title: Dose/time-dependent modulation of the endothelial function through induction agents: non-depleting versus depleting agents.
abstract: BACKGROUND
  Polyclonal anti-thymocyte globulins (ATGs) and anti-CD25 antibodies are agents used for induction of immunosuppression in solid-organ transplantation. We aimed to investigate the effect of different regimens of these immunosuppressive induction agents on transendothelial migration of peripheral blood mononuclear cells (PBMC) and evaluated the endothelial apoptosis after treatment.
  
  
  METHODS
  Human microvascular endothelial cells were either activated with tumor necrosis factor-α/interferon-γ or not and further treated with 25 or 125 μg/mL ATG (Thymoglobulin, Sanofi-Aventis, Germany) for 2 hours or 24 hours, or with 5 μg/mL Basiliximab (Simulect, Novartis, Germany) for 2 hours or 24 hours. PBMC were either activated with phytohaemagglutinin (PHA) or not and further treated with 25 or 125 μg/mL ATG or with 5 μg/mL Basiliximab for 2 h and then used for transendothelial migration assays. Apoptosis of endothelial cells was detected by means of Annexin-V staining after 2-hour incubation with either 25 or 125 μg/mL ATG or 5 μg/mL Basiliximab.
  
  
  RESULTS
  Prophylactic 24-hour administration of ATG to naive endothelial cells without PBMC treatment reduced transendothelial migration. Prophylactic 24-hour administration of ATG and Basiliximab to naive endothelial cells after PBMC treatment with the same agents reduced the transendothelial migration after 24 hours. In both cases, no effect could be observed after 2-hour treatment. Basiliximab but not ATG showed a reduction of transmigration after 2-hour treatment of PBMCs without naive EC treatment. Apoptosis of endothelial cells after treatment increased in both cases, being in case of ATG dose-dependent, increasing from 1.2% after either 25 μg/mL ATG to 8.7% after 125 μg/mL ATG.
  
  
  CONCLUSIONS
  Immunosuppressive induction agents modulate the endothelial activity in a dose- and time-dependent manner. Our results suggest that administration of induction agents over longer time periods could provide a potential benefit regarding endothelial immunomodulation. Increased doses may, however, show a deleterious effect on endothelial survival.
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, Johann Wolfgang Goethe University Hospital, Frankfurt/Main, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Werner
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, Johann Wolfgang Goethe University Hospital, Frankfurt/Main, Germany.
authors.forename: N V
authors.initials: NV
authors.lastname: Bogert
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, Johann Wolfgang Goethe University Hospital, Frankfurt/Main, Germany.
authors.forename: U A
authors.initials: UA
authors.lastname: Stock
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, Johann Wolfgang Goethe University Hospital, Frankfurt/Main, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Moritz
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, Johann Wolfgang Goethe University Hospital, Frankfurt/Main, Germany. Electronic address: Andres.Beiras@kgu.de.
authors.forename: A
authors.initials: A
authors.lastname: Beiras-Fernandez
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology* / Q000627:therapeutic use; D000961:Antilymphocyte Serum / Q000494:pharmacology* / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects*; D000077552:Basiliximab; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects*; D006084:Graft Rejection / Q000276:immunology / Q000517:prevention & control; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology* / Q000627:therapeutic use; D007963:Leukocytes, Mononuclear / Q000187:drug effects*; D011993:Recombinant Fusion Proteins / Q000494:pharmacology* / Q000627:therapeutic use; D013997:Time Factors; D057705:Transendothelial and Transepithelial Migration / Q000187:drug effects*
chemical_list: D000911:Antibodies, Monoclonal; D000961:Antilymphocyte Serum; D007166:Immunosuppressive Agents; D011993:Recombinant Fusion Proteins; D000077552:Basiliximab; C512542:thymoglobulin