| Objective To investigate the effect of PM2.5on the toxic effects, phagocytic function and oxidative damage of human monocyte-derived macrophage (MDM) generated from chronic obstructive pulmonary disease (COPD) patients and healthy subjects.Methods The PM2.5was collected during heating period in the urban areas of Lanzhou.32COPD patients, with22males and8females, mean age70.1±7.5years, and26healthy controls, with20males and6females, mean age65.7±5.0years, were included in this experiment, and the peripheral blood mononuclear cells were isolated from these subjects, then transformed into MDM by using the GM-CSF in vitro. The MDM from COPD patients and healthy subjects were divided into4groups:control group (group A and group C). PM2.5group (group B and group D). MTT assay was used to test the toxic effects of PM2.5on MDM. Flow cytometry and laser scanning confocal microscopy were applied to characterize the effect of PM2.5on the phagocytosis of fluorescein-labeled Escherichia coli BioParticles by MDM. Receptor expression was measured by flow cytometry. The total antioxidative capacity (TAC) in cultural supernatant was measured by o-phenanthroline colorimetric analysis. The content of malondialdehyde (MDA) in cultural supernatant was mwasured by thiobarbituricacid colormetric analysis. The glutathione peroxidase (GSH-PX) capacity in cultural supernatant was measured by the method of DNTB.Results①Cell toxicity experiment:PM2.5was toxic to human MDM, with the increase of PM2.5concentration and intervention time, the viability of MDM decreased, showing significant dose and time effect relationship(P<0.05).②The effect on the phagocytic function:goup A showed reduced phagocytic responses to Escherichia coli compared with group C(20.22±2.22vs56.88±7.27). the difference has statistic meaning;PM2.5caused significant impact on the phagocytic function of MDM from both group B and group D (4.91±0.67),(44.09±5.92)(P all <0.01). After exposure to PM2.5. the change value of MFI in COPD group was larger than healthy control group (75.26±5.33vs22.30±6.65)%(P＜0.05)③The degree of oxidative stress:The level of TAC in the cell supernatant fluid from group A (4.06±0.22) was lower than group C (5.07±0.30). the level of GSH-PX in the cell supernatant fluid in group A (47.10±4.13) was lower than group C (88.22±2.51). the content of MDA in the cell supernatant fluid in group A (4.75±0.53) was higher than group C (2.10±0.29)(P all<0.01). After exposure to PM2.5for24h. the TAC level in the cultural supernatant from both group B and group D were lower than those in their control groups (2.86±0.36vs4.06±0.22),(4.24±0.30vs5.07±0.30). the GSH-PX level in the cultural supernatant from both group B and group D were lower than those in their control groups (22.31±2.61vs47.10±4.13),(67.11±3.47vs88.22±2.51), while the content of MDA in the cultural supernatant from both group B and group D was higher than those in their control groups (9.78±0.85vs4.75±0.53),(3.78±0.81vs2.10±0.29), the difference was statistically significant (P all<0.01). After exposure to PM2.5, the amplitude of oxidative stress indicators in COPD group was significantly higher than the healthy control group, which TAC activity variations were (29.36±9.99vs16.31±6.29)%, GSH-PX level variations (52.49±5.18vs23.87±4.60)%, MDA content variations (107.02±16.34vs84.20±29.63)%(P all<0.05).④The correlation between the phagocytic function and the oxidative stress:there were positive correlations between the MDM phagocytic function damages and the level of TAC in COPD goup and COPD PM2.5group (r respectively=0.840,0.623).there were positive correlations between the MDM phagocytic function damages and the level of GSH-PX in COPD goup and COPD PM2.5group (r respectively=0.731,0.579), there were negative correlations between the MDM phagocytic function damages and the content of MDA in COPD goup and COPD PM2.5group (r respectively=-0.897,-0.605)(Pall<0.05); there were negative correlations between the level of TAC and the content of MDA in COPD goup and COPD PM2.5(r respectively=-0.745,-0.747). there were negative correlations between the level of GSH-PX and the content of MDA in COPD goup and COPD PM2.5(r respectively=-0.756,-0.734), there were positive correlations between the level of TAC and the level of GSH-PX in COPD goup and COPD PM2.5(r respectively=0.612,0.767)(Pall<0.05).Conclusion MDM from COPD patients demonstrated reduced phagocytosis for Escherichia coli with healthy control group, this defect in phagocytosis of bacteria that most frequently cause acute exacerbations of COPD was likely to be an important factor leading to colonization of the lower airways and the propensity for bacterial exacerbations,Atmospheric inhalable particles PM2.5was toxic to MDM, with a significant dose and time-related effect. PM2.5impaired the phagocytosis of MDM,and damage of the phagocytic ablility of MDM from COPD group was stronger than those in healthy control group, this suggested that PM2.5exposure affected the phagocytic function of macrophage,and COPD patients were particularly more susceptible to the adverse effects of PM2.5. PM2.5could cause an oxidative damage in MDM, there were positive correlations between the MDM phagocytic function damages and the oxidative damage, this may be the potential mechanism of the damage to the phagocytosis. |
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