Chronic endometritis modifies decidualization in human endometrial stromal cells

Correlation between hysteroscopic features and specific microbial species in women with chronic endometritis

Objective and rationale

Chronic endometritis (CE) has recently been associated with unexplained infertility and recurrent miscarriages. The current gold standard for CE detection is histopathological examination. However, office hysteroscopy and endometrial cultures are also significant, due to the possible link between CE and various microorganisms. Bacterial colonization of the endometrium has been associated with reduced success rates of in vitro fertilisation embryo transfer. Few studies have tried to correlate CE hysteroscopy findings with pathogenic microorganisms. This prospective cohort study sought to establish whether hysteroscopic diagnostic lesions correlate with specific microbial species.

Methods

The study encompassed women undergoing diagnostic tests for a range of subfertility health issues. 189 women completed the standard office diagnostic hysteroscopy (DH). 181 had also endometrial samples taken for microbial culture investigation. Correlation analysis (χ2 and Fisher's exact test) between hysteroscopic findings suggestive of CE and endometrial cultures was carried out. Logistic regression models were also fitted to measure whether a positive endometrial culture could affect CE conditions.

Results

A significant association of E. coli was observed between the hysteroscopically characterized CE + group with focal hyperplasia, when compared to the non-CE group. Logistic regression analysis revealed that women positive for E. coli were 4.423 times more likely to have focal endometrial hyperplasia. No other significant correlations were identified between DH and positive endometrial cultures.

Conclusions

The presence of E. coli in the endometrium was significantly correlated with focal hyperplasia findings from hysteroscopy, emphasizing the importance of microbial cultures in the diagnosis and targeted treatment of CE in women with subfertility.

The timing for embryo transfer after antibiotic therapy for chronic endometritis

OBJECTIVE

To explore the optimal timing of embryo transfer after the first round treatment of chronic endometritis (CE) in vitro.

MATERIALS AND METHODS

A total of 184 patients were recruited from a retrospective analysis of a large university-affiliated reproduction center in 2021. Some people chose to undergo embryo transfer in the same menstrual cycle with the first round of antibiotic treatment (Group 1, n = 29). Others received embryo transfer in the next cycle after the first round of treatment (Group 2, n = 69) or even one cycle later (Group 3，n = 96).

RESULTS

Patients in Group 1 got significantly lower biochemical pregnancy rate and clinical pregnancy rate and live birth rate than Group 2 (p < 0.05) and also Group 3 (p < 0.05). Then after comparing the influence factors, we found embryo transfer in the next cycle after antibiotic treatment had a higher clinical pregnancy rate than group 1 (OR = 3.2 p < 0.05) and group 3(OR = 2.5, p < 0.05). The live birth rate in group 2 was higher than group 1(OR = 3.5, p < 0.05).

CONCLUSION

These findings illustrate that embryo transfer in the next menstrual cycle is the optimal time. Embryo transfer in the same menstrual cycle with the first round of treatment reduces the pregnancy rate.

Antibiotic cured chronic endometritis remains a risk factor for early pregnancy loss in the subsequent frozen euploid embryo transfer

RESEARCH QUESTION

Do patients with antibiotic-cured chronic endometritis (CCE) have a comparable pregnancy outcome to those with non-chronic endometritis (NCE) in the subsequent frozen embryo transfer (FET) cycle?

DESIGN

A retrospective cohort analysis included 833 patients in their first FET cycles with single euploid embryo transfer. Chronic endometritis (≥5 CD138+ plasma cells per high-power field [CD138+/HPF]) was treated with standard antibiotic therapy. Patients were classified into two groups: the NCE group (n = 611, <5 CD138+/HPF) and the CCE group (n = 222, ≥5 CD138+/HPF and cured after antibiotic treatment). Pregnancy outcomes were compared. NCE group was divided into subgroup 1 (CD138+/HPF = 0) and subgroup 2 (CD138+/HPF = 1-4) for further analysis.

RESULTS

The rate of early pregnancy loss (EPL), incorporating all losses before 10 weeks' gestation, was significantly higher in the CCE group than the NCE group (21.2% versus 14.2%, P = 0.016), and the difference was statistically significant (adjusted odds ratio [AOR] 1.68, 95% confidence interval [CI] 1.11-2.55). No significant differences were observed between the two groups with regard to other pregnancy outcomes. In the subgroup analysis, the EPL rate and biochemical pregnancy rate were significantly higher in subgroup 2 than subgroup 1 (17.2% versus 9.4%, AOR 2.21, 95% CI 1.30-3.74; 12.2% versus 6.9%, AOR 2.01, 95% CI 1.09-3.68).

CONCLUSIONS

Chronic endometritis cured by standard antibiotic therapy remains a risk factor for EPL in FET cycles, although no differences were found in live birth rates between patients with CCE or with NCE.

Management strategies following implantation failure of euploid embryos

Background

Euploid blastocyst implantation failure may result from embryonic factors undetectable by preimplantation genetic testing for aneuploidy (PGT-A); however, various nonembryonic factors can also intricately interfere with implantation. This review seeks to clarify evidence-based testing and treatments for implantation failure after euploid embryo transfer.

Methods

We conducted a review of the literature on implantation failure after euploid embryo transfer or multiple embryo transfer cycles, which mainly included systematic reviews and meta-analyses.

Results

The recommended tests for implantation failure include (1) hysteroscopy, (2) endometrial CD138 immunohistochemistry and bacterial culture, (3) serum 25-hydroxyvitamin D3, and (4) thrombophilia screening. Based on diagnostic findings, the following treatments have been recommended: (1) antibiotics for chronic endometritis, (2) vitamin D replacement, (3) lifestyle modification, and (4) low-dose aspirin starting from the postimplantation period for thrombophilia. Moreover, frozen-thawed single euploid blastocyst transfer using assisted hatching and hyaluronan-enriched transfer medium may support embryo implantation.

Conclusion

To ensure a successful pregnancy in subsequent embryo transfers, simple, inexpensive, and evidence-based tests and treatments should be selected.

Association Between Endometritis and Endometrial Polyp: A Mendelian Randomization Study

Background

Endometrial polyps (EPs) are one of the most common intrauterine benign tumors, and are an important cause of uterine bleeding and female infertility. Previous studies have suggested that endometritis may contribute to the onset of EPs. This study aims to reveal the causal effect of endometritis on EPs by a two-sample Mendelian randomization (MR) study.

Methods

Utilizing summarized statistics from genome-wide association studies (GWAS) in the European population, we conducted a Mendelian randomization study. In order to select suitable instrumental variables (IVs) that were significantly related to the exposures, a number of quality control approaches were used. For endometritis, 2144 cases and 111,858 controls were included, while for EPs, 2252 cases and 460,758 controls. Utilizing the inverse variance weighted (IVW) as the primary analysis, the data were subjected to a two-sample MR analysis, and the weighted median (WM) technique and MR-Egger regression were carried out additionally. The sensitivity analysis revealed neither heterogeneity nor horizontal pleiotropy.

Results

Four independent single nucleotide polymorphisms (SNPs) from endometritis GWAS as IVs were selected. The IVW data did not agree to a causal association between endometritis and EPs (β=1.11e-04, standard error [SE] =4.88e-04, P = 0.82). Directional pleiotropy did not affect the outcome, according to the MR-Egger regression (intercept = 0.09, P = 0.10); Additionally, it showed no causation association between endometritis and EPs (β= -3.28e-03, SE = 3.54e-03, P = 0.45). Similar results were obtained using the weighted-median method (β=8.56e-05, SE=5.97e-04, P = 0.89). No proof of heterogeneity and horizontal pleiotropy between IV estimates was discovered.

Conclusion

In conclusion, by large scale genetic data, the results of this MR analysis provided suggestive evidence that the presence of endometritis is not associated with higher EPs risk.

Increasing expression of STING by ERα antagonizes LCN2 downregulation during chronic endometritis

Chronic endometritis has a high incidence in infertile women, which is caused by endometrial microbiome infection. In response to microbial infection, the role of defensins during chronic endometritis need explored. Besides, the expression of estrogen and its receptors vary in different menstrual cycles, but their roles in chronic endometritis are still unclear. In this study, we used the human endometrial tissues to examine the expression of antimicrobial peptides (AMPs) α-defensin hNP-1 and β-defensins hBD-1, hBD-2, hBD-3, hBD-4 and LCN2. We found the expression of hBD-1 and LCN2 were downregulated in endometritis tissues, while the expressions of hBD-2, hBD-3, hBD-4, hNP-1, and estrogen and ERα were upregulated in chronic endometritis tissues compared to normal tissues. The expression and phosphorylation of STING, which is a crucial mediator of mammalian innate immunity in response to pathogens, was regulated with the treatment of ERα inhibitor raloxifene (Rx). Furthermore, using with the estrogen receptor inhibitor Rx and STING inhibitor H-151 significantly decreases the LCN2 expression. Taken together, these results suggested ERα was upregulated to modulate STING expression inducing LCN2 antimicrobial peptide expression to modulate the mucosal immunity during chronic endometritis.

