The contribution of the maternal immune system to the establishment of pregnancy in cattle

Endometrial distribution of bovine immune cells in relation to days to conception after parturition

In dairy cows, the processes involved in the resolution of uterine inflammation during the postpartum are closely related to improved fertility during the subsequent lactation period. Little is known, however, about the role and distribution of endometrial immune cell populations during the pre-implantation period. This study was aimed to analyze the endometrial distribution of several mononuclear immune cells (T cells, γδ T cells, B cells and macrophages) in healthy dairy cows during the postpartum, beyond the transition period, looking for its possible association with the parturition-conception interval (PCI) and delayed conception. The quantification of immune cells was evaluated by immunohistochemistry (IHC), and the expression of hormone receptors in immune cells was evaluated by double IHC. Dairy cows were grouped according to their PCI: PCI shorter than or equal to 90 DIM (PCI≤90), PCI between 90 and 120 DIM (PCI90-120), and PCI greater than 150 DIM (PCI≥150). The distribution of endometrial mononuclear immune cells was analyzed by a Generalized Linear Model, and the association of the distribution of mononuclear immune cells with delayed conception was evaluated with a Kaplan-Meier test. The cows from the PCI90-120 group showed the highest number of endometrial macrophages, and a lower number of B cells than the PCI≤90 group. Results also showed an association between the lower number of B cells in the endometrium during the pre-implantation period and earlier conception. Also, the present findings indicates that ESR and PR are expressed in the endometrial MØ, T cells, γδ T cells and B cells.

Ovarian leukocytes: Association with follicular persistence and cyst formation in dairy cows

One of the initial causes of cystic ovarian disease (COD) is a failure in the normal ovulation mechanism. This study aimed to characterize the populations of immune cells (T-lymphocytes, B-lymphocytes, monocytes-macrophages and granulocytes) present in the ovary of cows with COD and induced follicular persistence, and evaluate their relation with follicular persistence and cyst formation. The follicular persistence model was developed using a progesterone (P4) slow-release intravaginal device, to obtain subluteal concentrations of P4. Results evidenced that T-lymphocytes, B-lymphocytes and monocytes-macrophages in the cortex, medulla, and theca externa and interna of dominant follicles were higher in the control group than in the COD and all persistence groups. Granulocytes in the medulla and theca externa of dominant follicles were lower in the control group than in the COD group, and those in the cortex and medulla were lower in the control group than in the persistence groups. The presence of T-lymphocytes, B-lymphocytes and granulocytes in the follicular fluid was abundant, especially that of granulocytes, without differences between control and COD cows. These results suggest that the immune system potentially plays a role in the local mechanisms of COD pathogenesis in dairy cows. In spontaneous COD and in our follicular persistence model, the distribution of the cells studied was different from that in the control group. However, to our knowledge, this is the first report describing the presence of immune cells in bovine follicular fluid samples and the expression of steroid hormone receptors in infiltrating immune cells in the bovine ovary.

Adipokines in pregnancy

Reproductive success consists of a sequential events chronology, starting with the ovum fertilization, implantation of the embryo, placentation, and cellular processes like proliferation, apoptosis, angiogenesis, endocrinology, or metabolic changes, which taken together finally conduct the birth of healthy offspring. Currently, many factors are known that affect the regulation and proper maintenance of pregnancy in humans, domestic animals, or rodents. Among the determinants of reproductive success should be distinguished: the maternal microenvironment, genes, and proteins as well as numerous pregnancy hormones that regulate the most important processes and ensure organism homeostasis. It is well known that white adipose tissue, as the largest endocrine gland in our body, participates in the synthesis and secretion of numerous hormones belonging to the adipokine family, which also may regulate the course of pregnancy. Unfortunately, overweight and obesity lead to the expansion of adipose tissue in the body, and its excess in both women and animals contributes to changes in the synthesis and release of adipokines, which in turn translates into dramatic changes during pregnancy, including those taking place in the organ that is crucial for the proper progress of pregnancy, i.e. the placenta. In this chapter, we are summarizing the current knowledge about levels of adipokines and their role in the placenta, taking into account the physiological and pathological conditions of pregnancy, e.g. gestational diabetes mellitus, preeclampsia, or intrauterine growth restriction in humans, domestic animals, and rodents.

Genome-wide association and functional annotation analysis for the calving interval in Nellore cattle

Calving interval (CI) measures the number of days between two consecutive calves of the same cow, and previous studies based on phenotype and pedigree data reported low heritability for this trait. However, the genetic architecture of CI in the Nellore breed was not evaluated based on genomic data. Thus, this study aimed to estimate the heritability based on genomic data and carry out a genome-wide association study (GWAS) for CI in the Nellore breed, using 12,599 pedigree records, 5078 CI records, and 3818 animals genotyped with 50k SNPchip panel. Both quality control and GWAS were performed in BLUPF90 family packages, which use the single-step genomic best linear unbiased predictor (ssGBLUP) method. The average CI was 427.6 days, with a standard deviation of 106.9 and a total range of 270-730 days. The heritability estimate was 0.04 ± 0.04. The p-values of GWAS analysis resulted in a genomic inflation factor (lambda) of 1.08. The only significant SNP (rs136725686) at the genome-wide level (p-value = 1.53E-06) was located on BTA13. Other 19 SNPs were significant at the chromosome-wide level, distributed on BTA1, 2, 3, 6, 10, 13, 14, 17, 18, 22, and 26. Functional annotation analysis found thirty-six protein-coding genes, including genes related to cell cycle (RAD21, BCAR3), oocyte function (LHX8, CLPX, UTP23), immune system (TXK, TEC, NFATC2), endocrine function (LRRFIP2, GPR158), estrous cycle (SLC38A7), and female fertility (CCK, LYZL4, TRAK1, FOXP1, STAC). Therefore, CI is a complex trait with small heritability in Nellore cattle, and various biological processes may be involved with the genetic architecture of CI in Nellore cattle.

Effects of recombinant osteopontin expressed in Escherichia coli on the recovery of the endometrial epidermal growth factor profile and fertility in repeat breeder dairy cows

Endometrial epidermal growth factor (EGF) shows a cyclic change with two peaks on days 2-4 and days 13-14 of the estrous cycle. In repeat breeder cows, loss of the peaks has been associated with reduced fertility. By infusing seminal plasma (SP) and osteopontin (OPN) derived from SP and milk into the vagina, their EGF profile and fertility are restored. However, SP is difficult to obtain, and both SP and OPN can transmit infectious diseases. While OPN can be sourced from recombinant protein without this risk, recombinant bovine OPN (rOPN) expressed in Escherichia coli should be examined for its effects on the EGF profile, since it does not undergo posttranslational modification, which is important for its biological activity. In study 1, PBS, SP (0.5 mL), and rOPN (0.3 mg) were infused into the vagina at estrus (day 0) in 74, 37, and 105 repeat breeder Holstein cows, respectively, with an altered EGF profile. The endometrial EGF concentrations were measured on day 3. Some cows (n = 58, 20, and 83, respectively) were inseminated immediately before the infusion and then diagnosed for pregnancy between days 30 and 35. The normalization rate of the EGF profile and conception rate in the rOPN group (58.1 % and 47.0 %, respectively) were not significantly different from those in the SP group (62.2 % and 45.0 %, respectively) but higher than those in PBS group (29.7 % and 28.1 %, respectively) (P < 0.05). In study 2, repeat breeder cows with an altered EGF profile were infused with PBS (n = 18) and rOPN (n = 17), while fertile controls with a normal EGF profile (n = 18) were infused with PBS. Two or three embryos were transferred into cows on day 7 and then recovered on day 14. Embryo recovery rates of the rOPN and fertile groups were comparable (58.7 % vs. 58.3 %) but higher than that of the PBS group (58.7 % vs. 32.0 %) (P < 0.05). The embryo recovery rate of cows with normalized EGF profile was higher than that of cows with unnormalized EGF profile (64.4 % vs. 16.7 %) (P < 0.05). The embryo sizes of cows in the rOPN and fertile groups were comparable but larger than those in the PBS group (P < 0.05). However, the embryo size was not correlated to the corresponding endometrial EGF concentrations. In conclusion, rOPN without posttranslational modifications normalized the EGF profile in repeat breeder cows. Improved fertility by normalization of the EGF profile could be attributed partly to the increased embryo viability up to day 14.

