Integrative Analyses of Uterine Transcriptome and MicroRNAome Reveal Compromised LIF-STAT3 Signaling and Progesterone Response in the Endometrium of Patients with Recurrent/Repeated Implantation Failure (RIF)

Effect of mifepristone on the transcriptomic signature of endometrial receptivity

STUDY QUESTION

How does a single dose of mifepristone on Day 2 after the LH peak (LH + 2) affect the endometrial receptivity transcriptome as assessed by the receptive signature established by the endometrial receptivity analysis (ERA)?

SUMMARY ANSWER

A single dose of mifepristone on day LH + 2 renders the endometrium non-receptive by altering the transcriptome associated with endometrial receptivity.

WHAT IS KNOWN ALREADY

Mifepristone is a progesterone receptor modulator that has been shown to alter endometrial receptivity. The ERA is a computational predictor that utilizes gene expression data of 248 genes from next generation sequencing to identify endometrial receptivity status.

STUDY DESIGN, SIZE, DURATION

Endometrial biopsies were collected on day LH + 7 from controls (n = 11) and from women treated with mifepristone (n = 7). For further comparative analysis, samples were also obtained from women in the proliferative phase (n = 7).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Mifepristone treatment consisted of 200 mg administered on day LH + 2. Endometrial biopsies were treated for RNA isolation and cDNA conversion and sequencing. Endometrial receptivity status was assessed by the ERA computational predictor. Differential gene expression between groups was also assessed. Ingenuity Pathway Analysis was used for network analysis. Validation of gene expression results was done by qPCR.

MAIN RESULTS AND THE ROLE OF CHANCE

Control samples were all staged around 'receptive' as would be clinically expected for LH + 7. Treatment samples were all staged as non-receptive (all but one was classified as 'proliferative' and the last as 'pre-receptive'). Differential gene expression analysis yielded 60 differentially expressed genes between the control and treatment groups. Bioinformatic pathway analysis for differential expression showed inactivation of the progesterone and glucocorticoid receptors, consistent with mifepristone action.

LIMITATIONS, REASONS FOR CAUTION

The primary limitations are the relative small number of subjects and the use of a limited gene panel.

WIDER IMPLICATIONS OF THE FINDINGS

This study sheds further light on the endometrial receptivity altering effects of mifepristone and on progesterone action. It further shows the capacity of the ERA to identify pharmacologically induced non-receptive endometrium, which expands its possible use clinically and in research.

STUDY FUNDING/COMPETING INTEREST(S)

C.v.G. and N.R.B. have no conflicts of interest. P.G.L. reports honorarium from University of HK/Shenzhen, other from NIF, India, outside the submitted work. K.G.D. reports consultancy for Bayer AG, Exelgyn, HRA-Pharma, Gedeon Richter, MSD, Mithra, Exeltis and Natural cycles, payment for lectures from Bayer AG, NSD, Ferring, HRA-Pharma, Exelgyn and Exeltis and clinical trials for Bayer AG, MSD, Exeltis, Mithra, HRA-Pharma and Sun Pharma. C.S. has a patent gene expression profile (ERA) issued to Igenomix and is scientific director of Igenomix S.L. M.R., R.N. and J.M.V. are employees of Igenomix S.L.

TRIAL REGISTRATION NUMBER

N/A.

mRNA/lncRNA expression patterns and the function of fibrinogen-like protein 2 in Meishan pig endometrium during the preimplantation phases

Embryonic implantation involves a complex and well-coordinated interaction between the developing conceptus and maternal uterus, and the preimplantation period has a major impact on litter size in pigs. The present study aimed to investigate the vital messenger RNAs (mRNAs) and long noncoding RNAs (lncRNAs) that regulate preimplantation in Meishan pigs. The enriched Gene Ontology terms were all related to "binding." Furthermore, "ECM-receptor interaction" was predicted as an important pathway that regulated the success of implantation. We speculated that the differentially expressed mRNAs S100A9, ANXA8, MUC16, and FGL2 and the differentially expressed lncRNAs TCONS_11206566, TCONS_09904861, and TCONS_1252933 may play vital roles in the process of implantation. Furthermore, this study verified that FGL2 was highly expressed on Day 12 of pregnancy, and we also investigated the function of FGL2 during preimplantation in vivo. In conclusion, this study provides useful information for further analyses of the molecular mechanisms of implantation in Chinese domestic pigs.

