Pathogen-associated molecular patterns initiate inflammation and perturb the endocrine function of bovine granulosa cells from ovarian dominant follicles via TLR2 and TLR4 pathways

Engineered exosome as a biological nanoplatform for drug delivery of Rosmarinic acid to improve implantation in mice with induced endometritis

Endometritis is an inflammatory and histopathologic disease in uterine tissues that interferes with the proper decidualization and implantation of the embryo. In this study, rosmarinic acid (RA) is used as an anti-inflammatory agent that encapsulates in exosomes and is used to attenuate lipopolysaccharide (LPS)-induced endometritis and improve implantation. For this purpose, exosomes were loaded with RA and then administrated into the animal groups, including RA, exosome, RA plus exosome (RA + Exo), and RA-loaded exosomes (RALExo) groups. The concentrations of RA or exosomes used in this study were 10 mg/kg, and the compounds were injected into the uterine horn 24 h following the induction of endometritis. Upon the presence of inflammation detected by the histopathological method, the most proper groups were mated with male mice. The effect of the treatment group on the implantation rate, progesterone levels, and gene expressions were assessed by Chicago Blue staining, enzyme-linked immunosorbent assay (ELISA), and Quantitative PCR (qPCR), respectively. Results showed RALExo10 and RA10 + Exo10 groups improved pathological alterations, enhanced progesterone levels, increased implantation rate, as well as heightened expression levels of Leukemia inhibitory factor (LIF) and Mucin-16 (MUC-16) genes. Besides, the expression levels of inflammatory cytokines, including Transforming growth factor-β (TGF-β), Interlukine-10 (IL-10), Interlukine-15 (IL-15), and Interlukine-18 (IL-18), were regulated. Our findings indicated that the expression of LIF, Muc-16 genes as well as IL-18, were significantly correlated with serum progesterone concentrations and the implantation rate in the treatment groups. The RALExo10 and RA10 + Exo10 groups showed ameliorated implantation rates in experimental groups.

Neurotensin agonist PD149163 modulates lipopolysaccharide induced inflammation and oxidative stress in the female reproductive system of mice

Inflammation-mediated reproductive health problems in females have become an emerging concern. The present investigation was aimed to elucidate the efficacy of the PD149163, agonist of the type I neurotensin receptor, in preventing/ameliorating the lipopolysaccharide (LPS) induced inflammation of the female reproductive system of the mice. Female Swiss Albino Mice (8 weeks old) were maintained in three groups (6/group): Group I as Control, Group II and Group III were exposed to intraperitoneal (i.p) LPS (1 mg/kg bw) for 5 days followed by treatment with PD149163 (100 μg/kg BW i.p.) to Group III (LPS + PD) for 28 days. After termination of the experiment on 29th day, plasma levels of inflammatory cytokines, LH, FSH, estradiol, corticosterone, oxidative stress effects in the ovary and histopathological study of the ovary and uterine horn were done. LPS-induced inflammation of the ovary and uterine horn was ameliorated/prevented by PD149163 as reflected in the reduced histopathological scores, significant elevation of the plasma anti-inflammatory cytokine IL-10 and decrease of the pro inflammatory cytokines TNF-α and IL-6. Significant decrease of lipid peroxide, increase of antioxidant defense enzymes, Superoxide dismutase and Catalase in the ovary indicated reduction of oxidative stress. The plasma levels of the reproduction related hormones and corticosterone were restored. PD149163 acts as an anti-inflammatory and anti-oxidative agent in modulation of inflammation in the female reproductive system (ovary & uterine horn). These findings suggest that the therapeutic potential of the analogs of neurotensin including PD149163 should be explored for the treatment of the female reproductive health issues.

Viperin (RSAD2) gene expression in peripheral blood mononuclear cells of pregnant crossbred beef cows is altered by Bos indicus genetics

The expression of interferon (IFN) stimulated genes (ISGs) in lymphocytes has been used for pregnancy diagnosis in cattle. However, among-cow variability has yielded sub-optimal predictive accuracy. We hypothesized that the expression of ISGs (ISG15, OAS1, RSAD2, CLEC3B, and AKR1B1) in early pregnancy varies according to the proportion of Bos indicus (B. indicus) genetics on females. Multiparous cows were classified in three genetic groups, High Angus (HA; n = 45 [0-33% Brahman influence]), Angus-Brahman (AB; n = 30 [34-67%]), and High Brahman (HB; n = 19 [68-100%]) and submitted to a Select-Synch + CIDR protocol. Cows that displayed estrus (n = 94) were artificially inseminated (Day0; D0). On D19, blood samples were collected to obtain peripheral blood mononuclear cells (PBMC) and measure progesterone (P4) concentrations. On D30, pregnancy diagnosis was performed. The expression of RSAD2 in PBMC of pregnant cows was positively related to the proportion of B. indicus genetics of the groups, but not the expression of ISG15 and OAS1. In pregnant cows, the proportion of B. indicus genetics was negatively associated to circulating levels of P4 concentrations. The P4 concentrations were related positively with RSAD2 expression. ROC curve results determined that for cattle with B. indicus genetics lower than 67%, the CLEC3B and AKR1B1 combination was the most accurate option to predict the outcome of pregnancy. In cows with more than 68% of B. indicus genetics, RSAD2 provided the best accuracy. In conclusion, there is a relationship between the proportion of B. indicus genetics and the ISGs gene expression in PBMC during pregnancy.

MNQ derivative D21 protects against LPS-induced inflammatory damage in bovine ovarian follicular GCs in vitro via the steroid biosynthesis signaling pathway

Bacterial infections of the reproductive system of dairy cows lead to inflammation, and lipopolysaccharide (LPS) of the cell wall of Gram-negative bacteria is the main pathogenic component of inflammation. LPS inhibits follicular growth and development and alters the expression of follicular granulosa cells (GCs) genes in the ovary, leading to their functional disorders. Naphthoquinones have anti-inflammatory effects. In this experiment, 2-methoxy-1,4-naphthoquinone (MNQ), an extract of Impatiens balsamina L, and its derivative D₂₁ were used to eliminate the inflammatory response of GCs exposed to LPS in vitro and to restore functional disorders in GCs. The anti-inflammatory effects of the two compounds were compared and their mechanism of action was investigated. The cytotoxicity of MNQ and its derivative D₂₁ on follicular GCs was determined by MTT method. The relative expression of inflammatory factors and steroid synthesis-related genes were determined by qRT-PCR. The protective effects of MNQ and D₂₁ on cellular inflammatory damage were observed by TEM. ELISA were performed to detect the levels of estradiol (E₂) and progesterone (P₄) in the culture supernatant. The expression of differential genes was analyzed by RNA-seq, and GO and KEGG enrichment analysis of differential genes were performed to investigate the mechanism of anti-inflammatory effect of D₂₁. The results showed that the maximum no-cytotoxic concentrations of MNQ and D₂₁ acting on GCs for 12 h were 4 μM and 64 μM, respectively. LPS concentration of 10 μg/mL had little effect on the survival of follicular GCs, but the relative expressions of IL-6, IL-1β and TNF-α were significantly higher (P < 0.05). The results of qRT-PCR, ELISA and TEM observations showed that the anti-inflammatory effect of D₂₁ was stronger than that of MNQ. RNA-seq analysis revealed a total of 341 differential genes between the LPS vs CK group (Control group) and the D₂₁+L vs LPS group, which were mainly enriched in signaling pathways such as steroid biosynthesis. Nine genes in this signaling pathway were analyzed, and the RNA-seq and qRT-PCR results were found to be basically consistent. In this study, we confirmed that derivative D₂₁ has stronger in vitro anti-inflammatory effects and better efficacy in protecting bovine follicular GCs from inflammatory damage than MNQ and acts through the steroid biosynthesis signaling pathway.