Mapping Expression Quantitative Trait Loci Targeting Candidate Genes for Pregnancy in Beef Cows

Despite collective efforts to understand the complex regulation of reproductive traits, no causative genes and/or mutations have been reported yet. By integrating genomics and transcriptomics data, potential regulatory mechanisms may be unveiled, providing opportunities to dissect the genetic factors governing fertility. Herein, we identified regulatory variants from RNA-Seq data associated with gene expression regulation in the uterine luminal epithelial cells of beef cows. We identified 4676 cis and 7682 trans eQTLs (expression quantitative trait loci) affecting the expression of 1120 and 2503 genes, respectively (FDR < 0.05). These variants affected the expression of transcription factor coding genes (71 cis and 193 trans eQTLs) and genes previously reported as differentially expressed between pregnant and nonpregnant cows. Functional over-representation analysis highlighted pathways related to metabolism, immune response, and hormone signaling (estrogen and GnRH) affected by eQTL-regulated genes (p-value ≤ 0.01). Furthermore, eQTLs were enriched in QTL regions for 13 reproduction-related traits from the CattleQTLdb (FDR ≤ 0.05). Our study provides novel insights into the genetic basis of reproductive processes in cattle. The underlying causal mechanisms modulating the expression of uterine genes warrant further investigation.

Extensive rewiring of the gene regulatory interactions between in vitro-produced conceptuses and endometrium during attachment

Pregnancy loss is a significant problem when embryos produced in vitro are transferred to a synchronized uterus. Currently, mechanisms that underlie losses of in vitro-produced embryos during implantation are largely unknown. We investigated this problem using cattle as a model of conceptus attachment by analyzing transcriptome data of paired extraembryonic membrane and endometrial samples collected on gestation days 18 and 25, which spans the attachment window in cattle. We identified that the transfer of an in vitro-produced embryo caused a significant alteration in transcript abundance of hundreds of genes in extraembryonic and endometrial tissues on gestation days 18 and 25, when compared to pregnancies initiated by artificial insemination. Many of the genes with altered transcript abundance are associated with biological processes that are relevant to the establishment of pregnancy. An integrative analysis of transcriptome data from the conceptus and endometrium identified hundreds of putative ligand-receptor pairs. There was a limited variation of ligand-receptor pairs in pregnancies initiated by in vitro-produced embryos on gestation day 18, and no alteration was observed on gestation day 25. In parallel, we identified that in vitro production of embryos caused an extensive alteration in the coexpression of genes expressed in the extraembryonic membranes and the corresponding endometrium on both gestation days. Both the transcriptional dysregulation that exists in the conceptus or endometrium independently and the rewiring of gene transcription between the conceptus and endometrium are a potential component of the mechanisms that contribute to pregnancy losses caused by in vitro production of embryos.

Paternal effects on fetal programming

Paternal programming is the concept that the environmental signals from the sire's experiences leading up to mating can alter semen and ultimately affect the phenotype of resulting offspring. Potential mechanisms carrying the paternal effects to offspring can be associated with epigenetic signatures (DNA methylation, histone modification and non-coding RNAs), oxidative stress, cytokines, and the seminal microbiome. Several opportunities exist for sperm/semen to be influenced during development; these opportunities are within the testicle, the epididymis, or accessory sex glands. Epigenetic signatures of sperm can be impacted during the pre-natal and pre-pubertal periods, during sexual maturity and with advancing sire age. Sperm are susceptible to alterations as dictated by their developmental stage at the time of the perturbation, and sperm and seminal plasma likely have both dependent and independent effects on offspring. Research using rodent models has revealed that many factors including over/under nutrition, dietary fat, protein, and ingredient composition (e.g., macro- or micronutrients), stress, exercise, and exposure to drugs, alcohol, and endocrine disruptors all elicit paternal programming responses that are evident in offspring phenotype. Research using livestock species has also revealed that sire age, fertility level, plane of nutrition, and heat stress can induce alterations in the epigenetic, oxidative stress, cytokine, and microbiome profiles of sperm and/or seminal plasma. In addition, recent findings in pigs, sheep, and cattle have indicated programming effects in blastocysts post-fertilization with some continuing into post-natal life of the offspring. Our research group is focused on understanding the effects of common management scenarios of plane of nutrition and growth rates in bulls and rams on mechanisms resulting in paternal programming and subsequent offspring outcomes. Understanding the implication of paternal programming is imperative as short-term feeding and management decisions have the potential to impact productivity and profitability of our herds for generations to come.

Understanding the underlying genetic mechanisms for age at first calving, inter-calving period and scrotal circumference in Bonsmara cattle

BACKGROUND

Reproduction is a key feature of the sustainability of a species and thus represents an important component in livestock genetic improvement programs. Most reproductive traits are lowly heritable. In order to gain a better understanding of the underlying genetic basis of these traits, a genome-wide association was conducted for age at first calving (AFC), first inter-calving period (ICP) and scrotal circumference (SC) within the South African Bonsmara breed. Phenotypes and genotypes (120,692 single nucleotide polymorphisms (SNPs) post editing) were available on 7,128 South African Bonsmara cattle; the association analyses were undertaken using linear mixed models.

RESULTS

Genomic restricted maximum likelihood analysis of the 7,128 SA Bonsmara cattle yielded genomic heritability's of 0.183 (SE = 0.021) for AFC, 0.207 (SE = 0.022) for ICP and 0.209 (SE = 0.019) for SC. A total of 16, 23 and 51 suggestive (P ≤ 4 × 10-6) SNPs were associated with AFC, ICP and SC, while 11, 11 and 44 significant (P ≤ 4 × 10-7) SNPs were associated with AFC, ICP and SC respectively. A total of 11 quantitative trait loci (QTL) and 11 candidate genes were co-located with these associated SNPs for AFC, with 10 QTL harbouring 11 candidate genes for ICP and 41 QTL containing 40 candidate genes for SC. The QTL identified were close to genes previously associated with carcass, fertility, growth and milk-related traits. The biological pathways influenced by these genes include carbohydrate catabolic processes, cellular development, iron homeostasis, lipid metabolism and storage, immune response, ovarian follicle development and the regulation of DNA transcription and RNA translation.

CONCLUSIONS

This was the first attempt to study the underlying polymorphisms associated with reproduction in South African beef cattle. Genes previously reported in cattle breeds for numerous traits bar AFC, ICP or SC were detected in this study. Over 20 different genes have not been previously reported in beef cattle populations and may have been associated due to the unique genetic composite background of the SA Bonsmara breed.

