Regulation of Cytokine-Induced iNOS Expression by a Hairpin Oligonucleotide in Murine Cerebral Endothelial Cells

Abstract

Inducible nitric oxide synthase (iNOS) is expressed in response to cytokines by a number of cell types participating in CNS inflammation, including brain cerebral endothelial cells. NF-κB, a transcription factor, mediates effector actions of pro-inflammatory cytokines. A combination of tumor necrosis factor alpha (TNF-α) and interferon gamma (IFN-γ) enhanced the expression of iNOS in murine cerebral endothelial cells (MCECs). In an attempt to modulate TNF-α+IFN-γ induced expression of iNOS in MCECs, we designed a double-strand hairpin (hp) oligonucleotide carrying the NF-κB motif. This hp oligonucleotide inhibited NF-κB binding activity and decreased both iNOS mRNA and protein expression induced by TNF-α+IFN-γ. As a control, a mutant hp oligonucleotide was without effect. The present study confirms the role of transcription factor NF-κB in iNOS expression induced by TNF-α+IFN-γ in MCECs. More importantly, it demonstrates that an appropriately designed hp oligonucleotide is an effective tool to modulate iNOS expression and may be of potential pharmacological use.