Endometritis: new time, new concepts

AI-algorithm training and validation for identification of endometrial CD138+ cells in infertility-associated conditions; polycystic ovary syndrome (PCOS) and recurrent implantation failure (RIF)

Background

Endometrial CD138+ plasma cells serve as a diagnostic biomarker for endometrial inflammation, and their elevated occurrence correlates positively with adverse pregnancy outcomes. Infertility-related conditions like polycystic ovary syndrome (PCOS) and recurrent implantation failure (RIF) are closely associated with systemic and local chronic inflammatory status, wherein endometrial CD138+ plasma cell accumulation could also contribute to endometrial pathology. Current methods for quantifying CD138+ cells typically involve laborious and time-consuming microscopic assessments of only a few random areas from a slide. These methods have limitations in accurately representing the entire slide and are susceptible to significant biases arising from intra- and interobserver variations. Implementing artificial intelligence (AI) for CD138+ cell identification could enhance the accuracy, reproducibility, and reliability of analysis.

Methods

Here, an AI algorithm was developed to identify CD138+ plasma cells within endometrial tissue. The AI model comprised two layers of convolutional neural networks (CNNs). CNN1 was trained to segment epithelium and stroma across 28,363 mm2 (2.56 mm2 of epithelium and 24.87 mm2 of stroma), while CNN2 was trained to distinguish stromal cells based on CD138 staining, encompassing 7345 cells in the object layers (6942 CD138- cells and 403 CD138+ cells). The training and performance of the AI model were validated by three experienced pathologists. We collected 193 endometrial tissues from healthy controls (n = 73), women with PCOS (n = 91), and RIF patients (n = 29) and compared the CD138+ cell percentages based on cycle phases, ovulation status, and endometrial receptivity utilizing the AI model.

Results

The AI algorithm consistently and reliably distinguished CD138- and CD138+ cells, with total error rates of 6.32% and 3.23%, respectively. During the training validation, there was a complete agreement between the decisions made by the pathologists and the AI algorithm, while the performance validation demonstrated excellent accuracy between the AI and human evaluation methods (intraclass correlation; 0.76, 95% confidence intervals; 0.36-0.93, p = 0.002) and a positive correlation (Spearman's rank correlation coefficient: 0.79, p < 0.01). In the AI analysis, the AI model revealed higher CD138+ cell percentages in the proliferative phase (PE) endometrium compared to the secretory phase or anovulatory PCOS endometrium, irrespective of PCOS diagnosis. Interestingly, CD138+ percentages differed according to PCOS phenotype in the PE (p = 0.03). On the other hand, the receptivity status had no impact on the cell percentages in RIF samples.

Conclusion

Our findings emphasize the potential and accuracy of the AI algorithm in detecting endometrial CD138+ plasma cells, offering distinct advantages over manual inspection, such as rapid analysis of whole slide images, reduction of intra- and interobserver variations, sparing the valuable time of trained specialists, and consistent productivity. This supports the application of AI technology to help clinical decision-making, for example, in understanding endometrial cycle phase-related dynamics, as well as different reproductive disorders.

Bridging the Diagnostic Gap between Histopathologic and Hysteroscopic Chronic Endometritis with Deep Learning Models

Chronic endometritis (CE) is an inflammatory pathologic condition of the uterine mucosa characterized by unusual infiltration of CD138(+) endometrial stromal plasmacytes (ESPCs). CE is often identified in infertile women with unexplained etiology, tubal factors, endometriosis, repeated implantation failure, and recurrent pregnancy loss. Diagnosis of CE has traditionally relied on endometrial biopsy and histopathologic/immunohistochemistrical detection of ESPCs. Endometrial biopsy, however, is a somewhat painful procedure for the subjects and does not allow us to grasp the whole picture of this mucosal tissue. Meanwhile, fluid hysteroscopy has been recently adopted as a less-invasive diagnostic modality for CE. We launched the ARCHIPELAGO (ARChival Hysteroscopic Image-based Prediction for histopathologic chronic Endometritis in infertile women using deep LeArninG mOdel) study to construct the hysteroscopic CE finding-based prediction tools for histopathologic CE. The development of these deep learning-based novel models and computer-aided detection/diagnosis systems potentially benefits infertile women suffering from this elusive disease.

Lack of Annexin A1 Exacerbates Inflammatory Response in Acute Endometritis Model

Annexin A1 (AnxA1) is a glucocorticoid-inducible protein and an important endogenous modulator of inflammation. However, its effect in the endometrial microenvironment is poorly explained. This study aimed to evaluate the role of endogenous AnxA1 in an endometritis mouse model induced by lipopolysaccharide (LPS). Female C57BL/6 wild-type (WT) and AnxA1-/- mice were divided into two groups: SHAM and LPS. To induce endometritis, mice received a vaginal infusion of 50 μL of LPS (1 mg/mL) dissolved in phosphate-buffered saline. After 24 h, the mice were euthanized, and blood and uteri samples were collected. The endometrium inflammatory scores were significantly increased in the LPS-treated group. AnxA1-/- mice from the LPS group demonstrated a significant increase in the number of degranulated mast cell levels compared to AnxA1-/- SHAM mice. The Western blotting analysis revealed that a lack of AnxA1 promoted the upregulation of NLRP3 and pro-IL-1β in the acute endometritis animal model compared to WT LPS animals. LPS-induced endometritis increased the number of blood peripheral leukocytes in both WT and AnxA1-/- mice compared with SHAM group mice (p < 0.001). AnxA1-/- mice also showed increased plasma levels of IL-1β (p < 0.01), IL-6, IL-10, IL-17, and TNF-α (p < 0.05) following LPS-induced endometritis. In conclusion, a lack of endogenous AnxA1 exacerbated the inflammatory response in an endometritis model via NLRP3 dysregulation, increased uterine mast cell activation, and plasma pro-inflammatory cytokine release.

Chronic endometritis and the endometrial microbiota: implications for reproductive success in patients with recurrent implantation failure

BACKGROUND

Chronic endometritis (CE) is associated with poor reproductive outcomes, yet the role of endometrial microbiota in patients with recurrent implantation failure (RIF) and CE remains unclear. This study aims to characterize endometrial microbiota in RIF patients with CE and assess its implications for reproductive outcomes.

METHODS

In this prospective study, we enrolled RIF patients both with and without CE. Endometrial and cervical samples were collected for 16 S rRNA gene sequencing. Microbiota composition was compared between groups using diversity indices, phylum, and genus-level analysis. Canonical correlation analysis (CCA) and Spearman's correlation coefficients were used to assess relationships between CE, reproductive outcomes, and microbiota. Predictive functional profiling was performed to evaluate metabolic pathways associated with CE.

RESULTS

Endometrial microbiota in CE patients exhibited greater diversity and evenness compared to non-CE patients. Principal coordinates analysis (PCoA) revealed distinct clustering between CE and non-CE groups. Linear discriminant analysis (LDA) identified Proteobacteria, Aminicenantales, and Chloroflexaceae as characteristic of CE, while Lactobacillus, Acinetobacter, Herbaspirillum, Ralstonia, Shewanela, and Micrococcaceae were associated with non-CE. CCA demonstrated associations between CE, adverse reproductive outcomes, and specific bacterial taxa. Microbial metabolic pathways significantly differed between CE and non-CE groups, with enrichment in pathways related to cofactors, vitamins, secondary metabolites, and the immune system in CE patients.

CONCLUSION

RIF patients with CE exhibit distinct endometrial microbiota compositions associated with adverse reproductive outcomes. The increased microbial diversity and altered metabolic pathways in CE suggest a potential correlation with reproductive outcomes, although further studies are necessary to elucidate the causal relationship between microbiota alterations and fertility. Modulating the endometrial microbiome may represent a novel therapeutic strategy to improve IVF outcomes in patients with CE.

Microbiome dysbiosis in patients with chronic endometritis and Clostridium tyrobutyricum ameliorates chronic endometritis in mice

Chronic endometritis is associated with the imbalance of female reproductive tract microbiota and pathogenic microbial infection. This study aimed to identify the specific changes in the endometrial microbiome in patients with endometritis and to explore how Clostridium tyrobutyricum (C.t) influences the progression of endometritis in mice for further elucidating endometritis pathogenesis. For this purpose, endometrial tissues from 100 participants were collected and divided into positive, weakly positive, and negative groups based on CD138 levels, while endometrial microbiome differences were detected and analyzed using 16S rRNA gene sequencing. Staphylococcus aureus (S. aureus)-induced endometritis mouse model was established, followed by treatment with C.t, and inflammatory response, epithelial barrier, and TLR4/NF-κB pathway were evaluated. Results showed that α- and β-diversity was significantly lower in the positive group compared with the weakly positive or negative groups, where the negative group had more unique operational taxonomic units. The abundance of Proteobacteria was found to be increased, while that of Actinobacteria, Firmicutes, and Bacteroidetes was found to be reduced in the positive group, while the area under the curve value was found to be 0.664. Furthermore, C.t treatment resulted in the alleviation of S. aureus-induced inflammatory response, epithelial barrier damage, and activation of the TLR4/NF-κB pathway in mice. Clinical samples analysis revealed that the diversity and abundance of microbiota were altered in patients with endometritis having positive CD138 levels, while mechanistic investigations revealed C.t alleviated S. aureus-induced endometritis by inactivating TLR4/NF-κB pathway. The findings of this study are envisaged to provide a diagnostic and therapeutic potential of microbiota in endometritis.

