Interferon-tau, a Type 1 interferon involved in maternal recognition of pregnancy

Response of bovine endometrium to interferon tau in the presence of lipopolysaccharide

We recently demonstrated that conceptus-derived interferon tau (IFNT), responsible for maternal recognition in cattle, acts on the uterus in a dose- and time-dependent manner by upregulating key interferon-stimulated genes (ISGs) in the endometrium. In high producing dairy cows, postpartum uterine infection is a major factor influencing fertility and pregnancy outcome. Lipopolysaccharide (LPS), an endotoxin of Gram-negative bacteria such as Escherichia coli, generates an altered uterine environment by inducing excessive inflammation at the maternal-conceptus interface. Thus, we aimed to investigate whether the endometrial response to IFNT is altered in the presence of LPS. Endometrial explants were isolated from uteri collected at a local abattoir from Holstein Friesian cows (n = 8) during the mid-luteal stage of the estrous cycle, and cultured in RPMI medium for 24 h in 5 % CO2 in humidified air without (control), or with IFNT (100 ng/mL), a single Day 15 conceptus, LPS (1 μg/mL), both IFNT and LPS, or both a Day 15 conceptus and LPS. Incubation with IFNT and a Day 15 conceptus up-regulated (P < 0.05) well-known classical ISGs (ISG15, OAS1, MX1 and MX2) as well as other candidate ISGs (CMPK2, IFI35, TRIM38 and TNFSF10) and down-regulated expression of IL1B in endometrial explants. Incubation with LPS increased (P < 0.05) abundance of NFKB1 (a key transcription factor involved in inflammatory and immune response), TNFA, IL1B and IL6 (pro-inflammatory cytokines), IL10 (anti-inflammatory cytokine), IL8, CXCL1, CXCL3 and CCL2 (chemokines), and, to a lesser extent, classical ISGs in endometrial explants. However, LPS did not alter endometrial response to IFNT, irrespective of IFNT concentration (1, 10 or 100 ng/mL). Results suggest that the expression of ISGs, up-regulated by conceptus-derived IFNT, is not altered in the endometrium in the presence of LPS; however, the increased expression of inflammation-related genes induced by LPS indicate an altered endometrial immune response that may be associated with compromised pregnancy establishment or pregnancy failure.

Placenta Extracellular Vesicles: Messengers Connecting Maternal and Fetal Systems

The placenta operates during gestation as the primary communication organ between the mother and fetus. It is essential for gas, nutrient exchange, and fetal waste transfer. The placenta also produces a wide range of hormones and other factors that influence maternal physiology, including survival and activity of the corpus luteum of the ovary, but the means whereby the placenta shapes fetal development remain less clear, although the fetal brain is thought to be dependent upon the placenta for factors that play roles in its early differentiation and growth, giving rise to the term "placenta-brain axis". Placental hormones transit via the maternal and fetal vasculature, but smaller placental molecules require protection from fetal and maternal metabolism. Such biomolecules include small RNA, mRNA, peptides, lipids, and catecholamines that include serotonin and dopamine. These compounds presumably shuttle to maternal and fetal systems via protective extracellular vesicles (EVs). Placental EVs (pEVs) and their components, in particular miRNA (miRs), are known to play important roles in regulating maternal systems, such as immune, cardiovascular, and reproductive functions. A scant amount is known about how pEVs affect fetal cells and tissues. The composition of pEVs can be influenced by gestational diseases. This review will provide critical insight into the roles of pEVs as the intermediary link between maternal and fetal systems, the impact of maternal pathologies on pEV cargo contents, and how an understanding of biomolecular changes within pEVs in health and disease might be utilized to design early diagnostic and mitigation strategies to prevent gestational diseases and later offspring disorders.

Expression of Interferon Epsilon in Mucosal Epithelium is Regulated by Elf3

Interferon epsilon (IFNε) is a unique type I interferon (IFN) that shows distinct constitutive expression in reproductive tract epithelium. Understanding how IFNε expression is regulated is critical for the mechanism of action in protecting the mucosa from infection. Combined computational and experimental investigation of the promoter of IFNε predicted transcription factor binding sites for the ETS family of transcription factors. We demonstrate here that Ifnε is regulated by Elf3, an epithelial restricted member of the ETS family. It is co-expressed with IFNε at the epithelium of uterus, lung and intestine, and we focused on regulation of IFNε expression in the uterus. Promoter reporter studies demonstrated that Elf3 was a strong driver of Ifnε expression; knockdown of Elf3 reduced expression levels of IFNε; Elf3 regulated Ifnε expression and chromatin immunoprecipitation (ChIP) confirmed the direct binding of Elf3 to the IFNε promoter. These data show that Elf3 is important in regulating protective mucosal immunity by driving constitutive expression of IFNε to protect mucosal tissues from infection in at least three organ systems.

Trophoblastic signals facilitate endometrial interferon response and lipid metabolism, ensuring normal decidualization

The decidua plays a crucial role in providing structural and trophic support to the developing conceptus before placentation. Following embryo attachment, embryonic components intimately interact with the decidual tissue. While evidence indicates the participation of embryo-derived factors in crosstalk with the uterus, the extent of their impact on post-implantation decidual development requires further investigation. Here, we utilize transgenic mouse models to selectively eliminate primary trophoblast giant cells (pTGCs), the embryonic cells that interface with maternal tissue at the forefront. pTGC ablation impairs decidualization and compromises decidual interferon response and lipid metabolism. Mechanistically, pTGCs release factors such as interferon kappa (IFNK) to strengthen the decidual interferon response and lipoprotein lipase (LPL) to enhance lipid accumulation within the decidua, thereby promoting decidualization. This study presents genetic and metabolomic evidence reinforcing the proactive role of pTGC-derived factors in mobilizing maternal resources to strengthen decidualization, facilitating the normal progression of early pregnancy.

Interferon-Tau in Maternal Peripheral Blood and Its Relationship with Progesterone and Pregnancy-Associated Glycoproteins in the Early Phases of Gestation in Water Buffalo

The aim of this study was to investigate the interferon tau (IFNt) concentration in the peripheral maternal blood during the early phase of pregnancy in buffalo cows and improve the knowledge on the physiological importance of circulating IFNt, evaluating the possible interaction with pregnancy-associated glycoproteins (PAGs) and progesterone (P4). Blood samples were taken from buffalo cows on day 0 (day of AI), 7, 14, 18, 28, and 40 post insemination for the IFNt, PAG, and P4 analysis and to determine the IFNt mRNA expression. The animals were categorized ex post into Pregnant, Non-pregnant and Embryo mortality groups. The interferon value was influenced by group (p = 0.003), being always higher in pregnant buffalo cows than in non-pregnant ones, while the embryo mortality group showed intermediate values between those for pregnant and non-pregnant animals. The mRNA expression of IFNt was not influenced by groups or any time points. The regression analysis that included IFNt as the independent variable showed that PAGs, from day 18 (p < 0.01), and P4, from day 28 (p < 0.05), were positively associated with IFNt values. The close associations among IFNt, PAGs and P4 demonstrate that all three molecules work together for fetal-placental well-being and pregnancy support. Unfortunately, the great individual variability in circulating IFNt makes this analysis unsuitable for early pregnancy diagnosis.

Single-cell transcriptional landscapes of bovine peri-implantation development

Supporting healthy pregnancy outcomes requires a comprehensive understanding of the molecular and cellular programs of peri-implantation development, when most pregnancy failure occurs. Here, we present single-cell transcriptomes of bovine peri-implantation embryo development at day 12, 14, 16, and 18 post-fertilization. We defined the cellular composition and gene expression of embryonic disc, hypoblast, and trophoblast lineages in bovine peri-implantation embryos, and identified markers and pathway signaling that represent distinct stages of bovine peri-implantation lineages; the expression of selected markers was validated in peri-implantation embryos. Using detailed time-course transcriptomic analyses, we revealed a previously unrecognized primitive trophoblast cell lineage. We also characterized conserved and divergence peri-implantation lineage programs between bovine and other mammalian species. Finally, we established cell-cell communication signaling underlies embryonic and extraembryonic cell interaction to ensure proper early development. These data provide foundational information to discover essential biological signaling underpinning bovine peri-implantation development.

