Production of PGE<sub>2</sub> by bovine cultured airway smooth muscle cells and its inhibition by cyclo‐oxygenase inhibitors

Delamere, Finola M; Holland, Elaine; Patel, Sachin; Bennett, J A; Pavord, Ian D.; Knox, Alan J.

doi:10.1111/j.1476-5381.1994.tb14840.x

Cited by 71 publications

(45 citation statements)

References 25 publications

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“…Prostaglandin E 2 assay PGE 2 concentration was determined by radioimmunoassay as previously described [31]. The authors have previously validated this assay [22,23,31] and have shown it to have a low cross-reactivity with other metabolites of AA [22,23].…”

Section: Cyclo-oxygenase Activitymentioning

confidence: 99%

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Selectivity of cyclo-oxygenase inhibitors in human pulmonary epithelial and smooth muscle cells

Range¹,

Pang²,

Holland³

et al. 2000

Eur Respir J

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Selectivity of cyclo-oxygenase inhibitors in human pulmonary epithelial and smooth muscle cells. S.P. Range, L. Pang, E. Holland, A.J. Knox. #ERS Journals Ltd 2000. ABSTRACT: Cyclo-oxygenase (COX) inhibitors may have a role in reducing inflammation in asthma and other pulmonary diseases. COX inhibitors have different selectivities for the two COX isoenzymes (COX 1 and COX 2) which vary between purified enzyme and intact cell preparations. The relative selectivity of COX inhibitors has not been studied in human airway cells.A number of COX inhibitors in cultured human airway cells were compared which exclusively express either COX 1 (primary degree cultured human airway smooth muscle (HASM) cells) or COX 2 (A549 pulmonary epithelial cell-line) as measured by Western blotting. COX activity was assayed by prostaglandin (PG)E 2 production following 30 min incubation with 5 mM arachidonic acid.COX activity in both cell types was similar; HASM cells 92. -5 M for aspirin. Sodium valerate had no effect in either HASM or A549 cells. The COX 2:COX 1 selectivity ratio (COX 2 IC50/COX 1 IC50) was <0.0001 for nimesulide, 0.001 for NS398, 0.03 for flurbiprofen and 1.9 for indomethacin.In conclusion the present study has shown that cyclo-oxygenase inhibitors have a range of selectivities for cyclo-oxygenase 1 and cyclo-oxygenase 2 in intact human airway cells. The relative cyclo-oxygenase 2 selectivity of N-(2-cyclohexyloxy-4-nitrophenyl)-methanesulphonamide and nimesulide may have implications for the treatment of asthma and other inflammatory pulmonary diseases. Recent studies have suggested that cyclo-oxygenase (COX) products may be involved in the pathophysiology of several pulmonary diseases: COX products have been implicated in the inflammation found in asthmatic airways, with different COX products exerting differential effects in different situations in vivo [1±3]. Inhaled indomethacin and aspirin protect against indirect bronchoconstrictor challenges in asthma [4,5] suggesting that release of constrictor prostaglandins such as prostaglandin (PG)D 2 and PGF 2a may contribute to the mechanisms of action of these stimuli. Under different circumstances COX products may have a protective role. PGE 2 has been shown to have a potential bronchoprotective role both in vitro [6,7] and in vivo [8,9]. Studies showing that oral indomethacin inhibits refractoriness to repeated bronchoconstriction challenge suggest that endogenous PGE 2 may be involved in this protective response [10,11]. A small number of patients with asthma exhibit aspirin sensitivity, whereby oral aspirin and other COX inhibitors produce bronchochoconstriction. This bronchoconstriction can be prevented by inhalation of PGE 2 [12,13]. Collectively these studies implicate COX products in several aspects of asthma pathophysiology, but it is clear that the responses to COX inhibition depend on the inhibitor studied, the route of administration, the circumstances of use and the type of patients studied. Studies in cultured airway smooth muscle cells in vitro have sug...

