VIP induces an immunosuppressant microenvironment in the maternal-placental interface and improves pregnancy outcome in mouse models of pregnancy complications

VANESA HAUK; LUCILA GALLINO; GUILLERMINA CALO; DANIEL PAPARINI; ROSANNA RAMHORST; CLAUDIA PÉREZ LEIRÓS

Pécs

Simposio; 11th International Symposium on VIP, PACAP and Related Peptides; 2013

The maintenance of immune homeostasis at implantation and during the early post-implantation stage involves several immunomodulatory circuits active at the maternal-placental interface. A dynamic response with a predominant anti-inflammatory and tolerogenic profile at the local level is required and various immune cell types and soluble factors are involved. The loss of homeostasis early after implantation can compromise pregnancy in an all-or-none manner with pregnancy loss, or affect its outcome at later stages as in pre-eclampsia. VIP has anti-inflammatory, tolerogenic and relaxing effects so its ability to promote an immunosuppressant microenvironment and improve pregnancy outcome was explored in two mouse models of pregnancy complications, the non obese diabetic (NOD) mouse at the pre-diabetic stage (singeneic mating) and the CBAxDBA abortion prone model. Pregnant uteri were carefully dissected at day 8-10 of pregnancy and implantation sites either viable or with incipient resorption processes were analyzed to calculate resorption rate, distribution along horns among other gestation outcome signs. Implantation sites were isolated for VIP, VPAC, cytokine and transcription factor assessment by RT-PCR, immunoblotting and immunohistochemistry. To assess the effect of VIP in vitro, implantation site explants were incubated for 6 h with 1-100 nM VIP at 37°C. To study the effect of VIP in vivo, mice were injected ip with 1-10 nmol VIP in PBS at day 6. Results indicate that VIP and VPAC2 receptor expression was detected in implantation sites at gestation days 8-10. Trophoblast cells were the predominant cell type positive for VIP immunostaining in the viable implantation sites at days 8 and 9, some of them were lying adjacent to maternal blood vessels and at the interface between the placenta and the decidua. Small round scattered cells with VIP immunostaining and negative for cytokeratine were also found in the mesometrial deciduas. VIP treatment of implantation site explants increased VPAC2, TGF-b, Foxp3 and IL-10 expression. Sites with resorption processes presented lower VIP expression, reduced suppressant markers, increased IL-17 and RORgT expression and a reduced response to VIP in Foxp3 protein levels, compared with viable sites. Pregnant NOD or CBA mice treated with VIP at gestational day 6 increased the number of implanted embryos, presented an even distribution of embryos along the horns with increased local expression of IL-10, TGF-b and Foxp3. In addition, VIP treatment promoted a suppressant clearance of apoptotic cells by peritoneal macrophages in both strains. We conclude that VIP/VPAC system is expressed at the early maternal-placental interface and that VIP induces local anti-inflammatory and tolerogenic signals that partially improve pregnancy outcome in two different murine models of pregnancy complications.