LAUSR

Purpose Many studies have shown the importance of keeping oral health to prevent against various diseases. Neutrophils (PMNs) play a very important role to keep oral health by its bactericidal activity such as reactive oxygen species (ROS) production and phagocytosis. We investigated the effects of lysed and heat-treated Enterococcus faecalis FK-23 (LFK) on ROS production and phagocytosis of human PMNs and its mechanism. Method I. PMNs (1×106 cells/ml) isolated from peripheral blood were stimulated with water-soluble LFK (5 mg/ml) and/or phorbol 12-myristate 13-acetate (PMA). Then, ROS production was measured using MCLA-dependent chemiluminescence. II. PMNs (1×106 cells/ml) were incubated for 1 h at 37 °C with/without LFK. Then, carboxylate-modified fluorescent beads were added to PMNs suspension and incubated for 30 min at 37 °C. After that, phagocytosis was measured by flow cytometry. Results LFK transiently increased ROS production from PMNs without change in total amounts. This effect was decreased by some inhibitors of mitochondrial complex. Thus, LFK might increase the reactivity of PMNs by enhancing mitochondrial functional ability or phagocytosis ability. These results suggest LFK may increase bactericidal activity of human PMNs to improve oral health.