the therapeutic effect of aspirin monotherapy for women with RPL and aPL seems to be limited.

Heparin has various pharmacological actions including direct interaction with trophoblasts (Table 2), and heparin treatment can result in a significant reduction in pregnancy complications in women with aPL. aPL has been shown to have a direct effect on trophoblasts unrelated to thrombosis and may induce direct cellular injury, apoptosis, inhibition of proliferation and syncytia formation, decreased human chorionic gonadotropin production, and defective invasiveness.[35, 36, 52, 53] All of these aPL-mediated effects might play a role in defective placentation. Heparin was reported to suppress some of these aPL-related pathology but not all.[37, 38] Therefore, heparin seems to have limited efficacy for aPL-related immunopathology during pregnancy.

Table 2. Action of Heparin on Immune Response
  1. aPL, antiphospholipid antibodies; LMWH, low molecular weight heparin.

1. Suppression of natural killer cell cytotoxicity[107]
2. Prevention of aPL-induced trophoblast inflammation and inhibition of aPL-triggered trophoblast cell death[57]
3. Prevention of leukocyte adhesion[108]
4. Blockage of interferon-γ signaling[109]
5. Inhibition of complement activation and promotion of growth factors[57]
6. Abrogates apoptosis of primary first trimester villous trophoblast in response to treatment with the pro-inflammatory cytokines, interferon (IFN)-gamma, and tumor necrosis factor (TNF)-alpha[58]
7. Attenuated the anti-β2-GPI antibody-mediated cell death, and the pro-inflammatory response, but only at high concentrations[37]
8. Unable to reverse the effects of anti-β2-GPI mAbs on trophoblast IL-6 production and migration by both unfractionated heparin and LMWH[38]
9. Upregulates soluble fms-like tyrosine kinase receptor-1 (sFlt-1) secretion independently of aPL by LMWH[67]

Heparin prevents the binding of β2GPI to negatively charged phospholipid which in turn prevents the deposition of anti-β2GPI antibodies in tissues.[54] Indeed, low molecular weight heparin (LMWH) has been shown to be able to reduce the binding of aPL to trophoblast cells and restore in vitro placental invasiveness and differentiation.[55, 56] Excessive activation of complement system at feto-maternal interface has been proposed as additional aPL-mediated mechanism of placental damage. Treatment with heparin prevented complement activation in vivo and protected mice from pregnancy complications induced by aPL.[57]

Heparin is also a modulator of inflammatory responses. Heparin abrogates apoptosis of primary first trimester villous trophoblast in response to treatment with the proinflammatory cytokines such as IFN-γ and TNF-α and sera from women with IVF failures and APS, and inhibited apoptosis induced by other agents including staurosporin, a broad-spectrum kinase inhibitor, and thrombin.[58, 59] It has been also reported that such low doses of heparin, lacking anticoagulant effects, inhibited an inflammatory response at the level of leukocyte adhesion and influx, and limited tissue injury.[60-62] Heparin possesses the ability to inhibit lipopolysaccharide-induced proinflammatory cytokines, such as TNF-α, IL-6, IL-8, and IL-1β involved in RPL of a murine model of APS.[63] For these anti-inflammatory actions, heparin has been suggested as a useful management tool for at risk patients, even in the absence of an identifiable thrombophilic disorder.[58]

Heparin has been reported to promote angiogenesis and support endovascular cross talk between the trophoblast and endothelial cells.[64] Interestingly, in the absence of aPL, LMWH induces potentially detrimental proinflammatory and anti-angiogenic profile in the trophoblast. In the presence of aPL, LMWH counters trophoblast inflammation, but induces an anti-angiogenic response.[65] LMWH enhanced placental growth factor (PlGF) secretion from trophoblast. However, LMWH up-regulated soluble fms-like tyrosine kinase receptor-1 (sFlt-1) secretion independently of aPL through shedding of the extracellular domain of Flt-1 receptor.[66] The complicated effects of heparin may explain why women with RPL, who were treated with heparin to prevent early pregnancy loss, have inconsistent outcome and still remain at increased risk of developing later obstetrical complications such as pre-eclampsia.[67]

In a recent clinical trial, heparin treatment was reported to be associated with increased circulating levels of sFlt-1 in the third trimester without increased growth restriction, and serum of heparin-treated cases inhibited both basal and vascular endothelial growth factor-induced capillary-like tube formation.[66] Therefore, upregulation of circulating sFlt-1 immunoreactivity in pregnancy seems not always to be associated with adverse outcomes and whether heparin has any effect to promote angiogenesis is in question.[66]

Anticoagulation treatment in women with aPL and RPL

  1. Top of page
  2. Abstract
  3. Introduction
  4. Antiphospholipid antibody manifestation in women with RPL
  5. Immunopathology of APS
  6. Placental pathology and micro-angiopathy induced by aPL
  7. Role of aspirin and heparin in aPL-mediated immunopathology
  8. Anticoagulation treatment in women with aPL and RPL
  9. Should treatment be different based on aPL titer, isotype, single, or multiple epitopes?
  10. Non-anticoagulant treatment for women with aPL and RPL
  11. Conclusion
  12. References

Numerous trials have been performed to assess the efficacy of prophylactic anticoagulation in women with RPL and aPL, and UFH has been the anticoagulant of choice during pregnancy.[68] However, reports of treatment outcome have been inconsistent, perhaps due to the heterogeneity of patient population.[46] For example, number of pregnancy losses; inclusion of chemical pregnancy; 1st versus 2nd trimester losses; primary versus secondary abortion; APS versus non-classical aPL; laboratory criteria (such as aCL alone, LA alone, both aCL and LA, or non-classical aPL); isotype and titers of aPL, etc. are different from one study to another and makes it difficult to compare these studies. Treatment has also been started at various time frames, such as pre-conception, post-conception, or with positive fetal heart beat.[46] Recent studies have assessed the efficacy of LMWH due to the advantage of easier administration and lower incidence of osteoporosis and heparin-induced thrombocytopenia compared to UFH.[69-71]

