Induced endometritis in early lactation compromises production and reproduction in dairy cows

Objectives of this experiment were to study the effect of infusing utero-pathogenic bacteria to induce endometrial inflammation on productive performance in early lactation and subsequent reproduction. Although endometritis is associated with perturbed reproduction, numerous factors may contribute to the observed association. It was hypothesized that induced endometrial inflammation, resulting in localized and systemic inflammatory responses, compromises production and reproduction. Holstein cows without clinical disease and with less than 18% polymorphonuclear leukocytes (PMN) in endometrial cytology on d 31 ± 3 postpartum had their estrous cycle synchronized. Cows were blocked by parity and genomic breeding value for cow conception rate and, within block, assigned randomly to remain as untreated controls (CON; n = 37) or to receive an intrauterine infusion of 5.19 × 10⁸ cfu Escherichia coli and 4.34 × 10⁸ cfu Trueperella pyogenes during the luteal phase to induce endometrial inflammation (INF; n = 48). Endometrial cytology was taken on d 2 and 7 after treatment to evaluate the proportion of PMN. Rectal temperature, dry matter intake, and yields of milk and components were measured in the first 7 d after treatment. Blood serum was analyzed for concentration of haptoglobin. Leukocytes were isolated from blood on d 2 and 7 after treatment and on d 19 after artificial insemination (AI) and mRNA was quantified for a select group of genes. Cows received AI and reproduction was followed for 300 d postpartum. Bacterial infusion induced endometrial inflammation with increased proportions of PMN in the endometrial cytology on d 2 (4.4 ± 0.7 vs. 26.3 ± 2.8%) and 7 (10.9 ± 1.7 vs. 17.4 ± 2.1%) after treatment, resulting in increased mean prevalence of subclinical endometritis (>10% PMN; 23.3 ± 6.3 vs. 80.9 ± 5.1%). Rectal temperature did not differ between CON and INF, but the concentration of haptoglobin in serum tended to increase in INF compared with CON (113 ± 14 vs. 150 ± 16 µg/mL). Induced endometrial inflammation reduced yields of milk (44.9 ± 0.8 vs. 41.6 ± 0.8 kg/d), protein (1.19 ± 0.03 vs. 1.12 ± 0.03 kg/d), and lactose (2.17 ± 0.04 vs. 2.03 ± 0.04 kg/d) and tended to reduce dry matter intake (20.7 ± 0.5 vs. 19.4 ± 0.6 kg/d) in the first 7 d after treatment. Indeed, the reduction in milk yield lasted 4 wk. However, treatment did not affect yields of energy-corrected milk or fat because treatment with INF increased the concentration of fat in milk (3.54 ± 0.10 vs. 3.84 ± 0.10%). Induced endometrial inflammation reduced pregnancy per AI at all inseminations (33.4 ± 5.1 vs. 21.6 ± 3.7%) and the hazard of pregnancy (0.61; 95% CI = 0.36-1.04), which extended the median days open by 24 d. Blood leukocytes from INF cows had increased mRNA expression of the pro-inflammatory gene IL1B on d 2 and 7 after treatment, but reduced expression of the IFN-stimulated genes ISG15 and MX2 on d 19 after AI. Induced endometrial inflammation depressed production and caused long-term negative effects on reproduction in lactating dairy cows.

Cholesterol supports bovine granulosa cell inflammatory responses to lipopolysaccharide

During bacterial infections of the bovine uterus or mammary gland, ovarian granulosa cells mount inflammatory responses to lipopolysaccharide (LPS). In vitro, LPS stimulates granulosa cell secretion of the cytokines IL-1α and IL-1β, and the chemokine IL-8. These LPS-stimulated inflammatory responses depend on culturing granulosa cells with serum, but the mechanism is unclear. Here we tested the hypothesis that cholesterol supports inflammatory responses to LPS in bovine granulosa cells. We used granulosa cells isolated from 4-8 mm and > 8.5 mm diameter ovarian follicles and manipulated the availability of cholesterol. We found that serum or follicular fluid containing cholesterol increased LPS-stimulated secretion of IL-1α and IL-1β from granulosa cells. Conversely, depleting cholesterol using methyl-β-cyclodextrin diminished LPS-stimulated secretion of IL-1α, IL-1β and IL-8 from granulosa cells cultured in serum. Follicular fluid contained more high-density lipoprotein cholesterol than low-density lipoprotein cholesterol, and granulosa cells expressed the receptor for high-density lipoprotein, scavenger receptor class B member 1 (SCARB1). Furthermore, culturing granulosa cells with high-density lipoprotein cholesterol, but not low-density lipoprotein or very low-density lipoprotein cholesterol, increased LPS-stimulated inflammation in granulosa cells. Cholesterol biosynthesis also played a role in granulosa cell inflammation because RNA interference of mevalonate pathway enzymes inhibited LPS-stimulated inflammation. Finally, treatment with follicle-stimulating hormone, but not luteinizing hormone, increased LPS-stimulated granulosa cell inflammation, and follicle-stimulating hormone increased SCARB1 protein. However, changes in inflammation were not associated with changes in oestradiol or progesterone secretion. Taken together these findings imply that cholesterol supports inflammatory responses to LPS in granulosa cells.

Oxysterols Protect Epithelial Cells Against Pore-Forming Toxins

Many species of bacteria produce toxins such as cholesterol-dependent cytolysins that form pores in cell membranes. Membrane pores facilitate infection by releasing nutrients, delivering virulence factors, and causing lytic cell damage - cytolysis. Oxysterols are oxidized forms of cholesterol that regulate cellular cholesterol and alter immune responses to bacteria. Whether oxysterols also influence the protection of cells against pore-forming toxins is unresolved. Here we tested the hypothesis that oxysterols stimulate the intrinsic protection of epithelial cells against damage caused by cholesterol-dependent cytolysins. We treated epithelial cells with oxysterols and then challenged them with the cholesterol-dependent cytolysin, pyolysin. Treating HeLa cells with 27-hydroxycholesterol, 25-hydroxycholesterol, 7α-hydroxycholesterol, or 7β-hydroxycholesterol reduced pyolysin-induced leakage of lactate dehydrogenase and reduced pyolysin-induced cytolysis. Specifically, treatment with 10 ng/ml 27-hydroxycholesterol for 24 h reduced pyolysin-induced lactate dehydrogenase leakage by 88%, and reduced cytolysis from 74% to 1%. Treating HeLa cells with 27-hydroxycholesterol also reduced pyolysin-induced leakage of potassium ions, prevented mitogen-activated protein kinase cell stress responses, and limited alterations in the cytoskeleton. Furthermore, 27-hydroxycholesterol reduced pyolysin-induced damage in lung and liver epithelial cells, and protected against the cytolysins streptolysin O and Staphylococcus aureus α-hemolysin. Although oxysterols regulate cellular cholesterol by activating liver X receptors, cytoprotection did not depend on liver X receptors or changes in total cellular cholesterol. However, oxysterol cytoprotection was partially dependent on acyl-CoA:cholesterol acyltransferase (ACAT) reducing accessible cholesterol in cell membranes. Collectively, these findings imply that oxysterols stimulate the intrinsic protection of epithelial cells against pore-forming toxins and may help protect tissues against pathogenic bacteria.

Review: Perspective on high-performing dairy cows and herds

Milk and dairy products provide highly sustainable concentrations of essential amino acids and other required nutrients for humans; however, amount of milk currently produced per dairy cow globally is inadequate to meet future needs. Higher performing dairy cows and herds produce more milk with less environmental impact per kg than lower performing cows and herds. In 2018, 15.4% of the world's dairy cows produced 45.4% of the world's dairy cow milk, reflecting the global contribution of high-performing cows and herds. In high-performing herds, genomic evaluations are utilized for multiple trait selection, welfare is monitored by remote sensing, rations are formulated at micronutrient levels, health care is focused on prevention and reproduction is managed with precision. Higher performing herds require more inputs and generate more waste products per cow, thus innovations in environmental management on such farms are essential for lowering environmental impacts. Our focus is to provide perspectives on technologies and practices that contribute most to sustainable production of milk from high-performing dairy cows and herds.

