Increased endometrial placenta growth factor (PLGF) gene expression in women with successful implantation

Expression of vascular endothelial growth factor A (VEGFA), placental growth factor (PlGF) and insulin-like growth factor 1 (IGF-1) in serum from women undergoing frozen embryo transfer

VEGFA, PlGF and IGF-1 are three main angiogenic factors which play significant roles in embryo implantation. However, the relationship between serum expressions of VEGFA, PlGF and IGF-1 and pregnancy outcomes has not been fully illustrated. In this study, serum specimens were collected precisely on day 7 after the LH surge in a natural non-conception cycle from 38 infertile patients who underwent frozen embryo transfer (FET) treatment. ELISA was used to determine the concentrations of VEGFA, PlGF and IGF-1. Serum levels of VEGFA, PlGF and IGF-1 were compared between patients who conceived (n=25) and who did not (n=13). Correlation and linear regression analyses were used to investigate the correlations of serum angiogenic factors and β-hCG MoM levels in the pregnant group. The results demonstrated that no significant difference was found in serum VEGFA, PlGF or IGF-1 concentration between pregnant and non-pregnant women. Spearman correlation analysis revealed a positive correlation between IGF-1 concentration and β-hCG level in pregnant participants (rs = 0.490, p = 0.013). In conclusion, serum IGF-1 level correlated positively with β-hCG level in pregnant women, which may provide information on the prognostic value of IGF-1 in this group of women.

CREB1 Is Involved in miR-134-5p-Mediated Endometrial Stromal Cell Proliferation, Apoptosis, and Autophagy

The successful establishment of endometrial receptivity is a key factor in ensuring the fertility of ewes and their economic benefits. Hu sheep have attracted attention due to their high fecundity and year-round estrus. In this study, we found that in the luteal phase, the uterine gland density, uterine coefficient, and number of uterine caruncles of high-fertility Hu sheep were higher than those of low-fertility Hu sheep. Thousands of differentially expressed genes were identified in the endometrium of Hu sheep with different fertility potential using RNA sequencing (RNA-Seq). Several genes involved in endometrial receptivity were screened using bioinformatics analysis. The qRT-PCR analysis further revealed the differential expression of cAMP reactive element binding protein-1 (CREB1) in the Hu sheep endometrium during the estrous cycle. Functionally, our results suggested that CREB1 significantly affected the expression level of endometrial receptivity marker genes, promoted cell proliferation by facilitating the transition from the G1 phase to the S phase, and inhibited cell apoptosis and autophagy. Moreover, we observed a negative linear correlation between miR-134-5p and CREB1 in the endometrium. In addition, CREB1 overexpression prevented the negative effect of miR-134-5p on endometrial stromal cell (ESC) growth. Taken together, these data indicated that CREB1 was regulated by miR-134-5p and may promote the establishment of uterine receptivity by regulating the function of ESCs. Moreover, this study provides new theoretical references for identifying candidate genes associated with fertility.

Expression of placental growth factor and a disintegrin and metalloprotease with a thrombospondin type motifs 1-4-8 during the three trimesters of rat pregnancy at the maternal-fetal interface

The functional roles of the a disintegrin and metalloprotease with a thrombospondin type motifs (ADAMTS) gene family in reproductive physiology, reproductive organs developments and adult reproductive health are still under investigation. The expression of the anti-angiogenic proteases ADAMTS-1, ADAMTS-4 and ADAMTS-8 in placental angiogenesis at various stages of pregnancy also remains unclear. The purpose of this study was therefore to determine the localization and expression of the ADAMTS-1, ADAMTS-4 and ADAMTS-8 proteins during the three stages of pregnancy in rats. Maternal-fetal tissue samples were collected on Days 5, 12 and 19 of each trimester, corresponding to the first, second and third trimesters. The expression of placental growth factor (PlGF) and ADAMTS-1, ADAMTS-4 and ADAMTS-8 at the maternal-fetal interface was examined using immunohistochemistry and western blot at three distinct phases of pregnancy. ADAMTS-1, ADAMTS-4 and ADAMTS-8 were detected in all three trimesters of pregnancy. The relative amount of PIGF increased in the first trimester and decreased significantly in the third trimester (p < 0.05). The expression of ADAMTS-1 and ADAMTS-4 was significantly higher in the second (p < 0.05) and third trimesters (p < 0.01) compared to the first trimester. However, no statistically significant change was observed in ADAMTS-8 expression between trimesters. The ADAMTS exhibiting the highest expression during the first trimester was ADAMTS8. These findings indicate that the expression of ADAMTS-1, ADAMTS-4 and ADAMTS-8 in the three different stages of rat pregnancy may be involved in the modulation of decidualization, morphogenesis and angiogenesis. Periodic changes in ADAMTS expression are thought to be regulated by gonadal steroids.

