Relationship between TLR4/NF-κB signaling pathway and propofol-induced inhibition of endotoxin-induced release of TNF-α from alveolar macrophages of rats

Objective To evaluate the relationship between Toll-like receptor 4(TLR4)/nuclear factor kappa B(NF-κB)signaling pathway and propofol-induced inhibition of endotoxin-induced release of tumor necrosis factor-alpha(TNF-α)from alveolar macrophages(AMs)of rats. Methods AMs extracted from adult male Sprague-Dawley rats were cultured and inoculated in 6-well plates(1×106 cells/well)and in 96-well plates(1×104 cells/well). The cells were divided into 5 groups(n=18 each)using a random number table: control group(group C), dimethyl sulfoxide group(group D), lipopolysaccharide(LPS)group(group L), propofol group(group P)and LPS plus propofol group(group L+ P). The cells were continuously cultured with phosphate buffer solution in group C. Dimethyl sulfoxide was added at the final concentration of 5 mg/ml in group D. LPS was added at the final concentration of 1 μg/ml in group L. Propofol was added at the final concentration of 25 μmol/L(4.46 μg/ml)in group P. LPS and propofol were added at the final concentration of 1 μg/ml and 25 μmol/L(4.46 μg/ml), respectively, in group L+ P.At 24 h of culture or incubation, the cell viability was detected by CCK-8 assay, the morphological changes of cells were observed using Wright′s staining, the concentration of TNF-α in the supernatant was determined by enzyme-linked immunosorbent assay, and TLR4 expression and NF-κB activities were measured by Western blot. Results Compared with group C, the cell viability and concentration of TNF-α in the supernatant were significantly increased, the expression of TLR4 was up-regulated, and the activity of NF-κB was enhanced in L and L+ P groups(P 0.05). Compared with group L, the cell viability and concentration of TNF-α in the supernatant were significantly decreased, the expression of TLR4 was down-regulated, and the activity of NF-κB was weakened(P<0.05), the morphological changes of cells were significantly attenuated, and the number of pseudopodia was reduced in group L+ P. Conclusion The mechanism by which propofol inhibits endotoxin-induced release of TNF-α from AMs is related to inhibited activation of TLR4/NF-κB signaling pathway in rats. Key words: Toll-like receptor 4; NF-kappa B; Propofol; Endotoxins; Macrophages, alveolar; Tumor necrosis factor-alpha