Transcriptomic analysis of endometrial receptivity for a genomic diagnostics model of Chinese women

Meta-analysis of endometrial transcriptome data reveals novel molecular targets for recurrent implantation failure

PURPOSE

Gene expression analysis of the endometrium has been shown to be a useful approach for identifying the molecular signatures and pathways involved in recurrent implantation failure (RIF). Nevertheless, individual studies have limitations in terms of study design, methodology and analysis to detect minor changes in expression levels or identify novel gene signatures associated with RIF.

METHOD

To overcome this, we conducted an in silico meta-analysis of nine studies, the systematic collection and integration of gene expression data, utilizing rigorous selection criteria and statistical techniques to ensure the robustness of our findings.

RESULTS

Our meta-analysis successfully unveiled a meta-signature of 49 genes closely associated with RIF. Of these genes, 38 were upregulated and 11 downregulated in RIF patients' endometrium and believed to participate in key processes like cell differentiation, communication, and adhesion. GADD45A, IGF2, and LIF, known for their roles in implantation, were identified, along with lesser-studied genes like OPRK1, PSIP1, SMCHD1, and SOD2 related to female infertility. Many of these genes are involved in MAPK and PI3K-Akt pathways, indicating their role in inflammation. We also investigated to look for key miRNAs regulating these 49 dysregulated mRNAs as potential diagnostic biomarkers. Along with this, we went to associate protein-protein interactions of 49 genes, and we could recognize one cluster consisting of 11 genes (consisted of 22 nodes and 11 edges) with the highest score (p = 0.001). Finally, we validated some of the genes by qRT-PCR in our samples.

CONCLUSION

In summary, the meta-signature genes hold promise for improving RIF patient identification and facilitating the development of personalized treatment strategies, illuminating the multifaceted nature of this complex condition.

Endometrial transcriptome profiling of patients with recurrent implantation failure during hormone replacement therapy cycles

Background

The molecular mechanisms underlying window of implantation (WOI) displacement in patients with recurrent implantation failure (RIF) remain unclear. This study aims to explore the transcriptomic signatures of endometrium with normal and displaced WOIs and to identify the causes of endometrial receptivity (ER) abnormalities and WOI displacement in RIF patients.

Methods

In this study, 40 RIF patients were recruited and underwent personalized embryo transfer (pET) guided by the predicted results of endometrial receptivity diagnosis (ERD) model. Transcriptome analysis of endometrium from patients with clinical pregnancies after pET was performed to identify differentially expressed genes (DEGs) associated with WOI displacement. Gene expression data from HRT and natural cycle endometrium were compared to identify specific gene expression patterns of ER-related genes during WOI.

Results

The ERD results indicated that 67.5% of RIF patients (27/40) were non-receptive in the conventional WOI (P+5) of the HRT cycle. The clinical pregnancy rate in RIF patients improved to 65% (26/40) after ERD-guided pET, indicating the effectiveness of transcriptome-based WOI prediction. Among the 26 patients with clinical pregnancy, the gene expression profiles of P+5 endometrium from advanced (n=6), normal (n=10) and delayed (n=10) WOI groups were significantly different from each other. Furthermore, 10 DEGs identified among P+5 endometrium of 3 groups were involved in immunomodulation, transmembrane transport and tissue regeneration, which could accurately classify the endometrium with different WOIs. Additionally, a large number of ER-related genes showed significant correlation and similar gene expression patterns in P+3, P+5, and P+7 endometrium from HRT cycles and LH+5, LH+7, and LH+9 endometrium from natural cycles.

Conclusion

Our study shows that ER-related genes share similar gene expression patterns during WOI in both natural and HRT cycles, and their aberrant expression is associated with WOI displacements. The improvement of pregnancy outcomes in RIF patients by adjusting ET timing according to ERD results demonstrates the importance of transcriptome-based endometrial receptivity assessment and the clinical efficiency of ERD model.

Decreased CD56+CD16-CD94+uNK cells in the mid-luteal phase in women with recurrent implantation failure are associated with IL-15 deficiency

PROBLEM

Whether the abnormal development of uterine natural killer (uNK) cells contributes to women with recurrent implantation failure (RIF) remains unclear.

