title: Cytokine expression in mice exposed to diesel exhaust particles by inhalation. Role of tumor necrosis factor.
abstract: BACKGROUND
  Particulate air pollution has been associated with lung and cardiovascular disease, for which lung inflammation may be a driving mechanism. The pro-inflammatory cytokine, tumor necrosis factor (TNF) has been suggested to have a key-role in particle-induced inflammation.We studied the time course of gene expression of inflammatory markers in the lungs of wild type mice and Tnf-/- mice after exposure to diesel exhaust particles (DEPs). Mice were exposed to either a single or multiple doses of DEP by inhalation. We measured the mRNA level of the cytokines Tnf and interleukin-6 (Il-6) and the chemokines, monocyte chemoattractant protein (Mcp-1), macrophage inflammatory protein-2 (Mip-2) and keratinocyte derived chemokine (Kc) in the lung tissue at different time points after exposure.
  
  
  RESULTS
  Tnf mRNA expression levels increased late after DEP-inhalation, whereas the expression levels of Il-6, Mcp-1 and Kc increased early. The expression of Mip-2 was independent of TNF if the dose was above a certain level. The expression levels of the cytokines Kc, Mcp-1 and Il-6, were increased in the absence of TNF.
  
  
  CONCLUSIONS
  Our data demonstrate that Tnf is not important in early DEP induced inflammation and rather exerts negative influence on Mcp-1 and Kc mRNA levels. This suggests that other signalling pathways are important, a candidate being one involving Mcp-1.
authors.affiliation: National Institute of Occupational Health, Lersø Parkallé 105, 2100 Copenhagen, Denmark. ats@ami.dk
authors.forename: Anne T
authors.initials: AT
authors.lastname: Saber
authors.forename: Nicklas R
authors.initials: NR
authors.lastname: Jacobsen
authors.forename: Jette
authors.initials: J
authors.lastname: Bornholdt
authors.forename: Sanna L
authors.initials: SL
authors.lastname: Kjaer
authors.forename: Marianne
authors.initials: M
authors.lastname: Dybdahl
authors.forename: Lotte
authors.initials: L
authors.lastname: Risom
authors.forename: Steffen
authors.initials: S
authors.lastname: Loft
authors.forename: Ulla
authors.initials: U
authors.lastname: Vogel
authors.forename: Håkan
authors.initials: H
authors.lastname: Wallin