Abstract
Type I interferons (IFNs) bind to the heterodimeric receptor composed of IFN-α/β receptor 1 (IFNAR1) and IFN-α and β receptor 2 (IFNAR2) to transmit signals into the cell. It is well known that IFN-δ (IFND), a type I IFN, is secreted by the conceptus during early pregnancy in pigs. However, expression and regulation of IFNAR1 and IFNAR2 in the porcine uterine endometrium are not well understood. Thus, we analyzed the expression and regulation of IFNAR1 and IFNAR2 in the uterine endometrium during the estrous cycle and pregnancy and conceptus and chorioallantoic tissues during pregnancy in pigs. The IFNAR1 and IFNAR2 mRNAs were expressed in the uterine endometrium, and their levels on Day 12 of pregnancy were higher than those on Day 12 of the estrous cycle and highest during pregnancy. The IFNAR1 and IFNAR2 mRNAs were also expressed in conceptuses during early pregnancy, in chorioallantoic tissues during mid-to-term pregnancy, and in endometrial epithelial cells and chorionic membrane during mid-to-late pregnancy. The abundance of IFNAR1 and IFNAR2 mRNAs was increased by interleukin-1β (IL1B), and the abundance of IFNAR2 was increased by estradiol in endometrial tissue explants. Thus, IFNAR1 and IFNAR2 mRNAs were expressed in the uterine endometrium during the estrous cycle and pregnancy in a pregnancy status- and stage-specific manner, and their expression was affected by estradiol and/or IL1B. These results suggest that endometrial and conceptus IFNAR1 and IFNAR2 may mediate the action of type I IFNs during the implantation period for the establishment and maintenance of pregnancy in pigs.