Factors produced by the bacteria Oxalobacter formigenes may prevent or treat kidney stones, which can lead to chronic kidney disease, according to new research,
The mouse study, “Oxalobacter formigenes-Derived Bioactive Factors Stimulate Oxalate Transport by Intestinal Epithelial Cells,” was published in the Journal of the American Society of Nephrology.
Kidney stone disease is the second most prevalent kidney disease in the U.S. after hypertension, and has no specific therapy. Colonization by Oxalobacter formigenes, however, has been associated with a reduced risk of kidney stones.
Oxalate is a small anion produced in the intestine. Under certain conditions, the excretion of oxalate by the kidneys is accompanied by the formation of kidney stones because oxalate can bind to calcium, forming calcium-oxalate stones. For this reason, elevated levels of oxalate in the urine serve as an indicator for high kidney stone risk.
However, Oxalobacter formigenes living in the intestines use oxalate as an energy source for its survival, reducing the amount of oxalate that has to be excreted by the kidneys and, as a result, the risk of stone formation.
Researchers from the University of Chicago used human intestinal cells grown in tissue culture and in mice to better understand the role and activity of these bacteria in the regulation of oxalate levels. They observed that certain molecules produced by the bacteria stimulate oxalate transport by the human intestinal cells.
The team also identified in mice which molecular pathway is activated by the bacterial molecules to promote this transport. This pathway includes a protein transporter called SLC26A6; when inhibited, this protein could no longer participate in oxalate transport.
Oxalobacter formigenes factors promoted a notable reduction of oxalate levels in the urine by approximately 33 percent in mice.
“Probiotic bacteria have several health benefits,” Dr. Hatim Hassan, MD, PhD, the lead author of the study, said in a news release. “However, the difficulties in determining intestinal bacterial bioavailability and biosafety concerns when administering live probiotics are potential problems facing current probiotics clinical applications. Developing probiotics-derived factors as novel therapeutic agents is an alternative approach that addresses such concerns.”
“The fact that these factors retain their biological activity and can effectively reduce urinary oxalate excretion in mice indicates their significant potential as novel therapeutic agents, and provides a compelling reason for the aggressive pursuit of their characterization, which is currently underway,” he added.