Expression of genes associated with immunity in the endometrium of cattle with disparate postpartum uterine disease and fertility

Progesterone-independent endometrial mRNA expression in dairy cows with clinical or subclinical endometritis

Up to 50 % of dairy cows fail to resolve uterine involution and develop chronic clinical (CE) or subclinical endometritis (SE) 21 days after calving. Clinical endometritis is associated with purulent discharge, while SE is not associated with overt clinical signs. Along with numerous knowledge gaps related to its pathogenesis, SE does not allow for a straightforward and effective therapy. Therefore, it is crucial to unravel differences in the expression of genes among healthy, CE, and SE cows. This might contribute to the discovery of new drug candidates and, in consequence, a potentially effective treatment. In the present study, cows between 21 and 28 days postpartum (PP) were examined using vaginoscopy for the presence of vaginal discharge and endometrial cytology for the determination of the endometrial polymorphonuclear cell (PMN) percentage. Next, an endometrial biopsy sample was taken to investigate the expression of 13 selected candidate genes by qPCR. Uterine health status was assigned to healthy (absence of abnormal vaginal discharge and ≤5 % PMN, n = 13), SE (absence of abnormal vaginal discharge and >5 % PMN, n = 30), and CE (mucopurulent or purulent vaginal discharge and >5 % PMN, n = 9). At the same time, a blood sample was collected to assess serum progesterone concentration and to categorize cows as low (≤1 ng/mL) or high (>1 ng/mL) in progesterone. High expression of IL1B, IL6, IL17A, CXCL8, PTGES, PTGS1, PTGS2, and INHBA genes and low expression of FST was noted in the endometrium of CE compared to healthy cows. Increased endometrial INHBA expression was observed in both SE and CE compared to healthy cows. Interestingly, greater expression of PTGES and PRXL2B genes and lower expression of PTGS2 were characteristic of SE versus CE or healthy. Among cows with no overt clinical symptoms of uterine disease (healthy and SE), the endometrial expression of IL1 B, CXCL8, and PTGES was greater in cows with high versus low serum progesterone. Several genes were differentially expressed among healthy, SE, and CE cows indicating different pathways for the development of different uterine diseases. In conclusion, we found progesterone-independent SE markers, which suggests that low endometrial PTGS2 expression may be indicative of an inadequate immune response and thus contribute to the pathogenesis of SE.

Targeting inflammation for the treatment of endometritis in bovines

The uterine endometrial surface of bovines is in constant exposureconstantly exposed with to a multitude ofmany microbial populations that changes throughout the post-partum phase in terms of complexity and dynamics. These microbes contribute to the host pathology, leading to severe economic losses along withnd reproductive capabilities. The basic primary interface that occurs between the internal tissues of the body of the hostbetween the host body's internal tissues and the microbes is the endometrial surface of the uterus. As a result of the infinite pathogenic population, there is always a danger for the opportunistic organisms to attack. Therefore, it is paramount that any interactions, especially microbial microbes with the endometrial surface, are regulated by the host cells. However, the inflammatory response as the defense mechanism contributes a pivotal roleis pivotal in host immunity and pathology. The inflammatory cascade and pathways are important essential to eliminate this clinical problem. In this review, we will discuss and explain how the inflammation and the various components of the immune system play their role in host pathology and therapeutic strategies, taking into account the interface between the host and the microbes on the surface of the endometrium. This review is also instrumental in further explanation of inflammatory uterine disease by discussing the response of inflammation to external insult.

Effects of ruminal lipopolysaccharide exposure on primary bovine ruminal epithelial cells

The objective of this study was to investigate the immunopotential of ruminal lipopolysaccharides (LPS) on cultured primary bovine rumen epithelial cells (REC). Primary bovine REC were isolated from 6 yearling steers and grown in culture for 3 experiments. Experiment 1 aimed to determine the immunopotential of ruminal LPS, experiment 2 aimed to assess tolerance to chronic LPS exposure, and experiment 3 aimed to evaluate antagonistic interactions between ruminal and Escherichia coli LPS. In experiments 1 and 2, REC were exposed to nonpyrogenic water, 20 μg/mL E. coli LPS (EC20), 10 μg/mL ruminal LPS, 20 μg/mL ruminal LPS, and 40 μg/mL ruminal LPS, either continuously or intermittently. For the continuous exposure, REC underwent a 6 h exposure, whereas for the intermittent exposure, the procedure was: (1) a 12 h continuous exposure to treatments followed by LPS removal for 24 h and then another 12 h of exposure (RPT), and (2) a 12 h continuous exposure to treatments followed by LPS removal and a recovery period of 36 h (RCV). In experiment 3, REC were exposed to nonpyrogenic water, 1 μg/mL E. coli LPS, 1 μg/mL ruminal LPS to 1 μg/mL E. coli LPS, 10 μg/mL ruminal LPS to 1 μg/mL E. coli LPS, and 50 μg/mL ruminal LPS to 1 μg/mL E. coli LPS. Each experiment was done as a complete randomized block design with 6 REC donors. The REC-donor was used as blocking factor. Each treatment had 2 technical replicates, and treatment responses for all data were analyzed with the MIXED procedure of SAS. For all experiments, total RNA was extracted from REC and real-time quantitative PCR was performed to determine the relative expression of genes for toll-like receptors (TLR2 and TLR4), proinflammatory cytokines (TNF, IL1B, and IL6), chemokines (CXCL2 and CXCL8), growth factor-like cytokines (CSF2 and TGFB1), and a lipid mediator (PTGS2). In experiment 1, the targeted genes were upregulated by EC20, whereas all ruminal LPS treatments resulted in a lower transcript abundance. Regarding RPT, and RCV condition, in experiment 2, the expression of targeted genes was not affected or was at a lower abundance to EC20 when compared with ruminal LPS treatments. Lastly, in experiment 3, all targeted genes resulted in lower or similar transcript abundance on all ruminal LPS ratios. Overall, our results indicate that ruminal LPS have a limited capacity to activate the TLR4/NF-kB pathway and to induce the expression of inflammatory genes.

The role of the oviduct environment in embryo survival

CONTEXT

Declining fertility is an issue in multiple mammalian species. As the site of fertilisation and early embryo development, the oviduct plays a critical role in embryo survival, yet there is a paucity of information on how the oviduct regulates this process.

AIMS

We hypothesised that differences in steroid hormone signalling and/or immune function would be observed in a model of poor embryo survival, the peripubertal ewe.

METHODS

We examined expression of steroid hormones in systemic circulation, oviductal expression of oestrogen receptorαand genes important in steroid hormone signalling, and immune function in pregnant and cyclic peripubertal and adult ewes on day 3 after oestrus.

KEY RESULTS

Concentrations of progesterone, but not oestradiol, were decreased in the peripubertal ewe compared to the adult ewe. Oestrogen receptorαprotein expression was increased in the peripubertal ewe, but pathway analysis of gene expression revealed downregulation of the oestrogen signalling pathway compared to the adult ewe. Differential expression of several genes involved in immune function between the peripubertal and adult ewe was consistent with an unfavourable oviductal environment in the peripubertal ewe lamb. Oestradiol concentration was positively correlated with the expression of multiple genes involved in the regulation of immune function.

CONCLUSIONS

Differences in the immune environment of the oviduct, potentially linked to differential modulation by steroid hormones, may partially underly the poor fertilisation and early embryo survival observed in the peripubertal ewe.

IMPLICATIONS

A unfavourable oviductal environment may play an important role in limiting reproductive success.

Inflammatory responses of bovine endometrial epithelial cells are increased under in vitro heat stress conditions

Cattle exposed to heat stress have reduced fertility, reduced milk production and increased incidence of postpartum uterine infection. Heat stress is suggested to alter immune function of cattle; however, the mechanisms underlying heat stress mediated uterine infection are unknown. We hypothesized that exposure of endometrial cells to heat stress would further increase expression of inflammatory mediators in response to bacterial components due to altered heat-shock protein expression. Bovine endometrial epithelial cells (BEND) were exposed to Escherichia coli lipopolysaccharide (LPS) or a synthetic triacylated lipopeptide (Pam3CSK4) under heat stress (41.0 °C) or thermoneutral (38.5 °C) conditions for 24 h. Exposure of BEND cells to LPS or Pam3CSK4 increased the expression of the proinflammatory mediators IL1B, IL6, and CXCL8 compared to control medium. However, exposure of BEND cells to heat stress increased LPS and Pam3CSK4 induced expression of IL1B compared to cells exposed to thermoneutral conditions, and expression of LPS induced IL6 was also increased when BEND cells were exposed to heat stress. To determine if heat shock proteins increased BEND cell expression of inflammatory mediators, HSP1A1 and HSF1 were targeted by siRNA knock down. Expression of HSP1A1 and HSF1 were reduced following siRNA knockdown; however, knockdown of HSP1A1 or HSF1 further increased heat stress mediated increased expression of inflammatory mediators. These data suggest that heat stress increased BEND cell inflammatory responses to bacterial components, while heat shock proteins HSP1A1 and HSF1 help to restrain inflammatory responses. These mechanisms may contribute to the increased incidence of uterine infection observed in cows under heat stress conditions.

