Localization of transforming growth factor β1 in airway mucosa of toluene diisocyanate-induced asthma

Abstract

Background and objective: There have been some reports on the expression of TGF β-an anti-inflammatory and fibrosing cytokine in airway mucosa of asthmatics. However, the ex- pression of TGF β1 in bronchial mucosa of TDI-induced asthma is not known. The aim of this study was to observe immunolocalization of TGF β1 in airway mucosa of TDI-induced asthma. Methods: TGF β1 expressions were compared using immunohistochemistry in bronchial muco- sa from 22 subjects with TDI-induced asthma (group I: 10 newly diagnosed, group II: 12 subjects with persistent asthma symptoms for more than 4 years after diagnosis), and 8 non- asthmatics undergoing pneumonectomy from lung tumor. The distribution and intensity of expression were analyzed by two observers in four areas of bronchial tissue-epithelium(EP), vascular endothelium(VE), smooth muscle(SM), and mucous glands(MG). Results: Positive rates of TGF β1 expression for groups Ⅰ and Ⅱ in the four areas were as follows; EP (50% vs 100%, p<0.05), VE(40% vs 100%, p<0.05), SM(33.3% vs 100%, p<0.05), and MG(66.7% vs 80%, p>0.05). Grades of TGF β1 expression of EP, VE, and SM were significantly higher in group II than in group I(p<0.05, respectively). There was no significant difference in distribution and intensity of TGF β1 expression between TDI-induced asthma and controls(p>0.05, respectively). Conclusion: TGF β1 expressions of EP, VE, SM and MG were noted in airway mucosa of TDI-induced asthma and expressions of EP, VE, and SM were more intense and frequent in patients with persistent asthma symptoms.