title: Lipoteichoic acid (LTA) from Staphylococcus aureus stimulates human neutrophil cytokine release by a CD14-dependent, Toll-like-receptor-independent mechanism: Autocrine role of tumor necrosis factor-[alpha] in mediating LTA-induced interleukin-8 generation.
abstract: OBJECTIVE
  In sepsis, Gram-positive and Gram-negative bacteria provoke similar inflammatory processes. Whereas lipopolysaccharides (LPSs) are acknowledged as the principal immunostimulatory components of Gram-negative bacteria, the effect of the Gram-positive cell wall component lipoteichoic acid (LTA) is less well characterized. In the present study, we investigated the effect of highly purified LTA from Staphylococcus aureus on cytokine generation by isolated human neutrophils.
  
  
  METHODS
  Isolated human neutrophils from healthy volunteers.
  
  
  METHODS
  Incubation of neutrophils with purified LTA from S. aureus in the absence or presence of interleukin (IL)-10, anti-CD14, or anti-Toll-like-receptor antibodies.
  
  
  METHODS
  Measurement of tumor necrosis factor (TNF)-alpha, IL-1beta, and IL-8 by enzyme-linked immunosorbent assay. Analysis of IL-8 mRNA by reverse transcriptase polymerase chain reaction.
  
  
  CONCLUSIONS
  The LTA challenge provoked a dramatic release of cytokines, with an early appearance of TNF-alpha and IL-1beta and a delayed liberation of IL-8. The first phase of IL-8 production was induced directly by LTA, whereas the second phase was endogenously mediated by TNF-alpha, as it was largely abrogated by neutralizing anti-TNF-alpha antibodies. In contrast, IL1-beta was not involved in LTA-induced IL-8 generation. Interestingly, the late phase of IL-8 generation could also be attenuated by exogenous IL-10, probably as a consequence of its downregulatory effects on TNF-alpha generation. When investigating the mechanism of LTA-induced cellular activation, activity-neutralizing antibodies demonstrated that CD14 was involved in LTA-mediated neutrophil cytokine generation. Using antibodies that neutralize the activity of Toll-like receptor 2 (TLR2) or 4 (TLR4), we also show that CD14-dependent, LTA-induced neutrophil activation did not proceed via TLR2- or TLR4-mediated pathways. In conclusion, LTA is a potent activator of human neutrophil cytokine generation, with the synthesis of the chemokine IL-8 being largely dependent on TNF-alpha generation in an autocrine fashion. This LTA-induced effect was inhibited by IL-10, dependent on CD14, and independent of TLR 2 or 4.
authors.affiliation: Department of Internal Medicine, University of Giessen Lung Center, Germany.
authors.forename: Katja
authors.initials: K
authors.lastname: Hattar
authors.forename: Ulrich
authors.initials: U
authors.lastname: Grandel
authors.forename: Alexander
authors.initials: A
authors.lastname: Moeller
authors.forename: Ludger
authors.initials: L
authors.lastname: Fink
authors.forename: Julia
authors.initials: J
authors.lastname: Iglhaut
authors.forename: Thomas
authors.initials: T
authors.lastname: Hartung
authors.forename: Siegfried
authors.initials: S
authors.lastname: Morath
authors.forename: Werner
authors.initials: W
authors.lastname: Seeger
authors.forename: Friedrich
authors.initials: F
authors.lastname: Grimminger
authors.forename: Ulf
authors.initials: U
authors.lastname: Sibelius
mesh_terms: D000704:Analysis of Variance; D002478:Cells, Cultured; D016207:Cytokines / Q000096:biosynthesis*; D006801:Humans; D016753:Interleukin-10 / Q000276:immunology; D016209:Interleukin-8 / Q000096:biosynthesis; D018950:Lipopolysaccharide Receptors / Q000276:immunology; D008070:Lipopolysaccharides / Q000276:immunology*; D009504:Neutrophils / Q000276:immunology / Q000378:metabolism*; D018805:Sepsis / Q000276:immunology*; D013203:Staphylococcal Infections / Q000276:immunology*; D013211:Staphylococcus aureus / Q000276:immunology / Q000378:metabolism; D013682:Teichoic Acids / Q000276:immunology*; D051193:Toll-Like Receptors / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology
chemical_list: D016207:Cytokines; D016209:Interleukin-8; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D013682:Teichoic Acids; D051193:Toll-Like Receptors; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; C009900:lipoteichoic acid