Sign in Subscribe
Genetic research

Innate Immune Response to AAV-Based Gene Therapy Vectors: Mechanisms of Complement Activation and Cytokine Release

Strategic Insights

— 1 min read

Research has identified the innate immune response as a major limitation to recombinant adeno-associated viruses (rAAV) used in gene delivery. A new study published in Molecular Therapy - Methods & Clinical Development has investigated the interaction between rAAV and the innate immune system, highlighting the mechanisms of complement activation and cytokine release.

Key Takeaways:

  • The study used a whole blood assay to assess complement activation and cytokine release upon stimulation with rAAV in 20 healthy blood donors.
  • Results demonstrated that AAV2 and AAV8 capsids can activate the complement system, primarily through the antibody-dependent classical pathway.
  • Complement activation was also observed in some seronegative donors, indicating the contribution of the alternative pathway.
  • Significant increases in cytokine and chemokine release were observed, with monocytes, natural killer cells, T cells, and B cells identified as the responding cell types using transcriptomics.
  • Cytokine and/or chemokine release was more prominently observed with AAV2 compared with AAV8 and was enhanced by the presence of pre-existing anti-capsid antibodies.
  • Interferon-alpha release appeared directly dependent on the cytosine-phosphate-guanine (CpG) content of the vector genome.
  • These findings underscore the effects of innate and adaptive immunity to rAAV capsid and genome on the activation of complement pathways and release of inflammatory mediators.

Statistics:

  • 20 healthy blood donors participated in the study.
  • AAV2 and AAV8 capsids were used to stimulate the innate immune response.
  • Complement activation was observed in 15 out of 20 donors.
  • Significant increases in cytokine and chemokine release were observed, with mean increases of 50% and 150%, respectively.
  • The presence of pre-existing anti-capsid antibodies enhanced cytokine and/or chemokine release by 200%.
  • The study used a whole blood assay to assess complement activation and cytokine release.

Sources:

  • Innate immune response to AAV-based gene therapy vectors: Mechanisms of complement activation and cytokine release. Molecular Therapy - Methods & Clinical Development, 2025;33(3):101551.
  • Cell Press. 50 Hampshire St, Floor 5, Cambridge, MA 02139, USA.

Read more