Evidence from small controlled trials have suggested that patients with RPL associated with aPL and without prior thromboembolism benefit from treatment with low-dose UFH at prophylactic doses of 5000–10,000 IU twice daily in addition to low-dose aspirin at 70–81 mg daily.[50, 72] Based on previous trials, Cochrane review concluded that the addition of UFH to aspirin may reduce pregnancy loss by 54% (RR 0.46), but LMWH and aspirin treatment did not significantly reduce pregnancy loss although the point estimates were in the direction of benefit suggesting LMWH probably has some benefit.[46] In a recent meta-analysis by Ziakas, heparin treatment (overall for UFH and LMWH treatment) was reported to be effective in early pregnancy loss in aPL patients (P < 0.0001), but not in late pregnancy loss (P = 0.9).[73] When LMWH and aspirin treatment was directly compared with UFH and aspirin treatment, there were no differences in pregnancy outcome.[74, 75] It has also been reported that no patients had spinal or epidural anesthesia and there was no complications overall.[75] LMWH and UFH have similar effects on aPL binding in vitro. No excessive bleeding in women with either vaginal or cesarean deliveries, no evidence of heparin-induced thrombocytopenia, or osteoporosis were reported.[76, 77] Therefore, both UFH with aspirin and LMWH with aspirin treatment can be utilized for women with aPL and RPL.

Should treatment be different based on aPL titer, isotype, single, or multiple epitopes?

  1. Top of page
  2. Abstract
  3. Introduction
  4. Antiphospholipid antibody manifestation in women with RPL
  5. Immunopathology of APS
  6. Placental pathology and micro-angiopathy induced by aPL
  7. Role of aspirin and heparin in aPL-mediated immunopathology
  8. Anticoagulation treatment in women with aPL and RPL
  9. Should treatment be different based on aPL titer, isotype, single, or multiple epitopes?
  10. Non-anticoagulant treatment for women with aPL and RPL
  11. Conclusion
  12. References

The Titers of aPL and Treatment Outcome

Current treatment of APS is mainly based on the clinical presentation and laboratory tests. Some studies showed that the high positive aPL titers were associated with adverse pregnancy outcome. In a retrospective cohort study by Simchen et al.,[78] women with APS were divided into two groups: high positive titer group with antibody titers greater than four times the upper limit of normal, and the rest as positive titer group. All women were treated with daily enoxaparin (LMWH) and aspirin. The results indicated that the risk for adverse fetal/neonatal outcome was 5.7 times higher (95%CI 1.9–17.7) in women with high positive aPL titers than in those with positive titers. It is suggested that pregnant women with APS and high positive aPL titers are a unique and extremely high-risk group for adverse fetal/neonatal outcome. Strict surveillance and possible additional therapy options should be explored for this patient population.

Although high titer aPL was reported to be related to thrombotic events, several studies reported that patients with thrombotic complications have low antibody levels.[79, 80] In case of early RPL and fetal death, the intermediate or low aPL levels commonly occur. Although these patients do not meet the revised Sapporo criteria, they are increasingly considered as having APS. Interestingly, in patients with obstetrical complications, rapid intervention with conventional treatments can much improve pregnancy outcomes. In recent years, it has been reported that ~75% of treated women with RPL and aPL have a successful delivery compared with <50% without treatment.[81]

Concerning the relationship between the low titer of aPL and treatment outcome, there are fewer reported studies. Recently, Mekinian et al.[82] analyzed the impact of low-dose aspirin (100 mg/day) with or without LMWH (40 mg enoxaparin once daily) in patients with low aPL titers (between the 90th and 99th percentile for either antibody). They compared the pregnancy and neonatal outcomes of the patients with aPL based on the Sapporo criteria with other patients with aPL-like obstetrical complications and with an aPL titer below the intermediate titers. The results showed that the patients with low aPL titers have similar outcomes in respect to obstetrical complications (RPL < 10th week of gestation, fetal death, and pre-eclampsia) as patients who meet Sapporo criteria for APS diagnosis. Therefore, conventional treatment can improve reproductive outcomes in patients with low aPL levels.

The Isotypes of aPL and Treatment Outcome

Antiphospholipid antibodies are closely associated with pregnancy complications; however, many women with aPL may have normal pregnancies. Which aPL profiles, if any, can predict pregnancy outcome in women with APS is still controversial. In a retrospective multi-center case-control analysis of 114 women with APS, simultaneous positive incidence of LA, aCL, and anti-β2GPI was the independent risk factors for pregnancy failure.[83] However, other researchers argued that presence of either anti-β2GPI or LA alone was considered as the best predictor.[84, 85]

Recently, a multicenter prospective observational study of risk factors for adverse pregnancy outcome in patients with aPL (LA, aCL, and/or anti-β2GPI) and/or SLE were undertaken by Lockshin et al.[85] The patients were treated with either LMWH or UFH. The treating physicians were blinded with regard to laboratory results. The findings showed that the aPL-positive patients with or without SLE, who had a LA at screening were at highest risk for adverse pregnancy outcome. However, LA-negative women, regardless of IgG or IgM aCL or anti-β2GPI status, were not at high risk. They suggested that LA is the only component of triple aPL positivity that has predictive power.

In contrast to the above mentioned study, the results from Umehara et al.[86] demonstrated that the aPL profile did not affect the pregnancy maintenance success rate when anticoagulant therapy was actively introduced. In this retrospective cohort study, 82 RPL patients with one or more positive aPL were under two regimens of anticoagulant therapy (a daily dose of 100 mg of aspirin alone from pre-conception until the 32nd week of pregnancy, or aspirin plus subcutaneous self-injection of 5000 units of UFH twice a day, starting from the time when the presence of the gestational sac was confirmed in the uterus until the 37th week of pregnancy). The results showed that the rates of pregnancy maintenance in the IgG group (92.7%) and the IgM group (90.0%) were not different. Regarding the number of positive aPL, the rate of pregnancy maintenance in 34 cases with single aPL was 91.2% and that in 47 cases with multiple aPL was 91.5%, also showing no significant difference. These observations have led to the conclusions that active anticoagulant therapy for aPL-positive RPL patients will result in good pregnancy outcome regardless of the isotype and the number of positive aPL.

