PGE2 downregulates LPS-induced inflammatory responses via the TLR4-NF-κB signaling pathway in bovine endometrial epithelial cells

Targeting inflammation for the treatment of endometritis in bovines

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

Downregulation of XBP1s aggravates lipopolysaccharide-induced inflammation by promoting NF-κB and NLRP3 pathways' activation in goat endometrial epithelial cells

After delivery, bacterial contamination and uterine tissue degeneration in animals can lead to the development of uterine diseases, such as endometritis, accompanied by endoplasmic reticulum stress (ERS). Increasing evidence suggests that spliced X-box binding protein 1 (XBP1s), a critical component of ERS, is involved in several pathological processes in various organisms. However, the specific molecular mechanisms by which XBP1s mediates the inflammatory response in goat endometrial epithelial cells (gEECs) remain largely unknown. In the present study, XBP1s protein was induced into the nucleus in the lipopolysaccharide (LPS, 5 μg/mL)-induced inflammatory response of gEECs. Lipopolysaccharide-induced expression and nucleation of XBP1s were reduced by the inhibition of Toll-like receptor 4 (TLR4) using TAK-242 (1 μM; a TLR4 inhibitor). Expression and nucleation of XBP1s were similarly reduced when the activity of inositol-requiring enzyme 1α (IRE1α) was inhibited using 4μ8C (10 μM; an IRE1α inhibitor). In addition, inhibition of IRE1a increased IL-1β, TNF-α, and IL-8 levels and secretion of IL-6 induced by LPS. Notably, phosphorylation of nuclear factor kappa-B (NF-κB) P65 protein and expression of NOD-like receptor thermal protein domain associated protein 3 (NLRP3) were similarly increased. Furthermore, knockdown of XBP1s in gEECs consistently promoted NF-κB P65 protein phosphorylation, NLRP3 protein expression, and inflammatory cytokine secretion. In summary, the current results suggest that in the LPS-induced inflammatory response in gEECs, LPS generates intracellular signaling cascades in gEECs via TLR4, which may promote XBP1s protein expression and nucleation by activating IRE1a. However, downregulation of XBP1s expression exacerbates inflammation by promoting activation of the NF-κB and NLRP3 inflammatory vesicle pathways. These results will potentially contribute to the treatment and prevention of endometritis in ruminants.

Protective effect of the total flavonoids from Clinopodium chinense against LPS-induced mice endometritis by inhibiting NLRP3 inflammasome-mediated pyroptosis

ETHNOPHARMACOLOGICAL RELEVANCE

Clinopodium chinense (Benth.) O. Kuntze (C. chinense) is a Chinese herbal medicine used in treating gynecological hemorrhagic diseases for hundreds of years. Flavonoids are one kind of the major components in C. chinense. The flavonoids of C. chinense (TFC) have a vital role in treating endometritis but the underlying therapeutic mechanisms of TFC against endometritis have been rarely reported.

AIM OF THE STUDY

To elucidate the therapeutic effect and possible mechanisms of TFC against lipopolysaccharide (LPS)-induced endometritis in vivo and LPS-induced primary mouse endometrial epithelial cells (MEECs) injury in vitro.

MATERIALS AND METHODS

The holistic phytochemicals of the TFC and TFC-contained serum were screened and identified using UPLC-Q-TOF-MS. The model of endometritis was established by intrauterine injection of LPS (5 mg/mL) into female BALB/c mice, and the model mice were treated with TFC for 7 days. The value of MPO was measured by Myeloperoxidase assay kit, the pathological changes in the endometrium were evaluated using H&E staining and transmission electron microscope (TEM), the secretions of IL-18, IL-1β and TNF-α were determined by ELISA kits, the mRNA expressions of IL-18, IL-1β and TNF-α were determined by RT-PCR assay, and the protein levels of TLR4, IKBα, p-IKBα, p65, p-p65, caspase-1, ASC, NLRP3 and GSDMD were measured by Western blot. Subsequently, MEECs were isolated from the uterus of pregnant female mice, injured by LPS for 24 h and incubated with the TFC-contained serum. Finally, cell viability, LDH release, hoechst 33342/PI staining, immunofluorescence staining, scanning electron microscope observation, ELISA assay, RT-PCR detection and Western blot analysis were carried out to further validate the therapeutic effect and the underlying mechanisms of TFC.

