Peri-Conceptual Cytokines - Setting the Trajectory for Embryo Implantation, Pregnancy and Beyond

Problem The peri-conceptual environment influences the early embryo to impart long-term consequences for the fetus and neonate; however, the underlying mechanisms are not well defined. Method of Study We argue that the cytokine network acting in the female reproductive tract during the pre- and peri-implantation period integrates environmental information to program the embryo and fine-tune the maternal immune response and endometrial remodelling to determine implantation success. Results As well as sex steroid hormones and male seminal fluid factors, female tract cytokines are influenced by agents signalling via the Toll-like receptors including the microbiome and a plethora of metabolic, chemical and other stressors. In mouse models, an altered peri-conceptual cytokine environment induced by cytokine deficiency, inflammatory insults or dysregulated seminal fluid signalling is associated with adverse effects on embryo development, pregnancy viability and reproductive outcome. Conclusion The cytokine network provides a pivotal mechanism through which environmental factors influence both embryo development and receptivity of the uterus.