[Immunology of fertilization, implantation and pregnancy: Key interactions and therapeutic perspectives]

The immunology of fertilization, implantation and pregnancy is based on a complex balance between maternal immune tolerance and a controlled inflammatory response. Adaptation of the maternal immune system is essential for the survival of the semi-allogenic foetus, and any imbalance can lead to complications such as implantation failure, early pregnancy loss and obstetric pathologies. Several cell types, including uterine Natural Killer (NKu) cells, macrophages and dendritic cells, play a key role in regulating the maternal-fetal interface. Similarly, the balance between pro- and anti-inflammatory cytokines, as well as the expression of specific HLA molecules, determines the success of gestation. Immunological disorders, such as those observed in endometriosis, adenomyosis and chronic endometritis, alter endometrial receptivity and increase the risk of reproductive failure. In addition, abnormalities in NK cell activation and cytokine profile have been implicated in repeated implantation failure and recurrent pregnancy loss. Although immunomodulatory treatments such as corticosteroids, intravenous immunoglobulins and intralipids are being explored to improve pregnancy outcomes, their efficacy has yet to be confirmed by large-scale studies.