Researchers discover a previously unknown bacterial component in kidney stone formation

(Press-News.org) In an unexpected finding, a UCLA-led team has discovered that bacteria are present inside the most common type of kidney stone, revealing a previously unrecognized component involved in their formation.

The findings, to be published in the peer-reviewed journal PNAS, point to a possible therapeutic target that could be used for prevention and treatment for the millions of people who are affected by the frequently painful condition.

“This breakthrough challenges the long‑held assumption that these stones develop solely through chemical and physical processes, and instead shows that bacteria can reside inside stones and may actively contribute to their formation,” said Dr. Kymora Scotland, an assistant professor of urology at the David Geffen School of Medicine at UCLA and the study’s co-senior author. “By uncovering this novel mechanism, the study opens the door to new therapeutic strategies that target the microbial environment of kidney stones.”

Gerard Wong, a professor in the UCLA Departments of Bioengineering, Chemistry and the California NanoSystems Institute at UCLA, served as the study’s co-author.

Kidney stones are composed of clumps of small crystals. Their prevalence has risen globally in recent years, so that today about 1 in 11 people will get them in their lifetime. Risk factors include family history, metabolic syndrome, and low fluid intake. The stones start forming when crystals grow in urine and become large enough that they can’t be washed out with normal urine flow.

There are several subsets of kidney stones and while one rare stone type is known to contain bacteria, by far the most common stone is calcium oxalate (CaOx),comprising almost 80% of kidney stone cases, which have not have been previously known to contain bacteria. While examining data from electron and florescence microscopy, the researchers unexpectedly detected live bacteria as well as layers, or biofilms, of bacteria integrated into the crystals.

“We found a new mechanism of stone formation that may help to explain why these stones are so common” Scotland said. “These results may also help to explain the connections between recurrent urinary tract infections and recurrent kidney stone formation, and provides insights on potential future treatment for these conditions.”

The findings suggest that bacteria could also be involved in other kidney stone types, she added.

The study has focused on calcium-based stones. How other less common stones form is still in question. More studies are needed to fully understand how bacteria and calcium-based kidney stones interact, the researchers conclude.

“Our multi-institutional team is currently performing studies to determine how bacteria and calcium-based kidney stones interact. We want to understand exactly what makes some patients particularly susceptible to recurrent stone formation, and what it is about these particular species of bacteria that allows them to nucleate these stones,” Scotland said.

Study co-authors are William Schmidt, Rena Yang and Ava Mousavi of UCLA;, Qian Chen and Jiahui Li of University of Illinois, Urbana-Champaign; Gerson Gonzalez Marin and Aaron Celestian of the Natural History Museum of Los Angeles; and Henry Schreiber IV, Rachael Hammann, Chloe Obernuefemann, Karla Bergeron, Aleksandra Klim, Daniel Wong, Kefu Du and Scott J. Hultgren of Washington University. Schmidt and Mousavi are also affiliated with University of Illinois, Urbana-Champagne, and Chen is affiliated with Chan Zuckerberg Biohub Chicago.

Grants from National Institutes of Health (1K08DK132486-01A1, KL2TR001882-06, R01AI143730, R01DK051406, and S10OD025017), the National Science Foundation (DMR2325840, CHE-0722519, and RaMP-2216721), a National Research Service Award (T32AI007323), Air Force Office of Scientific Research (FA9550-23-1-0609), Chan Zuckerberg Biohub Chicago, and a CNSI Voucher Award funded this research.

END