The Role of Trophoblast Interferons in the Maintenance of Early Pregnancy in Ruminants

PROBLEM: Are the effects of ruminant trophoblast interferon‐tau (IFN‐τ) on uterine prostaglandin (PG) secretion a specific action of this cytokine and what are the effects of IFN‐τ on expression of uterine genes not generally associated with pregnancy maintenance? METHODS: The effects of IFN‐τ and IFN‐α on bovine uterine expiant and epithelial cell production of PGF2α and PGE2 were determined in the presence and absence of oxytocin (OT). The effects of intrauterine administration of IFN‐τ were determined on uterine expression of retinol‐binding protein (RBP) and transforming growth factor‐beta (TGF‐β) isoforms. RESULTS: IFN‐τ attenuated uterine endometrial secretion of PGF2α and PGE2 in vitro and diminish PG stimulation by OT. IFN‐τ and IFN‐α were observed to be equipotent. Intrauterine infusion of IFN‐τ resulted in a significant decrease in steady‐state RBP mRNA levels and expression of TGF‐B1, 2, and 3 mRNA levels were lowest in IFN‐τ treated animals. CONCLUSION: Negative regulation of gene expression may be a general strategy in IFN activity. This may explain the similar activities of IFN‐τ and IFN‐α on a broad variety of cell types, including ruminant uterine endometrium.