Os003 Ipc Reduces Iri in the Rat Kidney Byrepressing Its Unique Microrna Expression Profile

Background: MicroRNAs are important post-transcriptional regulators of gene expression, implicated in many physiological and pathophysiological processes, including kidney disease. Ischaemia reperfusion injury (IRI) is an inevitable consequence of transplantation and results in delayed graft function and primary non-function. The aim of this research was to characterise the role of microRNAs in kidney IRI and their response to the therapeutic strategy of Ischaemic Preconditioning (IPC). Methods: An in vivo model of IRI and IPC was utilised, in which adult male lewis rats underwent surgery and were divided into 3 groups: sham; IRI (45 min bilateral renal pedicle cross-clamping); and IPC+IRI (3 cycles of 2 min ischaemia and 5 min reperfusion, prior to 45 min of IRI). Kidney tissue was retrieved at 48 h and blood samples taken at 0 h and 48 h. Histological, biochemical and mRNA AKI marker analysis was undertaken. MicroRNAs were profiled using Next Generation Sequencing (NGS) and hybridisation arrays, and changes in selected microRNAs confirmed by RT-qPCR. Results: IRI was characterised by: marked histological damage including acute tubular necrosis and endothelial cell loss; increased serum creatinine; and increased NGAL and KIM-1 expression. In contrast IPC reduced the histology scores, serum creatinine and NGAL and KIM-1 expression. NGS and Microarray analyses identified 18 differentially expressed microRNAs in IRI, which were confirmed by RT-qPCR. This microRNA expression profile was attenuated by IPC, with particular changes noted in 4 microRNAs ((miR-21, 221, and -222, up-regulated in IRI and down-regulated by IPC) and (miR-3753p, down-regulated in IRI and up-regulated by IPC)). Conclusion: These data have identified a unique microRNA signature of IRI in the rat kidney, and have shown that pulsatile IPC improved injury by attenuating this microRNA signature. MicroRNAs thus show significant promise as biomarkers of injury and potential therapeutic targets in this context.