MMP9 and chronic obstructive pulmonary disease: We observed characteristic pathological changes consistent with chronic bronchitis and emphysema which are characteristic of COPD, and found that icariin significantly decreased values of inflammatory scores, MLI and DI in CS-exposed mice, and inhibited the CS-induced production of TNF-α, IL-8 and MMP-9 in both BALF and serum, showing an obviously anti-inflammatory capacity in mice.