RESULTS

A total of 6 compounds in the plasma of mice after being intragastric administrated of TFC were identified. The results in vivo showed that TFC significantly reduced MPO value and alleviated pathological injury of the endometrium. Furthermore, TFC significantly decreased the serum IL-18, IL-1β and TNF-α levels, and the mRNA levels of IL-18, IL-1β and TNF-α. TFC also inhibited the expressions of TLR4, p-IKBα, p-p65, caspase-1, ASC, NLRP3 and GSDMD. Besides, compared with the model group in MEECs cells, TFC-contained serum prevented pyroptosis, decreased the levels of IL-18 and IL-1β, and inhibited the mRNA expressions of IL-18, IL-1β and GSDMD. TFC-contained serum also reversed the activation of NLRP3 inflammasome caused by nigericin, and restrainted the translocation of NF-κB into nuclear.

CONCLUSIONS

TFC protects mice endometritis from the injury of LPS via suppressing the activation of NLRP3 inflammasome and pyroptosis, the underlying mechanisms of which were related to restraining the TLR4/NF-κB/NLRP3 pathway activation.

Effect of VD3 on cell proliferation and the Wnt signaling pathway in bovine endometrial epithelial cells treated with lipopolysaccharide

Vitamin D (VD) deficiency plays an important role in the occurrence and development of various uterine diseases. At present, most studies on the mechanism of VD in the Wnt signaling pathway focus on cancer, while there are no relevant reports on its mechanism in endometritis. This study investigated the effect of vitamin D3 (VD3) on the Wnt signaling pathway in endometrial epithelial cells (BEECs) induced by lipopolysaccharide (LPS). BEECs obtained from bovine uteri were treated with VD3 (0, 50 ng/mL) and LPS (0, 10, 100 ng/mL) separately or in combination, and treated with the Wnt signaling pathway inhibitor IWR-1 to study the mechanism of action. The proliferation of BEECs was evaluated by a CCK-8 assay. qRT-PCR was used to assess the gene expression of Wnt pathway-related factors, including MYC, PCNA, LGR5, GREM1, β-catenin, FZD7, FZD2, Wnt4 and VDR. The results showed that VD3 had no significant effect on cell proliferation (P > 0.05); LPS inhibited BEEC proliferation in a time- and dose-dependent manner, and cells treated with LPS at different concentrations for 24-48 h in combination with VD3 promoted cell proliferation to varying degrees. IWR-1 inhibited cell proliferation in a time- and concentration-dependent manner, while LPS + IWR-1 treatment also significantly promoted cell proliferation after VD3 treatment (P < 0.01). The qRT-PCR results showed that the expression of Wnt4 and PCNA genes showed different trends with different LPS concentrations for stimulation, and the expression of the MYC and GREM1 genes was only stimulated by high-dose (100 ng/mL) LPS stimulation. The expression of FZD7, LGR5, FZD2 and β-catenin was upregulated by LPS at both concentrations. LPS + VD3 significantly downregulated the expression of the Wnt pathway-related genes MYC, PCNA, LGR5, GREM1 and β-catenin (P < 0.001), Wnt4 and FZD2 (P < 0.01), and significantly upregulated the expression of VDR (P < 0.05). After LPS + IWR-1 treatment, the expression of the β-catenin (P < 0.01) and LGR5 (P < 0.05) genes was significantly downregulated, while the Wnt4 (P < 0.01) and VDR (P < 0.001) genes were significantly upregulated, MYC was downregulated but without a significant difference (P > 0.05). In conclusion, VD3 treatment can mitigate the LPS-induced abnormal expression of Wnt signaling pathway genes in BEECs, showing that the Wnt pathway may be a protective pathway of VD3 against LPS-induced gene overexpression in BEECs. The results suggest that VD3 may play a regulatory role in pathways other than the Wnt signaling pathway. Whether VD3 affects the Wnt signaling pathway by affecting Wnt4 gene expression requires further study.

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

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

IFN-τ mediated miR-26a targeting PTEN to activate PI3K/AKT signalling to alleviate the inflammatory damage of bEECs

