[Effects of Nrf2 on gamma-glutamylcysteine synthase in lung of guinea pigs with bronchial asthma].

Aim: To investigate the effects of Nrf2 (Nuclear-E2 related factor) on gamma-glutamylcysteine synthase (gamma-GCS) in lung of guinea pigs with bronchial asthma.

Methods: 20 adult male guinea pigs were randomly divided into two groups (n = 10): control group (C group) and asthmatic group (A group), asthmatic model was established by ovalbumin intraperitoneal and ovalbumin inhalation. The reactive oxygen piece (ROS), reduced glutathione (GSH), oxidant glutathione (GSSG) and total GSH in lung tissue were examined respectively. Inflammatory cell infiltration and index of remodeling of bronchiole were detected. In situ hybridization detected the gamma-GCS heavy subunit (gamma-GCS h) mRNA in lung tissue. Immunohistochemistry detected the expression of Nrf2 protein and gamma-GCS protein in lung tissue. RT-PCR measured the expression of Nrf2 mRNA in lung tissue. The activity of gamma-GCS was measured by coupled enzyme assay.

Results: (1) The number of eosinophils and lymphocytes in bronchiole of A group were significantly higher than that of C group (P < 0.05), the remodeling of bronchiole in A group was definite. (2) ROS (U/mg pro), GSSG (micromol/g pro) and total GSH in lung tissue of A group were significantly higher than that of C group (P < 0.01). The GSH/GSSG in lung tissue of A group was much lower than that of C group (P < 0.01), GSH in lung tissue showed no difference between A group and C group. (3) Immunohistochemistry indicated that Nrf2 protein and gamma-GCS protein were more positively expressed in A group than that in C group (P < 0.01). In situ hybridization discovered that the expression of gamma-GCS-h mRNA in lung tissue of A group was more positive than that of C group. (4) RT-PCR showed that the expression of Nrf2 mRNA was no difference between A group and C group (P > 0.05). (5) The activity of gamma-GCS of A group was (28 +/- 8)U which was significantly higher than that of C group (9 +/- 2)U (P < 0.01). (6) Linear correlation analysis indicated that in lung tissue of guinea pig with asthma there existed strongly positive relationship among ROS, GSSG and the expression of Nrf2, gamma-GCS mRNA, gamma-GCS protein, the activity of gamma-GCS, there existed strongly negative relationship among GSH/GSSG and the expression of Nrf2, gamma-GCS mRNA, gamma-GCS protein, the activity of gamma-GCS.

Conclusion: There existed oxidative stress in lung of guinea pigs with bronchial asthma, which possibly positively regulated gamma-GCS via up regulating transcription factor Nrf2.