A simple, inexpensive and portable on-farm test for pregnancy diagnosis and ovary status in cows via chemical analysis of urine

Ovary dysfunction causes an aberrant endocrine surge at various reproductive cycle stages, negatively impacting fertility and economic profit. Optimizing dairy cow performance requires determining ovarian status and detecting early pregnancy. Still, little to no information is available about the diagnosis of the ovarian condition using urine chemical analysis at the field level in Bangladesh. This study aimed to develop a simple, inexpensive and portable on-farm technique for pregnancy diagnosis and ovary status determination in cows via chemical urine analysis. Fifty reproductively healthy cows were recruited from different donor farms. Prior to artificial insemination (AI), all selected cows were placed in a single ovsynch program. TAI (timed artificial insemination) was carried out. Urine was routinely collected from Day 0-55 days at estrus cycle stages for routine chemical analysis using barium chloride (BaCl2), followed by commercially available protein strip tests. The developed techniques for pregnancy and ovary status diagnosis in cows were validated with rectal palpation (RP). Barium chloride (BaCl2) analysis of urine revealed white precipitation corresponding to a mature follicle in the ovary during estrus and colorless precipitation corresponding to the corpus luteum during the diestrus period. Positive pregnancy was indicated by the presence of a colorless precipitate in the BaCl2 test, and a protein value of less than 100 mg/dl was found in the protein strip test. The maximum accuracy (42/50, 84%) was observed between 25 and 35 days, as confirmed by RP. Perplexing results were seen 45-55 days after AI, between pregnancies and luteal cystic disease. In both cases, we discovered that the BaCl2 precipitation was colorless. However, the protein value in the context of luteal cystic disease was found to be higher than 100 mg/dl. The barium chloride test, followed by protein strip tests, is a simple and portable way to diagnose pregnancy and determine ovarian status in cows at the field level.

Interferon-Stimulated Gene Expression in Peripheral Blood Leucocytes as a Convenient Prediction Marker for Embryo Status in Embryo-Transferred Japanese Black Cows during the Peri-Implantation Period

Pregnancy diagnosis during early gestation is important for cattle reproduction. The expression of interferon-stimulated genes (ISGs) in peripheral blood leukocytes (PBLs) was studied in embryo-transferred (ET) Japanese Black cattle. ISGs in PBLs-ISG15, MX1, MX2, and OAS1-were detected in multiple ovulation ET cattle using a real-time quantitative polymerase chain reaction, and receiver operating characteristic (ROC) curve analysis was performed. Gestational status was predicted using the average ISG levels during the normal estrous cycle (AVE) and the Youden index from the ROC curve analysis as cutoff values. The ISG15, MX1, and MX2 levels were significantly higher in pregnant cattle (n = 10) than in non-pregnant cattle (n = 23) on gestation day 21, whereas the levels of all ISGs were similar between non-pregnant and non-pregnant cattle with late embryonic death (n = 7). ISG15, MX1, and MX2 appropriately predicted the gestational status of ET cows. The statistical evaluation of the diagnostic accuracy in ET cows on day 21 of gestation presented higher values of sensitivity, specificity, accuracy, and positive predictive values of ISG15, MX1, and MX2 using the Youden index than using the AVE. Therefore, ISG15, MX1, and MX2 are excellent biomarkers of gestational status during the peri-implantation period in ET cattle.

Postnatal developmental expression and localization of apelin and apelin receptor protein in the ovary and uterus of mice

Postnatal ovarian and uterine development is crucial to accomplished female fertility. Thus, the investigations of factors that present in pre-pubertal stages are important as it might be responsible for the regulation of ovarian and uterine function. Apelin, an adipokine and its receptor (APJ) are present in female reproductive organs. However, no study has reported its postnatal expression in uterus and ovary. Thus, we investigated the postnatal developmental changes in expression and localization of apelin and APJ in the ovary and uterus of mice. Postnatal ovary and uterus were collected from postnatal day (PND) 1, 7, 14, 21, 42, 65 and performed western blot analysis and immunohistochemistry. Uterine APJ is elevated in PND14 and PND65, whereas, ovarian APJ elevated in PND7, PND14, and PND65. Apelin expression in both ovary and uterus showed intense staining at PND65 and PND14. Our results showed that apelin and APJ abundance was lower at PND21 in uterus and ovary. In conclusion, apelin and APJ are developmentally regulated in the ovary and uterus, and its localization in the different compartments of ovary and uterus suggest its distribution specific physiological role in the uterus and ovary.

Pregnancy stage-dependent modulation of neutrophil function may impact embryo survivability and pregnancy outcome in crossbred cows

Pregnancy is a complicated physiological process that involves synchronized coordination between immune and endocrine systems. Neutrophils have been suggested as a critical immune cell for embryo implantation and pregnancy maintenance. The present study was conducted to evaluate the dynamic changes in the mRNA expressions of the cluster of designation (CD11b, CD31, CD44 and CD62L) molecules and interferon-stimulated genes (ISG15, MX1 and OAS1) in blood neutrophils throughout pregnancy in dairy cows and correlate them with the outcome of pregnancy. Blood samples were taken from negative control (NC) group, and non-pregnant (NP) group at the time of artificial insemination (AI, day zero) and on days 10, 14, 16, 18, and 21 post-AI. In pregnant (P) cows, samples were taken as described above and after every 30 days until the time of parturition. In aborted cows, samples were collected until the time of the abortion. Comparison between pregnant, non-pregnant and aborted cows revealed that the expression of CD molecules increased (p < 0.05) on days 14, 16, 18 and 21 post-AI only in NP cows as compared to other groups. Although the expression of CD molecules remained constant throughout the study period in pregnant and aborted cows, the expression of CD11b, CD31 and CD62L increased (p < 0.05) on the day of abortion and parturition. Unlike CD molecules, the expression of CD44 decreased significantly (p < 0.05) at the time of abortion. There was a significant (p < 0.05) increase in the expression of interferon-stimulated genes including MX1, OAS1 and ISG15 during the peri-implantation period in pregnant cows, and at the time of abortion in aborted cows. However, the expression of ISGs was lower (p < 0.05) in non-pregnant cows as compared to the other groups. The results revealed the critical role played by neutrophils during pregnancy and form the basis to unravel the underlying mechanism for neutrophil associated immunological infertility in bovines.