Exploring the therapeutic effect of Pen Yan Kang Fu Decoction on SPID rats based on LIF/JAK2/STAT3 signaling pathway

Tubal inflammation, endometritis, and uterine adhesions due to post-pelvic inflammatory disease (SPID) are important causes of infertility. Chronic endometritis (CE) belongs to SPID, which seriously affects women's reproductive health, quality of life, and family harmony, and is a hot and difficult problem in clinical research. The efficacy of Pen Yan Kang Fu Decoction (PYKFD) has been verified in long-term clinical practice for chronic endometritis infertility caused by the SPID. Numerous studies have confirmed that the LIF/JAK2/STAT3 signaling pathway is important in embryo implantation and development, and endometritis infertility is close to LIF/JAK2/STAT3. In vivo results showed that PYKFD increased endometrial receptivity, repaired uterine tissue damage, and regulates the expression of endometrial receptivity-related factors ER (estrogen receptor), PR (progesterone receptor), CD31, and integrin αvβ3, and induced the transduction of LIF/JAK2/STAT3 signaling pathway. PYKFD can also regulate the expression of IL-6. The results of in vitro experiments showed that PYKFD regulates the behavior of rat endometrial epithelial cells (REECs) involving LIF. In conclusion, PYKFD can improve endometrial receptivity and promote endometrial repair by LIF/JAK2/STAT3 signaling pathway.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-024-03981-0.

Evaluation of Recurrent Pregnancy Loss

Recurrent pregnancy loss (RPL) affects approximately 5% of couples. Although RPL definitions vary across professional societies, an evaluation after a second clinically recognized first-trimester pregnancy loss is recommended. Good quality evidence links parental chromosomal rearrangements, uterine anomalies, and antiphospholipid syndrome (APS) to RPL. In contrast, the relationship between RPL and other endocrine, hematologic, and immunologic disorders or environmental exposures is less clear. Anticoagulant therapy and low-dose aspirin are recommended for patients with RPL who have also been diagnosed with APS. Vaginal progesterone supplementation may be considered in patients experiencing vaginal bleeding during the first trimester. Surgical correction may be considered for patients with RPL in whom a uterine anomaly is identified. Evaluation and management of additional comorbidities should be guided by the patient's history rather than solely based on the diagnosis of RPL, with the goal of improving overall health to reduce complications in the event of pregnancy. Most people with RPL, including those without identifiable risk factors, are expected to achieve a live birth within 5 years from the initial evaluation. Nevertheless, clinicians should be sensitive to the psychological needs of individuals with this condition and provide compassionate and supportive care across all stages.

Clinical utility of office hysteroscopy following failed in vitro fertilization-embryo transfer: A retrospective cohort study

OBJECTIVE

Despite its widespread use, in vitro fertilization (IVF) outcomes are challenged by implantation failure, largely due to factors such as embryo quality and endometrial receptivity. In this study, we investigated the clinical effect of office hysteroscopy (OH) on the subsequent frozen-thawed embryo transfer (FET) in infertile women who experienced a failed IVF-embryo transfer (IVF-ET) cycle.

METHODS

We included 577 infertile women who underwent OH because of a history of failed ET between October 2019 and September 2021. During OH, visible endometrial polyps (EPs) were diagnosed and removed by curette or biopsy forceps; chronic endometritis (CE) was diagnosed by histopathology and immunohistochemistry and treated with oral doxycycline (0.2 g/d) for 14 days. According to the hysteroscopic findings and endometrial pathology with immunohistochemistry, patients were divided into three groups: group A (n = 161) had CE with or without EPs, group B (n = 156) had EPs only, and group C (n = 260) had no CE or EPs.

RESULTS

In the following FET cycle, the implantation rates were 47%, 51%, and 45% (P = 0.411); the clinical pregnancy rates were 56%, 62%, and 55% (P = 0.436); the live birth rates were 45%, 51%, and 42% (P = 0.205); and the miscarriage rates were 18%, 16%, and 22% (P = 0.497) in groups A, B, and C, respectively. There were no significant differences among groups (P > 0.05).

CONCLUSION

OH is helpful for diagnosis and treatment of abnormal intrauterine environment in women with a failed IVF cycle and further improves their pregnancy outcome in the following FET.

Peripartum Pharmacotherapy: A Pharmacist's Guide

Complications throughout the peripartum period may be caused by preexisting conditions or pregnancy-induced conditions and may alter pharmacotherapy management. Pharmacotherapy management during late pregnancy and delivery requires careful consideration due to changing hormones, hemodynamic status, and pharmacokinetics, and concerns for potential maternal and/or fetal morbidity. Increased maternal and fetal monitoring are often required and may lead to therapy changes. Pharmacists, as key members of the interprofessional team, can contribute essential perspective to the management of postpartum pharmacotherapy through assessment and recommendation of appropriate and judicious use of medications.

Deciphering the role of female reproductive tract microbiome in reproductive health: a review

Relevant studies increasingly indicate that female reproductive health is confronted with substantial challenges. Emerging research has revealed that the microbiome interacts with the anatomy, histology, and immunity of the female reproductive tract, which are the cornerstone of maintaining female reproductive health and preventing adverse pregnancy outcomes. Currently, the precise mechanisms underlying their interaction and impact on physiological functions of the reproductive tract remain elusive, constituting a prominent area of investigation within the field of female reproductive tract microecology. From this new perspective, we explore the mechanisms of interactions between the microbiome and the anatomy, histology, and immunity of the female reproductive tract, factors that affect the composition of the microbiome in the female reproductive tract, as well as personalized medicine approaches in managing female reproductive tract health based on the microbiome. This study highlights the pivotal role of the female reproductive tract microbiome in maintaining reproductive health and influencing the occurrence of reproductive tract diseases. These findings support the exploration of innovative approaches for the prevention, monitoring and treatment of female reproductive tract diseases based on the microbiome.

Unveiling the protective effects of BMSCs/anti-miR-124-3p exosomes on LPS-induced endometrial injury

Researchers have reported that miR-124-3p is highly expressed in patients with chronic endometritis. However, the underlying mechanism of miR-124-3p in the development of endometritis remains unclear. This study constructed an in vitro endometrial cell injury model by treating HEECs with 2 μg/mL LPS for 48 h. Then, 1 mg/kg LPS was injected into both sides of the mouse uterus to construct an in vivo endometrial injury model. The expression of miR-124-3p in human endometrial epithelial cells (HEECs) was assessed using RT‒qPCR. Exosomes were separated from bone marrow-derived mesenchymal stem cells (BMSCs) and cocultured with HEECs. A dual-luciferase reporter assay was performed to confirm the relationship between miR-124-3p and DUSP6. The results indicated that LPS inhibited HEEC viability in a time- and dose-dependent manner. The miR-124-3p inhibitor reversed the LPS-induced apoptosis and inhibition of HEEC viability. In addition, miR-124-3p could be transferred from BMSCs to HEECs by exosomes. Exosomes were derived from BMSCs treated with an NC inhibitor (BMSCs/NC Exo) or miR-124-3p inhibitor (BMSCs/anti-miR-124-3p Exo). In addition, BMSCs/anti-miR-124-3p Exo abolished the LPS-induced inhibition of HEEC viability and proliferation by inducing HEEC apoptosis. Moreover, BMSCs/anti-miR-124-3p Exo alleviated the LPS-induced inflammation of HEECs by upregulating DUSP6 and downregulating p-p65 and p-ERK. Furthermore, in an LPS-induced in vivo endometrial injury model, BMSCs/anti-miR-124-3p Exo increased the expression level of DUSP6 and decreased the expression levels of p-p65 and p-ERK. BMSCs/anti-miR-124-3p Exo protected against LPS-induced endometrial damage in vitro and in vivo by upregulating DUSP6 and downregulating p-p65 and p-ERK1/2. This study showed that BMSCs/anti-miR-124-3p Exo might be a potential alternative for the treatment of endometritis.

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.

Impact of a positive Chlamydia trachomatis serology on cumulative IVF live birth rate

RESEARCH QUESTION

Does positive Chlamydia trachomatis serology have an impact on the cumulative live birth rate from IVF?

