Normalization of raised sodium absorption and raised calcium-mediated chloride secretion by adenovirus-mediated expression of cystic fibrosis transmembrane conductance regulator in primary human cystic fibrosis airway epithelial cells.

Cystic fibrosis airway epithelia exhibit a spectrum of ion transport properties that differ from normal, including not only defective cAMP-mediated Cl-secretion, but also in- creased Na+ absorption and increased Ca2"-mediated Cl- secretion. In the present study, we examined whether adeno- virus-mediated (Ad5) transduction of CFTR can correct all of these CF ion transport abnormalities. Polarized primary cultures of human CF and normal nasal epithelial cells were infected with Ad5-CBCFTR at an moi (104) which trans- duced virtually all cells or Ad5-CMV lacZ as a control. Con- sistent with previous reports, Ad5-CBCFTR, but not Ad5- CMV lacZ, corrected defective CF cAMP-mediated Cl -se- cretion. Basal Na + transport rates (basal I,q) in CF airway epithelial sheets (-78.59.8 puA/cm2) were reduced to levels measured in normal epithelial sheets (-30.02.0 pAA/cm2) by Ad5-CBCFTR (-36.94.8 1uA/cm2), but not Ad5- CMV lacZ ( -65.86.1 IAA/cm2). Surprisingly, a signfficant reduction in AIq in response to ionomycin, a measure of Ca2+-mediated Cl-secretion, was observed in CFTR-ex- pressing (corrected) CF epithelial sheets (-6.911.8 ,uA/ cm2) when compared to uninfected CF epithelial sheets (-76.215.1 puA/cm2). Dose response effects of AdS- CBCFTR on basal Na+ transport rates and Ca2+-mediated Cl-secretion suggest that the mechanism of regulation of these two ion transport functions by CFTR may be different. In conclusion, efficient transduction of CFTR corrects hyperabsorption of Na + in primary CF airway epithelial cells and restores Ca2+-mediated Clsecretion to levels observed in normal airway epithelial cells. Moreover, assessment of these ion transport abnormalities may represent important endpoints for testing the efficacy of gene therapy for cystic