Reduced placental growth and hCG secretion in vitro induced by antiphospholipid antibodies but not by anti-Ro or anti-La: Studies on sera from women with SLE/PAPS

Systemic lupus erythematosus (SLE) and primary anti-phospholipid syndrome (PAPS) are autoimmune diseases causing recurrent pregnancy loss. We hypothesized that anti-phospholipid antibodies (aPL), but not anti-Ro and anti-La antibodies, might have a role through direct placental damage. We cultured human placental explants in sera from women with SLE/PAPS with different antibodies. These sera were found to reduce placental growth and increase trophoblastic apoptosis. No effect was found on estradiol or progesterone secretion, but inhibition in βhCG secretion was detected. βhCG was reduced in women with a history of recurrent pregnancy loss or thromboembolic events, and was also the most sensitive marker when examining the effects of specific antibodies. High titers of aPL were found to cause the largest reduction in βhCG. Anti-Ro and anti-La did not induce placental damage. A strong correlation was found between the rise in the number of different antibodies in the sera and the incidence of recurrent pregnancy loss, which was also accompanied by a decline in the βhCG levels. In conclusion, aPL, but not anti-Ro or anti-La, may cause placental damage in vitro. Thus βhCG levels might constitute a predictive marker for the risk of placental damage and pregnancy loss in women with SLE/PAPS.