Abstract
Purpose:
Environmental pollution causes adverse effects on human health and the eyes are particularly vulnerable to these effects, as they are constantly exposed to the environment. The aim of the present study was to evaluate the redox status in human conjunctival epithelial cells after the incubation with diesel exhaust particles (DEP).
Methods:
The incubation was performed at different concentration of DEP (10, 50 and 100 μg/mL) for 24 hs and the following parameters were evaluated: reactive oxygen and nitrogen species production; protein oxidation; antioxidant enzymes activities (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST) and glutathione reductase (GR)); non-enzymatic antioxidant levels measured as total antioxidant capacity (TRAP) and reduced (GSH) and oxidized (GSSG) glutathione. One-way ANOVA test and Dunnett’s test as a post hoc test were used for statistical analysis.
Results:
The cells exposed to 50 and 100 μg/mL of DEP showed a significant increase in reactive oxygen species production (24%, p<0.01 and 45%, p<0.001, respectively) and in reactive nitrogen species production (257%, p<0.01 and 514%, p<0.001, respectively) compared to the control group. They also exhibited an increase in the activities of SOD (84% and 108%, p<0.001, respectively), GPx (41% and 50%, p<0.05 and p<0.01, respectively) and GST (42% and 45%, p<0.01, respectively). A decay in GR activity was observed (17% and 37%, p<0.05 and p<0.01, respectively), meanwhile CAT levels remained unchanged. DEP100 group also presented an increase in protein oxidation (58%, p<0.05). Furthermore, TRAP was significant reduced in both groups (42%, p<0.05 and 58%, p<0.01, respectively) as well as the GSH/GSSG ratio. There was no significant difference between DEP10 and control groups in all the measurements.
Conclusions:
The increase of reactive oxygen and nitrogen species production, the decrease in non-enzymatic antioxidants and the increase in the antioxidant enzymes activities are consequences of the exposure to DEP. These results suggest that the alteration of redox status could be a possible mechanism of damage in the human conjunctival epithelial cells exposed to this particular matter.