Indoleamine 2, 3-dioxygenase 1 mediated alterations in the functionality of immune cells, deciphers the pregnancy outcomes in crossbred dairy cows

Pregnancy establishment in bovines requires maternal immune cell modulation. Present study investigated possible role of immunosuppressive indolamine-2, 3-dioxygenase 1 (IDO1) enzyme in the alteration of neutrophil (NEUT) and peripheral blood mononuclear cells (PBMCs) functionality of crossbred cows. Blood was collected from non-pregnant (NP) and pregnant (P) cows, followed by isolation of NEUT and PBMCs. Plasma pro-inflammatory (IFNγ and TNFα) and anti-inflammatory cytokines (IL-4 and IL-10) were estimated by ELISA and analysis of IDO1 gene in NEUT and PBMCs by RT-qPCR. Neutrophil functionality was assessed by chemotaxis, measuring activity of myeloperoxidase and β-D glucuronidase enzyme and evaluating nitric oxide production. Changes in PBMCs functionality was determined by transcriptional expression of pro-inflammatory (IFNγ, TNFα) and anti-inflammatory cytokine (IL-4, IL-10, TGFβ1) genes. Significantly elevated (P < 0.05) anti-inflammatory cytokines, increased IDO1 expression, reduced NEUT velocity, MPO activity and NO production observed only in P cows. Significantly higher (P < 0.05) expression of anti-inflammatory cytokines and TNFα genes were observed in PBMCs. Study highlights possible role of IDO1 in modulating the immune cell and cytokine activity during early pregnancy and may be targeted as early pregnancy biomarkers.

miRNA expression profiles of peripheral white blood cells from beef heifers with varying reproductive potential

Reproductive performance is the most critical factor affecting production efficiency in the cow-calf industry. Heifers with low reproductive efficiency may fail to become pregnant during the breeding season or maintain a pregnancy. The cause of reproductive failure often remains unknown, and the non-pregnant heifers are not identified until several weeks after the breeding season. Therefore, improving heifer fertility utilizing genomic information has become increasingly important. One approach is using microRNAs (miRNA) in the maternal blood that play an important role in regulating the target genes underlying pregnancy success and thereby in selecting reproductively efficient heifers. Therefore, the current study hypothesized that miRNA expression profiles from peripheral white blood cells (PWBC) at weaning could predict the future reproductive outcome of beef heifers. To this end, we measured the miRNA profiles using small RNA-sequencing in Angus-Simmental crossbred heifers sampled at weaning and retrospectively classified as fertile (FH, n = 7) or subfertile (SFH, n = 7). In addition to differentially expressed miRNAs (DEMIs), their target genes were predicted from TargetScan. The PWBC gene expression from the same heifers were retrieved and co-expression networks were constructed between DEMIs and their target genes. We identified 16 differentially expressed miRNAs between the groups (p-value ≤0.05 and absolute (log2 fold change ≥0.05)). Interestingly, based on a strong negative correlation identified from miRNA-gene network analysis with PCIT (partial correlation and information theory), we identified miRNA-target genes in the SFH group. Additionally, TargetScan predictions and differential expression analysis identified bta-miR-1839 with ESR1 , bta-miR-92b with KLF4 and KAT2B, bta-miR-2419-5p with LILRA4, bta-miR-1260b with UBE2E1, SKAP2 and CLEC4D, and bta-let-7a-5p with GATM, MXD1 as miRNA-gene targets. The miRNA-target gene pairs in the FH group are over-represented for MAPK, ErbB, HIF-1, FoxO, p53, mTOR, T-cell receptor, insulin and GnRH signaling pathways, while those in the SFH group include cell cycle, p53 signaling pathway and apoptosis. Some miRNAs, miRNA-target genes and regulated pathways identified in this study have a potential role in fertility; other targets are identified as novel and need to be validated in a bigger cohort that could help to predict the future reproductive outcomes of beef heifers.

The bovine uterine fluid proteome is more impacted by the stage of the estrous cycle than the proximity of the ovulating ovary in the periconception period

Uterine secretions provide a suitable environment for sperm selective migration during a couple of days preceding ovulation and for early embryo development before implantation. Our goal was to identify and quantify proteins in the bovine uterine fluid during the periovulatory period of the estrous cycle. Genital tracts with normal morphology were collected from adult cyclic Bos taurus females in a local slaughterhouse and classified into pre-ovulatory or post-ovulatory stages of cycle (around days 19-21 and 0-5 of cycle, respectively; n = 8 cows per stage) based on ovarian morphology. Proteins from uterine fluid collected from the utero-tubal junction to the base of each horn (four pools of two cows per condition) were analyzed by nanoLiquid Chromatography coupled with tandem Mass Spectrometry (nanoLC-MS/MS). A total of 1214 proteins were identified, of which 91% were shared between all conditions. Overall, 57% of proteins were predicted to be secreted and 17% were previously reported in uterine extracellular vesicles. Paired comparisons between uterine horns ipsilateral and contralateral to ovulation evidenced 12 differentially abundant proteins, including five at pre-ovulatory stage. Furthermore, 35 proteins differed in abundance between pre- and post-ovulatory stages, including 21 in the ipsilateral side of ovulation. Functional analysis of identified proteins demonstrated roles in binding, metabolism, cellular detoxification and the immune response. This study provides a valuable database of uterine proteins for functional studies on sperm physiology and early embryo development.

Mesenchymal Stem Cells in Embryo-Maternal Communication under Healthy Conditions or Viral Infections: Lessons from a Bovine Model

Bovine mesenchymal stem cells are a relevant cell population found in the maternal reproductive tract that exhibits the immunomodulation capacity required to prevent embryo rejection. The phenotypic plasticity showed by both endometrial mesenchymal stem cells (eMSC) and embryonic trophoblast through mesenchymal to epithelial transition and epithelial to mesenchymal transition, respectively, is essential for embryo implantation. Embryonic trophoblast maintains active crosstalk via EVs and soluble proteins with eMSC and peripheral blood MSC (pbMSC) to ensure the retention of eMSC in case of pregnancy and induce the chemotaxis of pbMSC, critical for successful implantation. Early pregnancy-related proteins and angiogenic markers are detected as cargo in EVs and the soluble fraction of the embryonic trophectoderm secretome. The pattern of protein secretion in trophectoderm-EVs changes depending on their epithelial or mesenchymal phenotype and due to the uptake of MSC EVs. However, the changes in this EV-mediated communication between maternal and embryonic MSC populations infected by viruses that cause abortions in cattle are poorly understood. They are critical in the investigation of reproductive viral pathologies.

Progesterone-dependent and progesterone-independent modulation of luminal epithelial transcription to support pregnancy in cattle

In cattle, starting 4-5 days after estrus, preimplantation embryonic development occurs in the confinement of the uterine lumen. Cells in the endometrial epithelial layer control the molecular traffic to and from the lumen and, thereby determine luminal composition. Starting early postestrus, endometrial function is regulated by sex steroids, but the effects of progesterone on luminal cells transcription have not been measured in vivo. The first objective was to determine the extent to which progesterone controls transcription in luminal epithelial cells 4 days (D4) after estrus. The second objective was to discover luminal transcripts that predict pregnancy outcomes when the effect of progesterone is controlled. Endometrial luminal epithelial cells were collected from embryo transfer recipients on D4 using a cytological brush and their transcriptome was determined by RNASeq. Pregnancy by embryo transfer was measured on D30 (25 pregnant and 18 nonpregnant). Progesterone concentration on D4 was associated positively (n = 182) and negatively (n = 58) with gene expression. Progesterone-modulated transcription indicated an increase in oxidative phosphorylation, biosynthetic activity, and proliferation of epithelial cells. When these effects of progesterone were controlled, different genes affected positively (n = 22) and negatively (n = 292) odds of pregnancy. These set of genes indicated that a receptive uterine environment was characterized by the inhibition of phosphoinositide signaling and innate immune system responses. A panel of 25 genes predicted the pregnancy outcome with sensitivity and specificity ranging from 64%-96% and 44%-83%, respectively. In conclusion, in the early diestrus, both progesterone-dependent and progesterone-independent mechanisms regulate luminal epithelial transcription associated with pregnancy outcomes in cattle.

