Effect of H₂O₂ on Expression of Proinflammatory Cytokines in PDLCells

Objectives: Periodontitis is an inflammatory disease that leads to alveolar bone resorption. Interleukin (IL)-1, tumor necrosis factor (TNF), and IL-8 are proinflammatory and bone resorption-inducing cytokines. In periodontitis, periodontal tissue is exposed to reactive oxygen speices (ROS). To investigate the role of ROS in tissue destruction in periodontitis, we estimated the effect of

H₂O₂, an ROS, on the expression of IL-1, TNF, and IL-8 in human periodontal ligament (PDL) cells.

Methods: Induction of these cytokines was estimated by cytokine antibody array kit, reverse transcription–polymerase chain reaction (RT-PCR) or enzyme-linked immunosorbent assay (ELISA). Phosphorylation of c-jun NH₂-terminal kinase (JNK) by H₂O₂ was estimated by Western blotting.

Results: H₂O₂induced the production of IL-8, but did not induce the production of IL-1 and TNF. H₂O₂ increased the expression of IL-8 mRNA and the production of IL-8 in a concentration-dependent manner. Catalase, an inhibitor of H₂O₂, down-regulated the production of IL-8 induced by H₂O₂. H₂O₂ increased phosphorylation of JNK. Pretreatment with an inhibitor of JNK decreased the IL-8 production induced by H₂O₂.

Conclusion: These results indicate that H₂O₂ acts as inducer of IL-8 secretion via activation of JNK. Induction of IL-8 by H₂O₂ may involved in the pathogenesis of periodontitis.

This work was supported by the Korean Research Foundation Grant funded by the Korean Goverment (MOEHRD,Basic Research Promotion Fund)(KRF-2006-531-E00078)