Neutrophilic inflammation in induced sputum of patients with idiopathic pulmonary fibrosis.
BACKGROUND
Idiopathic pulmonary fibrosis (IPF) is a disease of unknown etiology. Biopsy and bronchoalveolar lavage studies have shown, that accumulation of inflammatory cells, particularily neutrophils, in the alveolar space is a relevant feature of the pathogenesis of IPF. This paper adresses the issue of whether the safe and non-invasive method of sputum induction is a suitable tool to study respiratory tract inflammation in IPF.


METHODS
In a cross-sectional analysis, 15 IPF patients and 14 healthy, non-smoking subjects underwent sputum induction. Total sputum cell counts, differentials, and the amount of interleukin (IL)-8, granulocyte-macrophage-colony stimulating factor (GM-CSF), and soluble ICAM-1 (sICAM) in sputum supernatant were analyzed.


RESULTS
IPF patients had increased sputum neutrophils (60 +/- 6 vs 22 +/- 3%, p = 0.0003), and supernatant concentrations of IL-8 (19 +/- 3 vs. 7 +/- 1 ng/ml, p = 0.0002), GM-CSF (205 +/- 43 vs. 122 +/- 36 pg/ml, p = 0.08) and sICAM (12 +/- 3 vs. 5 +/- 3 ng/ml, p = 0.01), when compared with healthy controls. Sputum IL-8 was correlated with sputum neutrophils (rho = 0.61, p = 0.0006) in all patients. The extent of sputum neutrophilia was also correlated with lung function impairment (vital capacity, % of predicted) in IPF patients (rho = -0.68, p = 0.007).


CONCLUSIONS
These data confirm the established role of neutrophilic inflammation in the pathogenesis of IPF, and show the potential of induced sputum to directly study inflammatory processes and surrogate markers in interstitial lung diseases like IPF.
Beeh
Kai Michael
KM
Pulmonary Department, Internal Medicine, University Hospital Mainz, Germany. k.beeh@3-med.klinik.uni-mainz.de
Beier
Jutta
J
Kornmann
Oliver
O
Buhl
Roland
R
D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000032:analysis; D003430:Cross-Sectional Studies; D005260:Female; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000032:analysis; D006801:Humans; D007249:Inflammation; D018799:Intercellular Adhesion Molecule-1 / Q000032:analysis; D016209:Interleukin-8 / Q000032:analysis; D008297:Male; D008875:Middle Aged; D018375:Neutrophil Activation; D011658:Pulmonary Fibrosis / Q000276:immunology*; D013183:Sputum / Q000166:cytology* / Q000276:immunology*
D015415:Biomarkers; D016209:Interleukin-8; D018799:Intercellular Adhesion Molecule-1; D016178:Granulocyte-Macrophage Colony-Stimulating Factor