title: Mechanism of accommodation in a sensitized human leukocyte antigen transgenic murine cardiac transplant model.
abstract: BACKGROUND
  Presence of donor-specific antibodies (Abs) is detrimental to posttransplant allograft function. Some sensitized recipients have successfully undergone transplantation after pretransplant conditioning regimen using plasmapheresis and/or intravenous immunoglobulin therapy, but underlying mechanisms that confer such allograft protection are undefined.
  
  
  METHODS
  We developed a single human leukocyte antigen (HLA)-mismatched heterotopic murine heart transplant model (HLA-A2 into HLA-A2-sensitized-C57BL/6) to determine whether pretreatment of donors with low concentration of HLA class I (W6/32) or control Ab (C1.18.4) will confer protection. Expression levels of survival genes, Bcl-2 and heme oxygenase-1, were analyzed by gene array analysis and quantitative real-time polymerase chain reaction. Expression levels of cytokine panel were analyzed by Luminex. Role of Bcl-2 in the induction of allograft protection was analyzed by silencing the Bcl-2 expression in the donor hearts using a small hairpin (shRNA) specific for Bcl-2.
  
  
  RESULTS
  Control Ab-pretreated hearts were rejected in less than 5 days demonstrating hemorrhage, Ab, and C4 deposition. In contrast, W6/32-pretreated hearts were rejected at 15 days (P<0.05) that was prolonged to 25 days with antilymphocyte serum treatment. W6/32-pretreated hearts on day 5 exhibited increased expression of Bcl-2 (5.5-folds), Bcl-xl (5.5-folds), and heme oxygenase-1 (4.4-folds); decreased expression of ICAM-1, VCAM-1 (3.2-fold), along with reduced levels of cytokines interleukin (IL)-1β (4.4-folds), tumor necrosis factor α (3.7-folds), IL-6 (7.5-folds), IL-12 (2.3-folds) and chemokines monocyte chemotactic protein 1 (4.5-folds), MIG (4.4-folds), MIP-1α (3.4-folds), and IL-8 (3.1-folds). Silencing of Bcl-2 in accommodated hearts before transplant resulted in loss of protection with rejection (9±3 vs. 15±2days, P<0.05).
  
  
  CONCLUSIONS
  Pretreatment of hearts with low levels of anti-HLA Abs increases expression of antiapoptotic genes that inhibits caspases, leading to decreased inflammatory cytokines and chemokines, which promote allograft survival.
authors.affiliation: Department of Surgery, Washington University School of Medicine, St. Louis, MO, USA.
authors.forename: Naohiko
authors.initials: N
authors.lastname: Fukami
authors.forename: Sabarinathan
authors.initials: S
authors.lastname: Ramachandran
authors.forename: Kishore
authors.initials: K
authors.lastname: Narayanan
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.forename: Dilip S
authors.initials: DS
authors.lastname: Nath
authors.forename: Martin
authors.initials: M
authors.lastname: Jendrisak
authors.forename: William
authors.initials: W
authors.lastname: Chapman
authors.forename: Thalachallour
authors.initials: T
authors.lastname: Mohanakumar
mesh_terms: D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology / Q000627:therapeutic use*; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006084:Graft Rejection / Q000276:immunology / Q000517:prevention & control*; D006085:Graft Survival / Q000276:immunology*; D006680:HLA Antigens / Q000235:genetics / Q000276:immunology*; D015789:HLA-A2 Antigen / Q000235:genetics / Q000276:immunology; D016027:Heart Transplantation / Q000276:immunology*; D051547:Heme Oxygenase-1 / Q000235:genetics / Q000378:metabolism; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D023421:Models, Animal; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000502:physiology; D013997:Time Factors
chemical_list: D000888:Antibodies, Anti-Idiotypic; D016207:Cytokines; D006680:HLA Antigens; D015789:HLA-A2 Antigen; D019253:Proto-Oncogene Proteins c-bcl-2; D051547:Heme Oxygenase-1