Interferon-tau Research Articles

Effects of progesterone and interferon tau on ovine endometrial phosphate, calcium, and vitamin D signaling

Given recent reports of expression of postnatal mineral transport regulators at the maternal-conceptus interface during the peri-implantation period, this study tested the hypothesis that progesterone (P4) and interferon tau (IFNT) regulate phosphate, calcium, and vitamin D signaling in the ovine endometrium. Mature Rambouillet ewes (n= 24) were surgically fitted with intrauterine catheters on day 7 of the estrous cycle. Ewes received daily intramuscular injections of 50mg of P4 in corn oil vehicle and 75mg of progesterone receptor antagonist (RU486) in corn oil from days 8 to 15, and twice-daily intrauterine injections of either control proteins (CX) or IFNT (25μg/uterine horn/day) from days 11 to 15 resulting in four treatment groups: P4 + CX; P4 + IFNT; RU486 + P4 + CX; and RU486 + P4 + IFNT. On day 16, ewes were hysterectomized. RU486 + P4 + CX treated ewes had lower concentrations of 25 (OH) D in plasma than P4 + CX treated ewes (P< 0.05). Endometria from ewes treated with IFNT had greater expression of FGF23 (P< 0.01), S100A9 (P< 0.05), and S100A12 (P= 0.05) mRNAs and lower expression of ADAM10 mRNA (P< 0.01) than of ewes treated with CX proteins. Expression of FGF23 mRNA was greater in endometria of ewes that received RU486 + P4 + IFNT than in ewes that received RU486 + P4 + CX (hormone × protein interaction, P< 0.05). The expression of S100G mRNA was greater in endometria of ewes that received P4 + IFNT compared to ewes that received RU486 + P4 + IFNT (P< 0.05; hormone × protein interaction, P< 0.01). These data implicate P4 and IFNT in the regulation of phosphate, calcium, and vitamin D signaling during the peri-implantation period of pregnancy and provide a platform for continued mechanistic investigations.

Progesterone and interferon tau regulate expression of polyamine enzymes during the ovine peri-implantation period†.

Progesterone (P4) and interferon tau (IFNT) are important for establishment and maintenance of pregnancy in ruminants. Agmatine and polyamines (putrescine, spermidine, and spermine) have important roles in the survival, growth, and development of mammalian conceptuses. This study tested the hypothesis that P4 and/or IFNT stimulate the expression of genes and proteins involved in the metabolism and transport of polyamines in the ovine endometrium. Rambouillet ewes (n = 24) were surgically fitted with intrauterine catheters on Day 7 of the estrous cycle. They received daily intramuscular injections of 50mg P4 in corn oil vehicle and/or 75-mg progesterone receptor antagonist (RU486) in corn oil vehicle from Days 8-15, and twice daily intrauterine injections (25μg/uterine horn/day) of either control serum proteins (CX) or IFNT from Days 11-15, resulting in four treatment groups: (i) P4 + CX; (ii) P4 + IFNT; (iii) RU486 + P4 + CX; or (iv) RU486 + P4 + IFNT. On Day 16, ewes were hysterectomized. The total amounts of arginine, citrulline, ornithine, agmatine, and putrescine in uterine flushings were affected (P < 0.05) by P4 and/or IFNT. P4 increased endometrial expression of SLC22A2 (P < 0.01) and SLC22A3 (P < 0.05) mRNAs. IFNT affected endometrial expression of MAT2B (P < 0.001), SAT1 (P < 0.01), and SMOX (P < 0.05) mRNAs, independent of P4. IFNT increased the abundance of SRM protein in uterine luminal (LE), superficial glandular (sGE), and glandular epithelia (GE), as well as MAT2B protein in uterine LE and sGE. These results indicate that P4 and IFNT act synergistically to regulate the expression of key genes required for cell-specific metabolism and transport of polyamines in the ovine endometrium during the peri-implantation period of pregnancy.

Recent progress of interferon-tau research and potential direction beyond pregnancy recognition.

Since the discovery of interferon-tau (IFNT) over 30 years ago as the trophectodermal cytokine responsible for the maintenance of the maternal corpus luteum (CL) in ruminants, exhaustive studies have been conducted to identify genes and gene products related to CL maintenance. Recent studies have provided evidence that although CL maintenance, with the up- and down-regulation of IFNT, is important, its regulatory role in the endometrial expression of interferon-stimulated genes (ISGs) is far more important for conditioning the uterine environment for successful conceptus implantation and thereafter. This review initially describes the mammalian implantation process, briefly but focuses on recent findings, as there appears to be a common phenomenon during early to mid-pregnancy among mammalian species.