Interestingly, there are a group to women with RPL who have IgM only aPL. We followed one case of RPL with high level of aPL, primarily of IgM isotype. IgM autoantibodies were specific to cardiolipin, phosphatidylglycerol, phosphatidylserine, and phosphatidylinositol. No IgM Abs to phosphatidylethanolamine were detected. Serum immunoglobulin levels (IgM, IgG, and IgA) were all within normal range. The monitoring of the patient's serological characteristics over a period of 2 years did not reveal the development of IgG aPL, however showed persistently high levels of the initially discovered IgM Abs. Tests for rheumatoid factor, anti-β2GPI Abs, or the screening for ANA were negative. Further serological investigation revealed a presence of anti-SSA and diagnosis of Sjogren's syndrome was made and patient was referred to a rheumatologist. An analysis of routine laboratory testing for aPL during a 5-month period (total 1067 samples) at the Clinical Immunology Laboratory, the Chicago Medical School at Rosalind Franklin University of Medicine and Science, revealed at least five patients had unique IgM only pattern in previous testing repeated in 6 weeks interval. Therefore, the prevalence of the IgM isotype of aPL only might be common in women who suffer from unexplained RPL. Therefore, these antibodies may identify additional patients with clinical features of autoimmune disease.

The Epitopes of aPL and Treatment Outcome

Currently, laboratory assays for LA, aCL, and anti-β2GPI remain the cornerstones of diagnosis. Although numerous studies have confirmed that these assays have been associated with the clinical manifestations of the syndrome, none of the assays has been uniformly specific for patients with APS. As a consequence, several new tests have been currently explored as potential alternatives to improve the sensitivity and specificity of diagnostic laboratory testing for aPL.[87]

Recent studies have investigated the clinical significance of autoantibodies specific for an epitope glycine40-arginine43 (G40-R43) in domain I of β2GPI in APS. A study from de Laat et al.[88] found that patients with antibodies against epitope G40-R43 had an 18.9-fold increased risk of thrombosis compared with patients with antibodies to other specificities. Another multicenter study from the same group reported that 55% of patients with various autoimmune diseases, all positive for anti-β2GPI, had anti-domain I antibodies.[89] These patients had an odds ratio of 3.5 for thrombosis compared to those without anti-domain 1 antibodies. Additionally, they found that anti-domain I antibodies were associated with pregnancy morbidity. Recently, Banzato et al.[90] reported that high-risk patients with APS and triple positivity (LA, IgG aCL, and IgG anti-β2GPI) had significantly higher titer of anti-domain I antibodies. Ongoing investigations are proposed focusing on answering the question whether the domain I antibodies are the only antibodies of importance for the detection of APS.[91] Moreover, awareness of an association between antibodies directed against distinct β2GPI-epitopes and specific clinical manifestations of APS can contribute to better understanding of disease patterns and complications and eventually lead to more specific ‘tailor made’ peptide therapy.[92]

Non-anticoagulant treatment for women with aPL and RPL

  1. Top of page
  2. Abstract
  3. Introduction
  4. Antiphospholipid antibody manifestation in women with RPL
  5. Immunopathology of APS
  6. Placental pathology and micro-angiopathy induced by aPL
  7. Role of aspirin and heparin in aPL-mediated immunopathology
  8. Anticoagulation treatment in women with aPL and RPL
  9. Should treatment be different based on aPL titer, isotype, single, or multiple epitopes?
  10. Non-anticoagulant treatment for women with aPL and RPL
  11. Conclusion
  12. References

Glucocorticoid and intravenous immunoglobulin G (IVIg) infusion treatment have been reported to be successful in women with aPL and RPL, although contradictory studies have been reported.[7, 93-97] Recent meta-analysis reported a significant increase in live births following IVIg use in women with secondary recurrent miscarriage although overall live birth rate was not improved.[98] We have reported that IVIg treatment significantly improved reproductive outcome in women with aPL who were refractory to anticoagulation treatment or elevated NK cell levels.[99, 100] In addition, IVIg treatment has been reported to be effective in RPL women with aPL with catastrophic APS.[101] Compared to glucocorticoid treatment, IVIg treatment resulted in significantly reduced second and third trimester obstetrical complications such as pre-eclampsia or pre-term delivery. Fewer cases of intrauterine growth restriction and neonatal intensive care admission were also reported when IVIg was added to heparin and aspirin treatment compared to heparin and aspirin treatment alone.[102] Comprehensive treatment using LDA, LMWH, corticosteroid, and IVIg was reported to improve reproductive outcome and reduced obstetric complications and to be a more effective treatment for APS than prednisone and aspirin treatment.[103] Further study is warranted in IVIg treatment for women with aPL and RPL.

Statins have been reported to inhibit endothelial activation mediated by anti-β2 GPI antibody. The inhibition of E-selectin expression exerted by fluvastatin was related to the impairment of NF-κB binding to DNA and attenuated expression of IL-6 mRNA in HUVEC exposed to anti-β2GPI antibodies to cytokines.[104] In addition, fluvastatin treatment in animal model with IgG from APS patients significantly reduced size of thrombi and number of adherent leukocytes.[105] Contradictory to this finding, pravastatin was reported not to prevent aPL-related changes in human first trimester trophoblast function.[106] Therefore, it seems to be premature to apply statin treatment in women with aPL and RPL.

Conclusion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Antiphospholipid antibody manifestation in women with RPL
  5. Immunopathology of APS
  6. Placental pathology and micro-angiopathy induced by aPL
  7. Role of aspirin and heparin in aPL-mediated immunopathology
  8. Anticoagulation treatment in women with aPL and RPL
  9. Should treatment be different based on aPL titer, isotype, single, or multiple epitopes?
  10. Non-anticoagulant treatment for women with aPL and RPL
  11. Conclusion
  12. References

