Elevated levels of transforming growth factor-beta1 in serum of patients with stable bronchiectasis

Abstract

Bronchiectasis is a condition, where serious and repeated infections and abnormal development of the lung result in permanent damage to the airways. Transforming growth factor-b1 (TGF-b1) is a major fibrogenic cytokine, the expression of which is increased in the lungs or bronchoalveolar lavage fluid of patients with inflammatory lung diseases. However, little is known on the expression of TGF-b1 levels in bronchiectasis. We measured the serum TGF-b1 concentrations in 95 patients with stable bronchiectasis (63 women; mean ± SD age, 58.9 ± 14.1 years) and 68 control subjects (23 women; 48.9 ± 12.8 years) by ELISA, and correlated these with clinical parameters. The serum TGF-b1 levels were significantly higher in bronchiectatic patients compared with control subjects (mean ± SEM, 2710.7 ± 197.4 pg/ml vs 1649.2 ± 124.2 pg/ml; P < 0.001). Smoking controls tended to have a higher serum TGF-b1 level but no differences were found between nonsmokers and smokers, with or without Pseudomonas aeruginosa infection in bronchiectatic patients. There was no correlation between serum TGF-b1 levels with FEV1 (% predicted), FVC (% predicted), 24 h sputum volume, number of bronchiectatic lung lobes and white blood cell (WBC) count (P > 0.05). In conclusion, systemic TGF-b1 appears to be elevated in bronchiectasis independent of other clinical parameters, and the level of serum TGF-b1 may be used to predict the presence or absence of the disease. Further studies on the potential mechanisms and pathogenesis implications of this elevation should be pursued in future. (Supported by a University of Hong Kong, URC/CRCG Research Grant)