Expression pattern of inflammatory response genes and their regulatory micrornas in bovine oviductal cells in response to lipopolysaccharide: implication for early embryonic development

LPS-Induced Mitochondrial Dysfunction Reduces Oocyte Maturation and Developmental Competence of Buffalo Embryos via ROS Mediated TLR4 Signalling

PROBLEM

Lipopolysaccharide (LPS) from gram-negative bacteria has reportedly been associated with infectious diseases like metritis, which has a substantial adverse effect on animal reproductive performance and causes serious financial losses for the dairy sector. The current work aimed to establish the impact of LPS on in vitro oocyte maturation and subsequent in vitro developmental competence of oocytes, as well as to investigate the explanatory molecular mechanism underlying this effect.

METHOD OF STUDY

Buffalo cumulus-oocyte complexes (COCs) were challenged with 0, 5, 10 and 20 µg/mL LPS during IVM followed by IVF and IVC. Cytoplasmic and nuclear maturation, cleavage and blastocyst rate, intracellular reactive oxygen species (ROS), mitochondrial membrane potential (MMP, ΔΨm) and transcript abundance of genes related to inflammation, antioxidation and apoptosis were evaluated.

RESULTS

The maturation and subsequent embryonic development competency were found to be significantly (p ≤ 0.05) reduced with the addition of 10 and 20 µg/mL LPS to IVM media. ROS production accompanied by a decreased ΔΨm was recorded in LPS-treated oocytes in comparison to the control group (p ≤ 0.05). Our results were further supported by the transcriptional expression of proinflammatory (TLR4, CD14 and RPS27A) and apoptotic gene (Caspase 3) which were found to be significantly increased while antioxidant genes (SOD2 and GPX1) were decreased significantly in matured oocytes and blastocyst after LPS exposure.

CONCLUSIONS

The deleterious effects of LPS are mediated through ROS generation, which triggers inflammatory processes via the TLR4 pathway and impairs oocyte maturation and subsequent embryonic development.

MicroRNAs in equine Endometritis: A review of pathophysiology and molecular insights for diagnostic and therapeutic strategies

Endometritis plays an important role in mare infertility. Certain infectious agents interfere with the innate immune system of endometrium, causing a systemic inflammatory response that lasts for a long time and circulates via the blood or cellular degeneration, leading to endometritis due to bacterial endotoxins. Different small, non-coding RNA molecules are involved in many biological functions. For instance, microRNAs (miRNAs) are involved in the post-transcriptional regulation of gene expression. These miRNAs are important regulators of gene expression, primarily via inhibiting transcription and translation processes. This manuscript reviews: (1) pathomorphological findings in equine endometritis, (2) the expression and effects of eca-miR-17, eca-miR-223, eca-miR-200a, eca-miR-155, and eca-miR-205 in endometritis and (3) the therapeutic role of miRNA in equine endometritis. The miRNAs have a vital regulatory role in a wide range of inflammatory diseases by regulating the molecular mechanism of cytokines that cause inflammation through signal pathways. This review emphasizes the demand for cutting-edge genetic technologies and the development of novel pharmaceutical preparations to improve our understanding of the genes encoding by these miRNAs. It also focuses on the efficacy of miRNAs for control, early diagnosis, and prevention of endometritis.

Plasma microRNAs as non-invasive biomarkers in bovine endometritis caused by Gram-negative and Gram-positive bacteria

The purpose was to identify differentially expressed plasma microRNAs (miRNAs) in cows with clinical and subclinical endometritis. In this study clinical endometritis (CE; n = 23) based on vaginal discharge score (VDS), subclinical endometritis (SCE; n = 17) based on VDS (0), and endometrial cytology (the presence of 8.00% polymorphonuclear neutrophils (PMN) on days 21-31 and 5.00% on days 41-51 days in milk (DIM) and healthy cows (n = 21) based on vaginal discharge score (0), and endometrial cytology (< 5.00% PMN on days 21 - 31 and < 5.00% on days 41 - 51 DIM) were selected. The results showed that the expression level of miR-146a was significantly higher in the CE (19.17-fold), and SCE (6.22-fold) groups than those of healthy cows. The relative transcript abundance of miR-223 was considerably down-regulated in the CE (0.26-fold) and SCE (0.06-fold) compared to the healthy cows. The expression levels of miR-146a and miR-223 were significantly higher in the CE group which could be caused by Gram-negative bacterial infection. Our results showed that the expression level of plasma miRNAs postpartum could be used as a reliable marker to distinguish between SCE, CE and healthy cows.

An Interplay between Epigenetics and Translation in Oocyte Maturation and Embryo Development: Assisted Reproduction Perspective

Germ cell quality is a key prerequisite for successful fertilization and early embryo development. The quality is determined by the fine regulation of transcriptomic and proteomic profiles, which are prone to alteration by assisted reproduction technology (ART)-introduced in vitro methods. Gaining evidence shows the ART can influence preset epigenetic modifications within cultured oocytes or early embryos and affect their developmental competency. The aim of this review is to describe ART-determined epigenetic changes related to the oogenesis, early embryogenesis, and further in utero development. We confront the latest epigenetic, related epitranscriptomic, and translational regulation findings with the processes of meiotic maturation, fertilization, and early embryogenesis that impact the developmental competency and embryo quality. Post-ART embryo transfer, in utero implantation, and development (placentation, fetal development) are influenced by environmental and lifestyle factors. The review is emphasizing their epigenetic and ART contribution to fetal development. An epigenetic parallel among mouse, porcine, and bovine animal models and human ART is drawn to illustrate possible future mechanisms of infertility management as well as increase the awareness of the underlying mechanisms governing oocyte and embryo developmental complexity under ART conditions.