Benefits of antibiotics and the optimal time interval between biopsy and the next embryo transfer in patients with chronic endometritis

This study evaluated the effects of antibiotics on the implantation rate (IR) as well as the optimal time interval from endometrial biopsy to subsequent embryo transfer (ET) to explore proper chronic endometritis (CE) management. We retrospectively analyzed the clinical data of patients who had failed 1 or 2 ET cycles and underwent hysteroscopy. CE was diagnosed when 3 or more cluster of differentiation138 - positive plasma cells were found per high-power field. We divided the patients into 3 groups: those with CE who received antibiotics (group 1), those with CE who did not receive antibiotics (group 2), and those without CE (group 3). We found that IR was significantly higher in Group 1 than in Group 2. Furthermore, while the IR in Groups 1 and 3 was significantly higher when the time interval was < 6 months than when the time interval was > 6 months, there were no significant differences in the IR when the time interval was < 2 months or ≥ 2 months but < 6 months. Postbiopsy oral antibiotic therapy significantly improved IR in patients with CE, whereas increasing the time interval from biopsy to ET reduced IR. This study may help to find a higher potential for success in the medical management of patients with CE.

Chronic endometritis diagnosed using a cut-off of ≥5 CD138 plasma cells significantly affects the reproductive outcomes of frozen embryo transfer: a case-control study

Objective

To investigate the clinical significance of a diagnosis of chronic endometritis (CE) made using a diagnostic cut-off of ≥1 or ≥5 CD138 plasma cells per high power field (HPF) in asymptomatic patients undergoing in vitro fertilization (IVF) with frozen embryo transfer (FET).

Material and Methods

In this retrospective case-control study, 1,865 patients underwent freeze-all-IVF treatment between January and December 2019, with 419 undergoing endometrial biopsies at oocyte retrieval. Of the 419 biopsy-patients, 301 have since undergone first FET. The processed endometrial biopsies of the 301 patients underwent immunohistochemical (IHC) examination with anti-CD138 to count CD138+ plasma cells per HPF. CE diagnosis was defined as 0 CD138 plasma cells (control-group), ≥1 CD138 plasma cells (CEcontrol-group) or ≥5 CD138 plasma cells (CEdisease-group) per HPF.

Results

Twenty-six (8.6%) patients were retrospectively diagnosed having ≥1 CD138 plasma cells, and five patients (1.7%) having ≥5 CD138 plasma cells (CEdisease-group) per HPF. The live birth and pregnancy loss rates of the three groups were 52.7% and 27.9%, 53.8% and 26.3% and 20.0% and 66.7%, respectively. The antral follicle count (AFC) of the three groups were 15.0 (9.0-22.0), 10.5 (7.75-15.25), and 6.0 (5.0-14.0), respectively.

Conclusion

Asymptomatic patients diagnosed with CE with ≥5 CD138 plasma cells per HPF, had the lowest live birth and highest pregnancy loss rates, with these patients also having significantly reduced AFC.

Immune Checkpoints in Recurrent Pregnancy Loss: New Insights into a Detrimental and Elusive Disorder

Recurrent pregnancy loss (RPL) refers to two or more miscarriages before 20 weeks gestation. Its prevalence is 1-2%; its pathogenesis remains unexplained in more than 50% of cases, in which the cause is thought to be abnormal immune activity during placentation leading to a lack of pregnancy-induced immune tolerance. It is unknown whether immune activity is deranged in the endometrium of women with RPL. We studied the gene expression and the quantitative tissue protein levels of three immune checkpoints (CD276, which enhances cytotoxic T-cell activity, cytotoxic T-lymphocyte-associated antigen-4 [CTL-4], which reduces Th1 cytokine production, and lymphocyte activation gene-3 [LAG-3], which shows suppressive activity on Tregs and CD4+ T-cells) in endometrial samples from 27 women with unexplained RPL and in 29 women with dysfunctional uterine bleeding and previous uneventful pregnancies as controls. RNA isolation, real-time PCR, protein isolation, and ELISA were performed. CD276 gene expression and protein tissue levels were significantly lower in the endometrium of the RPL group than in the controls, whereas both CTL-4 and LAG-3 were significantly higher. This difference suggests defective endometrial immune regulation and overactivation of immune response in women with a history of RPL, at least in relation to controls with dysfunctional uterine bleeding and previous normal reproductive history.

Impact of antibiotic cured chronic endometritis on perinatal outcomes: Re-evaluation of a cohort study with a detailed follow-up

PROBLEM

The impact of antibiotic-cured chronic endometritis (CE) on perinatal outcomes of patients conceived with frozen embryo transfer (FET) was unclear.

METHOD

This study was to re-evaluate the perinatal outcomes of a cohort of infertile patients who had undergone endometrial biopsy for CE detection from February 2018 to December 2019 and successfully delivered babies after FET. The study population was divided into two groups: the non-CE (NCE) group (0-4/HPF CD138) and the cured-CE (CCE) group (CD138+/HPF≥5 and has been cured after one or two rounds of antibiotic treatment). For subgroup analysis, the NCE group was further divided into subgroup 1 (CD138+/HPF = 0), subgroup 2 (CD138+/HPF = 1-4 with antibiotic treatment), and subgroup 3 (CD138+/HPF = 1-4 without antibiotic treatment) RESULTS: A total of 321 live births, including 210 in the NCE group and 111 in the CCE group were analyzed. The prevalence rates of premature rupture of the membrane and preterm birth were comparable between NCE and CCE (6.2% vs. 7.1% and 10.8% vs. 10.1%, respectively) groups. In addition, no differences were detected in the rates of placenta-mediated complications, such as preeclampsia, placenta abruption, or low birthweight. Multiple logistic analyses confirmed that CCE was not associated with an increased risk of any adverse perinatal outcomes. Subgroup analysis in NCE failed to find any significant differences in the incidences of obstetrical and neonatal complications.

CONCLUSIONS

CCE might not increase the risks of adverse perinatal outcomes after antibiotic treatment.

Histone H4 hyperacetylation but not DNA methylation regulates the expression of decidualization-associated genes during induced human endometrial stromal cells decidualization

The efficiency of endometrial stromal cells (ESC) decidualization is a critical player in successful embryo implantation and further pregnancy development. Epigenetic mechanisms strictly regulate massive changes that affect endometrium in each cycle, so investigating epigenetic patterns could help identify endometrial targets for infertility treatment solutions. The aim of our study was to analyze the changes in epigenetic modulators, histone modifications, and DNA methylation during induced human ESC in vitro decidualization. Decidualization markers and epigenetic factors' gene and protein expression levels were assessed during ESC cells in vitro decidualization, performing RT-qPCR and immunoblot tests. Furthermore, chromatin immunoprecipitation (ChIP) and methylated DNA immunoprecipitation (MeDIP) analysis by the following qPCR were conducted to evaluate the level of H4hyperAc and 5-methylcytosine in the decidualization-associated gene promoter and exon regions accordingly. Our results revealed that ESC decidualization caused the down-regulation of HDAC2 and subunits of PRC2. We observed the increased global level of H4hyperAc and H3K27me3. We also demonstrated that H4hyperAc was specifically enriched in the decidualization-associated genes (WNT4, HAND2, STAT5A) promoter regions during ESC decidualization. In contrast, the DNA methylation level in these promoter regions was relatively low before ESC induction and did not vary through ESC decidualization. Our findings demonstrate that specific gene promoters' histone acetylation increases during the induced ESC decidualization, which indicates the importance of epigenetic regulation in endometrial decidualization.