ATP Induces Interleukin-8, Intracellular Calcium Release, and ERK1/2 Phosphorylation in Bovine Endometrial Cells, Partially through P2Y Receptors

The bovine endometrium has an important defensive role in the postpartum period that acts when an inflammatory process associated with tissue damage or infection by bacteria is produced. Endometrial cells release cytokines and chemokines that recruit inflammatory cells, which release danger-associated molecular patterns (DAMPs), such as adenosine triphosphate (ATP), and initiate and regulate the inflammatory response. However, the role of ATP in bovine endometrial cells is unclear. The aim of this study was to determine the effect of ATP on interleukin-8 (IL-8) release, intracellular calcium mobilization, ERK1/2 phosphorylation, and the role of P2Y receptors, in bovine endometrial cells. Bovine endometrial (BEND) cells were incubated with ATP and the IL-8 release was determined by the ELISA assay. ATP of 50 and 100 μM significantly increased IL-8 released in BEND cells (50 μM: 23.16 ± 3.82 pg/mL, p = 0.0018; 100 μM: 30.14 ± 7.43 pg/mL, p = 0.0004). ATP (50 μM) also induced rapid intracellular calcium mobilization in Fura-2AM-loaded BEND cells, as well as ERK1/2 phosphorylation (ratio 1.1 ± 0.04, p = 0.0049). Suramin (50 μM), a pan-antagonist of P2Y receptors, partially reduced the intracellular calcium mobilization, ERK1/2 phosphorylation (ratio 0.83 ± 0.08, p = 0.045), and IL-8 release (9.67 ± 0.02 pg/mL, p = 0.014) induced by ATP. Finally, BEND cells expressed higher mRNA levels of P2Y1 and P2Y2 purinergic subtype receptors, and lower levels of P2Y11 and P2Y12 receptors, as determined by RT-qPCR. In conclusion, these results showed that ATP activates pro-inflammatory responses in BEND cells, which are partially mediated via P2Y receptors, and BEND cells express the mRNA of subtypes of P2Y receptors, which could have a key role in bovine endometrial inflammation.

Reproductive microbiome and cytokine profiles associated with fertility outcomes of postpartum beef cows

Shifts from commensal bacteria (for example, Lactobacillus in the phylum Firmicutes) within the reproductive tract have been associated with changes in local reproductive immune responses and decreased fertility in humans. The objective of this study was to characterize the microbiome and cytokine concentrations before artificial insemination (AI) in vaginal and uterine flushes from postpartum beef cows. Twenty Bos indicus-influenced beef cows (approximately 60 d postpartum and free of reproductive, health, or physical issues) were enrolled. The B. indicus prostaglandin (PG) 5-d + controlled intervaginal drug-releasing estrus synchronization protocol was initiated on day -8 of the study with timed AI on d0. Blood samples were collected on days -3, -1, and 28 via coccygeal venipuncture. Vaginal and uterine flushes were collected on days -3 and -1. Based on days 28 pregnancy status determined by transrectal ultrasonography, cows were identified as either Open (n = 13) or Pregnant (n = 7). Bacterial community analyses were conducted targeting the V4 hypervariable region of the 16S rRNA gene. Cytokine analyses were performed using the RayBiotech Quantibody Bovine Cytokine Array Q1 and MyBioSource ELISA kits per the manufacturer's instructions. Statistical analyses for bacteria relative abundance were conducted using PROC NPAR1WAY and for cytokine concentrations using PROC GLM in SAS 9.4. Uterine concentrations of interferon γ, interleukin (IL)1α, and IL21 were greater in Open than in Pregnant cows (P < 0.05). Regardless of pregnancy status, uterine IL13 increased from days -3 to -1 (9.76 vs. 39.48 ± 9.28 pg/mL, respectively; P < 0.05). Uterine relative abundance of the phylum Firmicutes decreased from days -3 to -1 in Open cows (60.4% ± 0.9% vs. 48.5% ± 3.2%; P = 0.004). In Open cows, the genus Blautia decreased in relative abundance within the uterus from days -3 to -1 (2.1% ± 0.2% vs. 0.9% ± 0.1%; P = 0.002). Uterine relative abundance of the phylum Tenericutes increased from days -3 to -1 in Pregnant cows (1.0% ± 0.1% vs. 7.6% ± 4.1%; P = 0.002). In Pregnant cows, the genus Ureaplasma tended to increase within the uterus from days -3 to -1 (0.08% ± 0.06% vs. 7.3% ± 4.1%; P = 0.054). These findings suggest a distinct difference in the reproductive microbiome and cytokine profiles before AI for resulting Open vs. Pregnant cows.

Is the IL1RA/IL1B Ratio a Suitable Biomarker for Subclinical Endometritis in Dairy Cows?

The adequate expression of cytokines is essential for the prevention and healing of bovine endometrial inflammation. This study investigated the intra-uterine concentration of the proinflammatory cytokine interleukin (IL)1B and its antagonist IL1RA in cows with and without subclinical endometritis (SE). Samples were taken from 37 uteri at the abattoir and 26 uteri in vivo. Uterine secretion samples were classified as showing no signs of SE (SEneg; polymorphonuclear neutrophil granulocyte (PMN) < 5%) or showing signs of SE (SEpos; PMN ≥ 5%). Concentrations and ratios for IL1B and IL1RA were measured using a commercial and a newly established AlphaLISA kit, respectively. In both groups, a higher concentration of IL1B was detected in the SEpos group compared with the SEneg group (abattoir: p = 0.027; in vivo p < 0.001). No significant differences were observed in the concentration of IL1RA (p > 0.05). In uterine secretion samples retrieved in vivo, a lower IL1RA/IL1B ratio was detected in the SEpos group compared with the SEneg group (p = 0.002). The results of this study highlight the important role of IL1B and IL1RA during endometritis and the potential of the IL1RA/IL1B ratio as a possible biomarker for SE.

Cortisol inhibits lipopolysaccharide-induced inflammatory response in bovine endometrial stromal cells via NF-κB and MAPK signaling pathways

Bovine uterine infection is commonly caused by Escherichia coli (E. coli). Elevated concentrations of plasma cortisol have been reported in postpartum cows. However, the direct role of cortisol in the inflammatory response of bovine endometrial stromal cells (BESCs) remains unclear. Therefore, the aim of the study was to explore the regulatory effect of cortisol on lipopolysaccharide (LPS)-induced inflammatory response in BESCs. Both the primary and immortalized BESCs were used in this study. BESCs were treated with cortisol (5, 15, and 30 ng/mL) in the presence of LPS. The mRNA expression of inflammatory cytokines and chemokines was detected using RT-qPCR. Western blot and immunofluorescence were used to analyze the activation of the NF-κB and MAPK signaling pathways. The results revealed that cortisol downregulated the LPS-induced overexpression of interleukin(IL)-1β, IL-6, IL-8, TNF-α, COX-2, iNOS in BESCs. Moreover, cortisol inhibited LPS-induced phosphorylation levels of IκB, p65, ERK1/2, JNK and p38, and p65 nuclear translocation in BESCs. These results indicated that cortisol inhibited LPS-induced inflammatory response in BESCs, which may be mediated by suppressing the NF-κB and MAPK signaling pathways.

Endometrial gene expression in response to lipopolysaccharide between estrous cycle phases and uterine horns in cattle

Uterine bacterial community abundances shift throughout the estrous cycle, potentially altering the immunological environment of the uterus and impacting subsequent fertility. The objective of the current study was to evaluate the immunological impact of lipopolysaccharide (LPS), as a model for potentially pathogenic bacteria, throughout the uterine endometrium between the luteal and follicular phase of the estrous cycle. Bovine uterine tracts were harvested in mid-luteal (n = 7) or follicular (n = 7) phase. Explants were collected from the contralateral and ipsilateral horn relative to the dominant follicle or corpus luteum, then subjected to one of three treatments: uncultured control, cultured control, or cultured with LPS (1 µg/mL). Explants underwent RNA extraction and targeted RNA sequencing for expression analyses of 40 immune response related genes. Sequencing reads were mapped to Bos taurus genome in CLC Genomics Workbench. Resulting total read counts were normalized by housekeeping gene GAPDH and analyzed for overall expression profile by Orthogonal Projections to Latent Structures Discriminant Analysis (OPLS-DA) and Variable Importance in Projection (VIP) analyses in Metaboanalyst. Individual gene expression differences were determined by GLIMMIX procedure in SAS with fixed effects of treatment, estrous phase, uterine horn, and their interaction, with random effect of individual uterus. Expression of 29 genes were affected among treatment groups, with seven genes increased in LPS treatment compared to other groups (P &lt; 0.05). Multiple genes were affected by estrous phase and uterine horn, independent of treatment (P &lt; 0.05). The OPLS-DA analyses indicated overall gene expression differences due to clustering by estrous cycle and treatment (P &lt; 0.001), with no effect of uterine horn (P &gt; 0.10). Similar clustering was observed between luteal and follicular phase explants of controls, but distinct separate clustering between phases with LPS treatment (P = 0.001). According to VIP analyses, mucins were identified as contributing the most to differences observed between phase and treatment. In conclusion, estrous cycle phase resulted in differing overall endometrial gene expression profiles of immune response to LPS treatment. Therefore, altered immunological environment of the uterus in response to bacteria at different estrous cycle stages may lead to differences in reproductive success.