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.

FOXL2 is a Progesterone Target Gene in the Endometrium of Ruminants

Forkhead Box L2 (FOXL2) is a member of the FOXL class of transcription factors, which are essential for ovarian differentiation and function. In the endometrium, FOXL2 is also thought to be important in cattle; however, it is not clear how its expression is regulated. The maternal recognition of pregnancy signal in cattle, interferon-Tau, does not regulate FOXL2 expression. Therefore, in the present study, we examined whether the ovarian steroid hormones that orchestrate implantation regulate FOXL2 gene expression in ruminants. In sheep, we confirmed that FOXL2 mRNA and protein was expressed in the endometrium across the oestrous cycle (day 4 to day 15 post-oestrus). Similar to the bovine endometrium, ovine FOXL2 endometrial expression was low during the luteal phase of the oestrous cycle (4 to 12 days post-oestrus) and at implantation (15 days post-oestrus) while mRNA and protein expression significantly increased during the luteolytic phase (day 15 post-oestrus in cycle). In pregnant ewes, inhibition of progesterone production by trilostane during the day 5 to 16 period prevented the rise in progesterone concentrations and led to a significant increase of FOXL2 expression in caruncles compared with the control group (1.4-fold, p < 0.05). Ovariectomized ewes or cows that were supplemented with exogenous progesterone for 12 days or 6 days, respectively, had lower endometrial FOXL2 expression compared with control ovariectomized females (sheep, mRNA, 1.8-fold; protein, 2.4-fold; cattle; mRNA, 2.2-fold; p < 0.05). Exogenous oestradiol treatments for 12 days in sheep or 2 days in cattle did not affect FOXL2 endometrial expression compared with control ovariectomized females, except at the protein level in both endometrial areas in the sheep. Moreover, treating bovine endometrial explants with exogenous progesterone for 48h reduced FOXL2 expression. Using in vitro assays with COS7 cells we also demonstrated that progesterone regulates the FOXL2 promoter activity through the progesterone receptor. Collectively, our findings imply that endometrial FOXL2 is, as a direct target of progesterone, involved in early pregnancy and implantation.

Invited review: Learning from the future-A vision for dairy farms and cows in 2067

The world's population will reach 10.4 billion in 2067, with 81% residing in Africa or Asia. Arable land available for food production will decrease to 0.15 ha per person. Temperature will increase in tropical and temperate zones, especially in the Northern Hemisphere, and this will push growing seasons and dairy farming away from arid areas and into more northern latitudes. Dairy consumption will increase because it provides essential nutrients more efficiently than many other agricultural systems. Dairy farming will become modernized in developing countries and milk production per cow will increase, doubling in countries with advanced dairying systems. Profitability of dairy farms will be the key to their sustainability. Genetic improvements will include emphasis on the coding genome and associated noncoding epigenome of cattle, and on microbiomes of dairy cattle and farmsteads. Farm sizes will increase and there will be greater lateral integration of housing and management of dairy cattle of different ages and production stages. Integrated sensors, robotics, and automation will replace much of the manual labor on farms. Managing the epigenome and microbiome will become part of routine herd management. Innovations in dairy facilities will improve the health of cows and permit expression of natural behaviors. Herds will be viewed as superorganisms, and studies of herds as observational units will lead to improvements in productivity, health, and well-being of dairy cattle, and improve the agroecology and sustainability of dairy farms. Dairy farmers in 2067 will meet the world's needs for essential nutrients by adopting technologies and practices that provide improved cow health and longevity, profitable dairy farms, and sustainable agriculture.

Inhibiting mevalonate pathway enzymes increases stromal cell resilience to a cholesterol-dependent cytolysin

Animal health depends on the ability of immune cells to kill invading pathogens, and on the resilience of tissues to tolerate the presence of pathogens. Trueperella pyogenes causes tissue pathology in many mammals by secreting a cholesterol-dependent cytolysin, pyolysin (PLO), which targets stromal cells. Cellular cholesterol is derived from squalene, which is synthesized via the mevalonate pathway enzymes, including HMGCR, FDPS and FDFT1. The present study tested the hypothesis that inhibiting enzymes in the mevalonate pathway to reduce cellular cholesterol increases the resilience of stromal cells to PLO. We first verified that depleting cellular cholesterol with methyl-β-cyclodextrin increased the resilience of stromal cells to PLO. We then used siRNA to deplete mevalonate pathway enzyme gene expression, and used pharmaceutical inhibitors, atorvastatin, alendronate or zaragozic acid to inhibit the activity of HMGCR, FDPS and FDFT1, respectively. These approaches successfully reduced cellular cholesterol abundance, but mevalonate pathway enzymes did not affect cellular resilience equally. Inhibiting FDFT1 was most effective, with zaragozic acid reducing the impact of PLO on cell viability. The present study provides evidence that inhibiting FDFT1 increases stromal cell resilience to a cholesterol-dependent cytolysin.

Analysis of STAT1 expression and biological activity reveals interferon-tau-dependent STAT1-regulated SOCS genes in the bovine endometrium

Signal transducer and activator of transcription (STAT) proteins are critical for the regulation of numerous biological processes. In cattle, microarray analyses identified STAT1 as a differentially expressed gene in the endometrium during the peri-implantation period. To gain new insights about STAT1 during the oestrous cycle and early pregnancy, we investigated STAT1 transcript and protein expression, as well as its biological activity in bovine tissue and cells of endometrial origin. Pregnancy increased STAT1 expression on Day 16, and protein and phosphorylation levels on Day 20. In cyclic and pregnant females, STAT1 was located in endometrial cells but not in the luminal epithelium at Day 20 of pregnancy. The expression of STAT1 during the oestrous cycle was not affected by progesterone supplementation. In vivo and in vitro, interferon-tau (IFNT) stimulated STAT1 mRNA expression, protein tyrosine phosphorylation and nuclear translocation. Using chromatin immunoprecipitation in IFNT-stimulated endometrial cells, we demonstrated an increase of STAT1 binding on interferon regulatory factor 1 (IRF1), cytokine-inducible SH2-containing protein (CISH), suppressor of cytokine signaling 1 and 3 (SOCS1, SOCS3) gene promoters consistent with the induction of their transcripts. Our data provide novel molecular insights into the biological functions of STAT1 in the various cells composing the endometrium during maternal pregnancy recognition and implantation.

Signal transducer and activator of transcription-3 licenses Toll-like receptor 4-dependent interleukin (IL)-6 and IL-8 production via IL-6 receptor-positive feedback in endometrial cells

Interleukin 6 (IL-6), acting via the IL-6 receptor (IL6R) and signal transducer and activator of transcription-3 (STAT3), limits neutrophil recruitment once bacterial infections are resolved. Bovine endometritis is an exemplar mucosal disease, characterized by sustained neutrophil infiltration and elevated IL-6 and IL-8, a neutrophil chemoattractant, following postpartum Gram-negative bacterial infection. The present study examined the impact of the IL6R/STAT3 signaling pathway on IL-8 production by primary endometrial cells in response to short- or long-term exposure to lipopolysaccharide (LPS) from Gram-negative bacteria. Tyrosine phosphorylation of STAT3 is required for DNA binding and expression of specific targets genes. Immunoblotting indicated constitutive tyrosine phosphorylation of STAT3 in endometrial cells was impeded by acute exposure to LPS. After 24 h exposure to LPS, STAT3 returned to a tyrosine phosphorylated state, indicating cross-talk between the Toll-like receptor 4 (TLR4) and the IL6R/STAT3 signaling pathways. This was confirmed by short interfering RNA targeting the IL6R, which abrogated the accumulation of IL-6 and IL-8, induced by LPS. Furthermore, there was a differential endometrial cell response, as the accumulation of IL-6 and IL-8 was dependent on STAT3, suppressor of cytokine signaling 3, and Src kinase signaling in stromal cells, but not epithelial cells. In conclusion, positive feedback through the IL6R amplifies LPS-induced IL-6 and IL-8 production in the endometrium. These findings provide a mechanistic insight into how elevated IL-6 concentrations in the postpartum endometrium during bacterial infection leads to marked and sustained neutrophil infiltration.

