title: Prolongation of cardiac allograft survival by inhibition of ERK1/2 signaling in a mouse model.
abstract: BACKGROUND
  It has been demonstrated that in vitro the presence of extracellular signal-regulated kinase 1 and 2 (ERK1/2) signaling inhibitor suppresses T cell activation and Th1 development. However, pharmacological interference of ERK1/2 signaling by administration of its small molecule inhibitor has not been tested as a therapeutic target in the prevention of allograft rejection.
  
  
  METHODS
  The immunosuppressive effect of targeting ERK1/2 signaling was tested on cardiac allograft survival in C57BL/6 (H-2b) to Balb/c (H-2d) murine model using PD98059 inhibitor. Phosphorylation/activation of ERK 1/2 and STAT6 proteins were assessed by Western blot.
  
  
  RESULTS
  Blockade of ERK1/2 using PD98059 had significant immunosuppressive effect and prolonged survival of mouse cardiac allografts from 8.3+/-0.5 days (vehicle) to 12.6+/-1.3 days (100 mg/kg PD98059; P<0.0001). Combination therapy of PD98059 (100 mg/kg) with cyclosporine (CsA, 15 mg/kg for 20 days) additionally enhanced graft survival (34.4+/-1.2 days) compared to CsA (14.9+/-1.1 days; P<0.0001) or PD98059 monotherapy (P<0.0001). Attenuation of graft rejection by PD98059 correlated to reduction of intragraft ERK phosphorylation and leukocyte infiltration, and to increase in interleukin (IL)-4 or decrease in interferon-gamma production within the grafts. In vitro inhibition of ERK1/2 by PD98059 promoted Th2 differentiation by upregulation IL-4 production but not altering IL-4 stimulating STAT6 pathway.
  
  
  CONCLUSIONS
  Targeting ERK1/2 signaling results in suppression of alloimmune responses by an unique mechanism that involves Th1/Th2 skewing, suggesting a therapeutic potential of inhibition of ERK1/2 signaling for transplant rejection, particularly in combination with CsA.
authors.affiliation: Department of Medicine, The University of Western Ontario, London, Ontario, Canada.
authors.forename: Shuang
authors.initials: S
authors.lastname: Wang
authors.forename: Qiunong
authors.initials: Q
authors.lastname: Guan
authors.forename: Hong
authors.initials: H
authors.lastname: Diao
authors.forename: Dameng
authors.initials: D
authors.lastname: Lian
authors.forename: Robert
authors.initials: R
authors.lastname: Zhong
authors.forename: Anthony M
authors.initials: AM
authors.lastname: Jevnikar
authors.forename: Caigan
authors.initials: C
authors.lastname: Du
mesh_terms: D000818:Animals; D016572:Cyclosporine / Q000627:therapeutic use; D004347:Drug Interactions; D004359:Drug Therapy, Combination; D005419:Flavonoids / Q000494:pharmacology / Q000627:therapeutic use; D006084:Graft Rejection / Q000201:enzymology / Q000517:prevention & control*; D006085:Graft Survival / Q000187:drug effects; D016027:Heart Transplantation; D007165:Immunosuppression Therapy / Q000379:methods*; D007371:Interferon-gamma / Q000378:metabolism; D015847:Interleukin-4 / Q000378:metabolism; D008213:Lymphocyte Activation / Q000187:drug effects; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors*; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology / Q000627:therapeutic use*; D015398:Signal Transduction / Q000187:drug effects; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D018418:Th2 Cells / Q000187:drug effects / Q000276:immunology
chemical_list: D005419:Flavonoids; D047428:Protein Kinase Inhibitors; D015847:Interleukin-4; D007371:Interferon-gamma; D016572:Cyclosporine; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one