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[P2-3-05] Systemic administration of lipopolysaccharide derived from Escherichia coli, but not from Porphyromonas gingivalis, increases blood IL-6, TNF-alpha and IL-10 levels in mice

〇Koji Saito¹, Yuri Aono¹, Arata Watanabe², Tetsuro Kono², Tomomi Hashizume-Takizawa³, Hiroyuki Okada², Hidenobu Senpuku³, Tadashi Saigusa¹ (1. Dept Pharmacol, Nihon Univ Sch Dent at Matsudo, 2. Dept Histol, Nihon Univ Sch Dent at Matsudo, 3. Dept Microbiol Immunol, Nihon Univ Sch Dent at Matsudo)

キーワード：lipopolysaccharide、Porphyromonas gingivalis、cytokine

Porphyromonas gingivalis (Pg) appears to play a role in the progression of periodontal disease. Lipopolysaccharide (LPS), a component of the Gram-negative bacterial cell wall, stimulates Toll-like receptors (TLRs). Mice exposed to a novel environment exhibit hyperlocomotion and we have found that systemic administration of LPS derived from Escherichia coli (Ec-LPS), but not from Pg (Pg-LPS), inhibits novelty-induced locomotor activity in mice by activating TLR4. In the present study, we further analyzed the effects of Ec- and Pg-LPS on IL-6, TNF-alpha and IL-10 levels in mouse serum. This is because these cytokines may have pro-inflammatory (IL-6 and TNF-alpha) or anti-inflammatory effects that are involved in changes in locomotor responses to a novel environment. Since in vitro studies have suggested that, unlike Ec-LPS, Pg-LPS may inhibit TLR4, we carried out co-administration experiments to examine whether the effects of Ec-LPS were counteracted by Pg-LPS. Male ddY mouse (25-30 g) were used. A disposable lancet was used to take blood samples from the submandibular vein. Approximately 0.5 ml of blood was quickly collected without total anesthesia and allowed to coagulate at room temperature, then centrifuged. The separated sera was stored at -70℃ until further analysis. Bead-based Multi-Plex kits were used to determine IL-6, TNF-alpha and IL-10 levels in the samples. Each compound was given intraperitoneally 4h before collecting blood samples. Pg-LPS (840 µg/kg) failed to alter, but Ec-LPS (840 µg/kg) significantly increased, blood IL-6, TNF-alpha and IL-10 levels. The TLR4 antagonist TAK-242 (3 mg/kg), which did not affect basal IL-6, TNF-alpha or IL-10 levels, counteracted Ec-LPS-induced increases in IL-6 and IL-10, but not in TNF-alpha levels. Co-administration of Pg-LPS (500µg/kg) inhibited Ec-LPS-induced increases in IL-10, but not in IL-6 or TNF-alpha levels. The present results show in vivo that Pg- and Ec-LPS induce different effects. Thus Ec-LPS, but not Pg-LPS, increases blood IL-6, TNF-alpha and IL-10 levels. Furthermore, Pg-LPS can prevent the Ec-LPS-induced TLR4-mediated increase in blood IL-10 levels.