Innate immunity and the sensing of infection, damage and danger in the female genital tract

Tissue homeostasis in the female genital tract is challenged by infection, damage, and even physiological events during reproductive cycles. We propose that the evolutionarily ancient system of innate immunity is sufficient to sense and respond to danger in the non-pregnant female genital tract. Innate immunity produces a rapidly inducible, non-specific response when cells sense danger. Here we provide a primer on innate immunity and discuss what is known about how danger signals are sensed in the endometrium and ovary, the impact of inflammatory responses on reproduction, and how endocrinology and innate immunity are integrated. Endometrial epithelial and stromal cells, and ovarian granulosa cells express pattern recognition receptors, similar to cells of the innate immune system. These pattern recognition receptors, such as the Toll-like receptors, bind pathogen-associated or damage-associated molecular patterns. Activation of pattern recognition receptors leads to inflammation, recruitment of immune cells from the peripheral circulation, and phagocytosis. Although the inflammatory response helps maintain or restore endometrial health, there may also be negative consequences for fertility, including perturbation of oocyte competence. The intensity of the inflammatory response reflects the balance between the level of danger and the systems that regulate innate immunity, including the endocrine environment. Understanding innate immunity is important because disease and inappropriate inflammatory responses in the endometrium or ovary cause infertility.

Tethered bilayer membranes as a complementary tool for functional and structural studies: The pyolysin case

We demonstrate the use of tethered bilayer lipid membranes (tBLMs) as an experimental platform for functional and structural studies of membrane associated proteins by electrochemical techniques. The reconstitution of the cholesterol-dependent cytolysin (CDC) pyolysin (PLO) from Trueperella pyogenes into tBLMs was followed in real-time by electrochemical impedance spectroscopy (EIS). Changes of the EIS parameters of the tBLMs upon exposure to PLO solutions were consistent with the dielectric barrier damage occurring through the formation of water-filled pores in membranes. Parallel experiments involving a mutant version of PLO, which is able to bind to the membranes but does not form oligomer pores, strengthen the reliability of this methodology, since no change in the electrochemical impedance was observed. Complementary atomic force microscopy (AFM) and neutron reflectometry (NR) measurements revealed structural details of the membrane bound PLO, consistent with the structural transformations of the membrane bound toxins found for other cholesterol dependent cytolysins. In this work, using the tBLMs platform we also observed a protective effect of the dynamin inhibitor Dynasore against pyolysin as well as pneumolysin. An effect of Dynasore in tBLMs, which was earlier observed in experiments with live cells, confirms the biological relevance of the tBLMs models, as well as demonstrates the potential of the electrochemical impedance spectroscopy to quantify membrane damage by the pore forming toxins. In conclusion, tBLMs are a reliable and complementary method to explore the activity of CDCs in eukaryotic cells and to develop strategies to limit the toxic effects of CDCs.

PHYSIOLOGY AND ENDOCRINOLOGY SYMPOSIUM: Uterine infection: linking infection and innate immunity with infertility in the high-producing dairy cow

Uterine contamination with bacteria is ubiquitous in the postpartum dairy cow. Nearly one-half of all postpartum dairy cows develop clinical disease resulting in metritis and endometritis, which cause depressed milk production and infertility. The causative links between uterine infection and infertility include a hostile uterine environment, disrupted endocrine signaling, and perturbations in ovarian function and oocyte development. In this review we consider the various mechanisms linking uterine infection with infertility in the dairy cow, specifically 1) innate immune signaling in the endometrium, 2) alteration in endocrine signaling in response to infectious agents, and 3) impacts of infection on ovarian function, oocyte development, and follicular development. Normal ovarian follicular and oocyte development requires a series of temporally and spatially orchestrated events; however, several of the cellular pathways required for ovarian function are also used during the innate immune response to bacterial pathogens. We propose that activation of cellular pathways during this immune response has a negative impact on ovarian physiology, which is manifest as infertility detected after the clearance of the bacteria. This review highlights how new insights into infection and immunity in cattle are linked to infertility.

Mechanisms linking bacterial infections of the bovine endometrium to disease and infertility

Bacterial infections of the endometrium after parturition commonly cause metritis and endometritis in dairy cattle, and these diseases are important because they compromise animal welfare and incur economic costs, as well as delaying or preventing conception. Here we highlight that uterine infections cause infertility, discuss which bacteria cause uterine disease, and review the evidence for mechanisms of inflammation and tissue damage in the endometrium. Bacteria cultured from the uterus of diseased animals include Escherichia coli, Trueperella pyogenes, and several anaerobic species, but their causative role in disease is challenged by the discovery of many other bacteria in the uterine disease microbiome. Irrespective of the species of bacteria, endometrial cell inflammatory responses to infection initially depend on innate immunity, with Toll-like receptors binding pathogen-associated molecular patterns, such as lipopolysaccharide and bacterial lipopeptides. In addition to tissue damage associated with parturition and inflammation, endometrial cell death is caused by a cholesterol-dependent cytolysin secreted by T. pyogenes, called pyolysin, which forms pores in plasma membranes of endometrial cells. However, endometrial cells surprisingly do not sense damage-associated molecular patterns, but a combination of infections followed by cell damage leads to release of the intracellular cytokine interleukin (IL)-1 alpha from endometrial cells, which then acts to scale inflammatory responses. To develop strategies to limit the impact of uterine disease on fertility, future work should focus on determining which bacteria and virulence factors cause endometritis, and understanding how the host response to infection is regulated in the endometrium.

A three-dimensional model of primary bovine endometrium using an electrospun scaffold

Endometrial stromal and epithelial cell function is typically studied in vitro using standard two-dimensional monocultures, but these cultures fail to reflect the complex three-dimensional (3D) architecture of tissue. A 3D model of bovine endometrium that reflects the architectural arrangement of in vivo tissue would beneficially assist the study of tissue function. An electrospun polyglycolide (PGA) scaffold was selected to grow a 3D model of primary bovine endometrial epithelial and stromal cells, that reflects the architecture of the endometrium for the study of pathophysiology. Electrospun scaffolds were seeded with stromal and epithelial cells, and growth was assessed using histological techniques. Prostaglandin E2 and prostaglandin F2α responsiveness of endometrial scaffold constructs was tested using oxytocin plus arachidonic acid (OT + AA) or lipopolysaccharide (LPS). Stromal and epithelial cells growing on the electrospun scaffold had an architectural arrangement that mimicked whole tissue, deposited fibronectin, had appropriate expression of vimentin and cytokeratin and were responsive to OT + AA and LPS, as measured by prostaglandin accumulation. In conclusion, a functional 3D model of stromal and epithelial cells was developed using a PGA electrospun scaffold which may be used to study endometrial pathophysiology.

SOCS genes expression during physiological and perturbed implantation in bovine endometrium

In mammals, suppressor of cytokine signalling (CISH, SOCS1 to SOCS7) factors control signalling pathways involved in the regulation of numerous physiological processes including pregnancy. In order to gain new insights into the biological functions of SOCS in the endometrium, a comprehensive analysis of SOCS gene expression was carried out in bovine caruncular (CAR) and intercaruncular (ICAR) tissues collected i) during the oestrous cycle, ii) at the time of maternal recognition of pregnancy and at implantation in inseminated females, iii) following uterine interferon-tau (IFNT) infusion at day 14 post-oestrus, iv) following a period of controlled intravaginal progesterone release and v) following transfer of embryos by somatic-cell nuclear transfer (SCNT). The regulatory effects of IFNT on in vitro cultured epithelial and stromal cells were also examined. Altogether, our data showed that CISH, SOCS4, SOCS5 and SOCS7 mRNA levels were poorly affected during luteolysis and pregnancy. In contrast, SOCS1, SOCS2, SOCS3 and SOCS6 mRNA levels were strongly up-regulated at implantation (day 20 of pregnancy). Experimental in vitro and in vivo models demonstrated that only CISH, SOCS1, SOCS2 and SOCS3 were IFNT-induced genes. Immunohistochemistry showed an intense SOCS3 and SOCS6 staining in the nucleus of luminal and glandular epithelium and of stromal cells of pregnant endometrium. Finally, SOCS3 expression was significantly increased in SCNT pregnancies in keeping with the altered immune function previously reported in this model of compromised implantation. Collectively, our data suggest that spatio-temporal changes in endometrial SOCS gene expression reflect the acquisition of receptivity, maternal recognition of pregnancy and implantation.

