Abstract: TH-PO1067

Development of a Humanized Murine Model for Study of O. formigenes Intestinal Colonization

Session Information

Category: Mineral Disease

  • 1204 Mineral Disease: Nephrolithiasis

Authors

  • Pebenito, Amanda, New York University School of Medicine, New York, New York, United States
  • Nazzal, Lama, New York University School of Medicine, New York, New York, United States
  • Liu, Menghan, New York University School of Medicine, New York, New York, United States
  • Blaser, Martin J., New York University School of Medicine, New York, New York, United States
Background

Oxalobacter formigenes (O.f.) are symbiotic bacteria in the human gut that degrade oxalate, a component of most kidney stones. Observational studies suggest that O.f. colonization reduces the risk for kidney stones. Given the importance of dietary oxalate and calcium levels, studies in mice are more practical than in humans; however, O.f. do not naturally colonize laboratory rodents. Our objective was to develop a humanized murine model to investigate the therapeutic potential of O. formigenes in its native microbiome.

Methods

To humanize mice, we transplanted feces from a pool of healthy human donors who were O.f.-negative (confirmed by PCR, qPCR, and oxalate degradation assay), supplemented with a human O.f. strain: OXCC13 (108 CFU/mL). The inoculum was introduced to C57BL/6J mice via esophageal gavage three times over six days. We compared two methods of humanization, transplanting inocula into mice that were (i) germ free; or (ii) treated with high-dose, broad-spectrum antibiotics (0.5g/L vancomycin, 1g/L ampicillin, 1g/L neomycin, 1g/L metronidazole in drinking water for 6 days) to suppress their native microbiome. As controls, one group received humanization with no pre-treatment and another received a sham gavage.

Results

Based on oxc qPCR and 16S rRNA sequencing, all humanized groups were stably colonized with O.f. through 8 weeks post-gavage, whereas mice that received sham gavage remained uncolonized (p<0.001). Humanization significantly changed microbial community structure as measured by unweighted UniFrac distances (p<0.001) and humanized germ-free and antibiotic-treated groups were highly similar in β-diversity. We also assessed humanization by the number of shared OTUs between treatment groups and donor inoculum over time. Both germ-free and antibiotic-treated mice had a significant increase in shared OTUs compared to sham (p=0.024, p=0.036). The number of shared OTUs was stable in each group through 8 weeks post-gavage without significant difference between germ-free and antibiotic-treated mice.

Conclusion

Our method of transplanting human feces and O.f. conferred a new microbial phenotype in mice that resembled a human microbiome and was stable over time. Antibiotic pre-treatment, a simpler alternative to germ-free mice, provided comparable results. This model may allow insights to O.f.’s role in preventing calcium oxalate stones.

Funding

  • Other NIH Support