Interferon-tau protects bovine endometrial epithelial cells against inflammatory injury by regulating the PI3K/AKT/β-catenin/FoxO1 signaling axis

Endometritis is one of the most common causes of infertility in dairy cows, and is histopathologically characterized by inflammation and damage of endometrial epithelium. Interferon-tau (IFN-τ) is a novel type I interferon secreted by ruminant trophoblast cells with low cytotoxicity even at high doses. Previous studies suggested that IFN-τ plays an important role in inflammation. However, the mechanisms whereby IFN-τ may modulate the inflammatory responses in the bovine endometrium are unknown. In the present study, primary bovine endometrial epithelial cells (BEEC) isolated from fresh and healthy uterine horns were used for in vitro studies. The integrity of BEEC was assessed by immunofluorescence staining for cytokeratin 18 (CK-18, a known epithelial marker). For the experiments, BEEC were stimulated with different concentrations of lipopolysaccharide (LPS; 0-20 µg/mL) for different times (0-24 h). Cell viability and apoptosis were assessed via CCK-8 and flow cytometry. In a preliminary study, we observed that compared with the control group without LPS, 10 µg/mL of LPS stimulation for 24 h induced apoptosis. In a subsequent study, 20 or 40 ng/mL of IFN-τ alleviated LPS-induced apoptosis. Relative to the LPS group, western blotting further revealed that IFN-τ inhibited the protein abundance of TLR4 and phosphorylated (p-) p65 (p-p65) and Bax/Bcl-2 ratio, suggesting that IFN-τ can protect BEEC against inflammatory injury. Furthermore, the protein abundance of p-phosphoinositide 3-kinase (p-PI3K), p-protein kinase B (p-AKT), p-glycogen synthase kinase-3β (p-GSK3β), β-catenin, and p-forkhead box O1 (p-FoxO1) was lower in the LPS group, whereas IFN-τ upregulated their abundance. The use of LY294002, a specific inhibitor of PI3K/AKT, attenuated the upregulation of p-PI3K, p-AKT p-GSK3β, β-catenin, and p-FoxO1 induced by IFN-τ, and also blocked the downregulation of TLR4, p-p65, and Bax/Bcl-2 ratio. This suggested that the inhibition of TLR4 signaling by IFN-τ was mediated by the PI3K/AKT pathway. Furthermore, compared with the LPS group, the β-catenin agonist SB216763 led to greater p-FoxO1 and lower p-p65 and cell apoptosis. In contrast, knockdown of β-catenin using small interfering RNA had the opposite effects. To explore the role of FoxO1 on the inhibition of TLR4 by IFN-τ, we employed LY294002 to inhibit the PI3K/AKT while FoxO1 was knocked down. Results revealed that the knockdown of FoxO1 blocked the upregulation of TLR4 and p-p65 induced by LY294002, and enhanced the inhibition of IFN-τ on TLR4, p-p65, and cell apoptosis. Overall, these findings confirmed that IFN-τ can protect endometrial epithelial cells against inflammatory injury via suppressing TLR4 activation through the regulation of the PI3K/AKT/β-catenin/FoxO1 axis. These represent new insights into the molecular mechanisms underlying the anti-inflammatory function of IFN-τ in BEEC, and also provide a theoretical basis for further studies on the in vivo application of IFN-τ to help prevent negative effects of endometritis.

Proteomic Approaches to Unravel the Molecular Dynamics of Early Pregnancy in Farm Animals: An In-Depth Review

Infertility is a major problem in farm animals, which has a negative economic effect on farm industries. Infertility can be defined as the inability of animals to achieve a successful pregnancy. Early pregnancy is crucial to establish a successful pregnancy, and it is reported that 70-80% and 20-30% of total embryonic loss occur in cattle and pigs, respectively, during the first month of pregnancy. The advanced high-throughput proteomics techniques provide valuable tools for in-depth understanding of the implantation process in farm animals. In the present review, our goal was to compile, assess, and integrate the latest proteomic research on farm animals, specifically focused on female reproduction, which involves endometrial tissues, uterine fluids, oviductal fluids, and microRNAs. The series of studies has provided in-depth insights into the events of the implantation process by unfolding the molecular landscape of the uterine tract. The discussed data are related to pregnant vs. non-pregnant animals, pregnancy vs. oestrous cycle, different days of the early pregnancy phase, and animals with uterine infections affecting reproduction health. Some of the studies have utilized non-invasive methods and in vitro models to decipher the molecular events of embryo-maternal interaction. The proteomics data are valuable sources for discovering biomarkers for infertility in ruminants and new regulatory pathways governing embryo-uterine interaction, endometrium receptivity, and embryonic development. Here, we envisage that the identified protein signatures can serve as potential therapeutic targets and biomarkers to develop new therapeutics against pregnancy diseases.

The effect of dietary omega-3 fatty acid supplementation on fetal growth, piglet birth weight and plasma fatty acid concentrations, using docosahexaenoic acid in early gestation in sows

The objective of the study was to test the effect of the omega-3 fatty acid docosahexaenoic acid (DHA) on fetal and placental development as well as the birth weight of piglets. A total of 238 multiparous sows were allocated to either a control diet group or a DHA diet group with an omega-6 to omega-3 ratio of 9.8 and 2.4, respectively, from mating to day 43 of gestation. A blood sample was collected and back fat thickness was measured prior to mating, on days 14, 42 and 112 of gestation. On day 43 of gestation, 14 sows were slaughtered and measurements of fetuses and placentas were taken. Piglets in some litters were weighed individually at farrowing. Dietary treatment did not affect fetal characteristics and back fat thickness (P > 0.05). Dietary treatment increased the plasma concentrations of total omega-3 fatty acids in sows (P < 0.05). Sows fed the DHA diet had a shorter gestation length compared to the control sows (P < 0.05), but the number of born piglets was not affected (P > 0.05). The average piglet birth weight and the within-litter variation in birthweight were unaffected by dietary DHA (P > 0.05), however, sows fed DHA diet had fewer piglets under 800 g at birth compared to control sows (P < 0.05). In conclusion, addition of DHA decreased the dietary ratio of omega-6 to omega-3 fatty acids, increased plasma n-3 fatty acid concentrations in sows and decreased the number of piglets weighing under 800 g at birth.

β-Hydroxybutyrate Effects on Bovine Caruncular Epithelial Cells: A Model for Investigating the Peri-Implantation Period Disruption in Ketotic Dairy Cows

Ketosis is a metabolic disorder arising from a negative energy balance (NEB). It is characterized by high β-Hydroxybutyrate (BHBA) blood levels and associated with reduced fertility in dairy cows. To investigate the impact of BHBA on bovine caruncular epithelial cells (BCEC) in vitro, these cells were stimulated with different concentrations of BHBA. Cell metabolism and motility were examined using an MTT assay and Live-cell imaging. RT-qPCR was used to examine mRNA expressions of TNF, IL6, RELA, prostaglandin E2 synthase (PTGES2) and receptor (PTGER2) as well as integrin subunits ITGAV, ITGA6, ITGB1 and ITGB3. Stimulation with 1.8 and 2.4 mM of BHBA negatively affected cell metabolism and motility. TNF showed increased mRNA expression related to rising BHBA concentrations. IL6, RELA, ITGAV, ITGA6, ITGB1 and ITGB3 as well as PTGER2 showed no changes in mRNA expression. Stimulation with 0.6 and 1.2 mM of BHBA significantly increased the mRNA expression of PTGES2. This does not indicate a negative effect on reproductive performance because low BHBA concentrations are found in steady-state conditions. However, the results of the study show negative effects of high BHBA concentrations on the function of BCECs as well as an inflammatory response. This could negatively affect the feto-maternal communication during the peri-implantation period in ketotic dairy cows.

Single-cell transcriptional landscapes of bovine peri-implantation development

Supporting healthy pregnancy outcomes requires a comprehensive understanding of the cellular hierarchy and underlying molecular mechanisms during peri-implantation development. Here, we present a single-cell transcriptome-wide view of the bovine peri-implantation embryo development at day 12, 14, 16 and 18, when most of the pregnancy failure occurs in cattle. We defined the development and dynamic progression of cellular composition and gene expression of embryonic disc, hypoblast, and trophoblast lineages during bovine peri-implantation development. Notably, the comprehensive transcriptomic mapping of trophoblast development revealed a previously unrecognized primitive trophoblast cell lineage that is responsible for pregnancy maintenance in bovine prior to the time when binucleate cells emerge. We analyzed novel markers for the cell lineage development during bovine early development. We also identified cell-cell communication signaling underling embryonic and extraembryonic cell interaction to ensure proper early development. Collectively, our work provides foundational information to discover essential biological pathways underpinning bovine peri-implantation development and the molecular causes of the early pregnancy failure during this critical period.

Significance Statement

Peri-implantation development is essential for successful reproduction in mammalian species, and cattle have a unique process of elongation that proceeds for two weeks prior to implantation and represents a period when many pregnancies fail. Although the bovine embryo elongation has been studied histologically, the essential cellular and molecular factors governing lineage differentiation remain unexplored. This study profiled the transcriptome of single cells in the bovine peri-implantation development throughout day 12, 14, 16, and 18, and identified peri-implantation stage-related features of cell lineages. The candidate regulatory genes, factors, pathways and embryonic and extraembryonic cell interactions were also prioritized to ensure proper embryo elongation in cattle.

Integrating Analysis to Identify Differential circRNAs Involved in Goat Endometrial Receptivity

Endometrial receptivity is one of the main factors underlying a successful pregnancy, with reports substantiating the fact that suboptimal endometrial receptivity accounts for two-thirds of early implantation event failures. The association between circRNAs and endometrial receptivity in the goat remains unclear. This study aims to identify potential circRNAs and regulatory mechanisms related to goat endometrial receptivity. Therefore, the endometrial samples on day 16 of pregnancy and day 16 of the estrous cycle were analyzed using high-throughput RNA-seq and bioinformatics. The results show that 4666 circRNAs were identified, including 7 downregulated and 11 upregulated differentially expressed circRNAs (DE-circRNAs). Back-splicing and RNase R resistance verified the identified circRNAs. We predicted the competing endogenous RNA (ceRNA) regulatory mechanism and potential target genes of DE-circRNAs. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses of these predicted target genes suggest that DE-circRNAs were significantly involved in establishing endometrial receptivity. Furthermore, Sanger sequencing, qPCR, correlation analysis and Fluorescence in Situ Hybridization (FISH) show that circ_MYRF derived from the host gene myelin regulatory factor (MYRF) might regulate the expression of interferon stimulating gene 15 (ISG15), thereby promoting the formation of endometrial receptivity. These novel findings may contribute to a better understanding of the molecular mechanisms regulating endometrial receptivity and promoting the maternal recognition of pregnancy (MRP).