Epithelial and stromal cells of bovine endometrium have roles in innate immunity and initiate inflammatory responses to bacterial lipopeptides in vitro via Toll-like receptors TLR2, TLR1, and TLR6

Bacteria often infect the endometrium of cattle to cause endometritis, uterine disease, and infertility. Lipopeptides are commonly found among bacteria and are detected by the Toll-like receptor (TLR) cell surface receptor TLR2 on immune cells. Heterodimers of TLR2 with TLR1 or TLR6 activate MAPK and nuclear factor-κB intracellular signaling pathways to stimulate inflammatory responses. In the endometrium, epithelial and stromal cells are the first to encounter invading bacteria, so the present study explored whether endometrial cells can also mount inflammatory responses to bacterial lipopeptides via TLRs. The supernatants of pure populations of primary bovine endometrial epithelial and stromal cells accumulated the cytokine IL-6 and the chemokine IL-8 in response to triacylated or diacylated bacterial lipopeptides. The accumulation of IL-6 and IL-8 in response to triacylated lipopeptides was reduced by small interfering RNA targeting TLR2 or TLR1 but not TLR6, whereas cellular responses to diacylated lipopeptide were reduced by small interfering RNA targeting TLR2, TLR1, or TLR6. Both lipopeptides induced rapid phosphorylation of ERK1/2, p38, and nuclear factor-κB in endometrial cells, and inhibitors of ERK1/2 or p38 limited the accumulation of IL-6. The ovarian steroids estradiol and progesterone had little impact on inflammatory responses to lipopeptides. The endometrial epithelial and stromal cell responses to lipopeptides via TLR2, TLR1, and TLR6 provide a mechanism linking a wide range of bacterial infections to inflammation of the endometrium.

Differential endometrial cell sensitivity to a cholesterol-dependent cytolysin links Trueperella pyogenes to uterine disease in cattle

Purulent disease of the uterus develops in 40% of dairy cows after parturition, when the epithelium of the endometrium is disrupted to expose the underlying stroma to bacteria. The severity of endometrial pathology is associated with isolation of Trueperella pyogenes. In the present study, T. pyogenes alone caused uterine disease when infused into the uterus of cattle where the endometrial epithelium was disrupted. The bacterium secretes a cholesterol-dependent cytolysin, pyolysin (PLO), and the plo gene was identical and the plo gene promoter was highly similar amongst 12 clinical isolates of T. pyogenes. Bacteria-free filtrates of the T. pyogenes cultures caused hemolysis and endometrial cytolysis, and PLO was the main cytolytic agent, because addition of anti-PLO antibody prevented cytolysis. Similarly, a plo-deletion T. pyogenes mutant did not cause hemolysis or endometrial cytolysis. Endometrial stromal cells were notably more sensitive to PLO-mediated cytolysis than epithelial or immune cells. Stromal cells also contained more cholesterol than epithelial cells, and reducing stromal cell cholesterol content using cyclodextrins protected against PLO. Although T. pyogenes or plo-deletion T. pyogenes stimulated accumulation of inflammatory mediators, such as IL-1beta, IL-6, and IL-8, from endometrium, PLO did not stimulate inflammatory responses by endometrial or hematopoietic cells, or in vitro organ cultures of endometrium. The marked sensitivity of stromal cells to PLO-mediated cytolysis provides an explanation for how T. pyogenes acts as an opportunistic pathogen to cause pathology of the endometrium once the protective epithelium is lost after parturition.

Peripheral blood leukocytes of cows with subclinical endometritis show an altered cellular composition and gene expression

Subclinical endometritis (SCE) is an important postpartum disease in dairy cows, but conventional cytobrush diagnosis often gives imprecise results. The aim of this study was to analyze disease-associated changes in peripheral blood as potential diagnostic parameters. Cellular subpopulations of blood leukocytes from cows with or without SCE (45-55 days postpartum) were flow-cytometrically quantified. Gene expression of whole blood leukocytes was assessed by PAXgene analysis. Subclinical endometritis cows showed significantly higher number of blood mononuclear cells and neutrophils. Among mononuclear cells, numbers of B-cells, NK-cells, and CD172a-positive monocytes were significantly elevated. Compared with non-SCE cows, blood leukocytes of SCE cows significantly expressed higher copy numbers of CXCL8, TNF, and IL12. To test whether circulating plasma factors are responsible for these changes, leukocytes, polymorphonuclear cells, and monocyte subpopulations (classical, intermediate, nonclassical) of healthy cows were stimulated with plasma of SCE and non-SCE cows. Although gene expression of whole leukocytes and polymorphonuclear cells remained unaltered, plasma from SCE animals significantly elevated expressed messenger RNA copy numbers of CXCL8, CXCL1, and IL1B in intermediate monocytes. In conclusion, elevated number of selected mononuclear subpopulations in peripheral blood and enhanced expression of distinct genes encoding for inflammatory mediators in blood leukocytes reflect the subclinical uterine inflammatory process in cows. Whether the observed changes in the periphery of SCE cows are the consequence of the uterine inflammatory process, or whether they affect the pathogenesis of the disease is currently unknown.

Granulosa cells from emerged antral follicles of the bovine ovary initiate inflammation in response to bacterial pathogen-associated molecular patterns via Toll-like receptor pathways

Bacterial infections of the uterus or mammary gland commonly perturb ovarian antral follicle growth and function, causing infertility in cattle. Cells of the innate immune system use Toll-like receptors (TLRs) TLR2, TLR4, and TLR5 to recognize pathogen-associated molecular patterns (PAMPs) of bacteria, leading to production of inflammatory mediators, such as IL-1beta, IL-6, and IL-8. The present study examined whether granulosa cells from emerged antral follicles have functional responses to typical bacterial PAMPs. Granulosa cells from emerged bovine antral follicles expressed mRNA for all 10 TLRs. Cellular expression of mRNA for the cytokines IL1B, IL6, IL10, and TNF, and chemokines IL8 and CCL5, increased after treatment with synthetic bacterial lipoprotein binding TLR2, lipopolysaccharide binding TLR4, or flagellin binding TLR5. Supernatants of granulosa cells accumulated IL-1beta, IL-6, and IL-8 protein in a concentration-dependent manner when treated with lipoprotein or lipopolysaccharide, but not flagellin. Accumulation of IL6 in response to lipoprotein and lipopolysaccharide was attenuated using siRNA targeting TLR2 and TLR4, respectively. Granulosa cells increased phosphorylation of mitogen-activated protein kinase (MAPK) 14 and MAPK3/1 within 30 min of treatment with lipopolysaccharide or lipoprotein, and inhibitors targeting MAPK14 reduced the accumulation of IL-6 in response to the PAMPs. Treatment with hormones follicle-stimulating hormone, luteinizing hormone, estradiol, or progesterone did not significantly affect granulosa cell responses to PAMPs. However, epidermal growth factor enhanced IL-6 accumulation in response to lipoprotein and inhibiting epidermal growth factor receptor (EGFR) abrogated the effect, whereas lipoprotein increased granulosa cell EGFR mRNA expression. In conclusion, bovine granulosa cells from emerged follicles sense bacterial PAMPs and initiate inflammatory responses via TLR2 and TLR4 pathways.

