Effects of interleukin-4 on the expression and activity of prostaglandin endoperoxide H synthase-2 in amnion-derived WISH cells.
Increased prostaglandin biosynthesis during intrauterine infection may be a possible mechanism by which preterm labour is initiated. Inflammatory cytokines and growth factors are known to stimulate prostaglandin production through an increase in prostaglandin endoperoxide H synthase (PGHS)-2 synthesis and activity. Interleukin-4 (IL-4), an anti-inflammatory cytokine, can downregulate PGHS-2 expression and inhibit prostaglandin production. Therefore, the aims of the current study were to determine the effects of IL-4 on PGHS-1 and PGHS-2 expression in amion-derived WISH cells treated with inflammatory cytokines and growth factors. In WISH cells, near-maximal production of the PGHS-2 mRNA occurred using 5 ng/ml EGF, 1 ng/ml IL-1beta or 50 ng/ml TNF-alpha. Time-course experiments determined that the PGHS-2 mRNA was induced maximally by these stimuli by 1 h. Pretreatment of WISH cells with IL-4 reduced PGHS-2 mRNA levels at 1 h by 67% in cells treated with EGF, 62% in cells treated with IL-1beta and 54% in cells treated with TNF-alpha. Pretreatment with IL-4 more effectively inhibited PGHS-2 expression than simultaneous addition with EGF or IL-1beta but not TNF-alpha. Immunoblot analysis showed a correlation between inhibition of mRNA levels and levels of PGHS-2 protein, although stimulation of PGHS-2 protein production by EGF was undetectable. Levels of PGHS-1 protein and mRNA remained unchanged in all experiments. Increased production of prostaglandin E2 (PGE2) in response to TNF-alpha and IL-1beta treatment was attenuated by IL-4 pretreatment, by 52% and 72%, respectively. No attenuation of EGF-stimulated PGE2 levels was seen. We conclude that IL-4 inhibits PGHS-2 mRNA and protein production in cytokine-stimulated WISH cells, but does not affect EGF-stimulated PGE2 production, suggesting that EGF can induce prostaglandin biosynthesis by a mechanism other than through increased PGHS-2 expression.
Gilmour
J S
JS
Department of Pharmacology and Clinical Pharmacology, University of Auckland, School of Medicine, 85 Park Road, Grafton, Auckland, New Zealand.
Hansen
W R
WR
Miller
H C
HC
Keelan
J A
JA
Sato
T A
TA
Mitchell
M D
MD
D000650:Amnion / Q000166:cytology / Q000201:enzymology; D002460:Cell Line; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D015847:Interleukin-4 / Q000494:pharmacology*; D007527:Isoenzymes / Q000235:genetics* / Q000378:metabolism*; D007700:Kinetics; D008565:Membrane Proteins; D011247:Pregnancy; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics* / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
D007527:Isoenzymes; D008565:Membrane Proteins; D012333:RNA, Messenger; D015847:Interleukin-4; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; C496511:PTGS1 protein, human; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases