Dr PY Mia Leung1,2, Dr Ali Graver1,2, Dr Marina Katerelos1,2, Professor David Power1,2, Associate Professor John B. Whitlam1,2, Professor Peter Mount1,2
1Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Australia, 2Department of Nephrology, Austin Health, Heidelberg, Australia
Biography:
I am completing a PhD through the Department of Medicine, University of Melbourne, under the supervision of Prof Peter Mount and A/Prof John Whitlam. My research is focussed on protein expression in urinary extracellular vesicles to understand kidney pathophysiology. I am currently a nephrologist at Austin Health working in kidney transplant and glomerulonephritis clinics.
Aim:
To determine whether expression of glycolysis regulators in urinary extracellular vesicles (UEV) from kidney allografts can be used to monitor kidney injury.
Background:
Metabolic reprogramming to increased glycolysis has been demonstrated in experimental kidney injury but not in kidney allografts. A critical enzyme controlling glycolysis is phosphofructokinase, which itself is regulated by 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase (including PFKFB2, PFKFB3, PFKFB4 isoforms).
Methods:
Urine samples were collected prospectively from kidney transplant recipients at the time of indication biopsy (n=51), or early post-transplant at Day 1 and 7 (n=55) and compared with healthy controls (n=32). UEV were separated by differential ultracentrifugation. UEV markers and glycolytic control proteins were assayed by immunoblotting.
Results:
In the indication biopsy cohort, UEV from recipients with T cell-mediated rejection (“TCMR”), comprising 6 TCMR and 1 borderline TCMR, had PFKFB4 detected in 5/7 (71%) compared to 10/44 (23%) of No-TCMR cases (p=0.018). Early post-transplant, glycolytic control proteins (PFK-L, PFKFB2 PFKFB3 and PFKFB4) were significantly elevated at both Day 1 and 7. Delayed graft function was associated with 2.0-fold increase in PFKFB2 (p=0.013) and 3.4-fold increase in PFKFB3 (p=0.0004) on Day 1. PFKFB2 and PFKFB3 (Day 1) also correlated with the creatinine reduction ratio (Spearman r=-0.44 p=0.041; r=-0.64, p=0.0012) and ischaemia time (r=0.55, p=0.0054; r=0.62, p=0.0011).
Conclusions:
Enzymes controlling the phosphofructokinase step, which powerfully promote glycolysis, were elevated in association with TCMR and post-transplant ischaemia severity. This suggests a switch to glycolysis as a source of energy following these injuries. The apparent specificity of increases in PFKFB enzymes suggests a novel cellular response and may be a possible monitoring tool.
Presentation Slides PDF – Click Here