Can endometrial infection/inflammation explain implantation failure, spontaneous abortion, and preterm birth after in vitro fertilization?

Viral Infection in Endometritis: Is There an Important Role or Not?

Chronic endometritis (CE) is a frequent pathological condition that is defined as localized inflammation in the endometrium. Some adverse fertility consequences such as recurrent miscarriage and failure of implantation are associated with chronic endometritis. On the one hand, inflammation plays an important role in the pathogenesis of endometritis, and on the other hand, the role of viral infections in inducing inflammation can make this review strongly attractive and practical. We set out to provide an overview of viral infections as a potential etiology of CE pathophysiology through the alteration of an endometrial microenvironment and its association with infertility. To the best of our knowledge, this is the first review to demonstrate the role of viral infection in chronic endometritis, and whether or not infection ultimately plays a role..

Prevalence and confounders of chronic endometritis diagnosed using CD138 in patients with recurrent implantation failure

OBJECTIVE

This retrospective study aimed to investigate the prevalence of chronic endometritis, diagnosed using CD138 immunohistochemistry, among infertile women and to assess the association between chronic endometritis and recurrent implantation failure (RIF).

METHODS

In total, 266 patients who underwent hysteroscopy due to infertility between 2019 and 2020 were included in the analysis. Of these, 136 patients with RIF and 130 non-RIF patients were included in the study. CD138 immunohistochemistry test results, blood biomarkers (including natural killer cells, white blood cells, and the lymphocyte-to-neutrophil ratio), and data on pregnancy outcomes were obtained. If the CD138 test yielded a positive result, the patients received antibiotic treatment.

RESULTS

The overall proportion of CD138-positive patients was 32.7% (87/266). The CD138 positivity rate was not related to the number of cycles with implantation failure. In the RIF patient group, no significant associations were found between CD138 positivity and peripheral blood markers. The clinical pregnancy rates were similar between infertile women treated with antibiotics for chronic endometritis and those without chronic endometritis.

CONCLUSION

To improve the pregnancy rate in infertile patients, it may be helpful to combine CD138 testing with other laboratory tests and administer antibiotic treatment if the result is positive.

Endometrial preparation protocols did not impact pregnancy outcomes of patients with cured chronic endometritis

RESEARCH QUESTION

Do endometrial preparation protocols have an effect on pregnancy outcomes in patients with cured chronic endometritis?

DESIGN

A retrospective study was conducted on 3721 infertile patients from December 2018 to August 2020. Endometrial tissues obtained during the proliferative phase were immunostained for CD138. The presence of CD138-positive cells within the stromal cells indicated chronic endometritis. All patients diagnosed with chronic endometritis received oral antibiotics. Patients underwent endometrial preparation and frozen embryo transfer once chronic endometritis was cured. This study compared various endometrial preparation protocols to assess their effects on pregnancy outcomes. Additionally, it aimed to investigate differences in pregnancy outcomes between patients without chronic endometritis and patients with cured chronic endometritis while following the same endometrial preparation protocol.

RESULTS

Almost no differences in pregnancy outcomes were observed between natural cycle, hormone replacement therapy (HRT) and gonadotrophin-releasing hormone agonist-HRT (GnRH agonist-HRT) protocols in patients without chronic endometritis and patients with cured chronic endometritis. The only notable difference was that, among women without chronic endometritis, the early miscarriage rate was higher for the GnRH agonist-HRT protocol (25.8%) compared with the natural cycle (17.4%) and HRT (17.7%) protocols (P = 0.025). However, this difference was not significant after adjusting for confounders (adjusted OR 1.383, 95% CI 0.931-2.055). The live birth rate, clinical pregnancy rate, early miscarriage rate, ectopic pregnancy rate and ongoing pregnancy rate did not differ significantly (P > 0.05) between patients without chronic endometritis and patients with cured chronic endometritis who underwent natural cycle, HRT and GnRH agonist-HRT protocols.

CONCLUSION

Endometrial preparation protocols had no impact on pregnancy outcomes in patients with cured chronic endometritis.

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

Objective and rationale

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

Methods

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

Results

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

Conclusions

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

The efficacy of vaginal treatment for non-Lactobacillus dominant endometrial microbiota-A case-control study

AIM

Reduced Lactobacillus occupancy in the uterine microflora has been associated with implantation failure. This study aimed to evaluate a treatment for improving the uterine microflora.

METHODS

This study included patients diagnosed with repeated implantation failure-defined as failure to achieve pregnancy after two or more transfers of viable embryos-who were classified as non-Lactobacillus dominant. Treatment A comprised oral administration of antibiotics for 1 week, followed by oral probiotic butyrate tablets (3 g/day) for approximately 30 days. Treatment B comprised a 1-week course of oral (750 mg/day) and vaginal (250 mg/day) metronidazole, followed by a 1-week intravaginal administration of probiotic capsules (1 capsule/day) and continued oral administration of probiotics (1 capsule/day). Both treatments were compared in terms of efficacy in improving vaginal flora. Improvement was defined as Lactobacillus occupancy >90% or an increase in Lactobacillus occupancy >20%.

RESULTS

Seven (41.2%) of 17 patients in the Treatment A group improved in response to the treatment. Contrastingly, 9 (90.0%) of 10 patients improved in the Treatment B group (p = 0.0127). Following treatment, Lactobacillus occupancy in the Treatment B group (62.9% ± 12.7%) was significantly higher than that in the Treatment A group (5.7% ± 9.8%) (p = 0.0242).

CONCLUSIONS

This study demonstrates the effectiveness of combining antibiotics and probiotics in vaginal formulations for treating abnormal uterine microflora. However, its potential impact on in vitro fertilization outcomes remains unclear and warrants further investigation through larger, more comprehensive studies.

Melatonin Alleviates Lipopolysaccharide-Induced Abnormal Pregnancy through MTNR1B Regulation of m6A

Pregnancy is a highly intricate and delicate process, where inflammation during early stages may lead to pregnancy loss or defective implantation. Melatonin, primarily produced by the pineal gland, exerts several pharmacological effects. N6-methyladenosine (m6A) is the most prevalent mRNA modification in eukaryotes. This study aimed to investigate the association between melatonin and m6A during pregnancy and elucidate the underlying protective mechanism of melatonin. Melatonin was found to alleviate lipopolysaccharide (LPS)-induced reductions in the number of implantation sites. Additionally, it mitigated the activation of inflammation, autophagy, and apoptosis pathways, thereby protecting the pregnancy process in mice. The study also revealed that melatonin regulates uterine m6A methylation levels and counteracts abnormal changes in m6A modification of various genes following LPS stimulation. Furthermore, melatonin was shown to regulate m6A methylation through melatonin receptor 1B (MTNR1B) and subsequently modulate inflammation, autophagy, and apoptosis through m6A. In conclusion, our study demonstrates that melatonin protects pregnancy by influencing inflammation, autophagy, and apoptosis pathways in an m6A-dependent manner via MTNR1B. These findings provide valuable insights into the mechanisms underlying melatonin's protective effects during pregnancy and may have implications for potential therapeutic strategies in managing pregnancy-related complications.

Pregravid preparation of women with chronic endometritis in IVF cycles

OBJECTIVE

Aim: of our study was to improve the pregravid preparation of women with chronic endometritis to develop individual approaches to overcoming infertility, taking into account the state of endometrium.

PATIENTS AND METHODS

Materials and Methods: The study included 90 women (main group, n=90), 28 to 38 years with an anatomically normal uterus and chronic endometritis (CE). Patients were divided into 2 groups: group I - 45 women with CE who received conventional treatment; group II - 45 women with CE who received pregravid preparation by subendometrial injections of Platelet-Rich Plasma (PRP).