The endometrial transcriptomic response to pregnancy is altered in cows after uterine infection

Pregnancy induces changes in the transcriptome of the bovine endometrium from 15 days after insemination. However, pregnancy is less likely to occur if cows had a postpartum bacterial infection of the uterus, even after the resolution of disease. We hypothesized that uterine bacterial infection alters the endometrial transcriptomic signature of pregnancy after the resolution of disease. To examine the endometrial transcriptomic signature of pregnancy, cows were inseminated 130 days after intrauterine infusion of pathogenic Escherichia coli and Trueperella pyogenes, subsequently endometrium was collected 16 days after insemination for RNA sequencing. We found 171 pregnancy regulated genes in cows 146 days after bacterial infection. When comparing our findings with previous studies that described the endometrial transcriptomic signature of pregnancy in healthy cows, 24 genes were consistently differentially expressed in pregnancy, including MX1, MX2 and STAT1. However, 12 pregnancy regulated genes were found only in the endometrium of healthy cows, including ISG15 and TRANK1. Furthermore, 28 pregnancy regulated genes were found only in the endometrium of cows following bacterial infection and these were associated with altered iNOS, TLR, and IL-7 signaling pathways. Although 94 predicted upstream regulators were conserved amongst the studies, 14 were found only in the endometrium of pregnant healthy cows, and 5 were found only in cows following bacterial infection, including AIRE, NFKBIA, and DUSP1. In conclusion, there were both consistent and discordant features of the endometrial transcriptomic signature of pregnancy 146 days after intrauterine bacterial infusion. These findings imply that there is an essential transcriptomic signature of pregnancy, but that infection induces long-term changes in the endometrium that affect the transcriptomic response to pregnancy.

Lactobacillus rhamnosus GR-1 Alleviates Escherichia coli-Induced Inflammation via NF-κB and MAPKs Signaling in Bovine Endometrial Epithelial Cells

Escherichia coli counts as a major endometritis-causing pathogen among dairy cows, which lowered the economic benefits of dairy farming seriously. Probiotic consumption has been reported to impart beneficial effects on immunomodulation. However, the inflammatory regulation mechanism of probiotics on endometritis in dairy cows remains unexplored. The current work aimed to clarify the mechanism whereby Lactobacillus rhamnosus GR-1 (L. rhamnosus GR-1) resists bovine endometrial epithelial cells (BEECs) inflammatory injury induced by E. coli. The model of cellular inflammatory injury was established in the BEECs, which comes from the uterus of healthy dairy cows using E. coli. The outcome of L. rhamnosus GR-1 addition on inflammation was evaluated in BEECs with E. coli-induced endometritis. The underlying mechanisms of anti-inflammation by L. rhamnosus GR-1 were further explored in E. coli-stimulated BEECs. In accordance with the obtained results, the use L. rhamnosus GR-1 alone could not cause the change of inflammatory factors, while L. rhamnosus GR-1 could significantly alleviate the expression of E. coli-induced inflammatory factors. Based on further study, L. rhamnosus GR-1 significantly hindered the TLR4 and MyD88 expression stimulated by E. coli. Moreover, we observed that in BEECs, L. rhamnosus GR-1 could inhibit the E. coli-elicited expressions of pathway proteins that are associated with NF-κB and MAPKs. Briefly, L. rhamnosus GR-1 can effectively protect against E. coli-induced inflammatory response that may be closely related to the inhibition of TLR4 and MyD88 stimulating NF-κB and MAPKs.

The Antioxidant Role of Selenium via GPx1 and GPx4 in LPS-Induced Oxidative Stress in Bovine Endometrial Cells

This study investigated the antioxidant role of selenium (Se) in the form of selenomethionine (SLM) in LPS-induced oxidative stress via the glutathione peroxidase (GPx) enzymes and the Nrf2/HO-1 transcription factor. The impact of serum supplementation in culture media on GPxs was also studied. The bovine uterus is constantly exposed to exogenous pathogens postpartum, and the endometrium is the first contact against bacteria invasion. Endometritis is an inflammation of the endometrium and is brought about by bacterial lipopolysaccharide capable of inducing oxidative stress. The BEND cells were supplemented at the point of seeding with the following SLM concentrations 0, 100, 500, and 1000 nM for 48 h. BEND cells, cultured with or without SLM (100 nM), were initially incubated for 48 h, and then, we serum starved the SLM group for 24, 48, and 72 h. Similarly, an assay involving serum volume (0, 2, 5, and 10%) supplementation in culture media (v/v) with or without SLM (100 nM) was performed for 48 h. The BEND cells were also seeded into four experimental groups and cultured for an initial 48 h as follows: control, LPS (20 μg/mL), SLM (100 nM), and SLM + LPS groups followed by 6-h LPS treatment. The role of SLM in modulating the expressions of GPx1 and GPx4 and the Nrf2 transcription factor-related genes was assessed using qRT-PCR and Western blot techniques. The results showed serum starvation in the presence of SLM supplementation decreased the expression of GPx1 enzyme but increased GPx4 compared to the control. The addition of SLM to cell culture media in an FBS limiting condition improved the expressions of both GPx1 and GPx4. SLM supplementation promoted GPx enzymes' expressions in a serum-free media (0%) and at 2% FBS in media. However, it did not improve their expressions at 10% FBS in media than the untreated groups. Together, our data show the protective role of Se by regulating the expressions of GPx1 and GPx4 enzymes in BEND cells. It also shows that SLM promoted the expression of Nrf2 transcription factor-related genes at both the mRNA and protein levels in BEND cells during LPS stimulation.

Relationship between Escherichia coli virulence factors, notably kpsMTII, and symptoms of clinical metritis and endometritis in dairy cows

Although Escherichia coli is a commensal bacterium of the bovine vaginal microbiota, it is an important pathogenic bacterium that causes diseases of the reproductive tract and sub-fertility. Recent studies have focused on virulence factors (VFs) of intrauterine E. coli; however, actual endometrial VFs have not been clearly identified. The purpose of this study was to identify the VFs of E. coli associated with clinical metritis and endometritis. Thirty-two strains of E. coli and four mixed Trueperella pyogenes (TP) strains were detected in the uterus of 19 Holstein dairy cows with obvious clinical signs (between 8 and 66 days postpartum). The presence of six E. coli VFs (fimH, fyuA, kpsMTII, hra1, csgA, and astA) was examined by PCR, and clinical signs and reproductive performance (mixed TP, the percentage of polymorphonuclear neutrophils [PMN%], days to uterine involution, etc.) were evaluated. Four VFs (fimH, hra1, csgA, and astA) were detected in all E. coli strains, whereas fyuA and kpsMTII were detected in 94% and 50% of strains, respectively. Cows with E. coli strains harboring kpsMTII exhibited significantly severe clinical scores (vaginal discharge score, PMN%, uterine involution), suggesting that kpsMTII is a key VF for progression of clinical metritis and endometritis. In the present study, we clearly identified six VFs associated with clinical metritis and endometritis. In addition, E. coli strains with kpsMTII probably play a crucial role in the progression of clinical metritis and endometritis.

Peripartal Rumen-Protected L-Carnitine Manipulates the Productive and Blood Metabolic Responses in High-Producing Holstein Dairy Cows

This study aimed to monitor the effect of including rumen-protected L-carnitine (Carneon 20 Rumin-Pro, Kaesler Nutrition GmbH, Cuxhaven, Germany) in the transition diet on the productive and metabolic responses of multiparous high-producing Holstein dairy cows. Thirty-two multiparous cows were allocated in a completely randomized design to receive the same diet plus 60 g fat prill containing 85% palmitic acid (control, n = 16) or 100 g rumen-protected L-carnitine (RLC, n = 16); at 28 days before expected calving until 28 days in milk (DIM). Fat prill was included in the control diet to balance the palmitic acid content of both experimental diets. Milk production over the 28 DIM for the control and RLC groups was 46.5 and 47.7 kg, respectively. Milk fat content tended to increase upon rumen-protected L-carnitine inclusion (p = 0.1). Cows fed rumen-protected L-carnitine had higher fat- and energy-corrected milk compared with the control group. Pre- and post-partum administration of L-carnitine decreased both high- and low-density lipoprotein concentrations in peripheral blood of post-partum cows. The results of this study indicated that the concentration of triglycerides and beta-hydroxybutyrate was not significantly different between the groups, whereas the blood non-esterified fatty acid concentration was markedly decreased in cows supplemented with L-carnitine. Animals in the RLC group had a significant (p < 0.05) lower blood haptoglobin concentration at 7 and 14 DIM than the control. Animals in the RLC group had a lower concentration of blood enzymes than those of the control group. The mRNA abundance of Toll-like receptors 4, cluster of differentiation 14, and myeloid differential protein 2 did not significantly change upon the supplementation of L-carnitine in the transition diet. In summary, the dietary inclusion of RLC improved dairy cow's performance during the early lactation period. Greater production, at least in part, is driven by improved energy utilization efficiency and enhanced metabolic status in animals during the periparturient period.

Cell-Specific Expression Pattern of Toll-Like Receptors and Their Roles in Animal Reproduction

Toll-like receptors (TLRs), a part of the innate immune system, have critical roles in protection against infections and involve in basic pathology and physiology. Secreted molecules from the body or pathogens could be a ligand for induction of the TLR system. There are many immune and non-immune types of cells that express at a least single TLR on their surface or cytoplasm. Those cells may be a player in a defense system or in the physiological regulation mechanisms. Reproductive tract and organs contain different types of cells that have essential functions such as hormone production, providing an environment for embryo/fetus, germ cell production, etc. Although lower parts of reproductive organs are in a relationship with outsider contaminants (bacteria, viruses, etc.), upper parts should be sterile to provide a healthy pregnancy and germ cell production. In those areas, TLRs bear controller or regulator roles. In this chapter, we will provide current information about physiological functions of TLR in the cells of the reproductive organs and tract, and especially about their roles in follicle selection, maturation, follicular atresia, ovulation, corpus luteum (CL) formation and regression, establishment and maintenance of pregnancy, sperm production, maturation, capacitation as well as the relationship between TLR polymorphism and reproduction in domestic animals. We will also discuss pathogen-associated molecular patterns (PAMPs)-induced TLRs that involve in reproductive inflammation/pathology.

