Lipopolysaccharide-induced mechanisms of ovarian dysfunction in cows with uterine inflammatory diseases

Rescuing fertility: Itaconic acid prevents ovarian damage through NRF2-mediated pyroptosis pathways in diminished ovarian reserve models

BACKGROUND

Diminished ovarian reserve (DOR) is a major cause of infertility, often triggered by inflammation and oxidative stress. Pyroptosis, a form of programmed cell death, has been implicated in DOR pathogenesis. Itaconic acid (IA), an endogenous metabolite, is known for its anti-inflammatory and antioxidant properties. This study aimed to explore whether IA could alleviate lipopolysaccharide (LPS)-induced DOR in mice by inhibiting pyroptosis through the NRF2 pathway.

METHODS

A DOR mouse model was established by administering LPS for 5 consecutive days, followed by IA treatment. Ovarian function was assessed by follicle count and hormone levels. Inflammatory markers, oxidative stress, and pyroptosis-related proteins were evaluated in both in vivo and in vitro models. The molecular mechanism was further investigated using inhibitors and molecular docking studies.

RESULTS

IA significantly improved ovarian function in LPS-induced DOR mice by increasing the number of follicles and normalizing hormone levels. IA also reduced inflammation, oxidative stress, and pyroptosis, as evidenced by lower expression of NLRP3, cleaved-caspase-1, and N-GSDMD, while increasing NRF2 expression. In vitro, IA enhanced granulosa cell (GC) viability, reduced reactive oxygen species (ROS), and decreased pyroptosis in LPS-treated GCs. Additionally, the beneficial effects of IA were mediated via the NRF2 pathway, as NRF2 inhibition (ML385) reversed these improvements. Additionally, we identified GSDMD as a downstream target of IA, with inhibition of GSDMD ameliorating DOR progression and inflammatory responses.

CONCLUSION

IA alleviates LPS-induced DOR by reducing inflammation, oxidative stress, and pyroptosis through activation of the NRF2 signaling and direct inhibition of the GSDMD pathway. These findings suggest that IA may serve as a potential therapeutic agent for improving ovarian reserve and fertility.

Nicotinamide Mononucleotide Restores NAD+ Levels to Alleviate LPS-Induced Inflammation via the TLR4/NF-κB/MAPK Signaling Pathway in Mice Granulosa Cells

Inflammation disrupts the normal function of granulosa cells (GCs), which leads to ovarian dysfunction and fertility decline. Inflammatory conditions such as polycystic ovary syndrome (PCOS), primary ovarian insufficiency (POI), endometriosis, and age-related ovarian decline are often associated with chronic low-grade inflammation. Nicotinamide mononucleotide (NMN) is an important precursor of NAD+ and has gained attention for its potential to modulate cellular metabolism, redox homeostasis, and mitigate inflammation. This study investigated the protective roles of NMN against lipopolysaccharide LPS-mediated inflammation in GCs. The results of this experiment demonstrated that LPS had negative effects on GCs in term of reduced viability and proliferation rates and upregulated the production of pro-inflammatory cytokines, including interleukin-1 beta (IL-1β), interleukin-6 (IL-6), cyclooxygenase-2 (Cox-2), and tumor necrosis factor-alpha (TNF-α). Notably, the levels of NAD+ and NAD+/NADH ratio in GCs were reduced in response to inflammation. On the other hand, NMN supplementation restored the NAD+ levels and the NAD+/NADH ratio in GCs and significantly reduced the expression of pro-inflammatory markers at both mRNA and protein levels. It also enhanced cell viability and proliferation rates of GCs. Furthermore, NMN also reduced apoptosis rates in GCs by downregulating pro-apoptotic markers, including Caspase-3, Caspase-9, and Bax while upregulating anti-apoptotic marker Bcl-2. NMN supplementation significantly reduced reactive oxygen species ROS and improved steroidogenesis activity by restoring the estradiol (E2) and progesterone (P4) levels in LPS-treated GCs. Mechanistically, this study found that NMN suppressed the activation of the TLR4/NF-κB/MAPK signaling pathways in GCs, which regulates inflammatory processes. In conclusion, the findings of this study revealed that NMN has the potential to reduce LPS-mediated inflammatory changes in GCs by modulating NAD+ metabolism and inflammatory signaling pathways. NMN supplementation can be used as a potential therapeutic agent for ovarian inflammation and related fertility disorders.

