Structure and function of small airways in smokers: relationship between air trapping at CT and airway inflammation.
OBJECTIVE
To use quantitative computed tomography (CT) to compare lung attenuation with both inflammatory infiltration and in vitro reactivity of peripheral airways in smokers scheduled to undergo lung resection for localized pulmonary lesions.


METHODS
Attenuation was measured in nine ex-smokers, 13 current smokers, and eight nonsmoking control subjects by using CT with respiratory gating and a contour-tracing algorithm. After lung resection in smokers, peripheral bronchi were dissected and studied in terms of both inflammation (by using immunohistochemistry to examine glycolmethacrylate-embedded specimens) and mechanical activity (by using an isolated organ bath system). Comparisons between groups were made by using analysis of variance and subsequent unpaired t tests. Correlations were evaluated by using the Pearson coefficient and stepwise multiple regression analysis.


RESULTS
The difference between inspiratory and expiratory attenuation was significantly higher in control subjects (-128 HU +/- 11 [SD]) than in ex-smokers (-77 HU +/- 10; P =.004) or current smokers (-67 HU +/- 11; P =.001). Cells infiltrating the smooth muscle increased with the decrease in expiratory attenuation (r = -0.46; P =.03) and the increase in inspiratory versus expiratory attenuation (r = 0.66; P =.001). Mast cell and neutrophil infiltration of smooth muscle was the most important factor in this relationship. Cellular infiltration of the smooth muscle increased with the decrease of in vitro relaxation response to salbutamol.


CONCLUSIONS
In smokers, air trapping is correlated with inflammatory infiltration of the smooth muscle layer of small airways.
Laboratoire de Physiologie Cellulaire Respiratoire, INSERM E-9937, Université Victor Ségalen Bordeaux 2, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France.
Patrick
P
Berger
Francois
F
Laurent
Hugues
H
Begueret
Vincent
V
Perot
Rozen
R
Rouiller
Chantal
C
Raherison
Mathieu
M
Molimard
Roger
R
Marthan
J Manuel
JM
Tunon-de-Lara
D000328:Adult; D000368:Aged; D001980:Bronchi / Q000473:pathology* / Q000503:physiopathology; D001995:Bronchography; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008168:Lung; D008297:Male; D008875:Middle Aged; D009130:Muscle, Smooth / Q000473:pathology; D012907:Smoking / Q000473:pathology*; D016540:Smoking Cessation; D014057:Tomography, X-Ray Computed