MicroRNA Bta-miR-24-3p Suppressed Galectin-9 Expression through TLR4/NF-ĸB Signaling Pathway in LPS-Stimulated Bovine Endometrial Epithelial Cells

Endometritis is a major infectious disease affecting dairy development. MicroRNAs are recognized as critical regulators of the innate immune response. However, the role and mechanism of Bta-miR-24-3p in the development of endometritis are still unclear. This study aimed to investigate the effect of Bta-miR-24-3p on the inflammatory response triggered by lipopolysaccharide (LPS) and to clarify the possible mechanism. LPS-treated bovine endometrial epithelial cells (BEECs) were cultured to investigate the role of Bta-miR-24-3p. The expression levels of Bta-miR-24-3p were downregulated, and galectin-9 (LGALS9) were measured by quantitative real-time polymerase chain reaction. The LPS-induced inflammatory response was assessed by the elevated secretion of inflammatory cytokines measured by using enzyme-linked immunosorbent assay and quantitative real-time polymerase chain reaction. Activation of nuclear factor-κB (NF-κB) and TLR4 pathway was assessed by Western blot. The interaction between Bta-miR-24-3p and LGALS9 was validated by bioinformatics analysis and a luciferase reporter assay. LPS-induction in BEECs with Bta-miR-24-3p was overexpressed leads inhibition of pro-inflammatory cytokines, LGALS9 expression, and TLR4/NF-ĸB pathway deactivation. Knockdown of LGALS9 inhibited the LPS-induced inflammatory response in BEECs. LGALS9 was validated as a target of Bta-miR-24-3p. Cloned overexpression of LGALS9 failed to alter the effect of Bta-miR-24-3p on the inflammatory response in BEECs. Overall, Bta-miR-24-3p attenuated the LPS-induced inflammatory response via targeting LGALS9. The immunotherapeutic stabilisation of Bta-miR-24-3p could give a therapeutic option for endometritis and other disorders commonly associated with endometritis, suggesting a novel avenue for endometritis treatment.

The ABCC4 gene is associated with pyometra in golden retriever dogs

Pyometra is one of the most common diseases in female dogs, presenting as purulent inflammation and bacterial infection of the uterus. On average 20% of intact female dogs are affected before 10 years of age, a proportion that varies greatly between breeds (3–66%). The clear breed predisposition suggests that genetic risk factors are involved in disease development. To identify genetic risk factors associated with the disease, we performed a genome-wide association study (GWAS) in golden retrievers, a breed with increased risk of developing pyometra (risk ratio: 3.3). We applied a mixed model approach comparing 98 cases, and 96 healthy controls and identified an associated locus on chromosome 22 (p = 1.2 × 10^–6, passing Bonferroni corrected significance). This locus contained five significantly associated SNPs positioned within introns of the ATP-binding cassette transporter 4 (ABCC4) gene. This gene encodes a transmembrane transporter that is important for prostaglandin transport. Next generation sequencing and genotyping of cases and controls subsequently identified four missense SNPs within the ABCC4 gene. One missense SNP at chr22:45,893,198 (p.Met787Val) showed complete linkage disequilibrium with the associated GWAS SNPs suggesting a potential role in disease development. Another locus on chromosome 18 overlapping the TESMIN gene, is also potentially implicated in the development of the disease.

Marked up-regulation of anti inflammatory cytokine gene expression in the peripheral blood mononuclear cells of postpartum cows with endometritis

This study was designed to determine the mRNA expression profile of inflammatory and anti-inflammatory cytokines in peripheral blood mononuclear cells (PBMC) of endometritic and non-endometritic cows to find out a possible marker for diagnosis of endometritis. Cows (21) including 12 endometritic, and 9 normal (non-endometritic) that did not develop uterine diseases postpartum (pp) were selected. Expression profile (mRNA) of cytokines, viz. IL-1β, TNFα, IL-8 and IL-4 in endometritic cows relative to non-endometritic was studied in PBMC isolated from the blood of the cows collected within 4 to 5 weeks pp. Fold difference (n-fold) in cytokine gene expression in the PBMC of endometritic cows relative to normal was calculated using relative quantification method (2-ΔΔCt). The relative fold change in gene expression for IL-1 was significantly lower in endometritic animals (0.31) than in cows that did not develop endometritis. Significant up-regulation was noted for the proinflammatory cytokine TNFα (9.53 fold and anti-inflammatory cytokine IL-4 (90.09) in cows suffering from endometritis relative to nonendometritic cows. Up-regulation of chemokine IL-8 gene (6.25 fold; was also observed in endometritic compared to non-endometritic cows. Highest and significant up-regulation of mRNA expression for IL-4 followed by TNFα in PBMC of endometritic cows recorded in the study may indicate the development of endometritis in postpartum cows.

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.

Endometrial Inflammation at the Time of Insemination and Its Effect on Subsequent Fertility of Dairy Cows

Simple Summary

A detailed understanding of cellular and molecular mechanisms in the bovine uterus is crucial to explain and avoid subfertility in dairy cows. Therefore, we examined the effect of inflammation in the bovine uterus in cows with no clinical signs of disease at the time of artificial insemination (AI) on subsequent pregnancy outcome. In a total of 71 healthy dairy cows, uterine cytology samples were collected by cytobrush technique within 10 min after insemination. Endometrial inflammation was investigated at the cellular and mRNA expression levels. All factors with a significant effect on fertility in our study were related to uterine polymorphonuclear neutrophil (PMN) migration, i.e., the first line of uterine defense. Cows with a proportion of ≥1% PMN had a 1.8-fold increased chance of pregnancy within 150 days postpartum compared to cows with fewer PMNs. From our results, we conclude that a certain level of inflammation at the molecular and cellular levels before the stimulus of AI might be favorable for cows’ fertility.

Abstract

Our objective was to investigate the level of endometrial immune response at artificial insemination (AI) and to relate it to subsequent fertility. From 71 healthy cows, endometrial cytobrush samples were taken at the first AI for cytological and mRNA analyses. Total RNA isolated from the cytobrushes was used for reverse transcription qPCR for selected transcripts. Animals were grouped into pregnant (PREG; n = 32) and non-pregnant (non-PREG; n = 39) cows following their first AI. The mRNA abundance of the neutrophil-related factor CEACAM1 and the chemokine CXCL5 was 1.2- (p = 0.03) and 2.0-fold (p = 0.04) greater in PREG than in non-PREG cows, respectively. Animals were further subdivided according to the number of inseminations until pregnancy (PREG1, n = 32; PREG2-3, n = 19) and in repeat breeder cows (RBC, n = 13). CEACAM1 and CXCL8 mRNA expression was 1.7- (p = 0.01) and 2.3-fold (p = 0.03) greater in PREG1 than in RBC, respectively. Cox regression showed that cows with PMN ≥ 1% had a 1.8-fold increased chance of pregnancy within 150 days postpartum compared with cows with fewer PMNs. We conclude that a certain level of inflammation before the stimulus of AI might be beneficial for subsequent fertility.

Uterine infection alters the transcriptome of the bovine reproductive tract three months later

Infection of the postpartum uterus with pathogenic bacteria is associated with infertility months later in dairy cattle. However, it is unclear whether these bacterial infections lead to long-term changes in the reproductive tract that might help explain this infertility. Here we tested the hypothesis that infusion of pathogenic bacteria into the uterus leads to changes in the transcriptome of the reproductive tract 3 months later. We used virgin Holstein heifers to avoid potential confounding effects of periparturient problems, lactation, and negative energy balance. Animals were infused intrauterine with endometrial pathogenic bacteria Escherichia coli and Trueperella pyogenes (n = 4) and compared with control animals (n = 6). Three months after infusion, caruncular and intercaruncular endometrium, isthmus and ampulla of the oviduct, and granulosa cells from ovarian follicles >8 mm diameter were profiled by RNA sequencing. Bacterial infusion altered the transcriptome of all the tissues when compared with control. Most differentially expressed genes were tissue specific, with 109 differentially expressed genes unique to caruncular endometrium, 57 in intercaruncular endometrium, 65 in isthmus, 298 in ampulla, and 83 in granulosa cells. Surprisingly, despite infusing bacteria into the uterus, granulosa cells had more predicted upstream regulators of differentially expressed genes than all the other tissues combined. In conclusion, there were changes in the transcriptome of the endometrium, oviduct and even granulosa cells, 3 months after intrauterine infusion of pathogenic bacteria. These findings imply that long-term changes throughout the reproductive tract could contribute to infertility after bacterial infections of the uterus.

