Transforming growth factor beta 1 (TGF beta 1) gene expression by eosinophils in asthmatic airway inflammation.

Abstract

The increase in thickness of bronchial walls by such structural changes as subepithelial fibrosis contributes to the severity and chronicity of asthma by amplifying airway narrowing. However, the pathogenesis of this structural alteration is not known. Transforming growth factor beta 1 (TGF beta 1) is known to have biologic activities relevant to the cellular and molecular events in subepithelial fibrosis, such as the deposition of collagen I and III and the increase of myofibroblasts beneath the epithelial basement membrane. Therefore, we examined TGF beta 1 gene expression in bronchial biopsy tissues from five severe asthmatics, five mild asthmatics, and five normal subjects using in situ hybridization combined with histochemical staining. Cells expressing TGF beta 1 mRNA were detected in tissues from four normal subjects, one mild asthmatic, and five severe asthmatics. The density of positive cells in severe asthmatic tissues (52.1 +/- 22.7, mean +/- SD/mm2) was significantly greater than that in mild ...