Lipopolysaccharide (LPS) suppresses follicle development marker expression and enhances cytokine expressions, which results in fail to granulosa cell proliferation in developing follicle in cows

Postpartum endometritis is known to be associated with ovarian dysfunction in cows. Lipopolysaccharide (LPS) generated by Gram-negative bacteria is recognized by toll-like receptor 4 (TLR4), which leads to an inflammatory response by the generation of cytokines such as tumor necrosis factor-α (TNF-α) and interleukins. In this study, we investigated the effect of endometrial LPS on granulosa cell functions during early follicular development in cows. Uteri and follicles were obtained from a slaughterhouse and classified into either clinical endometritis (CE) or normal groups by vaginal mucus test. TLR4 mRNA and protein in normal cows were expressed in granulosa cells collected from follicles measuring 1-3 and 4-7 mm in a diameter, respectively. LPS content in endometrium and follicular fluid of CE cows was significantly higher than that in normal cows. Compared to normal cows, CE cows showed lower expression of follicular development markers (FSHR, CYP19A1, CCND2, and LHCGR) in granulosa cells, lower estradiol-17β concentrations in follicular fluid, and lower granulosa cell proliferation. CE contraction significantly increased cytokine expressions (TNF, IL-1A, and IL-1B) in granulosa cells and suppressed apoptosis of granulosa cells compared to normal cows. LPS significantly suppressed the expression of follicular development markers and the production of estradiol-17β in granulosa cells and reduced granulosa cells proliferation compared to cells cultured without LPS. LPS significantly increased cytokine expressions and suppressed granulosa cell apoptosis. Thus, the present results suggest that the existence of LPS in developing follicles is one of the causes of ovarian quiescence in cows.

Protective effects of MNQ against Lipopolysaccharide-induced inflammatory damage in bovine ovarian follicular granulosa cells in Vitro

Inflammation of the reproductive tract in dairy cows lead to functional disorders of follicular granulosa cells (GCs) in mammalian ovaries resulting in infertility and serious losses to the livestock industry. Lipopolysaccharide (LPS) can induce an inflammatory response in follicular granulosa cells in vitro. The aim of this study was to investigate the cellular regulatory mechanism of MNQ (2-methoxy-1,4-naphthoquinone) on eliminating the inflammatory response and restoring normal functions for bovine ovarian follicular GCs cultured in vitro exposed to LPS. The cytotoxicity of MNQ and LPS on GCs were detected by MTT method to determine the safe concentration. The relative expression of inflammatory factors and steroid synthesis-related genes were detected by qRT-PCR. The concentration of steroid hormones in the culture broth were detected by ELISA. Differential gene expressions were analyzed by RNA-seq. There were no toxic effects on GCs at MNQ and LPS concentrations of less than 3 µM and 10 µg/mL, respectively and treated in 12 h. The relative expressions of IL-6, IL-1β and TNF-α were significantly higher in the LPS group compared with the CK group when GCs cultured in vitro were treated with the above concentrations and times (P < 0.05), but significantly lower in the MNQ+LPS group compared with the LPS group (P < 0.05). The levels of E₂ and P₄ in the culture solution were significantly reduced in the LPS group compared to the CK group (P < 0.05), and restored in the MNQ+LPS group. The relative expressions of CYP19A1, CYP11A1, 3β-HSD, and STAR were significantly decreased in the LPS group compared with the CK group (P < 0.05), while the MNQ+LPS group also recovered to some extent. There were 407 differential genes shared by LPS vs CK and MNQ+LPS vs LPS by RNA-seq analysis, which were mainly enriched in steroid biosynthesis and TNF signaling pathway. We screened 10 genes for analysis and found consistent results for RNA-seq and qRT-PCR. In this study, we confirmed the protective effect of MNQ, an extract from Impatiens balsamina L, on LPS-induced inflammatory responses in bovine follicular granulosa cells in vitro as well as functional damage, and acted through steroid biosynthesis and TNF signaling pathways.

Crosstalk between reproductive and immune systems: the teleostean perspective

The bidirectional interaction between the hypothalamic-pituitary-gonadal (HPG) axis and the immune system plays a crucial role in the adaptation of an organism to its environment, its survival and the continuance of a species. Nonetheless, very little is known about this interaction among teleost, the largest group of extant vertebrates. Fishes being seasonal breeders, their immune system is exposed to seasonally changing levels of HPG hormones. On the contrary, the presence and infiltration of leukocytes, the expression of pattern recognition receptors as well as cytokines in gonads suggest their key role in teleostean gametogenesis as in the case of mammals. Moreover, the modulation of gametogenesis and steroidogenesis by lipopolysaccharide implicates the pathological significance of inflammation on reproduction. Thus, it is important to engage in the understanding of the interaction between these two important physiological systems, not only from a phylogenetic perspective but also due to the importance of fish as an important economic resource. In view of this, the authors have reviewed the crosstalk between the reproductive and immune systems in teleosts and tried to explore the importance of this interaction in their survival and reproductive fitness.

Intrauterine LPS inhibited arcuate Kiss1 expression, LH pulses, and ovarian function in rats

In brief

Uterine inflammatory diseases are a major cause of infertility in humans and domestic animals. The current findings that intrauterine lipopolysaccharide is absorbed in systemic circulation and attenuates ovarian cyclic activities could provide a basis for developing novel treatments to improve fertility.

Abstract

Uterine inflammatory diseases are a major cause of infertility in humans and domestic animals. Circulating lipopolysaccharide (LPS), a bacterial endotoxin causing uterine inflammation, reportedly downregulates the hypothalamic-pituitary-gonadal axis to mediate ovarian dysfunction. In contrast, the mechanism whereby intrauterine LPS affects ovarian function has not been fully clarified. This study aimed to elucidate whether uterine exposure to LPS downregulates hypothalamic kisspeptin gene (Kiss1) expression, gonadotropin release, and ovarian function. Uterine inflammation was induced by intrauterine LPS administration to ovary-intact and ovariectomized female rats. As a result, plasma LPS concentrations were substantially higher in control rats until 48 h post injection, and the estrous cyclicity was disrupted with a prolonged diestrous phase. Three days post injection, the number of Graafian follicles and plasma estradiol concentration were reduced in LPS-treated rats, while numbers of Kiss1-expressing cells in the anteroventral periventricular nucleus and arcuate nucleus (ARC) were comparable in ovary-intact rats. Four days post injection, ovulation rate and plasma progesterone levels reduced significantly while gene expression of interleukin1β and tumor necrosis factor α was upregulated in the ovaries of LPS-treated rats that failed to ovulate. Furthermore, the number of Kiss1-expressing cells in the ARC and pulsatile luteinizing hormone (LH) release were significantly reduced in ovariectomized rats 24 h post injection. In conclusion, these results indicate that intrauterine LPS is absorbed in systemic circulation and attenuates ovarian function. This detrimental effect might be caused, at least partly, by the inhibition of ARC Kiss1 expression and LH pulses along with an induction of ovarian inflammatory response.

Lipopolysaccharide alters CEBPβ signaling and reduces estradiol production in bovine granulosa cells

Background

Bacterial infection of the uterus in postpartum dairy cows limits ovarian follicle growth, reduces blood estradiol concentrations, and leads to accumulation of bacterial lipopolysaccharide (LPS) in ovarian follicular fluid. Although treating granulosa cells with LPS in vitro decreases the expression of the estradiol synthesis enzyme CYP19A1 and reduces estradiol secretion, the molecular mechanisms are unclear. The transcription factor CCAAT enhancer binding protein beta (CEBPβ) not only facilitates the transcription of LPS regulated cytokines, but also binds to the promoter region of CYP19A1 in humans, mice, and buffalo. We hypothesized that LPS alters CEBPβ signaling to reduce CYP19A1 expression, resulting in decreased estradiol secretion.

Methods

Bovine granulosa cells were isolated from small/medium or large follicles and treated with LPS in the presence of FSH and androstenedione for up to 24 h.

Results

Treatment with LPS increased CXCL8 and IL6 gene expression and reduced estradiol secretion in granulosa cells from both small/medium and large follicles. However, LPS only reduced CYP19A1 expression in granulosa cells from large follicles. Treatment with LPS increased CEBPB expression and reduced CEBPβ nuclear localization in granulosa cells from small/medium follicles, but not granulosa cells from large follicles.

Conclusions

Although LPS reduces estradiol synthesis in bovine granulosa cells, the effects of LPS on CYP19A1 and CEBPβ are dependent on follicle size.

