Cyclooxygenase-2 and synthesis of PGE2 in human bronchial smooth-muscle cells

• Published in: American journal of respiratory and critical care medicine Vol. 155; no. 3; p. 864
• Main Authors: Viganò, T, Habib, A, Hernandez, A, Bonazzi, A, Boraschi, D, Lebret, M, Cassina, E, Maclouf, J, Sala, A, Folco, G
• Format: Journal Article
• Language: English
• Published: United States 01.03.1997
• Subjects: Arachidonic Acid - pharmacology; Blotting, Western; Bronchi - cytology; Bronchi - metabolism; Cells, Cultured; Cycloheximide - pharmacology; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors - pharmacology; Dexamethasone - pharmacology; Dinoprostone - biosynthesis; Dose-Response Relationship, Drug; Humans; Immunoblotting; Interleukin 1 Receptor Antagonist Protein; Interleukin-1 - pharmacology; Isoenzymes - biosynthesis; Membrane Proteins; Muscle, Smooth - drug effects; Muscle, Smooth - metabolism; Peroxidases - metabolism; Prostaglandin-Endoperoxide Synthases - biosynthesis; Pyrazoles - pharmacology; Receptors, Interleukin-1 - antagonists & inhibitors; Sialoglycoproteins - pharmacology
• ISSN: 1073-449X; 1535-4970
• DOI: 10.1164/ajrccm.155.3.9117018

The purpose of this study was to determine the mechanism of enhanced prostaglandin synthesis in cultured human bronchial smooth-muscle cells challenged with interleukin-1 beta (IL-1 beta). Cells were incubated with IL-1 beta (10 to 50 U/ml) for 0 to 24 h. Prostaglandin E2 (PGE2) production was evaluated through the conversion of exogenous (14C)-arachidonic acid and specific enzyme immunoassay of endogenous products. IL-1 beta enhanced PGE2 formation in a concentration- and time-dependent manner, reaching its peak at 6 to 8 h and fading at 18 to 24 h. Immunoblot analysis showed that the inducible cyclooxygenase enzyme (COX-2) was expressed only in IL-1 beta treated cells, whereas the constitutive isoform of cyclooxygenase (COX-1) remained unaltered. COX-2 expression and PGE2 formation were inhibited by dexamethasone (2 microM), cycloheximide (10 microM), and IL-1-receptor antagonist (IL-1 ra) (250 ng/ml), independently. PGE2 synthesis was significantly reduced by compound SC-58125, a specific COX-2 inhibitor. The close parallelism between the kinetics of COX-2 protein expression and PGE2 accumulation, as well as the constitutive nature of COX-1 isoform, indicate that IL-1 beta-driven PGE2 formation in human bronchial smooth-muscle cells is mediated by de novo expression of COX-2 enzyme.