Immune cytotoxic effect of trichloroethylene in Jurkat T cells / 中国职业医学

OBJECTIVE: To explore the immune cytotoxic effect and the maximum non-effect dose of trichloroethylene( TCE) on Jurkat T cells in vitro. METHODS: i) Naive and activated Jurkat T cells were treated with different concentrations of TCE( 0. 10, 0. 50, 1. 00, 2. 00, 5. 00, 10. 00 mmol / L). Phorbol-12-myristate-13-acetate and ionomycin were used as agonist. No TCE was used in the control group and dimethyl sulfoxide( DMSO) was used as the solvent group. The morphology of Jurkat T cells was observed using a light microscope and the survival rate of Jurkat T cells was investigated using CCK-8 essay after cells were cultured for 24,48 and 72 hours. ii) Nave and activated Jurkat T cells were treated with different concentrations of TCE( 0. 00,0. 02,0. 20,2. 00 mmol / L). The apoptosis of cells was detected using flow cytometry and the level of interleukin-2( IL-2) in supernatant was detected using enzyme linked immunosorbent assay after cells were cultured for 24,48 and 72 hours. RESULTS: i) Cytotoxic effect was observed after cells were exposed to 10. 00 mmol / L TCE for 24 hours. Cells dispersed,cell volume diminished,cell membrane ruptured,cytoplasm condensed and increased outflow of intercellular organelles. The effect of interaction between exposure dose and exposure time was statistically significant on cell survival rate( P < 0. 01). Compared with the control and DMSO groups at the same time points,there were no significant differences in the 0. 10,0. 50,1. 00 and 2. 00 mmol / L TCE treatment groups in cell survival rates in three different time points( P > 0. 05),while the cell survival rates of 5. 00 and 10. 00 mmol / L TCE treatment groups were significantly decreased( P < 0. 01). ii) When TCE concentration was 0. 00-2. 00 mmol / L,there were no significant differences in the main effect of exposure dose and interactions of between exposure dose and cell type or exposure time on cell apoptosis rate( P > 0. 05). Compared with the same time points and groups of naive Jurkat T cells,the levels of IL-2 of activated Jurkat T cells were significantly increased( P < 0. 01). In the three different time points,the level of IL-2 of activated Jurkat T cells increased in accordance with the TCE exposure dose,showing a dose-effect relationship( P < 0. 01). The level of IL-2 of activated Jurkat T cells increased in accordance with TCE exposure time,showing a time-effect relationship( P < 0. 01). CONCLUSION:s TCE at the level of 2. 00 mmol / L had no observed effect in Jurkat T cells. High doses of TCE( ≥5. 00 mmol / L) showed cytotoxic damages to naive and activated Jurkat T cells and low doses of TCE( ≤2. 00 mmol / L) could stimulate activated Jurkat T cells secrete IL-2 in a dosedependent and time-dependent manner.

Antioxidant Potential of Polyphenol Rich Extract from Hibiscus sabdariffa.

Aims: Hibiscus sabdariffa is a medicinal plant species that is consumed for its health benefits in Africa, therefore this study investigated the antioxidant properties of Hibiscus polyphenolic rich extract (HPE), prepared from Hibiscus sabdariffa. Place and Duration of Study: School of Biomolecular Sciences, Liverpool John Moores University, Byrom Street, Liverpool, United Kingdom, between June 2009 and December 2010. Methodology: The antioxidant assays evaluated the scavenging abilities of HPE: Firstly against superoxide ions generated during the xanthine oxidase mediated breakdown of xanthine to uric acid. Secondly against ABTS (2,2-azino-bis-(3-ethylbenzthiazoline 6-sulfonic acid)) radical cation generated by filtering a solution of ABTS through manganese dioxide powder and potassium persulphate. Finally metal chelation ability of HPE against Iron ions (Fe2+) induced oxidative damage in cultured Jurkat-T cells was also assessed. Results: The results showed that 1.0% and 2.5% (v/v) diethyl ether extract of HPE significantly inhibited superoxide ions by 42.35 and 100.00% respectively. The extract also inhibited uric acid production, which suggest that components of HPE inhibit xanthine oxidase activity. In addition, it was found that HPE scavenge ABTS radical cations in dose dependent manner. HPE inhibited Fe2+-mediated lipid peroxidation in cultured Jurkat-T cells supplemented with 0.5 mg/ml and 1.0 mg/ml of HPE by 19.67% and 31.69% respectively, metal chelation ability was identified as a potential mechanism behind this observed reduction. Conclusions: HPE is rich in different phenolic compounds; therefore strong antioxidant potential of HPE observed in this study may be related to their polyphenolic constituents. This study demonstrated that Hibiscus sabdariffa is an efficient antioxidant plant species in vitro and may be beneficial in reducing oxidative damage to lipid and thus prevent or reduce the development and progression of free radical mediated diseases.