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Section: Cyclo-oxygenase Activitymentioning

confidence: 99%

“…The authors have previously validated this assay [22,23,31] and have shown it to have a low cross-reactivity with other metabolites of AA [22,23]. Each sample analysed for PGE 2 was assayed in duplicate.…”

Section: Cyclo-oxygenase Activitymentioning

confidence: 99%

Selectivity of cyclo-oxygenase inhibitors in human pulmonary epithelial and smooth muscle cells

Range¹,

Pang²,

Holland³

et al. 2000

Eur Respir J

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“…However, blockade of PGE 2 production leads to partial reversal of β 2 AR desensitization in the context of inflammation (3), and thus PGE 2 may promote bronchoconstriction via desensitization of β 2 AR function or by activation of the G q -coupled EP 1 receptor. PGE 2 is produced by ASM, airway epithelial cells, and inflammatory cells and is the most abundant prostanoid in epithelial lining fluid (4)(5)(6). However, EP 1 -mediated signal transduction and its effect on airway responsiveness remains unclear.…”

Section: Introductionmentioning

confidence: 99%

Airway smooth muscle prostaglandin-EP1 receptors directly modulate 2-adrenergic receptors within a unique heterodimeric complex

McGraw

Mihlbachler²,

Schwarb³

et al. 2006

Journal of Clinical Investigation

110

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Multiple and paradoxical effects of airway smooth muscle (ASM) 7-transmembrane-spanning receptors activated during asthma, or by treatment with bronchodilators such as β 2 -adrenergic receptor (β 2 AR) agonists, indicate extensive receptor crosstalk. We examined the signaling of the prostanoid-EP 1 receptor, since its endogenous agonist prostaglandin E 2 is abundant in the airway, but its functional implications are poorly defined. Activation of EP 1 failed to elicit ASM contraction in mouse trachea via this G αq -coupled receptor. However, EP 1 activation markedly reduced the bronchodilatory function of β 2 AR agonist, but not forskolin, indicating an early pathway interaction. Activation of EP 1 reduced β 2 AR-stimulated cAMP in ASM but did not promote or augment β 2 AR phosphorylation or alter β 2 AR trafficking. Bioluminescence resonant energy transfer showed EP 1 and β 2 AR formed heterodimers, which were further modified by EP 1 agonist. In cell membrane [ 35 S]GTPγS binding studies, the presence of the EP 1 component of the dimer uncoupled β 2 AR from G αs , an effect accentuated by EP 1 agonist activation. Thus alone, EP 1 does not appear to have a significant direct effect on airway tone but acts as a modulator of the β 2 AR, altering G αs coupling via steric interactions imposed by the EP 1 :β 2 AR heterodimeric signaling complex and ultimately affecting β 2 AR-mediated bronchial relaxation. This mechanism may contribute to β-agonist resistance found in asthma. IntroductionThe 7-transmembrane-spanning (7-TM-spanning) receptors represent the largest signaling family in the genome. We estimate that the lung expresses 25-50 7-TM receptors in airway epithelial cells, airway smooth muscle (ASM), pulmonary vasculature, alveolar walls, and resident immune cells (1). In regard to asthma, several 7-TM receptors play established roles in bronchoconstriction (e.g., M 3 -muscarinic receptor) and bronchodilation (e.g., β 2 -adrenergic receptor [β 2 AR]). Despite identification of the endogenous ligands and receptor localization, there are a number of 7-TM receptors expressed in the airway whose functions are unknown, or appear to function paradoxically, based on recombinantly expressed receptors in model cell systems. This lack of understanding of receptor function has impeded our ability to ascertain the role of these ligands (some of which are markedly increased in asthma) in the relaxation/contraction of ASM; thus the mechanistic basis of bronchial hyperreactivity and bronchoconstriction in asthma remains only partially understood. In many cases the basis for incomplete mechanistic information can be attributed to the nature of recombinant expression systems, which may not take

