Selenium promotes metabolic conversion of T-2 toxin to HT-2 toxin in cultured human chondrocytes

To explore the metabolism of T-2 toxin in human chondrocytes (HCs) and determine the impact of selenium supplementation. For determination of cytotoxicity using the MTT assay, optical density values were read with an automatic enzyme-linked immunosorbent assay reader at 510 nm. Cell survival was calculated and the cytotoxicity estimated. To identify the metabolites of T-2 toxin, the medium supernatants and C28/I2 cells were analyzed by high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) separately. For HPLC-MS/MS, the mobile phase A was water and phase B was 98% methanol. The gradient for the elution was: 0-0.5 min, 50% of B; 0.5-2.0 min, 100% of B; 2.0-3.5 min, 100% of B; 3.6-6 min, 50% of B. T-2 toxin increased the toxicity to C28/I2 cells significantly in a dose- and time-dependent manner (viability range 91.5-22.0%). Supplementation with selenium (100 ng/mL) could increase the cell viability after the 24 h incubation. The concentration of T-2 toxin in the cell medium decreased from 20 to 6.67 ± 1.02 ng/mL, and the concentration of HT-2 toxin increased from 0 to 6.88 ± 1.23 ng/mL during the 48 h incubation, whereas the relative concentration of T-2 toxin in cells increased from 0 to 12.80 ± 1.84 ng/g. Supplementary selenium in the HCs cultures reduced the cytotoxicity induced by T-2 toxin significantly, and was associated with rapid conversion of T-2 toxin in the culture medium to HT-2 toxin. T-2 toxin was more toxic to HCs than HT-2 toxin at equivalent concentrations. HT-2 toxin was a detectable metabolite of T-2 toxin in cultured HCs, and selenium enhanced the metabolic conversion of T-2 toxin, reducing its cytotoxicity to HCs.