title: Protease-activated receptor-2-mediated inhibition for Ca2+ response to lipopolysaccharide in Guinea pig tracheal epithelial cells.
abstract: The protease-activated receptor-2 (PAR-2) has been implicated in airway inflammation. Here, we examined the interaction between PAR-2 and lipopolysaccharide (LPS), a major proinflammatory factor, using cultured guinea pig tracheal epithelial cells. In fura2-loaded cells, LPS (1 microg/ml) transiently increased intracellular Ca(2+) concentrations ([Ca(2+)]i), this effect being abolished by a Ca(2+) channel blocker, verapamil, and Ca(2+) removal. Prestimulation of PAR-2 with trypsin (0.1-1 U/ml) or an agonist peptide (SLIGRL-NH(2), 1 microM) for 60 min inhibited the LPS-induced [Ca(2+)]i increase. Such an inhibitory effect of trypsin was abolished by inhibitors of protein kinase C (PKC), chelerythrine and staurosporine. A PKC activator, phorbol 12,13-dibutylate, also reduced the LPS response. Trypsin also inhibited a transient increase in [Ca(2+)]i caused by a Ca(2+) channel opener, Bay K 8644. When the trypsin-pretreated cells were incubated in normal buffer for 10-60 min before LPS exposure, the effect of trypsin on the Ca(2+) response to LPS diminished in a time-dependent manner. Such a recovery was slowed by incubation with a protein phosphatase inhibitor, okadaic acid. Further, trypsin induced sustained activations of PKCalpha and -epsilon. Thus, PAR-2 stimulation reduced the epithelial cell response to LPS, probably through the inactivation of Ca(2+) channels via PKC-mediated phosphorylation.
authors.affiliation: Department of Pharmacology, Kansai Medical University, Moriguchi, Osaka 570-8506, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Oshiro
authors.forename: Hitomi
authors.initials: H
authors.lastname: Otani
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Yagi
authors.forename: Shirou
authors.initials: S
authors.lastname: Fukuhara
authors.forename: Chiyoko
authors.initials: C
authors.lastname: Inagaki
mesh_terms: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002120:Calcium Channel Agonists / Q000494:pharmacology; D015220:Calcium Channels / Q000378:metabolism; D002478:Cells, Cultured; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D006168:Guinea Pigs; D007527:Isoenzymes / Q000378:metabolism; D008070:Lipopolysaccharides / Q000378:metabolism* / Q000494:pharmacology; D019319:Okadaic Acid / Q000494:pharmacology; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D044464:Receptor, PAR-2 / Q000819:agonists / Q000276:immunology / Q000378:metabolism*; D020545:Respiratory Mucosa / Q000166:cytology* / Q000378:metabolism; D014132:Trachea / Q000033:anatomy & histology* / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism
chemical_list: D002120:Calcium Channel Agonists; D015220:Calcium Channels; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D008070:Lipopolysaccharides; D044464:Receptor, PAR-2; D019319:Okadaic Acid; D015240:Phorbol 12,13-Dibutyrate; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D011493:Protein Kinase C; D014357:Trypsin; D002118:Calcium