Comprehensive analysis of peripheral blood non-coding RNAs identifies a diagnostic panel for fungal infection after transplantation

The occurrence of fungal infection seriously affects the survival and life quality of transplanted patients. The accurate diagnosis is of particular importance in the early stage of infection. To develop a novel diagnostic method for this kind of patient, we established a post-transplant immunosuppressed mice model with fungus inoculation and collected their peripheral blood at specific time points after infection. After screening by microarray, differentially expressed miRNAs and lncRNAs were selected and homologously analyzed with those of human beings from the gene database. These miRNAs and lncRNAs candidates were validated by qRT-PCR in peripheral blood samples from transplanted patients. We found that, compared with normal transplanted patients, the levels of miR-215 and miR-let-7 c were up-regulated in the plasma of patients with fungal infection (P < 0.01), while levels of miR-154, miR-193a, NR_027669.1, and NR_036506.1 were down-regulated in their peripheral blood mononuclear cells (P < 0.01). Principal component analysis shows that the expression pattern of the above RNAs was different between the two groups. A 6-noncoding-RNA detection panel was established by the support vector machine analysis, whose area under the ROC curve was 0.927. The accuracy, precision, sensitivity, and specificity of this model were 0.928, 0.919, 0.944, and 0.910, respectively. Though our detection panel has excellent diagnostic efficacy, its clinical application value still needs to be further confirmed by multi-center prospective clinical trials.

Expression of genes associated with fertility in the uterus and oviduct of heifers challenged with lipopolysaccharide

Lipopolysaccharide (LPS) endotoxemia has been negatively associated with fertility. This study aimed to investigate the effect of LPS-induced inflammation on gene expression associated with bovine fertility in the uterus and oviduct. Sixteen healthy heifers were divided into two groups. The LPS group (n = 8) received two intravenous (i.v.) injections of 0.5 µg/kg of body weight of LPS with a 24-h interval, and the control group (n = 8) received two i.v. injections of saline solution with the same interval of time. All the animals had the follicular wave synchronized. Three days after the second injection of LPS, all animals were slaughtered and uterine and oviduct samples were collected. Gene expression associated with inflammatory response, thermal and oxidative stresses, oviduct environment quality, and uterine environment quality was evaluated. Body temperature and leucogram demonstrated that LPS induced an acute systemic inflammatory response. In the uterus, the expression of PTGS2 and NANOG genes was downregulated by the LPS challenge. However, no change in expression was observed in the other evaluated genes in the uterus, nor those evaluated in the oviduct. In conclusion, the inflammatory process triggered by LPS did not persist in the uterus and oviduct 3 days after challenge with LPS. Nonetheless, reduction in PTGS2 and NANOG expression in the uterus suggested that, indirectly, LPS may have a prolonged effect, which may affect corpus luteum and endometrial functions.

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.

Alterations in the Expression Profile of Serum miR-155, miR-223, miR-17, miR-200a, miR-205, as well as Levels of Interleukin 6, and Prostaglandins during Endometritis in Arabian Mares

So far the intimate link between serum microRNA (miRNA) and uterine inflammation in mares is unknown. We aimed (I) to investigate expression profile of eca-miR-155, eca-miR-223, eca-miR-17, eca-miR-200a, and eca-miR-205 (II) and to measure concentrations of interleukin 6 (IL-6), and prostaglandins (PGF_2α and PGE₂) in serum of mares with healthy and abnormal uterine status (endometritis). This study was conducted on 80 Arabian mares: young (4–7 years), and old (8–14 years). Mares were divided into 48 sub-fertile (endometritis) and 32 fertile (control) at stud farms. Serum was collected for measuring IL-6, PGF_2α, and PGE₂, as well as miRNA isolation and qRT-PCR. Concentrations of IL-6, PGE₂, and PGF_2α were higher in mares with endometritis compared to control. Age of mares had a remarkable effect on IL-6, PGE₂, and PGF_2α concentrations. Relative abundance of eca-miR-155, eca-miR-223, eca-miR-17, eca-miR-200a, and eca-miR-205 was higher in both young and old mares with endometritis. We noticed that eca-miR-155, eca-miR-223, eca-miR-200a, and eca-miR-205 revealed higher expression level in old than young mares with endometritis. This is the first study that has revealed the changes in cell free miRNA and serum inflammatory mediators during endometritis, and these findings could be used for a better understanding the pathophysiology mechanisms of endometritis in equine.

Analysis of miRNA expression changes in bovine endometrial stromal cells treated with lipopolysaccharide

After parturition, bovine uterine stromal cells are often exposed to complex bacterial and viral stimuli owing to epithelial cell rupture, resulting in an inflammatory response. In this study, we used an in vitro model to study the response of bovine endometrial stromal cells to inflammatory mediators and the associated regulated microRNAs in response to lipopolysaccharide. Lipopolysaccharide (LPS) is a bacterial wall component in gram-negative bacteria that causes inflammation upon immune recognition, which is used to create in vitro inflammation models. Thus, we used high-throughput RNA sequencing to identify miRNAs that may have an anti-inflammatory role in the LPS-induced inflammatory response. Two groups of bovine uterine cells were treated with phosphate buffer saline (PBS) and LPS, respectively. Compared with the control (PBS) group, the LPS-treated group had 219 differentially expressed miRNAs, of which 113 were upregulated, and 106 were downregulated. Gene ontology enrichment analysis revealed that the target genes of differentially expressed miRNAs were significantly enriched in several activities, such as transferase activity, small molecule binding, and protein binding. Kyoto Encyclopedia of Genes and Genomes pathway analysis indicated that the target genes of differential miRNAs were significantly enriched in fluid shear stress and atherosclerosis, MAPK signaling pathway, TNF signaling pathway. By analyzing differentially expressed miRNAs, we found that miR-200c, miR-1247-3p, and let-7b are directly related to the inflammatory response. For instance, miR-200c target genes (MAP3K1, MAP4K3, MAPKAPK5, MAP3K8, MAP3K5) and let-7b target genes (CASP3, IL13, MAPK8, CXCL10) were significantly enriched in the MAPK and IL-17 signaling pathways, respectively. In summary, our research provides insight into the molecular mechanism underlying LPS-induced inflammation in vitro, which may unveil new targets for the treatment of endometritis.

