Study objectives: Neutrophilic airway inflammation may
underlie the pathogenesis of COPD. We examined repeated measurements of
the fractional concentration of exhaled nitric oxide (FENO) and the
correlation with cells and mediators in induced sputum (IS) from
patients with COPD.
Participants: Eleven COPD subjects
(9 men and 2 women, aged 46 to 69 years) with predicted
FEV1 of 45 to 70%.
Setting: A hospital
prospective study with four visits at two weekly intervals.
Interventions: FENO and spirometry were assessed at all
visits, and IS for differential cell count, leukotriene-B4
(LTB4) and interleukin (IL)-8, nitrite, and nitrate at
visit 1, visit 3, and visit 4.
Results: During the
study, there were significant declines in mean percent predicted
FEV1, from 55.2 to 51.6% (p = 0.029), and mean
FEV1/FVC ratio, from 50.4 to 45.4% (p = 0.001),
accompanied by a significant increase in FENO geometric mean (95%
confidence limits), from 15.2 (10.9 to 21.2) to 23.6 (17.1 to 32.4)
parts per billion (p = 0.037), and sputum LTB4, from 1.79
(1.03 to 3.11) to 3.57 (1.95 to 6.53) ng/mL (p = 0.033), but no
significant change in other sputum parameters. From visits 1 to 4, the
change in percent neutrophils correlated with the changes in FENO and
IL-8 (r = 0.648, p = 0.028;
r = 0.60, p = 0.05, respectively). Hypertonic saline
solution induction of sputum caused a fall in FEV1, from
1.83 ± 0.44 to 1.46 ± 0.44 L (p = 0.049).
Conclusions: The worsening spirometry results were
accompanied by significant increases in FENO and sputum
LTB4. FENO may be related to neutrophilic inflammation
driven by the chemoattractant IL-8. FENO and IS may be useful markers
of airway inflammation in COPD patients. Sputum induction with
hypertonic saline solution causes a significant fall in
FEV1 requiring appropriate caution.