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Abstract: PO1984

Leukocyte-Derived Human RNase 6 and RNase 3 Provide Resistance to Urinary Tract Infection

Session Information

Category: Pediatric Nephrology

  • 1700 Pediatric Nephrology

Authors

  • Ruiz-Rosado, Juan de Dios, Center for Clinical and Translational Research, Abigail Wexner Research Institute at Nationwide Children’s Hospital, Columbus, Ohio, United States
  • Cortado, Hanna H., Center for Clinical and Translational Research, Abigail Wexner Research Institute at Nationwide Children’s Hospital, Columbus, Ohio, United States
  • Kercsmar, Macie M., Center for Clinical and Translational Research, Abigail Wexner Research Institute at Nationwide Children’s Hospital, Columbus, Ohio, United States
  • Jackson, Ashley R., Center for Clinical and Translational Research, Abigail Wexner Research Institute at Nationwide Children’s Hospital, Columbus, Ohio, United States
  • Li, Birong, Center for Clinical and Translational Research, Abigail Wexner Research Institute at Nationwide Children’s Hospital, Columbus, Ohio, United States
  • Becknell, Brian, Center for Clinical and Translational Research, Abigail Wexner Research Institute at Nationwide Children’s Hospital, Columbus, Ohio, United States
Background

Urinary tract infections (UTIs) account for 7 million office visits and $1.6 billion dollars in health care spending annually in the United States. Uropathogenic Escherichia coli (UPEC) is the primary etiological pathogen causing over 80% of UTI. Currently, there is a critical need for innovative and effective strategies to treat UTI and prevent UTI-associated sequelae. Antimicrobial peptides (AMPs) are fundamental components of the innate immune system that serve instrumental roles in eliminating pathogenic microbes and thus represent a potential therapeutic tool to limit UTIs.
We have identified AMPs within the Ribonuclease (RNase) A Superfamily that promote resistance against uropathogens. In this study, we determined the contribution of human RNase 6 and 3 to bacterial clearance following experimental UTI in vivo.

Methods

Humanized RNASE6 and RNASE3 transgenic mice (C57BL/6) were generated by integrating human RNASE6 or RNASE3 transgene fragments into the mouse genome. Humanized RNASE6–expressing or RNASE3-expressing transgenic female mice were transurethrally infected with UPEC strain UTI89. Non-transgenic littermates were used as negative controls. Bone marrow-derived macrophages (BMDMs) and BM neutrophils (PMNs) from RNASE6 and RNASE3 transgenic mice, respectively, were infected with UPEC in vitro. RNASE6 and RNASE3 expression were determined by western blot, flow cytometry and immunofluorescence. Bacterial burden was assessed via quantification of UPEC colony forming units.

Results

RNASE6 and RNASE3 transgenic mice showed reduced bacterial burden in the urine and bladder compared to non-transgenic mice following UPEC infection. F480+ macrophages in the infected bladder were identified as the main source of RNASE6, while RNASE3 was predominantly expressed by Ly6G+ neutrophils in the bladder submucosa. We also found that BMDMs from RNASE6 transgenic mice had reduced intracellular bacteria compared to WT BMDMs after UPEC infection in vitro. Decreased extracellular bacterial burden was observed in cell cultures from RNASE3 transgenic PMNs compared to non-transgenic PMNs.

Conclusion

Our findings indicate that RNASE6 and RNASE3 produced by innate phagocytes have a critical anti-microbial role against UPEC in vivo and in vitro. These RNases have the potential to effectively limit or prevent UTIs.

Funding

  • NIDDK Support