title: Transient depletion of specific immune cell populations to improve adenovirus-mediated transgene expression in the liver.
abstract: OBJECTIVE
  Adenoviral (Ad) vectors are currently one of the most efficient tools for in vivo gene transfer to the liver. However, anti-Ad immune responses limit the safety and efficacy of these vectors. The initial inflammatory reaction is a concern in terms of toxicity, and it favours the development of cellular and humoral responses leading to short transgene persistence and inefficient vector re-administrations. Therefore, safe and simple ways to interfere with these processes are needed. Study ways to deplete specific immune cell populations and their impact on liver-directed gene transfer.
  
  
  METHODS
  First-generation Ad vectors encoding reporter genes (luciferase or β-galactosidase) were injected intravenously into Balb/c mice. Kupffer cells and splenic macrophages were depleted by intravenous administration of clodronate liposomes. B lymphocytes, CD4(+) , CD8(+) T lymphocytes or NK cells were depleted by intraperitoneal injection of anti-M plus anti-D, anti-CD4, anti-CD8 or anti-asialo-GM1 antibodies respectively. Long-term evolution of luciferase expression in the liver was monitored by bioluminescence imaging.
  
  
  RESULTS
  The anti-CD4 monoclonal antibody impaired cellular and humoral immune responses, leading to efficient vector re-administration. Clodronate liposomes had no impact on humoral responses but caused a 100-1000 fold increase in liver transduction, stabilized transgene expression, reduced the concentration of inflammatory cytokines, and inhibited lymphocyte activation.
  
  
  CONCLUSIONS
  Transient CD4(+) T-cell depletion using antibodies is a clinically feasible procedure that allows efficient Ad redosing. Systemic administration of clodronate liposomes may further increase the safety and efficacy of vectors.
authors.affiliation: Division of Hepatology and Gene Therapy, CIMA, Foundation for Applied Medical Research, University of Navarra, Pamplona, Spain.
authors.forename: Pilar
authors.initials: P
authors.lastname: Alzuguren
authors.forename: Sandra
authors.initials: S
authors.lastname: Hervas-Stubbs
authors.forename: Gloria
authors.initials: G
authors.lastname: Gonzalez-Aseguinolaza
authors.forename: Joanna
authors.initials: J
authors.lastname: Poutou
authors.forename: Puri
authors.initials: P
authors.lastname: Fortes
authors.forename: Uxua
authors.initials: U
authors.lastname: Mancheno
authors.forename: Maria
authors.initials: M
authors.lastname: Bunuales
authors.forename: Cristina
authors.initials: C
authors.lastname: Olagüe
authors.forename: Nerea
authors.initials: N
authors.lastname: Razquin
authors.forename: Nico
authors.initials: N
authors.lastname: Van Rooijen
authors.forename: Monica
authors.initials: M
authors.lastname: Enguita
authors.forename: Ruben
authors.initials: R
authors.lastname: Hernandez-Alcoceba
mesh_terms: D000256:Adenoviridae / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects* / Q000276:immunology; D002478:Cells, Cultured; D004002:Clodronic Acid / Q000494:pharmacology; D005260:Female; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D005822:Genetic Vectors; D056724:Immunity, Humoral / Q000187:drug effects; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D008099:Liver / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D008156:Luciferases / Q000096:biosynthesis / Q000235:genetics; D008212:Lymphocyte Depletion / Q000379:methods*; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D013997:Time Factors; D014161:Transduction, Genetic; D019076:Transgenes; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000235:genetics
chemical_list: D000906:Antibodies; D007166:Immunosuppressive Agents; D004002:Clodronic Acid; D008156:Luciferases; D001616:beta-Galactosidase
keywords: B cells; CD4+ T cells; CD8+ T cells; Kupffer cells; NK cells; adenovirus; clodronate liposomes; immunosuppression; monoclonal antibodies; neutralizing antibodies