Airway angiogenesis in stable and exacerbated chronic obstructive pulmonary disease

Angiogenesis is a prominent feature of structural tissue remodelling that occurs in chronic airway diseases, including chronic obstructive pulmonary disease (COPD). The aim of this study was to evaluate the airway levels of VEGF, angiogenin, IL-8 and TNF-α in patients with COPD during the stable phase and during acute exacerbation of the disease. We analysed induced sputum samples from 28 patients with COPD. Thirteen of these patients were followed up and second samples of sputum were obtained during acute exacerbation of the disease. The two control groups consisted of 12 healthy smokers and seven healthy non-smokers, all with normal lung function tests. Concentrations of VEGF, angiogenin, IL-8, TNF-α and bFGF were measured by cytometric bead array. In the induced sputum of patients with stable COPD, concentrations of VEGF (P < 0.001, P = 0.02), angiogenin (P < 0.0001, P < 0.0001), IL-8 (P < 0.0001, P = 0.0021) and TNF-α (P < 0.001, P = 0.03) were significantly elevated in comparison with healthy smokers and non-smokers. No additional elevation of angiogenic factors was demonstrated at the time of exacerbation. There was a significant negative correlation between FEV1 and VEGF (P < 0.05, r = -0.38), angiogenin (P < 0.0001, r = -0.68) and IL-8 (P < 0.001, r = -0.54) among smokers (smoking COPD patients and healthy smokers). No significant differences were observed between groups of healthy smokers and non-smokers. These results showed increased airway angiogenesis in patients with COPD. Moreover, VEGF, IL-8 and angiogenin negatively correlated with pulmonary function, which suggests their important role in COPD airway remodelling. However, no additional angiogenic activation was found during exacerbation of COPD.