Anti-IL-2 receptor antibody decreases cytokine-induced apoptosis of human renal tubular epithelial cells (TEC)

Nephrol Dial Transplant. 2011 Jul;26(7):2144-53. doi: 10.1093/ndt/gfq714. Epub 2010 Dec 2.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Anti-Idiotypic / pharmacology*
  • Apoptosis / drug effects*
  • Apoptosis / immunology
  • Blotting, Western
  • CASP8 and FADD-Like Apoptosis Regulating Protein / genetics
  • CASP8 and FADD-Like Apoptosis Regulating Protein / metabolism
  • Cells, Cultured
  • Epithelial Cells / pathology
  • Flow Cytometry
  • Graft Rejection / immunology
  • Graft Rejection / prevention & control*
  • Humans
  • Immunosuppression
  • Interferon-gamma / pharmacology*
  • Interleukin-2 / pharmacology*
  • Kidney Tubules / drug effects
  • Kidney Tubules / metabolism
  • Kidney Tubules / pathology*
  • RNA, Messenger / genetics
  • Receptors, Interleukin-2 / immunology*
  • Reverse Transcriptase Polymerase Chain Reaction
  • T-Lymphocytes / drug effects
  • T-Lymphocytes / metabolism

Substances

  • Antibodies, Anti-Idiotypic
  • CASP8 and FADD-Like Apoptosis Regulating Protein
  • CFLAR protein, human
  • Interleukin-2
  • RNA, Messenger
  • Receptors, Interleukin-2
  • Interferon-gamma