Almagor M, Kahane I, Gilon C, Yatziv S
Infect Immun. 1986 Apr;52(1):240-4. doi: 10.1128/iai.52.1.240-244.1986.
The role of the glutathione (GSH) redox cycle and vitamin E as antioxidant defense systems was studied in normal human cultured skin fibroblasts infected by virulent Mycoplasma pneumoniae. In cells infected for 20 h, catalase activity was inhibited by 75% and the intracellular GSH decreased to 32% of its normal values. GSH peroxidase and oxidized glutathione (reductase activities in the infected cells were unaffected.) GSSG glutathione in the medium of the infected cells rose in accordance with the intracellular GSH decrease. The observed elevation in GSSG/GSH ratio was attributed to the increase in intracellular H2O2 content in M. pneumoniae-infected cells due to the marked inhibition in their catalase activity. The protective effect of the GSH redox cycle in infected cells was studied by depletion of cellular GSH, prior to their infection with M. pneumoniae, using buthionine sulfoximine (BSO), a selective inhibitor of gamma-glutamyl cysteine synthetase. After 16 h of incubation with BSO, the GSH levels were reduced to 38% of their normal value and recovered to 55% during 24 h after removal of the inhibitor. BSO had no effect on GSH peroxidase and catalase activities in either infected or noninfected cells. The level of malonyldialdehyde (an indicator of membrane lipid peroxidation) in BSO-treated cells infected by M. pneumoniae was 1.8 times higher than in infected controls. Cells enriched with 0.25 and 2.25 micrograms of vitamin E per mg of protein prior to their infection by M. pneumoniae revealed the following: a lesser degree of catalase inhibition, 46 and 30%, respectively, versus 64% in infected control cells that were not supplemented with vitamin E; lower levels of malonyldialdehyde, 55 and 20% increments, respectively, versus a 140% increment in infected controls; higher residual activity of lactate dehydrogenase, 76 and 96%, respectively, versus 58% in infected controls. Our data indicate that the oxidative damage induced in M. pneumoniae-infected cells due to the increase in intracellular levels of H2O2 and O2- is limited by the host cell GSH redox cycle and by supplementation with vitamin E.
在被强毒力肺炎支原体感染的正常人培养皮肤成纤维细胞中，研究了谷胱甘肽（GSH）氧化还原循环和维生素E作为抗氧化防御系统的作用。在感染20小时的细胞中，过氧化氢酶活性被抑制75%，细胞内谷胱甘肽降至其正常值的32%。感染细胞中的谷胱甘肽过氧化物酶和氧化型谷胱甘肽（还原酶活性未受影响）。感染细胞培养基中的氧化型谷胱甘肽（GSSG）随着细胞内谷胱甘肽的减少而升高。观察到的GSSG/GSH比值升高归因于肺炎支原体感染细胞中过氧化氢酶活性的显著抑制导致细胞内过氧化氢含量增加。在肺炎支原体感染细胞之前，使用γ-谷氨酰半胱氨酸合成酶的选择性抑制剂丁硫氨酸亚砜胺（BSO）消耗细胞内谷胱甘肽，研究了GSH氧化还原循环在感染细胞中的保护作用。用BSO孵育16小时后，谷胱甘肽水平降至其正常值的38%，在去除抑制剂后的24小时内恢复到55%。BSO对感染或未感染细胞中的谷胱甘肽过氧化物酶和过氧化氢酶活性均无影响。经BSO处理的肺炎支原体感染细胞中丙二醛（膜脂质过氧化的指标）水平比感染对照组高1.8倍。在被肺炎支原体感染之前，每毫克蛋白质富含0.25微克和2.25微克维生素E的细胞显示出以下情况：过氧化氢酶抑制程度较低，分别为46%和30%，而未补充维生素E的感染对照细胞为64%；丙二醛水平较低，分别增加55%和20%，而感染对照组增加140%；乳酸脱氢酶的残留活性较高，分别为76%和96%，而感染对照组为58%。我们的数据表明，肺炎支原体感染细胞中由于细胞内过氧化氢和超氧阴离子水平增加所诱导的氧化损伤受到宿主细胞GSH氧化还原循环和补充维生素E的限制。