Peri-implantation expression and regulation of ITGB8 in goat uterus

Ruminants have a superficial implantation pattern. The extended conceptus attaches to the receptive endometrium to form the cotyledonary placenta. During the attachment, a large number of events occur at the maternal-fetal interface. However, the related molecular mechanisms have not been fully understood. Integrin beta8 (ITGB8) is a subunit of integrin beta involved in embryo implantation. In this study, we determined peri-implantation expression and regulation of ITGB8 in goat uterus. The mRNA and protein levels of ITGB8 were both high in goat endometrial luminal epithelium (LE) and superficial glandular epithelium (sGE) during the adhesion period (Days 16–19 of pregnancy). Such expression profile was opposite to that of microRNA-187 (miR-187). Then, we validated that miR-187 targeted the 3′ untranslated region (UTR) of ITGB8 in primary goat endometrial epithelial cells (EECs). In EECs, inhibition of miR-187 resulted in not only up-regulated ITGB8 level but also reduced cell proliferation and focal adhesion kinase (FAK) activity. Moreover, ITGB8 and miR-187 were regulated by interferon tau (IFNT). Altogether, in goat, the miR-187/ITGB8 axis may be involved in conceptus attachment and is downstream of IFNT. Our results will help us better understand the mechanisms of ruminant implantation and may provide a useful tool to improve the reproduction ratio for ruminants.

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.

Heat stress modulates polymorphonuclear cell response in early pregnancy cows: I. interferon pathway and oxidative stress.

One of the major causes of early pregnancy loss is heat stress. In ruminants, interferon tau (IFNT) is the embryo signal to the mother. Once the interferon signaling pathway is activated, it drives gene expression for interferon-stimulated genes (ISGs) and alters neutrophils responses. The aim of the present study was to evaluate interferon (IFN) pathway, ISGs and gene expression in polymorphonuclear leukocytes (PMN) and oxidative stress in dairy cows under heat stress. Pregnant cows had their estrous cycle synchronized and randomly assigned to a comfort or heat stress group. Blood samples were collected at artificial insemination (AI) and on Days 10, 14 and 18 following AI. Pregnant cows were pregnancy checked by ultrasound on Day 30 and confirmed on Day 60 post-AI. Results are presented as mean ± SEM. The corpus luteum (CL) diameter was not different between groups of pregnant cows; concentration of progesterone of pregnant cows on Day 18 following AI was greater in comfort group compared to heat stressed group. Comfort pregnant cows had higher expression of all analyzed genes from interferon pathway, except for IFNAR1, on both Days 14 and 18. Conversely, heat stressed cows did not show altered expression of IFNT pathway genes and ISGs between Days 10, 14, and 18 after AI. The oxidative stress, determined as malondialdehyde (MDA) levels, was greater in heat stress group on Days 10, 14 and 18, independent of pregnancy status. Heat stress negatively influences expression of ISGs, IFN pathway gene expression in neutrophils, and oxidative stress. Our data suggest that lower conception rates in cows under heat stress are multifactorial, with the association of interferon pathway activation and the unbalanced oxidative stress being main contributing factors.

Involvement of the Interferon Tau Gene in Maternal Recognition of Gestation in Sheep

Objective: To describe the involvement of the interferon tau gene in the maternal recognition of pregnancy in sheep. Design/Methodology/Approach: A search and analysis of the scientific documents retrieved from the Web of Science and Scopus databases related to the functions of the interferon tau gene in the maternal recognition of pregnancy in sheep were conducted. Results: The interferon tau gene (IFNτ) participates in maternal recognition of pregnancy to avoid possible rejection of the embryo, and supports the secretion of progesterone involved in preparing the endometrium for implantation; it also inhibits myometrial motility to maintain pregnancy. IFNτ stimulates the transcription of so-called interferon-stimulated genes (ISGs), which are the effectors of cell-autonomous antiviral defense. One of the representative members of ISGs is the interferon 15-stimulated gene (ISG15) which regulates endometrial receptivity at implantation, as well as survival, growth and development of the conceptus. Study Limitations/Implications: Most embryonic losses occur between fertilization and maternal recognition of pregnancy. Understanding this issue is essential to understanding the possible causes of early pregnancy losses. Findings/Conclusions: Considerable progress has been made in the discovery of how the IFNτ and ISG15 genes act in maternal recognition of gestation in sheep

The Importance of Interferon-Tau in the Diagnosis of Pregnancy.