Endometritis is the failure of embryo implantation and an important cause of infertility in dairy cows. IFN-τ is a type I interferon unique to ruminants. In regulating the process of inflammatory response, IFN-τ can be expressed through MicroRNAs (miRNAs) to regulate the process of inflammation. However, IFN-τ regulates lipopolysaccharide (LPS)-induced inflammatory injury of bEECs through the highly conserved miR-26a in mammals, and the mechanism remains unclear. Bovine endometrial epithelial cells (bEECs)were isolated and cultured to establish an inflammatory injury model. RT–qPCR and ELISA were used to detect the secretion of inflammatory factors. Dual-luciferase assays and target gene silencing assays determine the regulatory role of miRNAs. The target protein was detected by immunofluorescence and western blotting. This study showed that the expression of miR-26a was significantly down-regulated in mouse endometrium inflammatory injury tissue and LPS stimulated bEECs; and IFN-τ reversed the expression of miR-26a. The study also showed that the overexpression of miR-26a significantly inhibited the secretion of pro-inflammatory cytokines IL-1β, IL-6 and TNF-α. In addition, studies have shown that miR-26a inhibits its translation by targeting PTEN 3′-UTR, which in turn activates the Phosphatidylinositide 3-kinases/protein kinase B (PI3K/AKT) pathway, so that nuclear factor kappa-B (NF-κB) signaling is inhibited. In summary, the results of this study further confirm that IFN-τ as an anti-inflammatory agent can up-regulate the expression of miR-26a and target the PTEN gene to inhibit the inflammatory damage of bEECs.

MicroRNA miR-24-3p Mediates the Negative Regulation of Lipopolysaccharide-Induced Endometrial Inflammatory Response by Targeting TNF Receptor-Associated Factor 6 (TRAF6)

Purpose

Endometritis is a female reproductive disease that affects the cattle industries development and microRNAs (miRNAs) play a pivotal role and critical regulators of the innate immune response in varieties of diseases. The present study intends to investigate the regulatory role of miR‐24-3p in the innate immune response involved in endometritis and evaluate its therapeutic potential.

Methods

Whole mice uteri and bovine endometrial epithelial cells (BEECs) were separately stimulated with LPS. The BEECs were also transfected with miR-24-3p mimic and negative control; siTRAF6 and siNC; pcDNA3.1 empty and pcDNA3.1(+)TRAF6 separately with LPS stimulation. The expression levels of miR‐24-3p and TRAF6 were measured via quantitative real‐time polymerase chain reaction (qRT-PCR) and Western blot, respectively. LPS‐induced inflammatory response assessed by inflammatory cytokines secretion and expression via ELISA and qRT-PCR. Bioinformatics analysis and luciferase reporter assay validated the interaction between miR‐24-3p and TRAF6. The activation of the NF‐ĸB/MAPK pathway and p65 phosphorylation was investigated by Western blot and immunofluorescence assay, respectively.

Results

The expression of miR‐24-3p was decreased, and TRAF6 was elevated with an increased level of pro-inflammatory cytokines in LPS‐treated BEECs and mice uterus. The overexpression of miR‐24-3p suppressed LPS‐induced secretion of inflammatory cytokines (IL‐1β, IL‐6, IL-8 and TNF-α) and deactivation of NF‐ĸB/MAPK pathways. The downregulation of TRAF6 inhibited LPS‐induced inflammatory response in BEECs. TRAF6 is validated as a target of miR‐24-3p, and miR‐24-3p reversed the overexpression of cloned TRAF6 on inflammation response in BEECs.

Conclusion

Our findings demonstrate that the overexpression of miR‐24-3p attenuates endometrial inflammation and the expression of pro-inflammatory mediators via suppressing TRAF6. Therefore, modulating the pathogenesis of endometritis and possibly, a therapeutic potential against endometritis.

Prostaglandin E receptor 2 mediates the inducible effects of prostaglandin E2 on expression of growth factors and enzymes in cattle endometrial epithelial cells and explants

Prostaglandin E₂ (PGE₂ ) is able to induce the expression of several growth factors and enzymes in cattle endometria. However, the specific type of PGE₂ receptors which mediates this effect is not fully clear. In this study, the role of prostaglandin E receptor 2 (PTGER2) in PGE₂ -mediated induction of growth factors and enzymes expression in cattle endometrial explants and epithelial cells were investigated. PTGER2 was blocked by a PTGER2 antagonist, AH6809, before PGE₂ treatment, then the mRNA and protein expression levels of several growth factors and enzymes were compared with that in PGE₂ alone treatment group by real-time RT-PCR and Western blotting analysis in endometrial epithelial cells and explants. Results indicated that PGE₂ significantly increased the mRNA and protein levels of these growth factors and enzymes, while the rates of increment in the expression of these growth factors and enzymes were inhibited by AH6809. In addition, a PTGER2 agonist, butaprost, significantly increased the expression levels of these growth factors and enzymes, and the effect could be blocked by AH6809. In conclusion, PTGER2 was found to be one dominant receptor mediating the inducible effects of PGE₂ on the expression of these growth factors and enzymes in cattle endometrial explants and epithelial cells.