Improvement of Fertilization Capacity and Developmental Ability of Vitrified Bovine Oocytes by JUNO mRNA Microinjection and Cholesterol-Loaded Methyl-β-Cyclodextrin Treatment

Vitrification of oocytes is crucial for embryo biotechnologies, germplasm cryopreservation of endangered and excellent female animals, and the fertility of humans. However, vitrification significantly impairs the fertilization ability of oocytes, which significantly limits its widely used application. JUNO protein, a receptor for Izumo1, is involved in sperm-oocyte fusion and is an indispensable protein for mammalian fertilization, and its abundance is susceptible to vitrification. However, it is still unclear how vitrification reduces the fertilization capacity of bovine oocytes by affecting JUNO protein. This study was designed to investigate the effect of vitrification on the abundance and post-translational modifications of JUNO protein in bovine oocytes. Our results showed that vitrification did not alter the amino acid sequence of JUNO protein in bovine oocytes. Furthermore, the liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis results showed that vitrification significantly reduced the number and changed the location of disulfide bonds, and increased the number of both phosphorylation and glycosylation sites of JUNO protein in bovine oocytes. Finally, the fertilization capacity and development ability of vitrified oocytes treated with 200 pg JUNO mRNA microinjection and cholesterol-loaded methyl-β-cyclodextrin (CLC/MβCD) were similar to those of fresh oocytes. In conclusion, our results showed that vitrification of bovine oocytes did not alter the protein sequence of JUNO, but induced post-translational modifications and changed protein abundance. Moreover, the fertilization and development ability of vitrified bovine oocytes were improved by the combination treatment of JUNO mRNA microinjection and CLC/MβCD.

Interferon Tau (IFNt) and Interferon-Stimulated Genes (ISGs) Expression in Peripheral Blood Leukocytes and Correlation with Circulating Pregnancy-Associated Glycoproteins (PAGs) during Peri-Implantation and Early Pregnancy in Buffalo Cows

The objective of this study was to analyze interferon-stimulated genes (ISGs) and interferon tau (IFNt) gene expression in peripheral blood leukocytes during the peri-implantation period and until 40 days of pregnancy in buffalo cows. Relationships were also examined between the expression of ISGs and IFNt and pregnancy-associated glycoproteins (PAGs) peripheral plasma concentration. Buffalo cows were synchronized and artificially inseminated (d 0). Blood samples were collected on days 0, 18, 28 and 40 after artificial insemination (AI) for peripheral blood mononuclear cells (PBMCs) and polymorphonuclear leukocytes (PMNs) isolation and PAGs radioimmunoassay analysis. The study was carried out on 21 buffalo cows divided ex post into Pregnant (n = 12) and Non-pregnant (n = 9) groups. Steady state levels of OAS1, MX2, ISG15 and IFNt mRNA were measured by RT-qPCR and their estimated marginal means (p < 0.01 for all) were higher in pregnant than non-pregnant buffaloes, both in PBMCs and PMNs. In PBMCs, pairwise comparisons showed that OAS1 and MX2 expressions differed between pregnant and non-pregnant buffaloes on all the days of observation (p < 0.001), while significant differences in ISG15 and IFNt started from day 28 post-AI (p < 0.05). In PMNs, ISG15 expression differed between groups only at days 18 and 28 (p < 0.001), while comparisons were always significant for IFNt (p < 0.05). The expression of all genes, except ISG15 as determined in PMNs, was positively associated with PAGs plasma concentrations (p < 0.05). This work showed a significant increase in ISGs and IFNt expressions in PBMCs and PMNs in buffalo during the peri-implantation period and early pregnancy, and their correlation with PAGs plasma concentration.

Unrevealing functional candidate genes for bovine fertility through RNA sequencing meta-analysis and regulatory elements networks of co-expressed genes and lncRNAs

The high genetic heterogeneity and environmental effects of subfertility in livestock species make the elucidation of the genetic mechanisms associated with reproductive efficiency a difficult task. Network and co-expression network meta-analyses were applied alongside genetic variant calling and long non-coding RNA (lncRNA) characterization to identify functionally relevant target genes and regulatory subnetworks associated with fertility in dairy cattle. In total, 505 lncRNAs (441 previously annotated in the bovine reference genome ARS-UCD 1.2 and 64 novel lncRNAs) were identified. Seven differentially expressed genes between high-fertile (HF) and sub-fertile (SF) Holstein cows were identified in the network meta-analysis (CA5A, ENSBTAG00000051149, ENSBTAG00000003272, DEFB7, DIO2, TRPV3, and COL4A4). Additionally, seven functional candidate differentially co-expressed (DcoExp) modules with a differential regulatory pattern (|z-score|>2) were identified between HF and SF cows. The functional candidate genes and DcoExp modules identified were associated with fertility relevant processes such as the regulation of embryonic implantation and proliferation, interaction and molecule transfer between the fetus and the cow, and the immune system. These results help to better understand the genetic mechanisms associated with reproductive efficiency in dairy cattle through the identification of potential biomarkers and genetic variants associated with differentially expressed regulatory gene and lncRNAs regulatory element networks.

Interferon-Tau regulates a plethora of functions in the corpus luteum

The corpus luteum (CL) plays a vital role in regulating the reproductive cycle, fertility, and in maintaining pregnancy. Interferon-tau (IFNT) is the maternal recognition of a pregnancy signal in domestic ruminants; its uterine, paracrine actions, which extend the CL lifespan, are widely established. However, considerable evidence also suggests a direct, endocrine role for IFNT. The purpose of this review is to highlight the importance of IFNT in CL maintenance, acting directly and in a cell-specific manner. A transcriptomic study revealed a distinct molecular profile of IFNT-exposed day 18, pregnant bovine CL, compared to the non-pregnant gland. A substantial fraction of the differentially expressed genes was downregulated, many of which are known to be elevated by prostaglandin F2A (PGF2A). In vitro, IFNT was found to mimic changes observed in the luteal transcriptome of early pregnancy. Key luteolytic genes such as endothelin-1 (EDN1), transforming growth factor-B1 (TGFB1), thrombospondins (THBSs) 1&2 and serpine-1 (SERPINE1) were downregulated in luteal endothelial cells. Luteal steroidogenic large cells (LGCs) were also found to be a target for the antilutelotytic actions of IFNT. IFNT-treated LGCs showed a significant reduction in the expression of the proapoptotic, antiangiogenic THBS1&2, as well as TGFBR1 and 2. Furthermore, IFNT was shown to be a potent survival factor for luteal cells in vivo and in vitro, activating diverse pathways to promote cell survival while suppressing cell death signals. Pentraxin 3 (PTX3), robustly upregulated by IFNT in various luteal cell types, mediated many of the prosurvival effects of IFNT in LGCs. A novel reciprocal inhibitory crosstalk between PTX3 and THBS1 lends further support to their respective survival and apoptotic actions in the CL. Even though IFNT did not directly regulate progesterone synthesis, it could maintain its concentrations, by increasing luteal cell survival and by supporting vascular stabilization. The direct effects of IFNT in the CL, enhancing cell survival and vasculature stabilization while curbing luteolytic activities, may constitute an important complementary branch leading to the extension of the luteal lifespan during early pregnancy.

Transcriptomic analysis shows that surgical treatment is likely to influence the endometrial receptivity of patients with stage III/IV endometriosis

BACKGROUND

Endometriosis negatively affects fertility, and it is a common disease in assisted reproductive practice. Surgical removal of endometriotic lesions is widely carried out to relieve symptoms and promote fertility. But it is not intensively investigated what changes in the secretory eutopic endometrium of patients with endometriosis after surgery.

METHODS

Eighteen patients with stage III/IV endometriosis were included in the study, and they were divided into the untreated group and the treated group (6 vs. 12). Basic clinical data were compared, and transcriptomic data of the secretory eutopic endometrium were analyzed with DESeq2, Cytoscape, ClueGO, CluePedia, and Gene Set Enrichment Analysis (GSEA). CIBERSORT was used to calculate the relative abundance of 22 immune cells in the samples.

RESULTS

We determined 346 differentially expressed genes (DEGs) using DESeq2. These DEGs were used to enrich seven Gene Ontology terms including three associated with immune processes and one correlated to prostaglandin using ClueGO and CluePedia. GSEA enriched 28 Gene Ontology terms in the treated group mainly associated with immune and blood pressure regulation process. Compared to the untreated group, the relative abundance of resting CD4+ memory T cells [0.218 (0.069, 0.334) vs. 0.332 (0.181, 0.429), P = 0.022] and the even less abundant memory B cells [0.001 (0.000, 0.083) vs. 0.033 (0.007, 0.057), P = 0.049] are significantly decreased in the treated group.

CONCLUSION

Surgical treatment of stage III/IV endometriosis influences some genes and biological processes related to endometrial receptivity, but more evidence is needed.

