Ovarian Hyperstimulation Reduces Vascular Endothelial Growth Factor-A During Uterine Receptivity

Xiaoyao powder improves endometrial receptivity via VEGFR-2-mediated angiogenesis through the activation of the JNK and P38 signaling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Xiaoyao powder (XYP) is a traditional Chinese medicine formula which has wide scope of indications related to liver stagnation, reconcile qi and blood in TCM syndrome. Infertility can induce similar symptoms and signs to the clinical features of liver stagnation syndrome, the treatment of infertility by soothing the liver is obvious. XYP can increase the clinical pregnancy rate, follicle development, oocyte quality and improve endometrial receptivity. However, its underlying pharmacological mechanism of improving endometrial receptivity is unclear.

AIM OF THE STUDY

The aim of the study was to investigate the effect of XYP on pregnancy rates and endometrial angiogenesis, to determine the potent mechanism in association with the pro-angiogenic behavior which closely related to improving endometrial receptivity.

MATERIALS AND METHODS

We established an animal model exhibiting decreasing endometrial receptivity by controlled ovarian hyperstimulation and a human endometrial microvascular endothelial cell (HEMEC) model. Endometrial morphology was observed by hematoxylin-eosin staining and Scanning electron microscopy. Western blot and qRT-PCR analysis were used to detect expression of PCNA, Cyclin D1, MMP9 and MAPK signaling pathway. Scratch-wound assay and tube formation assay were used to observe HEMEC migration and tubulogenesis.

RESULTS

The results demonstrated that XYP pretreatment could improve endometrial receptivity, which leads to high pregnancy rates. In the endometrium, XYP facilitated angiogenesis by promoting tube formation. XYP could enhance HEMEC proliferation and migration induced by VEGF, which were observed by the microscope and Scratch-wound assays. XYP promoted HEMEC proliferation and migration via the p38 and JNK MAPK signaling pathways.

CONCLUSION

XYP promotes HEMEC proliferation and migration via the P38 and the JNK MAPK signaling pathways, which contribute to the endometrial angiogenesis mediated by VEGFR-2 that is favorable for endometrial receptivity. We firstly elucidated the molecular mechanisms by which XYP improved endometrial receptivity by promoting angiogenesis.

PPP2R2A affects embryonic implantation by regulating the proliferation and apoptosis of Hu sheep endometrial stromal cells

Embryonic implantation is a complex reproductive physiological process in mammals. Although several endometrial proteins affecting embryonic implantation have been reported in the past, there are still potential endometrial proteins that have been neglected, and their specific regulatory mechanisms are unclear. This study demonstrated that protein phosphatase 2A regulatory subunit B55α (PPP2R2A) served as a novel regulator in medication of sheep embryonic implantation in vitro. Our results showed that sheep PPP2R2A encoded 447 amino acids and shared 91.74%-92.36% amino acid sequences with its orthologs compared with other species. Meanwhile, PPP2R2A was widely expressed in sheep uterine tissues, and it could regulate the expression levels of key regulators of embryonic implantation in endometrial stromal cells (ESCs). Knockdown of PPP2R2A significantly inhibited cell proliferation by blocking cell cycle transfer G0/G1 into S phase accompanied by downregulation of CDK2, CDK4, CCND1, CCNE1 and upregulation of P21. In contrast to PPP2R2A overexpression, PPP2R2A interference greatly promoted cell apoptosis and the expression of BAX, CASP3, CASP9 and BAX/BCL-2. Taken together, these results suggest that PPP2R2A, as a novel regulatory factor, affects embryonic implantation via regulating the proliferation and apoptosis of Hu sheep ESCs in vitro.

