Analysis of immunostimulatory activity of Porphyromonas gingivalis fimbriae conferred by Toll-like receptor 2 |
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Authors: | Yukari Aoki Koichi Tabeta Fuminobu Yoshimura |
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Affiliation: | a Center for Transdisciplinary Research, Niigata University, Niigata, Japan b Laboratory of Periodontology and Immunology, Department of Oral Health and Welfare, Niigata University Faculty of Dentistry, Niigata, Japan c Department of Microbiology, School of Dentistry, Aichi-Gakuin University, Nagoya, Japan |
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Abstract: | Bacterial fimbriae are an important pathogenic factor. It has been demonstrated that fimbrial protein encoded by fimA gene (FimA fimbriae) of Porphyromonas gingivalis not only contributes to the abilities of bacterial adhesion and invasion to host cells, but also strongly stimulates host innate immune responses. However, FimA fimbriae separated from P. gingivalis ATCC 33277 using a gentle procedure showed very weak proinflammatory activity compared with previous reports. Therefore, in the present study, biological characteristics of FimA fimbriae were further analyzed in terms of proinflammatory activity in macrophages. Macrophages differentiated from THP-1 cells were stimulated with native, heat-denatured, or either proteinase- or lipoprotein lipase-treated FimA fimbriae of P. gingivalis ATCC 33277. Stimulating activities of these FimA fimbriae were evaluated by TNF-α-inducing activity in the macrophages. To clarify the mode of action of FimA fimbriae, anti-Toll-like receptor (TLR) 2 blocking antibody was added prior to stimulation. Weak stimulatory activity of native FimA fimbriae was enhanced by heat treatment and low-dose proteinase K treatment. Higher dose of proteinase K treatment abrogated this up-regulation. The activity of treated FimA fimbriae was suppressed by anti-TLR2 antibody, and more substantially by lipoprotein lipase treatment. These results suggest that lipoproteins or lipopeptides associated with FimA fimbriae could at least in part account for signaling via TLR2 and subsequent TNF-α production in macrophages. |
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Keywords: | Porphyromonas gingivalis Fimbriae Toll-like receptor Lipopeptide |
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