Interleukin-1β Differentially Regulates β2 Adrenoreceptor and Prostaglandin E2-mediated cAMP Accumulation and Chloride Efflux from Calu-3 Bronchial Epithelial Cells: ROLE OF RECEPTOR CHANGES, ADENYLYL CYCLASE, CYCLO-OXYGENASE 2, AND PROTEIN KINASE A

Here we tested the effect of interleukin-1 beta, a proinflammatory cytokine, on cAMP accumulation and chloride efflux in Calu-3 airway epithelial cells in response to ligands binding to adenylyl cyclase-coupled receptors such as the beta(2) adrenoreceptor and EP prostanoid receptors. Interleukin-1 beta significantly increased isoprenaline-induced cAMP accumulation by increasing beta(2) adrenoreceptor numbers via a protein kinase A-dependent mechanism. In contrast, interleukin-1 beta significantly impaired prostaglandin E-2-induced cAMP accumulation by induction of cyclo-oxygenase-2, prostaglandin E-2 production, and a resulting down-regulation of adenylyl cyclase. The cAMP changes were all mirrored by alterations in chloride efflux assessed using the fluorescent chloride probe N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide with interleukin-1 beta increasing chloride efflux in response to isoprenaline and reducing the response to prostaglandin E2. Studies with glibenclamide confirmed that chloride efflux was via the cystic fibrosis transmembrane conductance regulator. Calu-3 expresses EP4 receptors, but not EP2, and receptor expression is reduced by interleukin-1 beta . Collectively, these results provide mechanistic insight into how interleukin-1 beta can differentially regulate cAMP generation and chloride efflux in response to different adenylyl cyclase-coupled ligands in the same cell. These findings have important implications for diseases involving inflammation and abnormal ion flux such as cystic fibrosis.