Effect of Selenium and Peroxynitrite on Immune Function of Immature Dendritic Cells in Humans

BACKGROUND: Selenium and peroxynitrite are known to support the growth and activity of immune cells, including T cells, B cells and macrophages. However, the role of these factors in the immune function of human immature dendritic cells (imDCs) is not clear. MATERIAL/METHODS: Monocytes from a mixture of blood samples were isolated using Ficoll density gradient centrifugation and purified with immunomagnetic beads before being induced into imDCs. Cells then either received no treatment (control group), or treatment with sodium selenite (Na(2)SeO(3), Se), 3-morpholinosydnonimine (SIN1, which decomposes into peroxynitrite), or Se+SIN1. Cell viability, migration, and antiphagocytic abilities, oxidative stress, and protein expression of extracellular signal-regulated kinases (ERK) and MMP2 were assessed using a CCK8 assay, cell counter and flow cytometry, microplate spectrophotometer, and Western blot analysis, respectively. RESULTS: Viability of imDCs was unaffected by 0.1 μmol/L of Na(2)SeO(3), although 1 mmol/L of SIN1 decreased it significantly (P<0.05). Chemotactic migration and antiphagocytic abilities were inhibited and enhanced, respectively, by treatment with Na(2)SeO(3) and SIN1 (P<0.05). Activities of superoxide dismutase and glutathione peroxidase were increased by Na(2)SeO(3) and Se+SIN1 (P<0.001). Glutathione content decreased with exposure to Na(2)SeO(3) and SIN1 (P<0.05), but increased after treatment with Se+SIN1 (P<0.05). Levels of reactive oxygen species only increased with SIN1 treatment (P<0.05). Treatment with Na(2)SeO(3), SIN1 and Se+SIN1 increased ERK phosphorylation and decreased MMP2 protein expression (P<0.05). CONCLUSIONS: Selenium and peroxynitrite can influence immune function in imDCs by regulating levels of reactive oxygen species or glutathione to activate ERK and promote antigen phagocytosis, as well as by decreasing MMP2 expression to inhibit chemotactic migration.