title: APT070 (mirococept), a membrane-localizing C3 convertase inhibitor, attenuates early human islet allograft damage in vitro and in vivo in a humanized mouse model.
abstract: OBJECTIVE
  A major obstacle to islet cell transplantation is the early loss of transplanted islets resulting from the instant blood-mediated inflammation reaction (IBMIR). The activation of complement pathways plays a central role in IBMIR. The aim of this study was to test the inhibitory effect of "painting" human islets with APT070, a membrane-localizing C3 convertase inhibitor, on inflammation evoked by exposure to human serum in vitro and by transplantation in vivo in a humanized diabetic mouse model.
  
  
  METHODS
  In vitro, human islets pre-incubated with APT070 were exposed to allogeneic whole blood. In vivo, similarly treated islets were transplanted underneath the kidney capsule of streptozotocin-induced diabetic NOD-SCID IL2rγ(-/-) mice that had been reconstituted with human CD34(+) stem cells. Complement activation and islet hormone content were assayed using enzyme-linked immunosorbent assays. Supernatants and sera were assayed for cytokines using cytometric beads array. Morphology of the islets incubated with human serum in vitro and in graft-bearing kidney were evaluated using immunofluorescence staining.
  
  
  RESULTS
  Pre-incubation with APT070 decreased C-peptide release and iC3b production in vitro, with diminished deposition of C4d and C5b-9 in islets embedded in blood clots. In vivo, the APT070-treated islets maintained intact structure and showed less infiltration of inflammatory cells than untreated islets. The pretreatments also significantly reduced pro-inflammatory cytokines in supernatants and sera.
  
  
  CONCLUSIONS
  Pre-treatment of islets with APT070 could reduce intra-islet inflammation with accompanying preservation of insulin secretion by beta cells. APT070 could be as a potential therapeutic tool in islet transplantation.
authors.affiliation: Division of Transplantation Immunology and Mucosal Biology, MRC Centre for Transplantation, King's College London, 5th Floor Tower Wing, Guy's Hospital, Great Maze Pond, London, SE1 9RT, UK.
authors.forename: Fang
authors.initials: F
authors.lastname: Xiao
authors.affiliation: Division of Transplantation Immunology and Mucosal Biology, MRC Centre for Transplantation, King's College London, 5th Floor Tower Wing, Guy's Hospital, Great Maze Pond, London, SE1 9RT, UK.
authors.forename: Liang
authors.initials: L
authors.lastname: Ma
authors.affiliation: Department of Diabetes & Endocrinology, King's College London, 2nd Floor, The Rayne Institute, 123 Coldharbour Lane, London, SE5 9NU, UK.
authors.forename: Min
authors.initials: M
authors.lastname: Zhao
authors.affiliation: Division of Transplantation Immunology and Mucosal Biology, MRC Centre for Transplantation, King's College London, 5th Floor Tower Wing, Guy's Hospital, Great Maze Pond, London, SE1 9RT, UK.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Smith
authors.affiliation: Department of Diabetes & Endocrinology, King's College London, 2nd Floor, The Rayne Institute, 123 Coldharbour Lane, London, SE5 9NU, UK.
authors.forename: Guocai
authors.initials: G
authors.lastname: Huang
authors.affiliation: Division of Diabetes & Nutritional Sciences, School of Medicine, King's College London, Guy's Hospital, Great Maze Pond, London, SE1 9RT, UK.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Jones
authors.affiliation: Division of Diabetes & Nutritional Sciences, School of Medicine, King's College London, Guy's Hospital, Great Maze Pond, London, SE1 9RT, UK.
authors.forename: Shanta
authors.initials: S
authors.lastname: Persaud
authors.affiliation: Division of Diabetes & Nutritional Sciences, School of Medicine, King's College London, Guy's Hospital, Great Maze Pond, London, SE1 9RT, UK.
authors.forename: Attilio
authors.initials: A
authors.lastname: Pingitore
authors.affiliation: Division of Transplantation Immunology and Mucosal Biology, MRC Centre for Transplantation, King's College London, 5th Floor Tower Wing, Guy's Hospital, Great Maze Pond, London, SE1 9RT, UK.
authors.forename: Anthony
authors.initials: A
authors.lastname: Dorling
authors.affiliation: Division of Transplantation Immunology and Mucosal Biology, MRC Centre for Transplantation, King's College London, 5th Floor Tower Wing, Guy's Hospital, Great Maze Pond, London, SE1 9RT, UK.
authors.forename: Robert
authors.initials: R
authors.lastname: Lechler
authors.affiliation: Division of Transplantation Immunology and Mucosal Biology, MRC Centre for Transplantation, King's College London, 5th Floor Tower Wing, Guy's Hospital, Great Maze Pond, London, SE1 9RT, UK.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Lombardi
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D050577:Complement C3-C5 Convertases / Q000037:antagonists & inhibitors*; D016207:Cytokines / Q000097:blood / Q000378:metabolism; D006801:Humans; D053631:Interleukin Receptor Common gamma Subunit / Q000235:genetics; D007515:Islets of Langerhans / Q000187:drug effects* / Q000378:metabolism; D016381:Islets of Langerhans Transplantation; D016688:Mice, Inbred NOD; D018345:Mice, Knockout; D016513:Mice, SCID; D014183:Transplantation, Heterologous
chemical_list: D016207:Cytokines; C507942:Il2rg protein, mouse; D053631:Interleukin Receptor Common gamma Subunit; D050577:Complement C3-C5 Convertases