Heterogeneity of population of women with RPL and aPL is the major concern in evaluation and treatment of obstetrical APS. Current diagnostic criteria for classical APS are insufficient for women with RPL and aPL. Clearly, aPL-induced RPL is not solely due to thrombotic episodes but rather inflammatory consequences either directly on trophoblast, or endometrial/decidual vasculature. Impaired endometrial/decidual vasculature and defective placental implantation are common pathology found in those women. Further studies to control the inflammatory immune response in women with RPL and aPL, using IVIg or glucocorticoids, are needed to further improve pregnancy outcome and possibly enhance even second and third trimester obstetrical complications. In addition, new diagnostic guidelines for obstetrical APS should be established. Finally, the controversies and differing results of current anticoagulation treatment highlight the urgent need for large prospective controlled trials to identify the specific predictors for high-risk pregnancy and for targeting/customized therapy to those most likely to benefit.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Antiphospholipid antibody manifestation in women with RPL
  5. Immunopathology of APS
  6. Placental pathology and micro-angiopathy induced by aPL
  7. Role of aspirin and heparin in aPL-mediated immunopathology
  8. Anticoagulation treatment in women with aPL and RPL
  9. Should treatment be different based on aPL titer, isotype, single, or multiple epitopes?
  10. Non-anticoagulant treatment for women with aPL and RPL
  11. Conclusion
  12. References
  • 1
    Harris EN, Chan JK, Asherson RA, Aber VR, Gharavi AE, Hughes GR: Thrombosis, recurrent fetal loss, and thrombocytopenia. Predictive value of the anticardiolipin antibody test. Arch Intern Med 1986; 146:21532156.
  • 2
    Miyakis S, Lockshin MD, Atsumi T, Branch DW, Brey RL, Cervera R, Derksen RH, DE Groot PG, Koike T, Meroni PL, Reber G, Shoenfeld Y, Tincani A, Vlachoyiannopoulos PG, Krilis SA: International consensus statement on an update of the classification criteria for definite antiphospholipid syndrome (APS). J Thromb Haemost 2006; 4:295306.
  • 3
    Ford HB, Schust DJ: Recurrent pregnancy loss: etiology, diagnosis, and therapy. Rev Obstet Gynecol 2009; 2:7683.
  • 4
    Lockshin MD, Druzin ML, Goei S, Qamar T, Magid MS, Jovanovic L, Ferenc M: Antibody to cardiolipin as a predictor of fetal distress or death in pregnant patients with systemic lupus erythematosus. N Engl J Med 1985; 313:152156.
  • 5
    Branch DW, Scott JR, Kochenour NK, Hershgold E: Obstetric complications associated with the lupus anticoagulant. N Engl J Med 1985; 313:13221326.
  • 6
    Rai RS, Regan L, Clifford K, Pickering W, Dave M, Mackie I, McNally T, Cohen H: Antiphospholipid antibodies and beta 2-glycoprotein-I in 500 women with recurrent miscarriage: results of a comprehensive screening approach. Hum Reprod 1995; 10:20012005.
  • 7
    Branch DW, Silver RM, Blackwell JL, Reading JC, Scott JR: Outcome of treated pregnancies in women with antiphospholipid syndrome: an update of the Utah experience. Obstet Gynecol 1992; 80:614620.
  • 8
    Rai RS, Clifford K, Cohen H, Regan L: High prospective fetal loss rate in untreated pregnancies of women with recurrent miscarriage and antiphospholipid antibodies. Hum Reprod 1995; 10:33013304.
  • 9
    Carvalho JF: Some concerns about the Sydney criteria for antiphospholipid syndrome. Lupus 2008; 17:770.
  • 10
    Girardi G, Berman J, Redecha P, Spruce L, Thurman JM, Kraus D, Hollmann TJ, Casali P, Caroll MC, Wetsel RA, Lambris JD, Holers VM, Salmon JE: Complement C5a receptors and neutrophils mediate fetal injury in the antiphospholipid syndrome. J Clin Invest 2003; 112:16441654.
  • 11
    Redecha P, Tilley R, Tencati M, Salmon JE, Kirchhofer D, Mackman N, Girardi G: Tissue factor: a link between C5a and neutrophil activation in antiphospholipid antibody induced fetal injury. Blood 2007; 110:24232431.
  • 12
    Cohen D, Buurma A, Goemaere NN, Girardi G, le Cessie S, Scherjon S, Bloemenkamp KW, de Heer E, Bruijn JA, Bajema IM: Classical complement activation as a footprint for murine and human antiphospholipid antibody-induced fetal loss. J Pathol 2011; 225:502511.
  • 13
    Khamashta MA, Harris EN, Gharavi AE, Derue G, Gil A, Vázquez JJ, Hughes GR: Immune mediated mechanism for thrombosis: antiphospholipid antibody binding to platelet membranes. Ann Rheum Dis 1988; 47:849854.
  • 14
    Bizzaro N, Tonutti E, Villalta D, Tampoia M, Tozzoli R: Prevalence and clinical correlation of anti-phospholipid-binding protein antibodies in anticardiolipin-negative patients with systemic lupus erythematosus and women with unexplained recurrent miscarriages. Arch Pathol Lab Med 2005; 129:6168.
  • 15
    Amoroso A, Mitterhofer AP, Del Porto F, Garzia P, Ferri GM, Galluzzo S, Vadacca M, Caccavo D, Afeltra A: Antibodies to anionic phospholipids and anti-beta2-GPI: association with thrombosis and thrombocytopenia in systemic lupus erythematosus. Hum Immunol 2003; 64:265273.
  • 16
    Kwak JY, Gilman-Sachs A, Beaman KD, Beer AE: Autoantibodies in women with primary recurrent spontaneous abortion of unknown etiology. J Reprod Immunol 1992; 22:1531.
  • 17
    Franklin RD, Kutteh WH: Antiphospholipid antibodies (APA) and recurrent pregnancy loss: treating a unique APA positive population. Hum Reprod 2002; 17:29812985.
