Prostanoids mediate IL-1β-induced β-adrenergic hyporesponsiveness in human airway smooth muscle cells

Abstract

We have previously reported that pretreatment of cultured human airway smooth muscle (HASM) cells with interleukin-1β (IL-1β) results in decreased β-adrenergic responsiveness. The purpose of this study was to determine whether prostanoids released as a result of cyclooxygenase-2 (COX-2) induction by IL-1β contribute to this effect of the cytokine. Confluent serum-deprived HASM cells were studied in passages 4–7. IL-1β (20 ng/ml for 22 h) reduced the ability of the β-agonist isoproterenol (Iso) to decrease stiffness of HASM cells as measured by magnetic twisting cytometry. The effect of IL-1β on Iso-induced changes in cell stiffness was abolished by nonselective [indomethacin (Indo), 10−6 M] and selective (NS-398, 10−5 M) COX-2 inhibitors. Indo and NS-398 also inhibited both the increased basal cAMP and the decreases in Iso-stimulated cAMP production induced by IL-1β. IL-1β (20 ng/ml for 22 h) caused an increase in both basal (15-fold) and arachidonic acid (AA)-stimulated (10-fold) PGE2 release. Indo blocked basal and AA-stimulated PGE2 release in both control and IL-1β-treated cells. NS-398 also markedly reduced basal and AA-stimulated PGE2release in IL-1β-treated cells but had no significant effect on AA-stimulated PGE2 release in control cells. Western blot analysis confirmed the induction of COX-2 by IL-1β. Exogenously administered PGE2(10−7 M, 22 h) caused a significant reduction in the ability of Iso to decrease cell stiffness, mimicking the effects of IL-1β. Cycloheximide (10 μg/ml for 24 h), an inhibitor of protein synthesis, also abolished the effects of IL-1β on Iso-induced cell stiffness changes and cAMP formation. In summary, our results indicate that IL-1β significantly increases prostanoid release by HASM cells as a result of increased COX-2 expression. The prostanoids appear to contribute to β-adrenergic hyporesponsiveness, perhaps by heterologous desensitization of the β2 receptor.

Airway smooth muscle cells: contributing to and regulating airway mucosal inflammation?

“…Intratracheal administration of IL-1b to rats induced an attenuation of b-adrenergic receptorinduced airway relaxation through mechanisms involving a reduction in b-adrenoceptors and an increase in the inhibitory G protein, G i a subunit, coupled to a reduction in adenylyl cyclase activity [67]. Similar observations were made with in vitro human airway smooth muscle cells incubated with IL-1b with a decreased response in muscle stiffness to isoprenaline mediated by uncoupling of breceptors from stimulatory G s -induced activation of adenylyl cyclase, perhaps through the release of PGE 2 [68,69]. TNF-a can also induce a reduction in isoprenalinestimulated adenylyl cyclase activity [70], together with increased expression of Ga 1±2 and G q a but not of G s a proteins [71].…”

Cyclooxygenase-2 and MicroRNA-155 Expression Are Elevated in Asthmatic Airway Smooth Muscle Cells

“…Furthermore, we demonstrate that inhibition of miR-155 function in asthmatic hASMCs is sufficient to reduce COX-2 protein abundance and PGE 2 secretion. Discussion b 2 -adrenoceptor hyporesponsiveness has been observed in some patients with asthma, and this has been linked to cytokine-induced COX-2 expression and the resulting autocrine effects of secreted PGE 2 (1)(2)(3)(4)(5). Because asthmatic hASMCs show enhanced cytokineresponsive gene expression, we hypothesized that COX-2 expression would be elevated by cytokine stimulation in asthmatic hASMCs.…”

“…Hyporesponsiveness to b 2 -adrenoceptor agonists due to heterologous desensitization is an important limitation to the successful control of asthma symptoms (1)(2)(3)(4)(5). Several of the cytokines that are elevated in the bronchoalveolar lavage fluid of patients with asthma (including IL-1b and TNF-a) promote b 2 -adrenoceptor hyporesponsiveness (1,(3)(4)(5)(6)(7).…”

“…Several of the cytokines that are elevated in the bronchoalveolar lavage fluid of patients with asthma (including IL-1b and TNF-a) promote b 2 -adrenoceptor hyporesponsiveness (1,(3)(4)(5)(6)(7). In vitro studies of airway smooth muscle suggest that cytokine-mediated up-regulation of cyclooxygenase-2 (COX-2) leads to enhanced secretion of PGE 2 , activation of the cAMP/PKA pathway, and disruption of coupling of b 2 -adrenoceptors with Gas (2,4,5). Cytokine exposure of human airway smooth muscle cells (hASMCs) from patients with asthma induces a much greater expression of several cytokine targets, including eotaxin-1, CXCL10, and CXCL8, than is observed in nonasthmatic hASMCs (8)(9)(10).…”

Altered Drug Metabolism and Transport in Pathophysiological Conditions

“…Although, a significant increase in the plasma concentrations of verapamil in rats and humans with underlying arthritis were reported, there were no changes in the PD of verapamil (prolongation of PR interval) (Mayo et al, 2000;Sattari et al, 2003). This discrepancy was then attributed to a decrease in the receptorligand affinity in inflammation (Laporte et al, 1998;Shore et al, 1997).…”