Resveratrol regulates the inflammation and oxidative stress of granulosa cells in PCOS via targeting TLR2

Polycystic ovary syndrome (PCOS) is featured as a common endocrine disorder in reproductive-aged women, while its pathophysiology is not fully illustrated. This study examined potential actions of resveratrol in PCOS cellular model and explored the underlying interaction between resveratrol and toll-like receptor 2 (TLR2). This study performed the bioinformatics analysis on two microarray datasets (GSE34526 and GSE138518). We found that TLR2 was one of potential hub genes that may be associated with PCOS. Further examination showed that TLR2 was highly expressed in granulosa cells from PCOS group compared with control. The in vitro studies showed that LPS intervention caused an increased expression of TLR2 and the pro-inflammatory mediators, and induced oxidative stress in the granulosa cells, which was concentration-dependently antagonized by resveratrol treatment. TLR2 silence significantly attenuated LPS-induced increase TNF-α, IL-1β, IL-6 and IL-8 expression and oxidative stress of granulosa cells. Furthermore, TLR2 overexpression promoted inflammatory response and oxidative stress in the granulosa cells, which was antagonized by resveratrol treatment. In conclusion, resveratrol could attenuate LPS-induced inflammation and oxidative stress in granulosa cells, and the underlying mechanisms may be related to the inhibitory effect of resveratrol on TLR2 expression in granulosa cells.

Cholesterol supports bovine granulosa cell inflammatory responses to lipopolysaccharide

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

Perspective on the relationship between reproductive tract microbiota eubiosis and dysbiosis and reproductive function

The role played by microbiota is attracting growing attention within the scientific and medical community, in both human and animal fields, in the last years. Most of the studies have been focused on the intestinal microbiome, whilst little attention has been paid to other systems, like the reproductive tract of both females and males. However, there is a growing body of information showing the interplay between reproductive tract dysbiosis, due to the action of pathogens and/or unhealthy lifestyle, and reproductive disease and disorders in many mammalian species. The present review aims to summarise current knowledge on the biodiversity of the microbiota of the reproductive tract, and the possible relationships between eubiosis or dysbiosis and reproductive health and function in both females and males.

Molecular Mechanisms of Lipopolysaccharide (LPS) Induced Inflammation in an Immortalized Ovine Luteal Endothelial Cell Line (OLENDO)

Escherichia coli (E. coli) is the most common Gram-negative bacterium causing infection of the uterus or mammary gland and is one of the major causes of infertility in livestock. In those animals affected by E. coli driven LPS-mediated infections, fertility problems occur in part due to disrupted follicular and luteal functionality. However, the molecular mechanisms by which LPS induces inflammation, and specifically, the role of LPS in the disruption of capillary morphogenesis and endothelial barrier function remain unclear. Here, we hypothesized that LPS may lead to alterations in luteal angiogenesis and vascular function by inducing inflammatory reactions in endothelial cells. Accordingly, OLENDO cells were treated with LPS followed by evaluation of the expression of selected representative proinflammatory cytokines: NF-kB, IL6, IL8, TNFα, and ICAM 1. While TNFα was not affected by treatment with LPS, transcripts of NF-kB, IL6, and IL8 were affected in a dosage-dependent manner. Additionally, the activity of TLR2 and TLR4 was blocked, resulting in suppression of the LPS-induced expression of ICAM 1, NF-kB, IL6, and IL8. Inhibition of the PKA or MAPK/ERK pathways suppressed the LPS-stimulated expression of NF-kB, IL6, and IL8, whereas blocking the PKC pathway had the opposite effect. Furthermore, LPS-induced phosphorylation of Erk1 and Erk2 was inhibited when the TLR4 or MAPK/ERK pathways were blocked. Finally, LPS seems to induce inflammatory processes in OLENDO cells via TLR2 and TLR4, utilizing different signaling pathways.

Effects of lipopolysaccharide on follicular estrogen production and developmental competence in bovine oocytes

Reproductive efficiency and female fertility is essential for productive and sustainable beef cattle operations. Gram-negative bacterial infections cause release of the endotoxin lipopolysaccharide (LPS) which initiates immune responses shown to alter ovarian steroidogenesis and impair oocyte development. The current study was designed to investigate the impact of varying levels of naturally occurring infection and follicular LPS on estradiol (E₂) production and oocyte maturation. Bovine ovary pairs were harvested from a slaughterhouse, and oocytes were aspirated from small follicles and matured in vitro. Meiotic events were evaluated on nuclear maturation and spindle morphology to classify oocytes as normal or abnormal. Follicular fluid LPS concentrations were measured and subsequently separated into Low or High LPS groups. A marked difference was detected between the percent of abnormal oocytes matured from Low LPS follicles, compared to the percent of abnormal oocytes matured from High LPS follicles (P = 0.1). Follicular E₂ concentrations tended to be greater for high LPS follicles (P = 0.1), however, relative abundance of mRNA transcripts for aromatase (P = 0.93) and beta-catenin (P = 0.63) were similar between groups. No changes were detected in Toll-like Receptor 4 (P = 0.15), Myeloid Differentiation Factor-2 (P = 0.61), or cluster of differentiation 14 (P = 0.46) mRNA transcript abundance in follicles with high LPS, compared to low. Therefore, even Low levels of follicular LPS indicating a subacute infection is capable of impacting the ovarian milieu and may represent an unappreciated factor leading to reduced female fertility and decreased cow retention.

The Aryl hydrocarbon receptor mediates reproductive toxicity of polychlorinated biphenyl congener 126 in rats

Polychlorinated biphenyls (PCBs) are endocrine disrupting chemicals with documented, though mechanistically ill-defined, reproductive toxicity. The toxicity of dioxin-like PCBs, such as PCB126, is mediated via the aryl hydrocarbon receptor (AHR) in non-ovarian tissues. The goal of this study was to examine the uterine and ovarian effects of PCB126 and test the hypothesis that the AHR is required for PCB126-induced reproductive toxicity. Female Holzman-Sprague Dawley wild type (n = 14; WT) and Ahr knock out (n = 11; AHR-/-) rats received a single intraperitoneal injection of either corn oil vehicle (5 ml/kg: WT_O and AHR-/-_O) or PCB126 (1.63 mg/kg in corn oil: WT_PCB and AHR-/-_PCB) at four weeks of age. The estrous cycle was synchronized and ovary and uterus were collected 28 days after exposure. In WT rats, PCB126 exposure reduced (P < 0.05) body and ovary weight, uterine gland number, uterine area, progesterone, 17β-estradiol and anti-Müllerian hormone level, secondary and antral follicle and corpora lutea number but follicle stimulating hormone level increased (P < 0.05). In AHR-/- rats, PCB126 exposure increased (P ≤ 0.05) circulating luteinizing hormone level. Ovarian or uterine mRNA abundance of biotransformation, and inflammation genes were altered (P < 0.05) in WT rats due to PCB126 exposure. In AHR-/- rats, the transcriptional effects of PCB126 were restricted to reductions (P < 0.05) in three inflammatory genes. These findings support a functional role for AHR in the female reproductive tract, illustrate AHR's requirement in PCB126-induced reprotoxicity, and highlight the potential risk of dioxin-like compounds on female reproduction.

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.

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.

Effects of Pre-ovulatory Follicular Fluid of Repeat Breeder Dairy Cows on Bovine Fertility Transcriptomic Markers and Oocytes Maturation and Fertilization Capacity

The current study aimed to determine the effects of the preovulatory follicular fluid (FF) of normal heifer (NH) and repeat breeder cows with subclinical endometritis (SCE) or without (nSCE) on oocyte maturation (Experiment 1) and fertilization rates (Experiment 2). Moreover, the pattern of gene expression of cumulus oocyte-complexes was evaluated in Experiment 1. In Experiment 1, nuclear maturation in the nSCE group was higher, compared to that in the SCE group (P = 0.05). In addition, the oocyte nuclear maturation in the normal heifer was significantly higher, in comparison to that of SCE groups (P < 0.05). Furthermore, the mean percentage of normal oocyte fertilization was higher in the nSCE group, compared to that in the SCE group (P < 0.05). The expressions of growth differentiation factor, GDF9; steroidogenic acute regulatory, StAR and follicle-stimulating hormone receptor, FSHr in the NH group were significantly higher, compared to those in SCE and nSCE groups (P < 0.05). Moreover, the expressions of all genes in the nSCE group were not significant, in comparison to those in the SCE group (P > 0.05). The supplementation of oocyte maturation medium with FF from pre-ovulatory follicles of repeat breeder cows resulted in less oocyte maturation and cumulus cell expansion. In conclusion, the lower fertility in RB cows could be ascribed to the lower oocyte maturation rate and less expression of GDF9, StAR, and FSHr in the cumulus-oocyte complexes.

