Microbiota composition and distribution along the female reproductive tract of women with endometriosis Original paper

What Was Studied?

This study investigated the microbiota composition and distribution along the female reproductive tract of women with endometriosis (EMS) compared to healthy controls. Using 16S rRNA amplicon sequencing, researchers mapped microbial communities from five distinct anatomical sites: the lower third of the vagina (CL), posterior vaginal fornix (CU), cervical mucus (CV), endometrium (ET), and peritoneal fluid (PF). The primary aim was to identify differences in microbial communities across these regions and understand how these alterations may contribute to the pathogenesis of endometriosis. A total of 36 women with confirmed pelvic endometriosis and 14 healthy controls undergoing surgery for benign gynecological conditions were included in the study.

Who Was Studied?

The study included 50 women aged 23 to 44, divided into two groups: 36 patients diagnosed with pelvic endometriosis and 14 healthy controls undergoing laparoscopic surgery for benign conditions like ovarian teratoma, serous cystadenoma, or uterine fibroids. All participants had regular menstrual cycles and had not used hormonal drugs, antibiotics, or vaginal medications within six months before sample collection. Samples were collected during the early follicular phase to minimize hormonal variability, and five distinct anatomical locations were sampled to comprehensively map microbial distribution.

What Were the Most Important Findings?

The study revealed distinct microbiota compositions along the reproductive tract in women with endometriosis compared to healthy controls. The lower reproductive tract (CL, CU) in both groups was predominantly colonized by Lactobacillus, maintaining a stable microbial community. However, microbial diversity began to shift notably at the cervical mucus (CV) in endometriosis patients, with the appearance of Veillonellaceae and an overall reduction in Lactobacillus. This shift continued upward, with dramatic changes observed in the endometrium (ET) and peritoneal fluid (PF) of endometriosis patients. In the ET, Pseudomonas, Acinetobacter, and Vagococcus emerged as dominant taxa, accompanied by a significant reduction of Lactobacillus. The peritoneal fluid samples further diverged, showing high microbial diversity, including Pseudomonas, Acinetobacter, Shewanella, Vagococcus, and Sphingobium, with minimal presence of Lactobacillus. The distinct microbial signatures in these upper reproductive sites suggest a potential role for these genera in promoting inflammation and lesion persistence in endometriosis. Importantly, Sphingobium and Pseudomonas viridiflava were consistently enriched in both the ET and PF of endometriosis patients, indicating their potential as microbial biomarkers for the disease. The findings support the hypothesis that site-specific microbial shifts contribute to the pathogenesis of endometriosis, likely through immune modulation and local inflammation.

What Are the Greatest Implications of This Study?

The study’s findings suggest that the microbiota composition along the female reproductive tract in endometriosis patients is markedly different from that of healthy controls, with key disruptions beginning in the cervical mucus and intensifying in the endometrium and peritoneal fluid. The reduction of Lactobacillus and the enrichment of pro-inflammatory taxa such as Pseudomonas, Acinetobacter, Vagococcus, Shewanella, and Sphingobium suggest these species may contribute to local immune activation, chronic inflammation, and potentially lesion maintenance in endometriosis. The identification of Sphingobium and Pseudomonas viridiflava as dominant species in upper reproductive tract samples provides a promising direction for non-invasive biomarkers for diagnosing endometriosis. Furthermore, this microbial dysbiosis may offer therapeutic targets for microbiome-modulating treatments aimed at restoring a healthy reproductive tract microbiota, potentially alleviating symptoms and reducing disease progression. This research underscores the importance of targeting microbial ecosystems in understanding and managing endometriosis.