title: Gene therapy for tolerance:  high-level expression of donor major histocompatibility complex in the liver overcomes naive and memory alloresponses to skin grafts.
abstract: BACKGROUND
  The liver has long been recognized as having tolerogenic properties. We investigated whether recombinant adenoassociated virus (rAAV)-mediated expression of donor major histocompatibility complex in recipient livers could induce tolerance to donor-strain grafts.
  
  
  METHODS
  Naive B10.BR (H-2) or B10.BR recipients primed with a H-2K-expressing (K) skin graft were injected with rAAV-expressing H-2K (rAAV-K) to induce K expression on hepatocytes 7 days before challenge with a K skin graft. K-specific responses were measured by interferon (IFN)-γ ELISpot and flow cytometric assessment of directly H-2K reactive cells. Fully allogeneic grafts from C57BL/6 (H-2) donors were transplanted onto longstanding B10.BR recipients of K skin to test for linked epitope suppression.
  
  
  RESULTS
  rAAV-K-treated B10.BR mice accepted K skin grafts with increased median survival time (MST) more than 169 days compared to uninoculated (MST=18.5 days) and rAAV-K-treated controls (MST=19 days). rAAV-K-treated B10.BR animals primed with K skin grafts also accepted secondary K skin grafts in the long term (MST>100 days) compared to accelerated rejection in primed, uninoculated mice (MST=12 days). Treatments did not induce liver pathology, assessed by serum alanine aminotransferase levels and histology. IFN-γ ELISpot analysis of splenocytes from rAAV-K-treated mice indicated reduced responses to donor K antigen, but protection was not extended to fully allogeneic C57BL/6 skin or heart grafts, even in recipients that had accepted K skin grafts in the long term.
  
  
  CONCLUSIONS
  High-level expression of donor major histocompatibility complex in recipient livers promotes tolerance to skin allografts, even in animals primed to produce a memory response. This provides proof of concept for an approach using liver-targeted gene delivery for tolerance induction to donor antigen.
authors.affiliation: Collaborative Transplantation Research Group, Bosch Institute, Royal Prince Alfred Hospital and University of Sydney, Australia.
authors.forename: Eithne C
authors.initials: EC
authors.lastname: Cunningham
authors.forename: Szun S
authors.initials: SS
authors.lastname: Tay
authors.forename: Chuanmin
authors.initials: C
authors.lastname: Wang
authors.forename: Michael
authors.initials: M
authors.lastname: Rtshiladze
authors.forename: Zane Z
authors.initials: ZZ
authors.lastname: Wang
authors.forename: Claire
authors.initials: C
authors.lastname: McGuffog
authors.forename: Jonathan
authors.initials: J
authors.lastname: Cubitt
authors.forename: Geoffrey W
authors.initials: GW
authors.lastname: McCaughan
authors.forename: Ian E
authors.initials: IE
authors.lastname: Alexander
authors.forename: Patrick
authors.initials: P
authors.lastname: Bertolino
authors.forename: Alexandra F
authors.initials: AF
authors.lastname: Sharland
authors.forename: David G
authors.initials: DG
authors.lastname: Bowen
authors.forename: G Alex
authors.initials: GA
authors.lastname: Bishop
mesh_terms: D000818:Animals; D000229:Dependovirus / Q000235:genetics; D015316:Genetic Therapy; D006084:Graft Rejection; D006183:H-2 Antigens / Q000032:analysis*; D007108:Immune Tolerance; D007156:Immunologic Memory; D007371:Interferon-gamma / Q000096:biosynthesis; D008099:Liver / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D016038:Skin Transplantation / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology; D014019:Tissue Donors
chemical_list: D006183:H-2 Antigens; C032876:H-2Kb protein, mouse; D007371:Interferon-gamma