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Abstract: SA-PO614

Cell-Specific Insulin Receptor Deletion Disrupts Urothelial Barrier Integrity Increasing Urinary Tract Susceptibility to Infection

Session Information

  • Pediatric Nephrology - II
    November 05, 2022 | Location: Exhibit Hall, Orange County Convention Center‚ West Building
    Abstract Time: 10:00 AM - 12:00 PM

Category: Pediatric Nephrology

  • 1800 Pediatric Nephrology

Authors

  • Bender, Kristin, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States
  • Schwartz, Laura, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States
  • Simoni, Aaron A., Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States
  • Spencer, John David, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States
Background

Individuals with diabetes mellitus have a higher risk for urinary tract infection (UTI), which may increase their risk for kidney injury. The underlying mechanisms of infection remain undefined. During infection, the bladder urothelium acts as a barrier during bacterial attachment and invasion. To investigate the role of insulin signaling on urothelial barrier integrity and infection susceptibility, we genetically deleted the insulin receptor (IR) in the basal or intermediate/superficial cells in the murine urothelium.

Methods

IR knock-out mice (IRKO) were generated by crossing mice homozygous for the floxed Insr (insulin receptor) gene with transgenic mice that have tamoxifen-inducible Cre recombinase under the Keratin 5 (Krt5) or Uroplakin 2 (Upk2) promoter expressed in the basal or intermediate/superficial cells, respectively. Littermates lacking the Cre transgene served as controls (IRflox). To determine if IR deletion impacts host defense, female mice were transurethrally infected with uropathogenic E. coli (UPEC). UPEC burden was enumerated in urine and bladder post infection. To assess bladder barrier permeability, uninfected bladders were mounted in an Ussing chamber, and transepithelial resistance (TER) and radioisotope permeabilities were measured. Cell adhesion markers in isolated urothelium were assessed by qRT-PCR and western blot.

Results

Compared to IRflox, IRKO mice exhibit normal development, normoglycemia, and normal bladder histology. Following transurethral UPEC infection, UPK2 IRKO mice have significantly greater UPEC burden in the urine and bladder while barrier studies indicted uninfected UPK2 IRKO mice have lower transepithelial resistance and increased water and urea permeabilities. No differences are observed in Krt5 IRKO in burden. Isolated urothelium from UPK2 IRKO mice expressed lower mRNA levels of several cell adhesion markers compared to IRflox.

Conclusion

These results suggest that insulin signaling in the intermediate/superficial cells in the urothelium is critical for the integrity of the urothelial barrier in UTI defense. Disruption of signaling in the basal cells did not impact the bladders defenses during infection. Additional studies to evaluate how IR deletion impacts urothelial defenses.

Funding

  • NIDDK Support