Intrauterine iodine administration is superior to antibiotics for reconception after late-embryonic losses in dairy cows

This field study was conducted to compare conception and insemination efficiency responses to intrauterine polyvinylpyrrolidone-iodine (PVP-I) and antibiotic (AB) treatments in dairy cows that experienced pregnancy loss. Data were collected from lactation cows with a history of pregnancy loss 27 to 70 days post-insemination (n = 97) during the 1st to 3rd lactation (days in milk = 196 ± 28). Cows were subjected to 1 of 3 treatments: i) 50 mL saline solution intrauterine infusion (S; n = 23); ii) 2% PVP-I (n = 42); or iii) 150 mg of amoxicillin trihydrate and 40 mg/mL gentamicin sulphate (n = 32). All cows followed the progesterone-based fixed-time insemination protocol. Data were analyzed by Chi-square test and 1-way analysis of variance. The PVP-I treatment (n = 25; 59.5%) was as effective as the AB treatment (n = 19; 59.4%), compared to the S treatment (n = 5; 21.7%) to achieve a new conception. The cows in group PVP-I conceived in a shorter time than those in group AB (46.0 ± 8.7 days versus 105.0 ± 10.0 days; P < 0.05) with a more efficient insemination to conception ratio (2.32 ± 0.43 versus 4.10 ± 0.32; P < 0.05). Data suggest that intrauterine PVP-I administration is superior to intrauterine AB administration in rescheduling reproductive protocol upon late embryonic and fetal losses.

Galectin-1 Confers Endometrial Gene Expression and Protein Related to Maternal-Conceptus Immune Tolerance in Cattle

Conceptus secretory factors include galectins, a family of carbohydrate binding proteins that elicit cell adhesion and immune suppression by interacting with intracellular and extracellular glycans. In rodents, galectin-1 (LGALS1) promotes maternal-fetal immune tolerance in the decidua through expansion of tolerogenic CD11c+ dendritic cells, increased anti-inflammatory IL-10, and activation of FOXP3+ regulatory T cells (Treg). This study characterized galectin expression in early ruminant conceptuses and endometrium. We also tested the effect of recombinant bovine LGALS1 (rbLGALS1) and progesterone (P4) on endometrial expression of genes and protein related to maternal-fetal immune tolerance in cattle. Elongating bovine and ovine conceptuses expressed several galectins, particularly, LGALS1, LGALS3 and LGALS8. Within bovine endometrium, expression of LGALS3, LGALS7 and LGALS9 was greater on Day 16 of pregnancy compared to the estrous cycle. Within ovine endometrium, LGALS7 was greater during pregnancy compared to the estrous cycle and endometrium of pregnant sheep tended to have greater LGALS9 and LGALS15. Expression of endometrial LGALS4 was less during pregnancy in sheep. Treating bovine endometrium with rbLGALS1 increased endometrial expression of CD11c, IL-10 and FOXP3, within 24 h. Specifically, within caruncular endometrium, both rbLGALS1 and P4 increased FOXP3, suggesting that both ligands may promote Treg expansion. Using IHC, FOXP3+ cells with a leukocyte phenotype were localized to the bovine uterine stratum compactum near the uterine surface and increased in response to rbLGALS1. We hypothesize that galectins have important functions during establishment of pregnancy in ruminants and bovine conceptus LGALS1 and luteal P4 confer mechanisms of maternal-conceptus immune tolerance in cattle.

The Combined Effect of Weaning Stress and Immune Activation during Pig Gestation on Serum Cytokine and Analyte Concentrations

Weaning stress can elicit changes in the metabolic, hormone and immune systems of pigs and interact with prolonged disruptions stemming from maternal immune activation (MIA) during gestation. The present study advances the characterization of the combined effects of weaning stress and MIA on blood chemistry, immune and hormone indicators that inform on the health of pigs. Three-week-old female and male offspring of control gilts or gilts infected with the porcine reproductive and respiratory syndrome virus were allocated to weaned or nursed groups. The anion gap and bilirubin profiles suggest that MIA enhances tolerance to the effects of weaning stress. Interleukin 1 beta and interleukin 2 were highest among weaned MIA females, and cortisol was higher among weaned relative to nursed pigs across sexes. Canonical discriminant analysis demonstrated that weaned and nursed pigs have distinct chemistry profiles, whereas MIA and control pigs have distinct cytokine profiles. The results from this study can guide management practices that recognize the effects of the interaction between MIA and weaning stress on the performance and health of pigs.

Association between phagocytic activity of monocytes and days to conception after parturition in dairy cows when considering the hormonal and metabolic milieu

The nutritional conditions and immune status of dairy cows affect reproductive performance. This study was conducted with the aim to analyze the phagocytic activity (PA) and phagocytic capacity (PC) of circulating monocytes after the period of transition from pregnancy to lactation, to evaluate possible associations with duration of time period to conception following parturition. Results indicated PA was not associated with duration of time period to conception following parturition. In contrast, cows with a lesser PC conceived earlier (98 ± 9 days in milk, DIM) than those with a greater PC (168 ± 15 DIM). Based on these results, to analyze the association of the hormonal and metabolic milieu with the PA and PC, the animals were grouped considering the days to conception following parturition. In the group with the greater number of days to conception (>168 DIM), the PA was associated with concentrations of progesterone and beta-hydroxybutyrate (BHB) at 90 DIM and glucose at 120 DIM, whereas PC was associated with the concentrations of progesterone, cortisol and glucose at 90 DIM, non-esterified fatty acids (NEFA) at 120 DIM, 17β-estradiol at 150 DIM, and 17β-estradiol and BHB at 180 DIM. Overall, these results represent a new perspective related to the reproductive performance of dairy cows. The modifications of cellular functions may be useful for predicting the onset of health complications in dairy cows and to manage cows in ways that result in an enhanced fertility during the subsequent lactational period.

Evaluation of Reproductive Tract Cytokines in Post-partum Beef Cows Relating to Reproductive Microbiota and Fertility Outcomes

The activity of the immune system in the reproductive tract has been proven to be crucial in the response to uterine diseases, normal reproductive functions, and tolerance to the allogeneic fetus during pregnancy. The objectives of the current study were to (1) evaluate uterine and vaginal cytokine concentrations in postpartum cows undergoing estrus synchronization followed by timed artificial insemination (TAI) and (2) correlate bacterial communities with cytokine concentrations. Postpartum Angus cows (n = 20) were subjected to a 7-Day Co-Synch protocol with pre-synchronization beginning 21 days prior (d −21) to TAI (d 0). Uterine and vaginal flushes were collected on d −21 and −2. Pregnancy was determined by transrectal ultrasound on d 30. Cytokines include interleukin (IL)-1b, IL-6, IL-10, transforming growth factor beta (TGF-β), and immunoglobin A (IgA) and concentrations were determined by commercial ELISA kits. No differences by day or pregnancy status in cytokine concentrations were detected in vaginal samples. No differences by day or pregnancy status in IgA, IL-10, or IL-1b concentrations were detected in uterine samples. Overall TGF-β concentrations in the uterus were greater in resulting pregnant than non-pregnant cows (44.0 ± 13.4 pg/mL vs. 14.7 ± 4.9 pg/mL; P = 0.047). Uterine TGF-β was correlated with the relative abundance of genera Treponema (r = −0.668; P = 0.049) in resulting non-pregnant cows on d −21 and with the relative abundance of genera Ureaplasma (r = 0.901; P = 0.0004) in resulting pregnant cows on d −2. In resulting pregnant animals, a tendency for a strong correlation was detected between d −2 progesterone concentrations and uterine TGF-β concentrations (r = 0.591, P = 0.07). Overall IL-6 concentrations in the uterus were greater in resulting non-pregnant than pregnant cows (198.7 ± 21.8 pg/mL vs. 144.3 ± 16.1 pg/mL; P = 0.045). A correlation was also detected between uterine IL-6 concentrations and the relative abundance of genera Butyrivibrio (r = 0.742; P = 0.022) in resulting non-pregnant cows on d −21. These results suggest possible relationships between different bacterial communities and cytokine concentrations within the uterus of beef cattle prior to TAI that may ultimately affect fertility outcomes.

