FAS/FASL-mediated cell death in the bovine endometrium

Molybdenum interferes with MMPs/TIMPs expression to reduce the receptivity of porcine endometrial epithelial cells

To investigate the effect of trace element molybdenum (Mo) on the receptivity of porcine endometrial epithelial cells (PEECs) and evaluate Mo toxicity and its potential molecular mechanisms, Mo-treated PEECs models were established by incubating the cells with various concentrations of medium containing Mo (0, 0.005, 0.020, 0.200, and 5 mmol/L MoNa2O4·2H2O). The results showed that Mo disrupted the morphology and ultrastructure of PEECs, triggered blurred cell edges, cell swelling, cell cycle arrest, and increased apoptosis. At the molecular level, Mo treatment activated the TGF-β1/SMAD2 and PI3K/AKT1 pathways, causing a significant increase in matrix metalloproteinase (MMP)-9 and MMP-2 protein expression. Accompanied by markedly increased tissue inhibitors matrix metalloproteinase (TIMP)-2 and decreased TIMP-1, the balance of MMP2/TIMP-2 and MMP-9/TIMP-1 were disrupted. Ultimately, the receptivity of PEECs was destroyed by excessive Mo, which is revealed by the significant decrease of receptive marker molecules, including leukemia inhibitory factor (LIF), integrins β3 (ITGβ3), heparin-binding epidermal growth factor (HB-EGF), and vascular endothelial growth factor (VEGF). To sum up, the current study demonstrated the potential toxicity of Mo to PEECs, indicating reproductive toxicity at high Mo concentrations and suggesting that the content of Mo should be evaluated as a potential risk factor.

Estradiol-17β regulates proliferation and apoptosis of sheep endometrial epithelial cells by regulating the relative abundance of YAP1

Yes-associated protein 1 (YAP1) transcription regulator of the Hippo protein kinase pathway, serves as a key regulator of tissue growth and organ size by regulating cell proliferation and apoptosis. Effects of YAP1 on proliferation and apoptosis of sheep endometrial epithelial cells (EEC) as a result of estradiol-17β (E₂) treatment, however, remain unclear. In the present study, the abundance of YAP1 protein in the uterine horn was greater than that in the uterine body or cervix. The YAP1 protein was primarily localized in the endometrial luminal and glandular epithelial cells of the uterine horn of ewes on day 2 of the estrous cycle. Compared with control samples, there was a lesser abundance of YAP1 mRNA transcript that was associated with a lesser proliferation and greater apoptosis of EEC. There were also lesser concentrations of epidermal growth factor and insulin-like growth factor 1 in the spent culture medium when there was a lesser abundance of YAP1 mRNA in EEC compared with those in the control group. When there was a greater abundance of YAP1 mRNA transcript, there were greater concentrations of epidermal growth factor and insulin-like growth factor 1 in the spent media. Furthermore, with estradiol-17β treatment the abundance of YAP1 mRNA transcript was similar to that of the control samples. Taken together, estradiol-17β may function as an essential regulator of EEC proliferation and apoptosis by modulation of concentrations of YAP1 protein in the sheep uterus. These results indicate there are molecular mechanisms of estradiol-17β and YAP1 in EEC proliferation and apoptosis of ewes.

Do arachidonic acid metabolites affect apoptosis in bovine endometrial cells with silenced PPAR genes?

Peroxisome proliferator-activated receptors (PPARs) are expressed in bovine uterus, and their agonists are arachidonic acid (AA) metabolites. We hypothesised that silencing of PPAR genes in bovine endometrial stromal cells (ESC) would change the intracellular signalling through PPAR and affect apoptosis after cell treatment with different AA metabolites. The study's aims are detection of apoptosis and examining the influence of prostaglandins and leukotrienes on apoptosis occurring in physiological ESC and cells with silenced PPAR (α, δ, and γ) genes. Silencing the PPARα and PPARδ genes in cells resulted in increased DNA fragmentation and mRNA and protein expression of caspase (CASP) -3 and -8 (P < 0.05). Neither DNA fragmentation nor the mRNA and protein expression of CASP3 and -8 in cells with silenced PPARγ gene were changed compared to physiological cells (P > 0.05). Among PPARs, PPARα and PPARδ appear to inhibit apoptosis, and AA metabolites, as PPAR agonists, modify this process in bovine ESC.

