Inhibition of miR-182 to prevent postischemic acute renal allograft failure in vivo

Acute renal failure (ARF) after kidney transplantation represents the main risk factor for allograft loss. While ARF occurs rarely after living donor transplantation, about 25% of deceased donor kidney recipients develop ARF and require dialysis within the first week after transplantation. Various molecular mechanisms have been elucidated. Pro-inflammatory response after brain death and ischemic reperfusion injury are significant factors contributing to development of ARF. Nevertheless, prevention of ARF after transplantation is desirable but still not feasible. MicroRNAs (miRNAs) are a class of small non-coding 18 to 24 nucleotide-long RNAs involved in the regulation of diverse cellular functions and in the pathogenesis of ARF. One of the most appealing properties of miRNAs as therapeutic agents is their ability to target multiple molecules, making them extremely efficient in regulating distinct biological cell processes relevant in specific diseases. One of their members, miR-182 is strongest increased during acute renal transplant failure. miR-182 regulates approx. 50% of significantly deregulated genes in renal allograft biopsies developing ARF within the first week after transplantation. Furthermore the inhibition of miR-182 showed anti-inflammatory properties over the target gene FOXO1 and is protective against ischemic injury. Aims: 1. We will investigate whether the inhibition of miR-182 will revert transcriptional activation of genes involved in ARF in the rat donor kidney 2. To elucidate the efficacy of miR-182 antisense in preventing the incidence and duration of postischemic ARF in a rat model. 3. The third aim is to test the proposed treatment in human deceased donor kidneys, which are declined for transplantation. Machine perfusion technique (lifeport) will be used to apply the drug into the donor kidneys ex vivo. This study seeks to investigate whether modulation of molecular regulators in human donor kidneys and prevention of allograft injury can be accomplished by inhibition of miR-182.

Acute kidney injury (AKI) remains a major clinical event associated with unacceptably high mortality rates, progression to end-stage renal disease, and rising incidence, severity, and cost. Our project aims to ameliorate AKI in transplantation, where it is an unavoidable phenomenon. Post-transplant AKI is also known as delayed graft function associated with reduced long-term graft survival and transition to chronic allograft dysfunction. Certainly, kidneys have an intrinsic ability to repair after significant injury. However, this process is inefficient and fails to some extend in these kidneys. Strategies to promote repair processes and minimize associated injury, fibrosis and necrosis are ultimate goals to overcome this devastating disease. MicroRNAs (miRNAs) are a class of small non-coding 18 to 24 nucleotide-long RNAs regulating diverse cellular functions by mRNA degradation and/or inhibition of translation. The relative ease by which miRNAs can be manipulated pharmacologically provides a fascinating therapeutic opportunity. One of the most appealing properties of miRNAs as therapeutic agents and probably the most important advantage in comparison with approaches targeting single genes is their ability to target multiple molecules, frequently in the context of a network, making them extremely efficient in regulating distinct cellular processes relevant to specific clinical phenotypes.miRNA-182-5p is the main driver of AKI and it is strongly correlated with global gene expression changes after ischemic insult. The present project studied the effect of miR-182 inhibition on kidney function after AKI. We show that miR-182-5p is consistently up-regulated after ischemic insult in human kidneys and animal models. Inhibition of miR-182-5p by antisense oligonucleotides (ASO) improves kidney function in rats after AKI. ASO can be successfully applied in an ex-vivo kidney machine perfusion system as well, directly paving the way to translate pre-clinical results into human studies, and thus, ameliorating ischemic acute kidney injury during the process of transplantation.