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“…Bradykinin (BK) stimulates PGE # synthesis and release in cultured bovine ASM cells [7]. In this regard, PGE # might…”

Section: Introductionmentioning

confidence: 99%

Bradykinin stimulates cAMP synthesis via mitogen-activated protein kinase-dependent regulation of cytosolic phospholipase A2 and prostaglandin E2 release in airway smooth muscle

Pyne

Tolan

Pyne

1997

Biochemical Journal

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Bradykinin stimulates cAMP synthesis in cultured airway smooth muscle (ASM) cells. This occurs via a pathway that involves: (1) the protein kinase C (PKC)-dependent activation of mitogen-activated protein kinase (MAPK); (2) the MAPK-dependent phosphorylation and activation of cytosolic phospholipase A2 (cPLA2) and (3) the utilization of cPLA2-derived arachidonate by the cyclo-oxygenase pathway to produce prostaglandin E2 (PGE2). PGE2 is released and binds to cell surface receptors to stimulate intracellular cAMP synthesis. The signalling pathway was confirmed by the use of PD098059 [the inhibitor of MAPK kinase-1 (MEK-1) activation], AACOCF3 (an inhibitor of cPLA2) and indomethacin (an inhibitor of cyclo-oxygenase), which all reduced bradykinin-stimulated cAMP synthesis. Bradykinin also elicits the inhibition of approx. 60% of the total cAMP phosphodiesterase activity in the cell [Stevens, Pyne, Grady and Pyne (1994) Biochem. J. 297, 233-239]. This is likely to decrease the rate of cAMP degradation markedly and therefore to potentiate PGE2-stimulated cAMP synthesis. Acute treatment of ASM cells with PMA (a direct activator of PKC) also stimulated the MAPK-dependent phosphorylation of cPLA2. However, in contrast with bradykinin, PMA did not stimulate arachidonate release, suggesting that additional signals (e.g. Ca2+ ions) are required for phosphorylation by MAPK to activate cPLA2. PMA was also without effect on PGE2 release and cAMP synthesis. Evidence that PKC can also directly regulate adenylate cyclase was obtained by using cells pretreated with cholera toxin. Under these conditions, PMA stimulated cAMP synthesis independently of arachidonate metabolites. Furthermore the combined treatment of cells with PMA (to activate PKC) and PGE2 (to activate Gs) stimulated synergistic cAMP synthesis. This might be due to the presence of the type 2 adenylate cyclase, which is synergistically activated by Gs and PKC.

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Production of PGE₂ by bovine cultured airway smooth muscle cells and its inhibition by cyclo‐oxygenase inhibitors

Cited by 71 publications

References 25 publications

Selectivity of cyclo-oxygenase inhibitors in human pulmonary epithelial and smooth muscle cells

Selectivity of cyclo-oxygenase inhibitors in human pulmonary epithelial and smooth muscle cells

Airway smooth muscle prostaglandin-EP1 receptors directly modulate 2-adrenergic receptors within a unique heterodimeric complex

Bradykinin stimulates cAMP synthesis via mitogen-activated protein kinase-dependent regulation of cytosolic phospholipase A2 and prostaglandin E2 release in airway smooth muscle

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Production of PGE2 by bovine cultured airway smooth muscle cells and its inhibition by cyclo‐oxygenase inhibitors

Cited by 71 publications

References 25 publications

Selectivity of cyclo-oxygenase inhibitors in human pulmonary epithelial and smooth muscle cells

Selectivity of cyclo-oxygenase inhibitors in human pulmonary epithelial and smooth muscle cells

Airway smooth muscle prostaglandin-EP1 receptors directly modulate 2-adrenergic receptors within a unique heterodimeric complex

Bradykinin stimulates cAMP synthesis via mitogen-activated protein kinase-dependent regulation of cytosolic phospholipase A2 and prostaglandin E2 release in airway smooth muscle

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Production of PGE₂ by bovine cultured airway smooth muscle cells and its inhibition by cyclo‐oxygenase inhibitors