RESULTS

Results: At the first stage of study, the ART statistical reports from 2015 to 2022 were analyzed at the Medical Center of Reproductive Health ≪Damia≫, (Ivano-Frankivsk). Analysis of the vaginal flora parameters before treatment at the first stage revealed the presence of conditionally pathogenic flora in culture from the cervical canal (Candida albicans - 2.4%, Escherihia coli - 4.8%, Staphylococcus epidermidis - 6.2% Enterococcus faecalis - 6.9%), and was evidence of a possible recurrence of inflammation during gestation. In the age category, the groups of patients were homogeneous, with no significant differences by the level of AMH and the level of CD 138. Biochemical pregnancy be present in 20 patients (44.4%) of group I and 28 (62.2%) of group II. Fertility within a year after the end of therapy was restored with the proposed method of therapy in most women (51.1%), in the comparison group this number was 11.1% lower. Pregnancy rate between the groups (I and II) did not differ significantly. The number of live births in group II - 19 births (42.2%) - was 2 times higher than I group (9 (20.0%), P<0.05). The most common complication for women in the comparison groups was early pregnancy loss. Among 18 (40.0%) clinical pregnancies of group I, 8 women (17.8%) had early miscarriage, 1 ectopic pregnancy (2.2%), while in group II clinical pregnancy be present in 23 women (51.1%). The number of terminated pregnancies was two times lower than in the first group (8.9% vs. 17.8%, P<0.05).

CONCLUSION

Conclusions: Chronic endometritis is one of the main causes of pregnancy loss after in vitro fertilization. Patients of the second group were treated with the proposed method of subendometrial injections with Platelet-Rich Plasma (PRP), prepared from autologous blood, is an effective method of preparing the endometrium for embryo transfer and can increase the number of live births in patients with chronic endometritis.

Uterine Microbiome: Does the Sampling Technique Matter?

Studies have proven the significance of microbial communities in various parts of the human body for health. In recent years it has been discovered that the uterine cavity is not sterile, and endometrium has its own microbiome which appears to have an impact on female fertility and gynecological pathologies. Lactobacillus has shown to dominate the microbial profile in the uterus and is considered an indicator of a healthy uterine environment. Yet, many argue that the Lactobacillus dominance is due to vaginal contamination during the sampling process. To date there is no clearly defined healthy endometrial microbial profile, which is largely due to the fact that determining the microbial community from the endometrium is complicated, and there is currently no consensus on sampling methods for the endometrial microbiome. As a result, this restricts ability to replicate discoveries made in other cohorts. Here we aim to give an overview of the sampling methods used and discuss what impedes the endometrial microbiome studies as well as how to reach a consensus on the study design. This knowledge could be incorporated into the future research and the knowledge on endometrial microbiome could be included into the diagnostics and treatment of female reproductive health.

A Narrative Review Discussing the Obstetric Repercussions Due to Alterations of Personalized Bacterial Sites Developed within the Vagina, Cervix, and Endometrium

BACKGROUND

The reproductive tract microbiota that evolved as an integrative component has been studied intensively in the last decade. As a result, novel research, clinical opportunities, and perspectives have been derived following the close investigation of this microecological environment. This has paved the way for an update to and improvement of the management strategies and therapeutic approaches. However, obscurities, contradictions, and controversies arise regarding the ascension route from the vagina to the endometrium via the cervix, with finality in adverse obstetric outcomes.

METHODS

Starting from these considerations, we aimed to gather all existing data and information from four major academic databases (PubMed, ISI Web of Knowledge, Scopus, and ScienceDirect) published in the last 13 years (2010-2023) using a controlled vocabulary and dedicated terminology to enhance the coverage, identification, and sorting of potentially eligible studies.

RESULTS

Despite the high number of returned entries (n = 804), only a slight percentage (2.73%) of all manuscripts were deemed eligible following two rounds of evaluation. Cumulatively, a low level of Lactobacillus spp. and of other core microbiota members is mandatory, with a possible eubiosis-to-dysbiosis transition leading to an impairment of metabolic and endocrine network homeostasis. This transposes into a change in the pro-inflammatory landscape and activation of signaling pathways due to activity exerted by the bacterial lipopolysaccharides (LPSs)/endotoxins that further reflect a high risk of miscarriage in various stages. While the presence of some pathogenic entities may be suggestive of an adverse obstetric predisposition, there are still pros and cons of the role of specific strains, as only the vagina and cervix have been targeted as opposed to the endometrium, which recently started to be viewed as the key player in the vagina-cervix-endometrium route. Consequently, based on an individual's profile, diet, and regime, antibiotics and probiotics might be practical or not.

CONCLUSIONS

Resident bacteria have a dual facet and are beneficial for women's health, but, at the same time, relaying on the abundance, richness, and evenness that are definitory indexes standing as intermediaries of a miscarriage.

Inhibition of TMUB1 blocks apoptosis and NF-κB pathway-mediated inflammation in recurrent spontaneous abortion

INTRODUCTION

Approximately 50% of cases with recurrent spontaneous abortion (RSA) have unexplained etiology. Aberrant expression of transmembrane and ubiquitin-like domain containing 1 (TMUB1) is closely related to a series of diseases, including RSA. However, the function and underlying mechanism of TMUB1 in the occurrence of RSA has not been described.

METHODS

TMUB1 expression was detected in the placental villous tissues of 30 women with normal miscarriages and 12 women with RSA. The pregnant mice were injected intraperitoneally with lipopolysaccharide (LPS) to induce abortion. Human chorionic trophoblast cells were treated with LPS. Pathological analysis of placental tissues was performed by hematoxylin and eosin staining.

RESULTS

TMUB1 was highly expressed in the placental villous tissues of RSA patients compared to the patients who underwent induced abortions. After LPS administration, the mice exhibited high embryo absorption and pathological alterations, as well as presented an increase in inflammation and apoptosis (the etiology of RSA induction) in placental tissues. Moreover, the upregulated expression of TMUB1 was also found in placental tissues of LPS-induced mice, and further investigation showed that TMUB1 deficiency blocked embryo loss as well as inhibited apoptotic rate and inflammation after LPS activation. Furthermore, we found that the loss of TMUB1 suppressed the phosphorylation of IkappaB kinase (IKK) α/β and attenuated cytoplasmic-nuclear translocation of nuclear factor-κB (NF-κB) p65 in LPS-induced cells.

CONCLUSION

Our results indicate that TMUB1 may involve in the modulation of apoptosis and NF-κB pathway-mediated inflammation in RSA. Therefore, TMUB1 may develop as a potential biomarker for RSA treatment.

Comparison of microbial profiles and viral status along the vagina-cervix-endometrium continuum of infertile patients

For decades, the endometrium was considered to be a sterile environment. However, now this concept is disputed, and there is growing evidence that microbiota composition might affect endometrial receptivity. Routine clinical management of infertility is still limited to a microbiological assessment of the lower reproductive tract. The purpose of this study was to compare the abundance of various bacterial, fungal, and viral species, qualitatively and quantitatively, in vaginal, cervical, and endometrial biomaterial of infertile patients. A total of 300 samples from 100 infertile patients of a private assisted reproduction clinic were analyzed. A broad real-time polymerase chain reaction panel was used to identify 28 relevant microbial taxa as well as three members of the Herpesviridae family. All patients underwent endometrial biopsy for further histopathological evaluation. Analysis of the microbial diversity (within the boundaries of the detection panel) revealed that Shannon indexes in the cervix and vagina were similar (1.4 × 10^-2 (1.6 × 10^-3 - 6.5 × 10^-1) vs 1.9 × 10^-2 (2.3 × 10^-3 - 5.3 × 10^-1), respectively, p = 0.502), whereas endometrial indexes differed significantly from both regions (0 (0 - 1.4 × 10^-1), p < 0.0001). Surprisingly, 17 microbial and viral taxa were detected in at least one sample. Endometrium exhibited a quite distinct microbiological profile, being different at the detection rates of 14 taxa (p < 0.05). Remarkably, 4% and 2% of endometrial samples were positive for Cytomegalovirus and Candida spp., respectively, while these were undetectable in corresponding cervical and vaginal samples. Prevalence of the Gardnerella vaginalis + Prevotella bivia + Porphyromonas spp. group in endometrium was associated with a low abundance of Lactobacillus spp. (p = 0.039). No noteworthy associations were identified between various microbiota characteristics and clinical parameters, such as chronic endometritis, uterine polyps and adhesions, endometriosis, and a history of sexually transmitted infections. These findings indicate that the microbiological profile of the endometrium is unique, and the analysis of the lower reproductive tract should supplement, rather than be a substitute for it.

