Comparative effect of selenium and glycine on hydrogen peroxide-induced cell death and activation of macrophage U937 cells

The effects of selenium and glycine (either separately or in combination) on hydrogen peroxide-induced cell death on U937 cells and activation of U937-derived macrophages were investigated. In the first instance, U937 cells were incubated with or without selenium (Se) or glycine (GLY) or both (Se + GLY) for 24 h before exposure to hydrogen peroxide. Control cells were not incubated with Se, GLY or exposed to hydrogen peroxide. Cell viability was later assessed via trypan blue and MTT assays. For the other experiment, U937 cells were transformed to the macrophage form using phorbol 12-myristate 13-acetate before incubating with or without Se, GLY, Se + GLY. Contents were subsequently exposed to hydrogen peroxide and 24 h later assessed for the production of TNF-α, IL-1, IL-6 and the expression of iNOS and NF-κB. The results revealed that hydrogen peroxide caused significant cell death which was ameliorated by both Se and GLY. Pre-incubation of the cells with both Se and GLY did not significantly enhance cell numbers compared to GLY (p > 0.05). On the other hand, Se and GLY reduced hydrogen peroxide-mediated production of TNF-α, IL-1, IL-6 and expression of iNOS and NF-κB. Incubating the U937-derived macrophages with Se + GLY significantly ameliorated hydrogen peroxide-mediated activation of macrophages when compared to pre-treatments with Se or GLY (p < 0.05). The findings demonstrate that both Se and GLY reduced hydrogen peroxide-induced alterations in U937 cells and U937-derived macrophages. Implications of the findings are discussed.