title: Perfluorocarbon attenuates lipopolysaccharide-mediated inflammatory responses of alveolar epithelial cells in vitro.
abstract: BACKGROUND
  Toll-like receptor-4 (TLR-4) is integrally involved in lipopolysaccharide (LPS) signaling and has a requisite role in the activation of nuclear factor-κB (NF-κB). The exact mechanisms that lend perfluorocarbon (PFC) liquids a cytoprotective effect have yet to be elucidated. Therefore we examined in an in vitro model the cytoprotective effect of PFC on LPS-stimulated alveolar epithelial cellls (AECs).
  
  
  METHODS
  AECs (A549 cells, human lung adenocarcinoma cell line) were divided into four groups: control, PFC, LPS and LPS + PFC (coculture group) groups. Intercellular adhesion molecule-1 (ICAM-1) was detected by ELISA, tumor necrosis factor-α (TNF-α) and interleukin-8 (IL-8) were detected by radioimmunological methods. The expression of TLR-4 mRNA and protein was detected by real time PCR and Western blotting, respectively. The activation of NF-κB was detected by Western blotting (proteins of I-κBa and NF-κB p65).
  
  
  RESULTS
  ICAM-1, TNF-α and IL-8 were significantly increased in LPS-stimulated AECs groups. The expression of TLR-4 mRNA and protein in LPS-stimulated groups was markedly increased. Meanwhile, NF-κB was activated as indicated by the significant degradation of IκB-α and the significant release of NF-κB P65 and its subsequent translocation into the nucleus. There were no significant effects of PFC alone on any of the factors studied while the coculture group showed significant downregulation of the secretion of ICAM-1, TNF-α and IL-8, the expression of TLR-4 mRNA and the activity of NF-κB.
  
  
  CONCLUSIONS
  Taken together, our results demonstrate that LPS can induce AEC-related inflammatory injury via the activation of TLR-4 and subsequent activation of NF-κB. PFC is able to protect AECs from LPS-induced inflammatory injury by blocking the initiation of the LPS signaling pathway, which is indicated by the significant decrease of TLR-4 expression and NF-κB activation.
authors.affiliation: Department of Respiratory Medicine, Chinese People's Liberation Army General Hospital, Beijing 100853, China.
authors.forename: Shu-Feng
authors.initials: SF
authors.lastname: Xu
authors.forename: Ping
authors.initials: P
authors.lastname: Wang
authors.forename: Rui-Ji
authors.initials: RJ
authors.lastname: Liu
authors.forename: Jing
authors.initials: J
authors.lastname: Zhao
authors.forename: Xiang-Ning
authors.initials: XN
authors.lastname: Zhang
authors.forename: Zhan-Zhao
authors.initials: ZZ
authors.lastname: Fu
authors.forename: Li-Ming
authors.initials: LM
authors.lastname: Gao
authors.forename: Zhi-Xin
authors.initials: ZX
authors.lastname: Liang
authors.forename: Ji-Ping
authors.initials: JP
authors.lastname: Sun
authors.forename: Liang-An
authors.initials: LA
authors.lastname: Chen
mesh_terms: D015153:Blotting, Western; D045744:Cell Line, Tumor; D004847:Epithelial Cells / Q000187:drug effects* / Q000276:immunology*; D005466:Fluorocarbons / Q000494:pharmacology*; D006801:Humans; D007249:Inflammation / Q000139:chemically induced / Q000276:immunology*; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D011650:Pulmonary Alveoli / Q000166:cytology*; D060888:Real-Time Polymerase Chain Reaction; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism
chemical_list: D005466:Fluorocarbons; D016209:Interleukin-8; D008070:Lipopolysaccharides; D016328:NF-kappa B; D051197:Toll-Like Receptor 4; D014409:Tumor Necrosis Factor-alpha; D018799:Intercellular Adhesion Molecule-1