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.

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.

Therapeutic intervention based on gene sequencing analysis of microbial 16S ribosomal RNA of the intrauterine microbiome improves pregnancy outcomes in IVF patients: a prospective cohort study

PURPOSE

A Lactobacillus-dominated microbiota in the endometrium was reported to be associated with favorable reproductive outcomes. We investigated in this study whether 16S ribosomal RNA (rRNA) gene sequencing analysis of the uterine microbiome improves pregnancy outcomes.

METHODS

This prospective cohort study recruited a total of 195 women with recurrent implantation failure (RIF) between March 2019 and April 2021 in our fertility center. Analysis of the endometrial microbiota by 16S rRNA gene sequencing was suggested for all patients who had three or more failed embryo transfers (ETs). One hundred and thirty-one patients underwent microbial 16S rRNA gene sequencing (study group) before additional transfers, while 64 patients proceeded to ET without that analysis (control group). The primary outcome was to compare the cumulative clinical pregnancy rate of two additional ETs.

MAIN RESULTS

An endometrial microbiota considered abnormal was detected in 30 patients (22.9%). All but one of these 30 patients received antibiotics according to the bacterial genus detected in their sample, followed by treatment with probiotics. As a result, the cumulative clinical pregnancy rate (study group: 64.5% vs. control group: 33.3%, p = 0.005) and the ongoing pregnancy rate (study group: 48.9% vs. control group: 32.8%, p = 0.028) were significantly increased in the study group compared to the control group.

CONCLUSION

Personalized treatment recommendations based on the microbial 16S rRNA gene sequencing of the uterine microbiota can improve IVF outcomes of patients with RIF.

TRIAL REGISTRATION

The University Hospital Medical Information Network (UMIN) Clinical Trial Registry: UMIN000036050 (date of registration: March 1, 2019).

The role of intraamniotic inflammation in threatened midtrimester miscarriage

BACKGROUND

The assessment and management of patients with threatened midtrimester miscarriage is a clinical challenge because the etiology of this condition is poorly understood.

OBJECTIVE

This study aimed to examine the frequency of intraamniotic infection or inflammation and the effect of antibiotics in patients presenting with regular uterine contractions and intact membranes before 20 weeks of gestation.

STUDY DESIGN

This retrospective study comprised patients who met the following criteria: (1) singleton gestation, (2) gestational age before 20 weeks, (3) the presence of regular uterine contractions confirmed by a tocodynamometer (8 or more contractions in 60 minutes), (4) intact amniotic membranes, and (5) transabdominal amniocentesis performed for the evaluation of the microbiologic and inflammatory status of the amniotic cavity. Samples of amniotic fluid were cultured for aerobic and anaerobic bacteria and genital mycoplasmas, and polymerase chain reaction was performed to detect Ureaplasma species. Amniotic fluid was tested for white blood cell counts and matrix metalloproteinase-8 concentrations to diagnose intraamniotic inflammation. Patients with intraamniotic inflammation, or intraamniotic infection, were treated with antibiotics (a combination of ceftriaxone, clarithromycin, and metronidazole). Treatment success was defined as the resolution of intraamniotic infection/inflammation at the follow-up amniocentesis or delivery after 34 weeks of gestation.

RESULTS

1) Intraamniotic inflammation was present in 88% (15/17) of patients, whereas infection was detectable in only 2 cases; 2) objective evidence of resolution of intraamniotic inflammation after antibiotic treatment was demonstrated in 100% (4/4) of patients who underwent a follow-up amniocentesis; 3) 30% (5/15) of women receiving antibiotics delivered after 34 weeks of gestation (3 of the 5 patients had a negative follow-up amniocentesis, and 2 of the women were without a follow-up amniocentesis); 4) the overall treatment success of antibiotics was 40% (6/15; 4 cases of objective evidence of resolution of intra-amniotic inflammation and 5 cases of delivery after 34 weeks of gestation).

CONCLUSION

The prevalence of intraamniotic inflammation in patients who presented with a threatened midtrimester miscarriage was 88% (15/17), and, in most cases, microorganisms could not be detected. Antibiotic treatment, administered to patients with intraamniotic inflammation, was associated with either objective resolution of intraamniotic inflammation or delivery after 34 weeks of gestation in 40% (6/15) of the cases.

Risk of spontaneous abortion after antibiotic therapy for chronic endometritis before in vitro fertilization and intracytoplasmic sperm injection stimulation

OBJECTIVE

To investigate whether cured chronic endometritis (CE) from antibiotic treatment would be associated with a higher risk of spontaneous abortion in the following in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) treatment.

DESIGN

Prospective cohort study.

SETTING

Tertiary reproductive medicine center.

PATIENT(S)

Patients with infertility who underwent a routine hysteroscopy underwent an IVF/ICSI stimulation between January 1, 2019, and December 31, 2020. Women with CE (N = 338) underwent antibiotic therapy, and the assisted reproductive outcomes were then compared with women without CE (N = 7,962).

INTERVENTION(S)

Chronic endometritis was diagnosed through hysteroscopy and confirmed by histology and immunohistochemistry for CD138.

MAIN OUTCOME MEASURE(S)

Spontaneous abortion rate after the initial embryo transfer.

RESULT(S)

A total of 7,218 patients underwent embryo transfer, with 330 in the cured CE group and 6,888 in the non-CE group. Women with cured CE had a higher rate of spontaneous abortion than did those without CE (11.8% vs. 9.2%; crude odds ratio [OR], 1.32 [0.94, 1.86]), and this difference was statistically significant after adjusting for confounding variables (adjusted OR, 1.49 [1.01, 2.19]). The live birth rate was 43.9% in the cured CE group and 50.5% in the non-CE group (crude OR, 0.77 [0.62, 0.96]; adjusted OR, 0.73 [0.59, 0.92]). The incidence of clinical pregnancy did not differ significantly between the 2 groups (56.1% vs. 60.0%; crude OR, 0.85 [0.68, 1.06]; adjusted OR, 0.83 [0.66, 1.03]). Sensitivity analyses stratified by initial fresh- or frozen-thawed embryo transfer cycles resulted in similar results.

CONCLUSION(S)

Chronic endometritis cured with antibiotic therapy was associated with an increased risk of spontaneous abortion among women undergoing IVF/ICSI treatment. The interpretation of the findings is limited by a potential confounding bias.

Evaluation of endometrial receptivity and implantation failure

PURPOSE OF REVIEW

To succinctly review the basic mechanisms of implantation and luteal phase endometrial differentiation, the etiologies of impaired endometrial function and receptivity, and the current methods that exist to evaluate and treat impaired endometrial receptivity.

RECENT FINDINGS

Human embryo implantation requires bidirectional communication between blastocyst and a receptive endometrium. Etiologies of impaired endometrial receptivity are varied. Some of these include delayed endometrial maturation, structural abnormalities, inflammation, and progesterone resistance. Current methods to evaluate endometrial receptivity include ultrasonography, hysteroscopy, and endometrial biopsy. Treatments are limited, but include operative hysteroscopy, treatment of endometriosis, and personalized timing of embryo transfer.

SUMMARY

Although some mechanisms of impaired endometrial receptivity are well understood, treatment options remain limited. Future efforts should be directed towards developing interventions targeted towards the known mediators of impaired endometrial receptivity.