DESIGN

A retrospective matched cohort study compared women with positive Chlamydia trachomatis serology (group A) who underwent IVF treatment between January 2016 and December 2021 with a control group of women with negative Chlamydia trachomatis serology (group B). The main outcome measures were the cumulative live birth rate per IVF cycle and the live birth rate per embryo transfer. Secondary outcomes were the cumulative rates of clinical pregnancy, ectopic pregnancy and pregnancy loss calculated per IVF cycle and per embryo transfer.

RESULTS

A total of 151 women in group A were matched 1:2 to 302 women in group B, representing 220 and 440 IVF cycles, respectively. Women with a history of Chlamydia trachomatis infection had a significantly higher rate of tubal obstruction (P < 0.001), excluded or operated hydrosalpinx (P = 0.002) and/or history of chronic endometritis (P < 0.001). There were no statistically significant differences between the two groups in the mean number of mature oocytes retrieved, fertilization rate or implantation rate. The IVF cumulative live birth rate per cycle was similar in the two groups (36.7% in group A versus 34.9% in group B, P = 0.692). The cumulative rates of clinical pregnancy, pregnancy loss, biochemical pregnancy and ectopic pregnancy were comparable between the two groups.

CONCLUSION

Positive Chlamydia trachomatis serology has no impact on IVF pregnancy outcomes.

Emerging bacterial factors for understanding pathogenesis of endometriosis

The pathogenesis of endometriosis is a complex process, and recent research has introduced novel hypotheses in this field. This review summarizes recent studies on the pathogenesis of endometriosis. We focused on several classical hypotheses, as well as their interactions with the microenvironment of hormonal dependence and immunosuppression. Furthermore, we highlighted the emergence of bacterial factors associated with endometriosis. Recent advances in next-generation sequencing (NGS) have revealed the presence and detailed distribution of these bacteria as well as the involvement of specific bacteria in pathogenesis. These factors alter the microenvironment in the early stages of endometriosis development, leading to lesion formation. Understanding the mechanisms underlying the early development of endometriosis from a new perspective would be helpful for the development of novel therapeutic agents for endometriosis.

Progress on the Endometrium

The endometrium is a dynamic tissue that facilitates mammalian internal reproduction and thus, the ability to deliver live born progeny that are more easily protected from predators. This tissue is unique in its ability to undergo cyclic regeneration and destruction in the absence of pregnancy. Ovarian steroids guide endometrial proliferation and maturation promoting its receptivity and selectivity with regards to blastocyst implantation. It is decidualization, terminal stromal maturation, that prevents the trophoblast from breeching containment of the uterus and allows for endometrial sloughing should pregnancy not occur. Endometrial pathology is highly variable and therefore a wide array of diagnostic measures are required for its interrogation. There remains no single test that can distinguish between all potential issues and it is critical that appropriate and evidence-based endometrial assessment is carried out. Emerging data on developmental markers, inflammatory mediators, and bacterial profiling offer hope that conditions including endometriosis, cancer, infertility, and implantation failure will be more easily and less invasively diagnosed. This will allow for a more timely and targeted approach to intervention. Accordingly, assessing novel measures requires an evidence-based approach prior to their mass utilization.

Cyclical endometrial repair and regeneration: Molecular mechanisms, diseases, and therapeutic interventions

The endometrium is a unique human tissue with an extraordinary ability to undergo a hormone-regulated cycle encompassing shedding, bleeding, scarless repair, and regeneration throughout the female reproductive cycle. The cyclical repair and regeneration of the endometrium manifest as changes in endometrial epithelialization, glandular regeneration, and vascularization. The mechanisms encompass inflammation, coagulation, and fibrinolytic system balance. However, specific conditions such as endometriosis or TCRA treatment can disrupt the process of cyclical endometrial repair and regeneration. There is uncertainty about traditional clinical treatments' efficacy and side effects, and finding new therapeutic interventions is essential. Researchers have made substantial progress in the perspective of regenerative medicine toward maintaining cyclical endometrial repair and regeneration in recent years. Such progress encompasses the integration of biomaterials, tissue-engineered scaffolds, stem cell therapies, and 3D printing. This review analyzes the mechanisms, diseases, and interventions associated with cyclical endometrial repair and regeneration. The review discusses the advantages and disadvantages of the regenerative interventions currently employed in clinical practice. Additionally, it highlights the significant advantages of regenerative medicine in this domain. Finally, we review stem cells and biologics among the available interventions in regenerative medicine, providing insights into future therapeutic strategies.

Nuciferine protects against lipopolysaccharide-induced endometritis via inhibiting ferroptosis and modulating AMPKα/mTOR/HIF-1α signaling axis

Nuciferine (NF) is an alkaloid isolated from Nelumbo nucifera and has been reported to exhibit a wide range of pharmacological effects. However, whether NF treatment exhibits a protective effect in endometritis remains unclear. Here, the protective effects of NF on lipopolysaccharide (LPS)-induced endometritis in mice were investigated in our research. The results showed that NF significantly reversed the uterine histopathological changes, inflammatory factor levels and myeloperoxidase (MPO) activity caused by LPS. Furthermore, we found that NF administration improved the reproductive capacity of mice with endometritis. Mechanistically, the expression of MyD88/nuclear factor-kappa B (NF-κB) and MAPK-related proteins in uterine tissue were decreased by NF treatment. Moreover, we observed the occurrence of ferroptosis in the LPS-induced endometritis mouse model, which was noticeably inhibited by NF treatment. In addition, we showed that NF exhibited anti-endometritis activity by modulating AMPKα/mTOR/HIF1α signaling axis. Finally, the molecular mechanism of the NF anti-inflammatory effect was clarified in mouse endometrial epithelial cells (mEECs). NF inhibited the releases of pro-inflammatory factors in LPS-induced mEECs via inhibiting NF-κB signaling pathway. All these findings suggest that NF may ameliorate LPS-induced endometritis caused by LPS, the mechanism of action is related to the ferroptosis, MyD88/NF-κB, MAPK and AMPKα/mTOR/HIF1α signaling pathway.

Bile acids ameliorates lipopolysaccharide-induced endometritis in mice by inhibiting NLRP3 inflammasome activation

AIMS

Endometritis is a common inflammatory disorder affecting the reproductive health in both humans and livestock. The NLR family pyrin domain containing 3 (NLRP3) inflammasome has recently been identified as a possible therapeutic target for several inflammatory disorders. Bile acids (BAs) have been shown to possess anti-inflammatory properties by inhibiting the activation of the NLRP3 inflammasome. However, whether BAs ameliorate endometritis by targeting NLRP3 inflammasome remain poorly understood.

MAIN METHODS

Female NLRP3+/+ and NLRP3-/- mice were subjected to uterine perfusion with lipopolysaccharide (LPS) to establish the endometritis model. For BAs pre-treatment, wild-type mice were administered oral gavage of BAs for seven days followed by uterine perfusion with LPS. All mice were euthanized and the uterine tissues were collected for analysis.

KEY FINDINGS

The abundances of NLRP3 and interleukin-1 beta (IL-1β) were significantly upregulated in the uterine tissues of endometritis mice. NLRP3 deficiency led to a reduction in the inflammatory response, neutrophil infiltration, and myeloperoxidase (MPO) activity in the uterus, as well as an inhibition of IL-1β secretion. Moreover, BAs pre-treatment successfully decreased LPS-induced upregulation of NLRP3, ASC, and Caspase1, lessened histopathological alteration in the uterus, and notably reduced MPO activity and secretion of IL-1β.

SIGNIFICANCE

NLRP3 inflammasome is a promising target for endometritis treatment and BAs exhibit anti-inflammatory properties by repressing NLRP3 inflammasome activation, making them a possible novel therapeutic strategy for endometritis.

Ginsenosides in endometrium-related diseases: Emerging roles and mechanisms

Ginsenosides, agents extracted from an important herb (ginseng), are expected to provide new therapies for endometrium-related diseases. Based on the molecular types of ginsenosides, we reviewed the main pharmacological effects of ginsenosides against endometrium-related diseases (e.g., endometrial cancers, endometriosis, and endometritis). The mechanism of action of ginsenosides involves inducing apoptosis of endometrium-related cells, promoting autophagy of endometrium-related cells, regulating epithelial-mesenchymal transition (EMT) in endometrium-related cells, and activating the immune system to kill cells associated with endometrial diseases. We hope to provide a theoretical foundation for the treatment of endometrium-related diseases by ginsenosides.

