SRS237 - Inhibition of the NLRP3 inflammasome improves functional outcomes and decreases expression of the inflammatory cytokines IL-1b and IL-18 during normothermic machine perfusion of human kidneys

Abstract Background Assembly and activation of the NLRP3 inflammasome is a critical mechanism in renal ischaemia reperfusion injury (IRI). NLRP3 activation leads to caspase-1 dependent release of the pro-inflammatory cytokines IL-1b and IL-18 and pyroptotic cell death. This study investigates the effects of the selective NLRP3 inhibitor MCC950 on renal IRI using normothermic machine perfusion (NMP) as a platform for targeted drug delivery. Methods Dose-response and cytokine release assays were performed using in vitro organ culture. Transplant-declined human kidneys (n = 4 control and n = 4 treatment) were allocated to 4h of NMP using a red cell-based perfusate with or without 100 mM of MCC950. Renal blood flow (RBF) and urine output (UO) were monitored continuously. Renal biopsies taken at the start and end of NMP were studied in an organ culture model of IRI. Results During NMP, MCC950 inhibition of NLRP3 increased RBF and UO (P < 0.050). Perfusate levels of IL-1b and IL-18 and other pro-inflammatory cytokines were decreased in MCC950 treated kidneys (P < 0.050). Organ culture of NMP kidney biopsies submitted to IRI demonstrated that NLRP3 inhibition with MCC950 reduced IL-1b to nearly undetectable levels (P = 0.0002) and significantly reduced IL-18 (P = 0.0373) release into the culture media. Conclusions NLRP3 inflammasome inhibition during NMP reduces renal IRI. The direct delivery of therapies to kidneys during NMP eliminates problem of targeting to the organ of interest and reduces the risk of off-target adverse effects in the recipient. This strategy has potential to better prepare kidneys prior to transplantation and should be evaluated in a clinical trial.