Immunity and inflammation in the uterus

Microbes often infect the uterus and particularly the endometrium of animals. Infections are most commonly associated with natural service, pregnancy and the post-partum period, leading to inflammation with the elaboration of cytokines, chemokines and prostaglandins. Clinical diseases such as metritis, endometritis and abortion are important causes of infertility. The adaptive immune response to infection has been characterized previously, so the present review aims to highlight the emerging role for innate immunity in the endometrium. The detection of microbes and the innate immune response depends on the detection of pathogen-associated molecular patterns by pattern recognition receptors. The main families of pattern recognition receptors are Toll-like receptors (TLRs), nucleotide oligomerization domain-like receptors, retinoic acid-inducible gene I-like receptors and C-type lectin receptors. These receptors are most often expressed by hematopoietic cells, but the epithelial and stromal cells of the endometrium also possess functional receptors. For example, endometrial cells express TLR4 for recognition of the lipopolysaccharide endotoxin of Gram-negative bacteria, leading to secretion of IL-6, IL-8 and prostaglandin E(2) . It is likely that the epithelial and stromal cells provide a first line of defence in the endometrium to alert hematopoietic cells to the presence of microbes within the uterus.

Explants of intact endometrium to model bovine innate immunity and inflammation ex vivo

PROBLEM

Bacterial infections commonly cause bovine endometritis and infertility via innate immune pathways. However, mechanistic studies using isolated cells or chopped tissue may be compromised by the disruption of endometrial architecture and release of damage-associated molecular patterns. So, this study aimed to establish an ex vivo model of intact bovine endometrium to study innate immunity and inflammation.

METHOD OF STUDY

Intact bovine endometrium explants were collected using a sterile 8-mm punch biopsy and cultured ex vivo with bacteria or pathogen-associated molecules. Interleukin accumulation was measured, and tissue viability was assessed by microscopy, TdT-mediated biotin-dUTP nick-end labelling and lactate dehydrogenase assay.

RESULTS

Intact endometrium explants accumulated IL-6, IL-1β and IL-8 in response to Gram-negative or Gram-positive bacteria, and their purified pathogen-associated molecules; inflammatory responses were dependent on the stage of oestrous cycle. Explants of intact endometrium maintained viability and tissue architecture, and had lower basal accumulation of interleukins compared with explants using chopped endometrium.

CONCLUSION

This study established a tractable ex vivo model of intact endometrium to explore the mechanisms of immunity and inflammation in the bovine endometrium.

Toll-like receptor 4 mediates the response of epithelial and stromal cells to lipopolysaccharide in the endometrium

BACKGROUND

Ascending infections of the female genital tract with bacteria causes pelvic inflammatory disease (PID), preterm labour and infertility. Lipopolysaccharide (LPS) is the main component of the cell wall of Gram-negative bacteria. Innate immunity relies on the detection of LPS by Toll-like receptor 4 (TLR4) on host cells. Binding of LPS to TLR4 on immune cells stimulates secretion of pro-inflammatory cytokines such as IL-6, chemokines such as CXCL1 and CCL20, and prostaglandin E(2). The present study tested the hypothesis that TLR4 on endometrial epithelial and stromal cells is essential for the innate immune response to LPS in the female genital tract.

METHODOLOGY/PRINCIPAL FINDINGS

Wild type (WT) mice expressed TLR4 in the endometrium. Intrauterine infusion of purified LPS caused pelvic inflammatory disease, with accumulation of granulocytes throughout the endometrium of WT but not Tlr4(-/-) mice. Intra-peritoneal infusion of LPS did not cause PID in WT or Tlr4(-/-) mice, indicating the importance of TLR4 in the endometrium for the detection of LPS in the female genital tract. Stromal and epithelial cells isolated from the endometrium of WT but not Tlr4(-/-) mice, secreted IL-6, CXCL1, CCL20 and prostaglandin E(2) in response to LPS, in a concentration and time dependent manner. Co-culture of combinations of stromal and epithelial cells from WT and Tlr4(-/-) mice provided little evidence of stromal-epithelial interactions in the response to LPS.

CONCLUSIONS/SIGNIFICANCE

The innate immune response to LPS in the female genital tract is dependent on TLR4 on the epithelial and stromal cells of the endometrium.

Markers of the uterine innate immune response of the mare

Reproductive efficiency in mares is low and persistent mating-induced endometritis (PMIE) is an important cause of subfertility. Mating-induced endometritis (MIE) an obligate precursor to PMIE, is a ubiquitous, transient inflammatory response to the presence of sperm, seminal components and pathogens. However, the specific inflammatory pathways that derive from MIE and that may also be precursors to PMIE are not clear. The ability to identify and measure robust, repeatable markers of inflammation integral to MIE may be key to understanding the progression to PMIE. The aim of the study was to (i) refine a protocol for inducing MIE and in doing so test a range of cellular and molecular parameters as valid markers of MIE to facilitate future studies of mares susceptible to PMIE (ii) concurrently identify those parameters with potential as inflammatory indicators during MIE to inform and enhance early treatment regimens in practice. Mating-induced endometritis was induced in pony mares using a stringent protocol; mares were treated intrauterine with frozen/thawed semen (n = 5; FTS) or frozen/thawed extender (n = 6: FTEx). The parameters tested were measured before treatment were compared to samples collected at strategic time points after treatment: uterine cytology using cytological (at 8, 16, 24, 48 and 72 h after treatment) or histological analysis (at 24 and 72 h); uterine bacteriology (at 24 and 72 h); secretion of prostaglandin F(2alpha) (PGF(2alpha); at 8, 16, 24, 48 and 72 h); peripheral concentrations of serum amyloid A (SAA; at 24h); endometrial mRNA gene expression, focussing upon IL8 and TLR4, as examples of genes pertinent to inflammation (at 24 h). Uterine neutrophil cell numbers in both treatment groups increased at 8 (P < 0.001), 16 (P < 0.01) and 24 (P < 0.01) h after insemination, indicative of MIE and distinguished between different treatments because neutrophil numbers were greater from FTS mares than FTEx mares 8h after challenge. Uterine neutrophil cell numbers, assessed by histology, increased (P < 0.001) 24 and 72 h after treatment. Prostaglandin F(2alpha) concentrations increased (P < 0.05) 16 h after treatments, while SAA concentrations and bacterial growth scores were not significantly different after treatment. Endometrium from pony mares expressed mRNA for IL8 and TLR4 but expression was not altered after insemination. The protocol induced MIE, as confirmed by uterine cytology and maybe used hereafter as a repeatable and robust method for studying immune mechanisms that underlie MIE and so may aid the understanding of progression to persistent inflammation. It can be concluded that of the range of parameters tested, neutrophil cell numbers by cytological analysis and PGF(2alpha) were regarded as the most accurate markers of inflammation during MIE and important for use in practice.

Mechanisms of infertility associated with clinical and subclinical endometritis in high producing dairy cattle

Clinical and subclinical endometritis are common causes of infertility and subfertility in high producing dairy cattle, delaying the onset of ovarian cyclic activity after parturition, extending luteal phases and reducing conception rates. Escherichia coli and Arcanobacterium pyogenes cause endometrial damage and inflammation. Components of microbes, such as lipopolysaccharide (LPS), are detected by Toll-like receptors on endometrial cells, leading to secretion of cytokines, chemokines and antimicrobial peptides. Long luteal phases associated with endometritis are probably caused by a switch in endometrial prostaglandin production from prostaglandin F2a (PGF) to prostaglandin E2. In addition, LPS impairs the function of the hypothalamus and pituitary, and directly perturbs ovarian granulosa cells steroidogenesis, providing mechanisms to explain the association between uterine disease and anovulatory anoestrus. Cows with uterine disease that ovulate have lower peripheral plasma progesterone concentrations that may further reduce the chance of conception associated with endometritis.

Isolation and characterization of bovine herpesvirus 4 (BoHV-4) from a cow affected by post partum metritis and cloning of the genome as a bacterial artificial chromosome

BACKGROUND

Bovine herpesvirus 4 (BoHV-4) is a gammaherpesvirus with a Worldwide distribution in cattle and is often isolated from the uterus of animals with postpartum metritis or pelvic inflammatory disease. Virus strain adaptation to an organ, tissue or cell type is an important issue for the pathogenesis of disease. To explore the mechanistic role of viral strain variation for uterine disease, the present study aimed to develop a tool enabling precise genetic discrimination between strains of BoHV-4 and to easily manipulate the viral genome.

