ASN's Mission

ASN leads the fight to prevent, treat, and cure kidney diseases throughout the world by educating health professionals and scientists, advancing research and innovation, communicating new knowledge, and advocating for the highest quality care for patients.

learn more

Contact ASN

1401 H St, NW, Ste 900, Washington, DC 20005

email@asn-online.org

202-640-4660

The Latest on Twitter

Kidney Week

Abstract: SA-PO434

RNase 7 Shields the Kidney and Bladder from Uropathogens

Session Information

  • Pediatric Nephrology - II
    October 27, 2018 | Location: Exhibit Hall, San Diego Convention Center
    Abstract Time: 10:00 AM - 12:00 PM

Category: Pediatric Nephrology

  • 1600 Pediatric Nephrology

Authors

  • Bender, Kristin, The Research Institute at Nationwide Children''s Hospital, Columbus, Ohio, United States
  • Eichler, Tad, The Research Institute at Nationwide Childrens Hospital, COLUMBUS, Ohio, United States
  • Murtha, Matthew J., Ohio State University Hospital, Columbus, Ohio, United States
  • Li, Birong, Nationwide Children's Hospital, Columbus, Ohio, United States
  • Becknell, Brian, Nationwide Children's Hospital, Columbus, Ohio, United States
  • Spencer, John David, The Research Institute at Nationwide Children's, Columbus, Ohio, United States
Background

In an era of multi-drug resistant pathogens, new therapies are needed to prevent urinary tract infections (UTI). Our laboratory identified Ribonuclease 7 (R7) as a human antimicrobial peptide that is secreted by the bladder urothelium and kidney’s intercalated cells into the urine. Neutralization of R7’s urinary antibacterial activity facilitates uropathogenic Escherichia coli (UPEC) replication. While R7 has potent bactericidal activity against UPEC, our understanding of its contributions to urothelial defenses is limited in vivo because its expression is absent in the laboratory mouse and restricted to humans/upper primates. Thus, we generated humanized transgenic R7 mice and assess R7’s in vivo antimicrobial activity.

Methods

Using BAC-based recombineering, we integrated the human RNASE7 gene into the mouse genome. BAC-R7 transcript and peptide expression was characterized in kidneys and bladders from R7 transgenic mice and littermate controls in states of health and after mice were transurethrally infected with UPEC. R7 cytotoxicity and its impact on murine immunity was evaluated with cytokine arrays, complete blood counts, serum chemistry, and histology. R7’s antibacterial activity was evaluated by subjecting mice to experimental UTI. After infection, kidneys, bladders, and urine were collected and UPEC burden was quantitated.

Results

R7 transgenic mice had normal development, phenotypes, and urinary tract histology. R7 mRNA and peptide expression were detected in bladder and kidneys of transgenic mice. Immunostaining localized R7 production to the kidney’s intercalated cells and the bladder urothelium, which mirrors human expression. R7 mice had normal renal function, cytokine profiles, and complete blood counts. After UTI, R7 transgenic mice had 2-3 fold lower urine, bladder, and kidney UPEC burden compared to littermate controls. Following UPEC inoculation, R7 mRNA and peptide expression increased in bladders and kidneys.

Conclusion

R7 expression in our transgenic humanized mice is similar to humans. R7 has limited cellular toxicity and does not impact basal murine immune function. Following experimental UTI, R7-expressing mice are significantly protected from UPEC. These studies provide the needed evidence that R7 has a key role in urothelial defense against UPEC and suggest that R7 may be an ideal candidate to develop as a new UTI therapy.

Funding

  • NIDDK Support