Endometrium On-a-Chip Reveals Insulin- and Glucose-induced Alterations in the Transcriptome and Proteomic Secretome

The molecular interactions between the maternal environment and the developing embryo are key for early pregnancy success and are influenced by factors such as maternal metabolic status. Our understanding of the mechanism(s) through which these individual nutritional stressors alter endometrial function and the in utero environment for early pregnancy success is, however, limited. Here we report, for the first time, the use of an endometrium-on-a-chip microfluidics approach to produce a multicellular endometrium in vitro. Isolated endometrial cells (epithelial and stromal) from the uteri of nonpregnant cows in the early luteal phase (Days 4-7) were seeded in the upper chamber of the device (epithelial cells; 4-6 × 104 cells/mL) and stromal cells seeded in the lower chamber (1.5-2 × 104 cells/mL). Exposure of cells to different concentrations of glucose (0.5, 5.0, or 50 mM) or insulin (Vehicle, 1 or 10 ng/mL) was performed at a flow rate of 1 µL/minute for 72 hours. Quantitative differences in the cellular transcriptome and the secreted proteome of in vitro-derived uterine luminal fluid were determined by RNA-sequencing and tandem mass tagging mass spectrometry, respectively. High glucose concentrations altered 21 and 191 protein-coding genes in epithelial and stromal cells, respectively (P < .05), with a dose-dependent quantitative change in the protein secretome (1 and 23 proteins). Altering insulin concentrations resulted in limited transcriptional changes including transcripts for insulin-like binding proteins that were cell specific but altered the quantitative secretion of 196 proteins. These findings highlight 1 potential mechanism by which changes to maternal glucose and insulin alter uterine function.

Association of gastrointestinal parasite burden, serum cytokines and hormones concentrations, and pregnancy in Angus-cross beef cows

The objective was to elucidate the relationships among gastrointestinal (GI) parasite load, serum cytokines (Th 1 - Interleukin (IL) 2, Interferon (IFN) γ and Tumor necrosis factor (TNF) α; Th 2- IL4, IL6, and IL10) levels, hormones (progesterone, cortisol, 8-epi-prostaglandin F2 alpha (isoprostane), prolactin, substance-p, and prostaglandin F metabolites) concentrations, and pregnancy in beef cattle. Angus-cross beef cows (n = 700; age, 3-8 y) were blocked by age and body condition score (BCS, 1-9), and were randomly assigned to treatment (n = 350, TRT, 50 mg of eprinomectin/50 kg BW, im) or control (n = 350, CON, no treatment) on Day -30. Cows were synchronized using Controlled Internal Drug Release insert (CIDR) + CO-Synch protocol and artificially inseminated at a fixed time on Day 0 (66 h after CIDR removal). Fecal samples were collected to determine fecal egg count per gram (FEG, McMaster method) on Days -30, -23, -16, -7, 7, 0, 16 and 23, and blood samples were collected on Days -7, 0, 7, 16 and 23. Serum cytokines were determined on Days -7, 0, 7, 16 and 23, and circulating hormones were measured on Day 16. BCS were recorded on Day 16 following artificial insemination (AI), and pregnancy status was diagnosed on Day 30 and 60. Pregnancy/AI varied among treatment groups on Day 30 [TRT, 62.0% (217/350); CON, 54.9% (192/350) (P = 0.05)] and Day 60 [TRT, 60.9% (213/350); CON, 51.7% (181/350) (P < 0.05)]. Pregnancy loss between 30 and 60 days for TRT and CON groups were 1.8% (4/217) and 5.7% (11/192), respectively (P < 0.05). The BCS on Day 16 did not differ among treatment groups (P> 0.1). Four groups of 40 cows were selected based on their pregnancy status and treatment: pregnant, TRT; non-pregnant, TRT; pregnant, CON; and non-pregnant, CON to compare the mean FEG, cytokines, and hormones levels. The FEG and cytokine concentrations were significantly (P < 0.05) influenced by treatment, pregnancy status, day, treatment by pregnancy status, and treatment by day. Day 16 hormone concentrations were considerably influenced by treatment, pregnancy status, and treatment by pregnancy. Although FEG on Day -30 did not differ among the groups (P> 0.1), it was lower in treated, pregnant cows compared with cows in other three groups from Day -23 onwards (P < 0.05). Overall and pairwise comparisons showed that serum concentrations of Type 1 cytokines, IL2, IFNγ, and TNFα were lower (P < 0.05) from gestational Day 7 onwards in treated, pregnant cows compared with cows in other three groups. In contrast, serum concentrations of Type 2 cytokines, IL4, IL6 and IL10 were greater (P < 0.05) from gestational Day 7 onwards in treated, pregnant cows compared with cows in other groups. Serum concentrations of progesterone was greater and other hormones were lower for pregnant cows in TRT group compared to cows in other groups on gestational Day 16. In conclusion, GI parasite load was reduced; Th 1 cytokines levels were decreased; Th 2 cytokines concentrations were increased; progesterone level was increased; and cortisol, substance-P, prolactin, isoprostane, and PGFM were decreased in pregnant, TRT cows. These changes also resulted in an increase in P/AI. It is plausible that direct and bidirectional host-parasite interactions mediated by cytokines and hormones may have promoted maternal tolerance of an immunologically diverse conceptus and the establishment of pregnancy.

Conceptus-modulated innate immune function during early pregnancy in ruminants: a review

This review focuses on the innate immune events modulated by conceptus signaling during early pregnancy in ruminants. Interferon-tau (IFN-τ) plays a role in the recognition of pregnancy in ruminants, which involves more than the inhibition of luteolytic pulses of PGF2α to maintain corpus luteum function. For successful pregnancy establishment, the allogenic conceptus needs to prevent rejection by the female. Therefore, IFN-τ exerts paracrine and endocrine actions to regulate the innate immune system and prevent conceptus rejection. Additionally, other immune regulators work in parallel with IFN-τ, such as the pattern recognition receptors (PRR). These receptors are activated during viral and bacterial infections and in early pregnancy, but it remains unknown whether PPR expression and function are controlled by IFN-τ. Therefore, this review focuses on the main components of the innate immune response that are involved with early pregnancy and their importance to avoid conceptus rejection.

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.

Biochemistry and Immune Biomarkers Indicate Interacting Effects of Pre- and Postnatal Stressors in Pigs across Sexes

The effects of maternal immune activation (MIA) elicited by a prenatal stressor and postnatal metabolic or immune stressors on chemical and inflammatory biomarkers were studied in male and female pigs. Pigs exposed to MIA elicited by porcine reproductive and respiratory syndrome virus and matching controls were assigned at two months of age to fasting stress, immune stress, or a saline group. The serum levels of over 30 chemistry and immune analytes were studied. Significantly low levels of blood urea nitrogen were detected in females exposed to MIA, while the highest creatinine levels were identified in fasting females exposed to MIA. The levels of interferon gamma and interleukin 8 were highest in pigs exposed to postnatal immune challenge. The profiles suggest that MIA may sensitize pigs to postnatal stressors for some indicators while making them more tolerant of other stressors. Effectiveness of practices to ameliorate the impact of postnatal stressors on the physiology of the pig could be enhanced by considering the prenatal stress circumstances.

Lymphocyte soluble factors from pregnant cows modulate mRNA transcript abundances encoding for proteins associated with trophoblast growth and development

This study was conducted to determine whether T cell populations are responsible for modulating placental development during gestation in cattle. It was hypothesized that CD4+CD25+ and γ/δ+ T cells modulate gene expression, based on mRNA transcript abundances, and promote proliferation and survival of trophoblast cells. Peripheral blood was collected from cows at 160 to 180 days of gestation and non-pregnant cows, T cell populations CD8+, CD4+, CD4+CD25+, CD24+CD25-, and γ/δ+ T cells were isolated, cultured for 48 h, and supernatant was collected. Placental samples were digested, and trophoblast cells were cultured for 24 h. Trophoblast cells were cultured with 50 μL of T cell-conditioned media and 50 μL of fresh culture media for an additional 48 h. Samples in control wells were treated with unconditioned media. Trophoblast cell proliferation, apoptosis, and mRNA transcript assays were conducted. There was no effect of T cell population on trophoblast apoptosis rate, proliferation, and relative mRNA transcript abundances. The T cell supernatant from pregnant and non-pregnant cows induced greater apoptosis rates in trophoblast cells than unconditioned media. Trophoblast cells proliferated less when treated with T cell supernatant from pregnant compared to unconditioned medium and non-pregnant cows. Treatment with the T cell supernatant from pregnant cows resulted in larger abundances of BMP5, IGF1R, PAG10, FGF2, RSPO3 and TMED2 and also a lesser abundance of FGF2 mRNA transcript than non-pregnant group and unconditioned media treatments. Supernatant from T cell derived from pregnant cows modulates trophoblast mRNA transcript abundances differently from T cell supernatant of non-pregnant cows.

