Down-regulation of uterine LIF expression induced by the hormonal level disorder causes embryo implantation loss after mice exposed to carbon disulfide at peri-implantation

Association of miRNA-145 with the occurrence and prognosis of hydrosalpinx-induced defective endometrial receptivity

MiR-145 is reported to facilitate inflammation and is also associated with unsuccessful embryonic implantation. Whether miR-145 mediates inflammatory response underlying hydrosalpinx-induced defective endometrial receptivity (ER) remains unclear, and this study attempted to clarify this point. Endometrium samples were collected from hydrosalpinx patients (case, n = 243) and patients with tubal patency/obstruction (control, n = 187). The peripheral blood samples of cases and controls were collected to determine the genotypes of miR-145 SNPs. The value of miR-145 expression in the diagnosis and prognostic estimation of hydrosalpinx was assessed using ROC curve and regression analysis, respectively. Lipopolysaccharide (LPS) cell model was established with endometrial cells, and cells were transfected with miR-145 mimic, inhibitor, or negative control. MiR-145 and cytokine levels were quantified by quantitative reverse transcription PCR or western blot. MiR-145 expression was significantly higher in hydrosalpinx compared to control group, and high miR-145 expression was significantly associated with moderate/severe tube lesion, high pulsatility index (>1.06), and high resistance index (>0.61) in hydrosalpinx patients. ROC curve analysis indicated that monitoring miR-145 expression may be useful for the diagnosis of hydrosalpinx (AUC = 0.704). A alleles of rs41291957 (G>A) and rs353292 (G>A) were significantly associated with an increased risk of hydrosalpinx compared to G allele (p < 0.05), yet the mutant allele of rs353291 (A>G) and rs4705343 (T>C) significantly reduced susceptibility to hydrosalpinx compared to the wild type allele. Treatments with miR-145 mimic and LPS in endometrial cells significantly increased the levels of transforming growth factor-β1, tumor necrosis factor -α, interleukin (IL)-6, and IL-8 compared to negative control, while treatment with miR-145 inhibitor decreased the cytokine levels. In conclusion, abnormally expressed miR-145 may be involved in hydrosalpinx-induced ER defects by regulating the inflammatory response.

Carbon disulfide induced decidualization disorder in the mice uterus at the window of implantation

Carbon disulfide (CS₂) is regarded as a common occupational poison that is widely used in the textile industry in China. Our previous research suggests that CS₂ can induce significant implantation disorders in pregnant mice; however, the specific mechanism remains unclear. Uterine conception in mice must undergo decidualization, which is the prerequisite for propitious blastocyst implantation into the endometrium. Therefore, in this study, we established models of pregnant mice to explore the toxic effects of CS₂ on decidualization to elucidate the basic mechanism of implantation disorder after CS₂ exposure. The uterine tissues were immediately collected according to the predetermined endpoints to measure the expression levels of IGFBP1 and PRL (markers of decidualization differentiation), IL-11 (representing the secretory function of decidual cells), AKT and pAKT by western blotting, RT-PCR, immunohistochemical staining, H&E staining and ELISA. N-carbamoyl glutamic acid (NCG) acted as an agonist of AKT to verify the upstream regulatory mechanism of decidualization disorder by CS₂. The results showed that the normal reaction of decidual transformation was obviously disrupted by CS₂ upon 3.5 dpc and 4.5 dpc exposure. The blastocyst did not adhere to the epithelium after 3.5 dpc-exposure and did not invade the endometrium after 4.5 dpc-exposure, resulting in its suspension in the uterine cavity, stagnation and eventual loss. The proteins expression levels were decreased by 95.2% for IGFBP1 and 76.2% for PRL at the 4.5 dpc endpoint after 3.5 dpc CS₂ exposure compared with the control. Simultaneously, the mRNA and protein expression levels of IL-11 in uterine tissues were significantly reduced by CS₂, and consistent decreasing trends over time were observed for IGFBP1 and PRL, compared with the control. Additionally, the ratio of pAKT/AKT protein expression was decreased by 72.2% and 94.8% at 12 h and 18 h after 3.5 dpc exposure and by 53.3% and 74.3% at 6 h and 12 h after 4.5 dpc exposure, respectively, compared with the corresponding controls. Furthermore, NCG could recover the IGFBP1 and PRL protein expression, which was increased by 27.5% and 52.3% at 4.5 dpc and 6.5 dpc, respectively, after 3.5 dpc exposure for IGFBP1 and by 30.3% at 6.5 dpc after 4.5 dpc exposure for PRL, compared with CS₂ exposure alone. Collectively, this study suggested that the decidualization disorder caused by CS₂ at the window of implantation in pregnant mice, which is triggered by pAKT, contributed to the implantation disorder and eventually led to embryo loss. It is worth noting that our study may provide a new perspective and reference for exploring the toxic mechanism of implantation disorder and even infertility in harmful circumstances.

