title: Activation of proteinase-activated receptor-2 in mesothelial cells induces pleural inflammation.
abstract: Pleural inflammation underlies many pleural diseases, but its pathogenesis remains unclear. Proteinase-activated receptor-2 (PAR(2)) is a novel seven-transmembrane receptor with immunoregulatory roles. We hypothesized that PAR(2) is present on mesothelial cells and can induce pleural inflammation. PAR(2) was detected by immunohistochemistry in all (19 parietal and 11 visceral) human pleural biopsies examined. In cultured murine mesothelial cells, a specific PAR(2)-activating peptide (SLIGRL-NH(2)) at 10, 100, and 1,000 muM stimulated a 3-, 42-, and 1,330-fold increase of macrophage inflammatory protein (MIP)-2 release relative to medium control, respectively (P < 0.05 all) and a 2-, 32-, and 75-fold rise over the control peptide (LSIGRL-NH(2), P < 0.05 all). A similar pattern was seen for TNF-alpha release. Known physiological activators of PAR(2), tryptase, trypsin, and coagulation factor Xa, also stimulated dose-dependent MIP-2 release from mesothelial cells in vitro. Dexamethasone inhibited the PAR(2)-mediated MIP-2 release in a dose-dependent manner. In vivo, pleural fluid MIP-2 levels in C57BL/6 mice injected intrapleurally with SLIGRL-NH(2) (10 mg/kg) were significantly higher than in mice injected with LSIGRL-NH(2) or PBS (2,710 +/- 165 vs. 880 +/- 357 vs. 88 +/- 46 pg/ml, respectively; P < 0.001). Pleural fluid neutrophil counts were higher in SLIGRL-NH(2) group than in the LSIGRL-NH(2) and PBS groups (by 40- and 26-fold, respectively; P < 0.05). This study establishes that activation of mesothelial cell PAR(2) potently induces the release of inflammatory cytokines in vitro and neutrophil recruitment into the pleural cavity in vivo.
authors.affiliation: Centre for Respiratory Research, Rayne Institute, University College London, 5 University St., London WC1E 6JJ, UK. ycgarylee@hotmail.com
authors.forename: Y C Gary
authors.initials: YC
authors.lastname: Lee
authors.forename: Darryl A
authors.initials: DA
authors.lastname: Knight
authors.forename: Kirk B
authors.initials: KB
authors.lastname: Lane
authors.forename: Dong Sheng
authors.initials: DS
authors.lastname: Cheng
authors.forename: M Audrey
authors.initials: MA
authors.lastname: Koay
authors.forename: Lisete R
authors.initials: LR
authors.lastname: Teixeira
authors.forename: Jon C
authors.initials: JC
authors.lastname: Nesbitt
authors.forename: Rachel C
authors.initials: RC
authors.lastname: Chambers
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Thompson
authors.forename: Richard W
authors.initials: RW
authors.lastname: Light
mesh_terms: D000818:Animals; D001706:Biopsy; D054426:Chemokine CXCL2; D018925:Chemokines / Q000378:metabolism; D004848:Epithelium / Q000378:metabolism* / Q000473:pathology; D015951:Factor Xa / Q000494:pharmacology; D006801:Humans; D007249:Inflammation / Q000209:etiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009504:Neutrophils / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology*; D010996:Pleural Effusion / Q000737:chemistry / Q000209:etiology*; D044464:Receptor, PAR-2 / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000494:pharmacology; D014357:Trypsin / Q000494:pharmacology; D053802:Tryptases
chemical_list: D054426:Chemokine CXCL2; D018925:Chemokines; C404915:Cxcl2 protein, mouse; D009842:Oligopeptides; D044464:Receptor, PAR-2; C509190:Tpsb2 protein, mouse; D012697:Serine Endopeptidases; D014357:Trypsin; C509222:Tpsab1 protein, mouse; D053802:Tryptases; D015951:Factor Xa