Molecular Therapy: Methods & Clinical Development (Sep 2023)

Innate and adaptive AAV-mediated immune responses in a mouse model of Duchenne muscular dystrophy

  • Michael R. Emami,
  • Alejandro Espinoza,
  • Courtney S. Young,
  • Feiyang Ma,
  • Philip K. Farahat,
  • Philip L. Felgner,
  • Jeffrey S. Chamberlain,
  • Xiangmin Xu,
  • April D. Pyle,
  • Matteo Pellegrini,
  • S. Armando Villalta,
  • Melissa J. Spencer

Journal volume & issue
Vol. 30
pp. 90 – 102

Abstract

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High systemic doses of adeno-associated viruses (AAVs) have been associated with immune-related serious adverse events (SAEs). Although AAV was well tolerated in preclinical models, SAEs were observed in clinical trials, indicating the need for improved preclinical models to understand AAV-induced immune responses. Here, we show that mice dual-dosed with AAV9 at 4-week intervals better recapitulate aspects of human immunity to AAV. In the model, anti-AAV9 immunoglobulin G (IgGs) increased in a linear fashion between the first and second AAV administrations. Complement activation was only observed in the presence of high levels of both AAV and anti-AAV IgG. Myeloid-derived pro-inflammatory cytokines were significantly induced in the same pattern as complement activation, suggesting that myeloid cell activation to AAV may rely on the presence of both AAV and anti-AAV IgG complexes. Single-cell RNA sequencing of peripheral blood mononuclear cells confirmed that activated monocytes were a primary source of pro-inflammatory cytokines and chemokines, which were significantly increased after a second AAV9 exposure. The same activated monocyte clusters expressed both Fcγ and complement receptors, suggesting that anti-AAV-mediated activation of myeloid cells through Fcγ receptors and/or complement receptors is one mechanism by which anti-AAV antigen complexes may prime antigen-presenting cells and amplify downstream immunity.

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