Cystic fibrosis transmembrane conductance regulator function is suppressed in cigarette smokers.
BACKGROUND
Cigarette smoke extract inhibits chloride secretion in human bronchial epithelial cells. Oxidants decrease gene expression, protein expression, and function of the cystic fibrosis transmembrane conductance regulator (CFTR).


OBJECTIVE
Because cigarette smoke is a rich source of oxidants, we verified the hypothesis that CFTR may be suppressed by exposure to cigarette smoke in vitro and in vivo.


METHODS
The effects of cigarette smoke exposure on Calu-3 and T84 cell CFTR expression and function were observed. Also studied were the nasal potential differences (PDs) in 26 men (9 smokers, 17 nonsmokers) who had no detectable CFTR gene mutations as determined during investigations for infertility. CFTR expression and function were determined by Northern blotting, Western blotting, and cAMP-dependent 125I efflux assays. Extensive CFTR genotyping was performed in each subject. Nasal PD measurements were made at baseline and during amiloride, chloride-free buffer, and isoproterenol perfusions.


RESULTS
Cigarette smoke decreased CFTR expression and function in Calu-3 and T84 cell lines. Furthermore, the nasal PDs of cigarette smokers showed a pattern typical of CFTR deficiency with a blunted response to chloride-free buffer and isoproterenol compared with nonsmokers (-9.6 +/- 4.0 vs. -22.3 +/- 10.1 mV; p < 0.001).


CONCLUSIONS
We conclude that cigarette smoke decreases the expression of CFTR gene, protein, and function in vitro and that acquired CFTR deficiency occurs in the nasal respiratory epithelium of cigarette smokers. We suggest that acquired CFTR deficiency may contribute to the physiopathology of cigarette-induced diseases such as chronic bronchitis.
Pulmonary Research Unit, Faculty of Medicine, Université de Sherbrooke, 3001, 12ième Avenue Nord, Sherbrooke, Quebec, J1H 5N4 Canada. andre.cantin@usherbrooke.ca
André M
AM
Cantin
John W
JW
Hanrahan
Ginette
G
Bilodeau
Lynda
L
Ellis
Annie
A
Dupuis
Jie
J
Liao
Julian
J
Zielenski
Peter
P
Durie
D000328:Adult; D000704:Analysis of Variance; D015152:Blotting, Northern; D015153:Blotting, Western; D016022:Case-Control Studies; D002478:Cells, Cultured; D002712:Chlorides / Q000378:metabolism; D003550:Cystic Fibrosis / Q000097:blood / Q000235:genetics; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics* / Q000378:metabolism; D015536:Down-Regulation; D004847:Epithelial Cells / Q000166:cytology*; D005786:Gene Expression Regulation; D020022:Genetic Predisposition to Disease; D005838:Genotype; D005978:Glutathione / Q000378:metabolism*; D049691:History, Medieval; D006801:Humans; D008297:Male; D009297:Nasal Mucosa / Q000166:cytology; D016133:Polymerase Chain Reaction; D011336:Probability; D012333:RNA, Messenger / Q000032:analysis; D012016:Reference Values; D012680:Sensitivity and Specificity; D012907:Smoking / Q000235:genetics* / Q000378:metabolism
D002712:Chlorides; D012333:RNA, Messenger; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D005978:Glutathione