In Vitro Analysis of LPS-Induced miRNA Differences in Bovine Endometrial Cells and Study of Related Pathways

Lipopolysaccharide (LPS) is one of the main factors inducing endometritis in dairy cows. However, the specific pathogenesis of LPS-induced endometritis in dairy cows is not fully understood. The objective of this study was to establish an in vitro endometritis model using LPS-induced bovine endometrial epithelial (BEND) cells. BEND cells were treated with LPS of different concentrations and times. The cell-counting kit-8 (CCK-8) was used to detect the cell survival rate after LPS treatment, and quantitative real-time PCR (RT-qPCR) was used to detect the expression of control group and LPS-treated group of inflammatory factors interleukin-1 beta (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor-alpha (TNF-α). The results showed that the survival rate of endometrial epithelial cells stimulated by 5 μg/mL LPS for 6 h was 75.13%, and the expression of inflammatory factors was significantly increased. Therefore, 5 μg/mL LPS for 6 h could be selected as a suitable model for the study of inflammation. In addition, miRNA sequencing and target gene prediction was performed on normal and LPS-treated BEND cells. Among twenty-one differentially expressed miRNAs, six miRNAs were selected and their expression levels were detected by RT-qPCR, which were consistent with the sequencing results. Twenty-one differentially expressed miRNAs collectively predicted 17,050 target genes. This study provides a theoretical basis for further investigation of the pathogenesis of endometritis.

Potential mechanisms and therapeutic strategies for LPS-associated female fertility decline

As a major component of the outer membrane of Gram-negative bacteria, lipopolysaccharide (LPS) can be recognized by toll-like receptors (TLRs) and induce inflammation through MyD88 or the TIR domain-containing adapter-inducing interferon-β (TRIF) pathway. Previous studies have found that LPS-associated inflammatory/immune challenges were associated with ovarian dysfunction and reduced female fertility. However, the etiology and pathogenesis of female fertility decline associated with LPS are currently complex and multifaceted. In this review, PubMed was used to search for references on LPS and fertility decline so as to elucidate the potential mechanisms of LPS-associated female fertility decline and summarize therapeutic strategies that may improve LPS-associated fertility decline.

The presence of Leptospira spp. in the follicular fluid of naturally infected cows affects the overall efficiency of the in vitro embryo production technique

The relationship between Leptospira infection and reproductive failures, as well as the mechanisms that lead to it, has not yet been fully established. It has been hypothesized that the presence of Leptospira spp. in the follicular fluid (FF) could impair the oocyte developmental competence. Thus, the impact of the presence of Leptospira spp. in the FF on in vitro embryo production (IVEP) outcomes was assessed. Dairy cows (n=244) from different farms were subjected to ovum pick-up for cumulus-oocyte complexes (COCs) collection. After PCR analysis of the FF, cows were retrospectively allocated into either: positive (POS-FF) or negative (NEG-FF) group. Statistical modeling was conducted using the farm, PCR result, and laboratory in which the IVEP was performed as effects. Noteworthy, 26.6% of the animals were positive for Leptospira spp., and 70% of farms had at least one POS-FF cow in the herd. POS-FF cows had a lower number of COCs recovered (22.6 ± 1.2 vs 15.0 ± 2.8, P=0.036), rate of viable COCs (85.6 ± 0.9% vs 78.1 ± 2.8%, P=0.015), number of good-quality COCs (16.0 ± 0.9 vs 9.8 ± 2.1, P=0.026), cleaved embryos (11.9 ± 0.7 vs 7.5 ± 1.5, P=0.032), and blastocysts (7.3 ± 0.4 vs 2.3 ± 0.7, P=0.044) yielded per cow. In conclusion, the presence of Leptospira spp. in the FF of naturally infected cows impaired the amount of COCs recovered, decreasing the overall IVEP efficiency.

