Upregulation of basic fibroblast growth factor in smokers with chronic bronchitis

The aim of the study was to investigate the expression of basic fibroblast growth factor (bFGF) and its receptor, fibroblast growth factor receptor (FGFR)-1, in the central airways of smokers with chronic bronchitis. The lobar bronchi from 17 subjects undergoing thoracotomy for solitary nodules were examined. All had a history of cigarette smoking, nine had symptoms of chronic bronchitis and airflow limitation, and eight were asymptomatic with normal lung function. Using immunohistochemical methods, bFGF and FGFR-1 expression in the total airway wall and the different airway compartments, i.e. bronchial glands, submucosal vessels and smooth muscle, was quantified. Moreover, to investigate the role of bFGF in angiogenesis, the number of submucosal vessels was quantified. Smokers with chronic bronchitis had an increased bFGF expression in the total airway wall compared with asymptomatic smokers, which was mainly due to bFGF upregulation in bronchial glands. By contrast, the expression of FGFR-1 and the number of submucosal vessels was similar in the two groups of subjects examined. In conclusion, smokers with chronic bronchitis have an increased expression of basic fibroblast growth factor in the central airways, which is mainly due to an increased expression in bronchial glands, suggesting the involvement of this growth factor in the pathogenesis of chronic bronchitis.