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

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

Concentration-Dependent Type 1 Interferon-Induced Regulation of MX1 and FABP3 in Bovine Endometrial Explants

The inadequate maternal recognition of embryonic interferon τ (IFNτ) might explain subfertility in cattle. This study aimed at modeling the inducibility of type 1 interferon receptor subunits 1/2 (IFNAR1/2), mimicking competition between IFNτ and infection-associated interferon α (IFNα), and simulating type 1 interferon pathways in vitro. Endometrial explants (n = 728 from n = 26 healthy uteri) were collected at the abattoir, challenged with IFNτ and/or IFNα in different concentrations, and incubated for 24 h. Gene expression analysis confirmed the inducibility of IFNAR1/2 within this model, it being most prominent in IFNAR2 with 10 ng/mL IFNα (p = 0.001). The upregulation of interferon-induced GTP-binding protein (MX1, classical pathway) was higher in explants treated with 300 ng/mL compared to 10 ng/mL IFNτ (p < 0.0001), whereas the non‑classical candidate fatty acid binding protein 3 (FABP3) exhibited significant downregulation comparing 300 ng/mL to 10 ng/mL IFNτ. The comparison of explants challenged with IFNτ + IFNα indicated the competition of IFNτ and IFNα downstream of the regulatory factors. In conclusion, using this well-defined explant model, interactions between infection-associated signals and IFNτ were indicated. This model can be applied to verify these findings and to mimic and explore the embryo-maternal contact zone in more detail.

Effects of maternal immune activation in porcine transcript isoforms of neuropeptide and receptor genes

The prolonged effects of maternal immune activation in response stressors during gestation on the offspring's molecular pathways after birth are beginning to be understood. An association between maternal immune activation and neurodevelopmental and behavior disorders such as autism and schizophrenia spectrum disorders has been detected in long-term gene dysregulation. The incidence of alternative splicing among neuropeptides and neuropeptide receptor genes, critical cell-cell signaling molecules, associated with behavior may compromise the replicability of reported maternal immune activation effects at the gene level. This study aims to advance the understanding of the effect of maternal immune activation on transcript isoforms of the neuropeptide system (including neuropeptide, receptor and connecting pathway genes) underlying behavior disorders later in life. Recognizing the wide range of bioactive peptides and functional receptors stemming from alternative splicing, we studied the effects of maternal immune activation at the transcript isoform level on the hippocampus and amygdala of three-week-old pigs exposed to maternal immune activation due to viral infection during gestation. In the hippocampus and amygdala, 29 and 9 transcript isoforms, respectively, had maternal immune activation effects (P-value < 0.01). We demonstrated that the study of the effect of maternal immune activation on neuropeptide systems at the isoform level is necessary to expose opposite effects among transcript isoforms from the same gene. Genes were maternal immune activation effects have also been associated with neurodevelopmental and behavior disorders. The characterization of maternal immune activation effects at the transcript isoform level advances the understanding of neurodevelopmental disorders and identifies precise therapeutic targets.

Long-Lasting Impact of Maternal Immune Activation and Interaction With a Second Immune Challenge on Pig Behavior

The combined effects on pig behavior of maternal immune challenge during gestation followed by a second immune challenge later in life have not been studied. Porcine reproductive and respiratory syndrome virus (PRRSV) infection during gestation can elicit maternal immune activation (MIA) yet the interactions with the offspring response to a second immune challenge after birth remains unexplored. Knowledge on the response to viral challenges in rodents has been gained through the use of the viral mimetic polyinosinic-polycytidylic acid (Poly(I:C)), yet the effects of this immune stimulant on pig behavior have not been assessed. This study advances the understanding of the combined effect of MIA and a second immune challenge later in life on female and male pig behavior. Three complementary experiments enabled the development of an effective Poly(I:C) challenge in pigs, and testing the interaction between PRRSV-elicited MIA, Poly(I:C) challenge at 60 days of age, and sex on behaviors. Individual-level observations on sickness, locomotor, and social behaviors were measured 1-3 h after Poly(I:C) challenge. Vomiting, panting, lethargy, walking, laying, playing, and touching behaviors were analyzed using generalized linear mixed effect models. Results indicated that a Poly(I:C) dose of 1 mg/kg within 1 h after injection increased the incidence of laying and sickness behavior. The Poly(I:C) challenge decreased the incidence of locomotor behaviors and activity levels. Pigs exposed to MIA had lower rates of social behaviors such as playing. The combined effect of PRRSV-elicited MIA and Poly(I:C) immune challenge further sensitized the pigs to behavior disruption across sexes including changes in sternal and lateral laying, walking, lethargy, and touching incidence. Notably, the effects of Poly(I:C) immune challenge alone on behaviors tended to be more extreme in males, whereas the effects of Poly(I:C) following MIA tended to be more extreme in females. Our findings demonstrate that MIA and Poly(I:C) affected behaviors, and the viral mimetic effects shortly after injection can offer insights into the prolonged effect of postnatal viral infections on feeding, social interactions and health status. Management practices that reduce the likelihood of gestational diseases and accommodate for behavioral disruptions in the offspring can minimize the impact of MIA.

Reduced gastrointestinal worm burden following long term parasite control improves body condition and fertility in beef cows

The objective of this study was to compare effects of gastrointestinal parasite control over a long vs short term (PC-LT vs. PC-ST) on fecal parasite load, body condition and pregnancy in beef cows. On Day 0, fecal samples were collected from Angus cross cows (n = 1462) and they were assigned a body condition score (BCS: 1, emaciated; 9, Obese) and randomly divided into two groups (within location) to receive extended-release eprinomectin [PC-LT; n = 749; 50 mg/50 kg body weight (BW)] or pour-on ivermectin (PC-ST; n = 713; 25 mg/50 kg BW). All cows were synchronized with CO-Synch + CIDR [100 μg GnRH + progesterone vaginal insert (CIDR) application on Day 20, CIDR removal +25 mg PGF2a on Day 27, and artificial insemination +100 μg GnRH on Day 30 (66 h after CIDR removal)] protocol, artificially inseminated (AI; Day 30) and on Day 44, exposed to breeding bulls (1:40 bull to cow ratio) for the remainder of the 85 day breeding season. On Day 90, a second fecal sample was collected from all cows and the cows were examined to determine pregnancy/AI (P/AI). All cows were assigned a BCS on Day 180 and re-examined to determine pregnancy/breeding season (P/BS). Worm egg count per gram of feces (FEG) was determined by McMaster method. There were no differences (P > 0.1) between PC-LT and PC-ST groups on Day 0 for FEG (46.9 ± 13.1 vs 42.6 ± 15.2, respectively; mean ± SEM) or BCS (5.95 ± 0.12 vs 6.00 ± 0.20). The mean FEG (PC-LT, 12.3 ± 4.7 vs. PC-ST, 131.3 ± 10.9) on Day 90 and BCS (PC-LT, 6.04 ± 0.07 vs. PC-ST, 5.79 ± 0.13) on Day 180 differed (P < 0.05) between the two groups. Mean P/AI [PC-LT, 62.9 %; (471/749) vs PC-ST, 57.4 %; (409/713)] and P/BS [PC-LT, 92.9 % (696/749) vs PC-ST, 90.0 (642/713)] also differed (P < 0.05). Lower FEG at Day 90 resulted in moderate to good body condition at Day 180 and cows with moderate to good body condition at Day 180 had higher P/BS. In conclusion, lower worm burden with long-term parasite control reduced FEG and improved BCS, P/AI and P/BS.

