Short-And Long-Term Synergistic Renoprotection Induced By Erythropoietin Derived Peptide And Caspase-3 Sirna Against Renal Ischemia/Reperfusion Injury In Mice

Renal group, Nantong-Leicester Joint Kidney Science Institute. Introduction: Renal ischemia/reperfusion (IR) injury is one of major causes of acute kidney injury (AKI) that is lack of effective treatment. Our previous studies have revealed that EPO derived helix B surface peptide (HBSP) or cyclic HBSP (CHBP), the ligand of innate repair receptor EPOR/βcR, was renoprotective against IR injury. This study further investigated the potential synergetic renoprotection of HBSP/CHBP with small interfering RNA targeting caspase-3 (C3siRNA). Methods: Mouse renal IR injury was established in adult male C57BL/6, by blocking bilateral renal pedicles for 30 min and reperfusion for 48 h and 2 w (n = 6-9), with respective sham groups at each time point (n = 5). CHBP or HBSP at 24 nmol/kg and/or C3siRNA or negative control siRNA (NCsiRNA, 0.03 mg/kg) were administered to the IR mice. Renal function, histology and molecular biological parameters were assessed, along with genomic profile in 48-h kidneys using affymetrix gene chips. Results: At 48-h IR, CHBP or C3siRNA preserved kidney function and structure, while co-treatment of both exhibited greater preservation in kidney structure compared to single usage, as well as reduced 17 kDa active caspase-3.Microarray data revealed that 281 differentially expressed genes (DEGs) were modified by CHBP in IR kidneys, but 504 DEGs were further changed by C3siRNA treatment in contrast to the NCsiRNA control, with 3 genes commonly affected in both comparisons, according to fold change > 1.414 and P < 0.05. Some highly-dysregulated genes such as RBP4, Grem1 and Angptl2 might be new biomarker candidates. Gene Ontology analysis of biological processes showed that CHBP mainly promoted cell division, function and metabolism, and C3siRNA further modulated genes involving in renal inflammation and cell survival.At 2-w IR, co-treatment with HBSP and C3siRNA showed the additional preservation of kidney structure, as well as reduced collagen deposition in the tubulointerstitial area, compared with any single treatment.Conclusion: This proof-of-effect study indicated that simultaneously modulating caspase-3 enhanced the renoprotection of CHBP/HBSP, which might improve the short and long-term outcome of IR-induced AKI. Other highly changed candidate genes might be new biomarkers of AKI upon further validation. National Natural Science Foundation of China 81873622. References: 1. Yang C. A novel proteolysis-resistant cyclic helix B peptide ameliorates kidney ischemia reperfusion injury. Biochim Biophys Acta. 2014;1842(11):2306-17. 2. Yang C. Serum-stabilized naked caspase-3 siRNA protects autotransplant kidneys in a porcine model. Mol Ther. 2014;22(10):1817-28. 3. Wu Y. Protective Effects of HBSP on Ischemia Reperfusion and Cyclosporine A Induced Renal Injury. Clin Dev Immunol. 2013;2013:758159.