Honokiol inhibits endoplasmic reticulum stress-associated lipopolysaccharide-induced inflammation and apoptosis in bovine endometrial epithelial cells

Honokiol (HKL) has been previously reported to exert anti-inflammatory effects in numerous diseases. However, the role of HKL in endometritis remains unclear. The present study aimed to explore and elucidate the role of HKL in a lipopolysaccharide (LPS)-induced in vitro model of endometritis. Bovine endometrial epithelial cells (bEECs) were pre-treated with HKL at doses of 1, 10 and 20 µM, followed by 1 µg/ml LPS. MTT assay was then used to detect cell viability. ELISA was utilized to measure the levels of the proinflammatory cytokines TNF-α, IL-1β and IL-6 in bEECs culture supernatants. Reverse transcription-quantitative PCR was further performed to examine the mRNA expression levels of these cytokines. Cell apoptosis was observed by TUNEL staining and the levels of Bcl-2, Bax, cleaved caspase 3 and cleaved caspase 9 were assayed by western blotting. Western blotting was also performed to detect the expression levels of endoplasmic reticulum (ER) stress-related proteins activating transcription factor 6, CCAAT-enhancer-binding protein homologous protein, inositol-requiring enzyme 1 and cleaved caspase 12 in bEECs. LPS treatment reduced cell viability and HKL treatment improved the viability of bEECs after LPS treatment. The LPS-induced inflammatory response and apoptosis in bEECs were also inhibited by HKL treatment. Additionally, the increased expression of ER stress-related proteins induced by LPS was reversed by HKL treatment. Following stimulation with the ER stress inducer tunicamycin, it was revealed that HKL attenuated ER stress and inhibited LPS-induced inflammatory response and apoptosis in bEECs. In summary, HKL inhibited ER stress associated with LPS-induced inflammation and apoptosis in bEECs, providing evidence that HKL can serve to be a novel agent for the treatment of endometritis.

ISGylation Inhibits an LPS-Induced Inflammatory Response via the TLR4/NF-κB Signaling Pathway in Goat Endometrial Epithelial Cells

Simple Summary

Endometritis is a common and important reproductive disease of domestic animals, leading to repeated infertility, abortion, and ovarian dysfunction, which affects the reproductive rate and production performance of female domestic animals, and causes serious financial loss to farmers. Infection with Gram-negative bacteria, the release of LPS and activation of the TLR4/NF-κB signaling pathway are the principal factors responsible for the disease. However, the mechanism of the interaction between endometrial immunity and bacterial infection is not entirely clear. Ubiquitin-like protein ISG15 can regulate the TLR4/NF-κB signaling pathway via the ISGylation modification system, which modulates the inflammatory response. In the present study, we found that ISG15 proteins were mainly located in the cytoplasm of goat endometrial epithelial cells (gEECs) and that the expression of key genes and proteins of ISGylation increased in LPS-induce gEECs. Overexpression and silencing of the ISG15 gene demonstrated that ISGylation inhibited an LPS-induced inflammatory response via the TLR4/NF-κB signaling pathway in gEECs. Here, we provide the experimental basis for further exploration of the role of the ISGylation modification system in the inflammatory response of endometrium and a potential method for the treatment of endometritis.

Abstract

Endometritis is a common and important reproductive disease of domestic animals. The principal factors responsible for the disease are infection with Gram-negative bacteria, the release of Lipopolysaccharides (LPS) and activation of the TLR4/NF-κB signaling pathway. However, we do not fully understand the interaction between endometrial immunity and bacterial infection in the disease etiology. The ubiquitin-like protein ISG15 can regulate the TLR4/NF-κB signaling pathway via the ISGylation modification system, modulating the inflammatory response. In the present study, we found that ISG15 protein was expressed mainly in the cytoplasm of goat endometrial epithelial cells (gEECs) and that the expression of key genes and proteins of ISGylation increased in LPS-induced gEECs. Overexpression and silencing of the ISG15 gene demonstrated that ISGylation inhibited an LPS-induced inflammatory response via the TLR4/NF-κB signaling pathway in gEECs. Here, we provide the experimental basis for further exploration of the role of the ISGylation modification system in the inflammatory response of endometrium and a potential method for the treatment of endometritis.

