Abstract
Remodelling of the airways involves a thickening of the reticular lamina of the basement membrane and proliferation of the smooth muscle. IGF-1 stimulates proliferation of a variety of mesenchymal cell types and collagen synthesis. We hypothesis that an increase in IGF-1 progresses airway remodelling. We investigated whether the levels of IGF-1 in 15 mild to moderate asthmatics were higher than in five normal controls. In addition, we examined whether the levels of IGF-1 correlated with FEV 1% and bronchial responsiveness. The IGF-1mRNA expression showed no significant difference between asthmatics and normal controls in bronchial biopsies, but in BALF asthmatics the IGF-1mRNA expression was higher than in normal controls. We observed a significant increase of IGF-1 protein levels (p<0.05), eosinophils (p<0.05), total cells in BALF (p<0.05) in the asthmatics compared with normal controls. This was accompanied by a significant increase in the thickness of the reticular lamina of the basement membrane (p<0.05) . Significant correlation was found between the levels of IGF-1 and eosinophils (%) in BALF (Rs=0.45, p=0.04), and the thickness of the reticular lamina of the basement membrane (Rs=0.56, p=0.01) . These results suggest that an increase in IGF-1 progresses the thickness of the reticular lamina of the basement membrane and an increase in IGF-1 is correlated with eosinophil increase, and therefore, may progress remodelling of the airways.
