Table 1.

Comparison of remodeling between upper and lower airways.

	Lower airways	Upper airways
Epithelium	Evident structural changes with rupture franca	Subtle structural changes
Reticular basement membrane	Mainly thickening and collagen I and III deposits	Similar to lower airways
Blood vessels	Increased vascularization, vasodilatation and microvascular extravasation	Angiogenesis not yet demonstrated conclusively. Presence of mild vascular changes
Glands	Goblet cell and mucous gland hyperplasia and increased mucus production	Distended, degenerated and obstructed acini and ducts
Response to therapy	Inhaled corticosteroids decrease subepithelial fibrosis, there is decreased basement membrane thickening and bronchial hyperreactivity	Absence of conclusive studies