Decreased PECAM1-mediated TGF-β1 expression in the mid-secretory endometrium in women with recurrent implantation failure

STUDY QUESTION

Is recurrent implantation failure (RIF) associated with decreased expression of platelet and endothelial cell adhesion molecule 1 (PECAM1) and transforming growth factor β1 (TGF-β1) in the endometrium during the implantation window?

SUMMARY ANSWER

The present study demonstrates that the expression of PECAM1 and TGF-β1 is significantly decreased in the mid-secretory endometrium in women with RIF, which may account for embryo implantation failure.

WHAT IS KNOWN ALREADY

RIF has become a bottleneck issue that hampers the improvement of pregnancy rates in IVF-embryo transfer (IVF-ET). The causes of RIF are complex and may involve the dysregulation of various growth factors, metabolites, and inflammatory cytokines. At present, the precise pathogenesis of RIF has not been elucidated.

STUDY DESIGN, SIZE, DURATION

This was a prospective case-control study. Endometrial tissue samples were obtained from January 2014 to December 2016 from two groups of women who had undergone IVF (RIF group, 22 women who underwent ≥3 ETs including a total of ≥4 good-quality embryos without pregnancy, control group, 18 women who conceived in their first treatment cycle). At the same time, samples were obtained from 18 women with infertility secondary to tubal factor in the early proliferative, late proliferative and mid-secretory phases of the menstrual cycle (n = 6 per group). Samples used for isolation of primary human endometrial epithelial cells and stromal cells (HEECs and HESCs) were collected in December 2017 from six women with infertility secondary to tubal factor.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We investigated gene expression using integrative whole genome expression microarray analysis, including differentially expressed gene screening, principal component analysis, and functional enrichment analysis. RT-qPCR, western blotting, immunohistochemistry, immunofluorescence co-localization analysis and short hairpin RNA (shRNA) plasmid transfection in Ishikawa cell line, HEECs and HESCs were used to investigate the expression of PECAM1 and TGF-β1.

MAIN RESULTS AND THE ROLE OF CHANCE

Integrative data mining of whole-genome expression profiles identified cell adhesion as a key regulator in RIF. Database retrieval and literature review screened several novel cell adhesion-related genes that might participate in embryo implantation, which include PECAM1, intercellular adhesion molecule 2 (ICAM2), integrin subunit β2 (ITGB2), selectin P (SELP) and TEK receptor tyrosine kinase (TEK). Among these targets, the mRNA and protein levels of PECAM1 were significantly lower in the RIF group than those in the control group. During the menstrual cycles of women with secondary infertility, the protein expression level of PECAM1 was the lowest in early proliferative phase, slightly increased in late proliferative phase and was the highest in mid-secretory phase. While the expression level of HOXA10, an endometrial receptivity marker, kept at a low level in early proliferative phase and increased in late proliferative phase, then maintained at a high level in the mid-secretory phase. Furthermore, TGF-β1, mediated by PECAM1, was also decreased significantly in the RIF group. Using shRNA-based approach, we demonstrated that the depletion of PECAM1 significantly decreased the expression of TGF-β1 in Ishikawa cells, as well as in primary HEECs and HESCs. These results indicated that PECAM1 and TGF-β1 might play a pivotal role in modulating endometrial receptivity.

LIMITATIONS REASONS FOR CAUTION

Although we have shown that PECAM1 and TGF-β1 were down-regulated in the women with RIF, the molecular mechanism of the effect of the factors on the endometrial receptivity remain unclear.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings provide insight into the contribution of PECAM1 and TGF-β1 in regulating implantation, which could be used to develop potential therapeutic methods for RIF.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by grants from the National Natural Science Foundation of China (Nos. 81771656 and 81370763), Special fund for clinical research of the Chinese Medical Association (No. 16020480664), and the Merck Serono China Research Fund for Fertility Agreement. The authors have no competing interests.

