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目的探讨肿瘤坏死因子-α(TNF-α)对泡沫细胞胆固醇流出途径的影响及可能作用机制。方法采用人组织瘤细胞-1(THP-1)细胞诱导分化形成的泡沫细胞,测定 TNF-α与细胞胆固醇流出的时间、浓度关系。然后给予饱和浓度的 TNF-α刺激,随机将泡沫细胞分成对照组、TNF-α组、对甲苯磺酰-L-苯丙氨酸甲基甲酮(N-α-tosyl-L-phenylalanine chloromethy ketone,TPCK)组及TPCK+TNF-α组,以 RT-PCR 法、Western blot 法测定细胞 ATP 结合盒转运子 A1(ABCA1)的表达。结果 TNF-α抑制细胞胆固醇流出呈时间、浓度效应,在10.0ng/ml 时,TNF-α抑制胆固醇流出达到饱和效应。10.0 ng/ml TNF-α刺激后以时间依赖方式下调 ABCA1表达。TPCK 预孵育后可部分逆转 TNF-α对 ABCA1表达的下调。结论炎症因子 TNF-α可通过抑制 ABCA1的表达而减少细胞胆固醇的流出,核因子_KB(NF-_KB)激活抑制剂 TPCK 可逆转 TNF-α的上述影响,提示 TNF-α抑制 ABCA1表达与 NF-_KB 激活有关。TNF-α/NF-_KB 信号途径可抑制泡沫细胞的胆固醇流出,从而加重细胞内胆固醇的蓄积。
Objective To investigate the effect of tumor necrosis factor-α (TNF-α) on the cholesterol efflux pathway in foam cells and its possible mechanism. Methods Foam cells induced by human tissue tumor cell-1 (THP-1) were used to determine the relationship between TNF-α and the time and concentration of cellular cholesterol efflux. Then, the cells were randomly divided into control group, TNF-α group, N-α-tosyl-L-phenylalanine chloromethy ketone , TPCK) group and TPCK + TNF-α group. The expression of ATP-binding cassette transporter A1 (ABCA1) was detected by RT-PCR and Western blot. Results TNF-α inhibited the efflux of cellular cholesterol in a time and concentration-dependent manner. At 10.0 ng / ml, TNF-α inhibited the efflux of cholesterol and achieved a saturation effect. After stimulation with 10.0 ng / ml TNF-α, ABCA1 expression was down-regulated in a time-dependent manner. Pretreatment with TPCK partially reversed the down-regulation of ABCA1 expression by TNF-α. Conclusion The inflammatory cytokine TNF-α can inhibit the efflux of cellular cholesterol by inhibiting the expression of ABCA1. TPCK, an inhibitor of nuclear factor-κB (NF-κB) activation, reverses the above effects of TNF-α, suggesting that TNF-α inhibits the expression of ABCA1 and NF -_KB Activation related. The TNF-alpha / NF-_KB signaling pathway inhibits the efflux of cholesterol from foam cells, thereby exacerbating the accumulation of intracellular cholesterol.