History, insights, and future perspectives on studies into luteal function in cattle

The corpus luteum (CL) forms following ovulation from the remnant of the Graafian follicle. This transient tissue produces critical hormones to maintain pregnancy, including the steroid progesterone. In cattle and other ruminants, the presence of an embryo determines if the lifespan of the CL will be prolonged to ensure successful implantation and gestation, or if the tissue will undergo destruction in the process known as luteolysis. Infertility and subfertility in dairy and beef cattle results in substantial economic loss to producers each year. In addition, this has the potential to exacerbate climate change because more animals are needed to produce high-quality protein to feed the growing world population. Successful pregnancies require coordinated regulation of uterine and ovarian function by the developing embryo. These processes are often collectively termed "maternal recognition of pregnancy." Research into the formation, function, and destruction of the bovine CL by the Northeast Multistate Project, one of the oldest continuously funded Hatch projects by the USDA, has produced a large body of evidence increasing our knowledge of the contribution of ovarian processes to fertility in ruminants. This review presents some of the seminal research into the regulation of the ruminant CL, as well as identifying mechanisms that remain to be completely validated in the bovine CL. This review also contains a broad discussion of the roles of prostaglandins, immune cells, as well as mechanisms contributing to steroidogenesis in the ruminant CL. A triadic model of luteolysis is discussed wherein the interactions among immune cells, endothelial cells, and luteal cells dictate the ability of the ruminant CL to respond to a luteolytic stimulus, along with other novel hypotheses for future research.

Insights from two independent transcriptomic studies of the bovine corpus luteum during pregnancy

Several recent studies have used transcriptomics to investigate luteal changes during the maternal recognition of the pregnancy period in ruminants. Although these studies have contributed to our understanding of luteal function during early pregnancy, few attempts have been made to integrate information across these studies and distinguish key luteal transcripts or functions that are repeatably identified across multiple studies. Therefore, in this study, two independent studies of the luteal transcriptome during early pregnancy were combined and compared. In the first study, corpora lutea (CL) from day 20 of pregnancy were compared with CL collected on day 14 of pregnancy, prior to embryonic signaling. The cattle were nonlactating. In the second study, CL from day 20 of pregnancy were compared with CL collected from day 20 cyclic cattle that had been confirmed as not yet undergoing luteal regression. These were lactating cattle. Three methods were used to compare these two datasets, to identify key luteal regulators. In the first method, all transcripts with Benjamini-Hochberg-adjusted P-value (Q value) < 0.05 in both datasets were considered. This yielded 22 transcripts, including several classical interferon-stimulated genes, as well as regulators of transforming growth factor-beta (TGFB) and latent TGFB-binding proteins (LTBP)1 and 2. In the second, less conservative method, all transcripts with P < 0.01 and changed in the same direction in both datasets were considered. This yielded an additional 20 transcripts that were not identified in the first analysis, for a total of 42 common transcripts. These transcripts were regulators of functions such as inflammatory balance and matrix remodeling. In the third method, transcripts with Q < 0.10 were subject to pathway analysis, and common pathways were identified. Retinoic acid signaling and classical interferon signaling pathways were identified with this method. Finally, regulation by interferon tau (IFNT) was investigated. Among the 42 transcripts identified, 32 were regulated by IFNT in cultured luteal cells (Q < 0.05). Among those not regulated by IFNT were LTBP1 and 2, which are TGFB-binding proteins. In summary, common transcripts from two studies of the luteal transcriptome during early pregnancy were combined and shared changes were identified. This not only generated a list of potential key luteal regulators, which were mostly IFNT regulated, but also included transcripts not regulated by IFNT, including LTBP1 and 2.

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.

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.

Temporal changes in the corpus luteum during early pregnancy reveal regulation of pathways that enhance steroidogenesis and suppress luteolytic mechanisms†

Although rescue of the corpus luteum (CL) is required for pregnancy, luteal function during maternal recognition of pregnancy remains largely unexplored. CL were collected from pregnant cattle on days 14, 17, 20, and 23, to encompass the maternal recognition of pregnancy period. Next-generation sequencing was used to profile mRNA abundance during this time, while tandem mass spectrometry and nanostring technology were used to profile proteins and miRNA, respectively. A total of 1157 mRNA were differentially abundant, while 27 miRNA changed, and 29 proteins tended to change. mRNA that increased were regulators of interferon signaling and DNA repair, while those that decreased were associated with luteolytic processes, such as calcium signaling and matrix metallopeptidase (MMP) signaling, indicating inhibition of these processes. One of these, MMP12, was regulated by prostaglandin F2A in vitro. mRNA that were maximally abundant on day 20 were primarily associated with immune processes. Two of these, C-C motif chemokine ligand 1 and NFKB inhibitor alpha, were regulated by interferon tau in vitro. MiRNA that increased were predicted to inhibit phosphatidylinositol signaling, while those that decreased may be negative regulators of steroidogenesis. One protein that was greater on day 20 than on day 14 was aldehyde dehydrogenase 1 family member A1 (ALDH1A1), which synthesizes retinoic acid. Pharmacological inhibition of this enzyme, or of retinoic acid receptor signaling, led to suppression of progesterone production in vitro. Overall, these data indicate that there are changes in the CL of pregnancy that are important for continued luteal function.