Toll-Like Receptor 4 Inhibits Estradiol Secretion via NF-κB Signaling in Human Granulosa Cells

Toll-like receptor 4 (TLR4) may play a critical role in regulating follicular development. Data are scarce on the role of TLR4 in the follicle. This study investigated the effects of TLR4 on steroidogenesis in human granulosa cells. Immunohistochemical analysis revealed stage-specific expression of TLR4 in the mouse ovarian cycle, and immunofluorescence showed TLR4 expression in the human granulosa-like tumor cell line (KGN). TLR4 agonist lipopolysaccharides (LPS) significantly inhibited follicular development and synthesis of estradiol (E2) in mice. In KGN cells, TLR4 activation significantly inhibited CYP19A1, FSHR and StAR, and TLR4 inhibition reversed these effects. TLR4 activation also inhibited forskolin-induced secretion of E2 by inhibiting CYP19A1, with no effect on progesterone. Further studies showed activation of p38, JNK and NF-κB signaling after TLR4 activation. Subsequent analyses showed that an NF-κB antagonist reversed the inhibitory effects on CYP19A1 expression and E2 secretion. Together, our results suggest that TLR4 activation may suppress CYP19A1 expression and E2 secretion via NF-κB signaling in human granulosa cells, with important implications for the regulation of ovarian pathophysiology.

Effects of LPS on the Secretion of Gonadotrophin Hormones and Expression of Genes in the Hypothalamus-Pituitary-Ovary (HPG) Axis in Laying Yangzhou Geese

Simple Summary

Lipopolysaccharide (LPS), an endotoxin from E. coli, has been proven to impair follicle development and steroidogenesis, secretion of pituitary and hypothalamus reproductive hormones in mammals. However, the effects of LPS on the avian reproductive axis remain elusive. Pathogenic bacterial infection due to the particular mating behavior on the water containing pathogens was reported to decrease the laying rate and cause economic loss in goose production. In this study, we showed that LPS infection disturbed the plasma pituitary gonadotrophin hormone concentrations and the gene expression of the reproductive axis in Yangzhou geese. Notably, for the first time we proved that both the expression of gonadotrophin-releasing hormone (GnRH) and gonadotropin-inhibiting hormone (GnIH), two important reproductive genes from the hypothalamus, were altered after LPS treatment in birds. Our results can explain the decreased laying rate in goose after bacterial infection, and also provide new insights into reproductive dysfunction caused by LPS and the immune challenge in birds.

Abstract

Lipopolysaccharide (LPS) from gram-negative bacteria was found to be involved in the decrease in laying performance in goose flocks with high stocking density during summer months. LPS injection delayed the increase in the laying rate and altered hierarchical follicle morphology. While there is evidence that LPS exerts suppressive effects on goose reproduction, the time course effects of LPS on the hypothalamus-pituitary-ovary (HPG) axis remain elusive. In this study, we investigated the expression of genes in the HPG axis and the plasma gonadotrophin hormone concentrations in breeding geese at 0, 6, 12, 24, and 36 h after intravenous injection with LPS. The results showed that LPS treatment enhanced and suppressed expression of hypothalamic gonadotropin-inhibiting hormone (GnIH) and gonadotrophin-releasing hormone (GnRH) mRNA, respectively, and similar effects were observed on the mRNA expression of their receptors, GnIHR and GnRHR, in the pituitary. LPS treatment transiently increased follicle FSHβ mRNA expression at 12 h and exerted no significant effect on LHβ mRNA expression in the pituitary. Regardless of the expression of FSHβ and LHβ, plasma follicle stimulating hormone (FSH) and luteinizing hormone (LH) concentrations were significantly increased during 24–36 h after LPS treatment. In the ovary, StAR and Cyp11a1 were mainly expressed in the granulosa layer (GL) of hierarchical follicles, while Cyp17a1 and Cyp19a1 were mainly expressed in white follicles (WFs) and yellowish follicles (YFs), and to a lesser extent in the theca layer (TL). After LPS treatment, the mRNA levels of Cyp11a1 in the GLs, Cyp17a1 in the WFs and TL, and Cyp19a1 in the WFs, YFs, and TL were significantly decreased. However, LPS treatment transiently upregulated StAR expression at 12 h. These results indicate that the exposure of laying geese to LPS may impair the HPG axis and disturb ovarian steroidogenesis. Our research provides new insights into reproductive dysfunction caused by LPS and the immune challenge in birds.

Understanding the trade-off between the environment and fertility in cows and ewes

The environment contributes to production diseases that in turn badly affect cow performance, fertility and culling. Oestrus intensity is lower in lame cows, and in all cows 26% potential oestrus events are not expressed (to avoid getting pregnant). To understand these trade-offs, we need to know how animals react to their environment and how the environment influences hypothalamus-pituitary-adrenal axis (HPA) interactions with the hypothalamus-pituitary-ovarian axis (HPO). Neurotransmitters control secretion of GnRH into hypophyseal portal blood. GnRH/LH pulse amplitude and frequency drive oestradiol production, culminating in oestrus behaviour and a precisely-timed GnRH/LH surge, all of which are disrupted by poor environments. Responses to peripheral neuronal agents give clues about mechanisms, but do these drugs alter perception of stimuli, or suppress consequent responses? In vitro studies confirm some neuronal interactions between the HPA and HPO; and immuno-histochemistry clarifies the location and sequence of inter-neurone activity within the brain. In both species, exogenous corticoids, ACTH and/or CRH act at the pituitary (reduce LH release by GnRH), and hypothalamus (lower GnRH pulse frequency and delay surge release). This requires inter-neurones as GnRH cells do not have receptors for HPA compounds. There are two (simultaneous, therefore fail-safe?) pathways for CRH suppression of GnRH release via CRH-Receptors: one being the regulation of kisspeptin/dynorphin and other cell types in the hypothalamus, and the other being the direct contact between CRH and GnRH cell terminals in the median eminence. When we domesticate animals, we must provide the best possible environment otherwise animals trade-off with lower production, less intense oestrus behaviour, and impaired fertility. Avoiding life-time peri-parturient problems by managing persistent lactations in cows may be a worthy trade-off on both welfare and economic terms – better than the camouflage use of drugs/hormones/feed additives/intricate technologies? In the long term, getting animals and environment in a more harmonious balance is the ultimate strategy.

TNFα-Erk1/2 signaling pathway-regulated SerpinE1 and SerpinB2 are involved in lipopolysaccharide-induced porcine granulosa cell proliferation

Lipopolysaccharide (LPS) is an inhibitory factor that causes hormonal imbalance and subsequently affects ovarian function and fertility in mammals. Previous studies have shown that the exposure of granulosa cells (GC) to LPS leads to steroidogenesis dysfunction. However, the effects of LPS on the viability of GC remain largely unclear. In the present study, we aimed to address this question and unveil the underlying molecular mechanisms using cultured porcine GC. Results showed that GC proliferation and tumor necrosis factor α (TNFα) secretion were significantly increased after exposure to LPS, and these effects were completely reversed by blocking the TNFα sheddase, ADAM17. Moreover, GC proliferation induced by LPS was mimicked by treatment with recombinant TNFα. In addition, SerpinE1 and SerpinB2 expression levels increased in GC after treatment with LPS or recombinant TNFα, whereas blocking the Erk1/2 pathway completely abolished these effects and also inhibited GC proliferation. Further, consistent with the effects of blocking the Erk1/2 pathway, cell proliferation was completely inhibited by knocking down SerpinE1 or SerpinB2 in the presence of LPS or recombinant TNFα. Mitochondrial membrane potential (MMP) polarization in GC was increased by LPS or recombinant TNFα treatment, and these changes were completely negated by Erk1/2 inhibition, but not by SerpinE1 or SerpinB2 knockdown. Taken together, these results suggested that the TNFα-mediated upregulation of SerpinE1 and SerpinB2, through activation of the Erk1/2 pathway plays a crucial role in LPS-stimulated GC proliferation, and the increase in GC MMP may synergistically influence this process.

