Conceptus-uterus interactions in pigs: endometrial gene expression in response to estrogens and interferons from conceptuses.

This review highlights information on conceptus-uterus interactions in the pig with respect to uterine gene expression in response to estrogens and interferons (IFNs) secreted from elongating conceptuses. Pig conceptuses release estrogens for pregnancy recognition, but also secrete IFNs that do not appear to be antiluteolytic. Estrogens and IFNs induce expression of largely non-overlapping sets of genes, and evidence suggests that pig conceptuses orchestrate essential events of early pregnancy including pregnancy recognition signaling, implantation and secretion of histotroph by precisely controlling temporal and spatial (cell-specific) changes in uterine gene expression through initial secretion of estrogens, followed by cytokines including IFNG and IFND. By Day 12 of pregnancy, estrogens increase the expression of multiple genes in the uterine luminal epithelium including SPP1, STC1, IRF2 and STAT1 that likely have roles for implantation. By Day 15 of pregnancy, IFNs upregulate a large array of IFN responsive genes in the underlying stroma and glandular epithelium including ISG15, IRF1, STAT1, SLAs and B2M that likely have roles in uterine remodeling to support placentation.