Abstract: Objective:To observe the effects and mechanisms of Porphyromonas gingivalis (P. gingivalis) lipopolysaccharide (LPS) on the formation of vital neutrophil extracellular traps (NETs). Methods:Neutrophils were obtained from peripheral venous blood of healthy individuals by density gradient centrifugation and primed with 25 ng/mL GM-CSF and 0.3 μg/mL P. gingivalis LPS for 35 min. Formation of vital NETs was observed by immunofluorescence staining and extracellular DNA was quantified by a microplate reader. DNA sources were explored by PCR. Quantities of extra- and intracellular P. gingivalis in neutrophils were determined to assay the bactericidal efficiency of vital NETs. Levels of reactive oxygen species (ROS) were detected by flow cytometry. Phosphorylation levels of protein kinase Raf, mitogen-activated extracellular signal-regulated kinase (MEK), and extracellular signal-regulated kinase (ERK) were explored by Western blot. Results:GM-CSF+P. gingivalis LPS stimulation led to the formation of vital NETs and the increased levels of extracellular DNA (P＜0.05), which enhanced bactericidal activity of neutrophils (P＜0.05). In this process, mitochondrial DNA was released instead of nuclear DNA. In addition，levels of ROS, p-Raf, p-MEK and p-ERK were significantly increased in the cells treated with GM-CSF+P. gingivalis LPS compared with negative group (P＜0.05). In addition, DPI, an inhibitor of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, pretreatment resulted in decreased levels of extracellular DNA and ROS (P＜0.01). Conclusions:GM-CSF+P. gingivalis LPS might contribute to the formation of vital NETs depending on the production of ROS and the phosphorylations of Raf, MEK, ERK, which might contribute to the elimination of P. gingivalis and regulate periodontal inflammatory responses.