Role of CD14 in responses to clinical isolates of Escherichia coli: Effects of K1 capsule expression

Shalaka Metkar, Shanjana Awasthi, Erick Denamur, Kwang Sik Kim, Sophie C. Gangloff, Saul Teichberg, Alain Haziot, Jack Silver, Sanna M. Goyert

Research output: Contribution to journalArticle

Abstract

Severe bacterial infections leading to sepsis or septic shock can be induced by bacteria that utilize different factors to drive pathogenicity and/or virulence, leading to disease in the host. One major factor expressed by all clinical isolates of gram-negative bacteria is lipopolysaccharide (LPS); a second factor expressed by some Escherichia coli strains is a K1 polysaccharide capsule. To determine the role of the CD14 LPS receptor in the pathogenic effects of naturally occurring E. coli, the responses of CD14-/- and CD14+/+ mice to three different isolates of E. coli obtained from sepsis patients were compared; two isolates express both smooth LPS and the K1 antigen, while the third isolate expresses only LPS and is negative for K1. An additional K1-positive isolate obtained from a newborn with meningitis and a K1-negative isogenic mutant of this strain were also used for these studies. CD14-/- mice were resistant to the lethal effects of the K1-negative isolates. This resistance was accompanied by significantly lower levels of systemic tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) in these mice than in CD14+/+ mice, enhanced clearance of the bacteria, and significantly fewer additional gross symptoms. In contrast, CD14 -/- mice were as sensitive as CD14+/+ mice to the lethal effects of the K1-positive isolates, even though they had significantly lower levels of TNF-α and IL-6 than CD14+/+ mice. These studies show that different bacterial isolates can use distinctly different mechanisms to cause disease and suggest that new, nonantibiotic therapeutics need to be directed against multiple targets.

Original languageEnglish (US)
Pages (from-to)5415-5424
Number of pages10
JournalInfection and Immunity
Volume75
Issue number11
DOIs
StatePublished - Nov 2007

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ASJC Scopus subject areas

  • Immunology

Cite this

Metkar, S., Awasthi, S., Denamur, E., Kim, K. S., Gangloff, S. C., Teichberg, S., Haziot, A., Silver, J., & Goyert, S. M. (2007). Role of CD14 in responses to clinical isolates of Escherichia coli: Effects of K1 capsule expression. Infection and Immunity, 75(11), 5415-5424. https://doi.org/10.1128/IAI.00601-07