Acute cigarette smoke-induced connective tissue breakdown requires both neutrophils and macrophage metalloelastase in mice

Synthetic serine elastase inhibitor reduces cigarette smoke-induced emphysema in guinea pigs

To test whether a serine elastase inhibitor could prevent or reduce emphysema, we exposed guinea pigs to cigarette smoke acutely, or daily for 6 months, and treated some animals with the neutrophil elastase inhibitor ZD0892. Acute smoke exposure increased lavage neutrophils and increased desmosine and hydroxyproline, measures of elastin and collagen breakdown; all these measures were reduced by ZD0892. Long-term smoke exposure produced emphysema and increases in lavage neutrophils, desmosine, hydroxyproline, and plasma tumor necrosis factor alpha (TNF-alpha). ZD0892 treatment returned lavage neutrophils, desmosine, and hydroxyproline levels to control values, and decreased airspace enlargement by 45% and TNF-alpha by 30%. Animals exposed to smoke for 4 months and then to smoke plus ZD0892 for 2 months were not protected against emphysema. Mice exposed to smoke showed increases in gene expression of neutrophil chemoattractant macrophage inflammatory protein-2, macrophage chemoattractant protein-1, and TNF-alpha at 2 hours along with increased plasma TNF-alpha; ZD0892 prevented the increases in macrophage inflammatory protein-2 and macrophage chemoattractant protein-1 expression and reduced plasma TNF-alpha levels to baseline. These data demonstrate that a serine elastase inhibitor ameliorates the inflammatory and destructive effects of cigarette smoke, and that these effects are mediated in part by neutrophils and by smoke-driven TNF-alpha production.