Lipopolysaccharide-binding protein in follicular fluid is associated with the follicular inflammatory status and granulosa cell steroidogenesis in dairy cows

Metabolic stress and subsequent hepatic dysfunction in high-producing dairy cows are associated with inflammatory diseases and declining fertility. Lipopolysaccharide (LPS)-binding protein (LBP) is produced by hepatocytes and controls the immune response, suggesting that it is involved in the pathophysiology of inflammation-related attenuation of reproductive functions during metabolic stress. This study investigated the effect of LBP on the inflammatory status, oocyte quality, and steroidogenesis in the follicular microenvironment of dairy cows. Using bovine ovaries obtained from a slaughterhouse, follicular fluid and granulosa cells were collected from large follicles to evaluate the follicular status of metabolism, inflammation, and steroidogenesis. Cumulus-oocyte complexes were aspirated from small follicles and subjected to in vitro embryo production. The results showed that follicular fluid LBP concentrations were significantly higher in cows with fatty livers and hepatitis than in those with healthy livers. Follicular fluid LBP and LPS concentrations were negatively correlated, whereas LPS concentration showed a positive correlation with the concentrations of non-esterified fatty acids (NEFA) and β-hydroxybutyric acid in follicular fluid. The blastulation rate of oocytes after in vitro fertilization was impaired in cows in which coexisting large follicles had high NEFA levels. Follicular fluid NEFA concentration was negatively correlated with granulosa cell expression of the estradiol (E2) synthesis-related gene (CYP19A1). Follicular fluid LBP concentration was positively correlated with follicular fluid E2 concentration and granulosa cell CYP19A1 expression. In conclusion, follicular fluid LBP may be associated with favorable conditions in the follicular microenvironment, including low LPS levels and high E2 production by granulosa cells.

The role of miR-10a-5p in LPS-induced inhibition of progesterone synthesis in goose granulosa cells by down-regulating CYP11A1

The poultry ovary is a preferred target for E. coli and Salmonella infection of tissues, and lipopolysaccharide (LPS) is a critical molecule in infecting the organism and interfering with cell function, invading the ovaries through the cloaca and interfering with progesterone (P4) secretion by follicular granulosa cells (GCs), seriously affecting the health of breeding geese. miRNAs are small, non-coding RNAs with a variety of important regulatory roles. To investigate the mechanism of miR-10a-5p mediated LPS inhibition of progesterone synthesis in goose granulosa cells, Yangzhou geese at peak laying period were selected as experimental animals to verify the expression levels of genes and transcription factors related to progesterone synthesis. In this study, bioinformatic predictions identified miR-10a-5p target gene CYP11A1, and genes and transcription factors related to the sex steroid hormone secretion pathway were screened. We detected that LPS inhibited CYP11A1 expression while increasing miR-10a-5p expression in vivo. Progesterone decreased significantly in goose granulosa cells treatment with 1 μg/mL LPS for 24 h, while progesterone-related genes and regulatory factors were also suppressed. We also determined that the downregulation of miR-10a-5p led to CYP11A1 expression. Overexpression of miR-10a-5p suppressed LPS-induced CYP11A1 expression, resulting in decreased progesterone secretion. Our findings indicated that miR-10a-5p was up-regulated by LPS and inhibited progesterone synthesis by down-regulating CYP11A1. This study provides insight into the molecular mechanisms regulating geese reproduction and ovulation.

Interval from Oestrus to Ovulation in Dairy Cows-A Key Factor for Insemination Time: A Review

This review describes the oestrus-to-ovulation interval, the possibility of predicting the time of ovulation, and the optimum time for insemination relative to oestrus in dairy cows. The duration of oestrus in dairy cows is approximately 8-20 h, with differences possibly related to the methods of oestrus detection and the frequency of observations. Most cows ovulate approximately 24-33 h after the onset of oestrus and 15-22 h after the end of oestrus. The interval from the preovulatory luteinising hormone (LH) surge to ovulation is approximately 4-30 h. Ovulation occurs when follicle diameter averages 18-20 mm. When it is possible to correctly determine the beginning of oestrus, artificial insemination can be performed utilizing the "a.m.-p.m. rule", and only one insemination may be applied. In cows with too long or too short oestrus-to-ovulation intervals, fertility can be compromised. One important factor that can alter the oestrus-to-ovulation interval is acute or chronic heat stress during the warm season. When there is a risk that insemination may occur too early or too late with respect to the time of ovulation, GnRH administration can be considered.

