Differential roles of CD14 and toll-like receptors 4 and 2 in murine Acinetobacter pneumonia.

Authors: Knapp, S  Wieland, CW  Florquin, S  Pantophlet, R  Dijkshoorn, L  Tshimbalanga, N  Akira, S  Van der Poll, T 
Citation: Knapp S, etal., Am J Respir Crit Care Med. 2006 Jan 1;173(1):122-9. Epub 2005 Oct 6.
Pubmed: (View Article at PubMed) PMID:16210672
DOI: Full-text: DOI:10.1164/rccm.200505-730OC

RATIONALE: Acinetobacter baumannii is an opportunistic bacterial pathogen that is increasingly associated with gram-negative nosocomial pneumonia, but the molecular mechanisms that play a role in innate defenses during A. baumannii infection have not been elucidated. OBJECTIVE: To gain first insight into the role of CD14 and Toll-like receptors 4 and 2 in host response to A. baumannii pneumonia. METHODS: Respective gene-deficient mice were intranasally infected with A. baumannii, and bacterial outgrowth, lung inflammation, and pulmonary cytokine/chemokine responses were determined. To study the importance of LPS in the inflammatory response, mice were also challenged with A. baumannii LPS. MEASUREMENTS AND MAIN RESULTS: Bacterial counts were increased in CD14 and Toll-like receptor 4 gene-deficient mice, and only these animals developed bacteremia. The pulmonary cytokine/chemokine response was impaired in Toll-like receptor 4 knockout mice and the onset of lung inflammation was delayed. In contrast, Toll-like receptor 2-deficient animals displayed an earlier cell influx into lungs combined with increased macrophage inflammatory protein-2 and monocyte chemoattractant protein-1 concentrations, which was associated with accelerated elimination of bacteria from the pulmonary compartment. Neither CD14 nor Toll-like receptor 4 gene-deficient mice responded to intranasal administration of LPS, whereas Toll-like receptor 2 knockout mice were indistinguishable from wild-type animals. CONCLUSIONS: Our results suggest that CD14 and Toll-like receptor 4 play a key role in innate sensing of A. baumannii via the LPS moiety, resulting in effective elimination of the bacteria from the lung, whereas Toll-like receptor 2 signaling seems to counteract the robustness of innate responses during acute A. baumannii pneumonia.

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CRRD Object Information
CRRD ID: 4144197
Created: 2010-10-12
Species: All species
Last Modified: 2010-10-12
Status: ACTIVE



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RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.