Transcriptomic Analysis of STAT1/3 in the Goat Endometrium During Embryo Implantation

Interferon tau (IFNT), a pregnancy recognition signal in ruminants, promotes the establishment of embryo implantation by inducing the expression of interferon-stimulated genes (ISGs) via the Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway. However, the precise regulatory mechanism of IFNT in goat embryo implantation remains largely unknown. In this study, we performed RNA sequencing of goat endometrial epithelial cells (gEECs) with or without 20 ng/mL IFNT treatment. Differential comparison showed that there were 442 upregulated differentially expressed genes (DEGs) and 510 downregulated DEGs. Bioinformatic analyses revealed that DEGs were significantly enriched in immune-related functions or pathways. The qRT-PCR validation results showed that the expression levels of STAT family members (STAT1, STAT2, and STAT3) were significantly upregulated in gEECs after IFNT treatment, which is in agreement with the RNA-seq data. Meanwhile, the protein levels of p-STAT1 and p-STAT3 increased significantly in gEECs after 6 and 24 h of IFNT treatment, respectively. Further in vivo experiments also confirmed that both mRNA and protein phosphorylation levels of STAT1 and STAT3 in the uterus on day 18 of pregnancy (P18) were significantly increased compared to those on day 5 (P5) and day 15 of pregnancy (P15). On P5, STAT1 and STAT3 proteins were primarily located in the uterine luminal epithelium (LE) and glandular epithelium (GE), and were also detected in the stromal cells. The intense immunostaining of STAT1 and STAT3 proteins were decreased on P15 and then increased on P18, especially in the superficial GE and subepithelial stromal cells. Moreover, p-STAT1 and p-STAT3 were highly expressed in the deep GE on P18. Collectively, these results highlight the role of IFNT in regulating endometrial receptivity in gEECs and uncover the temporal and spatial changes in the expression of STAT1/3 during embryo implantation in the goat endometrium.

Downregulated luteolytic pathways in the transcriptome of early pregnancy bovine corpus luteum are mimicked by interferon-tau in vitro

Background

Maintenance of the corpus luteum (CL) beyond the time of luteolysis is essential for establishing pregnancy. Identifying the distinct features of early pregnancy CL remains unresolved, hence we analyzed here the transcriptome of CL on day 18 pregnant (P) and non-pregnant (NP) cows using RNA-Seq. CL of P cows expressed ISGs, verifying exposure to the pregnancy recognition signal, interferon-tau (IFNT), whereas the CL of NP cows had elevated luteal progesterone levels, implying that luteolysis had not yet commenced.

Results

The DEGs, IPA, and metascape canonical pathways, along with GSEA analysis, differed markedly in the CL of P cows from those of NP cows, at the same day of the cycle. Both metascape and IPA identified similar significantly enriched pathways such as interferon alpha/beta, sonic hedgehog pathway, TNFA, EDN1, TGFB1, and PDGF. However, type-1 interferon and sonic hedgehog pathways were positively enriched whereas most of the enriched pathways were downregulated in the P compared to NP samples. Thirty-four % of these pathways are known to be elevated by PGF2A during luteolysis. Notably, selective DEGs in luteinized granulosa cells were modulated by IFNT in vitro in a similar manner to their regulation in the CL of P cows.

Conclusion

This study unraveled the unique transcriptomic signature of the IFNT-exposed, early pregnancy CL, highlighting the abundance of downregulated pathways known to be otherwise induced during luteolysis. These and IFNT-regulated in vitro pregnancy-specific DEGs suggest that IFNT contributes to the characteristics and maintenance of early pregnancy CL.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-07747-3.

Analysis of Transcripts of Uncertain Coding Potential Using RNA Sequencing During the Preattachment Phase in Goat Endometrium

Transcripts of uncertain coding potential (TUCP) are part of long noncoding RNAs, which include short open reading frames and could be translated into small peptides. In recent years, a growing number of TUCPs has been implicated in multiple biological activities, such as embryogenesis and transcriptional regulation. However, the abundance of TUCPs and their roles in goat endometrium during pregnancy recognition (day 16) remain undocumented. In this study, bioinformatics analyses were conducted to identify the differentially expressed (DE) TUCPs between pregnant animals and corresponding nonpregnant controls. A total of 5551 TUCPs were identified; 114 TUCPs were DE in goat endometrium, of which 74 TUCPs were upregulated in pregnant endometrium, whereas 40 TUCPs were downregulated. The related genes of TUCP were predicted by using coexpression and colocalization methods. In summary, 419 genes were predicted by colocalization, and 9464 genes were predicted by coexpression. The kyoto encyclopedia of genes and genomes (KEGG) and gene ontology (GO) analysis showed that TUCPs, which are highly expressed in pregnant endometrium, were mainly associated with endometrial remodeling, nutrient synthesis, and transportation. However, TUCPs that were lowly expressed in pregnant endometrium were mainly associated with immune tolerance, which is necessary for the protection and development of the embryo in the uterus. These findings may be used for the comparative analysis of TUCP transcripts in endometrium and assist in the selection of applicable candidate genes associated with embryo implantation for further functional analyses.

The role of maternal preconception vitamin D status in human offspring sex ratio

Evolutionary theory suggests that some animal species may experience shifts in their offspring sex ratio in response to maternal health and environmental conditions, and in some unfavorable conditions, females may be less likely to bear sons. Experimental data in both animals and humans indicate that maternal inflammation may disproportionately impact the viability of male conceptuses; however, it is unknown whether other factors associated with both pregnancy and inflammation, such as vitamin D status, are associated with the offspring sex ratio. Here, we show that among 1,228 women attempting pregnancy, preconception 25-hydroxyvitamin D concentrations are positively associated with the live birth of a male infant, with notably stronger associations among women with elevated high sensitivity C-reactive protein, a marker of systemic low-grade inflammation. Our findings suggest that vitamin D may mitigate maternal inflammation that would otherwise be detrimental to the implantation or survival of male conceptuses in utero.

Interferon-τ regulates the expression and function of bovine leukocyte antigen by downregulating bta-miR-204

IFN-τ is a pregnancy recognition factor that regulates embryo implantation in ruminants. IFN-τ has been suggested to be involved in the expression of microRNA (miRNA/miR) and bovine leukocyte antigen (BoLA), which is an analog of the human major histocompatibility complex class I. However, little is known about whether the miRNAs are involved in the expression of BoLA in ruminants. The present study firstly verified that bta-miR-204 was downregulated and that BoLA was upregulated in the uterine tissues of dairy cows during early pregnancy. Subsequently, luciferase reporter assays, reverse transcription-quantitative PCR and western blot analysis were used to validate BoLA as the target gene of bta-miR-204. Moreover, BoLA was markedly upregulated and bta-miR-204 was downregulated in bovine endometrial epithelial cells (bEECs) treated with IFN-τ. In addition, the results indicated that when the expression level of BoLA was increased by IFN-τ, the expression level of programmed death-ligand 1 (PD-L1) and programmed death-ligand 2 (PD-L2) was also increased. Furthermore, when BoLA was silenced in bEECs by small interfering RNA, the expression of PD-L1 and PD-L2 was not affected by IFN-τ. The expression level of PD-L1 and PD-L2 was also increased in the uterine tissues of pregnant dairy cattle. In conclusion, IFN-τ may function by suppressing the expression of bta-miR-204 to increase the expression of BoLA during the embryo implantation period in cattle. IFN-τ may induce PD-L1 and PD-L2 transcription by regulating BoLA, which may influence the T cell immune response, thereby regulating pregnant cattle immunization.

Local action of cytokines and immune cells in communication between the conceptus and uterus during the critical period of early embryo development, attachment and implantation - Implications for embryo survival in cattle: A review

Early embryo development, implantation and pregnancy involve a complex dialogue between the embryo and mother. In cattle this dialogue starts as early as days 3-4 when the embryo is still in the oviduct, and it continues to implantation. Immunological processes involving cytokines, mast cells and macrophages form an important part of this dialogue. Amongst the cytokines, interleukin-6 (Il-6) and leukemia inhibitory factor (LIF) are secreted by both the embryo and uterine endometrium and form part of an ongoing and reciprocating dialogue. Mast cells and macrophages populate the uterine endometrium during embryo development and are involved in achieving the correct balance between inflammatory and anti-inflammatory reactions at the uterus that are associated with embryo attachment and implantation. Embryo loss is the major cause of reproductive wastage in cattle, and livestock generally. A deeper understanding of immunological processes during early embryo development will help to achieve the next step change in the efficiency of natural and assisted breeding.

Transforming growth factor-β superfamily and interferon-τ in ovarian function and embryo development in female cattle: review of biology and application

Survival of the embryo and establishment of a pregnancy is a critical period in the reproductive function of female cattle. This review examines how the transforming growth factor-β (TGFB) superfamily (i.e. bone morphogenetic protein (BMP) 15, growth differentiation factor (GDF) 9, anti-Müllerian hormone (AMH)) and interferon-τ (IFNT) affect ovarian function and embryo development. The oocyte in a primary follicle secretes BMP15 and GDF9, which, together, organise the surrounding granulosa and theca cells into the oocyte-cumulus-follicle complex. At the same time, the granulosa secretes AMH, which affects the oocyte. This autocrine-paracrine dialogue between the oocyte and somatic cells continues throughout follicle development and is fundamental in establishing the fertilisation potential and embryo developmental competency of oocytes. The early bovine embryo secretes IFNT, which acts at the uterine endometrium, corpus luteum and blood leucocytes. IFNT is involved in the maternal recognition of pregnancy and immunomodulation to prevent rejection of the embryo, and supports progesterone secretion. Manipulation of BMP15, GDF9, AMH and IFNT in both invivo and invitro studies has confirmed their importance in reproductive function in female cattle. This review makes the case that a deeper understanding of the biology of BMP15, GDF9, AMH and IFNT will lead to new strategies to increase embryo survival and improve fertility in cattle. The enhancement of oocyte quality, early embryo development and implantation is considered necessary for the next step change in the efficiency of natural and assisted reproduction in cattle.

Endometrial extracellular matrix rigidity and IFNτ ensure the establishment of early pregnancy through activation of YAP

Background

In mammals, early pregnancy is a critical vulnerable period during which complications may arise, including pregnancy failure. Establishment of a maternal endometrial acceptance phenotype is a prerequisite for semiheterogeneous embryo implantation, comprising the rate‐limiting step of early pregnancy.