Regulatory mechanisms of endometrial decidualization and pregnancy-related diseases

Endometrial decidualization is one of the earliest changes by which the uterus adapts to pregnancy. During this period, the endometrium undergoes complex changes in its biochemistry, physiology, and function at various levels, providing a suitable microenvironment for embryo implantation and development. Favorable decidualization lays an essential foundation for subsequent gestation, without which pregnancy failure or pregnancy complications may occur. The interaction between pregnancy-related hormones and cytokines produced by embryonic and uterine cells is known to be essential for decidualization, in which some transcription factors also play pivotal roles. Increasing evidence has revealed the importance of metabolism in regulating decidualization. Here, we summarize and discuss these crucial elements in decidualization and the relationship between decidualization and pregnancy complications. A better comprehension of these issues should help to improve the prediction of pregnancy outcomes and the use of appropriate intervention.

The suppressed autophagy induced by carbon disulfide could be rescued by N-carbamoyl glutamate during the window of embryo implantation in mice

OBJECTIVES

To explore the effects of carbon disulfide (CS₂) and N-carbamoyl glutamate (NCG) on autophagy during the window of embryo implantation in mice and whether dietary NCG supplementation can promote embryo implantation in case of CS₂ exposure.

METHODS

Pregnant mice that received single intraperitoneal injection of CS₂ on Gestational day (GD)4 were fed basal diet with or without NCG supplementation from GD1 to endpoints. The control mice were injected solvents. There were four endpoints (GD5, GD6, GD7 and GD9 endpoints) in each group. The uterus was collected on endpoints to detect autophagy-related markers by using the methods of transmission electron microscopy (TEM), immunohistochemistry (IHC), quantitative real-time polymerase chain reaction (qRT-PCR) and ELISA.

RESULTS

The P62 brown punctate staining increased in CS₂ exposure group and reduced after dietary NCG supplementation, which was opposite with LC3B, Beclin1 and ATG5 on GD5 endpoint. Simultaneously, P62 protein expression raised 43.33% on GD5 endpoint (p < 0.01) when exposed to CS₂ and descended to the control level after NCG supplementation. The rate of decline of LC3B and Beclin1 proteins were 27.04% (p < 0.01) and 23.27% (p < 0.05) on GD5 endpoint, 20.20% (p < 0.05) and 11.30% on GD7 endpoint in CS₂ exposure group, respectively, then NCG supplementation caused the LC3B and Beclin1 protein expression to rise in different degrees. Comparatively, the mRNA expression of all autophagy-related gene changed more apparently on three endpoints than the protein expression. The images of TEM showed that nearly no autophagosome could be seen in CS₂ exposure group, while dietary NCG supplementation increased the number of autophagosome obviously on GD5 endpoint. The number of implanted embryos which declined due to CS₂ exposure returned to normal in NCG supplementation group.

CONCLUSIONS

Dietary NCG supplementation could rescue the suppressed autophagy induced by CS₂ in the window of implantation and increase the number of implanted embryos.

Carbon Disulfide Induces Embryo Implantation Disorder by Disturbing the Polarization of Macrophages in Mice Uteri

Carbon disulfide (CS₂) induces embryo implantation disorders. Macrophages participate in the process of pregnancy. Therefore, we want to explore the effects of CS₂ exposure on polarization and immune function of macrophages in pregnant mice uteri. The exposure times were gestation days 3 (GD3), 4 (GD4), and 5 (GD5), and the observation end points were arranged in a time series after CS₂ exposure. The uterine tissues were collected to detect the expression levels of macrophages cytokines (IL-6, IL-12, TGF-β1, and Vegf-a) and downstream regulatory cytokines of Th1-type (IL-2 and IFN-γ) and Th2-type (IL-10 and IL-4) by flow cytometry, ELISA, and q-PCR. The results showed that, compared with the controls, the ratios of M1/M2 macrophages in the endometrium significantly increased by 96%, 110%, and 177% at the GD4, GD6, and GD7 observation end points after GD3 exposure and increased about 3.88-fold and 2.37-fold at the GD6 and GD7 observation end points after GD4 exposure, respectively. In contrast, the ratio of M1 and M2 macrophages significantly reduced by 53% at the GD5 observation end point after GD3 exposure. Meanwhile, the expression levels of IL-6 were significantly increased about 2.00-fold for mRNA and 1.60-fold for protein at GD4 observation end points after GD3 exposure, and the mRNA levels of IL-12 increased about 3.61-fold at the GD6 observation end points after GD4 exposure. The mRNA levels of TGF-β1 were significantly decreased by 41%, 25%, and 20% at the GD7 observation end points after exposure at GD3, GD4, and GD5, and the expression levels of Vegf-a mRNA and protein were decreased. Furthermore, the ratio of IL-2/IL4, IL-2/IL-10, IFN-γ/IL-4, and IFN-γ/IL-10 in the uterine tissue was significantly increased at the exposure groups. These findings suggest that the imbalanced polarization of macrophages is the key regulator in the progress of CS₂-induced embryo loss.