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.

Association among lipopolysaccharide, the transforming growth factor-beta superfamily, follicular growth, and transcription factors in spontaneous bovine ovarian cysts

The aim of this study was to investigate some of the growth and transcriptional factors originating from oocytes and granulosa cells in follicular fluid and to identify the relationships between the basic blood metabolite-metabolic hormones and intrafollicular lipopolysaccharide (LPS) concentrations. Thirty cows included in the study were allocated into 2 groups comprising 15 cows with healthy preovulatory follicles (cyclic cows) and 15 cows with confirmed cystic follicles. The ovaries and uteri of all cows were assessed by transrectal ultrasonographic examination. Blood serum samples were collected at 15, 25, 35, 45, and 55 d after calving for analysis of nonesterified fatty acids, β-hydroxybutyrate, insulin, glucose, IGF-I, ACTH, and cortisol. Ovaries and uteri were examined using transrectal ultrasound. Vaginal discharge was evaluated on the same days. Follicular fluid was also aspirated on days 35-55 from the healthy preovulatory follicles and cystic follicles using a transvaginal ovum pickup method. The densitometric levels of inhibin-α, growth and differentiation factor (GDF-9), bone morphogenetic protein (BMP-6), and GATA-4 and GATA-6 proteins were analyzed by the Western blotting technique; the concentrations of antimullerian hormone (AMH), IGF-I, estradiol-17 beta (E2), and progesterone (P4) were determined by ELISA; and the concentrations of LPS in the follicular fluid were measured by the Limulus amebocyte lysate test. The serum insulin, ACTH, and cortisol concentrations were higher in cystic cows than cyclic cows, but serum IGF-I concentrations were lower in cystic cows. The IGF-I concentrations of cystic follicular fluids were lower, whereas AMH levels were significantly greater than those of healthy preovulatory follicular fluids. The cystic follicles had significantly lower expression levels of GDF-9, BMP-6, GATA-4, and GATA-6; in contrast, inhibin-α expression and LPS concentrations were significantly higher than in healthy preovulatory follicles. The proportion of pathologic vaginal discharge within 25 d postpartum in cystic cows were higher than in the cyclic group. In conclusion, it is suggested that intrafollicular dysregulation of the transforming growth factor-β superfamily, growth, and transcriptional factors is affected by high intrafollicular LPS concentrations and systemic metabolic changes and these disturbances may be responsible for the generation of ovarian cysts.

INSIGHTS ON AROMATASE IMMUNOHISTOCHEMISTRY: VARIATIONS BETWEEN INTRINSIC MOLECULAR SUBTYPES OF BREAST CANCERS

CONTEXT

Aromatase is a key enzyme in local estrogen production by androgen conversion, especially in women post-menopause. There have been controversies concerning aromatase localization in breast carcinomas and its association with current histopathological variables.

MATERIAL AND METHODS

Using polyclonal antibody immunohistochemistry we assessed (by intensity and percentage scores) the immunolocalization of aromatase in 70 tissue samples, and described particularities within the molecular subtypes of breast cancer.

RESULTS

Aromatase was found in all tissue compartments: tumor (95.7%), stroma (58.6%) and adipose tissue (94.3%). Aromatase expression in tumor cells correlated inversely with tumor grading (p=-0.361, p=0.027), and positively with estrogen receptor status (ER, p=0.143, p<0.001). Dividing the study group by intrinsic subtypes, a strongly inversely association between tumor aromatase and grading (p=-0.486, p<0.001), and between stromal aromatase and Ki67-index (p=-0.448, p=0.048) was observed in luminal A breast cancer. Tumor aromatase and ER percentage scores had stronger correlations in luminal B HER2 negative (p=0.632, p=0.002), and positive (p=0.324, p=0.026) tumors. In contrast, in triple negative tumors, a positive association stromal aromatase and Ki67 index (p=-0.359, p=0.007) was observed.

CONCLUSION

Local aromatase was linked to better tumor differentiation and proliferation in luminal breast subtypes, and not in triple negative cases, suggesting a potential prognostic role of aromatase in breast carcinomas.

Inflammatory Stimuli Trigger Increased Androgen Production and Shifts in Gene Expression in Theca-Interstitial Cells

Polycystic ovary syndrome (PCOS) is a common reproductive endocrine disorder characterized by theca cell hyperplasia and excessive androgen production. An increasing body of evidence has pointed to a close association between PCOS and low-grade chronic systemic inflammation. However, the mechanistic basis for this linkage is unknown. Therefore, we evaluated the effects of the inflammatory agents lipopolysaccharide (LPS) and IL-1β on rat theca-interstitial cells (TICs). We found that incubation with either LPS or IL-1β elicited a dose-dependent increase in both TIC viability and androgen production. Using RNA sequencing analysis, we found that both of these inflammatory agents also triggered profound and widespread shifts in gene expression. Using a stringent statistical cutoff, LPS and IL-1β elicited differential expression of 5201 and 5953 genes, respectively. Among the genes upregulated by both LPS and IL-1β were key regulatory genes involved in the cholesterol and androgen biosynthesis pathways, including Cyp17a1, Cyp11a1, Hsd3b, and Hmgcr. This provides a molecular explanation for the mechanism of action of inflammatory agents leading to increased androgen production. Gene ontology and pathway analysis revealed that both LPS and IL-1β regulated genes highly enriched for many common functions, including the immune response and apoptosis. However, a large number of genes (n = 2222) were also uniquely regulated by LPS and IL-1β, indicating that these inflammatory mediators have substantial differences in their mechanism of action. Together, these findings highlight the potential molecular mechanisms through which chronic low-grade inflammation contributes to the pathogenesis of androgen excess in PCOS.

Intrafollicular lipopolysaccharide injection delays ovulation in cows

The aim of this study was to evaluate effects of intra-follicular (i.f.) treatment with lipopolysaccharide (LPS) on follicular and luteal development in cows. There were 18 non-lactating cows assigned to two groups to address this aim: control group (n = 9), which received an i.f. injection of saline; and LPS group (n = 9), which received an i.f. injection of 1 μg of LPS per mL of follicular fluid. Cows were treated with an intravaginal P4 releasing device (IVD) and estradiol benzoate on D0. On D4 and D5 cows were treated with cloprostenol sodium and on D7 the IVD was removed. At 12 h after IVD removal, cows were administered the i.f. injection of LPS or saline. After administration of these treatments, follicular development was evaluated every 12 h until ovulation. The LPS treatment increased blood flow in pre-ovulatory follicles (P = 0.05). Follicle growth was reduced by LPS injection (P < 0.02) resulting a longer period to the time of ovulation for cows in the LPS than control group (P = 0.03). The percentage of cows having ovulations was less for the LPS than control group (P = 0.03). The diameter of the CL, CL blood flow and P4 concentrations 5 and 12 days after ovulation did not differ between groups (P> 0.05). In conclusion, intra-follicular treatment with LPS resulted in a decreased rate of follicle growth, delayed timing of ovulations and a lesser number of cows having ovulations.

Lipopolysaccharide and tumor necrosis factor-alpha alter gene expression of oocytes and cumulus cells during bovine in vitro maturation

Communication between the oocyte and cumulus facilitates oocyte growth, cell cycle regulation, and metabolism. This communication is mediated by direct contact between oocytes and cumulus cells, and soluble secreted molecules. Secreted molecules involved in this process are known inflammatory mediators. Lipopolysaccharide (LPS) is detected in follicular fluid and is associated with reduced fertility, whereas accumulation of inflammatory mediators in follicular fluid, including tumor necrosis factor-α (TNF-α), is associated with female infertility. Maturation of oocytes in the presence of LPS or TNF-α reduces meiotic maturation and the capacity to develop to the blastocyst. Here we evaluated the abundance of 92 candidate genes involved immune function, epigenetic modifications, embryo development, oocyte secreted factors, apoptosis, cell cycle, and cell signaling in bovine cumulus cells or zona-free oocytes after exposure to LPS or TNF-α during in vitro maturation. We hypothesize that LPS or TNF-α will alter the abundance of transcripts in oocytes and cumulus cell in a cell type dependent manner. Exposure to LPS altered abundance of 31 transcripts in oocytes (including ACVR1V, BMP15, DNMT3A) and 12 transcripts in cumulus cells (including AREG, FGF4, PIK3IP1). Exposure to TNF-α altered 1 transcript in oocytes (IGF2) and 4 transcripts in cumulus cells (GJA1, PLD2, PTGER4, STAT1). Cumulus expansion was reduced after exposure to LPS or TNF-α. Exposing COCs to LPS had a marked effect on expression of targeted transcripts in oocytes. We propose that altered oocyte transcript abundance is associated with reduced meiotic maturation and embryo development observed in oocytes cultured in LPS or TNF-α.