Mizoribine-mediated Apoptosis Signaling in Jurkat T Cells

PURPOSE: Mizoribine (MZR), an inhibitor of Inosine monophosphate (IMP) dehydrogenase which depletes cellular GTP, is clinically used as an immunosuppressive drug. This study was designed to evaluate the mechanism by which MZR exerts the cytotoxic effect on Jurkat T cells. METHODS: Jurkat T cell is a human T lymphocytic cell line. It was obtained from the Korean Type Culture Collection. Cell viability was measured by the MTT assay and flow cytometry. Caspase activity assay, Western blotting, 2-D PAGE, and mitochondrial membrane potential were detected using biochemical analysis. Morphologic finding was observed by Hoechst staining. RESULTS: The data demonstrated that the treatment of MZR decreased cell viability in a dose- and time-dependent manner. MZR-induced cell death was confirmed as apoptosis, which was characterized by chromatin condensation and H2AX phosphorylation. MZR increased the catalytic activity of caspase-3 protease, -8 protease and -9 proteases. The activation of caspase-3 protease was further confirmed by the degradation of polymerase (PARP), a substrate of caspase-3 protease by MZR in Jurkat T cells. Furthermore, MZR induced the changes of the mitochondrial transmembrane potential (MTP) and the cytosolic release of cytochrome c from the mitochondria. In addition, MZR induced the decrease of Bcl-X(L) expression whereas the increase of Bcl-X(S), Bak and Bim expression. Guanosine markedly inhibited cell viability and apoptosis through consistent suppression of the activity of caspase-8 protease, an upstream caspase among the caspase family, H2AX phosphorylation and PARP cleavage in MZR-treated cells. Also, I have screened the expression profile of proteins in the Jurkat T cells by using two-dimensional (2-D) gel electrophoresis. Among 300 spots resolved in the 2-D gels, the comparison of the control versus apoptotic cells revealed that the signal intensity of 10 spots was decreased and 5 spots was increased. CONCLUSION: The results suggest that MZR functions as an inhibitor of IMP dehydrogenase in apoptosis of Jurkat T cells via activation of intrinsic caspase cascades as well as mitochondrial dysfunction.

Mizoribine-mediated Apoptosis Signaling in Jurkat T Cells

PURPOSE: Mizoribine (MZR), an inhibitor of Inosine monophosphate (IMP) dehydrogenase which depletes cellular GTP, is clinically used as an immunosuppressive drug. This study was designed to evaluate the mechanism by which MZR exerts the cytotoxic effect on Jurkat T cells. METHODS: Jurkat T cell is a human T lymphocytic cell line. It was obtained from the Korean Type Culture Collection. Cell viability was measured by the MTT assay and flow cytometry. Caspase activity assay, Western blotting, 2-D PAGE, and mitochondrial membrane potential were detected using biochemical analysis. Morphologic finding was observed by Hoechst staining. RESULTS: The data demonstrated that the treatment of MZR decreased cell viability in a dose- and time-dependent manner. MZR-induced cell death was confirmed as apoptosis, which was characterized by chromatin condensation and H2AX phosphorylation. MZR increased the catalytic activity of caspase-3 protease, -8 protease and -9 proteases. The activation of caspase-3 protease was further confirmed by the degradation of polymerase (PARP), a substrate of caspase-3 protease by MZR in Jurkat T cells. Furthermore, MZR induced the changes of the mitochondrial transmembrane potential (MTP) and the cytosolic release of cytochrome c from the mitochondria. In addition, MZR induced the decrease of Bcl-X(L) expression whereas the increase of Bcl-X(S), Bak and Bim expression. Guanosine markedly inhibited cell viability and apoptosis through consistent suppression of the activity of caspase-8 protease, an upstream caspase among the caspase family, H2AX phosphorylation and PARP cleavage in MZR-treated cells. Also, I have screened the expression profile of proteins in the Jurkat T cells by using two-dimensional (2-D) gel electrophoresis. Among 300 spots resolved in the 2-D gels, the comparison of the control versus apoptotic cells revealed that the signal intensity of 10 spots was decreased and 5 spots was increased. CONCLUSION: The results suggest that MZR functions as an inhibitor of IMP dehydrogenase in apoptosis of Jurkat T cells via activation of intrinsic caspase cascades as well as mitochondrial dysfunction.