METHODS

A strain of BoHV-4 was isolated from the uterus of a persistently infected cow and designated BoHV-4-U. The authenticity of the isolate was confirmed by RFLP-PCR and sequencing using the TK and IE2 loci as genetic marker regions for the BoHV-4 genome. The isolated genome was cloned as a Bacterial Artificial Chromosome (BAC) and manipulated through recombineering technology

RESULTS

The BoHV-4-U genome was successfully cloned as a BAC, and the stability of the pBAC-BoHV-4-U clone was confirmed over twenty passages, with viral growth similar to the wild type virus. The feasibility of using BoHV-4-U for mutagenesis was demonstrated using the BAC recombineering system.

CONCLUSION

The analysis of genome strain variation is a key method for investigating genes associated with disease. A resource for dissection of the interactions between BoHV-4 and host endometrial cells was generated by cloning the genome of BoHV-4 as a BAC.

Endometrial explant culture to study the response of equine endometrium to insemination

Mating-induced endometritis (MIE) is ubiquitous in the horse after natural mating and artificial insemination with frozen/thawed semen causing the most aggressive response. The majority of mares eliminate MIE 24-48 h after insemination. An endometrial explant culture was tested as a potential in vitro exemplar for sperm-induced MIE. Endometrial prostaglandin F(2alpha) (PGF(2alpha)) secretion and expression of interleukin-8 (IL-8) were used as markers of inflammation. Endometrial explants were cultured from uteri collected from follicular phase mares. Explants were challenged with 1 or 10 x 10(6) sperm/ml frozen/thawed semen, chilled semen, washed sperm or seminal plasma. Medium was collected 24 and 72 h after challenge and assayed for PGF(2alpha) by radioimmunoassay. Treatment of endometrial explants with frozen/thawed, chilled semen or washed sperm did not change the secretion of PGF(2alpha) compared with untreated controls. However, 24 h after challenge cultured explants expressed IL-8. The in vitro endometrial explant system did not represent the in vivo response to semen when PGF(2alpha) was used as a marker of inflammation, yet the use of gene expression as an inflammatory marker warrants further investigation.

Bovine endometrial stromal cells display osteogenic properties

The endometrium is central to mammalian fertility. The endometrial stromal cells are very dynamic, growing and differentiating throughout the estrous cycle and pregnancy. In humans, stromal cells appear to have progenitor or stem cell capabilities and the cells can even differentiate into bone. It is not clear whether bovine endometrial stromal cells exhibit a similar phenotypic plasticity. So, the present study tested the hypothesis that bovine endometrial stromal cells could be differentiated along an osteogenic lineage. Pure populations of bovine stromal cells were isolated from the endometrium. The endometrial stromal cell phenotype was confirmed by morphology, prostaglandin secretion, and susceptibility to viral infection. However, cultivation of the cells in standard endometrial cell culture medium lead to a mesenchymal phenotype similar to that of bovine bone marrow cells. Furthermore, the endometrial stromal cells developed signs of osteogenesis, such as alizarin positive nodules. When the stromal cells were cultured in a specific osteogenic medium the cells rapidly developed the characteristics of mineralized bone. In conclusion, the present study has identified that stromal cells from the bovine endometrium show a capability for phenotype plasticity similar to mesenchymal progenitor cells. These observations pave the way for further investigation of the mechanisms of stroma cell differentiation in the bovine reproductive tract.

Bacterial infection of endometrial stromal cells influences bovine herpesvirus 4 immediate early gene activation: a new insight into bacterial and viral interaction for uterine disease

Experimental infection with the gamma-herpesvirus bovine herpesvirus 4 (BoHV-4) rarely establishes disease, yet BoHV-4 is commonly associated with uterine disease in cattle. Uterine disease involves co-infection with bacteria such as Escherichia coli, which stimulate the production of prostaglandin E(2) (PGE(2)) by endometrial cells. BoHV-4 replication depends on immediate early 2 (IE2) gene transactivation and, in the present study, PGE(2), E. coli or its lipopolysaccharide upregulated the IE2 gene promoter in uterine cells. Bacterial co-infection is important for BoHV-4 uterine disease.

Field investigation of perinatal mortality in friesian cattle associated with myocardial degeneration and necrosis

Perinatal mortality and stillbirths were investigated in an extensively managed herd of Friesian cows and heifers calving over a 2-year period: 504 cows were calved and 215 heifers. Cows were bred to Friesian and Jersey bulls using natural service. The perinatal fetal mortality rate was 7.5% for cows and 30% for heifers. An experienced stockman managed these calvings and veterinary assistance was required only on nine occasions. All stillborn fetuses were examined post-mortem by the Veterinary Laboratories Agency, Carmarthen and no infectious agent was identified on any occasion. Thyroid hyperplasia was found in two fetuses. In blood samples taken from 10 late pregnant heifers, mean glutathione peroxidase values were 7.9 +/- 1.7 IU/ml Packed Cell Volume (PCV). Tissues from eight fetuses were submitted to the University of Liverpool for histopathological examination; all presented lesions consistent with myocardial degeneration and necrosis of the left ventricle. Following treatment of 205 late pregnant heifers with sodium selenite and vitamin E, the overall perinatal mortality rate in these cattle fell to below 11%.

Bovine herpesvirus 4 is tropic for bovine endometrial cells and modulates endocrine function

Bovine postpartum uterine disease, metritis, affects about 40% of animals and is widely considered to have a bacterial aetiology. Although the gamma-herpesvirus bovine herpesvirus 4 (BoHV-4) has been isolated from several outbreaks of metritis or abortion, the role of viruses in endometrial pathology and the mechanisms of viral infection of uterine cells are often ignored. The objectives of the present study were to explore the interaction, tropism and outcomes of BoHV-4 challenge of endometrial stromal and epithelial cells. Endometrial stromal and epithelial cells were purified and infected with a recombinant BoHV-4 carrying an enhanced green fluorescent protein (EGFP) expression cassette to monitor the establishment of infection. BoHV-4 efficiently infected both stromal and epithelial cells, causing a strong non-apoptotic cytopathic effect, associated with robust viral replication. The crucial step for the BoHV-4 endometriotropism appeared to be after viral entry as there was enhanced transactivation of the BoHV-4 immediate early 2 gene promoter following transient transfection into the endometrial cells. Infection with BoHV-4 increased cyclooxygenase 2 protein expression and prostaglandin estradiol secretion in endometrial stromal cells, but not epithelial cells. Bovine macrophages are persistently infected with BoHV-4, and co-culture with endometrial stromal cells reactivated BoHV-4 replication in the persistently infected macrophages, suggesting a symbiotic relationship between the cells and virus. In conclusion, the present study provides evidence of cellular and molecular mechanisms, supporting the concept that BoHV-4 is a pathogen associated with uterine disease.

Use of the cow as a large animal model of uterine infection and immunity

For most of the reproductive cycle in both humans and animals, the uterus is clear of pathogenic bacteria. However, it is readily contaminated with pathogens, such as Escherichia and Tritichomonas species, during sexual intercourse and after parturition. Uterine infection is particularly common after parturition in cattle (Bos taurus), causing clinical disease and infertility. The endocrine and immune responses to uterine infection in cattle have been investigated in vivo and using tissue culture. Cattle are of sufficient size to permit monitoring of reproductive and immune function throughout uterine infections, and primary cell cultures are readily established. In the whole animal, uterine infections suppress GnRH and LH secretion, and inhibit the growth of ovarian follicles and their estradiol secretion. The immune response is characterized by an influx of neutrophils into the uterus and increased concentrations of acute phase proteins in peripheral plasma. In vitro, the endometrial and ovarian cell function is modified by challenge with bacteria, their products such as lipopolysaccharide or pro-inflammatory cytokines. However, it is interesting to note that the susceptibility to uterine infection and the immune response are partially regulated by the ovarian steroid hormone mileu. In conclusion, the ease of working with cattle, the availability of tissues and the similarity of uterine infection between mammals, make Bos taurus a good model for studying uterine infection and immunity.