Changes in Oviductal Cells and Small Extracellular Vesicles miRNAs in Pregnant Cows

Early embryonic development occurs in the oviduct, where an ideal microenvironment is provided by the epithelial cells and by the oviductal fluid produced by these cells. The oviductal fluid contains small extracellular vesicles (sEVs), which through their contents, including microRNAs (miRNAs), can ensure proper cell communication between the mother and the embryo. However, little is known about the modulation of miRNAs within oviductal epithelial cells (OECs) and sEVs from the oviductal fluid in pregnant cows. In this study, we evaluate the miRNAs profile in sEVs from the oviductal flushing (OF-sEVs) and OECs from pregnant cows compared to non-pregnant, at 120 h after ovulation induction. In OF-sEVs, eight miRNAs (bta-miR-126-5p, bta-miR-129, bta-miR-140, bta-miR-188, bta-miR-219, bta-miR-345-3p, bta-miR-4523, and bta-miR-760-3p) were up-regulated in pregnant and one miRNA (bta-miR-331-5p) was up-regulated in non-pregnant cows. In OECs, six miRNAs (bta-miR-133b, bta-miR-205, bta-miR-584, bta-miR-551a, bta-miR-1193, and bta-miR-1225-3p) were up-regulated in non-pregnant and none was up-regulated in pregnant cows. Our results suggest that embryonic maternal communication mediated by sEVs initiates in the oviduct, and the passage of gametes and the embryo presence modulate miRNAs contents of sEVs and OECs. Furthermore, we demonstrated the transcriptional levels modulation of selected genes in OECs in pregnant cows. Therefore, the embryonic-maternal crosstalk potentially begins during early embryonic development in the oviduct through the modulation of miRNAs in OECs and sEVs in pregnant cows.

A Review of Ureaplasma diversum: A Representative of the Mollicute Class Associated With Reproductive and Respiratory Disorders in Cattle

The Mollicutes class encompasses wall-less microbes with a reduced genome. They may infect plants, insects, humans, and animals including those on farms and in livestock. Ureaplasma diversum is a mollicute associated with decreased reproduction mainly in the conception rate in cattle, as well as weight loss and decreased quality in milk production. Therefore, U. diversum infection contributes to important economic losses, mainly in large cattle-producing countries such as the United States, China, Brazil, and India. The characteristics of Mollicutes, virulence, and pathogenic variations make it difficult to control their infections. Genomic analysis, prevalence studies, and immunomodulation assays help better understand the pathogenesis of bovine ureaplasma. Here we present the main features of transmission, virulence, immune response, and pathogenesis of U. diversum in bovines.

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.

Effect of rosiglitazone on developmental competence of mouse embryos treated with lipopolysaccharide

Lipopolysaccharide (LPS) significantly reduces pre- and post-implantation developmental competence of embryos. One of the reason of this effect could be a consequence of TLR4-mediated inflammation. In this study, we assessed the anti-inflammatory effect of peroxisome proliferator activated receptor γ (PPAR γ) agonist, rosiglitazone (RGZ), in LPS-treated mouse embryos. Initially, the optimal doses of LPS, RGZ and GW9662 (a potent and selective PPARγ antagonist) were determined by treating the mouse zygotes up to blastocyst stage and assessment of compaction and blastocyst rates. Quantitative PCR was used to assess the mRNA expression of inflammatory cytokines. Immunostaining was used to study the translocation of PPARγ in blastocysts. Finally, the blastocysts were transferred to surrogate mouse to determine the post-implantation developmental competence. 0.0625 mg/mL of LPS significantly reduced the developmental competency by around 50% compared to control group. 10 μM of RGZ significantly ameliorated the toxic effect of LPS, which was also significantly reversed by 1.25 μM GW9662. Through immunostaining, it was shown that LPS could prevent the translocation of PPARγ to nucleus; and translocation was facilitated by RGZ and this effect was reversed by GW9662. A similar effect was also observed for the mRNA expression of inflammatory cytokines (Il-1β and Il-6). LPS significantly increased the expression of these cytokines, while RGZ significantly reduced their expression, which was also significantly reversed by GW9662. It was also shown that embryos exposed to LPS had significantly reduced post implantation developmental competence which was considerably improved by treatment with RGZ. In conclusion, these data may have clinical implications for ameliorating the adverse effects of LPS in dairy farming and infertility treatment.

