Endometriosis affects 1 in 9 Australian women.
Management options range from over the counter pain medications, hormonal contraceptive pills or intra-uterine devices (IUD) to laparospic surgery or hysterectomy. Is it possible that the microbiome could hold some answers for women with endometriosis?
The journal:
International Journal of Molecular Sciences
The paper:
Intricate Connections between the Microbiota and Endometriosis (May 2021)
The authors:
Irene Jiang, Paul J. Yong, Catherine Allaire, and Mohamed A. Bedaiwy
How are endometriosis and the gut microbiome connected?
1. Bacterial Contamination Theory:
This theory suggests that bacteria from other parts of the body, like the gut, may travel to the reproductive tract and cause inflammation and tissue damage. An imbalance in the normal gut bacteria may make it easier for these bacteria to move to the reproductive tract.
2. Immune Activation:
The microbiota helps regulate the immune system, and an imbalance in the bacteria may lead to a constantly active immune system. This could contribute to inflammation and tissue damage in the reproductive tract, leading to endometriosis.
3. Cytokine-Impaired Gut Function:
Cytokines are proteins that help control inflammation and the immune system. An imbalance in gut bacteria may alter the production and signaling of cytokines, which could lead to impaired gut function and more inflammation throughout the body, including in the reproductive tract.
4. Altered Estrogen Metabolism and Signaling:
Estrogen is a hormone that affects endometriosis. Changes in the gut bacteria may affect how the body processes and responds to estrogen, leading to abnormal levels of the hormone and contributing to endometriosis.
5. Aberrant Progenitor and Stem-Cell Homeostasis:
Progenitor and stem cells are involved in repairing tissues. Problems with these cells have been linked to endometriosis. Changes in the bacteria in the reproductive tract may affect the environment around these cells, leading to problems with their normal functioning and contributing to endometriosis.
6. Endotoxins from the gut
Lipopolysaccharides (LPS), which are a type of endotoxin produced by some types of bacteria, may play a role in the development or progression of endometriosis. The authors suggested that LPS may contribute to inflammation and tissue damage in the reproductive tract, leading to the development of endometriosis.
7. The upper reproductive tract may also have a microbiome:
This paper suggests the existence of a microbiome in the female reproductive tract (FRT). To clarify, this different to the well established vaginal microbiome. Specifically, the upper FRT includes the uterus, fallopian tubes, and ovaries. It was previously thought that the upper FRT was a sterile environment. However, this perception has changed over the years with more research.
For example, researchers have isolated bacteria from the endometrium during hysteroscopy, confirming that the uterine environment is not sterile. In fact, up to 95% of hysterectomy samples contain bacterial DNA.
A 2016 study examined bacterial samples from endometrial fluid and vaginal aspirates of reproductive-aged women to determine the existence of a distinct microbial community to the one in the vagina. The researchers identified the existence of a distinct and stable endometrial microbiota, which suggests that the microbiota in the upper FRT may play a role in endometriosis.
Overall, there is still no consensus on the core female reproductive tract microbiome or its exact role in endometriosis. However, the growing evidence of the existence of a microbiome in the upper FRT may lead to new insights and treatments for endometriosis in the future.