Effects of prostaglandin F2α treatment at follicular wave emergence on endometrial epidermal growth factor concentration on day 3 of the next estrous cycle and on fertility in dairy cows

Inadequate exposure to estradiol (E2) and progesterone (P4) may be the main causes of altered endometrial epidermal growth factor (EGF) profile, leading to reduced fertility in dairy cows. We hypothesized that PGF2α administration at different timings of the estrous cycle and stages of follicular development could change the profile of steroid hormones between luteolysis and estrus. This results in reduction in the peak concentration of endometrial EGF on day 3 (day 0 = estrus) in the next estrous cycle. In study 1, lactating Holstein cows were treated with PGF2α either on days 12-14 (selection phase group, n = 20) or on days 16-17 (control group, n = 24) of the estrous cycle. Blood samples were obtained before PGF2α treatment, 24 and 48 h after treatment, and on the day of estrus and ovulation for E2 and P4 assays. Endometrial tissues were collected by biopsy on day 3 for EGF assays. The duration from PGF2α treatment to both estrus and ovulation was longer in the selection phase group than in the control group (P < 0.05). The time between estrus and ovulation was longer in the selection phase group (P < 0.05). E2 concentrations were higher in the control group on the day of estrus (P < 0.05). P4 concentrations were not different between the groups. Endometrial EGF concentrations were lower in the selection phase group than in the control group (P < 0.05). In study 2, lactating Holstein cows were treated with PGF2α either on day 12 (selection phase group, n = 76) or day 16 (control group, n = 80). They were subjected to artificial insemination (AI) at estrus, and those that failed to ovulate by 24h after the first AI were subjected to second AI. On day 3, endometrial EGF concentration was determined. At estrus and on days 3 and 7, blood was collected for E2 and P4 assay from 20 randomly selected cows in each group before PGF2α treatment. The cows in the selection phase group exhibited lower EGF concentration, proportion of cows with normal EGF profile, and conception rate than cows in the control group (P < 0.05). On the day of estrus, E2 concentrations tended to be lower in the selection phase group than in the control group (P = 0.08). P4 concentrations were not different between the groups. These findings suggest that low E2 concentrations at estrus and low P4 concentrations for a prolonged period due to premature termination of CL in the absence of a dominant follicle are potential causes of altered endometrial EGF profile in dairy cows.

Alpha-linolenic acid alleviates the detrimental effects of lipopolysaccharide during in vitro ovine oocyte development

During the transition period and early lactation of ruminants with higher production, the reproductive organs are exposed to various stressors, like inflammation stimulators such as lipopolysaccharides (LPS), as a consequence of high concentrate consumption. In this study, we aimed to determine the probable potential of α-linolenic acid (ALA) in alleviating LPS-induced effects in ovine oocytes in vitro as well as the underlying controlling mechanisms. Different concentrations of LPS (0, 0.01, 0.1, 1, and 10 μg/mL) were added to the oocyte maturation medium to evaluate its effect on oocyte developmental competence. Likewise, different concentrations of ALA (0, 10, 50, 100, and 200 μM/mL) were added to the maturation medium to define its effects on oocyte developmental competence. Accordingly, a combination of ALA and LPS in a dose-dependent manner was added to the maturation medium to elucidate their effect on oocyte developmental competence and uncover any possible potential of ALA to alleviate the detrimental effect induced by the presence of LPS. The expressions of candidate genes were measured in mature oocytes treated either with ALA, LPS, or ALA plus LPS. Adding LPS to the maturation medium decreased the cleavage rate of the treated oocytes, and those oocytes reached the blastocyst stage at a lower rate. Adding ALA to the maturation medium in the presence of LPS alleviated the detrimental effects of LPS in a dose-dependent manner, which ultimately led to higher cleavage and blastocyst formation. A higher expression of Trim26, GRHPR, NDUFA, PGC-1α, SOD, CS, SDH, p53, and CAT was observed in LPS-treated oocytes compared with the ALA and control groups. Additionally, CS and CAT transcripts were down-regulated in oocytes in LPS plus ALA-treated group compared to that of the LPS-treated group. These findings revealed that ALA has the potential to alleviate the detrimental effects induced by LPS on in ovine oocytes during maturation in vitro. Thus, LPS-detrimental effect and ALA-preventing mechanisms seem to be regulated through the expression of genes involved in mitochondrial biogenesis and function, oxidative stress, and antioxidant systems.

