The anti-inflammatory effect of 10-oxo-trans-11-octadecenoic acid (KetoC) on RAW 264.7 cells stimulated with Porphyromonas gingivalis lipopolysaccharide.

BACKGROUND: There is rapidly developing interest into the role of several anti-inflammatory agents to resolve inflammation in periodontal disease. A bioactive polyunsaturated fatty acid, 10-oxo-trans-11-octadecenoic acid (KetoC), is known to have various beneficial physiological effects; however, the effect of KetoC on inflammation remains unclear. Here, we investigated the effect of KetoC on RAW 264.7 cells stimulated with Porphyromonas gingivalis lipopolysaccharide, and explored the intracellular mechanism responsible for its anti-inflammatory effects. METHODS: RAW 264.7 cells were pre-treated with or without KetoC, and then stimulated with or without P. gingivalis lipopolysaccharide. Levels of tumor necrosis factor α (TNFα), interleukin (IL)-6 and IL-1ß were determined by real-time polymerase chain reaction and enzyme-linked immunosorbent assay. Specific antagonists for G protein-coupled receptor (GPR)40 and GPR120 were used to clarify the receptor for KetoC. The intracellular mechanism was investigated using western blotting analysis to separate nuclear and cytosolic NF-κB p65 protein. RESULT: KetoC (5 µmol/L) was not toxic to RAW 264.7 cells, and significantly reduced the expression of TNFα and IL-6 mRNA and protein, and IL-1ß mRNA. No protein production of IL-1ß was observed. Additionally, when bound to GPR120, KetoC trended to downregulate nuclear NF-κB p65 protein levels. However, the antagonist for GPR40 failed to diminish the action of KetoC. CONCLUSION: KetoC suppressed the proinflammatory cytokines TNFα, IL-6 and IL-1ß via NF-κB p65, by binding to its receptor GPR120. KetoC is a promising candidate in future studies as a bioactive anti-inflammatory agent in treating periodontal disease.

Natural killer T cells mediate alveolar bone resorption and a systemic inflammatory response in response to oral infection of mice with Porphyromonas gingivalis.

BACKGROUND AND OBJECTIVE: T and B cells are known to be involved in the disease process of periodontitis. However, the role of natural killer T cells in the pathogenesis of periodontitis has not been clarified. MATERIALS AND METHODS: To examine the role of these cells, C57BL/6J (wild-type), CD1d(-/-) and α-galactosylceramide (αGC)-stimulated wild-type mice were orally infected with Porphyromonas gingivalis strain W83. RESULTS: Apart from CD1d(-/-) mice, the level of alveolar bone resorption was elevated by the infection and was further accelerated in αGC-stimulated mice. The infection induced elevated levels of serum amyloid A and P. gingivalis-specific IgG in the sera, although the degree of elevation was much smaller in the CD1d(-/-) mice. Infection-induced RANKL elevation was only observed in αGC-stimulated mice. Although the cytokines produced by splenocytes were mainly T-helper 1 type in wild-type mice, those in αGC-stimulated mice were predominantly T-helper 2 type. In the liver, the infection demonstrated no effect on the gene expression for interferon-γ, interleukin-4 and RANKL except αGC-stimulated mice in which the infection upregulated the gene expressions. CONCLUSION: This study is the first to show that natural killer T cells upregulated systemic and local inflammatory responses induced by oral infection with P. gingivalis, thereby contributing to the progression of alveolar bone resorption.