Pregnancy and interferon tau regulate major histocompatibility complex class I and beta2-microglobulin expression in the ovine uterus

Decidual stromal cell response to paracrine signals from the trophoblast: amplification of immune and angiogenic modulators

During the invasive phase of implantation, trophoblasts and maternal decidual stromal cells secrete products that regulate trophoblast differentiation and migration into the maternal endometrium. Paracrine interactions between the extravillous trophoblast and the maternal decidua are important for successful embryonic implantation, including establishing the placental vasculature, anchoring the placenta to the uterine wall, and promoting the immunoacceptance of the fetal allograph. To our knowledge, global crosstalk between the trophoblast and the decidua has not been elucidated to date, and the present study used a functional genomics approach to investigate these paracrine interactions. Human endometrial stromal cells were decidualized with progesterone and further treated with conditioned media from human trophoblasts (TCM) or, as a control, with control conditioned media (CCM) from nondecidualized stromal cells for 0, 3, and 12 h. Total RNA was isolated and processed for analysis on whole-genome, high-density oligonucleotide arrays containing 54,600 genes. We found that 1374 genes were significantly upregulated and that 3443 genes were significantly downregulated after 12 h of coincubation of stromal cells with TCM, compared to CCM. Among the most upregulated genes were the chemokines CXCL1 (GRO1) and IL8,CXCR4, and other genes involved in the immune response (CCL8 [SCYA8], pentraxin 3 (PTX3), IL6, and interferon-regulated and -related genes) as well as TNFAIP6 (tumor necrosis factor alpha-induced protein 6) and metalloproteinases (MMP1, MMP10, and MMP14). Among the downregulated genes were growth factors, e.g., IGF1, FGF1, TGFB1, and angiopoietin-1, and genes involved in Wnt signaling (WNT4 and FZD). Real-time RT-PCR and ELISAs, as well as immunohistochemical analysis of human placental bed specimens, confirmed these data for representative genes of both up- and downregulated groups. The data demonstrate a significant induction of proinflammatory cytokines and chemokines, as well as angiogenic/static factors in decidualized endometrial stromal cells in response to trophoblast-secreted products. The data suggest that the trophoblast acts to alter the local immune environment of the decidua to facilitate the process of implantation and ensure an enriched cytokine/chemokine environment while limiting the mitotic activity of the stromal cells during the invasive phase of implantation.

Prostaglandins and reproduction in female farm animals

Prostaglandins impact on ovarian, uterine, placental, and pituitary function to regulate reproduction in female livestock. They play important roles in ovulation, luteal function, maternal recognition of pregnancy, implantation, maintenance of gestation, microbial-induced abortion, parturition, postpartum uterine and ovarian infections, and resumption of postpartum ovarian cyclicity. Prostaglandins have both positive and negative effects on reproduction; they are used to synchronize oestrus, terminate pseudopregnancy in mares, induce parturition, and treat retained placenta, luteinized cysts, pyometra, and chronic endometritis. Improved therapeutic uses for prostaglandins will be developed when we understand better their involvement in implantation, maintenance of luteal function, and establishment and maintenance of pregnancy.

Monozygotic Twin Model Reveals Novel Embryo-Induced Transcriptome Changes of Bovine Endometrium in the Preattachment Period1

Initiation and maintenance of pregnancy are critically dependent on an intact embryo-maternal communication in the preimplantation period. To get new insights into molecular mechanisms underlying this complex dialog, a holistic transcriptome study of endometrium samples from Day 18 pregnant vs. nonpregnant twin cows was performed. This genetically defined model system facilitated the identification of specific conceptus-induced changes of the endometrium transcriptome. Using a combination of subtracted cDNA libraries and cDNA array hybridization, 87 different genes were identified as upregulated in pregnant animals. Almost one half of these genes are known to be stimulated by type I interferons. For the ISG15ylation system, which is assumed to play an important role in interferon tau (IFNT) signaling, mRNAs of four potential components (IFITM1, IFITM3, HSXIAPAF1, and DTX3L) were found at increased levels in addition to ISG15 and UBE1L. These results were further substantiated by colocalization of these mRNAs in the endometrium of pregnant animals shown by in situ hybridization. A functional classification of the identified genes revealed several different biological processes involved in the preparation of the endometrium for the attachment and implantation of the embryo. Specifically, elevated transcript levels were found for genes involved in modulation of the maternal immune system, genes relevant for cell adhesion, and for remodeling of the endometrium. This first systematic study of maternal transcriptome changes in response to the presence of an embryo on Day 18 of pregnancy in cattle is an important step toward deciphering the embryo-maternal dialog using a systems biology approach.

Identification of endometrial genes regulated by early pregnancy, progesterone, and interferon tau in the ovine uterus

During early pregnancy in ruminants, progesterone (P4) from the corpus luteum and interferon tau (IFNT) from the conceptus act on the endometrium to regulate genes important for uterine receptivity and conceptus growth. The use of the uterine gland knockout (UGKO) ewe has demonstrated the critical role of epithelial secretions in regulation of conceptus survival and growth. A custom ovine cDNA array was used to identify alterations in gene expression of endometria from Day 14 cyclic, pregnant, and UGKO ewes (study 1) and from cyclic ewes treated with P4 or P4 with ZK 136,317 antiprogestin and control proteins or IFNT (study 2). In study 1, expression of 47 genes was more than 2-fold different between Day 14 pregnant and cyclic endometria, whereas 23 genes was different between Day 14 cyclic and UGKO endometria. In study 2, 70 genes were different due to P4 alone, 74 genes were affected by IFNT in a P4-dependent manner, and 180 genes were regulated by IFNT in a P4-independent manner. In each study, an approximately equal number of genes were found to be activated or repressed in each group. Endometrial genes increased by pregnancy and P4 and/or IFNT include B2M, CTSL, CXCL10, G1P3, GRP, IFI27, IFIT1, IFITM3, LGALS15, MX1, POSTN, RSAD2, and STAT5A. Transcripts decreased by pregnancy and P4 and/or IFNT include COL3A1, LUM, PTMA, PUM1, RPL9, SPARC, and VIM. Identification and analysis of these hormonally responsive genes will help define endometrial pathways critical for uterine support of peri-implantation conceptus survival, growth, and implantation.

Conceptus signals for establishment and maintenance of pregnancy

Establishment and maintenance of pregnancy results from signaling by the conceptus (embryo/fetus and associated extraembryonic membranes) and requires progesterone produced by the corpus luteum (CL). In most mammals, hormones produced by the trophoblast maintain progesterone production by acting directly or indirectly to maintain the CL. In domestic animals (ruminants and pigs), hormones from the trophoblast are antiluteolytic in that they act on the endometrium to prevent uterine release of luteolytic prostaglandin F2 alpha (PGF). In cyclic and pregnant sheep, progesterone negatively autoregulates expression of the progesterone receptor (PR) gene in the endometrial luminal (LE) and superficial glandular epithelium (GE). Available evidence in cyclic sheep indicates that loss of the PR is closely followed by increases in epithelial estrogen receptors (ER) and then oxytocin receptors (OTR), allowing oxytocin to induce uterine release of luteolytic PGF pulses. In pregnant sheep, the conceptus trophoblast produces interferon tau (IFN tau) that acts on the endometrium to inhibit transcription of the ER alpha gene directly and the OTR gene indirectly to abrogate development of the endometrial luteolytic mechanism. Subsequently, sequential, overlapping actions of progesterone, IFN tau, placental lactogen (PL) and growth hormone (GH) comprise a hormonal servomechanism that regulates endometrial gland morphogenesis and terminal differentiated function to maintain pregnancy in sheep. In pigs, the conceptus trophoblast produces estrogen that alters the direction of PGF secretion from an endocrine to exocrine direction, thereby sequestering luteolytic PGF within the uterine lumen. Conceptus estrogen also increases expression of fibroblast growth factor 7 (FGF-7) in the endometrial LE that, in turn, stimulates proliferation and differentiated functions of the trophectoderm, which expresses the FGF-7 receptor. Strategic manipulation of these physiological mechanisms can offer therapeutic schemes to improve uterine capacity, conceptus survival and reproductive health.

