Lipid peroxidation caused by oxygen radicals from Fusobacterium-stimulatedneutrophils as a possible model for the emergence of periodontitis

OBJECTIVE: The possible contribution of bacteria and polymorphonuclear neut rophils (PMN) to the disease process of periodontitis was evaluated, DESIGN: Fusobacterium nucleatum has been associated with chronic adult peri odontitis. Intracellular production and extracellular release of reactive o xygen species (ROS) by PMN stimulated by fusobacteria were evaluated, To es timate the potential extracellular damage that might be caused by the ROS, the lipid peroxidation (LPO) of an exogenous phospholipid, Intralipid, was assayed. METHODS: The ROS production of PMN was studied by the nitroblue tetrazolium and chemiluminescence tests. The levels of malonaldehyde (MDA) and 4-hydro xyalkenals were used to indicate LPO, RESULTS: Fusobacterium nucleatum strains stimulated neutrophils to produce a large amount of ROS, independently of plasma complement factors. The two strains tested induced considerable intracellular, but no extracellular che miluminescence responses during the first hour, indicating that ROS were re leased into phagosomes. However an incubation period of 4 h, in the presenc e of the extracellular lipid resulted in a high degree of LPO, presumably c aused by ROS release from the Fusobacterium-stimulated PMN, ROS production and lipid peroxidation could be counteracted by vitamin E, CONCLUSION: In periodontitis local bacteria might stimulate PMN to release ROS, which cause inflammation and destruction.