OPTIMIZING IMMEDIATE GRAFT FUNCTION IN KIDNEY TRANSPLANTATION

N. Rogers¹, M. Stephenson², S. Kireta³, P.T. Coates^4
1Central Northern Adelaide Renal And Transplantation Services, The Royal Adelaide Hospital, Adelaide/SA/AUSTRALIA, ²Transplant Immunology Laboratory, The Basil Hetzel Centre for Medical Research, Adelaide/AUSTRALIA, ³Transplant Immunology Laboratory, Hanson Centre for Research, Adelaide/AUSTRALIA, ⁴Central Northern Adelaide Renal And Transplantation Service, Royal Adelaide Hospital, Adelaide/AUSTRALIA

Body:
Liposomal curcumin ameliorates renal ischaemia-reperfusion injury via NFkB inhibition and anti-oxidant pathways. Introduction Ischaemia-reperfusion injury (IRI) in an inevitable consequence of transplantation and results from prolonged oxidative stress. Prophylactic treatment with extracellular antioxidants has been unsuccessful in significantly limiting IRI. Curcumin, a lipophilic extract of turmeric, is a novel agent with anti-oxidant and anti-inflammatory activity. We hypothesized that liposomal curcumin would provide targeted intracellular delivery and limit both biochemical and functional aspects of IRI. Methods Liposomes were synthesised with egg phosphatidylcholine, using thin film evaporation and hydration, followed by extrusion under nitrogen pressure to produce uniform size. Incorporation of curcumin was confirmed by UV spectrophotometry (wavelength 460nm) and liposome size (400nm) was measured using a zetasizer. The final concentration of curcumin was 2mM. Liposomes were fluorescently labelled and injected into mice to assess distribution and cellular uptake using flow cytometry and immunofluorescence. Liposomes, with or without curcumin, were injected into male C57BL/6 mice 24 hours prior to 30 minutes bilateral renal ischaemia and reperfusion after 4 or 24 hours. Serum urea and creatinine, histologic damage, apoptosis and markers of oxidative stress were measured Results Liposomes were taken up by renal tubular and antigen-presenting cells (APC), particularly CD11c-CD11b+F4/80+ macrophages, CD11c+B220+ and CD11c+CD8a+ myeloid DC, and CD11c+PDCA-1 plasmacytoid DC. APC exposed in vivo to liposomal curcumin were isolated and incubated ex vivo with lipopolysaccharide, and showed decreased NFkB expression and nuclear translocation (detected by immunofluorescence) compared to controls. Pre-treatment of mice with curcumin liposomes decreased serum urea and creatinine levels by >50% at 4h and 24 hours reperfusion (p<0.01). Salvage of renal function was accompanied by less severe histologic injury (blinded, semi-quantitative grading of tubular infarction and cast formation), decreased apoptosis (detected by TUNEL staining) and significantly reduced TLR4, HSP70 and TNFa mRNA expression. Juxta-medullary neutrophil infiltration was significantly lower (50% reduction in absolute cell numbers, p<0.01), as was mRNA expression of chemokine markers RANTES and fractalkine. Intracellular superoxide generation was reduced (detected by dihydroethidine staining) and superoxide dismutase levels (mRNA) were near-normalised in curcumin-treated mice. Expression of inducible nitric oxide synthase mRNA was decreased, together with immunofluorescent staining for 3-nitrotyrosine, consistent with limitation of nitrosative stress. Curcumin-treated mice also expressed lower levels of thioredoxin-interacting protein (detected by immunofluorescence and mRNA) compared to controls. Conclusion 1] Liposomal curcumin is a novel delivery method of a non-toxic NFkB inhibitor that improves biochemical and histological manifestations of renal IRI. 2] The effects are mediated by a reduction in oxidative stress markers. This approach would merit clinical translation.

Disclosure: All authors have declared no conflicts of interest.