Anti-IL-2 receptor antibody decreases cytokine-induced apoptosis of human renal tubular epithelial cells (TEC).
BACKGROUND
Transplant rejection is mediated by T-cell activation which is modulated by interleukin-2 (IL-2) binding to IL-2R (CD25). Monoclonal anti-IL-2 receptor antibody is used in renal transplantation to reduce rejection. Interestingly, proximal tubular epithelial cells (TEC) express CD25, similar to T cells. We have demonstrated that IL-2 induces murine TEC apoptosis through down-regulation of the caspase-8 inhibitor protein c-FLIP. Anti-CD25 antibody may be useful clinically to limit renal injury, but this has not been tested in human TEC.


METHODS
Human PT-2 TEC were isolated and cloned from the urine of transplant patients. Apoptosis was determined by FACS with Annexin-V FITC. Protein expression was studied using western blot, and mRNA levels by quantitative real-time (PR-PCR).


RESULTS
We demonstrated that the morphology of a human kidney cell line (PT-2) cloned from urine was consistent with proximal TEC and expresses alkaline phosphatase, cytokeratin, vimentin, CD13, CD26, and low levels of E-cadherin. Basal IL-2 receptor (CD25) was up-regulated by IL-2/IFN-γ stimulation, and cytokine exposure induced apoptosis in a dose-dependent manner. Apoptosis with IL-2/IFN-γ was associated with increased caspase-8 activity and decreased endogenous caspase-8 inhibitor c-FLIP mRNA and protein expression. IL-2/IFN-γ-induced apoptosis could be blocked by pre-treatment of PT-2 with anti IL-2R antibody (basiliximab) but not control IgG antibody.


CONCLUSIONS
These data demonstrate for the first time in human TEC that IL-2 and IFN-γ can induce TEC apoptosis which can be blocked by CD25 blockade antibody. These data suggest that anti-CD25 mAb might similarly attenuate inflammation-induced TEC injury in vivo. Kidney-expressed CD25 may represent a clinically important new target for attenuating early inflammatory injury in donor kidneys and preserving renal function during anti-rejection therapy.
Department of Medicine, University of Western Ontario, London, ON, Canada.
Shuang
S
Wang
Zhu-Xu
ZX
Zhang
Ziqin
Z
Yin
Weihua
W
Liu
Bertha
B
Garcia
Xuyan
X
Huang
Philip
P
Acott
Anthony M
AM
Jevnikar
D000888:Antibodies, Anti-Idiotypic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000276:immunology; D015153:Blotting, Western; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000473:pathology; D005434:Flow Cytometry; D006084:Graft Rejection / Q000276:immunology / Q000517:prevention & control*; D006801:Humans; D007165:Immunosuppression Therapy; D007371:Interferon-gamma / Q000494:pharmacology*; D007376:Interleukin-2 / Q000494:pharmacology*; D007684:Kidney Tubules / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D012333:RNA, Messenger / Q000235:genetics; D015375:Receptors, Interleukin-2 / Q000276:immunology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism
D000888:Antibodies, Anti-Idiotypic; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D007376:Interleukin-2; D012333:RNA, Messenger; D015375:Receptors, Interleukin-2; D007371:Interferon-gamma