Methods

Confocal fluorescence, immunohistochemistry and western blot for nuclear and cytoplasmic protein were used to examine the activation of yes‐associated protein (YAP) in uterine tissue and primary endometrial cells. The target binding between miR16a and YAP was verified by dual‐luciferase reporter gene assay. The mouse pregnancy model and pseudopregnancy model were used to investigate the role of YAP in the maternal uterus during early pregnancy in vivo.

Results

We showed that YAP translocates into the nucleus in the endometrium of cattle and mice during early pregnancy. Mechanistically, YAP acts as a mediator of ECM rigidity and cell density, which requires the actomyosin cytoskeleton and is partially dependent on the Hippo pathway. Furthermore, we found that the soluble factor IFNτ, which is a ruminant pregnancy recognition factor, also induced activation of YAP by reducing the expression of miR‐16a.

Conclusions

This study revealed that activation of YAP is necessary for early pregnancy in bovines because it induced cell proliferation and established an immunosuppressive local environment that allowed conceptus implantation into the uterine epithelium.

Effects of dietary n-3-PUFA supplementation, post-insemination plane of nutrition and pregnancy status on the endometrial transcriptome of beef heifers

Supplementation of cattle diets with n-3-polyunsaturated fatty acids (PUFA) can improve reproductive efficiency. Conversely, short-term fluctuations in feed supply can impact pregnancy establishment. The objectives of this study were to examine the effects of (1) dietary supplementation with n-3-PUFA and (2) post-insemination plane of nutrition on the endometrial transcriptome. Beef crossbred heifers were offered concentrate based diets fortified with n-3-PUFA (PUFA; n = 32) or not (CONT; n = 28) for 30 days prior to breeding at a synchronised oestrous. Following artificial insemination, heifers were allocated within treatment to either a high or low plane of nutrition. Heifers were maintained on these diets for 16 days following which endometrial tissue was harvested at slaughter for subsequent RNAseq analysis. The influence of pregnancy status on the endomentrial transcriptome, within each dietary treatment group, was also examined. Post-insemination diet affected (P < 0.05) the endometrial transcriptome. Specifically, within n-3-PUFA-supplemented heifers, genes involved in embryonic development and mTOR signalling pathways, important in pregnancy establishment, were identified as differentially expressed. Results indicate that dietary supplementation of cattle diets with n-3-PUFA may have a positive effect on the expression of key fertility-related genes and pathways, during the critical window of maternal recognition of pregnancy, particularly where animals are underfed.

Implantation associated changes in expression profile of indoleamine-2, 3-dioxygenase 1, Th1-Th2 cytokines and interferon-stimulated genes on neutrophils and peripheral blood mononuclear cells of crossbred cows

Effective bidirectional communication between the embryo and dam improves the reproductive efficiency of dairy cows. Possible role of immunosuppressive indolamine-2, 3-dioxygenase 1 (IDO1) enzyme in the regulation of maternal systemic cytokine balance/shift during early pregnancy establishment along with various interferon-stimulated genes (ISGs) expression in neutrophils and peripheral blood mononuclear cell (PBMCs) were investigated in crossbred cows. Blood was collected on days 0 i.e. day of Artificial Insemination (AI), 10, 18 and 36 post-AI followed by isolation of neutrophils and PBMCs for gene expression study of IDO1, anti-inflammatory cytokines (IL-4, IL-10 and TGFβ1), pro-inflammatory cytokines (IFNγ and TNFα) and ISGs (ISG15, MX1, MX2, OAS1) in pregnant and non-pregnant cows. Cows were grouped as pregnant and non-pregnant after pregnancy confirmation by non-return to heat, ultrasonography, per rectal examination along with progesterone and IFNτ assay. Significantly (P < 0.05) higher relative mRNA expression of IDO1 and anti-inflammatory cytokines on days 10 and 18 post-AI were observed in both neutrophils and PBMCs of pregnant cows. Pregnant cows showed significantly (P < 0.05) higher mRNA transcripts of IFNγ and TNFα genes on days 18 post-AI in both neutrophils and PBMCs. Expression of ISGs was higher (P < 0.05) on day 10^th and 18^th post AI in both the neutrophils and PBMCs of pregnant cows. The study indicates that systemic immune regulation by IDO1 (through cytokine shift) and ISGs in peripheral immune cells are essential for the establishment of pregnancy and may be targeted in future as biomarkers for pregnancy diagnosis.

A comparative study on various immunological parameters influencing embryo survivability in crossbred dairy cows

Since long embryonic mortality has remained an area of concern affecting the reproduction, production, and profitability of dairy cows. We investigated the possible interaction between interleukins, hormones, and neutrophil associated CD markers during the implantation window in Karan Fries (KF) cows naturally coming to heat. Blood collection was done on days 0 i.e. day of Artificial Insemination (AI), 10, 18, 21, 30 and on day 40 post-AI. Total leucocyte count (TLC) and neutrophil to lymphocyte (N:L) ratio were recorded. Blood neutrophils were isolated and their number, phagocytic activity (PA), myeloperoxidase (MPO) concentration and relative mRNA expression of cell adhesion molecules (CD-11b, CD-31, CD-44, CD-62L) as well as progesterone-inducing-blocking-factor (PIBF) and glucocorticoid receptor alpha (GRα) were examined. Plasma progesterone, cortisol, IL-2, IL-8, IL-6, and IL-10 were also measured. Pregnancy was confirmed by non-return to heat, ultrasonography and per rectal examination along with progesterone assay. Cows were further divided into pregnant (P), early embryonic mortality (EEM) and late embryonic mortality (LEM) groups. Embryonic losses cows showed lower plasma concentration of IL-10 (<100 pg/ml) and a higher concentration of IL-2 (>500 pg/ml). Also, a 4 fold increase in the relative mRNA expression of CD-11b and 2.5 fold changes in CD-44 expression were observed in embryonic mortality. We observed a 1.5 fold increase in the relative mRNA expression of PIBF and a 0.5 fold increase in GRα expression in pregnant cows compared to EEM (on day 21) and LEM (on days 30 and 40) cows. Our results depicted that the hyperimmune status of the dam which could be due to multifactorial events that led to the pregnancy failure. The above basic values may be used for checking the immune status and thus timely management strategies can be taken to prevent embryonic losses.

Review: Practical Use of n-3 Fatty Acids to Improve Reproduction Parameters in the Context of Modern Sow Nutrition

Simple Summary

The use of n-3 fatty acids could have many favourable aspects considering the nutrition of mammals, as can be seen from studies carried out on humans or livestock animals. Concerning large-scale pig farms, the reproduction performance could be made more balanced at a high level by enhancing efficacy and decreasing the ecological footprint of pork production. In this review, we attempt to identify specific periods in the sow production cycle in which the feeding of n-3 fatty acids returns an investment, in addition to demonstrating the importance of the dosage and proportion of n-6 and n-3 fatty acids, originating from different nutritional sources.

Abstract

The effects of long-chain polyunsaturated fatty acids (LC PUFAs) have been frequently investigated in sows because the profitability of pig production depends mainly on reproduction performance. In feeding trials, different sources and doses of n-3 PUFAs-rich feeds were used with various breeds and stages of production; however, a discrepancy in the response of n-3 PUFAs on sow reproduction has been observed. According to the results of the previous studies, n-3 fatty acids can postpone the time of parturition, decreasing the synthesis of prostaglandins, which are necessary for uterus contraction during labour. These effects could also be useful during the post-weaning period when low prostaglandin levels are indispensable for embryo survival. The n-3 fatty acids fed during the lactation period secreted in milk, may improve piglet performance. In this review, we will focus on the contradictory results of previous studies concerning practical swine nutrition. The main purpose of the review is to highlight those periods of swine breeding when the use of n-3 fatty acids may be advantageous in case of the deficiency of these essential nutrients. In finding the appropriate dose of n-3 PUFAs in terms of sow nutrition, the n-6 PUFAs levels in the given feeds must be taken into account to ensure that there are no significant reductions in the final n-6/n-3 ratio. Despite the numerous previous field trials, there are no current feeding recommendations available for PUFAs in swine nutrition. Hence, more research is required in different practical feeding situations to certify the assumptions and conclusions of this review.

Bovine Interferon-Tau Activates Type I interferon-Associated Janus-signal Transducer in HPV16-positive Tumor Cell

The mechanisms of signal transduction by interferon-tau (IFN-τ) are widely known during the gestation of ruminants. In trophoblast cells, IFN-τ involves the activation of the JAK-STAT pathway, and it can have effects on other cell types, such as tumor cells. Here we report that the HPV16-positive BMK-16/myc cell treated with ovine IFN-τ, results in the activation of the canonical JAK-STAT and non-canonical JAK-STAT pathway. The MAPK signaling pathway was activated, we detected the proteins MEK1, MEK2, Raf1, STAT3, STA4, STAT5 and STAT6. Moreover, IFN-τ induced the expression of MHC Class I, MX and IP10 in the tumor cells and this response may be associated with the viral replication and with the anti-proliferative and the immunoregulatory effects of IFN-τ.

