Naringenin Regulates CFTR Activation and Expression in Airway Epithelial Cells

Background/Aims: Sputum symptoms are commonly seen in the elderly. This study aimed to identify an efficacious expectorant treatment stratagem through evaluating the secretion-promoting activation and cystic fibrosis transmembrane conductance regulator (CFTR) expression of the bioactive herbal monomer naringenin. Methods: Vectorial Cl - transport was determined by measuring short-circuit current (I SC ) in rat airway epithelium. cAMP content was measured by ELISA in primary cultured epithelial cells and Calu-3 cells. CFTR expression in Calu-3 cells was determined by qPCR. Results: Addition of naringenin to the basolateral side of the rat airway led to a concentration-dependent sustained increase in I SC . The current was suppressed when exposed to Cl – -free solution or by bumetanide, BaCl 2 , and DPC but not by DIDS and IBMX. Forskolin-induced I SC increase and CFTRinh-172/MDL-12330A-induced I SC inhibition were not altered by naringenin. Intracellular cAMP content was significantly increased by naringenin. With lipopolysaccharide stimulation, CFTR expression was significantly reduced, and naringenin dose-dependently enhanced CFTR mRNA expression. Conclusion: These results demonstrate that naringenin has the ability to stimulate Cl - secretion, which is mediated by CFTR through a signaling pathway by increasing cAMP content. Moreover, naringenin can increase CFTR expression when organism CFTR expression is seriously hampered. Our data suggest a potentially effective treatment strategy for sputum.