Cigarette smoking and lung destruction. Accumulation of neutrophils in the lungs of cigarette smokers.

TLDR

Lung destruction in emphysema linked to cigarette smoking is thought to be driven by elastase released by neutrophils that migrate to alveolar structures in response to smoke. The study aimed to directly evaluate whether cigarette smoke induces neutrophil accumulation in the lungs. Researchers isolated cell suspensions from bronchoalveolar lavage fluid and open lung biopsies of nonsmokers and smokers (with normal lungs or sarcoidosis) to assess neutrophil presence. Smokers exhibited markedly increased neutrophils in bronchoalveolar lavage fluid and lung biopsies versus nonsmokers, and alveolar macrophages from smokers released a neutrophil‑attracting chemotactic factor—an effect absent in nonsmokers unless their macrophages were exposed to smoke in vitro—indicating cigarette smoke attracts neutrophils by stimulating macrophage chemotaxis.

Abstract

It has been hypothesized that lung destruction in persons with emphysema associated with cigarette smoking is mediated by elastase released by neutrophils that have migrated to the alveolar structures in response to cigarette smoke. To directly evaluate this hypothesis, cell suspensions, isolated from bronchoalveolar lavage fluid and from open lung biopsies of nonsmokers and cigarette smokers with normal lung parenchyma and from open lung biopsies of nonsmokers and cigarette smokers who have sarcoidosis were evaluated for the presence of neutrophils. A significantly increased number of neutrophils was present in the cell suspensions isolated from bronchoalveolar lavage fluid and from open lung biopsies of both normal and sarcoid cigarette smokers compared with that in the nonsmokers (p less than 0.01, each comparison). Evaluation of the alveolar macrophages present in lavage fluid suggested a mechanism by which neutrophils may be attracted to the lungs of cigarette smokers: alveolar macrophages of cigarette smokers release a chemotactic factor for neutrophils, whereas alveolar macrophages of nonsmokers do not. In addition, alveolar macrophages of nonsmokers, after exposure to cigarette smoke, in vitro, are stimulated to release this chemotactic factor. These studies demonstrate that an increased number of neutrophils are present in the lungs of cigarette smokers compared with that in nonsmokers and suggest that cigarette smoke may attract neutrophils to the lung by stimulating alveolar macrophages to release a potent chemotactic factor for neutrophils.