Gut and reproductive tract microbiota: Insights into the pathogenesis of endometriosis (Review)

The Significance of Circulating Microbial Signatures in the Prognosis and Immune Microenvironment of Patients with Cervical Cancer

An increasing body of research indicates that the circulating microbiome plays a significant role in cancer initiation and progression and the treatment response. The genomic characteristics of circulating microorganisms may influence the tumor immune microenvironment, thereby affecting cancer progression and therapeutic outcomes. However, whether the circulating microbiome can serve as a prognostic biomarker for cervical cancer patients and its mechanistic role in the tumor immune microenvironment still requires further investigation. Univariate, Lasso, and multivariate Cox regression analyses were utilized to identify the circulating microbial signatures associated with overall survival (OS) in patients with cervical cancer. A circulating Microbial Abundance Prognostic Score (MAPS) model was constructed based on these findings. A nomogram that integrated clinical features and MAPSs was developed to predict the OS rates in patients with cervical cancer. Blood microbiome data were combined with matched tumor RNA-seq data to analyze the differences in the tumor microenvironment between high- and low-MAPS groups, elucidating the impact of the MAPS on the tumor immune microenvironment. Finally, the potential application of the circulating MAPS to predicting the efficacy of immunotherapy and chemotherapy was assessed. The MAPS predictive model, which includes 15 circulating microorganisms, has shown independent prognostic value for patients with cervical cancer. Integrating the MAPS into a nomogram improved the accuracy of the prognostic predictions. Combined microbial and gene analyses revealed potential interactions between prognostic tumor microbiomes and the tumor immune microenvironment. The drug sensitivity analysis indicated the potential of MAPS as a predictor of chemotherapy's efficacy. Our findings suggest that circulating microbial signatures hold promise as novel prognostic biomarkers and may inform personalized treatment strategies in cervical cancer. Further large-scale and multicenter studies are warranted to validate the clinical utility of the MAPS.

Early-life environmental exposures and the risk of endometriosis/adenomyosis in the NutriNet-Santé cohort

OBJECTIVE

The etiology of endometriosis is poorly known; established risk factors are limited and few environmental risk factors have been identified. We aimed to explore the associations between several perinatal and childhood environmental exposures and the risk of endometriosis/adenomyosis in women.

METHODS

This study was based on NutriNet-Santé, an ongoing web-based prospective cohort following-up several tens of thousands of French adults since 2009. The analysis included 25,251 women with health data available who completed a self-administered questionnaire on perinatal and childhood exposures in 2019. Associations with self-reported endometriosis/adenomyosis were investigated using multivariable logistic regression models, adjusted for potential confounders identified through direct acyclic graphs.

RESULTS

Among women, 1126 (4.5 %) self-reported a diagnosis of endometriosis/adenomyosis. Endometriosis/adenomyosis was positively associated with a low birth weight (<2500 g vs. ≥2500 g: adjusted odds-ratio (aOR) = 1.43, 95 % confidence interval (95 % CI) = 1.03-2.00), exposure to maternal smoking during pregnancy (aOR = 1.86, 95 % CI = 1.33-2.61), daycare attendance (aOR = 1.61, 95 % CI = 1.11-2.33), exposure to pets in childhood (both cat and dog vs. no animals: aOR = 1.23, 95 % CI = 1.08-1.41), and mold exposure in housing during childhood (aOR = 1.42, 95 % CI = 1.15-1.74). Conversely, living on a farm during childhood (aOR = 0.77, 95 % CI = 0.62-0.97) and having farmer parents (aOR = 0.72, 95 % CI = 0.54-0.97) were inversely associated with endometriosis. Maternal age at birth, birth length, prematurity, mode of delivery, or exposure to breastfeeding was not associated with endometriosis/adenomyosis.

CONCLUSION

Findings from this large population-based study among French adult women suggest associations between several perinatal and childhood exposures and endometriosis/adenomyosis. Research on early-life and childhood environments with endometriosis/adenomyosis might have important implications for the primary prevention of endometriosis and adenomyosis.

Nutrition Interventions in the Treatment of Endometriosis: A Scoping Review

BACKGROUND

Pain, poor quality of life (QOL) and gastrointestinal (GI) symptoms are commonly experienced by individuals with endometriosis. Although diet and nutrition supplements are frequently used to manage endometriosis-related symptoms, there is limited understanding of the breadth and quality of research in this field. Our aim was to undertake a scoping review of diet and nutrition supplement intervention studies in people with endometriosis, diagnosed by ultrasound or surgery.

