Disruption of CFTR-dependent lipid rafts reduces bacterial levels and corneal disease in a murine model of Pseudomonas aeruginosa keratitis.
OBJECTIVE
Pseudomonas aeruginosa enters corneal epithelial cells in vitro via membrane microdomains or lipid rafts. Bacterial entry, mediated by the cystic fibrosis transmembrane conductance regulator (CFTR), promotes infection and disease. This study was conducted to determine whether P. aeruginosa and CFTR are colocalized to rafts in isogenic corneal cells expressing wild-type (WT) or mutant DeltaF508-CFTR and whether disruption of the rafts both in vitro and in vivo affects the bacterial levels and the course of the disease.


METHODS
Transformed human corneal epithelial cells from a patient homozygous for DeltaF508-CFTR, and the same cells corrected with WT-CFTR, were exposed to six isolates of P. aeruginosa-three invasive and three cytotoxic strains-in the presence of beta-cyclodextrin (CD), which disrupts rafts. Association and cellular uptake of the invasive strains were measured, as was lactate dehydrogenase release induced by the cytotoxic strains. Scratch-injured mouse eyes were infected with the six P. aeruginosa strains, and the effect of prophylactic or therapeutic administration of CD on bacterial levels and disease was evaluated.


RESULTS
P. aeruginosa and CFTR were colocalized with lipid rafts in cells with WT-CFTR, and CD treatment of these cells disrupted bacterial association, internalization, and cytotoxic effects. Cells expressing DeltaF508-CFTR were marginally affected by CD. Prophylactic and therapeutic topical application of CD ameliorated corneal disease and reduced the bacterial count in the eye.


CONCLUSIONS
P. aeruginosa enters human corneal epithelial cells via lipid rafts containing CFTR, and disruption of raft-mediated uptake of this organism by CD protects against disease and reduces bacterial levels in the mouse model of keratitis.
Zaidi
Tanweer
T
Channing Laboratory and Hematology Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
Bajmoczi
Milan
M
Zaidi
Tauqeer
T
Golan
David E
DE
Pier
Gerald B
GB
D000818:Animals; D001422:Bacterial Adhesion / Q000187:drug effects; D015153:Blotting, Western; D002461:Cell Line, Transformed; D015169:Colony Count, Microbial; D003320:Corneal Ulcer / Q000378:metabolism / Q000382:microbiology / Q000517:prevention & control*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics / Q000378:metabolism*; D004195:Disease Models, Animal; D019573:Epithelium, Corneal / Q000382:microbiology*; D015818:Eye Infections, Bacterial / Q000378:metabolism / Q000382:microbiology / Q000517:prevention & control*; D005455:Fluorescent Antibody Technique; D006801:Humans; D021962:Membrane Microdomains / Q000378:metabolism*; D051379:Mice; D018613:Microscopy, Confocal; D011552:Pseudomonas Infections / Q000378:metabolism / Q000382:microbiology / Q000517:prevention & control*; D011550:Pseudomonas aeruginosa / Q000502:physiology*; D034741:RNA, Small Interfering / Q000494:pharmacology; D047392:beta-Cyclodextrins / Q000494:pharmacology
D034741:RNA, Small Interfering; D047392:beta-Cyclodextrins; D019005:Cystic Fibrosis Transmembrane Conductance Regulator