Follicular fluid PlGF and IVF/ICSI outcomes among PCOS and normo-ovulatory women using different controlled hyperstimulation protocols: A prospective case-control study

Background

Gonadotropin-releasing hormone (GnRH) analogues are used to prevent premature luteinizing hormone (LH) surge during In-Vitro Fertilization. However, the follicular fluid levels of the Placental growth factor (FF PlGF), the novel angiogenic factor, differ significantly between GnRH-agonist and GnRH-antagonist protocols. Thus, we compared the IVF/ICSI outcomes and their correlations with FF PlGF levels in polycystic ovary syndrome (PCOS) and normo-ovulatory women during different hyperstimulation protocols.

Methods

This case-control study is a re-analysis of two prospective trials that were conducted on women who were referred to Orient Hospital, Damascus, Syria, from December 2019 to August 2021. A total of 75 PCOS-women (PCOS-Agonist, n = 53; PCOS-Antagonist, n = 22) and 83 normo-ovulatory women (Control-Agonist, n = 50; Control-Antagonist, n = 33) were included. Follicular fluid samples were collected on retrieval day.

Results

Although PCOS-women were stimulated using lower gonadotropin doses, the Ovarian-sensitivity-indexes were higher in PCOS-groups (PCOS-Agonist vs Control-Agonist; P-value <0.001), (PCOS-Antagonist vs Control-Antagonist; P-value = 0.042). However, FF PlGF levels, maturation rate, fertilization rate, and oocytes morphology were comparable between PCOS and controls independently of the protocol used. Interestingly, FF PlGF levels were positively correlated with Ovarian-sensitivity-indexes in the PCOS-Antagonist, Control-Agonist, and Control-Anta groups, but not in the PCOS-Agonist group. Nevertheless, FF PlGF levels were comparable between pregnant and non-pregnant women in all studied groups.

Conclusions

Although PCOS exaggerates ovarian response to stimulation irrespective of the protocol used, it does not have a detrimental impact on oocytes morphology or competence. Moreover, FF PlGF levels could be a marker of the ovarian response other than a predictor of pregnancy achievement.

Effect of hydroxychloroquine on antiphospholipid antibodies-inhibited endometrial angiogenesis

BACKGROUND

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by thrombotic events and/or pregnancy morbidity (≥3 recurrent early miscarriage or fetal death or a prematurity <34 weeks of gestation) with persistently positive antiphospholipid antibodies (aPLs). It is reported that aPLs damage the placental tissue by binding to β2-glycoprotein I (β2GPI) on the surface of trophoblast and endothelial cells. Hydroxychloroquine (HCQ) is considered to be beneficial in the treatment of obstetrical APS and shown to restore the aPL-inhibited invasion and differentiation of trophoblast. However, not enough evidence exists regarding the effect of HCQ on endometrial angiogenesis. The aim of our study was to assess whether HCQ has an effect on aPL-inhibited endothelial angiogenesis.

METHODS

In this research, to explore the effect of HCQ for angiogenesis, we investigated: (1) Human umbilical vein endothelial cells (HUVECs) viability by CCK-8; (2) HUVECs migration by wound healing; (3) HUVEC angiogenesis by Matrigel assay in vitro; (4) mRNA expression of MMP-2 and VEGF by real-time quantitative Polymerase Chain Reaction (RT-PCR); (5) protein expression of VEGF, MMP-2 by western blot.

