Cystic fibrosis and beta-adrenergic response of airway epithelial cell cultures

Abstract

Confluent cell sheets were cultured from the tracheal epithelium of normal humans or from tracheal and nasal epithelia of patients with cystic fibrosis (CF). Changes in short-circuit current (Isc) or cyclic AMP (cAMP) levels in response to 10(-5) M isoproterenol were measured. In CF tracheal cells the response to isoproterenol was transient, and the maximal increase in Isc was one-tenth normal. In CF nasal cells, isoproterenol or epinephrine caused only small transient increases in Isc. However, in both CF nasal and tracheal cells, the Ca ionophore, A23187, caused relatively large increases in Isc that were inhibited by the Cl transport blocker, bumetanide, suggesting that Cl secretion can be induced by raising intracellular levels of Ca. In normal tracheal cell sheets, cAMP levels increased within 15 s of isoproterenol addition and continued to increase for up to 20 min. Resting levels of cAMP in CF tracheal cells were not statistically different from those of normal cells and showed linear increases for up to 4 min after addition of isoproterenol. Changes in cAMP in CF nasal cells were similar to the changes in CF tracheal cells. After 2 min, all three cell types showed cAMP levels elevated approximately equal to 10-fold. These results suggest that receptor-activated stimulation of adenylate cyclase is normal in CF. However, though raised cAMP levels stimulate Cl secretion in normal, they are unable to do so in CF airway epithelial cells.

Characterization of human tracheal epithelial cells transformed by an origin-defective simian virus 40.

“…The differences in the amount of cAMP accumulated within 1 min of stimulation may reflect clonal variability or variability due to the stage of neoplastic progression. The differences in cAMP levels do not appear to affect the Cl transport properties of the transformants, since the Cl ion channels respond to stimulation in a manner similar to that observed in primary culture (32,37). The present cultures provide an important tool for analysis of the mechanism by which Cl channels are regulated in normal individuals.…”

Defective regulatory volume decrease in human cystic fibrosis tracheal cells because of altered regulation of intermediate conductance Ca 2+ -dependent potassium channels

“…Vectorial ion transport is greatly affected in many CF epithelia (1). CF cells, unlike normal epithelial cells, do not elicit a net Cl Ϫ secretion when challenged with cAMPelevating agents (20), whereas Cl Ϫ secretion in response to agonists that elevate intracellular Ca 2ϩ is preserved (20)(21)(22)(23). To check the phenotypic characteristics of the original ⌬F508 cells (CFT1) and the cells permanently transfected with ␤gal (CFT1-LC3) or wild-type CFTR (CFT1-LCFSN), we studied the secretory responses of these cells.…”

Interleukin-1β Differentially Regulates β2 Adrenoreceptor and Prostaglandin E2-mediated cAMP Accumulation and Chloride Efflux from Calu-3 Bronchial Epithelial Cells

“…Cyclic AMP then activates protein kinase A, which phosphorylates the regulatory domain of CFTR. Airway epithelial cells express several adenylyl cyclase-coupled receptors, including ␤ 2 adrenoreceptors and EP prostanoid receptors whose activation promotes CFTR-mediated chloride flux (21). Although there is some evidence that cytokines can affect the function of components of this signaling pathway in airway cells, including epithelial cells (22) and airway smooth muscle cells (14), little is known about the functional consequences of these effects, particularly on CFTR-mediated chloride efflux in airway epithelial cells.…”