Fig. 3: Pulmonary administration of the synthetic TLR7 agonist imiquimod induces emphysema-like alveolar enlargement and apoptosis and impairs lung function in mice.
From: TLR7 promotes smoke-induced experimental lung damage through the activity of mast cell tryptase
a Wild-type (WT) BALB/c mice (female, 6–8 weeks old) were administered low-dose imiquimod (50 μg in 50 μl sterile saline), intranasally (i.n.) 5 times per week, for 8 weeks. Controls received sterile saline. b Quantification of destructive index (n = 6 mice per group) of saline- or imiquimod-administered WT mice. c Quantification of mean linear intercept (n = 6 mice per group) and representative micrographs (right) of hematoxylin and eosin (H&E)-stained lung sections from saline (top panel)- or imiquimod (bottom panel)-administered WT mice. Scale bars, 200 µm. d Quantification of apoptotic cells (n = 6 mice per group) and representative micrographs (right) of TUNEL-stained lung sections from saline (top panel)- or imiquimod (bottom panel)-administered WT mice. Arrows indicate TUNEL+ cells. Scale bars, 20 µm. e Transpulmonary resistance of saline- or imiquimod-administered WT mice (n = 6 mice per group). WT BALB/c mice (female, 6–8 weeks old, n = 8) were challenged with high-dose imiquimod (100 μg in 50 μl sterile saline) intranasally, 5 times per week, for 2 weeks. Controls were challenged with sterile saline. f Total leukocytes, g macrophages, and h lymphocytes in bronchoalveolar lavage fluid (BALF, n = 6 mice per group). mRNA expression of i Cxcl1, j Tnf, k Infar1 were assess in lungs by qPCR (n = 6 mice per group). l Lungs were stained with H&E (scale bar = 50 μm) and m alveolar diameter was assessed (n = 6 mice per group). n Lung function, in terms of transpulmonary resistance was assessed using the flexiVent system (n = 6 mice per group). WT BALB/c mice were administered 5×105 bone-marrow-derived mast cells intranasally from either WT or Tlr7−/− mice. o Neutrophils and p mast cells were counted in BALF 3 days after receiving mast cells (n = 5 mice per group). q WT BALB/c mice were exposed to normal air or CS for 8 weeks and some groups were administered imiquimod (50 μg in 50 μl sterile saline), i.n. 5 times per week, between Week 6 to 8 (for 2 weeks). Controls received sterile saline. r Quantification of the destructive index (n = 6 mice per group) of saline- or imiquimod-administered WT mice exposed to normal air or CS for 8 weeks. s Quantification of mean linear intercept (n = 6 mice per group) and representative micrographs (right) of H&E-stained lung sections from saline (top panel)- or imiquimod (bottom panel)-administered WT mice exposed to normal air (left panel) or CS (right panel) for 8 weeks. Scale bars, 200 µm. t Quantification of apoptotic cells (n = 6 mice per group) and representative micrographs (right) of TUNEL-stained lung sections from saline (top panel)- or imiquimod (bottom panel)-administered WT mice exposed to normal air (left panel) or CS (right panel) for 8 weeks. Arrows indicate TUNEL+ cells. Scale bars, 20 µm. u Transpulmonary resistance of saline- or imiquimod-administered WT mice exposed to normal air or CS for 8 weeks (n = 8 mice per group). All data are presented as means ± s.e.m. and are representative of two independent experiments. For panels b–n statistical analysis was performed using two-tailed Mann–Whitney test. For the rest of the panels, statistical analysis was performed using one-way ANOVA with Bonferroni’s multiple comparison test. Source data are provided as a Source Data file.
