Failure of BCL-2 up-regulation in proximal tubular epithelial cells of donor kidney biopsy specimens is associated with apoptosis and delayed graft function.
In renal transplantation, postischemic acute renal failure (ARF) develops in more than 20% of patients. We investigated whether tubular epithelial cells obtained from donor kidneys without subsequent ARF express a different pattern of survival genes, compared with cells from kidneys exhibiting ARF. Donor kidney biopsy specimens were obtained before transplantation from eight recipients of cadaveric kidneys with primary graft function (CAD-PF), eight patients with biopsy-proven ARF without rejection (CAD-ARF), and eight recipients of living donor kidneys with primary graft function (LIV). One thousand proximal tubular epithelial cells per biopsy specimen were isolated by laser capture microdissection. Quantitative analysis of apoptosis and the apoptosis regulatory genes Bcl-2, Bcl-xL, and Bax were performed by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-digoxigenin nick-end labeling staining and real-time PCR, respectively. Primary cultures of human proximal tubular epithelial cells served as calibrator. The number of apoptotic cells was significantly higher in CAD-ARF compared with LIV and CAD-PF (1.5 +/- 1.1% [p < 0.05] vs. 0.3 +/- 0.2% vs. 0.4 +/- 0.2%; mean +/- SD). The apoptosis inhibitors Bcl-2 and Bcl-xL were significantly up-regulated in renal tubular cells of recipients without ARF compared with CAD-ARF. The ratios of Bcl-2/GAPDH normalized to calibrator were as follows: LIV 48 +/- 30, CAD-PF 38 +/- 55, and CAD-ARF 5 +/- 7 (p < 0.05). The corresponding ratios for Bcl-xL were as follows: LIV 6 +/- 6, CAD-PF 5 +/- 3, and CAD-ARF 1 +/- 1 (p < 0.05). No difference in the expression of the proapoptotic Bax could be observed. These data suggest that failure of proximal tubular cells to respond to injury by up-regulation of survival factors from the Bcl-2 family contributes to postischemic ARF in patients after cadaveric renal transplantation.
Department of Internal Medicine III, Division of Nephrology, University of Vienna, Austria.
Christoph
C
Schwarz
Peter
P
Hauser
Rudolf
R
Steininger
Heinz
H
Regele
Georg
G
Heinze
Gert
G
Mayer
Rainer
R
Oberbauer
D017209:Apoptosis / Q000502:physiology*; D001706:Biopsy; D005786:Gene Expression Regulation; D019254:Genes, bcl-2; D006085:Graft Survival / Q000502:physiology*; D006801:Humans; D007668:Kidney; D016030:Kidney Transplantation / Q000502:physiology*; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014019:Tissue Donors; D019459:Urothelium / Q000166:cytology / Q000502:physiology*