Fig. 1.

CS-exposed mice are more susceptible to S. pneumoniae. (2 columns).

Mice were chronically exposed to air or CS (5 cigarettes/day, 5 days/week) over a period of 12 weeks to develop symptoms associated to COPD. Mice were then intranasally challenged with S. pneumoniae (Sp) to induce COPD exacerbation or with PBS (Mock) as a control (a). Survival of air and CS-exposed mice was monitored for a week after challenge with 5 × 10⁴ or 5 × 10⁵ CFU of Sp or Mock (b). Absolute numbers of total cells, macrophages, lymphocytes and neutrophils were determined in BAL fluids (c). Neutrophils identified as CD45⁺ F4/80⁻ CD11b⁺ Ly6G⁺ were analyzed in lung tissues 24 h after infection (d). Histological changes were evaluated on lung sections either at 1 or 3 dpi (5 × 10⁴ CFU) (e). CFU counts were evaluated in the BAL, lung tissues and blood at 1, 3 and 7 dpi (f). Data represent as mean ± SEM (n = 48–80 mice per group). *: p < 0.05 or **: p < 0.01 (one-way ANOVA test).