Dissection of host cell signal transduction during Acinetobacter baumannii-triggered inflammatory response

PLoS One. 2010 Apr 7;5(4):e10033. doi: 10.1371/journal.pone.0010033.

Abstract

Infected airway epithelial cells up-regulate the expression of chemokines, chiefly IL-8, and antimicrobial molecules including beta-defensins (BD). Acinetobacter baumannii is a cause of hospital-acquired pneumonia. We examined whether A. baumannii induced the expressions of IL-8 and BD2 by airway epithelial cells and the receptors implicated in bacterial detection. A549 and human primary airway cells released IL-8 upon infection. A. baumannii-infected cells also increased the expression of BD2 which killed A. baummannii strains. IL-8 induction was via NF-kappaB and mitogen-activated kinases p38 and p44/42-dependent pathways. A. baumannii engaged Toll-like receptor (TLR) 2 and TLR4 pathways and A549 cells could use soluble CD14 as TLRs co-receptor. A. baumannii lipopolysaccharide stimulated IL-8 release by A549 cells and sCD14 facilitated the recognition of the lipopolysaccharide. Mass spectrometry analysis revealed that A. baumannii lipid A structure matches those with endotoxic potential. These results demonstrate that airway epithelial cells produce mediators important for A. baumannii clearance.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acinetobacter Infections
  • Acinetobacter baumannii / immunology*
  • Cell Line
  • Epithelial Cells
  • Host-Pathogen Interactions*
  • Humans
  • Inflammation / etiology*
  • Inflammation Mediators / analysis
  • Interleukin-8 / genetics
  • Pneumonia / immunology
  • Pneumonia / microbiology*
  • Respiratory System / cytology
  • Signal Transduction*
  • Up-Regulation / genetics
  • beta-Defensins / genetics

Substances

  • Inflammation Mediators
  • Interleukin-8
  • beta-Defensins