Mechanstic Investigation On Renal Tubular Epithelial Cell-derived Extracellular Vesicles In The Protection Of Remote Ischemic Preconditioning For Renal Ischemia-Reperfusion Injury

Objective:Remote ischemic preconditioning?RIPC?has proven to be a reliable strategy for prevention of injury to various organs.However the mechanism by which it does so is still unclear.The animal model of right kidney RIPC to proect the left kidney ischemia-reperfusion injury?IRI?was constructed firstly,for the attempt to explore the role of renal tubular epithelial cell?RTEC?-derived extracellular vesicles?EVs?in this processes.Methods:The rat model of left kidney IRI protected by right kidney RIPC was constructed.The characteristics of EVs which isolated from IPC right renal venous perfusates were identified.EVs were injected into rats with IRI kidneys to evaluate its therpaeutic effect on renal IRI.Hypoxia preconditioning?HPC?of human kidney 2?HK-2?cells was conducted to simulate IPC in vitro.EVs were isolated and then quantified.Both normoxic and HPC EVs were treated in vivo to assess the protective effect of renal IRI.To further explore the underlying mechanism,hypoxia-inducible factor 1??HIF-1??-and RAB22-inhibited HK-2 cells were used to investigate the role of the HIF-1?/RAB22 pathway in HPC-induced EV production.Moreover,microRNA?miRNA?sequencing analysis and bioinformatics analysis was performed.Results:The rat model of left kidney IRI protected by right kidney RIPC was successfully established.EVs mainly derived form RTECs during RIPC were found to mediated the protective effect of RIPC on renal IRI.Then,we revealed that the optimal conditions for simulating IPC in vitro was no more than 12 h under the 1%O₂ culture circumstance.HPC enhanced the production of EVs,and the production of EVs was regulated by the HIF-1?/RAB22 pathway during HPC.Moreover,HPC EVs were found to be more effective at attenuating mice renal IRI.Furthermore,16 miRNAs were upregulated in HPC EVs.Functional and pathway analysis indicated that the miRNAs may participate in multiple processes and pathways by binding their targets to influence the biochemical results during RIPC.Conclusion:We demonstrated that hypoxia activated HIF-1?/Rab22 pathway which mediated RTEC-derived EVs during RIPC.The HPC EVs protected renal IRI potentially through differentially expressed miRNAs.Further study is needed to verify the effective EV-miRNAs and their underlying mechanism.