RELEASE OF TRANSFORMING GROWTH-FACTOR-BETA (TGF-BETA) AND FIBRONECTINBY ALVEOLAR MACROPHAGES IN AIRWAY DISEASES

Asthma and chronic bronchitis are associated with airway remodelling, and airway macrophages are present in bronchial inflammation. TGF-beta and fibronectin released by alveolar macrophages possess a fibrogenic potency. The potential role of alveolar macrophages in airway remodel ling was studied in asthma and chronic bronchitis by the release of TG F-beta and fibronectin. Alveolar macrophages were isolated by bronchoa lveolar lavage in 14 control subjects, 14 asthmatics and 14 chronic br onchitics. The spontaneous and lipopolysaccharide (LPS)- or concanaval in A (Con A)-induced release of TGF-beta and fibronectin was measured by ELISA. Alveolar macrophages from chronic bronchitics spontaneously release greater amounts of TGF-beta and fibronectin than those from as thmatic and control subjects. Alveolar macrophages from asthmatics rel ease greater amounts of TGF-beta and fibronectin than those from contr ol subjects. The spontaneous release of TGF-beta is significantly corr elated with that of fibronectin. Fibronectin release was significantly reduced after LPS stimulation, and TGF-beta release was significantly increased after LPS stimulation, except in chronic bronchitis patient s. Con A increased the release of TGF-beta in cells from normal subjec ts. This study suggests that activated macrophages play a role in airw ay remodelling in chronic bronchitis and to a lesser extent in asthma.