Modulation of Bovine Endometrial Cell Receptors and Signaling Pathways as a Nanotherapeutic Exploration against Dairy Cow Postpartum Endometritis

Simple Summary

The provision of updated information on the molecular pathogenesis of bovine endometritis with host-pathogen interactions and the possibility of exploring the cellular sensors mechanism in a nanotechnology-based drug delivery system against persistent endometritis were reported in this review. The mechanism of Gram-negative bacteria and their ligands has been vividly explored, with the paucity of research detail on Gram-positive bacteria in bovine endometritis. The function of cell receptors, biomolecules proteins, and sensors were reportedly essential in transferring signals into cell signaling pathways to induce immuno-inflammatory responses by elevating pro-inflammatory cytokines. Therefore, understanding endometrial cellular components and signaling mechanisms across pathogenesis are essential for nanotherapeutic exploration against bovine endometritis. The nanotherapeutic discovery that could inhibit infectious signals at the various cell receptors and signal transduction levels, interfering with transcription factors activation and pro-inflammatory cytokines and gene expression, significantly halts endometritis.

Abstract

In order to control and prevent bovine endometritis, there is a need to understand the molecular pathogenesis of the infectious disease. Bovine endometrium is usually invaded by a massive mobilization of microorganisms, especially bacteria, during postpartum dairy cows. Several reports have implicated the Gram-negative bacteria in the pathogenesis of bovine endometritis, with information dearth on the potentials of Gram-positive bacteria and their endotoxins. The invasive bacteria and their ligands pass through cellular receptors such as TLRs, NLRs, and biomolecular proteins of cells activate the specific receptors, which spontaneously stimulates cellular signaling pathways like MAPK, NF-kB and sequentially triggers upregulation of pro-inflammatory cytokines. The cascade of inflammatory induction involves a dual signaling pathway; the transcription factor NF-κB is released from its inhibitory molecule and can bind to various inflammatory genes promoter. The MAPK pathways are concomitantly activated, leading to specific phosphorylation of the NF-κB. The provision of detailed information on the molecular pathomechanism of bovine endometritis with the interaction between host endometrial cells and invasive bacteria in this review would widen the gap of exploring the potential of receptors and signal transduction pathways in nanotechnology-based drug delivery system. The nanotherapeutic discovery of endometrial cell receptors, signal transduction pathway, and cell biomolecules inhibitors could be developed for strategic inhibition of infectious signals at the various cell receptors and signal transduction levels, interfering on transcription factors activation and pro-inflammatory cytokines and genes expression, which may significantly protect endometrium against postpartum microbial invasion.

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

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

Chlorogenic acid ameliorates mice clinical endometritis by activating Keap1/Nrf2 and inhibiting NFκB signalling pathway

OBJECTIVES

Clinical endometritis is a common reproductive disorder in mammals that seriously endangers animal health and causes economic losses worldwide. This study aims to use lipopolysaccharide and Trueperella pyogenes exotoxin as modelling reagents (LC) to perfuse the mouse uterus in order to establish a model of clinical endometritis and to investigate the anti-inflammatory and antioxidant effects of chlorogenic acid (CGA).

METHODS

In this study, five LC uterine perfusions were selected to model clinical endometritis. The anti-inflammatory and antioxidant effects of CGA were clarified. Through HE staining, proinflammatory cytokines, blood testing, NFκB and Keap1/Nrf2 signalling pathways and other index changes to explore the protection mechanism of CGA.

KEY FINDINGS

After CGA treatment, the appearance, inflammatory damage and blood indicators of the mouse uterus returned to normal. Simultaneously, CGA could inhibit the activation of NFκB and reduce the release of inflammatory cytokines; CGA could also activate Keap1/Nrf2, promote the dissociation of Keap1 and Nrf2 and significantly increase the expression of the downstream genes HO-1 and NQO1.

CONCLUSIONS

The above results together explain that five LC uterine perfusions can be used to establish a mouse model of clinical endometritis. CGA can treat clinical endometritis by activating Keap1/Nrf2 and inhibiting the NFκB signalling pathway.

MiR-505 as an anti-inflammatory regulator suppresses HMGB1/NF-κB pathway in lipopolysaccharide-mediated endometritis by targeting HMGB1

Endometritis is characterized by severe inflammation and tissue damage. It is a common clinical disease that causes infertility due to infectious diseases of the reproductive system. MicroRNAs (miRNAs) are the current focus of research on the regulation of the inflammatory process and play a vital role in various inflammatory diseases. The highly conserved miR-505 regulates the mechanism of lipopolysaccharide (LPS) induced endometritis, but the extent to which pro-inflammatory genes are activated remains unclear. The results of this study showed that the expression of miR-505 was significantly down-regulated in mouse endometritis tissue and LPS-stimulated BEND cells. The study also showed that overexpression of miR-505 significantly suppressed the production of the pro-inflammatory cytokines IL-1β, IL-6 and TNF-α, and this effect was reversed by inhibiting the expression of miR-505. Moreover, miR-505 inhibited the expression of HMGB1 by targeting its 3'-UTR, thereby inhibiting the activation of HMGB1/NF-κB signalling. Taken together, the results of this study further confirmed that miR-505, as an anti-inflammatory agent, regulates the activation of the HMGB1/NF-κB signalling pathway through negative feedback.