CFTR and FOXO1 gene expression are reduced and high mobility group box 1 (HMGB1) is increased in the ovaries and serum of women with polycystic ovarian syndrome

We previously described increased HMGB1 and reduced FOXO1 dependent on CFTR loss of function in cystic fibrosis (CF) and we showed in vitro that HMGB1 was lowered by insulin. Reduced CFTR gene expression has been described in granulosa cells (GC) from PCOS-induced rats. We aimed at studying CFTR and FOXO1 gene expression in GC, HMGB1 concentrations in serum and follicular fluids (FF), and insulin and IL-6 in FF in PCOS women. Thirty PCOS and 36 non-PCOS women (CTRL) undergoing in vitro fertilization were enrolled. CFTR and FOXO1 gene expression were downregulated in PCOS (p ≤ .05). HMGB1 was higher in PCOS both in FF (p ≤ .05) and in serum (p < .005) whereas insulin was lower, and IL-6 was unchanged with respect to controls. 17-β estradiol was higher in PCOS than in CTRL (p ≤ .005). HMGB1 correlated negatively with insulin in FF (p ≤ .005). The increase in HMGB1 both in FF and in serum, likely reflects both low grade inflammation and insulin sensitivity. IL-6 was unchanged possibly reflecting functions other than inflammation.

Toll-like receptors and high mobility group box 1 in granulosa cells during bovine follicle maturation

Toll-like receptors (TLRs) are present in the ovaries and reproductive tract of various mammals. The biological function of TLR during ovulation is one of the main contents in the research of reproductive immunology. In this study, we found that messenger RNA levels of TLR1-TLR10 in granulosa cells were different, and TLRs and high mobility group box 1 (HMGB1) in granulosa cells of large follicles were significantly higher than those of small and middle follicles. Coimmunoprecipitation results showed that HMGB1 interacts with TLR2 in granulosa cells, especially large follicles. The result of immunohistochemistry showed that TLRs and HMGB1 were present in granulosa cell layer of ovarian follicles. We also found 25 mIU/ml follicle-stimulating hormone (FSH) significantly upregulated the expression of TLRs and HMGB1. These results suggest that TLR2/4 and HMGB1 in granulosa cells may be involved in the ovarian innate immune and ovarian follicular maturation, regulated by FSH. However, further research of the function and mechanisms of TLRs and HMGB1 in granulosa cells are needed.

Role of endoplasmic reticulum stress in lipopolysaccharide-inhibited mouse granulosa cell estradiol production

The decrease in the level of estradiol (E₂) in granulosa cells caused by lipopolysaccharide (LPS) is one of the major causes of infertility underlying postpartum uterine infections; the precise molecular mechanism of which remains elusive. This study investigated the role of endoplasmic reticulum (ER) stress in LPS-induced E₂ decrease in mouse granulosa cells. Our results showed that LPS increased the pro-inflammatory cytokines [(interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor (TNF)-α)], activated ER stress marker protein expression [(glucose-regulated protein 78 (GRP78) and CCAAT/enhancer-binding protein homologous protein (CHOP)], and decreased cytochrome P450 family 19 subfamily A member 1 (Cyp19a1) expression and E₂ production. Moreover, inhibition of ER stress by 4-phenylbutyrate (4-PBA) attenuated thapsigargin-(TG, ER stress agonist) or LPS-induced reduction of Cyp19a1 and E₂, pro-inflammatory cytokines expression (IL-1β, IL-6, IL-8, and TNF-α), and the expression of CHOP and GRP78. Additionally, inhibition of toll-like receptor 4 (TLR4) by resatorvid (TAK-242) reversed the inhibitory effects of LPS on Cyp19a1 expression and E₂ production, activation of GRP78 and CHOP, and expression of IL-1β, IL-6, IL-8, and TNF-α. In summary, our study suggests that ER stress is involved in LPS-inhibited E₂ production in mouse granulosa cells.

Inhibition of indoleamine 2,3-dioxygenase attenuates endotoxin-mediated tolerance in granulosa cells through kynurenine pathway

Ovarian granulosa cells (GCs) have been shown to have innate immune capabilities, which modulate their native endocrine functions through toll-like receptors (TLRs). We have recently shown that GCs exposed to lipopolysaccharide (LPS; 1.0 µg/mL) transiently regulate proinflammatory cytokine expression (interleukin 1β [IL-1β], IL-6, and tumor necrosis factor α) through chromatin remodeling. In the present study, we have demonstrated that GCs become tolerant to LPS on repeated exposure of LPS. To understand the mechanism of this endotoxin tolerance (ET) phenomenon in buffalo GCs, we have further studied the genome-wide transcriptomic analyses in buffalo GCs (unpublished data) and identified indoleamine 2,3-dioxygenase 1 (IDO1) gene, known to be involved in tryptophan catabolism, was found to be highly upregulated in endotoxin-tolerant GCs. Real-time gene expression analyses also showed similar results. Further analyses of tryptophan and tryptophan metabolite, kynurenine, showed that tryptophan was found to be depleted with the accumulation of kynurenine in the endotoxin-tolerant GCs. The effect of IDO1 induced ET was reversed when cells were pretreated with IDO1 inhibitor (1-methyl tryptophan, 1 mM). To the best of our knowledge, this is the first report describing the role of IDO1 gene in ET in GCs mimicked by repeated endotoxin exposure in vitro. In summary, the present study convincingly demonstrated that the tryptophan catabolism, through the kynurenine pathway, plays a crucial role as an immunomodulatory mechanism of ET in GCs. The finding could be exploited in developing potential therapeutics to treat impaired GCs function due to the ET underlying prolonged uterine or systemic infection leads to accumulation of endotoxin in follicular fluid.

Lipopolysaccharide disrupts gap junctional intercellular communication in an immortalized ovine luteal endothelial cell line

Gram-negative bacteria, in particular Escherichia coli with its cell wall lipopolysaccharide (LPS), often cause metritis and mastitis in domestic animals. Ovarian LPS accumulation may initiate local inflammatory reactions mediated through cell surface Toll-like receptors (TLRs). This may disrupt ovarian functionality leading to infertility. Possible adverse effects of LPS on luteal activity are not yet well explored. We hypothesized that LPS could lead to alterations in luteal vascular functionality. Therefore, we established an in vitro cell line model (OLENDO) by immortalizing microvascular endothelial cells isolated from ovine corpus luteum (CL) with a potent Simian Virus 40 T-antigen (SV40-Tag). OLENDO exhibit endothelial cell characteristics, like low-density lipoprotein (LDL) uptake, express BSL-I, and VEGFR2, as well as TLR2 and TLR4 receptors. LPS-treatment of OLENDO altered in vitro tube formation, had no effects on cell viability and decreased gap junctional intercellular communication (GJIC). LPS did not impair GJA1/Cx43 protein expression, but altered its cellular localization showing signs of internalization. Taken together, we demonstrated the mechanisms underlying LPS induced impairment of luteal GJIC and immune processes in a novel and well-characterized OLENDO cell line.

