Expression and regulation of colony-stimulating factors and their receptors and the role of colony-stimulating factor 1 at the maternal-conceptus interface in pigs

Objective: Colony-stimulating factors (CSFs) regulate cell survival, proliferation, and differentiation, but their roles at the maternal-conceptus interface in pigs remain unclear.This study investigated the expression, regulation, and function of CSFs (CSF1, CSF2, and CSF3) and their receptors (CSF1R, CSF2RA, and CSF3R) at the maternal-conceptus interface.Methods: The expression and regulation of CSFs and their respective receptors were analyzed in the endometrium during the estrous cycle and pregnancy, and in conceptus and chorioallantoic tissues during pregnancy.The functions of CSF1 were also investigated in endometrial epithelial and conceptus trophectoderm cells.Results: CSFs and CSF receptors were expressed in the endometrium during the estrous cycle and pregnancy with increasing levels of CSF1, CSF3, CSF1R, CSF2RA, and CSF3R during the periimplantation period.The expression of CSF receptors was localized predominantly to endometrial epithelial cells.CSFs and their receptors were also expressed in conceptuses and chorioallantoic tissues during pregnancy.IL1B upregulated the expression of CSFs and their receptors, whereas IFNG increased most CSFs and receptors but reduced CSF2 expression in endometrial explants.Furthermore, CSF1 altered the expression of cytokines, matrix metalloproteinases, prostaglandin synthesis enzymes, and prostaglandin transporters in endometrial epithelial cells.In trophectoderm cells, CSF1 reduced cell migration while increasing the expression of implantation-related genes and prostaglandin synthesis enzymes in vitro.Conclusion: CSFs and their receptors are dynamically expressed at the maternal-conceptus interface and may play important roles in the establishment of pregnancy by regulating endometrial epithelial and conceptus trophectoderm cell functions in pigs.