Increase of bradykinin-stimulated arachidonic acid release in a ΔF508 cystic fibrosis epithelial cell line

Abstract

Modification of chloride conductanse by bradykinin in epithelial cells has been attributed to an activation of protein kinase A resulting from adenylcyclase stimulation by arachidonic acid cyclooxygenase products. The results presented here compare tracheal epithelial cell lines from one control and two cystic fibrosis patients which were immortalized by transfection with the SV40 large T oncogene. The three cell lines presented the same arachidonic acid content, turnover and mobilisation under basal conditions. Bradykinin stimulated the release of arachidonic acid and the synthesis of cyclooxygenase derivatives (mainly PGE 2). The cell line from the cystic fibrosis patient bearing a phenylalanine 508 deletion, which is the major form of the disease, showed a higher bradkinin-induced arachidonic acid release than either control cells or cells from a patient presenting a minor form of the disease. This higher sensitivity suggests a dysregulation of phospholipase A 2 stimulation in cystic fibrosis cells and was confirmed on non-immortalized tracheal epithelial cells in primary culture and on skin fibroblasts from patients bearing the same mutation. This defect is associated with a potentiation of cholera toxin pretreatment on cAMP content of ΔF508 cell line. The impaired control of arachidonic acid release cannot be attributed to an increased number of bradykinin binding sites, since this increase was similar in the two cystic fibrosis cell lines.