Don’t write off gut microbiota
Ramakrishna Kommagani, PhD, associate professor of pathology and immunology at Baylor College of Medicine in Houston, agreed. “Endometriosis is a complex disease, which appears to be impacted by many factors, including genetic, epigenetic, and environmental factors,” Dr. Kommagani said.
Dr. Ramakrishna Kommagani, Baylor College of Medicine Photography Services
Dr. Ramakrishna Kommagani
A key difference between his work and Dr. Kondo’s is his focus on gut microbiota, whereas the Japanese team looked at bacteria in the vagina and endometrium. But Dr. Kommagani said he thinks both could play a role. “Maybe the vaginal microbiome might have a direct impact on disease similar to what we showed on the gut,” he said.
But he said at least part of the answer to why some women develop endometriosis may have to do more with the balance of beneficial and harmful bacteria in the gut rather than because of a single family of microbes like Fusobacterium.
Most recently, by dovetailing a mouse model for inducing endometriosis in mice treated with antibiotics to deplete their gut microbiome, Dr. Kommagani’s lab expanded on its previous work: They showed that the animals developed fewer of the typical lesions seen in endometriosis than those that did not receive antibiotics before all of the mice underwent the surgical procedure used by researchers to induce endometriosis – possibly because they had no bacteria in their gut triggering the inflammatory response required for the development of endometriosis.
But after oral feedings with fecal matter from mice without endometriosis, the microbiota-depleted rodents began developing lesions typical of endometriosis, suggesting that altered gut flora from mice with endometriosis appeared to promote the disorder. Meanwhile, their microbiota-depleted counterparts who were fed fecal matter from mice without endometriosis did not develop the typical lesions.
Dr. Kommagani’s team then compared metabolites from bacteria in stool from mice with and without endometriosis and investigated the in vitro effect of these metabolites on cells from human endometriotic lesions. One of them, quinic acid, increased the proliferation of human endometriotic epithelial cells.
“Some metabolites such as fiber-derived short-chain fatty acids have beneficial effects; they inhibit the disease,” Dr. Kommagani said. “But maybe an amino acid derivative such as quinic acid, [may] promote disease, and these are generated because there is a gut dysbiosis.”
This statement hints at some of the possible therapeutic approaches for endometriosis, such as a high-fiber diet to promote healthy gut flora, or perhaps antibiotics to eradicate unhealthy bacteria. But as with other conditions that have been linked to dysbiosis, like inflammatory bowel disease, use of antibiotics is a bit like balancing on a tightrope; although antibiotics may remove harmful bacteria, their use may negatively affect the beneficial bacteria.
Clues in genetic variants
Krina Zondervan, DPhil, professor and head of the department of reproductive and genomic epidemiology at the University of Oxford (England), focuses on genomic, molecular, and epidemiologic approaches to understanding endometriosis.