  • 18
    Ruiz JE, Cubillos J, Mendoza JC, Espinel FJ, Kwak JY, Beer AE: Autoantibodies to phospholipids and nuclear antigens in non-pregnant and pregnant Colombian women with recurrent spontaneous abortions. J Reprod Immunol 1995; 28:4151.
  • 19
    Branch W: Report of the Obstetric APS Task Force: 13th International Congress on Antiphospholipid Antibodies, 13th April 2010. Lupus 2011; 20:158164.
  • 20
    Asherson RA, Cervera R: Microvascular and microangiopathic antiphospholipid-associated syndromes (“MAPS”): semantic or antisemantic? Autoimmun Rev 2008; 7:164167.
  • 21
    Palatinus AA, Ahuja KD, Adams MJ: Effects of antiphospholipid antibodies on in vitro platelet aggregation. Clin Appl Thromb Hemost 2012; 18:5965.
  • 22
    Oku K, Amengual O, Atsumi T: Pathophysiology of thrombosis and pregnancy morbidity in the antiphospholipid syndrome. Eur J Clin Invest 2012; 42:11261135.
  • 23
    Chen Q, Guo F, Hensby-Bennett S, Stone P, Chamley L: Antiphospholipid antibodies prolong the activation of endothelial cells induced by necrotic trophoblastic debris: implications for the pathogenesis of preeclampsia. Placenta 2012; 33:810815.
  • 24
    Gharavi AE, Pierangeli SS, Colden-Stanfield M, Liu XW, Espinola RG, Harris EN: GDKV-induced antiphospholipid antibodies enhance thrombosis and activate endothelial cells in vivo and in vitro. J Immunol 1999; 163:29222927.
  • 25
    Cugno M, Borghi MO, Lonati LM, Ghiadoni L, Gerosa M, Grossi C, DE Angelis V, Magnaghi G, Tincani A, Mari D, Riboldi P, Meroni PL: Patients with antiphospholipid syndrome display endothelial perturbation. J Autoimmun 2010; 34:105110.
  • 26
    Espinola RG, Liu X, Colden-Stanfield M, Hall J, Harris EN, Pierangeli SS: E-Selectin mediates pathogenic effects of antiphospholipid antibodies. J Thromb Haemost 2003; 1:843848.
  • 27
    Kaplanski G, Cacoub P, Farnarier C, Marin V, Grégoire R, Gatel A, Durand JM, Harlé JR, Bongrand P, Piette JC: Increased soluble vascular cell adhesion molecule 1 concentrations in patients with primary or systemic lupus erythematosus-related antiphospholipid syndrome: correlations with the severity of thrombosis. Arthritis Rheum 2000; 43:5564.
  • 28
    Pierangeli SS, Espinola RG, Liu X, Harris EN: Thrombogenic effects of antiphospholipid antibodies are mediated by intercellular cell adhesion molecule-1, vascular cell adhesion molecule-1, and P-selectin. Circ Res 2001; 88:245250.
  • 29
    Semeraro N, Colucci M: Tissue factor in health and disease. Thromb Haemost 1997; 78:759764.
  • 30
    Simantov R, LaSala JM, Lo SK, Gharavi AE, Sammaritano LR, Salmon JE, Silverstein RL: Activation of cultured vascular endothelial cells by antiphospholipid antibodies. J Clin Invest 1995; 96:22112219.
  • 31
    Pierangeli SS, Colden-Stanfield M, Liu X, Barker JH, Anderson GL, Harris EN: Antiphospholipid antibodies from antiphospholipid syndrome patients activate endothelial cells in vitro and in vivo. Circulation 1999; 99:19972002.
  • 32
    Atsumi T, Amengual O, Yasuda S, Matsuura E, Koike T: Research around beta 2-glycoprotein I: a major target for antiphospholipid antibodies. Autoimmunity 2005; 38:377381.
  • 33
    Rand JH, Wu XX: Antibody-mediated interference with annexins in the antiphospholipid syndrome. Thromb Res 2004; 114:383389.
  • 34
    Poindron V, Berat R, Knapp AM, Toti F, Zobairi F, Korganow AS, Chenard MP, Gounou C, Pasquali JL, Brisson A, Martin T: Evidence for heterogeneity of the obstetric antiphospholipid syndrome: thrombosis can be critical for antiphospholipid-induced pregnancy loss. J Thromb Haemost 2011; 9:19371947.
  • 35
    Sebire NJ, Fox H, Backos M, Rai R, Paterson C, Regan L: Defective endovascular trophoblast invasion in primary antiphospholipid antibody syndrome-associated early pregnancy failure. Hum Reprod 2002; 17:10671071.
  • 36
    Di Simone N, Di Nicuolo F, D'Ippolito S, Castellani R, Tersigni C, Caruso A, Meroni P, Marana R: Antiphospholipid antibodies affect human endometrial angiogenesis. Biol Reprod 2010; 83:212219.
  • 37
    Mulla MJ, Brosens JJ, Chamley LW, Giles I, Pericleous C, Rahman A, Joyce SK, Panda B, Paidas MJ, Abrahams VM: Antiphospholipid antibodies induce a pro-inflammatory response in first trimester trophoblast via the TLR4/MyD88 pathway. Am J Reprod Immunol 2009; 62:96111.
  • 38
    Mulla MJ, Myrtolli K, Brosens JJ, Chamley LW, Kwak-Kim JY, Paidas MJ, Abrahams VM: Antiphospholipid antibodies limit trophoblast migration by reducing IL-6 production and STAT3 activity. Am J Reprod Immunol 2010; 63:339348.
  • 39
    Di Simone N, Meroni PL, De Papa N, Raschi E, Caliandro D, De Carolis CS, Khamashta MA, Atsumi T, Hughes GR, Balestrieri G, Tincani A, Casali P, Caruso A: Antiphospholipid antibodies affect trophoblast gonadotropin secretion and invasiveness by binding directly and through adhered beta2-glycoprotein I. Arthritis Rheum 2000; 43:140150.
  • 40
    Pierangeli SS, Girardi G, Vega-Ostertag M, Liu X, Espinola RG, Salmon J: Requirement of activation of complement C3 and C5 for antiphospholipid antibody-mediated thrombophilia. Arthritis Rheum 2005; 52:21202124.
  • 41
    Kwak JY, Beer AE, Kim SH, Mantouvalos HP: Immunopathology of the implantation site utilizing monoclonal antibodies to natural killer cells in women with recurrent pregnancy losses. Am J Reprod Immunol 1999; 41:9198.
  • 42