Estrogen Regulates Endoplasmic Reticulum Stress-Mediated Apoptosis by ERK-p65 Pathway to Promote Endometrial Angiogenesis

Estrogen (17β-oestradiol, E2) plays an essential role in endometrial receptivity and has been shown to stimulate angiogenesis via E2-ERα (estrogen receptor)-mediated upregulation of VEGF transcription. In this study, we have tried to decipher the mechanism of E2-promoting angiogenesis. We pre-incubated human endometrial microvascular endothelial cells (HEMECs) with E2 and performed western blotting, qRT-PCR, and cellular immunofluorescence experiments. We observed that E2 treatment of HEMECs increased ERα expression and reduced the expression of GRP78, which led to reduction of Caspase 3 expression by the CHOP pathway. In addition, E2 not only activated ERK signaling pathway but also inhibited p65 phosphorylation along with its translocation from nucleus to the cytoplasm, and subsequently inhibiting GRP78 expression, which led to inhibition of cell apoptosis. Together, these findings highlight the novel mechanism underlying E2-mediated improvement in endometrial angiogenesis through the ERK-p65 signaling pathway.

Ovarian stimulation and exogenous progesterone affect the endometrial miR-16-5p, VEGF protein expression, and angiogenesis

Angiogenesis, where vascular endothelial growth factor (VEGF) is critically involved, is an important factor in endometrial receptivity. Angio-miRNAs form a special class of microRNAs (miRNAs) that target angiogenic genes and regulate angiogenesis. Various studies have shown that ovarian stimulation and exogenous progesterone affect endometrial vascular density. The present research aimed to assess the impact of HMG/HCG and progesterone on miR-16-5p, VEGF protein expression, and angiogenesis in the mouse endometrium during the preimplantation period. Forty adult female mice were divided into four groups: 1) control, 2) ovarian stimulation (HMG and 48 h after HCG IP), 3) progesterone (progesterone IP for 3 days), 4) ovarian stimulation + progesterone (HMG and 48 h after HCG IP) + (progesterone IP for 3 days) groups.The mice were sacrificed 96 h following HCG administration. miR-16-5p, VEGF protein expression, and CD31-positive cell (Endothelial cell) density were specified.The results showed that endothelial cell density,VEGF protein, and miR-16-5p expression increased in all treatment groups, with the maximum increase belonging to the ovarian stimulation + progesterone group. This study provides evidence that ovarian stimulation and progesterone administration enhance endometrial angiogenesis through VEGF protein upregulation. Furthermore, except for miR-16-5p, other miRNAs and molecules appear to be involved in angiogenic pathways, thereby requiring further studies.

Evaluation of Diabetes Effects on the Expression of Leukemia Inhibitory Factor and Vascular Endothelial Growth Factor A Genes and Proteins at the Time of Endometrial Receptivity after Superovulation in Rat Model

Background:

Diabetes, a major metabolic disorder, seems to affect the fertility rates of women in various ways. Due to the uncertainty of the effects of diabetes along with superovulation treatment on the infertility, we investigate the effects of ovulation induction treatment as therapeutic approach on the expression of leukemia inhibitory factor (LIF) and vascular endothelial growth factor A (VEGFA) as two main factors which are involved in the implantation in the streptozotocin (STZ)-induced type 1 diabetic rats.

Materials and Methods:

Type 1 diabetes was induced by injections of STZ in Wistar rats. The animals were kept in diabetic conditions for 4 weeks, while some were treated with insulin for treatment. After treatment, the ovulation was induced by human menopausal gonadotropin (hMG) and human chorionic gonadotropin (hCG). The rats were then sacrificed and the expression of LIF and VEGFA was checked by immunohistochemistry staining method, and the relative expression of LIF and VEGFA was measured by quantitative reverse transcription polymerase chain reaction (RT-PCR) and Western blotting methods.

Results:

It was observed that diabetes and insulin treatment for diabetes altered the expression of Lif and VEGFA in both mRNA and protein levels. However, superovulation treatment seems to ameliorate this alternation for both factors.

Conclusion:

According to our results, diabetes and insulin therapy could alter the expression of Lif and VEGFA genes and proteins that are effective in endometrial receptivity and implantation process. It seems in diabetic cases, the effect of hCG and hMG therapy by itself could regulate the level of expression and presence of these two genes and proteins.

