title: PAR1-dependent and independent increases in COX-2 and PGE2 in human colonic myofibroblasts stimulated by thrombin.
abstract: Subepithelial myofibroblast-derived prostaglandin E(2) (PGE(2)) regulates epithelial chloride secretion in the intestine. Thrombin is elevated in inflammatory conditions of the bowel. Therefore, we sought to determine a role for thrombin in regulating PGE(2) synthesis by colonic myofibroblasts. Incubation of cultured CCD-18Co colonic myofibroblasts with thrombin, the proteinase-activated receptor 1 (PAR(1))-activating peptide (Cit-NH(2)), and peptides corresponding to 2 noncatalytic regions of thrombin (TP367 and TP508) for 18 h increased both cyclooxygenase (COX)-2 expression (immunocytochemistry) and PGE(2) synthesis (enzyme immunoassay). Inhibition of thrombin by D-Phe-Pro-Arg-chloromethylketone (PPACK) did not significantly reduce PGE(2) synthesis, which remained elevated compared with control. We also investigated the basic fibroblast growth factor (bFGF) dependence of thrombin-induced PGE(2) elevations. Recombinant human bFGF concentration dependently increased PGE(2) synthesis, and a bFGF neutralizing antibody inhibited PGE(2) synthesis induced by TP367 and TP508 (approximately 40%) and by thrombin (approximately 20%) (but not Cit-NH(2)). Thrombin, therefore, upregulates COX-2-derived PGE(2) synthesis by both catalytic cleavage of PAR(1) and bFGF-dependent noncatalytic activity. This presents a novel mechanism by which intestinal myofibroblasts might regulate epithelial chloride secretion.
authors.affiliation: Mucosal Inflammation Research Group, University of Calgary, Calgary, Alberta, Canada T2N 4N1.
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Seymour
authors.forename: Nosheen F
authors.initials: NF
authors.lastname: Zaidi
authors.forename: Morley D
authors.initials: MD
authors.lastname: Hollenberg
authors.forename: Wallace K
authors.initials: WK
authors.lastname: MacNaughton
mesh_terms: D000068579:Celecoxib; D002460:Cell Line; D003106:Colon / Q000378:metabolism*; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D015232:Dinoprostone / Q000378:metabolism*; D005260:Female; D016222:Fibroblast Growth Factor 2 / Q000502:physiology; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007223:Infant; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008565:Membrane Proteins; D009130:Muscle, Smooth / Q000166:cytology / Q000378:metabolism; D010446:Peptide Fragments / Q000494:pharmacology; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D011720:Pyrazoles; D044463:Receptor, PAR-1; D018179:Receptors, Thrombin / Q000502:physiology*; D013449:Sulfonamides / Q000494:pharmacology; D013917:Thrombin / Q000494:pharmacology / Q000502:physiology*
chemical_list: D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D007527:Isoenzymes; D008565:Membrane Proteins; D010446:Peptide Fragments; D011720:Pyrazoles; D044463:Receptor, PAR-1; D018179:Receptors, Thrombin; D013449:Sulfonamides; D016222:Fibroblast Growth Factor 2; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D013917:Thrombin; D000068579:Celecoxib; D015232:Dinoprostone