PDF(Pubmed)
Abstract：
Both environmental exposure to vanadium pentoxide (V2O5, V+5 for its ionic counterparts) and fibroblast senescence are associated with pulmonary fibrosis, but whether V+5 causes fibroblast senescence remains unknown. We found in a dose-response study that 2-40 μM V+5 caused human lung fibroblasts (HLF) senescence with increased senescence-associated β-galactosidase activity and p16 expression, while cell death occurred at higher concentration (LC50, 82 μM V+5). Notably, measures of reactive oxygen species (ROS) production with fluorescence probes showed no association of ROS with V+5-dependent senescence. Preloading catalase (polyethylene-conjugated), a H2O2 scavenger, did not alleviate the cellular senescence induced by V+5. Analyses of the cellular glutathione (GSH) system showed that V+5 oxidized GSH, increased GSH biosynthesis, stimulated cellular GSH efflux and increased protein S-glutathionylation, and addition of N-acetyl cysteine inhibited V+5-elevated p16 expression, suggesting that thiol oxidation mediates V+5-caused senescence. Moreover, strong correlations between GSSG/GSH redox potential (Eh), protein S-glutathionylation, and cellular senescence (R2 > 0.99, p < 0.05) were present in V+5-treated cells. Studies with cell-free and enzyme-free solutions showed that V+5 directly oxidized GSH with formation of V+4 and GSSG in the absence of O2. Analyses of V+5 and V+4 in HLF and culture media showed that V+5 was reduced to V+4 in cells and that a stable V+4/V+5 ratio was rapidly achieved in extracellular media, indicating ongoing release of V+4 and reoxidation to V+5. Together, the results show that V+5-dependent fibroblast senescence is associated with a cellular/extracellular redox cycling mechanism involving the GSH system and occurring under conditions that do not cause cell death. These results establish a mechanism by which environmental vanadium from food, dietary supplements or drinking water, can cause or contribute to lung fibrosis in the absence of high-level occupational exposures and cytotoxic cell death.
摘要：
环境暴露于五氧化二钒（V2O5，V+5为其离子对应物）和成纤维细胞衰老与肺纤维化有关，但V+5是否会导致成纤维细胞衰老尚不清楚。我们在剂量反应研究中发现，2-40μMV5引起人肺成纤维细胞（HLF）衰老，与衰老相关的β-半乳糖苷酶活性和p16表达增加，而细胞死亡发生在较高浓度（LC50，82μMV+5）。值得注意的是,用荧光探针测量活性氧（ROS）的产生表明ROS与V5依赖性衰老无关。预加载过氧化氢酶（聚乙烯共轭），H2O2清除剂,没有减轻V+5诱导的细胞衰老。细胞谷胱甘肽（GSH）系统的分析表明，V5氧化了GSH，GSH生物合成增加，刺激细胞GSH流出和增加蛋白质S-谷胱甘肽酰化，和添加N-乙酰半胱氨酸抑制V+5-升高的p16表达，表明硫醇氧化介导V+5引起的衰老。此外，GSSG/GSH氧化还原电位(Eh)，蛋白质S-谷胱甘肽酰化，和细胞衰老(R2>0.99,p<0.05)存在于V+5处理的细胞中。对无细胞和无酶溶液的研究表明，在没有O2的情况下，V5直接氧化GSH，形成V4和GSSG。HLF和培养基中V+5和V+4的分析表明，细胞中的V+5被还原为V+4，并且在胞外培养基中迅速达到稳定的V+4/V+5比例，表明V+4的持续释放和再氧化为V+5。一起,结果表明,V+5依赖性成纤维细胞衰老与涉及GSH系统的细胞/细胞外氧化还原循环机制相关,并且发生在不引起细胞死亡的条件下。这些结果建立了一种机制，通过这种机制，环境钒从食品，膳食补充剂或饮用水，在没有高水平职业暴露和细胞毒性细胞死亡的情况下，可能导致或促成肺纤维化。
