Research Project
10280276
In the United States, more than 200,000 patients are estimated to suffer from enteric hyperoxaluria (EH). EH affects patients with malabsorptive gastrointestinal diseases and is well-known to cause recurrent nephrolithiasis. Therapies for EH are limited and only partially mitigate hyperoxaluria. Several gut bacteria can degrade oxalate and likely play an essential role in protecting against hyperoxaluria. The role that these oxalate-degrading bacteria, collectively referred to as the oxalobiome, play in the pathophysiology of EH has not been elucidated. We developed a novel computational method to perform the first comprehensive study of human oxalate-degrading microbes. We defined their individual contributions to overall oxalate degradation in vivo in healthy and inflammatory bowel disease (IBD) population, a population at risk for EH. Our data showed that IBD patients have a reduction in the function of the oxalobiome associated with higher levels of fecal oxalate, suggesting that this population might benefit from the restoration of the oxalobiome. Hence, this proposal?s scientific premise is that the microbiome is an important determinant of urinary oxalate (UOx) levels and that with greater knowledge of the oxalobiome?s biology, we can manipulate it to prevent EH and kidney stones. Our overall hypothesis is that the oxalobiome function determines UOx. As a corollary, we hypothesize that the microbiome can be therapeutically targeted to reduce hyperoxaluria and the risk of kidney stones. To test this hypothesis, we propose studies that leverage our expertise in conducting microbiome trials and microbiome functional analyses in addition to our experience in performing humanizations. Our first aim is to analyze associations of oxalobiome alterations with UOx levels in patients with EH. We will place healthy and EH subjects on controlled diets before and after inducing their oxalobiome with daily oxalate supplementation to analyze the oxalobiome structure, using metagenomic sequencing, and function, using metatranscriptomic sequencing. We will identify the oxalobiome members with the highest oxalate metabolic activity in healthy and EH subjects, and those whose absence is associated with the development of hyperoxaluria. Global analysis of the microbiome dynamics and networks will allow us to identify bacterial taxa that are associated with lower UOx in EH and healthy adults. Our second aim is to determine whether human-to-mouse transfer of whole and enriched oxalobiome communities results in reduced urinary oxalate. For this aim, we will develop an EH IBD mouse model and perform human-to-mouse transfer of whole and enriched oxalobiome communities to evaluate its effects on UOx. Deciphering the oxalobiome function in EH, using recently developed technologies, in conjunction with our targeted computational methods, and then testing our hypotheses in mouse models, will permit us to develop promising microbiological approaches to control hyperoxaluria in EH.