FasL on decidual macrophages mediates trophoblast apoptosis: A potential cause of recurrent miscarriage

Macrophages can induce Fas ligand (FasL)-mediated apoptosis, and the deregulation of apoptosis is known to be associated with recurrent miscarriage (RM). The aim of the present study was to investigate the possible involvement of FasL in macrophage-mediated trophoblast apoptosis and its potential role in RM. Human decidual and placental villous tissues were collected from 81 women (21 for the RM group, 26 for the spontaneous abortion group and 34 for the control group) at 7-9 weeks of gestation. The distribution changes of macrophages and the expression of FasL on macrophages were evaluated by immunohistochemical, immunofluorescence and western blot analyses. A macrophage and trophoblast co-culture model was used to determine the effects of FasL on the apoptosis of trophoblasts. The results indicated that CD86⁺ macrophage populations in decidual tissues were significantly increased, accompanied by reduced CD163⁺ macrophages in the abortion and RM groups. Furthermore, the distribution of CD68⁺ macrophages was also significantly altered in specimens from the abortion and RM groups, and they were observed to have infiltrated into the trophoblast cells. In addition, elevated expression of FasL on CD68⁺ and CD86⁺ macrophages in the decidua was observed in the spontaneous abortion and RM groups of patients, and FasL was demonstrated to mediate the induction of trophoblast apoptosis by macrophages in co-culture. These results indicate that the aberration of macrophage-induced FasL-mediated apoptosis may represent one of the causes of RM.

Endometrial Epithelial Cell Apoptosis Is Inhibited by a ciR8073-miR181a-Neurotensis Pathway during Embryo Implantation

Development of the receptive endometrium (RE) from the pre-receptive endometrium (PE) is essential for embryo implantation, but its molecular mechanisms have not been fully understood. In this study, lncRNA-miRNA-mRNA and circRNA-miRNA-mRNA networks were constructed to explore the functions of potential competing endogenous RNAs (ceRNA) during the development of RE in dairy goats. We observed that circRNA8073 (ciR8073) decreased the levels of miR-181a by acting as a miRNA sponge. This effect indirectly increased the expression of neurotensin in endometrial epithelial cells (EECs). Neurotensin then inhibited EEC apoptosis by increasing the expression of BCL-2/BAX in favor of BCL-2 via the MAPK pathway and also induced increased expression of leukemia-inhibitory factor, cyclo-oxygenase 2, vascular endothelial growth factor A, and homeobox A10. We have thus identified a ciR8073-miR181a-neurotensin pathway in the endometrium of dairy goats. Through this pathway, ciR8073 functions as a ceRNA that sequesters miR-181a, thereby protecting neurotensin transcripts from miR-181a-mediated suppression in EECs.

miR-26a promoted endometrial epithelium cells (EECs) proliferation and induced stromal cells (ESCs) apoptosis via the PTEN-PI3K/AKT pathway in dairy goats

Changes in endometrial cell morphology and function are absolutely necessary for successful embryo implantation. In this study, miR-26a was widely expressed in dairy goats, and was found to be regulated by β-estradiol (E2) and progesterone (P4) in endometrial epithelium cells (EECs) as well as stromal cells (ESCs). Furthermore, miR-26a played a role in the regulation of cells proliferation and apoptosis by directly regulating PTEN and indirectly regulating the PI3K/AKT pathway in EECs but not in ESCs of dairy goats in vitro. In addition, miR-26a regulated the expression of osteopontin (OPN), vascular endothelial growth factor (VEGF), Cyclooxygenase-2 (COX-2), and prolactin (PRL) in endometrial cells. Therefore, we could get a conclusion that miR-26a had very complex and diverse functions in the endometrial cells during the development of endometrial receptivity in dairy goats. This study provided an efficient platform for studying the regulatory effect of miR-26a on endometrial cells during the development of endometrial receptivity in dairy goats.

CircRNA-9119 regulates the expression of prostaglandin-endoperoxide synthase 2 (PTGS2) by sponging miR-26a in the endometrial epithelial cells of dairy goat

Circular RNAs (circRNAs) have been found to play important functional roles in epigenetic regulation under certain physiological and pathological conditions. However, knowledge of circRNAs during the development of receptive endometrium (RE) from pre-RE is limited. In the RE of dairy goats, higher circRNA-9119 levels, with lower miR-26a and higher prostaglandin-endoperoxide synthase 2 (PTGS2) levels, were detected. Further study showed that circRNA-9119 decreased levels of miR-26a by acting as a microRNA sponge, and that miR-26a downregulated the expression of PTGS2 via the predicted target site in endometrial epithelial cells (EECs) of dairy goats in vitro. In this way, circRNA-9119 functioned as a competing endogenous RNAs (ceRNA) that sequestered miR-26a, thereby protecting PTGS2 transcripts from miR-26a-mediated suppression in dairy goat EECs in vitro. Furthermore, PTGS2 participated in the regulation of some protein markers for endometrial receptivity in dairy goat EECs in vitro. Thus, a circRNA-9119–miR-26a–PTGS2 pathway in the endometrium was identified, and modulation of circRNA-9119–miR-26a–PTGS2 expression in EECs may emerge as a potential target to regulate the development of RE.

