IκBα glutathionylation and reduced histone H3 phosphorylation inhibit eotaxin and RANTES

Airway smooth muscle cells (ASMCs) secrete eotaxin and RANTES (regulated on activation, normal T-cell expressed and secreted) in response to tumour necrosis factor (TNF)-?, which is inhibited by the nuclear factor (NF)-?B inhibitor dimethylfumarate (DMF). NF-?B/I?B (inhibitor of NF-?B) glutathionylation and changes in chromatin remodelling can inhibit NF-?B activity. In this study, we determined whether NF-?B/I?B glutathionylation and reduced histone H3 phosphorylation might underlie the inhibitory effect of DMF on NF-?B activity, and eotaxin and RANTES secretion. Primary human ASMCs were treated with DMF, diamide and/or glutathione (GSH) ethylester (OEt) prior to TNF-? stimulation and were subsequently analysed by ELISA, electrophoretic mobility shift assay, immunofluorescence, co-immunoprecipitation or immunoblotting. DMF reduced intracellular GSH and induced I?B? glutathionylation (I?B?-SSG), which inhibited I?B? degradation, NF-?B p65 nuclear entry and NF-?B/DNA binding. In addition, DMF inhibited the phosphorylation of histone H3, which was possibly mediated by the inhibitory effect of DMF on mitogen- and stress-activated protein kinase (MSK)-1. However, p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase MAPK and MAPK phosphatase-1, upstream of MSK-1, were not inhibited by DMF. Importantly, DMF-mediated effects on NF-?B, histone H3, eotaxin and RANTES were reversed by addition of GSH-OEt. Our data suggest that DMF inhibits NF-?B-dependent eotaxin and RANTES secretion by reduction of GSH with subsequent induction of I?B?-SSG and inhibition of histone H3 phosphorylation. Our findings offer new potential drug targets to reduce airway inflammation in asthma.