Immunocytochemical localization of cyclo-oxygenase isoforms in cultured human airway structural cells.
BACKGROUND
Cyclo-oxygenase (COX) exists as two isoforms, COX-1, the constitutive isoform, and COX-2, which is inducible by cytokines or inflammatory stimuli and may participate in airway inflammation.


OBJECTIVE
To determine the basal distribution of COX isoforms, and their regulation by interleukin-1 beta (IL-1beta), bradykinin (BK) and dexamethasone (Dex) in cultured airway structural cells.


METHODS
We measured COX-1 and COX-2 in cultured human airway smooth muscle (HASM) cells, MRC5 fibroblasts and normal human epithelial cells (NHBE) using immunocytochemical analysis.


RESULTS
The majority of all types of untreated cultured cells expressed COX-1 (75% of HASM, 75% of MRC5 fibroblasts and 72% of NHBE cells). Fibroblasts and smooth muscle cells showed low constitutive COX-2 expression (2 and 8%, respectively) but this was higher in NHBE cells (28%). IL-1beta (24 h incubation) or BK (4 h incubation) had no effect on COX-1 expression in any of the cells studied. In contrast, there was a two- and 1.5-fold rise in the percentage of NHBE cells expressing COX-2; a 7.5- and sixfold rise in the percentage of HASM cells expressing COX-2 and a 33.5- and 20.5-fold increase in the percentage of fibroblasts expressing COX-2 after IL-1beta or BK treatment, respectively. Pretreatment with dexamethasone abolished IL-1beta- and BK-stimulated COX-2 induction in all cells studied.


CONCLUSIONS
COX-1 is expressed constitutively in human airway fibroblasts, smooth muscle and epithelial cells but epithelial cells also show constitutive expression of COX-2. Both IL-1beta and BK induced COX-2 expression in all cells studied and this induction was blocked by dexamethasone. Immunocytochemical techniques can be successfully used to detect the distribution of COX isoforms in cell cultures.
Petkova
D K
DK
Respiratory Medicine Unit, City Hospital, Nottingham, UK.
Pang
L
L
Range
S P
SP
Holland
E
E
Knox
A J
AJ
D015153:Blotting, Western; D001920:Bradykinin / Q000494:pharmacology; D002478:Cells, Cultured; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D003907:Dexamethasone / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology / Q000201:enzymology; D005347:Fibroblasts / Q000166:cytology / Q000201:enzymology; D006801:Humans; D007124:Immunoenzyme Techniques; D007375:Interleukin-1 / Q000494:pharmacology; D007527:Isoenzymes / Q000378:metabolism*; D008168:Lung / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D008565:Membrane Proteins; D009130:Muscle, Smooth / Q000166:cytology / Q000201:enzymology; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*
D007375:Interleukin-1; D007527:Isoenzymes; D008565:Membrane Proteins; D003907:Dexamethasone; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; C496511:PTGS1 protein, human; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D001920:Bradykinin