Conceptus signals for establishment and maintenance of pregnancy

Establishment and maintenance of pregnancy results from signaling by the conceptus (embryo/fetus and associated extraembryonic membranes) and requires progesterone produced by the corpus luteum. In most mammals, hormones produced by the trophoblast maintain progesterone production by acting directly or indirectly to maintain the corpus luteum. In domestic animals (ruminants and pigs), hormones from the trophoblast are antiluteolytic in that they act on the endometrium to prevent uterine release of luteolytic prostaglandin F2alpha. In cyclic and pregnant sheep, progesterone negatively autoregulates progesterone receptor gene expression in the endometrial luminal and superficial glandular epithelium. In cyclic sheep, loss of the progesterone receptor is closely followed by increases in epithelial estrogen receptors and then oxytocin receptors, allowing oxytocin to induce uterine release of luteolytic prostaglandin F2alpha pulses. In pregnant sheep, the conceptus trophoblast produces interferon tau that acts on the endometrium to inhibit transcription of the estrogen receptor alpha gene directly and the oxytocin receptor gene indirectly to abrogate development of the endometrial luteolytic mechanism. Subsequently, sequential, overlapping actions of progesterone, interferon tau, placental lactogen, and growth hormone comprise a hormonal servomechanism that regulates endometrial gland morphogenesis and terminal differentiated function to maintain pregnancy in sheep. In pigs, the conceptus trophoblast produces estrogen that alters the direction of prostaglandin F2alpha secretion from an endocrine to exocrine direction, thereby sequestering luteolytic prostaglandin F2alpha within the uterine lumen. Conceptus estrogen also increases expression of fibroblast growth factor 7 in the endometrial lumenal epithelium that, in turn, stimulates proliferation and differentiated functions of the trophectoderm, which expresses the fibroblast growth factor 7 receptor. Strategic manipulation of these physiological mechanisms may improve uterine capacity, conceptus survival, and reproductive health.

Progesterone and Placental Hormone Actions on the Uterus: Insights from Domestic Animals1

Progesterone is unequivocally required for maternal support of conceptus (embryo/fetus and associated extraembryonic membranes) survival and development. In cyclic sheep, progesterone is paradoxically involved in suppressing and then initiating development of the endometrial luteolytic mechanism. In cyclic and pregnant sheep, progesterone negatively autoregulates progesterone receptor (PR) gene expression in the endometrial luminal (LE) and superficial glandular epithelium (GE). In cyclic sheep, PR loss is closely followed by increases in epithelial estrogen receptor (ERalpha) and then oxytocin receptor (OTR), allowing oxytocin to induce uterine release of luteolytic prostaglandin F2alpha pulses. In pregnant sheep, the conceptus produces interferon tau (IFNtau) that acts on the endometrium to inhibit transcription of the ERalpha gene and thus development of the endometrial luteolytic mechanism. After Day 13 of pregnancy, the endometrial epithelia do not express the PR, whereas the stroma and myometrium remain PR positive. The absence of PR in the endometrial GE is required for onset of differentiated function of the glands during pregnancy. The sequential, overlapping actions of progesterone, IFNtau, placental lactogen (PL), and growth hormone (GH) comprise a hormonal servomechanism that regulates endometrial gland morphogenesis and terminal differentiated function during gestation. In pigs, estrogen, the pregnancy-recognition signal, increases fibroblast growth factor 7 (FGF-7) expression in the endometrial LE that, in turn, stimulates proliferation and differentiated functions of the trophectoderm, which expresses the receptor for FGF-7. Strategic manipulation of these physiological mechanisms may offer therapeutic schemes to improve uterine capacity, conceptus survival, and reproductive health of domestic animals and humans.

Expression of Cyclooxygenase-2 and Granulocyte-Macrophage Colony-Stimulating Factor in the Endometrial Epithelium of the Cow Is Up-Regulated During Early Pregnancy and in Response to Intrauterine Infusions of Interferon-τ1

On the basis of results obtained in vitro, we previously proposed a model in which signals from the conceptus, namely interferon-tau (IFN-tau) and prostaglandin E2, increase the expression of cyclooxygenase (COX)-2 or granulocyte-macrophage colony-stimulating factor (GM-CSF) in immune and nonimmune cells of the bovine endometrium. Two experiments were conducted to verify the validity of this hypothesis in vivo. In experiment 1, the in vivo expression of COX-2 and GM-CSF during early pregnancy was monitored. Uteri from heifers were collected at different days (d) of the estrous cycle and pregnancy (P). In experiment 2, the effects of intrauterine infusions of IFN-tau on the expression of COX-2 and GM-CSF were analyzed. Immunohistochemistry was performed on uterine sections, and image analysis was used to evaluate the staining intensity in the conceptus, the luminal epithelium (LE), and the subepithelial stroma. In experiment 1, staining for COX-2 was maximal between d18P and d24P, both in the LE and in the conceptus, whereas staining for GM-CSF reached a plateau between d18P and d30P in the LE. In experiment 2, in response to IFN-tau, COX-2 was up-regulated in the LE of the ipsilateral horn, whereas GM-CSF was enhanced in both uterine horns. The current report supports the view that the conceptus, through its secretion of IFN-tau, stimulates maternal epithelial expression of COX-2 and GM-CSF during the peri-attachment period in the cow.