Several decades of improving dairy cattle towards unilateral utilization of dairy cattle led to enormous progress in the field of milk yield; however, it resulted in a number of unfavorable features, such as reproductive disorders, increased calf mortality, and reduced health. Most cases of embryo loss and/or lost pregnancies occur during the first four to five weeks of gestation; accurate detection for pregnancy during this period is likely to contribute to an improvement in gestation rates. A specific protein, interferon-tau (IFNT), stimulates interferon-stimulated genes (ISGs), and their expression increases during gestation within 21 days after insemination. In bovines, the early conceptus undergoes a phase of rapid growth and elongation before implantation, the latter occurring 2–3 weeks after fertilization. IFNT acts mainly in the endometrium of the luminal epithelium. It is a new type I interferon that regulates several genes encoding uterine-derived factors. They are crucial in the processes of preparing the uterus for placenta attachment, modifying the uterine immune system, and regulating early fetal development. Because IFNT is expressed and induces ISGs in the endometrium during pregnancy recognition, it was reasoned that surrogate markers for pregnancy or IFNT might be present in the blood and provide an indicator of pregnancy status in cattle.

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.

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

BackgroundMaintenance 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.ResultsThe 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.ConclusionThis 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.

Cathepsin L gene: Molecular characterization, functional analysis and expression profile in the endometrium of goat (Capra hircus)

In ruminant species, endometrial remodeling plays a pivotal role in regulation of estrous cycle and establishment of pregnancy. Among interferon tau (IFNT) stimulated genes, cathepsin (CTS) L is one of them, which is up-regulated in the endometrium during early pregnancy and plays an important role in endometrial remodeling and embryo development. However, the specific role of CTSL is not yet documented in goats. Therefore, in the present study, coding sequence (CDS) of CTSL was cloned, characterized, and its temporal expression profile was also examined in the endometrium of caprine (cp) for the first time. A fragment of cpCTSL, 963 bp in length, was amplified from complementary DNA (cDNA) with a 936 bp coding sequence, which encodes a polypeptide of 312 amino acids. Coding and deduced amino acid sequences of cpCTSL exhibited 72.8 to 99.3% identities with other species. A polypeptide of 312 amino acids of cpCTSL revealed three domains, a signal peptide sequence, a pro-domain and a partially mature domain. Further, the relative expression of cpCTSL mRNA and protein was determined by quantitative real-time PCR and western blot, respectively, in the endometrium of pregnant and cyclic does. Both cpCTSL mRNA and protein were expressed maximally (P < 0.05) during early pregnancy and these were 11.34 and 5.48-fold greater (P < 0.05), respectively, as compared to cyclic does. It is concluded that CTSL is mostly similar in structure to other species and increased level in the endometrium indicates its involvement in endometrial remodeling to sustain pregnancy in goats.

JAK3 and PI3K mediates the suppressive effects of interferon tau on neutrophil extracellular traps formation during peri-implantation period

Interferon tau (IFNτ) is the main maternal signal for pregnancy in ruminants and modulates the functions of various immune cells, including neutrophils. Neutrophil extracellular traps (NETs) are one of the main defence mechanisms of neutrophils. In this study, we observed higher (p < 0.01) ex-vivo NETs extrusion by blood neutrophils from day 16–18 post artificial insemination (AI) in non-inseminated and inseminated non-pregnant cows compared to pregnant cows. In vitro study also showed that IFNτ hampers NETs formation in dose and time dependent manner. The lowest (p < 0.01) NETs formation and the highest (p < 0.01) mRNA expression (RT-PCR) of IFNτ stimulated genes (ISG15, OAS1, MX1) were observed when neutrophil incubated with 9 ng/mL IFNτ for 3.5 h. Signalling cascades mediating IFNτ impairment of NETs formation were identified using inhibitors of JAK2, JAK3, p38, PI3K/Akt and MAPK/Erk. IFNτ reduced (p < 0.01) the mRNA expression (RT-PCR) and concentration (ELISA) of genes and proteins that mediate NETs formation in blood neutrophils including histones (H1, H2), neutrophil elastase (NE) and myeloperoxidase (MPO). However, the effects of IFNτ on these genes and proteins were eliminated in the presence of JAK3 or PI3K inhibitors. Immunocytochemistry study also showed strong MPO signal in the presence of JAK3 or PI3K inhibitors as compared to positive control (PC, IFNτ alone). The results indicate that IFNτ impairs NETs formation using JAK3 and PI3K and thus essential for successful implantation and establishment of pregnancy in cows.

Comparison of the Ability of High and Low Virulence Strains of Non-cytopathic Bovine Viral Diarrhea Virus-1 to Modulate Expression of Interferon Tau Stimulated Genes in Bovine Endometrium.

Bovine Viral Diarrhea virus (BVDV) is a pestivirus with a single-stranded, positive sense RNA genome. It is endemic in many cattle populations, causing major economic losses in part due to reduced fertility. BVDV exhibits great genetic diversity and is classified as type 1 or 2 (BVDV-1, BVDV-2) with either non-cytopathogenic (ncp) or cytopathogenic (cp) biotypes. Differing strains of ncpBVDV differ in virulence, affecting clinical outcome. BVDV replicates in the reproductive tract, affecting host immunity and embryo survival. This study used an in vitro model of primary bovine endometrial cell cultures to compare the effects of two BVDV ncp type 1a strains of differing virulence (termed HO and KY) on endometrial transcription of candidate interferon stimulated genes (ISG) using qPCR. Half the cultures were stimulated with interferon tau (IFNT, the conceptus produced pregnancy recognition factor) in the presence or absence of viral infection. Cultures were replicated on cells from 10 BVDV-free cows. IFNT treatment stimulated transcription of 10 candidate ISGs, whereas both ncpBVDV-1 strains alone inhibited transcription of 8/10 ISGs. In combined BVDV-1+IFNT cultures, the stimulatory effect of IFNT on expression of GBP4, ISG15, HERC5, RSAD2, IFIH1, IFIT3, and MX1 was significantly inhibited by HO, but only ISG15, RSAD2, IFI27, and IFIT3 were decreased by KY. Inhibition by HO was generally greater. The IFNT-induced expression of TRIM56 was, however, increased by HO. These data show that HO, the more virulent ncpBVDV-1 strain, has a greater capacity to inhibit key antiviral pathways. These differences need confirmation at the protein level but may influence immune tolerance of the host. They could also reduce fertility by increasing uterine susceptibility to bacterial infection and disrupting IFNT-mediated pregnancy recognition.

Neutrophils recognize and amplify IFNT signals derived from day 7 bovine embryo for stimulation of ISGs expression in vitro: A possible implication for the early maternal recognition of pregnancy

Previously, we reported that the presence of multiple day 7 (D7) bovine embryos in the uterus induces systemic immune responses in circulating polymorphonuclear neutrophils (PMNs), but with unknown mechanism. Thus, this study aimed to investigate the direct impact of D7 bovine embryo on PMNs’ immune responses in vitro and whether these PMNs can amplify and transfer embryo signals further to another PMN population. PMNs were directly stimulated by embryo culture media (ECM) or interferon tau (IFNT) (10 ng/ml) followed by evaluating mRNA expression by real-time PCR and phenotypic analysis by flow cytometry. To test whether PMNs can transfer embryo signals to a new PMN population, PMNs triggered by ECM or IFNT, were thoroughly washed and diluted to remove any media components, and again were incubated in fresh culture media for 3 h, from which culture supernatants were collected and used as PMN conditioned media (CM) to stimulate a new PMN population. Similar to ECM, IFNT directly stimulated expressions of IFNs (IFNA, IFNG), interferon-stimulated genes (ISGs; OAS1, ISG15, MX1), STAT1, TGFB and IL8, and downregulated TNFA in PMNs. Flow cytometrical analyses demonstrated that IFNT stimulated expressions of pregnancy-related phenotypic markers, CD16 and arginase-1 (ARG1), in PMNs. Most importantly, PMN CM induced ISGs and STAT1 mRNA in fresh PMNs. Since IFNT directly upregulated IFNA expression in PMNs, the impact of IFNA on PMNs’ immune responses was further tested. Stimulation of PMNs with IFNA, especially at a low level (1 pg/ml), induced IFNT-like immune responses comparable to those induced by PMN CM. Together, these findings indicated that D7 bovine embryos induce direct anti-inflammatory responses with upregulation of ISGs expressions in PMNs mainly via IFNT. Additionally, PMNs can amplify and transfer embryo signals to a new PMN population in a cell-to-cell communication mechanism possibly mediated in part by IFNA. Such a novel immunological crosstalk might contribute to embryo tolerance and pregnancy establishment in cattle.

