The Diagnostic Criteria for Chronic Endometritis: A Survey of Pathologists

Risk factors of chronic endometritis in women who have undergone hysteroscopy: a prospective nested case-control study

There is limited research on risk factors for chronic endometritis regarding reproductive history and clinical symptoms. Thus, this nested case-control study identified risk factors for chronic endometritis in women who have undergone hysteroscopy. Endometrial tissue sections were obtained from 502 women with intrauterine disorders who underwent hysteroscopy. Chronic endometritis was diagnosed via CD138 immunostaining. The women were divided into two groups: 271 women without chronic endometritis and 231 women with chronic endometritis. The prevalence of chronic endometritis was 46%. Univariate logistic regression revealed that prolonged menstruation and intermenstrual bleeding were associated with chronic endometritis, and subsequent multivariate logistic regression analyses showed that these were further independently associated. With univariable logistic regression, the gravidity and abortion history were correlated with chronic endometritis; however, no significant correlation was found with the adjusted odds ratio (OR) of 0.74 (95% confidence interval [CI] 0.46-1.19) or 0.76 (95% CI 0.58-1.11), respectively. No significant correlation was found between caesarean section history and the rates of chronic endometritis. No significant difference was found in all other variables between the three groups with > 5, ≤ 5 plasma cells and in a unknown group. Prolonged menstruation and intermenstrual bleeding were risk factors associated with chronic endometritis. Chronic endometritis should be considered and CD138 immunohistochemical examination should be recommended in women with these symptoms.

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.

Hysteroscopic features suggestive of chronic endometritis: a systematic review

The purpose of this systematic review is to identify common hysteroscopic findings suggestive of endometritis, chronic or subclinical, based on current scientific evidence. Data sources were MEDLINE, Embase, PubMed and other sources of grey literature. Four (4) authors independently selected studies addressing hysteroscopic detection of CE based on specific and clearly stated hysteroscopic criteria. The diagnosis was confirmed by histologic assessment, as stated in the materials and methods of these studies included. The initial search identified 599 studies, of which 21 met the inclusion criteria. Significant heterogeneity among published studies on Chronic endometritis (CE) remains the main limitation in performing a metanalysis and further analysis of diagnostic accuracy on the subject. Hysteroscopy is an important diagnostic tool in cases of chronic endometritis when accompanied by endometrial biopsies. Clinicians relate hyperaemia and endometrial oedema with chronic endometritis while more than half include micropolyposis as a pathognomonic feature of this subclinical condition. Micropolyps, stromal oedema, haemorrhagic spots, strawberry aspect, and hyperaemia are proposed as adequate indicators of hysteroscopic evidence of CE according to the literature. The impact of CE in long-term reproductive outcomes remain unclear, thus clinicians ought to communicate this to the patients and provide treatment where clinically appropriate. In addition, we present hysteroscopic images of histologically confirmed CE cases that could play the role of a hysteroscopic atlas.

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 combination of CD138/MUM1 dual-staining and artificial intelligence for plasma cell counting in the diagnosis of chronic endometritis

OBJECTIVE

To investigate the utility of combination of CD138/MUM1 dual-staining (DS) and artificial intelligence (AI) for plasma cell (PC) counting in the diagnosis of chronic endometritis (CE).

METHODS

Two hundred ninety-eight infertile women underwent endometrial biopsy were included. In 100 women, three successive sections were cut from each paraffin-embedded tissue block for CD138 immunohistochemical (IHC) single-staining (SS), MUM1 SS and CD138/MUM1 DS. The prevalence of CE and the sensitivity/specificity in the diagnosis of CE with different methods was studied. These sections diagnosed as CE with DS were collected to train artificial intelligence (AI) diagnostic system. In other 198 women, their tissue sections stained with CD138/MUM1 DS were used to test the AI system in the diagnosis of CE.

RESULTS

CD138/MUM1 DS revealed that the cell membranes and nuclei of PCs were simultaneously labelled by CD138 and MUM1, respectively. The positive rate of ECs identified by CD138/MUM1 DS (38%, 38/100) was lower than CD138 SS (52%, 52/100) and MUM1 SS (62%, 62/100) (p < .05). The sensitivity, specificity and accuracy of CD138/MUM1 DS in the diagnosis of ECs reached 100%. The sensitivity, specificity and accuracy rates of AI diagnostic system of ECs were 100%, 83.3% and 91.4%, respectively. The 17 cases over-diagnosed as EC with the AI were corrected quickly by pathologists reviewing these false PC pictures listed by the AI.

CONCLUSION

The combination of CD138/MUM1 DS and AI is a promising method to improve the accuracy and efficiency of CE diagnosis.

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.

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.

