Exhaled NO and iNOS expression in sputum cells of healthy, obese and OSA subjects.
BACKGROUND
Obstructive sleep apnoea (OSA) is associated with airways inflammation; a key role in this regard seems to be played by nitric oxide (NO). The aim of this study was to measure exhaled NO and expression of its enzyme, the inducible nitric oxide synthase (iNOS) in cells of induced sputum in OSA patients and in obese subjects without sleep apnoea and to correlate these inflammatory markers with severity of OSA.


METHODS
We enrolled 18 obese patients with OSA (10 men, age 48.2 +/- 8.4 years), 15 obese patients without OSA (eight men, age 52.8 +/- 11 years) and 10 healthy subjects (five men, age 42 +/- 4 years). Exhaled NO was measured using a chemiluminescence analyser; iNOS expression was measured in the sputum cells by immunocytochemistry.


RESULTS
Exhaled NO resulted significantly increased in OSA and in obese patients (23.1 +/- 2.1 and 17.9 +/- 2.1 p.p.b.) than in healthy subjects (7.2 +/- 0.6 p.p.b.; P < 0.001). OSA and obese patients showed a higher percentage of neutrophils and a lower percentage of macrophages in the induced sputum compared to healthy subjects. In addition, OSA and obese patients showed higher iNOS expression in neutrophils and in macrophages with respect to healthy subjects. A positive correlation between exhaled NO, iNOS expression and AHI was observed.


CONCLUSIONS
These data confirm the presence of airway inflammation in OSA and in obese patients, and suggest the possible role for NO and iNOS expression in neutrophils of the induced sputum as noninvasive markers to identify and monitor the airway inflammation in these subjects.
D000328:Adult; D001944:Breath Tests; D005260:Female; D005540:Forced Expiratory Flow Rates; D006801:Humans; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism*; D009765:Obesity / Q000150:complications / Q000378:metabolism*; D017286:Polysomnography; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000145:classification / Q000150:complications / Q000378:metabolism*; D013183:Sputum / Q000378:metabolism*
D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II