Altered expression of the Smad signalling pathway: implications for COPD pathogenesis.

Pulmonary emphysema, as a feature of chronic obstructive pulmonary disease (COPD), is characterised by destruction of alveolar tissue. The present authors previously demonstrated reduced decorin expression in the peribronchial area of COPD patients, reflecting an altered extracellular matrix (ECM) modulation. Decorin transcription is regulated by the transforming growth factor (TGF)-beta-Smad pathway, the key intracellular signal route for initiation of ECM component gene transcription. Whether this pathway is aberrantly expressed in COPD is not known. An immunohistochemical study was performed to compare protein expression of TGF-beta1 and TGF-beta receptors, Smad 2, 3, 4 and 7, and decorin in lung tissue of Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages II and IV COPD patients and controls. Epithelial expression of the inhibitory Smad 7 was significantly lower in patients with GOLD stages II and IV than in controls, with other Smad protein expressions being similar in the groups. The expression of TGF-beta1 and TGF-beta receptor type I was significantly lower in stage II patients. Decorin staining of the adventitia and alveolar walls was significantly reduced in COPD stage IV. In conclusion, the transforming growth factor-beta-Smad pathway is aberrantly expressed in chronic obstructive pulmonary disease patients, implying an abnormal tissue repair ultimately resulting in reduced decorin production. The results of the present study contribute to better understanding of the pathogenesis of emphysema and the airway fibrosis observed in chronic obstructive pulmonary disease patients.

High ICAM-1 gene expression in pulmonary fibroblasts of COPD patients: a reflection of an enhanced immunological function.

Chronic obstructive pulmonary disease (COPD) is characterised by destruction of extracellular matrix (ECM) in parenchymal areas, whereas the bronchial walls can show fibrosis. In addition, an extensive inflammatory process is observed. CD8+ T-cells, located throughout the lung, and epithelial cells in centrally located airways, produce cytokines involved in the inflammatory process. These cytokines may influence the present fibroblasts, the key effectors in the defective ECM repair and maintenance in COPD. The current authors explored the effects of the cytokine microenvironment on cell-cell interaction gene expression in pulmonary fibroblasts of controls (n = 6), and Global Initiative for Chronic Obstructive Lung Disease stage II (n = 7) and stage IV (n = 7) COPD patients. The current authors simulated the in vivo microenvironment using supernatants of CD3/CD28 stimulated CD8+ T-cells isolated from peripheral blood of COPD patients, supernatant of a bronchial-epithelial cell line, or a combination of both. The present data show that fibroblasts of chronic obstructive pulmonary disease patients display an altered response to the cytokine microenvironment, depending on both the disease stage and the central or peripheral location in the lung. Especially adhesion-related genes are upregulated in fibroblasts of chronic obstructive pulmonary disease patients, which can indicate a more pronounced role of fibroblasts in the inflammatory process in chronic obstructive pulmonary disease, possibly resulting in reduced function as effectors of extracellular matrix repair.