The association between chronic deciduitis and recurrent pregnancy loss

Chronic deciduitis (CD) is defined as the presence of lymphocytes or plasma cells in decidual tissue. CD suggests the presence of chronic endometritis (CE) which is associated with recurrent pregnancy loss (RPL). In this study, we examined the role CD plays in RPL patients with aneuploid and euploid miscarriage. The frequency of CD in 49 RPL patients (22 euploid and 27 aneuploid miscarriages) and 17 control women was assessed and the subsequent live birth rate (LBR) in the presence and absence of CD were compared. When only one CD138-positive endometrial stromal plasma cell (ESPC) was found per high-power field (HPF), we diagnosed small-positive CD (Grade 1). When a cluster of two or more CD138-positive ESPCs was found per HPF, we diagnosed it as CD Grade 2. The prevalence of Grade 1 was 18.2% (4/22) in patients with euploid miscarriage, 37.0% (10/27) in patients with aneuploid miscarriage and 23.5% (4/17) in control women. The prevalence of Grade 2 was 45.5% (10/22) in patients with euploid miscarriage, 55.6% (15/27) in patients with aneuploid miscarriage and 23.5% (4/17) in control women. There was a significant difference in the prevalence of CD (p = 0.015). The LBR of patients with CD was similar to that of patients without CD. CD was associated with RPL, especially in patients with aneuploid miscarriage. However, since there was no difference in the LBR of patients with or without CD in the next pregnancy, it was unclear whether CD was a contributing cause of RPL.

Therapeutic efficacy of gentle endometrial curettage on antibiotic-resistant chronic endometritis in infertile women

Purpose

To identify the efficacy of endometrial curettage on antibiotic-resistant chronic endometritis (CE) in infertile women.

Methods

Of 1580 women with CE, 87 with antibiotic-resistant CE after two to five cycles of antibiotic treatment were recruited between 2019 and 2021. The women who underwent endometrial curettage without applying any force and, in the subsequent menstrual cycle, endometrial sampling for CD138 immunostaining without antibiotic use. Pregnancy outcomes after in vitro fertilization treatment were analyzed in women who did not desire endometrial curettage and in those with cured and persistent CE after endometrial curettage.

Results

In 64 women who underwent endometrial curettage, the number of CD138-positive cells decreased from 28.0 ± 35.3 to 7.7 ± 14.0 (p < 0.0001), and CE in 41 women (64.1%) was cured (<5 CD138-positive cells). The pathological findings detected 3.1% of endometrial hyperplasia and 1.6% of endometrial cancer. The ongoing pregnancy rates in women aged ≤42 without endometrial curettage were significantly lower than those of women with cured and persistent CE (26.7%, 67.6%, and 57.1%, respectively, p = 0.03).

Conclusions

Gentle endometrial curettage for antibiotic-resistant CE significantly decreased the number of CD138-positive cells, resulting in improved pregnancy outcomes regardless of remaining CE. Endometrial curettage is also important as a screening for endometrial malignancy.

Immunogenetic Role of IL17A Polymorphism in the Pathogenesis of Recurrent Miscarriage

Interleukin-17A (IL17A) is a proinflammatory cytokine and is assumed to play an important role in fetal rejection. In order to evaluate the potential role of IL17A polymorphism in the pathogenesis of recurrent miscarriage (RM), serum IL17A levels were estimated by ELISA. Single-nucleotide polymorphism was assessed by polymerase chain reaction-restriction fragment-length polymorphism (PCR-RFLP) using gene-specific primers and the EcoNI restriction enzyme. Serum IL17A levels were nonsignificantly (p > 0.5) low in RM patients compared with the control group. IL17A gene amplification by PCR yielded the undigested product of 815 bp, and its digestion with EcoNI enzyme produced 815, 529, 286, and 270 bp fragments for the GG genotype; 529, 286, and 270 bp fragments for the GA genotype; and 529 and 286 bp fragments for the AA genotype. The genotype frequency between the RM and control groups exhibited a significant difference (p = 0.001), whereas no significant difference was observed between allele frequencies in the two groups (p = 0.0954). These data suggest that the IL17A gene polymorphism exhibits no significant effect on IL17A gene expression. However, it significantly decreases and increases RM risk in the homozygous and recessive models, suggesting its potential pregnancy-protecting and -harming roles in the AA and GA + GG genotypes, respectively.

Bovine lactoferrin suppresses inflammatory cytokine expression in endometrial stromal cells in chronic endometritis

Chronic endometritis (CE) is a type of chronic inflammation in the endometrium that is associated with infertility, which is primarily due to implantation failure. Antibiotics are the most common treatment for CE. However, some patients with CE are resistant to antibiotic treatment, while others refuse this treatment. Therefore, we focused on lactoferrin (Lf), which exhibits antimicrobial and anti-inflammatory properties, and studied its effect on inflammation in endometrial stromal cells (ESCs) from patients with CE. Endometrial tissue was collected from patients with CE, and ESCs were isolated and cultured. When ESCs were cultured with bovine lactoferrin (bLf: 1 mg/mL), the mRNA expression of TNF-α (p < 0.05) and IL-1β (p < 0.01) was significantly decreased compared with that in cells cultured without bLf. The level of TNF-α protein in the culture medium was significantly decreased (p < 0.01), while that of IL-1β was also decreased, but not significantly (p < 0.10), when 1 mg/mL of bLf was added to the culture medium. When more inflammation was induced artificially by adding 0.1 ng/mL of TNF-αto ESCs, the addition of bLf (1 mg/mL) to ESCs decreased IL-6 and IL-1β mRNA expression to levels similar to those in ESCs without TNF-α treatment. Furthermore, it was revealed that the actions of bLf are mediated by the AKT and MAPK intracellular signaling pathways, which are mechanisms by which the increase in TNF-α-induced cytokine expression is suppressed in ESCs. bLf suppresses the expression of inflammatory cytokines in human ESCs and may be a new therapeutic candidate for CE.

Zooming in on the endometrial factor of recurrent implantation failure

Recurrent implantation failure (RIF) is a major limiting factor in the success rates of in-vitro fertilisation despite the remarkable clinical and technological advancement made at improving assisted reproductive technology. The primary purpose of the endometrium is to provide a receptive site for the implantation of the blastocyst and support its growth and subsequent development. Endometrial pathologies such as endometrial polyps, adenomyosis, Asherman's syndrome, chronic endometritis, and congenital Müllerian ducts defect negatively influence the integrity and receptivity of the endometrium, as well as the implantation of the embryo. This review highlights the implications of these endometrial pathologies and their association with RIF.

A case of discrepancy between three ERA tests in a woman with repeated implantation failure complicated by chronic endometritis

BACKGROUND

Endometrial receptivity array (ERA) is used to determine the timing of embryo transfer (ET) synchronized with the window of implantation (WOI). The effectiveness and evaluation of ERAs in women with recurrent implantation failure remain controversial. We report the case of a patient with recurrent implantation failure that raises the issue of reproducibility of ERA tests.

CASE REPORT

A 36-year-old Japanese woman with secondary infertility who had previously given birth failed to conceive after three frozen-thawed embryo transfer (FET) cycles. An ERA test was conducted to confirm the WOI. The first ERA test was performed 125 h after progesterone exposure. The laboratory reported that the endometrium was in a non-receptive (post-receptive) phase, and recommended retesting 101 h after progesterone exposure. A simultaneous chronic endometritis (CE) test showed a score of 3. After the antibiotics administration to treat CE, the second ERA test was performed after 101 h of progesterone exposure. The laboratory reported that the endometrium had not reached the WOI and estimated the WOI to be 113 ± 3 h after progesterone exposure. The third ERA test was performed 113 h after progesterone exposure. The laboratory reported that the endometrium was in a non-receptive (pre-receptive) phase and estimated the WOI to be 137 ± 3 h after progesterone exposure. A CE test performed at the same time as the second and third ERA tests showed a score of 1 for the collected endometrium. According to the third ERA test results, the vitrified-warmed blastocyst was transferred at 137 h of progesterone exposure. Pregnancy was achieved and the patient had an uncomplicated vaginal delivery at 39 weeks. One year later, another pregnancy was achieved after FET at 137 h of progesterone exposure, and the patient delivered at 33 weeks due to an unexpected membrane rupture.

CONCLUSION

Because the results of the ERA test may vary in the presence of CE, CE should be diagnosed simultaneously with or before conducting ERA tests. If CE is diagnosed, ERA testing should be performed after treatment with antimicrobials or other drugs.

Impact of antibiotic treatment for chronic endometritis on pregnancy outcomes in women with reproductive failures (RIF and RPL): A systematic review and meta-analysis

Objective

The aim of this study was to investigate the effect of antibiotic treatment for chronic endometritis (CE) on reproductive outcomes.