Bovine scavenger receptor class A (SR-A) exhibit specific patterns of regulation in the endometrium during the oestrous cycle and early pregnancy

In mammals, tight regulation of maternal endometrial function is critical for pregnancy success. In bovine species, endometrial expression of members of the scavenger receptor class A (SR-A) has been listed in high-throughput analyses, but very little is known about the involvement of these immune factors during implantation in mammals. To provide first insights into the contribution of SR-A to endometrial physiology, we analysed the expression and regulation of all members of SR-A (SR-A1, SR-A3-SR-A6) during the oestrous cycle and early pregnancy in cattle. Levels of SR-A1 were increased on Day 20 of pregnancy, whereas SR-A3 levels were increased on Day 13 of the oestrous cycle and of the pregnancy. Although SR-A4 levels were reduced on Day 20 of the oestrous cycle, they remained high in pregnant animals. SR-A5 levels increased by Day 13 of the oestrous cycle and decreased on Day 20, but remained high in pregnant animals. Interferon-τ does not affect SR-A gene expression, whereas progesterone regulates the expression of the SR-A3 and SR-A5 transcripts. Endometrial SR-A3 appeared significantly higher in cows carrying invitro-produced embryos than in AI cows. Our data suggest that members of the SR-A family are involved in endometrial remodelling and regulation of endometrial gland physiology, both processes being critical for implantation in mammals.

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.

Identification of Loci and Pathways Associated with Heifer Conception Rate in U.S. Holsteins

Heifer conception rate (HCR) is defined as the percentage of inseminated heifers that become pregnant at each service. The genome-wide association analyses in this study focused on identifying the loci associated with Holstein heifer (n = 2013) conception rate at first service (HCR1) and the number of times bred (TBRD) to achieve a pregnancy. There were 348 unique loci associated (p < 5 × 10⁻⁸) with HCR1 and 615 unique loci associated (p < 5 × 10⁻⁸) with TBRD. The two phenotypes shared 302 loci, and 56 loci were validated in independent cattle populations. There were 52 transcription factor binding sites (TFBS) and 552 positional candidate genes identified in the HCR1- and TBRD-associated loci. The positional candidate genes and the TFBS associated with HCR1 and TBRD were used in the ingenuity pathway analysis (IPA). In the IPA, 11 pathways, 207 master regulators and 11 upstream regulators were associated (p < 1.23 × 10⁻⁵) with HCR1 and TBRD. The validated loci associated with both HCR1 and TBRD make good candidates for genomic selection and further investigations to elucidate the mechanisms associated with subfertility and infertility.

Symposium review: Progesterone effects on early embryo development in cattle

The causes of low fertility in dairy cattle are complex and multifactorial and may be due to compromised follicle development affecting oocyte quality, a suboptimal reproductive tract environment incapable of supporting normal embryo development, or a combination of both. Progesterone (P4) plays a key role in reproductive events associated with establishment and maintenance of pregnancy, through its effects on oocyte quality and its action on the uterine endometrium. Reduced P4 concentrations during growth of the ovulatory follicle are associated with lower fertility, and low concentrations of circulating P4 after ovulation have been associated with reductions in conceptus growth and elongation, decreased interferon-τ (IFNT) production, and lower pregnancy rates in cattle. In contrast, elevated concentrations of circulating P4 in the period immediately following conception have been associated with advancement of conceptus elongation, increased IFNT production, and, in some cases, higher pregnancy rates in cattle. Despite the potential beneficial effects of exogenous P4 supplementation on fertility, results of supplementation studies have been inconsistent. As part of the 2019 ADSA Reproduction Symposium, focusing on the etiology of pregnancy losses in dairy cattle, the aim of this review is to highlight recent findings from our group and others in relation to embryo-maternal interaction during bovine pregnancy establishment and the role of P4 in uterine biology and embryo development.

Characterization of the endometrial transcriptome in early diestrus influencing pregnancy status in dairy cattle after transfer of in vitro-produced embryos

Modifications of the endometrial transcriptome at day 7 of the estrus cycle are crucial to maintain gestation after transfer of in vitro-produced (IVP) embryos, although these changes are still largely unknown. The aim of this study was to identify genes, and their related biological mechanisms, important for pregnancy establishment based on the endometrial transcriptome of recipient lactating dairy cows that become pregnant in the subsequent estrus cycle, upon transfer of IVP embryos. Endometrial biopsies were taken from Holstein Friesian cows on day 6-8 of the estrus cycle followed by embryo transfer in the following cycle. Animals were classified retrospectively as pregnant (PR, n = 8) or nonpregnant (non-PR, n = 11) cows, according to pregnancy status at 26-47 days. Extracted mRNAs from endometrial samples were sequenced with an Illumina platform to determine differentially expressed genes (DEG) between the endometrial transcriptome from PR and non-PR cows. There were 111 DEG (false discovery rate < 0.05), which were mainly related to extracellular matrix interaction, histotroph metabolic composition, prostaglandin synthesis, transforming growth factor-β signaling as well as inflammation and leukocyte activation. Comparison of these DEG with DEG identified in two public external data sets confirmed the more fertile endometrial molecular profile of PR cows. In conclusion, this study provides insights into the key early endometrial mechanisms for pregnancy establishment, after IVP embryo transfer in dairy cows.

The frontiers of biomedical science and its application to animal science in addressing the major challenges facing Australasian dairy farming

Extraordinary advances are occurring in biomedical science that may revolutionise how we approach health and disease. Many have applications in the dairy industry. We have described one particular area of extracellular vesicles that have already proven to be of interest in diagnostics and prognostics for fertility and assessment of ‘transition’ cows (i.e. evaluation of the problems related to the risk of clinical diseases in dairy cows, such as mastitis and milk fever, during transition period). The addition of measurements of circulating RNA and DNA may prove of value in identifying dairy cows with higher risks of clinical diseases and potentially poor fertility. We describe the exciting opportunity provided by the possibility of generating exosomes to order as therapeutic agents to potentially enhance fertility. The even more radical concept of using exosomes to deliver a CRISPR-linked gene editing function is presented. Undoubtedly, the use of biomedical advances to assist the dairy industry is an obvious and practical approach that has significant merit.

Peripheral and placental immune responses in sheep after experimental infection with Toxoplasma gondii at the three terms of gestation

Although it is known that gestation could influence the clinical course of ovine toxoplasmosis, the precise effect of the term of gestation when sheep are infected are yet mostly unknown. The aim of this study was to evaluate the peripheral and placental immune responses developed in pregnant sheep after experimental infection with Toxoplasma gondii at different times of gestation. Thirty-six pregnant sheep were allocated in different groups, orally inoculated with sporulated oocysts of T. gondii at early, mid and late gestation and culled within 30 days post-infection. The peripheral humoral and cytokine responses were evaluated, as well as the transcription of cytokines at the placenta. Serological analysis revealed that, regardless the term of gestation when infected, specific IgG against T. gondii were detected from day 8 post-infection and there was an early peripheral release of IFN-γ at the first week post-infection followed by a short peak of IL10 and TNF-α at the second week post-infection. There were no significant differences in this response between infected groups. At the placenta, a similar increase in transcription of IFN-γ, and TNF-α was found at the three terms of gestation, while IL-4 increased mainly at the first and second terms and IL-10 transcription was higher at the last term. While these findings show that both Th1 and Th2 cytokines play a key role in the pathogenesis of ovine toxoplasmosis and that placental and peripheral immune responses do not closely correlate, there seems to be no clear modulation of these responses along the gestation.