Influence of pathogens causing clinical mastitis on reproductive variables of dairy cows

In dairy cattle, mastitis is a disease of the mammary gland caused by pathogens such as bacteria, viruses, fungi, and algae. Mastitis causes economic losses to dairy farms as well as public health concerns. The reproductive efficiency of commercial dairy herds has important implications for the economic success of dairy operations and is strongly associated with the health status of cows. Mastitis has previously been linked with decreased fertility of dairy cows, but the effect of specific pathogens on the severity of fertility reduction is still unclear. In this study, cows diagnosed with mastitis caused by major pathogens (Staphylococcus aureus, Streptococcus agalactiae, Escherichia coli, Klebsiella spp., Mycoplasma spp., and environmental Streptococcus) needed more artificial inseminations (AI) than did cows with mastitis caused by minor pathogens (coagulase-negative Staphylococcus and Corynebacterium spp.) and healthy cows. Cows diagnosed with mastitis, independent of what pathogen was causing mastitis, had more days open compared with nonmastitic cows. The percentage of cows that successfully established pregnancy at first AI was greater for the control group than for the major pathogens group but not significantly different from the minor pathogens group. Pregnancy loss was lower in the control group than in the major pathogens group; however, there was no difference compared with the minor pathogen group. Mastitis caused by gram-negative bacteria decreased the percentage of pregnancy per first AI and increased days open and pregnancy loss compared with the control group. Cows with mastitis caused by gram-positive bacteria also had increased days open compared with control cows. This study shows that different mastitis-causing bacteria can affect the fertility of cows differently. Mastitis events caused by major pathogens and gram-negative bacteria were associated with the greatest decrease in reproductive efficiency.

Adverse reproductive effects of S100A9 on bovine sperm and early embryonic development in vitro

The phenomenon of aging arises from multiple, complex interactions causing dysfunction in cells and organs. In particular, fertility drastically decreases with age. Previously, we have demonstrated that the functional characteristics of the bovine oviduct and uterus change with the age-dependent upregulation of inflammation and noted that S100A9 triggers inflammatory responses in oviduct epithelial cells. In the present study, we investigated the hypothesis that S100A9 affects reproductive events to aspect such as sperm function, fertilization, and the development of the embryo in cows. To investigate the effect of S100A9 on bovine sperm, we incubated sperms in vitro with S100A9 for 5 h and observed significantly decreased sperm motility and viability. During in vitro fertilization, S100A9 treatment for 5 h did not affect the rate of fertilization, time of first division of embryos, or embryo development to blastocyst stage. Treatment of 2-cell stage embryos with S100A9 for 5 h significantly reduced the proportion of cells undergoing normal division (4-8 cell embryos) and embryo development to the blastocyst stage. In experiment involving 24 h treatment of 2-cell embryos, the development of all embryos stopped at the 2-cell stage in the S100A9-treated group. In blastocyst-stage embryos, S100A9 treatment significantly stimulated the expression of endoplasmic reticulum (ER) and the mRNA expression of ER stress markers, and activated caspase-3 with subsequent nuclear fragmentation. Pre-treatment with an ER stress inhibitor significantly suppressed caspase-3 activation by the S100A9 treatment, suggesting that S100A9 induces blastocyst dysfunction by apoptosis (via caspase-3 activation) depending on ER stress. These results indicate that direct exposure to S100A9 exerted adverse effects on sperm function and embryo development. These findings suggest that excessive dose of S100A9 may have an adverse effect to the reproductive machinery by inducing inflammation and tissue dysfunction.

The attenuation of the toxic effects of LPS on mouse pre-implantation development by alpha-lipoic acid

The present study was conducted to evaluate the effects of alpha-lipoic acid (ALA) on quantitative and qualitative indices of mouse embryos challenged by lipopolysaccharide (LPS). Having determined the effective concentrations of LPS (1 mg/mL) that could reduce blastocyst formation rate by around 50% and the optimal concentration of ALA (10 μM) that could attenuate the toxic effects of LPS on blastocyst formation, the following indices were defined: inner cell mass and trophectoderm cell numbers, blastocyst mitochondrial distribution, ROS and GSH levels, as well as the relative expression of Tlr-4. Nrf-2 and Tnf-RI/P-60 receptor involved in inflammatory pathways. Finally, embryos derived from the experimental and control groups were transferred to synchronized recipients and their implantation rate and post-implantation capacity were determined. Treatment with LPS resulted in an increase in intracellular ROS level (P ≤ 0.05), and remarkable decreases (P ≤ 0.05) in intracellular GSH content, mitochondrial mass, and blastocyst quality. ALA attenuated all the aforementioned negative effects of LPS. The relative expression levels of Nrf-2 and Tnf-RI/P-60 receptor (P ≤ 0.05) significantly increased in response to LPS, and treatment with ALA significantly reduced the relative expression of Tnf-RI/P-60. ALA also improved the post-implantation developmental capacity of embryos treated with LPS. In conclusion, our findings indicate that the reproductive toxicity of LPS could be overcome by ALA treatment. These effects were mainly due to the improvements made in intracellular antioxidant capacity as well as suppression of some inflammatory elements, especially the main receptor of TNF-α, the Tnf-RI/P-60, involved in induction of apoptosis. These observations have important implications for dairy farming and treatment of infertility.

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.

S100A8, which increases with age, induces cellular senescence-like changes in bovine oviduct epithelial cells

PROBLEM

The oviduct is an essential component in reproduction and oviduct epithelial cells (OECs) secrete various types of cytokine. However, mechanisms of aging and inflammation of OECs are unknown. We previously reported the age-dependent functional changes of bovine OECs such that aged OECs expressed higher levels of inflammatory cytokines. We selected S100A8 and S100A9 as molecules expressed more highly in aged OECs, as candidates to induce age-related changes, and investigated using bovine OECs.

METHOD OF STUDY

The OECs were isolated from bovine oviductal tissues (Aged, more than 120 months; Young, between 30 and 50 months) and cultured.

RESULTS

Aged OECs exhibited higher senescence-associated (SA)-β-gal staining (a biomarker of cellular senescence) and mRNA expression of SA-inflammatory cytokines than young OECs. Cellular senescence occurred in both young and aged OECs upon passaging the cells. Treatment with S100A8, but not S100A9, resulted in the induction of cellular senescence in bovine OECs. Both S100A8 and S100A9 stimulated the secretion of the inflammatory cytokine IL-8 from bovine OECs. S100A8-induced IL-8 secretion was dependent on receptor RAGE, AP-1 activation, and reactive oxygen species production. In addition, S100A8 reduced the content of collagen while inducing the expression of matrix metalloproteinases, suggesting the induction of dysregulation of the extracellular matrix in OECs.