LPS-Induced Activation of the cGAS-STING Pathway is Regulated by Mitochondrial Dysfunction and Mitochondrial DNA Leakage in Endometritis

Introduction

Chronic endometritis is a common disease in women of childbearing age and can cause pelvic inflammatory disease. The cGAS-STING pathway plays an important role in many inflammatory diseases.

Purpose

The aim of this study was to investigate the relationship between the cGAS-STING pathway and endometritis.

Methods

We collected endometrium samples from patients with endometritis to detect changes in the cGAS-STING pathway. In vitro, human endometrial stromal cells (HESC) were stimulated with lipopolysaccharide (LPS), and a mouse STING gene-knockout model was established by CRISPR/cas9 for STING to further explore the mechanism underlying its effects in endometritis. We used Western blotting (WB) and immunohistochemical staining to detect the variations in protein levels and real-time PCR to study the variations in gene expression.

Results

We observed the activation of the cGAS-STING pathway and an increase in the expression of cytokine-encoding genes, including IL-8, IL-6, IL-1β, and IFN-β1, in endometrial tissues of patients with endometritis. Stimulation of HESCs using LPS demonstrated increase in the expression of proteins involved the cGAS-STING pathway and the gene expression of inflammatory cytokines. STING-knockdown experiments demonstrated a decrease in the gene expression levels of inflammatory cytokines. Moreover, we also identified the translocation of IRF3 and STING after LPS stimulation. Regarding mitochondrial function, LPS led to an increase in reactive oxygen species levels and a reduction in mitochondrial membrane potential. However, we observed that the mitochondrial DNA (mtDNA) leaked into the cytoplasm, upregulating the levels of proteins involved in the cGAS-STING pathway upon LPS stimulation. Furthermore, our results showed that LPS induced hyperemia, inflammatory factor production, and expression of Pho-TBK1 in wild-type mice compared with the levels in control mice, and STING gene-knockdown alleviated these effects.

Conclusion

LPS induces mitochondrial dysfunction in endometrial stromal cells, resulting in mtDNA leakage and promoting endometritis by stimulating the cGAS-STING pathway.

The menstrual cycle phase impacts the detection of plasma cells and the diagnosis of chronic endometritis in endometrial biopsy specimens

OBJECTIVE

To assess the impact of menstrual cycle phase on the detection of plasma cells.

DESIGN

A retrospective cohort study.

SETTING

Fertility clinic.

PATIENT(S)

Biopsies from 157 patients met criteria for inclusion, 91 in the follicular phase and 60 in the luteal phase. Patient groups were similar in body mass index and number of previous live births; however, differed in terms of age, infertility history, and biopsy indication.

INTERVENTIONS

Endometrial biopsies from patients at a fertility clinic from 2018-2020 were retrospectively reviewed. Biopsies were excluded if patients had a previous chronic endometritis diagnosis, abnormal uterine cavity or were on hormone therapy. Each case was reviewed by a gynecologic pathologist for plasma cells by hematoxylin and eosin and CD138 staining. Demographic and clinical data were collected. Continuous variables were compared using Welch t test and Wilcoxon's rank sum test, and categorical variables using Pearson's χ² test. Logistic regression was used to calculate odds ratio and 95% confidence intervals for the association between the presence of plasma cells and cycle phase. Multinomial logistic regression was used to estimate the odds ratios for nominal outcomes. Pathology reports were reviewed. Plasma cell enumeration using hematoxylin and eosin-stained sections and CD138 immunohistochemical stains (performed at the time of biopsy by a gynecologic pathologist) was recorded.

MAIN OUTCOME MEASURE(S)

Presence and density of plasma cells.

RESULT(S)

We found a higher likelihood of finding plasma cells in the follicular than in luteal phase (59.3% vs. 19.7%). There was a higher likelihood of finding plasma cells in the early (cycle days 5-8, 29 cases or 76.3% of cases with plasma cells) than in the late follicular phase (cycle days 9-14, 25 cases or 47.2%). There was a higher density of plasma cells in the follicular phase group than in the luteal phase group (25.3% vs. 1.5% scattered and 13.2% vs. 0 clusters).

CONCLUSION(S)

Plasma cells are more likely to be present during the follicular phase compared with the luteal phase and in the early compared with the late follicular phase. Further studies are needed to identify the optimal timing of biopsy to standardize the diagnosis.

Does antibiotic therapy for chronic endometritis improve clinical outcomes of patients with recurrent implantation failure in subsequent IVF cycles? A systematic review and meta-analysis

PURPOSE

This study aims to assess whether antibiotic therapy for chronic endometritis (CE) could improve subsequent IVF outcomes in patients with recurrent implantation failure (RIF).