Minimum inhibitory concentrations of some antimicrobial drugs against bacteria causing uterine infections in cattle

The minimum inhibitory concentrations (MICs) of oxytetracycline, cephapirin, cephapirin/mecillinam, cefquinome, ceftiofur and enrofloxacin, candidate antibiotics for the principal bacteria associated with uterine infections: Escherichia coli, Arcanobacterium pyogenes and the anaerobic bacteria Fusobacterium necrophorum and Prevotella melaninogenicus, were determined by the agar dilution method. The bacteria were isolated from animals with clinical metritis and/or endometritis. For E coli, cefquinome and enrofloxacin had the lowest MIC90 and MIC50 values (< 0.06 microg/ml), and oxytetracycline and cephapirin had the highest values. For A pyogenes, oxytetracycline had the highest MIC50 value (16 microg/ml), but all the cephalosporins had values below 0.06 microg/ml. For the anaerobic bacteria, enrofloxacin and oxytetracycline had the highest MIC50 values but all the cephalosporins had values of 0.06 microg/ml or below.

Postpartum uterine health in cattle

Uterine health is often compromised in cattle because postpartum contamination of the uterine lumen by bacteria is ubiquitous, and pathogenic bacteria frequently persist causing clinical disease. The subfertility associated with uterine infection involves perturbation of the hypothalamus, pituitary and ovary, in addition to the direct effects on the uterus, and appears to persist even after clinical resolution of the disease. Absorption of bacterial components from the uterus can prevent the follicular phase LH surge and ovulation. In addition, the first postpartum dominant follicle has a slower growth rate and secretes less estradiol at the end of the growth phase. There are also localised ovarian effects of high uterine bacterial growth density, because fewer first dominant follicles are selected in the ovary ipsilateral than contralateral to the previously gravid uterine horn. Thus, it is important to diagnose and treat uterine disease promptly and effectively. Examination of the contents of the vagina for the presence of pus is the most useful method for diagnosis of endometritis. The character and odor of the vaginal mucus can be scored and this endometritis score is correlated with the growth density of pathogenic bacteria in the uterus, and is prognostic for the likely success of treatment. The challenge for the future is to design prevention and control programs to reduce the incidence of disease, and understand how the immune and endocrine systems are integrated.

Association between postpartum pyrexia and uterine bacterial infection in dairy cattle

The temperature of 90 dairy cattle was recorded for the first 10 days after parturition and the animals were categorised as either normal (< 39.7 degreesC) or pyrexic. Swabs were collected from the uterine lumen seven, 14, 21 and 28 days after parturition for aerobic and anaerobic culture; bacteria were identified and their growth was scored semiquantitatively. Blood samples were collected three times a week for the estimation of the concentrations of acute phase proteins. The cows' temperatures were often above the accepted normal range, but it was not a good indicator of the number of bacteria in the uterus. However, pyrexia was correlated with the presence of specific uterine pathogens (P < 0.05) and in particular with Prevotella species (P < 0.01). The pyrexic animals had a higher plasma concentration of the acute phase protein (alpha1-acid glycoprotein (P < 0.05). Although pyrexia is an indicator of postpartum inflammation, additional clinical signs are necessary to identify uterine bacterial infection.

Effect of intrauterine administration of oestradiol on postpartum uterine bacterial infection in cattle

After parturition fewer first dominant follicles are selected in the ovary ipsilateral to the previously gravid uterine horn in cattle. However, the presence of a large oestradiol-secreting follicle in the ipsilateral ovary is a predictor of fertility, possibly due to a localised effect of oestradiol which increases the rate of elimination of the ubiquitous uterine bacterial contamination that occurs after calving. The present study tested the hypothesis that oestradiol reduces uterine bacterial contamination when administered into the uterine lumen around the expected time for selection of the first postpartum dominant follicle. Animals were infused with saline (n=15) or 10mg oestradiol benzoate (n=15) into the previously gravid uterine horn on Days 7 and 10 postpartum. Peripheral coccygeal blood samples were collected daily and oestradiol concentrations measured by radioimmunoassay (RIA). Uterine lumen swabs were collected 7, 14 and 21 days postpartum for aerobic and anaerobic culture, bacteria were identified and growth scored semi-quantitatively. Plasma oestradiol concentrations were higher for treated animals between Days 7 and 14 (1.4+/-0.1 versus 2.0+/-0.2 pg/ml, P<0.05). Control animals had a similar bacterial growth score on Days 7 and 14, with a lower value on Day 21 (5.7+/-1.0 and 6.1+/-0.7 versus 0.3+/-0.1, P<0.05). However, treated animals had a surprising higher bacterial load on Day 14, than on Days 7 or 21 (7.1+/-0.9 versus 4.0+/-0.6 or 3.6+/-0.6, P<0.05). The increased score was attributable to more pathogens associated with endometritis on Day 14 than Day 7 (5.1+/-1.0 versus 2.5+/-0.5, P<0.05), in particular Prevotella melaninogenicus (1.5+/-0.5 versus 0.7+/-0.2, P<0.05) and Fusobacterium necrophorum (1.5+/-0.4 versus 0.3+/-0.2, P<0.05). In conclusion, administration of oestradiol into the uterine lumen surprisingly increased uterine pathogenic anaerobic bacterial contamination. Thus, it is unlikely that increased fertility associated with a first dominant follicle in the ipsilateral ovary is a consequence of the elimination of bacterial contamination by ovarian oestradiol.

Influence of Griseofulvin treatment on semen quality in the dog

Griseofulvin is used to treat dermatomycosis in many species and causes oligospermia in supra-pharmacological doses. The aim of the present study was to evaluate the effect of Griseofulvin administered at therapeutic doses upon semen quality in dogs. Four dogs were treated with Griseofulvin (25 mg/kg per day) for 30 days. Semen collections and analyses were performed before, during and for 100 days after treatment for the Griseofulvin group and 10 untreated control dogs. Semen analyses included mean percentage of forward progressively motile sperm, total sperm output, normal live sperm and normal dead sperm. There was no significant difference between control and treated dogs for each of the semen quality parameters. Therapeutic dosage of Griseofulvin had no deleterious effect upon semen quality in dogs, although this does not preclude potential embryotoxic and teratogenic effects.

The effect of oestradiol on postpartum uterine involution in sheep

The present study tested the hypothesis that ovarian oestradiol increases the rate of uterine involution after parturition in sheep. The day after parturition, ewes were randomly assigned as un-operated controls (n=5), or a 3 cm silastic implant containing oestradiol (n=8) or empty (n=7) was sutured within the bursa of the ovary ipsilateral to the previously gravid uterine horn. Blood samples were collected daily for measurement of PGFM and acute phase proteins until 17 days postpartum when the ewes were slaughtered and the genital tract was collected. There was no consistent effect of treatment group on uterine involution determined by the collagen density, dry matter content, width, length, or weight of the genital tract. Furthermore, there was no evidence of a localised effect of oestradiol on involution as there were no significant differences between the previously gravid and non-gravid uterine horns. However, oestradiol-treated ewes had lower plasma concentrations of 15-keto-13,14-dihydro-prostaglandin F2alpha (P<0.01), alpha1-acid glycoprotein (P<0.05) and ceruloplasmin (P<0.001); but, not haptoglobin. These observations could reflect a direct effect of oestradiol on inflammatory mediator synthesis or secretion because, in the absence of parallel physical measurements, it is unlikely that these observations reflect a beneficial effect of treatment on uterine health.