Contrast-Enhanced Ultrasonography as a Diagnostic Strategy for Severe Endometrial Injury

ABSTRACT

Endometrial injury is associated with poorer pregnancy outcomes. The purpose of this study was to evaluate the diagnostic efficacy of contrast-enhanced ultrasonography (CEUS) in the detection of endometrial injury. This study included women who underwent CEUS of the uterus at the author's hospital between April 2020 and January 2021. The diagnostic performances of the CEUS-derived parameters in the detection of severe endometrial injury were evaluated by receiver operating characteristic curve analyses. The study included 67 participants (healthy control, n = 14; mild endometrial injury, n = 24; severe endometrial injury, n = 29). Enhancement intensity (EI) and area under the time-intensity curve (AUC TIC ) were significantly lower in the severe endometrial injury patients than healthy and mild endometrial injury subjects for both endometrial and subendometrial regions ( P < 0.05). Correlations analysis showed that EI and AUC TIC were positively correlated with endometrial thickness ( r = 0.460, P = 0.01, and r = 0.555, P < 0.01, respectively) and subendometrial thickness ( r = 0.501, P < 0.01, and r = 0.438, P = 0.01, respectively). The area under the receiver operating characteristic curve, sensitivity, and specificity were 0.720 ( P = 0.002), 79.31%, and 66.67% for endometrial EI; 0.818 ( P < 0.001), 75.86%, and 79.17% for subendometrial EI; 0.917 ( P < 0.001), 72.41%, and 95.83% for endometrial AUC TIC ; and 0.810 ( P < 0.001), 89.66%, and 70.83% for subendometrial AUC TIC , respectively. Contrast-enhanced ultrasonography may have clinical utility in the prediction of endometrial injury in women of childbearing age.

The Endometrial Microbiota: Challenges and Prospects

Contrary to popular belief, we have known for many years that the endometrium is not a sterile environment and is considered to be a low-biomass milieu compared to the vagina. Numerous trials and studies have attempted to establish a valid sampling method and assess its physiological composition, but no consensus has been reached. Many factors, such as ethnicity, age and inflammation, can influence the microbiome. Moreover, it possesses a higher alpha-diversity and, therefore, contains more diverse bacteria than the vagina. For instance, Lactobacillus has been shown to be a predominant genus in the vaginal microbiome of healthy women. Consequently, even if a majority of scientists postulate that a predominance of Lactobacillus inside the uterus improves reproductive outcomes, vaginal contamination by these bacteria during sampling cannot be ruled out. Certain pathologies, such as chronic endometritis, have been identified as inflammation perpetrators that hinder the embryo implantation process. This pro-inflammatory climate created by dysbiosis of the endometrial microbiota could induce secondary inflammatory mediators via Toll-like receptors, creating an environment conducive to the development of endometriosis and even promoting carcinogenesis. However, studies to this day have focused on small populations. In addition, there is no clearly defined healthy uterine composition yet. At most, only a few taxa have been identified as pathogenic. As sampling and analysis methods become increasingly precise, we can expect the endometrial microbiota to be incorporated into future diagnostic tools and treatments for women's health.

Protective effect of the total flavonoids from Clinopodium chinense against LPS-induced mice endometritis by inhibiting NLRP3 inflammasome-mediated pyroptosis

ETHNOPHARMACOLOGICAL RELEVANCE

Clinopodium chinense (Benth.) O. Kuntze (C. chinense) is a Chinese herbal medicine used in treating gynecological hemorrhagic diseases for hundreds of years. Flavonoids are one kind of the major components in C. chinense. The flavonoids of C. chinense (TFC) have a vital role in treating endometritis but the underlying therapeutic mechanisms of TFC against endometritis have been rarely reported.

AIM OF THE STUDY

To elucidate the therapeutic effect and possible mechanisms of TFC against lipopolysaccharide (LPS)-induced endometritis in vivo and LPS-induced primary mouse endometrial epithelial cells (MEECs) injury in vitro.

MATERIALS AND METHODS

The holistic phytochemicals of the TFC and TFC-contained serum were screened and identified using UPLC-Q-TOF-MS. The model of endometritis was established by intrauterine injection of LPS (5 mg/mL) into female BALB/c mice, and the model mice were treated with TFC for 7 days. The value of MPO was measured by Myeloperoxidase assay kit, the pathological changes in the endometrium were evaluated using H&E staining and transmission electron microscope (TEM), the secretions of IL-18, IL-1β and TNF-α were determined by ELISA kits, the mRNA expressions of IL-18, IL-1β and TNF-α were determined by RT-PCR assay, and the protein levels of TLR4, IKBα, p-IKBα, p65, p-p65, caspase-1, ASC, NLRP3 and GSDMD were measured by Western blot. Subsequently, MEECs were isolated from the uterus of pregnant female mice, injured by LPS for 24 h and incubated with the TFC-contained serum. Finally, cell viability, LDH release, hoechst 33342/PI staining, immunofluorescence staining, scanning electron microscope observation, ELISA assay, RT-PCR detection and Western blot analysis were carried out to further validate the therapeutic effect and the underlying mechanisms of TFC.

RESULTS

A total of 6 compounds in the plasma of mice after being intragastric administrated of TFC were identified. The results in vivo showed that TFC significantly reduced MPO value and alleviated pathological injury of the endometrium. Furthermore, TFC significantly decreased the serum IL-18, IL-1β and TNF-α levels, and the mRNA levels of IL-18, IL-1β and TNF-α. TFC also inhibited the expressions of TLR4, p-IKBα, p-p65, caspase-1, ASC, NLRP3 and GSDMD. Besides, compared with the model group in MEECs cells, TFC-contained serum prevented pyroptosis, decreased the levels of IL-18 and IL-1β, and inhibited the mRNA expressions of IL-18, IL-1β and GSDMD. TFC-contained serum also reversed the activation of NLRP3 inflammasome caused by nigericin, and restrainted the translocation of NF-κB into nuclear.

CONCLUSIONS

TFC protects mice endometritis from the injury of LPS via suppressing the activation of NLRP3 inflammasome and pyroptosis, the underlying mechanisms of which were related to restraining the TLR4/NF-κB/NLRP3 pathway activation.

Transcription Factor Nrf2 Modulates Lipopolysaccharide-Induced Injury in Bovine Endometrial Epithelial Cells

Endometritis in high-yield dairy cows adversely affects lactation length, milk quality, and the economics of dairy products. Endoplasmic reticulum stress (ERS) in bovine endometrial epithelial cells (BEECs) occurs as a consequence of diverse post-natal stressors, and plays a key role in a variety of inflammatory diseases. Nuclear-factor-erythroid-2-related factor 2 (Nrf2) is an important protective regulatory factor in numerous inflammatory responses. However, the mechanism by which Nrf2 modulates inflammation by participating in ERS remains unclear. The objective of the present study was to explore the role of Nrf2 in lipopolysaccharide (LPS)-induced injury to BEECs and to decipher the underlying molecular mechanisms of this injury. The expression of Nrf2- and ERS-related genes increased significantly in bovine uteri with endometritis. Isolated BEECs were treated with LPS to stimulate the inflammatory response. The expression of Nrf2 was significantly higher in cells exposed to LPS, which also induced ERS in BEECs. Activation of Nrf2 led to enhanced expression of the genes for the inflammation markers TNF-α, p65, IL-6, and IL-8 in BEECs. Moreover, stimulation of Nrf2 was accompanied by activation of ERS. In contrast, Nrf2 knockdown reduced the expression of TNF-α, p65, IL-6, and IL-8. Additionally, Nrf2 knockdown decreased expression of ERS-related genes for the GRP78, PERK, eIF2α, ATF4, and CHOP proteins. Collectively, our findings demonstrate that Nrf2 and ERS are activated during inflammation in BEECs. Furthermore, Nrf2 promotes the inflammatory response by activating the PERK pathway in ERS and inducing apoptosis in BEECs.

The effect of chronic endometritis and treatment on patients with unexplained infertility

PURPOSE

This paper was mainly conducted to investigate the effect of chronic endometritis (CE) on the clinical outcome of patients with unexplained infertility.

MATERIALS AND METHODS

145 patients with unexplained infertility from the Reproductive Center of our hospital from January 2018 to December 2021 were selected as the unexplained infertility group. 42 patients with definite infertility causes were selected as the control group during the same period. Both groups of patients underwent hysteroscopy and immunohistochemical tests for CD38 and CD138. According to the results of hysteroscopy and immunohistochemistry, the incidence of CE between the two groups was analyzed. Patients with CE as CE group accepted oral antibiotic therapy for 14 days. Another 58 patients with unexplained infertility who did not undergo hysteroscopy and immunohistochemical tests for CD38 and CD138 were selected as the unexamined group. Both groups of patients were expected natural pregnancy. Follow-up lasted for 1 year, and the pregnant patients were followed up until delivery.The clinical pregnancy rate, spontaneous abortion rate and baby-carrying home rate of the two groups were compared.