METHOD OF STUDY

We characterized the development of uNK cells and peripheral blood NK cells (pbNK) in the mid-luteal phase in women with RIF (n = 31) and controls (n = 14) by flow cytometry. Endometrial IL-15 mRNA expression was studied by quantitative reverse transcription-PCR. The GSE58144 dataset was used to validate the correlation results.

RESULTS

We found decreased proportions of stage 4 CD56+CD16-CD94+ uNK cells (median: 9.56% vs. 17.78%, P .014) and increased proportions of stage 6 CD56+CD16+CD57+ uNK cells (median: 1.54% vs. 0.74%, P = .020) in the mid-luteal endometrium of women with RIF compared to fertile women. We also found that there was no quantitative correlation between uNK cells and the corresponding pbNK cell subpopulations (P > .05). In addition, IL-15 mRNA levels in the mid-luteal endometrium were positively correlated with the proportion of CD56+ uNK cells (r = .392, P = .008), especially with stage 4 uNK cell populations (r = .408, P = .005).

CONCLUSIONS

We showed that the proportion of stage 4 uNK cells decreased in the RIF group compared to controls, and the decrease in stage 4 uNK cells correlated positively with low IL-15 mRNA expression. We suggest that the reduced stage 4 uNK cells in women with RIF are associated with IL-15 deficiency.

Endometrial Receptivity During the Preimplantation Period: A Narrative Review

Endometrial receptivity is a complex and critical process fundamental to achieving a successful pregnancy. While researchers have made significant strides in understanding the underlying mechanisms governing endometrial receptivity, effective diagnostic and therapeutic strategies remain scarce. This review article aims to elucidate the various factors that contribute to endometrial receptivity, including the hormonal regulation and molecular mechanisms that govern this process, as well as potential biomarkers for assessing endometrial receptivity. One of the major challenges in identifying reliable biomarkers for endometrial receptivity is the intricate nature of the process itself. Nonetheless, recent advances in transcriptomic and proteomic technologies have identified several candidate biomarkers that could potentially enhance our ability to predict endometrial receptivity. Furthermore, emerging technologies such as single-cell RNA sequencing and mass spectrometry-based proteomics hold great promise for providing novel insights into the molecular mechanisms underlying endometrial receptivity. Despite the lack of reliable biomarkers, various therapeutic strategies have been proposed to improve endometrial receptivity. One promising approach involves the transplantation of mesenchymal stem cells (MSCs), which have been shown to increase endometrial thickness and receptivity in both animal models and clinical trials. Growth factors, cytokines, and exosomes derived from MSCs and other cell types may also have therapeutic potential for addressing endometrial dysfunction.

The serum oestradiol/progesterone ratio on the day of OPU + 7, but not the day of OPU + 5, affects the rates of live birth in fresh blastocyst embryo transfer cycles

BACKGROUND

In an in vitro fertilization (IVF) cycle, the embryo ends its wandering time and begins the process of implantation into the uterine cavity on the seventh day after oocyte pick-up (OPU + 7), which is closer than OPU + 5 to the time of nidation. Therefore, measuring the oestradiol (E2)/progesterone (P) ratio on OPU + 7 may be helpful for predicting pregnancy outcomes.

METHODS

This is a retrospective cohort study of 2,257 women undergoing a follicular-phase depot gonadotropin-releasing hormone agonist (GnRH-a) protocol for in vitro fertilization /intracytoplasmic sperm injection (IVF/ICSI) treatment and fresh blastocyst embryo transfer cycles at a university-affiliated fertility center between January 2016 and April 2021. First, 2,257 women were split into two groups based on clinical pregnancy for analyzing the levels of E₂ and P and the E₂/P ratio on the day of OPU + 2, OPU + 5 and OPU + 7. And then 2,257 cycles were stratified into three groups based on E₂/P ratio tertiles on OPU + 7: the low group (1.3-15.7 pg/ng), middle group (15.7-28.8 pg/ng), and high group (28.8-487.2 pg/ng). The threshold effect of the E₂/P ratio on OPU + 7 on live birth was investigated using a two-piecewise linear regression model and a smoothing function curve.

