Role of TLR2/NF-κB signaling pathway in aluminum-induced inflammatory response in GMI-R1 cells / 中国职业医学

ABSTRACT

{L-End}Objective To investigate the role and mechanism of Toll-like receptor 2 (TLR2)/nuclear factor-κB(NF-κB) signaling pathway in the inflammatory response induced by aluminum in the rat GMI-R1 microglia cells. {L-End}Methods GMI-R1 cells in logarithmic growth phase were randomly divided into the control group, positive control group, and low-, medium-, and high-dose groups. The cells in the three dose groups were stimulated with maltolol aluminum at concentrations of 100, 200, and 400 μmol/L, respectively. The cells in the positive control group were stimulated with lipopolysaccharide at a mass concentration of 20 mg/L, while the cells in the control group were not treated. The morphological changes of cells were observed, and the cell survival rate was evaluated by CCK-8 method after 24 hours of culture. The secretion levels of tumor necrosis factor-α (TNF-α), interleukin (IL) -12 and IL-4 were detected by enzyme-linked immunosorbent assay. The relative protein expression of TLR2, NF-κB P65, cluster of differentiation (CD) 68 and CD206 of cells was detected by Western blotting, and the expression of CD68 and CD206 of cells was detected by immunofluorescence method. {L-End}Results The results of cell morphology showed that the number of GMI-R1 cells decreased, the number of activated cells increased, the degree of cell cytoplasm filling decreased, and the cell protrusions elongated with the increase of exposure dose, showing a dose-response relationship. The cell viability of the positive control group and the medium- and high-dose groups were significantly lower than those of the control group (all P<0.05). The secretion levels of TNF-α, IL-12 and the relative expression of TLR2 and CD68 proteins increased (all P<0.05) while the secretion level of IL-4 decreased (all P<0.05) in the cells of positive control group compared with the control group. The secretion levels of TNF-α and IL-12 increased (all P<0.05) while the secretion levels of IL-4 decreased in the cells of the three doses groups (all P<0.05), compared with the control group, and all showed a dose-effect relationship. The relative expression of TLR2 protein in the cells of the three doses groups increased (all P<0.05) compared with the control group. The relative expression of NF-κB p65 and CD68 protein in the cells of the medium- and high-dose groups increased (all P<0.05), but the relative expression of CD206 protein decreased (all P<0.05) compared with the control group. The relative expression of TLR2 and NF-κB p65 protein increased (all P<0.05) while the relative expression of CD206 protein decreased (all P<0.05) in cells of the high-dose group, compared with the low- and medium-dose groups. The average fluorescence intensity of CD68 increased (all P<0.05) while the average fluorescence intensity of CD206 decreased in the cells of high-dose group and the positive control group (all P<0.05), compared with the control group. {L-End}Conclusion Aluminum participated in and promoted the inflammatory response of GMI-R1 cells through the TLR2/NF-κB signaling pathway.