CONCLUSION

We suggest that bovine OECs recognize an excessive increase in age-associated DAMPs, such as S100A8 and S100A9, and that these signals may contribute to chronic oviductal inflammation, resulting in infertility associated with oviductal dysfunction.

Understanding the hidden relations between pro- and anti-inflammatory cytokine genes in bovine oviduct epithelium using a multilayer response surface method

An understanding gene-gene interaction helps users to design the next experiments efficiently and (if applicable) to make a better decision of drugs application based on the different biological conditions of the patients. This study aimed to identify changes in the hidden relationships between pro- and anti-inflammatory cytokine genes in the bovine oviduct epithelial cells (BOECs) under various experimental conditions using a multilayer response surface method. It was noted that under physiological conditions (BOECs with sperm or sex hormones, such as ovarian sex steroids and LH), the mRNA expressions of IL10, IL1B, TNFA, TLR4, and TNFA were associated with IL1B, TNFA, TLR4, IL4, and IL10, respectively. Under pathophysiological + physiological conditions (BOECs with lipopolysaccharide + hormones, alpha-1-acid glycoprotein + hormones, zearalenone + hormones, or urea + hormones), the relationship among genes was changed. For example, the expression of IL10 and TNFA was associated with (IL1B, TNFA, or IL4) and TLR4 expression, respectively. Furthermore, under physiological conditions, the co-expression of IL10 + TNFA, TLR4 + IL4, TNFA + IL4, TNFA + IL4, or IL10 + IL1B and under pathophysiological + physiological conditions, the co-expression of IL10 + IL4, IL4 + IL10, TNFA + IL10, TNFA + TLR4, or IL10 + IL1B were associated with IL1B, TNFA, TLR4, IL10, or IL4 expression, respectively. Collectively, the relationships between pro- and anti-inflammatory cytokine genes can be changed with respect to the presence/absence of toxins, sex hormones, sperm, and co-expression of other gene pairs in BOECs, suggesting that considerable cautions are needed in interpreting the results obtained from such narrowly focused in vitro studies.

Expression profiling of selected miRNAs in equine endometrium in response to LPS challenge in vitro: A new understanding of the inflammatory immune response

Bacterial infections of the genital tract are the major cause of reproductive failure in the mares. MiRNAs are important regulators of gene expression, mostly through transcriptional and translational regression. We hypothesized that LPS induced aberrant expression of miRNAs and their targets, which are involved in regulation of uterine homeostasis. Three groups of primary endometrial epithelial and stromal cells, and endometrial tissue explants were cultured. The 1^st group was kept as control, while the 2^nd and 3^rd groups were challenged with low (0.5 μg/mL) or high (3.0 μg/mL) doses of Lipopolysaccharides (LPS). Cell pellets and tissue explants were collected after 24 and 48 h, for total RNA isolation and qRT-PCR of the selected miRNAs and their targets. Culture media and cell lysates were collected after 24 and 48 h, for cytokines (IL6 and TNF_α) and prostaglandins (PGE₂ & PGF_α2) measurement. Both endometrial cells expressed TLR4 and its accessory molecules (MyD88 & CD14) that are required for triggering inflammatory immune response after LPS, via up-regulation of TRAF6, TNF_α, IL6 and IL8, compared to the respective control. After both doses of LPS challenge, miR-155, miR-223 and miR-17 were significantly increased; miR-181b, miR-21 and let-7a were significantly decreased compared to respective controls. Interestingly, miR-24 and miR-532-5p were clearly up-regulated after only the low LPS dose. TNF_α, IL6 and PGs in culture media and from cell lysates revealed dose- and time-dependent patterns, after LPS. Results indicated that both epithelial and stromal cells have a primary role in innate immune response after LPS challenge, while this recognition occurred via TLR4 and its accessory molecules. Dysregulation of miRNAs and their targets expression after LPS might affect normal uterine function through perturbation of PG and cytokine secretion.

Up-regulated mRNA expression of some anti-inflammatory mediators in bovine oviduct epithelial cells by urea in vitro: Cellular pathways by Reactome analysis

Increased urea concentration is a major cause of low fertility in dairy cows fed high-protein diets. A strong correlation exists between the urea concentration in the blood and oviduct fluid of dairy cows. In this study, bovine oviduct epithelial cells (BOECs) were incubated with varying concentrations of urea (0, 20, 40, and 80 mg/dL) in the absence of ovarian sex steroids (estradiol and progesterone) and luteinizing hormone. The 80 mg/dL urea reduced the cell viability, and thus was excluded in further analysis. Compared to the control (U0), the 20 mg/dL urea (U20) increased the mRNA expression of Toll-like receptor (TLR) 4, interleukin (IL) 10, IL4, and prostaglandin (PG) E synthase (mPGES) but decreased the mRNA expression of tumor necrosis factor α (TNFA). Compared to U0, the 40 mg/dL urea (U40) decreased the mRNA expression of TNFA and increased alpha-1-acid glycoprotein (AGP). U40 also increased TLR2, IL10, and IL4 mRNA expression compared to U0. In addition, compared to U20, the U40 decreased the mRNA expression of TLR4 and IL1B but increased that of AGP and TLR2. Subsequently, the mRNA expression data were then projected into the Reactome database. The Reactome analysis showed that pathways, including cytokine signaling in the immune system (i.e., TNFs bind their physiological receptors) and death receptor signaling (i.e., TNF signaling), were down-regulated in the presence of urea compared to the U0 group. These in vitro data implied that high urea level can alter the balance between pro- and anti-inflammatory responses in BOECs, thus providing a suboptimal environment for the early reproductive events or a weakened innate immune system, predisposing the oviduct to infections.