A Two-Cohort RNA-seq Study Reveals Changes in Endometrial and Blood miRNome in Fertile and Infertile Women

The endometrium undergoes extensive changes to prepare for embryo implantation and microRNAs (miRNAs) have been described as playing a significant role in the regulation of endometrial receptivity. However, there is no consensus about the miRNAs involved in mid-secretory endometrial functions. We analysed the complete endometrial miRNome from early secretory (pre-receptive) and mid-secretory (receptive) phases from fertile women and from patients with recurrent implantation failure (RIF) to reveal differentially expressed (DE) miRNAs in the mid-secretory endometrium. Furthermore, we investigated whether the overall changes during early to mid-secretory phase transition and with RIF condition could be reflected in blood miRNA profiles. In total, 116 endometrial and 114 matched blood samples collected from two different population cohorts were subjected to small RNA sequencing. Among fertile women, 91 DE miRNAs were identified in the mid-secretory vs. early secretory endometrium, while no differences were found in the corresponding blood samples. The comparison of mid-secretory phase samples between fertile and infertile women revealed 21 DE miRNAs from the endometrium and one from blood samples. Among discovered novel miRNAs, chr2_4401 was validated and showed up-regulation in the mid-secretory endometrium. Besides novel findings, we confirmed the involvement of miR-30 and miR-200 family members in mid-secretory endometrial functions.

Role of estrogen and RAS signaling in repeated implantation failure

In humans, hormonal regulation is crucial for the preparation of uterine environment leading to either successful implantation or menstrual cycle. Estrogen is a pivotal female steroid hormone that regulates the uterine dynamics along with progesterone in the estrous and menstrual cycles in humans. Estrogen signals act via nuclear estrogen receptor or membrane-bound receptor. The membrane-bound estrogen receptor plays a crucial role in the rapid response of estrogen in the uterine epithelium. Recently, RASD1 has received attention as a novel signal transducer of estrogen in various systems including female reproductive organs. In this review, we discuss the regulation of estrogen and RASD1 signaling in the uterus and also provide insights into RAS as a novel signaling molecule in repeated implantation failure.

Increased Krüppel-like factor 12 impairs embryo attachment via downregulation of leukemia inhibitory factor in women with recurrent implantation failure

Recurrent implantation failure (RIF) caused by various etiological factors remains a challenge for fertility clinicians using assisted reproductive technology (ART) worldwide. Dysregulation of leukemia inhibitory factor (LIF) in the endometria of women with RIF is involved in impaired endometrial receptivity and embryo adhesion. However, the mechanism through which LIF expression is regulated in women with RIF is still poorly understood. Our previous study noted that the abnormally increased endometrial Krüppel-like factor 12 (KLF12) in RIF women led to impaired decidualization and embryo implantation. Here, we further found that KLF12 inhibited embryo adhesion in vivo and in vitro by repressing LIF expression. Mechanistically, KLF12 bound to conserved sites (CAGTGGG, −6771 to −6765 and −7115 to −7109) within the LIF promoter region and repressed LIF transcription directly. Exogenous LIF significantly reversed the KLF12-mediated repression of BeWo spheroid adhesion. KLF12 expression was reduced significantly in Ishikawa cells treated with progestogen, which was due to the activation of Akt signaling. These findings may provide novel potential therapeutic regimens for patients with RIF and disrupted endometrial receptivity.

Regulation of Cyclic AMP-Response Element Binding Protein Zhangfei (CREBZF) Expression by Estrogen in Mouse Uterus

CREBZF (cAMP-response element binding protein zhangfei) is a member of ATF/CREB family, and which regulates various cellular functions by suppressing major factors with direct interaction. In this study, we have examined the expression of CREBZF on mouse endometrium during uterus estrous cycles and estrogen (E2) treatment. In uterus, CREBZF mRNA expression was higher than other organs and mRNA and protein of CREBZF was increased in proestrus phase and decreased in estrus phase. The expression of CREBZF in 3-weeks old mouse uterus was reduced by E2 injection in endometrium. In addition, the expression of progesterone receptor, a marker of E2 in ovariectomized mice was found to be strongly expressed in stroma, while CREBZF was only expressed in epithelium. Also, we conformed that E2-suppressed CREBZF was restored by co-injection of ICI 182,780, an estrogen receptor antagonist. Overall, these results suggest that CREBZF is regulated by estrogen and involved in ER signaling pathway in mouse uterus.

