Thailand medical researchers discover that Lactobacillus Acidophilus can prevent kidney stone development

Thailand Medical: In an intriguing study conducted by researchers from Mahidol University, the potential role of Lactobacillus acidophilus in combating kidney stone formation has been explored. This Thailand Medical News delves into the findings that could offer a new avenue for preventing calcium oxalate (CaOx) stones, a common form of kidney stones. Researchers from the Medical Proteomics Unit at Siriraj Hospital, Mahidol University, aimed to clarify the mechanisms by which L. acidophilus, a common commensal bacterium, inhibits kidney stone formation, contrasting it with Escherichia coli, a known promoter of stone development.


Thailand medical researchers discover that Lactobacillus Acidophilus can prevent
kidney stone development

The Background on Calcium Oxalate Stones
Calcium oxalate stones are one of the most prevalent types of kidney stones, affecting over half of kidney stone patients. These stones are formed due to the supersaturation of calcium and oxalate ions in the urine. The process begins with the formation of CaOx crystals, which can then grow, aggregate, and adhere to the renal tubules, eventually forming stones. A variety of factors, including high levels of calcium (hypercalciuria), oxalate (hyperoxaluria), and changes in urine chemistry, contribute to stone development.
 
However, bacteria present in the urinary tract may also play a significant role in this process. While some bacteria like E. coli have been associated with an increased risk of stone formation, others, such as Lactobacillus, may offer protective benefits. This study focused on the direct inhibitory effects of L. acidophilus, a species of Lactobacillus commonly found in the urinary tract, and its comparison with E. coli in promoting CaOx stone development.
 
Key Findings of the Study
The researchers discovered that L. acidophilus can significantly reduce various steps in CaOx stone formation, including crystal growth, aggregation, and adhesion to kidney cells. These findings were obtained through a series of experiments designed to simulate the conditions in which CaOx crystals form and grow in the kidney.
 
In one experiment, the researchers exposed kidney cells to L. acidophilus and E. coli at a concentration of 1 × 10³ colony-forming units (CFU) per milliliter. They found that L. acidophilus reduced the formation of new CaOx crystals, decreased the growth and aggregation of existing crystals, and prevented the crystals from adhering to the renal cell membranes. In contrast, E. coli promoted crystal growth and aggregation but did not significantly affect crystal-cell adhesion.
 
Mechanism Behind the Inhibitory Effect
The study found that the mechanism behind the inhibitory effect of L. acidophilus on CaOx stones does not involve oxalate degradation, as was initially hypothesized. When the bacteria were incubated with oxalate for up to three hours, there was no significant reduction in the remaining oxalate, suggesting that neither L. acidophilus nor E. coli degraded the oxalate during this period. However, both bacteria were found to bind to CaOx crystals.
 
Interestingly, the difference in the effects of these two bacteria was attributed to their surface components. L. acidophilus possesses an S-layer protein on its surface, while E. coli has flagella. The study found that removing the S-layer protein from L. acidophilus or the flagella from E. coli completely abolished their respective inhibitory and promoting effects on CaOx crystal development. This highlights the crucial role of these surface structures in mediating the interaction between the bacteria and the CaOx crystals.
 
Implications for Kidney Stone Prevention
These findings are significant because they suggest that L. acidophilus could be used as a natural inhibitor of kidney stone formation. By preventing the growth, aggregation, and adhesion of CaOx crystals, this bacterium could help reduce the risk of kidney stone formation in individuals prone to the condition. Furthermore, the study sheds light on the importance of bacterial surface components in modulating stone formation, offering new targets for future therapeutic interventions.
 
The protective role of L. acidophilus in the urinary tract could also explain why certain individuals, particularly those with a healthy urinary microbiome, are less prone to developing kidney stones. Previous research has shown that Lactobacillus species are more abundant in the urine of healthy individuals compared to those with kidney stones. Therefore, promoting the growth of beneficial bacteria like L. acidophilus could be a promising strategy for preventing kidney stone disease.
 
Future Directions
While this study provides important insights into the role of L. acidophilus in preventing kidney stones, there are still several areas that require further investigation. For instance, the study was conducted under in vitro conditions, and it remains to be seen whether the same effects can be observed in vivo.
 
Additionally, the protective effects of other Lactobacillus species, as well as the role of other bacterial surface components, need to be explored to gain a more comprehensive understanding of how the urinary microbiome influences kidney stone formation.
 
Furthermore, the researchers highlighted that although the concentration of L. acidophilus used in this study was physiologically relevant, much higher concentrations of the bacterium were required to observe oxalate degradation. This suggests that under normal conditions, the primary mechanism by which L. acidophilus inhibits kidney stone formation is through its surface interactions with CaOx crystals, rather than through oxalate degradation. Future studies should aim to determine whether enhancing the growth of L. acidophilus in the urinary tract could provide sufficient protection against stone formation in vivo.
 
Conclusion
This study represents a significant step forward in understanding how the urinary microbiome, and specifically L. acidophilus, can influence the development of kidney stones. By inhibiting the growth, aggregation, and adhesion of CaOx crystals, L. acidophilus offers a promising natural defense against kidney stone formation. Further research is needed to confirm these findings in vivo and explore the potential for probiotic therapies that harness the protective effects of beneficial bacteria in the urinary tract.
 
The study findings were published in the peer-reviewed journal: Microbiome.
https://link.springer.com/article/10.1186/s40168-024-01877-y
 
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