Effect of endometriosis on the fecal bacteriota composition of mice during the acute phase of lesion formation Original paper

What Was Studied?

This study investigated the effect of endometriosis on the fecal bacteriota composition of mice during the acute phase of lesion formation. Researchers aimed to understand whether the establishment of endometriotic lesions would influence gut microbial communities, potentially contributing to systemic inflammation or metabolic disruptions associated with the disease. Uterine tissue fragments from GFP+ donor mice were transplanted into the peritoneal cavity of GFP- wild-type mice, inducing endometriotic lesions. Sham-transplanted mice served as controls. Fecal samples were collected three days before, and at 7 and 21 days after lesion induction, and analyzed through 16S rRNA gene sequencing to map changes in microbial composition.

Who Was Studied?

The study involved C57BL/6 wild-type mice as the experimental model for endometriosis. The model was established by transplanting uterine tissue fragments from GFP+ donor mice into the peritoneal cavity of GFP- recipient mice, allowing for easy visualization of endometriotic lesions. Sham-transplanted animals, which received physiological saline solution instead of tissue fragments, served as controls. The study analyzed fecal samples collected at specific time points to assess microbiota changes during the acute phase of endometriosis development.

What Were the Most Important Findings?

The study found that the induction of endometriosis did not produce significant changes in the composition of the fecal bacteriota during the acute phase of lesion formation (7 and 21 days post-transplantation). Despite the successful establishment of endometriotic lesions and typical histomorphology observed under fluorescence microscopy, alpha and beta diversity analyses showed no substantial differences between the endometriosis-induced group and sham controls. Detailed sequencing revealed a highly diverse microbial community dominated by Bacteroidales S24-7 group, Lactobacillus, Prevotellaceae UCG-001 group, and Lachnospiraceae NK4A136 group in both experimental and control mice. Notably, contrary to previous studies suggesting dysbiosis following endometriosis induction, this investigation showed microbial stability throughout the acute phase of lesion formation. The researchers speculated that gut microbiota disturbances may become apparent only in the chronic stages of the disease, reflecting long-term inflammation and tissue remodeling. Furthermore, the study emphasized that strict statistical controls, including the removal of singleton OTUs and application of false discovery rate (FDR) corrections, were applied to prevent false positives. These rigorous controls could have contributed to the observed stability of gut microbiota composition, challenging earlier reports of rapid dysbiosis post-endometriosis induction.

What Are the Greatest Implications of This Study?

The study challenges prevailing hypotheses that endometriosis immediately disrupts gut microbiota during the early phases of lesion formation. The findings suggest that intestinal dysbiosis may not occur in the acute phase but could instead be a consequence of chronic inflammation and prolonged disease progression. This insight implies that gut microbial changes observed in patients with endometriosis might reflect long-term disease dynamics rather than initial lesion establishment. These results underscore the need for longitudinal studies to distinguish between acute and chronic microbiome shifts in endometriosis. The findings also highlight the importance of standardized microbiome analysis protocols and strict statistical measures to accurately assess microbial composition in endometriosis models. Understanding the timeline of microbiome alterations in endometriosis could guide therapeutic strategies targeting microbial populations in chronic disease stages rather than acute phases.