RESULTS

We found that HCQ treatment significantly restored the expression of aPL-inhibited VEGF and MMP-2. HCQ restored aPL-inhibited HUVEC proliferation, migration, and angiogenesis in vitro.

CONCLUSION

In conclusion, aPLs inhibit HUVECs angiogenesis, however, HCQ can restore the effect of aPL-inhibited HUVECs migration and angiogenesis in vitro, demonstrating its beneficial therapeutic role in obstetrical APS.

Role of Vascular Endothelial Growth Factor (VEGF) in Human Embryo Implantation: Clinical Implications

Vascular endothelial growth factor (VEGF) is a well-known angiogenic factor that plays a critical role in various physiological and pathological processes. VEGF also contributes to the process of embryo implantation by enhancing embryo development, improving endometrial receptivity, and facilitating the interactions between the developing embryo and the endometrium. There is a correlation between the alteration of VEGF expression and reproductive failure, including recurrent implantation failure (RIF) and recurrent miscarriage (RM). In order to clarify the role of VEGF in embryo implantation, we reviewed recent literature concerning the expression and function of VEGF in the reproductive system around the time of embryo implantation and we provide a summary of the findings reported so far. We also explored the effects and the possible underlying mechanisms of action of VEGF in embryo implantation.

PreImplantation Factor in endometriosis: A potential role in inducing immune privilege for ectopic endometrium

Endometriosis is a chronic inflammatory condition characterised by the growth of endometrial epithelial and stromal cells outside the uterine cavity. In addition to Sampson’s theory of retrograde menstruation, endometriosis pathogenesis is facilitated by a privileged inflammatory microenvironment, with T regulatory FoxP3⁺ expressing T cells (Tregs) being a significant factor. PreImplantation Factor (PIF) is a peptide essential for pregnancy recognition and development. An immune modulatory function of the synthetic PIF analog (sPIF) has been successfully confirmed in multiple animal models. We report that PIF is expressed in the epithelial ectopic cells in close proximity to FoxP3⁺ stromal cells. We provide evidence that PIF interacts with FoxP3⁺ cells and modulates cell viability, dependent on cell source and presence of inflammatory mediators. Our finding represent a novel PIF-based mechanism in endometriosis that has potential for novel therapeutics.

Placental growth factor (PlGF) as an angiogenic/inflammatory switcher: lesson from early pregnancy losses

Placental growth factor (PlGF) is an angiogenic factor which belongs to vascular endothelial growth factor (VEGF) family. In addition to the angiogenic function of PlGF, in some conditions such as preeclampsia and early pregnancy losses, it can induce inflammatory reactions which could be accompanied with reduced angiogenesis. Hence, it is crucial to investigate inflammatory and angiogenic switching states and understand underlying mechanisms. PlGF is expressed in endometrium, placenta and trophoblast cells and is involved in maturation of uterine NK cells. Up-regulation of PlGF directs VEGF to VEGFR-2 and reinforces angiogenesis. However, when VEGF/VEGFR-2 signaling pathway is impaired, PlGF may shift to severe inflammation and cause tissue damages which could lead to early pregnancy losses. Downregulation of PlGF has also been reported in pregnancy complications. In this review, we discussed the role of PlGF in embryo implantation failure and early pregnancy loss and also possible mechanisms regarding the role of PlGF in angiogenic/inflammatory switching in early pregnancy losses. Furthermore, we summarized the effects of various compounds on PlGF expression and briefly talked about its therapeutic potential that may be an opportunity for prevention of pregnancy loss.

Follicular fluid PlGF/sFlt-1 ratio and soluble receptor for advanced glycation end-products correlate with ovarian sensitivity index in women undergoing A.R.T

PURPOSE

Considering potential roles of soluble receptor for advanced glycation end products (sRAGE) and placental growth factor (PlGF) in ovarian function and embryo implantation, in the present study we have evaluated the association of these factors and also PlGF/sFlt-1 ratio with the ovarian response and implantation rate by dividing patients according to the OSI.

