Decreased cytokine and chemokine mRNA expression in bronchoalveolar lavage in asymptomatic smoking subjects.

BACKGROUND

Smoking alters the inflammatory cell balance in the airways, often leading to repeated respiratory infections and, eventually, chronic obstructive pulmonary disease (COPD) in susceptible individuals.

OBJECTIVE

It was the aim of this study to evaluate alterations in the airway inflammatory balance caused by chronic cigarette smoke exposure.

METHODS

We compared results of biopsy and bronchoalveolar lavage (BAL) samples from non-smoking (n = 8) and smoking (n = 5; pack years 25.06 +/- 11.75, range 7.13-36.8) subjects without COPD.

RESULTS

In BAL samples, we found a significantly higher number of total cells (353 +/- 96 million vs. 114 +/- 52 million; p = 0.003) and macrophages (331 +/- 100 million vs. 84 +/- 36 million; p = 0.002) in asymptomatic smoking subjects in comparison with never-smokers. Macrophages correlated negatively with the forced expiratory volume in 1 s as percent of the predicted value (rho = -0.75, p = 0.003). Of 23 mediators examined, mRNA expression of cytokines interleukin (IL)-6, interferon-gamma, tumor necrosis factor-beta, IL-13 and chemokines CCL5, CCL3, CCL4 and CCL20 was significantly lowered in BAL cells of smokers compared with never-smokers and was negatively correlated with macrophages and positively correlated with the forced expiratory volume in 1 s as percent of the predicted value. Differential cell counts were similar between smokers and never-smokers in the bronchial biopsies.

CONCLUSION

We conclude that in a susceptible population, smoking suppresses inflammatory defense by inhibiting expression of inflammatory mediators in the airways on a large scale.