Heat stress induces oxidative stress and activates the KEAP1-NFE2L2-ARE pathway in bovine endometrial epithelial cells

Heat stress adversely affects the reproductive function in cows. Although a relationship between heat stress and oxidative stress has been suggested, it has not been sufficiently verified in bovine endometrial epithelial cells. Here, we investigated whether oxidative stress is induced by heat stress in bovine endometrial epithelial cells under high temperature. Luciferase reporter assays showed that the reporter activity of heat shock element (HSE) and antioxidant responsive element (ARE) was increased in endometrial epithelial cells cultured under high temperature compared to that in cells cultured under basal (thermoneutral) temperature. Also, nuclear factor, erythroid 2 like 2 (NFE2L2), a master regulator of cellular environmental stress response, stabilized and the expression levels of antioxidant enzyme genes increased under high temperature. Immunostaining confirmed the nuclear localization of NFE2L2 in endometrial epithelial cells cultured under high temperature. Quantitative polymerase chain reaction analysis showed that the expression levels of representative inflammatory cytokine genes, such as prostaglandin-endoperoxide synthase 2 (PTGS2) and interleukin 8, were significantly decreased in endometrial epithelial cells cultured under high temperature compared to those in cells cultured under basal temperature. Thus, our results suggest that heat stress induces oxidative stress, whereas NFE2L2 plays a protective role in bovine endometrial epithelial cells cultured under heat stress conditions.

Cloprostenol, a synthetic analog of prostaglandin F2α induces functional regression in cultured luteal cells of felids†

In the present study, we investigated the effect of the synthetic analog of prostaglandin F2α (PGF2α)-cloprostenol-on cultured steroidogenic luteal cells of selected felid species over a 2-day culture period. The changes induced by cloprostenol were measured based on progesterone concentration and mRNA expression analysis of selected genes. Cloprostenol significantly reduced concentration of progesterone in cell culture medium of small luteal cells isolated from domestic cat corpora lutea (CL) at the development/maintenance stage (P < 0.05), but did not influence progesterone production in cultured cells from the regression stage. A decrease or complete silencing of progesterone production was also measured in cultured luteal cells of African lion (formation stage) and Javan leopard (development/maintenance stage). Gene-expression analysis by real-time PCR revealed that treatment with cloprostenol did not have an influence on expression of selected genes coding for enzymes of steroidogenesis (StAR, HSD3B, CYP11A1) or prostaglandin synthesis (PTGS2, PGES), nor did it effect hormone receptors (AR, ESR1, PGR, PTGER2), an anti-oxidative enzyme (SOD1) or factors of cell apoptosis (FAS, CASP3, TNFRSF1B, BCL2) over the studied period. Significant changes were measured only for expressions of luteinizing hormone (P < 0.05), prolactin (P < 0.05) and PGF2α receptors (P < 0.005) (LHCGR, PRLR, and PTGFR). The obtained results confirm that PGF2α/cloprostenol is a luteolytic agent in CL of felids and its impact on progesterone production depends on the developmental stage of the CL. Cloprostenol short-term treatment on luteal cells was associated only with functional but not structural changes related to luteal regression.

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.

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.

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.

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.

New approaches to diagnose and target reproductive failure in cattle

Reproductive failure and pregnancy loss in cattle are some of the largest economic burdens to cattle producers and one of most perplexing factors influencing management decisions. Pregnancy loss may occur at any point during gestation with the largest percentage of loss occurring in the first 30 days and, subsequently, decreasing as the pregnancy progresses. Losses may be attributed to numerous factors, predisposed issues or environmental conditions such as nutritional stressors or disease. From a research perspective, determining the exact causes of pregnancy loss or embryonic mortality in cattle have been difficult, due to limitations of accurately determining early gestation pregnancy status. Until methods that precisely determine embryo success early in gestation are available, our understanding of in vivo pregnancy loss will lack clarity necessary to develop management strategies to decrease such loss. In this review, we will briefly discuss the pivotal periods of pregnancy loss affecting beef and dairy cattle, methods and technologies to determine pregnancy status and embryo viability and potential opportunities to decrease reproductive failure.

Molecular profiling demonstrates modulation of immune cell function and matrix remodeling during luteal rescue†

The corpus luteum (CL) is essential for maintenance of pregnancy in all mammals and luteal rescue, which occurs around day 16-19 in the cow, is necessary to maintain luteal progesterone production. Transcriptomic and proteomic profiling were performed to compare the day 17 bovine CL of the estrous cycle and pregnancy. Among mRNA and proteins measured, 140 differentially abundant mRNA and 24 differentially abundant proteins were identified. Pathway analysis was performed using four programs. Modulated pathways included T cell receptor signaling, vascular stability, cytokine signaling, and extracellular matrix remodeling. Two mRNA that were less in pregnancy were regulated by prostaglandin F2A in culture, while two mRNA that were greater in pregnancy were regulated by interferon tau. To identify mRNA that could be critical regulators of luteal fate, the mRNA that were differentially abundant during early pregnancy were compared to mRNA that were differentially abundant during luteal regression. Eight mRNA were common to both datasets, including mRNA related to regulation of steroidogenesis and gene transcription. A subset of differentially abundant mRNA and proteins, including those associated with extracellular matrix functions, were predicted targets of differentially abundant microRNA (miRNA). Integration of miRNA and protein data, using miRPath, revealed pathways such as extracellular matrix-receptor interactions, abundance of glutathione, and cellular metabolism and energy balance. Overall, this study has provided a comprehensive profile of molecular changes in the corpus luteum during maternal recognition of pregnancy and has indicated that some of these functions may be miRNA-regulated.

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.

Circular RNA Gprc5a Promotes HCC Progression by Activating YAP1/TEAD1 Signalling Pathway by Sponging miR-1283

BACKGROUND

Circular RNA (circRNA) plays a critical role in tumorigenesis and tumor progression. Many studies indicate that circRNA Gprc5a is significantly upregulated and functions as an oncogene in a variety of cancers. However, the molecular mechanism of circGprc5a in liver cancer remains unclear.

METHODS

qRT-PCR was used to measure the expression levels of circGprc5a, miR-1283, YAP1 and TEAD1 mRNA in hepatocellular carcinoma (HCC) tissues or cells. YAP1 and TEAD1 protein levels were detected by Western blot. CCK-8 assay, cell colony formation, BrdU incorporation and Annexin V-FITC/PI assays were performed to analyze the effects of circGprc5a and miR-1283 on cell proliferation and apoptosis. The relationship between circGprc5a, miR-1283, YAP1 and TEAD1 was analyzed using bioinformatic analysis and luciferase. The tumor changes in mice were detected by in vivo experiments.

RESULTS

CircGprc5a was highly expressed in liver cancer, and closely related poor survival of patients with liver cancer. Knockout of circGprc5a inhibited proliferation of HCC and induced apoptosis. CircGprc5a activated the YAP1/TEAD1 signaling pathway by acting as a sponge for miR-1283. Furthermore, overexpression of miR-1283 abolished the promotion of circGprc5a on HCC cells. Therefore, miR-1283 expression correlated negatively with circGprc5a expression yet positively with the expression of YAP1/TEAD1 in liver cancer.

CONCLUSION

CircGprc5a promoted the development of HCC by inhibiting the expression of miR-1283 and activating the YAP1/TEAD1 signaling pathway.

Proteomics and transcriptomics study reveals the utility of ISGs as novel molecules for early pregnancy diagnosis in dairy cows

An early and precise diagnosis of pregnancy in cows is critical to short the calving interval and to improve their reproductive efficiency. Neutrophils are the first blood cells to sensitize the embryo in the uterus and participate in maternal recognition of pregnancy after getting induced by interferon tau (IFNτ). To study the protein abundance ratio, blood samples were collected on 0th, 10th, 18th and 36th day post-artificial insemination (AI) from crossbred Karan Fries cows. Neutrophils were isolated through density gradient centrifugation and studied for protein abundance by high-performance liquid chromatography coupled with mass spectrometry (LC-MS). Protein abundance ratios for Myxovirus resistance (MX1 and MX2) were found to be higher (P < 0.05) on day 10 and day 18 post-AI, whereas Oligoadenylate synthetase-1 (OAS1) and Interferon stimulated gene-15 ubiquitin-like modifier (ISG15) proteins were more abundant on day 18 post-AI. The relative mRNA expressions of these molecules were also studied by qPCR. The gene expression of ISG15, MX1, MX2 and OAS1 was found to be higher (P < 0.05) on day 10th, 18th and 36th post-AI compared to day 0. The study indicates that ISGs on blood neutrophils are essential for the establishment of pregnancy and may be targeted as potential biomarkers for pregnancy diagnosis in cows.

Pregnancy-associated changes of peroxisome proliferator-activated receptor delta (PPARD) and cytochrome P450 family 21 subfamily A member 2 (CYP21A2) expression in the bovine corpus luteum

We investigated gene expression profiles of the corpus luteum (CL) at the time of maternal recognition to evaluate the functional changes of the CL during early pregnancy in cows and help improve reproductive efficiency and avoid defective fetuses. Microarray analyses using a 15 K bovine oligo DNA microarray detected 30 differentially expressed genes and 266 differentially expressed genes (e.g., PPARD and CYP21A2) in the CL on pregnancy days 15 (P15) and 18 (P18), respectively, compared with the CL on day 15 (NP15) of non-pregnancy (n = 4 for each group). PPARD expression was the highest while the CYP21A2 expression was the lowest in P15 and P18 compared with that of NP15. These microarray results were validated by quantitative real-time PCR analysis. The addition of interferon-τ and supernatants derived from homogenized fetal trophoblast increased ISG15 and MX1 expressions in the cultured luteal tissue (P < 0.01), but did not affect PPARD and CYP21A2 expressions. PPARD expression in the luteal tissue was stimulated (P < 0.05) by GW0742, known as a selective PPARD agonist, and PPARD ligands (i.e., arachidonic, linoleic and linolenic acids). In contrast, CYP21A2 mRNA expression was not affected by both agonist and ligands. The concentration of prostaglandin (PG) E2 and PGF2α decreased after GW0742 stimulation and increased after arachidonic acid stimulation (P < 0.05). The addition of GW0742 and arachidonic acid increased progesterone (P4) concentration. Collectively, these findings suggest that high expression levels of PPARD and low expression levels of CYP21A2 in the CL during early pregnancy may support P4 production by bovine luteal cells.

Effect of summer heat stress on gene expression in bovine uterine endometrial tissues

Heat stress negatively affects reproductive functions in cows. Increased temperature disturbs fetal development in utero. However, the effect of heat stress on uterine endometrial tissues has not been fully examined. Using qPCR analysis, we measured the mRNA expression of various molecular markers in uterine endometrial tissue of dairy cows from Hokkaido, Japan, in winter and summer. Markers examined were heat shock proteins (HSPs), antioxidant enzymes (catalase, copper/zinc superoxide dismutase, manganese superoxide dismutase, and glutathione peroxidase 4), inflammatory cytokines, and interferon stimulated genes. Our results showed heat stress, body and milk temperatures were higher during summer than during winter. Expression levels of HSP27, HSP60, and HSP90 mRNA, and of catalase and copper/zinc superoxide dismutase mRNA were lower in summer than in winter. Tumor necrosis factor alpha expression was higher in summer than in winter. In conclusion, summer heat stress may reduce the expression of HSPs, affecting the levels of inflammatory cytokines in bovine uterine endometrial tissue.