Pregnancy-induced changes in the transcriptome of the bovine corpus luteum during and after embryonic interferon-tau secretion†.

Understanding luteal maintenance during early pregnancy is of substantial biological and practical importance. Characterizing effects of early pregnancy, however, has historically been confounded by use of controls with potential exposure to early Prostaglandin F2-alpha (PGF) pulses or differences in Corpus Luteum (CL) age. To avoid this, the present study utilized bihourly blood sampling to ensure control CL (n=6) were of a similar age to CL from pregnant animals (n=5), yet without exposure to PGF pulses. Additionally, CL from second month of pregnancy (n=4) were analyzed to track fate of altered genes after cessation of embryonic interferon tau (IFNT) secretion. The major alteration in gene expression in first month of pregnancy occurred in interferon-stimulated genes (ISGs), with immune/interferon signaling pathways enriched in three independent over-representation analyses. Most ISGs decreased during second month of pregnancy, though, surprisingly, some ISGs remained elevated in the second month even after cessation of IFNT secretion. Investigation of luteolytic genes found few altered transcripts, in contrast to previous reports, likely due to removal of controls exposed to PGF pulses. An exception to this trend was decreased expression of transcription factor NR4A1. Beyond luteolytic genes and ISGs, over representation analyses highlighted the prevalence of altered genes within the extracellular matrix and regulation of Insulin-like growth factor (IGF) availability, confirming results of other studies independent of luteolytic genes. These results support the idea that CL maintenance in early pregnancy is related to lack of PGF exposure, although potential roles for CL expression of diverse ISGs and other pathways activated during early pregnancy remain undefined.

Bovine Embryonic Mortality with Special Reference to Mineral Deficiency, Heat Stress and Endocrine Factors: A Review

Embryonic Mortality is the major cause of reproductive and economic loss in cattle and Buffaloes. Embryonic Mortality is more common during the early than the late embryonic period, i.e., from day 8th to 16th at the hatching of blastocysts and initiation of elongation and commencement of implantation without affecting cycle lengths. Early embryonic mortality is a major source of embryonic and economic loss with mortality rate up to 40%. Embryonic mortality is also reported due to mineral deficiency and heat stress in cattle and buffaloes. Physical modifications of animal environment, nutritional management with Antioxidant, trace minerals and genetic development of breeds that are less sensitive to heat stress should be best solution. Embryonic death occurs at the time of maternal recognition of pregnancy, probably related to a failure of the Interferon tau (IFNι) secretory mechanism along with progesterone deficiency and luteal insufficiency. Recent research, both in terms of physiological mechanisms and pharmacological treatments has mostly focused on the period of maternal recognition of pregnancy or the anti-luteolytic effect. hCG/ GnRH /Progesterone supplementation have shown positive results. Supplementation of interferon as anti-luteolytic agent and supplementing Omega-3 has shown encouraging results. Ovarian examination, Animal history, blood/milk progesterone levels, PAG test and ultrasound appear to be the only practical tool presently available for diagnosis of embryonic mortality. This present review article is covering all the aspects of embryonic mortality with special reference totrace minerals, heat stress, hormonal impact and interferon tau.

Heat stress influences the attenuation of prostaglandin synthesis by interferon tau in bovine endometrial cells

Heat stress (HS) reduces reproductive performance of cattle, possibly by disrupting endocrine regulation such as prostaglandin (PG) production from uterus and estradiol 17β production from the dominant follicle. Prostaglandin F2α (PGF2α) secretion from endometrium surges during the luteal phase due to tumor necrosis factor (TNF) α stimulation and a positive-feedback loop with oxytocin (OT) from the corpus luteum, ultimately triggering luteolysis, while interferon τ (IFNT) inhibits upregulation of PGF2α production by TNFα and OT, thereby preventing luteolysis and triggering recognition of pregnancy. In the present study, we investigated the effect of OT, TNFα, and IFNT on PGF2α production in both types of endometrial cells under HS conditions. Stimulation of PGF2α production in endometrial epithelial cells by OT was unaffected by HS, while stimulation of PGF2α production in endometrial stromal cells by TNFα was enhanced by HS, and this increased PGF2α production was not significantly suppressed by IFNT. These results suggest that HS disrupted the regulation of PGF2α production by TNFα and IFNT in bovine endometrial stromal cells and it might be one of causes for low conception rate of cattle in summer.

