Expression of vascular endothelial growth factor, basic fibroblast growth factor, and angiogenin immunoreactivity in asthmatic airways and its relationship to angiogenesis

Abstract

Background: Angiogenesis is a prerequisite for airway remodeling in bronchial asthma. Several growth factors may play important roles in inflammation and angiogenesis through effects on inflammatory cell infiltration or neovascularization.

Objective: We sought to compare bronchial vascularity and expression of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and angiogenin in bronchial biopsy specimens from asthmatic and healthy control subjects.

Methods: Bronchial biopsy specimens were obtained from 16 asthmatic subjects and 9 normal control subjects. The number of vessel profiles and the vascular area per unit area on a histologic section were estimated by using computerized image analysis after staining for type IV collagen in vessel walls. Numbers of VEGF+, bFGF+, and angiogenin+ cells were determined by means of immunoreactivity.

Results: The airways of asthmatic subjects had significantly more vessels (P < .05) and greater vascular area (P < .001) than that observed in control subjects. Asthmatic subjects exhibited higher VEGF and bFGF and angiogenin immunoreactivity in the submucosa than did control subjects (P < .001, respectively). Significant correlations were detected between the vascular area and the numbers of angiogenic factor-positive cells (VEGF: rs = 0.93, P < .001; bFGF: rs = 0.83, P < .001; angiogenin: rs = 0.88, P < .001) within the asthmatic airways. Furthermore, the degree of vascularity was inversely correlated with airway caliber and airway responsiveness. Colocalization analysis revealed that the angiogenic factor-positive cells were CD34+ cells, eosinophils, and macrophages.

Conclusion: Our results suggest that increased vascularity of the bronchial mucosa in asthmatic subjects is closely related to the expression of angiogenic factors, which may then contribute to the pathogenesis of asthma.