Inhibition of TNF-induced interleukin-6 gene expression by barley (Hordeum vulgare) ethanol extract in BV-2 microglia

BackgroundInflammation in the central nervous system is closely associated with pathological neurodegenerative diseases as well as psychiatric disorders. Prolonged activation of microglia can produce many inflammatory mediators, which may result in pathological neurotoxic side effects. Interleukin (IL)-6 serves as a hallmark of the injured brain.ObjectiveWhole grains are known to contain many bioactive components. However, little information is available about anti-neuroinflammatory effects of grains in the CNS. This study aims to investigate the effect of Hordeum vulgare ethanol extract (HVE) on the suppression of IL-6 expression in BV2 microglia.MethodsInhibitory effects of HVE on IL-6 expression were analyzed by immunoblot anaysis, immunofluoresce microscopic analysis, reverse transcription-polymerase chain reaction, and luciferase promoter reporter assay.ResultsHVE inhibited TNF-induced phosphorylation of IKK/, IB, and p65/RelA NF-B. TNF-induced IL-6 mRNA expression and promoter activity were reduced by HVE. Point mutation of NF-B-binding site within the IL-6 gene promoter abolished TNF-induced reporter activity, whereas exogenous expression of p65 NF-B enhanced IL-6 promoter activity.ConclusionNF-B-binding site within the IL-6 promoter region is a HVE target element involved in the inhibition of TNF-induced IL-6 gene transcription. HVE inhibits TNF-induced IL-6 expression via suppression of NF-B signaling in BV2 microglial cells.