Objective: To investigate the mechanism of the action of glucocorticoid induced leucine zipper (GILZ) in inflammatory reaction.
Methods: Human monocyte cell line THP-1 cells were divided into two groups and cultured in non-serum RPMI1640 medium.In one group the cells were treated with dexamethasone (DEX). Twelve hours later total RNA and total protein were abstracted in both two groups. The mRNA encoding for expression of GILZ was semiquantitatively detected by reserve transcriptase-polymerase chain reaction (RT-PCR). Protein expression of nuclear factor-KappaB (NF-KappaB) p65 and activator protein-1 (AP-1) were assessed by Western blotting. Peripheral blood of 10 trauma patients [injury severity score (ISS) >or=16 scores] were collected and the leukocytes were isolated within 24 hours after trauma. The leukocytes were divided into two groups and cultured in non-serum medium. In one group the cells were treated with DEX. Twelve hours later total RNA and total protein were abstracted in both two groups. The mRNA encoding for expression of GILZ was semiquantitatively detected by RT-PCR. Protein expression of NF-KappaB p65 and AP-1 were assessed by Western blotting.
Results: Stimulated by DEX, the expression of GILZ mRNA was increased both in THP-1 cells and the leukocytes of trauma patients compared with those of control groups (both P<0.01). Whereas, protein expressions of NF-KappaB p65 and AP-1 of THP-1 cells and leukocytes in peripheral blood of trauma patients were decreased in the stimulation groups compared with those of control groups (all P<0.01).
Conclusion: The expression of GILZ gene is up-regulated by glucocorticoid. Overexpression of GILZ inhibits NF-KappaB and AP-1 activities, suggesting that GILZ possesses anti-inflammatory function.