Gentamicin-induced correction of CFTR function in patients with cystic fibrosis and CFTR stop mutations.
BACKGROUND
Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene containing a premature termination signal cause a deficiency or absence of functional chloride-channel activity. Aminoglycoside antibiotics can suppress premature termination codons, thus permitting translation to continue to the normal end of the transcript. We assessed whether topical administration of gentamicin to the nasal epithelium of patients with cystic fibrosis could result in the expression of functional CFTR channels.


METHODS
In a double-blind, placebo-controlled, crossover trial, patients with stop mutations in CFTR or patients homozygous for the DeltaF508 mutation received two drops containing gentamicin (0.3 percent, or 3 mg per milliliter) or placebo in each nostril three times daily for two consecutive periods of 14 days. Nasal potential difference was measured at base line and after each treatment period. Nasal epithelial cells were obtained before and after gentamicin treatment from patients carrying stop mutations, and the C-terminal of surface CFTR was stained.


RESULTS
Gentamicin treatment caused a significant reduction in basal potential difference in the 19 patients carrying stop mutations (from -45+/-8 to -34+/-11 mV, P=0.005) and a significant response to chloride-free isoproterenol solution (from 0+/-3.6 to -5+/-2.7 mV, P<0.001). This effect of gentamicin on nasal potential difference occurred both in patients who were homozygous for stop mutations and in those who were heterozygous, but not in patients who were homozygous for DeltaF508. After gentamicin treatment, a significant increase in peripheral and surface staining for CFTR was observed in the nasal epithelial cells of patients carrying stop mutations.


CONCLUSIONS
In patients with cystic fibrosis who have premature stop codons, gentamicin can cause translational "read through," resulting in the expression of full-length CFTR protein at the apical cell membrane, and thus can correct the typical electrophysiological abnormalities caused by CFTR dysfunction.
Wilschanski
Michael
M
Department of Pediatrics, Cystic Fibrosis Center, Shaare Zedek Medical Center, Jerusalem, Israel.
Yahav
Yaacov
Y
Yaacov
Yasmin
Y
Blau
Hannah
H
Bentur
Lea
L
Rivlin
Joseph
J
Aviram
Micha
M
Bdolah-Abram
Tali
T
Bebok
Zsuzsa
Z
Shushi
Liat
L
Kerem
Batsheva
B
Kerem
Eitan
E
D000281:Administration, Intranasal; D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use*; D002648:Child; D018389:Codon, Nonsense / Q000187:drug effects*; D018592:Cross-Over Studies; D003550:Cystic Fibrosis / Q000188:drug therapy* / Q000235:genetics / Q000503:physiopathology; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D017353:Gene Deletion; D005838:Genotype; D005839:Gentamicins / Q000494:pharmacology / Q000627:therapeutic use*; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects; D008875:Middle Aged; D009297:Nasal Mucosa / Q000166:cytology / Q000187:drug effects / Q000503:physiopathology
D000900:Anti-Bacterial Agents; C505032:CFTR protein, human; D018389:Codon, Nonsense; D005839:Gentamicins; D019005:Cystic Fibrosis Transmembrane Conductance Regulator