title: The suppression of inflammatory macrophage-mediated cytotoxicity and proinflammatory cytokine production by transgenic expression of HLA-E.
abstract: BACKGROUND
  Macrophages participate in xenogenic rejection and represent a major biological obstacle to successful xenotransplantation. The signal inhibitory regulatory protein α (SIRPα) receptor was reported to be a negative regulator of macrophage phagocytic activity via interaction with CD47, its ligand. Because a majority of human macrophages express the inhibitory receptor CD94/NKG2A, which binds specifically to the human leukocyte antigen (HLA)-E and contains immunoreceptor tyrosine-based inhibition motifs (ITIMs), the inhibitory function of HLA class I molecules, HLA-E, on macrophage-mediated cytolysis was examined. The suppressive effect against proinflammatory cytokine production by macrophages was also examined.
  
  
  METHODS
  Complementary DNA (cDNA) of HLA-E, and CD47 were prepared and transfected into swine endothelial cells (SEC). The expression of the modified genes was evaluated by flow cytometry and macrophage-mediated cytolysis was assessed using in vitro generated macrophages.
  
  
  RESULTS
  Transgenic expression of HLA-E significantly suppressed the macrophage-mediated cytotoxicity. HLA-E transgenic expression demonstrated a significant suppression equivalent to CD47 transgenic expression. Furthermore, transgenic HLA-E suppressed the production of pro-inflammatory cytokines by inflammatory macrophages.
  
  
  CONCLUSIONS
  These results indicate that generating transgenic HLA-E pigs might protect porcine grafts from, not only NK cytotoxicity, but also macrophage-mediated cytotoxicity.
authors.affiliation: Department of Surgery, Osaka University Graduate School of Medicine, Osaka, Japan. Electronic address: amaeda@orgtrp.med.osaka-u.ac.jp.
authors.forename: Akira
authors.initials: A
authors.lastname: Maeda
authors.forename: Takuji
authors.initials: T
authors.lastname: Kawamura
authors.forename: Takehisa
authors.initials: T
authors.lastname: Ueno
authors.forename: Noriaki
authors.initials: N
authors.lastname: Usui
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Eguchi
authors.forename: Shuji
authors.initials: S
authors.lastname: Miyagawa
mesh_terms: D000818:Animals; D051928:CD47 Antigen / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D002460:Cell Line; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D042783:Endothelial Cells / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D015870:Gene Expression; D064593:Heterografts; D015395:Histocompatibility Antigens Class I / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D006801:Humans; D007249:Inflammation; D018836:Inflammation Mediators / Q000276:immunology* / Q000378:metabolism; D008264:Macrophages / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D016377:Organ Transplantation; D013552:Swine; D019076:Transgenes; D023001:Transplantation Tolerance; D000097625:HLA-E Antigens
chemical_list: D051928:CD47 Antigen; D016207:Cytokines; D015395:Histocompatibility Antigens Class I; D018836:Inflammation Mediators; D000097625:HLA-E Antigens; C497894:CD47 protein, human
keywords: HLA-E; Immunoreceptor tyrosine-based inhibition motif (ITIM); Inflammatory macrophage; Pro-inflammatory cytokine; Xenocytotoxicity