RESULTS

There were 75 patients with CE in the unexplained infertility group, and the prevalence rate was 51.7% (75/145). Compared with the control group (28.6%), the incidence of CE was significantly higher (P < 0.05). After treated with antibiotic treatment, the patients' clinical pregnancy rate was 61.3% (46/75) and baby-carrying home rate was 60% (45/75) in the CE group, which were higher than those in the unexamined group(43.1% & 36.2%) (P < 0.05), while the spontaneous abortion rate was 2.2% (1/46),which was lower than that in the unexamined group (16.0%) (P < 0.05).

CONCLUSIONS

For patients with unexplained infertility, hysteroscopy combined with endometrial immunohistochemical detection of CD38 and CD138 should be performed in time to exclude CE. The clinical pregnancy outcome of CE patients can be significantly improved by antibiotic treatment.

The mechanism of action of safflower total flavonoids in the treatment of endometritis caused by incomplete abortion based on network pharmacology and 16S rDNA sequencing

ETHNOPHARMACOLOGICAL RELEVANCE

Safflower is a traditional Chinese medicine used for treating gynaecological diseases. However, its material basis and mechanism of action in the treatment of endometritis induced by incomplete abortion are still unclear.

AIM OF THE STUDY

This study aimed to reveal the material basis and mechanism of action of safflower in the treatment of endometritis induced by incomplete abortion through comprehensive methods, including network pharmacology and 16S rDNA sequencing.

MATERIALS AND METHODS

Network pharmacology and molecular docking methods were used to screen the main active components and potential mechanisms of action of safflower in the treatment of endometritis induced by incomplete abortion in rats. A rat model of endometrial inflammation by incomplete abortion was established. The rats were treated with safflower total flavonoids (STF) based on forecasting results, serum levels of inflammatory cytokines were analysed, and immunohistochemistry, Western blots, and 16S rDNA sequencing were performed to investigate the effects of the active ingredient and the treatment mechanism.

RESULTS

The network pharmacology prediction results showed 20 active components with 260 targets in safflower, 1007 targets related to endometritis caused by incomplete abortion, and 114 drug-disease intersecting targets, including TNF, IL6, TP53, AKT1, JUN, VEGFA, CASP3 and other core targets, PI3K/AKT, MAPK and other signalling pathways may be closely related to incomplete abortion leading to endometritis. The animal experiment results showed that STF could significantly repair uterine damage and reduce the amount of bleeding. Compared with the model group, STF significantly down-regulated the levels of pro-inflammatory factors (IL-6, IL-1β, NO, TNF-α) and the expression of JNK, ASK1, Bax, caspase3, and caspase11 proteins. At the same time, the levels of anti-inflammatory factors (TGF-β and PGE2) and the protein expression of ERα, PI3K, AKT, and Bcl2 were up-regulated. Significant differences in the intestinal flora were seen between the normal group and the model group, and the intestinal flora of the rats was closer to the normal group after the administration of STF.

CONCLUSIONS

The characteristics of STF used in the treatment of endometritis induced by incomplete abortion were multi-targeted and involved multiple pathways. The mechanism may be related to the activation of the ERα/PI3K/AKT signalling pathway by regulating the composition and ratio of the gut microbiota.

Selenomethionine protects against Escherichia coli-induced endometritis by inhibiting inflammation and necroptosis via regulating the PPAR-γ/NF-κB pathway

Endometritis, inflammation of the endometrium, is a major cause of subfertility in women. Selenomethionine (SeMet)is known to exert anti-inflammatory activity. We aimed to verify the protective roles of SeMet on Escherichia coli (E.coli)-induced endometritis. The extent of uterus damage was assessed by detecting histopathology and inflammatory mediators. The results revealed that SeMet significantly prevented E.coli-induced endometritis by attenuating uterine histopathology and inflammatory cytokine production. E.coli-induced MPO activity and MDA content were inhibited by SeMey. E.coli-induced ZO-1 and occludin were upregulated by SeMet. E.coli-induced necroptosis was also inhibited by SeMet. Additionally, E.coli-induced NF-κB activation was alleviated by SeMet. PPAR-γ expression was upregulated by SeMet. Notably, the protective effects of SeMet on endometritis were abolished by a PPAR-γ inhibitor. In conclusion, SeMet inhibits E.coli-induced endometritis by attenuating inflammation and necroptosis, which is mediated by the PPAR-γ/NF-κB signaling pathway.

Follicular helper T lymphocytes in the endometria of patients with reproductive failure: Association with pregnancy outcomes and inflammatory status of the endometria

PROBLEM

The phenotypes and functions of B and CD4⁺ T-helper cell subsets during chronic inflammation of the endometria remain largely unexplored. This study aimed to investigate the characteristics and functions of follicular helper T (Tfh) cells to understand the pathological mechanisms of chronic endometritis (CE).

METHOD OF STUDY

Eighty patients who underwent hysteroscopic and histopathological examinations for CE were divided into three groups-those with positive results for hysteroscopy and CD138 staining (DP), negative results for hysteroscopy but positive CD138 staining (SP), and negative results for hysteroscopy and CD138 staining (DN). The phenotypes of B cells and CD4⁺ T-cell subsets were analyzed using flow cytometry.

RESULTS

CD38⁺ and CD138⁺ cells were mainly expressed in the non-leukocyte population of the endometria, and the endometrial CD19⁺ CD138⁺ B cells were fewer than the CD3⁺ CD138⁺ T cells. The percentage of Tfh cells increased with chronic inflammation in the endometria. Additionally, the elevated percentage of Tfh cells correlated with the number of miscarriages.

CONCLUSIONS

CD4⁺ T cells, particularly Tfh cells, may be critical in chronic endometrial inflammation and affect its microenvironment, thereby regulating endometrial receptivity, compared to B cells.

The Endometrial Microbiota—16S rRNA Gene Sequence Signatures in Healthy, Pregnant and Endometritis Dairy Cows

Endometritis is one of the most important causes of infertility in dairy cows, resulting in high economic losses in the dairy industry. Though the presence of a commensal uterine microbiota is now well established, the complex role of these bacteria in genital health, fertility, and susceptibility to uterine diseases remains unclear. In this study, we explore the endometrial microbiota through 16S rRNA gene profiling from cytobrush samples taken ex vivo from healthy, pregnant, and endometritis cows. There were no significant differences between healthy and pregnant cows, whose uterine microbiota were dominated by Streptococcus, Pseudomonas, Fusobacterium, Lactococcus and Bacteroides. Compared to pregnant and clinically healthy cows, the uterine bacterial community of endometritis cows was significantly decreased in species diversity (p < 0.05), reflecting uneven community composition in different patterns with either dominance of Escherichia-Shigella, Histophilus, Bacteroides and Porphyromonas or Actinobacteria.

Adverse impact of CD138+ cells in proliferative-phase endometrium on pregnancy outcomes in fresh IVF/ICSI cycles

To evaluate the impact of Syndecan-1 (CD138) in proliferative-phase endometrium on pregnancy outcomes in fresh in vitro fertilization (IVF)/ intracytoplasmic sperm injection (ICSI) cycles. This retrospective cohort study contained 273 patients who underwent IVF/ICSI with fresh embryo transfer following an endometrial curettage from January 2020 to May 2022. Endometrial curettage was performed on all patients within 3 to 5 days following menstruation and endometrial tissue was acquired for detection of plasma cells by immunohistochemistry. Subsequent pregnancy outcomes of all cycles were traced and analyzed. A total of 149 patients became pregnant (i.e., pregnant group) in the fresh transfer IVF/ICSI cycles and 124 did not become pregnant (i.e., nonpregnant group). The number of CD138 + cells/ high-power field (HPF) of the nonpregnant group was significantly higher than the pregnant group (2.36 ± 4.24 vs 1.31 ± 3.41, P = .008). The cut off value of CD138 + cells/HPF was 2 by receiver operating characteristic curve analysis, with an area under the receiver operating characteristic curve of 0.572. Compared with the negative group (i.e., CD138 + cells/HPF < 2, n = 204), the positive group (i.e., CD138 + cells/HPF ≥ 2, n = 69) had a significantly lower clinical pregnancy rate (71.8% vs 40.6%, P < .001). The clinical pregnancy rate revealed a gradually decreasing trend with the increase in CD138 + cells. Proliferative-phase endometrial CD138 + cells may be an adverse indicator for pregnancy outcomes in fresh IVF/ICSI cycles, with a certain value in predicting non-pregnancy. Pregnancy outcome was poor when CD138 + cells/HPF ≥ 2 in the endometrium and may worsen with the increase in CD138 + cells.

