*3.2.1 Defective placentation*

aPLs affect trophoblast viability by both decreasing their proliferation and promoting their death [49] and by altering their expression of the apoptotic regulators BcL-2 and Bax [54]. Furthermore, aPLs decrease the expression of caspases 3 and 7, suggesting that they are involved in death mechanism of the trophoblast [55]. Moreover, as demonstrated by different studies [49, 56], aPLs are involved in the inhibition of syncytialization, an essential process for the replenishment of the syncytiotrophoblast. It has been speculated that the mechanism by which aPLs inhibit syncytializationis due to the decrease of caspase expression, the activation of which is required for cytotrophoblast fusion [52]. Thus, proliferation of cytotrophoblast is reduced, while death increases. This results in a fewer cytotrofoblasts available to replenish the syncytiotrophoblasts. On the other hand, increased death of the syncytiotrofoblasts, leads to increased production of trophoblast debris and increased denudation of syncytiotrophoblasts and fibrinoid deposition. This process leads to a decrease in de syncytialisation and thus impaired placentation [49].
