Immunotoxic characterization of a nanoparticle-based inhalable influenza vaccine in murine and human precision cut lung slices

Rationale: Every year influenza viruses cause new outbreaks of respiratory tract infections. The selective pressure on circulating influenza viruses exerted by strain-specific antibody responses drives an antigenic drift of seasonal influenza viruses and leads to pandemics. Therefore there is a growing demand on seasonal influenza vaccines in order to adapt to the current virus strain. An optimal pandemic influenza vaccine should fulfil certain requirements, like an easy and safe administration, strong and effective immune response and a fast and economic way of high amount production in order to allow quick access in times of pandemics. In this study we tested local immunotoxicity of a new nanoparticle-based inhalable influenza vaccine in murine and human precision cut lung slices (PCLS) ex vivo. Methods: Murine and human PCLS were treated with different concentrations of SiO2-nanoparticles, plant-derived influenza H1N1 (A/California /04/09) antigen (HAC1) only or HAC1 antigen formulated with SiO2-nanoparticles (ratio HAC1:SiO2 = 1 %). Tissue vitality was determined by WST-1 assay and live/dead staining. Cytokine secretion was measured by MSD and ELISA assays. Results: Both, murine and human PCLS showed a trend towards attenuation in vitality at high concentrations of SiO2 only or in combination with HAC1. No additional effect in the combined treatment could be observed. However, the highest doses of SiO2 are far above the intended human dosages, but were chosen to determine the limits of our test system. The proinflammatory cytokine TNF-a was not induced by the different treatments. In contrast, IL-8 and murine KC were significantly increased at high SiO2 concentrations of 1000 µg/ml. Additionally, a dose-dependent increase of IL-2 and IFN-y was observed in human PCLS for the antigen and the combined treatment of SiO2-nanoparticles and antigen. Conclusion: The low toxicity and the induced immunoregulatory cytokine profile demonstrate that the formulation of an antigen with SiO 2-nanoparticles is a promising system for pandemic influenza vaccine development.