The effects of protein level on cytokines and chemokines in the uterine environment of beef heifers during development

The development of replacement heifers is crucial for breeding success and herd efficiency. Nutritional management can affect not only reproductive development but also the inflammatory status of the uterine environment, which may impact reproductive functions such as pregnancy establishment and development. The study herein evaluated the concentration of cytokines and chemokines in the uterus of heifers supplemented with different levels of protein. Angus heifers (n = 60) were blocked by body weight (BW) and randomly assigned to 1 of 3 treatments based on protein supplementation level: control of 10% crude protein (CON), 20% crude protein (P20), or 40% crude protein (P40). BW, body condition score, and blood samples were taken every 2 wk for 140 d to monitor development. Uterine flushes were performed monthly and concentrations of cytokines (IL-1α, IL-1β, TNF-α, IFN-γ, IL-10, VEGF-α, IL-17A, and IL-36RA) and chemokines (IL-8, MCP-1, MIP-1α, and MIP-1β) were quantified via ELISA multiplex. To test if there were mean differences in cytokines between the treatment groups or over time, PROC GLIMMIX (SAS v 9.4) was utilized. Concentrations of all cytokines and chemokines, except IL-1α, changed throughout heifer development (P < 0.05). Heifers in the P40 treatment group displayed reduced concentrations of MCP-1 (P = 0.007) and tended to have decreased concentrations of IFN-γ (P = 0.06). Cytokine IL-36RA tended (P = 0.06) to be affected by protein level, with the lowest concentrations observed in CON heifers. Most cytokines and chemokines increased following the initial month of supplementation (P < 0.05). The increase in concentrations after 1 mo may indicate an adaptive response in the uterus to diet change. Cytokines and chemokines fluctuated due to physiological changes occurring during development. Further research is needed to determine the influence of nutrition on uterine inflammation and long-term impacts on reproductive function.

Hydroxysafflor Yellow A Inhibits Staphylococcus aureus-Induced Mouse Endometrial Inflammation via TLR2-Mediated NF-kB and MAPK Pathway

The present study is designed to investigate the effect of hydroxysafflor yellow A (HYA) on Staphylococcus aureus (S. aureus)-induced mouse endometrial inflammation and to explore its molecular mechanism. We established a mouse endometritis model by intrauterine injection of S. aureus and intrauterine injection of HYA for treatment. Immunohistochemistry, immunofluorescence, and Western blot were used to detect protein expression in uterine tissue, and qPCR was used to measure mRNA expression. HYA could significantly weak uterine pathological changes caused by S. aureus and reduce MPO activity, CD45, CD3, and ED-1 protein expression in uterine tissues of S. aureus-infected mice. Similarly, HYA also significantly decreased S. aureus induced the increase in TNF-α, IL-1β, and IL-6 in uterine tissue. In vivo, we found that knockdown of TLR2 was very important could significantly reduce S. aureus induced the elevated expression of TNF-α, IL-1β, and IL-6 in mEECs. Importantly, in terine tissues of S. aureus-infected mice, HYA significantly decreased the ratio of p-p65/p65, p-IKBα/IKBα, p-p38/p38, p-Erk/Erk, and p-JNK/JNK expression. HYA displays anti-inflammatory effects on S. aureus mouse endometrial inflammation, and this effect might be related to HYA which could block TLR2-mediated NF-kB and MAPK pathway.

Lipopolysaccharide stimulates bovine endometrium explants through toll‑like receptor 4 signaling and PGE2 synthesis

Bovine endometrium infection with gram-negative bacteria commonly causes uterine diseases. Previous studies indicate that prostaglandin E₂ (PGE₂) is an inflammatory mediator in bacterial endometritis. However, the mechanism underlying lipopolysaccharide (LPS)-induced inflammatory response regulation in bovine endometrial explants remains elusive. In the present study, bovine explants were pre-treated with 15-hydroxyprostaglandin dehydrogenase (15-PGDH) inhibitors before LPS stimulation. PGE₂ secretion, prostaglandin synthetase, pro-inflammatory factor, damage-associated molecular pattern (DAMP), and related signaling pathway factor levels were evaluated. Using 15-PGDH inhibitors pre-treatment, LPS-treated bovine endometrial explants exhibited augmentation of PGE₂ and DAMP expression, and upregulation of various signaling pathway factors. Protein kinase A (PKA), extracellular-signal-regulated kinase, and c-Jun N-terminal kinase phosphorylation and degradation of nuclear transcription factor-κB (NF-κB) inhibitors were induced in the pre-treated endometrial explants. The mechanism underlying LPS-induced PGE₂ accumulation acting as a pro-inflammatory mediator through toll-like receptor 4 signaling in bovine explants could involve the PKA, mitogen-activated protein kinase, and NF-κB pathways.

MicroRNA: Could It Play a Role in Bovine Endometritis?

Endometritis in dairy cows is a major economic problem worldwide; without advances in lifestyle management and drug treatment, it causes high morbidity and death. Micro ribonucleic acid (miRNAs) these days is seen as an important part of gene control networks. It is a class of small nucleotides 20-25, single-stranded RNA molecules. In endometritis, the inflammatory response caused by the gram-negative bacteria Escherichia coli (E. coli) alters the expression of miRNA which can regulate the innate immune system. This manuscript reviews (1) the interaction of miRNAs with the signaling of NF-κB and dysregulation of miRNAs and NF-κB activity in endometritis and (2) the activity of miR-let-7c, miR-148a, and miR-488 in NF-κB activation and their effect on endometritis. Cows with reduced immunity are more vulnerable to transition diseases, such as endometritis. During post-partum, cows undergo stress, metabolic disorders, hormonal imbalance, negative energy balance, and changes in diet. One of the many categories of regulatory molecules, which explain its natural function and pathological impact on NF-κB dysregulation, is important to inform the complexity of the immune system and to develop treatments for endometritis. It shows that miRNAs could have multiple applications in veterinary medicine. Nevertheless, a comprehensive study of is essential which should be aimed at exploring the role of microRNA at physiological level and its effect due to dysfunction and dysregulation.

Prediction of Calving to Conception Interval Length Using Algorithmic Analysis of Endometrial mRNA Expression in Bovine

Simple Summary

Our study aimed to develop the unsupervised clustering model based solely on selected markers to investigate the association between calving conception interval length, subclinical endometritis, and endometrial gene expression. An algorithmic analysis of endometrial gene expression showed a higher predictive ability to identify cows exhibiting excellent fertility than previously used methods, highlighting the correlation between INHBA/INHA and calving–conception interval length.

Abstract

After parturition, the uterus undergoes significant reconstruction, allows the endometrium to create an environment for subsequent embryo development. Here, we used an unsupervised algorithmic approach to select characteristic endometrial mRNA expression patterns of proposed markers and investigate each marker’s role as an individual indicator of reproductive success. Clinically healthy cows at a sixth week postpartum were examined, the percentage of neutrophils (PMNs%) in the cytological smear was calculated, and an endometrial biopsy was taken for qPCR. Based on pregnancy examination, cows were divided into three groups: Pregnant before 100 days postpartum (P100, n = 11), pregnant between 100–200-day (P200, n = 14), and culled (C, n = 10). Animals were also classified based on two PMNs% thresholds > 5% PMNs and > 10% PMNs. The expression of IL1B, IL6, CXCL8, and IL17A was higher in >10%PMNs. The expression of PTGS1 was higher in the P200 compared to P100. Upregulation of inhibin A subunit (INHA) and downregulation of inhibin β A subunit (INHBA) were observed in the P100. INHBA/INHA ratio was the most accurate linear predictor of the calving-to-conception interval. The application of the k-means algorithm allowed the identification of five unique expression patterns. The sensitivity and specificity of predicting allocation to P100 were 81% and 79%. We also documented the low efficiency of genes associated with subclinical endometritis and PMNs% in determining reproductive capability. These results suggested the presence of distinctive expression patterns in 6 weeks postpartum, correlated with cows’ reproductive capacity. Furthermore, we proposed the INHBA/INHA ratio as an indicator of calving-to-conception interval length.

Reproductive Tract Infections in Dairy Cows: Can Probiotics Curb Down the Incidence Rate?

Postpartum uterine diseases are common in dairy cows and are a great concern for the dairy industry as they are associated with various consequences, including lower fertility, lower milk yield, and an overall negative impact on the host health. An infected uterus is a source of bacterial compounds and cytokines that spill into the systemic circulation, spreading inflammation to other organs. In this review article, we discuss a short overview of the anatomy of the reproductive tract of dairy cows and several infectious diseases of the uterus including metritis, endometritis, and pyometra. Additionally, we discuss the microbiome of the reproductive tract in health and during uterine diseases. As well, diagnostic criteria for metritis and endometritis and contributing factors for increased susceptibility to metritis infection are important topics of this review. To better understand how the uterus and reproductive tract respond to bacterial pathogens, a section of this review is dedicated to immunity of the reproductive tract. Both the innate and adaptive immunity systems are also discussed. We conclude the review with a factual discussion about the current treatments of uterine diseases and the new developments in the area of application of probiotics for uterine health. Mechanisms of actions of probiotics are discussed in detail and also some applications to prevent uterine infections in dairy cows are discussed.

