Adenovirus vector delivery stimulates natural killer cell recognition

Area of Science:

• Immunology
• Gene Therapy

Background:

• First-generation replication-deficient adenovirus (RDAd) vectors are utilized for gene delivery.
• The immune response to RDAd vectors, particularly concerning innate immunity, requires further elucidation.
• Natural killer (NK) cells are crucial components of the innate immune system involved in pathogen defense and tumor surveillance.

Purpose of the Study:

• To investigate the effect of RDAd vector delivery into primary human fibroblasts on NK cell activity.
• To identify the specific NK cell populations and receptors involved in the observed cytolysis.
• To determine if vector integrity influences the induction of NK cell-mediated responses.

Main Methods:

• Primary human fibroblasts were exposed to RDAd vectors in vitro.
• Cytolytic activity of various NK cell populations (NKL clone, polyclonal lines, autologous clones) against fibroblasts was assessed.
• Antibody blocking assays were performed using antibodies against the NK-activating receptor NKG2D.
• Gamma-irradiation was used to inactivate the RDAd vectors before delivery.

Main Results:

• RDAd vector delivery induced significant NK cell-mediated cytolysis of primary human fibroblasts.
• This cytolysis was mediated by diverse NK cell populations, including specific clones and polyclonal lines.
• Inhibition of the NKG2D receptor with blocking antibodies significantly reduced adenovirus-induced cytolysis.
• Gamma-irradiation of the RDAd vector completely abolished the induction of cytolysis.

Conclusions:

• RDAd vectors can directly trigger NK cell-mediated killing of target cells in vitro.
• The NK-activating receptor NKG2D plays a critical role in mediating this adenovirus-induced cytolysis.
• Breakthrough expression from intact RDAd vectors likely contributes to the pro-inflammatory responses observed during in vivo gene delivery, as gamma-irradiation eliminates this effect.