Sulfur mustard triggers oxidative stress through glutathione depletion and altered expression of glutathione-related enzymes in human airways.

CONTEXT

Sulfur mustard (SM) is a lipophilic and reactive chemical compound that targets human airway system.

OBJECTIVE

Glutathione (GSH) depletion, oxidative stress (OS) status, and changes in expression of GSH-dependent antioxidant enzymes were considered in human mustard lungs.

MATERIALS AND METHODS

Lung biopsies and bronchoalveolar lavage (BAL) were collected from non-exposed (n = 10) individuals and SM-exposed patients (n = 12). Alterations in expression of GSH-dependent enzymes were studied using RT Profiler™ PCR array. OS was evaluated by determining BAL fluid levels of total antioxidant capacity (TAC), malondialdehyde (MDA), and GSH.

RESULTS

Mean TAC (0.142 ± 0.027 µmol/l) and GSH (4.98 ± 1.02 nmol/l) in BAL fluids of control group was significantly higher (p < .05) than those in SM-exposed patients (TAC = 0.095 ± 0.018 µmol/l and GSH= 3.09 ± 1.02 nmol/l), while MDA level in BAL fluids of these patients (0.71 ± 0.06 nmol/l) was significantly (p = .001) higher than that in controls (0.49 ± 0.048 nmol/l). Glutathione peroxidases (GPXs), glutathione-s-transferases (GSTs), and glutathione synthetase (GSS) enzymes were overexpressed in mustard lung biopsies, while glutathione reductase (GSR) was significantly downregulated (14.95-fold).

CONCLUSIONS

GSH depletion induced by GSR downregulation may be a major mechanism of SM toxicity on human lung. Despite overexpression of GSTs and GPXs genes, GSH depletion may decline the productivity of these enzymes and total antioxidants capacity, which is associated with OS.