Precision Medicine for Chronic Endometritis: Computer-Aided Diagnosis Using Deep Learning Model

Chronic endometritis (CE) is a localized mucosal infectious and inflammatory disorder marked by infiltration of CD138(+) endometrial stromal plasmacytes (ESPC). CE is drawing interest in the field of reproductive medicine because of its association with female infertility of unknown etiology, endometriosis, repeated implantation failure, recurrent pregnancy loss, and multiple maternal/newborn complications. The diagnosis of CE has long relied on somewhat painful endometrial biopsy and histopathologic examinations combined with immunohistochemistry for CD138 (IHC-CD138). With IHC-CD138 only, CE may be potentially over-diagnosed by misidentification of endometrial epithelial cells, which constitutively express CD138, as ESPCs. Fluid hysteroscopy is emerging as an alternative, less-invasive diagnostic tool that can visualize the whole uterine cavity in real-time and enables the detection of several unique mucosal findings associated with CE. The biases in the hysteroscopic diagnosis of CE; however, are the inter-observer and intra-observer disagreements on the interpretation of the endoscopic findings. Additionally, due to the variances in the study designs and adopted diagnostic criteria, there exists some dissociation in the histopathologic and hysteroscopic diagnosis of CE among researchers. To address these questions, novel dual immunohistochemistry for CD138 and another plasmacyte marker multiple myeloma oncogene 1 are currently being tested. Furthermore, computer-aided diagnosis using a deep learning model is being developed for more accurate detection of ESPCs. These approaches have the potential to contribute to the reduction in human errors and biases, the improvement of the diagnostic performance of CE, and the establishment of unified diagnostic criteria and standardized clinical guidelines for the disease.

Effect of different antibiotic therapies on the reproductive outcomes of fresh embryo transfer for chronic endometritis: A retrospective cohort study

OBJECTIVE

To investigate the reproductive outcomes by comparing two kinds of antibiotic schemes for chronic endometritis (CE) in infertile women's fresh embryo transfer (FET) cycles and identify subgroups of patients with CE who need long-term antibiotics treatment.

DESIGN

A retrospective cohort study.

SETTING

University-based reproductive medical center.

PATIENT(S)

A total of 492 women with CD138-positive plasmacytes per 10 high-power fields (CD138+/10HPF).

INTERVENTION(S)

Hysteroscopy was performed and endometrial biopsy samples were collected in the proliferative phase. Long-term or short-term antibiotics were administrated. After antibiotics treatment, patients underwent in vitro fertilization (IVF)/ intracytoplasmic sperm injection (ICSI) and received ET.

MAIN OUTCOME MEASURE(S)

Ongoing pregnancy rate, clinical pregnancy rate, clinical miscarriage rate.

RESULT (S)

There were no significant differences in pregnancy outcomes between patients with CD138+/10HPF 1-4 (low-grade CE) who received long-term antibiotic therapy and short-term antibiotics groups. Among women with CD138+/10HPF ≥5 (high-grade CE), live birth rate (48.4% vs. 14.7%, p = .001), clinical pregnancy rate (66.7% vs. 35.3%, p = .002) and ongoing pregnancy rate (59.1% vs. 20.6%, p < .001) in the long-term arm were significantly higher than that in the short-term arm. The clinical miscarriage rate (21.0% vs. 58.3%, p = .013) was statistically lower in the long-term antibiotics group, but no statistical differences were found between the two groups in preterm delivery rate.

CONCLUSION

Long-term antibiotics treatment was a sensible choice to improve pregnancy outcomes in women with CD138+/10HPF ≥5 (high-grade CE). The pregnancy outcomes of women with low-grade CE only defined by histological diagnosis were not greatly improved after antibiotic therapy. Therefore, we recommended the proper diagnosis criteria were CD138+/10HPF ≥5 pathologically.

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.

Chronic endometritis increases the recurrence of endometrial polyps in premenopausal women after hysteroscopic polypectomy

BACKGROUND

The reported recurrence rate of endometrial polyps (EPs) after hysteroscopic polypectomy varied widely, and the factors influencing the recurrence of EPs are still controversial. Furthermore, the known definite independent risk factors are almost unchangeable, such as the number of EPs and previous polypectomy history. The aim of this study was to evaluate the impact of chronic endometritis (CE) on the recurrence of EPs in premenopausal women who underwent hysteroscopic polypectomy.

METHODS

A retrospective study was conducted at a university-affiliated hospital. Premenopausal women who underwent hysteroscopic polypectomy were enrolled, and those with definite confounding factors for polyp recurrence were excluded, including endometriosis and previous polypectomy history. A total of 233 women were enrolled in this study, including 64 (27.5%) cases with CE and 169 (72.5%) cases without CE. CE was diagnosed via immunohistochemical detection of CD138 on the endometrial specimen. Comparison of the recurrence rate of EPs was performed in women with or without CE at each monitoring stage (i.e., at 3, 6, 9 and 12 months) after hysteroscopic polypectomy.

RESULTS

The recurrence rates of EPs at one year in patients with and without CE were 26.6% (95% confidence interval [CI] 15.8-37.4%) and 9.5% (95% CI 5.0-14.0%), respectively, with an overall recurrence rate of 14.2% (95% CI 9.7-18.7%). The hazard ratio (HR) for EPs recurrence in the EPs with CE cohort versus the EPs without CE cohort was 3.08 (95% CI 1.56-6.09) (P = 0.001). Similarly, the recurrence rate of EPs was significantly higher in women with CE than in those without CE at each monitoring stage (i.e., 3, 6 and 9 months). CE and multiple EPs were risk factors for EPs recurrence. The HR for EPs recurrence in the EPs with CE cohort compared with the EPs without CE cohort was 3.06, after adjustment for the number of EPs.

CONCLUSIONS

CE was a harmful factor for the recurrence of EPs in premenopausal women after hysteroscopic polypectomy. Thus, routine screening for CE during hysteroscopic polypectomy was needed. Frequent monitoring was needed for multiple EPs as the number of EPs also contributed to polyp recurrence.

Existence of chronic endometritis and its influence on pregnancy outcomes in infertile women with minimal/mild endometriosis

OBJECTIVE

This study aimed to evaluate the prevalence of chronic endometritis (CE) in women with minimal/mild endometriosis and to analyze whether CE affects their pregnancy outcomes.

METHODS

This retrospective study included 201 infertile women who were diagnosed with minimal/mild endometriosis after undergoing hysteroscopy combined with laparoscopy from January 2016 to December 2018. Immunohistochemistry was used to detect CD138 and CD38, which are specific markers of plasma cells in the endometrial stroma to diagnose CE. Subsequently, we investigated the prevalence of CE and the effects of CE on spontaneous cumulative pregnancy rate, live birth rate, and miscarriage rate within 24 months after surgery.

RESULTS

The prevalence of CE in infertile women with minimal/mild endometriosis was 24.38%. Patients diagnosed with CE showed a significantly lower cumulative pregnancy rate and live birth rate compared with women without CE (46.51% vs. 71.13% [P = 0.004]; 44.19% vs. 63.38% [P = 0.025]). However, the rate of miscarriage in women with CE was also lower than in women without CE (0 vs. 7.04%, P = 0.074).

CONCLUSION

Since CE had an adverse effect on cumulative pregnancy rate and live birth rate in infertile women with minimal/mild endometriosis, we suggested that diagnosis and treatment of CE may improve their pregnancy outcomes.

Commonalities and Disparities between Endometriosis and Chronic Endometritis: Therapeutic Potential of Novel Antibiotic Treatment Strategy against Ectopic Endometrium

Chronic endometritis (CE) is a local mucosal inflammatory disorder of the uterine lining, which is histopathologically recognized as the unusual infiltration of CD138(+) plasmacytes into the endometrial stromal compartment. Accumulating body of research documented that CE is associated with female infertility and several obstetric/neonatal complications. The major cause of CE is thought to be intrauterine infection represented by common bacteria (Escherichia coli, Enterococcus faecalis, Streptococcus, and Staphylococcus), Mycoplasma/Ureaplasma, and Mycobacterium. Additionally, local dysbiosis in the female reproductive tract may be involved in the onset and development of CE. Antibiotic treatments against these microorganisms are effective in the elimination of endometrial stromal plasmacytes in the affected patients. Meanwhile, endometriosis is a common female reproductive tract disease characterized by endometriotic tissues (ectopic endometrium) growing outside the uterus and potentially causes chronic pelvic symptoms (dysmenorrhea, dyspareunia, dyschezia, and dysuria), infertility, and ovarian cancers. Endometriosis involves endocrinological, genetic, and epigenetic factors in its etiology and pathogenesis. Recent studies focus on immunological, inflammatory, and infectious aspects of endometriosis and demonstrate several common characteristics between endometriosis and CE. This review aimed to better understand the immunological and microbial backgrounds underlying endometriosis and CE and look into the therapeutic potential of the novel antibiotic treatment strategy against endometriosis in light of endometrial infectious disease.

The alteration of intrauterine microbiota in chronic endometritis patients based on 16S rRNA sequencing analysis

BACKGROUND

Chronic endometritis (CE) is a disease of continuous and subtle inflammation occurring in the endometrial stromal area, which is often asymptomatic or present with non-specific clinical symptoms.

