Microbiota Insights in Endometriosis

Emerging Evidence Links Microbiota Dysbiosis to Endometriosis

Key Points

Highlights:

• Growing evidence suggests that alterations in gut and reproductive tract microbiota may be associated with endometriosis.
• Microbial dysbiosis may influence immune responses, inflammation, estrogen metabolism, and lesion development.

Importance:

• Endometriosis is increasingly viewed as a systemic disease involving immune, inflammatory, hormonal, and metabolic pathways.
• Understanding how microbiota interacts with these pathways may help identify novel diagnostic biomarkers and therapeutic targets.

What's Done Here?

• This is a comprehensive narrative review synthesizing experimental, clinical, and translational studies investigating the role of microbiota in endometriosis.
• The review examines evidence related to gut microbiota, reproductive tract microbiota, and peritoneal microbial environments, as well as their interactions with immune regulation, inflammatory signaling, and estrogen metabolism.
• Mechanistic pathways involving immune dysfunction, cytokine signaling, microbial metabolites, and hormonal regulation are also discussed.

Key Points:

• Several studies report altered gut microbiota composition in women with endometriosis, including shifts in bacterial diversity and abundance.
• Dysbiosis may influence immune responses and inflammatory signaling, potentially promoting lesion establishment and persistence.
• Microbiota may also affect estrogen metabolism through the estrobolome, potentially influencing disease progression.
• Experimental models suggest that microbial changes can modify inflammatory and immune pathways relevant to endometriosis.
• Interactions between microbiota and immune cells, cytokine networks, and hormonal signaling may contribute to disease development.

Strength and Limitations:

• Strengths are the comprehensive synthesis of experimental and clinical evidence and the integration of microbiome, immunologic, and hormonal perspectives in endometriosis research.
• Limitations are the heterogeneity of existing studies, small sample sizes in many microbiome analyses, and the predominance of observational and experimental data that do not establish causality.

From the Editor-in-Chief – EndoNews

"Interest in the role of the microbiome in endometriosis has expanded rapidly over the past decade, reflecting a broader recognition that many chronic diseases are influenced not only by local tissue factors but also by systemic interactions involving immunity, metabolism, and host–microbial ecosystems. The review by Parpex and colleagues synthesizes emerging evidence suggesting that alterations in gut and reproductive tract microbial communities may intersect with inflammatory, immune, and hormonal pathways relevant to endometriosis.

One concept highlighted in microbiome research is the potential influence of microbial populations on estrogen metabolism, particularly through bacterial enzymes capable of modifying circulating estrogen levels. Because endometriosis is an estrogen-dependent condition, alterations in these microbial pathways could theoretically influence disease biology. At the same time, microbiota are known to participate in immune regulation and inflammatory signaling, processes that are already recognized as central components of endometriosis pathophysiology. These intersecting mechanisms provide a biologically plausible framework through which microbial dysbiosis could contribute to disease development or persistence.

However, the interpretation of microbiome findings in endometriosis requires careful consideration. Current evidence is derived largely from small observational studies, often with heterogeneous sampling sites, sequencing techniques, and analytical methods. Differences in diet, medication exposure, hormonal therapy, and geographic background further complicate comparisons across studies. Importantly, microbial alterations identified in patients may represent secondary consequences of chronic inflammation, hormonal changes, or treatment effects, rather than primary drivers of disease.

For these reasons, the microbiome should presently be viewed as a potential contributor within a broader network of disease mechanisms, rather than as an isolated explanatory factor. Future research will need to integrate microbial data with immunologic, metabolic, and hormonal analyses in well-characterized patient cohorts. Longitudinal studies and mechanistic models will be particularly important to determine whether microbial changes precede disease development or simply reflect the altered biological environment associated with established endometriosis.

The growing attention to host–microbiome interactions nevertheless underscores an important shift in the conceptualization of endometriosis. Increasingly, the disease is being approached as a multisystem disorder involving complex biological networks, rather than solely as an ectopic endometrial lesion confined to the pelvis. Clarifying how microbial ecosystems intersect with these networks may ultimately expand our understanding of disease mechanisms and inform future diagnostic or therapeutic strategies."

Lay Summary

Alterations in the body’s microbial communities may play a role in the development and progression of endometriosis, according to a review published in the journal Microbiome. In the study, Dr. Pierre-Yves Parpex and colleagues summarized current evidence on how changes in gut and reproductive tract microbiota may interact with immune, inflammatory, and hormonal pathways involved in the disease.

Endometriosis has traditionally been viewed as a condition driven primarily by hormonal and inflammatory mechanisms. However, increasing attention has been directed toward the human microbiome, the collection of microorganisms that live in and on the body, because these microbial communities are known to influence immune regulation, metabolism, and systemic inflammation.

In their review, the authors examined experimental and clinical studies exploring the relationship between gut microbiota, reproductive tract microbiota, and endometriosis. Several investigations have reported differences in microbial composition between women with and without the disease, including alterations in bacterial diversity and the relative abundance of specific microbial groups.

These microbial changes may influence biological pathways relevant to endometriosis. For example, certain bacteria participate in the regulation of estrogen metabolism through the so-called estrobolome, a group of microbial genes capable of modifying circulating estrogen levels. Because endometriosis is an estrogen-dependent disease, changes in this microbial activity could potentially influence disease development or progression.

The review also highlights the possible interaction between microbiota and the immune system, including the regulation of inflammatory cytokines and immune cell activity. Such interactions may contribute to the chronic inflammatory environment that characterizes endometriosis.

At the same time, the authors emphasize that current evidence remains heterogeneous and largely observational. While microbiome alterations have been observed in association with endometriosis, it is not yet clear whether these changes contribute directly to disease mechanisms or arise as a consequence of the condition.

The authors conclude that future studies integrating microbiome analysis with immunologic, hormonal, and metabolic research may help clarify the role of microbial ecosystems in endometriosis and potentially open new avenues for diagnostics or therapeutic strategies.

Research Source: https://pubmed.ncbi.nlm.nih.gov/41345720/