MMP9 and chronic asthma: Most importantly, alveolar macrophages (AMs) from chronic asthma with a fast FEV1 decline spontaneously released a higher amount of MMP-9 (8.52 ± 3.53 ng/mL, n = 8, p < 0.05) than those of asthma with a slow FEV1 decline (0.99 ± 0.20 ng/mL, n = 13) or normal subjects (0.47 ± 0.20 ng/mL, n = 10).