Dexmedetomidine inhibits the lipopolysaccharide‐stimulated inflammatory response in microglia through the pathway involving TLR4 and NF‐κB

Abstract

Abstract To investigate the effects of dexmedetomidine (DEX) on lipopolysaccharide (LPS)‐induced neuroinflammation in BV2 microglia. BV2 microglial cells were treated with various concentrations of DEX (0, 1, 10, and 100 ng/mL) for 1 hour, and then incubated in the presence or absence of 0.1 μg/mL LPS for 24 hours. Cell viability was assessed by Cell Counting Kit‐8 assays. The expression levels of IL‐1β, IL‐6, and TNF‐α were determined using enzyme‐linked immunosorbent assay (ELISA). The expressions of TLR4 and NF‐кB were detected by western blotting. Moreover, BV2 microglial cells were transfected with small interfering RNA (siRNA) specific for TLR4 (si‐TLR4 group) or negative control siRNA (si‐NC group) for 24 hours, followed by exposing to 0.1 μg/mL LPS for 24 hours. TLR4, IL‐1β, IL‐6, and TNF‐α expressions were detected by quantitative real‐time reverse transcription‐polymerase chain reaction (RT‐qPCR). There were no significant differences in cell viability with the different treatments. Compared with the control group, LPS markedly increased the release of IL‐6, TNF‐α, IL‐1β, TLR4, and NF‐κB, but these increases were significantly attenuated by pretreatment with 10 or 100 ng/mL DEX in a dose‐dependent relationship, but not with 1 ng/mL DEX. Gene expression levels of IL‐1β, IL‐6, and TNF‐α were obviously upregulated in si‐NC group and si‐TLR4 group when cells were exposed to 0.1 μg/mL LPS for 24 hours. Meanwhile, si‐TLR4 group had significantly lower IL‐1β, IL‐6, and TNF‐α expressions than si‐NC group. The anti‐inflammatory effects of DEX on LPS‐induced BV2 microglia may be mediated through pathway involving TLR4 and NF‐κB.

Keywords

• dexmedetomidine
• inflammation
• microglia
• toll‐like receptor 4