Abnormal expression of estrogen receptor is associated with thin endometrium

This study was conducted to investigate the association of estrogen receptor (ER) and progesterone receptor (PR) expressions with thin endometrium. Patients with endometrial thickness of less than 7 mm were classified as the study group, while the control group was comprised of patients with endometrial thickness of 7 to 14 mm. The expressions of ER and PR were detected with semi-quantitative immunohistochemical analysis, and the differences were compared between the two groups. The expression of ER was significantly decreased (p < .05) in the stromal cells of thin endometrium during both proliferative and secretory phases as compared to those of normal endometrium. Likewise, ER expression was found to be lower in the glandular cells of thin endometrium than those of normal endometrium during proliferative phase. However, no significant differences were observed for the expression of PR in both glandular and stromal cells between the two groups. Thin endometrium was associated with reduced expression of ER in stromal cells both during proliferative and secretory phase, but in glandular epithelial cells only during proliferative phase.

Mitochondrial separation protein inhibitor inhibits cell apoptosis in rat lungs during intermittent hypoxia

Obstructive sleep apnoea (OSA) is a very common sleep and breathing disorder that occurs in worldwide. It is important to develop a more effective treatment for OSA to overcome lung cell apoptosis during intermittent hypoxia (IH). A mitochondrial separation protein inhibitor (Mdivi-1) has been demonstrated to be a powerful tool for inhibiting apoptosis. In the present study, the protective effect and possible mechanism of apoptosis in lung cells during IH was investigated using in vivo and in vitro experiments. Following IH exposure for 4 weeks, the lung tissues of Sprague Dawley rats exhibited interstitial lesions, while Mdivi-1 reduced these pulmonary interstitial lesions. B-cell lymphoma (Bcl)-2 mRNA and protein expression levels were decreased however caspase-3, caspase-9 and dynamin-related protein 1 (Drp-1) mRNA and protein expression levels were increased. Following Mdivi-1 intervention, Bcl-2 mRNA and protein expression levels were increased while caspase-3, caspase-9 and Drp-1 mRNA and protein expression levels were decreased (P<0.05). After exposure to IH for 12 h, the apoptosis rate of WTRL1 cells in rats increased gradually with the IH time (P<0.05). Bcl-2 mRNA and protein expression levels were decreased, whereas caspase-3, caspase-9, cytochrome C (Cyt-C) and Drp-1 mRNA levels were increased, and caspase-3, caspase-9 and Drp-1 protein expression levels were increased. After Mdivi-1 intervention, Bcl-2 mRNA and protein expression levels were increased but caspase-3, caspase-9, Cyt-C and Drp-1 mRNA levels were decreased along with caspase-9, Cyt-C and Drp-1 protein expression levels which were decreased (P<0.05). The results of the present study suggest that Mdivi-1 may be a potential agent for treating OSA because it inhibits the mitochondrial pathway and reduces apoptosis.

Activating transcription factor 3 promotes embryo attachment via up-regulation of leukemia inhibitory factor in vitro

BACKGROUND

A receptive endometrium is essential for maternal-embryonic molecular communication during implantation. However, the specific molecular regulatory mechanisms of the endometrial capacity remain poorly understood. Here, we examined activating transcription factor 3 (ATF3) expression in human endometria and the functional effect of ATF3 on embryo attachment in vitro.

METHODS

Immunohistochemistry (IHC) was used to assess the ATF3 expression patterns in human endometria. Quantitative real-time PCR (qRT-PCR), western blotting and immunofluorescence (IF) studies were applied to explore ATF3 expression in Ishikawa cells upon estrogen (E₂) and medroxyprogesterone acetate (MPA) treatment. qRT-PCR and western blotting were performed to inspect LIF (leukemia inhibitory factor) expression after enhancement or inhibition of ATF3, and a luciferase reporter assay and ChIP-PCR were used to confirm the regulatory mechanism of ATF3 to LIF. Endometrial epithelial capacity was assessed by an in vitro model of attachment of BeWo spheroids to Ishikawa cells. Western blotting was performed to compare the expression of ATF3 in endometrial samples of recurrent implantation failure (RIF) patients with that in samples from fertile women (FER) who had undergone no less than one successful embryo transplantation.

RESULTS

ATF3 was located in human endometrial epithelial cells and stromal cells and was significantly induced by E₂ and MPA in Ishikawa cells. Adenovirus-mediated overexpression of ATF3 in Ishikawa cells activated LIF promoter activity and enhanced its expression. Accordingly, the stimulation of BeWo spheroid adhesion promoted by ATF3 was inhibited by pretreatment with a specific antibody against LIF via the antibody-blocking assay. Moreover, ATF3 was aberrantly decreased in the endometria of RIF patients.

CONCLUSIONS

Our findings suggest that ATF3 plays a significant role in regulating human endometrial receptivity and embryo attachment in vitro via up-regulation of leukemia inhibitory factor.

TRIAL REGISTRATION

Construction and management of the Nanjing multi-center biobank. No. 2013-081-01 . Registered 10 Dec. 2013.