Fig. 4

Silica synergizes with influenza viruses to exacerbate lung injury in mice. (A) Schematic diagram showing the synergistic instillation of nanoparticles and influenza viruses. Nanoparticles were injected at a dose of 30 mg/kg body weight. Mice were infected with H5N1 and H1N1 viruses (TCID₅₀ = 10⁶) at a dose of 4 mL/kg body weight 2 days after nanoparticle injection. Mice were sacrificed, and lung tissues were harvested on day 5 (n = 3 to 5 per group). (B) Body weights were recorded each day during the nanoparticle and influenza virus synergistic exposure experiments. (C) Lung wet/dry ratio. (D) Representative images of H&E staining. The histopathological scores of lung injury and the numbers of infiltrating neutrophils per microscopic field (n = 30–40 fields per lung section) are shown in the right panel. Scale bars, 50 μm. The data are presented as the mean ± S.E.M. of three independent experiments. *, P < 0.05; **, P < 0.01;***, P < 0.001