Fertility response of lactating dairy cows subjected to three different breeding programs under subtropical conditions

Background

It is comprehensively recognized that reduced reproductive efficiency represents a great economic loss to dairy producers. Ovarian cysts and anestrus syndromes are considered the greatest significant causes of low reproductive efficiency in dairy herds worldwide as they detrimentally affect the longevity and profitability of dairy herd. Pregnancy rate is the best available single deciding parameter used for assessment of the reproductive efficiency at the herd level which measures the probability that open cows become pregnant per unit of time. So, the current study was planned to evaluate the suitability of using Ovsynch plus CIDR and G6G resynchronization protocols as an efficient treatment regimen for cystic ovarian diseased cows and anestrus cows, respectively, through comparing pregnancy rates of cystic ovarian diseased cows that subjected to Ovsynch supplemented with controlled internal drug release device with the pregnancy rate of healthy cows that subjected to a Presynch-Ovsynch synchronization protocol, as well as through comparing pregnancy rates of anestrus cows that subjected to G6G treatment protocol with the pregnancy rate of healthy cows. Moreover, possible factors such as breed, parity, and season which may affect the treatment success were also evaluated.

Results

The results of the current study revealed an overall mean pregnancy rate of 36.64%. Moreover, Simmental cows recorded a greater (p < 0.01) pregnancy rate (45.16%) than that recorded for Holstein cows (34.98%). A highly significant seasonal effect was observed, as a higher (p < 0.01) pregnancy rate was recorded for cows inseminated during cold months (39.54%) compared with that recorded for cows inseminated during hot months (29.18%).

Conclusions

No significant differences were detected in the pregnancy rates among the three breeding programs; thence, the application of the G6G synchronization protocol for anestrus cows and Ovsynch-CIDR synchronization protocol for cows with ovarian cysts could be used as effective treatment regimens as they resulted in nearly the same pregnancy rates that recorded for healthy cows. In addition, the treatment response was highly influenced by cow’s breed, parity, and season of breeding.

Interferon-Tau Exerts Direct Prosurvival and Antiapoptotic Actions in Luteinized Bovine Granulosa Cells

Interferon-tau (IFNT), serves as a signal to maintain the corpus luteum (CL) during early pregnancy in domestic ruminants. We investigated here whether IFNT directly affects the function of luteinized bovine granulosa cells (LGCs), a model for large-luteal cells. Recombinant ovine IFNT (roIFNT) induced the IFN-stimulated genes (ISGs; MX2, ISG15, and OAS1Y). IFNT induced a rapid and transient (15–45 min) phosphorylation of STAT1, while total STAT1 protein was higher only after 24 h. IFNT treatment elevated viable LGCs numbers and decreased dead/apoptotic cell counts. Consistent with these effects on cell viability, IFNT upregulated cell survival proteins (MCL1, BCL-xL, and XIAP) and reduced the levels of gamma-H2AX, cleaved caspase-3, and thrombospondin-2 (THBS2) implicated in apoptosis. Notably, IFNT reversed the actions of THBS1 on cell viability, XIAP, and cleaved caspase-3. Furthermore, roIFNT stimulated proangiogenic genes, including FGF2, PDGFB, and PDGFAR. Corroborating the in vitro observations, CL collected from day 18 pregnant cows comprised higher ISGs together with elevated FGF2, PDGFB, and XIAP, compared with CL derived from day 18 cyclic cows. This study reveals that IFNT activates diverse pathways in LGCs, promoting survival and blood vessel stabilization while suppressing cell death signals. These mechanisms might contribute to CL maintenance during early pregnancy.

The transfer of parthenogenetic embryos following artificial insemination in cows can enhance pregnancy recognition via the secretion of interferon tau

Repeat breeding is a reproductive disorder in cattle. Embryo transfer following artificial insemination (AI) improves pregnancy rate by replenishing interferon tau (IFNT), but it results in a notably higher rate of twin occurrence. This study hypothesized that parthenogenetic (PA) embryo transfer following AI (AI + PA) could improve the conception rate because that PA embryo become as a supplemental source of IFNT without twins. PA embryos showed higher IFNT mRNA expression than in vitro fertilization (IVF) embryos. An examination of the effect of the cultured conditioned media (CM) of PA or IVF embryos on Madin-Darby bovine kidney cells with stably introduced promoter-reporter constructs of interferon-stimulated gene 15 (ISG15, marker of IFN response) showed higher stimulation levels of ISG15 promoter activity with PA than with IVF embryo. We investigated in vivo the effect of AI + PA on healthy Japanese Black cattle. Cattle transferred with PA embryo alone were non-fertile, but those that underwent AI + PA showed a pregnancy rate of 53.3%, the similar as that with AI alone (60%). In pregnant cattle in AI + PA group, adding the PA embryo upregulated the expression of ISGs and plasma progesterone concentration. No twin were generated in AI only and AI + PA groups. Using repeat breeding Holstein cows that did not become pregnant with 4-9 times of AI, transfer of PA embryo following AI resulted in a higher pregnancy rate than that of control (AI only). We suggest that AI + PA may be beneficial for improving maternal pregnancy recognition in repeat breeder cattle while avoiding twin generation.

Inflammation and angiogenesis in the corpus luteum

Angiogenesis is a very important process that helps establish and maintain the normal structure and function of the corpus luteum (CL). Early luteal development can be considered a kind of physiological injury with an inflammatory response; therefore, the inflammatory response may play an important role in the luteal angiogenesis. The inflammatory response is companied by activated leukocytes and their mediators. For luteal tissue, numerous activated leukocytes such as macrophages, neutrophils and eosinophils are present in the early luteal phase and are widely involved in neovascularization. The objective of this review is to describe the role of the inflammatory factors in the angiogenesis and to discuss their mechanism. Knowledge of action and mechanism of these inflammatory factors on angiogenic activity will be beneficial for the understanding of luteal function.