METHODS

In a cross-sectional study, 90 infertile women who were undergoing ICSI cycle using long protocol were recruited. The patients were divided according to ovarian sensitivity index (OSI). ICSI cycle outcomes were evaluated for each patient and PlGF, sFlt-1 and sRAGE levels of follicular fluid were assayed using commercial ELISA kits.

RESULTS

Follicular fluid (FF) sRAGE levels and PlGF/sFlt-1 ratio were statistically greater in high-responder women than other responders (p < 0.05). Positive correlations were obtained between sRAGE level with the number of oocytes, follicles and OSI level. sRAGE levels with cutoff value of 4.83 (ng/ml) for evaluating the pregnancy outcome showed 81.8 % sensitivity and 60.7 % specificity. Furthermore, there were positive associations between PlGF/sFlt-1 ratio with the number of oocytes, embryos and OSI level.

CONCLUSION

In conclusion, the results of current study supported that good ovarian response is independent of pregnancy outcome. Our results showed that FF levels of sRAGE and PlGF/sFlt-1 ratio could be used as markers for determining the high-responder women. Also, FF sRAGE levels could be a good predictor for ART outcome.

Differential expression of vascular endothelial growth factor angiogenic factors in different endometrial compartments in women who have an elevated progesterone level before oocyte retrieval, during in vitro fertilization-embryo transfer treatment

OBJECTIVE

To investigate the relationship between endometrial expressions of angiogenic factors around the time of embryo implantation and P level before oocyte retrieval during IVF-ET treatment.

DESIGN

Retrospective study.

SETTING

University Assisted Reproductive Unit.

PATIENT(S)

Forty patients were recruited, 20 women with an elevated P level, and 20 women with a normal P level, into cancelled embryo transfer (ET) cycles.

INTERVENTION(S)

Endometrial biopsy samples were obtained from women who had an elevated or normal P level 7 days after human chorionic gonadotropin administration. The protein expression levels of VEGF-A, VEGF-C, and PLGF were examined using immunohistochemistry.

MAIN OUTCOME MEASURE(S)

A semiquantitative analysis was performed using histochemical-score analysis of staining intensity in the luminal epithelium, glandular epithelium, and stroma, separately.

RESULT(S)

Luminal epithelial expression of vascular endothelial growth factor (VEGF)-A, VEGF-C, and PLGF did not significantly differ in women with elevated or normal P levels before oocyte retrieval. Glandular epithelial expression of VEGF-A, VEGF-C, and PLGF was higher in women with elevated P levels, compared with those with normal P levels. A significantly higher stromal expression of VEGF-A and PLGF was found in women with elevated P levels.

CONCLUSION(S)

A high P level before oocyte retrieval was associated with expression of VEGF angiogenic factors in glandular epithelium and stromal compartment around the time of embryo implantation. Our findings suggest that the lower implantation rates observed in this group of women may relate to decreased endometrial receptivity arising from altered expression of angiogenic factors.

Molecular aspects of implantation failure

Despite expanding global experience with advanced reproductive technologies, the majority of IVF attempts do not result in a successful pregnancy, foremost as a result of implantation failure. The process of embryo implantation, a remarkably dynamic and precisely controlled molecular and cellular event, appears inefficient in humans and is poorly understood. However, insights gained from clinical implantation failure, early pregnancy loss, and emerging techologies that enable molecular interrogation of endometrial-embryo interactions are unravelling this major limiting step in human reproduction. We review current molecular concepts thought to underlie implantation failure, consider the contribution of embryonic and endometrial factors, and discuss the clinical value of putative markers of impaired endometrial receptivity. Finally we highlight the nature of the dialogue between the maternal endometrium and the implanting embryo and discuss the concept of natural embryo selection. This article is part of a Special Issue entitled: Molecular Genetics of Human Reproductive Failure.