MMP9 and chronic obstructive pulmonary disease: In a study by Vlahos and coworkers, MMP-9 activity was elevated in severe COPD, closely related to neutrophilic inflammation, and in vivo, neutrophil activation was associated with glucocorticoid refractory release of MMP-9 [46] It is tempting to speculate that higher serum MMP-9 levels and a greater MMP-9/TIMP-1 ratio in patients with triple therapy is related to advanced disease and more exacerbations, but it is potentially an altered response to glucocorticoids.