Is there a component of "microflora imbalance" in endometriosis?

Role of microbiota in endometriosis patients is still not clarified

Key Points

Highlights:

• Recent discoveries of bacteria in the peritoneal fluid necessitate the clarification of the relationship between the microbiota of the female genital tract and endometriosis.

Importance:

• Understanding the pathogenesis of female genital tract dysbiosis, i.e. the imbalance in the microflora of women with endometriosis may lead to potential therapeutic options.

What’s done here:

• A prospective cohort study was performed on 36 women who underwent surgery for the ovarian mass.
• Eighteen women had endometriosis.
• Vaginal secretions, endometrial, peritoneal, and ovarian cyst fluids were collected during surgery.
• Next-generation sequencing of bacterial 16S rRNA was utilized for microbiome identification.

Key results:

• Specific microbiota was not identified in peritoneal and ovarian cyst fluids, regardless of the presence or absence of endometriosis.
• In terms of infectious bacteria prevalence in the vagina and the eutopic endometria, there exists a possibility for dysbiosis in endometriosis patients.

Limitations of the study:

• The small number of patients and lack of information about the previous treatment of bacterial vaginosis is a potential problem. 
• The presence of hormone therapy before surgery and the absence of information on the menstrual cycle that could affect the microbiota are also potentially important limitations.

Lay Summary

Dr. Oishi and colleagues from Ryukyus and Mie Universities, Japan, published a prospective cohort study on the microbiota of the female genital tract in the journal "Reproductive Medicine and Biology".

Recent studies have found a small number of bacteria in female peritoneal fluids and endometria, but it is unclear how this microbiota may affect human health. Also, the relationship between the microbiota of the female genital tract and endometriosis needs to be clarified. The discovery of a female genital tract dysbiosis, i.e. imbalance in the microbiota of women with endometriosis could yield potential therapeutic options.

In this prospective cohort study, 36 women underwent surgery for ovarian tumoral masses, of which 18 had endometriosis. After collection of vaginal secretions, endometrial, peritoneal, and ovarian cyst fluids during surgery, next-generation sequencing of bacterial 16S rRNA was performed for the identification of microorganisms.

No specific microbiome was identified in peritoneal and ovarian cyst fluids regardless of the presence or absence of endometriosis.

However, when cut-off values for infectious bacteria were utilized, there was a noteworthy increase of infectious species in  64.3% of vaginal, and 18.6% of ectopic endometrial specimens endometriosis patients. These infectious bacteria prevalence in the vagina and endometria raises the possibility of dysbiosis in endometriosis patients. This point necessitates further research to reveal the importance of microbiota in endometriosis etiology.

Research Source: https://pubmed.ncbi.nlm.nih.gov/35386386/