Symposium review: Mechanisms of disruption of fertility by infectious diseases of the reproductive tract

Diseases of postpartum dairy cows impair reproductive processes, resulting in prolonged anestrus, reduced conception, and increased pregnancy attrition, regardless of whether the initial disease precedes insemination (even by many weeks), occurs close to insemination, or follows fertilization. Bacteria and their products activate pattern recognition receptors that respond to pathogen-associated molecular patterns (PAMP). These receptors include toll-like receptors (TLR), nucleotide-binding oligomerization domain (NOD)-like receptors and others, and their activation culminates in upregulation of proinflammatory cytokines such as IL-1β, IL-18, and tumor necrosis factor-α. These may have direct effects on the uterus and conceptus. Importantly, however, these inflammatory mediators, as well as the bacterial products, make their way to the ovary via the general circulation (even from distant sites) or possibly by using the countercurrent vascular mechanism that normally transports endometrial prostaglandin to the ipsilateral ovary. Endotoxin reaches concentrations in follicular fluid that exceed those found in the circulation or even in the infected uterus. Ovarian follicular cells also express TLR and can respond directly to bacterial products including endotoxin, impairing their function. Inflammation is accompanied by increased oxidative stress. The process of oocyte development from activation of primordial oocytes to potential ovulation spans 4 mo. Competence by an oocyte encompasses the ability to undergo not only fertilization but also a complex cytoplasmic maturation that lays the foundation for completion of meiosis at the appropriate time, the transition to mitosis in the zygote, and further development of the conceptus. Oocyte maturation relies on intimate association between cumulus cells and the oocyte, characterized by gap junctions through which molecules of various sizes pass. Signaling also occurs in the oocyte-to-cumulus cell direction. Because both granulosa and theca interna cells are capable of responding to inflammatory mediators, with observed alterations in some functions, it seems likely that disturbed ovarian follicular function may contribute to failure of oocytes to become fully competent, even if the insult occurs well before ovulation. Therefore, interruption of normal fertility by uterine infections may be mediated at the level of the uterine environment but the effect on the ovary and oocyte is likely to be even more important.

Impact of heat stress during the follicular phase on porcine ovarian steroidogenic and phosphatidylinositol-3 signaling

Environmental conditions that impede heat dissipation and increase body temperature cause heat stress (HS). The study objective was to evaluate impacts of HS on the follicular phase of the estrous cycle. Postpubertal gilts (126.0 ± 21.6 kg) were orally administered altrenogest to synchronize estrus, and subjected to either 5 d of thermal-neutral (TN; 20.3 ± 0.5 °C; n = 6) or cyclical HS (25.4 - 31.9 °C; n = 6) conditions during the follicular phase preceding behavioral estrus. On d 5, blood samples were obtained, gilts were euthanized, and ovaries collected. Fluid from dominant follicles was aspirated and ovarian protein homogenates prepared for protein abundance analysis. HS decreased feed intake (22%; P = 0.03) and while plasma insulin levels did not differ, the insulin:feed intake ratio was increased 3-fold by HS (P = 0.02). Insulin receptor protein abundance was increased (29%; P < 0.01), but insulin receptor substrate 1, total and phosphorylated protein kinase B, superoxide dismutase 1, and acyloxyacyl hydrolase protein abundance were unaffected by HS (P > 0.05). Plasma and follicular fluid 17β-estradiol, progesterone, and lipopolysaccharide-binding protein concentrations as well as abundance of steroid acute regulatory protein, cytochrome P450 19A1, and multidrug resistance-associated protein 1 were not affected by HS (P > 0.05). HS increased estrogen sulfotransferase protein abundance (44%; P = 0.02), toll-like receptor 4 (36%; P = 0.05), and phosphorylated REL-associated protein (31%; P = 0.02). Regardless of treatment, toll-like receptor 4 protein was localized to mural granulosa cells in the porcine ovary. In conclusion, HS altered ovarian signaling in postpubertal gilts during their follicular phase in ways that likely contributes to seasonal infertility.

Tolerance and Innate Immunity Shape the Development of Postpartum Uterine Disease and the Impact of Endometritis in Dairy Cattle

Bacteria are ubiquitous in the bovine uterus after parturition, but 50 years ago, cows tolerated these bacteria and few animals developed uterine disease. Now, up to 40% of dairy cattle develop postpartum uterine disease. Uterine disease causes infertility by compromising the function of not only the endometrium but also the ovary. Animals defend themselves against pathogens using tolerance and resistance mechanisms. Tolerance is the ability to limit the disease severity induced by a given pathogen burden. Resistance is the ability to limit the pathogen burden and is usually the function of immunity. Endometrial cells contribute to tolerance and have roles in innate immunity and the inflammatory response to pathogens. However, failures in endometrial tolerance and the character of the inflammatory response shape postpartum uterine disease. We propose that uterine health is more dependent on the ability of the endometrium to tolerate pathogens than the ability to resist invading bacteria.

Plasma metabolomic profiles differ at the time of artificial insemination based on pregnancy outcome, in Bos taurus beef heifers

Infertility remains the most prevalent reason for cattle being removed from production environments. We utilized metabolomic profiling to identify metabolites in the blood plasma that may be useful in identifying infertile heifers at the time of artificial insemination (AI). Prior to AI, phenotypic parameters including body condition, weight, and reproductive organ measurements were collected. These were determined not effective at differentiating between fertile and infertile heifers. Analysis of the resulting metabolomic profiles revealed 15 metabolites at significantly different levels (T-test P ≤ 0.05), with seven metabolites having a greater than 2-fold difference (T-test P ≤ 0.05, fold change ≥2, ROC-AUC ≥ 0.80) between infertile and fertile heifers. We further characterized the utility of using the levels of these metabolites in the blood plasma to discriminate between fertile and infertile heifers. Finally, we investigated the potential role inflammation may play by comparing the expression of inflammatory cytokines in the white blood cells of infertile heifers to that of fertile heifers. We found significantly higher expression in infertile heifers of the proinflammatory markers tumor necrosis factor alpha (TNFα), interleukin 6 (IL6), and the C-X-C motif chemokine 5 (CXCL5). Our work offers potentially valuable information regarding the diagnosis of fertility problems in heifers undergoing AI.

Age-related changes in the bovine corpus luteum function and progesterone secretion

Decreased fertility associated with maternal ageing is a well-known critical problem, and progesterone (P4) concentration decreases during the menopause transition in women. The corpus luteum (CL) secretes P4, thereby supporting the implantation and maintenance of pregnancy. It is proposed that a bovine model is suitable for studying age-associated decline of fertility in women because the physiology of cows is similar to that of women and cows have a greater longevity compared with other animal models. Thus, we investigated the age-dependent qualitative changes and inflammatory responses in the bovine CL. In vivo experiment: Cows were divided into three groups, namely, young (mean age: 34.8 months), middle (80.1 months) and aged (188.9 months). Blood samples were collected on days 7 and 12 during the estrous cycle. In vitro experiments: Cows were divided into young (mean age: 27.6 months) and aged (183.1 months). The CL tissues of these groups were collected from a local slaughterhouse and used for tissue culture experiments. An in vivo experiment, plasma P4 concentration in aged cows was significantly lower than that in young cows, whereas no difference was found regarding the area of CL. An in vitro examination in the bovine CL tissues showed that the luteal P4 concentration, P4 secretion, and mRNA expression of StAR and 3β-HSD were lower in aged cows compared with young cows, especially in the early luteal phase. However, no differences were detected in the mRNA expression of inflammation- and senescence-related factors and inflammatory responses to lipopolysaccharides between the CL tissues from young and aged cows, indicating that an age-dependent increase in inflammation is not involved in the luteal function. P4 production and secretion from the bovine CL diminish in old cows, especially during the early luteal phase, suggesting that senescence may affect the luteal function in cows.

Antimicrobial peptide expression in swine granulosa cells in response to lipopolysaccharide

Antimicrobial peptides (AMP) are host defense peptides present in all species examined. The objective of the current study was to characterize the expression of a group of antimicrobial peptides in ovarian cells, and to investigate their expression response to pathogen ligands. It was found that while PG1 transcript was not detected in the ovary, the expression of BD2 is the highest in small follicle derived granulosa cells (SGC), and its expression decreases during follicular development to large follicle stage (LGC; p < 0.05). The expression of BD2 in cumulus cells also decreased from GV to MII stage of oocyte maturation. ANG4 expression increased in granulosa cells during follicular development from SGC to LGC stage (p < 0.05), although no significant difference was observed in cumulus cells from different stages of oocyte maturation. We further examined AMP expression in follicle cells treated with different toll-like receptor (TLR) ligands which mimic pathogen exposure in the ovary. Of the four TLR ligands examined, lipopolysaccharide (LPS) exposure resulted in a 11.5 fold increase of BD2 expression, and a significant decrease of LYZ in LGC. A similar response pattern in BD2 and LYZ expression was also observed in SGC. These responses of AMP expression to LPS are associated with increased TLR4 signaling pathway component in mRNA and protein level, such as MyD88 and NFkB, and pro-inflammatory cytokines/chemokines, such as IL-6, TNFα and IL-8 (p < 0.05). Our data suggest that AMPs may play a role in innate defense as well as other physiological functions during ovarian follicular development and oocyte maturation.

