In the present study, we investigated the effects of a Kampo medicine Orento (TJ-120) on the production of prostaglandin E
2 (PGE
2), interleukin (IL)-6 and IL-8 by human gingival fibroblasts (HGFs) treated with lipopolysaccharide from
Porphyromonas gingivalis (PgLPS). HGFs proliferation was dose-dependently decreased with Orento at days 3 and 7. However, treatment with PgLPS (10 ng/ml), Orento (up to 1 mg/ml) and their combinations for 24 h did not affect the viability of HGFs. Orento suppressed PgLPS-induced PGE
2 production in a dose-dependent manner but did not alter basal PGE
2 level. In contrast, Orento did not alter PgLPS-induced IL-6 and IL-8 productions. These alterations by Orento were similar to those by a mitogen-activated protein kinase kinase (MAPKK/MEK) inhibitor, PD98059. A Orento showed no effect on cyclooxygenase (COX)-1 and COX-2 activities, and increased cytoplasmic phospholipase A
2 (cPLA
2) expression and increased PgLPS-induced COX-2 expression. Orento suppressed PgLPS-induced mobility retardation of cPLA
2 band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gels, that is cPLA
2 phosphorylation and its activation, while Orento alone did not alter cPLA
2 phosphorylation. Orento suppressed PgLPS-induced extracellular signal-regulated kinase (ERK) phosphorylation, which is known to lead to ERK activation and cPLA
2 phosphorylation. These results suggest that Orento decreased PGE
2 production by inhibition of cPLA
2 phosphorylation and its activation
via inhibition of ERK phosphorylation, and also that Orento may be useful to improve gingival inflammation in periodontal disease.
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