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A new study from Lawson Health Research Institute and Western University published in the journal Microbiome has found changes in the microbiome in multiple locations in the body are linked to the formation of kidney stones.

The human microbiome comprises trillions of microorganisms, including healthy bacteria. In recent years, research has begun to uncover its role in health and numerous diseases.

The research team examined the gut, urinary and salivary microbiomes in 83 patients who had kidney stones and compared them to 30 healthy controls. They found changes in all three microbiomes were linked to kidney stone formation.

“Kidney stone disease has been rising in recent years, affecting roughly 10 per cent of people,” says Dr. Jeremy Burton, Lawson Scientist and Research Chair of Human Microbiome and Probiotics at St. Joseph’s Health Care London (St. Joseph’s). “While previous research has shown a connection between the gut microbiome and kidney stones in those who have taken antibiotics, we also wanted to explore the connection to other microbiomes in the hopes we can advance understanding and potential treatments.”

Study participants included people who had formed kidney stones, had not had antibiotic exposure in the last 90 days and were having the stones removed surgically at St. Joseph’s.

“Our testing – called shotgun metagenomic sequencing – allowed us to discover which bacteria were present in the gut and the genetic capabilities of those bacteria, or how it functions. We also did a simpler sequencing of the oral and urinary samples,” explains Dr. Kait Al, lead author on the study and Postdoctoral Research Fellow at Western’s Schulich School of Medicine & Dentistry.

Kidney stones are most commonly formed from calcium oxalate, which is a waste product produced by the body. Historically, it was thought people with specific gut microbes, like one bacterium called Oxalobacter formigenes that breaks down oxalate, were less likely to form kidney stones. This study suggests there are other factors.

“It’s a more complex story. The microbes form a kind of network that’s stable and beneficial in healthy people, but in those with kidney stones, that network is broken down. They’re not producing the same vitamins and useful metabolites, not just in the gut but also in the urinary tract and oral cavity,” Dr. Al explains.

There was also evidence that those with kidney stones had been exposed to more antimicrobials, as they had more antibiotic-resistant genes.

“We found not only that those who got kidney stones had an unhealthy microbiome, including a gut microbiome that was more likely to excrete toxins to the kidneys, but also that they were antibiotic resistant,” explains Dr. Burton, also an Associate Professor in the Department of Microbiology and Immunology at Schulich Medicine & Dentistry.  

The research team says that although more research is needed, these initial findings shed light on the overall importance of a person’s microbiome and keeping it as healthy as possible, with a microbiome-friendly diet and minimal antibiotic use potentially part of the solution.

The study was funded in part through the Weston Foundation and supported by the American Urological Association.

When patients with testicular cancer undergo lymph node removal surgery there is a risk that their fertility will be affected if proper nerve sparing techniques are not used. Up to 75 per cent of men will not be able to father children if they receive the surgery without these techniques.

Lawson’s Internal Research Fund (IRF) has awarded a grant to Dr. Nicholas Power, a researcher at Lawson and urologic oncologist at London Health Sciences Centre (LHSC), who is leading a study to identify the nerves involved in fertility that are affected in lymph node removal surgery for testicular cancer.

“Sometimes patients go through a lot to be cured of testicular cancer only to be left dealing with long-term survivorship issues such as fertility. We hope to gain new insights into how fertility can be preserved after these men receive lymph node removal surgery,” says Dr. Power, who is also an assistant professor at Western University’s Schulich School of Medicine & Dentistry.

In collaboration with Schulich assistant professors Dr. Marjorie Johnson and Dr. Brian Allman, and PhD candidate Tyler Beveridge, Dr. Power published initial results in The Journal of Urology announcing their discovery of a brand new anatomic structure, the pre-hypogastric ganglion, which needs to be spared in surgery to maintain fertility. They were also able to describe the first roadmap of retroperitoneal neuroanatomy – the anatomy of nerves in the space where surgeons locate lymph nodes most commonly affected by testicular cancer that has spread.

“There has never been a definitive anatomic study of the nerves of the retroperitoneum so it was our goal to provide the first comprehensive study of the nerves as they relate directly to patients who have testicular cancer,” explains Dr. Power. “After we published the initial results we were approached by textbook authors to use our data in upcoming editions of anatomy and surgical atlases. This will help to provide insight into nerve sparing techniques for surgeons who have not been trained at high-volume centers and ultimately improve the quality of care in testicular cancer patients overall.”

Already Dr. Power has found that using this knowledge when he performs lymph node removal surgery for testicular cancer has led to a 95 per cent success rate of preserving fertility.

The IRF will go towards their research to further investigate the actual function and physiology of the retroperitoneal neuroanatomy using a pig model.

“Lawson’s IRF provides incredible support for a field of study such as ours that is not yet at the stage of applying for a large grant. Receiving the funding gives us the independence to test out novel yet important hypotheses that will then lead us to further grants,” says Dr. Power.

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Above: Dr. Nicholas Power

The IRF is designed to provide Lawson scientists and students the opportunity to obtain start-up funds for new projects with the potential to obtain larger funding, be published in a high-impact journal, or provide a clinical benefit to patients. Funding is provided by the clinical departments of London Health Sciences Centre and St. Joseph’s Health Care London, as well as the hospital foundations (London Health Sciences Foundation and St. Joseph's Health Care Foundation).