Antiphospholipid antibodies and infertility

Antiphospholipid syndrome and infertility

Antiphospholipid syndrome is a systemic autoimmune disease associated with obstetric complications along with vascular events affecting multiple organ systems in patients having positive titers of antiphospholipid antibodies. Eight to 20% of infertility cases have an unknown cause, part of which could be due to antiphospholipid syndrome. Although still debatable, many studies have addressed the relation between reproductive failure and antiphospholipid antibodies through the relation between antiphospholipid antibodies and unexplained infertility as well as the effect of antiphospholipid antibodies on the outcome of in vitro fertilization–embryo transfer. Few studies and cases have associated the presence of antiphospholipid antibodies with male infertility, describing morphofunctional penile abnormalities and testicular infarction. There are not enough data to support the routine practice of testing antiphospholipid antibodies in patients with infertility.

[Hormone therapy, fertility and pregnancy in antiphospholipid syndrome]

Antiphospholipid syndrome (APS) carries a risk of thrombosis and infertility. Consequently the use of any type of hormone therapy and pregnancy in APS requires special considerations. The present article provides a broad review of all these issues. The use of contraception, hormone replacement therapy and selective estrogen receptor modulators in APS are described. In vitro fertilization/embryo transfer and ovarian induction in these patients are reviewed. Lastly, the possible fetal and maternal complications that can occur during pregnancy are described and, based on the literature, recommendations for the management of pregnancy in women with APS are provided.

[So-called antiphospholipid antibodies and infertility: biological data]

Recurrent early and late foetal losses are common problems found in women with antiphospholipid syndrome, with therapeutic implication and improvement of the prognosis for the next pregnancies with antithrombotic therapy. After these results, some groups propose to extend the antiphospholipid investigations to infertility and failure of in vitro fertilization embryo transfer, but actually without demonstration of a real utility in the management of these women.

Antiphospholipid antibodies in implantation failures

PROBLEM

The amino phospholipids (PL), phosphatidylserine (PS) and phosphatidylethanolamine (PE) are distributed asymmetrically in the plasma membranes of eucaryotic cells. This arrangement involves active transport of PS and PE from the outer to inner membrane leaflet by an aminophospholipid translocase (flipase). Cell activation, injury and programmed cell death (apoptosis) cause collapse of the PS/PE asymmetry by activation of another enzyme system, scramblase. Unlike other cells, the developing trophoblast exteriorizes PS during its differentiation.

METHODS OF STUDY

An analysis of published and unpublished data.

RESULTS

The trophoblast is targeted by antiphospholipid antibodies (aPL), especially to PS (aPS). Cardiolipin is not present in the trophoblast plasma membrane, nonetheless, anticardiolipin (aCL) has been implicated in trophoblast pathology. The aPS and aCL are often crossreactive. Both animal and in vitro experimental models have shown monoclonal and polyclonal aPS and aCL to specifically destroy trophoblast, inhibit syncytium formation, halt human chorionic gonadatropin (hCG) production, and limit trophoblast invasion. Antibodies to PE (aPE) have not been well characterized, however, recent reports from several independent laboratories document that aPE are associated significantly with very early (embryonic) recurrent pregnancy loss (RPL). Umeda and coworkers have shown that during cytokinesis (late telophase) of Chinese hamster ovary (CHO) cells, formation of PE rafts in cleavage furrows is required for completion of cell division and formation of daughter cells. This raises the question whether aPE might interfere with implantation and cell division during embryogenesis.

CONCLUSIONS

A role for aPL in implantation failure and occult pregnancy loss constitutes the basis of this overview.

Molecular pathogenesis of the antiphospholipid syndrome

The antiphospholipid (aPL) syndrome is an acquired autoimmune disorder of unknown etiology in which patients present with thrombosis together with laboratory evidence for antibodies in blood that recognize anionic phospholipid-protein complexes. The main antigenic target for the aPL antibodies has been identified to be beta(2) glycoprotein I (beta(2)GPI), a phospholipid-binding protein. The high affinity of aPL antibody-beta(2)GPI complex for phospholipid membranes seems to be a critical step in the mechanism of this disease. This review focuses on some of the major mechanisms that have been proposed to explain this disorder.