Reproductive challenges facing the cattle industry at the beginning of the 21st century

The aim of this review is to pinpoint the areas that require further research for greatest impact to improve the efficiency of dairy and beef production. Increased knowledge about the principal causes of reduced fertility is essential. Increases in milk yield have been at the expense of reduced fertility in dairy cows and although diet has a major impact, the precise interaction between nutrition and reproduction still needs to be characterized in both beef and dairy cows. Furthermore, during periods of inadequate nutrition or stress, the intensity of oestrus is reduced by inadequate exposure to oestradiol. However, it is still unclear which pheromones are involved at oestrus, how synthesis is controlled and how pheromones are detected in herd-mates. GnRH may be involved in behaviour but the brain centres that translate hormonal messages are unknown. Attempts to overcome poor oestrous detection include measurements of milk progesterone, telemetric pressure detectors and devices that record the extra activity at oestrus. Substitution of heat detection by 'hormone treatment remedies' has met strong consumer resistance in Europe. The creation of larger cattle units and increased movements world-wide render herds more susceptible to infectious agents, such as Neospora, Leptospira, Trypanosoma and Bovine Viral Diarrhoea virus (BVDv), but it is unclear how other clinical conditions, such as lameness or endometritis, also interfere with ovarian function. The future of dominant follicles selected within 14 days after parturition is crucial--normal ovulation, prolonged persistence or atresia. Calving carries the greatest risk in the reproductive life of a cow and yet little work has focused on reducing the frequency of this event. For dairy cows, a greater understanding about induced or extended lactation is required. For beef animals, precise induction of twinning and nutritional adjustments could produce two offspring per pregnancy. At the start of pregnancy, the trophoblast produces interferon to prevent luteolysis, but the immunological implications are unknown and it is not clear how the rest of pregnancy is maintained. Profiles of pregnancy specific protein B (PSPB) have increased understanding of embryonic death. However, 25% of cows in abattoirs are pregnant, even though 30% of involuntary cullings are 'for failing to conceive'. Clearly, this is an area of wastage that requires urgent resolution. It is unknown why undernutrition at the time of insemination or in early pregnancy leads to delayed births, low fetal weights and later adverse health. At the end of pregnancy, the fetus controls the onset of parturition, but very little is known about the biochemical control of cervical dilation and placental separation. On the male side, bulls are selected for optimal freezability of semen; however, there is as yet no reliable predictor for semen fertility. Methods for accurately pre-determining the sex of both semen and embryos will revolutionize the dairy and beef industries.

Effect of postpartum manual examination of the vagina on uterine bacterial contamination in cows

Twenty-one days after they had calved, the vaginas of 34 cows were examined with a clean gloved hand, and 26 cows were left unexamined. Swabs were collected from the lumen of the uterine body of the cows on the same day and seven days later; bacteria were identified by aerobic and anaerobic culture, and bacterial growth was scored semi-quantitatively. On the same days, blood samples were collected and the concentrations of acute phase proteins were measured, and the diameters of the cows' uterine horns were measured by transrectal ultrasonography. The vaginal examinations did not result in uterine bacterial contamination or an acute phase protein response, and they did not affect the diameters of the uterine horns.

Influence of uterine bacterial contamination after parturition on ovarian dominant follicle selection and follicle growth and function in cattle

First postpartum dominant follicles are preferentially selected in the ovary contralateral to the previously gravid uterine horn. The aim of the present study was to test the hypothesis that uterine bacterial contamination alters the location of ovarian follicle emergence and selection, and inhibits follicle growth and function. Swabs were collected from the uterine body lumen of cattle on days 7, 14, 21 and 28 after parturition. Bacteria were identified by aerobic and anaerobic culture; bacterial growth was scored semiquantitatively and animals were categorized into standard or high bacterial contamination categories on the basis of the number of colonies detected. Follicular growth and function were monitored by daily transrectal ultrasonography, and estimation of plasma FSH, oestradiol and progesterone concentrations. There was no effect of bacterial contamination on plasma FSH concentration profiles or emergence of the ovarian follicle wave. When uterine bacterial growth scores were high on day 7 or day 21 after parturition, fewer first (1/20 versus 15/50; P < 0.05) or second (1/11 versus 13/32; P < 0.05) dominant follicles were selected in the ipsilateral compared with the contralateral ovary, respectively. The diameter of the first dominant follicle was smaller in animals with a high day 7 bacterial score (P < 0.001), dominant follicle growth was slower (P < 0.05) and oestradiol secretion was decreased (P < 0.05). The present study provides evidence for an effect of the uterus on the ovary after parturition, whereby uterine bacteria have a contemporaneous localized effect on ovarian follicle selection and subsequent growth and function, but not on initial emergence.

Influence of uterine bacterial contamination after parturition on ovarian dominant follicle selection and follicle growth and function in cattle

First postpartum dominant follicles are preferentially selected in the ovary contralateral to the previously gravid uterine horn. The aim of the present study was to test the hypothesis that uterine bacterial contamination alters the location of ovarian follicle emergence and selection, and inhibits follicle growth and function. Swabs were collected from the uterine body lumen of cattle on days 7, 14, 21 and 28 after parturition. Bacteria were identified by aerobic and anaerobic culture; bacterial growth was scored semiquantitatively and animals were categorized into standard or high bacterial contamination categories on the basis of the number of colonies detected. Follicular growth and function were monitored by daily transrectal ultrasonography, and estimation of plasma FSH, oestradiol and progesterone concentrations. There was no effect of bacterial contamination on plasma FSH concentration profiles or emergence of the ovarian follicle wave. When uterine bacterial growth scores were high on day 7 or day 21 after parturition, fewer first (1/20 versus 15/50; P < 0.05) or second (1/11 versus 13/32; P < 0.05) dominant follicles were selected in the ipsilateral compared with the contralateral ovary, respectively. The diameter of the first dominant follicle was smaller in animals with a high day 7 bacterial score (P < 0.001), dominant follicle growth was slower (P < 0.05) and oestradiol secretion was decreased (P < 0.05). The present study provides evidence for an effect of the uterus on the ovary after parturition, whereby uterine bacteria have a contemporaneous localized effect on ovarian follicle selection and subsequent growth and function, but not on initial emergence.

Cryopreservation of epididymal dog sperm

A method of cryopreservation was developed for sperm salvaged from the cauda epididymis and vas deferens of domestic dog testes. Four modifications of the glycerol concentration of a buffer used for cryopreservation of dog ejaculates and two freezing rates were assessed for their effect upon post-thaw spermatozoal motility and morphology. There was no statistical difference between the four glycerol concentrations or the two freezing rates and the buffer containing 6% glycerol and the freezing rate provided by 0.5 ml straws was chosen for further study. This method resulted in a significant reduction in the percentage of live spermatozoa detected with Hoechst staining and a reduction in the percentage of capacitated spermatozoa after freeze-thawing. However, there was no difference in the ability of frozen-thawed spermatozoa to penetrate homologous oocytes. This study demonstrates that cryopreservation of epididymal canine sperm can be performed using methods similar to those established for ejaculates of the same species, and that despite some damage, spermatozoa retain their functional ability.

Acute phase protein responses to uterine bacterial contamination in cattle after calving

Repeated ultrasonographic examinations and collections of blood samples and uterine lumenal swabs between seven and 28 days after calving were used to examine the relative effects of bacterial contamination and involution of the uterus on the concentrations of acute phase proteins in the blood of 26 dairy cows. The severity of bacterial contamination, as determined by the total bacterial growth score, was a significant variable for the concentrations of the acute phase proteins alpha1-acid glycoprotein (P < 0.0001), haptoglobin (P < 0.05) and ceruloplasmin (P < 0.0001). In addition, the concentrations of alpha1-acid glycoprotein and ceruloplasmin were increased in the cows from which Escherichia coli (P < 0.0001) and Arcanobacterium pyogenes (P < 0.05), respectively, were isolated from the uterine lumen. Uterine involution, as determined by the decreasing diameter of the previously gravid uterine horn, was associated with a decrease in the concentrations of alpha1-acid glycoprotein (P < 0.005), haptoglobin (P < 0.05) and ceruloplasmin (P < 0.01). However, the response of the acute phase proteins to bacterial contamination was independent of the day on which the samples were collected, indicating that their concentrations were increased by bacterial contamination in addition to the changes associated with uterine involution.