We have previously reported diminished immunohistochemical staining of decorin in lung tissue from patients with severe emphysema. The aim of this study is to investigate whether this diminished staining is due to a quantitative abnormal production of decorin by pulmonary fibroblasts in vitro. Therefore, we measured decorin (Western blot), collagen type I (ELISA), and fibronectin (ELISA) production by fibroblasts obtained from lung tissue of patients with severe and mild emphysema at basal culture conditions and after modulation with transforming growth factor-beta1, basic fibroblast growth factor, and interferon-gamma. Decorin production at basal culture conditions was significantly higher in fibroblast cultures from patients with severe emphysema compared to fibroblasts from mild emphysema. After stimulation with transforming growth factor-beta1 and basic fibroblast growth factor, decorin production was significantly more reduced in fibroblast cultures from patients with severe emphysema whereas collagen type I and fibronectin production were not affected. We conclude that decorin production by lung fibroblasts of patients with severe emphysema is dysregulated after modulation with cytokines known to be important in smoking associated inflammation. This dysregulation of decorin production may contribute to the impaired lung tissue repair, present in patients with emphysema, since these alterations in the extracellular matrix may cause diminished cytokine binding and neutralization.

To characterize the possible role of a dysregulated proliferative capacity of pulmonary fibroblasts in insufficient tissue repair in lungs from patients with pulmonary emphysema, the authors undertook in vitro proliferative studies with pulmonary fibroblasts obtained from lung tissue of patients with emphysema. A comparison was made with fibroblasts from control subjects. The authors determined the in vitro proliferative capacity of fibroblasts at basal culture conditions and after modulation with interleukin-1beta, interferon-gamma, transforming growth factor-beta(1), and basic fibroblast growth factor. Proliferative capacity was determined by measurement of 5-bromo-2-deoxyuridine (BrdU) incorporation. BrdU incorporation by fibroblast cultures from both groups was very similar. Fibroblast cultures from control subjects, however, incorporated more BrdU after incubation with interleukin-1beta than cultures from patients with emphysema (P<.05). On the other hand, transforming growth factor-beta(1) decreased incorporation of BrdU stronger in fibroblast cultures from control subjects than from patients with emphysema (P<.05). Thus, the proliferative capacity of fibroblast cultures isolated from lung tissue of patients with pulmonary emphysema is different from that of control subjects. Although the difference is small, it may be an essential contribution to the development of pulmonary emphysema that only occurs after repeated smoke-induced injury over many years of an individual's life.