Fig. 7

DNMT1 gene silencing or pharmacologic inhibition ameliorates CS-induced emphysema and pulmonary apoptosis without affecting ROS. a HE staining in the lungs of the control (vector), CS exposure (CS + vector), CS exposure plus DNMT1-silencing plasmid (CS + DNMT1 shRNA) and CS exposure with AZA treatment (CS + AZA) groups. b ROS levels in lungs from the four groups. The CS exposure group had higher lung tissue ROS levels (RFU) than the control group (13.66 ± 3.04 vs. 3.80 ± 1.62, P < 0.01 by one-way ANOVA and LSD test). The CS plus DNMT1 shRNA and CS plus AZA groups also had higher ROS levels than the control group (12.79 ± 2.54 and 11.76 ± 2.74 vs. 3.80 ± 1.62, P < 0.01 by one-way ANOVA and LSD test). This indicates that inhibiting DNMT1 does not reverse CS-induced ROS production and supports the hypothesis that DNMT1 could be a downstream factor in oxidative stress. c, d MLI and DI were calculated in the four groups. Compared to the CS group mice, the CS + DNMT1 shRNA and CS + AZA mice had lower MLI and DI values (62.01 ± 7.87 vs. 42.60 ± 2.24 and 43.39 ± 4.37, 58.26 ± 7.69 vs. 23.89 ± 4.18 and 23.12 ± 4.36, respectively, P < 0.01 by Kruskal-Wallis test). e, f and g Lung function in the four groups. The results showed better TV, Cdyn and RI in the CS + DNMT1 shRNA and CS + AZA mice than in the CS-exposed alone mice (105.56 ± 12.67 and 105.88 ± 13.68 vs. 75.11 ± 9.08, 143.44 ± 17.36 and 147.00 ± 17.85 vs. 82.33 ± 7.09, 57.33 ± 5.77 and 57.25 ± 7.76 vs. 151.44 ± 8.35, respectively, P < 0.01 by one-way ANOVA and LSD test). (H)TUNEL staining was conducted in lung tissues from the four groups. → the TUNEL-positive nuclei. i The AI was calculated in the four groups. TUNEL revealed less AI (%) in the CS + DNMT1 shRNA and CS + AZA groups than in the CS group (4.01 ± 1.40 and 4.35 ± 1.24 vs. 47.02 ± 6.27, P < 0.01 by one-way ANOVA and LSD test). *P < 0.05 vs. the CS group, #P < 0.05 vs. the vector group. The data in the figure represent the mean ± SD