title: The effects of Escherichia coli capsule, O-antigen, host neutrophils, and complement in a rat model of Gram-negative pneumonia.
abstract: Gram-negative enteric bacilli are agents of life-threatening pneumonia. The role of the bacterial capsule and O-antigen moiety of lipopolysaccharide in the pathogenesis of Gram-negative pneumonia was assessed. In a rat model of pneumonia the LD(50) of a wild-type extraintestinal pathogenic Escherichia coli strain (CP9) was significantly less than its isogenic derivatives deficient in capsule (CP9.137), O-antigen (CP921) or both capsule and O-antigen (CP923) (P< or =0.003). Studies using complement depleted or neutropenic animals established that both neutrophils and complement are important for the pulmonary clearance of E. coli. Data from these studies also support that capsule and O-antigen serve, at least in part, to counter the complement and neutrophil components of the pulmonary host defense response. Lastly, the contribution of E. coli versus neutrophils in causing lung injury was examined. Findings suggest that E. coli virulence factors and/or non-neutrophil host factors are more important mediators of lung injury than neutrophils. These findings extend our understanding of Gram-negative pneumonia and have treatment implications.
authors.affiliation: Department of Medicine, Division of Infectious Diseases, 3435 Main St., Biomedical Research Building, Room 141, Buffalo, NY 14214, USA. trusso@acsu.buffalo.edu
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Russo
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Davidson
authors.forename: Ulrike B
authors.initials: UB
authors.lastname: Carlino-MacDonald
authors.forename: Jadwiga D
authors.initials: JD
authors.lastname: Helinski
authors.forename: Roger L
authors.initials: RL
authors.lastname: Priore
authors.forename: Paul R
authors.initials: PR
authors.lastname: Knight
mesh_terms: D000818:Animals; D016667:Bacterial Capsules / Q000502:physiology; D003165:Complement System Proteins / Q000276:immunology*; D004195:Disease Models, Animal; D004926:Escherichia coli / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000276:immunology* / Q000382:microbiology; D005798:Genes, Bacterial; D016254:Mutagenesis, Insertional; D009504:Neutrophils / Q000276:immunology*; D019081:O Antigens / Q000502:physiology; D018410:Pneumonia, Bacterial / Q000276:immunology* / Q000382:microbiology; D011135:Polysaccharides, Bacterial / Q000276:immunology / Q000502:physiology*; D051381:Rats; D037521:Virulence Factors / Q000502:physiology
chemical_list: D019081:O Antigens; D011135:Polysaccharides, Bacterial; D037521:Virulence Factors; D003165:Complement System Proteins