Comparison of the Effects of Early Pregnancy with Human Interferon, Alpha 2 (IFNA2), on Gene Expression in Bovine Endometrium1

Abstract

Interferon tau (IFNT), a type I IFN similar to alpha IFNs (IFNA), is the pregnancy recognition signal produced by the ruminant conceptus. To elucidate specific effects of bovine IFNT and of other conceptus-derived factors, endometrial gene expression changes during early pregnancy were compared to gene expression changes after intrauterine application of human IFNA2. In experiment 1, endometrial tissue samples were obtained on Day (D) 12, D15, and D18 postmating from nonpregnant or pregnant heifers. In experiment 2, heifers were treated from D14 to D16 of the estrous cycle with an intrauterine device releasing IFNA2 or, as controls, placebo lipid extrudates or PBS only. Endometrial biopsies were performed after flushing the uterus. All samples from both experiments were analyzed with an Affymetrix Bovine Genome Array. Experiment 1 revealed differential gene expression between pregnant and nonpregnant endometria on D15 and D18. In experiment 2, IFNA2 treatment resulted in differential gene expression in the bovine endometrium. Comparison of the data sets from both studies identified genes that were differentially expressed in response to IFNA2 but not in response to pregnancy on D15 or D18. In addition, genes were found that were differentially expressed during pregnancy but not after IFNA2 treatment. In experiment 3, spatiotemporal alterations in expression of selected genes were determined in uteri from nonpregnant and early pregnant heifers using in situ hybridization. The overall findings of this study suggest differential effects of bovine IFNT compared to human IFNA2 and that some pregnancy-specific changes in the endometrium are elicited by conceptus-derived factors other than IFNT.endometrium, hormone action, pregnancy, reproductive immunology, uterus

Maternal-embryo interaction leading up to the initiation of implantation of pregnancy in cattle

“…It is only when IFNT secretion from the conceptus is sufficient to induce the pregnancy recognition response in both the endometrium and in the extra uterine environment, that divergences between the pregnant and non-pregnant uterus are established. In general, these differences are detectable by Day 15 or Day 16 of pregnancy (Forde et al, 2011b;Bauersachs et al, 2012) and the major changes identified include response to a Type I Interferon, of which IFNT is one. This includes the up-regulation of 'classical' interferon-stimulated genes (ISGs) such as ISG15, (Johnson et al, 1998), MX1 and MX2 (Hicks et al, 2003), OAS1, BST2, B2M, CXCL10, STAT1, STAT2, PTX3, EIF4E, USP18 (Forde et al, 2011b) Indeed in the last number of years there have been quite a number of large transcriptomic studies performed on gene expression changes in the endometrium of pregnancy compared with non-pregnant or cyclic heifers.…”

“…This includes the up-regulation of 'classical' interferon-stimulated genes (ISGs) such as ISG15, (Johnson et al, 1998), MX1 and MX2 (Hicks et al, 2003), OAS1, BST2, B2M, CXCL10, STAT1, STAT2, PTX3, EIF4E, USP18 (Forde et al, 2011b) Indeed in the last number of years there have been quite a number of large transcriptomic studies performed on gene expression changes in the endometrium of pregnancy compared with non-pregnant or cyclic heifers. Despite the different platforms used for analysis, breed of animal and different data analysis methods Bauersachs et al (2012) used gene set enrichment analysis to reveal a conceptus-induced signature in the endometrium across numerous studies on Days 15, 16, 17, 18 and 20.…”

“…Further evidence that the conceptus itself produces factors that affect the endometrium is that differences (although quite subtle) between pregnant and cyclic heifers were identified on Day 13 of pregnancy in the endometrium of heifers using RNA sequencing, but these genes were not regulated by short-term exposure to IFNT (Forde et al, 2012b). Also, comparison of endometrium tissue recovered from pregnant heifers to those exposed to IFN α in the uterine lumen for 2 days, revealed that not all genes induced by the conceptus are regulated by IFN (Bauersachs et al, 2012). Collectively these data demonstrate that, although the main molecule affecting the endometrium is IFNT, additional molecules, some of which have yet to be identified, may also play a role in conceptus maternal interactions.…”

“…Indeed, as mentioned above, it is possible to transfer an embryo to a synchronous uterus 7 days after oestrus and establish a pregnancy, as is routine in commercial bovine embryo transfer, and even up to Day 16. It is only in association with maternal recognition of pregnancy, which occurs on approximately Day 16 in cattle, that significant changes in the transcriptomic profile are detectable between cyclic and pregnant endometria (Forde et al, 2011b;Bauersachs et al, 2012), when the endometrium responds to increasing amounts of interferon-tau (IFNT) secreted by the filamentous conceptus.…”

Embryo maternal immune interactions in cattle

“…Generally, genes encoding trophoblast kunitz domain proteins, pregnancyassociated glycoproteins, cytoskeletal transcripts, heat shock proteins and calcium-binding proteins had highest expression levels at each of these stages of development (Lonergan and Forde, 2014;Mamo et al, 2011). Bauersachs et al (2012) carried out a gene set enrichment analysis of several global transcriptomic datasets from days 15, 16, 17, 18 and 20 of the oestrus cycle or pregnancy and identified a conceptus-induced signature in the endometrium during the process of pregnancy recognition. Together with progesterone (P4), IFNT regulates endometrial gene expression necessary for the establishment of the proper uterine environment during the implantation period (Klein et al, 2006).…”