Figure 5.

Weight loss, neutrophils recruitment, and bacteria in blood and macrophage activation of secondary infected mice are reduced after CXCR1/2 treatment. Mice were infected with influenza A virus (IAV) (500 PFU, i.n.) and after 3, 4, 5, and 6 days of infection were treated twice a day with DF2162 (10 mg/kg—oral gavage) or the vehicle of the drug. After 14 days of IAV infection, mice were secondary infected with Streptococcus pneumoniae (10³ CFU, i.n.). Single infections were also performed. Mock mice were instilled (i.n.) with PBS. The lethality [(A), n = 7–9 mice per group, representative of three independent experiment] and weight loss [(B), n = 20–35 mice per group, compilation of three independent experiments] were accompanied. In another experiment, mice under the same treatments and infection conditions were euthanized after 48 h after the second infection. Number of total leukocytes (C) and neutrophils (D) in the airways, neutrophils in the lungs [(E)— myeloperoxidase assay (MPO) assay] and bacteria in BALF (F) or in blood (G) were accessed (n = 4–6 mice per group, representative of two independent experiments). In another experiment, IAV-infected mice treated with vehicle or DF2162 as above were euthanized after 14 days; alveolar macrophages recovered from BALF were ex vivo infected with S. pneumoniae (MOI 1:10); after 24 h supernatant was collected for CXCL1 measurement (H). The results are presented as mean ± SEM. *P < 0.05; **P < 0.01, and ***P < 0.001 when compared to Mock group; ^##P < 0.01 and ^###P < 0.001 when compared to Vehicle group.