Toll样受体4在二氧化硅诱导巨噬细胞肿瘤坏死因子α合成中的作用

目的 探讨Toll样受体4(TLR4)在二氧化硅诱导巨噬细胞肿瘤坏死因子α(TNFα)合成过程中的介导作用.方法 将二氧化硅的粉尘悬液与人巨噬细胞株THP-1温育,收集细胞培养液,利用酶联免疫吸附(ELISA)方法测定培养液中TNFα的含量.为了解TLR4在二氧化硅诱导TNFα合成过程中的作用,用TLR4受体的中和抗体(HTA125,20 μg/ml)预处理THP-1细胞,观察该处理对二氧化硅上述作用的影响.此外,利用可表达野生型或突变型TLR4的小鼠巨噬细胞株,进一步比较二氧化硅诱导两型细胞合成TNFα水平的差异.结果 100 μg/ml二氧化硅刺激THP-1细胞4、8 h,可致细胞TNFα的释放量升高[分别为(4.71±0.84)、(6.22±0.58)pg/ml],为对照组[(3.18±0.41)pg/ml]的1.48和1.96倍,差异有统计学意义(P<0.05).用HTA125抗体预处理THP-1细胞,可致二氧化硅诱导细胞释放TNFα的量降低27%.同表达野生型TLR4的小鼠巨噬细胞相比,表达突变型TLR4细胞在二氧化硅刺激后TNFα的释放量降低30%.结论 TLR4在二氧化硅诱导TNFα合成过程中起一定的作用.

Involvement of Toll-like receptor in silica-induced tumor necrosis factor a release from human macrophage cell line

Objective To characterize the role of Toll-like receptor 4 (TLR4) in silica-induced pro-duction of tumor necrosis factor α(TNFα) from macrophage cell line. Methods The human macrophage cell line THP-1 was incubated with silica suspension. Cell media were collected and TNFα levels in the super-natants measured with ELJSA. To examine the involvement of TLR4 in silica-induced TNFα release, the neu-tralizing antibody (HTA125) against human TLR4 receptor was employed topretreat THP-1 cells prior to silica treatment. Moreover, murine macrophages expressing wild type or mutated TLR4 were also treated with silica to verify the effect of TLR4 in silica-induced TNFα release. Results Compared with the control group[(3.18± 0.41) pg/ml], the TNFα release in cells exposed to 100 μg/ml silica for 4 h and 8 h [(4.71±0.84),(6.22±0.58) pg/ml, respectively] increased 1.48 and 1.96 fold, respectively. Pretreatment of THP-1 cells with 20 μg/ml HTA 125 antibody significantly blocked silica-induced TNFα release by 27%. Furthermore, the TNFα content re-leased from cells expressing mutated TLR4 reduced by 30% in compared with that from the cells expressing wild type TLR4 after silica stimulation. Conclusion TLR4 mediates silica-induced TNFα release from macrophages.