DNA methylation changes in endometrium and correlation with gene expression during the transition from pre-receptive to receptive phase

The inner uterine lining (endometrium) is a unique tissue going through remarkable changes each menstrual cycle. Endometrium has its characteristic DNA methylation profile, although not much is known about the endometrial methylome changes throughout the menstrual cycle. The impact of methylome changes on gene expression and thereby on the function of the tissue, including establishing receptivity to implanting embryo, is also unclear. Therefore, this study used genome-wide technologies to characterize the methylome and the correlation between DNA methylation and gene expression in endometrial biopsies collected from 17 healthy fertile-aged women from pre-receptive and receptive phase within one menstrual cycle. Our study showed that the overall methylome remains relatively stable during this stage of the menstrual cycle, with small-scale changes affecting 5% of the studied CpG sites (22,272 out of studied 437,022 CpGs, FDR < 0.05). Of differentially methylated CpG sites with the largest absolute changes in methylation level, approximately 30% correlated with gene expression measured by RNA sequencing, with negative correlations being more common in 5' UTR and positive correlations in the gene 'Body' region. According to our results, extracellular matrix organization and immune response are the pathways most affected by methylation changes during the transition from pre-receptive to receptive phase.

Ulipristal acetate administration at mid-cycle changes gene expression profiling of endometrial biopsies taken during the receptive period of the human menstrual cycle

The aim of this study was to analyze the effects of mid-cycle administration of Ulipristal acetate (UPA) on gene expression in endometrial biopsies taken during the receptive phase of the cycle. Fourteen healthy menstruating women were studied during 14 control non-treated and 12 treated cycles with a single dose of 30 mg UPA when follicle diameter reached 20 mm. Ovulation in both treated and control cycles was confirmed by serial determinations of serum LH, progesterone and vaginal ultrasound. An endometrial biopsy at day LH+7, in each cycle, was taken for RNA microarray and qPCR analysis or prepared for histological and immunohistochemistry studies. Functional analysis of differentially expressed genes showed the presence of changes compatible with a non-receptive endometrial phenotype, further confirmed by qPCR and immunohistochemistry. This study suggests the effects of UPA on endometrial receptivity, offering a plausible explanation for the higher contraceptive efficacy of this method compared to that of levonorgestrel.

Rapid expression of RASD1 is regulated by estrogen receptor-dependent intracellular signaling pathway in the mouse uterus

Dexamethasone-induced RAS-related protein 1 (RASD1) is a signaling protein that is involved in various cellular processes. In a previous study, we found that RASD1 expression was down-regulated in the uterine endometrium of repeated implantation failure patients. The study aim was to determine whether RASD1 is expressed in the endometrium of mouse uterus and how it is regulated by steroid hormones during the estrous cycle. In this study, we investigated RASD1 expression and regulation in an ovariectomized female mouse model. Rasd1 mRNA was highly expressed in mouse reproductive tissues, including the uterus. Rasd1 expression was detected exclusively in the endometrial epithelium at the proestrus stage of the estrous cycle. Rasd1 expression in uteri increased with administration of estradiol, but not progesterone. Its expression was rapidly induced within 2 h after E₂ treatment. Pretreatment with ICI 182,780, an estrogen receptor antagonist, reduced RASD1 protein expression. In addition, we identified that rapid expression of Rasd1 was mediated by the estrogen intracellular signaling including both p38-mitogen-activated protein kinase and the extracellular signal-regulated kinase. These findings suggest that RASD1 acts as a novel signaling molecule and plays an important role in regulating dynamic uterine remodeling during the estrous cycle in the uterus.

Effects of autologous platelet-rich plasma on implantation and pregnancy in repeated implantation failure: A pilot study

BACKGROUND

Repeated implantation failure (RIF) is a major challenge in reproductive medicine and despite several methods that have been described for management, there is little consensus on the most effective one.

OBJECTIVE

This study was conducted to evaluate the effectiveness of platelet-rich plasma in improvement of pregnancy rate in RIF patients.

MATERIALS AND METHODS

Twenty women with a history of RIF who were candidates for frozen-thawed embryo transfer were recruited in this study. Intrauterine infusion of 0.5 ml of platelet-rich plasma that contained platelet 4-5 times more than peripheral blood sample was performed 48 hrs before blastocyst transfer.

RESULTS

Eighteen participants were pregnant with one early miscarriage and one molar pregnancy. Sixteen clinical pregnancies were recorded and their pregnancies are ongoing.

CONCLUSION

According to this study, it seems that platelet-rich plasma is effective in improvement of pregnancy outcome in RIF patients.