Design

Systematic review and meta-analysis.

Patients

Women with reproductive failures, including recurrent implantation failure (RIF), and recurrent pregnancy loss (RPL).

Interventions

Literature searches were performed using three electronic databases (PubMed, Embase, and Web of Science) until 1 December 2021 (without date restriction). The following comparators were included: women with CE receiving antibiotics vs. untreated controls; women with cured CE vs. women with normal endometrial histology (negative for CE); and women with cured CE vs. women with persistent CE (PCE). The summary measures were indicated as odds ratio (OR) with a 95% confidence interval (CI).

Main outcome measures

These include on-going pregnancy rate/live birth rate (OPR/LBR), clinical pregnancy rate (CPR), and miscarriage rate/pregnancy loss rate (MR/PLR).

Results

A total of 2,154 women (from twelve studies) were enrolled. Compared with the control group, women with CE receiving antibiotics did not show a statistically significant difference in OPR/LBR (P = 0.09) and CPR (P = 0.36), although there was a lower MR (P = 0.03). Women with cured CE have higher OPR/LBR (OR 1.57) and CPR (OR 1.56) in comparison with those with non-CE. There was a statistically significantly higher OPR/LBR (OR 6.82, P < 0.00001) and CPR (OR 9.75, P < 0.00001) in women with cured CE vs. those with persistent CE.

Conclusion

While antibiotic treatment is a sensible option to cure CE, more well-designed prospective studies are needed to evaluate the reproductive impact of antibiotic treatment. Cured CE provides high-quality maternal conditions for subsequent embryo transfer and successful pregnancy.

Chronic Endometritis in Infertile Women: Impact of Untreated Disease, Plasma Cell Count and Antibiotic Therapy on IVF Outcome-A Systematic Review and Meta-Analysis

This systematic review and meta-analysis aims to evaluate the impact of chronic endometritis (CE) and its therapy on in vitro fertilization (IVF) outcome. Additionally, we aim to investigate whether various degrees of CE severity may exert a different effect on IVF outcome. Ongoing-pregnancy rate/live-birth-rate (OPR/LBR), clinical-pregnancy rate (CPR), and miscarriage rate (MR) were calculated. A total number of 4145 patients (from ten studies) were included. Women with CE had lower OPR/LBR (OR 1.97, p = 0.02) and CPR (OR 2.28, p = 0.002) compared to those without CE. CE cure increased OPR/LBR (OR 5.33, p < 0.0001) and CPR (OR 3.64, p = 0.0001). IVF outcome was comparable between women with cured CE and those without CE (OPR/LBR, CPR and MR: p = ns). Women with severe CE had lower OPR/LBR (OR 0.43, p = 0.003) and CPR (OR 0.40, p = 0.0007) compared to those mild CE. Mild CE showed no influence on the IVF outcome as compared to women without CE (OPR/LBR, CPR and MR: p = ns). Based on this data analysis, CE significantly reduces OPR/LBR and CPR in women undergoing IVF. Importantly, CE resolution after antibiotic therapy may improves IVF outcome, leading to similar OPR/LBR and CPR as compared to unaffected patients. The negative effects of CE on IVF outcome may be restricted to severe disease, whereas mild CE may have no influence on IVF success.

Single-cell analysis of menstrual endometrial tissues defines phenotypes associated with endometriosis

BACKGROUND

Endometriosis is a common, complex disorder which is underrecognized and subject to prolonged delays in diagnosis. It is accompanied by significant changes in the eutopic endometrial lining.

METHODS

We have undertaken the first single-cell RNA-sequencing (scRNA-Seq) comparison of endometrial tissues in freshly collected menstrual effluent (ME) from 33 subjects, including confirmed endometriosis patients (cases) and controls as well as symptomatic subjects (who have chronic symptoms suggestive of endometriosis but have not been diagnosed).

RESULTS

We identify a unique subcluster of proliferating uterine natural killer (uNK) cells in ME-tissues from controls that is almost absent from endometriosis cases, along with a striking reduction of total uNK cells in the ME of cases (p < 10^-16). In addition, an IGFBP1+ decidualized subset of endometrial stromal cells are abundant in the shed endometrium of controls when compared to cases (p < 10^-16) confirming findings of compromised decidualization of cultured stromal cells from cases. By contrast, endometrial stromal cells from cases are enriched in cells expressing pro-inflammatory and senescent phenotypes. An enrichment of B cells in the cases (p = 5.8 × 10^-6) raises the possibility that some may have chronic endometritis, a disorder which predisposes to endometriosis.

CONCLUSIONS

We propose that characterization of endometrial tissues in ME will provide an effective screening tool for identifying endometriosis in patients with chronic symptoms suggestive of this disorder. This constitutes a major advance, since delayed diagnosis for many years is a major clinical problem in the evaluation of these patients. Comprehensive analysis of ME is expected to lead to new diagnostic and therapeutic approaches to endometriosis and other associated reproductive disorders such as female infertility.

The Regulators of Human Endometrial Stromal Cell Decidualization

Several factors are important for implantation and subsequent placentation in the endometrium, including immunity, angiogenesis, extracellular matrix, glucose metabolism, reactive oxidative stress, and hormones. The involvement or abnormality of these factors can impair canonical decidualization. Unusual decidualization can lead to perinatal complications, such as disruption of trophoblast invasion. Drastic changes in the morphology and function of human endometrial stromal cells (hESCs) are important for decidualization of the human endometrium; hESCs are used to induce optimal morphological and functional decidualization in vitro because they contain estrogen and progesterone receptors. In this review, we will focus on the studies that have been conducted on hESC decidualization, including the results from our laboratory.

Serum amyloid A, a host-derived DAMP in pregnancy?

Serum amyloid A (SAA) is one of the acute phase proteins released primarily from the liver in response to infection, inflammation and trauma. Emerging evidence indicates that SAA may function as a host-derived damage-associated molecular pattern (DAMP) protein to sense danger signals in pregnancy. The plasma SAA levels in maternal circulation are significantly increased in normal parturition, particularly in postpartum, as well as in gestational disorders such as premature preterm rupture of membranes, pre-eclampsia, gestational diabetes, and recurrent spontaneous abortion. It is likely that SAA acts as a non-specific DAMP molecule in response to inflammation and trauma experienced under these conditions. Notably, SAA can also be synthesized locally in virtually all gestational tissues. Within these gestational tissues, under the induction by bacterial products, pro-inflammatory cytokines and stress hormone glucocorticoids, SAA may exert tissue-specific effects as a toll-like receptor 4 (TLR4)-sensed DAMP molecule. SAA may promote parturition through stimulation of inflammatory reactions via induction of pro-inflammatory cytokines, chemokines, adhesion molecules and prostaglandins in the uterus, fetal membranes and placenta. In the fetal membranes, SAA may also facilitate membrane rupture through induction of matrix metalloproteases (MMPs)- and autophagy-mediated collagen breakdown and attenuation of lysyl oxidase-mediated collagen cross-linking. SAA synthesized in extravillous trophoblasts may promote their invasiveness into the endometrium in placentation. Here, we summarized the current understanding of SAA in pregnancy with an aim to stimulate in-depth investigation of SAA in pregnancy, which may help better understand how inflammation is initiated in gestational tissues in both normal and abnormal pregnancies.

Multi-drug-resistant chronic endometritis in infertile women with repeated implantation failure: trend over the decade and pilot study for third-line oral antibiotic treatment

PURPOSE

To evaluate the yearly prevalence and annual transition of multi-drug-resistant-chronic endometritis (MDR-CE) in infertile women with a history of repeated implantation failure (RIF) and to establish the third-line antibiotic treatment regimen against MDR-CE.

METHODS

This retrospective/prospective cohort and pilot study included 3473 RIF women between April 2010 and September 2021. The endometrial stromal plasmacyte density index (ESPDI) was calculated in 3449 CD138-immunostained endometrial sections to evaluate CE. The microbiota in the vaginal secretions and endometrial fluid was compared between 17 patients with MDR-CE and 16 patients with antibiotics-sensitive CE. In a pilot study, oral moxifloxacin (400 mg/day, 10 days, n = 24) or azithromycin (500 mg/day, 3 days, n = 24) was administered to eligible patients with MDR-CE.