Zinc-nanoparticles alleviate the ovarian damage induced by bacterial lipopolysaccharide (LPS) in pregnant rats and their fetuses

Lipopolysaccharide (LPS) is an endotoxin derived from the cell wall of Gram-negative bacteria. LPS exposure during early gestation is associated with adverse effects on the placenta as well as on developmental outcomes, including embryonic resorption, fetal death, congenital teratogenesis, and fetal growth retardation. This work aimed to explore the adverse effects of LPS injected at an early stage of gestation on the gonads of pregnant rats and the ovaries of their pups and the role of zinc nanoparticles (Zn-NPs) against these adverse effects. Twenty-four pregnant rats were used in this study. They were divided at gestation day 4 into four groups (n = 6): control, Zn-NPs (20 mg/kg orally from gestation day E14 till the end of weaning), LPS (50 µg/kg at gestation days E7 and E9), and LPS + Zn-NPs group. The body weight and placenta weight were recorded at gestational day 16. At postnatal day 21 (weaning), the mothers rats and their offspring were sacrificed and immediately dissected to remove the ovaries and uteri from the mothers and the ovaries from their offspring for subsequent biochemical, histological, and immunohistochemical investigations. The obtained results revealed that LPS exposure during early gestation caused severe histopathological alterations in the placenta, uterus, and ovaries of mothers, as well as in the ovaries of their pups. Also, the uterine and ovarian sections displayed a positive reaction for caspase-3 antibody and a negative reaction for Bcl-2 antibody, which reflects the apoptotic effect of LPS. Additionally, remarkable reductions in the levels of antioxidants (superoxide dismutase and catalase) and significant increases in malondialdehyde (MDA) levels were recorded in the serum of LPS-treated mothers and in the ovarian tissues of their offspring. Further biochemical analysis of the ovarian tissues from LPS-maternally treated offspring showed a significant increase in the levels of caspase-3, TNF-α, and TGF-β1, but a significant decrease in the level of IGF-1. On the other hand, treatment of mothers with Zn-NPs from day 14 of gestation until the weaning day (21st day postnatal) successfully ameliorated most of the deleterious histopathological, immunohistochemical, and biochemical changes induced by LPS.

Bovine reproductive immunoinfertility: pathogenesis and immunotherapy

Infertility is one of the primary factors for cattle reproduction in the present scenario. Reproduction-related immunoinfertility mainly involves immunization against the antigens related to reproductive hormones (LHRH, GnRH, Gonadal steroids, PGF2α and oxytocin), spermatozoa, seminal plasma and ovum. Anovulation, delayed ovulation, sperm immobilization, failure of fertilization, prolonged uterine involution, extended calving interval, prolonged post-partum estrus and reduced conception rate could be a result of immunoinfertility that occur due to the blockage of receptor site by antibodies formed against hormones, sperm and ovum. Immunoinfertility can be treated in the animal by giving sexual rest to females, by using various reproductive technologies such as in-vitro fertilization, gamete intra fallopian tube transfer, and intracytoplasmic sperm injection, sperm washing and by treating the animals with immunomodulators such as LPS, Oyster glycogen, etc. This review summarizes the different causes of bovine reproductive immunoinfertility and amelioration strategies to overcome it.

