The process of airway remodeling is potentially a crucial outcome of asthma, and has been associated with the increase in inflammatory cells specially macrophages, neutrophils, basophils and their mediators TGF-β, iNOS, ROS, NO, IL-12, IL-1β, TNF-α, TXA2, MPOs, MMP-9, ROS, histamine, LTC4, IL-4, and IL-13, which affect airway structural property and pulmonary functions [47, 74, 91, 92]. This evidence concerns the gene MMP9 and asthma.