Contribution of CFTR to apical-basolateral fluid transport in cultured human alveolar epithelial type II cells

• Published in: American journal of physiology. Lung cellular and molecular physiology 2006-02, Vol.290 (2), p.L242-L249
• Main Authors: Fang, Xiaohui, Song, Yuanlin, Hirsch, Jan, Galietta, Luis J. V, Pedemonte, Nicoletta, Zemans, Rachel L, Dolganov, Gregory, Verkman, A. S, Matthay, Michael A
• Format: Article
• Language: English
• Subjects: Biological Transport, Active; Cells, Cultured; Cyclic AMP - physiology; Cystic Fibrosis Transmembrane Conductance Regulator - antagonists & inhibitors; Cystic Fibrosis Transmembrane Conductance Regulator - physiology; Electric Impedance; Epithelial Cells - metabolism; Epithelial Sodium Channels; Gene Expression Profiling; Humans; Permeability; Phenotype; Pulmonary Alveoli - cytology; Pulmonary Alveoli - metabolism; Sodium Channels - physiology
• ISSN: 1040-0605; 1522-1504
• DOI: 10.1152/ajplung.00178.2005

1 Cardiovascular Research Institute and 2 Department of Medicine/Physiology, University of California, San Francisco, California; and 3 Laboratorio di Genetica Molecolare, Istituto Giannina Gaslini, Genoa, Italy Submitted 20 April 2005 ; accepted in final form 29 August 2005 Previous studies in intact lung suggest that CFTR may play a role in cAMP-regulated fluid transport from the distal air spaces of the lung. However, the potential contribution of different epithelial cells (alveolar epithelial type I, type II, or bronchial epithelial cells) to CFTR-regulated fluid transport is unknown. In this study we determined whether the CFTR gene is expressed in human lung alveolar epithelial type II (AT II) cells and whether the CFTR chloride channel contributes to cAMP-regulated fluid transport in cultured human AT II cells. Human AT II cells were isolated and cultured on collagen I-coated Transwell membranes for 120–144 h with an air-liquid interface. The cultured cells retained typical AT II-like features based on morphologic studies. Net basal fluid transport was 0.9 ± 0.1 µl·cm –2 ·h –1 and increased to 1.35 ± 0.11 µl·cm –2 ·h –1 (mean ± SE, n = 18, P < 0.05) by stimulation with cAMP agonists. The CFTR inhibitor, CFTR inh -172, inhibited cAMP stimulated but not basal fluid transport. In short-circuit current ( I sc ) studies with an apical-to-basolateral transepithelial Cl – gradient, apical application of CFTR inh -172 reversed the forskolin-induced decrease in I sc . Real time RT-PCR demonstrated CFTR transcript expression in human AT II cells at a level similar to that in airway epithelial cells. We conclude that CFTR is expressed in cultured human AT II cells and may contribute to cAMP-regulated apical-basolateral fluid transport. lung epithelial cells; cystic fibrosis transmembrane conductance regulator; ion channel; cyclic adenosine monophosphate; pulmonary edema; alveolar fluid clearance Address for reprint requests and other correspondence: X. Fang, Cardiovascular Research Inst., Univ. of California, San Francisco, CA 94143-0130 (e-mail: xiaohui.fang{at}ucsf.edu )