Influence of follicular fluid and cumulus cells on oocyte quality: clinical implications

An equilibrium needs to be established by the cellular and acellular components of the ovarian follicle if developmental competence is to be acquired by the oocyte. Both cumulus cells (CCs) and follicular fluid (FF) are critical determinants for oocyte quality. Understanding how CCs and FF influence oocyte quality in the presence of deleterious systemic or pelvic conditions may impact clinical decisions in the course of managing infertility. Given that the functional integrities of FF and CCs are susceptible to concurrent pathological conditions, it is important to understand how pathophysiological factors influence natural fertility and the outcomes of pregnancy arising from the use of assisted reproduction technologies (ARTs). Accordingly, this review discusses the roles of CCs and FF in ensuring oocyte competence and present new insights on pathological conditions that may interfere with oocyte quality by altering the intrafollicular environment.

Disruption of female reproductive function by endotoxins

Endotoxemia can be caused by obesity, environmental chemical exposure, abiotic stressors and bacterial infection. Circumstances that deleteriously impact intestinal barrier integrity can induce endotoxemia, and controlled experiments have identified negative impacts of lipopolysaccharide (LPS; an endotoxin mimetic) on folliculogenesis, puberty onset, estrus behavior, ovulation, meiotic competence, luteal function and ovarian steroidogenesis. In addition, neonatal LPS exposures have transgenerational female reproductive impacts, raising concern about early life contacts to this endogenous reproductive toxicant. Aims of this review are to identify physiological stressors causing endotoxemia, to highlight potential mechanism(s) by which LPS compromises female reproduction and identify knowledge gaps regarding how acute and/or metabolic endotoxemia influence(s) female reproduction.

Transcriptome analysis of ovine granulosa cells reveals differences between small antral follicles collected during the follicular and luteal phases

Ovarian follicular growth occurs in both the follicular and luteal phases of the estrous cycle but in very different endocrine contexts. In both phases, many small antral follicles with similar morphologic and histologic characteristics are present within the ovaries as a reserve for the terminal folliculogenesis. However, there are several gaps in our molecular knowledge of the gene expression profiles of small antral follicles in the follicular and luteal phases. The aim of the present study was to use RNA sequencing to compare and analyze the global transcriptional profile of ovine granulosa cells collected from small antral follicles (1-3 mm) either during the follicular or the luteal phase of the estrous cycle, with the hypothesis that they should be differential. We identified 663 genes whose mRNA was differentially expressed or accumulated in the granulosa cell layer of small antral follicles in the two phases. A comprehensive interpretation of these data was performed through integrative analyses (Gene Ontology, Ingenuity Pathway Analysis) and the exploitation of already available transcriptomic data on follicular growth and atresia. In particular, we observed that the contrasted endocrine context between follicular and luteal phases may have an impact on estradiol, follicle-stimulating hormone (FSH), and on the activin/inhibin signaling pathways. Furthermore, we reveal the possible initiation of early follicular atresia in small antral follicles during the follicular phase in interaction with the presence of immune cells. This study provides new insights into the gene expression profile in ovine granulosa cells, and we suggest that these molecular changes may have an implication at the time of follicle selection.

Human granulosa-luteal cells initiate an innate immune response to pathogen-associated molecules

The microenvironment of the ovarian follicle is key to the developmental success of the oocyte. Minor changes within the follicular microenvironment can significantly disrupt oocyte development, compromising the formation of competent embryos and reducing fertility. Previously described as a sterile environment, the ovarian follicle of women has been shown to contain colonizing bacterial strains, whereas in domestic species, pathogen-associated molecules are concentrated in the follicular fluid of animals with uterine infection. The aim of this study is to determine whether human granulosa-luteal cells mount an innate immune response to pathogen-associated molecules, potentially disrupting the microenvironment of the ovarian follicle. Human granulosa-luteal cells were collected from patients undergoing assisted reproduction. Cells were cultured in the presence of pathogen-associated molecules (LPS, FSL-1 and Pam3CSK4) for 24h. Supernatants and total RNA were collected for assessment by PCR and ELISA. Granulosa-luteal cells were shown to express the molecular machinery required to respond to a range of pathogen-associated molecules. Expression of TLR4 varied up to 15-fold between individual patients. Granulosa-luteal cells increased the expression of the inflammatory mediators IL1B, IL6 and CXCL8 in the presence of the TLR4 agonist E. coli LPS. Similarly, the TLR2/6 ligand, FSL-1, increased the expression of IL6 and CXCL8. Although no detectable changes in CYP19A1 or STAR expression were observed in granulosa-luteal cells following challenge, a significant reduction in progesterone secretion was measured after treatment with FSL-1. These findings demonstrate the ability of human granulosa-luteal cells to respond to pathogen-associated molecules and generate an innate immune response.

Evaluating lipopolysaccharide-induced oxidative stress in bovine granulosa cells

PURPOSE

The purpose of this study was to evaluate the capacity of bovine granulosa cells to generate reactive oxygen intermediates in response to lipopolysaccharide. We hypothesized that granulosa cells increase reactive oxygen intermediates in response to Gram-negative lipopolysaccharide in a similar manner to immune cells.

METHODS

Bovine peripheral blood mononuclear cells and granulosa cells were cultured in the presence of lipopolysaccharide. Oxidative stress was evaluated using the fluorescent marker dye CellROX, and oxidative stress-related genes were measured using real-time RT-PCR.

RESULTS

As expected, peripheral blood mononuclear cells increased oxidative stress in response to lipopolysaccharide as measured by accumulation of the fluorescent marker dye CellROX. While granulosa cells demonstrate the capacity to increase accumulation of CellROX dye in response to a positive control menadione, lipopolysaccharide had no effect on accumulation of CellROX dye. The expression of GSR, SOD1, and SOD2 were variable in peripheral blood mononuclear cells treated with lipopolysaccharide but were consistently upregulated when co-incubated with the antioxidant, N-acetyl cysteine. The expression of oxidative stress-related genes was not altered in granulosa cells, with the exception of elevated SOD1 following lipopolysaccharide exposure in the absence of antioxidant.

CONCLUSIONS

Combined, these data suggest that while reactive stress is important in pathogen killing and inflammation in immune cells, granulosa cells do not increase oxidative stress in response to lipopolysaccharide.

Time course effect of lipopolysaccharide on Toll-like receptors expression and steroidogenesis in the Chinese goose ovary

The ovary of Chinese goose is easily infected by microorganisms because of the mating behaviour in water, which causes decreased laying performance. This study investigated the time course effect of lipopolysaccharide (LPS) on the steroidogenesis and mRNA expression of Toll-like receptors (TLRs), a class of key pattern recognition receptor, in the breeding goose ovary. The laying geese were treated intravenously with LPS for 0, 6, 12, 24 and 36 h, and all birds were slaughtered approximately 8 h after oviposition. The expression levels of TLRs in the white and yellowish follicles, and granulosa and theca layers of hierarchical follicles were examined by real-time PCR. All 10 members of avian TLR family were differentially expressed among the different follicular tissues. Moreover, at 24 and 36 h after LPS treatment, the hierarchical follicle morphological structure was altered, but the expression levels of TLRs were still higher than the control. Furthermore, during LPS treatment period, the expression pattern of TLRs 2A and 4 genes was similar to that of TLR15 in the white follicles, TLRs 1B, 5 and 15 in the yellowish follicles, TLRs 7 and 15 in the granulosa layer, and TLRs 1A, 2B, 3, 7 and 15 in the theca layer, which had a negative correlation with the kinetics of plasma P4 and E2 concentrations. In conclusion, the mechanism by which pathogen infection inhibited goose follicular growth and further decreased egg production may involve a gradually enhanced inflammatory response and reduced endocrine function. This may be due to stimulated TLRs in the ovary.