MicroRNAome: Potential and Veritable Immunomolecular Therapeutic and Diagnostic Baseline for Lingering Bovine Endometritis

The bovine endometrium is a natural pathogen invasion barrier of the uterine tissues' endometrial epithelial cells that can resist foreign pathogen invasion by controlling the inflammatory immune response. Some pathogens suppress the innate immune system of the endometrium, leading to prolonged systemic inflammatory response through the blood circulation or cellular degradation resulting in bovine endometritis by bacterial endotoxins. The microRNA (miRNA) typically involves gene expression in multicellular organisms in post-transcription regulation by affecting both the stability and the translation of messenger RNA. Accumulated evidence suggests that miRNAs are important regulators of genes in several cellular processes. They are a class of endogenous non-coding RNAs, which play pivotal roles in the inflammatory response of reproductive diseases. Studies confirmed that miRNAs play a key regulatory role in various inflammatory diseases by mediating the molecular mechanism of inflammatory cytokines via signal pathways. It implicates some miRNAs in the occurrence of bovine endometritis, resorting to regulating the activities of some inflammatory cytokines, chemokine, differentially expressed genes, and protein through modulating of specific cellular signal pathways functions. This review dwells on improving the knowledge of the role of miRNAs involvement in inflammatory response as to early diagnosis, control, and prevention of bovine endometritis and consequently enlighten on the molecular improvement of the genes coded by various differentially expressed miRNA through the need to adopt recent genetic technologies and the development of new pharmaceutical preparations.

Analysis of Transcriptomic Changes in Bovine Endometrial Stromal Cells Treated With Lipopolysaccharide

Endometritis adversely affects the ability of cattle to reproduce and significantly reduces milk production. The is mainly composed of epithelial and stromal cells, and they produce the first immune response to invading pathogens. However, most of the epithelial cells are disrupted, and stromal cells are exposed to an inflammatory environment when endometritis occurs, especially postpartum. Many bacteria and toxins start attacking stromal cell due to loss of epithelium, which stimulates Toll-like receptor (TLRs) on stromal cells and causes upregulated expression of cytokines. Understanding the genome-wide characterization of bovine endometritis will be beneficial for prevention and treatment of endometritis. In this study, whole-transcriptomic gene changes in bovine endometrial stromal cells (BESCs) treated with LPS were compared with those treated with PBS (control group) and were analyzed by RNA sequencing. Compared with the control group, a total of 366 differentially expressed genes (DEGs) were identified in the LPS-induced group (234 upregulated and 132 downregulated genes), with an adjusted P < 0.05 by DESeq. Gene Ontology (GO) enrichment analysis revealed that DEGs were most enriched in interleukin-1 receptor binding, regulation of cell activation, and lymphocyte-activated interleukin-12 production. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed DEGs were most enriched in the TNF signaling pathway, Toll-like receptor signaling pathway, cytokine-cytokine receptor interaction, NF-κB signaling pathway, and chemokine signaling pathway. The results of this study unraveled BESCs affected with LPS transcriptome profile alterations, which may have a significant effect on treatment inflammation by comprehending molecular mechanisms and authenticating unique genes related to endometritis.

Peripartum changes in the activity and expression of neutrophils may predispose to the postpartum occurrence of metritis in dairy cows

Metritis is a postpartum uterine pathology that causes a huge economic loss due to increased culling risk and impaired milk yield and reproduction in cows. The present study was carried out to study the changes in the activity and expression of blood neutrophils in crossbred dairy cows with and without metritis. Collection of blood samples was done at -3, -2 and - 1 weeks before calving, at calving and during the first day of metritis diagnosis in metritis group (n = 8) or at day 8-10 post calving in healthy group (n = 8). Neutrophils were studied for its percentage (microscopically), respiratory burst (nitro blue tetrazolium assay), myeloperoxidase (MPO) concentrations (sandwich ELISA) and expression of CXCR1, CXCR2, TLR2, TLR4, GRα, CD11b, CD14, CD25, CD44, CD47 and CD62L (RT-PCR). Immunocytochemistry was used to investigate MPO concentration and CD14 activity, and western blotting was used for estimating MPO. Although most of these parameters changed in the cows that developed metritis one week before calving, MPO and CD14 got altered much earlier. Myeloperoxidase concentrations and expression of CD14 were considerably lower starting from -2 weeks before calving in cows that developed metritis compared to healthy cows. Further studies are warranted to study the possible use of MPO and CD14 to identify transition cows more vulnerable to develop metritis several weeks before disease occurrence.

Qualitative and quantitative differences in endometrial inflammatory gene expression precede the development of bovine uterine disease

The transcriptome of the endometrium early postpartum was profiled to determine if inflammatory gene expression was elevated in cows which subsequently developed uterine disease. Endometrial cytobrush samples were collected at 7 days postpartum (DPP) from 112 Holstein–Friesian dairy cows, from which 27 were retrospectively chosen for RNA-seq on the basis of disease classification [ten healthy and an additional 17 diagnosed with cytological endometritis (CYTO), or purulent vaginal discharge (PVD)] at 21 DPP. 297 genes were significantly differentially expressed between cows that remained healthy versus those that subsequently developed PVD, including IL1A and IL1B (adjusted p < 0.05). In contrast, only 3 genes were significantly differentially expressed in cows which subsequently developed CYTO. Accounting for the early physiological inflammatory status present in cows which do not develop disease enhanced the detection of differentially expressed genes associated with CYTO and further expression profiling in 51 additional cows showed upregulation of multiple immune genes, including IL1A, IL1B and TNFA. Despite the expected heterogeneity associated with natural infection, enhanced activation of the inflammatory response is likely a key contributory feature of both PVD and CYTO development. Prognostic biomarkers of uterine disease would be particularly valuable for seasonal-based dairy systems where any delay to conception undermines sustainability.

Leukocyte populations in peripheral blood of dromedary camels with clinical endometritis

Endometritis represents the main cause of reproductive failure in dromedary camels. In dromedary camels, associations between endometritis-causing pathogen-species, disease severity, and systemic changes in the immune system have not been evaluated. In the current study, there was use of flow cytometry and immunofluorescence of membrane proteins for the evaluation of leukocyte subsets and the cellular phenotype in blood of camels with clinical endometritis and evaluations of associations with disease severity and endometritis-causing pathogens. Animals with endometritis had markedly larger numbers of total leukocytes and neutrophils. Although total lymphocyte and monocyte counts did not differ between camels with and without clinical endometritis, there were lesser numbers of total and effector CD4-positive T cells in camels with endometritis. Among monocytes, number of camel inflammatory monocytes (Mo-II) was markedly greater, whereas Mo-III numbers were less in the blood of camels with clinical endometritis. Number of inflammatory monocytes was also indicative of endometritis severity grade. Among camels with clinical endometritis, E. coli- and S. aureus-infected animals had similar endometritis grades and comparable phenotype and composition patterns of leukocytes. Neutrophils and monocytes of camels with clinical endometritis had fewer cell adhesion molecules (i.e., CD11a and CD18). Collectively, the results from the current study allowed for identification of associations between endometritis severity grade and larger numbers of inflammatory monocytes. The results also indicate there is no association between endometritis pathogen-species and changes in phenotype or composition of blood leukocytes.

Differential expression of TGF-β and IL-1R2 genes during endometritis infection in Egyptian buffalo

Contamination of the uterine lumen with bacteria occurred in bovid within the first week after parturition. The bacterial infection causes the persistent inflammation in the endometrium leading to the infertility and huge economical loss in animal production. TGF-β and IL-1R2 genes are involved in innate immune recognition of pathogens and the inflammatory response. This study aimed to compare the expression of these two genes in uteri samples of endometritis-infected and apparently healthy buffaloes using QT-PCR. The uteri samples were collected from endometritis-infected and normal buffaloes. Bacterial examination of uteri from endometritis-infected buffaloes showed the presence of bacterial contamination with E. coli, P. Klebsiella pneumonia and/or P. vulgaris. RNA was extracted from uteri of infected and normal animal, and cDNA was synthesized for QT-PCR. Using GAPDH as a housekeeping gene, the gene expression of two tested genes was assessed and the results showed that the expression of TGF-β and IL-1R2 genes was up-regulated in infected animals compared to control by 11.39 and 12.99 folds, respectively and this increase of gene expressions was highly significant. In conclusion, the gene expression assessment of important innate immune genes—like TGF-β and IL-1R2 genes can help to establish new approaches for the improvement of the immune response of buffalo through marker-assisted selection of animals characterized by superior innate immunity system.

Gene expression in bovine endometrial cells and blood-derived neutrophils stimulated by uterine secretions

Uterine epithelial cells (UEC) and migrated polymorphonuclear cells (PMN) play important roles in the uterine defence against microbial infection. The aims of the present study were to investigate i) whether undiluted uterine secretions modulate the expression of genes associated with the innate immune response in UEC and PMN in vitro, ii) whether these changes differ between the two cell populations and iii) whether uterine secretions from cows with subclinical endometritis produce a different response to those from unaffected cows. Therefore, undiluted uterine secretions, cytobrush and biopsy samples were collected from bovine uteri at a local abattoir. All cows had calved at least 3 months prior to sample collection. Subclinical endometritis was diagnosed by cytology (≥5% polymorphonuclear neutrophils) and histology. The uteri were thereby retrospectively categorised as endometritis-positive (E-pos; n = 14), if either the cytology or the histology results were positive, or endometritis-negative (E-neg; n = 17), if both diagnostics were negative. Cultured UEC responded to secretions from E-pos and E-neg cows with an increased gene expression of CXC ligand (CXCL) 8 and interleukin (IL) 6 compared to incubation with control medium alone. PMN expressed significantly higher mRNA levels of CXCL5, CXCL8 and IL1B in response to supernatant from UEC incubated with secretions from both groups (E-pos and E-neg) compared to those incubated with control medium alone. Gene expression of IL10 in uterine epithelial cells remained comparable to the control in cells exposed to E-pos secretions and was 3.6 times lower in those exposed to E-neg secretions. These results demonstrate that the expression of genes associated with the innate immune response in UEC and indirectly also PMN is affected by uterine secretions in vitro. Depending on the target gene, these changes differ between the two cell populations. UEC exposed to uterine secretions from cows without subclinical endometritis produce lower levels of IL10 compared to those exposed to secretions from affected cows or control medium alone. Therefore, the model established in this study can be used as a valuable tool to further understand the contributions of the two cell populations to the coordinated immune response in the uterus.