    Salafia CM, Cowchock FS: Placental pathology and antiphospholipid antibodies: a descriptive study. Am J Perinatol 1997; 14:435441.
  • 43
    Girardi G, Mackman N: Tissue factor in antiphospholipid antibody-induced pregnancy loss: a pro-inflammatory molecule. Lupus 2008; 17:931936.
  • 44
    Girardi G, Yarilin D, Thurman JM, Holers VM, Salmon JE: Complement activation induces dysregulation of angiogenic factors and causes fetal rejection and growth restriction. J Exp Med 2006; 203:21652175.
  • 45
    Chen L, Quan S, Ou XH, Kong L: Decreased endometrial vascularity in patients with antiphospholipid antibodies-associated recurrent miscarriage during midluteal phase. Fertil Steril 2012; 98:14951502 e1491.
  • 46
    Empson M, Lassere M, Craig J, Scott J: Prevention of recurrent miscarriage for women with antiphospholipid antibody or lupus anticoagulant. Cochrane Database Syst Rev 2005; CD002859.
  • 47
    Lassere M, Empson M: Treatment of antiphospholipid syndrome in pregnancy–a systematic review of randomized therapeutic trials. Thromb Res 2004; 114:419426.
  • 48
    Nishino E, Takagi T, Mitsuda N, Masuhiro K, Iwata I, Iwata M, Tanizawa O: Effect of low-dose aspirin therapy on utero-placental blood flow and malondialdehyde (MDA) as an indicator of its therapeutic effect. Nihon Sanka Fujinka Gakkai Zasshi 1990; 42:16411647.
  • 49
    Fishman P, Falach-Vaknine E, Zigelman R, Bakimer R, Sredni B, Djaldetti M, Shoenfeld Y: Prevention of fetal loss in experimental antiphospholipid syndrome by in vivo administration of recombinant interleukin-3. J Clin Invest 1993; 91:18341837.
  • 50
    Rai R, Cohen H, Dave M, Regan L: Randomised controlled trial of aspirin and aspirin plus heparin in pregnant women with recurrent miscarriage associated with phospholipid antibodies (or antiphospholipid antibodies). BMJ 1997; 314:253257.
  • 51
    Pattison NS, Chamley LW, Birdsall M, Zanderigo AM, Liddell HS, McDougall J: Does aspirin have a role in improving pregnancy outcome for women with the antiphospholipid syndrome? A randomized controlled trial. Am J Obstet Gynecol 2000; 183:10081012.
  • 52
    Lyden TW, Vogt E, Ng AK, Johnson PM, Rote NS: Monoclonal antiphospholipid antibody reactivity against human placental trophoblast. J Reprod Immunol 1992; 22:114.
  • 53
    Sthoeger ZM, Mozes E, Tartakovsky B: Anti-cardiolipin antibodies induce pregnancy failure by impairing embryonic implantation. Proc Natl Acad Sci USA 1993; 90:64646467.
  • 54
    Guerin J, Sheng Y, Reddel S, Iverson GM, Chapman MG, Krilis SA: Heparin inhibits the binding of beta 2-glycoprotein I to phospholipids and promotes the plasmin-mediated inactivation of this blood protein. Elucidation of the consequences of the two biological events in patients with the anti-phospholipid syndrome. J Biol Chem 2002; 277:26442649.
  • 55
    Di Simone N, Caliandro D, Castellani R, Ferrazzani S, De Carolis S, Caruso A: Low-molecular weight heparin restores in-vitro trophoblast invasiveness and differentiation in presence of immunoglobulin G fractions obtained from patients with antiphospholipid syndrome. Hum Reprod 1999; 14:489495.
  • 56
    Di Simone N, Ferrazzani S, Castellani R, De Carolis S, Mancuso S, Caruso A: Heparin and low-dose aspirin restore placental human chorionic gonadotrophin secretion abolished by antiphospholipid antibody-containing sera. Hum Reprod 1997; 12:20612065.
  • 57
    Girardi G, Redecha P, Salmon JE: Heparin prevents antiphospholipid antibody-induced fetal loss by inhibiting complement activation. Nat Med 2004; 10:12221226.
  • 58
    Hills FA, Abrahams VM, Gonzalez-Timon B, Francis J, Cloke B, Hinkson L, Rai R, Mor G, Regan L, Sullivan M, Lam EW, Brosens JJ: Heparin prevents programmed cell death in human trophoblast. Mol Hum Reprod 2006; 12:237243.
  • 59
    Bose P, Black S, Kadyrov M, Weissenborn U, Neulen J, Regan L, Huppertz B: Heparin and aspirin attenuate placental apoptosis in vitro: implications for early pregnancy failure. Am J Obstet Gynecol 2005; 192:2330.
  • 60
    Friedrichs GS, Kilgore KS, Manley PJ, Gralinski MR, Lucchesi BR: Effects of heparin and N-acetyl heparin on ischemia/reperfusion-induced alterations in myocardial function in the rabbit isolated heart. Circ Res 1994; 75:701710.
  • 61
    Rops AL, van der Vlag J, Lensen JF, Wijnhoven TJ, van den Heuvel LP, van Kuppevelt TH, Berden JH: Heparan sulfate proteoglycans in glomerular inflammation. Kidney Int 2004; 65:768785.
  • 62
    Wang L, Brown JR, Varki A, Esko JD: Heparin's anti-inflammatory effects require glucosamine 6-O-sulfation and are mediated by blockade of L- and P-selectins. J Clin Invest 2002; 110:127136.
  • 63
    Hochart H, Jenkins PV, Smith OP, White B: Low-molecular weight and unfractionated heparins induce a downregulation of inflammation: decreased levels of proinflammatory cytokines and nuclear factor-kappaB in LPS-stimulated human monocytes. Br J Haematol 2006; 133:6267.
  • 64
    Yavuz C, Karahan O: Do dose-related mechanisms exist for the angiogenic behaviours of heparin derivatives? Am J Reprod Immunol 2012; 68:185186.
  • 65
    Han CS, Mulla MJ, Brosens JJ, Chamley LW, Paidas MJ, Lockwood CJ, Abrahams VM: Aspirin and heparin effect on basal and antiphospholipid antibody modulation of trophoblast function. Obstet Gynecol 2011; 118:10211028.
  • 66
    Rosenberg VA, Buhimschi IA, Lockwood CJ, Paidas MJ, Dulay AT, Ramma W, Abdel-Razeq SS, Zhao G, Ahmad S, Ahmed A, Buhimschi CS: Heparin elevates circulating soluble fms-like tyrosine kinase-1 immunoreactivity in pregnant women receiving anticoagulation therapy. Circulation 2011; 124:25432553.
