Ghrelin deficiency modifies the uterine inflammatory response affecting mice embryo implantation and development.

Buenos Aires

Simposio; The International Federation of Placenta Associations 2019 Symposium (IFPA2019); 2019

IFPA and SLIMP

In a previous study, we reported that ghrelin inhibition during the peri-implantation period causes increased embryo loss and fetal atrophy. Similar results, but to a lesser extent, were observed in conditions of hyperghrelinemia. These data indicated that ghrelin exerts crucial physiological roles during early gestation. Since it has been shown that ghrelin has immune modulatory properties, we aimed to analyze the uterine inflammatory/immune response of pregnant mice using an already validated mouse model of peri-implantation ghrelin misbalance.Experimental hyperghrelinemia or ghrelin action blockade was induced by treatment with ghrelin or the ghrelin receptor antagonist (D-Lys3)GHRP-6, respectively. Albino Swiss (N:NIH) dams (6-7/treatment) were s.c. injected with ghrelin (4 nmol/animal/day), (D-Lys3)GHRP-6 (6 nmol/animal/day) or vehicle (control) from day 3 to 8 of gestation. Dams were euthanized at day 8 and the following parameters were analyzed: 1) percentage of normal or atrophied fetuses and number of implantation sited or resorbed fetuses (micro and macroscopically), 2) expression of VEGF, MMP9, GM-CSF, IL-10, IL-17 and IL-6 mRNA in uterine tissue by qPCR and 3) the frequencies of uterine tissue infiltrating leukocyte subsets [T (CD3+) lymphocytes, NK cells, granulocytes (Gr1+), dendritic cells (CD11c+) and macrophages (CD11b+)] by flow cytometry. Statistical analyses were performed using ANOVA.The blockade of ghrelin by the (D-Lys3)GHRP-6 antagonist treatment induced a significant increase in the number of resorbed fetuses (control=0.5±0.5 and ghrelin=1.2±0.4 vs. antagonist=3.7±0.5, p<0.05) and the percentage of atrophied fetuses (control=4.4±4.0 and ghrelin=8.9±3.6 vs. antagonist=30.2±4.0, p<0.05). Furthermore, (D-Lys3)GHRP-6 treatment significantly increased uterine expression of IL-6 (control=4.2±1.0 vs. antagonist=8.4±0.9, p<0.05), IL-17 (control=7.3±0.9 and ghrelin=6.8±0.9 vs. antagonist=11.6±0.9, p<0.05) and MMP9 (control=6.2±0.6 vs. ghrelin=7.9±0.6 and antagonist=8.6±0.6, p<0.05). Conversely, the ghrelin antagonist treatment induced a significant decrease in uterine expression levels of IL-10 (control=10.6±0.9 vs. antagonist=6.5±0.8, p<0.05). Moreover, the antagonist treatment modified the proportions of uterine tissue infiltrating leukocyte subsets. In fact, significantly decreased frequencies of T cells (control=1.1±0.1 vs. ghrelin=0.4±0.1 vs. antagonist=0.1±0.1, p<0.05) and significantly increased frequencies of NK (control=1.2±0.2 and ghrelin=1.2±0.1 vs. antagonist=1.8±0.1) and dendritic cells (control=12.1±1.6 and ghrelin=9.5±1.4 vs. antagonist=17.9±1.4) were found in uterine tissue of treated dams with respect to controls. In conclusion, our results show that ghrelin inhibition causes increased embryo loss and alters the immune compartment of uterine tissue by biasing the local immune response towards an inflammatory phenotype.