RESULTS

From April 2010 to March 2020, CE was detected in 31.4% of RIF women and MDR was detected in 7.8% of CE. While the prevalence of CE was stable for a decade, MDR in CE increased steadily (OR 8.27, 95% CI 2.58-26.43, p trend < 0.001). The bacterial species/communities unique to MDR-CE were not found. The histopathologic cure rate of MDR-CE was similar between the moxifloxacin and azithromycin groups (79.2% vs 75.0%, OR 1.27, 95% CI 0.32-4.89, p value 0.73), as well as reproductive outcomes in subsequent embryo transfer cycles.

CONCLUSION

In RIF women, MDR in CE increased over the decade. As a third-line treatment for MDR-CE, azithromycin may have a clinical advantage due to its shorter time administration periods.

CLINICAL TRIAL NUMBER

ClinicalTrials.gov Identifier: UMIN-CTR 000029449/000031909.

Acupuncture for Female Infertility: Discussion on Action Mechanism and Application

A higher incidence of female infertility has been reported with an unexpectedly early appearance in recent years. The female infertility treatment and application of assisted reproductive technology have recently gained immense interest from scientists. Many studies have discussed the beneficial effects of acupuncture on female infertility. With advancements in science and medical technology, acupuncture-related research has increased in investigating its effectiveness in treating female infertility. This review focuses on a compilation of research in recent years on acupuncture for female infertility treatment and the exploration of the underlying mechanism. For this purpose, literature was searched using various search engines like PubMed, Web of Science, and Google Scholar. The search was refined by only focusing on recent studies on acupuncture effectiveness and mechanism in female infertility and evaluating pregnancy outcomes.

Diagnosing chronic endometritis: when simplification fails to clarify

Reproductive immunology has grown in importance in recent years and has even developed into a discipline of its own within the field of reproductive medicine. Many aspects of reproductive failure such as repeated implantation failure or recurrent miscarriages are, meanwhile, seen as a consequence of aberrant expression of immunological factors. This is reflected by the increasing number of tests for assessing and quantifying different immune cell types as well as by a wide range of immune therapies offered to a clientele consisting of desperate patients requesting additional ‘IVF tools’: first, what is still usually disregarded is the enormous plasticity and fluctuation of most immune cells in the genital tract; second, their still poorly characterized functions in the endometrial cycle: further, their partially unknown role in embryo implantation and in establishing a pregnancy; and third, the fact that one of the fundamental hypotheses of reproductive immunology—of note—the Medawar concept or ‘Medawar's Paradox’ of semi-allogeneic graft embryo, is partially based on an erroneous assumption, i.e. the immunologic rejection and tolerance of an embryo. In the present opinion article, we comment on the diagnostic procedures and therapy approaches for chronic endometritis within the scope of reproductive medicine.

Differential Vaginal Microbiota Profiling in Lactic-Acid-Producing Bacteria between Infertile Women with and without Chronic Endometritis

Purpose: Chronic endometritis (CE) is an infectious and inflammatory disorder associated with infertility of unknown etiology, repeated implantation failure, and recurrent pregnancy loss. In the current clinical practice, intrauterine interventions such as endometrial biopsy/histopathologic examinations and/or hysteroscopy are required for the diagnosis of CE. In this study, we analyzed the microbiota in vaginal secretions (VS) as a potential prediction tool for CE in infertile women. Methods: Using next-generation sequencing analysis, we compared the VS and endometrial fluid (EF) microbiota in infertile women with (n = 20) or without CE (n = 103). Results: The detection rate of Streptococcus and Enterococcus as well as the bacterial abundance of Atopobium and Bifidobacterium in the VS microbiota was significantly lower in the CE group than in the non-CE group. Meanwhile, the detection rate and bacterial abundance of Lactobacillus in the EF and VS microbiota were at similar levels between the two groups. Conclusion: These findings suggest that VS microbiota in infertile women with CE is characterized by the reduction in Bifidobacterium and lactic-acid-producing bacteria other than Lactobacillus. Our results hold promise for the prediction of CE, not by somewhat interventional intrauterine procedures, but by less invasive VS sampling. TRIAL REGISTRATION NUMBER: UMIN000029449 (registration date 6 October 2017).

The association between chronic deciduitis and preeclampsia

Chronic deciduitis (CD) is slight inflammation of the decidua found during pregnancy. The cause of preeclampsia is thought to be placental hypoplasia, and various theories have been proposed to explain the detailed mechanism; however, its association with decidual inflammation is unclear. A retrospective case control study was conducted in a single university. Subjects were cases who delivered by cesarean section between January 1, 2013 and June 30, 2020 and whose placentas were pathological assessed. CD was diagnosed by CD138 immunostaining of placental decidua tissue, and the perinatal prognosis and incidences of hypertensive disorder of pregnancy and preeclmpsia were examined according to the presence or absence of CD. A logistic regression analysis was performed to evaluate the association between preeclampsia and 11 explanatory variables (10 patient or perinatal background factors and CD). The study population included 76 patients (non-CD, n = 54; CD, n = 22). The rate of preeclampsia was significantly higher in the CD group (P = 0.0006). Patients with CD gave birth at a significantly earlier gestational age (P=0.040) with a lower birth weight (P = 0.001), and a higher rate of LFD (P = 0.005). The Apgar scores at 1 and 5 min and umbilical artery pH were lower (P = 0.0003, 0.021 and 0.002, respectively) in the CD group. The logistic regression analysis revealed that CD was positively associated with preeclampsia. A retrospective examination of the placenta found that patients with CD had a significantly higher incidence of preeclampsia and CD is considered to be a factor that is associated with poor perinatal outcomes.

Overexpression of hypoxia-inducible factor 1α and excessive vascularization in the peri-implantation endometrium of infertile women with chronic endometritis

OBJECTIVE

Chronic endometritis (CE) contributes to impaired endometrial receptivity and is closely associated with poor in vitro fertilization (IVF) outcomes. However, the mechanisms underlying CE are unclear. Here, we investigated the role of the hypoxic microenvironment and endometrial vascularization in the peri-implantation endometrium of infertile women with CE.

METHODS

This retrospective study involved 15 fertile women and 77 infertile patients diagnosed with CE based on CD138+ ≥1/10 high-power fields (HPFs). The CE patients were divided into Group 1 (CD138+ 1-4/10 HPFs, 53 cases) and Group 2 (CD138+ ≥5/10 HPFs, 24 cases). The expression levels of hypoxia-inducible factor 1α (HIF1α), vascular endothelial growth factor A (VEGFA), and vascular endothelial growth factor receptor 2 (VEGFR2) in peri-implantation endometrium were assessed by qRT-PCR and western blot analyses. Spatial levels of HIF1α, VEGFA, and VEGFR2 in various endometrial compartments was determined using immunohistochemistry and H-score analysis. Microvascular density (MVD) was determined using CD34 staining and scored using Image J. Finally, we used qRT-PCR to assess changes in the expression of HIF1α, VEGFA, and VEGFR2 in CE patients after treatment with first-line antibiotics.

RESULTS

Relative to Group 1 and control group, during the implantation window, protein and mRNA levels of HIF1α, VEGFA, and VEGFR2 were markedly high in Group 2 (P<0.05). H-score analysis showed that HIF1α, VEGFA, and VEGFR2 in the luminal, glandular epithelium, and stromal compartments were markedly elevated in Group 2, comparing to control group and Group 1 (P<0.05). Moreover, markedly elevated MVD levels were observed in Group 2. Notably, the above indexes did not differ significantly in the control group versus Group 1. Treatment with antibiotics significantly suppressed the endometrial HIF1α and VEGFA levels in CE-cured patients.

CONCLUSIONS

Here, we for the first time report the upregulation of HIF1α, VEGFA, and VEGFR2, as well as excessive endometrial vascularization in the peri-implantation endometrium of CE patients. Our findings offer new insights into reduced endometrial receptivity in CE-associated infertility.

Occurrence of chronic endometritis in different types of human adenomyosis

Purpose

Human adenomyosis has an adverse effect on female fertility. Exact mechanistic basis is still unclear. We investigated the occurrence of chronic endometritis (CE) in different types of human adenomyosis.

Methods

This is a prospective non‐randomized observational study enrolling patients with focal (n = 30), diffuse (n = 26), intrinsic (n = 23), and extrinsic (n = 10) adenomyosis. Endometrial biopsy samples were collected from hysterectomy specimens. Immunohistochemical analysis was performed using antibody against CD68 (Mφ marker) with biopsy samples of intrinsic/extrinsic adenomyosis and CD138 (Syndecan‐1), a marker of plasma cells, in all biopsy samples.