Fetal‐placental antigens and the maternal immune system: Reproductive immunology comes of age

Reproductive physiology and immunology as scientific disciplines each have rich, largely independent histories. The physicians and philosophers of ancient Greece made remarkable observations and inferences to explain regeneration as well as illness and immunity. The scientific enlightenment of the renaissance and the technological advances of the past century have led to the explosion of knowledge that we are experiencing today. Breakthroughs in transplantation, immunology, and reproduction eventually culminated with Medawar’s discovery of acquired immunological tolerance, which helped to explain the transplantation success and failure. Medawar’s musings also keenly pointed out that the fetus apparently breaks these newly discovered rules, and with this, the field of reproductive immunology was launched. As a result of having stemmed from transplantation immunology, scientist still analogizes the fetus to a successful allograft. Although we now know of the fundamental differences between the two, this analogy remains a useful tool to understand how the fetus thrives despite its immunological disparity with the mother. Here, we review the history of reproductive immunology, and how major and minor histocompatibility antigens, blood group antigens, and tissue‐specific “self” antigens from the fetus and transplanted organs parallel and differ.

Delayed Antiviral Immune Responses in Severe Acute Respiratory Syndrome Coronavirus Infected Pregnant Mice

Sex differences in immune responses had been reported to correlate with different symptoms and mortality in the disease course of coronavirus disease 2019 (COVID-19). However, whether severe acute respiratory syndrome coronavirus (SARS-CoV-2) infection interferes with females’ fertility and causes different symptoms among pregnant and non-pregnant females remains unknown. Here, we examined the differences in viral loads, SARS-CoV-2-specific antibody titers, proinflammatory cytokines, and levels of T cell activation after SARS-CoV-2 sub-lethal infection between pregnant and non-pregnant human Angiotensin-Converting Enzyme II (ACE2) transgenic mouse models. Both mice showed elevated levels of viral loads in the lung at 4 days post-infection (dpi). However, viral loads in the pregnant group remained elevated at 7 dpi while decreased in the non-pregnant group. Consistent with viral loads, increased production of proinflammatory cytokines was detected from the pregnant group, and the IgM or SARS-CoV-2-specific IgG antibody in serum of pregnant mice featured delayed elevation compared with non-pregnant mice. Moreover, by accessing kinetics of activation marker expression of peripheral T cells after infection, a lower level of CD8+ T cell activation was observed in pregnant mice, further demonstrating the difference of immune-response between pregnant and non-pregnant mice. Although vertical transmission did not occur as SARS-CoV-2 RNA was absent in the uterus and fetus from the infected pregnant mice, a lower pregnancy rate was observed when the mice were infected before embryo implantation after mating, indicating that SARS-CoV-2 infection may interfere with mice’s fertility at a specific time window. In summary, pregnant mice bear a weaker ability to eliminate the SARS-CoV-2 virus than non-pregnant mice, which was correlated with lower levels of antibody production and T cell activation.

Hysteroscopic findings in chronic endometritis

Chronic endometritis (CE) is a subtle pathology. Despite being difficult to detect and probably underdiagnosed, it has great clinical relevance, representing as it does a reversible cause of infertility. Nowadays, histological examination with identification of endometrial stromal plasma cells is considered the gold standard for diagnosis. Diagnostic difficulties persist, however, as a result of the technical limitations of this method and the lack of standardized histological diagnostic criteria. Hysteroscopy has been proposed as an aid for CE diagnosis. The method works by detecting signs of inflammation (focal or diffuse hyperemia, stromal edema, presence of micropolyps and the typical strawberry aspect) on the endometrial surface. Yet, the jury is still out on how reliable this technique is. Hysteroscopy displays a high sensitivity (over 86% and up to 100%) and high negative predictive value (over 92% and up to 100%) in the diagnosis of CE, and it should probably be performed routinely in the assessment of patients with unexplained infertility, repeated implantation failure and repeated pregnancy loss; however, since values in the literature regarding specificity are conflicting, in cases of suspected CE, hysteroscopy may be combined with histological examination, which remains the gold standard to confirm CE. Considering that histopathological evaluation probably underdiagnoses CE, and that hysteroscopy tends to overdiagnose, further studies are needed to determine which technique (or combination of techniques) has greater value for patients.

The identification of endometrial immune cell densities and clustering analysis in the mid-luteal phase as predictor for pregnancy outcomes after IVF-ET treatment

Changes in endometrial immune cell density has been reported to be associated with reproductive failure. The prognostic value of endometrial immune cell density measurement remains uncertain. We aimed to investigate the prognostic value of endometrial immune cells measurement on pregnancy outcome after IVF in women. In this prospective study, one hundred twenty-eight women underwent endometrial sampling in a natural cycle preceding single frozen-thawed embryo transfer (ET). Endometrial biopsy was obtained precisely 7 days after luteinizing hormone surge (LH + 7). Multiplex immunohistochemical method was employed to simultaneously stain the endometrium samples with a panel of human antibodies against CD56 for uterine natural killer (uNK) cells, CD3 and CD8 for T cell, CD3 for pan T cells and CD68 for macrophages. The density of the various immune cells and the clustering levels between them were measured. ET was performed at the blastocyst stage. Women who did not conceive had a significantly higher density of uNK cells and higher clustering level between uNK cells-and-macrophages than women who did conceive. In accordance, the prognostic value of uNK measurement on pregnancy outcome was significantly improved when combined with uNK-to-macrophage clustering analysis simultaneously. Taken together, our results suggested that uNK cells density and clustering level between uNK cells-and macrophages may be a promising predictor for successful implantation after IVF-ET.

IFN-τ Attenuates LPS-Induced Endometritis by Restraining HMGB1/NF-κB Activation in bEECs

Endometritis is a common inflammatory disease in uterine tissues that leads to animal infertility. Among the causes, Escherichia coli infection is one of the main reasons. Interferon-tau (IFN-τ) is the initial pregnancy signal for ruminant embryos and can induce immune tolerance in humans and other species. However, there are scarce reports on whether IFN-τ has a regulatory effect on endometrial inflammatory damage through HMGB1-NF-κB signalling. The purpose of this study was to investigate the regulatory mechanism of IFN-τ in HMGB1-NF-κB signalling in LPS-induced endometritis. ELISA and qPCR were used to detect the expression of LPS-induced pro-inflammatory cytokines in bovine endometrial epithelial cells (bEECs or BEND) under IFN-τ intervention, and the levels of HMGB1, p-IKK and p-p65 were detected by Western blotting. The nuclear translocation of NF-κB p65 was determined through immunofluorescence. In addition, bEECs were transfected with si-HMGB1 to elucidate the key role of HMGB1 and IFN-τ in the endometrial inflammatory cascade. The results indicated that IFN-τ inhibits the expression of related pro-inflammatory cytokines in an inflammatory injury model of bovine endometrial epithelial cells induced by LPS. Furthermore, experiments have proven that IFN-τ has protective effects on E. coli endotoxin-induced endometritis in mice in vivo. IFN-τ inhibited the HMGB1-NF-κB axis and significantly reduced the secretion of pro-inflammatory cytokines, the expression of HMGB1 protein and the levels of IKK and NF-κB p65 phosphorylation. In summary, our results showed that IFN-τ resists E. coli endotoxin-induced endometritis by attenuating HMGB1/NF-κB signalling.

Analysis of vaginal and endometrial microbiota communities in infertile women with a history of repeated implantation failure

PURPOSE

To identify specific bacterial communities in vaginal and endometrial microbiotas as biomarkers of implantation failure by comprehensively analyzing their microbiotas using next-generation sequencing.

METHODS

We investigated α- and β-diversities of vaginal and endometrial microbiotas using 16S rRNA gene sequencing and compared their profiles between 145 women with repeated implantation failure (RIF) and 21 controls who lacked the factors responsible for implantation failure with a high probability of being healthy and fertile to identify specific bacteria that induce implantation failure.

RESULTS

The endometrial microbiotas had higher α-diversities than did the vaginal microbiotas (P < .001). The microbiota profiles showed that vaginal and endometrial samples in RIF patients had significantly higher levels of 5 and 14 bacterial genera, respectively, than those in controls. Vaginal Lactobacillus rates in RIF patients were significantly lower at 76.4 ± 38.9% compared with those of the controls at 91.8 ± 22.7% (P = .018), but endometrial Lactobacillus rates did not significantly differ between the RIF patients and controls (56.2 ± 36.4% and 58.8 ± 37.0%, respectively, P = .79).

