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Abstract: SA-PO069

Erythropoietin-Derived HBSP Binding to Tubular Epithelia In Vitro Reduces Apoptosis and Synergistically Protects Kidneys with Caspase-3 siRNA Against 2-Week Ischemia-Reperfusion Injury in the Mouse

Session Information

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms

Authors

  • Wu, Yuanyuan, Nantong University, Nantong, China
  • Liu, Yu, Affiliated Hospital of Nantong University, Nantong, China
  • Zhang, Yufang, Nantong University, Nantong, Jiangsu, China
  • Li, Wenting, Nantong University, Nantong, China
  • Barker, Joanna M., University of Leicester, Leicester, United Kingdom
  • Lowe, Mark Philip, University of Leicester, Leicester, United Kingdom
  • Brunskill, Nigel J., University of Leicester, Leicester, United Kingdom
  • Yang, Bin, University of Leicester, Leicester, United Kingdom
Background

Ischemia-reperfusion injury (IRI) induced acute kidney injury has high morbidity and mortality, but no specific treatment. Renoprotection by caspase-3 siRNA (C3siRNA), erythropoietin (EPO) derived peptide HBSP, or cyclic HBSP ± C3siRNA, has been previously demonstrated against IRI at 24 or 48 h. HBSP only recognizes tissue protective heterodimer receptor (EPOR/βcR) and highly expresses in early IRI kidneys. This study further explored the synergistic long-term effect and mechanism of these agents administrated at the onset of injury.

Methods

Bilateral occlusion and sham operation of renal pedicles for 30 min were performed on adult male C57BL/6 mice, followed by reperfusion for 2 w, with or without the treatment of HBSP ± C3siRNA/negative control siRNA (NCsiRNA, n=5-9). Twenty-four nmol/kg BW of HBSP was administrated at the onset of occlusion and 15 min after reperfusion, while 30 µg/kg BW of C3siRNA or NCsiRNA was injected via tail vein 2 h before surgery. Moreover, the localization of fluorescent iridium labeled HBSP (HBSP-Ir) at 25 µM was detected at 1 h post incubation with TCMK-1 cells (mouse kidney tubular epithelial cell line, TECs) ± H2O2 at 200 µM post 24 h. Apoptosis was assessed when HBSP-Ir at 5, 10, 20 or 40 ng/ml was added together with H2O2 for 24 h.

Results

The typical impairment of renal structure and function was observed in the IRI kidneys, with increased apoptotic cells. However, this injury was reversed by HBSP or C3siRNA, which decreased serum creatinine, tubulointerstitial damage and apoptosis. Furthermore, co-treatment with both agents resulted in greater preservation of kidney structure and apoptosis compared with single administration. In addition, HBSP-Ir bound to TCMK-1 cells only treated by H2O2. HBSP-Ir also significantly reduced cell apoptosis at all dosages.

Conclusion

HBSP binds to TECs and induces anti-apoptosis. HBSP administrated at the early stage of injury has long-term and synergistic effects with C3siRNA on renal IRI. These data indicate a feasibility that HBSP might be a guide for cell-specific delivery of siRNA, if both are conjugated, targeting caspase-3 in specific cells highly-expressed EPOR/βcR in IRI kidneys.