Results

In GnRHa‐untreated groups, a higher trend in the occurrence of CE, as characterized by infiltration of ≥1 plasma cells in endometrial stroma, was found in women with focal (58.8%, p = 0.0849) and diffuse adenomyosis (60.0%, p = 0.0841) comparing to control women (10.0%). In women with focal adenomyosis, ipsilateral side showed a significantly higher occurrence of CE (58.8%) than on the contralateral side (11.7%) (p = 0.043). Tissue infiltration of macrophages in endometria was significantly higher in intrinsic than in extrinsic adenomyosis (p = 0.03) without showing any significant difference in the occurrence of CE between these two variants of adenomyosis.

Conclusion

A variable occurrence of CE in different types of adenomyosis may be involved in adverse reproductive outcome.

Subsequent IVF outcomes following antibiotic therapy for chronic endometritis in patients with recurrent implantation failure

AIM

The aim is to identify the chronic endometritis (CE) incidence in recurrent implantation failure (RIF) patients undergoing in vitro fertilization (IVF) treatment and compare the IVF outcomes of RIF patients with CE following antibiotic therapy with RIF patients without CE. Another purpose is to compare the IVF outcomes of described RIF patients with patients undergoing the first cycle of IVF.

METHODS

In this retrospective cohort study, CE was diagnosed with CD-138 immunohistochemical staining. Among RIF patients, two groups were formed as group 1, including patients diagnosed with CE and treated by antibiotics (n = 129), and group 2, including patients without CE (n = 103). Patients with the first IVF cycle having similar infertility etiologies with RIF patients were reviewed as group 3 (n = 932).

RESULTS

CE was diagnosed in 55.6% of RIF patients. The number of oocytes retrieved was not different between groups. Implantation rates (IR) were similar after antibiotic treatment in RIF patients with or without CE. However, Group 3 had a higher IR (41.1%) than group 1 and 2 (23.1% and 30.1%, respectively) (p < 0.001). Clinical pregnancy (CPR) and live birth rates (LBR) were comparable between RIF groups. However, CPR and LBR were significantly higher in group 3 (48.6% and 40.5%) than group 1 (36.4% and 27.9%), and group 2 (37.9% and 30.1%) (p = 0.007 and p = 0.005, respectively).

CONCLUSION

Unidentified endometrial factors except CE may also affect the implantation process, although CE is a frequent finding in patients with RIF. Reproductive outcomes may not be improved only with antibiotics in RIF patients with CE.

Deciphering the Role of PGRMC1 During Human Decidualization Using an In Vitro Approach

CONTEXT

Non-classical membrane progesterone receptor (mPRs) and progesterone receptor membrane component 1 (PGRMC1) expression have been detected in endometrium, but their role in decidualization had not yet been investigated. We previously demonstrated PGRMC1 downregulation in receptive endometrium and that its overexpression inhibits decidualization. Furthermore, during decidualization, PGRMC1 mainly interacts with proteins involved in biosynthesis, intracellular transport, and mitochondrial activity.

OBJECTIVE

To determine PGRMC1 and mPRs signaling role during decidualization.

METHODS

Isolated primary endometrial stromal cells (EnSC) were decidualized in vitro in the presence of classic stimuli (E2 + P4), PGRMC1 inhibitor (AG205), or membrane-impermeable P4 (P4-BSA). Endometrial biopsies were obtained from 19 fertile oocyte donors attending the IVI-Valencia in vitro fertilization (IVF) clinic. EnSC decidualization was evaluated by prolactin ELISA and F-actin immunostaining. Progesterone receptor localization was evaluated by immunofluorescence. EnSC transcriptomic profiles were analyzed by microarray technology.

RESULTS

PGRMC1 inhibition during EnSC decidualization (AG205dEnSC) does not interfere with EnSC cytoskeletal rearrangements and prolactin secretion. However, global transcriptional profiling revealed more differentially expressed genes in AG205dEnSC than in dEnSC, compared with nondecidualized EnSC (ndEnSC). In silico analysis showed that PGRMC1 inhibition upregulated more genes related to metabolism, molecular transport, and hormonal biosynthesis compared with control dEnSC. EnSC decidualized in the presence of P4-BSA showed a similar behavior as ndEnSC in terms of morphological features, absence of prolactin secretion, and transcriptomic pattern.

CONCLUSION

Our findings associate PGRMC1 to hormonal biosynthesis, metabolism, and vesicular transport-important cellular functions for dEnSC supporting pregnancy. Activation of membrane P4 receptor signaling alone was unable to induce downstream effects needed for proper decidualization.

Clinical consequences of defective decidualization

Decidualization is characterized by a series of genetic, metabolic, morphological, biochemical, vascular and immune changes occurring in the endometrial stroma in response to the implanting embryo or even before conception and involves the stromal cells of the endometrium. It is a fundamental reproductive event occurring in mammalian species with hemochorial placentation. A growing body of experimental and clinical evidence strongly suggests that defective or disrupted decidualization contributes to the establishment of an inappropriate maternal-fetal interface. This has relevant clinical consequences, ranging from recurrent implantation failure and recurrent pregnancy loss in early pregnancy to several significant complications of advanced gestation. Moreover, recent evidence indicates that selected diseases of the endometrium, such as chronic endometritis and endometriosis, can have a detrimental impact on the decidualization response in the endometrium and may help explain some aspects of the reduced reproductive outcome associated with these conditions. Further research efforts are needed to fully understand the biomolecular mechanisms ans events underlying an abnormal decidualization response. This will permit the development of new diagnostic and therapeutic strategies aimed to improve the likelihood of achieveing a successful pregnancy.

Immunological Testing in Assisted Reproductive Technology

Fetal implantation requires carefully orchestrated involvement of the maternal immune system. Aberrant function within implantation has been suggested as a cause of implantation failure. The emergence of immunological theories of miscarriage has led to immunological testing as an adjuvant treatment in assisted reproductive technology; however, it remains controversial, with mixed evidence both for immunological cause and the benefits of immunological testing. Literature on common methods of immunological testing within assisted reproductive technology is reviewed including those of peripheral and uterine natural killer cells, chronic endometritis, and T-helper cells cytokine ratio. There is little consensus in the evidence on immunological testing in the context of recurrent implantation failure. The field is limited by a lack of uniformity in approach to testing and heterogeneity of the pathophysiological cause. Nevertheless, the maternal immune system is heavily involved in implantation and the new era of personalized medicine ensures that a more defined approach to immunological testing will be achieved.

CHRONIC ENDOMETRITIS IN PATIENTS WITH REPEATED IMPLANTATION FAILURES:EPIDEMIOLOGY, ETIOLOGY, PATHOGENESIS AND OVERCOMING INFERTILITY

Recent evidence indicates that the endometrium plays a much more important role in successful implantation and clinical pregnancy than many other recognized factors. Chronic endometritis (CE) is associated with negative reproductive outcomes, including repeated implantation failures. Streptococcus spp., Escherichia coli, Enterococcus faecalis, Klebsiella pneumoniae, Staphylococcus spp., Corynebacterium and Mycoplasma / Ureaplasmaspp are currently considered the main pathogens of CE. This disease disrupts the architectonics of the endometrium at different levels: first of all, CE promotes changes in the population of immunocompetent cells and, therefore, contributes to the disruption of the local immune response in the endometrium at the time of implantation. Antibiotic treatment for CE improves implantation rates and decreases abortion rates, although there are no well-designed prospective studies to support this conclusion. Considering the insufficient effectiveness of antibiotic therapy for CE, especially in cases of resistance of pathogens, or in the case of viral chronic endometritis, it is necessary to develop schemes with additional use of drugs that affect other etiopathogenetic pathways of development and maintenance of CE. An example of such a treatment can be cytokine therapy, which requires further study regarding the efficacy and safety in CE therapy.

Evaluating the influence of progesterone concentration and time of exposure on in vitro endometrial decidualisation

This study aimed to evaluate the influence of progesterone (concentration and time of exposure) on endometrial decidualisation using an in vitro model cell line: Human Endometrial Stromal Cells (HESCs). HESCs exposed to progesterone (1 and 10 μM) had higher percentages of decidualised cells and higher expression of the decidual marker (Insulin Like Growth Factor Binding Protein 1 (IGFBP1)) compared with those exposed to (0.1 μM). Among those HESCs cultured with 1 μM progesterone for 11 days, the highest rate of morphological differentiation (40-50%) occurred between days 7-9 and IGFBP1 peaked on day 7. The cell-cycle pathway was significantly down-regulated in HESCs exposed to at least 1 μM progesterone regardless of the incubation period. We conclude that exposure to high progesterone concentration for 7-9 days is essential to maximise the process of decidualisation.

