Potent Therapy and Transcriptional Profile of Combined Erythropoietin Derived Peptide CHBP and Caspase-3 siRNA against Kidney Ischemia/Reperfusion Injury in mice

Abstract

Cause-specific treatment and timely diagnosis are still not available for acute kidney injury (AKI) apart from supportive therapy and serum creatinine measurement. A novel erythropoietin-derived cyclic helix B surface peptide (CHBP) protects kidneys against AKI with different causes, but the underlying mechanism is not fully defined. Herein, we investigated the transcriptional profile of renoprotection induced by CHBP and its potential synergistic effects with siRNA targeting caspase-3, an executing enzyme of apoptosis and inflammation, (CASP3siRNA) on ischemia/reperfusion (IR)-induced AKI. Utilizing a mouse model with 30-min renal bilateral ischemia and 48-h reperfusion, the renoprotection of CHBP or CASP3siRNA was demonstrated in renal function and structure, active caspase-3 and HMGB1 expression. Combined treatment of CHBP and CASP3siRNA further preserved kidney structure, and reduced active caspase-3 and HMGB1. Furthermore, differentially expressed genes (DEGs) were identified with fold change > 1.414 and P < 0.05. In IR kidneys, 281 DEGs induced by CHBP were mainly involved in promoting cell division and improving cellular function and metabolism (up-regulated STAT5B and SLC22A7). The additional administration of CASP3siRNA caused 504 and 418 DEGs in IR + CHBP kidneys with or without NCsiRNA, with 37 genes in common. These DEGs were associated with modulated apoptosis and inflammation (up-regulated BCL6, SLPI and SERPINA3M), and immunity, injury and microvascular homeostasis (up-regulated CFH and GREM1, and down-regulated ANGPTL2). This proof-of-effect study indicated the potent renoprotection of CASP3siRNA upon CHBP at the early stage of IR-induced AKI. Underlying genes, BCL6, SLPI, SERPINA3M, GREM1 and ANGPTL2, might be potential new biomarkers for clinical applications.