Metabolomic profiles of plasma and uterine luminal fluids from healthy and repeat breeder Holstein cows

BackgroundRepeat breeding is a critical reproductive disorder in cattle. The problem of repeat breeder cattle remains largely unmanageable due to a lack of informative biomarkers. Here, we utilized metabolomic profiling in an attempt to identify metabolites in the blood plasma and uterine luminal fluids. We collected blood and uterine fluid from repeat breeder and healthy cows on day 7 of the estrous cycle.ResultsMetabolomic analysis identified 17 plasma metabolites detected at concentrations that distinguished between the two groups, including decreased various bile acids among the repeat breeders. However, no metabolites that varied significantly were detected in the uterine luminal fluids between two groups. Among the plasma samples, kynurenine was identified as undergoing the most significant variation. Kynurenine is a metabolite produced from tryptophan via the actions of indoleamine 2,3-dioxygenase (IDO). As IDO is key for maternal immune tolerance and induced in response to interferon tau (IFNT, ruminant maternal recognition of pregnancy factor), we examined the responsiveness to IFNT on peripheral blood mononuclear cells (PBMC) isolated from healthy and repeat breeder cows. The mRNA expression of IFNT-response makers (ISG15 and MX2) were significantly increased by IFNT treatment in a dose-dependent manner in both groups. Although treatment with IFNT promoted the expression of IDO in PBMCs from both groups, it did so at a substantially reduced rate among the repeat breeder cows, suggesting that decreased levels of kynurenine may relate to the reduced IDO expression in repeat breeder cows.ConclusionsThese findings provide valuable information towards the identification of critical biomarkers for repeat breeding syndrome in cattle.

Analysis of novel embryonic factors of cattle and effects on endometrial cells in vitro

Interferon tau (IFNT) is thought to have essential functions in maternal recognition and establishment of pregnancy in ruminants. There, however, is a lack of research on embryonic factors that affect pregnancy other than IFNT. The present study was conducted to determine what are other embryo-derived factors involved in pregnancy recognition and to identify effects on endometrial cells using an in vitro culture system. With use of LC–MS/MS procedures to evaluate the supernatant of elongating embryos of cattle in culture, there was detection of 78 secretary proteins including five cytokines and two growth factors. Then there was analysis for up-regulated genes using ingenuity pathway procedure, IFNT and MIF were identified as upstream regulators of 37 and five genes, respectively. The mRNA transcript of MIF receptors was identified in endometrial cells, however, not in embryos. Among genes induced by MIF, CCL2, IL7 and IL23A transcripts were identified in endometrial cells. When endometrial cells were treated with interferon alpha (IFNA) and MIF, the CCL2 transcript was in a larger abundance of endometrial epithelial and polymorphonuclear neutrophil cells, and there was a larger abundance of there mRNA transcripts as a result of MIF treatment of peripheral blood mononuclear cells. In conclusion, MIF secreted by elongating embryos of cattle synergistically regulates relative abundances of specific mRNA transcripts of endometrial cells when there is treatment with IFNA, indicating further there are several factors other than IFNT that have effects on gene expression in the endometrium during early stages of gestation in cattle.

Possible impact of neutrophils on immune responses during early pregnancy in ruminants.

The interaction between early embryo and maternal immune system for the establishment of pregnancy is the focus of several studies; however, it remains unclear. The maternal immune response needs to keep a balance between avoiding any damage to the conceptus and maintaining its function in combating microbes as well. When conceptus-maternal crosstalk cannot achieve this balance, pregnancy losses might occur. Intercommunication between mother and conceptus is fundamental during early pregnancy to dictate the outcome of pregnancy. In ruminants, the embryo reacts with the maternal system mainly via interferon tau (IFNT) release. IFNT can act locally on the embryo and endometrial cells and systemically in several tissues and cells to regulate their response via the expression of interferon-stimulated genes (ISGs). Also, IFNT can induce the expression of inflammatory-related genes in immune cells. Day 7 embryo induces a shift in the maternal immune response towards anti-inflammatory (Th2) immune responses. During maternal recognition of pregnancy, peripheral mononuclear cells (PBMCs) and polymorphonuclear cells (PMNs) express markers that configure an anti-inflammatory response. However, PMNs response is more sensitive to the effects of IFNT. PMNs are more likely to express interferon-stimulated genes (ISGs), transforming growth factor-beta (TGFB), interleukin 10 (IL10), and arginase-1 (ARG1), configuring one of the most rapid immune responses to early pregnancy. This review focus on the local and peripheral immune responses during early pregnancy in ruminants, mainly the PMNs function in the immune system.