Investigation of infertility using endometrial organoids

Infertility is a common problem in modern societies with significant socio-psychological implications for women. Therapeutic interventions are often needed which, depending on the cause, can either be medical treatment, surgical procedures or assisted reproductive technology (ART). However, the treatment of infertility is not always successful due to our limited understanding of the preparation of the lining of the uterus, the endometrium, for pregnancy. The endometrium is of central importance for successful reproduction as it is the site of placental implantation providing the interface between the mother and her baby. Due to the dynamic, structural and functional changes the endometrium undergoes throughout the menstrual cycle, it is challenging to study. A major advancement is the establishment of 3D organoid models of the human endometrium to study this dynamic tissue in health and disease. In this review, we describe the changes that the human endometrium undergoes through the different phases of the menstrual cycle in preparation for pregnancy. We discuss defects in the processes of endometrial repair, decidualization and acquisition of receptivity that are associated with infertility. Organoids could be utilized to investigate the underlying cellular and molecular mechanisms occurring in non-pregnant endometrium and early pregnancy. These studies may lead to therapeutic applications that could transform the treatment of reproductive failure.

BAG2-Mediated Inhibition of CHIP Expression and Overexpression of MDM2 Contribute to the Initiation of Endometriosis by Modulating Estrogen Receptor Status

Endometriosis is an estrogen-dependent gynecological disease primarily affecting women of childbearing age, which gives rise to pelvic pain calling for multiple operations, and sometimes leading to infertility. However, the etiology of endometriosis remains poorly understood. In this study we investigated the roles of two Ubiquitin E3 Ligases, namely hsc70-interacting protein (CHIP) and mouse double minute 2 (MDM2), in the abnormal estrogenic activity in endometriosis. We first collected endometrial tissues from 91 cases of endometriosis and 78 cases of uterine myomas. Next, we established a murine endometriosis model by ectopic endometrial tissue implantation. In other studies, we isolated human endometrial stromal cells (HESCs) were isolated from the endometrial tissues, and performed HA- or FLAG-immunoprecipitation assays and immunoblotting with an anti-ubiquitin antibody to test the interactions among BAG2, CHIP, MDM2, estrogen receptor α (ERα), and ERβ. The expression of ERα was downregulated while that of ERβ, BAG2, and MDM2 was upregulated in human endometriosis and in the mouse model. CHIP degraded ERβ instead of ERα via the ubiquitin-proteasome pathway, while BAG2 impaired the CHIP-mediated degradation of ERβ in cultured HESCs derived from human endometriosis. The degradation of ERα by MDM2 in cultured endometriosis-HESCs also occurred through the ubiquitin-proteasome pathway. Knockdown of both BAG2 and MDM2 alleviated the development of endometriosis in mice. Our findings suggest that the interference of BAG2 and MDM2 may have therapeutic effects in endometriosis. Understanding better the molecular mechanisms underlying the regulation of the abnormal estrogenic activity in endometriosis is crucial for the advancement of targeted therapeutic strategies.

Induction of the epithelial-mesenchymal transition in the endometrium by chronic endometritis in infertile patients

Background

The purpose of the present study was to evaluate the relationship between chronic endometritis and the epithelial-mesenchymal transition in the endometrium of infertile patients in the implantation phase.

Methods

Endometrial biopsy specimens from 66 infertility patients were analyzed. The presence of chronic endometritis was investigated by immunostaining for CD138. Immunohistochemical staining for E-cadherin, N-cadherin, Slug, and Snail was performed, and the expression profiles were statistically analyzed according to the presence of chronic endometritis. When the loss of E-cadherin expression and/or the positive expression of N-cadherin was detected, the specimen was considered epithelial-mesenchymal transition-positive. Epithelial-mesenchymal transition-positive cases were also statistically analyzed according to the presence of chronic endometritis. The characteristics of the patients in the epithelial-mesenchymal transition-positive and epithelial-mesenchymal transition-negative groups were compared. The association between variables, including age, body mass index, gravidity, parity, and each causative factor of infertility and epithelial-mesenchymal transition positivity was analyzed.

Results

The rates of the loss of E-cadherin expression, the gain of N-cadherin and epithelial-mesenchymal transition positivity were significantly higher in chronic endometritis patients. The expression of Slug, cytoplasmic Snail, and nuclear Snail was also detected at significantly higher rates in chronic endometritis patients. Chronic endometritis were related to the epithelial-mesenchymal transition.

Conclusion

The epithelial-mesenchymal transition was frequently detected in the endometrium in infertile patients with chronic endometritis. Since the epithelial-mesenchymal transition is associated with chronic endometritis, the epithelial-mesenchymal transition appears to be involved in the alteration of mechanisms of implantation.

Incidence and risk factors for velamentous umbilical cord insertion in singleton pregnancies after assisted reproductive technology

AIM

Assisted reproductive technology (ART) is gaining popularity worldwide. However, it is associated with increased incidence of velamentous umbilical cord insertion (VCI) in the placenta, resulting in adverse perinatal outcomes. This study aimed to identify the risk factors that might affect the incidence of VCI in pregnancies after ART treatment.

METHODS

We retrospectively analyzed the records of 906 singleton pregnancies via ART; all women delivered in our facility. Three ART-related variables and infant sex were examined: (1) fertilization method (conventional in vitro fertilization or intracytoplasmic sperm injection), (2) type of embryo at the time of transfer (fresh or frozen-thawed), (3) developmental stage of embryo at the time of transfer (cleavage stage or blastocyst), and (4) infant sex (male or female). Logistic regression analysis was used to assess the impact of these variables on the incidence of VCI.

RESULTS

Of 906 cases, 55 had VCI (incidence rate, 6.1%). After adjusting for potential confounders, blastocyst stage of development (adjusted odds ratio [aOR]: 4.3, 95% confidence interval [CI]: 1.9-12.7) and female sex (aOR: 2.2, 95% CI: 1.2-3.9) emerged as independent risk factors for the development of VCI. The fertilization method and type of embryo at the time of transfer did not affect the incidence of VCI.

CONCLUSIONS

Blastocyst stage of development and female sex pose a higher risk for developing VCI. Thus, more attention should be paid to pregnancies achieved by blastocyst and with a female fetus to detect VCI proactively and safeguard the health of both mother and fetus/neonate.

Histological diagnostic criterion for chronic endometritis based on the clinical outcome

BACKGROUND

The diagnostic criteria of chronic endometritis remain controversial in the treatment for infertile patients.

METHODS

A prospective observational study was conducted in a single university from June 2014 to September 2017. Patients who underwent single frozen-thawed blastocyst transfer with a hormone replacement cycle after histological examination for the presence of chronic endometritis were enrolled. Four criteria were used to define chronic endometritis according to the number of plasma cells in the same group of patients: 1 or more (≥ 1) plasma cells, 2 or more (≥ 2), 3 or more (≥ 3), or 5 or more (≥ 5) in 10 high-power fields. Pregnancy rates, live birth rates, and miscarriage rates of the non-chronic endometritis and the chronic endometritis groups defined with each criterion were calculated. A logistic regression analysis was performed for live births using eight explanatory variables (seven infertility factors and chronic endometritis). A receiver operating characteristic curve was drawn and the optimal cut-off value was calculated.

RESULTS

A total of 69 patients were registered and 53 patients were finally analyzed after exclusion. When the diagnostic criterion was designated as the presence of ≥ 1 plasma cell in the endometrial stroma per 10 high-power fields, the pregnancy rate, live birth rate, and miscarriage rate were 63.0% vs. 30.8%, 51.9% vs. 7.7%, and 17.7% vs. 75% in the non-chronic and chronic endometritis groups, respectively. This criterion resulted in the highest pregnancy and live birth rates among the non-chronic endometritis and the smallest P values for the pregnancy rates, live birth rates, and miscarriage rates between the non-chronic and chronic endometritis groups. In the logistic regression analysis, chronic endometritis was an explanatory variable negatively affecting the objective variable of live birth only when chronic endometritis was diagnosed with ≥ 1 or ≥ 2 plasma cells per 10 high-power fields. The optimal cut-off value was obtained when one or more plasma cells were found in 10 high-power fields (sensitivity 87.5%, specificity 64.9%).