The ameliorating effects of Bushen Tiaoxue Granules and Kunling Wan on impaired angiogenesis and endometrial receptivity in rats following controlled ovarian hyperstimulation

OBJECTIVE

To investigate the effects of Bushen Tiaoxue Granules and Kunling Wan, the two Chinese medicines, on vascular dysfunction and the impairment of endometrial receptivity caused by controlled ovarian hyperstimulation and its underlying mechanism.

METHODS

Female Sprague Dawley rats with regular estrous cycle were enrolled and given Bushen Tiaoxue Granules or Kunling Wan by gavage for 12 days, and then, controlled ovarian hyperstimulation model was induced. We assessed endometrial microvessels, endometrial blood flow, levels of estradiol and progesterone in serum, vascular endothelial growth factor A upstream molecules estrogen and progesterone receptors in the endometrium, and pregnancy outcome.

RESULTS

Pre-treatment of Bushen Tiaoxue Granules or Kunling Wan increases endometrial blood flow of controlled ovarian hyperstimulation rats, up-regulates vascular endothelial growth factor A and microvessels, improves the endometrial morphology of controlled ovarian hyperstimulation rats during implantation, decreases the super physiological concentration of estradiol and progesterone in serum, and increases the expression of vascular endothelial growth factor A upstream molecules estrogen and progesterone receptors in the endometrium. In addition, Bushen Tiaoxue Granules or Kunling Wan elevates the lysophosphatidic acid receptor 3 that participates in vascularization and increases the expression of leukemia inhibitory factor through up-regulating the expression of p53 in the endometrium, ultimately affecting pregnancy outcome.

CONCLUSION

This study demonstrated Bushen Tiaoxue Granules or Kunling Wan as a potential strategy for prevention of impairment in angiogenesis and endometrial receptivity induced by controlled ovarian hyperstimulation.

Myeloid-Derived Suppressor Cells Are Regulated by Estradiol and Are a Predictive Marker for IVF Outcome

In vitro fertilization (IVF) is an effective means to treat infertility, but the pregnancy rate is still unsatisfactory and reliable markers to predict pregnancy outcome are ill-defined. Myeloid-derived suppressor cell (MDSC) are critically involved in decisions related to the acceptance or rejection of foreign fetal antigens by the maternal immune system. However, factors that regulate peripheral blood MDSC during pre-pregnancy are poorly defined. Thus, the goal of this study was to assess the relationships among serum estradiol (E₂) and endothelial growth factor (VEGF) levels, MDSC ratios, and pregnancy outcome associated with IVF. Patients undergoing IVF treatment (n = 54) were recruited from January to June 2018. Levels of E₂ and VEGF were measured by ELISA, MDSC ratios among peripheral blood mononuclear cells (PBMC) were detected by flow cytometry, and the crosstalk among these parameters was analyzed. A receiver operating characteristic curve (ROC) of MDSC levels was plotted to assess this measure as an independent predictive factor for pregnancy. In addition, we analyzed the possible involvement of molecular pathways by bioinformatics. When E₂ levels were <4,000 pg/ml, MDSC proportion was positively correlated with serum E₂ and VEGF levels. However, when E₂ levels were >4,000 pg/ml, MDSC ratio and VEGF levels were negatively correlated with E₂. A ROC curve revealed that the percentage of MDSC had better sensitivity and specificity at a concentration of 8.22% (0.875 and 0.75, respectively; area under the curve (AUC) = 0.859) to predict pregnancy success, based on multiple logistic regression analysis. Furthermore, we found 12 target genes of E₂ and VEGF, and also functional genes related to MDSC, indicating potential protein-protein interactions underlying these associations. In summary, we showed that E₂, depending on its concentration, might play a dichotomous role in influencing the MDSC proportion by regulating VEGF. In IVF patients, an increased MDSC ratio among PBMC was highly correlated with elevated pregnancy rates, independent of the effects of E₂, which might provide new insight into immune-related miscarriage and IVF failure.