Abstract

BACKGROUND
Exposure to swine dust causes an intense airway inflammation with increased levels of interleukin 8 (IL-8) and predominantly neutrophils in the nasal and bronchoalveolar lavage fluids of healthy human subjects. It is not clear which components in the swine house environment are responsible for the airway reaction. The aim of the present study was to evaluate and compare the effect in vitro of swine dust components on human alveolar macrophages and bronchial epithelial cells.


METHODS
Normal human bronchial epithelial cells (NHBE), human pulmonary epithelial carcinoma cell line (A549), and human alveolar macrophages were stimulated with swine dust, lipopolysaccharides (LPS; present in Gram negative bacteria), grain dust (swine feed components), and glucans (a structural component of fungi) in a dose response manner (1–100 μg/ml).


RESULTS
Swine dust at a concentration of 100 μg/ml increased IL-8 production 20 fold in NHBE cells, 28 fold in A549 cells, and 15 fold in macrophages. LPS (100 μg/ml) stimulated all three cell types significantly, in macrophages to the same extent as swine dust, but in NHBE and A549 cells swine dust was 5–8 times as potent. Grain dust (100 μg/ml) had no effect in A549 cells but stimulated NHBE cells and macrophages. Glucans (100 μg/ml) stimulated A549 cells and macrophages but not NHBE cells. Both glucans and grain dust were weaker stimuli than swine dust and LPS. The LPS content of swine dust solution was 2.16 (0.2) ng/100 μg and of grain dust was 0.53 (0.04) ng/100 μg.


CONCLUSIONS
Swine dust is a strong stimulus for IL-8 production in both bronchial epithelial cells and human alveolar macrophages, whereas LPS has different potency in these cells.