Importance of Viral Disease in Dairy Cow Fertility

Many viral diseases are endemic in cattle populations worldwide. The ability of many viruses to cross the placenta and cause abortions and fetal malformations is well understood. There is also significant evidence that viral infections have additional actions in dairy cows, which are reflected in reduced conception rates. These effects are, however, highly dependent on the time at which an individual animal first contracts the disease and are less easy to quantify. This paper reviews the evidence relating to five viruses that can affect fertility, together with their potential mechanisms of action. Acute infection with non-cytopathic bovine viral diarrhea virus (BVDV) in mid-gestation increases abortion rates or causes the birth of persistently infected calves. BVDV infections closer to the time of breeding can have direct effects on the ovaries and uterine endometrium, which cause estrous cycle irregularities and early embryo mortality. Fertility may also be reduced by BVDV-induced immunosuppression, which increases the susceptibility to bacterial infections. Bovine herpesvirus (BHV)-1 is most common in pre-pubertal heifers, and can slow their growth, delay breeding, and increase the age at first calving. Previously infected animals subsequently show reduced fertility. Although this may be associated with lung damage, ovarian lesions have also been reported. Both BHV-1 and BHV-4 remain latent in the host following initial infection and may be reactivated later by stress, for example associated with calving and early lactation. While BHV-4 infection alone may not reduce fertility, it appears to act as a co-factor with established bacterial pathogens such as Escherichia coli and Trueperella pyogenes to promote the development of endometritis and delay uterine repair mechanisms after calving. Both Schmallenberg virus (SBV) and bluetongue virus (BTV) are transmitted by insect vectors and lead to increased abortion rates and congenital malformations. BTV-8 also impairs the development of hatched blastocysts; furthermore, infection around the time of breeding with either virus appears to reduce conception rates. Although the reductions in conception rates are often difficult to quantify, they are nevertheless sufficient to cause economic losses, which help to justify the benefits of vaccination and eradication schemes.

Use of a prediction method for early pregnancy status utilizing receiver operating characteristic curve analysis of peripheral blood leukocyte interferon-stimulated genes in Japanese-Black cattle

A prediction method for early pregnancy status (pregnant or non-pregnant) in cattle that can be used within 3 weeks after insemination is desired. Interferon-stimulated genes (ISGs) in peripheral blood leukocytes (PBLs) have been examined as prediction molecules for determination of pregnancy status. Relative abundances of ISG15 and MX2 gene transcripts in PBLs were suitable biomarkers for the prediction of pregnancy status when there were assessments of Holstein cattle. In the present study, it was determined whether ISG biomarkers are applicable for predicting gestation in Japanese-Black (JB) cattle and evaluation of the applicability of receiver operating characteristic (ROC) analysis procedures for this purpose. There was assessment of the reliability of using average ISG values in PBLs collected during the estrous cycle (AVE) as a cutoff compared to the Youden index cutoff values. Application of AVE to assessment of pregnancy status in JB cattle indicated there was reliable predictions for pregnancy status when using ISG15 and MX2 values on day 21 after insemination, which coincided with the time of assessment in the previous study with Holstein cattle. The area under the curve values of the ROC curves confirmed the reliability of using ISGs to predict pregnancy from days 18 to 21 after insemination. Comparing AVE with Youden index values, there was confirmation of the accuracy of AVE for predicting gestation. The average mRNA transcript abundance values of ISG15 and MX2 may serve as excellent pregnancy biomarkers for cattle within 3 weeks of insemination.

Combined effect of mastitis and parity on pregnancy loss in lactating Holstein cows

The main objective of this study was to examine the combined effect of mastitis and parity on pregnancy loss (PL) in lactating Holstein cows. A secondary objective was to estimate the cost of mastitis including that of PL attributable to mastitis. A total of 1,774 lactation periods from 1,047 Holstein cows with different parities from one dairy farm were included in a matched case-control study. All study cows were diagnosed pregnant by transrectal ultrasonography on day 33 after timed artificial insemination (TAI). Case cows (n = 222 lactations) were those later diagnosed non-pregnant by transrectal palpation on day 47 or 75 after TAI. Control cows (n = 1,552 lactations) were those confirmed pregnant by transrectal palpation on day 75 after TAI. Case cows were matched with eligible controls according to year of calving and calving-to-conception interval (CCI) ± 3 days. Cows with different parities were classified as exposed to subclinical mastitis (somatic cell score (SCS) > 4.5 in at least one Dairy Herd Improvement Association (DHIA) test day) or clinical mastitis (with or without evidence of subclinical mastitis) during two exposure periods: 1-42 days before breeding or 1-75 days during gestation (1 to PL diagnosis day in case cows, or 1-75 day in control cows). Conditional logistic regression was used to model the odds of PL as a function of previous exposure to mastitis in different parities. Cost of PL attributable to mastitis ($/case) among cows with mastitis was estimated based on attributable risk calculated in the epidemiologic analysis. We observed a higher than expected combined effect between exposure to mastitis (subclinical or clinical) before breeding and parity 3 or ≥ 4, and during gestation and parity ≥ 4 on PL. The cost of PL attributable to mastitis was highest ($196/case) in cows in parity ≥ 4 affected with clinical mastitis during gestation. Overall, study results indicate the impact of mastitis on PL is higher in older cows (parity ≥ 3). Dairy farmers and attending veterinarians can consider the combined effect of mastitis and parity when evaluating causes for PL and strategies for optimizing reproductive performance in dairy cows.

Endometrial expression of various genes (ISGs, PPARs, RXRs and MUC1) on day 16 post-ovulation in repeat breeder cows, with or without subclinical endometritis

Our objective was to elucidate differences in endometrial mRNA expressions of interferon-stimulated genes (ISG15, CTSL1, RSAD2, SLC2A1, CXCL10, and SLC27A6), peroxisome proliferator activated receptors (PPARA, PPARD, and PPARG), retinoic acid receptors (RXRA, RXRB, and RXRG), and mucin 1 (MUC1) in repeat breeder cows, with or without subclinical endometritis (RB + SE and RB, respectively) and normal cows on day 16 post-ovulation (n = 4 cows per group). The CXCL10 and SLC27A6 mRNA abundances were greater for normal cows compared to RB and RB + SE cows (P < 0.05 and P < 0.01 respectively) whereas ISG15 and SLC2A1 mRNA abundances were greater for normal cows compared to RB + SE (P < 0.05). The SLC27A6 mRNA abundances were greater for RB versus RB + SE (P < 0.01). Similarly, PPARD, PPARG, RXRA and RXRG mRNA abundances were greater for normal cows compared to RB and RB + SE (P < 0.01 and P < 0.05, respectively). Abundances of PPARD, PPARG, RXRA and RXRG mRNA were greater for RB versus RB + SE (P < 0.05) and MUC1 was lower in abundance in normal cows compared to RB or RB + SE (P < 0.05). Key predicted molecular functions were binding, signal transducer and transporter; key biological processes were cellular, localization and metabolic; key cellular components were cell part, membrane and organelle components; and key protein classes were nucleic acid binding, receptor, and transcription factors. Gene networking analysis highlighted interactions and pathways involving PAPRs, RXRs, and MUC1, notably among PPARD, PPARG, and MUC1. In conclusion, endometrial mRNA expressions of ISGs (CXCL10 and SLC27A6), PPAR isomers (PPARD and PPARG), and RXRs (RXRA and RXRG) were in lower abundances, whereas MUC1 expression was more abundant in RB or RB + SE compared to normal cows on day 16. In addition, ISG15 and SLC2A1 genes were less abundant in RB + SE versus RB or normal cows. Altered expression of these uterine genes and associated potential impairment in embryo elongation and implantation may promote embryonic loss in repeat breeder cows. Furthermore, interactions among PPARD, PPARG and MUC1 may be therapeutically exploitable.

Maternal nutrient restriction in early pregnancy increases the risk of late embryo loss despite no effects on peri-implantation interferon-stimulated genes in suckler beef cattle

Reducing feeding costs in suckler beef herds to improve economic returns could have detrimental impacts on fertility. This study sought to determine whether maternal nutrient restriction during early pregnancy affects interferon-stimulated gene (ISG) expression in peripheral blood mononuclear cells during the peri-implantation period in two beef cattle breeds. Relationships were also examined between subnutrition and pregnancy failure defined according to ISG fold changes on Days 18 and 21 and to plasma pregnancy specific protein B (PSPB) concentrations on Day 28 post-artificial insemination (AI). Pirenaica or Parda de Montaña dams were assigned to a control (n = 23) or subnutrition (n = 30) group, receiving 100% or 65% of their estimated nutritional requirements from Day 1 to 82 post-AI, respectively. Treatment did not affect ISG expression or fertility. According to ISG fold changes (chi-square P = .023) or PSPB levels (chi-square P = .04) recorded in the subnutrition group, late embryo loss was more likely than in controls. Positive correlation was detected between Day 28 PSPB concentrations and both Day 18 MX1, MX2 and ISG15 expression, and Day 21 OAS1 expression. OAS1 and MX1 fold changes were found to be the best variables to discriminate pregnancy status. Our findings indicate that maternal nutrient restriction during the first third of pregnancy does not impair embryo signalling yet may increase the risk of pregnancy failure.

