Adverse pregnancy outcome in the antiphospholipid syndrome: focus for future research

Antiphospholipid antibodies do not a syndrome make

The association of antiphospholipid antibodies (aPLs) with a poor obstetric history and/or thrombotic event is typical of the antiphospholipid syndrome (APS). We report four cases of poor pregnancy outcome where a diagnostic label of APS resulted in delayed recognition of other causes of pregnancy loss. Pregnancy outcomes in these women were not improved with antithrombotic therapy alone. Successful outcomes were achieved only when other causes of recurrent miscarriage were considered and treated.

Management of pregnancy in antiphospholipid syndrome

Pregnant women with APS are at high risk of maternal and fetal pregnancy complications. Multidisciplinary teams expert in this condition should coordinate management. Even with current management strategies, the risk of maternal thrombosis, fetal loss, or other adverse obstetric outcomes remains. Close monitoring of the various aspects of this condition may reduce maternal morbidity and improve fetal outcome. The pathogenesis of the adverse pregnancy outcome in APS has not yet been fully elucidated, although active research in this field continues. Until this is ascertained, we must accept that many aspects of management are purely empiric, and it is our duty to counsel patients thoroughly so that they understand the risks and benefits of the treatment options they are offered.

Antiphospholipid antibodies affect trophoblast gonadotropin secretion and invasiveness by binding directly and through adhered beta2-glycoprotein I

OBJECTIVE

To investigate the in vitro ability of antiphospholipid antibodies (aPL) to bind human trophoblast cells and to affect gonadotropin secretion and invasiveness.

METHODS

Antiphospholipid antibody IgG from women with recurrent miscarriages, beta2-glycoprotein I (beta2GPI)-independent IgG aPL human monoclonal antibody (mAb) (519), and IgM anti-beta2GPI human mAb (TMIG2) were investigated for their binding to trophoblasts cultured for various amounts of time, their ability to affect invasiveness of Matrigel-coated filters, and their release of human chorionic gonadotropin (hCG).

RESULTS

Polyclonal IgG aPL, as well as mAb 519 and TMIG2, bound to trophoblasts, the highest binding being found when cells displayed the greatest amount of syncytium formation. TM1G2 binding was found to be betaGPI dependent. Both polyclonal and monoclonal aPL, but not the controls, significantly reduced hCG release and Matrigel invasiveness.

CONCLUSION

These findings suggest that aPL recognition of both anionic PL and adhered beta2GPI on trophoblast cell structures might represent a potential pathogenetic mechanism for defective placentation in women with the antiphospholipid syndrome.

Neonatal and pediatric outcome of infants born to mothers with antiphospholipid syndrome

OBJECTIVE

To determine any adverse outcome to infants born to mothers with Antiphospholipid Syndrome (APS).

DESIGN

Case control study with retrospective data collection and prospective pediatric review.

SETTING

Regional Recurrent Miscarriage Clinic based at a University Teaching Hospital.

PARTICIPANTS

Infants (n = 62) of mothers with APS, compared to 124 index cases randomly selected from the delivery register, matched for gestation and sex who delivered between 1992 and 1997.

RESULTS

Sixty two infants born to 55 women with APS were reviewed to study the neonatal outcome. The prematurity rate for the group was 10%, compared to 8.5% for the total hospital population over the same period of time. Twenty-one percent (21%) had birth weights less than or equal to the 10th centile, which was not statistically significant compared to matched controls. The presence of dual parameter positivity (lupus anticoagulant and anticardiolipin antibody) for APS is clearly associated with a higher incidence of growth restriction. All children were normal on neurodevelopmental and physical examination at pediatric review.

CONCLUSIONS

There was a low rate of preterm delivery. Although the incidence of growth restriction of 21% is higher than expected it was not statistically significant. There were no developmental abnormalities on follow-up of these children.

Normal expression of tissue factor, thrombomodulin, and annexin V in placentas from women with antiphospholipid syndrome

OBJECTIVE

Placentas from pregnancies complicated by antiphospholipid syndrome often show thromboses and infarction, which may result from aberrations in placental coagulant pathways. We tested the hypothesis that alterations in tissue factor, thrombomodulin, and annexin V expressions contribute to poor pregnancy outcome associated with antiphospholipid syndrome.

STUDY DESIGN

Frozen sections from random biopsy samples of the basal plates of placentas from patients with primary antiphospholipid syndrome (n = 9), patients with secondary antiphospholipid syndrome (n = 3), and gestational age-matched control subjects (n = 10) were immunostained for tissue factor, thrombomodulin, and annexin V. Intensity of immunostaining was assessed by means of quantitative image analysis. Annexin V protein expression was evaluated with Western blotting techniques.

RESULTS

Tissue factor was expressed in the perivascular cells of the villous vasculature. Thrombomodulin and annexin V immunostaining was localized to the syncytiotrophoblast. There were no differences in the intensity of immunostaining for tissue factor, thrombomodulin, and annexin V between placentas from women with antiphospholipid syndrome and those from control subjects. Western blot analysis of annexin V expression showed no differences between study patients and control subjects.

CONCLUSION

Alterations in placental coagulant pathways involving tissue factor, thrombomodulin, and annexin V do not contribute to poor pregnancy outcome associated with antiphospholipid syndrome.

Pregnancy loss and antiphospholipid antibodies

With the use of low-dose heparin, fetal survival of aPL pregnancies is 70-80%, but prematurity and intrauterine growth restriction are common. It is likely, but not proven, that dysregulated placental coagulation and resultant vasculopathy are the cause of fetal loss. Details of dysregulated coagulation remain to be described. Opportunities remain to determine the role of coagulopathy in repeated pregnancy loss, identify a critical event or window to which intervention might be directed, identify maternal (and fetal) characteristics other than aPL that determine fetal loss, describe toxicity profiles of current treatments, develop more specific, less toxic therapies, and describe long-term fetal and maternal outcomes.

Use of intravenous immunoglobulin therapy in pregnancy in systemic lupus erythematosus and antiphospholipid antibody syndrome

Systemic lupus erythematosus and antiphospholipid antibody syndrome are associated with an increased risk of intrauterine growth restriction, miscarriage, stillbirth and premature delivery. Recent advances in therapy during pregnancy have improved the outcome but there is still significant fetal and maternal morbidity and mortality. Treatment of patients failing conventional therapy during the second half of pregnancy is difficult and may be complicated by the development of preeclampsia. The addition of intravenous immunoglobulin therapy offers a low risk strategy for reducing autoantibody mediated disease and improving placental function in severely compromised, growth restricted pregnancies.