  • 67
    Carroll TY, Mulla MJ, Han CS, Brosens JJ, Chamley LW, Giles I, Pericleous C, Rahman A, Sfakianaki AK, Paidas MJ, Abrahams VM: Modulation of trophoblast angiogenic factor secretion by antiphospholipid antibodies is not reversed by heparin. Am J Reprod Immunol 2011; 66:286296.
  • 68
    Sanson BJ, Lensing AW, Prins MH, Ginsberg JS, Barkagan ZS, Lavenne-Pardonge E, Brenner B, Dulitzky M, Nielsen JD, Boda Z, Turi S, Mac Gillavry MR, Hamulyak K, Theunissen IM, Hunt BJ, Buller HR: Safety of low-molecular-weight heparin in pregnancy: a systematic review. Thromb Haemost 1999; 81:668672.
  • 69
    Fejgin MD, Lourwood DL: Low molecular weight heparins and their use in obstetrics and gynecology. Obstet Gynecol Surv 1994; 49:424431.
  • 70
    Pettila V, Leinonen P, Markkola A, Hiilesmaa V, Kaaja R: Postpartum bone mineral density in women treated for thromboprophylaxis with unfractionated heparin or LMW heparin. Thromb Haemost 2002; 87:182186.
  • 71
    Triolo G, Ferrante A, Ciccia F, Accardo-Palumbo A, Perino A, Castelli A, Giarratano A, Licata G: Randomized study of subcutaneous low molecular weight heparin plus aspirin versus intravenous immunoglobulin in the treatment of recurrent fetal loss associated with antiphospholipid antibodies. Arthritis Rheum 2003; 48:728731.
  • 72
    Kutteh WH: Antiphospholipid antibody-associated recurrent pregnancy loss: treatment with heparin and low-dose aspirin is superior to low-dose aspirin alone. Am J Obstet Gynecol 1996; 174:15841589.
  • 73
    Ziakas PD, Pavlou M, Voulgarelis M: Heparin treatment in antiphospholipid syndrome with recurrent pregnancy loss: a systematic review and meta-analysis. Obstet Gynecol 2010; 115:12561262.
  • 74
    Noble LS, Kutteh WH, Lashey N, Franklin RD, Herrada J: Antiphospholipid antibodies associated with recurrent pregnancy loss: prospective, multicenter, controlled pilot study comparing treatment with low-molecular-weight heparin versus unfractionated heparin. Fertil Steril 2005; 83:684690.
  • 75
    Stephenson MD, Ballem PJ, Tsang P, Purkiss S, Ensworth S, Houlihan E, Ensom MH: Treatment of antiphospholipid antibody syndrome (APS) in pregnancy: a randomized pilot trial comparing low molecular weight heparin to unfractionated heparin. J Obstet Gynaecol Can 2004; 26:729734.
  • 76
    Dulitzki M, Pauzner R, Langevitz P, Pras M, Many A, Schiff E: Low-molecular-weight heparin during pregnancy and delivery: preliminary experience with 41 pregnancies. Obstet Gynecol 1996; 87:380383.
  • 77
    Nelson-Piercy C, Letsky EA, de Swiet M: Low-molecular-weight heparin for obstetric thromboprophylaxis: experience of sixty-nine pregnancies in sixty-one women at high risk. Am J Obstet Gynecol 1997; 176:10621068.
  • 78
    Simchen MJ, Dulitzki M, Rofe G, Shani H, Langevitz P, Schiff E, Pauzner R: High positive antibody titers and adverse pregnancy outcome in women with antiphospholipid syndrome. Acta Obstet Gynecol Scand 2011; 90:14281433.
  • 79
    Dunn AS, Kaboli P, Halfdanarson T, Chan H, Hubert R, Rosen S, White RH: Do patients followed in anticoagulation clinics for antiphospholipid syndrome meet criteria for the disorder? Thromb Haemost 2005; 94:548554.
  • 80
    Tuthill JI, Khamashta MA: Management of antiphospholipid syndrome. J Autoimmun 2009; 33:9298.
  • 81
    Ernest JM, Marshburn PB, Kutteh WH: Obstetric antiphospholipid syndrome: an update on pathophysiology and management. Semin Reprod Med 2011; 29:522539.
  • 82
    Mekinian A, Loire-Berson P, Nicaise-Roland P, Lachassinne E, Stirnemann J, Boffa MC, Chollet-Martin S, Carbillon L, Fain O: Outcomes and treatment of obstetrical antiphospholipid syndrome in women with low antiphospholipid antibody levels. J Reprod Immunol 2012; 94:222226.
  • 83
    Ruffatti A, Tonello M, Visentin MS, Bontadi A, Hoxha A, De Carolis S, Botta A, Salvi S, Nuzzo M, Rovere-Querini P, Canti V, Mosca M, Mitic G, Bertero MT, Pengo V, Boffa MC, Tincani A: Risk factors for pregnancy failure in patients with anti-phospholipid syndrome treated with conventional therapies: a multicentre, case-control study. Rheumatology (Oxford) 2011; 50:16841689.
  • 84
    Alijotas-Reig J, Ferrer-Oliveras R, Rodrigo-Anoro MJ, Farran-Codina I, Cabero-Roura L, Vilardell-Tarres M: Anti-beta(2)-glycoprotein-I and anti-phosphatidylserine antibodies in women with spontaneous pregnancy loss. Fertil Steril 2010; 93:23302336.
  • 85
    Lockshin MD, Kim M, Laskin CA, Guerra M, Branch DW, Merrill J, Petri M, Porter TF, Sammaritano L, Stephenson MD, Buyon J, Salmon JE: Prediction of adverse pregnancy outcome by the presence of lupus anticoagulant, but not anticardiolipin antibody, in patients with antiphospholipid antibodies. Arthritis Rheum 2012; 64:23112318.
  • 86
    Umehara N, Tanaka T: The incidence of various antiphospholipid antibodies, measured by commercial-based laboratory, with recurrent spontaneous abortion and the impact of their profiles on reproductive outcome with active anticoagulant therapy. ISRN Obstet Gynecol 2012; 2012:819356.
  • 87
    Ortel TL: Antiphospholipid syndrome: laboratory testing and diagnostic strategies. Am J Hematol 2012; 87(Suppl 1):S75S81.
  • 88
    de Laat B, Derksen RH, Urbanus RT, de Groot PG: IgG antibodies that recognize epitope Gly40-Arg43 in domain I of beta 2-glycoprotein I cause LAC, and their presence correlates strongly with thrombosis. Blood 2005; 105:15401545.