CONCLUSIONS

Impaired microbiota communities containing specific bacteria in both the endometrium and vagina were associated with implantation failure. The vaginal Lactobacillus rates, but not the endometrial, may be a biomarker for RIF.

Chronic endometritis in women with suspected retained products of conception and their reproductive outcomes

OBJECTIVE

To determine whether women who underwent operative hysteroscopy for suspected retained products of conception (rPOC) have histopathologic evidence of chronic endometritis (CE).

DESIGN

Retrospective cohort.

SETTING

Academic center.

PATIENT(S)

One hundred and eleven women who underwent operative hysteroscopy for suspected rPOC between 2016 and 2018.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Evidence of CE on histopathology and subsequent reproductive outcomes.

RESULT(S)

One hundred and eleven women with retained products of conception were included in our study of which 26 (23.4%) were diagnosed with CE. Women without CE had a higher median gravidity (1 vs. 2, p = .021) and a higher median number of prior pregnancy losses (1 vs. 2 prior losses, p = .005) compared to those with CE. Subsequent pregnancy data were available for 63 women. There was no difference in the subsequent pregnancy rate (61.5 vs. 54%, p = .626) between those with and without CE. Once pregnant, miscarriage (37.5 vs. 25.9%, p = .524) and live birth rates (50 vs. 44.4%, p = .782) were similar between the groups. Women with CE received antibiotics 57.7% of the time, the most common of which was doxycycline (46.6%). Of the women with CE who received antibiotics (n = 10), 8 became pregnant, and 4 of whom went on to have a live birth.

CONCLUSION(S)

Nearly 1 in 4 women undergoing hysteroscopy for rPOC was incidentally diagnosed with CE. It is not clear whether CE is a causative agent for retained products or a response to the pregnancy loss. In this cohort, a diagnosis of CE did not negatively impact subsequent reproductive outcomes.

Impact of chronic endometritis in infertility: a SWOT analysis

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

Normalization of endometrial histopathology and endometrial NK cells concentration predict successful pregnancy in repeated implantation failure

OBJECTIVE

The primary objective was to establish the endometrial predictors of clinical pregnancy in a population of repeated implantation failure with oocyte donation after specific endometrial treatment. The secondary one was to evaluate reproduction outcomes in terms of Implantation rate (IR), Clinical pregnancy (CP), Live birth delivery rate (LBDR) and Prematurity, in relation to normalization or no-normalization of the predictors.

METHODS

66 patients were assigned to the study. We ran a Pipelle endometrial biopsy to investigate the endometrium lymphocyte population by Flow Cytometry and abnormal/normal patterns by histopathology in pre/post-treatment. We employed the binary logistic regression model to identify the predictors for CP. For the secondary objective, we assessed the clinical outcomes in function to the normalization or no normalization in post-treatment.

RESULTS

Endometrial histopathology and endometrial NK cell counts resulted in CP predictors (Wald chi2 test (p=0.044 and 0.001)), respectively. We had a higher IR, CP and LBDR when both predictors were normalized in comparison with no normalization (p<0.001). There was a high percentage of prematurity in both normalized vs. non-normalized groups (34.4% (11/32) and 71.43% (5/7), respectively) without significant differences.

CONCLUSION

Endometrial histopathology and endometrial NK cell counts showed that they are valid predictors of pregnancy outcome in repeated implantation failure after treatment. In post-treatment, the pregnancy outcomes were significantly higher in the presence of both normalized predictors. Pregnancy rates were zero in the no-normalization of both predictors. There was a high percentage of prematurity in both groups.

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

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

Pregnancy outcomes of the first thawing cycle in "freeze-all" strategy of infertility patients with fever during oocyte recruitment: a matched-pair study

Background:

It is currently unknown whether patients with a fever after controlled ovulation during egg retrieval could increase the risk of pelvic infection or not, and fever itself may affect endometrial receptivity or embryo quality with poor pregnancy outcomes. The aim of this study was to analyze the outcomes of patients with fever during oocyte retrieval after the first frozen-thawed embryo transfer (FET) cycle.

Methods:

This was a 1:3 retrospective paired study matched for age. In this study, 58 infertility patients (Group 1) had a fever during the control ovulation, and the time of the oocyte retrieval was within 72 hours, they underwent ovum pick up and whole embryo freezing (“freeze-all” strategy). The control subjects (Group 2) are 174 patients matched for age who underwent whole embryo freezing for other reasons. The baseline characteristics, clinical data of ovarian stimulation, and outcomes, such as the clinical pregnancy rate, ongoing clinical pregnancy rate were compared between the two groups in the subsequent FET cycle.

Results:

All patients had no pelvic inflammatory disease after oocyte retrieval. Anti-Mullerian hormone (AMH) levels (4.2 vs. 2.2, P <0.001) were higher in group 2, and the number of oocytes retrieved, and fertilization rate were lower in group 1 (P < 0.001), but the endometrial thickness, the number of embryo transfers, and the type of luteal support supplementation were similar between the two groups. Regarding pregnancy outcomes in the subsequent FET cycle, the implantation rate, clinical pregnancy rate, early spontaneous rate, ectopic pregnancy rate, and ongoing pregnancy rate were all not significantly different. Further regression analyses showed that the clinical pregnancy rate and ongoing pregnancy rate were also not significantly different.

Conclusions:

Transvaginal ultrasound-guided follicular puncture for oocyte retrieval is a safe and minimally invasive method for patients with fever. Moreover, the fever had almost no effect on embryo quality.

Beyond Uterine Natural Killer Cell Numbers in Unexplained Recurrent Pregnancy Loss: Combined Analysis of CD45, CD56, CD16, CD57, and CD138

Changes in the number and cytotoxic potential of uterine Natural Killer (uNK) cells have been associated with reduced fertility. To provide a better characterization of immunophenotypes in the endometrium of women with uRPL (unexplained recurrent pregnancy loss), we examined the applicability of a set of five immune cell markers. The concentration (cells/mm²) of CD45⁺ leukocytes, CD56⁺ uNK cells, and CD138⁺ plasma cells as well as of CD16⁺ and CD57⁺ cells, which indicate high cytotoxic uNK cells, were assessed by immunohistochemistry in endometrial biopsies from 61 uRPL patients and 10 controls. Control fertile endometria presented 90-300 CD56⁺ uNK cells/mm². uRPL cases were classified in subgroups of low (uRPL-CD56^low < 90 cells/mm²), normal (uRPL-CD56^normal 90-300 cells/mm²), and high uNK cell counts (uRPL-CD56^high > 300 cells/mm²). Some cases from the uRPL-CD56^low and uRPL-CD56^normal subgroups showed elevated proportions of cytotoxic CD16⁺ and CD57⁺ cells in relation to CD56⁺ cells. In the uRPL-CD56^high subgroup, the CD57/CD56 ratio was reduced in most samples and the CD16/CD56 ratio was unaltered. Analysis of CD138 excluded the influence of chronic endometritis on these observations. Our results reinforce a link between uRPL and a dysfunctional endometrial environment associated with distinct immune cell profiles.

