Effect of endogenous and exogenous prostaglandin E(2) on interleukin-1 beta-induced cyclooxygenase-2 expression in human airway smooth-muscle cells.
We studied the effect of endogenous and exogenous prostaglandin E(2) (PGE(2)), a metabolite of arachidonic acid through the cyclooxygenase (COX) pathway, on interleukin (IL)-1 beta-induced COX-2 expression, using primary cultures of human bronchial smooth-muscle cells (HBSMC). Treatment with exogenous PGE(2) resulted in enhanced expression of IL-1 beta-induced COX-2 protein and messenger RNA (mRNA) as compared with the effect of the cytokine per se. Inhibition of PGE(2) production with a nonselective COX inhibitor (flurbiprofen, 10 microM) resulted in a significant reduction in IL-1 beta- induced COX-2 expression, supporting a role of endogenous COX metabolites in the modulation of COX-2 expression. None of the experimental conditions used in the study affected the expression of constitutive cyclooxygenase (COX-1). Treatment with cycloheximide to inhibit translation, and with dexamethasone or actinomycin D to inhibit transcription, linked the effect of PGE(2) to the transcriptional level of COX-2 mRNA rather than to a potential effect on protein and/or mRNA stabilization. PGE(2) increased adenylate cyclase activity in a concentration dependent manner, and forskolin, a direct activator of adenylate cyclase, caused a marked increase in IL-1 beta-dependent COX-2, suggesting the existence of a causal relationship between the two events. The same results were observed with salbutamol, a bronchodilator that acts by increasing cyclic adenosine monophosphate. The effect of PGE(2) on COX-2 expression may contribute to the hypothesized antiinflammatory role of PGE(2) in human airways, providing a self-amplifying loop leading to increased biosynthesis of PGE(2) during an inflammatory event.
Bonazzi
A
A
Center for Cardiopulmonary Pharmacology, University of Milan, Milan, Italy.
Bolla
M
M
Buccellati
C
C
Hernandez
A
A
Zarini
S
S
Viganò
T
T
Fumagalli
F
F
Viappiani
S
S
Ravasi
S
S
Zannini
P
P
Chiesa
G
G
Folco
G
G
Sala
A
A
D000262:Adenylyl Cyclases / Q000032:analysis; D000704:Analysis of Variance; D015152:Blotting, Northern / Q000379:methods / Q000706:statistics & numerical data; D015153:Blotting, Western / Q000379:methods / Q000706:statistics & numerical data; D001980:Bronchi / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D002478:Cells, Cultured; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000494:pharmacology*; D004790:Enzyme Induction / Q000187:drug effects; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology*; D007527:Isoenzymes / Q000032:analysis / Q000096:biosynthesis / Q000187:drug effects; D008565:Membrane Proteins; D009130:Muscle, Smooth / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D010544:Peroxidases / Q000032:analysis / Q000096:biosynthesis / Q000187:drug effects*; D011451:Prostaglandin-Endoperoxide Synthases / Q000032:analysis / Q000096:biosynthesis / Q000187:drug effects*; D011459:Prostaglandins E, Synthetic / Q000494:pharmacology*
D007375:Interleukin-1; D007527:Isoenzymes; D008565:Membrane Proteins; D011459:Prostaglandins E, Synthetic; D010544:Peroxidases; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D000262:Adenylyl Cyclases; D015232:Dinoprostone