Identification of genes in the ovine endometrium regulated by interferon tau independent of signal transducer and activator of transcription 1

Interferon tau (IFNtau), a type I IFN produced by the conceptus trophectoderm, increases many type I IFN-stimulated genes (ISGs) in the ovine uterine endometrial stroma and glandular epithelium (GE) using signal transducer and activator of transcription 1 (STAT1)-dependent pathways. Most ISGs are not induced or increased by IFNtau in the STAT1-negative endometrial luminal epithelium (LE). The objective was to identify genes regulated by IFNtau in a STAT1-independent manner using DNA microarray and human cell lines. The RNA from human 2fTGH and U3A (STAT1 null 2fTGH) cell lines, stimulated for 24 h with nothing or recombinant ovine IFNtau, was profiled using an Affymetrix human genome U95Av2 microarray. In 2fTGH cells, IFNtau increased the expression of 101 genes at least 2-fold, including IFN-inducible 56-kDa protein (IFI56), ISG12 or p27, and guanylate binding protein isoform I (GBP-2). In U3A cells, IFNtau increased expression of 66 genes at least 2-fold, including Wnt7a. Steady-state levels of IFI56, ISG12, GBP-2, and Wnt7a mRNAs increased in the ovine uterine endometrium between d 10 and 16 of pregnancy but not during the estrous cycle. GBP-2 and IFI56 mRNAs were expressed only in endometrial stroma, ISG12 in both LE and GE, and Wnt7a only in LE of the ovine uterus. Intrauterine infusion of ovine IFNtau increased expression of all four genes in the endometrium of cyclic ewes. Therefore, IFNtau does regulate genes independent of STAT1 in the endometrial LE and U3A cells and dependent on STAT1 in the endometrial stroma and 2fTGH cells. These IFNtau -stimulated genes may be important in establishment of uterine receptivity to the embryo and conceptus implantation given their stage-specificity in endometrium across diverse species.

Interferon-tau blocks the stimulatory effect of tumor necrosis factor-alpha on prostaglandin F2alpha synthesis by bovine endometrial stromal cells

Tumor necrosis factor-alpha (TNFalpha) has been shown to be a potent stimulator of prostaglandin (PG) F2alpha synthesis in bovine endometrial stromal cells. The aims of the present study were to determine the effect of interferon-tau (IFNtau) on TNFalpha-stimulated PGF2alpha synthesis and the intracellular mechanisms of TNFalpha and IFNtau action in the stromal cells. When cultured bovine stromal cells were exposed to TNFalpha (0.006-0.6 nM) for 24 h, the production of PGF2alpha and cyclooxygenase (COX)-2 gene expression were stimulated by TNFalpha (0.06-0.6 nM, P < 0.05). Moreover, a specific COX-2 inhibitor (NS-398; 5 nM) blocked the stimulatory effect of TNFalpha on PGF2alpha production (P < 0.05). Although IFNtau (0.03-30 ng/ml) did not stimulate basal PGF2alpha production in the stromal cells, it suppressed TNFalpha action in PGF2alpha production dose dependently (P < 0.05). Moreover, the stimulatory effect of TNFalpha (0.6 nM) on COX-2 gene expression was completely blocked by IFNtau (30 ng/ml; P < 0.05), although the gene expression of COX-2 was not influenced by IFNtau. The overall results indicate that the stimulatory effect of TNFalpha on PGF2alpha production is mediated by the up-regulation of COX-2 gene expression and suggest that one of the mechanisms of the inhibitory effect of IFNtau on luteolysis is the inhibition of TNFalpha action in PGF2alpha production in the stromal cells by the down-regulation of COX-2 gene expression stimulated by TNFalpha.