Detrimental effects of lipopolysaccharides on maturation of bovine oocytes

Objective

Gram-negative bacteria lipopolysaccharide (LPS) has been reported to be associated with uterine impairment, embryonic resorption, ovarian dysfunction, and follicle retardation. Here, we aimed to investigate the toxic effects of LPS on the maturation ability and parthenogenetic developmental competence of bovine oocytes.

Methods

First, we developed an in vitro model to study the response of bovine cumulus-oocyte complexes (COCs) to LPS stress. After incubating germinal vesicle COCs in 10 μg/mL of LPS, we analyzed the following three aspects: the expression levels of the LPS receptor toll-like receptor 4 (TLR4) in COCs, activities of intracellular signaling protein p38 mitogen-activated protein kinase (p38 MAPK) and nuclear factor-kappa B (NF-κB); and the concentrations of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and IL-6. Furthermore, we determined the effects of LPS on the maturation ability and parthenogenetic developmental competence of bovine oocytes.

Results

The results revealed that LPS treatment significantly elevated TLR4 mRNA and protein expression levels in COCs. Exposure of COCs to LPS also resulted in a marked increase in activity of the intracellular signaling protein p-p38 MAPK and NF-κB. Furthermore, oocytes cultured in maturation medium containing LPS had significantly higher concentrations of the proinflammatory cytokines IL-1β, TNF-α, and IL-6. LPS exposure significantly decreased the first polar body extrusion rate. The cytoplasmic maturation, characterized by polar body extrusion and distribution of peripheral cortical granules, was significantly impaired in LPS-treated oocytes. Moreover, LPS exposure significantly increased intracellular reactive oxygen species levels and the relative mRNA abundance of the antioxidants thioredoxin (Trx), Trx2, and peroxiredoxin 1 in oocytes. Moreover, the early apoptotic rate and the release of cytochrome C were significantly increased in response to LPS. The cleavage, morula, and blastocyst formation rates were significantly lower in parthenogenetically activated oocytes exposed to LPS, while the incidence of apoptotic nuclei in blastocysts was significantly increased.

Conclusion

Together, these results provide an underlying mechanism by which LPS impairs maturation potential in bovine oocytes.

Pre- and post-puberty expression of genes and proteins in the uterus of Bos indicus heifers: the luteal phase effect post-puberty

Progesterone signaling and uterine function are crucial in terms of pregnancy establishment. To investigate how the uterine tissue and its secretion changes in relation to puberty, we sampled tissue and uterine fluid from six pre- and six post-pubertal Brahman heifers. Post-pubertal heifers were sampled in the luteal phase. Gene expression of the uterine tissue was investigated with RNA-sequencing, whereas the uterine fluid was used for protein profiling with mass spectrometry. A total of 4034 genes were differentially expressed (DE) at a nominal P-value of 0.05, and 26 genes were significantly DE after Bonferroni correction (P < 3.1 × 10^-6 ). We also identified 79 proteins (out of 230 proteins) that were DE (P < 1 × 10^-5 ) in the uterine fluid. When we compared proteomics and transcriptome results, four DE proteins were identified as being encoded by DE genes: OVGP1, GRP, CAP1 and HBA. Except for CAP1, the other three had lower expression post-puberty. The function of these four genes hypothetically related to preparation of the uterus for a potential pregnancy is discussed in the context of puberty. All DE genes and proteins were also used in pathway and ontology enrichment analyses to investigate overall function. The DE genes were enriched for terms related to ribosomal activity. Transcription factors that were deemed key regulators of DE genes are also reported. Transcription factors ZNF567, ZNF775, RELA, PIAS2, LHX4, SOX2, MEF2C, ZNF354C, HMG20A, TCF7L2, ZNF420, HIC1, GTF3A and two novel genes had the highest regulatory impact factor scores. These data can help to understand how puberty influences uterine function.

Ureaplasma diversum and Its Membrane-Associated Lipoproteins Activate Inflammatory Genes Through the NF-κB Pathway via Toll-Like Receptor 4

Objectives:Ureaplasma diversum is a pathogen of cows that may cause intense inflammatory responses in the reproductive tract and interfere with bovine reproduction. The aims of this study were to evaluate the immune response of bovine blastocysts and macrophages to U. diversum infection and to evaluate the invasion capacity of this microorganism in bovine blastocysts.

Methods: Viable and heat-inactivated U. diversum strains ATCC 49782 and CI-GOTA and their extracted membrane lipoproteins were inoculated in macrophages in the presence or absence of signaling blockers of Toll-Like Receptor (TLR) 4, TLR2/4, and Nuclear Factor KB (NF-κB). In addition, the same viable U. diversum strains were used to infect bovine blastocysts. RNA was extracted from infected and lipoprotein-exposed macrophages and infected blastocysts and assayed by qPCR to evaluate the expression of Interleukin 1 beta (IL-1β), Tumor Necrosis Factor Alpha (TNF-α), TLR2 and TLR4 genes. U. diversum internalization in blastocysts was followed by confocal microscopy.

Results: Both Ureaplasma strains and different concentrations of extracted lipoproteins induced a higher gene expression of IL-1β, TNF-α, TLR2, and TLR4 in macrophages (p < 0.05) when compared to non-infected cells. The used blockers inhibited the expression of IL-1β and TNF-α in all treatments. Moreover, U. diversum was able to internalize within blastocysts and induce a higher gene expression of IL-1b and TNF- α when compared to non-infected blastocysts (p < 0.05).

