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目的 探讨抗氧化剂N-乙酰半胱氨酸(NAC)对大鼠肺泡巨噬细胞NR8383在染尘不同时间的自噬活动影响.方法 常规培养NR8383细胞,染尘3、6、12、20、24 h,并给予NAC,分别收集细胞上清液,采用双抗体夹心酶联免疫吸附法检测肿瘤坏死因子-α(TNF-α)、转化生长因子-β Ⅰ(TGF-β Ⅰ)表达水平,自噬水平检测采用蛋白免疫印迹法和细胞免疫荧光法.结果 体外巨噬细胞染尘模型最佳时间为20 h;NAC+矽尘组NR8383细胞TNF-α表达[(116.82±8.98) pg/mL]低于矽尘组[(1823.58±764.85) pg/mL](P＜0.05);NAC+矽尘组NR8383细胞TGF-β Ⅰ表达[(8.27±3.62) pg/mL]与矽尘组[(14.28±5.71) pg/mL]比较差异无统计学意义(P ＞0.05);NAC+矽尘组与矽尘组NR8383细胞LC3蛋白表达[分别为(3.52 ±0.57)、(3.84 ±0.53) pg/mL]高于对照组[(2.24 ±0.56) pg/mL];免疫荧光结果显示,矽尘组NR8383细胞在20 h荧光信号强于对照组;NAC+矽尘组NR8383细胞荧光强度与矽尘组无明显差异.结论 矽尘刺激使NR8383细胞自噬表达增强;NAC可降低细胞上清液中TNF-α分泌水平,NAC可能参与染尘肺泡巨噬细胞的炎症反应过程.“,”Objective To assess the role of N-acetyl-L-cysteine (NAC) on the expression of autophagy in rat NR8383 cells exposed to silicon dioxide (SiO2).Methods NR8383 cells were cultured routinely and exposed to SiO2 dust (50 mg/L) for 3,6,12,20,and 24 hours,respectively,and then tumor necrosis factor-α (TNF-α) and transforming growth factor-β Ⅰ (TGF-β Ⅰ) in culture superuatant were detected with double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) to determined the optimal time for following NAC treatment (10 mmol/L).Light chain 3 (LC3) level in NR8383 cells was determined with Western blot and immunofluorescence with confocal microscopy.Results The optimal exposure time to SiO2 dust was 20 hours in the rat NR8383 cell model.The TNF-α level in the silica exposure group with NAC treatment was significantly lower than that in the group without NAC treatment (116.82 ±8.98 vs.1 823.58 ± 764.85 pg/mL,P ＜ 0.05) but the level of TGF-β Ⅰ was not significantly different between the two groups (8.27 ±3.62 vs.14.28 ±5.71 pg/mL,P ＞0.05).The LC3 protein levels in both the silica exposure groups with and without NAC treatment (3.52 0.57 and 3.84 0.53 pg/mL) were higher than that in the control group (2.24 ±0.56 pg/mL).Immunofluorescence confocal microscopy analysis demonstrated that LC3 expression in NR8383 cells with silica exposure for 20 hours was stronger than that of the control group but was not different from that of the exposure group with NAC treatment.Conclusion SiO2 can enhance autophagy in rat NR8383 cells and NAC can reduce TNF-α in cell culture supematant,suggesting that NAC might be involved in the inflammatory response of the cells exposed to SiO2.