Immune status during postpartum, peri-implantation and early pregnancy in cattle: An updated view

Throughout the estrous cycle the mammalian endometrium undergoes morphological and functional changes that are essential for the establishment of pregnancy and proper ovarian and uterine functions. Among these changes, the most important are alterations in both inter- and intracellular signalling molecules, many of which modulate immune processes. In the endometrial tissue there are local innate (nonspecific) and adaptive (specific/acquired) response mechanisms which vary because of the endocrine status during the estrous cycle, pregnancy and postpartum period. Endometrial cells have responses that support the immune system by producing pro-inflammatory factors such as cytokines, sensors, effector molecules and chemokines. This response is important during gestation, pregnancy, and fetal growth, as well as in preventing infection, and immuno-rejection of the semi-allogeneic embryo. In dairy cows, both before and immediately after calving, there are marked changes in the values for hormonal and metabolic variables and the immune status is impaired. Thus, in several studies there has been assessment of the physiological and/or abnormal maternal immune changes and possible effects on dairy cow reproductive performance. The objective with this review is to summarize the novel information about the immune mechanisms involved during the postpartum period, subsequent peri-implantation period and pregnancy in dairy cows, and the possible effects on reproductive performance. This information provides for an enhanced understanding of the local and systemic immune responses associated with the metabolic and hormonal status of dairy cows, and alterations in the immune system of high producing cows and the possible effects on subsequent fertility.

Temporal expression and localization of vascular endothelial growth factor family members in the bovine uterus during peri-implantation period

The aim of this study was to determine endometrial mRNA expression patterns and uterine protein localizations of vascular endothelial growth factor (VEGF) ligands (VEGFA, VEGFB, VEGFC, and VEGFD) and their receptors (VEGFR1, soluble VEGFR1 (sVEGFR1), VEGFR2, and VEGFR3) during the peri-implantation period in cows. The number of blood and lymphatic vessels in the bovine uterus was also investigated. Bovine uterine tissues were collected from pregnant animals on days 15, 18, and 27 after artificial insemination and from non-pregnant animals on days 15 and 18 of the estrous cycle (day 0 = day of estrus). The mRNA expression level of VEGFA, VEGFR1, sVEGFR1, and VEGFR3 were higher on day 18 than on day 15 in the non-pregnant group. On day 18, the levels of mRNA expression of these genes were higher in the non-pregnant group than in the pregnant group. VEGFB mRNA expression levels was higher on day 15 than on days 18 and 27 of gestation and was higher in the pregnant group than in the non-pregnant group on day 15. Using immunohistochemistry, VEGF ligands and their receptors were found in luminal epithelium, glandular epithelium, stroma, and blood vessels of the endometrium. In addition, VEGFA, VEGFD, and VEGFR3 were also detected in the uterine myometrium. In the pregnant group, the number of blood vessels in the endometrium increased from day 15 to 18 and was greater than that of the non-pregnant group on day 18. Our results demonstrate that the VEGF family is expressed and regulated in the bovine uterus during the peri-implantation period, which may be associated with uterine functions, including vascular remodeling in maternal recognition of pregnancy and implantation.

Symposium review: Immunological detection of the bovine conceptus during early pregnancy

Infertility and subfertility reduce the economic viability of dairy production. Inflammation reduces conception rates in dairy cattle, but surprisingly little information exists about the populations and the functions of immune cells at the conceptus-maternal interface during the periattachment period in dairy cattle. Early pregnancy is accompanied by immune stimulation at insemination and conceptus secretion of IFN-τ, pregnancy-associated glycoproteins, prostaglandins, and other molecules whose effects on immune function during early pregnancy have not been determined. Our working hypothesis is that pregnancy induces changes in immune cell populations and functions that are biased toward immunological tolerance, tissue remodeling, and angiogenesis. This review summarizes current knowledge, starting with insemination and proceeding through early pregnancy, as this is the period of maximal embryo loss. Results indicated that early pregnancy is accompanied by a marked increase in the proportion of endometrial immune cells expressing markers for natural killer (CD335) cells and cytotoxic T cells (CD8) along with an increase in cells expressing major histocompatibility class II antigens (macrophages and dendritic cells). This is accompanied by increased abundance of mRNA for IL-15, a natural killer growth factor, and IL-10 in the endometrium during early pregnancy. Furthermore, expression of indoleamine 2,3 dioxygenase was 15-fold greater in pregnant compared with cyclic heifers at d 17, but then declined by d 20. This enzyme converts tryptophan to kynurenine, which alters immune function by creating a localized tryptophan deficiency and by activation of the aryl hydrocarbon receptor and induction of downstream tolerogenic mediators. Expression of the aryl hydrocarbon receptor is abundant in the bovine uterus, but its temporal and spatial regulation during early pregnancy have not been characterized. Pregnancy is also associated with increased expression of proteins known to inhibit immune activation, including programed cell death ligand-1 (CD274), lymphocyte activation gene-3 (CD223), and cytotoxic T-lymphocyte associated protein-4 (CD152). These molecules interact with receptors on antigen-presenting cells and induce lymphocyte tolerance. Current results support the hypothesis that early pregnancy signaling in dairy heifers involves changes in the proportions of immune cells in the endometrium as well as induction of molecules known to mediate tolerance. These changes are likely essential for uterine wall remodeling, placentation, and successful pregnancy.

Transcriptome profiles in peripheral white blood cells at the time of artificial insemination discriminate beef heifers with different fertility potential

Background

Infertility is a longstanding limitation in livestock production with important economic impact for the cattle industry. Female reproductive traits are polygenic and lowly heritable in nature, thus selection for fertility is challenging. Beef cattle operations leverage estrous synchronization in combination with artificial insemination (AI) to breed heifers and benefit from an early and uniform calving season. A couple of weeks following AI, heifers are exposed to bulls for an opportunity to become pregnant by natural breeding (NB), but they may also not become pregnant during this time period. Focusing on beef heifers, in their first breeding season, we hypothesized that: a- at the time of AI, the transcriptome of peripheral white blood cells (PWBC) differs between heifers that become pregnant to AI and heifers that become pregnant late in the breeding season by NB or do not become pregnant during the breeding season; and b- the ratio of transcript abundance between genes in PWBC classifies heifers according to pregnancy by AI, NB, or failure to become pregnant.

Results

We generated RNA-sequencing data from 23 heifers from two locations (A: six AI-pregnant and five NB-pregnant; and B: six AI-pregnant and six non-pregnant). After filtering out lowly expressed genes, we quantified transcript abundance for 12,538 genes. The comparison of gene expression levels between AI-pregnant and NB-pregnant heifers yielded 18 differentially expressed genes (DEGs) (ADAM20, ALDH5A1, ANG, BOLA-DQB, DMBT1, FCER1A, GSTM3, KIR3DL1, LOC107131247, LOC618633, LYZ, MNS1, P2RY12, PPP1R1B, SIGLEC14, TPPP, TTLL1, UGT8, eFDR≤0.02). The comparison of gene expression levels between AI-pregnant and non-pregnant heifers yielded six DEGs (ALAS2, CNKSR3, LOC522763, SAXO2, TAC3, TFF2, eFDR≤0.05). We calculated the ratio of expression levels between all gene pairs and assessed their potential to classify samples according to experimental groups. Considering all samples, relative expression from two gene pairs correctly classified 10 out of 12 AI-pregnant heifers (P = 0.0028) separately from the other 11 heifers (NB-pregnant, or non-pregnant).

Conclusion

The transcriptome profile in PWBC, at the time of AI, is associated with the fertility potential of beef heifers. Transcript levels of specific genes may be further explored as potential classifiers, and thus selection tools, of heifer fertility.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-4505-4) contains supplementary material, which is available to authorized users.