MiR-449a regulates caprine endometrial stromal cell apoptosis and endometrial receptivity

In this study, an RT-qPCR analysis showed that the expression levels of miR-449a in the pre-receptive endometrium were lower compared to the receptive endometrium, which is consistent with previous sequencing data (previous investigations). To detect the role of miR-449a in endometrial receptivity, we transfected caprine endometrial stromal cells (ESCs) cultured in vitro with miR-449a mimics. The results revealed that miR-449a decreased the mRNA and protein levels of LGR4 by targeting its 3′-untranslated region. The miR-449a mimics significantly reduced the G₁ cell population from 52.56% (mimic NC) to 42.19% with a concordant increase in the G₂ and S cell populations from 47.44% (mimic NC) to 57.81%, suggesting that miR-449a caused ESC cell cycle arrest. In addition, the number of apoptotic cells was significantly higher in ESCs transfected with miR-449a mimics (P < 0.05) than in ESCs transfected with mimic NC. In vivo, rich pinopodes were observed on the endometrial surface in the miR-449a agomir group compared with the miR-449a antagomir group. The results of hematoxylin-eosin staining showed that endometrial thickness was significantly increased in the miR-449a agomir group compared with the miR-449a antagomir group. These results suggest that miR-449a could enhance endometrial receptivity.

miR-182 aids in receptive endometrium development in dairy goats by down-regulating PTN expression

Increasing evidence has shown that miRNAs play important roles in endometrium development during the menstrual cycle in humans and many other animals. Our previous data indicated that miR-182 levels increase 15.55-fold and pleiotrophin (PTN) levels decrease 20.97-fold in the receptive endometrium (RE, D15) compared with the pre-receptive endometrium (PE, D5) in dairy goats. The present study shows that miR-182 is widely expressed in different tissues of dairy goats and that its expression levels are regulated by E2 and P4 in endometrial epithelium cells (EECs). We confirmed that PTN is a target of miR-182 and that miR-182 regulates the protein levels of AKT, Bcl-2, FAS, MAPK, Caspase-3 and SP1 in EECs. Furthermore, miR-182 up-regulates or maintains the expression levels of osteopontin (OPN), cyclooxygenase-2 (COX-2) and prolactin receptor (PRLR) in EECs, suggesting that miR-182 is an important regulatory factor in the construction of endometrial receptivity in dairy goats. In conclusion, miR-182 participates in the development of endometrial receptivity by down-regulating PTN and affecting the expression of select apoptosis-related genes and increasing or maintaining the expression levels of OPN, COX-2 and PRLR in the EECs of dairy goats.

Increased Uterine NK cell numbers and perforin expression during the implantation phase in IVF Cycles with GnRH Antagonist Protocol

GnRH antagonist negatively affects endometrial receptivity in in vitro fertilization (IVF) cycles, however, its underlying mechanism remains unclear. To explore its target molecules, we studied endometria in the window phase of fixed GnRH antagonist, low-dose flexible GnRH antagonist, GnRH agonist long protocol, and untreated control groups. There were 384 differentially expressed genes (DEGs) in the fixed antagonist group with greater than twofold expression change compared with the control group and 197 DEGs between the fixed antagonist and agonist groups, the majority of which were associated with the natural killer (NK) cell-mediated cytotoxicity pathway. We then analysed the PRF1 and FASLG protein levels. The perforin level were significantly higher in both the antagonist groups than in other two groups, and was higher in the fixed antagonist group. Similarly, the uNK cell numbers were higher in the antagonist groups, and the highest uNK cell number occurred in the fixed group (p < 0.05). No significant differences existed in the Fas ligand levels and apoptosis rates among the three treatment groups, but were higher in the treatment groups than the control group. Together, these data indicate that GnRH antagonist may increase the uNK cell numbers and perforin expression, and this effect may be dose-dependent.

Protective effects of hydrogen sulfide inhalation on oxidative stress in rats with cotton smoke inhalation-induced lung injury

The aim of the present study was to investigate the mechanism by which hydrogen sulfide (H₂S) inhalation protects against oxidative stress in rats with cotton smoke inhalation-induced lung injury. A total of 24 male Sprague-Dawley rats were separated randomly into four groups, which included the control, H₂S, smoke and smoke + H₂S groups. A rat model of cotton smoke inhalation-induced lung injury was established following inhalation of 30% oxygen for 6 h. In addition, H₂S (80 ppm) was inhaled by the rats in the H₂S and smoke + H₂S groups for 6 h following smoke or sham-smoke inhalation. Enzyme-linked immunosorbent assays were performed to measure various indices in the rat lung homogenate, while the levels of nuclear factor (NF)-κBp65 in the lung tissue of the rats were determined and semiquantitatively analyzed using immunohistochemistry. In addition, quantitative fluorescence polymerase chain reaction was employed to detect the mRNA expression of inducible nitric oxide synthase (iNOS) in the rat lung tissue. The concentrations of malondialdehyde (MDA), nitric oxide (NO), inducible iNOS and NF-κBp65, as well as the sum-integrated optical density of NF-κBp65 and the relative mRNA expression of iNOS, in the rat lung tissue from the smoke + H₂S group were significantly lower when compared with the smoke group. The concentrations of MDA, NO, iNOS and NF-κBp65 in the H₂S group were comparable to that of the control group. Therefore, inhalation of 80 ppm H₂S may reduce iNOS mRNA transcription and the production of iNOS and NO in rats by inhibiting NF-κBp65 activation, subsequently decreasing oxidative stress and cotton smoke inhalation-induced lung injury.