METHODS

MEDLINE Complete, Embase, CINAHL and PsycINFO databases were searched for articles published in English from database inception to November 2024. Quality was assessed by two reviewers independently using the Joanna Briggs Institute appraisal tools. In total, 5130 publications were screened and 13 were included.

RESULTS

Among these, five evaluated the effect of diet intervention, one evaluated the effect of a combined diet-supplement intervention and seven evaluated the effect of a nutrition supplement in endometriosis. Overall, there were seven randomised controlled trials (RCTs) (n = 1 diet intervention, n = 6 nutrition supplement), two nonrandomised controlled studies (n = 1 diet intervention, n = 1 combined diet-supplement) and four uncontrolled studies (n = 3 diet intervention, n = 1 nutrition supplement). On the basis of evidence from the RCTs, the low fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) diet improved QOL and GI symptoms, whereas garlic supplements and combination trace element supplements may be beneficial for improving reduced pain symptoms related to endometriosis. The quality of most included studies was poor. Adherence to the interventions was only measured in five studies and only one diet study measured baseline diet.

CONCLUSIONS

High-quality RCTs of diet and nutrition supplement interventions are needed to progress the understanding of whether they should be integrated into the clinical management of endometriosis.

Unraveling shared and unique genetic causal relationship between gut microbiota and four types of uterine-related diseases: Bidirectional Mendelian inheritance approaches to dissect the "Gut-Uterus Axis"

BACKGROUND

The gut microbiota has emerged as a pivotal factor in the etiology of uterine-related diseases. This study aims to elucidate the genetic causal link between gut microbiota composition and these conditions, focusing on the systemic impact and uterine pathology to better understand the "Gut-Uterus Axis."

METHODS

We utilized pooled data from two different GWAS databases, including data from 209 gut microbiota traits and data from four uterus-related diseases. Bidirectional Mendelian Randomization (MR) approaches, incorporating Bayesian weighting and traditional inverse variance weighting (IVW) methods, were employed to explore causal relationships. The robustness of findings was ensured through sensitivity analyses, outlier testing, and MR-PRESSO analysis.

RESULTS

Seventeen significant associations were identified between gut microbiota traits and uterine-related diseases, suggesting potential causal links. These associations were consistent across sensitivity analyses, affirming the reliability of our results. Conversely, reverse MR analyses did not reveal statistically significant associations between uterine diseases and bacterial traits, indicating a unidirectional influence of gut microbiota on uterine health. These findings highlight the complex interplay within the "Gut-Uterus Axis."

CONCLUSION

This research establishes a causal relationship between gut microbiota and uterine diseases, advocating for targeted interventions to mitigate associated risks. It underscores the interconnectedness of gut and reproductive health, promoting a holistic approach to management and treatment within the "Gut-Uterus Axis".

The causality between gut microbiota and endometriosis: a bidirectional Mendelian randomization study

Background

Observational studies and animal experiments had suggested a potential relationship between gut microbiota abundance and pathogenesis of endometriosis (EMs), but the relevance of this relationship remains to be clarified.

Methods

We perform a two-sample bidirectional Mendelian randomization (MR) analysis to explore whether there is a causal correlation between the abundance of the gut microbiota and EMs and the direction of causality. Genome-wide association study (GWAS) data ukb-d-N80, finn-b-N14-EM, and MiBinGen were selected. Inverse variance weighted (IVW), weighted median, and MR Egger are selected for causal inference. The Cochran Q test, Egger intercept test, and leave-one-out analysis are performed for sensitivity analyses.

Results

In the primary outcome, we find that a higher abundance of class Negativicutes, genus Dialister, genus Enterorhabdus, genus Eubacterium xylanophilum group, genus Methanobrevibacter and order Selenomonadales predict a higher risk of EMs, and a higher abundance of genus Coprococcus and genus Senegalimassilia predict a lower risk of EMs. During verifiable outcomes, we find that a higher abundance of phylum Cyanobacteria, genus Ruminococcaceae UCG002, and genus Coprococcus 3 predict a higher risk of EMs, and a higher abundance of genus Flavonifracto, genus Bifidobacterium, and genus Rikenellaceae RC9 predict a lower risk of EMs. In primary reverse MR analysis, we find that EMs predict a lower abundance of the genus Eubacterium fissicatena group, genus Prevotella7, genus Butyricicoccus, family Lactobacillaceae, and a higher abundance of genus Ruminococcaceae UCG009. In verifiable reverse MR analysis, we find that EMs predict a lower abundance of the genus Ruminococcaceae UCG004 and a higher abundance of the genus Howardella.