The impact of inflammatory stress on hypothalamic kisspeptin neurons: Mechanisms underlying inflammation-associated infertility in humans and domestic animals

Inflammatory diseases attenuate reproductive functions in humans and domestic animals. Lipopolysaccharide (LPS), an endotoxin released by bacteria, is known to disrupt female reproductive functions in various inflammatory diseases. LPS administration has been used to elucidate the impact of pathophysiological activation of the immune system on reproduction. Hypothalamic kisspeptin neurons are the master regulators of mammalian reproduction, mediating direct stimulation of hypothalamic gonadotropin-releasing hormone (GnRH) release and consequent release of gonadotropins, such as luteinizing hormone (LH) and follicle-stimulating hormone from the pituitary. The discovery of kisspeptin neurons in the mammalian hypothalamus has drastically advanced our understanding of how inflammatory stress causes reproductive dysfunction in both humans and domestic animals. Inflammation-induced ovarian dysfunction could be caused, at least partly, by aberrant GnRH and LH secretion, which is regulated by kisspeptin signaling. In this review, we focus on the effects of LPS on hypothalamic kisspeptin neurons to outline the impact of inflammatory stress on neuroendocrine regulation of mammalian reproductive systems. First, we summarize the attenuation of female reproduction by LPS during inflammation and the effects of LPS on ovarian and pituitary function. Second, we outline the inhibitory effects of LPS on pulsatile- and surge-mode GnRH/LH release. Third, we discuss the LPS-responsive hypothalamic-pituitary-adrenal axis and hypothalamic neural systems in terms of the cytokine-mediated pathway and the possible direct action of LPS via its hypothalamic receptors. This article describes the impact of LPS on hypothalamic kisspeptin neurons and the possible mechanisms underlying LPS-mediated disruption of LH pulses/surge via kisspeptin neurons.

Dimethyl itaconic acid improves viability and steroidogenesis and suppresses cytokine production in LPS-treated bovine ovarian granulosa cells by regulating TLR4/nfkβ, NLRP3, JNK signaling pathways

The stimulation of pro-inflammatory pathways by lipopolysaccharide (LPS) endotoxins is a key player in the pathological mechanisms involved in the development of ovarian dysfunctions in dairy cows. Dimethyl itaconate acid (DMIA) is a novel immunometabolite that has recently emerged as a regulator of inflammatory responses in mammals. The present study was undertaken to determine the anti-inflammatory effects of DMIA on bovine granulosa cells (GCs) and to explore its possible molecular mechanisms. The ovarian GCs were obtained from small follicles of dairy cows. The GCs were stimulated with 1 μg/mL LPS for 4 h and then treated with 250 μM DMIA for 12 h. The viability, production of pro-inflammatory cytokines, activation of inflammatory signaling pathways and synthesis of steroid hormones were evaluated in treated GCs. Our results showed that DMIA reduced the inflammatory responses in LPS stimulated GCs by down-regulating the expression of nod-like receptor family pyrin domain containing 3 inflammasome, and toll-like receptor 4 and by suppressing the phosphorylation of nuclear factor kappa B and c-Jun N-terminal kinase proteins. DMIA also attenuated the increased production of pro inflammatory cytokines (interleukin 6, tumor necrosis factor α and interleukin 1 beta (p < 0.01) in LPS stimulated GCs. Exposure of LPS stimulated GCs to DMIA improved the impaired steroidogenesis by up-regulation of steroid synthesis genes including 3-beta-hydroxysteroid dehydrogenase, follicle stimulating hormone receptor and cytochrome P450 aromatase. The results of the present study highlight the potential role of itaconic acid for the improvement of GCs inflammation in dairy cows with ovarian dysfunctions.

