RESUMEN
Background/purpose: Periodontitis is a chronic infectious disease. The oxidative stress environment can cause or exacerbate the inflammation in periodontitis. Nicotinamide adenine dinucleotide phosphate oxidase (NOX) may be the most important source of reactive oxygen species (ROS) in periodontal tissues. The pathological mechanism of periodontitis may be related to the increased ROS caused by enhanced NOX activity. The purpose was to investigate the effect of tumor necrosis factor (TNF-α) on inflammatory cytokines and ROS, and the role of NOX-2 in human gingival fibroblasts (HGFs). Materials and methods: HGFs were cultured and divided into the normal control group (NC group) and the inflammatory model group (TNF-α group) induced by 10 ng/ml TNF-α. Thereafter, NOX-2 siRNA was used to knock down NOX-2 gene expression. Quantitative real-time PCR was applied to detect IL-6, MCP-1, and NOX-2 mRNA levels. The levels of IL-6 and MCP-1 protein were examined by ELISA. The level of NOX-2 was evaluated by Western blot. ROS expression was measured by the fluorescence microplate. Results: The mRNA and protein expression levels of IL-6, MCP-1, and NOX-2 were significantly increased, and the expression of ROS was significantly elevated in response to 10 ng/ml TNF-α. Compared with the si-NC group, the mRNA and protein expression levels of IL-6 and MCP-1 were significantly down-regulated and ROS expression was significantly decreased in the si-NOX2 group stimulated by 10 ng/ml TNF-α. Conclusion: TNF-α promotes the expression of NOX-2 in human gingival fibroblasts and enhances the expression of inflammatory factors and ROS in human gingival fibroblasts through the upregulation of NOX-2 partly.