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Abstract: SA-PO174

Neutrophil Extracellular Traps (NETs) in the Peritoneal Cavity Contribute to Septic AKI (SAKI) via IL-17A Production in a Mouse Cecal Ligation and Puncture (CLP) Sepsis Model

Session Information

  • AKI: Mechanisms - III
    November 04, 2023 | Location: Exhibit Hall, Pennsylvania Convention Center
    Abstract Time: 10:00 AM - 12:00 PM

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms

Authors

  • Naito, Yoshitaka, National Institutes of Health, Bethesda, Maryland, United States
  • Hayase, Naoki, National Institutes of Health, Bethesda, Maryland, United States
  • Chari, Rohit R., National Institutes of Health, Bethesda, Maryland, United States
  • Aragao Carneiro dos Santos, Alef, National Institutes of Health, Bethesda, Maryland, United States
  • Hu, Xuzhen, National Institutes of Health, Bethesda, Maryland, United States
  • Yuen, Peter S.T., National Institutes of Health, Bethesda, Maryland, United States
  • Star, Robert A., National Institutes of Health, Bethesda, Maryland, United States
Background

There are no specific treatments for SAKI. We previously showed that the Toll-like receptor 9 (TLR9) pathway contributes to SAKI: (1) TLR9 is stimulated by mitochondrial DNA endogenously released during sepsis, (2) TLR9 activates interleukin (IL)-17A, and (3) knockout of TLR9 or IL-17A improves sepsis. Mitochondrial DNA was reported to stimulate NET formation via TLR9 in pulmonary graft dysfunction. Knockout of Peptidyl Arginine Deiminase 4 (PAD4), an enzyme essential for NET formation, completely abolished IL-17A accumulation during atherosclerosis in aorta. Treatment with Cl-amidine, a PAD inhibitor, improved survival after CLP. We hypothesized that NET formation in an infectious site could contribute to SAKI via IL-17A production in sepsis.

Methods

PAD4 KO, IL-17A KO and wild type (WT) controls were subjected to CLP. We assessed kidney function and IL-17A levels in peritoneal lavage fluid (PLF) and blood. Leukocyte infiltration in PLF, blood, and kidney were assessed by flow cytometry. NET formation in the cells in PLF was assessed by immunocytochemistry. To further investigate the effect of NETs on SAKI, we collected neutrophils from WT PLF at 18h after CLP and administered them intraperitoneally into PAD4 KO mice immediately after CLP.

Results

PAD4 KO and IL-17A KO attenuated SAKI and PAD4 KO decreased IL-17A levels in PLF and blood at 18h after CLP. CLP upregulated neutrophil infiltration into PLF, blood, and kidney at 18h. IL-17AKO attenuated neutrophil increase in blood and infiltration into kidney, but not in PLF. The cells in PLF at 18h after CLP contained >70% of neutrophils and formed NETs without any stimulation ex vivo. Adoptive transfer of WT neutrophils partially counteracted the protective effect of PAD4 KO against SAKI.

Conclusion

We found that PAD4 KO and 17A KO protected against SAKI, and PAD4 KO decreased IL-17A production in plasma and peritoneal cavity. IL-17A promoted neutrophil infiltration into blood and kidney after CLP. Adoptive transfer of WT neutrophils into the peritoneal cavity reversed the beneficial effect of PAD4 KO on CLP-induced SAKI. These findings suggest that NETs in the peritoneal cavity might contribute to a distant organ effect of SAKI via IL-17A production.

Funding

  • NIDDK Support