In women with chronic or subclinical endometritis is hysteroscopy suitable for setting the diagnosis? A systematic review

The role of hysteroscopy in cases of chronic or subclinical endometritis remains uncertain. Reevaluating the clinical relevance of diagnostic hysteroscopic in these cases will improve the level of case in women's health worldwide. The objective of this systematic review was to assess the suitability of hysteroscopy in detecting and diagnosing female patients with chronic or subclinical endometritis, as a first-line diagnostic tool. For this systematic review, five major search engines PubMed, Embase, MEDLINE, Google Scholar, as well as ResearchGate were searched using MeSH (medical subject headings) without language or year restrictions up to November 2019. All types of scientific papers were taken into consideration, with a priority to randomized control trials enrolling women with chronic or subclinical endometritis and compared with standard diagnostic tools such as histology or immunohistochemistry, in order to ensure the efficacy of the method. Risk of bias was assessed using the recommended Cochrane Collaboration criteria. In order to gather more information and data, we have decided to include all the scientific evidence regardless of study design. Data collection and analysis were performed according to PRISMA protocol. Hysteroscopy is an important diagnostic tool in cases of endometritis when accompanied by endometrial samples assessment techniques. In cases of high suspicion endometritis facilitates greater diagnostic accuracy. Hysteroscopy facilitates also the assessment of antibiotic administration efficacy in cases of confirmed endometritis. Micropolyposis, stromal edema or congestion, diffuse or focal hyperemia are the dominant hysteroscopic features that are considered by most studies as suggestive of chronic or subclinical endometritis. The heterogeneity of the included studies presents a high risk of bias as assessed according to Cochrane Collaboration criteria. Hysteroscopy is not suitable as a first-line diagnostic tool in cases of chronic or subclinical endometritis. Further randomized controlled trials need to be conducted in order to define the role of hysteroscopy as a first-line diagnostic tool in cases of chronic or subclinical endometritis.

Identification of environmental chemicals targeting miscarriage genes and pathways using the comparative toxicogenomics database

BACKGROUND

Miscarriage is a prevalent public health issue and many events occur before women are aware of their pregnancy, complicating research design. Thus, risk factors for miscarriage are critically understudied. Our goal was to identify environmental chemicals with a high number of interactions with miscarriage genes, based on known toxicogenomic responses.

METHODS

We used miscarriage (MeSH: D000022) and chemical gene lists from the Comparative Toxicogenomics Database in human, mouse, and rat. We assessed enrichment for gene ontology biological processes among the miscarriage genes. We prioritized chemicals (n = 25) found at Superfund sites or in the blood or urine pregnant women. For chemical-disease gene sets of sufficient size (n = 13 chemicals, n = 20 comparisons), chi-squared enrichment tests and proportional reporting ratios (PRR) were calculated. We cross-validated enrichment results.

RESULTS

Miscarriage was annotated with 121 genes and overrepresented in inflammatory response (q = 0.001), collagen metabolic process (q = 1 × 10-13), cell death (q = 0.02), and vasculature development (q = 0.005) pathways. The number of unique genes annotated to a chemical ranged from 2 (bromacil) to 5607 (atrazine). In humans, all chemicals tested were highly enriched for miscarriage gene overlap (all p < 0.001; parathion PRR = 7, cadmium PRR = 6.5, lead PRR = 3.9, arsenic PRR = 3.5, atrazine PRR = 2.8). In mice, highest enrichment (p < 0.001) was observed for naphthalene (PRR = 16.1), cadmium (PRR = 12.8), arsenic (PRR = 11.6), and carbon tetrachloride (PRR = 7.7). In rats, we observed highest enrichment (p < 0.001) for cadmium (PRR = 8.7), carbon tetrachloride (PRR = 8.3), and dieldrin (PRR = 5.3). Our findings were robust to 1000 permutations each of variable gene set sizes.

CONCLUSION

We observed chemical gene sets (parathion, cadmium, naphthalene, carbon tetrachloride, arsenic, lead, dieldrin, and atrazine) were highly enriched for miscarriage genes. Exposures to chemicals linked to miscarriage, and thus linked to decreased probability of live birth, may limit the inclusion of fetuses susceptible to adverse birth outcomes in epidemiology studies. Our findings have critical public health implications for successful pregnancies and the interpretation of adverse impacts of environmental chemical exposures on pregnancy.

The first glimpse of the endometrial microbiota in early pregnancy

Investigation of the microbial community in the female reproductive tract with the use of sequencing techniques has revealed that endometrial samples obtained through a transvaginal catheter are dominated by Lactobacillus species. Dysbiotic changes in the endometrial microbiota may be associated with implantation failure or early spontaneous abortion in patients who undergo assisted reproductive technology treatment. Whether or not there is an endometrial microbiota in early pregnancy is unknown. Herein we describe, the human endometrial microbiota in a patient who subsequently had an 8th week spontaneous clinical miscarriage with euploid embryos in the next cycle and, for the first time, during a successful pregnancy in which the endometrial fluid was sampled at 4 weeks of gestation. The microbial profile found on the endometrial sample before the spontaneous abortion had higher bacterial diversity and lower Lactobacillus abundance than the endometrial fluid from the healthy pregnancy. Functional metagenomics detected different Lactobacillus species between the 2 samples. Lactobacillus crispatus was present in the endometrium before the spontaneous abortion, as were other bacteria involved in dysbiosis, which had an unstable functional pattern characterized by transposases and insertion elements. Lactobacillus iners was the most prevalent microbe found in the endometrium during early pregnancy; its presence was associated with defense mechanisms and basal functions. These novel observations prompt future investigations to understand the potential implications of microbiology on healthy and pathologic human pregnancy.

Differential Composition of Vaginal Microbiome, but Not of Seminal Microbiome, Is Associated With Successful Intrauterine Insemination in Couples With Idiopathic Infertility: A Prospective Observational Study

Background

Vaginal and seminal microbiomes have gained increasing interest for their involvement in reproductive health and fertility. However, their role in reproductive outcome is not fully understood yet. In this study, we aimed to correlate the vaginal and the seminal microbiome of 23 couples with idiopathic infertility to the clinical pregnancy rate after intrauterine insemination (IUI).

Methods

Vaginal swabs and seminal fluids were collected on the day of IUI procedure and analyzed through polymerase chain reaction amplification of variable regions 3 and 4 (V3–V4) of 16S ribosomal ribonucleic acid genes and Illumina MiSeq sequencing. The taxonomic data were then correlated to IUI success.

Results

Idiopathic infertile women showed a different average composition of vaginal microbiome compared with control sequences, whereas for seminal counterpart no relevant differences were observed. Furthermore, among idiopathic infertile women, different patterns of Lactobacillus species dominations were observed, with a predominance either of Lactobacillus crispatus, a marker of a healthy vaginal ecosystem, or of Lactobacillus iners and Lactobacillus gasseri, associated with a more dysbiosis-prone environment. More important, considering all investigated variables, vaginal L crispatus domination was the only factor strongly associated to IUI success (P = .0002).

Conclusions

Our results strengthen the potential role of L crispatus in promoting a favorable environment for pregnancy and suggest that microbiome characterization could be useful, together with standard clinical and laboratory assessments, in the pre-IUI evaluation of infertile couples.

Chronic Endometritis: Old Problem, Novel Insights and Future Challenges

Chronic endometritis (CE) is a poorly investigated pathology which has been related to adverse reproductive outcomes, such as implantation failure and recurrent miscarriage. In this paper, we aim to provide an overview of diagnosis, etiology, pathophysiology and treatment of CE, its impact on endometrial microenvironment and its association with infertility. We present a narrative review of the current literatures, synthesizing the findings retrieved from searches of computerized databases. CE is more prevalent in infertile patients. Effective antibiotic treatment of CE seems to improve the pregnancy and live birth rate in patients with unexplained recurrent pregnancy loss (RPL), and increase ongoing pregnancy rate in patients with recurrent implantation failure. In order to increase the diagnostic accuracy, immunohistochemistry is recommended besides the conventional histology. In addition, hysteroscopy could be considered as gold standard tool for diagnosis, considering its high correlation with histological findings. CE, as the chronic inflammation of endometrium, is usually asymptomatic and probably underestimated. Interaction of bacteria with endometrial microenvironment promotes changes in leukocyte population, cytokine production and growth factors which support its negative impact on endometrial receptivity. Nevertheless, standardization of the criteria for histopathological diagnosis and immunohistochemistry technique needs to be defined.

The association between vaginal bacterial composition and miscarriage: a nested case-control study

Objective

To characterise vaginal bacterial composition in early pregnancy and investigate its relationship with first and second trimester miscarriages.

