Porphyromonas gingivalis (Pg), Aggregatibacter actinomycetemcomitans (Aa), Tannerella forsythia (Tf), Prevotella intermedia (Pi), and Fusobacterium nucleatum (Fn) are major periodontal pathogens. Lipopolysaccharides (LPSs) from periodontal bacteria play an important role in periodontal pathogenesis by stimulating host cells to produce inflammatory cytokines. In this study, highly pure LPSs from the five major periodontopathogens were prepared, and their monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor-α (TNF-α)-inducing activities were compared in human umbilical vein endothelial cells (HUVECs) and THP-1 macrophagic cells, respectively. In HUVECs, LPSs from Aa and Fn were potent stimulators for MCP-1 induction; however, LPSs from Pg, Pi, and Tf were much weaker MCP-1 inducers. In THP-1 cells, LPSs from Pg, Aa, and Fn were relatively strong inducers of TNF-α, whereas LPSs from Pi and Tf produced little activity. The Toll-like receptor (TLR)2/TLR4 dependency of various LPSs was also determined by measuring NF-κB reporter activity in TLR2- or TLR4-expressing 293 cells. LPSs from Aa, Fn, and Tf stimulated only TLR4; however, LPSs from Pg and Pi stimulated both TLR2 and TLR4. These results suggest that LPSs from major periodontal bacteria differ considerably in their cell-stimulating activity.

We have previously shown that the specific phosphatidylinositol 3-kinase inhibitor LY294002 (LY29), and its inactive analog LY303511 (LY30), inhibit a monocyte chemoattractant protein-1 (MCP-1) expression in human umbilical vein endothelial cells; these results suggest the potential of LY30 as an anti-inflammatory drug. In this study, we determined the effects of LY30 on the production of various inflammatory cytokines in human macrophagic THP-1 cells which were stimulated with lipopolysaccharide (LPS). LY30 selectively suppressed the mRNA expression of IL-12 p40, TNF-α, and MCP-1 without affecting the expression of IL-1α, IL-6, and IL-8. Inhibition of the production of IL-12 and TNF-α by LY30 was also demonstrated using ELISA assays. In order to elucidate the mechanisms of the action of LY30, we examined the role played by the mitogen-activated protein kinases and the key transcription factors, AP-1 and NF-κB in LPS-stimulated THP-1 cells. The results revealed that LY30 inhibited LPS-induced activation of ERK, but not p38 or JNK. Furthermore, the AP-1 DNA binding activity was suppressed by LY30 based upon the dosage, whereas NF-κB DNA binding was not affected. These results suggest that LY30 selectively inhibits cytokine production in the LPS-stimulated macrophagic THP-1 cells by downregulating the activation of ERK and AP-1.

Background: Periodontitis is an inflammatory disease characterized by the breakdown of tooth-supporting tissues, leading to tooth loss. Aggregatibacter actinomycetemcomitans are major etiologic bacterium causing aggressive periodontitis. Ursodeoxycholic acid (UDCA), a hydrophilic gall bladder acid, has been used as an effective drug for various diseases related to immunity. The aim of this study was to investigate the effect of UDCA on the inflammatory response induced by A. actinomycetemcomitans. Methods: A human acute monocytic leukemia cell line (THP-1) was differentiated to macrophage- like cells by treatment with phorbol 12-mystristate 13-acetate (PMA) and used for all experiments. The cytotoxic effect of UDCA was examined by MTT assay. THP-1 cells were pretreated with UDCA for 30 min before A. actinomycetemcomitans infection and the culture supernatant was analyzed for various cytokine production by ELISA. The effect of UDCA on bacterial growth was examined by measuring optical densities using a spectrophotometer. Results: UDCA showed no cytotoxic effect on THP-1 cells, up to 80 μM Ed highlight: Please confirm technical meaning. UDCA pretreatment inhibited the A. actinomycetemcomitansinduced IL-1β, TNF-⍺, and IL-17A secretion in a dosedependent manner. UDCA also inhibited IL-21 production at 60 μM. The production of IL-12 and IL-4 was not influenced by A. actinomycetemcomitans infection. Conclusion: These findings indicate that UDCA inhibits the production of inflammatory cytokines involved in innate and Th17 immune responses in A. actinomycetemcomitansinfected THP-1- derived macrophages, which suggests its possible use for the control of aggressive periodontitis.