Effect of lipoxin A4 on lipopolysaccharide-induced activation of microglia and role of SIRT1/NF-κB signaling pathway / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the effect of lipoxin A4 on lipopolysaccharide (LPS)-induced activation of microglia and role of silent information regulator sirtuin 1 (SIRT1)/NF-κB signaling pathway.Methods:This experiment was performed in two parts.PartⅠ The well-growth BV2 microglia were divided into 4 groups ( n=30 each) using a random number table method: control group (group C), LXA4 group (group LXA4), LPS group (group LPS) and LPS+ LXA4 group (group LLI). PartⅡ The well-growth BV2 microglia were divided into 2 groups ( n=30 each) using a random number table method: LPS+ LXA4 group (group LL2) and LPS+ LXA4+ SIRT1 inhibitor EX527 group (group LLE). Cells in group C were commonly cultured without any treatment. In LXA4 group and LPS group, LXA4 (final concentration 100 nmol/L) and LPS (final concentration 100 ng/ml) were added respectively, and then the cells were incubated for 24 h. In LL1 group and LL2 group, LXA4 (final concentration 100 nmol/L) was added at 1 h before treatment with LPS, and the other treatments were similar to those previously described in LPS group. EX527 (final concentration of 5 μmol/L) was added at 30 min before treatment with LXA4, and the other treatments were similar to those previously described in LL2 group.The expression of inducible nitricoxide synthase (iNOS), CD32, arginine synthase 1 (Arg-1), CD206, interleuckin-1β (IL-1β), IL-6, tumor necrosis factor-α (TNF-α) and IL-10 mRNA was detected by real-time polymerase chain reaction. The concentrations of IL-1β, IL-6, TNF-α and IL-10 in the supernatant were measured using enzyme-linked immunosorbent assay. The content of ROS was detected by DCFH-DA. The activity of SOD was measured by WST-8 assay. The expression of NADPH oxidase 2 (NOX2), superoxide dismutase 1 (SOD1), heme oxygenase-1 (HO-1), SIRT1 and acetylated NF-κB p65 was detected by Western blot. Results:Compared with group C, the expression of iNOS, CD32, IL-1β, IL-6 and TNF-α mRNA was significantly up-regulated, the concentrations of IL-1β, IL-6 and TNF-α in the supernatant were increased ( P<0.05), no significant change was found in the expression of Arg-1, CD206 and IL-10 mRNA and IL-10 concentrations in the supernatant, the expression of NOX2 and HO-1 was up-regulated, SOD1 expression was down-regulated, the activity of SOD was decreased, the content of ROS was increased, the expression of SIRT1 was down-regulated, and the expression of acetylated NF-κB p65 was up-regulated in group LPS ( P<0.05). Compared with group LPS, the expression of iNOS, CD32, IL-1β, IL-6 and TNF-α mRNA was significantly down-regulated, the expression of Arg-1, CD206 and IL-10 mRNA was up-regulated, concentrations of IL-1β, IL-6 and TNF-α in the supernatant were decreased, the concentration of IL-10 was increased, the expression of NOX2 was down-regulated, the expression of HO-1 and SOD1 was up-regulated, the activity of SOD was increased, the content of ROS was decreased, the expression of SIRT1 was up-regulated, and the expression of acetylated NF-κB p65 was down-regulated in group LL1 ( P<0.05). Compared with group LL2, the concentrations of IL-1β, IL-6 and TNF-α in the supernatant were significantly increased, the activity of SOD was decreased, the content of ROS was increased ( P<0.05), and no significant change was found in the IL-10 concentration in the supernatant in group LLE ( P>0.05). Conclusions:LXA 4 can inhibit LPS-induced polarization of microglia to M1 phenotype, and the mechanism may be related to enhancement of SIRT1 activity and inhibition of NF-κB transcriptional activity.