METHODS

This study investigated the composition and distribution of the intrauterine microbiota of 71 patients who underwent hysteroscopy during the routine clinical inspection of infertility. Among them, patients who were diagnosed with chronic endometritis (CE) were allocated into CE group (n = 29) and others into non-CE group (n = 42). There was no significant difference in average age between the two groups (P = 0.19). Uterine flushing fluid was collected by the self-developed cervical trocar uterine cavity sampler and 16S rRNA sequencing was performed.

RESULTS

The alpha diversity in the CE group was significantly higher than that in the non-CE group (P < 0.05). Firmicutes (newly named Bacillota) were the dominant phylum in the non-CE group (72.23%), while their abundance was much lower in the CE group (49.92%), but there was no statistically significant difference between the two groups. The abundances of Actinobacteriota and Cyanobacteria in the CE group were significantly higher than those in the non-CE group (P < 0.05). At the genus level, the abundance of Lactobacillus dominated in all samples, which presented a significantly lower abundance in the CE group (40.88%) than that in the non-CE group (64.22%) (P < 0.05). Correspondingly, the abundance of non-Lactobacillus was higher in the CE group, among which Pseudomonas and Cutibacterium increased significantly (P < 0.01). Moreover, compared with the non-CE group, the pathways involved in arginine and proline metabolism and retinol metabolism were significantly enriched in the CE group (P < 0.05), while the metabolism of lipid and prenyltransferases were significantly decreased in the CE group (P < 0.05).

CONCLUSIONS

A certain microbial community was colonized in the uterine cavity, which was dominated by Lactobacillus. The structure and distribution of intrauterine microbiota in the CE group were different from those in the non-CE group by showing a lower abundance of Lactobacillus, and a significantly higher abundance of Pseudomonas and Cutibacterium. Additionally, the microbial metabolism was altered in the CE group. This study elaborated the alteration of intrauterine microbiota in CE patients, which may contribute to the diagnosis of CE and provide a reference for antibiotic treatment of CE.

Trophoblastic infiltration of tubal pregnancy may have an association with chronic inflammation of the fallopian tube

OBJECTIVE

To explore the factors associated with trophoblastic infiltration in ampullary pregnancy from the perspective of clinical and pathologic characteristics.

METHODS

A single-center, retrospective, clinicopathologic cohort study was conducted in women who were diagnosed with tubal pregnancy and underwent salpingectomy in the International Peace Maternal and Child Health Care Hospital from January 2018 to June 2021.

RESULTS

A total of 333 eligible women diagnosed with ampullary pregnancy were included in the analysis. Multivariate logistic analysis showed that preoperative β-human chorionic gonadotropin greater than 3000 IU/L (adjusted odds ratio [aOR] 3.77, 95% confidence interval [CI] 2.02-7.03), and vascular remodeling phenomenon (aOR 4.34, 95% CI 2.41-7.83) were positively correlated with the infiltration of extravillous trophoblasts into serosa, while presence of chronic inflammation of the fallopian tube was a negatively corellated factor (aOR 0.49, 95% CI 0.29-0.85).

CONCLUSION

The depth of trophoblastic infiltration in tubal pregnancy may be related to the presence of chronic inflammation in the fallopian tube. A tubal pregnancy in a tube with chronic salpingitis is more likely to develop into an abortive ectopic pregnancy; whereas in a fallopian tube without chronic inflammation, the risk of it developing into a ruptured ectopic pregnancy increases. Hence, early identification is needed to properly address this dangerous pregnancy situation.

Should we stop screening for chronic endometritis?

Chronic endometritis is a poorly understood infectious or inflammatory process, potentially disrupting the correct implantation of a human embryo (Puente et al., 2020). The exact prevalence is a subject of discussion and ranges across the available literature from 2% to almost 60%, with a higher suspicion of the condition being present in women with recurrent early pregnancy loss and recurrent implantation failure (Puente et al., 2020). The impact of chronic endometritis on reproductive outcomes following IVF remains questionable given the lack of proper data convincingly showing an improvement after diagnosis and treatment. This article aims to provide the reader with a critical appraisal of current diagnostic methods, treatments and patient populations to be tested for chronic endometritis.

Oil-based contrast for hysterosalpingography-regulated Th1/Th2-type cytokines and alleviated inflammation in rats with LPS-induced chronic endometritis

AIM

The chronic endometritis (CE) prevalence in people experiencing infertility is 2.8-56.8%, pregnancy rates in patients with infertility increase after hysterosalpingography with oil-based contrast, but the effect and mechanism are not clear. Here, we analyzed the effects of intrauterine ethiodized poppyseed oil (EPO) bathing on a rat model of CE and the possible underlying mechanism.

METHODS

CE rats were induced by lipopolysaccharide (LPS) exposure, and rats were subjected to intrauterine bathing with EPO or phosphate-buffered saline (PBS) after model verification. Serum and uterus levels of IFN-γ, IL-4, TNF-α, and IL-1β were detected by ELISA kit, and the number of CD138⁺ and CD68⁺ cells and uterine IFN-γ, IL-4, TNF-α, IL-1β, and NF-κB P65 expression were detected by immunohistochemistry after bathing.

RESULTS

LPS exposure induced the typical CE phenotype with CD138⁺ phagocyte infiltration of the endometrial stroma. Compared with PBS bathing, bathing with EPO in CE rats showed decreases in the CD138⁺ and CD68⁺ cells populations and significant decreases in serum and uterine IFN-γ levels, moreover, uterine IL-4 levels were slightly higher, and the IFN-γ/IL-4(Th1/Th2-type cytokine ratio) in the uterus was significantly lower. Local IFN-γ, TNF-α, and NF-κB P65 expression in the endometrium was significantly downregulated, while IL-4 expression was upregulated.

CONCLUSION

Intrauterine oil-based contrast bathing significantly alleviated local inflammation in the rat CE model by downregulating NF-κB P65 expression, reducing IFN-γ (Th1), increasing IL-4 levels (Th2) in the endometrium, and regulating the Th1/Th2-type cytokine trends toward Th2.

The Cystic Anechoic Zone of Uterine Cavity Newly Observed during Controlled Ovarian Hyperstimulation Affects Pregnancy Outcomes of Fresh Embryo Transfer

During controlled ovarian hyperstimulation (COH), cystic anechoic zones in the uterine cavity are occasionally visible. This retrospective matched cohort study collected information on patients who underwent in vitro fertilization/intracytoplasmic injection (IVF/ICSI) from January 2014 to December 2020 at our center. The propensity score algorithm matched 179 cases that had uterine cystic anechoic zones, with 358 which did not have uterine cystic anechoic zones cases. After matching, the live birth rate (38.0% vs. 48.6%, p = 0.025) of patients with uterine cystic anechoic zones was lower than that in the no uterine cystic anechoic zone group, while for clinical pregnancy miscarriage rate (22.2% vs. 12.4%, p = 0.031), the rate was higher. The results showed no correlation in the association between live birth rate (r = −0.027, p = 0.718), clinical pregnancy rate (r = −0.037, p = 0.620) or biochemical pregnancy rate (r = −0.015, p = 0.840) and the diameters of the cystic anechoic zones in the uterine cavity. There was a significant difference in the type of endometrium between the two groups (p < 0.001). The result of this study can provide guidance to patients on whether to undergo fresh embryo transfer in the current cycle.

Gut and genital tract microbiomes: Dysbiosis and link to gynecological disorders

Every year, millions of women are affected by genital tract disorders, such as bacterial vaginosis (BV), endometrial cancer, polycystic ovary syndrome (PCOS), endometriosis, and uterine fibroids (UFs). These disorders pose a significant economic burden on healthcare systems and have serious implications for health and fertility outcomes. This review explores the relationships between gut, vaginal, and uterine dysbiosis and the pathogenesis of various diseases of the female genital tract. In recent years, reproductive health clinicians and scientists have focused on the microbiome to investigate its role in the pathogenesis and prevention of such diseases. Recent studies of the gut, vaginal, and uterine microbiomes have identified patterns in bacterial composition and changes across individuals' lives associated with specific healthy and diseased states, particularly regarding the effects of the estrogen-gut microbiome axis on estrogen-driven disorders (such as endometrial cancer, endometriosis, and UFs) and disorders associated with estrogen deficiency (such as PCOS). Furthermore, this review discusses the contribution of vitamin D deficiency to gut dysbiosis and altered estrogen metabolism as well as how these changes play key roles in the pathogenesis of UFs. More research on the microbiome influences on reproductive health and fertility is vital.