Design

Nested case–control study.

Setting

Queen Charlotte’s and Chelsea Hospital, Imperial College Healthcare NHS Trust, London.

Population

161 pregnancies: 64 resulting in first trimester miscarriage, 14 in second trimester miscarriage and 83 term pregnancies.

Methods

Prospective profiling and comparison of vaginal bacteria composition using 16S rRNA gene‐based metataxonomics from 5 weeks’ gestation in pregnancies ending in miscarriage or uncomplicated term deliveries matched for age, gestation and body mass index.

Main outcome measures

Relative vaginal bacteria abundance, diversity and richness. Pregnancy outcomes defined as first or second trimester miscarriage, or uncomplicated term delivery.

Results

First trimester miscarriage associated with reduced prevalence of Lactobacillus spp.‐dominated vaginal microbiota classified using hierarchical clustering analysis (65.6 versus 87.7%; P = 0.005), higher alpha diversity (mean Inverse Simpson Index 2.5 [95% confidence interval 1.8–3.0] versus 1.5 [1.3–1.7], P = 0.003) and higher richness 25.1 (18.5–31.7) versus 16.7 (13.4–20), P = 0.017), compared with viable pregnancies. This was independent of vaginal bleeding and observable before first trimester miscarriage diagnosis (P = 0.015). Incomplete/complete miscarriage associated with higher proportions of Lactobacillus spp.‐depleted communities compared with missed miscarriage. Early pregnancy vaginal bacterial stability was similar between miscarriage and term pregnancies.

Conclusions

These findings associate the bacterial component of vaginal microbiota with first trimester miscarriage and indicate suboptimal community composition is established in early pregnancy. While further studies are required to elucidate the mechanism, vaginal bacterial composition may represent a modifiable risk factor for first trimester miscarriage.

Tweetable abstract

Vaginal bacterial composition in first trimester miscarriage is associated with reduced Lactobacillus spp. abundance and is independent of vaginal bleeding.

Vaginal bacterial composition in first trimester miscarriage is associated with reduced Lactobacillus spp. abundance and is independent of vaginal bleeding.

Confirmation of chronic endometritis in repeated implantation failure and success outcome in IVF-ET after intrauterine delivery of the combined administration of antibiotic and dexamethasone

PROBLEM

The aim of this prospective study was to investigate the prevalence of chronic endometritis (CE) in repeated implantation failure (RIF) patients and to determine whether intrauterine delivery of the combined administration of antibiotic and dexamethasone improves the clinical pregnancy outcome.

METHOD OF STUDY

The combination of hysteroscopy and histology was used to diagnose CE in the patients with RIF, and the diagnosed patients were treated with the intrauterine delivery of the combined antibiotic and dexamethasone therapy. The prevalence of CE in the RIF patients was recorded, and the therapeutic effect was also evaluated in the first IVF-ET cycle.

RESULTS

In a total number of 298 patients with RIF, 109 cases (36.58%) were diagnosed as CE. Intrauterine infusion treatment resulted in CE resolution in 77.98% of patients. After the treatment, 85 cases with no signs of CE (Group 2) had a significantly higher implantation rate (31.33%) and clinical pregnancy rate (51.76%) as compared with both 126 cases without CE diagnosis (Group 1; 16.30% and 30.15%, respectively) and 24 cases with persistence of CE (Group 3; 14.89% and 25.00%, respectively). The live birth rate in the first IVF-ET cycle following treatment in Group 2 was significantly higher than that of both Group 1 and Group 3 (all P < .05).

CONCLUSION

Chronic endometritis is highly prevalent in patients with RIF. To the best of our knowledge, we for the first time reported that intrauterine delivery of the combined administration of antibiotic and dexamethasone as a treatment option of CE could achieve expected therapeutic effects and successful pregnancy outcomes.

Association of pelvic inflammatory disease (PID) with ectopic pregnancy and preterm labor in Taiwan: A nationwide population-based retrospective cohort study

Background

Pelvic inflammatory disease (PID) is an infectious disease that causes tubal occlusion and other pelvic and abdominal adhesions. The incidence of pelvic inflammatory disease (PID) has increased due to the sexually active status of the young population. This leads to a more serious problem and a larger effect than previously observed. However, there have been few studies on this topic in Asian populations.

Aim

We aimed to evaluate the risk of preterm labor and/or ectopic pregnancy in Taiwanese women following PID.

Design

Using the Taiwan National Health Insurance Database, we designed a retrospective cohort study that included 12- to 55-year-old pregnant women between 2000 and 2010. We selected a 1:3 age-matched control group of non-PID women. The endpoint was any episode of preterm labor or ectopic pregnancy; otherwise, the patients were tracked until 31 December 2010.

Methods

The risk factors for preterm labor or ectopic pregnancy were explored. For cases included from the index date until the end of 2010, we analyzed the risk of incident preterm labor or ectopic pregnancy. With the use of a multivariate Cox proportional hazard regression analysis, we calculated the hazard ratio (HR) with a 95% CI and compared it with that of the control group.

Results

This study examined 30,450 patients with PID and 91,350 controls. During the follow-up period, patients in the PID group were more likely to develop preterm labor or ectopic pregnancy than patients in the control group. The cumulative incidence rates for developing preterm labor were 1.84% (561/30,450 individuals) in patients with PID and 1.63% (1492/91,350 individuals) in patients without PID. On the other hand, the cumulative incidence rate for developing ectopic pregnancy in patients with PID was 0.05% (14/30,450 individuals) but was only 0.04% (33/91,350 individuals) in patients without PID. Compared with those without PID, the patients with PID had a 1.864 times (P<0.001) higher risk of developing preterm labor and a 2.121 times (P = 0.003) higher risk of developing ectopic pregnancy.

Conclusion

Our study provided evidence of an increased risk of preterm labor or ectopic pregnancy in PID patients.

Does the endometrial cavity have a molecular microbial signature?

Recent molecular studies concluded that the endometrium has a resident microbiota dominated by Lactobacillus spp. and is therefore similar to that of the vagina. These findings were largely derived from endometrial samples obtained through a transcervical catheter and thus prone to contamination. Herein, we investigated the molecular microbial profiles of mid-endometrial samples obtained through hysterectomy and compared them with those of the cervix, vagina, rectum, oral cavity, and controls for background DNA contamination. Microbial profiles were examined through 16S rRNA gene qPCR and sequencing. Universal bacterial qPCR of total 16S rDNA revealed a bacterial load exceeding that of background DNA controls in the endometrium of 60% (15/25) of the study subjects. Bacterial profiles of the endometrium differed from those of the oral cavity, rectum, vagina, and background DNA controls, but not of the cervix. The bacterial profiles of the endometrium and cervix were dominated by Acinetobacter, Pseudomonas, Cloacibacterium, and Comamonadaceae. Both 16S rRNA gene sequencing and Lactobacillus species-specific (L. iners & L crispatus) qPCR showed that Lactobacillus was rare in the endometrium. In conclusion, if there is a microbiota in the middle endometrium, it is not dominated by Lactobacillus as was previously concluded, yet further investigation using culture and microscopy is necessary.

Allogeneic murine pregnancy models for assessing the developmental effects of immune-stimulating antibodies: Challenges in reproducibility

Literature suggests that murine allogeneic pregnancy models are an alternative approach for evaluating the developmental toxicity of immune-stimulating agents. In this study, multiple syngeneic and allogeneic murine pregnancy models were used to assess the potential embryo-fetal effects of four different murine antibodies (IgG₁ or IgG₂ ) that activate the immune system by binding to T-cell receptors (PD-L1, LAG-3, and GITR). The pregnancy models were generated by within and between matings of five different inbred strains of mice (CBA/CaJ, DBA/2J, BALB/c, C57BL/6, and CBA/J). The antibodies were administered every 2-3 days by intraperitoneal injection (n = 12-29/group) during gestation days 6 to 14. There were no differences in embryo-fetal endpoints between the allogeneic and syngeneic pregnancies. Additionally, treatment with the antibodies had no effect on mean postimplantation loss in either the syngeneic or allogeneic pregnancies despite confirmation of pharmacologically-relevant systemic exposures. These results suggest that allogeneic murine pregnancy models need further validation and testing before they can be reliably used as an alternative approach for assessing the developmental effects of agents that stimulate the immune system.

