Hypothyroidism induces a decrease in uterine NK cells during the implantation process.

GAMARRA LUQUES, C; RINALDINI, E; RINALDINI, E; TRONCOSO M.; HAPON, MB; TRONCOSO M.; HAPON, MB; GAMARRA LUQUES, C

San Luis

Congreso; XXXVII Reunión ciéntifica anual de la Sociedad de Biología de Cuyo; 2019

Sociedad de Biología de Cuyo

Uterine natural killer (uNK) cells are the major leukocyte present in the endometrium during implantation. The role of these cells is important in maintaining a healthy pregnancy. The main function of uNK cells is to regulate maternal uterine vasculature remodeling. It has been demonstrated that uNK cells produce proangiogenic factors such as VEGF, growth factors and provide local IFN-γ for initiation of spiral artery formation during pregnancy. It is known that angiogenesis is a critical process in the uterine endometrium for embryo implantation, maintenance of early pregnancy, and development of the placenta. Our lab is focused on understanding the effect of hypothyroidism in the embryo implantation process. Hypothyroidism is one of the most common endocrine abnormalities implicated in the recurrent loss of pregnancy. We had shown that hypothyroidism in the rat is associated with a lower number of pups per litter due to a lower number of implantation sites. We had also observed a decrease in the proliferation (PCNA) of the endothelial and decidua cells and reduced vascularization during the process of implantation of the embryo. In this work, we hypothesized that hypothyroidism induces a decrease in uNK cells during the embryo implantation process. Therefore, the aim of this work was to study the effect of hypothyroidism in the uNK cells during the embryo implantation process, in two early stages of pregnancy. Hypothyroidism was induced in female Wistar rats bred in our laboratory by daily administration of 6-propyl-2-thiouracil (PTU) 0.1 g/l in drinking water. On day five (G5) and seven (G7) of gestation, uterine vascularization and the presence of uNK cells were evaluated by indirect immunofluorescence (IFI). Our results show that hypothyroidism significantly decreases the number of uNK cells before the implantation process (G5). However, when implantation occurs (G7), there is no significant difference between the animals treated with PTU and the controls. In conclusion, hypothyroidism affects the number of uNK cells present in the uterine decidua, before implantation occurs (G5). This could be related to the decrease in vascularization, a process necessary for embryo implantation to occur, reported before by our group. However, further studies are necessary to corroborate these hypothesis.