Background: Porphyromonas gingivalis is one of the most important periodontopathogens. It produces cysteine proteinases named gingipains. We previously examined the effect of gingipains on abscess formation in a murine model. The rgpA rgpB double and kgp mutants induced smaller abscesses than the wild type. Moreover, the rgpA rgpB kgp triple (gingipain‐null) mutant hardly showed lesion formation at all under the experimental conditions used, indicating that genes encoding gingipains are important for P. gingivalis virulence . Objectives: Here, we further report the humoral immune responses induced by P. gingivalis strains. Methods: After the lesions were apparently cured, sera were collected from the mice and immunoglobulin G (IgG) responses against the whole cell antigens of wild‐type P. gingivalis were measured . Results: Wild‐type strain was found to induce a strong antibody reaction. On the other hand, the rgpA rgpB kgp triple and kgp mutants induced significantly lower antibody responses compared to the wild type. Western blotting analysis confirmed the differences in antibody production. Next, these mice were re‐infected with wild‐type strain. Mice that were first infected with wild‐type strain showed significantly smaller lesion formation than control mice that were first infected with medium only. On the other hand, mice that were first infected with mutant strains devoid of gingipain activities did not show resistance to re‐infection and immunoglobulins directed against gingipains may be protective. Conclusions: These results suggest that gingipains play an important role in abscess formation in mice, and humoral immune responses seem to be partly responsible for the resistance to re‐infection by P. gingivalis .
ABSTRACT Bacteroides forsythus is one of the important periodontopathic bacteria, and this microorganism is known to have an S-layer outside the outer membrane. The S-layer-like antigens were recently isolated from B. forsythus , and they were found to be 270- and 230-kDa proteins in the envelope fraction. In this study, these proteins were confirmed to be specific to B. forsythus by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and they were clearly recognized by sera from patients with adult and early-onset periodontitis in Western immmunoblot analysis. We compared the immunoglobulin G (IgG) responses against the purified S-layer-like antigen by enzyme-linked immunosorbent assay. IgG responses against this antigen were low in healthy control subjects, but they were significantly higher in subjects with adult and early-onset periodontitis. Together with the fact that the IgG responses against the crude extract of B. forsythus did not rise significantly in patients with periodontitis, S-layer-like proteins are considered to be specific antigens of B. forsythus and may play an important role in the progression of periodontitis.
Objective: In order to examine if Tannerella forsythia stimulates the growth of Porphyromonas gingivalis , an in vitro study was performed. Background: P. gingivalis and T. forsythia are often isolated simultaneously from active periodontitis sites, indicating that these bacteria somewhat interact in the periodontal environment. We reported previously that mixed infection of P. gingivalis and T. forsythia synergistically induced lesion formation in a murine abscess model, and gingipains of P. gingivalis played an important role in this synergism . One of the possible mechanisms of this synergism is growth promotion by coinfection of the two bacteria. Methods: Cell extracts of T. forsythia were added to the nutrition‐decreased medium and the promotion of growth of P. gingivalis was examined. Results: Sonicated extract of T. forsythia stimulated growth of P. gingivalis in nutrition‐decreased medium in a dose‐dependent manner. Proteins appeared to be the nature of growth‐promoting factor, and the cell extract of T. forsythia had no stimulating effect on the growth of P. gingivalis strain devoid of gingipain activities. Conclusion: A product or a component of T. forsythia seemed to stimulate growth of P. gingivalis under nutrition‐limited conditions. Gingipains are considered to play an important role in digestion or uptake of this growth‐promoting factor. The interaction between T. forsythia and P. gingivalis in growth may be in part related with the synergistic virulence in a murine model.
Here, we report the management of a type I endoperiodontal lesion with furcation bone loss. A 59-year-old female attended our hospital with the chief complaint of mobility of tooth 46 and recurrent gingival swelling around the tooth. She previously received dental treatment from two dentists, but her condition did not improve. The tooth manifested the symptoms of typical periodontitis, such as gingival swelling, tooth mobility, pus discharge from the periodontal pocket and furcation bone loss. The tooth had no caries and the pulp reacted to an electric pulp test. Careful examination of the gingiva revealed traces of dental fistula. X-ray examination via a gutta percha inserted into the fistula revealed that furcation bone loss was associated with the periapical lesion. We diagnosed a type I endoperiodontal lesion, and applied Periocheck, a detection kit for peptidase-producing bacteria, to check for decreases in bacteria in the furcation and root canals. Soon after non-surgical root canal treatment, the condition of tooth 46 improved without periodontal treatment. After confirming a negative score with Periocheck, the root canal was filled. After 3 months, the furcation bone loss was on the way to recovery. These results indicate that proper diagnosis and confirmation of a decrease in root canal bacteria are important for treating endoperiodontal lesions. (J. Oral Sci. 47, 143-147, 2005)
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