Conclusion

Our study implies a mutual causality between gut microbiota abundance and the pathogenesis of EMs, which may provide a novel direction for EMs diagnosis, prevention, and treatment, may promote future functional or clinical analysis.

Rethinking the pathogenesis of endometriosis: Complex interactions of genomic, epigenetic, and environmental factors

AIM

Endometriosis is a complex, multifactorial disease. Recent advances in molecular biology underscore that somatic mutations within the epithelial component of the normal endometrium, alongside aberrant epigenetic alterations within endometrial stromal cells, may serve as stimulators for the proliferation of endometriotic tissue within the peritoneal cavity. Nevertheless, pivotal inquiries persist: the deterministic factors driving endometriosis development in certain women while sparing others, notwithstanding comparable experiences of retrograde menstruation. Within this review, we endeavor to synopsize the current understanding of diverse pathophysiologic mechanisms underlying the initiation and progression of endometriosis and delineate avenues for future research.

METHODS

A literature search without time restriction was conducted utilizing PubMed and Google Scholar.

RESULTS

Given that aberrant clonal expansion stemming from cancer-associated mutations is common in normal endometrial tissue, only endometrial cells harboring mutations imparting proliferative advantages may be selected for survival outside the uterus. Endometriotic cells capable of engendering metabolic plasticity and modulating mitochondrial dynamics, thereby orchestrating responses to hypoxia, oxidative stress, inflammation, hormonal stimuli, and immune surveillance, and adeptly acclimating to their harsh surroundings, stand a chance at viability.

CONCLUSION

The genesis of endometriosis appears to reflect the evolutionary principles of mutation, selection, clonal expansion, and adaptation to the environment.

Endometriosis: A Comprehensive Analysis of the Pathophysiology, Treatment, and Nutritional Aspects, and Its Repercussions on the Quality of Life of Patients

Endometriosis is a chronic proinflammatory pathology characterized by the growth of tissue similar to the endometrium outside the uterus, affecting approximately 5 to 15% of women worldwide. Suffering from endometriosis entails a complex pathophysiological process, significantly impacting the quality of life and reproductive function of affected women; therefore, it must be addressed in a personalized and comprehensive manner, as its management requires a multidisciplinary approach. This article aims to conduct a comprehensive literature review of endometriosis, not only as a pathophysiological condition but also as a significant factor impacting the social, nutritional, and mental well-being of those who experience it. Emphasis is placed on the importance of understanding and assessing the impact of the pathology to provide a better and more comprehensive approach, integrating various alternatives and strategic treatments for the factors involved in its development. The aim is to provide a complete overview of endometriosis, from its pathophysiology to its impact on the quality of life of patients, as well as a review of current treatment options, both pharmacological and alternative, in order to broaden the perspective on the pathology to improve the care of patients with this disease.

Comparative analysis of endometrial, vaginal, and gut microbiota in patients with and without adenomyosis

INTRODUCTION

Alterations in microbiota composition have been implicated in a variety of human diseases. Patients with adenomyosis present immune dysregulation leading to a persistent chronic inflammatory response. In this context, the hypothesis that alterations in the microbiota may be involved in the pathogenesis of adenomyosis, by affecting the epigenetic, immunologic, and biochemical functions of the host, has recently been postulated. The aim of the present study was to compare the microbiota composition in the vagina, endometrium, and gut of individuals with and without adenomyosis.

MATERIAL AND METHODS

Cross-sectional study including 38 adenomyosis patients and 46 controls, performed between September 2021 and October 2022 in a university hospital-based research center. The diagnosis of adenomyosis was based on sonographic criteria. Fecal, vaginal, and endometrial samples were collected. Study of the microbiota using 16S rRNA gene sequencing.

RESULTS

Patients with adenomyosis exhibited a significant reduction in the gut microbial alpha diversity compared with healthy controls (Chao1 p = 0.012, Fisher p = 0.005, Observed species p = 0.005). Beta-diversity analysis showed significant differences in the compositions of both gut and vaginal microbiota between adenomyosis patients and the control group (Adonis p-value = 0.001; R2 = 0.03 and Adonis p-value = 0.034; R2 = 0.04 respectively). Specific bacterial taxa were found to be either overrepresented (Rhodospirillales, Ruminococcus gauvreauii group, Ruminococcaceae, and Actinomyces) or underrepresented in the gut and endometrial microbiota of adenomyosis patients compared with controls. Distinct microbiota profiles were identified among patients with internal and external adenomyosis phenotypes.

