Effect of PM2.5 on the level of nuclear factor erythroid-2 related factor 2 in chronic obstructive pulmonary disease mice and its relationship with oxidative stress

Abstract

To explore the effects of fine particulate matter on the level of nuclear factor erythroid-2 related factor 2 (Nrf2) in pulmonary tissues of chronic obstructive pulmonary disease (COPD) mouse models and its relationship with oxidative stress. Totally 40 BALB/c mice were randomly divided into normal control group, normal PM2.5 group, COPD control group and COPD PM2.5 group.COPD mice were established using exposure of cigarette smoking.PM2.5 (20 mg/kg) was intratracheally instilled in PM2.5 group mice.Mice pulmonary function was measured by mice noninvasive body plethysmograph and lung histopathology was observed in normal control group and normal PM2.5 group mice.The mRNA and protein expression of Nrf2 was measured with real-time polymerase chain reaction (PCR) and Western blot methods.Total antioxidative capacity (TAC) was measured by O-phenanthroline colorimetry.Glutathione peroxidase (GSH-PX) was measured by improved Hafeman colorimetry and malondialdehyde (MDA) by thiobarbiturieacid colorimetry. Nrf2 mRNA and protein in normal control group, normal PM2.5 group, COPD control group and COPD PM2.5 group were 1.00, 4.46±0.42, 4.93±0.63, 6.41±0.35 and 0.92±0.08, 1.23±0.07, 1.20±0.09, 1.43±0.10.Nrf2 mRNA and protein in COPD control group were increased than those in normal control group while those in normal PM2.5 group and COPD PM2.5 group were respectively higher than each control group.Comparing to normal PM2.5 group, the Nrf2 mRNA and protein in COPD PM2.5 group were increased (all P<0.01). TAC and GSH-PX in each group were (5.1±0.4), (2.9±0.4), (3.3±0.3), (1.8±0.3) and (13.4±0.5), (9.9±0.7), (9.8±0.7), (7.0±0.6) U/mgpro.TAC and GSH-PX in COPD control group were decreased than those in normal control group while those in normal PM2.5 group and COPD PM2.5 group were respectively lower than each control group.Comparing to normal PM2.5 group, the Nrf2 mRNA and protein in COPD PM2.5 group were decreased (all P<0.01). MDA in each group were (2.9±0.4), (4.8±0.5), (4.5±0.3), and (6.2±0.4) nmol/mgpro.MDA in COPD control group were increased than those in normal control group while those in normal PM2.5 group and COPD PM2.5 group were respectively higher than each control group.Comparing to normal PM2.5 group, the MDA in COPD PM2.5 group were increased (all P<0.01). Positive correlations were observed between Nrf2 mRNA, protein and MDA, while negative correlations were observed between Nrf2 mRNA, protein and TAC, GSH-PX in all groups (all P<0.05). PM2.5 can induce Nrf2 expression and aggravate oxidative stress in COPD mice.The increased expression of Nrf2 is closely associated with oxidative stress.