RESULTS

The level of P in the clinical pregnancy group were lower than that in the nonclinical pregnancy group on both OPU + 2 and OPU + 7 (201.9 ± 71.6 ng/ml vs 213.1 ± 77.6 ng/ml, 89.5 ± 88.5 ng/ml vs 99.5 ± 94.9 ng/ml, P < 0.05). The E₂/P ratio in the clinical pregnancy group were higher than that in the nonclinical pregnancy group on both OPU + 2 and OPU + 7 (8.4 ± 6.5 pg/ng vs 8.0 ± 6.8 pg/ng, 32.3 ± 38.5 pg/ng vs 25.2 ± 31.0 pg/ng, P < 0.01). The E₂/P ratio on OPU + 7 was positively associated with positive hCG (adjusted OR = 1.01; 95% CI, 1.01-1.02; P < 0.0001), clinical pregnancy (adjusted OR = 1.01; 95% CI, 1.00-1.01; P = 0.0067) and live birth (adjusted OR = 1.01; 95% CI, 1.00-1.01; P < 0.001), and a nonlinear correlation was observed between the E₂/P ratio and LBR on OPU + 7.

CONCLUSIONS

A higher E₂/P ratio is associated with a higher LBR, but the E₂/P ratio should be maintained within a suitable range.

Serum LH Level on the Day of hCG Administration as a Predictor of the Reproductive Outcomes in Ovulation Induction Cycle Frozen-Thawed Embryo Transfer

Purpose: To evaluate the clinical utility of serum luteinizing hormone (LH) level in predicting frozen embryo transfer (FET) outcomes among the patients with an ovulation induction (OI) cycle. Methods: A total of 250 patients who underwent OI cycle frozen-thawed embryo transfer from January 2018 to June 2020 in Drum Tower Hospital affiliated with Nanjing University Medical School were retrospectively analyzed. The primary outcomes were clinical pregnancy rate and the live birth rate. Results: The results showed that a significant difference in Serum LH level on the day of human chorionic gonadotropin (hCG) administration was observed between the clinical pregnancy group and no clinical pregnancy group (p = 0.002), while there was no significant difference between the live birth group and no live birth group (p = 0.06). Multiple logistic regression analysis of factors related to clinical pregnancy showed serum LH level on the day of hCG administration was related to improved clinical pregnancy rate (OR was 1.02, 95% CI: 1.0-1.03, p = 0.02), while serum LH level had no significant effect on live birth rate. The ROC curves revealed the serum LH level was significantly correlated with clinical pregnancy rate and live birth rate; the cut-off point of serum LH level on the day of hCG administration was 8.46 miu/mL for clinical pregnancy rate (AUC 0.609, p = 0.003). Conclusion: In patients with OI FET, serum LH level on the day of hCG administration might be a biomarker for the prediction of clinical pregnancy. The prediction that patients who underwent OI cycle frozen-thawed embryo transfer with serum LH levels below 8.46 mIU /mL might be pregnant appeared to be meaningful.

The clinical efficiency of transcriptome-based endometrial receptivity assessment (Tb-ERA) in Chinese patients with recurrent implantation failure (RIF): A study protocol for a prospective randomized controlled trial

Background

Today, approximately 10% of participants in assisted reproductive technology (ART) are defined as having recurrent implantation failure (RIF). Recent studies show that endometrial receptivity array can improve pregnancy and implantation rates by nearly 20% in women with RIF. However, these studies are limited, with little published data in the Chinese population. Recently, we have established a transcriptome-based endometrial receptivity assessment (Tb-ERA) method of predicting the endometrial window of implantation (WOI) using transcriptome-profiling data of different phases of the menstrual cycle from healthy fertile Chinese women by RNA-Seq. It is meaningful to conduct a randomized controlled trial (RCT) to assess the clinical efficiency of Tb-ERA in Chinese patients with RIF.

Methods

In this RCT, a total of 200 RIF patients will be recruited and randomized into 2 groups. Patients in the Tb-ERA group will undergo a Tb-ERA test, after which embryo transfer time will be adjusted according to Tb-ERA results and embryo transfer will be performed again in the next cycle. Patients in the control group will not receive any interventions until the next transfer cycle. We will perform statistical analysis on both groups at the primary endpoint (clinical-pregnancy rate) and at secondary endpoints (rate of WOI displacement, embryo implantation, biochemical pregnancy, early abortion, and ectopic pregnancy). Implications: This study aims to evaluate the effectiveness of our Tb-ERA test in Chinese RIF patients and to determine that whether Tb-ERA could improve the clinical-pregnancy rate in these RIF patients.

Trial registration

NCT04497558, registered August 4, 2020.