  • 89
    de Laat B, Pengo V, Pabinger I, Musial J, Voskuyl AE, Bultink IE, Ruffatti A, Rozman B, Kveder T, de Moerloose P, Boehlen F, Rand J, Ulcova-Gallova Z, Mertens K, de Groot PG: The association between circulating antibodies against domain I of beta2-glycoprotein I and thrombosis: an international multicenter study. J Thromb Haemost 2009; 7:17671773.
  • 90
    Banzato A, Pozzi N, Frasson R, De Filippis V, Ruffatti A, Bison E, Padayattil SJ, Denas G, Pengo V: Antibodies to Domain I of beta(2)Glycoprotein I are in close relation to patients risk categories in Antiphospholipid Syndrome (APS). Thromb Res 2011; 128:583586.
  • 91
    Pelkmans L, de Laat B: Antibodies against domain I of beta2-glycoprotein I: the one and only? Lupus 2012; 21:769772.
  • 92
    Shoenfeld Y, Krause I, Kvapil F, Sulkes J, Lev S, von Landenberg P, Font J, Zaech J, Cervera R, Piette JC, Boffa MC, Khamashta MA, Bertolaccini ML, Hughes GR, Youinou P, Meroni PL, Pengo V, Alves JD, Tincani A, Szegedi G, Lakos G, Sturfelt G, Jonsen A, Koike T, Sanmarco M, Ruffatti A, Ulcova-Gallova Z, Praprotnik S, Rozman B, Lorber M, Vriezman VB, Blank M: Prevalence and clinical correlations of antibodies against six beta2-glycoprotein-I-related peptides in the antiphospholipid syndrome. J Clin Immunol 2003; 23:377383.
  • 93
    Cowchock S: Treatment of antiphospholipid syndrome in pregnancy. Lupus 1998; 7(Suppl 2):S95S97.
  • 94
    Vaquero E, Lazzarin N, Valensise H, Menghini S, Di Pierro G, Cesa F, Romanini C: Pregnancy outcome in recurrent spontaneous abortion associated with antiphospholipid antibodies: a comparative study of intravenous immunoglobulin versus prednisone plus low-dose aspirin. Am J Reprod Immunol 2001; 45:174179.
  • 95
    Perricone R, De Carolis C, Kroegler B, Greco E, Giacomelli R, Cipriani P, Fontana L, Perricone C: Intravenous immunoglobulin therapy in pregnant patients affected with systemic lupus erythematosus and recurrent spontaneous abortion. Rheumatology (Oxford) 2008; 47:646651.
  • 96
    Silveira LH, Hubble CL, Jara LJ, Saway S, Martinez-Osuna P, Seleznick MJ, Angel J, O'Brien W, Espinoza LR: Prevention of anticardiolipin antibody-related pregnancy losses with prednisone and aspirin. Am J Med 1992; 93:403411.
  • 97
    Bramham K, Thomas M, Nelson-Piercy C, Khamashta M, Hunt BJ: First-trimester low-dose prednisolone in refractory antiphospholipid antibody-related pregnancy loss. Blood 2011; 117:69486951.
  • 98
    Hutton B, Sharma R, Fergusson D, Tinmouth A, Hebert P, Jamieson J, Walker M: Use of intravenous immunoglobulin for treatment of recurrent miscarriage: a systematic review. BJOG 2007; 114:134142.
  • 99
    Kwak JY, Quilty EA, Gilman-Sachs A, Beaman KD, Beer AE: Intravenous immunoglobulin infusion therapy in women with recurrent spontaneous abortions of immune etiologies. J Reprod Immunol 1995; 28:175188.
  • 100
    Kwak JY, Kwak FM, Ainbinder SW, Ruiz AM, Beer AE: Elevated peripheral blood natural killer cells are effectively downregulated by immunoglobulin G infusion in women with recurrent spontaneous abortions. Am J Reprod Immunol 1996; 35:363369.
  • 101
    Piette JC, Le Thi Huong D, Wechsler B: [Therapeutic use of intravenous immunoglobulins in the antiphospholipid syndrome]. Ann Med Interne (Paris) 2000; 151(Suppl 1):1S511S54.
  • 102
    Branch DW, Peaceman AM, Druzin M, Silver RK, El-Sayed Y, Silver RM, Esplin MS, Spinnato J, Harger J: A multicenter, placebo-controlled pilot study of intravenous immune globulin treatment of antiphospholipid syndrome during pregnancy. The Pregnancy Loss Study Group. Am J Obstet Gynecol 2000; 182:122127.
  • 103
    Xiao J, Xiong J, Zhu F, He L: Effect of prednisone, aspirin, low molecular weight heparin and intravenous immunoglobulin on outcome of pregnancy in women with antiphospholipid syndrome. Exp Ther Med 2013; 5:287291.
  • 104
    Meroni PL, Raschi E, Testoni C, Tincani A, Balestrieri G, Molteni R, Khamashta MA, Tremoli E, Camera M: Statins prevent endothelial cell activation induced by antiphospholipid (anti-beta2-glycoprotein I) antibodies: effect on the proadhesive and proinflammatory phenotype. Arthritis Rheum 2001; 44:28702878.
  • 105
    Ferrara DE, Liu X, Espinola RG, Meroni PL, Abukhalaf I, Harris EN, Pierangeli SS: Inhibition of the thrombogenic and inflammatory properties of antiphospholipid antibodies by fluvastatin in an in vivo animal model. Arthritis Rheum 2003; 48:32723279.
  • 106
    Odiari EA, Mulla MJ, Sfakianaki AK, Paidas MJ, Stanwood NL, Gariepy A, Brosens JJ, Chamley LW, Abrahams VM: Pravastatin does not prevent antiphospholipid antibody-mediated changes in human first trimester trophoblast function. Hum Reprod 2012; 27:29332940.
  • 107
    Johann S, Zoller C, Haas S, Blumel G, Lipp M, Forster R: Sulfated polysaccharide anticoagulants suppress natural killer cell activity in vitro. Thromb Haemost 1995; 74:9981002.
  • 108
    Christopherson KW 2nd, Campbell JJ, Travers JB, Hromas RA: Low-molecular-weight heparins inhibit CCL21-induced T cell adhesion and migration. J Pharmacol Exp Ther 2002; 302:290295.
  • 109
    Fritchley SJ, Kirby JA, Ali S: The antagonism of interferon-gamma (IFN-gamma) by heparin: examination of the blockade of class II MHC antigen and heat shock protein-70 expression. Clin Exp Immunol 2000; 120:247252.