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Abstract: SA-PO608

α-Defensins 1-3 Gene-Dosage Drives Protection of the Urinary Tract From Uropathogenic Bacterial Challenge

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

  • Canas, Jorge Jose, Indiana University School of Medicine, Indianapolis, Indiana, United States
  • Schwaderer, Andrew L., Indiana University School of Medicine, Indianapolis, Indiana, United States
  • Hains, David S., Indiana University School of Medicine, Indianapolis, Indiana, United States
Background

Antimicrobial peptides (AMPs) are potent innate immune effectors with direct antimicrobial activity against a range of bacteria. The AMP α-Defensin 1-3 (DEFA1A3) is expressed by human neutrophils granules and kidney epithelial cells. Recently, a low DNA copy number of DEFA1A3 has been associated with increased UTI risk in children (<4 copies versus >6 per diploid genome). Due to the lack of this gene in mice, we utilize a human DEFA1A3 gene knock-in mouse with a 4 copy gene per haploid genome to study gene-dosage interactions. This study aims to compare bacterial burden and antimicrobial gene expression between human DEFA1A3 gene knock-in mice under a pyelonephritis model.

Methods

Experimental UTIs were induced by transurethral inoculation of uropathogenic E. coli strain CFT073 into DEFA1A3+/+ (8 copies), DEFA1A3+/0 (4 copies), and DEFA1A30/0 (0 copies) littermate mice. Following 6 hours post-infection (6-hpi), kidneys and bladders were homogenized for bacterial colony-forming unit analysis and mRNA isolation.

Results

Compared to DEFA1A30/0, DEFA1A3+/+ mice had a significant reduction of mean bacterial burden titers in kidneys and bladders (Figure 1). Following gene expression antimicrobial response array and qRT-PCR in DEFA1A3+/+ and DEFA1A30/0 kidneys, the most significantly differentially expressed genes were Rac1 and Lyz2 (Figure 2).

Conclusion

The human DEFA1A3 gene knock-in mouse represents a critical tool to evaluate novel α-defensins 1-3 gene-immune interactions. Further studies will involve exploring gene-drug interactions under antibiotic prophylaxis settings before UTI challenge.

Figure 1. Bacterial titers of kidney (A) and bladders (B) comparing DEFA1A3+/+, DEFA1A3+/0, and DEFA1A30/0 mice. Percentages above the line are clearance rates in kidneys without bacterial growth.

Figure 2. Kidney DEFA1A3+/+and DEFA1A30/0 mouse mRNA expression of Rac (A) and Lyz2 (B) relative to Gapdh gene.

Funding

  • NIDDK Support