Effects of co-exposure of fluorine and arsenic on protein expression of TRAF-6-mediated NF-κB1 signaling pathway in osteoblasts and osteoclast co-culture systems / 中华地方病学杂志

ABSTRACT

Objective:To investigate the effects of combined exposure of fluorine, arsenic, and fluorine-arsenic on the signaling pathway related protein expression of tumor necrosis factor receptor-related factor 6 (TRAF-6)/nuclear factor κB1(NF-κB1) in a co-culture system of mouse osteoblasts MC3T3-E1 and mouse monocyte macrophage RAW264.7.Methods:MC3T3-E1 cells were co-cultured with RAW264.7 cells after induction with osteogenic inducers. The cells were cultured for 7 days in vitro, and different doses of sodium fluoride (0.0, 0.1, 0.4, 1.6 mmol/L NaF, F), sodium arsenite (0.0, 0.5, 2.5, 12.5 μmol/L NaAsO 2, As) and different doses of fluorine and arsenic were added to the culture medium and cultured for 24 h using factorial design. The expression levels of nuclear factor κB receptor activating factor (RANK), TRAF-6, NF-κB1, T cell activating factor (NFATc1), and tartrate-resistant acid phosphatase (TRAP) protein were detected by Western blotting. Results:When fluorine was used alone, compared with the control group (F 0.0As 0.0, 1.00 ± 0.00), the expressions of RANK, NF-κB1 and TRAP proteins (1.11 ± 0.04, 1.29 ± 0.05, 1.38 ± 0.04, 1.24 ± 0.04, 1.13 ± 0.03, 1.34 ± 0.05, 1.12 ± 0.03, 1.24 ± 0.04, 1.61 ± 0.06) were increased ( P < 0.05); TRAF-6 protein expressions in F 0.1 and F 1.6 groups (1.23 ± 0.04, 1.35 ± 0.03) were increased ( P < 0.05). When arsenic was used alone, compared with the control group (F 0.0As 0.0), the expressions of RANK, TRAF-6, NF-κB1 proteins were increased in As 0.5 group ( P < 0.05), the expressions of RANK and NFATc1 proteins were reduced in As 12.5 group ( P < 0.05). When fluorine was combined with arsenic, at the same dose of fluorine, RANK protein expression in F 0.1As 0.5 group and TRAF-6 protein expression in F 0.1As 12.5, F 0.4As 0.5, F 0.4As 2.5 groups, NF-κB1 protein expression in F 0.1As 0.5 F 0.4As 2.5, F 0.4As 12.5 groups, NFATc1 protein expression in F 0.1As 0.5 and F 0.4As 0.5 groups, TRAP protein expression in F 0.1As 12.5 group were higher than the corresponding fluorine groups alone (F 0.1, F 0.4, P < 0.05), but lower than the sum of fluorine and arsenic alone. At the same dose of arsenic, RANK protein expression in F 0.1As 12.5 group, TRAF-6 protein expression in F 0.1As 12.5 and F 0.4As 2.5 groups, and NF-κB1 protein expression in F 0.1As 12.5, F 0.4As 2.5, F 0.4As 12.5, and F 1.6As 2.5 groups, TRAP protein expression in F 1.6As 2.5 and F 1.6As 12.5 groups were higher than the corresponding arsenic groups alone (As 2.5, As 12.5, P < 0.05), but lower than the sum of fluorine and arsenic alone. Fluorine had a major effect on the expressions of RANK, TRAF-6, NF-κB1, NFATc1, and TRAP proteins ( F=3.41, 341.73, 66.01, 56.49, 147.40, P < 0.05); arsenic also had a main effect on all protein indicators ( F=686.71, 174.96, 107.32, 235.80, 331.37, P < 0.05); the combined effect of fluorine and arsenic had an interaction effect on each protein indicator ( F=50.39, 234.94, 116.72, 67.77, 36.56, P < 0.05). Conclusions:In the co-culture system of MC3T3-E1 and RAW264.7 cells, fluorine can activate TRAF-6-mediated expression of NF-κB1 signaling pathway-related proteins, thereby promoting osteoclast differentiation; the effects of arsenic on the expression of related proteins are not completely consistent. The interaction of fluorine and arsenic exposure on TRAF-6-mediated expression of NF-κB1 signaling pathway-related proteins is mainly antagonistic.