title: A20-mediated modulation of inflammatory and immune responses in aortic allografts and development of transplant arteriosclerosis.
abstract: BACKGROUND
  Transplant arteriosclerosis (TA) is the pathognomonic feature of chronic rejection, the primary cause of allograft failure. We have shown that the NF-κB inhibitory protein A20 exerts vasculoprotective effects in endothelial and smooth muscle cells (SMC), and hence is a candidate to prevent TA. We sought direct proof for this hypothesis.
  
  
  METHODS
  Fully mismatched, C57BL/6 (H2) into BALB/c (H2), aorta to carotid allografts were preperfused with saline, recombinant A20 adenovirus (rAd.A20) or rAd.β-galactosidase (β-gal), implanted, harvested 4 weeks after transplantation, and analyzed by histology, immunohistochemistry, and immunofluorescence staining. We measured indoleamine 2,3-dioxygenase, interleukin-6, and transforming growth factor-β mRNA and protein levels in nontransduced, and rAd.A20 or rAd.β-gal-transduced human SMC cultures after cytokine treatment.
  
  
  RESULTS
  Vascular overexpression of A20 significantly reduced TA lesions. This correlated with decreased graft inflammation and increased apoptosis of neointimal SMC. Paradoxically, T-cell infiltrates increased in A20-expressing allografts, including the immunoprivileged media, which related to A20 preventing indoleamine 2,3-dioxygenase upregulation in SMC. However, infiltrating T cells were predominantly T-regulatory cells (CD25+/Forkhead Box P3 [FoxP3+]). This agrees with A20 inhibiting interleukin-6 and promoting transforming growth factor-β production by medial SMC and in SMC cultures exposed to cytokines, which favors differentiation of regulatory over pathogenic T cells.
  
  
  CONCLUSIONS
  In summary, A20 prevents immune-mediated remodeling of vascular allografts, therefore reduces TA lesions by affecting apoptotic and inflammatory signals and modifying the local cytokine milieu to promote an immunoregulatory response within the vessel wall. This highlights a novel function for A20 in local immunosurveillance, which added to its vasculoprotective effects, supports its therapeutic promise in TA.
authors.affiliation: Division of Vascular and Endovascular Surgery, Center for Vascular Biology Research and the Transplant Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Siracuse
authors.forename: Mark D
authors.initials: MD
authors.lastname: Fisher
authors.forename: Cleide G
authors.initials: CG
authors.lastname: da Silva
authors.forename: Clayton R
authors.initials: CR
authors.lastname: Peterson
authors.forename: Eva
authors.initials: E
authors.lastname: Csizmadia
authors.forename: Herwig P
authors.initials: HP
authors.lastname: Moll
authors.forename: Scott M
authors.initials: SM
authors.lastname: Damrauer
authors.forename: Peter
authors.initials: P
authors.lastname: Studer
authors.forename: Lynn Y
authors.initials: LY
authors.lastname: Choi
authors.forename: Sanah
authors.initials: S
authors.lastname: Essayagh
authors.forename: Elzbieta
authors.initials: E
authors.lastname: Kaczmarek
authors.forename: Elizabeth R
authors.initials: ER
authors.lastname: Maccariello
authors.forename: Andy
authors.initials: A
authors.lastname: Lee
authors.forename: Soizic
authors.initials: S
authors.lastname: Daniel
authors.forename: Christiane
authors.initials: C
authors.lastname: Ferran
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D001011:Aorta / Q000378:metabolism / Q000473:pathology / Q000637:transplantation*; D017209:Apoptosis; D001161:Arteriosclerosis / Q000150:complications / Q000276:immunology* / Q000378:metabolism; D002339:Carotid Arteries / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D002478:Cells, Cultured; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D006084:Graft Rejection / Q000209:etiology / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D007113:Immunity, Innate / Q000276:immunology*; D007249:Inflammation / Q000276:immunology*; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D023421:Models, Animal; D009131:Muscle, Smooth, Vascular / Q000378:metabolism / Q000473:pathology; D014184:Transplantation, Homologous; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3
chemical_list: D016207:Cytokines; D047908:Intracellular Signaling Peptides and Proteins; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3; D003546:Cysteine Endopeptidases; C513261:Tnfaip3 protein, mouse