Implantation associated divergence in neutrophil glucocorticoid and cysteine-X-cysteine receptor genes in cattle

The differential roles of Interferon-tau (IFNT) and Progesterone (P₄) in triggering pro- and anti-inflammatory responses during peri-implantation period were assessed in cows. An ex vivo study was done by isolating neutrophils from the animals post artificial insemination (AI) at defined intervals and analyzing the expression changes of Glucocorticoid receptor-α (GRα) and Interleukin-8 receptor (CXCR1) genes. An in vitro study was also done isolating neutrophils from prepubertal heifers subjecting them to IFNT and Progesterone P₄ supplementation separately. We observed that from day 14 post Artificial Insemination, there is a significant up-regulation of neutrophil GRα and CXCR1 in pregnant and non-pregnant cows respectively. The in vitro study showed that IFNT significantly up-regulates GRα whereas P₄ significantly up-regulates CXCR1. The total leukocyte count and neutrophil count were also significantly higher in non-pregnant cows. We conclude that IFNT efficiently mediates neutrophil immunosuppression during peri-implantation period in cows by interacting with Interleukin 8 receptor and can also exert ligand independent actions on GRα.

Genomic merit for reproductive traits. II: Physiological responses of Holstein heifers

Fertility traits were recently added to the evaluation of genetic merit, allowing for the selection of Holstein cattle with improved reproductive performance. In the current study, we investigated the associations among genomic merit for daughter pregnancy rate (GDPR) and heifer conception rate (GHCR) and physiological responses during proestrus and diestrus. Holstein heifers (n = 99) were classified based on GDPR [high = 3.26 ± 0.76 (1.6 to 5.3), n = 48; low = -0.17 ± 0.75 (-1.8 to 1.0), n = 51] and GHCR [high = 2.75 ± 0.77 (1.5 to 5.5), n = 49; low = 0.06 ± 0.67 (-2.1 to 1.2), n = 50]. Heifers were fitted with an automated estrous detection device, were treated with PGF_2α for synchronization of estrus, and received either artificial insemination or embryo transfer at detected estrus. Blood was sampled at the time of PGF_2α treatment, within 24 h of the onset of estrus (d 0), and on d 7, 14, 19 ± 2, 28, and 35. Blood samples from all heifers were analyzed for concentrations of estradiol (d 0) and progesterone (on the day of PGF_2α treatment and d 0, 7, and 14). Blood samples from heifers pregnant on d 38 ± 3 were analyzed for concentrations of progesterone (d 0, 7, 14, 19 ± 2, 28, and 35), pregnancy-specific protein B (d 19 ± 2, 28, and 35), and insulin-like growth factor 1 (d 0, 7, 14, 19 ± 2, 28, and 35). Expression of mRNA for interferon-stimulated gene 15 in peripheral leukocytes isolated from blood collected on d 19 ± 2 was determined. Ovaries were scanned by ultrasound daily from d 0 to 4 or until ovulation was detected. Heifers with low GHCR tended to be less likely to be detected in estrus (78.0 vs. 91.8%). Estradiol concentration on d 0 was greater for heifers with high GDPR (4.53 ± 0.23 vs. 3.79 ± 0.23 pg/mL). The ovulatory follicle was larger for heifers with high GDPR (16.28 ± 0.33 vs. 14.55 ± 0.35 mm), whereas heifers with high GHCR tended to have smaller ovulatory follicles (15.00 ± 0.31 vs. 15.83 ± 0.37 mm). Heifers with high GDPR tended to be more likely to ovulate within 96 h of the onset of estrus (90.7 vs. 75.0%). Among heifers pregnant on d 38 ± 3, GDPR and GHCR were not associated with mRNA expression for interferon-stimulated gene 15. Heifers with high GDPR had greater concentration of pregnancy-specific protein B from d 28 to 35 (3.03 ± 0.15 vs. 2.48 ± 0.1 ng/mL). Heifers with high GHCR tended to have greater insulin-like growth factor 1 concentration from d 7 to 35 (108.0 ± 3.2 vs. 97.7 ± 4.2 ng/mL). Our results suggest that selection for Holstein cattle for GDPR may have positive effects on reproductive performance through changes in ovarian follicle development and steroidogenesis. Although selection of Holstein cattle for GHCR may negatively affect estrous expression by affecting ovarian follicle growth, selection for GHCR may improve reproductive performance by altering the somatotropic axis.

Parthenogenetic bovine embryos secrete type I interferon capable of stimulating ISG15 in luteal cell culture

Interferon tau (IFNT) is the pregnancy recognition signal in ruminants and is secreted by trophoblast cells. Paracrine action in the endometrium is well established by inhibiting luteolytic pulses of prostaglandin F2 alpha. Recently, endocrine action was documented in the corpus luteum, blood cell and liver. It was hypothesized that conditioned medium (CM) obtained from days 7, 9 and 12 parthenogenetic embryos alters luteal cell gene expression. The aim was to establish a bovine mixed luteal cell culture to evaluate cellular response associated to interferon stimulated genes, steroidogenesis and apoptosis. Conditioned medium was obtained from Days 7, 9 and 12 parthenogenetic (PA) embryos culture. Moreover, antiviral assay was performed on CM from Days 7, 9 and 12 to verify Type I interferon activity. Luteal cell culture was validated by steroidogenic and apoptotic genes (CYP11A1 , HSD3B1, BAX, BCL2, AKT and XIAP mRNA expression), and concentration of progesterone as endpoint. Luteal cell culture was treated with interferon alpha (IFNA) and CM from parthenogenetic embryos. Antiviral assay revealed Type I interferon activity on CM from embryos increasing on Days 9 and 12. ISG15 mRNA was greater in the mixed luteal cells culture treated with 1, 10 and 100ng/ml of interferon alpha (IFNA) and also on Days 7, 9 and 12 CM treatments. Concentration of progesterone was not altered in luteal cell culture regardless of treatments. Steroidogenic and apoptotic genes were similar among groups in luteal cell culture treated with different doses of IFNA or CM from PA embryos. In conclusion, parthenogenetic embryo-derived CM has antiviral activity, luteal cell culture respond to Type I interferon by expressing IGS15. These data indicate this model can be used for IFNT endocrine signaling studies.

