VIP in vivo treatment modulates maternal macrophage activation profile and efferocytic ability in the CBAxDBA resorption prone model

LUCILA GALLINO; GUILLERMINA CALO; VANESA HAUK; LAURA FRACCAROLI; ESTEBAN GRASSO; MONICA VERMEULEN; CLAUDIA PEREZ LEIROS; ROSANNA RAMHORST

Congreso; IMMUNOCOLOMBIA2015 - 11th Congress of the Latin American Association of Immunology; 2015

Homeostasis maintenance at the fetomaternal interface is the result of multiple processes that occur at local and systemic levels which require several ongoing signals and checkpoints. Immune cells involved in the control of the early inflammatory response have a central role atthe maternalplacental interface such as the activation of macrophages in an alternative profile. Particularly VIP, vasoactive intestinal peptide, mediates immune and nervous effector functions and has emerged as a potential effective treatment for inflammatory and autoimmune disordersbased on its antiinflammatory and tolerogenic effects as it was demonstrated in mouse models of inflammation through its action on macrophages and T cell VPAC receptors. Since the control of the initial inflammatory response after embryo implantation appears to be crucial for a successful outcome and considering that VIP mediates antiinflammatoryand tolerogenic immune effects, we hypothesized that VIP participates in homeostasis maintenance at the early maternalplacental interface inducing an immunosuppresant microenvironment through efferocytosis associated with an alternative activation profile of maternal macrophages.We used the mating of CBA/J females (H2k) with DBA/2 males (H2d) that provokes spontaneously high resorption rates associated with a failure in the maternal tolerogenic response and we investigated whether in vivo VIP treatment contributes to an immunosuppressant local microenvironment associated with an improved pregnancy outcome. Thereore, implantation sites from the CBA/J × DBA/2 mating females on day 8.5 of gestationwere isolated after in vivo VIP treatment (2nmol/mouse i.p.) or PBS on day 6.5. for VIP/VPAC, Foxp3, RORγt, TGFbeta and PPAR gamma expression was assessed by RTPCR. Peritoneal macrophages were obtained at day 8.5 and efferocytic ability was tested using latex beadsFITC or apoptotic thymocytes, evaluated by FACS and microscopy respectively. Supernatants were obtained and TNFalfa and IL12 tested by ELISA while IL10by FACS analysis. We could oberve that pregnancy induced the expression of VIP, VPAC1 and VPAC2 in the uterus compared with nonpregnantmice. VIP treatment significantly increased the number of viableimplantation sites and improved the asymmetric distribution of implanted embryos. This effect was acompained by a decrease in RORγt and increase in TGFbeta and PPARgamma expression at the implantation sites. On the other hand, VIP modulated the efferocytosis evaluated by two complementary approaches, the efferocytosis of latex beads and of apoptotic thymocytes. In addition, VIP treatment in vivo increased the frequency of F4/80 cells IL10producers while did not modulate TNFalfa and IL12 secretion suggesting their activation in an alternative profile.The present results provide new data that the in vivo treatment with VIP prevents embryo resorption and improves pregnancy end points evidenced as an increase in the number of viable embryo with a symmetric distribution in the uterine horns associated with an increase in the efferocytic ability of maternal macrophages associated with an immunosuppressantmicroenvironment.