Polymorphonuclear leucocytes consume oxygen in sputum from chronic Pseudomonas aeruginosa pneumonia in cystic fibrosis.
BACKGROUND
Chronic lung infection with Pseudomonas aeruginosa is the most severe complication for patients with cystic fibrosis (CF). This infection is characterised by endobronchial mucoid biofilms surrounded by numerous polymorphonuclear leucocytes (PMNs). The mucoid phenotype offers protection against the PMNs, which are in general assumed to mount an active respiratory burst leading to lung tissue deterioration. An ongoing respiratory burst by the PMNs has, however, not been demonstrated previously in endobronchial secretions from chronically infected patients with CF.


OBJECTIVE
Based on the accumulating evidence for depletion of molecular oxygen (O(2)) in the mucus in infected CF bronchi, it was hypothesised that the O(2) depletion in the mucus in infected CF bronchi may be accelerated by the respiratory burst of the PMNs due to the reduction of O(2) to the superoxide anion (O(-)(2)) by the phagocyte NADPH oxidase (Phox).


METHODS
Methods were established to isolate the O(2) consumption by the respiratory burst from aerobic respiration in freshly expectorated sputum from chronically infected patients with CF.


RESULTS
Inhibition of the Phox with diphenylene iodonium (DPI) delayed O(2) depletion, nearly abolished staining of O(-)(2)-producing PMNs with hydroethidine and inhibited the rapid luminol-enhanced chemiluminescence in sputum. Furthermore, the total O(2) consumption was correlated to the concentration of PMNs in the sputum samples.


CONCLUSIONS
The results demonstrate that CF sputum contains PMNs with an active consumption of O(2) for O(-)(2) production and suggest that the respiratory burst is ongoing and causes accelerated O(2) depletion due to formation of O(-)(2) in the lungs of chronically infected patients with CF.
Department of Clinical Microbiology, Juliane Mariesvej 22, Rigshospitalet, 2100 Copenhagen, Denmark.
M
M
Kolpen
C R
CR
Hansen
T
T
Bjarnsholt
C
C
Moser
L D
LD
Christensen
M
M
van Gennip
O
O
Ciofu
L
L
Mandsberg
A
A
Kharazmi
G
G
Döring
M
M
Givskov
N
N
Høiby
P Ø
PØ
Jensen
D000328:Adult; D001980:Bronchi / Q000276:immunology / Q000382:microbiology; D002908:Chronic Disease; D003550:Cystic Fibrosis / Q000382:microbiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019255:NADPH Oxidases / Q000378:metabolism; D009504:Neutrophils / Q000378:metabolism* / Q000382:microbiology; D010101:Oxygen Consumption / Q000502:physiology*; D010587:Phagocytosis; D011552:Pseudomonas Infections / Q000382:microbiology*; D011550:Pseudomonas aeruginosa; D017382:Reactive Oxygen Species / Q000378:metabolism; D016897:Respiratory Burst / Q000502:physiology; D013183:Sputum / Q000166:cytology / Q000382:microbiology; D013481:Superoxides / Q000378:metabolism; D055815:Young Adult
D017382:Reactive Oxygen Species; D013481:Superoxides; D019255:NADPH Oxidases