Compared with CS-treated control, CS-treated mice receiving nebulised DNase-I (DNase-I Neb. mice, Fig. 7a) showed alleviated emphysema-phenotype, as indicated by reduced FRC/BW (Fig. 7k) and MLI of alveoli (Fig. S13a, f), although there were only downward trends for total and different cell counts in BALF (Fig. 7b–d), histological scores (Fig. 7m, n), and mucin staining scores (Supplementary Fig. S13b, g) were observed in DNase-I Neb. mice. The gene discussed is MUC5AC; the disease is pulmonary emphysema.