title: Inhibition of nuclear translocation of calcineurin suppresses T-cell activation and prevents acute rejection of donor hearts.
abstract: BACKGROUND
  Inhibition of calcineurin (CnA) activity by cyclosporine A (CsA) is the mainstay in immunosuppressive therapy. CsA inhibits the phosphatase activity of the cytosolic phosphatase CnA and, therefore, prevents the dephosphorylation and subsequently nuclear translocation of the transcription factor nuclear factor of activated T cells (NFAT). However, CsA has multiple other targets within the cell and is, therefore, not specific. We developed a new approach to inhibit CnA/NFAT signaling. This synthetic peptide prevented CnA nuclear translocation in vitro. The purpose of this study was to demonstrate that this novel approach could potentially inhibit T-cell function in vitro and in vivo.
  
  
  METHODS
  T-cell activation (Jurkat T cells, naïve rat T cells, and peripheral human T cells) was assessed by protein synthesis, interleukin (IL)-2 promoter activity, and IL-2 levels after T-cell activation. Immunohistological stainings for CnA were performed to investigate nuclear localization of CnA. The immunosuppressive effects in vivo of the synthetic peptide were investigated in rats with heterotopic transplanted hearts.
  
  
  RESULTS
  The nuclear localization signal peptide significantly decreased alloantigen-specific T-lymphocyte proliferation, IL-2 promoter activity, and IL-2 production (338% ± 27% vs. 149% ± 11%, n=8, P<0.05) in cultured T cells by inhibition of CnA nuclear translocation. The synthetic peptide also significantly decreased the number of graft infiltrating CD8 T lymphocytes. Moreover, treatment with the synthetic inhibitory inhibited acute graft rejection (5 ± 0.6 days vs. 12 ± 2 days, n=10, P<0.05).
  
  
  CONCLUSIONS
  Inhibition of nuclear translocation of CnA is a novel approach to inhibit the activation of the CnA/NFAT signaling cascade. Further studies have to demonstrate the long-term use of this principle in vivo.
authors.affiliation: Department of Medicine I, University of Wuerzburg, Würzburg, Germany.
authors.forename: Franziska
authors.initials: F
authors.lastname: Panther
authors.forename: Jörn
authors.initials: J
authors.lastname: Strasen
authors.forename: Martin
authors.initials: M
authors.lastname: Czolbe
authors.forename: Maria
authors.initials: M
authors.lastname: Lazariotou
authors.forename: Natalie
authors.initials: N
authors.lastname: Burkard
authors.forename: Tatjana
authors.initials: T
authors.lastname: Williams
authors.forename: Volkmar
authors.initials: V
authors.lastname: Lange
authors.forename: Christoph
authors.initials: C
authors.lastname: Otto
authors.forename: Oliver
authors.initials: O
authors.lastname: Ritter
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D000208:Acute Disease; D000595:Amino Acid Sequence; D000818:Animals; D019703:Calcineurin / Q000378:metabolism; D065095:Calcineurin Inhibitors; D006084:Graft Rejection / Q000517:prevention & control*; D016027:Heart Transplantation / Q000276:immunology*; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D008213:Lymphocyte Activation / Q000187:drug effects*; D008969:Molecular Sequence Data; D050778:NFATC Transcription Factors / Q000037:antagonists & inhibitors / Q000502:physiology; D019913:Nuclear Localization Signals / Q000494:pharmacology*; D051381:Rats; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology*; D028961:beta Karyopherins / Q000378:metabolism
chemical_list: D065095:Calcineurin Inhibitors; D007166:Immunosuppressive Agents; C424166:KPNB1 protein, human; D050778:NFATC Transcription Factors; D019913:Nuclear Localization Signals; D028961:beta Karyopherins; D019703:Calcineurin