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Abstract: SA-OR46

Cross-Talk Between Neutrophils and Macrophages Dictates the Outcome of Acute Pyelonephritis

Session Information

Category: Pediatric Nephrology

  • 1700 Pediatric Nephrology

Authors

  • Ruiz-Rosado, Juan de Dios, Abigail Wexner Research Institute at Nationwide Children’s Hospital, Columbus, Ohio, United States
  • Cortado, Hanna H., 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
  • Becknell, Brian, Abigail Wexner Research Institute at Nationwide Children’s Hospital, Columbus, Ohio, United States
  • Partida-Sanchez, Santiago, Abigail Wexner Research Institute at Nationwide Children’s Hospital, Columbus, Ohio, United States
Background

Pediatric urinary tract infections (UTI) account for 1.5 million clinician visits annually in the United States. Uropathogenic Escherichia coli (UPEC) causes over 80% of UTIs. Up to 50% of infants with a UTI develop a kidney infection (acute pyelonephritis, APN). Despite prompt diagnosis and treatment with appropriate antibiotics, a population of children with APN develops renal scarring, which can lead to kidney injury and renal dysfunction. The cellular immune mechanisms underlying renal scarring after an APN episode remain incompletely understood. In this study, we determined the contribution of neutrophils and monocytes to the development of kidney pathology following experimental APN.

Methods

C3H/HeOuJ female mice were treated with monoclonal antibodies to deplete neutrophils (anti-Ly6G), monocytes (anti-CD115), or both neutrophils and monocytes (anti-Gr1). After cell depletion, the animals were transurethrally infected with UPEC strain CFT073. Bacterial ascent was assessed via biophotonic imaging and quantification of bacterial burden in the kidney. The cell dynamics of monocytes and neutrophils were determined by flow cytometry and immunofluorescence microscopy. Renal inflammation and fibrosis were assessed by H&E and Sirius-Red, respectively. Transcriptomic analyses of infected kidneys were performed using TaqMan Arrays.

Results

Our data indicate that neutrophils, not monocytes, are required to prevent widespread UPEC dissemination during APN. In contrast, monocyte-derived macrophages promote bacterial dissemination and induce an early inflammatory response upon UPEC infection. Exacerbated, macrophage-dependent inflammation during APN leads to increased renal abscess formation, tubular injury, renal fibrosis, and azotemia.

Conclusion

While highlighting the essential antimicrobial role for neutrophils, our findings point to a novel detrimental function for macrophages during APN, and the potential utility of macrophage targeted therapies to reduce long-term sequelae following APN.

Funding

  • NIDDK Support