MMP9 and asthma: ● High in severe and uncontrolled asthma, especially with persistent airflow limitation [162,163,166] ● Higher serum levels detected at the exacerbation rather than the stable phase of asthma [162,164] ● Promotes the production of matrix metalloproteinase 9 (MMP-9) thus plays a role in airway inflammation as well as in airway remodelling [165]