2006 Fiscal Year Final Research Report Summary
Enhancement of virulence by mixed infection and the role of T. forsythensis
| Project/Area Number |
16592071
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Periodontal dentistry
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| Research Institution | Fukuoka Dental College |
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Principal Investigator |
YONEDA Masahiro Fukuoka Dental College, associate professor, 歯学部, 准教授 (10253460)
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| Co-Investigator(Kenkyū-buntansha) |
HIROFUJI Takao Fukuoka Dental College, professor, 歯学部, 教授 (10189897)
MAEDA Katsumasa Kyushu University, Graduate School, Faculty of Dental Science, professor, 大学院歯学研究院, 教授 (00117243)
ANAN Hisashi Fukuoka Dental College, professor, 歯学部, 教授 (80158732)
HAMACHI Takafumi Kyushu University, Kyushu University Hospital, assistant professor, 病院・講師 (80198811)
KABASHIMA Hiroaki Kyushu University, Graduate School, Faculty of Dental Science, research assistant, 大学院歯学研究院, 助教 (20214504)
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| Project Period (FY) |
2004 – 2006
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| Keywords | Porphyromonas gingivalis / Tannerella forsythia / mixed infection / growth promotion / type 2 diabetes mice / protease-deficient strains / halitosis |
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| Research Abstract |
Periodontitis is considered to be associated with mixed infection. Porphyromonas gingivalis and Tannerella forsythia are often isolated from active periodontitis sites, indicating these two bacteria have some synergistic effects.
We had previously reported that P. gingivalis and T. forsythia induced synergistic abscess formation in a murine abscess model. In vivo experiment in this study revealed sonicated extracts of T. forsythia stimulated the growth of P gingivalis in a liquid medium. It was also found that cysteine proteinases of P. gingivalis, gingipains played an important role in this growth promotion. From these results, P. gingivalis may hydrolyze. some protein components of T. forsythia, and utilizes for its growth in the mixed infection in mouse.
We also examined the host factors in microbial infection. Mutant strain of P gingivalis, which is devoid of gingipain activities, did not induce large abscess formation in a murine abscess model, but it induced large lesion in the type 2 diabetes mellitus mouse. From this result, even a less-virulent bacterium, such as gingipain-deficient mutant, was found to express pathogenecity in a host with low self defense mechanism like diabetes mellitus. We will further examine the effect of mixed infection in the type 2 diabetes mellitus mouse.
On the other hand, periodontopathic bacteria can be the cause of endo-periodontal lesion or oral malodor. We made case reports on the endo-periodontal lesion and halitosis caused by periodontopathic bacteria.
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