Integration of molecules to construct the processes of conceptus implantation to the maternal endometrium

During the peri-implantation period, ruminant conceptuses go through rapid elongation, followed by their attachment to the uterine endometrial epithelial cells, during which interferon-tau (IFNT), a trophectodermal cytokine required for the process of maternal recognition of pregnancy, is expressed in a temporal and spatial manner. On day 22 (day 0 = day of estrus), 2 to 3 d after the initiation of bovine conceptus attachment to the uterine epithelium, when IFNT production begins to subside, the expression of molecules related to epithelial-mesenchymal transition, zinc finger E-box binding homeobox 1, snail family transcriptional repressor 2, N-cadherin, and vimentin was found in the trophectoderm. Through the use of in vitro coculture system with bovine trophoblast CT-1 and endometrial epithelial cells, a series of experiments have been conducted to elucidate mechanisms associated with the regulation of IFNT gene transcription and conceptus implantation, including epithelial-mesenchymal transition processes. Expression of IFNT, both up- and downregulation, during the peri-implantation period is tightly controlled. Cytokines and cell adhesion molecules such as epidermal growth factor, basic fibroblast growth factor, transforming growth factor beta, activin A, L-selectin-podocalyxin, and vascular cell adhesion molecule 1-integrin α4 expressed in utero all contribute to the initiation of epithelial-mesenchymal transition in the trophectoderm. These results indicate that conceptus implantation to the uterine endometrium proceeds while elongated conceptuses and endometria express cell adhesion molecules and their receptors, and the trophectoderm experiences epithelial-mesenchymal transition. Data accumulated suggest that while the conceptus and the endometrial epithelium adhere, trophectodermal cells must gain more flexibility for binucleate and possibly trinucleate cell formation during the peri-implantation period, and that understanding and constructing the conditions throughout implantation processes is key to improving ruminants' fertility.

Gene expression of CCL8 and CXCL10 in peripheral blood leukocytes during early pregnancy in cows

Background

The aim of the present study was to evaluate CCL8 and CXCL10 expression and its regulatory mechanism in peripheral blood leukocytes (PBLs) at the time of maternal recognition in cows. Blood samples were collected on 14, 15, 16, 17 and 18 d after artificial insemination (AI). Based on the day of return of estrus, cows were divided into three groups, pregnant (n = 5), early embryonic mortality (EEM; n = 5) and late embryonic mortality (LEM; n = 5). The gene expression levels in PBLs were assessed with quantitative real-time reverse transcription PCR.

Results

The expression of CCL8 and CXCL10 mRNA in PBLs gradually increased from 14 to 18 d of pregnant cows and significant differences were observed on 18 d (P < 0.05), whereas no significant changes were observed both in EEM and LEM cows. Interferon-stimulated protein 15 kDa (ISG15), myxovirus-resistance gene (MX) 1 and MX2 mRNA expression in PBLs increased from 14 to 18 d which was significant on 18 d of pregnant cows as well as in LEM cows (P < 0.05), but no changes were observed in EEM cows. To determine whether the expression of CCL8 and CXCL10 in PBLs was regulated by pregnancy-related substances or not, expression level was assessed after exposure to interferon-τ (IFNT) and CCL16. Monocytes, granulocytes and lymphocytes were obtained using density-gradient centrifugation and flow cytometry. The addition of IFNT (100 ng/mL) and CCL16 (100 ng/mL) to cultured PBLs increased the expression of CCL8 and CXCL10 mRNA (P < 0.05). The expression of ISG15, MX1 and MX2 mRNA in PBLs was also stimulated by IFNT and CCL16 (P < 0.05).

Conclusions

The expression of CCL8 and CXCL10 genes increased in PBLs during early pregnancy. Since IFNT stimulated CCL8 and CXCL10 expression in cultured PBLs, the increase of CCL8 and CXCL10 might be pregnancy-dependent events. The expression of both CCL8 and CXCL10 in PBLs was stimulated by CCL16 as well as IFNT, suggesting a chemokine interaction that at least includes CCL8, CXCL10 and CCL16, and may play a role in regulating maternal recognition in cows.

Paracrine and endocrine actions of interferon tau (IFNT)

This review focuses on the paracrine and endocrine actions of interferon tau (IFNT) during pregnancy recognition and establishment in ruminants. Pregnancy recognition involves the suppression of the endometrial luteolytic mechanism by the conceptus to maintain progesterone production by the corpus luteum (CL). The paracrine antiluteolytic effects of conceptus-derived IFNT inhibit upregulation of oxytocin receptors in the endometrial epithelia of the uterus, thereby preventing the production of luteolytic prostaglandin F2 alpha (PGF2α) pulses. In the endometrium, IFNT induces or upregulates a large number of classical IFN-stimulated genes (ISGs) and regulates expression of many other genes in a cell-specific manner that are likely important for conceptus elongation, implantation and establishment of pregnancy. Further, IFNT has endocrine effects on extrauterine cells and tissues. In sheep, IFNT induces luteal resistance to PGF2α, thereby ensuring survival of the CL for maintenance of pregnancy. The ISGs induced in circulating peripheral blood mononuclear cells by IFNT may also be useful as an indicator of pregnancy status in cattle. An increased knowledge of IFNT and ISGs is important to improve the reproductive efficiency in ruminants.

Chronicling the discovery of interferon tau

It has been 38 years since a protein, now known as interferon tau (IFNT), was discovered in ovine conceptus-conditioned culture medium. After 1979, purification and testing of native IFNT revealed its unique antiluteolyic activity to prevent the regression of corpora lutea on ovaries of nonpregnant ewes. Antiviral, antiproliferative and immunomodulatory properties of native and recombinant IFNT were demonstrated later. In addition, progesterone and IFNT were found to act cooperatively to silence expression of classical interferon stimulated genes in a cell-specific manner in ovine uterine luminal and superficial glandular epithelia. But, IFNT signaling through a STAT1/STAT2-independent pathway stimulates expression of genes, such as those for transport of glucose and amino acids, which are required for growth and development of the conceptus. Further, undefined mechanisms of action of IFNT are key to a servomechanism that allows ovine placental lactogen and placental growth hormone to affect the development of uterine glands and their expression of genes throughout gestation. IFNT also acts systemically to induce the expression of interferon stimulated genes that influence secretion of progesterone by the corpus luteum. Finally, IFNT has great potential as a therapeutic agent due to its low cytotoxicity, anti-inflammatory properties and effects to mitigate diabetes, obesity-associated syndromes and various autoimmune diseases.

