Role of Toll-like receptor 4 in gram-positive and gram-negative pneumonia in mice.
To determine the role of Toll-like receptor 4 (TLR4) in the immune response to pneumonia, C3H/HeJ mice (which display a mutant nonfunctional TLR4) and C3H/HeN wild-type mice were intranasally infected with either Streptococcus pneumoniae (a common gram-positive respiratory pathogen) or Klebsiella pneumoniae (a common gram-negative respiratory pathogen). In cases of pneumococcal pneumonia, TLR4 mutant mice showed a reduced survival only after infection with low-level bacterial doses, which was associated with a higher bacterial burden in their lungs 48 h postinfection. In Klebsiella pneumonia, TLR4 mutant mice demonstrated a shortened survival after infection with either a low- or a high-level bacterial dose together with an enhanced bacterial outgrowth in their lungs. These data suggest that TLR4 contributes to a protective immune response in both pneumococcal and Klebsiella pneumonia and that its role is more important in respiratory tract infection caused by the latter (gram-negative) pathogen.
Branger
Judith
J
Laboratory of Experimental Internal Medicine, Academic Medical Center, University of Amsterdam, The Netherlands. j.branger@amc.uva.nl
Knapp
Sylvia
S
Weijer
Sebastiaan
S
Leemans
Jaklien C
JC
Pater
Jennie M
JM
Speelman
Peter
P
Florquin
Sandrine
S
van der Poll
Tom
T
D000818:Animals; D016905:Gram-Negative Bacterial Infections / Q000276:immunology* / Q000473:pathology; D016908:Gram-Positive Bacterial Infections / Q000276:immunology* / Q000473:pathology; D006098:Granulocytes / Q000502:physiology; D007113:Immunity, Innate; D008168:Lung / Q000473:pathology; D008562:Membrane Glycoproteins / Q000502:physiology*; D051379:Mice; D008809:Mice, Inbred C3H; D018410:Pneumonia, Bacterial / Q000276:immunology* / Q000473:pathology; D011956:Receptors, Cell Surface / Q000502:physiology*; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors
D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors