铅与纳米SiO2联合染毒对A549细胞氧化损伤的影响

为了研究铅与纳米SiO2联合染毒所致的细胞损伤特征,并从氧化应激方面探讨其可能的作用机制。用铅和SiO2处理A549细胞,采用四唑盐(MTT)比色法检测细胞存活率,评价铅和SiO2联合染毒所致的细胞损伤特征;采用硫代巴比妥酸(TBA)比色法检测细胞内丙二醛(MDA)含量,评价铅与SiO2联合染毒所致细胞的氧化应激状态;检测了细胞内抗氧化物还原型谷胱甘肽(GSH)含量以及细胞内抗氧化酶的活性,以评价铅与SiO2联合染毒对细胞抗氧化系统的影响。将实验数据进行ANOVA分析。结果表明,铅、SiO2单独染毒组各指标没有明显改变;而联合染毒能造成细胞氧化损伤,表现为细胞存活率、GSH水平、超氧化物歧化酶(SOD)及谷胱甘肽过氧化物酶(GSH-Px)活性显著低于对照组及2个单独染毒组(P<0.05),细胞内MDA含量显著高于对照组及各单独染毒组(P<0.05)。可见,联合染毒可引起明显的细胞毒性,氧化损伤可能是铅与SiO联合染毒致肺细胞毒性损伤的作用机制之一。

Effects of Combined Exposure to Lead and Nano-SiO2 on the Oxidative Damage of A549 Cells

To investigate the possible mechanism and characteristics of the damage effects on A549 cells induced by lead and nano-SiO₂ from oxidative stress. A549 cells were alone or combinedly exposed to lead and nano-SiO₂. In order to investigate the possible characteristics of combined cytotoxicity of lead and SiO₂, the survival rates were detected by methyl thiazolyl tetrazolium (MTT) method. The level of malondialdehyde (MDA) was measured by 2-thiobarbituric acid (TBA) colorimetric method to assess the extent of oxidative stress. To evaluate the lead and SiO₂ jointly treated cells to the influence of the antioxidant defense system, the content of glutathione (GSH) and activities of antioxidant enzymes were detected. The results of ANOVA test showed that all indexes of single exposure group did not obviously change. However, lead and SiO₂ combined treatment can induce cell oxidative stress. After combined exposure to lead and SiO₂, cell survival rate, glutathione level, activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were decreased significantly (P<0.05); malonaldehyde concentration increased remarkably (P<0.05). Therefore, it is deduced that combined exposure produce apparent cytotoxic effects. Oxidative damage may be one possible damage mechanism of cells after combined exposure to lead and SiO₂.