Differential gene expression in bovine endometrial epithelial cells after challenge with LPS; specific implications for genes involved in embryo maternal interactions

Lipopolysaccharide (LPS) expressed on the surface of Gram-negative bacteria activates pro-inflammatory pathways, dys-regulates the function of endometrial cells and is a key player in the mechanisms involved in endometritis. This study aimed to investigate the effects of LPS on bovine endometrial epithelial cells (bEEC) from whole transcriptome with a special focus on genes involved in embryo-maternal interactions. Following in vitro culture, bEEC from three cows were exposed to 0, 2, and 8 μg/mL LPS for 24h. RNA samples extracted at 0 and 24 hours were analyzed by RNA sequencing (RNA-seq). At 24h, 2035 differentially expressed genes (DEGs) were identified between controls and samples treated with 2 μg/mL LPS. Gene ontology analysis showed that over-expressed DEGs were associated to immune response, response to stress and external stimuli, catalytic activity, and cell cycle. Genes associated with cell membrane and cell adhesion pathways were under-expressed. LPS induced changes in expression of specific genes related to embryo-maternal interactions including under-expression of eight members of the cadherin superfamily, over-expression of six members of the mucin family, and differential expression of a large set of genes binding the above molecules and of more than 20 transcripts coding for cytokines and their receptors. Type I interferon-τ dependent genes were also over-expressed. From a sub-set of 19 genes, (biological replicates of bEEC from cows taken at time 6 (n = 3), 24 (n = 6) and 48 hours (n = 3), and 2 technical replicates per sample) differential gene expression was confirmed by RT²-qPCR (r² between fold changes at 24 hours by RT²-qPCR and RNA-seq = 0.97). These results indicate that LPS affects the function of bEEC in many ways by differential transcription, glycolytic metabolism and oxidative stress. Many transcriptomic signatures related to implantation and embryo maternal interactions were strongly affected by LPS. These results pave the way for further studies to investigate the duration of these changes and their possible impact on endometrial function and fertility.

Newly identified interferon tau-responsive Hes family BHLH transcription factor 4 and cytidine/uridine monophosphate kinase 2 genes in peripheral blood granulocytes during early pregnancy in cows

In cattle, interferon-stimulated genes (ISGs) such as ISG15, MX1, MX2, and OAS1 are known as classic ISGs that are highly involved in the implantation process. Various molecules play a crucial role in the mechanisms underlying ISG effects. Although microarray analyses have highlighted the expression of various molecules during the implantation period, these molecules remain incompletely characterized. In the present study, various specifically expressed genes were selected and their characteristics were examined. The microarray data from peripheral blood leukocytes derived from artificially inseminated cows and granulocytes obtained from embryo-transferred cows, respectively, were used to identify new ISG candidates. Seven common genes, including ISG15 and OAS1, were confirmed, but only 4 of the 5 genes were amplified by reverse transcription quantitative polymerase chain reaction. In addition, 3 expressed sequence tags (ESTs) exhibited significantly greater expression in granulocytes from pregnant cows than that observed in bred nonpregnant cows, and the expression in granulocytes increased after interferon-tau stimulation. Sequence alignment revealed similar sequences within 2 ESTs on the Hairy and enhancer of split (Hes) family basic helix-loop-helix transcription factor 4 (HES4) gene. An additional EST was identified as cytidine/uridine monophosphate kinase 2 (CMPK2). In silico analysis facilitated the identification of transcription factor-binding sequences, including an interferon-stimulated response element and interferon regulatory factor-binding sites, within the promoter region of HES4 and CMPK2. These genes may function as new ISGs in the context of implantation and may participate in the coordination of the feto-maternal interface in cows.

Fine-tuned adaptation of embryo-endometrium pairs at implantation revealed by transcriptome analyses in Bos taurus

Interactions between embryo and endometrium at implantation are critical for the progression of pregnancy. These reciprocal actions involve exchange of paracrine signals that govern implantation and placentation. However, it remains unknown how these interactions between the conceptus and the endometrium are coordinated at the level of an individual pregnancy. Under the hypothesis that gene expression in endometrium is dependent on gene expression of extraembryonic tissues and genes expressed in extraembryonic tissues are dependent of genes expressed in the endometrium, we performed an integrative analysis of transcriptome profiles of paired extraembryonic tissue and endometria obtained from cattle (Bos taurus) pregnancies initiated by artificial insemination. We quantified strong dependence (|r| > 0.95, empirical false discovery rate [eFDR] < 0.01) in transcript abundance of genes expressed in the extraembryonic tissues and genes expressed in the endometrium. The profiles of connectivity revealed distinct coexpression patterns of extraembryonic tissues with caruncular and intercaruncular areas of the endometrium. Notably, a subset of highly coexpressed genes between extraembryonic tissue (n = 229) and caruncular areas of the endometrium (n = 218, r > 0.9999, eFDR < 0.001) revealed a blueprint of gene expression specific to each pregnancy. Gene ontology analyses of genes coexpressed between extraembryonic tissue and endometrium revealed significantly enriched modules with critical contribution for implantation and placentation, including “in utero embryonic development,” “placenta development,” and “regulation of transcription.” Coexpressing modules were remarkably specific to caruncular or intercaruncular areas of the endometrium. The quantitative association between genes expressed in extraembryonic tissue and endometrium emphasize a coordinated communication between these two entities in mammals. We provide evidence that implantation in mammalian pregnancy relies on the ability of the extraembryonic tissue and the endometrium to develop a fine-tuned adaptive response characteristic of each pregnancy.

An integrative analysis of interactions between conceptus and endometrium, in cattle, reveals complex regulatory networks operating at the time of implantation, highlighting the unique transcriptional blueprint of conceptus-maternal communication

Implantation in mammals requires a complex crosstalk between the conceptus (the embryo and associated membranes) and the uterus. An imbalanced regulation of the factors contributing to these interactions has negative impacts on the attachment of the fetus, the progression of the pregnancy, and the progeny. Focusing on paired conceptus–endometrium analyses of individual pregnancies in cows, we have determined that communication at implantation encompasses synchronized genome-wide coregulation of genes. Gene regulatory interactions between one conceptus and the surrounding maternal tissue vary between endometrial regions containing or lacking glands. Our data reveal new insights, to our knowledge, on the coordination of molecular mechanisms that contribute to implantation and pregnancy establishment in mammals. We conclude that the biological response of the endometrium is embryo-specific, a phenomenon that deserves further investigation in the context of assisted reproductive technologies.

Interferons and Proinflammatory Cytokines in Pregnancy and Fetal Development

Successful pregnancy requires carefully-coordinated communications between the mother and fetus. Immune cells and cytokine signaling pathways participate as mediators of these communications to promote healthy pregnancy. At the same time, certain infections or inflammatory conditions in pregnant mothers cause severe disease and have detrimental impacts on the developing fetus. In this review, we examine evidence for the role of maternal and fetal immune responses affecting pregnancy and fetal development, both under homeostasis and following infection. We discuss immune responses that are necessary to promote healthy pregnancy and those that lead to congenital disorders and pregnancy complications, with a particular emphasis on the role of interferons and cytokines. Understanding the contributions of the immune system in pregnancy and fetal development provides important insights into the pathogenesis underlying maternal and fetal diseases and sheds insights on possible targets for therapy.

The evolution of interferon-tau

Thirty years ago, a novel type I interferon (IFN) was identified by molecular cloning of cDNA libraries constructed from RNA extracted from ovine and bovine pre-implantation embryos. This protein was eventually designated as IFN-tau (IFNT) to highlight its trophoblast-dependent expression. IFNT function is not immune related. Instead, it interacts with the maternal system to initiate the establishment and maintenance of pregnancy. This activity is indispensable for the continuation of pregnancy. Our review will describe how IFNT evolved from other type I IFNs to function in this new capacity. IFNT genes have only been identified in pecoran ruminants within the Artiodactyla order (e.g. cattle, sheep, goats, deer, antelope, giraffe). The ancestral IFNT gene emerged approximately 36 million years ago most likely from rearrangement and/or insertion events that combined an ancestral IFN-omega (IFNW) gene with a trophoblast-specifying promoter/enhancer. Since then, IFNT genes have duplicated, likely through conversion events, and mutations have allowed them to adapt to their new function in concert with the emergence of different species. Multiple IFNT polymorphisms have been identified in cattle, sheep and goats. These genes and gene alleles encode proteins that do not display identical antiviral, antiproliferative and antiluteolytic activities. The need for multiple IFNT genes, numerous alleles and distinct activities remains debatable, but the consensus is that this complexity in IFNT expression and biological activity must be needed to provide the best opportunity for pregnancy to be recognized by the maternal system so that gestation may continue.

Genome sequencing and protein domain annotations of Korean Hanwoo cattle identify Hanwoo-specific immunity-related and other novel genes

Background

Identification of genetic mechanisms and idiosyncrasies at the breed-level can provide valuable information for potential use in evolutionary studies, medical applications, and breeding of selective traits. Here, we analyzed genomic data collected from 136 Korean Native cattle, known as Hanwoo, using advanced statistical methods.

Results

Results revealed Hanwoo-specific protein domains which were largely characterized by immunoglobulin function. Furthermore, domain interactions of novel Hanwoo-specific genes reveal additional links to immunity. Novel Hanwoo-specific genes linked to muscle and other functions were identified, including protein domains with functions related to energy, fat storage, and muscle function that may provide insight into the mechanisms behind Hanwoo cattle’s uniquely high percentage of intramuscular fat and fat marbling.

Conclusion

The identification of Hanwoo-specific genes linked to immunity are potentially useful for future medical research and selective breeding. The significant genomic variations identified here can crucially identify genetic novelties that are arising from useful adaptations. These results will allow future researchers to compare and classify breeds, identify important genetic markers, and develop breeding strategies to further improve significant traits.

Electronic supplementary material

The online version of this article (10.1186/s12863-018-0623-x) contains supplementary material, which is available to authorized users.

