Defining the Expression and Functions of SLPI, an Antibacterial Peptide Produced by Kidney Intercalated Cells
- Pediatric Nephrology - II
November 03, 2023 | Location: Exhibit Hall, Pennsylvania Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Pediatric Nephrology
- 1900 Pediatric Nephrology
- Simoni, Aaron A., Nationwide Children's Hospital, Columbus, Ohio, United States
- Yepes Junquera, Guillermo, Nationwide Children's Hospital, Columbus, Ohio, United States
- Schwartz, Laura, Nationwide Children's Hospital, Columbus, Ohio, United States
- Spencer, John David, Nationwide Children's Hospital, Columbus, Ohio, United States
Mounting evidence suggests intercalated cells (IC) in the kidney collecting duct have antibacterial defenses that prevent pyelonephritis. In part, ICs prevent uropathogenic E. coli (UPEC) infections by expressing antimicrobial peptides and secreting them into the urine. The goal of this project is to define the expression, regulation, and antibacterial capacity of secretory leukocyte protease inhibitor (SLPI), a peptide that prevents infections in other organ systems by killing Gram-positive and negative bacteria. SLPI expression in the kidney has not been tested and its antibacterial activity against UPEC is unclear.
To evaluate SLPI expression, human kidney samples were obtained from people with and without a history of pyelonephritis. Mouse kidney samples were collected before and after mice were transurethrally infected with UPEC. ICs were enriched from mouse kidneys using FACS, cultured to confluency, and challenged with UPEC. SLPI expression was defined using qRT-PCR and Western blot. To test how SLPI is transcriptionally regulated, chromatin immunoprecipitation was performed. The antibacterial activity of SLPI was defined by performing UPEC bactericidal assays.
qRT-PCR and Western blot identify SLPI expression in human and mouse kidneys and show SLPI expression increases with pyelonephritis. Within ICs, Slpi transcript expression increases 1.7-fold following UPEC infection. With UPEC infection, we observed increased NF-kB binding to the SLPI promoter. Recombinant human and mouse SLPI exhibit dose-dependent killing of UPEC, including multi-drug resistant UPEC.
These findings are the first to demonstrate that SLPI is expressed in human and mouse kidneys and ICs. Its expression is augmented during pyelonephritis, perhaps via NF-kB activation. They also show that SLPI has antibacterial activity against UPEC and multi-drug resistant UPEC. Future studies are needed to assess the utility of SLPI as a pyelonephritis biomarker and define its IC antimicrobial activity in model systems.
- NIDDK Support