Potential role of toll-like receptor 3 in a murine model of polyinosinic-polycytidylic acid-induced embryo resorption

Objective: To investigate the potential role that toll-like receptor 3 (TLR3) may play in a murine model of polyinosinic-polycytidylic acid (polylC)-induced embryo resorption. Design: An animal model-based study on induced embryo resorption. Setting: University animal laboratory. Animal(s): Pathogen-free animals housed under barrier conditions and monitored for health status. Pregnant BALB/c mouse mated by C57BL/6 male was used as a model of allogeneic gestation. Intervention(s): The administration of polylC was performed to establish a murine model of induced embryo resorption. with or without TLR3 blocking by multiple injection of mAb against this receptor. Main Outcome Measure(S): Flow cytometric analysis was performed to detect the percentage of CD45(+)DX5(+) and DX5(+)CD69(+) cell subsets, with the DX5 antigen used as a common natural killer (NK) cell marker, and CD69 as a marker for activated NK cells, respectively. Result(s): In the allogeneic mating model, BALB/cXC57BL/6, both the CD45(+)DX5(+) and DX5(+)CD69(+) cell percentages were significantly elevated upon polylC stimulation at the absence of anti-TLR3 administration but were kept unchanged if the female mice were pretreated with anti-TLR3 monoclonal antibody. Accordingly, the resorption rate of embryos was boosted by polylC administration. but this effect could be abrogated by pretreatment of anti-TLR3 mAb. Conclusion(s): The engagement of polylC with TLR3 may be critical to the activation of NK cells infiltrated at the feto-maternal interface, subsequently resulting in an increase in embryo resorption.