Histone Deacetylase Regulates IL‐4 Gene Expression in Mast Cells by Oxidative Stress

Abstract

Objectives: Many pro-inflammatory cytokines are regulated by acetylation and deacetylation of core histone. Since dysregulation of Th2 cytokine production is a key for the pathogenesis of allergic diseases, we examined the role of histone deacetylase (HDAC) on expression of IL-4 gene in mast cells. We also examined whether oxidative stress has some impact on HDAC activity. Methods: RBL-2H3 cells, a rat mast cell line, were sensitized overnight with DNP-specific IgE. The cells were then treated with HDAC inhibitors (trichostatin A) for 15 min and stimulated with DNP-antigen. After 2 hour incubation, total RNA was isolated to determine the level of IL-4 gene transcription by real-time reverse transcriptase polymerase chain reaction (Taqman system). After incubated with H2O2 for 0 to 24 hours, HDAC activity was measured in nuclear extracts obtained from the RBL-2H3 cells with HDAC Fluorescent activity assay kit (BIOMOL) as well as the detection of IL-4 mRNA. Results: IL-4 mRNA expression was induced with antigen in IgE-sensitized RBL-2H3 cells. Pretreatment of trichostatin A and H2O2 enhanced IL-4 mRNA expression with dose-dependent manner. There is 5-fold induction of IL-4 mRNA by HDAC inhibitors. HDAC activity of RBL-2H3 cells were reduced with H2O2 treatment. Conclusions: Our results suggest that oxidative stress may up-regulate IL-4 gene expression in mast cell via decrease of HDAC activity.