Effects of Hydrosalpinx on Endometrial Receptivity and Uterine Microbiome: An Interesting Case of Double Uterus with Unilateral Hydrosalpinx

Endometrial receptivity array (ERA)—an objective tool used in assisted reproductive technology—is used for personalized embryo transfer in in vitro fertilization. Hydrosalpinx affects implantation through various mechanisms. However, its effects on ERA are not well established. In this case report, we present the diagnosis and treatment of a 34-year-old nulligravida woman with infertility for two years, obesity, double uterus with unilateral hydrosalpinx and right kidney deficiency. Based on ERA results, endometrial microbiome metagenomic analysis (EMMA), analysis of infectious chronic endometritis (ALICE), and CD138 immunostaining, the patient was treated with hormonal replacement cycle and amoxicillin/clavulanic acid. After one week of amoxicillin/clavulanic acid administration, the vitirified-warmed 4AA blastocyst was transferred to the left uterus—which was absent of hydrosalpinx and easily accessible to transfer and pregnancy was achieved. To the best of our knowledge, this case study is the first one in which we found that there were no differences between the left and right uterus in ERA, EMMA, ALICE, and CD138 immunostainings. Hence, we suggest that hydrosalpinx does not necessarily cause endometrial changes in all cases. Further research to evaluate the effects of hydrosalpinx on implantation with ERA and EMMA/ALICE is warranted.

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.

Enhanced expression of miR-26a ameliorates lipopolysaccharide-induced endometritis by targeting MAP3K8 to inactivate MAPK signaling pathway

Endometritis is a severe postpartum inflammatory disease that puts cows' reproductive health at risk and causes the dairy industry to suffer significant financial losses. The present study aimed to investigate the regulatory role of miR‑26a in LPS‑induced bovine endometrial epithelial cells (bEECs) and the implication for endometritis. Here, we found inflammatory cell infiltration and destruction of endometrial structure in cow uterus, and dramatic increase in myeloperoxidase (MPO) activity and upregulation of pro-inflammatory cytokines (IL-1β, TNF-α, and IL-6) in endometritis. Meanwhile, miR-26a was down-regulated, but MAP3K8 was increased in the uterine tissue of endometritis. Similarly, the expression of miR-26a was significantly decreased in LPS-stimulated bEECs, while MAP3K8 was risen. In addition, we further verified that MAP3K8 was a target of miR-26a by dual-luciferase reporter assay. Under LPS stress, over-expressing miR-26a markedly decreased MAP3K8 expression levels, along with the reduced expression of inflammatory factors, such as IL-1β, TNF-α and IL-6, whereas this effect was countered by the inhibition of miR-26a. Furthermore, we demonstrated that miR-26a overexpression prevented the MAPK pathway from being activated by targeting MAP3K8. Then we carried out experiments in LPS-stimulated mice uterus to expound that MAP3K8 was essential in endometritis development, which further confirmed the reliability of the above results. In conclusion, overexpression of miR-26a effectively inhibited the expression of MAP3K8 in LPS-induced bEECs and thereby partially suppressed the activation of MAPK signaling pathway. miR-26a and MAP3K8 may be a promising biomarker and therapeutic target for dairy cow endometritis.

New biopsy after antibiotic treatment: effect on outcomes of assisted reproduction in patients with infertility and chronic endometritis

RESEARCH QUESTION

What is the effect of chronic endometritis on patients with infertility, the necessity of endometrial re-examination and the effect of improving chronic endometritis after one cycle of antibiotic treatment on pregnancy outcomes?

DESIGN

Infertile patients (n = 4003) who underwent IVF and intracytoplasmic sperm injection treatment were included. Pregnancy outcomes of groups positive for chronic endometritis were compared with groups that were negative (group 1). Patients that were positive were divided into the chronic endometritis new biopsy group (group 2) and chronic endometritis non-re-examination group (group 3). After doxycycline treatment and re-examination, the chronic endometritis new biopsy group was divided into improved chronic endometritis group (ICE) and not-improved chronic endometritis group (NICE), and their general indicators and reproductive outcomes were compared.

RESULTS

No significant difference was observed in embryo implantation, early or late pregnancy loss, ectopic pregnancy, clinical pregnancy and live birth rates between groups 2 and 3. The clinical pregnancy and live birth rates in the NICE group were significantly lower than those in the ICE group (P = 0.008 and P = 0.001, respectively). After controlling for potential confounding factors, age, average number of high-quality embryos, endometrial thickness on the day of embryo transfer and number and type of embryo transfer were factors associated with live birth rates.

CONCLUSIONS

Endometrial re-examination of women with chronic endometritis treated with doxycycline had no effect on pregnancy outcomes. The first cycle of doxycycline treatment could effectively improve reproductive outcomes of women with five or more CD138+ cells/high-power field.

Challenges in Clinical Diagnosis and Management of Chronic Endometritis

Chronic endometritis (CE) is a local mucosal infectious and inflammatory disorder characterized by unusual filtration of CD138(+) endometrial stromal plasmacytes. CE is attracting attention due to its potential association with infertility of unknown etiology, repeated implantation failure, recurrent pregnancy loss, and several maternal/neonatal complications. Due to the variance in study design among researchers, universal diagnostic criteria remain to be established for the clinical diagnosis and management of CE. This review article aims to summarize current knowledge and provide insights into unsolved questions on CE to establish clinical guidelines for the disease from the viewpoint of human reproduction.

Additional dydrogesterone for the treatment of chronic endometritis treated with antibiotic in premenopausal women with endometrial polyps: a retrospective cohort study

Background

To assess the efficacy of dysdrogesterone in the treatment of chronic endometritis (CE) treated with antibiotic in premenopausal women with endometrial polyps (EPs).

Methods

Routine detection of endometrium was simultaneously conducted to determine whether there was CE by syndecan-1 (CD138), while women underwent hysteroscopic polypectomy in our hospital. Antibiotic was given for the treatment of CE. A total of 235 premenopausal women with CE who underwent hysteroscopic polypectomy were enrolled in the retrospective observational study. In the control group, single antibiotic was given for the treatment of CE form January 2016 to December 2018, and in the treatment group additional dydrogesterone was used from January 2019 to November 2020. Comparison of cure rates of CE with different treatment regimens was performed.

Results

The cure rates of CE in dydrogesterone and antibiotic combination group and the single antibiotic group were 85.2% and 74.3%, respectively, with overall cure rate of 80.0% (188/235). The combination group showed better effects regarding the cure rate of CE (P < .05). Multivariate analysis confirmed that the cure rate of CE was not affected by age, body mass index, number of EPs, the status of estrogen receptor and the status of progesterone receptor. Conversely, dydrogesterone and endometrial scratching were beneficial factors for cure rate increase with antibiotic treatment.

Conclusion

Combination of dydrogesterone and antibiotic was more effective for cure rate of CE than antibiotic alone in premenopausal women after hysteroscopic polypectomy. Endometrial scratching also contributed to the cure rate increase with antibiotic treatment.

Intrauterine LPS inhibited arcuate Kiss1 expression, LH pulses, and ovarian function in rats

In brief

Uterine inflammatory diseases are a major cause of infertility in humans and domestic animals. The current findings that intrauterine lipopolysaccharide is absorbed in systemic circulation and attenuates ovarian cyclic activities could provide a basis for developing novel treatments to improve fertility.

Abstract

Uterine inflammatory diseases are a major cause of infertility in humans and domestic animals. Circulating lipopolysaccharide (LPS), a bacterial endotoxin causing uterine inflammation, reportedly downregulates the hypothalamic-pituitary-gonadal axis to mediate ovarian dysfunction. In contrast, the mechanism whereby intrauterine LPS affects ovarian function has not been fully clarified. This study aimed to elucidate whether uterine exposure to LPS downregulates hypothalamic kisspeptin gene (Kiss1) expression, gonadotropin release, and ovarian function. Uterine inflammation was induced by intrauterine LPS administration to ovary-intact and ovariectomized female rats. As a result, plasma LPS concentrations were substantially higher in control rats until 48 h post injection, and the estrous cyclicity was disrupted with a prolonged diestrous phase. Three days post injection, the number of Graafian follicles and plasma estradiol concentration were reduced in LPS-treated rats, while numbers of Kiss1-expressing cells in the anteroventral periventricular nucleus and arcuate nucleus (ARC) were comparable in ovary-intact rats. Four days post injection, ovulation rate and plasma progesterone levels reduced significantly while gene expression of interleukin1β and tumor necrosis factor α was upregulated in the ovaries of LPS-treated rats that failed to ovulate. Furthermore, the number of Kiss1-expressing cells in the ARC and pulsatile luteinizing hormone (LH) release were significantly reduced in ovariectomized rats 24 h post injection. In conclusion, these results indicate that intrauterine LPS is absorbed in systemic circulation and attenuates ovarian function. This detrimental effect might be caused, at least partly, by the inhibition of ARC Kiss1 expression and LH pulses along with an induction of ovarian inflammatory response.