[Bovine uterine diseases: Aspects of microbiology, molecular biology, and immunology]

Postpartum uterine diseases, such as puerperal metritis and clinical endometritis may affect over 40 % of cows in dairy farms. Regardless of their severity, these diseases are one of the main reasons for impaired fertility, causing declines in dairy cow productivity and hence, resulting in economic losses. Although uterine diseases have been the topic of scientific discussion for many years, until now it was not possible to agree on uniform definitions for the different kinds of manifestation. By including technical innovations and testing procedures, enormous scientific progress and a deeper knowledge of the physiology as well as the pathologic mechanisms have been achieved. Bovine metritis and endometritis may be regarded as multifactorial diseases caused by a combination of microbial infection, the dysregulation of the immune system, and additional risk factors. These interactions have been analyzed on microbial and molecular biological levels as well as by the use of bioinformatics and molecular genetics. As a result, new species of bacteria and inflammatory mediators possibly contributing to the development of uterine diseases have recently been described. Additionally, metabolic and genetic risk factors and their roles in leading to fertility impairment have been evaluated. In conclusion, it was possible to identify new approaches for possible therapeutic and preventive methods, a subset of which may already be implemented into daily practical routine. This article provides an overview of recent scientific results concerning bovine metritis and endometritis with a focus on microbial, microbiological and immunological studies.

Persistent effects on bovine granulosa cell transcriptome after resolution of uterine disease

Metritis is associated with reduced fertility in dairy cows, but the mechanisms are unclear because the disease resolves several weeks before insemination. One hypothesis is that metritis causes persistent changes in granulosa cells during follicle development, which might be evident in the transcriptome of granulosa cells from dominant follicles weeks after parturition. To test this hypothesis, we collected the follicular fluid and granulosa cells from dominant follicles 63 days post partum from cows previously diagnosed with metritis, at least 6 weeks after resolution of the disease and from cows not diagnosed with metritis (control cows). Bacterial lipopolysaccharide was detected in follicular fluid, and concentrations were associated with follicular fluid IL-8 and glucose concentrations. Transcriptome analysis using RNAseq revealed 177 differentially expressed genes in granulosa cells collected from cows that had metritis compared with control cows. The most upregulated genes were ITLN1, NCF2, CLRN3, FSIP2 and ANKRD17, and the most downregulated genes were ACSM1, NR4A2, GHITM, CBARP and NR1I3. Pathway analysis indicated that the differentially expressed genes were involved with immune function, cell-cell communication, cell cycle and cellular metabolism. Predicted upstream regulators of the differentially expressed genes included NFκB, IL-21 and lipopolysaccharide, which are associated with infection and immunity. Our data provide evidence for a persistent effect of metritis on the transcriptome of granulosa cells in ovarian follicles after the resolution of disease.

Characterization of native Escherichia coli populations from bovine vagina of healthy heifers and cows with postpartum uterine disease

Even though Escherichia coli are common bacteria of the bovine vaginal microbiota, they represent an important pathogen that causes diseases in the reproductive tract and subfertility. However, the actual endometrial virulence profile of E. coli is poorly understood. The present study aims to characterize the phylogenetic structure and virulence potential of native vaginal populations of E. coli from healthy heifers (H), and cows with postpartum uterine diseases (PUD), such as metritis/endometritis (MT) or repeat breeder cows (RB). To this end, the virulence repertoire of 97 E. coli isolates was genotypically and phenotypically assessed. Most of them were assigned to phylogenetic group A (74%), followed by B1 (17%) and D (9%); RB strains were significantly (p < 0.05) more represented by B1. Seven of the 15 evaluated virulence genes (VFG) were detected and the most prevalent were fimH (87%), agn43 (41%) and csgA (35%); while traT (27%), fyuA (11%), hlyA (5%) and kpsMT II (5%) were observed in a lower proportion. Particularly, fyuA was significantly higher (p < 0.05) in MT cows whereas csgA showed the same behavior in PUD animals (p < 0.05). When comparing H and PUD strains, these last ones were associated to positive expression of biofilm, fimbriae curli/cellulose and motility; yet RB strains did not show motility. Vaginal B1 E. coli populations, that possess VFG (fyuA and csgA) as well as the expression of motility, curli fimbriae/cellulose and biofilm, may represent risk factors for endometrial disorders; specifically, those that also, have kpsMT II may have a pathogenic potential for causing the RB syndrome. Future research focusing on the detection of these strains in the vaginal microbiota of cows with postpartum uterine diseases should be done since the control of their presence in vagina could reduce the risk that they access the uterus during the postpartum period.

Clostridium tyrobutyricum alleviates Staphylococcus aureus-induced endometritis in mice by inhibiting endometrial barrier disruption and inflammatory response

Endometritis is an inflammatory disease of the uterus caused by bacterial infection, and it affects both human and animal health. This study aims to investigate the protective effects and molecular mechanisms of probiotics such as Clostridium tyrobutyricum (C. tyrobutyricum) on Staphylococcus aureus (S. aureus)-induced endometritis. The results showed that S. aureus infection significantly induced the pathological damage of the uterus, increased the production of pro-inflammatory cytokines, such as TNF-α and IL-1β, and attenuated the expression of tight junction proteins of uterine tissues. However, C. tyrobutyricum pretreatment obviously reduced the inflammatory response and reversed the changes of tight junction proteins of the uterus induced by S. aureus. Together, the data showed that C. tyrobutyricum also inhibited the expression of the TLR2/NF-κB signaling pathway and HDAC induced by S. aureus. In addition, the treatment of mice with live C. tyrobutyricum, spent culture supernatants (SCS) from C. tyrobutyricum, rather than inactive C. tyrobutyricum, inhibited the inflammatory response induced by S. aureus. Through further research, we found that the levels of butyrate in both blood and uterine tissues of mice treated with C. tyrobutyricum were significantly increased. These findings underscore the protective effect of C. tyrobutyricum on endometritis by enhancing the uterus barrier integrity and inhibiting the inflammatory response. The anti-inflammatory mechanism may occur through the regulation of the expression of TLR2/NF-κB and HDAC, and C. tyrobutyricum can be a potentially therapeutic candidate for the treatment of endometritis.

PGE2 increases inflammatory damage in Escherichia coli-infected bovine endometrial tissue in vitro via the EP4-PKA signaling pathway

Endometritis is the most common bovine uterine disease following parturition. The role of prostaglandin E2 (PGE2) in the regulation of endometrial inflammation and repair is well understood. Excess PGE2 is also generated in multiple inflammatory diseases, including endometritis. However, it remains unclear whether PGE2 is associated with pathogen-induced inflammatory damage to the endometrium. To clarify the role of PGE2 in pathogen-induced inflammatory damage, this study evaluated the production of PGE2, inflammatory factors, and damage-associated molecular patterns (DAMPs) in cultured Escherichia coli-infected bovine endometrial tissue. PGE2 production was significantly higher in E. coli-infected tissue, and in E. coli-infected tissue treated with 15-prostaglandin dehydrogenase (15-PGDH) inhibitors, as compared to uninfected tissue. Phospholipase A2 (PLA2), cyclooxygenase-2 (COX-2), and microsomal prostaglandin E synthase-1 (mPGES-1) were also upregulated in E. coli-infected tissue, while concentrations of arachidonic acid (AA), leukotrienes, DAMPs, and other proinflammatory factors increased. The accumulation of PGE2 clearly damaged the cultured tissue. Treatment with the COX-2, mPGES-1, EP4, and protein kinase A (PKA) inhibitors decreased the production of PGE2, inflammatory factors, and DAMPs, simultaneously alleviating the E. coli-induced endometrial tissue damage. Therefore, the PGE2 that was generated by COX-2 and mPGES-1 accumulated, and this pathogenic PGE2 increased inflammatory damage by upregulating inflammatory factors and DAMPs in E. coli-infected bovine endometrial tissue. This upregulation of inflammatory factors and DAMPs might be regulated by the EP4-PKA signaling pathway.

