title: Toll-like receptor 2 mediates fatal immunopathology in mice during treatment of secondary pneumococcal pneumonia following influenza.
abstract: Host inflammatory responses contribute to the significant immunopathology that occurs during treatment of secondary bacterial pneumonia following influenza. We undertook the present study to determine the mechanisms underlying disparate outcomes in a mouse model with β-lactam and macrolide antibiotics. Lysis of superinfecting bacteria by ampicillin caused an extensive influx of neutrophils into the lungs resulting in a consolidative pneumonia, necrotic lung damage, and significant mortality. This was mediated through Toll-like receptor (TLR) 2 and was independent of TLR4 and the Streptococcus pneumoniae cytotoxin pneumolysin. Treatment with azithromycin prevented neutrophil accumulation and rescued mice from subsequent mortality. This effect was independent of the antibacterial activity of this macrolide since dual therapy with ampicillin and azithromycin against an azithromycin-resistant strain also was able to cure secondary pneumonia. These data suggest that strategies for eliminating bacteria without lysis coupled with immunomodulation of inflammation should be pursued clinically.
authors: Department of Infectious Diseases, St Jude Children's Research Hospital, Memphis, TN 38105, USA.
authors: Asa
authors: A
authors: Karlström
authors: Sarah M
authors: SM
authors: Heston
authors: Kelli L
authors: KL
authors: Boyd
authors: Elaine I
authors: EI
authors: Tuomanen
authors: Jonathan A
authors: JA
authors: McCullers
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D005260:Female; D007155:Immunologic Factors / Q000008:administration & dosage*; D008168:Lung / Q000276:immunology / Q000473:pathology; D018942:Macrolides / Q000008:administration & dosage; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009504:Neutrophils / Q000276:immunology; D009976:Orthomyxoviridae Infections / Q000150:complications*; D011018:Pneumonia, Pneumococcal / Q000188:drug therapy / Q000276:immunology* / Q000401:mortality / Q000473:pathology*; D013296:Streptococcus pneumoniae / Q000276:immunology* / Q000472:pathogenicity; D051195:Toll-Like Receptor 2 / Q000276:immunology*; D016896:Treatment Outcome; D047090:beta-Lactams / Q000008:administration & dosage
chemical_list: D000900:Anti-Bacterial Agents; D007155:Immunologic Factors; D018942:Macrolides; C493486:Tlr2 protein, mouse; D051195:Toll-Like Receptor 2; D047090:beta-Lactams