Conclusion: The obtained results strongly suggest that U. diversum and its lipoproteins interact with TLR4 in a signaling pathway acting via NF-kB signaling to stimulate the inflammatory response. This is the first study to evaluate the in vitro immunological response of macrophages and bovine blastocysts against U. diversum. These results may contribute to a better understanding of the immunomodulatory activity and pathogenicity of this infectious agent.

Urea changes oocyte competence and gene expression in resultant bovine embryo in vitro

SummaryNutrition influences the microenvironment in the proximity of oocyte and affects early embryonic development. Elevated blood urea nitrogen, even in healthy dairy cows, is associated with reduced fertility and there is high correlation between blood urea levels and follicular fluid urea levels. Using a docking calculation (in silico), urea showed a favorable binding activity towards the ZP-N domain of ZP3, that of ZP2, and towards the predicted full-length sperm receptor ZP3. Supplementation of oocyte maturation medium with nutrition-related levels of urea (20 or 40 mg/dl as seen in healthy dairy cows fed on low or high dietary protein, respectively) dose-dependently increased: (i) the proportion of oocytes that remained uncleaved; and (ii) oocyte degeneration; and reduced cleavage, blastocyst and hatching rates. High levels of urea induced shrinkage in oocytes, visualised using scanning electron microscopy. Urea downregulated NANOG while dose-dependently upregulating OCT4, DNMT1, and BCL2 expression. Urea at 20 mg/dl induced BAX expression. Using mathematical modelling, the rate of oocyte degeneration was sensitive to urea levels; while cleavage, blastocyst and hatching rates exhibited negative sensitivity. The present data imply a novel role for urea in reducing oocyte competence and changing gene expression in the resultant embryos.

Natural and environmental oestrogens induce TGFB1 synthesis in oviduct cells

Autocrine/paracrine factors generated in response to 17β-oestradiol (E2), within the oviduct, facilitate early embryo development for implantation. Since transforming growth factor beta 1 (TGFB1) plays a key role in embryo implantation, regulation of its synthesis by E2 may be of biological/pathophysiological relevance. Here, we investigated whether oviduct cells synthesize TGFB1 and whether E2 and environmental oestrogens (EOEs; xenoestrogens and phytoestrogens) modulate its synthesis. Under basal conditions, bovine oviduct cells (OCs; oviduct epithelial cells and oviduct fibroblasts; 1:1 ratio) synthesized TGFB1. E2 concentration-dependent induced TGFB1 levels in OCs and these effects were mimicked by some, but not all EOEs (genistein, biochanin A and 4-hydroxy-2',4',6'-trichlorobiphenyl, 4-hydroxy-2',4',6'-dichlorobiphenyl); moreover, EOEs enhanced (P < 0.05) the stimulatory effects of E2 on TGFB1 synthesis. The OCs expressed oestrogen receptors alpha and beta and aryl hydrocarbon; moreover, co-treatment with ER antagonist ICI182780 blocked the stimulatory effects of E2 and EOEs on TGFB1 synthesis. Treatment with non-permeable E2-BSA failed to induce TGFB1, thereby ruling out the involvement of membrane ERs. Cycloheximide (protein synthesis inhibitor) blocked E2-induced TGFB1 synthesis providing evidence for de novo synthesis. The stimulatory effects of E2 and EOEs, were inhibited (P < 0.05) by MAPK inhibitor (PD98059), whereas intracellular-Ca²⁺ chelator (BAPTA-AM) and adenylyl cyclase inhibitor (SQ22536) abrogated the effects of E2, but not EOEs, suggesting that post-ER effects of E2 and EOEs involve different pathways. Our results provide the first evidence that in OCs, E2 and EOEs stimulate TGFB1 synthesis via an ER-dependent pathway. Exposure of the oviduct to EOEs may result in continuous/sustained induction of TGFB1 levels in a non-cyclic fashion and may induce deleterious effects on reproduction.

Profiling of proteins secreted in the bovine oviduct reveals diverse functions of this luminal microenvironment

The oviductal microenvironment is a site for key events that involve gamete maturation, fertilization and early embryo development. Secretions into the oviductal lumen by either the lining epithelium or by transudation of plasma constituents are known to contain elements conducive for reproductive success. Although previous studies have identified some of these factors involved in reproduction, knowledge of secreted proteins in the oviductal fluid remains rudimentary with limited definition of function even in extensively studied species like cattle. In this study, we used a shotgun proteomics approach followed by bioinformatics sequence prediction to identify secreted proteins present in the bovine oviductal fluid (ex vivo) and secretions from the bovine oviductal epithelial cells (in vitro). From a total of 2087 proteins identified, 266 proteins could be classified as secreted, 109 (41%) of which were common for both in vivo and in vitro conditions. Pathway analysis indicated different classes of proteins that included growth factors, metabolic regulators, immune modulators, enzymes, and extracellular matrix components. Functional analysis revealed mechanisms in the oviductal lumen linked to immune homeostasis, gamete maturation, fertilization and early embryo development. These results point to several novel components that work together with known elements mediating functional homeostasis, and highlight the diversity of machinery associated with oviductal physiology and early events in cattle fertility.

