IL12-mediated liver inflammation reduces the formation of AAV transcriptionally active forms but has no effect over preexisting AAV transgene expression

PLoS One. 2013 Jul 2;8(7):e67748. doi: 10.1371/journal.pone.0067748. Print 2013.


Recombinant adenoassociated viral vectors (rAAV) have proven to be excellent candidates for gene therapy clinical applications. Recent results showed that cellular immunity to AAV represents a major challenge facing the clinical use of systemic administration of these vectors. Interestingly, no preclinical animal model has previously fully reproduced the clinical findings. The aim of the present work was to enhance the T cell immune response against AAV capsid in mice by the administration of a rAAV expressing the immunostimulatory cytokine IL-12. Our results indicate that although IL-12 expression enhanced the AAV capsid-specific immune response it failed to eliminate transduced hepatocytes and long-term expression was achieved. We found that AAV-mediated transgene expression is altered by IL-12-induced liver inflammation. However, IL-12 expression has no effect over preexisting AAV-mediated transgene expression. IL-12 down-regulates AAV mediated transgene expression via induction of IFN-γ production by NK and T cells, but without altering the transduction efficiency measured by viral genomes. Our results indicate that liver inflammation affects the formation of transcriptionally active AAV vector genomes through an unknown mechanism that can be avoided by the use of DNA-demethylating or anti-inflammatory agents.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Capsid / immunology
  • Dependovirus / genetics
  • Dependovirus / immunology*
  • Female
  • Gene Expression / immunology*
  • Genetic Therapy / methods
  • Genetic Vectors / immunology
  • Hepatocytes / immunology*
  • Hepatocytes / pathology
  • Inflammation / genetics
  • Inflammation / immunology
  • Inflammation / pathology
  • Interferon-gamma / genetics
  • Interferon-gamma / immunology
  • Interleukin-12 / genetics
  • Interleukin-12 / immunology*
  • Killer Cells, Natural / cytology
  • Killer Cells, Natural / immunology
  • Liver / immunology*
  • Liver / pathology
  • Mice
  • Mice, Inbred C57BL
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / immunology
  • T-Lymphocytes / cytology
  • T-Lymphocytes / immunology
  • Transcription, Genetic / immunology*
  • Transgenes / immunology


  • Recombinant Fusion Proteins
  • Interleukin-12
  • Interferon-gamma

Grant support

IGF and LV are in receipt of FPI grants, MDS is in receipt of a fellowship from Fondo de Investigaciones Sanitarias. This work was supported by grants from European Union VII Framework program (FP7-health: AIPGENE-2010-261506), UTE project CIMA, Fundación Barrié de la Maza y Condesa de Fenosa, Centro de Investigación Biomédica en Red en el Área temática de Enfermedades Hepáticas y Digestivas Instituto de Salud Carlos III, SAF 2006-03623 and SAF2009-08524 (Ministerio Educación y Ciencia/Ministerio de Ciencia e Innovación) and Fundación Mutua Madrileña. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.