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 (E_h), 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.

环境暴露于五氧化二钒（V ₂ O ₅，V ⁺⁵为其离子对应物）和成纤维细胞衰老均与肺纤维化相关，但 V ⁺⁵是否导致成纤维细胞衰老仍不清楚。我们在一项剂量反应研究中发现，2–40 μM V ⁺⁵会导致人肺成纤维细胞 (HLF) 衰老，并增加衰老相关的 β-半乳糖苷酶活性和 p16 表达，而细胞死亡发生在较高浓度（LC ₅₀ , 82 μM V ⁺⁵ )。^{值得注意的是，用荧光探针测量活性氧（ROS）产生表明ROS与V +5}依赖性衰老没有关联。预加载过氧化氢酶（聚乙烯共轭）（一种 H ₂ O ₂清除剂）并不能减轻 V ⁺⁵诱导的细胞衰老。对细胞谷胱甘肽（GSH）系统的分析表明，V ⁺⁵氧化 GSH，增加 GSH 生物合成，刺激细胞 GSH 外流并增加蛋白质 S-谷胱甘肽化，并且添加 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， V ⁺⁵处理的细胞 中存在GSSG/GSH 氧化还原电位 (E _h )、蛋白质 S-谷胱甘肽化和细胞衰老之间的强相关性 (R ²  > 0.99，p < 0.05)。对无细胞和无酶溶液的研究表明，在没有 O ₂的情况下， V ⁺⁵直接氧化 GSH，形成 V ⁺⁴和 GSSG 。对 HLF 和培养基中V ⁺⁵和 V ^{+4的分析表明，细胞内 V +5}降至 V ⁺⁴，并且细胞外培养基中快速达到稳定的 V ⁺⁴ /V ⁺⁵比率，表明持续释放V ⁺⁴并再氧化为V ⁺⁵。总之，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有关，并且在不导致细胞死亡的条件下发生。这些结果建立了一种机制，在没有高水平职业暴露和细胞毒性细胞死亡的情况下，来自食物、膳食补充剂或饮用水的环境钒可以导致或促成肺纤维化。