Globally, acute kidney injury (AKI) is associated with significant mortality and an enormous economic burden. Whereas iron is essential for metabolically active renal cells, it has the potential to cause renal cytotoxicity by promoting Fenton chemistry-based oxidative stress involving lipid peroxidation. In addition, 1,25-dihydroxyvitamin D3 (calcitriol), the active form of vitamin D, is reported to have an antioxidative role. In this study, we intended to demonstrate the impact of vitamin D on iron-mediated oxidant stress and cytotoxicity of Vero cells exposed to iohexol, a low osmolar iodine-containing contrast media in vitro. Cultured Vero cells were pretreated with 1,25-dihydroxyvitamin D3 dissolved in absolute ethanol (0.05%, 2.0 mM) at a dose of 1 mM for 6 hours. Subsequently, iohexol was added at a concentration of 100 mg iodine per mL and incubated for 3 hours. Total cellular iron content was analysed by a flame atomic absorption spectrophotometer at 372 nm. Lipid peroxidation was determined by TBARS (thiobarbituric acid reactive species) assay. Antioxidants including total thiol content were assessed by Ellman’s method, catalase by colorimetric method, and superoxide dismutase (SOD) by nitroblue tetrazolium assay. The cells were stained with DAPI (4,6-diamidino-2-phenylindole), and the cytotoxicity was evaluated by viability assay (MTT assay). The results indicated that iohexol exposure caused a significant increase of the total iron content in Vero cells. A concomitant increase of lipid peroxidation and decrease of total thiol protein levels, catalase, and superoxide dismutase activity were observed along with decreased cell viability in comparison with the controls. Furthermore, these changes were significantly reversed when the cells were pretreated with vitamin D prior to incubation with iohexol. Our findings of this in vitro model of iohexol-induced renotoxicity lend further support to the nephrotoxic potential of iron and underpin the possible clinical utility of vitamin D for the treatment and prevention of AKI.

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骨化三醇对培养肾细胞的铁毒性及其改善作用

在全球范围内，急性肾损伤 (AKI) 与显着的死亡率和巨大的经济负担有关。尽管铁对代谢活跃的肾细胞至关重要，但它有可能通过促进基于芬顿化学的氧化应激（包括脂质过氧化）而引起肾细胞毒性。此外，据报道，维生素 D 的活性形式 1,25-二羟基维生素 D3（骨化三醇）具有抗氧化作用。在这项研究中，我们旨在证明维生素 D 对暴露于碘海醇（一种体外低渗含碘造影剂）的 Vero 细胞的铁介导的氧化应激和细胞毒性的影响. 将培养的 Vero 细胞用溶解在无水乙醇（0.05%，2.0 mM）中的 1,25-二羟基维生素 D3 以 1 mM 的剂量预处理 6 小时。随后，以每毫升 100 毫克碘的浓度加入碘海醇并孵育 3 小时。通过火焰原子吸收分光光度计在 372 nm 处分析细胞总铁含量。脂质过氧化通过TBARS（硫代巴比妥酸反应性物质）测定法测定。包括总硫醇含量在内的抗氧化剂通过 Ellman 方法、过氧化氢酶通过比色法和超氧化物歧化酶 (SOD) 通过硝基四唑鎓测定进行评估。细胞用 DAPI (4 ,6-二脒基-2-苯基吲哚），并通过活力测定（MTT测定）评估细胞毒性。结果表明，碘海醇暴露导致 Vero 细胞中总铁含量显着增加。与对照相比，观察到脂质过氧化的伴随增加和总硫醇蛋白水平、过氧化氢酶和超氧化物歧化酶活性的降低以及细胞活力的降低。此外，当细胞在与碘海醇孵育之前用维生素 D 预处理时，这些变化显着逆转。我们对碘海醇诱导的肾毒性体外模型的发现进一步支持铁的肾毒性潜力，并支持维生素 D 治疗和预防 AKI 的可能临床效用。