Type I interferons instigate fetal demise after Zika virus infection

Zika virus (ZIKV) infection during pregnancy is associated with adverse fetal outcomes, including microcephaly, growth restriction, and fetal demise. Type I interferons (IFNs) are essential for host resistance against ZIKV, and IFN-α/β receptor (IFNAR)-deficient mice are highly susceptible to ZIKV infection. Severe fetal growth restriction with placental damage and fetal resorption is observed after ZIKV infection of type I IFN receptor knockout (Ifnar1-/-) dams mated with wild-type sires, resulting in fetuses with functional type I IFN signaling. The role of type I IFNs in limiting or mediating ZIKV disease within this congenital infection model remains unknown. In this study, we challenged Ifnar1-/- dams mated with Ifnar1+/- sires with ZIKV. This breeding scheme enabled us to examine pregnant dams that carry a mixture of fetuses that express (Ifnar1+/-) or do not express IFNAR (Ifnar1-/-) within the same uterus. Virus replicated to a higher titer in the placenta of Ifnar1-/- than within the Ifnar1+/- concepti. Yet, rather unexpectedly, we found that only Ifnar1+/- fetuses were resorbed after ZIKV infection during early pregnancy, whereas their Ifnar1-/- littermates continue to develop. Analyses of the fetus and placenta revealed that, after ZIKV infection, IFNAR signaling in the conceptus inhibits development of the placental labyrinth, resulting in abnormal architecture of the maternal-fetal barrier. Exposure of midgestation human chorionic villous explants to type I IFN, but not type III IFNs, altered placental morphology and induced cytoskeletal rearrangements within the villous core. Our results implicate type I IFNs as a possible mediator of pregnancy complications, including spontaneous abortions and growth restriction, in the context of congenital viral infections.

Species Specific Antiviral Activity of Porcine Interferon-α8 (IFNα8)

Interferons (IFNs) have been known as antiviral genes and they are classified by type 1, type 2, and type 3 IFN. The type 1 IFN consists of IFNα, IFNβ, IFNτ, and IFNω whereas the type 2 IFN consists of only IFNγ, which is a key cytokine driving T helper cell type 1 immunity. IFNλ belongs to the type 3 IFN, which is also known as IL-28 and IL-29 possessing antiviral activities. Type 1 IFN is produced by viral infection whereas type 2 IFN is induced by mitogenic or antigenic T-cell stimuli. The IFNτ of bovine was first discovered in an ungulate ruminant recognition hormone. IFNτ belongs to the type 1 IFN with the common feature of type 1 IFN such as antiviral activity. IFNs have been mostly studied for basic research and clinical usages therefore there was no effort to investigate IFNs in industrial animals. Here we cloned porcine IFNα8 from peripheral blood mononuclear cells of Korean domestic pig (Sus scrofa domestica). The newly cloned IFNα8 amino acid sequence from Korean domestic pig shares 98.4% identity with the known porcine IFNα8 in databank. The recombinant porcine IFNα8 showed potent antiviral activity and protected bovine Madin-Darby bovine kidney epithelial (MDBK) cells from the cytopathic effect of vesicular stomatitis virus, but it failed to protect human Wistar Institute Susan Hayflick (WISH) cells and canine Madin-Darby canine kidney epithelial-like (MDCK) cells. The present study demonstrates species specific antiviral activity of porcine IFNα8.

Transcriptional control of IFNT expression

Once interferon-tau (IFNT) had been identified as a type I IFN in sheep and cattle and its functions were characterized, numerous studies were conducted to elucidate the transcriptional regulation of this gene family. Transfection studies performed largely with human choriocarcinoma cell lines identified regulatory regions of the IFNT gene that appeared responsible for trophoblast-specific expression. The key finding was the recognition that the transcription factor ETS2 bound to a proximal region within the 5'UTR of a bovine IFNT and acted as a strong transactivator. Soon after other transcription factors were identified as cooperative partners. The ETS2-binding site and the nearby AP1 site enable response to intracellular signaling from maternal uterine factors. The AP1 site also serves as a GATA-binding site in one of the bovine IFNT genes. The homeobox-containing transcription factor, DLX3, augments IFNT expression combinatorially with ETS2. CDX2 has also been identified as transactivator that binds to a separate site upstream of the main ETS2 enhancer site. CDX2 participates in IFNT epigenetic regulation by modifying histone acetylation status of the gene. The IFNT downregulation at the time of the conceptus attachment to the uterine endometrium appears correlated with the increased EOMES expression and the loss of other transcription coactivators. Altogether, the studies of transcriptional control of IFNT have provided mechanistic evidence of the regulatory framework of trophoblast-specific expression and critical expression pattern for maternal recognition of pregnancy.

Evaluation of interferon-stimulated genes in peripheral blood granulocytes as sensitive responders to bovine early conceptus signals

Early detection of gestation is important in the bovine industry. New methods have been developed to detect gene expression in leucocytes induced by interferon-tau (IFNT) as gestation biomarkers. However, it is debatable which blood cell is suitable for detecting gene expression. This study was aimed at confirming whether granulocytes respond to IFNT specifically. Granulocytes and mononuclear cells (MNCs) from cows, and several types of bovine cultured cells, were treated with recombinant (r) IFNT and gene expression was analysed by quantitative real-time reverse transcriptase (RT)-PCR and microarray analysis. Expression levels of IFN receptors (R1 and R2) were approximately 30- to 900-fold higher in granulocytes than in other cultured cells, and 1.5- to 2.5-fold higher in MNCs than in granulocytes. Microarray analysis following a 2h recombinant IFNT (rIFNT) treatment revealed expression changes for 900 genes in granulocytes. Genes with expression changes included known IFN-stimulated genes (ISGs; ISG15, OAS1, MX1, and MX2). Eighteen genes were selected following granulocyte microarray analysis and their expression changes were confirmed in early gestation, which revealed that nine genes had significantly higher expression levels in pregnant than in non-pregnant animals. In conclusion, granulocytes specifically responded to rIFNT treatment and the resulting gene expression changes correlated with those in vivo. Microarray analysis indicated that various genes showed expression changes in rIFNT-treated granulocytes, which may result in the identification of alternate candidate genes for the early detection of gestation. These results strongly indicate that gene expression in granulocytes is a suitable tool to determine pregnancy status.

Fibroblast growth factor 2 induces proliferation and distribution of G2 /M phase of bovine endometrial cells involving activation of PI3K/AKT and MAPK cell signaling and prevention of effects of ER stress

Fibroblast growth factor 2 (FGF2) is abundantly expressed in conceptuses and endometria during pregnancy in diverse animal models including domestic animals. However, its intracellular mechanism of action has not been reported for bovine endometrial cells. Therefore, the aim of this study was to identify functional roles of FGF2 in bovine endometrial (BEND) cell line which has served as a good model system for investigating regulation of signal transduction following treatment with interferon-tau (IFNT) in vitro. Results of present study demonstrated that administration of FGF2 to BEND cells increased their proliferation and regulated the cell cycle through DNA replication by an increase of PCNA and Cyclin D1. FGF2 also increased phosphorylation of AKT, P70S6K, S6, ERK1/2, JNK, and P38 in BEND cells in a dose-dependent manner, and expression of each of those transcription factors was inhibited by their respective pharmacological inhibitor including Wormannin, U0126, and SP600125. In addition, the increase in proliferation of BEND cells and activation of the protein kinases in response to FGF2 was suppressed by BGJ398, a FGFR inhibitor. Furthermore, proliferation of BEND cells was inhibited by tunicamycin, but treatment of BEND cells with FGF2 restored proliferation of BEND cells. Consistent with this result, the stimulated unfolded protein response (UPR) regulatory proteins induced by tunicamycin were down-regulated by FGF2. Results of this study suggest that FGF2 promotes proliferation of BEND cells and likely enhances uterine capacity and maintenance of pregnancy by activating cell signaling via the PI3K and MAPK pathways and by restoring ER stress through the FGFR.

Interferon-τ induced gene expression in bovine hepatocytes during early pregnancy

Interferon-tau (IFNτ) is the conceptus derived specific early pregnancy signal in bovidae. Locally, IFNτ induces an IFNτ specific gene expression (ISG) in endometrial cells and by this it averts luteolysis of the corpus luteum (CL) by suppressing prostaglandin production. Moreover, it was shown that IFNτ also induces ISG in the liver in pregnant sheep and in liver biopsies from Holstein Friesian heifers on Day 18 of pregnancy. The objective of the present study was to confirm increased hepatic ISG in vivo on Day 18 of pregnancy and to prove if hepatocytes and not non-parenchymal cells react to IFNτ by using immunohistochemistry and primary bovine hepatocytes stimulated in vitro with recombinant bovine IFNτ. For the animal experiment, Angus heifers (n = 12) were cycle synchronized and the Day of ovulation (Day 0) was defined by ovarian ultrasonography and verified by progesterone < 0.1 ng/ml. Heifers were artificially inseminated either with sperm (n = 9) or with seminal plasma (mock control, n = 3). Early pregnancy was defined and detected by progesterone and pregnancy associated glycoprotein (PAG) concentration in blood before and after induced luteolysis by a PGF-injection on Day 21 in n = 3 inseminated heifers. A liver biopsy was taken on Day 18 for the analysis of gene (ISG 15, MX 1, MX 2 and OAS 1) and protein (OAS1) expression using qPCR and immunohistochemistry, respectively. Primary bovine hepatocytes were collected from bull liver using a two-step collagenase perfusion, cultured short-term in a monolayer and stimulated with IFNτ. Thereafter, gene expression was measured by qPCR. In liver biopsies obtained from pregnant heifers ISG was numerically higher expressed compared to biopsies from non-pregnant heifers. Furthermore, the OAS 1 protein expression was localized in hepatocytes on Day 18 of pregnancy. In vitro, primary bovine hepatocytes showed an increased mRNA expression of ISG after IFNτ stimulation. In conclusion, the findings confirm that IFNτ induces ISG in the parenchymal part of the liver in early pregnancy of cattle.