Inflammatory response in repeat breeder buffaloes

The aim of this study was to investigate the repeat breeding condition in Italian Mediterranean buffaloes that failed to conceive after at least 300 days in milk. The trial was carried out on 40 pluriparous Italian Mediterranean buffaloes with more than 300 days in milk. All the animals underwent ultrasound examination to assess endometrial thickness and oestrus synchronization by the Ovsynch-TAI Program. On the day of oestrus, blood samples were collected for the haemocytometric cell count and biochemical assay, and the animals were slaughtered in a local abattoir. A post-mortem uterine flushing was performed using sterile saline for microbiological analyses. Furthermore, uterine biopsies were carried out for histopathological assessment. Finally, endometrial samples were used for real-time PCR (RT-PCR) analysis to evaluate the expression of genes involved in innate immune recognition of pathogens and the inflammatory response, such as Toll-like receptor (TLR)1, TLR8, interleukin (IL)-1β, IL-6, IL-8, COL4A2, connective tissue growth factor (CTGF), and cysteine-rich angiogenic inducer 61 (CYR61). Statistical analysis was performed by one-way ANOVA. Based on the infiltration of lymphocytes and plasma cells or endometrial gland, lymphatic, and blood vessel ectasia recorded in the histopathological examination, the animals were classified into three groups: healthy (H Group; n = 5), moderate endometritis (M Group; n = 25), and severe endometritis (S Group; n = 10). A significantly greater (P < 0.01) endometrial thickness was recorded in the S Group compared to that in the H and M Group (1.07 ± 0.03 vs. 0.70 ± 0.07 and 0.81 ± 0.04 cm in the S, H, and M Group, respectively). The white blood cell count was lower in the H Group compared to that in the M and S Group (6.3 ± 0.6 vs. 9.3 ± 0.4 and 10.5 ± 0.5 in the H, M, and S Group, respectively). To perform RT-PCR analysis, five animals from groups M and S were randomly selected in order to have balanced results. A higher (P < 0.01) expression of TLR1, together with a lower expression of COL4A2, IL-1β, IL-6, IL-8, and CYR61, was recorded in the H Group, compared to both the M and S Groups. In conclusion, about 90% of repeat breeder buffaloes show moderate or severe endometritis, associated with an altered histopathological endometrial profile and altered mRNA expression of pro-inflammatory and fibrotic factors.

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.

Blood metabolic profile tests at dairy cattle farms as useful tools for animal health management

Blood metabolic profile tests are simple cost-effective biochemical tests which are mostly used to identi-fy nutritional and/or management challenges in dairy cattle herds, but they also can be simply used to find animals which are clinically healthy, but really have some hidden problems like low production performance, reproductive diseases and/or long calving intervals and other sub-clinical diseases. Rou-tine metabolic profile tests commonly consist of blood glucose, urea, albumin, cholesterol, beta-hydroxybutyric acid and non-esterified fatty acids values, as well as sodium, potassium, chloride, calci-um, magnesium and inorganic phosphate levels. Briefly, the current review discusses blood metabolic profile tests, their importance, introduces an easy method for it, emphasises on the relation between blood metabolic profile parameters and many important sub-clinical diseases including ketosis, milk fever, mastitis, cystic ovaries, displaced abomasum and etc., and indicates that because of its simplicity, low cost and easy for analysis results, it can be considered as a good method for diagnosis of important diseases at dairy cattle farms.

Changes in peripheral blood mononuclear cells' mRNA expression of TLRs and CD14 during puerperal metritis in dairy cattle

BACKGROUND

Peripheral blood mononuclear cells (PBMCs), commonly referred to as lymphocytes and monocytes, representing cells of the innate and adaptive immune systems.

AIMS

To find out whether changes in PBMCs' mRNA expression of pattern recognition receptors (PRRs) are associated with puerperal metritis in Holstein cows.

METHODS‏

Peripheral blood mononuclear cells were collected from 20 cows with puerperal metritis and 20 cows without metritis at 10 days postpartum. Expression of toll-like receptors 2 and 4 (TLR2 and TLR4), and cluster of differentiation 14 (CD14) genes were assessed in PBMCs using a quantitative real time-polymerase chain reaction (qRT-PCR) technique. The data was normalized to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as a reference gene, and 2^-∆∆Ct methodology was used for relative quantification.

RESULTS

The results of the present study demonstrated that the expression of TLR4 (P=0.04) and CD14 (P=0.008) was significantly greater in cows with puerperal metritis compared to the control group. However, the expression of TLR2 (P=0.06) was not significantly different between cows with puerperal metritis and healthy cows.

CONCLUSION

This study suggests that puerperal metritis significantly increases the expression of TLR4 and CD14 genes in the PBMCs which contributes to the proper stimulation of inflammation and uterine clearance of bacteria soon after calving.

Characterization of metabolic and inflammatory profiles of transition dairy cows fed an energy-restricted diet

Periparturient diseases of dairy cows are caused by disproportionate energy metabolism, mineral imbalance, and perturbed immune function. The aim of the present study was to characterize metabolism, innate immune endometrial gene expression, and uterine microbial populations of transition animals receiving normal or restricted energy diets. Pregnant multiparous Holstein cows (n = 14) were randomly assigned to one of the two dietary treatments from 20 d prepartum until 35 d postpartum (DPP). One group was fed a diet providing 100% energy requirements (NE), whereas the other received an energy-restricted diet providing 80% energy requirements (RE). Feed intake, milk yield, body weight, body condition score, temperature, respiratory, and pulse rate were recorded. After calving, blood was collected weekly to analyze nonesterified fatty acids (NEFAs), β-hydroxybutyrate (BHB), and total cholesterol (TC). Endometrial cytobrushes were collected for gene expression analysis of inflammatory markers, microbial populations determination, and cytological evaluation. The restricted energy diet did not alter feed intake or milk yield but changed energy balance and metabolites levels (P < 0.05). In fact, RE animals had high NEFA and BHB levels, and low TC concentrations (P < 0.05). Moreover, RE animals had upregulated gene expression of serum amyloid A3 (SAA3) at 35 DPP (P < 0.05) and CXC chemokine receptor 2 (CXCR2) at 14 DPP (P < 0.01). Interleukin (IL) 1 and IL8 genes were downregulated 14 DPP but upregulated 35 DPP in RE animals, whereas IL6 and lipopolysaccharide-binding protein (LBP) genes were upregulated at 14 DPP (P ≤ 0.05). The most abundant phyla in RE animals (n = 3) were Bacteroidetes and Fusobacteria, whereas Proteobacteria was the least abundant at both 14 and 35 DPP. In conclusion, it can be speculated that energy balance is one of the main drivers for uterine inflammation by affecting metabolism, immune function, and uterine microbiota. However, these findings should be validated in a larger sample size.

miR-148a suppresses inflammation in lipopolysaccharide-induced endometritis

Endometritis is a postnatal reproductive disorder disease, which leads to great economic losses for the modern dairy industry. Emerging evidence indicates that microRNAs (miRNAs) play a pivotal role in a variety of diseases and have been identified as critical regulators of the innate immune response. Recent miRNome profile analysis revealed an altered expression level of miR‐148a in cows with endometritis. Therefore, the present study aims to investigate the regulatory role of miR‐148a in the innate immune response involved in endometritis and estimate its potential therapeutic value. Here, we found that miR‐148a expression in lipopolysaccharide (LPS)‐stimulated endometrial epithelial cells was significantly decreased. Our results also showed that overexpression of miR‐148a using agomiR markedly reduced the production of pro‐inflammatory cytokines, such as IL‐1β and TNF‐α. Moreover, overexpression of miR‐148a also suppressed NF‐κB p65 activation by targeting the TLR4‐mediated pathway. Subsequently, we further verified that miR‐148a repressed TLR4 expression by binding to the 3′‐UTR of TLR4 mRNA. Additionally, an experimental mouse endometritis model was employed to evaluate the therapeutic value of miR‐148a. In vivo studies suggested that up‐regulation of miR‐148a alleviated the inflammatory conditions in the uterus as evidenced by H&E staining, qPCR and Western blot assays, while inhibition of miR‐148a had inverse effects. Collectively, pharmacologic stabilization of miR‐148a represents a novel therapy for endometritis and other inflammation‐related diseases.

EP2/4 Receptors Promote the Synthesis of PGE2 Increasing Tissue Damage in Bovine Endometrial Explants Induced by Escherichia coli

The bovine uterine is easily contaminated with bacteria during coitus or parturition. A previous study suggested that prostaglandin E₂ (PGE₂) promoted Escherichia coli-infected bovine endometrial tissue inflammatory damage via cyclooxygenase-2 (COX-2) and microsomal prostaglandin E synthase-1 (mPGES-1). However, it remains unclear which PGE₂ receptors regulate the proinflammatory effect of PGE₂ In this study, we evaluated the effect of PGE₂ and its mediated receptors on E. coli-infected endometrium explants isolated from the bovine uterus. The E. coli-infected bovine endometrial explants were cultured in vitro, and the study used EP2/4 receptor agonists to investigate the responses of COX-2, mPGES-1, PGE₂, proinflammatory factors, and damage-associated molecular patterns (DAMPs). The expression of COX-2, mPGES-1, PGE₂, proinflammatory factors, and DAMPs was significantly increased after infection with E. coli; however, the high expression levels caused by E. coli were reduced following treatment with COX-2 and mPGES-1 inhibitors. In addition, the expression levels of COX-2, mPGES-1, PGE₂, proinflammatory factors, and DAMPs were higher in treatment with EP2/4 receptor agonists in E. coli-infected endometrium explants, and their promotable effects were effectively blocked by EP2/4 receptor antagonists. These findings provide evidence that PGE₂ may promote the progress of inflammation in endometrial explants infected with E. coli in bovines. Furthermore, EP2/4 may be involved in a positive feedback loop for COX-2 and mPGES-1 expression, and this may be responsible for the proinflammatory reaction of PGE₂ in E. coli-infected uteri of bovines. SIGNIFICANCE STATEMENT: PGE₂ promoted E. coli-infected bovine endometrial tissue damage via COX-2 and mPGES-1. However, this proinflammatory effect of PGE₂ depends on which receptors are affected by PGE₂, and this remains unclear. In this study, it was investigated that EP2 and EP4 may be involved in a positive feedback loop for COX-2 and mPGES-1 expression, and this may be responsible for the proinflammatory reaction of PGE₂ in E. coli-infected uteri of bovines.