CONCLUSIONS

The study revealed reduced gut microbiota diversity in adenomyosis patients, accompanied by distinct compositions in gut and vaginal microbiota compared with controls. Overrepresented or underrepresented bacterial taxa were noted in the gut and endometrial microbiota of adenomyosis patients, with variations in microbiota profiles among those with internal and external adenomyosis phenotypes. These findings suggest a potential association between microbiota and adenomyosis, indicating the need for further research to comprehensively understand the implications of these differences.

Postmenopausal endometriosis: a challenging condition beyond menopause

IMPORTANCE AND OBJECTIVE

Postmenopausal endometriosis is a complex condition that challenges the conventional belief that endometriosis resolves with menopause. Despite the cessation of menstruation, a subset of women continues to experience or develop endometriosis-related symptoms during the postmenopausal period. Thus, this review aimed to shed light on postmenopausal endometriosis, exploring its clinical features, diagnostic considerations, management approaches, and the potential impact on women's health.

METHODS

PubMed/Medline, Scopus, and Web of Science databases were used for the research, with only articles in English language, using the following terms: "postmenopausal endometriosis," "menopause," "management," "treatment," and "quality of life," from inception to 2023.

DISCUSSION AND CONCLUSION

The clinical features of postmenopausal endometriosis include persistent or recurrent pelvic pain, dyspareunia, bowel, or urinary symptoms and, occasionally, abnormal vaginal bleeding. The absence of menstrual cycles presents a diagnostic challenge, as the traditional diagnostic criteria for endometriosis rely on menstrual patterns. Visual cues may be less evident, and the symptoms often overlap with other gynecological conditions, necessitating a thorough evaluation to differentiate postmenopausal endometriosis from other potential causes. Management approaches for postmenopausal endometriosis encompass surgical intervention, hormonal therapies, pain management, and individualized care. Postmenopausal endometriosis significantly impacts the quality of life, sexual health, and long-term well-being of women. Understanding the clinical features, diagnostic challenges, and management approaches of postmenopausal endometriosis is crucial for healthcare professionals to provide effective care and to improve the quality of life of women affected by this condition.

Bacterial infection in endometriosis: a silver-lining for the development of new non-hormonal therapy?

The pathogenesis of endometriosis is a hotly debated topic, yet still cloaked in multiple layers of hypothetical theories. A recent report raises the possibility that bacterial infection, especially those of the genus Fusobacterium, may be the cause of endometriosis, at least in certain women. More importantly, the demonstration that treatment with broad-spectrum antibiotics significantly reduced the size of lesions in a mouse endometriosis model rekindles the hope for new non-hormonal treatments. The development of new therapies has been plagued by strings of unsuccessful clinical trials over the last two decades. Is this antibiotic therapy, a silver lining for the research and development of non-hormonal drugs for endometriosis?

A large-scale causal analysis of gut microbiota and endometriosis associated infertility: A Mendelian randomization study

Endometriosis is a prevalent condition with notable impacts on fertility. Recent studies have implicated gut microbiota in the development of endometriosis associated infertility (EAI). This study employs Mendelian randomization (MR) to elucidate the causal relationship between specific gut microbes and EAI. Using MR, we selected single nucleotide polymorphisms associated with 211 gut microbiota taxa from large-scale genome-wide association studies summary data. We applied statistical methods including inverse variance weighting, weighted median, and MR-Egger for analysis. Outliers were identified through the leave-one-out method. MR-Egger intercept tests were conducted to address horizontal pleiotropy, while Cochran Q and P values assessed heterogeneity. The false discovery rate method was used for multiple testing correction. Sensitivity analysis and F statistics evaluated the reliability and potential biases of our results. The inverse variance weighting method indicated a significant association of the genus Actinomyces (OR = 1.657, 95% CI: 1.187-2.312, P = .00298) with an increased risk of EAI. Conversely, genera Holdemania (OR = 0.630, 95% CI: 0.444-0.894, P = .00969) and Ruminococcaceae NK4A214 group (OR = 0.689, 95% CI: 0.481-0.999, P = .0439) appeared as protective factors. MR-PRESSO global test and MR-Egger regression indicated no significant horizontal pleiotropy (P > .05). Leave-one-out analysis confirmed the robustness of these findings. Our study provides evidence of a causal relationship between specific gut microbiome taxa and EAI. These findings offer novel insights and may guide the development of new preventive and therapeutic strategies for managing EAI.