Different inflammatory responses of bovine oviductal epithelial cells in vitro to bacterial species with distinct pathogenicity characteristics and passage number

The bovine oviduct provides the site for fertilization and early embryonic development. Modifications to this physiological environment, for instance the presence of pathogenic bacterial species, could diminish reproductive success at early stages of pregnancy. The aim of this study was to elucidate the inflammatory responses of bovine oviductal epithelial cells (BOEC) to a pathogenic bacterial species (Trueperella pyogenes) and a potentially pathogenic bacterium (Bacillus pumilus). BOEC from four healthy animals were isolated, cultured in passage 0 (P0) and passaged until P3. Trypan blue staining determined BOEC viability during 24 h co-culture with different multiplicities of infection (MOI) of T. pyogenes (MOI 0.01, 0.05, 0.1 and 1) or B. pumilus (MOI 1 and 10). BOEC remained viable when co-cultured with T. pyogenes at MOI 0.01 and with B. pumilus at MOI 1 and 10. Extracted total RNA from control and bacteria co-cultured samples was subjected to reverse transcription-quantitative polymerase chain reaction (RTq-PCR) to determine mRNA expression of various studied genes. The rate of release of interleukin 8 (IL8) and prostaglandin E₂ (PGE₂) from BOEC was measured by ELISA after 24 h co-culture with bacteria. RT-qPCR of various selected pro-inflammatory factors revealed similar mRNA expression of pro-inflammatory factors in BOEC co-cultured with T. pyogenes and in the controls. Higher mRNA expression of IL 1A, -1B, tumor necrosis factor alpha and CXC ligand (CXCL) 1/2, -3, -5 and IL8 and PG synthesis enzymes in BOEC co-cultured with B. pumilus was observed. In the presence of B. pumilus a higher amount of IL8 and PGE₂ was released from BOEC than from controls. The viability and pro-inflammatory response of P3 BOEC incubated with bacteria was lower than in P0 BOEC. These findings illustrate the pathogenicity of T. pyogenes towards BOEC in detail and the potential role of B. pumilus in generating inflammation in oviductal cells. Culturing conditions influenced the pro-inflammatory responses of BOEC towards bacteria. Therefore, researchers conducting epithelial-bacterial in vitro co-culture should not underestimate the effects of these parameters.

Effect of lipopolysaccharide on the expression of inflammatory mRNAs and microRNAs in the mouse oviduct

Infection with Gram-negative bacteria is a major cause of aberrant inflammation in the oviduct; consequences can include tubal-based infertility and/or ectopic pregnancy. Understanding the inflammatory response is necessary for the development of novel treatment options that counter inflammation-induced infertility. The aim of the present study was to determine the effect of intraperitoneal (i.p.) administration of Escherichia coli-derived lipopolysaccharide (LPS) on the acute expression of inflammatory mRNAs and microRNAs (miRNAs) in the oviduct. On the day of oestrus, 6- to 8-week-old CD1 mice were injected i.p. with 0, 2 or 10µg LPS in 100μL phosphate-buffered saline. Mice were killed 24h later and the oviducts collected for gene expression analyses. The effect of treatment on the expression of mRNAs and miRNAs was evaluated by one-way analysis of variance (ANOVA), with treatment means of differentially expressed (P<0.05) transcripts separated using Scheffé's test. LPS treatment affected 49 of 179 targeted inflammatory mRNAs and 51 of 578 miRNAs (P<0.05). The identity of differentially expressed miRNAs predicted as regulators of chemokine and interleukin ligand mRNAs was then extracted using the microRNA.org database. The results of the present study indicate that systemic treatment with LPS induces a robust inflammatory response in the oviducts of mice, and identify key mRNAs and putative miRNAs modulating this effect.

Palmitic acid stimulates interleukin-8 via the TLR4/NF-κB/ROS pathway and induces mitochondrial dysfunction in bovine oviduct epithelial cells

PROBLEM

We investigated the effect of palmitic acid (PA), a major saturated fatty acid in NEFA, on bovine oviduct epithelial cells (OECs) during in vitro cell culture.

METHOD OF STUDY

Bovine oviductal tissues ipsilateral to the corpus luteum were collected 1-3 days after ovulation; the OECs were isolated and cultured.

RESULTS

PA increased lipid accumulation and activated caspase-3 in OECs, resulting in decreased cell proliferation. PA also stimulated the secretion of inflammatory cytokine interleukin (IL)-8 depending on TLR4, NF-κB activation, and reactive oxygen species (ROS) production. Moreover, PA induced mitochondrial dysfunction, including mitochondrial fission, ATP production, and mitochondrial ROS production. It also increased levels of LC3 and p62 proteins, suggesting autophagy induction in OECs.

CONCLUSION

We suggest that bovine OECs recognize an excessive increase in endogenous and sterile danger signals, such as PA, which may contribute to chronic oviductal inflammation, resulting in infertility associated with oviductal dysfunction.

Lipopolysaccharide (LPS) disrupts particle transport, cilia function and sperm motility in an ex vivo oviduct model

The oviduct functions in the transportation of gametes to the site of fertilization (the ampulla) and is the site of early embryonic development. Alterations of this early developmental environment, such as the presence of sexually transmitted pathogens, may affect oviduct function leading to reduced fertilization rates and contribute to compromised embryonic development. In this study, sperm interactions, particle transport speed (PTS) and cilia beat frequency (CBF) in the ampulla following exposure to lipopolysaccharide (LPS), a constituent of the sexually transmitted pathogens Chlamydia trachomatis and Chlamydia abortus, was investigated. Three complementary experiments were performed to analyse; (1) bound sperm motility and cilia function (2) transport velocity in the oviduct and (3) the expression of genes related to immune function and inflammatory response (CASP3, CD14, MYD88, TLR4 and TRAF6). The motility of bound sperm was significantly lower in ampullae that were exposed to LPS. CBF and PTS significantly increased after treatment with LPS for 2 hours. Finally, gene expression analysis revealed that CASP3 and CD14 were significantly upregulated and TLR4 trended towards increased expression following treatment with LPS. These findings provide an insight on the impact of LPS on the oviduct sperm interaction, and have implications for both male and female fertility.