MiR-643 inhibits lipopolysaccharide-induced endometritis progression by targeting TRAF6

Endometritis is a prevalent disease with inflammation of uterus endangering women reproductive health. MicroRNAs (miRNAs) play important roles in inflammatory disorders, including endometritis. However, the role and mechanism of miR-643 in endometritis development remain unclear. This study aimed to investigate the effect of miR-643 on lipopolysaccharide (LPS)-induced inflammatory response and clarify the potential mechanism. LPS-treated human endometrial epithelial cells (HEECs) were cultured to investigate the role of miR-643 in vitro. The expression levels of miR-643 and tumor necrosis factor receptor-associated factor 6 (TRAF6) were measured via quantitative real-time polymerase chain reaction and western blot, respectively. LPS-induced inflammatory response was assessed by inflammatory cytokines secretion via enzyme-linked immunosorbent assay. The activation of nuclear factor-κB (NF-κB) pathway was investigated by western blot. The interaction between miR-643 and TRAF6 was validated by bioinformatics analysis, luciferase reporter assay, and RNA immunoprecipitation. The expression of miR-643 was decreased and TRAF6 protein level was enhanced in LPS-treated HEECs. The overexpression of miR-643 suppressed LPS-induced secretion of inflammatory cytokines (tumor necrosis factor-α, interleukin-1β [IL-1β], and IL-6) and activation of NF-κB pathway. The knockdown of TRAF6 inhibited LPS-induced inflammatory response in HEECs. TRAF6 was validated as a target of miR-643 and TRAF6 restoration reversed the effect of miR-643 on inflammation response in LPS-treated HEECs. Collectively, miR-643 attenuated LPS-induced inflammatory response by targeting TRAF6, indicating a novel avenue for the treatment of endometritis.

Cryptochlorogenic acid attenuates LPS-induced inflammatory response and oxidative stress via upregulation of the Nrf2/HO-1 signaling pathway in RAW 264.7 macrophages

Phenolic acids are found in natural plants, such as caffeic acid, rosmarinic acid, and chlorogenic acid. They have long been used as pharmacological actives, owing to their anti-inflammatory and antioxidant activities. Cryptochlorogenic acid (CCGA) is a special isomer of chlorogenic acid; the pharmacological effects and related molecular mechanisms of CCGA have been poorly reported. In the present study, the antioxidant and anti-inflammatory effects of CCGA in RAW 264.7 macrophages and the underlying mechanisms were investigated. The results revealed that CCGA dose-dependently inhibited LPS-induced production of NO, TNF-α, and IL-6 and blocked iNOS, COX-2, TNF-α, and IL-6 expressions. CCGA also significantly increased the GSH/GSSG ratio and SOD activity and reduced the MDA level. Moreover, CCGA suppressed the nuclear translocation of NF-κB by hindering the phosphorylation of IκB kinase (IKK) and degrading IκB. It also downregulated the phosphorylation of MAPKs. Our results indicated that CCGA significantly inhibited NF-κB activation by controlling the expression of pro-inflammatory factors and promoting the nuclear transfer of Nrf2. In conclusion, CCGA could attenuate LPS-induced inflammatory symptoms by modulating NF-κB/MAPK signaling cascades and inhibit LPS-induced oxidative stress via Nrf2 nuclear translocation.

Different effects of cortisol on pro-inflammatory gene expressions in LPS-, heat-killed E.coli-, or live E.coli-stimulated bovine endometrial epithelial cells

Background

Bacterial infections are common in postpartum dairy cows. Cortisol level has been observed to increase in dairy cows during peripartum period, and is associated with the endometrial innate immunity against pathogens like E.coli. However, the mechanism underlying how cortisol regulates E.coli-induced inflammatory response in bovine endometrial epithelial cells (BEEC) remains elusive.

Results

Cortisol decreased the expressions of IL1β, IL6, TNF-α, IL8, and TLR4 mRNA in BEEC treated with LPS or heat-killed E.coli, but up-regulated these gene expressions in BEEC stimulated by live E.coli.

Conclusion

Cortisol exerted the anti-inflammatory action on LPS- or heat-killed E.coli-stimulated BEEC, but the pro-inflammatory action on live E.coli-induced BEEC.

