Kidney Week

Abstract: TH-PO116

Early Inflammatory Response to Pyelonephritis Induced by Uro-Pathogenic E. coli Requires P2Y2 Receptor Activation

Session Information

• AKI: Inflammation, New Technologies, Omics
  October 25, 2018 | Location: Exhibit Hall, San Diego Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Acute Kidney Injury

• 103 AKI: Mechanisms

Authors

• Christensen, Mette G., Aarhus University, Aarhus, Denmark

Mette G. Christensen,

• Therkildsen, Jacob Rudjord, Aarhus University, Aarhus, Denmark

Jacob Rudjord Therkildsen,

• Norregaard, Rikke, Aarhus University, Aarhus, Denmark

Rikke Norregaard,

• Praetorius, Helle A., Aarhus University, Aarhus, Denmark

Helle A. Praetorius,

Background

Urinary tract infections are exceedingly common and severe infections including pyelonephritis are often caused by E. coli that produces the pore-forming virulence-factor alpha-hemolysin (HlyA). We have previously demonstrated that HlyA releases cellular ATP directly through its membrane pore and that the associated erythrocyte lysis is completely prevented by blocking ATP-signalling. Renal epithelia are not lysed by the toxin. Instead the released ATP causes P2Y₂-receptor dependent intracellular [Ca²⁺] oscillations followed by epithelial IL-6 release. Thus, we speculated that P2Y₂ receptor deficient mice may be more susceptible to pyelonephritis as a result of inadequate epithelial-induced immune activation.

Methods

Acute pyelonephritis was induced by injecting 100 million HlyA-producing, uropathogenic E. coli into the urinary bladder of balb/c mice. After 24 hours, pyelonephritis was confirmed by culture of the right kidney, the urine and plasma were collected and the left kidney was isolated for histology after perfusion fixation.

Results

The mice showed relatively modest change in overall behaviour in response to the renal infection compared to vehicle controls and the survival or degree of infection was similar in P2Y₂^-/- and P2Y₂^+/+ mice after 24 h. The P2Y₂^+/+ mice with confirmed pyelonephritis, showed marked elevation of plasma IL-6 (42.0±7.3 pg/ml) compared to control (12.2±4.5 pg/ml, p=0.001). Preliminary data show reduced plasma IL-6 in P2Y₂^-/- mice with confirmed pyelonephritis (24.7±10.3 pg/ml). Similarly, we found significant elevation in keratinocyte chemoattractant (KC, a murine homologue of IL-8) in plasma of P2Y₂^+/+ mice subjected to HlyA-producing E. coli (91.3±27.4 pg/ml) compared to control (23.9±7.1 pg/ml, p=0.003). In contrast, plasma KC were markedly lower in P2Y₂^-/- mice with pyelonephritis (33.6±14.7 pg/ml). These changes are likely to reflect early interaction between bacteria and renal epithelium, since the degree of neutrophil infiltration had not increased in pyelonephritic kidneys at this early time point.

Conclusion

These results indicate that ATP signalling via the P2Y₂ receptor plays a pivotal role in the early response to pyelonephritis with HlyA-producing E. coli. Data on ATP release to the urine, survival and immune reaction after 3 days are pending.

Funding

• Government Support - Non-U.S.