Interferon-tau promotes luteal endothelial cell survival and inhibits specific luteolytic genes in bovine corpus luteum

Interferon-tau (IFNT), a maternal recognition of pregnancy (MRP) signals in domestic ruminants, suppresses the release of luteolytic pulses of uterine prostaglandin F2a (PGF2a), thus extending the corpus luteum (CL) life span. We hypothesized that IFNT also exerts anti-luteolytic actions in bovine CL. To examine the direct effects of IFNT on bovine CL, luteal slices and enriched luteal endothelial cells (LECs) were utilized. We found that recombinant ovine IFNT (roIFNT) markedly elevates interferon-associated genes (STAT1, STAT2 and IRF9) and interferon-stimulated genes (ISGs: MX2, ISG15 and OAS1Y) in both models. Furthermore, IFNT time-dependently induced STAT1 phosphorylation in LECs without affecting total STAT1. roIFNT-stimulated viable LECs numbers and the knockdown of protein inhibitor of activated STAT1 (PIAS1) abolished this effect, suggesting that PIAS1 may mediate the proliferative effect of IFNT. IFNT significantly downregulated luteolytic genes such as TGFB1, thrombospondin-1 (THBS1), endothelin-1 (EDN1) and serpin family E member-1 (SERPINE1) in LECs. However, less robust effects were observed in luteal slices. Moreover, PGF2a alone induced THBS1, SERPINE1 and EDN1 mRNA in CL slices whereas in the presence of IFNT, THBS1 and SERPINE1 stimulation was abolished. Collectively, these results indicate that IFNT acts via STAT1- IRF9-dependent and independent pathways and affects diverse luteal functions. Most interestingly, this study suggests the existence of an anti-luteolytic effect of IFNT in bovine CL, namely, inhibiting key PGF2a-induced luteolytic genes. The proliferative effect of IFNT may constitute an additional mechanism that promotes luteal cell survival, thus, extending the luteal life span during early pregnancy in cows.

Trends in recombinant protein use in animal production

Recombinant technologies have made possible the production of a broad catalogue of proteins of interest, including those used for animal production. The most widely studied proteins for the animal sector are those with an important role in reproduction, feed efficiency, and health. Nowadays, mammalian cells and fungi are the preferred choice for recombinant production of hormones for reproductive purposes and fibrolytic enzymes to enhance animal performance, respectively. However, the development of low-cost products is a priority, particularly in livestock. The study of cell factories such as yeast and bacteria has notably increased in the last decades to make the new developed reproductive hormones and fibrolytic enzymes a real alternative to the marketed ones. Important efforts have also been invested to developing new recombinant strategies for prevention and therapy, including passive immunization and modulation of the immune system. This offers the possibility to reduce the use of antibiotics by controlling physiological processes and improve the efficacy of preventing infections. Thus, nowadays different recombinant fibrolytic enzymes, hormones, and therapeutic molecules with optimized properties have been successfully produced through cost-effective processes using microbial cell factories. However, despite the important achievements for reducing protein production expenses, alternative strategies to further reduce these costs are still required. In this context, it is necessary to make a giant leap towards the use of novel strategies, such as nanotechnology, that combined with recombinant technology would make recombinant molecules affordable for animal industry.

Induction of IFNT-Stimulated Genes by Conceptus-Derived Exosomes during the Attachment Period

Biochemical and/or physical communication between the conceptus and the uterine endometrium is required for conceptus implantation to the maternal endometrium, leading to placentation and the establishment of pregnancy. We previously reported that in vitro co-culture system with bovine trophoblast CT-1 cells, primary uterine endometrial epithelial cells (EECs), and uterine flushings (UFs) mimics in vivo conceptus attachment process. To identify molecules in UFs responsible for this change, we first characterized protein contents of UFs from day 17 cyclic (C17) and pregnant (P17) ewes through the use of two dimensional-Polyacrylamide Gel Electrophoresis (2D-PAGE), followed by Liquid Chromatography-tandem Mass Spectrometry (LC-MS/MS) analysis. These analyses identified 266 proteins specific for P17 UFs, from which 172 proteins were identified as exosomal proteins. Among 172 exosomal proteins, 8 proteins that had been identified as exosomal proteins were chosen for further analysis, including macrophage-capping protein (CAPG), aldo-keto reductase family 1, member B1 protein (AKR1B1), bcl-2-like protein 15 (BCL2L15), carbonic anhydrase 2 (CA2), isocitrate dehydrogenase 2 (IDH2), eukaryotic translation elongation factor 2 (EEF2), moesin (MSN), and ezrin (EZR). CAPG and AKR1B1 were again confirmed in P15 and P17 UFs, and more importantly CAPG and AKR1B1, mRNA and protein, were found only in P15 and P17 conceptuses. Moreover, exosomes were isolated from C15, C17, P15, or P17 UFs. Only P15 and P17 exosomes, originated from the conceptus, contained interferon tau (IFNT) as well as CAPG and AKR1B1, and up-regulated STAT1, STAT2, MX1, MX2, BST2, and ISG15 transcripts in EECs. These observations indicate that in addition to endometrial derived exosomes previously described, conceptus-derived exosomes are present in UFs and could function to modify endometrial response. These results suggest that exosomes secreted from conceptuses as well as endometria are involved in cell to cell interactions for conceptus implantation to the maternal endometrium.