Anti-inflammatory effect of Yam Glycoprotein on lipopolysaccharide-induced acute lung injury via the NLRP3 and NF-κB/TLR4 signaling pathway

Acute lung injury (ALI) is a common lung disease accompanied by acute and persistent pulmonary inflammatory response syndrome, which leads to alveolar epithelial cells and capillary endothelial cell damage. Yam glycoprotein, separated from traditional Chinese yam, has been shown to have anti-inflammatory and immunomodulatory effects. In this experiment, we mainly studied the therapeutic effect and mechanism of a glycoprotein on the lipopolysaccharide (LPS)-induced ALI mice. An oral glycoprotein method was used to treat the mouse ALI model induced by LPS injection in the peritoneal cavity. Afterward, we measured the wet/dry (W/D) ratio, the activity of myeloperoxidase (MPO), the oxidative index superoxide dismutase (SOD), malondialdehyde (MDA), glutathione peroxidase (GSH-PX) and the production of inflammatory cytokines interleukin-1β (IL-1β), tumour necrosis factor-α (TNF-α), and interleukin-6 (IL-6) to evaluate the effect of yam glycoprotein on lung tissue changes. We examined the protein expression of TLR4, ASC, NF-κBp65, p-NF-κBp65, Caspase-1, IκB, NLRP3, p-IκB, and β-actin by western blot analysis. Immunohistochemical analyses of NLRP3 and p-p65 in lung tissue were carried out to assess the mechanism of glycoprotein action. This result suggests that glycoprotein markedly depressed LPS-induced lung W/D ratio, MPO activity, MDA content SOD and GSH-Px depletion, and the contents of inflammatory cytokines IL-1β, IL-6, and TNF-α. Moreover, glycoprotein blocked TLR4/NF-κBp65 signaling activation and NLRP3inflammasome expression in LPS-induced ALI mice. As this particular study shows, glycoprotein has a safeguarding effects on LPS-induced ALI mice, possibly via activating NLRP3inflammasome and TLR4/NF-κB signaling pathways.

Catalpol ameliorates LPS-induced endometritis by inhibiting inflammation and TLR4/NF-κB signaling

Catalpol is the main active ingredient of an extract from Radix rehmanniae, which in a previous study showed a protective effect against various types of tissue injury. However, a protective effect of catalpol on uterine inflammation has not been reported. In this study, to investigate the protective mechanism of catalpol on lipopolysaccharide (LPS)-induced bovine endometrial epithelial cells (bEECs) and mouse endometritis, in vitro and in vivo inflammation models were established. The Toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) signaling pathway and its downstream inflammatory factors were detected by enzyme-linked immunosorbent assay (ELISA), quantitative real-time polymerase chain reaction (qRT-PCR), western blot (WB), and immunofluorescence techniques. The results from ELISA and qRT-PCR showed that catalpol dose-dependently reduced the expression of pro-inflammatory cytokines such as tumor necrosis factor α (TNF-α), interleukin (IL)-1β, and IL-6, and chemokines such as C-X-C motif chemokine ligand 8 (CXCL8) and CXCL5, both in bEECs and in uterine tissue. From the experimental results of WB, qRT-PCR, and immunofluorescence, the expression of TLR4 and the phosphorylation of NF-κB p65 were markedly inhibited by catalpol compared with the LPS group. The inflammatory damage to the mouse uterus caused by LPS was greatly reduced and was accompanied by a decline in myeloperoxidase (MPO) activity. The results of this study suggest that catalpol can exert an anti-inflammatory impact on LPS-induced bEECs and mouse endometritis by inhibiting inflammation and activation of the TLR4/NF-κB signaling pathway.

Circulating exosomes may identify biomarkers for cows at risk for metabolic dysfunction

Disease susceptibility of dairy cows is greatest during the transition from pregnancy to lactation. Circulating exosomes may provide biomarkers to detect at-risk cows to enhance health and productivity. From 490 cows, animals at high- (n = 20) or low-risk (n = 20) of transition-related diseases were identified using plasma non-esterified fatty acid and β-hydroxybutyrate concentrations and liver triacylglyceride concentrations during the two weeks post-calving. We isolated circulating exosomes from plasma of dairy cows at low-risk (LR-EXO) and high-risk (HR-EXO), and analyzed their proteome profiles to determine markers for metabolic dysfunction. We evaluated the effects of these exosomes on eicosanoid pathway expression by bovine endometrial stromal (bCSC) and epithelial (bEEL) cells. HR-EXO had significantly lower yield of circulating exosomes compared with LR-EXO, and unique proteins were identified in HR-EXO and LR-EXO. Exposure to LR-EXO or HR-EXO differentially regulated eicosanoid gene expression and production in bCSC and bEEL cells. In bCSC, LR-EXO exposure increased PGE₂ and PGD₂ production, whereas HR-EXO exposure increased PTGS2 gene expression. In bEEL, HR-EXO exposure caused a decrease in PGE_2, PGF_2α, PGD₂, PGFM and TXB₂ production. The unique presence of serpin A3-7, coiled-coil domain containing 88A and inhibin/activin β A chain in HR-EXO, indicates potential biomarkers for cows at-risk for metabolic diseases. Our results are in line with the health status of the cow indicating a potential diagnostic role for exosomes in enhancing cows’ health and fertility.