Brazilian Organic Honey from Atlantic Rainforest Decreases Inflammatory Process in Mice

Honey is an ancient food in the human diet, and the chemical composition of some types of honey has been associated with several beneficial biological effects. Among them, honey has been highlighted to improve health and control inflammatory processes. However, there is no study elucidating the mechanism of action of honey produced organically. Here, we separated organic honey (OH) samples from the Brazilian Atlantic Rainforest into eight different profiles (OH-1 to OH-8) and evaluated, in vitro and in vivo, their anti-inflammatory potential. To determine cell viability, RAW 264.7 macrophages were treated with several concentrations of OH-1 up to OH-8, and anti-inflammatory activity was assessed through NF-κB activation and TNF-α levels. All types of the studied honey up to a concentration of 4% (w/v) did not interfere with macrophage viability and decreased NF-kB activation and TNF-α levels in macrophage culture in vitro. OH-7 was selected as the most promising anti-inflammatory and used in subsequent assays. Mice pretreated orally with OH-7 showed a decrease in neutrophil migration and TNF-α level. Thus, these types of Brazilian organic honey show promising anti-inflammatory potential, particularly the OH-7 variety. Brazilian organic honey may lead to the development of new products and/or be incorporated into food for use in veterinary medicine and human health as well.

MicroRNA-146 attenuates lipopolysaccharide induced ovarian dysfunction by inhibiting the TLR4/NF- κB signaling pathway

Premature ovarian insufficiency (POI) is a disease that seriously affects women’s reproductive function and even leads to lifelong infertility. Little is known about the mechanism of lipopolysaccharide (LPS)-induced ovarian dysfunction. Thus, we aimed to identify the role of the up-regulation of microRNA (miRNA)-146 expression offered protection against ovarian dysfunction by inhibiting the toll-like receptor (TLR) 4, TLR4/phosphorylated (p)-nuclear factor (NF)-κB signaling pathway and inflammatory cytokine tumor necrosis factor (TNF)-a and Interleukin (IL)-6. In an in vivo study, we established an LPS-induced ovarian dysfunction mouse model. The mouse ovarian granulosa cells were transfected with miR-146 mimic or negative controls or inhibitor and then treated with LPS. Therefore, cell viability, cells apoptosis, IL-6 and TNF-a, TLR4, NF- κB were assessed, respectively. These results demonstrated that the up-regulation of miRNA-146 expression may protect against LPS-induced ovarian dysfunction and markedly increased the cell viability, and significantly reduced the ovarian granulosa cells apoptotic rate, and down-regulated IL-6 and TNF-a expression. In addition, miRNA-146 exerted protective ovarian functions might be via inhibiting TLR4/NF-κB signaling pathway. In summary, we reveal the up-regulation of miRNA-146 expression mitigated ovarian dysfunction by negatively regulating expression of the IL-6 and TNF-a, which may shed light on the potential molecular mechanisms of overexpression of miRNA-146 may reversed the ovarian dysfunction by inhibiting the TLR4/ NF-κB signaling pathway.

Metabolomic and transcriptomic responses of mouse testis to the dextran sulfate sodium induced colitis

Inflammatory bowel diseases (IBDs), including Crohn's disease (CD) and ulcerative colitis, are widespread in developed countries and gradually increasing in developing countries. Evidences showed that man with CD has a decrease of serum testosterone, but how IBD take effects on testicular testosterone synthesis is not well elucidated. To investigate the effects of IBD on testis, we analyzed testicular metabolome and transcriptome data of the dextran sulfate sodium (DSS) induced IBD mice. As a result, metabolomic data showed that DSS indeed induced androgen decrease in mouse testis. Correspondingly, androgen synthesis associated genes, especially Lhcgr, were down-regulated in DSS testis. From the metabolomic data, we found vitamin intake associated metabolites vitamin B2 and pyridoxamine were significantly decreased, whereas fatty acid metabolism associated molecules N-lauroylglycine and N-decanoylglycine were increased in DSS testis. In addition, we found 8-hydroxy-deoxyguanosine, a DNA oxidative damage marker, and 8-oxoguanine, a molecule responsible for DNA damage repair, were also changed in DSS testis. Simultaneously, our data also showed that DSS up-regulated the expression of meiosis initiation associated gene Stra8 and oxygen transport associated genes in testis. In summary, these results depicted the complex effects of colitis on testis. These metabolites and transcripts changed in DSS testis could be used as potential targets for IBD treatment or symptom relieve.

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.