CONCLUSIONS

Chronic endometritis should be diagnosed as the presence of ≥ 1 plasma cells in 10 high-power fields. According to this diagnostic criterion, chronic endometritis adversely affected the pregnancy rate and the live birth rate.

Impact of chronic endometritis in infertility: a SWOT analysis

Chronic endometritis is a pathology often associated with reproductive failure, but there are still no clear recommendations on whether its inclusion in the initial study of infertile couples is necessary. In this discussion paper, based on a SWOT (Strengths, Weaknesses, Opportunities, Threats) analysis, the different aspects of the repercussions of chronic endometritis in fertility are evaluated. To avoid possible subjectivity in the analysis and results of this study, the researchers followed the Oxford criteria for the evaluation of evidence. The results from the evaluation of the reviewed literature seem to indicate that, pending new evidence, it would be advisable not to include chronic endometritis in the initial baseline study before assisted reproduction in order not to delay other assisted reproduction treatments. However, it would be advisable in cases of repetitive implantation failure and pregnancy loss after having undergone IVF with viable embryos and before continuing with costly reproductive processes, since results could be improved. The development of randomized studies assessing the impact of antibiotic treatment as a possible therapeutic option in infertile women with chronic endometritis, as well as the possible impact on endometrial microbiota and receptivity/implantation, would allow for the establishment of more precise clinical guidelines in this regard.

Endometrial causes of recurrent pregnancy losses: endometriosis, adenomyosis, and chronic endometritis

Chronic inflammatory processes affecting the endometrium, as encountered in endometriosis, adenomyosis, and chronic endometritis, alter endometrial receptivity. These disorders are associated with early pregnancy losses and possibly recurrent pregnancy losses (RPL). In the cases of endometriosis, other factors associated with the disease also are susceptible of causing miscarriages and possibly RPL, such as an impact of intrapelvic inflammatory processes affecting the oocyte and embryo in case of natural conception. Conversely these latter effects obviously are bypassed in case of assisted reproductive technology. Chronic inflammation of the endometrium in the condition known as chronic endometritis also causes early pregnancy losses and RPL with beneficial effects achieved when specific treatment is undertaken.

Analysis of the therapeutic effects of hysteroscopic polypectomy with and without doxycycline treatment on chronic endometritis with endometrial polyps

PROBLEM

We aimed to compare the therapeutic effects of hysteroscopic polypectomy with and without doxycycline treatment on chronic endometritis (CE) with endometrial polyps.

METHOD OF STUDY

DESIGN: A cross-sectional study was conducted on 267 infertile patients, of whom 243 were recruited, who underwent hysteroscopic polypectomy between March 2019 and March 2020. During surgery, the endometrial specimens for the immunohistochemistry analysis of the plasma cell marker CD138 and for the intrauterine bacterial culture were obtained to diagnose CE, and the prevalence of CE was analyzed. Of the 222 women who were diagnosed with CE after polypectomy, we treated 62 women with doxycycline (antibiotic group) and did not provide antibiotics in 160 women (non-antibiotic group).

RESULTS

Most of the infertile patients with endometrial polyps had CE (92.6%). The recovery rate from CE by hysteroscopic polypectomy was significantly higher in the non-antibiotic group than in the antibiotic group (88.8% and 58.1%, respectively, p < 0.0001). The duration of recovery from CE in the non-antibiotic group was shorter than that in the antibiotic group (42.6 ± 41.0 and 56.5 ± 32.3 days, respectively, p < 0.0001). The clinical pregnancy rate within 6 months in non-antibiotic group was higher than that in the antibiotic group (63.2% and 43.8%, respectively, p = 0.034).

CONCLUSION

Endometrial polyps are significantly associated with CE. Most CE patients with endometrial polyps had been cured by polypectomy without doxycycline. Inappropriate antibiotic therapy may delay recovery from CE and decrease the efficacy of polypectomy on CE and pregnancy rates.

Platelet-Rich Plasma as a Potential New Strategy in the Endometrium Treatment in Assisted Reproductive Technology

The success rate of assisted reproduction techniques (ART) has long been less than satisfactory albeit the great progress made in recent years, demonstrating the need for alternative options in the ART cycles. Growing evidence correlates the effect of intrauterine platelet-rich plasma (PRP) infusion on the endometrium with reassuring reproductive results. Thus, in this review, we focus on the current clinical and mechanical evidence on PRP and its effect on endometrial receptivity, and assess the features, benefits and limitations of the current studies and potential risks of PRP in ART.

CHRONIC ENDOMETRITIS - MODERN CONCEPTS, PRINCIPLES OF MAINTENANCE. LITERATURE REVIEW

In our review article, we assessed the etiological factors of chronic endometritis, the most frequent manifestations of clinical and endoscopic data, the effectiveness of various diagnostic procedures and existing treatment methods. However, until now, many questions of the optimal algorithm for the diagnosis and treatment of this pathology remain open and require further study. In connection with the above, a certain practical and scientific interest may be of prospective studies assessing modern diagnostic and treatment methods for ChE, their impact on the number of unsuccessful reproductive outcomes of ART programs, taking into account the personal characteristics of the reproductive system of patients.

Chronic endometritis and altered embryo implantation: a unified pathophysiological theory from a literature systematic review

PURPOSE

Chronic endometritis (CE) is a frequent hysteroscopic and histological finding which affects embryo transfer implantation during IVF-ICSI cycles. In particular, CE impairs proper decidualization and, subsequently, implantation. Although this correlation has been clearly clarified, a pathophysiological explanation assembling all the studies performed has not been elucidated yet. For this reason, we have structured a systematic review considering all the original articles that evaluated a pathological element involved in CE and implantation impairment.

METHODS

The authors searched electronic databases and, after screening, collected 15 original articles. These were fully scanned and used to create a summary pathway.

RESULTS

CE is primarily caused by infections, which lead to a specific cytokine and leukocyte pattern in order to prepare the uterus to fight the noxa. In particular, the immunosuppression requested for a proper semi-allogenic embryo transfer implantation is converted into an immunoreaction, which hampers correct embryo implantation. Moreover, endometrial vascularization is affected and both irregular vessel density and luminal thickening and thrombosis reduce what we have first identified as endometrial flow reserve. Finally, incorrect uterine wave propagation could affect embryo contact with decidua.

CONCLUSION

This is the first summary of evidence on CE pathophysiology and its relationship with infertility. Understanding the CE pathophysiology could improve our knowledge in embryo transfer success.

Analysis of the risk factors and treatment for repeated implantation failure: OPtimization of Thyroid function, IMmunity, and Uterine Milieu (OPTIMUM) treatment strategy

PROBLEM

What are the pregnancy outcomes after the OPtimization of Thyroid function, Immunity, and Uterine Milieu (OPTIMUM) treatment strategy in patients with repeated implantation failure (RIF)?

METHOD OF STUDY

Infertile women with a history of RIF after more than three embryo transfer (ET) cycles underwent implantation testing, including a hysteroscopy, endometrial biopsy for CD138 immunostaining and bacterial culture, and serum 25-hydroxyvitamin D₃ , interferon-γ-producing helper T (Th1) cell, IL-4-producing helper T (Th2) cell, thyroid-stimulating hormone, thyroid peroxidase antibody, and thrombophilia screening between April 2017 and August 2018. We treated chronic endometritis with antibiotics, aberrant high Th1/Th2 cell ratios with vitamin D and/or tacrolimus intake, overt/subclinical hypothyroidism with levothyroxine, and thrombophilia with low-dose aspirin. Of the 116 RIF women, 88 women with 133 ET cycles were recruited from a questionnaire-based survey regarding pregnancy outcomes. Fifty-nine consecutive RIF patients without the OPTIMUM treatment strategy were also recruited as a control.

RESULTS

The 116 women with RIF after the OPTIMUM treatment strategy were 38.3 ± 3.8 years old and had an implantation failure history over 5 (3-19) ET cycles. Implantation testing identified impaired intrauterine circumstances in 75 women (64.7%), an aberrant elevated Th1/Th2 cell ratio in 56 women (48.3%), and thyroid abnormalities in 33 women (28.4%). Cumulative ongoing pregnancy rates including spontaneous pregnancy in the patients aged < 40 and ≥ 40 years were 72.7% and 45.5% within two ET cycles, respectively. The pregnancy outcomes in the OPTIMUM group were significantly higher than those in the control.

CONCLUSIONS

The OPTIMUM treatment strategy improved pregnancy outcomes in patients with RIF.