Protective effect of erythropoietin preconditioning on kidney ischemia-reperfusion injury

Objective To explore the protective effect of erythropoietin (EPO) on renal ischemia-reperfusion injury (IRI) in rats.Methods Thirty male SD rats were randomly divided into sham operation group (Sham), renal IRI group (IRI) and EPO pretreatment group (EPO), 10 rats in each group. The renal IRI model was constructed by clamping the left renal pedicle for 1 h, removing the right kidney, and reperfusion for 24 h. In EPO group, EPO (1 000 U/kg) was intraperitoneally injected at 1 h before operation, while Sham group and IRI group were intraperitoneally injected with equal volume of normal saline. The left renal pedicle was clamped for 45 min in EPO and IRI groups, but not in Sham group. Renal perfusion was restored for 24 h, and then kidneys and serum were obtained. Enzyme linked immunosorbent assay (ELISA) was used to detect serum creatinine (SCr), blood urea nitrogen (BUN), pro-inflammatory cytokines[interleukin-6 (IL-6); interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α)] and anti-inflammatory cytokine (IL-10 and TGF-β). The reverse transcriptase polymerase chain reaction (RT-PCR) was used to detect renal pro-inflammatory cytokines (IL-6, IFN- γ and TNF-α) and anti-inflammatory cytokines[IL-10 and transforming growth factor beta (TGF-β)] mRNA expression levels. Western blotting was used to detect EPO receptor (EPOR), phosphorylated EPOR (p-EPOR), tyrosine kinase-2 (JAK2), signal transducer and activator of transcription 3 (STAT3), phosphorylated JAK2 (p-JAK2), phosphorylated STAT3 (p-STAT3) protein expression levels. Periodic acid Schiff staining (PAS) was used to examine the pathological changes of renal tissues.Results As compared with Sham group, the expression levels of p-EPOR, p-JAK2, p-STAT3, SCr, BUN, IL-6, TNF-α and IFN-γ were significantly increased, pathological changes of renal tissues obviously alleviated, and expression levels of IL-10 and TGF-β were markedly reduced in IRI group. There was no significant difference in EPOR, JAK2 and STAT3 levels between Sham group and IRI group. As compared with IRI group, the expression levels of p-EPOR, p-JAK2, p-STAT3, IL-10 and TGF-β were significantly increased, the levels of SCr, BUN, IL-6, TNF-α and IFN-γ were significantly reduced, and the pathological changes of renal tissues were significantly alleviated in EPO group, but there was no significant difference in EPOR, JAK2 and STAT3 expression between IRI group and EPO group.Conclusions EPO preconditioning can alleviate inflammation by inhibiting renal IRI, which may be related with the activation of EPOR/JAK2/STAT3 signaling pathway.