METHODS

Studies that explore CE treatment in patients with RIF were retrieved from PubMed, EMBASE, Wanfang, and Google Scholar up to Jan 31, 2022. All retrieved studies were selected according to the inclusion and exclusion criteria. The main outcome measures include implantation rate (IR), clinical pregnancy rate (CPR), ongoing pregnancy rate/live birth rate (OPR/LBR), and miscarriage rate (MR). Odds ratios (ORs) were analyzed for pregnancy outcomes with a 95% confidence interval (CI).

RESULTS

Nine articles were enrolled in this study. Patients receiving oral antibiotic administration (OAA) did not show any advantage over patients without CE with regard to IR, OPR/LBR, and MR, but they showed a higher CPR. Patients with cured CE after OAA therapy had significantly higher CPR, IR, and OPR/LBR compared with patients without CE. Patients with persistent CE after OAA therapy had significantly lower IR, CPR, and OPR/LBR compared with patients without CE. Patients with cured CE had significantly higher IR, CPR, and OPR/LBR compared with persistent CE patients.

CONCLUSIONS

Antibiotic treatment may improve the pregnancy outcomes of RIF patients in subsequent IVF cycles only if the condition of CE is confirmed cured in a control biopsy afterwards. Otherwise, no sufficient evidence has shown improvements in clinical outcomes in RIF patients with persistent CE.

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.

Upstream stimulatory factor 2 (USF2) induced upregulation of triggering receptor expressed on myeloid cells 1 (TREM1) promotes endometritis by regulating toll-like receptor (TLR) 2/4-nuclear factor-kappaB (NF-κB) signaling pathway

Triggering receptor expressed on myeloid cells 1 (TREM1) participates in the development of endometritis. This study aims at identifying the effects and interaction of TREM1 and upstream stimulatory factor 2 (USF2) in endometritis by using a model of lipopolysaccharide (LPS)-induced human endometrial epithelial cells (HEnEpCs). ELISA was performed to determine the levels of interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF-α) after LPS stimulation. TREM1 and USF2 expression was examined with RT-qPCR and Western blot. The JASPAR database was employed to predict the binding site between USF2 and TREM1, which was confirmed by luciferase reporter and chromatin immunoprecipitation assays. After TREM1 overexpression, IL-6, IL-1β, and TNF-α expression was detected by ELISA. Next, the binding of TREM1 to toll-like receptor (TLR) 2/4 was examined with co-immunoprecipitation. Then, proteins in TLR2/4-nuclear factor-kappaB (NF-κB) signaling in HEnEpCs under LPS condition were assessed by Western blot or immunofluorescence before and after TREM1 knockdown. Finally, TLR2 or TLR4 was silenced to explore whether intervene TLR2/4-NF-κB signaling pathway could rescue TREM1-overexpression-induced inflammation in LPS-induced HEnEpCs. Results revealed that upregulated TREM1 was observed in LPS-challenged HEnEpCs. Next, USF2 was found to have transcriptionally active TREM1 expression. Additionally, USF2 knockdown decreased the levels of IL-6, IL-1β, and TNF-α, whereas this effect was rescued after TREM1 overexpression. Besides, TREM1 could bind to TLR2/4 to regulate NF-κB signaling. Moreover, the intervention of TLR2/4-NF-κB signaling pathway rescued TREM1-overexpression-induced inflammation in LPS-stimulated HEnEpCs. Collectively, USF2 promotes endometritis by upregulating TREM1, thereby activating TLR2/4-NF-κB pathway.

Chronic endometritis: A prevalent yet poorly understood entity

OBJECTIVE

To examine the prevalent understanding of and management approaches to chronic endometritis among obstetricians/gynecologists.

METHODS

In a cross-sectional observational study, 262 members of national and international professional obstetrician/gynecologist societies were surveyed via anonymous electronic survey that investigated knowledge of the pathophysiology, diagnostic criteria, clinical implications, and treatment strategies for chronic endometritis. Statistical analyses of results were performed using Fisher's exact tests, chi square tests and odds ratios with 95% confidence intervals. A two-sided P < 0.05 was deemed statistically significant.

RESULTS

Responses identified a concerning spectrum of deficiencies in the understanding of the pathophysiology of chronic endometritis, in awareness of clinical presentation of chronic endometritis, and in the understanding of methodology/ies that allow diagnosis of chronic endometritis. Heterogeneities in management approaches to chronic endometritis were apparent.

CONCLUSION

Our findings underscore a need for targeted efforts to gain clarity on chronic endometritis and to establish evidence-based consensus for good clinical practice. In the absence of a clear understanding of chronic endometritis diagnosis, we posit that the prevalent inconsistencies are likely inflicting unquantified and underappreciated burdens on patients and healthcare systems. We propose consideration for a task force to examine existing literature and create standards for good practice for a prevalent condition.