Prostaglandin E2 and an EP4 receptor agonist inhibit LPS-Induced monocyte chemotactic protein 5 production and secretion in mouse cardiac fibroblasts via Akt and NF-κB signaling

BACKGROUND

Prostaglandin E2 (PGE₂) signals through 4 separate G-protein coupled receptor sub-types to elicit a variety of physiologic and pathophysiological effects. We have previously reported that mice lacking the EP4 receptor in the cardiomyocytes develop heart failure with a phenotype of dilated cardiomyopathy. Also, these mice have increased levels of chemokines, like MCP-5, in their left ventricles. We have recently reported that overexpression of the EP4 receptor could improve cardiac function in the myocardial infarction model. Furthermore, we showed that overexpression of EP4 had an anti-inflammatory effect in the whole left ventricle. It has also been shown that PGE₂ can antagonize lipopolysaccharide-induced secretion of chemokines/cytokines in various cell types. We therefore hypothesized that PGE₂ inhibits lipopolysaccharide (LPS)-induced MCP-5 secretion in adult mouse cardiac fibroblasts via its EP4 receptor.

METHODS AND RESULTS

Our hypothesis was tested using isolated mouse adult ventricular fibroblasts (AVF) treated with LPS. Pre-treatment of the cells with PGE₂ and the EP4 agonist CAY10598 resulted in reductions of the pro-inflammatory response induced by LPS. Specifically, we observed reductions in MCP-5 secretion. Western blot analysis showed reductions in phosphorylated Akt and IκBα indicating reduced NF-κB activation. The anti-inflammatory effects of PGE₂ and EP4 agonist signaling appeared to be independent of cAMP, p-44/42, or p38 pathways.

CONCLUSION

Exogenous treatment of PGE₂ and the EP4 receptor agonist blocked the pro-inflammatory actions of LPS. Mechanistically, this was mediated via reduced Akt phosphorylation and inhibition of NF-κB.

Regulatory roles of PGE2 in LPS-induced tissue damage in bovine endometrial explants

Bovine endometritis is the most common uterine disease following parturition. The role of prostaglandin E₂ (PGE₂) in regulating normal physiological function in the bovine endometrium has been clearly established. Although PGE₂ accumulation is observed in multiple inflammatory diseases, such as endometritis, its association with pathogen-induced inflammatory damage in the endometrium is unclear. To clarify the role of PGE₂ in lipopolysaccharide (LPS)-induced endometritis in cultured bovine endometrial explants, the levels of PGE₂ secretion, prostaglandin synthetases, pro-inflammatory factors, and damage-associated molecular patterns (DAMPs) were evaluated in the present study. Significant PGE₂ accumulation in response to LPS stimulation, up-regulation of prostaglandin-endoperoxide synthase-2 (PTGS-2), microsomal prostaglandin E synthase-1 (mPGES-1), pro-inflammatory factors including interleukin-6 (IL-6), tumor necrosis factor (TNF-α), and induced nitric oxide synthase (iNOS)/nitric oxide (NO) and DAMPs including hyaluronan binding protein 1 (HABP1) and high mobility group box-1 (HMGB1), were observed compared to the control group. LPS induced distinct damage in the bovine endometrium, characterized by morphological changes and increases in HABP1 and HMGB1 expression. PTGS-2 inhibitors CAY10404 and NS398 effectively decreased the secretion of PGE₂ and the expression of prostaglandin synthetases, pro-inflammatory factors and DAMPs, and alleviated LPS-induced tissue damage. These results indicate that PGE₂ accumulates via PTGS-2 and mPGES-1 and induces tissue damage by upregulating pro-inflammatory factors and DAMPs in LPS-treated bovine endometrial explants. These findings provide a basis for the effect of PGE₂ on LPS-treated bovine endometrium, and suggest a potential target for curing endometritis.