Endometrial expression of immunomodulatory cytokines and their regulators during early pregnancy in bonnet monkeys (Macaca radiata)

BACKGROUND: It is well established that endometrium undergoes extensive histological changes during implantation and subsequent stages of pregnancy in rodents as well as primates. Our previous investigation using a non-human primate model has demonstrated that morphological alterations are initiated even before the embryo invades the endometrium. The present study was undertaken to determine whether the embryo-induced morphological changes are accompanied by any alteration in the protein levels of the immunomodulatory cytokines and their regulators in the preimplantation stage endometrium. METHODS: The endometrial expression of immunosuppressive factors such as transforming growth factor beta 2 (TGF beta 2), glycodelin (PP14), leukaemia inhibitory factor (LIF) and interleukin-6 (IL-6) were analysed on day 6 post-ovulation in pregnant and non-pregnant bonnet monkeys (Macaca radiata) using immunohistochemical methods. RESULTS: The endometrial expression of TGF beta 2, TGF beta 2 receptor, PP14 and IL-6 were significantly up-regulated (p < 0.05) in pregnant animals as compared to non-pregnant animals, whereas the expression of LIF and its receptor remained unaltered in pregnant animals. CONCLUSIONS: Expression levels of some immunomodulatory cytokines in endometrium are significantly increased even before the embryo invades the endometrium. The altered cytokine expression profile in endometrium probably contributes towards generating a conducive environment for the embryo survival, growth and development in the uterus.