title: Toll-like receptor 4 relates to lipopolysaccharide-induced mucus hypersecretion in rat airway.
abstract: BACKGROUND
  Toll-like receptor 4 (TLR4) is a transmembrane protein that participates in the recognition of lipopolysaccharide (LPS), a potentially important source of inflammation. To investigate the role of TLR4 in LPS-induced airway mucus hypersecretion (AMH), we used a LPS-induced rat model treated with dexamethasone (DEX).
  
  
  METHODS
  Rats were randomly divided into four experimental groups: 1) saline (SA)-treated with distilled water (DW) (control group); 2) LPS-treated with DW (LPS group); 3) LPS-treated with DEX (LPS plus DEX group); 4) SA-treated with DEX (DEX group). DEX (5 mg/kg) was intraperitoneally injected 1 h before being administered intratracheally with LPS. Expressions of TLR4 and MUC5AC were evaluated with RT-PCR, in situ hybridization, immunohistochemistry and Alcian blue/Periodic acid-schiff (AB/PAS) staining.
  
  
  RESULTS
  Increased expressions of TLR4 protein and mRNA were found in rat airway treated with LPS and peaked on day 2 after LPS administration. Following this, LPS increased MUC5AC expression and AB/PAS-stained goblet cells in rat airway. Correlation analysis showed TLR4 correlated well with the expression of MUC5AC (r = 0.684, p <0.01) and AB/PAS-stained area (r = 0.781, p <0.01). In addition, DEX pretreatment significantly reduced LPS-induced overexpression of TLR4 (p <0.05) in rat airway.
  
  
  CONCLUSIONS
  These results suggest TLR4 relates to LPS-induced AMH and support a role of TLR4 in DEX inhibition of LPS-induced AMH.
authors.affiliation: Division of Pulmonary Diseases, State Key Laboratory of Biotherapy of China, and Department of Respiratory Medicine, Sichuan University, Chengdu, Sichuan, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.forename: Jian-Yong
authors.initials: JY
authors.lastname: Zhang
authors.forename: Shang-Fu
authors.initials: SF
authors.lastname: Zhang
authors.forename: Dai-Shun
authors.initials: DS
authors.lastname: Liu
authors.forename: Dan
authors.initials: D
authors.lastname: Xu
authors.forename: Xun
authors.initials: X
authors.lastname: Wang
authors.forename: Ya-Juan
authors.initials: YJ
authors.lastname: Chen
authors.forename: Fu-Qiang
authors.initials: FQ
authors.lastname: Wen
mesh_terms: D000818:Animals; D001980:Bronchi / Q000187:drug effects* / Q000378:metabolism; D003907:Dexamethasone / Q000008:administration & dosage; D007150:Immunohistochemistry; D008070:Lipopolysaccharides / Q000633:toxicity*; D008297:Male; D009093:Mucus / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014132:Trachea / Q000187:drug effects* / Q000378:metabolism
chemical_list: D008070:Lipopolysaccharides; D051197:Toll-Like Receptor 4; D003907:Dexamethasone