Periodontopathic Bacterium Fusobacterium nucleatum Affects Matrix Metalloproteinase-9 Expression in Human Alveolar Epithelial Cells and Mouse Lung

Background/Aim: Despite evidence of an association between pulmonary diseases and periodontopathic bacteria, the molecular mechanisms remain unknown. Matrix metallo proteinase-9 (MMP9) plays important roles in pneumonia, chronic obstructive pulmonary disease, and asthma; therefore, we assessed the effects of Fusobacterium nucleatum on MMP9 expression in mouse lung and A549 human alveolar epithelial cells. Materials and Methods: Heat-killed F. nucleatum was administered to the trachea of mice or added to A549 cell cultures. MMP9 expression was determined using real-time PCR and western blotting. The involvement of mitogen-activated protein kinases (MAPKs) and nuclear factor-??B (NF-??B) in MMP9 expression was examined. Results: F. nucleatum induced expression of MMP9 in mouse lung and bronchoalveolar lavage fluid. In A549 cells, F. nucleatum induced production of MMP9 protein and mRNA in a density-dependent manner; this was inhibited by inhibitors of extracellular-regulated kinase 1/2 and NF-??B, but not of p38 and Jun N-terminal protein kinase. Conclusion: F. nucleatum may contribute to the onset of pulmonary diseases via MMP9 expression through extracellularregulated kinase 1/2 and NF-??B activation.