Review: Chronic endometritis and its effect on reproduction

AIM

Chronic endometritis (CE) is a disease of continuous and subtle inflammation characterized by the infiltration of plasma cells in the endometrial stromal area. Although the clinical significance of CE has been thought in clinical practice for a long time because it is either asymptomatic or presents with subtle symptoms, recent studies have shown the potential adverse effects of CE on fertility. In the present review, we focus on the concept, diagnosis, etiology, pathophysiology, diagnosis, impact on reproduction and treatment for it to understand CE.

METHODS

The published articles were reviewed.

RESULTS

The prevalence of CE has been found to be 2.8-56.8% in infertile women, 14-67.5% in women with recurrent implantation failure (RIF), and 9.3-67.6% in women with recurrent pregnancy loss. Microorganisms are thought to be a main cause of CE, since antibiotic treatment has been reported to be an effective therapy for CE. Common bacteria are frequently detected in the uterine cavity of CE patients by microbial culture. In CE endometrium, the prevalence of immune cells and decidualization has been reported to be modified, and these modifications are thought to adversely affect fertility. The gold standard for the diagnosis of CE is the histological detection of plasma cells in the stromal area of the endometrium in endometrial specimens, although universally accepted criteria for the diagnosis of CE have not been determined. The treatment currently thought to be most effective for the recovery of fertility in CE is administration of oral antibiotics. Patients whose CE has been cured have been reported to have a higher ongoing pregnancy rate, clinical pregnancy rate, and implantation rate compared with patients with persistent CE.

CONCLUSION

CE greatly affects implantation and impairs fertility. Antibiotic administration is an effective therapeutic option. Pregnancy rate in in vitro fertilization is improved when CE is cured by antibiotic.

How uterine microbiota might be responsible for a receptive, fertile endometrium

BACKGROUND

Fertility depends on a receptive state of the endometrium, influenced by hormonal and anatomical adaptations, as well as the immune system. Local and systemic immunity is greatly influenced by microbiota. Recent discoveries of 16S rRNA in the endometrium and the ability to detect low-biomass microbiota fueled the notion that the uterus may be indeed a non-sterile compartment. To date, the concept of the 'sterile womb' focuses on in utero effects of microbiota on offspring and neonatal immunity. However, little awareness has been raised regarding the importance of uterine microbiota for endometrial physiology in reproductive health; manifested in fertility and placentation.

OBJECTIVE AND RATIONALE

Commensal colonization of the uterus has been widely discussed in the literature. The objective of this review is to outline the possible importance of this uterine colonization for a healthy, fertile uterus. We present the available evidence regarding uterine microbiota, focusing on recent findings based on 16S rRNA, and depict the possible importance of uterine colonization for a receptive endometrium. We highlight a possible role of uterine microbiota for host immunity and tissue adaptation, as well as conferring protection against pathogens. Based on knowledge of the interaction of the mucosal immune cells of the gut with the local microbiome, we want to investigate the potential implications of commensal colonization for uterine health.

SEARCH METHODS

PubMed and Google Scholar were searched for articles in English indexed from 1 January 2008 to 1 March 2018 for '16S rRNA', 'uterus' and related search terms to assess available evidence on uterine microbiome analysis. A manual search of the references within the resulting articles was performed. To investigate possible functional contributions of uterine microbiota to health, studies on microbiota of other body sites were additionally assessed.

OUTCOMES

Challenging the view of a sterile uterus is in its infancy and, to date, no conclusions on a 'core uterine microbiome' can be drawn. Nevertheless, evidence for certain microbiota and/or associated compounds in the uterus accumulates. The presence of microbiota or their constituent molecules, such as polysaccharide A of the Bacteroides fragilis capsule, go together with healthy physiological function. Lessons learned from the gut microbiome suggest that the microbiota of the uterus may potentially modulate immune cell subsets needed for implantation and have implications for tissue morphology. Microbiota can also be crucial in protection against uterine infections by defending their niche and competing with pathogens. Our review highlights the need for well-designed studies on a 'baseline' microbial state of the uterus representing the optimal starting point for implantation and subsequent placenta formation.

WIDER IMPLICATIONS

The complex interplay of processes and cells involved in healthy pregnancy is still poorly understood. The correct receptive endometrial state, including the local immune environment, is crucial not only for fertility but also placenta formation since initiation of placentation highly depends on interaction with immune cells. Implantation failure, recurrent pregnancy loss, and other pathologies of endometrium and placenta, such as pre-eclampsia, represent an increasing societal burden. More robust studies are needed to investigate uterine colonization. Based on current data, future research needs to include the uterine microbiome as a relevant factor in order to understand the players needed for healthy pregnancy.

The relation of the vaginal microbiota to early pregnancy development during in vitro fertilization treatment-A meta-analysis

An abnormal vaginal microbiota composition has been shown to lead to pre-term births, miscarriage, and problems with conceiving. Studies have suggested that dysbiosis reduces successful early pregnancy development during IVF. However, conflicting reports exist. This meta-analysis aims to answer the following question: what is the aggregated effect found by studies investigating the influence of the vaginal microbiota composition on early pregnancy rates after IVF treatment? A systematic review was performed using the Medline and EMBASE databases, using search terms for healthy vaginal microbiota, abnormal vaginal microbiota, fertility and pregnancy. The search resulted in six included articles. Of these, all six were used for further meta-analysis. The main outcome measures were the clinical pregnancy rate, determined through ultrasound proven fetal heartbeat and/or hCG results before 10 weeks gestation, in relation to the vaginal microbiota composition. We found a correlation between abnormal vaginal microbiota and lower rates of early pregnancy development after IVF treatment (OR = 0.70, 95% CI = 0.49 - 0.99). One study showed the reverse correlation. However, heterogeneity between study methodologies in various forms was found. In conclusion, women with an abnormal vaginal microbiota are roughly 1.4 times less likely to have a successful early pregnancy development after IVF treatment when compared to women with normal microbiota.

Efficient treatment of chronic endometritis through a novel approach of intrauterine antibiotic infusion: a case series

BACKGROUND

Early diagnosis and efficient management of Chronic Endometritis (CE) in patients seeking fertility treatment are two components every practitioner wishes to address. With respect to endometrial restoration, antibiotic treatment appears to perform well. However, regarding the improvement of In Vitro Fertilization (IVF) success rates, literature evidence is inconclusive, and consensus on optimal treatment has yet to be reached. This manuscript uniquely brings to literature the first report on effective employment of intrauterine antibiotic infusion to treat CE and contribute to addressing the infertility related to it.

CASE PRESENTATION

In this case series, we present 3 patients reporting numerous previous failed IVF attempts accompanied with diagnosed CE which failed to be properly treated in the past. Following initial assessment in our clinic and verification of CE findings, an oral antibiotic regime was administered based on the infectious agent detected. Re-evaluation concluded slightly improved microbiological environment in the endometrium but persisting inflammation. Antibiotic intrauterine infusion was proposed to the patients as an alternative practice. All our patients achieved a pregnancy shortly following intrauterine treatment with one patient reporting a live birth of twin babies and two patients currently reporting an ongoing pregnancy.

CONCLUSIONS

The implications of this case series contribute to medical knowledge and extend to both effective treatment of CE and subsequent management of related infertility. The current line of treatment of CE through oral antibiotic regimes highlights the need for exploring new options and calls for larger studies on the clinical implication of their use. This novel approach enabled natural conception for patients presenting with established Recurrent Implantation Failure (RIF) having undergone numerous futile IVF attempts. The clinical impact from the practitioner's perspective is considerable allowing for an alternative line of treatment that merits further investigation.