Poster session

[P3-2-32] The relationship between Porphyromonas gingivalis gingipains-induced phospholipase C activation and periodontal inflammation

〇Masaaki Nakayama^1,2, Mariko Naito³, Koji Nakayama³, Naoya Ohara^1,2 (1. Dept Oral Microbiol, Okayama Univ Grad Sch Med Dent Pharm Sci , 2. Adv Res Ctr Oral Craniofacial Sci, Okayama Univ Grad Sch Med Dent Pharm Sci , 3. Dept Microbiol Oral Infect, Nagasaki Univ Grad Sch Biomed Sci)

Keywords:Porphyromonas gingivalis、inflammation、phospholipase

Porphyromonas gingivalis (Pg) is an oral bacterium involved in chronic periodontitis. In periodontitis, COX-2 expression and PGE2 production are observed. In monocytic cells with Pg infection, we indicated that gingipains from Pg causes COX-2 expression and PGE2 production and that intracellular calcium influx from extracellular fluid is required for these events. In this study, we show the involvement of phospholipase C (PLC) in COX-2 expression and PGE2 production by gingipains in the monocytic cell line THP-1. We studied the involvement of PLC in gingipains-induced COX-2 expression and PGE2 production and also investigated its involvement of two pathways, ERK and IKK, which are upstream factors of gingipains-induced COX-2 expression, by using the PLC inhibitor U73122 and its negative compound U73343. The results showed that COX-2 expression and PGE2 production by Pg infection were reduced in a concentration-dependent manner by U73122, while U73343 had little inhibitory effect on these events. Activation of ERK and IKK by Pg infection was suppressed by U73122 compared to U73122. In addition, ERK-regulated c-Fos and c-Jun expression and phosphorylation were also suppressed by U73122. Collectively, we found that PLC activation is required for COX-2 expression and PGE2 production by gingipains in Pg infection, potentially involed in chronic inflammation of periodontal tissues.